Research Article Neural Mechanisms That Underlie Angina...

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Hindawi Publishing Corporation ISRN Pain Volume 2013, Article ID 671503, 10 pages http://dx.doi.org/10.1155/2013/671503 Research Article Neural Mechanisms That Underlie Angina-Induced Referred Pain in the Trigeminal Nerve Territory: A c-Fos Study in Rats Bunsho Hayashi, 1 Masako Maeda, 1 Masayoshi Tsuruoka, 1,2 and Tomio Inoue 1 1 Department of Physiology, Showa University School of Dentistry, 1-5-8 Hatanodai, Shinagawa-ku, Tokyo 142-8555, Japan 2 Department of Physical erapy, Teikyo Heisei University Faculty of Community Health Care, 4-1 Uruido Minami, Ichihara, Chiba 290-0193, Japan Correspondence should be addressed to Masayoshi Tsuruoka; [email protected] Received 31 May 2013; Accepted 8 July 2013 Academic Editors: C. M. Cend´ an, M. I. D´ ıaz-Reval, C. Forster, C.-L. Hsieh, and C. Laurido Copyright © 2013 Bunsho Hayashi et al. is is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. e present study was designed to determine whether the trigeminal sensory nuclear complex (TSNC) is involved in angina- induced referred pain in the trigeminal nerve territory and to identify the peripheral nerve conducting nociceptive signals that are input into the TSNC. Following application of the pain producing substance (PPS) infusion, the number of Fos-labeled cells increased significantly in the subnucleus caudalis (Sp5C) compared with other nuclei in the TSNC. e Fos-labeled cells in the Sp5C disappeared when the leſt and right cervical vagus nerves were sectioned. Lesion of the C1-C2 spinal segments did not reduce the number of Fos-labeled cells. ese results suggest that the nociceptive signals that conduct vagal afferent fibers from the cardiac region are input into the Sp5C and then projected to the thalamus. 1. Introduction Angina pectoris has been recognized as the cause of a variety of cardiac symptoms, including chest pain and pain that may radiate either to arm or to the neck and jaw. Foreman and colleagues anesthetized a primate and recorded the responses from the spinothalamic tract (STT) cells in the T1–T5 and C5-C6 segments of the animal’s spinal cord following either occlusion of the coronary artery or the injection of algesic chemicals into the pericardial sac. e authors also found a convergence of visceral and somatic input to the chest and upper arm [1]. eir findings were consistent with the observation that referred pain associated with an attack of angina pectoris commonly occurs in proximal somatic fields. e referred pain is explained by the convergence of visceral and somatic inputs to the same dorsal horn neuron in the nociceptive ascending pathway [2]. It is well known that angina pectoris induces toothache or neck and jaw pain. e dental literature has described the presence of toothaches attributed to angina attacks and coronary artery disease [3]. us, referral to the somatic structures in the territory of the trigeminal nerve is one of the characteristics of anginal pain, and the neural mechanisms of this pain are of particular interest because such mechanisms appear to be due to a convergence of trigeminal and spinal inputs in either the spinal cord or the trigeminal sensory nucleus. Several lines of electrophysiological studies have demonstrated that an injection of algesic chemicals into the pericardial sac results in increased activity in C1-C2 STT cells [47]. is finding suggests that angina-induced referred pain in the trigeminal nerve territory is attributed to the convergence of both inputs from the trigeminal nerve territory and inputs from the cardiac region to C1-C2 STT cells because it is known that these cells receive converging somatic information from the neck and jaw regions [8]. However, angina-induced referred pain in the trigeminal nerve territory induced by the convergence of both inputs from the cardiac region and inputs from the neck and jaw regions to C1-C2 STT cells was not found in clinical or experimental observations. e trigeminal sensory nuclear complex (TSNC) is one of the components of the ascending sensory pathway that

Transcript of Research Article Neural Mechanisms That Underlie Angina...

Page 1: Research Article Neural Mechanisms That Underlie Angina ...downloads.hindawi.com/archive/2013/671503.pdf · angina-induced referred pain. It is of particular interest to examine such

Hindawi Publishing CorporationISRN PainVolume 2013 Article ID 671503 10 pageshttpdxdoiorg1011552013671503

Research ArticleNeural Mechanisms That Underlie Angina-Induced ReferredPain in the Trigeminal Nerve Territory A c-Fos Study in Rats

Bunsho Hayashi1 Masako Maeda1 Masayoshi Tsuruoka12 and Tomio Inoue1

1 Department of Physiology Showa University School of Dentistry 1-5-8 Hatanodai Shinagawa-ku Tokyo 142-8555 Japan2Department of Physical Therapy Teikyo Heisei University Faculty of Community Health Care 4-1 Uruido MinamiIchihara Chiba 290-0193 Japan

Correspondence should be addressed to Masayoshi Tsuruoka mtsuruokathuacjp

Received 31 May 2013 Accepted 8 July 2013

Academic Editors C M Cendan M I Dıaz-Reval C Forster C-L Hsieh and C Laurido

Copyright copy 2013 Bunsho Hayashi et alThis is an open access article distributed under theCreativeCommonsAttribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

The present study was designed to determine whether the trigeminal sensory nuclear complex (TSNC) is involved in angina-induced referred pain in the trigeminal nerve territory and to identify the peripheral nerve conducting nociceptive signals thatare input into the TSNC Following application of the pain producing substance (PPS) infusion the number of Fos-labeled cellsincreased significantly in the subnucleus caudalis (Sp5C) compared with other nuclei in the TSNC The Fos-labeled cells in theSp5C disappeared when the left and right cervical vagus nerves were sectioned Lesion of the C1-C2 spinal segments did not reducethe number of Fos-labeled cellsThese results suggest that the nociceptive signals that conduct vagal afferent fibers from the cardiacregion are input into the Sp5C and then projected to the thalamus

1 Introduction

Angina pectoris has been recognized as the cause of a varietyof cardiac symptoms including chest pain and pain that mayradiate either to arm or to the neck and jaw Foreman andcolleagues anesthetized a primate and recorded the responsesfrom the spinothalamic tract (STT) cells in the T1ndashT5 andC5-C6 segments of the animalrsquos spinal cord following eitherocclusion of the coronary artery or the injection of algesicchemicals into the pericardial sac The authors also founda convergence of visceral and somatic input to the chestand upper arm [1] Their findings were consistent with theobservation that referred pain associated with an attack ofangina pectoris commonly occurs in proximal somatic fieldsThe referred pain is explained by the convergence of visceraland somatic inputs to the same dorsal horn neuron in thenociceptive ascending pathway [2]

It is well known that angina pectoris induces toothacheor neck and jaw pain The dental literature has describedthe presence of toothaches attributed to angina attacks andcoronary artery disease [3] Thus referral to the somatic

structures in the territory of the trigeminal nerve is one of thecharacteristics of anginal pain and the neural mechanisms ofthis pain are of particular interest because such mechanismsappear to be due to a convergence of trigeminal and spinalinputs in either the spinal cord or the trigeminal sensorynucleus Several lines of electrophysiological studies havedemonstrated that an injection of algesic chemicals intothe pericardial sac results in increased activity in C1-C2STT cells [4ndash7] This finding suggests that angina-inducedreferred pain in the trigeminal nerve territory is attributedto the convergence of both inputs from the trigeminal nerveterritory and inputs from the cardiac region to C1-C2 STTcells because it is known that these cells receive convergingsomatic information from the neck and jaw regions [8]However angina-induced referred pain in the trigeminalnerve territory induced by the convergence of both inputsfrom the cardiac region and inputs from the neck and jawregions to C1-C2 STT cells was not found in clinical orexperimental observations

The trigeminal sensory nuclear complex (TSNC) is oneof the components of the ascending sensory pathway that

2 ISRN Pain

transmits sensory signals from the orofacial region to thehigher centers of the brain [9] Therefore this complex maybe considered to a candidate for the relay nuclei that transmitsangina-induced referred pain It is of particular interest toexamine such a possibility because the mechanisms appearto be a convergence of trigeminal and spinal inputs in theTSNC One of the objectives of the present study was todetermine whether the TSNC is involved in the ascendingsensory pathway that transmits nociceptive signals from thecardiac region to the thalamus in the brain

During the twentieth century it was believed that noci-ceptive information from the cardiac region was input to thethoracic segments of the spinal cord via the cardiac sym-pathetic nerve while the vagal afferent fibers were thoughtto transmit innocuous cardiac sensory information [10ndash13]Several morphological and electrophysiological studies fromthe late 1990s showed that vagal afferent fibers and the nucleustractus solitarius play an important role in angina-relatedreferred pain in the trigeminal nerve territory [4 5 7 14]This finding is consistent with clinical observations thatneck and jaw pain continues or develops after the use of asympathectomy to relieve anginal pain [15 16] The secondaim of the present study was to identify the peripheral nervethat conducts the nociceptive signals that are input into theTSNC

2 Materials and Methods

All of the experimental protocols used in the present studywere approved by the Institutional Animal Care and UseCommittee of Showa University and were in accordance withthe guideline of the International Association for the Study ofPain [17] For example the number of animals was kept to aminimum to minimize the animalrsquos discomfort

21 Animals The experiments were performed on maleWistar rats weighing 400ndash550 g (119899 = 30 Charles RiverTokyo) The animals were housed in groups of 3-4 in a cagecontaining sawdust bedding and were granted free accessto rat chow and water The laboratory was equipped with a12 h12 h (8 am8 pm) light-dark cycle Room temperatureand humidity were maintained at 235∘C and 60 respec-tively

22 Surgical Preparation Theanimalswere anesthetizedwithurethane (12 gkg ip) After a tracheotomy was performedthe animals were artificially ventilated to maintain an end-tidal CO

2level between 35 and 45 An adequate level

of anesthesia was determined by the absence of pupillarydilation or increases in heart rate Under the anestheticcondition in the present study no spontaneous movementwas observed in the animals throughout the experimentsMean blood pressure was measured directly via a catheterthat was inserted into the right femoral artery Heart rate wasmonitored by electrocardiogram The mean blood pressureand the electrocardiogram were fed into an AD converter(CED 1401 +) andwere recorded using Spike2 software (CEDCambridge UK) The animalrsquos core body temperature was

regulated at approximately 375∘C using a thermostaticallycontrolled heating blanket

23 Pain Producing Substance (PPS) The cardiac nociceptivereceptors were stimulated chemically using a modified painproducing chemical mixture that was designed to excite boththe vagal and sympathetic afferent endings [18] The PPSsolution contained bradykinin (10minus5M) serotonin (10minus5M)prostaglandin E2 (10minus5M) histamine (10minus5M) and adeno-sine (10minus3M) all of whichmay be released duringmyocardialischemia [1 19 20]The chemicals were individually dissolvedin saline solution to a concentration of 10minus3M and were keptfrozenOn the day of the experiment the stock solutionswerewarmed and further diluted in normal saline to concentra-tions of 10minus5M (except the adenosine which was diluted to aconcentration of 10minus3M)

24 Intrapericardial Infusion of the PPS Solution Using amodification of the procedure thatwas described by Euchner-Wamser et al [19] a catheter was placed in the pericardial sacThe catheter wasmade of silicone tubing (0020 ID 0037OD14ndash16 cm length) and was filled with 02ndash05mL of warmednormal saline A thoracotomy was performed on the leftcostal cartilages of ribs 1ndash3 to expose the thymus gland andthe heart The thymus gland was opened along the midlineand the catheter was carefully inserted into the pericardialsac over the left ventricle The catheter was fixed in place bysuturing together the two thymus lobes and the layers of thechest wall To test the pericardial catheter 02mL of salinewas easily injected and removed via a 1mL syringe that wasconnected to the catheter

For nociceptive chemical stimulation of the heart 02mLof the PPS solution was infused into the pericardial sacthrough the catheter over 20ndash30 s The solution was thenallowed to stand for 2min The PPS solution was withdrawnover 20ndash30 s then 02mL of saline flush was infused for2min to rinse away the chemicals within the pericardial sacThe infusion-withdrawal procedure of the PPS solution andsaline flush comprised one set of the experimental protocoland three sets of this procedure were repeated at an intervalof 2-3min as 1 process Throughout the duration of theexperiment three processes were applied in total At least10min elapsed between each process At 15 h after the finalinfusion process of infusion pontamine sky blue dye wasinfused into the pericardial sac to confirm that the PPSsolution did not leak through to the outside of the pericardialsac Saline was substituted for the PPS solution in the vehicle-infused group although the experimental protocol remainedidentical to that performed on the PPS-infused group In theuntreated control group the catheter was inserted into thepericardial sac but no solution was infused

25 Fos Study At the end of each experiment the animalswere perfused intracardially with 002M phosphate buffer(PBS) followed by 4 paraformaldehyde in 01M phosphate-buffered saline (PBS) The spinal cord (C1-C2 segments) andthe brain were removed and placed in 4 paraformaldehydein 01M phosphate-buffered saline (PH74) at 4∘C for 3ndash7

ISRN Pain 3

days The samples were then stored in a cryoprotected 30sucrose solution in 01M phosphate-buffered saline (PH 74)at 4∘C for 3ndash7 days Consecutive transverse 50 120583m sectionswere cut using a cryostat (IEC) at minus20∘C and then transferredimmediately to ten alternatewells of polypropylene plates thatcontained PBS The sections were washed three times in PBSfor 10min each and were then incubated in 3 H

2O2for

30min to stop endogenous peroxidase activity The sectionswere again washed three times for 10min each in PBS Thesections were then incubated in a blocking solution thatcontained 3 normal goat serum (NGS) (Vertor Labora-tories USA) for 30min The sections were then incubatedovernight in c-Fos antibody that was taken from rabbits(1 5000 SC-52 Santa Cruz biotechnology CA USA) at4∘C This incubation caused no cross-reactivity with the Junprotein (Oncogene) At the completion of this incubation thesections were washed in cold PBS three times for 10min eachat room temperature and then incubated with biotinylatedanti-rabbit IgG (1 1000 Dako) for 120min and peroxidase-conjugated streptavidin (1 1000 Dako) for 60min at roomtemperature All of the antibodies were diluted with PBSwhich contained 1 normal goat serum and 05 TritonX-100 For the peroxidase reaction 3101584031015840-diaminobenzidinetetrahydrochloride (DAB Sigma) with nickel ammoniumsulfate intensification was used The sections were mountedon slides air-dried overnight and then counter-stained withneutral red when necessary Finally coverslips were appliedto the slides

26 Vagotomy and Spinal Cord Lesion For the vagotomya tie was gently pulled around the nerve and then the leftand right cervical vagus nerves were separated from thecarotid artery and cut with a scissors In a second group ofanimals the involvement of C1-C2 neurons in PPS-inducedreferred pain in the trigeminal nerve territory was examinedby lesioning the C1-C2 segments of the spinal cord usinga small knife without a laminectomy After the lesion wasperformed the exposed upper cervical enlargement of thespinal cord was covered with bone waxThemusculature andskin were sutured The animals were provided at least 30minrest after the procedure

27 Quantification and Statistical Analysis For each animalthe Fos-labeled cell profiles in 110 serial sections (916ndash1466mm caudal to bregma) including the trigeminal brain-stem sensory nuclear complex were counted at the lightmicroscope level and camera lucida drawings were made ofthe cells The trigeminal sensory nuclear complex is dividedinto the principal sensory trigeminal nucleus (Pr5VL) sub-nucleus oralis (Sp5O) subnucleus interpolaris (Sp5I) andsubnucleus caudalis (Sp5C) The nomenclature and nuclearboundaries were defined based on the atlas produced byPaxinos and Watson [21] For each nucleus of the TSNC thenumber of identified Fos-labeled cells was counted for everythree sections and the total number of Fos-labeled cells wascalculated for each rat

The data are represented as the mean plusmn SEM Statisticalanalyses were carried out using Studentrsquos paired 119905-test to

compare single groups before and after treatment The Fosdata were analyzed using one-way ANOVA (the multiplecomparison test) andor Studentrsquos 119905-test where applicable Adifference was accepted as significant when 119875 lt 005

3 Results

The animalrsquos mean blood pressure and heart rate afterurethane anesthesia were approximately 80ndash100mmHg and300ndash350min respectively To accomplish our objectivesspecial attention was given to the change in the mean bloodpressure and the electrocardiogram following the infusionof either PPS solution or saline into the pericardial sac Nosignificant changeswere observed in themean blood pressureand the electrocardiogram for all of the rats that were tested(data not shown) Based on this finding the influence ofthe infusion-withdrawal procedure of either PPS solution orsaline flush into the pericardial sac could be excluded in thepresent study

31 c-Fos Expression following the Infusion of PPS Solutioninto the Pericardial Sac Figure 1 shows the c-Fos expressionin the C2 spinal segments following the infusion of the PPSsolution into the pericardial sac The number of Fos-labeledcells in the C2 spinal segment was significantly higher inthe PPS-infused rats compared with the vehicle-infused anduninfused control rats In the present study data were usedonly from those animals whose number of Fos-labeled cellsin the C2 spinal segment increased following the infusionof PPS solution into the pericardial sac because several linesof electrophysiological studies have demonstrated that aninjection of algesic chemicals into the pericardial sac resultsin increased activity in C1-C2 STT cells [4ndash7]

In the TSNC Fos-like immunoreactivity was observed inthe PPS-infused rats (119899 = 4) in the vehicle-infused rats (119899 =4) and even in the untreated control rats (119899 = 4) Examplesof c-Fos expression are shown in Figure 2 and the numberof Fos-labeled cells is summarized in Figure 3 The numberof Fos-labeled cells for the Pr5 the Sp5O and the Sp5I didnot reveal significant differences across the treated groups Bycontrast for the Sp5C a significant increase in the number ofFos-labeled cells was observed bilaterally in the PPS-infusedrats No difference was observed in the number of increasedFos-labeled cells in the PPS-infused rats between the left andright Sp5C (Figures 3(a) and 3(b))

A comparison of the number of Fos-labeled cells in thesuperficial layers (marginal layer and substantia gelatinosa)and magnocellular layer in the Sp5C indicated that thenumber of Fos-labeled cells in the superficial layers was sig-nificantly higher than in the magnocellular layer (Figure 4)

32 Effects of Vagotomy or C1-C2 Spinal Cord Lesion on c-Fos Expression Following either the vagotomy or a spinalcord lesion the animalrsquos mean blood pressure and heart ratedid not significantly change compared to the values thatwere present before the surgical treatments although theytransiently increased after the lesion of the C1-C2 spinalsegments

4 ISRN Pain

(a)

(A)

(B)(b)

(A)

(B)

lowast

Num

ber o

f Fos

-labe

led

cells

0

2

4

6

8

10

12

14

1618

Control Vehicle PPS

Right side

lowast

Num

ber o

f Fos

-labe

led

cells

02468

1012141618

Control Vehicle PPS

Left side

Figure 1 (a-A) Photomicrograph of c-Fos expression in the C2 spinal segment of a PPS-infused rat The area bounded by the broken line ismagnified 10 diameter (a-B) A black spot indicates a Fos-labeled cell (black arrow) (b)The number of Fos-labeled cells in uninfused control(Control 119899 = 4) vehicle-infused (Vehicle 119899 = 4) or PPS-infused (PPS 119899 = 4) rats lowast119875 lt 005 significantly different from the number ofFos-labeled cells in vehicle-infused rats

For the PPS-infused rats (119899 = 6) the effects of thevagotomy on c-Fos expression in the C2 spinal segments andthe Sp5C are shown in a representative example in Figure 5and the number of Fos-labeled cells is compared betweenrats that did and did not receive the vagotomy in Figure 6A bilateral section of the cervical vagus nerves showed asignificant decrease in the number of Fos-labeled cells inboth the Sp5C and C2 spinal segments In particular no Fos-labeled cells were observed in the Sp5C In contrast the lesionof the C1-C2 spinal segments produced a significant increasein the number of Fos-labeled cells in the Sp5C This increasein the number of Fos-labeled cells was observed in both thePPS-infused (119899 = 6) and the vehicle-infused (119899 = 3) ratsExamples of c-Fos expression are shown in Figure 7 and thenumber of Fos-labeled cells is summarized in Figure 8

4 Discussion

In the present study special attention was given to the changeof the mean blood pressure and the heart rate followingboth the infusion of either PPS solution or saline into thepericardial sac and the surgical treatments which were eitherthe vagotomy or the spinal cord lesion The animalrsquos meanblood pressure and heart rate did not change significantly

compared to the values that were present before infusion orsurgical treatments although a slight decrease was observedFrom these findings the influence of the infusion-withdrawalprocedure of either PPS solution or saline flush into thepericardial sac was excluded from the present study as wasthe influence of surgical treatments

41 Involvement of the Sp5C in Angina-Induced Referred Painin the Trigeminal Nerve Territory Some electrophysiologicalstudies suggest that angina-induced referred pain in thetrigeminal nerve territory is attributed to the convergence ofboth inputs from the trigeminal nerve territory and inputsfrom the cardiac region to the C1-C2 STT cells [4ndash8] Thisconvergence explained themechanism that underlies referredpain in the trigeminal nerve territory associated with theangina pectoris Clinical or experimental evidence of thiseffect has not yet been found The present study was thefirst study to demonstrate that nociceptive signals from thecardiac region are input to the TSNC specifically to the Sp5C

To compare the number of Fos-labeled cells among thenuclei in the TSNC we counted the total number of Fos-labeled cells in each nucleus because each nucleus differed inarea Counting individual nuclei is considered an acceptable

ISRN Pain 5

Control Vehicle PPS

Pr5

Sp5O

Sp5I

Sp5C

600 120583m

Figure 2 Photomicrographs of c-Fos expression in the left TSNC of uninfused control (Control) vehicle-infused (Vehicle) or PPS-infused(PPS) rats Pr5 the principal sensory trigeminal nucleus Sp5O the subnucleus oralis Sp5I the subnucleus interpolaris Sp5C the subnucleuscaudalis

method for counting Fos-labeled cells in the trigeminal sen-sory nuclear complex [22ndash28] In the present study infusionof the PPS to the pericardial sac resulted in a significantincrease in Fos-labeled cells in the Sp5C but not in othernuclei The Sp5C is a component of the ascending sensorypathway that transmits nociceptive signals from the trigemi-nal nerve territory to the thalamus Nociceptive informationfrom the orofacial region is input to the Sp5C and thentransmits to the ventral posteromedial (VPM) nucleus of thethalamus Therefore it is likely that the activity of the Sp5Cneurons that is evoked by sensory signals from the cardiacregion induces referred pain that is generally associated

with an attack of angina pectoris in the orofacial regionAdditionally the unmyelinated afferent fibers that conductnociceptive signals terminate to the superficial layers in theSp5C [29] The result in the present study that the numberof Fos-labeled cells in superficial layers was significantlyhigher than that in the magnocellular layer suggests that thenociceptive signals from the cardiac region are transmitted tothe thalamus via the superficial layers of the Sp5C

42 Peripheral Afferents Conducting Nociceptive Signals to theSp5C The heart receives reciprocal double innervations ofthe cardiac sympathetic and vagus nerves Bilateral sections

6 ISRN Pain

0

5

10

15

20

25

30N

umbe

r of F

os-la

bele

d ce

lls

Pr5 Sp5O Sp5I Sp5C

Left side

ControlVehiclePPS

lowast

(a)

0

5

10

15

20

25

Num

ber o

f Fos

-labe

led

cells

Pr5 Sp5O Sp5I Sp5C

lowastRight side

ControlVehiclePPS

(b)

Figure 3 A comparison of the number of Fos-labeled cells across uninfused control (Control 119899 = 4) vehicle-infused (Vehicle 119899 = 4) andPPS-infused (PPS 119899 = 4) rats in the left (a) and right (b) TSNC Pr5 the principal sensory trigeminal nucleus Sp5O the subnucleus oralisSp5I the subnucleus interpolaris Sp5C the subnucleus caudalis Note that a significant increase in the number of Fos-labeled cells was onlyobserved in both sides of the Sp5C lowast119875 lt 005 significantly different from the number of Fos-labeled cells in vehicle-infused rats

Num

ber o

f Fos

-labe

led

cells

0

5

10

15

20

25

30

35

Superficial layersMagnocellular layer

Left side Right side

lowast

lowast

Figure 4 A comparison of the number of Fos-labeled cells betweenthe superficial and the magnocellular layers in the Sp5C Notethat the number of Fos-labeled cells in the superficial layers wassignificantly higher than in the magnocellular layer lowast119875 lt 005significantly different between two layers of the Sp5C

of the cervical vagus nerves completely reversed the c-Fos expression that was found in the Sp5C following theinfusion of the PPS solution into the pericardial sac Thisresult shows that the nociceptive signals from the cardiacregion to the Sp5C were conducted by the vagal afferentfibers Additionally a small amount of Fos-labeled cells wasobserved in the C2 spinal segment which indicates that c-Fosexpression may be induced by surgical procedures

Among the animals that received a lesion in the C1-C2spinal segments an increase in Fos-labeled cells in the Sp5Cwas observed in the vehicle-infused rats This result suggeststhat the lesion of the C1-C2 spinal segments influenced c-Fos expression in the Sp5C Therefore it is apparent that thelesion procedures affected the increase in Fos-labeled cells inthe PPS-infused rats Unfortunately we cannot explain thisphenomenon in the present study The rate of increase in theFos-labeled cells was greater in the PPS-infused rats than thatin the vehicle-infused rats For the animals that received theC1-C2 lesion the number of Fos-labeled cells was not reducedin the PPS-infused rats compared with the vehicle-inducedrats thus it is possible that the nociceptive signals from thecardiac region were input to the Sp5C via a neural pathwayin the brain but not via the spinal cord Unfortunately thelocation of this neural pathway was not identified in thepresent study In humans the vagal afferent signals from thevisceral organs including the cardiac region are not inputto the Sp5C although the vagal afferent signals from theskin of the ear concha are input to the Sp5C [30] Severalmorphological and electrophysiological studies have shownthat vagal afferent fibers and the nucleus tractus solitariusplay an important role in angina-induced referred pain in thetrigeminal nerve territory [4 5 7 14] This evidence suggeststhat the nociceptive signals from the cardiac region are inputto the Sp5C via the nucleus tractus solitarius However thepathway from the nucleus tractus solitarius to the Sp5C hasnot been confirmed in anatomical studies It is possible thatthe output signals from the nucleus tractus solitarius areprojected to the Sp5C by way of other nuclei in the brainThe existence of this possibility could not be clarified in thepresent study

ISRN Pain 7

(a)

(b)

(A) (B)

(A) (B)

200 120583m 100 120583m

200 120583m 200 120583m

Figure 5 Effects of vagotomy on c-Fos expression in PPS-infused ratsThe cervical vagus nerve was bilaterally sectioned Photomicrographsshow c-Fos expression in the left Sp5C (a) and the C2 spinal segment (b) Fos-labeled cells were observed in intact rats (a-A and b-A) TheFos-labeled cells were not observed in the vagotomy rats (a-B and b-B)

Num

ber o

f Fos

-labe

led

cells

0

10

20

30

40Sp5C

Left side Right side

lowast lowast

(a)

Num

ber o

f Fos

-labe

led

cells

Left side Right side

lowast lowast

0

5

10

15

20

25

30

C2 spinal segment

Intact ratsSectioned rats

(b)

Figure 6 A comparison of the number of Fos-labeled cells between the intact and vagotomy rats following an infusion of PPS solution Notethat c-Fos expression was significantly reversed by the vagotomy lowast119875 lt 005 significantly different between two groups of rats

8 ISRN Pain

600 120583m

(a)

(b)

(A) (B)

(A) (B)

Figure 7 Effects of the lesion of the C1-C2 spinal segments on c-Fos expression in vehicle-infused (a) and PPS-infused (b) ratsPhotomicrographs show c-Fos expression in the left Sp5C Fos-labeled cells were observed in the intact rats (a-A and b-A) The numberof Fos-labeled cells remarkably increased in the lesioned rats (a-B and b-B) compared with the intact rats

Left side Right side

Num

ber o

f Fos

-labe

led

cells

0

5

10

15

20Vehicle

lowast

(a)

Right sideLeft side

Intact ratsC1-C2 lesioned rats

Num

ber o

f Fos

-labe

led

cells

0

10

20

30

40

50

60 PPSlowast

lowast

(b)

Figure 8 A comparison of the number of Fos-labeled cells between intact and C1-C2-lesioned rats following an infusion of either vehicleor PPS solution Note that c-Fos expression significantly increased when the C1-C2 spinal segments were lesioned lowast119875 lt 005 significantlydifferent between two groups of rats

ISRN Pain 9

The descending projection from the Sp5C to the spinaldorsal horn has been demonstrated anatomically [31ndash35]Therefore the activation of Sp5C cells induced by nociceptivesignals from the cardiac region may explain the results fromprior studies that injection of algesic chemicals into thepericardial sac resulted in an increase in activity among theC1-C2 STT cells [4ndash7]

In conclusion nociceptive signals from the cardiac regionare input to the SP5C via an unknown pathway in the brainThese signals are transmitted to secondary neurons at thesuperficial layers in the Sp5C and then projected to thethalamusThis ascending pathway may contribute to angina-induced referred pain in the trigeminal nerve territory

Conflict of Interests

The authors have no conflict of interests to declare

Acknowledgments

The authors thank Dr Yumiko Hayashi for her criticalreading of the paper This work was supported in part by agrant from Daiichi-Sankyo Co Ltd

References

[1] R D Foreman ldquoMechanisms of cardiac painrdquo Annual Reviewof Physiology vol 61 pp 143ndash167 1999

[2] T C Ruch ldquoVisceral sensation and referred painrdquo in FultonHowellrsquos Textbook of Physiology pp 385ndash401 WB SaundersPhiladelphia Pa USA 15th edition 1946

[3] D E Myers ldquoVagus nerve pain referred to the craniofacialregion A case report and literature review with implications forreferred cardiac painrdquo The British Dental Journal vol 204 no4 pp 187ndash189 2008

[4] M J Chandler J Zhang and R D Foreman ldquoVagal sympa-thetic and somatic sensory inputs to upper cervical (C1-C3)spinothalamic tract neurons inmonkeysrdquo Journal of Neurophys-iology vol 76 no 4 pp 2555ndash2567 1996

[5] M J Chandler J Zhang and R D Foreman ldquoPericardialinjections of inflammatory chemicals excite upper cervical (C1-C3) spinothalamic tract (STT) cells in monkeysrdquo Society forNeuroscience vol 21 article 2604 1995

[6] R D Foreman and C Qin ldquoNeuromodulation of cardiac painand cerebral vasculature neural mechanismsrdquo Cleveland ClinicJournal of Medicine vol 76 pp S75ndashS79 2009

[7] C Qin M J Chandler K E Miller and R D ForemanldquoResponses and afferent pathways of superficial and deeper C1-C2 spinal cells to intrapericardial algogenic chemicals in ratsrdquoJournal of Neurophysiology vol 85 no 4 pp 1522ndash1532 2001

[8] D L McNeill M J Chandler Q G Fu and R D ForemanldquoProjection of nodose ganglion cells to the upper cervical spinalcord in the ratrdquoBrain Research Bulletin vol 27 no 2 pp 151ndash1551991

[9] B J Sessle ldquoPeripheral and central mechanisms of orofacialinflammatory painrdquo International Review of Neurobiology vol97 pp 179ndash206 2011

[10] B Greenwood-VanMeerveldMGibsonWGunter J ShepardR Foreman and D Myers ldquoStereotaxic delivery of corticos-terone to the amygdala modulates colonic sensitivity in ratsrdquoBrain Research vol 893 no 1-2 pp 135ndash142 2001

[11] W D Gunter J D Shepard R D Foreman D A Myers andB Greenwood-Van Meerveld ldquoEvidence for visceral hypersen-sitivity in high-anxiety ratsrdquo Physiology and Behavior vol 69no 3 pp 379ndash382 2000

[12] C Qin B Greenwood-Van Meerveld D A Myers and R DForeman ldquoCorticosterone acts directly at the amygdala to alterspinal neuronal activity in response to colorectal distensionrdquoJournal of Neurophysiology vol 89 no 3 pp 1343ndash1352 2003

[13] J C White and W H Seet Eds Pain and the NeurosurgeonCharles C Thomas Springfield Ill USA 1969

[14] F Hua T Harrison C Qin et al ldquoc-Fos expression in ratbrain stem and spinal cord in response to activation of car-diac ischemia-sensitive afferent neurons and electrostimulatorymodulationrdquo The American Journal of PhysiologymdashHeart andCirculatory Physiology vol 287 no 6 pp H2728ndashH2738 2004

[15] I Lindgren and H Olivecrona ldquoSurgical treatment of anginapectorisrdquo Journal of Neurosurgery vol 4 no 1 pp 19ndash39 1947

[16] J C White and E F Bland ldquoThe surgical relief of severe anginapectoris methods employed and endrdquo Medicine vol 27 no 1pp 1ndash42 1948

[17] M Zimmermann ldquoEthical guidelines for investigations ofexperimental pain in conscious animalsrdquo Pain vol 16 no 2 pp109ndash110 1983

[18] H O Handwerker and PW Reeh ldquoPain and inflammationrdquo inProceedings of the 5th World Congress on Pain M R Bond J ECharlton andC JWoolf Eds pp 59ndash70 Elsevier AmsterdamThe Netherlands 1991

[19] I Euchner-Wamser S T Meller and G F Gebhart ldquoA modelof cardiac nociception in chronically instrumented rats behav-ioral and electrophysiological effects of pericardial administra-tion of algogenic substancesrdquo Pain vol 58 no 1 pp 117ndash1281994

[20] S T Meller and G F Gebhart ldquoA critical review of the afferentpathways and the potential chemical mediators involved incardiac painrdquo Neuroscience vol 48 no 3 pp 501ndash524 1992

[21] G Paxinos and C Watson Eds The Rat Brain in StereotaxicCoodinates Academic Press New York NY USA 1998

[22] M E Edelsbrunner M Nakano and P Holzer ldquoAfferentsignalling from the acid-challenged rat stomach is inhibitedand gastric acid elimination is enhanced by lafutidinerdquo BMCGastroenterology vol 9 article 40 2009

[23] T Haino S Hironaka T Ooka et al ldquoOrosensory deprivationalters taste-elicited c-Fos expression in the parabrachial nucleusof neonatal ratsrdquo Neuroscience Research vol 67 no 3 pp 228ndash235 2010

[24] K Okamoto R Thompson A Tashiro Z Chang and D ABereiter ldquoBright light produces Fos-positive neurons in caudaltrigeminal brainstemrdquo Neuroscience vol 160 no 4 pp 858ndash864 2009

[25] K Tokita T Shimura S Nakamura T Inoue and T YamamotoldquoInvolvement of forebrain in parabrachial neuronal activationinduced by aversively conditioned taste stimuli in the ratrdquo BrainResearch vol 1141 no 1 pp 188ndash196 2007

[26] T Yamamoto and K Sawa ldquoc-Fos-like immunoreactivity in thebrainstem following gastric loads of various chemical solutionsin ratsrdquo Brain Research vol 866 no 1-2 pp 135ndash143 2000

10 ISRN Pain

[27] T Yamamoto and K Sawa ldquoComparison of c-Fos-like immu-noreactivity in the brainstem following intraoral and intragas-tric infusions of chemical solutions in ratsrdquo Brain Research vol866 no 1-2 pp 144ndash151 2000

[28] T YamamotoM Takemura T Inui et al ldquoFunctional organiza-tion of the rodent parabrachial nucleusrdquoAnnals of the New YorkAcademy of Sciences vol 1170 pp 378ndash382 2009

[29] B J Sessle ldquoNeural mechanisms and pathways in craniofacialpainrdquo Canadian Journal of Neurological Sciences vol 26 no 3pp S7ndashS11 1999

[30] R Nieuwenhuys J Voogd and C H R van Huijzen EdsTheHuman Central Nervous System A Synopsis and Atlas SpringerBerlin Germany 1978

[31] H Burton A D Craig Jr D A Poulos and J T Molt ldquoEfferentprojections from temperature sensitive recording loci withinthe marginal zone of the nucleus caudalis of the spinal trigem-inal complex in the catrdquo Journal of Comparative Neurology vol183 no 4 pp 753ndash777 1979

[32] H Burton and A D Loewy ldquoDescending projections from themarginal cell layer and other regions of themonkey spinal cordrdquoBrain Research vol 116 no 3 pp 485ndash491 1976

[33] C E Catsman-Berrevoets and H G J M Kuypers ldquoCells oforigin of cortical projections to dorsal column nuclei spinalcord and bulbar medial reticular formation in the rhesusmonkeyrdquoNeuroscience Letters vol 3 no 5-6 pp 245ndash252 1976

[34] H G J M Kuypers and V A Maisky ldquoRetrograde axonaltransport of horseradish peroxidase from spinal cord to brainstem cell groups in the catrdquo Neuroscience Letters vol 1 no 1pp 9ndash14 1975

[35] D A Ruggiero C A Ross and D J Reis ldquoProjections from thespinal trigeminal nucleus to the entire length of the spinal cordin the ratrdquo Brain Research vol 225 no 2 pp 225ndash233 1981

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Page 2: Research Article Neural Mechanisms That Underlie Angina ...downloads.hindawi.com/archive/2013/671503.pdf · angina-induced referred pain. It is of particular interest to examine such

2 ISRN Pain

transmits sensory signals from the orofacial region to thehigher centers of the brain [9] Therefore this complex maybe considered to a candidate for the relay nuclei that transmitsangina-induced referred pain It is of particular interest toexamine such a possibility because the mechanisms appearto be a convergence of trigeminal and spinal inputs in theTSNC One of the objectives of the present study was todetermine whether the TSNC is involved in the ascendingsensory pathway that transmits nociceptive signals from thecardiac region to the thalamus in the brain

During the twentieth century it was believed that noci-ceptive information from the cardiac region was input to thethoracic segments of the spinal cord via the cardiac sym-pathetic nerve while the vagal afferent fibers were thoughtto transmit innocuous cardiac sensory information [10ndash13]Several morphological and electrophysiological studies fromthe late 1990s showed that vagal afferent fibers and the nucleustractus solitarius play an important role in angina-relatedreferred pain in the trigeminal nerve territory [4 5 7 14]This finding is consistent with clinical observations thatneck and jaw pain continues or develops after the use of asympathectomy to relieve anginal pain [15 16] The secondaim of the present study was to identify the peripheral nervethat conducts the nociceptive signals that are input into theTSNC

2 Materials and Methods

All of the experimental protocols used in the present studywere approved by the Institutional Animal Care and UseCommittee of Showa University and were in accordance withthe guideline of the International Association for the Study ofPain [17] For example the number of animals was kept to aminimum to minimize the animalrsquos discomfort

21 Animals The experiments were performed on maleWistar rats weighing 400ndash550 g (119899 = 30 Charles RiverTokyo) The animals were housed in groups of 3-4 in a cagecontaining sawdust bedding and were granted free accessto rat chow and water The laboratory was equipped with a12 h12 h (8 am8 pm) light-dark cycle Room temperatureand humidity were maintained at 235∘C and 60 respec-tively

22 Surgical Preparation Theanimalswere anesthetizedwithurethane (12 gkg ip) After a tracheotomy was performedthe animals were artificially ventilated to maintain an end-tidal CO

2level between 35 and 45 An adequate level

of anesthesia was determined by the absence of pupillarydilation or increases in heart rate Under the anestheticcondition in the present study no spontaneous movementwas observed in the animals throughout the experimentsMean blood pressure was measured directly via a catheterthat was inserted into the right femoral artery Heart rate wasmonitored by electrocardiogram The mean blood pressureand the electrocardiogram were fed into an AD converter(CED 1401 +) andwere recorded using Spike2 software (CEDCambridge UK) The animalrsquos core body temperature was

regulated at approximately 375∘C using a thermostaticallycontrolled heating blanket

23 Pain Producing Substance (PPS) The cardiac nociceptivereceptors were stimulated chemically using a modified painproducing chemical mixture that was designed to excite boththe vagal and sympathetic afferent endings [18] The PPSsolution contained bradykinin (10minus5M) serotonin (10minus5M)prostaglandin E2 (10minus5M) histamine (10minus5M) and adeno-sine (10minus3M) all of whichmay be released duringmyocardialischemia [1 19 20]The chemicals were individually dissolvedin saline solution to a concentration of 10minus3M and were keptfrozenOn the day of the experiment the stock solutionswerewarmed and further diluted in normal saline to concentra-tions of 10minus5M (except the adenosine which was diluted to aconcentration of 10minus3M)

24 Intrapericardial Infusion of the PPS Solution Using amodification of the procedure thatwas described by Euchner-Wamser et al [19] a catheter was placed in the pericardial sacThe catheter wasmade of silicone tubing (0020 ID 0037OD14ndash16 cm length) and was filled with 02ndash05mL of warmednormal saline A thoracotomy was performed on the leftcostal cartilages of ribs 1ndash3 to expose the thymus gland andthe heart The thymus gland was opened along the midlineand the catheter was carefully inserted into the pericardialsac over the left ventricle The catheter was fixed in place bysuturing together the two thymus lobes and the layers of thechest wall To test the pericardial catheter 02mL of salinewas easily injected and removed via a 1mL syringe that wasconnected to the catheter

For nociceptive chemical stimulation of the heart 02mLof the PPS solution was infused into the pericardial sacthrough the catheter over 20ndash30 s The solution was thenallowed to stand for 2min The PPS solution was withdrawnover 20ndash30 s then 02mL of saline flush was infused for2min to rinse away the chemicals within the pericardial sacThe infusion-withdrawal procedure of the PPS solution andsaline flush comprised one set of the experimental protocoland three sets of this procedure were repeated at an intervalof 2-3min as 1 process Throughout the duration of theexperiment three processes were applied in total At least10min elapsed between each process At 15 h after the finalinfusion process of infusion pontamine sky blue dye wasinfused into the pericardial sac to confirm that the PPSsolution did not leak through to the outside of the pericardialsac Saline was substituted for the PPS solution in the vehicle-infused group although the experimental protocol remainedidentical to that performed on the PPS-infused group In theuntreated control group the catheter was inserted into thepericardial sac but no solution was infused

25 Fos Study At the end of each experiment the animalswere perfused intracardially with 002M phosphate buffer(PBS) followed by 4 paraformaldehyde in 01M phosphate-buffered saline (PBS) The spinal cord (C1-C2 segments) andthe brain were removed and placed in 4 paraformaldehydein 01M phosphate-buffered saline (PH74) at 4∘C for 3ndash7

ISRN Pain 3

days The samples were then stored in a cryoprotected 30sucrose solution in 01M phosphate-buffered saline (PH 74)at 4∘C for 3ndash7 days Consecutive transverse 50 120583m sectionswere cut using a cryostat (IEC) at minus20∘C and then transferredimmediately to ten alternatewells of polypropylene plates thatcontained PBS The sections were washed three times in PBSfor 10min each and were then incubated in 3 H

2O2for

30min to stop endogenous peroxidase activity The sectionswere again washed three times for 10min each in PBS Thesections were then incubated in a blocking solution thatcontained 3 normal goat serum (NGS) (Vertor Labora-tories USA) for 30min The sections were then incubatedovernight in c-Fos antibody that was taken from rabbits(1 5000 SC-52 Santa Cruz biotechnology CA USA) at4∘C This incubation caused no cross-reactivity with the Junprotein (Oncogene) At the completion of this incubation thesections were washed in cold PBS three times for 10min eachat room temperature and then incubated with biotinylatedanti-rabbit IgG (1 1000 Dako) for 120min and peroxidase-conjugated streptavidin (1 1000 Dako) for 60min at roomtemperature All of the antibodies were diluted with PBSwhich contained 1 normal goat serum and 05 TritonX-100 For the peroxidase reaction 3101584031015840-diaminobenzidinetetrahydrochloride (DAB Sigma) with nickel ammoniumsulfate intensification was used The sections were mountedon slides air-dried overnight and then counter-stained withneutral red when necessary Finally coverslips were appliedto the slides

26 Vagotomy and Spinal Cord Lesion For the vagotomya tie was gently pulled around the nerve and then the leftand right cervical vagus nerves were separated from thecarotid artery and cut with a scissors In a second group ofanimals the involvement of C1-C2 neurons in PPS-inducedreferred pain in the trigeminal nerve territory was examinedby lesioning the C1-C2 segments of the spinal cord usinga small knife without a laminectomy After the lesion wasperformed the exposed upper cervical enlargement of thespinal cord was covered with bone waxThemusculature andskin were sutured The animals were provided at least 30minrest after the procedure

27 Quantification and Statistical Analysis For each animalthe Fos-labeled cell profiles in 110 serial sections (916ndash1466mm caudal to bregma) including the trigeminal brain-stem sensory nuclear complex were counted at the lightmicroscope level and camera lucida drawings were made ofthe cells The trigeminal sensory nuclear complex is dividedinto the principal sensory trigeminal nucleus (Pr5VL) sub-nucleus oralis (Sp5O) subnucleus interpolaris (Sp5I) andsubnucleus caudalis (Sp5C) The nomenclature and nuclearboundaries were defined based on the atlas produced byPaxinos and Watson [21] For each nucleus of the TSNC thenumber of identified Fos-labeled cells was counted for everythree sections and the total number of Fos-labeled cells wascalculated for each rat

The data are represented as the mean plusmn SEM Statisticalanalyses were carried out using Studentrsquos paired 119905-test to

compare single groups before and after treatment The Fosdata were analyzed using one-way ANOVA (the multiplecomparison test) andor Studentrsquos 119905-test where applicable Adifference was accepted as significant when 119875 lt 005

3 Results

The animalrsquos mean blood pressure and heart rate afterurethane anesthesia were approximately 80ndash100mmHg and300ndash350min respectively To accomplish our objectivesspecial attention was given to the change in the mean bloodpressure and the electrocardiogram following the infusionof either PPS solution or saline into the pericardial sac Nosignificant changeswere observed in themean blood pressureand the electrocardiogram for all of the rats that were tested(data not shown) Based on this finding the influence ofthe infusion-withdrawal procedure of either PPS solution orsaline flush into the pericardial sac could be excluded in thepresent study

31 c-Fos Expression following the Infusion of PPS Solutioninto the Pericardial Sac Figure 1 shows the c-Fos expressionin the C2 spinal segments following the infusion of the PPSsolution into the pericardial sac The number of Fos-labeledcells in the C2 spinal segment was significantly higher inthe PPS-infused rats compared with the vehicle-infused anduninfused control rats In the present study data were usedonly from those animals whose number of Fos-labeled cellsin the C2 spinal segment increased following the infusionof PPS solution into the pericardial sac because several linesof electrophysiological studies have demonstrated that aninjection of algesic chemicals into the pericardial sac resultsin increased activity in C1-C2 STT cells [4ndash7]

In the TSNC Fos-like immunoreactivity was observed inthe PPS-infused rats (119899 = 4) in the vehicle-infused rats (119899 =4) and even in the untreated control rats (119899 = 4) Examplesof c-Fos expression are shown in Figure 2 and the numberof Fos-labeled cells is summarized in Figure 3 The numberof Fos-labeled cells for the Pr5 the Sp5O and the Sp5I didnot reveal significant differences across the treated groups Bycontrast for the Sp5C a significant increase in the number ofFos-labeled cells was observed bilaterally in the PPS-infusedrats No difference was observed in the number of increasedFos-labeled cells in the PPS-infused rats between the left andright Sp5C (Figures 3(a) and 3(b))

A comparison of the number of Fos-labeled cells in thesuperficial layers (marginal layer and substantia gelatinosa)and magnocellular layer in the Sp5C indicated that thenumber of Fos-labeled cells in the superficial layers was sig-nificantly higher than in the magnocellular layer (Figure 4)

32 Effects of Vagotomy or C1-C2 Spinal Cord Lesion on c-Fos Expression Following either the vagotomy or a spinalcord lesion the animalrsquos mean blood pressure and heart ratedid not significantly change compared to the values thatwere present before the surgical treatments although theytransiently increased after the lesion of the C1-C2 spinalsegments

4 ISRN Pain

(a)

(A)

(B)(b)

(A)

(B)

lowast

Num

ber o

f Fos

-labe

led

cells

0

2

4

6

8

10

12

14

1618

Control Vehicle PPS

Right side

lowast

Num

ber o

f Fos

-labe

led

cells

02468

1012141618

Control Vehicle PPS

Left side

Figure 1 (a-A) Photomicrograph of c-Fos expression in the C2 spinal segment of a PPS-infused rat The area bounded by the broken line ismagnified 10 diameter (a-B) A black spot indicates a Fos-labeled cell (black arrow) (b)The number of Fos-labeled cells in uninfused control(Control 119899 = 4) vehicle-infused (Vehicle 119899 = 4) or PPS-infused (PPS 119899 = 4) rats lowast119875 lt 005 significantly different from the number ofFos-labeled cells in vehicle-infused rats

For the PPS-infused rats (119899 = 6) the effects of thevagotomy on c-Fos expression in the C2 spinal segments andthe Sp5C are shown in a representative example in Figure 5and the number of Fos-labeled cells is compared betweenrats that did and did not receive the vagotomy in Figure 6A bilateral section of the cervical vagus nerves showed asignificant decrease in the number of Fos-labeled cells inboth the Sp5C and C2 spinal segments In particular no Fos-labeled cells were observed in the Sp5C In contrast the lesionof the C1-C2 spinal segments produced a significant increasein the number of Fos-labeled cells in the Sp5C This increasein the number of Fos-labeled cells was observed in both thePPS-infused (119899 = 6) and the vehicle-infused (119899 = 3) ratsExamples of c-Fos expression are shown in Figure 7 and thenumber of Fos-labeled cells is summarized in Figure 8

4 Discussion

In the present study special attention was given to the changeof the mean blood pressure and the heart rate followingboth the infusion of either PPS solution or saline into thepericardial sac and the surgical treatments which were eitherthe vagotomy or the spinal cord lesion The animalrsquos meanblood pressure and heart rate did not change significantly

compared to the values that were present before infusion orsurgical treatments although a slight decrease was observedFrom these findings the influence of the infusion-withdrawalprocedure of either PPS solution or saline flush into thepericardial sac was excluded from the present study as wasthe influence of surgical treatments

41 Involvement of the Sp5C in Angina-Induced Referred Painin the Trigeminal Nerve Territory Some electrophysiologicalstudies suggest that angina-induced referred pain in thetrigeminal nerve territory is attributed to the convergence ofboth inputs from the trigeminal nerve territory and inputsfrom the cardiac region to the C1-C2 STT cells [4ndash8] Thisconvergence explained themechanism that underlies referredpain in the trigeminal nerve territory associated with theangina pectoris Clinical or experimental evidence of thiseffect has not yet been found The present study was thefirst study to demonstrate that nociceptive signals from thecardiac region are input to the TSNC specifically to the Sp5C

To compare the number of Fos-labeled cells among thenuclei in the TSNC we counted the total number of Fos-labeled cells in each nucleus because each nucleus differed inarea Counting individual nuclei is considered an acceptable

ISRN Pain 5

Control Vehicle PPS

Pr5

Sp5O

Sp5I

Sp5C

600 120583m

Figure 2 Photomicrographs of c-Fos expression in the left TSNC of uninfused control (Control) vehicle-infused (Vehicle) or PPS-infused(PPS) rats Pr5 the principal sensory trigeminal nucleus Sp5O the subnucleus oralis Sp5I the subnucleus interpolaris Sp5C the subnucleuscaudalis

method for counting Fos-labeled cells in the trigeminal sen-sory nuclear complex [22ndash28] In the present study infusionof the PPS to the pericardial sac resulted in a significantincrease in Fos-labeled cells in the Sp5C but not in othernuclei The Sp5C is a component of the ascending sensorypathway that transmits nociceptive signals from the trigemi-nal nerve territory to the thalamus Nociceptive informationfrom the orofacial region is input to the Sp5C and thentransmits to the ventral posteromedial (VPM) nucleus of thethalamus Therefore it is likely that the activity of the Sp5Cneurons that is evoked by sensory signals from the cardiacregion induces referred pain that is generally associated

with an attack of angina pectoris in the orofacial regionAdditionally the unmyelinated afferent fibers that conductnociceptive signals terminate to the superficial layers in theSp5C [29] The result in the present study that the numberof Fos-labeled cells in superficial layers was significantlyhigher than that in the magnocellular layer suggests that thenociceptive signals from the cardiac region are transmitted tothe thalamus via the superficial layers of the Sp5C

42 Peripheral Afferents Conducting Nociceptive Signals to theSp5C The heart receives reciprocal double innervations ofthe cardiac sympathetic and vagus nerves Bilateral sections

6 ISRN Pain

0

5

10

15

20

25

30N

umbe

r of F

os-la

bele

d ce

lls

Pr5 Sp5O Sp5I Sp5C

Left side

ControlVehiclePPS

lowast

(a)

0

5

10

15

20

25

Num

ber o

f Fos

-labe

led

cells

Pr5 Sp5O Sp5I Sp5C

lowastRight side

ControlVehiclePPS

(b)

Figure 3 A comparison of the number of Fos-labeled cells across uninfused control (Control 119899 = 4) vehicle-infused (Vehicle 119899 = 4) andPPS-infused (PPS 119899 = 4) rats in the left (a) and right (b) TSNC Pr5 the principal sensory trigeminal nucleus Sp5O the subnucleus oralisSp5I the subnucleus interpolaris Sp5C the subnucleus caudalis Note that a significant increase in the number of Fos-labeled cells was onlyobserved in both sides of the Sp5C lowast119875 lt 005 significantly different from the number of Fos-labeled cells in vehicle-infused rats

Num

ber o

f Fos

-labe

led

cells

0

5

10

15

20

25

30

35

Superficial layersMagnocellular layer

Left side Right side

lowast

lowast

Figure 4 A comparison of the number of Fos-labeled cells betweenthe superficial and the magnocellular layers in the Sp5C Notethat the number of Fos-labeled cells in the superficial layers wassignificantly higher than in the magnocellular layer lowast119875 lt 005significantly different between two layers of the Sp5C

of the cervical vagus nerves completely reversed the c-Fos expression that was found in the Sp5C following theinfusion of the PPS solution into the pericardial sac Thisresult shows that the nociceptive signals from the cardiacregion to the Sp5C were conducted by the vagal afferentfibers Additionally a small amount of Fos-labeled cells wasobserved in the C2 spinal segment which indicates that c-Fosexpression may be induced by surgical procedures

Among the animals that received a lesion in the C1-C2spinal segments an increase in Fos-labeled cells in the Sp5Cwas observed in the vehicle-infused rats This result suggeststhat the lesion of the C1-C2 spinal segments influenced c-Fos expression in the Sp5C Therefore it is apparent that thelesion procedures affected the increase in Fos-labeled cells inthe PPS-infused rats Unfortunately we cannot explain thisphenomenon in the present study The rate of increase in theFos-labeled cells was greater in the PPS-infused rats than thatin the vehicle-infused rats For the animals that received theC1-C2 lesion the number of Fos-labeled cells was not reducedin the PPS-infused rats compared with the vehicle-inducedrats thus it is possible that the nociceptive signals from thecardiac region were input to the Sp5C via a neural pathwayin the brain but not via the spinal cord Unfortunately thelocation of this neural pathway was not identified in thepresent study In humans the vagal afferent signals from thevisceral organs including the cardiac region are not inputto the Sp5C although the vagal afferent signals from theskin of the ear concha are input to the Sp5C [30] Severalmorphological and electrophysiological studies have shownthat vagal afferent fibers and the nucleus tractus solitariusplay an important role in angina-induced referred pain in thetrigeminal nerve territory [4 5 7 14] This evidence suggeststhat the nociceptive signals from the cardiac region are inputto the Sp5C via the nucleus tractus solitarius However thepathway from the nucleus tractus solitarius to the Sp5C hasnot been confirmed in anatomical studies It is possible thatthe output signals from the nucleus tractus solitarius areprojected to the Sp5C by way of other nuclei in the brainThe existence of this possibility could not be clarified in thepresent study

ISRN Pain 7

(a)

(b)

(A) (B)

(A) (B)

200 120583m 100 120583m

200 120583m 200 120583m

Figure 5 Effects of vagotomy on c-Fos expression in PPS-infused ratsThe cervical vagus nerve was bilaterally sectioned Photomicrographsshow c-Fos expression in the left Sp5C (a) and the C2 spinal segment (b) Fos-labeled cells were observed in intact rats (a-A and b-A) TheFos-labeled cells were not observed in the vagotomy rats (a-B and b-B)

Num

ber o

f Fos

-labe

led

cells

0

10

20

30

40Sp5C

Left side Right side

lowast lowast

(a)

Num

ber o

f Fos

-labe

led

cells

Left side Right side

lowast lowast

0

5

10

15

20

25

30

C2 spinal segment

Intact ratsSectioned rats

(b)

Figure 6 A comparison of the number of Fos-labeled cells between the intact and vagotomy rats following an infusion of PPS solution Notethat c-Fos expression was significantly reversed by the vagotomy lowast119875 lt 005 significantly different between two groups of rats

8 ISRN Pain

600 120583m

(a)

(b)

(A) (B)

(A) (B)

Figure 7 Effects of the lesion of the C1-C2 spinal segments on c-Fos expression in vehicle-infused (a) and PPS-infused (b) ratsPhotomicrographs show c-Fos expression in the left Sp5C Fos-labeled cells were observed in the intact rats (a-A and b-A) The numberof Fos-labeled cells remarkably increased in the lesioned rats (a-B and b-B) compared with the intact rats

Left side Right side

Num

ber o

f Fos

-labe

led

cells

0

5

10

15

20Vehicle

lowast

(a)

Right sideLeft side

Intact ratsC1-C2 lesioned rats

Num

ber o

f Fos

-labe

led

cells

0

10

20

30

40

50

60 PPSlowast

lowast

(b)

Figure 8 A comparison of the number of Fos-labeled cells between intact and C1-C2-lesioned rats following an infusion of either vehicleor PPS solution Note that c-Fos expression significantly increased when the C1-C2 spinal segments were lesioned lowast119875 lt 005 significantlydifferent between two groups of rats

ISRN Pain 9

The descending projection from the Sp5C to the spinaldorsal horn has been demonstrated anatomically [31ndash35]Therefore the activation of Sp5C cells induced by nociceptivesignals from the cardiac region may explain the results fromprior studies that injection of algesic chemicals into thepericardial sac resulted in an increase in activity among theC1-C2 STT cells [4ndash7]

In conclusion nociceptive signals from the cardiac regionare input to the SP5C via an unknown pathway in the brainThese signals are transmitted to secondary neurons at thesuperficial layers in the Sp5C and then projected to thethalamusThis ascending pathway may contribute to angina-induced referred pain in the trigeminal nerve territory

Conflict of Interests

The authors have no conflict of interests to declare

Acknowledgments

The authors thank Dr Yumiko Hayashi for her criticalreading of the paper This work was supported in part by agrant from Daiichi-Sankyo Co Ltd

References

[1] R D Foreman ldquoMechanisms of cardiac painrdquo Annual Reviewof Physiology vol 61 pp 143ndash167 1999

[2] T C Ruch ldquoVisceral sensation and referred painrdquo in FultonHowellrsquos Textbook of Physiology pp 385ndash401 WB SaundersPhiladelphia Pa USA 15th edition 1946

[3] D E Myers ldquoVagus nerve pain referred to the craniofacialregion A case report and literature review with implications forreferred cardiac painrdquo The British Dental Journal vol 204 no4 pp 187ndash189 2008

[4] M J Chandler J Zhang and R D Foreman ldquoVagal sympa-thetic and somatic sensory inputs to upper cervical (C1-C3)spinothalamic tract neurons inmonkeysrdquo Journal of Neurophys-iology vol 76 no 4 pp 2555ndash2567 1996

[5] M J Chandler J Zhang and R D Foreman ldquoPericardialinjections of inflammatory chemicals excite upper cervical (C1-C3) spinothalamic tract (STT) cells in monkeysrdquo Society forNeuroscience vol 21 article 2604 1995

[6] R D Foreman and C Qin ldquoNeuromodulation of cardiac painand cerebral vasculature neural mechanismsrdquo Cleveland ClinicJournal of Medicine vol 76 pp S75ndashS79 2009

[7] C Qin M J Chandler K E Miller and R D ForemanldquoResponses and afferent pathways of superficial and deeper C1-C2 spinal cells to intrapericardial algogenic chemicals in ratsrdquoJournal of Neurophysiology vol 85 no 4 pp 1522ndash1532 2001

[8] D L McNeill M J Chandler Q G Fu and R D ForemanldquoProjection of nodose ganglion cells to the upper cervical spinalcord in the ratrdquoBrain Research Bulletin vol 27 no 2 pp 151ndash1551991

[9] B J Sessle ldquoPeripheral and central mechanisms of orofacialinflammatory painrdquo International Review of Neurobiology vol97 pp 179ndash206 2011

[10] B Greenwood-VanMeerveldMGibsonWGunter J ShepardR Foreman and D Myers ldquoStereotaxic delivery of corticos-terone to the amygdala modulates colonic sensitivity in ratsrdquoBrain Research vol 893 no 1-2 pp 135ndash142 2001

[11] W D Gunter J D Shepard R D Foreman D A Myers andB Greenwood-Van Meerveld ldquoEvidence for visceral hypersen-sitivity in high-anxiety ratsrdquo Physiology and Behavior vol 69no 3 pp 379ndash382 2000

[12] C Qin B Greenwood-Van Meerveld D A Myers and R DForeman ldquoCorticosterone acts directly at the amygdala to alterspinal neuronal activity in response to colorectal distensionrdquoJournal of Neurophysiology vol 89 no 3 pp 1343ndash1352 2003

[13] J C White and W H Seet Eds Pain and the NeurosurgeonCharles C Thomas Springfield Ill USA 1969

[14] F Hua T Harrison C Qin et al ldquoc-Fos expression in ratbrain stem and spinal cord in response to activation of car-diac ischemia-sensitive afferent neurons and electrostimulatorymodulationrdquo The American Journal of PhysiologymdashHeart andCirculatory Physiology vol 287 no 6 pp H2728ndashH2738 2004

[15] I Lindgren and H Olivecrona ldquoSurgical treatment of anginapectorisrdquo Journal of Neurosurgery vol 4 no 1 pp 19ndash39 1947

[16] J C White and E F Bland ldquoThe surgical relief of severe anginapectoris methods employed and endrdquo Medicine vol 27 no 1pp 1ndash42 1948

[17] M Zimmermann ldquoEthical guidelines for investigations ofexperimental pain in conscious animalsrdquo Pain vol 16 no 2 pp109ndash110 1983

[18] H O Handwerker and PW Reeh ldquoPain and inflammationrdquo inProceedings of the 5th World Congress on Pain M R Bond J ECharlton andC JWoolf Eds pp 59ndash70 Elsevier AmsterdamThe Netherlands 1991

[19] I Euchner-Wamser S T Meller and G F Gebhart ldquoA modelof cardiac nociception in chronically instrumented rats behav-ioral and electrophysiological effects of pericardial administra-tion of algogenic substancesrdquo Pain vol 58 no 1 pp 117ndash1281994

[20] S T Meller and G F Gebhart ldquoA critical review of the afferentpathways and the potential chemical mediators involved incardiac painrdquo Neuroscience vol 48 no 3 pp 501ndash524 1992

[21] G Paxinos and C Watson Eds The Rat Brain in StereotaxicCoodinates Academic Press New York NY USA 1998

[22] M E Edelsbrunner M Nakano and P Holzer ldquoAfferentsignalling from the acid-challenged rat stomach is inhibitedand gastric acid elimination is enhanced by lafutidinerdquo BMCGastroenterology vol 9 article 40 2009

[23] T Haino S Hironaka T Ooka et al ldquoOrosensory deprivationalters taste-elicited c-Fos expression in the parabrachial nucleusof neonatal ratsrdquo Neuroscience Research vol 67 no 3 pp 228ndash235 2010

[24] K Okamoto R Thompson A Tashiro Z Chang and D ABereiter ldquoBright light produces Fos-positive neurons in caudaltrigeminal brainstemrdquo Neuroscience vol 160 no 4 pp 858ndash864 2009

[25] K Tokita T Shimura S Nakamura T Inoue and T YamamotoldquoInvolvement of forebrain in parabrachial neuronal activationinduced by aversively conditioned taste stimuli in the ratrdquo BrainResearch vol 1141 no 1 pp 188ndash196 2007

[26] T Yamamoto and K Sawa ldquoc-Fos-like immunoreactivity in thebrainstem following gastric loads of various chemical solutionsin ratsrdquo Brain Research vol 866 no 1-2 pp 135ndash143 2000

10 ISRN Pain

[27] T Yamamoto and K Sawa ldquoComparison of c-Fos-like immu-noreactivity in the brainstem following intraoral and intragas-tric infusions of chemical solutions in ratsrdquo Brain Research vol866 no 1-2 pp 144ndash151 2000

[28] T YamamotoM Takemura T Inui et al ldquoFunctional organiza-tion of the rodent parabrachial nucleusrdquoAnnals of the New YorkAcademy of Sciences vol 1170 pp 378ndash382 2009

[29] B J Sessle ldquoNeural mechanisms and pathways in craniofacialpainrdquo Canadian Journal of Neurological Sciences vol 26 no 3pp S7ndashS11 1999

[30] R Nieuwenhuys J Voogd and C H R van Huijzen EdsTheHuman Central Nervous System A Synopsis and Atlas SpringerBerlin Germany 1978

[31] H Burton A D Craig Jr D A Poulos and J T Molt ldquoEfferentprojections from temperature sensitive recording loci withinthe marginal zone of the nucleus caudalis of the spinal trigem-inal complex in the catrdquo Journal of Comparative Neurology vol183 no 4 pp 753ndash777 1979

[32] H Burton and A D Loewy ldquoDescending projections from themarginal cell layer and other regions of themonkey spinal cordrdquoBrain Research vol 116 no 3 pp 485ndash491 1976

[33] C E Catsman-Berrevoets and H G J M Kuypers ldquoCells oforigin of cortical projections to dorsal column nuclei spinalcord and bulbar medial reticular formation in the rhesusmonkeyrdquoNeuroscience Letters vol 3 no 5-6 pp 245ndash252 1976

[34] H G J M Kuypers and V A Maisky ldquoRetrograde axonaltransport of horseradish peroxidase from spinal cord to brainstem cell groups in the catrdquo Neuroscience Letters vol 1 no 1pp 9ndash14 1975

[35] D A Ruggiero C A Ross and D J Reis ldquoProjections from thespinal trigeminal nucleus to the entire length of the spinal cordin the ratrdquo Brain Research vol 225 no 2 pp 225ndash233 1981

Submit your manuscripts athttpwwwhindawicom

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Behavioural Neurology

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Parkinsonrsquos Disease

Evidence-Based Complementary and Alternative Medicine

Volume 2014Hindawi Publishing Corporationhttpwwwhindawicom

Page 3: Research Article Neural Mechanisms That Underlie Angina ...downloads.hindawi.com/archive/2013/671503.pdf · angina-induced referred pain. It is of particular interest to examine such

ISRN Pain 3

days The samples were then stored in a cryoprotected 30sucrose solution in 01M phosphate-buffered saline (PH 74)at 4∘C for 3ndash7 days Consecutive transverse 50 120583m sectionswere cut using a cryostat (IEC) at minus20∘C and then transferredimmediately to ten alternatewells of polypropylene plates thatcontained PBS The sections were washed three times in PBSfor 10min each and were then incubated in 3 H

2O2for

30min to stop endogenous peroxidase activity The sectionswere again washed three times for 10min each in PBS Thesections were then incubated in a blocking solution thatcontained 3 normal goat serum (NGS) (Vertor Labora-tories USA) for 30min The sections were then incubatedovernight in c-Fos antibody that was taken from rabbits(1 5000 SC-52 Santa Cruz biotechnology CA USA) at4∘C This incubation caused no cross-reactivity with the Junprotein (Oncogene) At the completion of this incubation thesections were washed in cold PBS three times for 10min eachat room temperature and then incubated with biotinylatedanti-rabbit IgG (1 1000 Dako) for 120min and peroxidase-conjugated streptavidin (1 1000 Dako) for 60min at roomtemperature All of the antibodies were diluted with PBSwhich contained 1 normal goat serum and 05 TritonX-100 For the peroxidase reaction 3101584031015840-diaminobenzidinetetrahydrochloride (DAB Sigma) with nickel ammoniumsulfate intensification was used The sections were mountedon slides air-dried overnight and then counter-stained withneutral red when necessary Finally coverslips were appliedto the slides

26 Vagotomy and Spinal Cord Lesion For the vagotomya tie was gently pulled around the nerve and then the leftand right cervical vagus nerves were separated from thecarotid artery and cut with a scissors In a second group ofanimals the involvement of C1-C2 neurons in PPS-inducedreferred pain in the trigeminal nerve territory was examinedby lesioning the C1-C2 segments of the spinal cord usinga small knife without a laminectomy After the lesion wasperformed the exposed upper cervical enlargement of thespinal cord was covered with bone waxThemusculature andskin were sutured The animals were provided at least 30minrest after the procedure

27 Quantification and Statistical Analysis For each animalthe Fos-labeled cell profiles in 110 serial sections (916ndash1466mm caudal to bregma) including the trigeminal brain-stem sensory nuclear complex were counted at the lightmicroscope level and camera lucida drawings were made ofthe cells The trigeminal sensory nuclear complex is dividedinto the principal sensory trigeminal nucleus (Pr5VL) sub-nucleus oralis (Sp5O) subnucleus interpolaris (Sp5I) andsubnucleus caudalis (Sp5C) The nomenclature and nuclearboundaries were defined based on the atlas produced byPaxinos and Watson [21] For each nucleus of the TSNC thenumber of identified Fos-labeled cells was counted for everythree sections and the total number of Fos-labeled cells wascalculated for each rat

The data are represented as the mean plusmn SEM Statisticalanalyses were carried out using Studentrsquos paired 119905-test to

compare single groups before and after treatment The Fosdata were analyzed using one-way ANOVA (the multiplecomparison test) andor Studentrsquos 119905-test where applicable Adifference was accepted as significant when 119875 lt 005

3 Results

The animalrsquos mean blood pressure and heart rate afterurethane anesthesia were approximately 80ndash100mmHg and300ndash350min respectively To accomplish our objectivesspecial attention was given to the change in the mean bloodpressure and the electrocardiogram following the infusionof either PPS solution or saline into the pericardial sac Nosignificant changeswere observed in themean blood pressureand the electrocardiogram for all of the rats that were tested(data not shown) Based on this finding the influence ofthe infusion-withdrawal procedure of either PPS solution orsaline flush into the pericardial sac could be excluded in thepresent study

31 c-Fos Expression following the Infusion of PPS Solutioninto the Pericardial Sac Figure 1 shows the c-Fos expressionin the C2 spinal segments following the infusion of the PPSsolution into the pericardial sac The number of Fos-labeledcells in the C2 spinal segment was significantly higher inthe PPS-infused rats compared with the vehicle-infused anduninfused control rats In the present study data were usedonly from those animals whose number of Fos-labeled cellsin the C2 spinal segment increased following the infusionof PPS solution into the pericardial sac because several linesof electrophysiological studies have demonstrated that aninjection of algesic chemicals into the pericardial sac resultsin increased activity in C1-C2 STT cells [4ndash7]

In the TSNC Fos-like immunoreactivity was observed inthe PPS-infused rats (119899 = 4) in the vehicle-infused rats (119899 =4) and even in the untreated control rats (119899 = 4) Examplesof c-Fos expression are shown in Figure 2 and the numberof Fos-labeled cells is summarized in Figure 3 The numberof Fos-labeled cells for the Pr5 the Sp5O and the Sp5I didnot reveal significant differences across the treated groups Bycontrast for the Sp5C a significant increase in the number ofFos-labeled cells was observed bilaterally in the PPS-infusedrats No difference was observed in the number of increasedFos-labeled cells in the PPS-infused rats between the left andright Sp5C (Figures 3(a) and 3(b))

A comparison of the number of Fos-labeled cells in thesuperficial layers (marginal layer and substantia gelatinosa)and magnocellular layer in the Sp5C indicated that thenumber of Fos-labeled cells in the superficial layers was sig-nificantly higher than in the magnocellular layer (Figure 4)

32 Effects of Vagotomy or C1-C2 Spinal Cord Lesion on c-Fos Expression Following either the vagotomy or a spinalcord lesion the animalrsquos mean blood pressure and heart ratedid not significantly change compared to the values thatwere present before the surgical treatments although theytransiently increased after the lesion of the C1-C2 spinalsegments

4 ISRN Pain

(a)

(A)

(B)(b)

(A)

(B)

lowast

Num

ber o

f Fos

-labe

led

cells

0

2

4

6

8

10

12

14

1618

Control Vehicle PPS

Right side

lowast

Num

ber o

f Fos

-labe

led

cells

02468

1012141618

Control Vehicle PPS

Left side

Figure 1 (a-A) Photomicrograph of c-Fos expression in the C2 spinal segment of a PPS-infused rat The area bounded by the broken line ismagnified 10 diameter (a-B) A black spot indicates a Fos-labeled cell (black arrow) (b)The number of Fos-labeled cells in uninfused control(Control 119899 = 4) vehicle-infused (Vehicle 119899 = 4) or PPS-infused (PPS 119899 = 4) rats lowast119875 lt 005 significantly different from the number ofFos-labeled cells in vehicle-infused rats

For the PPS-infused rats (119899 = 6) the effects of thevagotomy on c-Fos expression in the C2 spinal segments andthe Sp5C are shown in a representative example in Figure 5and the number of Fos-labeled cells is compared betweenrats that did and did not receive the vagotomy in Figure 6A bilateral section of the cervical vagus nerves showed asignificant decrease in the number of Fos-labeled cells inboth the Sp5C and C2 spinal segments In particular no Fos-labeled cells were observed in the Sp5C In contrast the lesionof the C1-C2 spinal segments produced a significant increasein the number of Fos-labeled cells in the Sp5C This increasein the number of Fos-labeled cells was observed in both thePPS-infused (119899 = 6) and the vehicle-infused (119899 = 3) ratsExamples of c-Fos expression are shown in Figure 7 and thenumber of Fos-labeled cells is summarized in Figure 8

4 Discussion

In the present study special attention was given to the changeof the mean blood pressure and the heart rate followingboth the infusion of either PPS solution or saline into thepericardial sac and the surgical treatments which were eitherthe vagotomy or the spinal cord lesion The animalrsquos meanblood pressure and heart rate did not change significantly

compared to the values that were present before infusion orsurgical treatments although a slight decrease was observedFrom these findings the influence of the infusion-withdrawalprocedure of either PPS solution or saline flush into thepericardial sac was excluded from the present study as wasthe influence of surgical treatments

41 Involvement of the Sp5C in Angina-Induced Referred Painin the Trigeminal Nerve Territory Some electrophysiologicalstudies suggest that angina-induced referred pain in thetrigeminal nerve territory is attributed to the convergence ofboth inputs from the trigeminal nerve territory and inputsfrom the cardiac region to the C1-C2 STT cells [4ndash8] Thisconvergence explained themechanism that underlies referredpain in the trigeminal nerve territory associated with theangina pectoris Clinical or experimental evidence of thiseffect has not yet been found The present study was thefirst study to demonstrate that nociceptive signals from thecardiac region are input to the TSNC specifically to the Sp5C

To compare the number of Fos-labeled cells among thenuclei in the TSNC we counted the total number of Fos-labeled cells in each nucleus because each nucleus differed inarea Counting individual nuclei is considered an acceptable

ISRN Pain 5

Control Vehicle PPS

Pr5

Sp5O

Sp5I

Sp5C

600 120583m

Figure 2 Photomicrographs of c-Fos expression in the left TSNC of uninfused control (Control) vehicle-infused (Vehicle) or PPS-infused(PPS) rats Pr5 the principal sensory trigeminal nucleus Sp5O the subnucleus oralis Sp5I the subnucleus interpolaris Sp5C the subnucleuscaudalis

method for counting Fos-labeled cells in the trigeminal sen-sory nuclear complex [22ndash28] In the present study infusionof the PPS to the pericardial sac resulted in a significantincrease in Fos-labeled cells in the Sp5C but not in othernuclei The Sp5C is a component of the ascending sensorypathway that transmits nociceptive signals from the trigemi-nal nerve territory to the thalamus Nociceptive informationfrom the orofacial region is input to the Sp5C and thentransmits to the ventral posteromedial (VPM) nucleus of thethalamus Therefore it is likely that the activity of the Sp5Cneurons that is evoked by sensory signals from the cardiacregion induces referred pain that is generally associated

with an attack of angina pectoris in the orofacial regionAdditionally the unmyelinated afferent fibers that conductnociceptive signals terminate to the superficial layers in theSp5C [29] The result in the present study that the numberof Fos-labeled cells in superficial layers was significantlyhigher than that in the magnocellular layer suggests that thenociceptive signals from the cardiac region are transmitted tothe thalamus via the superficial layers of the Sp5C

42 Peripheral Afferents Conducting Nociceptive Signals to theSp5C The heart receives reciprocal double innervations ofthe cardiac sympathetic and vagus nerves Bilateral sections

6 ISRN Pain

0

5

10

15

20

25

30N

umbe

r of F

os-la

bele

d ce

lls

Pr5 Sp5O Sp5I Sp5C

Left side

ControlVehiclePPS

lowast

(a)

0

5

10

15

20

25

Num

ber o

f Fos

-labe

led

cells

Pr5 Sp5O Sp5I Sp5C

lowastRight side

ControlVehiclePPS

(b)

Figure 3 A comparison of the number of Fos-labeled cells across uninfused control (Control 119899 = 4) vehicle-infused (Vehicle 119899 = 4) andPPS-infused (PPS 119899 = 4) rats in the left (a) and right (b) TSNC Pr5 the principal sensory trigeminal nucleus Sp5O the subnucleus oralisSp5I the subnucleus interpolaris Sp5C the subnucleus caudalis Note that a significant increase in the number of Fos-labeled cells was onlyobserved in both sides of the Sp5C lowast119875 lt 005 significantly different from the number of Fos-labeled cells in vehicle-infused rats

Num

ber o

f Fos

-labe

led

cells

0

5

10

15

20

25

30

35

Superficial layersMagnocellular layer

Left side Right side

lowast

lowast

Figure 4 A comparison of the number of Fos-labeled cells betweenthe superficial and the magnocellular layers in the Sp5C Notethat the number of Fos-labeled cells in the superficial layers wassignificantly higher than in the magnocellular layer lowast119875 lt 005significantly different between two layers of the Sp5C

of the cervical vagus nerves completely reversed the c-Fos expression that was found in the Sp5C following theinfusion of the PPS solution into the pericardial sac Thisresult shows that the nociceptive signals from the cardiacregion to the Sp5C were conducted by the vagal afferentfibers Additionally a small amount of Fos-labeled cells wasobserved in the C2 spinal segment which indicates that c-Fosexpression may be induced by surgical procedures

Among the animals that received a lesion in the C1-C2spinal segments an increase in Fos-labeled cells in the Sp5Cwas observed in the vehicle-infused rats This result suggeststhat the lesion of the C1-C2 spinal segments influenced c-Fos expression in the Sp5C Therefore it is apparent that thelesion procedures affected the increase in Fos-labeled cells inthe PPS-infused rats Unfortunately we cannot explain thisphenomenon in the present study The rate of increase in theFos-labeled cells was greater in the PPS-infused rats than thatin the vehicle-infused rats For the animals that received theC1-C2 lesion the number of Fos-labeled cells was not reducedin the PPS-infused rats compared with the vehicle-inducedrats thus it is possible that the nociceptive signals from thecardiac region were input to the Sp5C via a neural pathwayin the brain but not via the spinal cord Unfortunately thelocation of this neural pathway was not identified in thepresent study In humans the vagal afferent signals from thevisceral organs including the cardiac region are not inputto the Sp5C although the vagal afferent signals from theskin of the ear concha are input to the Sp5C [30] Severalmorphological and electrophysiological studies have shownthat vagal afferent fibers and the nucleus tractus solitariusplay an important role in angina-induced referred pain in thetrigeminal nerve territory [4 5 7 14] This evidence suggeststhat the nociceptive signals from the cardiac region are inputto the Sp5C via the nucleus tractus solitarius However thepathway from the nucleus tractus solitarius to the Sp5C hasnot been confirmed in anatomical studies It is possible thatthe output signals from the nucleus tractus solitarius areprojected to the Sp5C by way of other nuclei in the brainThe existence of this possibility could not be clarified in thepresent study

ISRN Pain 7

(a)

(b)

(A) (B)

(A) (B)

200 120583m 100 120583m

200 120583m 200 120583m

Figure 5 Effects of vagotomy on c-Fos expression in PPS-infused ratsThe cervical vagus nerve was bilaterally sectioned Photomicrographsshow c-Fos expression in the left Sp5C (a) and the C2 spinal segment (b) Fos-labeled cells were observed in intact rats (a-A and b-A) TheFos-labeled cells were not observed in the vagotomy rats (a-B and b-B)

Num

ber o

f Fos

-labe

led

cells

0

10

20

30

40Sp5C

Left side Right side

lowast lowast

(a)

Num

ber o

f Fos

-labe

led

cells

Left side Right side

lowast lowast

0

5

10

15

20

25

30

C2 spinal segment

Intact ratsSectioned rats

(b)

Figure 6 A comparison of the number of Fos-labeled cells between the intact and vagotomy rats following an infusion of PPS solution Notethat c-Fos expression was significantly reversed by the vagotomy lowast119875 lt 005 significantly different between two groups of rats

8 ISRN Pain

600 120583m

(a)

(b)

(A) (B)

(A) (B)

Figure 7 Effects of the lesion of the C1-C2 spinal segments on c-Fos expression in vehicle-infused (a) and PPS-infused (b) ratsPhotomicrographs show c-Fos expression in the left Sp5C Fos-labeled cells were observed in the intact rats (a-A and b-A) The numberof Fos-labeled cells remarkably increased in the lesioned rats (a-B and b-B) compared with the intact rats

Left side Right side

Num

ber o

f Fos

-labe

led

cells

0

5

10

15

20Vehicle

lowast

(a)

Right sideLeft side

Intact ratsC1-C2 lesioned rats

Num

ber o

f Fos

-labe

led

cells

0

10

20

30

40

50

60 PPSlowast

lowast

(b)

Figure 8 A comparison of the number of Fos-labeled cells between intact and C1-C2-lesioned rats following an infusion of either vehicleor PPS solution Note that c-Fos expression significantly increased when the C1-C2 spinal segments were lesioned lowast119875 lt 005 significantlydifferent between two groups of rats

ISRN Pain 9

The descending projection from the Sp5C to the spinaldorsal horn has been demonstrated anatomically [31ndash35]Therefore the activation of Sp5C cells induced by nociceptivesignals from the cardiac region may explain the results fromprior studies that injection of algesic chemicals into thepericardial sac resulted in an increase in activity among theC1-C2 STT cells [4ndash7]

In conclusion nociceptive signals from the cardiac regionare input to the SP5C via an unknown pathway in the brainThese signals are transmitted to secondary neurons at thesuperficial layers in the Sp5C and then projected to thethalamusThis ascending pathway may contribute to angina-induced referred pain in the trigeminal nerve territory

Conflict of Interests

The authors have no conflict of interests to declare

Acknowledgments

The authors thank Dr Yumiko Hayashi for her criticalreading of the paper This work was supported in part by agrant from Daiichi-Sankyo Co Ltd

References

[1] R D Foreman ldquoMechanisms of cardiac painrdquo Annual Reviewof Physiology vol 61 pp 143ndash167 1999

[2] T C Ruch ldquoVisceral sensation and referred painrdquo in FultonHowellrsquos Textbook of Physiology pp 385ndash401 WB SaundersPhiladelphia Pa USA 15th edition 1946

[3] D E Myers ldquoVagus nerve pain referred to the craniofacialregion A case report and literature review with implications forreferred cardiac painrdquo The British Dental Journal vol 204 no4 pp 187ndash189 2008

[4] M J Chandler J Zhang and R D Foreman ldquoVagal sympa-thetic and somatic sensory inputs to upper cervical (C1-C3)spinothalamic tract neurons inmonkeysrdquo Journal of Neurophys-iology vol 76 no 4 pp 2555ndash2567 1996

[5] M J Chandler J Zhang and R D Foreman ldquoPericardialinjections of inflammatory chemicals excite upper cervical (C1-C3) spinothalamic tract (STT) cells in monkeysrdquo Society forNeuroscience vol 21 article 2604 1995

[6] R D Foreman and C Qin ldquoNeuromodulation of cardiac painand cerebral vasculature neural mechanismsrdquo Cleveland ClinicJournal of Medicine vol 76 pp S75ndashS79 2009

[7] C Qin M J Chandler K E Miller and R D ForemanldquoResponses and afferent pathways of superficial and deeper C1-C2 spinal cells to intrapericardial algogenic chemicals in ratsrdquoJournal of Neurophysiology vol 85 no 4 pp 1522ndash1532 2001

[8] D L McNeill M J Chandler Q G Fu and R D ForemanldquoProjection of nodose ganglion cells to the upper cervical spinalcord in the ratrdquoBrain Research Bulletin vol 27 no 2 pp 151ndash1551991

[9] B J Sessle ldquoPeripheral and central mechanisms of orofacialinflammatory painrdquo International Review of Neurobiology vol97 pp 179ndash206 2011

[10] B Greenwood-VanMeerveldMGibsonWGunter J ShepardR Foreman and D Myers ldquoStereotaxic delivery of corticos-terone to the amygdala modulates colonic sensitivity in ratsrdquoBrain Research vol 893 no 1-2 pp 135ndash142 2001

[11] W D Gunter J D Shepard R D Foreman D A Myers andB Greenwood-Van Meerveld ldquoEvidence for visceral hypersen-sitivity in high-anxiety ratsrdquo Physiology and Behavior vol 69no 3 pp 379ndash382 2000

[12] C Qin B Greenwood-Van Meerveld D A Myers and R DForeman ldquoCorticosterone acts directly at the amygdala to alterspinal neuronal activity in response to colorectal distensionrdquoJournal of Neurophysiology vol 89 no 3 pp 1343ndash1352 2003

[13] J C White and W H Seet Eds Pain and the NeurosurgeonCharles C Thomas Springfield Ill USA 1969

[14] F Hua T Harrison C Qin et al ldquoc-Fos expression in ratbrain stem and spinal cord in response to activation of car-diac ischemia-sensitive afferent neurons and electrostimulatorymodulationrdquo The American Journal of PhysiologymdashHeart andCirculatory Physiology vol 287 no 6 pp H2728ndashH2738 2004

[15] I Lindgren and H Olivecrona ldquoSurgical treatment of anginapectorisrdquo Journal of Neurosurgery vol 4 no 1 pp 19ndash39 1947

[16] J C White and E F Bland ldquoThe surgical relief of severe anginapectoris methods employed and endrdquo Medicine vol 27 no 1pp 1ndash42 1948

[17] M Zimmermann ldquoEthical guidelines for investigations ofexperimental pain in conscious animalsrdquo Pain vol 16 no 2 pp109ndash110 1983

[18] H O Handwerker and PW Reeh ldquoPain and inflammationrdquo inProceedings of the 5th World Congress on Pain M R Bond J ECharlton andC JWoolf Eds pp 59ndash70 Elsevier AmsterdamThe Netherlands 1991

[19] I Euchner-Wamser S T Meller and G F Gebhart ldquoA modelof cardiac nociception in chronically instrumented rats behav-ioral and electrophysiological effects of pericardial administra-tion of algogenic substancesrdquo Pain vol 58 no 1 pp 117ndash1281994

[20] S T Meller and G F Gebhart ldquoA critical review of the afferentpathways and the potential chemical mediators involved incardiac painrdquo Neuroscience vol 48 no 3 pp 501ndash524 1992

[21] G Paxinos and C Watson Eds The Rat Brain in StereotaxicCoodinates Academic Press New York NY USA 1998

[22] M E Edelsbrunner M Nakano and P Holzer ldquoAfferentsignalling from the acid-challenged rat stomach is inhibitedand gastric acid elimination is enhanced by lafutidinerdquo BMCGastroenterology vol 9 article 40 2009

[23] T Haino S Hironaka T Ooka et al ldquoOrosensory deprivationalters taste-elicited c-Fos expression in the parabrachial nucleusof neonatal ratsrdquo Neuroscience Research vol 67 no 3 pp 228ndash235 2010

[24] K Okamoto R Thompson A Tashiro Z Chang and D ABereiter ldquoBright light produces Fos-positive neurons in caudaltrigeminal brainstemrdquo Neuroscience vol 160 no 4 pp 858ndash864 2009

[25] K Tokita T Shimura S Nakamura T Inoue and T YamamotoldquoInvolvement of forebrain in parabrachial neuronal activationinduced by aversively conditioned taste stimuli in the ratrdquo BrainResearch vol 1141 no 1 pp 188ndash196 2007

[26] T Yamamoto and K Sawa ldquoc-Fos-like immunoreactivity in thebrainstem following gastric loads of various chemical solutionsin ratsrdquo Brain Research vol 866 no 1-2 pp 135ndash143 2000

10 ISRN Pain

[27] T Yamamoto and K Sawa ldquoComparison of c-Fos-like immu-noreactivity in the brainstem following intraoral and intragas-tric infusions of chemical solutions in ratsrdquo Brain Research vol866 no 1-2 pp 144ndash151 2000

[28] T YamamotoM Takemura T Inui et al ldquoFunctional organiza-tion of the rodent parabrachial nucleusrdquoAnnals of the New YorkAcademy of Sciences vol 1170 pp 378ndash382 2009

[29] B J Sessle ldquoNeural mechanisms and pathways in craniofacialpainrdquo Canadian Journal of Neurological Sciences vol 26 no 3pp S7ndashS11 1999

[30] R Nieuwenhuys J Voogd and C H R van Huijzen EdsTheHuman Central Nervous System A Synopsis and Atlas SpringerBerlin Germany 1978

[31] H Burton A D Craig Jr D A Poulos and J T Molt ldquoEfferentprojections from temperature sensitive recording loci withinthe marginal zone of the nucleus caudalis of the spinal trigem-inal complex in the catrdquo Journal of Comparative Neurology vol183 no 4 pp 753ndash777 1979

[32] H Burton and A D Loewy ldquoDescending projections from themarginal cell layer and other regions of themonkey spinal cordrdquoBrain Research vol 116 no 3 pp 485ndash491 1976

[33] C E Catsman-Berrevoets and H G J M Kuypers ldquoCells oforigin of cortical projections to dorsal column nuclei spinalcord and bulbar medial reticular formation in the rhesusmonkeyrdquoNeuroscience Letters vol 3 no 5-6 pp 245ndash252 1976

[34] H G J M Kuypers and V A Maisky ldquoRetrograde axonaltransport of horseradish peroxidase from spinal cord to brainstem cell groups in the catrdquo Neuroscience Letters vol 1 no 1pp 9ndash14 1975

[35] D A Ruggiero C A Ross and D J Reis ldquoProjections from thespinal trigeminal nucleus to the entire length of the spinal cordin the ratrdquo Brain Research vol 225 no 2 pp 225ndash233 1981

Submit your manuscripts athttpwwwhindawicom

Stem CellsInternational

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

MEDIATORSINFLAMMATION

of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Behavioural Neurology

EndocrinologyInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Disease Markers

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

BioMed Research International

OncologyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Oxidative Medicine and Cellular Longevity

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

PPAR Research

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Immunology ResearchHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

ObesityJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Computational and Mathematical Methods in Medicine

OphthalmologyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Diabetes ResearchJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Research and TreatmentAIDS

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Gastroenterology Research and Practice

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Parkinsonrsquos Disease

Evidence-Based Complementary and Alternative Medicine

Volume 2014Hindawi Publishing Corporationhttpwwwhindawicom

Page 4: Research Article Neural Mechanisms That Underlie Angina ...downloads.hindawi.com/archive/2013/671503.pdf · angina-induced referred pain. It is of particular interest to examine such

4 ISRN Pain

(a)

(A)

(B)(b)

(A)

(B)

lowast

Num

ber o

f Fos

-labe

led

cells

0

2

4

6

8

10

12

14

1618

Control Vehicle PPS

Right side

lowast

Num

ber o

f Fos

-labe

led

cells

02468

1012141618

Control Vehicle PPS

Left side

Figure 1 (a-A) Photomicrograph of c-Fos expression in the C2 spinal segment of a PPS-infused rat The area bounded by the broken line ismagnified 10 diameter (a-B) A black spot indicates a Fos-labeled cell (black arrow) (b)The number of Fos-labeled cells in uninfused control(Control 119899 = 4) vehicle-infused (Vehicle 119899 = 4) or PPS-infused (PPS 119899 = 4) rats lowast119875 lt 005 significantly different from the number ofFos-labeled cells in vehicle-infused rats

For the PPS-infused rats (119899 = 6) the effects of thevagotomy on c-Fos expression in the C2 spinal segments andthe Sp5C are shown in a representative example in Figure 5and the number of Fos-labeled cells is compared betweenrats that did and did not receive the vagotomy in Figure 6A bilateral section of the cervical vagus nerves showed asignificant decrease in the number of Fos-labeled cells inboth the Sp5C and C2 spinal segments In particular no Fos-labeled cells were observed in the Sp5C In contrast the lesionof the C1-C2 spinal segments produced a significant increasein the number of Fos-labeled cells in the Sp5C This increasein the number of Fos-labeled cells was observed in both thePPS-infused (119899 = 6) and the vehicle-infused (119899 = 3) ratsExamples of c-Fos expression are shown in Figure 7 and thenumber of Fos-labeled cells is summarized in Figure 8

4 Discussion

In the present study special attention was given to the changeof the mean blood pressure and the heart rate followingboth the infusion of either PPS solution or saline into thepericardial sac and the surgical treatments which were eitherthe vagotomy or the spinal cord lesion The animalrsquos meanblood pressure and heart rate did not change significantly

compared to the values that were present before infusion orsurgical treatments although a slight decrease was observedFrom these findings the influence of the infusion-withdrawalprocedure of either PPS solution or saline flush into thepericardial sac was excluded from the present study as wasthe influence of surgical treatments

41 Involvement of the Sp5C in Angina-Induced Referred Painin the Trigeminal Nerve Territory Some electrophysiologicalstudies suggest that angina-induced referred pain in thetrigeminal nerve territory is attributed to the convergence ofboth inputs from the trigeminal nerve territory and inputsfrom the cardiac region to the C1-C2 STT cells [4ndash8] Thisconvergence explained themechanism that underlies referredpain in the trigeminal nerve territory associated with theangina pectoris Clinical or experimental evidence of thiseffect has not yet been found The present study was thefirst study to demonstrate that nociceptive signals from thecardiac region are input to the TSNC specifically to the Sp5C

To compare the number of Fos-labeled cells among thenuclei in the TSNC we counted the total number of Fos-labeled cells in each nucleus because each nucleus differed inarea Counting individual nuclei is considered an acceptable

ISRN Pain 5

Control Vehicle PPS

Pr5

Sp5O

Sp5I

Sp5C

600 120583m

Figure 2 Photomicrographs of c-Fos expression in the left TSNC of uninfused control (Control) vehicle-infused (Vehicle) or PPS-infused(PPS) rats Pr5 the principal sensory trigeminal nucleus Sp5O the subnucleus oralis Sp5I the subnucleus interpolaris Sp5C the subnucleuscaudalis

method for counting Fos-labeled cells in the trigeminal sen-sory nuclear complex [22ndash28] In the present study infusionof the PPS to the pericardial sac resulted in a significantincrease in Fos-labeled cells in the Sp5C but not in othernuclei The Sp5C is a component of the ascending sensorypathway that transmits nociceptive signals from the trigemi-nal nerve territory to the thalamus Nociceptive informationfrom the orofacial region is input to the Sp5C and thentransmits to the ventral posteromedial (VPM) nucleus of thethalamus Therefore it is likely that the activity of the Sp5Cneurons that is evoked by sensory signals from the cardiacregion induces referred pain that is generally associated

with an attack of angina pectoris in the orofacial regionAdditionally the unmyelinated afferent fibers that conductnociceptive signals terminate to the superficial layers in theSp5C [29] The result in the present study that the numberof Fos-labeled cells in superficial layers was significantlyhigher than that in the magnocellular layer suggests that thenociceptive signals from the cardiac region are transmitted tothe thalamus via the superficial layers of the Sp5C

42 Peripheral Afferents Conducting Nociceptive Signals to theSp5C The heart receives reciprocal double innervations ofthe cardiac sympathetic and vagus nerves Bilateral sections

6 ISRN Pain

0

5

10

15

20

25

30N

umbe

r of F

os-la

bele

d ce

lls

Pr5 Sp5O Sp5I Sp5C

Left side

ControlVehiclePPS

lowast

(a)

0

5

10

15

20

25

Num

ber o

f Fos

-labe

led

cells

Pr5 Sp5O Sp5I Sp5C

lowastRight side

ControlVehiclePPS

(b)

Figure 3 A comparison of the number of Fos-labeled cells across uninfused control (Control 119899 = 4) vehicle-infused (Vehicle 119899 = 4) andPPS-infused (PPS 119899 = 4) rats in the left (a) and right (b) TSNC Pr5 the principal sensory trigeminal nucleus Sp5O the subnucleus oralisSp5I the subnucleus interpolaris Sp5C the subnucleus caudalis Note that a significant increase in the number of Fos-labeled cells was onlyobserved in both sides of the Sp5C lowast119875 lt 005 significantly different from the number of Fos-labeled cells in vehicle-infused rats

Num

ber o

f Fos

-labe

led

cells

0

5

10

15

20

25

30

35

Superficial layersMagnocellular layer

Left side Right side

lowast

lowast

Figure 4 A comparison of the number of Fos-labeled cells betweenthe superficial and the magnocellular layers in the Sp5C Notethat the number of Fos-labeled cells in the superficial layers wassignificantly higher than in the magnocellular layer lowast119875 lt 005significantly different between two layers of the Sp5C

of the cervical vagus nerves completely reversed the c-Fos expression that was found in the Sp5C following theinfusion of the PPS solution into the pericardial sac Thisresult shows that the nociceptive signals from the cardiacregion to the Sp5C were conducted by the vagal afferentfibers Additionally a small amount of Fos-labeled cells wasobserved in the C2 spinal segment which indicates that c-Fosexpression may be induced by surgical procedures

Among the animals that received a lesion in the C1-C2spinal segments an increase in Fos-labeled cells in the Sp5Cwas observed in the vehicle-infused rats This result suggeststhat the lesion of the C1-C2 spinal segments influenced c-Fos expression in the Sp5C Therefore it is apparent that thelesion procedures affected the increase in Fos-labeled cells inthe PPS-infused rats Unfortunately we cannot explain thisphenomenon in the present study The rate of increase in theFos-labeled cells was greater in the PPS-infused rats than thatin the vehicle-infused rats For the animals that received theC1-C2 lesion the number of Fos-labeled cells was not reducedin the PPS-infused rats compared with the vehicle-inducedrats thus it is possible that the nociceptive signals from thecardiac region were input to the Sp5C via a neural pathwayin the brain but not via the spinal cord Unfortunately thelocation of this neural pathway was not identified in thepresent study In humans the vagal afferent signals from thevisceral organs including the cardiac region are not inputto the Sp5C although the vagal afferent signals from theskin of the ear concha are input to the Sp5C [30] Severalmorphological and electrophysiological studies have shownthat vagal afferent fibers and the nucleus tractus solitariusplay an important role in angina-induced referred pain in thetrigeminal nerve territory [4 5 7 14] This evidence suggeststhat the nociceptive signals from the cardiac region are inputto the Sp5C via the nucleus tractus solitarius However thepathway from the nucleus tractus solitarius to the Sp5C hasnot been confirmed in anatomical studies It is possible thatthe output signals from the nucleus tractus solitarius areprojected to the Sp5C by way of other nuclei in the brainThe existence of this possibility could not be clarified in thepresent study

ISRN Pain 7

(a)

(b)

(A) (B)

(A) (B)

200 120583m 100 120583m

200 120583m 200 120583m

Figure 5 Effects of vagotomy on c-Fos expression in PPS-infused ratsThe cervical vagus nerve was bilaterally sectioned Photomicrographsshow c-Fos expression in the left Sp5C (a) and the C2 spinal segment (b) Fos-labeled cells were observed in intact rats (a-A and b-A) TheFos-labeled cells were not observed in the vagotomy rats (a-B and b-B)

Num

ber o

f Fos

-labe

led

cells

0

10

20

30

40Sp5C

Left side Right side

lowast lowast

(a)

Num

ber o

f Fos

-labe

led

cells

Left side Right side

lowast lowast

0

5

10

15

20

25

30

C2 spinal segment

Intact ratsSectioned rats

(b)

Figure 6 A comparison of the number of Fos-labeled cells between the intact and vagotomy rats following an infusion of PPS solution Notethat c-Fos expression was significantly reversed by the vagotomy lowast119875 lt 005 significantly different between two groups of rats

8 ISRN Pain

600 120583m

(a)

(b)

(A) (B)

(A) (B)

Figure 7 Effects of the lesion of the C1-C2 spinal segments on c-Fos expression in vehicle-infused (a) and PPS-infused (b) ratsPhotomicrographs show c-Fos expression in the left Sp5C Fos-labeled cells were observed in the intact rats (a-A and b-A) The numberof Fos-labeled cells remarkably increased in the lesioned rats (a-B and b-B) compared with the intact rats

Left side Right side

Num

ber o

f Fos

-labe

led

cells

0

5

10

15

20Vehicle

lowast

(a)

Right sideLeft side

Intact ratsC1-C2 lesioned rats

Num

ber o

f Fos

-labe

led

cells

0

10

20

30

40

50

60 PPSlowast

lowast

(b)

Figure 8 A comparison of the number of Fos-labeled cells between intact and C1-C2-lesioned rats following an infusion of either vehicleor PPS solution Note that c-Fos expression significantly increased when the C1-C2 spinal segments were lesioned lowast119875 lt 005 significantlydifferent between two groups of rats

ISRN Pain 9

The descending projection from the Sp5C to the spinaldorsal horn has been demonstrated anatomically [31ndash35]Therefore the activation of Sp5C cells induced by nociceptivesignals from the cardiac region may explain the results fromprior studies that injection of algesic chemicals into thepericardial sac resulted in an increase in activity among theC1-C2 STT cells [4ndash7]

In conclusion nociceptive signals from the cardiac regionare input to the SP5C via an unknown pathway in the brainThese signals are transmitted to secondary neurons at thesuperficial layers in the Sp5C and then projected to thethalamusThis ascending pathway may contribute to angina-induced referred pain in the trigeminal nerve territory

Conflict of Interests

The authors have no conflict of interests to declare

Acknowledgments

The authors thank Dr Yumiko Hayashi for her criticalreading of the paper This work was supported in part by agrant from Daiichi-Sankyo Co Ltd

References

[1] R D Foreman ldquoMechanisms of cardiac painrdquo Annual Reviewof Physiology vol 61 pp 143ndash167 1999

[2] T C Ruch ldquoVisceral sensation and referred painrdquo in FultonHowellrsquos Textbook of Physiology pp 385ndash401 WB SaundersPhiladelphia Pa USA 15th edition 1946

[3] D E Myers ldquoVagus nerve pain referred to the craniofacialregion A case report and literature review with implications forreferred cardiac painrdquo The British Dental Journal vol 204 no4 pp 187ndash189 2008

[4] M J Chandler J Zhang and R D Foreman ldquoVagal sympa-thetic and somatic sensory inputs to upper cervical (C1-C3)spinothalamic tract neurons inmonkeysrdquo Journal of Neurophys-iology vol 76 no 4 pp 2555ndash2567 1996

[5] M J Chandler J Zhang and R D Foreman ldquoPericardialinjections of inflammatory chemicals excite upper cervical (C1-C3) spinothalamic tract (STT) cells in monkeysrdquo Society forNeuroscience vol 21 article 2604 1995

[6] R D Foreman and C Qin ldquoNeuromodulation of cardiac painand cerebral vasculature neural mechanismsrdquo Cleveland ClinicJournal of Medicine vol 76 pp S75ndashS79 2009

[7] C Qin M J Chandler K E Miller and R D ForemanldquoResponses and afferent pathways of superficial and deeper C1-C2 spinal cells to intrapericardial algogenic chemicals in ratsrdquoJournal of Neurophysiology vol 85 no 4 pp 1522ndash1532 2001

[8] D L McNeill M J Chandler Q G Fu and R D ForemanldquoProjection of nodose ganglion cells to the upper cervical spinalcord in the ratrdquoBrain Research Bulletin vol 27 no 2 pp 151ndash1551991

[9] B J Sessle ldquoPeripheral and central mechanisms of orofacialinflammatory painrdquo International Review of Neurobiology vol97 pp 179ndash206 2011

[10] B Greenwood-VanMeerveldMGibsonWGunter J ShepardR Foreman and D Myers ldquoStereotaxic delivery of corticos-terone to the amygdala modulates colonic sensitivity in ratsrdquoBrain Research vol 893 no 1-2 pp 135ndash142 2001

[11] W D Gunter J D Shepard R D Foreman D A Myers andB Greenwood-Van Meerveld ldquoEvidence for visceral hypersen-sitivity in high-anxiety ratsrdquo Physiology and Behavior vol 69no 3 pp 379ndash382 2000

[12] C Qin B Greenwood-Van Meerveld D A Myers and R DForeman ldquoCorticosterone acts directly at the amygdala to alterspinal neuronal activity in response to colorectal distensionrdquoJournal of Neurophysiology vol 89 no 3 pp 1343ndash1352 2003

[13] J C White and W H Seet Eds Pain and the NeurosurgeonCharles C Thomas Springfield Ill USA 1969

[14] F Hua T Harrison C Qin et al ldquoc-Fos expression in ratbrain stem and spinal cord in response to activation of car-diac ischemia-sensitive afferent neurons and electrostimulatorymodulationrdquo The American Journal of PhysiologymdashHeart andCirculatory Physiology vol 287 no 6 pp H2728ndashH2738 2004

[15] I Lindgren and H Olivecrona ldquoSurgical treatment of anginapectorisrdquo Journal of Neurosurgery vol 4 no 1 pp 19ndash39 1947

[16] J C White and E F Bland ldquoThe surgical relief of severe anginapectoris methods employed and endrdquo Medicine vol 27 no 1pp 1ndash42 1948

[17] M Zimmermann ldquoEthical guidelines for investigations ofexperimental pain in conscious animalsrdquo Pain vol 16 no 2 pp109ndash110 1983

[18] H O Handwerker and PW Reeh ldquoPain and inflammationrdquo inProceedings of the 5th World Congress on Pain M R Bond J ECharlton andC JWoolf Eds pp 59ndash70 Elsevier AmsterdamThe Netherlands 1991

[19] I Euchner-Wamser S T Meller and G F Gebhart ldquoA modelof cardiac nociception in chronically instrumented rats behav-ioral and electrophysiological effects of pericardial administra-tion of algogenic substancesrdquo Pain vol 58 no 1 pp 117ndash1281994

[20] S T Meller and G F Gebhart ldquoA critical review of the afferentpathways and the potential chemical mediators involved incardiac painrdquo Neuroscience vol 48 no 3 pp 501ndash524 1992

[21] G Paxinos and C Watson Eds The Rat Brain in StereotaxicCoodinates Academic Press New York NY USA 1998

[22] M E Edelsbrunner M Nakano and P Holzer ldquoAfferentsignalling from the acid-challenged rat stomach is inhibitedand gastric acid elimination is enhanced by lafutidinerdquo BMCGastroenterology vol 9 article 40 2009

[23] T Haino S Hironaka T Ooka et al ldquoOrosensory deprivationalters taste-elicited c-Fos expression in the parabrachial nucleusof neonatal ratsrdquo Neuroscience Research vol 67 no 3 pp 228ndash235 2010

[24] K Okamoto R Thompson A Tashiro Z Chang and D ABereiter ldquoBright light produces Fos-positive neurons in caudaltrigeminal brainstemrdquo Neuroscience vol 160 no 4 pp 858ndash864 2009

[25] K Tokita T Shimura S Nakamura T Inoue and T YamamotoldquoInvolvement of forebrain in parabrachial neuronal activationinduced by aversively conditioned taste stimuli in the ratrdquo BrainResearch vol 1141 no 1 pp 188ndash196 2007

[26] T Yamamoto and K Sawa ldquoc-Fos-like immunoreactivity in thebrainstem following gastric loads of various chemical solutionsin ratsrdquo Brain Research vol 866 no 1-2 pp 135ndash143 2000

10 ISRN Pain

[27] T Yamamoto and K Sawa ldquoComparison of c-Fos-like immu-noreactivity in the brainstem following intraoral and intragas-tric infusions of chemical solutions in ratsrdquo Brain Research vol866 no 1-2 pp 144ndash151 2000

[28] T YamamotoM Takemura T Inui et al ldquoFunctional organiza-tion of the rodent parabrachial nucleusrdquoAnnals of the New YorkAcademy of Sciences vol 1170 pp 378ndash382 2009

[29] B J Sessle ldquoNeural mechanisms and pathways in craniofacialpainrdquo Canadian Journal of Neurological Sciences vol 26 no 3pp S7ndashS11 1999

[30] R Nieuwenhuys J Voogd and C H R van Huijzen EdsTheHuman Central Nervous System A Synopsis and Atlas SpringerBerlin Germany 1978

[31] H Burton A D Craig Jr D A Poulos and J T Molt ldquoEfferentprojections from temperature sensitive recording loci withinthe marginal zone of the nucleus caudalis of the spinal trigem-inal complex in the catrdquo Journal of Comparative Neurology vol183 no 4 pp 753ndash777 1979

[32] H Burton and A D Loewy ldquoDescending projections from themarginal cell layer and other regions of themonkey spinal cordrdquoBrain Research vol 116 no 3 pp 485ndash491 1976

[33] C E Catsman-Berrevoets and H G J M Kuypers ldquoCells oforigin of cortical projections to dorsal column nuclei spinalcord and bulbar medial reticular formation in the rhesusmonkeyrdquoNeuroscience Letters vol 3 no 5-6 pp 245ndash252 1976

[34] H G J M Kuypers and V A Maisky ldquoRetrograde axonaltransport of horseradish peroxidase from spinal cord to brainstem cell groups in the catrdquo Neuroscience Letters vol 1 no 1pp 9ndash14 1975

[35] D A Ruggiero C A Ross and D J Reis ldquoProjections from thespinal trigeminal nucleus to the entire length of the spinal cordin the ratrdquo Brain Research vol 225 no 2 pp 225ndash233 1981

Submit your manuscripts athttpwwwhindawicom

Stem CellsInternational

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

MEDIATORSINFLAMMATION

of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Behavioural Neurology

EndocrinologyInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Disease Markers

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

BioMed Research International

OncologyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Oxidative Medicine and Cellular Longevity

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

PPAR Research

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Immunology ResearchHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

ObesityJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Computational and Mathematical Methods in Medicine

OphthalmologyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Diabetes ResearchJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Research and TreatmentAIDS

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Gastroenterology Research and Practice

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Parkinsonrsquos Disease

Evidence-Based Complementary and Alternative Medicine

Volume 2014Hindawi Publishing Corporationhttpwwwhindawicom

Page 5: Research Article Neural Mechanisms That Underlie Angina ...downloads.hindawi.com/archive/2013/671503.pdf · angina-induced referred pain. It is of particular interest to examine such

ISRN Pain 5

Control Vehicle PPS

Pr5

Sp5O

Sp5I

Sp5C

600 120583m

Figure 2 Photomicrographs of c-Fos expression in the left TSNC of uninfused control (Control) vehicle-infused (Vehicle) or PPS-infused(PPS) rats Pr5 the principal sensory trigeminal nucleus Sp5O the subnucleus oralis Sp5I the subnucleus interpolaris Sp5C the subnucleuscaudalis

method for counting Fos-labeled cells in the trigeminal sen-sory nuclear complex [22ndash28] In the present study infusionof the PPS to the pericardial sac resulted in a significantincrease in Fos-labeled cells in the Sp5C but not in othernuclei The Sp5C is a component of the ascending sensorypathway that transmits nociceptive signals from the trigemi-nal nerve territory to the thalamus Nociceptive informationfrom the orofacial region is input to the Sp5C and thentransmits to the ventral posteromedial (VPM) nucleus of thethalamus Therefore it is likely that the activity of the Sp5Cneurons that is evoked by sensory signals from the cardiacregion induces referred pain that is generally associated

with an attack of angina pectoris in the orofacial regionAdditionally the unmyelinated afferent fibers that conductnociceptive signals terminate to the superficial layers in theSp5C [29] The result in the present study that the numberof Fos-labeled cells in superficial layers was significantlyhigher than that in the magnocellular layer suggests that thenociceptive signals from the cardiac region are transmitted tothe thalamus via the superficial layers of the Sp5C

42 Peripheral Afferents Conducting Nociceptive Signals to theSp5C The heart receives reciprocal double innervations ofthe cardiac sympathetic and vagus nerves Bilateral sections

6 ISRN Pain

0

5

10

15

20

25

30N

umbe

r of F

os-la

bele

d ce

lls

Pr5 Sp5O Sp5I Sp5C

Left side

ControlVehiclePPS

lowast

(a)

0

5

10

15

20

25

Num

ber o

f Fos

-labe

led

cells

Pr5 Sp5O Sp5I Sp5C

lowastRight side

ControlVehiclePPS

(b)

Figure 3 A comparison of the number of Fos-labeled cells across uninfused control (Control 119899 = 4) vehicle-infused (Vehicle 119899 = 4) andPPS-infused (PPS 119899 = 4) rats in the left (a) and right (b) TSNC Pr5 the principal sensory trigeminal nucleus Sp5O the subnucleus oralisSp5I the subnucleus interpolaris Sp5C the subnucleus caudalis Note that a significant increase in the number of Fos-labeled cells was onlyobserved in both sides of the Sp5C lowast119875 lt 005 significantly different from the number of Fos-labeled cells in vehicle-infused rats

Num

ber o

f Fos

-labe

led

cells

0

5

10

15

20

25

30

35

Superficial layersMagnocellular layer

Left side Right side

lowast

lowast

Figure 4 A comparison of the number of Fos-labeled cells betweenthe superficial and the magnocellular layers in the Sp5C Notethat the number of Fos-labeled cells in the superficial layers wassignificantly higher than in the magnocellular layer lowast119875 lt 005significantly different between two layers of the Sp5C

of the cervical vagus nerves completely reversed the c-Fos expression that was found in the Sp5C following theinfusion of the PPS solution into the pericardial sac Thisresult shows that the nociceptive signals from the cardiacregion to the Sp5C were conducted by the vagal afferentfibers Additionally a small amount of Fos-labeled cells wasobserved in the C2 spinal segment which indicates that c-Fosexpression may be induced by surgical procedures

Among the animals that received a lesion in the C1-C2spinal segments an increase in Fos-labeled cells in the Sp5Cwas observed in the vehicle-infused rats This result suggeststhat the lesion of the C1-C2 spinal segments influenced c-Fos expression in the Sp5C Therefore it is apparent that thelesion procedures affected the increase in Fos-labeled cells inthe PPS-infused rats Unfortunately we cannot explain thisphenomenon in the present study The rate of increase in theFos-labeled cells was greater in the PPS-infused rats than thatin the vehicle-infused rats For the animals that received theC1-C2 lesion the number of Fos-labeled cells was not reducedin the PPS-infused rats compared with the vehicle-inducedrats thus it is possible that the nociceptive signals from thecardiac region were input to the Sp5C via a neural pathwayin the brain but not via the spinal cord Unfortunately thelocation of this neural pathway was not identified in thepresent study In humans the vagal afferent signals from thevisceral organs including the cardiac region are not inputto the Sp5C although the vagal afferent signals from theskin of the ear concha are input to the Sp5C [30] Severalmorphological and electrophysiological studies have shownthat vagal afferent fibers and the nucleus tractus solitariusplay an important role in angina-induced referred pain in thetrigeminal nerve territory [4 5 7 14] This evidence suggeststhat the nociceptive signals from the cardiac region are inputto the Sp5C via the nucleus tractus solitarius However thepathway from the nucleus tractus solitarius to the Sp5C hasnot been confirmed in anatomical studies It is possible thatthe output signals from the nucleus tractus solitarius areprojected to the Sp5C by way of other nuclei in the brainThe existence of this possibility could not be clarified in thepresent study

ISRN Pain 7

(a)

(b)

(A) (B)

(A) (B)

200 120583m 100 120583m

200 120583m 200 120583m

Figure 5 Effects of vagotomy on c-Fos expression in PPS-infused ratsThe cervical vagus nerve was bilaterally sectioned Photomicrographsshow c-Fos expression in the left Sp5C (a) and the C2 spinal segment (b) Fos-labeled cells were observed in intact rats (a-A and b-A) TheFos-labeled cells were not observed in the vagotomy rats (a-B and b-B)

Num

ber o

f Fos

-labe

led

cells

0

10

20

30

40Sp5C

Left side Right side

lowast lowast

(a)

Num

ber o

f Fos

-labe

led

cells

Left side Right side

lowast lowast

0

5

10

15

20

25

30

C2 spinal segment

Intact ratsSectioned rats

(b)

Figure 6 A comparison of the number of Fos-labeled cells between the intact and vagotomy rats following an infusion of PPS solution Notethat c-Fos expression was significantly reversed by the vagotomy lowast119875 lt 005 significantly different between two groups of rats

8 ISRN Pain

600 120583m

(a)

(b)

(A) (B)

(A) (B)

Figure 7 Effects of the lesion of the C1-C2 spinal segments on c-Fos expression in vehicle-infused (a) and PPS-infused (b) ratsPhotomicrographs show c-Fos expression in the left Sp5C Fos-labeled cells were observed in the intact rats (a-A and b-A) The numberof Fos-labeled cells remarkably increased in the lesioned rats (a-B and b-B) compared with the intact rats

Left side Right side

Num

ber o

f Fos

-labe

led

cells

0

5

10

15

20Vehicle

lowast

(a)

Right sideLeft side

Intact ratsC1-C2 lesioned rats

Num

ber o

f Fos

-labe

led

cells

0

10

20

30

40

50

60 PPSlowast

lowast

(b)

Figure 8 A comparison of the number of Fos-labeled cells between intact and C1-C2-lesioned rats following an infusion of either vehicleor PPS solution Note that c-Fos expression significantly increased when the C1-C2 spinal segments were lesioned lowast119875 lt 005 significantlydifferent between two groups of rats

ISRN Pain 9

The descending projection from the Sp5C to the spinaldorsal horn has been demonstrated anatomically [31ndash35]Therefore the activation of Sp5C cells induced by nociceptivesignals from the cardiac region may explain the results fromprior studies that injection of algesic chemicals into thepericardial sac resulted in an increase in activity among theC1-C2 STT cells [4ndash7]

In conclusion nociceptive signals from the cardiac regionare input to the SP5C via an unknown pathway in the brainThese signals are transmitted to secondary neurons at thesuperficial layers in the Sp5C and then projected to thethalamusThis ascending pathway may contribute to angina-induced referred pain in the trigeminal nerve territory

Conflict of Interests

The authors have no conflict of interests to declare

Acknowledgments

The authors thank Dr Yumiko Hayashi for her criticalreading of the paper This work was supported in part by agrant from Daiichi-Sankyo Co Ltd

References

[1] R D Foreman ldquoMechanisms of cardiac painrdquo Annual Reviewof Physiology vol 61 pp 143ndash167 1999

[2] T C Ruch ldquoVisceral sensation and referred painrdquo in FultonHowellrsquos Textbook of Physiology pp 385ndash401 WB SaundersPhiladelphia Pa USA 15th edition 1946

[3] D E Myers ldquoVagus nerve pain referred to the craniofacialregion A case report and literature review with implications forreferred cardiac painrdquo The British Dental Journal vol 204 no4 pp 187ndash189 2008

[4] M J Chandler J Zhang and R D Foreman ldquoVagal sympa-thetic and somatic sensory inputs to upper cervical (C1-C3)spinothalamic tract neurons inmonkeysrdquo Journal of Neurophys-iology vol 76 no 4 pp 2555ndash2567 1996

[5] M J Chandler J Zhang and R D Foreman ldquoPericardialinjections of inflammatory chemicals excite upper cervical (C1-C3) spinothalamic tract (STT) cells in monkeysrdquo Society forNeuroscience vol 21 article 2604 1995

[6] R D Foreman and C Qin ldquoNeuromodulation of cardiac painand cerebral vasculature neural mechanismsrdquo Cleveland ClinicJournal of Medicine vol 76 pp S75ndashS79 2009

[7] C Qin M J Chandler K E Miller and R D ForemanldquoResponses and afferent pathways of superficial and deeper C1-C2 spinal cells to intrapericardial algogenic chemicals in ratsrdquoJournal of Neurophysiology vol 85 no 4 pp 1522ndash1532 2001

[8] D L McNeill M J Chandler Q G Fu and R D ForemanldquoProjection of nodose ganglion cells to the upper cervical spinalcord in the ratrdquoBrain Research Bulletin vol 27 no 2 pp 151ndash1551991

[9] B J Sessle ldquoPeripheral and central mechanisms of orofacialinflammatory painrdquo International Review of Neurobiology vol97 pp 179ndash206 2011

[10] B Greenwood-VanMeerveldMGibsonWGunter J ShepardR Foreman and D Myers ldquoStereotaxic delivery of corticos-terone to the amygdala modulates colonic sensitivity in ratsrdquoBrain Research vol 893 no 1-2 pp 135ndash142 2001

[11] W D Gunter J D Shepard R D Foreman D A Myers andB Greenwood-Van Meerveld ldquoEvidence for visceral hypersen-sitivity in high-anxiety ratsrdquo Physiology and Behavior vol 69no 3 pp 379ndash382 2000

[12] C Qin B Greenwood-Van Meerveld D A Myers and R DForeman ldquoCorticosterone acts directly at the amygdala to alterspinal neuronal activity in response to colorectal distensionrdquoJournal of Neurophysiology vol 89 no 3 pp 1343ndash1352 2003

[13] J C White and W H Seet Eds Pain and the NeurosurgeonCharles C Thomas Springfield Ill USA 1969

[14] F Hua T Harrison C Qin et al ldquoc-Fos expression in ratbrain stem and spinal cord in response to activation of car-diac ischemia-sensitive afferent neurons and electrostimulatorymodulationrdquo The American Journal of PhysiologymdashHeart andCirculatory Physiology vol 287 no 6 pp H2728ndashH2738 2004

[15] I Lindgren and H Olivecrona ldquoSurgical treatment of anginapectorisrdquo Journal of Neurosurgery vol 4 no 1 pp 19ndash39 1947

[16] J C White and E F Bland ldquoThe surgical relief of severe anginapectoris methods employed and endrdquo Medicine vol 27 no 1pp 1ndash42 1948

[17] M Zimmermann ldquoEthical guidelines for investigations ofexperimental pain in conscious animalsrdquo Pain vol 16 no 2 pp109ndash110 1983

[18] H O Handwerker and PW Reeh ldquoPain and inflammationrdquo inProceedings of the 5th World Congress on Pain M R Bond J ECharlton andC JWoolf Eds pp 59ndash70 Elsevier AmsterdamThe Netherlands 1991

[19] I Euchner-Wamser S T Meller and G F Gebhart ldquoA modelof cardiac nociception in chronically instrumented rats behav-ioral and electrophysiological effects of pericardial administra-tion of algogenic substancesrdquo Pain vol 58 no 1 pp 117ndash1281994

[20] S T Meller and G F Gebhart ldquoA critical review of the afferentpathways and the potential chemical mediators involved incardiac painrdquo Neuroscience vol 48 no 3 pp 501ndash524 1992

[21] G Paxinos and C Watson Eds The Rat Brain in StereotaxicCoodinates Academic Press New York NY USA 1998

[22] M E Edelsbrunner M Nakano and P Holzer ldquoAfferentsignalling from the acid-challenged rat stomach is inhibitedand gastric acid elimination is enhanced by lafutidinerdquo BMCGastroenterology vol 9 article 40 2009

[23] T Haino S Hironaka T Ooka et al ldquoOrosensory deprivationalters taste-elicited c-Fos expression in the parabrachial nucleusof neonatal ratsrdquo Neuroscience Research vol 67 no 3 pp 228ndash235 2010

[24] K Okamoto R Thompson A Tashiro Z Chang and D ABereiter ldquoBright light produces Fos-positive neurons in caudaltrigeminal brainstemrdquo Neuroscience vol 160 no 4 pp 858ndash864 2009

[25] K Tokita T Shimura S Nakamura T Inoue and T YamamotoldquoInvolvement of forebrain in parabrachial neuronal activationinduced by aversively conditioned taste stimuli in the ratrdquo BrainResearch vol 1141 no 1 pp 188ndash196 2007

[26] T Yamamoto and K Sawa ldquoc-Fos-like immunoreactivity in thebrainstem following gastric loads of various chemical solutionsin ratsrdquo Brain Research vol 866 no 1-2 pp 135ndash143 2000

10 ISRN Pain

[27] T Yamamoto and K Sawa ldquoComparison of c-Fos-like immu-noreactivity in the brainstem following intraoral and intragas-tric infusions of chemical solutions in ratsrdquo Brain Research vol866 no 1-2 pp 144ndash151 2000

[28] T YamamotoM Takemura T Inui et al ldquoFunctional organiza-tion of the rodent parabrachial nucleusrdquoAnnals of the New YorkAcademy of Sciences vol 1170 pp 378ndash382 2009

[29] B J Sessle ldquoNeural mechanisms and pathways in craniofacialpainrdquo Canadian Journal of Neurological Sciences vol 26 no 3pp S7ndashS11 1999

[30] R Nieuwenhuys J Voogd and C H R van Huijzen EdsTheHuman Central Nervous System A Synopsis and Atlas SpringerBerlin Germany 1978

[31] H Burton A D Craig Jr D A Poulos and J T Molt ldquoEfferentprojections from temperature sensitive recording loci withinthe marginal zone of the nucleus caudalis of the spinal trigem-inal complex in the catrdquo Journal of Comparative Neurology vol183 no 4 pp 753ndash777 1979

[32] H Burton and A D Loewy ldquoDescending projections from themarginal cell layer and other regions of themonkey spinal cordrdquoBrain Research vol 116 no 3 pp 485ndash491 1976

[33] C E Catsman-Berrevoets and H G J M Kuypers ldquoCells oforigin of cortical projections to dorsal column nuclei spinalcord and bulbar medial reticular formation in the rhesusmonkeyrdquoNeuroscience Letters vol 3 no 5-6 pp 245ndash252 1976

[34] H G J M Kuypers and V A Maisky ldquoRetrograde axonaltransport of horseradish peroxidase from spinal cord to brainstem cell groups in the catrdquo Neuroscience Letters vol 1 no 1pp 9ndash14 1975

[35] D A Ruggiero C A Ross and D J Reis ldquoProjections from thespinal trigeminal nucleus to the entire length of the spinal cordin the ratrdquo Brain Research vol 225 no 2 pp 225ndash233 1981

Submit your manuscripts athttpwwwhindawicom

Stem CellsInternational

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

MEDIATORSINFLAMMATION

of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Behavioural Neurology

EndocrinologyInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Disease Markers

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

BioMed Research International

OncologyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Oxidative Medicine and Cellular Longevity

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

PPAR Research

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Immunology ResearchHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

ObesityJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Computational and Mathematical Methods in Medicine

OphthalmologyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Diabetes ResearchJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Research and TreatmentAIDS

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Gastroenterology Research and Practice

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Parkinsonrsquos Disease

Evidence-Based Complementary and Alternative Medicine

Volume 2014Hindawi Publishing Corporationhttpwwwhindawicom

Page 6: Research Article Neural Mechanisms That Underlie Angina ...downloads.hindawi.com/archive/2013/671503.pdf · angina-induced referred pain. It is of particular interest to examine such

6 ISRN Pain

0

5

10

15

20

25

30N

umbe

r of F

os-la

bele

d ce

lls

Pr5 Sp5O Sp5I Sp5C

Left side

ControlVehiclePPS

lowast

(a)

0

5

10

15

20

25

Num

ber o

f Fos

-labe

led

cells

Pr5 Sp5O Sp5I Sp5C

lowastRight side

ControlVehiclePPS

(b)

Figure 3 A comparison of the number of Fos-labeled cells across uninfused control (Control 119899 = 4) vehicle-infused (Vehicle 119899 = 4) andPPS-infused (PPS 119899 = 4) rats in the left (a) and right (b) TSNC Pr5 the principal sensory trigeminal nucleus Sp5O the subnucleus oralisSp5I the subnucleus interpolaris Sp5C the subnucleus caudalis Note that a significant increase in the number of Fos-labeled cells was onlyobserved in both sides of the Sp5C lowast119875 lt 005 significantly different from the number of Fos-labeled cells in vehicle-infused rats

Num

ber o

f Fos

-labe

led

cells

0

5

10

15

20

25

30

35

Superficial layersMagnocellular layer

Left side Right side

lowast

lowast

Figure 4 A comparison of the number of Fos-labeled cells betweenthe superficial and the magnocellular layers in the Sp5C Notethat the number of Fos-labeled cells in the superficial layers wassignificantly higher than in the magnocellular layer lowast119875 lt 005significantly different between two layers of the Sp5C

of the cervical vagus nerves completely reversed the c-Fos expression that was found in the Sp5C following theinfusion of the PPS solution into the pericardial sac Thisresult shows that the nociceptive signals from the cardiacregion to the Sp5C were conducted by the vagal afferentfibers Additionally a small amount of Fos-labeled cells wasobserved in the C2 spinal segment which indicates that c-Fosexpression may be induced by surgical procedures

Among the animals that received a lesion in the C1-C2spinal segments an increase in Fos-labeled cells in the Sp5Cwas observed in the vehicle-infused rats This result suggeststhat the lesion of the C1-C2 spinal segments influenced c-Fos expression in the Sp5C Therefore it is apparent that thelesion procedures affected the increase in Fos-labeled cells inthe PPS-infused rats Unfortunately we cannot explain thisphenomenon in the present study The rate of increase in theFos-labeled cells was greater in the PPS-infused rats than thatin the vehicle-infused rats For the animals that received theC1-C2 lesion the number of Fos-labeled cells was not reducedin the PPS-infused rats compared with the vehicle-inducedrats thus it is possible that the nociceptive signals from thecardiac region were input to the Sp5C via a neural pathwayin the brain but not via the spinal cord Unfortunately thelocation of this neural pathway was not identified in thepresent study In humans the vagal afferent signals from thevisceral organs including the cardiac region are not inputto the Sp5C although the vagal afferent signals from theskin of the ear concha are input to the Sp5C [30] Severalmorphological and electrophysiological studies have shownthat vagal afferent fibers and the nucleus tractus solitariusplay an important role in angina-induced referred pain in thetrigeminal nerve territory [4 5 7 14] This evidence suggeststhat the nociceptive signals from the cardiac region are inputto the Sp5C via the nucleus tractus solitarius However thepathway from the nucleus tractus solitarius to the Sp5C hasnot been confirmed in anatomical studies It is possible thatthe output signals from the nucleus tractus solitarius areprojected to the Sp5C by way of other nuclei in the brainThe existence of this possibility could not be clarified in thepresent study

ISRN Pain 7

(a)

(b)

(A) (B)

(A) (B)

200 120583m 100 120583m

200 120583m 200 120583m

Figure 5 Effects of vagotomy on c-Fos expression in PPS-infused ratsThe cervical vagus nerve was bilaterally sectioned Photomicrographsshow c-Fos expression in the left Sp5C (a) and the C2 spinal segment (b) Fos-labeled cells were observed in intact rats (a-A and b-A) TheFos-labeled cells were not observed in the vagotomy rats (a-B and b-B)

Num

ber o

f Fos

-labe

led

cells

0

10

20

30

40Sp5C

Left side Right side

lowast lowast

(a)

Num

ber o

f Fos

-labe

led

cells

Left side Right side

lowast lowast

0

5

10

15

20

25

30

C2 spinal segment

Intact ratsSectioned rats

(b)

Figure 6 A comparison of the number of Fos-labeled cells between the intact and vagotomy rats following an infusion of PPS solution Notethat c-Fos expression was significantly reversed by the vagotomy lowast119875 lt 005 significantly different between two groups of rats

8 ISRN Pain

600 120583m

(a)

(b)

(A) (B)

(A) (B)

Figure 7 Effects of the lesion of the C1-C2 spinal segments on c-Fos expression in vehicle-infused (a) and PPS-infused (b) ratsPhotomicrographs show c-Fos expression in the left Sp5C Fos-labeled cells were observed in the intact rats (a-A and b-A) The numberof Fos-labeled cells remarkably increased in the lesioned rats (a-B and b-B) compared with the intact rats

Left side Right side

Num

ber o

f Fos

-labe

led

cells

0

5

10

15

20Vehicle

lowast

(a)

Right sideLeft side

Intact ratsC1-C2 lesioned rats

Num

ber o

f Fos

-labe

led

cells

0

10

20

30

40

50

60 PPSlowast

lowast

(b)

Figure 8 A comparison of the number of Fos-labeled cells between intact and C1-C2-lesioned rats following an infusion of either vehicleor PPS solution Note that c-Fos expression significantly increased when the C1-C2 spinal segments were lesioned lowast119875 lt 005 significantlydifferent between two groups of rats

ISRN Pain 9

The descending projection from the Sp5C to the spinaldorsal horn has been demonstrated anatomically [31ndash35]Therefore the activation of Sp5C cells induced by nociceptivesignals from the cardiac region may explain the results fromprior studies that injection of algesic chemicals into thepericardial sac resulted in an increase in activity among theC1-C2 STT cells [4ndash7]

In conclusion nociceptive signals from the cardiac regionare input to the SP5C via an unknown pathway in the brainThese signals are transmitted to secondary neurons at thesuperficial layers in the Sp5C and then projected to thethalamusThis ascending pathway may contribute to angina-induced referred pain in the trigeminal nerve territory

Conflict of Interests

The authors have no conflict of interests to declare

Acknowledgments

The authors thank Dr Yumiko Hayashi for her criticalreading of the paper This work was supported in part by agrant from Daiichi-Sankyo Co Ltd

References

[1] R D Foreman ldquoMechanisms of cardiac painrdquo Annual Reviewof Physiology vol 61 pp 143ndash167 1999

[2] T C Ruch ldquoVisceral sensation and referred painrdquo in FultonHowellrsquos Textbook of Physiology pp 385ndash401 WB SaundersPhiladelphia Pa USA 15th edition 1946

[3] D E Myers ldquoVagus nerve pain referred to the craniofacialregion A case report and literature review with implications forreferred cardiac painrdquo The British Dental Journal vol 204 no4 pp 187ndash189 2008

[4] M J Chandler J Zhang and R D Foreman ldquoVagal sympa-thetic and somatic sensory inputs to upper cervical (C1-C3)spinothalamic tract neurons inmonkeysrdquo Journal of Neurophys-iology vol 76 no 4 pp 2555ndash2567 1996

[5] M J Chandler J Zhang and R D Foreman ldquoPericardialinjections of inflammatory chemicals excite upper cervical (C1-C3) spinothalamic tract (STT) cells in monkeysrdquo Society forNeuroscience vol 21 article 2604 1995

[6] R D Foreman and C Qin ldquoNeuromodulation of cardiac painand cerebral vasculature neural mechanismsrdquo Cleveland ClinicJournal of Medicine vol 76 pp S75ndashS79 2009

[7] C Qin M J Chandler K E Miller and R D ForemanldquoResponses and afferent pathways of superficial and deeper C1-C2 spinal cells to intrapericardial algogenic chemicals in ratsrdquoJournal of Neurophysiology vol 85 no 4 pp 1522ndash1532 2001

[8] D L McNeill M J Chandler Q G Fu and R D ForemanldquoProjection of nodose ganglion cells to the upper cervical spinalcord in the ratrdquoBrain Research Bulletin vol 27 no 2 pp 151ndash1551991

[9] B J Sessle ldquoPeripheral and central mechanisms of orofacialinflammatory painrdquo International Review of Neurobiology vol97 pp 179ndash206 2011

[10] B Greenwood-VanMeerveldMGibsonWGunter J ShepardR Foreman and D Myers ldquoStereotaxic delivery of corticos-terone to the amygdala modulates colonic sensitivity in ratsrdquoBrain Research vol 893 no 1-2 pp 135ndash142 2001

[11] W D Gunter J D Shepard R D Foreman D A Myers andB Greenwood-Van Meerveld ldquoEvidence for visceral hypersen-sitivity in high-anxiety ratsrdquo Physiology and Behavior vol 69no 3 pp 379ndash382 2000

[12] C Qin B Greenwood-Van Meerveld D A Myers and R DForeman ldquoCorticosterone acts directly at the amygdala to alterspinal neuronal activity in response to colorectal distensionrdquoJournal of Neurophysiology vol 89 no 3 pp 1343ndash1352 2003

[13] J C White and W H Seet Eds Pain and the NeurosurgeonCharles C Thomas Springfield Ill USA 1969

[14] F Hua T Harrison C Qin et al ldquoc-Fos expression in ratbrain stem and spinal cord in response to activation of car-diac ischemia-sensitive afferent neurons and electrostimulatorymodulationrdquo The American Journal of PhysiologymdashHeart andCirculatory Physiology vol 287 no 6 pp H2728ndashH2738 2004

[15] I Lindgren and H Olivecrona ldquoSurgical treatment of anginapectorisrdquo Journal of Neurosurgery vol 4 no 1 pp 19ndash39 1947

[16] J C White and E F Bland ldquoThe surgical relief of severe anginapectoris methods employed and endrdquo Medicine vol 27 no 1pp 1ndash42 1948

[17] M Zimmermann ldquoEthical guidelines for investigations ofexperimental pain in conscious animalsrdquo Pain vol 16 no 2 pp109ndash110 1983

[18] H O Handwerker and PW Reeh ldquoPain and inflammationrdquo inProceedings of the 5th World Congress on Pain M R Bond J ECharlton andC JWoolf Eds pp 59ndash70 Elsevier AmsterdamThe Netherlands 1991

[19] I Euchner-Wamser S T Meller and G F Gebhart ldquoA modelof cardiac nociception in chronically instrumented rats behav-ioral and electrophysiological effects of pericardial administra-tion of algogenic substancesrdquo Pain vol 58 no 1 pp 117ndash1281994

[20] S T Meller and G F Gebhart ldquoA critical review of the afferentpathways and the potential chemical mediators involved incardiac painrdquo Neuroscience vol 48 no 3 pp 501ndash524 1992

[21] G Paxinos and C Watson Eds The Rat Brain in StereotaxicCoodinates Academic Press New York NY USA 1998

[22] M E Edelsbrunner M Nakano and P Holzer ldquoAfferentsignalling from the acid-challenged rat stomach is inhibitedand gastric acid elimination is enhanced by lafutidinerdquo BMCGastroenterology vol 9 article 40 2009

[23] T Haino S Hironaka T Ooka et al ldquoOrosensory deprivationalters taste-elicited c-Fos expression in the parabrachial nucleusof neonatal ratsrdquo Neuroscience Research vol 67 no 3 pp 228ndash235 2010

[24] K Okamoto R Thompson A Tashiro Z Chang and D ABereiter ldquoBright light produces Fos-positive neurons in caudaltrigeminal brainstemrdquo Neuroscience vol 160 no 4 pp 858ndash864 2009

[25] K Tokita T Shimura S Nakamura T Inoue and T YamamotoldquoInvolvement of forebrain in parabrachial neuronal activationinduced by aversively conditioned taste stimuli in the ratrdquo BrainResearch vol 1141 no 1 pp 188ndash196 2007

[26] T Yamamoto and K Sawa ldquoc-Fos-like immunoreactivity in thebrainstem following gastric loads of various chemical solutionsin ratsrdquo Brain Research vol 866 no 1-2 pp 135ndash143 2000

10 ISRN Pain

[27] T Yamamoto and K Sawa ldquoComparison of c-Fos-like immu-noreactivity in the brainstem following intraoral and intragas-tric infusions of chemical solutions in ratsrdquo Brain Research vol866 no 1-2 pp 144ndash151 2000

[28] T YamamotoM Takemura T Inui et al ldquoFunctional organiza-tion of the rodent parabrachial nucleusrdquoAnnals of the New YorkAcademy of Sciences vol 1170 pp 378ndash382 2009

[29] B J Sessle ldquoNeural mechanisms and pathways in craniofacialpainrdquo Canadian Journal of Neurological Sciences vol 26 no 3pp S7ndashS11 1999

[30] R Nieuwenhuys J Voogd and C H R van Huijzen EdsTheHuman Central Nervous System A Synopsis and Atlas SpringerBerlin Germany 1978

[31] H Burton A D Craig Jr D A Poulos and J T Molt ldquoEfferentprojections from temperature sensitive recording loci withinthe marginal zone of the nucleus caudalis of the spinal trigem-inal complex in the catrdquo Journal of Comparative Neurology vol183 no 4 pp 753ndash777 1979

[32] H Burton and A D Loewy ldquoDescending projections from themarginal cell layer and other regions of themonkey spinal cordrdquoBrain Research vol 116 no 3 pp 485ndash491 1976

[33] C E Catsman-Berrevoets and H G J M Kuypers ldquoCells oforigin of cortical projections to dorsal column nuclei spinalcord and bulbar medial reticular formation in the rhesusmonkeyrdquoNeuroscience Letters vol 3 no 5-6 pp 245ndash252 1976

[34] H G J M Kuypers and V A Maisky ldquoRetrograde axonaltransport of horseradish peroxidase from spinal cord to brainstem cell groups in the catrdquo Neuroscience Letters vol 1 no 1pp 9ndash14 1975

[35] D A Ruggiero C A Ross and D J Reis ldquoProjections from thespinal trigeminal nucleus to the entire length of the spinal cordin the ratrdquo Brain Research vol 225 no 2 pp 225ndash233 1981

Submit your manuscripts athttpwwwhindawicom

Stem CellsInternational

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

MEDIATORSINFLAMMATION

of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Behavioural Neurology

EndocrinologyInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Disease Markers

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

BioMed Research International

OncologyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Oxidative Medicine and Cellular Longevity

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

PPAR Research

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Immunology ResearchHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

ObesityJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Computational and Mathematical Methods in Medicine

OphthalmologyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Diabetes ResearchJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Research and TreatmentAIDS

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Gastroenterology Research and Practice

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Parkinsonrsquos Disease

Evidence-Based Complementary and Alternative Medicine

Volume 2014Hindawi Publishing Corporationhttpwwwhindawicom

Page 7: Research Article Neural Mechanisms That Underlie Angina ...downloads.hindawi.com/archive/2013/671503.pdf · angina-induced referred pain. It is of particular interest to examine such

ISRN Pain 7

(a)

(b)

(A) (B)

(A) (B)

200 120583m 100 120583m

200 120583m 200 120583m

Figure 5 Effects of vagotomy on c-Fos expression in PPS-infused ratsThe cervical vagus nerve was bilaterally sectioned Photomicrographsshow c-Fos expression in the left Sp5C (a) and the C2 spinal segment (b) Fos-labeled cells were observed in intact rats (a-A and b-A) TheFos-labeled cells were not observed in the vagotomy rats (a-B and b-B)

Num

ber o

f Fos

-labe

led

cells

0

10

20

30

40Sp5C

Left side Right side

lowast lowast

(a)

Num

ber o

f Fos

-labe

led

cells

Left side Right side

lowast lowast

0

5

10

15

20

25

30

C2 spinal segment

Intact ratsSectioned rats

(b)

Figure 6 A comparison of the number of Fos-labeled cells between the intact and vagotomy rats following an infusion of PPS solution Notethat c-Fos expression was significantly reversed by the vagotomy lowast119875 lt 005 significantly different between two groups of rats

8 ISRN Pain

600 120583m

(a)

(b)

(A) (B)

(A) (B)

Figure 7 Effects of the lesion of the C1-C2 spinal segments on c-Fos expression in vehicle-infused (a) and PPS-infused (b) ratsPhotomicrographs show c-Fos expression in the left Sp5C Fos-labeled cells were observed in the intact rats (a-A and b-A) The numberof Fos-labeled cells remarkably increased in the lesioned rats (a-B and b-B) compared with the intact rats

Left side Right side

Num

ber o

f Fos

-labe

led

cells

0

5

10

15

20Vehicle

lowast

(a)

Right sideLeft side

Intact ratsC1-C2 lesioned rats

Num

ber o

f Fos

-labe

led

cells

0

10

20

30

40

50

60 PPSlowast

lowast

(b)

Figure 8 A comparison of the number of Fos-labeled cells between intact and C1-C2-lesioned rats following an infusion of either vehicleor PPS solution Note that c-Fos expression significantly increased when the C1-C2 spinal segments were lesioned lowast119875 lt 005 significantlydifferent between two groups of rats

ISRN Pain 9

The descending projection from the Sp5C to the spinaldorsal horn has been demonstrated anatomically [31ndash35]Therefore the activation of Sp5C cells induced by nociceptivesignals from the cardiac region may explain the results fromprior studies that injection of algesic chemicals into thepericardial sac resulted in an increase in activity among theC1-C2 STT cells [4ndash7]

In conclusion nociceptive signals from the cardiac regionare input to the SP5C via an unknown pathway in the brainThese signals are transmitted to secondary neurons at thesuperficial layers in the Sp5C and then projected to thethalamusThis ascending pathway may contribute to angina-induced referred pain in the trigeminal nerve territory

Conflict of Interests

The authors have no conflict of interests to declare

Acknowledgments

The authors thank Dr Yumiko Hayashi for her criticalreading of the paper This work was supported in part by agrant from Daiichi-Sankyo Co Ltd

References

[1] R D Foreman ldquoMechanisms of cardiac painrdquo Annual Reviewof Physiology vol 61 pp 143ndash167 1999

[2] T C Ruch ldquoVisceral sensation and referred painrdquo in FultonHowellrsquos Textbook of Physiology pp 385ndash401 WB SaundersPhiladelphia Pa USA 15th edition 1946

[3] D E Myers ldquoVagus nerve pain referred to the craniofacialregion A case report and literature review with implications forreferred cardiac painrdquo The British Dental Journal vol 204 no4 pp 187ndash189 2008

[4] M J Chandler J Zhang and R D Foreman ldquoVagal sympa-thetic and somatic sensory inputs to upper cervical (C1-C3)spinothalamic tract neurons inmonkeysrdquo Journal of Neurophys-iology vol 76 no 4 pp 2555ndash2567 1996

[5] M J Chandler J Zhang and R D Foreman ldquoPericardialinjections of inflammatory chemicals excite upper cervical (C1-C3) spinothalamic tract (STT) cells in monkeysrdquo Society forNeuroscience vol 21 article 2604 1995

[6] R D Foreman and C Qin ldquoNeuromodulation of cardiac painand cerebral vasculature neural mechanismsrdquo Cleveland ClinicJournal of Medicine vol 76 pp S75ndashS79 2009

[7] C Qin M J Chandler K E Miller and R D ForemanldquoResponses and afferent pathways of superficial and deeper C1-C2 spinal cells to intrapericardial algogenic chemicals in ratsrdquoJournal of Neurophysiology vol 85 no 4 pp 1522ndash1532 2001

[8] D L McNeill M J Chandler Q G Fu and R D ForemanldquoProjection of nodose ganglion cells to the upper cervical spinalcord in the ratrdquoBrain Research Bulletin vol 27 no 2 pp 151ndash1551991

[9] B J Sessle ldquoPeripheral and central mechanisms of orofacialinflammatory painrdquo International Review of Neurobiology vol97 pp 179ndash206 2011

[10] B Greenwood-VanMeerveldMGibsonWGunter J ShepardR Foreman and D Myers ldquoStereotaxic delivery of corticos-terone to the amygdala modulates colonic sensitivity in ratsrdquoBrain Research vol 893 no 1-2 pp 135ndash142 2001

[11] W D Gunter J D Shepard R D Foreman D A Myers andB Greenwood-Van Meerveld ldquoEvidence for visceral hypersen-sitivity in high-anxiety ratsrdquo Physiology and Behavior vol 69no 3 pp 379ndash382 2000

[12] C Qin B Greenwood-Van Meerveld D A Myers and R DForeman ldquoCorticosterone acts directly at the amygdala to alterspinal neuronal activity in response to colorectal distensionrdquoJournal of Neurophysiology vol 89 no 3 pp 1343ndash1352 2003

[13] J C White and W H Seet Eds Pain and the NeurosurgeonCharles C Thomas Springfield Ill USA 1969

[14] F Hua T Harrison C Qin et al ldquoc-Fos expression in ratbrain stem and spinal cord in response to activation of car-diac ischemia-sensitive afferent neurons and electrostimulatorymodulationrdquo The American Journal of PhysiologymdashHeart andCirculatory Physiology vol 287 no 6 pp H2728ndashH2738 2004

[15] I Lindgren and H Olivecrona ldquoSurgical treatment of anginapectorisrdquo Journal of Neurosurgery vol 4 no 1 pp 19ndash39 1947

[16] J C White and E F Bland ldquoThe surgical relief of severe anginapectoris methods employed and endrdquo Medicine vol 27 no 1pp 1ndash42 1948

[17] M Zimmermann ldquoEthical guidelines for investigations ofexperimental pain in conscious animalsrdquo Pain vol 16 no 2 pp109ndash110 1983

[18] H O Handwerker and PW Reeh ldquoPain and inflammationrdquo inProceedings of the 5th World Congress on Pain M R Bond J ECharlton andC JWoolf Eds pp 59ndash70 Elsevier AmsterdamThe Netherlands 1991

[19] I Euchner-Wamser S T Meller and G F Gebhart ldquoA modelof cardiac nociception in chronically instrumented rats behav-ioral and electrophysiological effects of pericardial administra-tion of algogenic substancesrdquo Pain vol 58 no 1 pp 117ndash1281994

[20] S T Meller and G F Gebhart ldquoA critical review of the afferentpathways and the potential chemical mediators involved incardiac painrdquo Neuroscience vol 48 no 3 pp 501ndash524 1992

[21] G Paxinos and C Watson Eds The Rat Brain in StereotaxicCoodinates Academic Press New York NY USA 1998

[22] M E Edelsbrunner M Nakano and P Holzer ldquoAfferentsignalling from the acid-challenged rat stomach is inhibitedand gastric acid elimination is enhanced by lafutidinerdquo BMCGastroenterology vol 9 article 40 2009

[23] T Haino S Hironaka T Ooka et al ldquoOrosensory deprivationalters taste-elicited c-Fos expression in the parabrachial nucleusof neonatal ratsrdquo Neuroscience Research vol 67 no 3 pp 228ndash235 2010

[24] K Okamoto R Thompson A Tashiro Z Chang and D ABereiter ldquoBright light produces Fos-positive neurons in caudaltrigeminal brainstemrdquo Neuroscience vol 160 no 4 pp 858ndash864 2009

[25] K Tokita T Shimura S Nakamura T Inoue and T YamamotoldquoInvolvement of forebrain in parabrachial neuronal activationinduced by aversively conditioned taste stimuli in the ratrdquo BrainResearch vol 1141 no 1 pp 188ndash196 2007

[26] T Yamamoto and K Sawa ldquoc-Fos-like immunoreactivity in thebrainstem following gastric loads of various chemical solutionsin ratsrdquo Brain Research vol 866 no 1-2 pp 135ndash143 2000

10 ISRN Pain

[27] T Yamamoto and K Sawa ldquoComparison of c-Fos-like immu-noreactivity in the brainstem following intraoral and intragas-tric infusions of chemical solutions in ratsrdquo Brain Research vol866 no 1-2 pp 144ndash151 2000

[28] T YamamotoM Takemura T Inui et al ldquoFunctional organiza-tion of the rodent parabrachial nucleusrdquoAnnals of the New YorkAcademy of Sciences vol 1170 pp 378ndash382 2009

[29] B J Sessle ldquoNeural mechanisms and pathways in craniofacialpainrdquo Canadian Journal of Neurological Sciences vol 26 no 3pp S7ndashS11 1999

[30] R Nieuwenhuys J Voogd and C H R van Huijzen EdsTheHuman Central Nervous System A Synopsis and Atlas SpringerBerlin Germany 1978

[31] H Burton A D Craig Jr D A Poulos and J T Molt ldquoEfferentprojections from temperature sensitive recording loci withinthe marginal zone of the nucleus caudalis of the spinal trigem-inal complex in the catrdquo Journal of Comparative Neurology vol183 no 4 pp 753ndash777 1979

[32] H Burton and A D Loewy ldquoDescending projections from themarginal cell layer and other regions of themonkey spinal cordrdquoBrain Research vol 116 no 3 pp 485ndash491 1976

[33] C E Catsman-Berrevoets and H G J M Kuypers ldquoCells oforigin of cortical projections to dorsal column nuclei spinalcord and bulbar medial reticular formation in the rhesusmonkeyrdquoNeuroscience Letters vol 3 no 5-6 pp 245ndash252 1976

[34] H G J M Kuypers and V A Maisky ldquoRetrograde axonaltransport of horseradish peroxidase from spinal cord to brainstem cell groups in the catrdquo Neuroscience Letters vol 1 no 1pp 9ndash14 1975

[35] D A Ruggiero C A Ross and D J Reis ldquoProjections from thespinal trigeminal nucleus to the entire length of the spinal cordin the ratrdquo Brain Research vol 225 no 2 pp 225ndash233 1981

Submit your manuscripts athttpwwwhindawicom

Stem CellsInternational

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

MEDIATORSINFLAMMATION

of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Behavioural Neurology

EndocrinologyInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Disease Markers

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

BioMed Research International

OncologyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Oxidative Medicine and Cellular Longevity

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

PPAR Research

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Immunology ResearchHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

ObesityJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Computational and Mathematical Methods in Medicine

OphthalmologyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Diabetes ResearchJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Research and TreatmentAIDS

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Gastroenterology Research and Practice

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Parkinsonrsquos Disease

Evidence-Based Complementary and Alternative Medicine

Volume 2014Hindawi Publishing Corporationhttpwwwhindawicom

Page 8: Research Article Neural Mechanisms That Underlie Angina ...downloads.hindawi.com/archive/2013/671503.pdf · angina-induced referred pain. It is of particular interest to examine such

8 ISRN Pain

600 120583m

(a)

(b)

(A) (B)

(A) (B)

Figure 7 Effects of the lesion of the C1-C2 spinal segments on c-Fos expression in vehicle-infused (a) and PPS-infused (b) ratsPhotomicrographs show c-Fos expression in the left Sp5C Fos-labeled cells were observed in the intact rats (a-A and b-A) The numberof Fos-labeled cells remarkably increased in the lesioned rats (a-B and b-B) compared with the intact rats

Left side Right side

Num

ber o

f Fos

-labe

led

cells

0

5

10

15

20Vehicle

lowast

(a)

Right sideLeft side

Intact ratsC1-C2 lesioned rats

Num

ber o

f Fos

-labe

led

cells

0

10

20

30

40

50

60 PPSlowast

lowast

(b)

Figure 8 A comparison of the number of Fos-labeled cells between intact and C1-C2-lesioned rats following an infusion of either vehicleor PPS solution Note that c-Fos expression significantly increased when the C1-C2 spinal segments were lesioned lowast119875 lt 005 significantlydifferent between two groups of rats

ISRN Pain 9

The descending projection from the Sp5C to the spinaldorsal horn has been demonstrated anatomically [31ndash35]Therefore the activation of Sp5C cells induced by nociceptivesignals from the cardiac region may explain the results fromprior studies that injection of algesic chemicals into thepericardial sac resulted in an increase in activity among theC1-C2 STT cells [4ndash7]

In conclusion nociceptive signals from the cardiac regionare input to the SP5C via an unknown pathway in the brainThese signals are transmitted to secondary neurons at thesuperficial layers in the Sp5C and then projected to thethalamusThis ascending pathway may contribute to angina-induced referred pain in the trigeminal nerve territory

Conflict of Interests

The authors have no conflict of interests to declare

Acknowledgments

The authors thank Dr Yumiko Hayashi for her criticalreading of the paper This work was supported in part by agrant from Daiichi-Sankyo Co Ltd

References

[1] R D Foreman ldquoMechanisms of cardiac painrdquo Annual Reviewof Physiology vol 61 pp 143ndash167 1999

[2] T C Ruch ldquoVisceral sensation and referred painrdquo in FultonHowellrsquos Textbook of Physiology pp 385ndash401 WB SaundersPhiladelphia Pa USA 15th edition 1946

[3] D E Myers ldquoVagus nerve pain referred to the craniofacialregion A case report and literature review with implications forreferred cardiac painrdquo The British Dental Journal vol 204 no4 pp 187ndash189 2008

[4] M J Chandler J Zhang and R D Foreman ldquoVagal sympa-thetic and somatic sensory inputs to upper cervical (C1-C3)spinothalamic tract neurons inmonkeysrdquo Journal of Neurophys-iology vol 76 no 4 pp 2555ndash2567 1996

[5] M J Chandler J Zhang and R D Foreman ldquoPericardialinjections of inflammatory chemicals excite upper cervical (C1-C3) spinothalamic tract (STT) cells in monkeysrdquo Society forNeuroscience vol 21 article 2604 1995

[6] R D Foreman and C Qin ldquoNeuromodulation of cardiac painand cerebral vasculature neural mechanismsrdquo Cleveland ClinicJournal of Medicine vol 76 pp S75ndashS79 2009

[7] C Qin M J Chandler K E Miller and R D ForemanldquoResponses and afferent pathways of superficial and deeper C1-C2 spinal cells to intrapericardial algogenic chemicals in ratsrdquoJournal of Neurophysiology vol 85 no 4 pp 1522ndash1532 2001

[8] D L McNeill M J Chandler Q G Fu and R D ForemanldquoProjection of nodose ganglion cells to the upper cervical spinalcord in the ratrdquoBrain Research Bulletin vol 27 no 2 pp 151ndash1551991

[9] B J Sessle ldquoPeripheral and central mechanisms of orofacialinflammatory painrdquo International Review of Neurobiology vol97 pp 179ndash206 2011

[10] B Greenwood-VanMeerveldMGibsonWGunter J ShepardR Foreman and D Myers ldquoStereotaxic delivery of corticos-terone to the amygdala modulates colonic sensitivity in ratsrdquoBrain Research vol 893 no 1-2 pp 135ndash142 2001

[11] W D Gunter J D Shepard R D Foreman D A Myers andB Greenwood-Van Meerveld ldquoEvidence for visceral hypersen-sitivity in high-anxiety ratsrdquo Physiology and Behavior vol 69no 3 pp 379ndash382 2000

[12] C Qin B Greenwood-Van Meerveld D A Myers and R DForeman ldquoCorticosterone acts directly at the amygdala to alterspinal neuronal activity in response to colorectal distensionrdquoJournal of Neurophysiology vol 89 no 3 pp 1343ndash1352 2003

[13] J C White and W H Seet Eds Pain and the NeurosurgeonCharles C Thomas Springfield Ill USA 1969

[14] F Hua T Harrison C Qin et al ldquoc-Fos expression in ratbrain stem and spinal cord in response to activation of car-diac ischemia-sensitive afferent neurons and electrostimulatorymodulationrdquo The American Journal of PhysiologymdashHeart andCirculatory Physiology vol 287 no 6 pp H2728ndashH2738 2004

[15] I Lindgren and H Olivecrona ldquoSurgical treatment of anginapectorisrdquo Journal of Neurosurgery vol 4 no 1 pp 19ndash39 1947

[16] J C White and E F Bland ldquoThe surgical relief of severe anginapectoris methods employed and endrdquo Medicine vol 27 no 1pp 1ndash42 1948

[17] M Zimmermann ldquoEthical guidelines for investigations ofexperimental pain in conscious animalsrdquo Pain vol 16 no 2 pp109ndash110 1983

[18] H O Handwerker and PW Reeh ldquoPain and inflammationrdquo inProceedings of the 5th World Congress on Pain M R Bond J ECharlton andC JWoolf Eds pp 59ndash70 Elsevier AmsterdamThe Netherlands 1991

[19] I Euchner-Wamser S T Meller and G F Gebhart ldquoA modelof cardiac nociception in chronically instrumented rats behav-ioral and electrophysiological effects of pericardial administra-tion of algogenic substancesrdquo Pain vol 58 no 1 pp 117ndash1281994

[20] S T Meller and G F Gebhart ldquoA critical review of the afferentpathways and the potential chemical mediators involved incardiac painrdquo Neuroscience vol 48 no 3 pp 501ndash524 1992

[21] G Paxinos and C Watson Eds The Rat Brain in StereotaxicCoodinates Academic Press New York NY USA 1998

[22] M E Edelsbrunner M Nakano and P Holzer ldquoAfferentsignalling from the acid-challenged rat stomach is inhibitedand gastric acid elimination is enhanced by lafutidinerdquo BMCGastroenterology vol 9 article 40 2009

[23] T Haino S Hironaka T Ooka et al ldquoOrosensory deprivationalters taste-elicited c-Fos expression in the parabrachial nucleusof neonatal ratsrdquo Neuroscience Research vol 67 no 3 pp 228ndash235 2010

[24] K Okamoto R Thompson A Tashiro Z Chang and D ABereiter ldquoBright light produces Fos-positive neurons in caudaltrigeminal brainstemrdquo Neuroscience vol 160 no 4 pp 858ndash864 2009

[25] K Tokita T Shimura S Nakamura T Inoue and T YamamotoldquoInvolvement of forebrain in parabrachial neuronal activationinduced by aversively conditioned taste stimuli in the ratrdquo BrainResearch vol 1141 no 1 pp 188ndash196 2007

[26] T Yamamoto and K Sawa ldquoc-Fos-like immunoreactivity in thebrainstem following gastric loads of various chemical solutionsin ratsrdquo Brain Research vol 866 no 1-2 pp 135ndash143 2000

10 ISRN Pain

[27] T Yamamoto and K Sawa ldquoComparison of c-Fos-like immu-noreactivity in the brainstem following intraoral and intragas-tric infusions of chemical solutions in ratsrdquo Brain Research vol866 no 1-2 pp 144ndash151 2000

[28] T YamamotoM Takemura T Inui et al ldquoFunctional organiza-tion of the rodent parabrachial nucleusrdquoAnnals of the New YorkAcademy of Sciences vol 1170 pp 378ndash382 2009

[29] B J Sessle ldquoNeural mechanisms and pathways in craniofacialpainrdquo Canadian Journal of Neurological Sciences vol 26 no 3pp S7ndashS11 1999

[30] R Nieuwenhuys J Voogd and C H R van Huijzen EdsTheHuman Central Nervous System A Synopsis and Atlas SpringerBerlin Germany 1978

[31] H Burton A D Craig Jr D A Poulos and J T Molt ldquoEfferentprojections from temperature sensitive recording loci withinthe marginal zone of the nucleus caudalis of the spinal trigem-inal complex in the catrdquo Journal of Comparative Neurology vol183 no 4 pp 753ndash777 1979

[32] H Burton and A D Loewy ldquoDescending projections from themarginal cell layer and other regions of themonkey spinal cordrdquoBrain Research vol 116 no 3 pp 485ndash491 1976

[33] C E Catsman-Berrevoets and H G J M Kuypers ldquoCells oforigin of cortical projections to dorsal column nuclei spinalcord and bulbar medial reticular formation in the rhesusmonkeyrdquoNeuroscience Letters vol 3 no 5-6 pp 245ndash252 1976

[34] H G J M Kuypers and V A Maisky ldquoRetrograde axonaltransport of horseradish peroxidase from spinal cord to brainstem cell groups in the catrdquo Neuroscience Letters vol 1 no 1pp 9ndash14 1975

[35] D A Ruggiero C A Ross and D J Reis ldquoProjections from thespinal trigeminal nucleus to the entire length of the spinal cordin the ratrdquo Brain Research vol 225 no 2 pp 225ndash233 1981

Submit your manuscripts athttpwwwhindawicom

Stem CellsInternational

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

MEDIATORSINFLAMMATION

of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Behavioural Neurology

EndocrinologyInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Disease Markers

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

BioMed Research International

OncologyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Oxidative Medicine and Cellular Longevity

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

PPAR Research

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Immunology ResearchHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

ObesityJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Computational and Mathematical Methods in Medicine

OphthalmologyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Diabetes ResearchJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Research and TreatmentAIDS

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Gastroenterology Research and Practice

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Parkinsonrsquos Disease

Evidence-Based Complementary and Alternative Medicine

Volume 2014Hindawi Publishing Corporationhttpwwwhindawicom

Page 9: Research Article Neural Mechanisms That Underlie Angina ...downloads.hindawi.com/archive/2013/671503.pdf · angina-induced referred pain. It is of particular interest to examine such

ISRN Pain 9

The descending projection from the Sp5C to the spinaldorsal horn has been demonstrated anatomically [31ndash35]Therefore the activation of Sp5C cells induced by nociceptivesignals from the cardiac region may explain the results fromprior studies that injection of algesic chemicals into thepericardial sac resulted in an increase in activity among theC1-C2 STT cells [4ndash7]

In conclusion nociceptive signals from the cardiac regionare input to the SP5C via an unknown pathway in the brainThese signals are transmitted to secondary neurons at thesuperficial layers in the Sp5C and then projected to thethalamusThis ascending pathway may contribute to angina-induced referred pain in the trigeminal nerve territory

Conflict of Interests

The authors have no conflict of interests to declare

Acknowledgments

The authors thank Dr Yumiko Hayashi for her criticalreading of the paper This work was supported in part by agrant from Daiichi-Sankyo Co Ltd

References

[1] R D Foreman ldquoMechanisms of cardiac painrdquo Annual Reviewof Physiology vol 61 pp 143ndash167 1999

[2] T C Ruch ldquoVisceral sensation and referred painrdquo in FultonHowellrsquos Textbook of Physiology pp 385ndash401 WB SaundersPhiladelphia Pa USA 15th edition 1946

[3] D E Myers ldquoVagus nerve pain referred to the craniofacialregion A case report and literature review with implications forreferred cardiac painrdquo The British Dental Journal vol 204 no4 pp 187ndash189 2008

[4] M J Chandler J Zhang and R D Foreman ldquoVagal sympa-thetic and somatic sensory inputs to upper cervical (C1-C3)spinothalamic tract neurons inmonkeysrdquo Journal of Neurophys-iology vol 76 no 4 pp 2555ndash2567 1996

[5] M J Chandler J Zhang and R D Foreman ldquoPericardialinjections of inflammatory chemicals excite upper cervical (C1-C3) spinothalamic tract (STT) cells in monkeysrdquo Society forNeuroscience vol 21 article 2604 1995

[6] R D Foreman and C Qin ldquoNeuromodulation of cardiac painand cerebral vasculature neural mechanismsrdquo Cleveland ClinicJournal of Medicine vol 76 pp S75ndashS79 2009

[7] C Qin M J Chandler K E Miller and R D ForemanldquoResponses and afferent pathways of superficial and deeper C1-C2 spinal cells to intrapericardial algogenic chemicals in ratsrdquoJournal of Neurophysiology vol 85 no 4 pp 1522ndash1532 2001

[8] D L McNeill M J Chandler Q G Fu and R D ForemanldquoProjection of nodose ganglion cells to the upper cervical spinalcord in the ratrdquoBrain Research Bulletin vol 27 no 2 pp 151ndash1551991

[9] B J Sessle ldquoPeripheral and central mechanisms of orofacialinflammatory painrdquo International Review of Neurobiology vol97 pp 179ndash206 2011

[10] B Greenwood-VanMeerveldMGibsonWGunter J ShepardR Foreman and D Myers ldquoStereotaxic delivery of corticos-terone to the amygdala modulates colonic sensitivity in ratsrdquoBrain Research vol 893 no 1-2 pp 135ndash142 2001

[11] W D Gunter J D Shepard R D Foreman D A Myers andB Greenwood-Van Meerveld ldquoEvidence for visceral hypersen-sitivity in high-anxiety ratsrdquo Physiology and Behavior vol 69no 3 pp 379ndash382 2000

[12] C Qin B Greenwood-Van Meerveld D A Myers and R DForeman ldquoCorticosterone acts directly at the amygdala to alterspinal neuronal activity in response to colorectal distensionrdquoJournal of Neurophysiology vol 89 no 3 pp 1343ndash1352 2003

[13] J C White and W H Seet Eds Pain and the NeurosurgeonCharles C Thomas Springfield Ill USA 1969

[14] F Hua T Harrison C Qin et al ldquoc-Fos expression in ratbrain stem and spinal cord in response to activation of car-diac ischemia-sensitive afferent neurons and electrostimulatorymodulationrdquo The American Journal of PhysiologymdashHeart andCirculatory Physiology vol 287 no 6 pp H2728ndashH2738 2004

[15] I Lindgren and H Olivecrona ldquoSurgical treatment of anginapectorisrdquo Journal of Neurosurgery vol 4 no 1 pp 19ndash39 1947

[16] J C White and E F Bland ldquoThe surgical relief of severe anginapectoris methods employed and endrdquo Medicine vol 27 no 1pp 1ndash42 1948

[17] M Zimmermann ldquoEthical guidelines for investigations ofexperimental pain in conscious animalsrdquo Pain vol 16 no 2 pp109ndash110 1983

[18] H O Handwerker and PW Reeh ldquoPain and inflammationrdquo inProceedings of the 5th World Congress on Pain M R Bond J ECharlton andC JWoolf Eds pp 59ndash70 Elsevier AmsterdamThe Netherlands 1991

[19] I Euchner-Wamser S T Meller and G F Gebhart ldquoA modelof cardiac nociception in chronically instrumented rats behav-ioral and electrophysiological effects of pericardial administra-tion of algogenic substancesrdquo Pain vol 58 no 1 pp 117ndash1281994

[20] S T Meller and G F Gebhart ldquoA critical review of the afferentpathways and the potential chemical mediators involved incardiac painrdquo Neuroscience vol 48 no 3 pp 501ndash524 1992

[21] G Paxinos and C Watson Eds The Rat Brain in StereotaxicCoodinates Academic Press New York NY USA 1998

[22] M E Edelsbrunner M Nakano and P Holzer ldquoAfferentsignalling from the acid-challenged rat stomach is inhibitedand gastric acid elimination is enhanced by lafutidinerdquo BMCGastroenterology vol 9 article 40 2009

[23] T Haino S Hironaka T Ooka et al ldquoOrosensory deprivationalters taste-elicited c-Fos expression in the parabrachial nucleusof neonatal ratsrdquo Neuroscience Research vol 67 no 3 pp 228ndash235 2010

[24] K Okamoto R Thompson A Tashiro Z Chang and D ABereiter ldquoBright light produces Fos-positive neurons in caudaltrigeminal brainstemrdquo Neuroscience vol 160 no 4 pp 858ndash864 2009

[25] K Tokita T Shimura S Nakamura T Inoue and T YamamotoldquoInvolvement of forebrain in parabrachial neuronal activationinduced by aversively conditioned taste stimuli in the ratrdquo BrainResearch vol 1141 no 1 pp 188ndash196 2007

[26] T Yamamoto and K Sawa ldquoc-Fos-like immunoreactivity in thebrainstem following gastric loads of various chemical solutionsin ratsrdquo Brain Research vol 866 no 1-2 pp 135ndash143 2000

10 ISRN Pain

[27] T Yamamoto and K Sawa ldquoComparison of c-Fos-like immu-noreactivity in the brainstem following intraoral and intragas-tric infusions of chemical solutions in ratsrdquo Brain Research vol866 no 1-2 pp 144ndash151 2000

[28] T YamamotoM Takemura T Inui et al ldquoFunctional organiza-tion of the rodent parabrachial nucleusrdquoAnnals of the New YorkAcademy of Sciences vol 1170 pp 378ndash382 2009

[29] B J Sessle ldquoNeural mechanisms and pathways in craniofacialpainrdquo Canadian Journal of Neurological Sciences vol 26 no 3pp S7ndashS11 1999

[30] R Nieuwenhuys J Voogd and C H R van Huijzen EdsTheHuman Central Nervous System A Synopsis and Atlas SpringerBerlin Germany 1978

[31] H Burton A D Craig Jr D A Poulos and J T Molt ldquoEfferentprojections from temperature sensitive recording loci withinthe marginal zone of the nucleus caudalis of the spinal trigem-inal complex in the catrdquo Journal of Comparative Neurology vol183 no 4 pp 753ndash777 1979

[32] H Burton and A D Loewy ldquoDescending projections from themarginal cell layer and other regions of themonkey spinal cordrdquoBrain Research vol 116 no 3 pp 485ndash491 1976

[33] C E Catsman-Berrevoets and H G J M Kuypers ldquoCells oforigin of cortical projections to dorsal column nuclei spinalcord and bulbar medial reticular formation in the rhesusmonkeyrdquoNeuroscience Letters vol 3 no 5-6 pp 245ndash252 1976

[34] H G J M Kuypers and V A Maisky ldquoRetrograde axonaltransport of horseradish peroxidase from spinal cord to brainstem cell groups in the catrdquo Neuroscience Letters vol 1 no 1pp 9ndash14 1975

[35] D A Ruggiero C A Ross and D J Reis ldquoProjections from thespinal trigeminal nucleus to the entire length of the spinal cordin the ratrdquo Brain Research vol 225 no 2 pp 225ndash233 1981

Submit your manuscripts athttpwwwhindawicom

Stem CellsInternational

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

MEDIATORSINFLAMMATION

of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Behavioural Neurology

EndocrinologyInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Disease Markers

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

BioMed Research International

OncologyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Oxidative Medicine and Cellular Longevity

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

PPAR Research

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Immunology ResearchHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

ObesityJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Computational and Mathematical Methods in Medicine

OphthalmologyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Diabetes ResearchJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Research and TreatmentAIDS

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Gastroenterology Research and Practice

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Parkinsonrsquos Disease

Evidence-Based Complementary and Alternative Medicine

Volume 2014Hindawi Publishing Corporationhttpwwwhindawicom

Page 10: Research Article Neural Mechanisms That Underlie Angina ...downloads.hindawi.com/archive/2013/671503.pdf · angina-induced referred pain. It is of particular interest to examine such

10 ISRN Pain

[27] T Yamamoto and K Sawa ldquoComparison of c-Fos-like immu-noreactivity in the brainstem following intraoral and intragas-tric infusions of chemical solutions in ratsrdquo Brain Research vol866 no 1-2 pp 144ndash151 2000

[28] T YamamotoM Takemura T Inui et al ldquoFunctional organiza-tion of the rodent parabrachial nucleusrdquoAnnals of the New YorkAcademy of Sciences vol 1170 pp 378ndash382 2009

[29] B J Sessle ldquoNeural mechanisms and pathways in craniofacialpainrdquo Canadian Journal of Neurological Sciences vol 26 no 3pp S7ndashS11 1999

[30] R Nieuwenhuys J Voogd and C H R van Huijzen EdsTheHuman Central Nervous System A Synopsis and Atlas SpringerBerlin Germany 1978

[31] H Burton A D Craig Jr D A Poulos and J T Molt ldquoEfferentprojections from temperature sensitive recording loci withinthe marginal zone of the nucleus caudalis of the spinal trigem-inal complex in the catrdquo Journal of Comparative Neurology vol183 no 4 pp 753ndash777 1979

[32] H Burton and A D Loewy ldquoDescending projections from themarginal cell layer and other regions of themonkey spinal cordrdquoBrain Research vol 116 no 3 pp 485ndash491 1976

[33] C E Catsman-Berrevoets and H G J M Kuypers ldquoCells oforigin of cortical projections to dorsal column nuclei spinalcord and bulbar medial reticular formation in the rhesusmonkeyrdquoNeuroscience Letters vol 3 no 5-6 pp 245ndash252 1976

[34] H G J M Kuypers and V A Maisky ldquoRetrograde axonaltransport of horseradish peroxidase from spinal cord to brainstem cell groups in the catrdquo Neuroscience Letters vol 1 no 1pp 9ndash14 1975

[35] D A Ruggiero C A Ross and D J Reis ldquoProjections from thespinal trigeminal nucleus to the entire length of the spinal cordin the ratrdquo Brain Research vol 225 no 2 pp 225ndash233 1981

Submit your manuscripts athttpwwwhindawicom

Stem CellsInternational

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

MEDIATORSINFLAMMATION

of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Behavioural Neurology

EndocrinologyInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Disease Markers

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

BioMed Research International

OncologyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Oxidative Medicine and Cellular Longevity

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

PPAR Research

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Immunology ResearchHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

ObesityJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Computational and Mathematical Methods in Medicine

OphthalmologyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Diabetes ResearchJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Research and TreatmentAIDS

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Gastroenterology Research and Practice

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Parkinsonrsquos Disease

Evidence-Based Complementary and Alternative Medicine

Volume 2014Hindawi Publishing Corporationhttpwwwhindawicom

Page 11: Research Article Neural Mechanisms That Underlie Angina ...downloads.hindawi.com/archive/2013/671503.pdf · angina-induced referred pain. It is of particular interest to examine such

Submit your manuscripts athttpwwwhindawicom

Stem CellsInternational

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

MEDIATORSINFLAMMATION

of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Behavioural Neurology

EndocrinologyInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Disease Markers

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

BioMed Research International

OncologyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Oxidative Medicine and Cellular Longevity

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

PPAR Research

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Immunology ResearchHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

ObesityJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Computational and Mathematical Methods in Medicine

OphthalmologyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Diabetes ResearchJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Research and TreatmentAIDS

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Gastroenterology Research and Practice

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Parkinsonrsquos Disease

Evidence-Based Complementary and Alternative Medicine

Volume 2014Hindawi Publishing Corporationhttpwwwhindawicom