Glucocorticoid-Dependent Neuroplasticity: Fueling the Cycle of Stress and Addiction John Mantsch,...

Glucocorticoid-Dependent Neuroplasticity: Fueling the Cycle of Stress and Addiction

John Mantsch, Ph.D.Department of Biomedical Sciences

Marquette UniversityMilwaukee, WI

http://www.mu.edu/index.html

DRUG EFFECTS ENVIRONMENT

GENETICS

RISK FACTORS FOR COCAINE ADDICTION

DRUG-ASSOCIATED CUESDRUG-ASSOCIATED CONTEXTSTRESS

ACUTE REWARDING EFFECTSWITHDRAWAL EFFECTSDRUG-INDUCED NEUROPLASTICITY

PERSONALITY TRAITSGENETIC POLYMORPHISMS


CLINICAL EVIDENCE FOR A LINK BETWEEN STRESS AND COCAINE ADDICTION:

• High incidence of anxiety/mood disorders in cocaine-addicted populations.

• Link between drug dependence and post-traumatic stress disorder (PTSD)

• Personalized stress imagery precipitates cocaine craving in recovering cocaine addicts.


• Surgical implantation of silastic catheter into jugular vein

• Exit via head- or back-mounted cannula port• Drug delivery line attached to a counter-

balanced leak-proof swivel to allow unrestricted movement

• Tested in operant chamber (modified Skinner box) - experimenter-controlled environment

• Pressing a response lever activates a pump resulting in infusion of set volume of drug solution

• In general - drugs with abuse potential in humans will be self-administered by rats (e.g., cocaine, heroin, alcohol, benzodiazepines,methamphetamine, nicotine, and cannabinoids).

IV DRUG SELF-ADMINISTRATION COCAINE


RELAPSE OF DRUG USE/DRUG CRAVING: REINSTATEMENT PROTOCOLS

POSITIVE REINFORCING (EUPHORIC) EFFECTS OF DRUGS: MAINTENANCE PROTOCOLS

PREDISPOSITION TO USE DRUGS: ACQUISITION PROTOCOLS

LOSS OF CONTROL OVER DRUG USE (ADDICTION): ESCALATION PROTOCOLS

Acute Stress Reinstates Extinguished Cocaine-Seeking Behavior in Rats

BAS COC EFS BAS COC EFS0

50

100

150 #

#

ACTIVE LEVER INACTIVE LEVER

Res

po

nse

s/2-

h S

essi

on

BAS = Last day of EXTCOC = IP Cocaine (10 mg/kg)EFS = 3 x 0.6 mA/0.5-s shocks

ave every 45 sec for 15 min

1 2 3 4 5 6 7 8 9 100

20

40

60

80

100

Extinction Day

Res

po

nse

s/2-

h S

essi

on

12 13 140

100

200

300

400

SA Day

Res

po

nse

s/6-

h S

essi

on

1. Self-Administration 2. Extinction 3. Reinstatement

In syringe: Cocaine (1.0 mg/kg/inf) Saline Saline

Ahmed and Koob 1997Erb et al 1997Mantsch et al 1999


CHRONIC STRESS


EFFECTS OF CHRONIC-STRESS ON COCAINE-INDUCED NEUROPLASTICITY

COCAINE ALONE COCAINE AND STRESS


MODELING HUMAN ADDICTION

HUMANS

• LOSS OF CONTROL OVER DRUG USE

• LONG-TERM SUSCEPTIBILITY TO DRUG RELAPSE

RATS

• ESCALATING PATTERNS OF DRUG SELF-ADMINISTRATION

• AUGMENTED REINSTATEMENT OF EXTINGUISHED COCAINE-SEEKING BEHAVIOR

EFFECTS OF REPEATED ELECTRIC FOOTSHOCK (EFS) STRESS ON COCAINE SELF-ADMINISTRATION

4 X 30-min Cocaine Self-Administration Sessions0.5 mg/kg/inf; Fixed-ratio 4 schedule

Groups (tested for 14 days):1. EFS: received footshock during 5-min components2. No EFS: did not receive footshock during 5-min components

Five Minutes Intermittent Electric Footshock3 x 0.6 mA shocks; 100 msec duration/frequencyAverage of 45 sec


CHRONIC STRESS PRODUCES AN ESCALATION OF COCAINE BUT NOT FOOD SELF-ADMINISTRATION BY RATS

•EFS: Electric footshock in the SA chamber at the time of SA testing •No EFS: control group

Mantsch and Katz, 2007; Neuropsychopharmacology

BAS0

5

10

15

20

25

30

35

40

45

50

No EFSEFS

1 2 3 4 5 6 7 8 9 10 11 12 13 14

* * * ** *

Coc Self-Administration Day

Co

c In

fusi

on

s/S

essi

on

BAS0

50

100

150

200

250

300

350

1 2 3 4 5 6 7 8 9 10 11 12 13 14

No EFSEFS

Food Self-Administration Day

Fo

od

Pel

lets

/Ses

sio

n

Food

Cocaine


EFS ONLY ESCALATES SA IF DELIVERED AT THE TIME OF SA TESTING WITHIN THE SA ENVIRONMENT

•EFS/SA Context/SA: Electric footshock in the SA chamber at the time of SA testing •EFS/Non-SA Context/Post-SA: EFS in a non-SA context at the time of SA testing .•EFS/SA Context/Post-SA: EFS the SA context at the time of SA testing.•No EFS: control

BAS0

5

10

15

20

25

30

35

40

45

50

No EFSEFS/SA Context/SA

1 2 3 4 5 6 7 8 9 10 11 12 13 14

* * * ** *

EFS/Non-SA Context/Post-SA

EFS/SA Context/Post-SA

Self-Administration Day

Infu

sio

ns

/Se

ss

ion

Mantsch and Katz, 2007; Neuropsychopharmacology


THE CHRONIC VARIABLE STRESS PROTOCOL

• Chronic: 14 days; twice daily exposure• Mild: non-noxious stressors• Variable: 7 stressor presented in randomized sequence

WEEK 1 WEEK 2DAY AM PM DAY AM PM

1 Forced Swim Restraint 8 Cold Noise

2 Noise Cold Swim 9 Open Field Cold Swim

3 Rotation Open Field 10 Restraint Rotation

4 Cold Forced Swim 11 Noise Forced Swim

5 Restraint Cold 12 Restraint Open Field

6 Open Field Rotation 13 Cold Swim Restraint

7 Cold Swim Noise 14 Forced Swim Cold

References: JP Herman et al (1995) Neuroendocrinology 61: 180-90; WE Cullinan et al (2000) Brain Research 887: 118-124.

THE CHRONIC VARIABLE STRESS PROTOCOL…

3. Does not result in attenuation of the stress response with repeated exposure

Group Basal CORT(ng/ml)

CORT response to EFS (ng/ml)

No CVS 50.56 ± 10.69 295.63 ± 6.73

CVS 80.22 ± 38.87 294.58 ± 8.46

Group Adrenal Weight(mg)

Thymus Weight(mg)

No CVS 52.7 ± 2.6 449 ± 17

CVS 64.8 ± 2.8* 372 ± 15*

2. Produces physiological signs of chronic stress

1. Does not affect body weight or produce noticable changes in health/vitality

Group Basal Body Wt (mg)

Post-CVS Body Weight (mg)

No CVS 334 ± 2.3 357 ± 4.0

CVS 337 ± 2.3 348 ± 3.0


EFFECTS OF CVS ON COCAINE-INDUCED NEUROPLASTICITY

8 AM 12 PM 4 PM

Room TempSwim Restraint

CocaineSA/Injection

A. A sample experimental test day

SA TESTING/ EXTINCTION/ INDUCTION WITHDRAWAL

14 DAYS+/- CVS

14 DAYSNo CVS

SA TRAINING/HABITUATION

REINSTATEMENT/DRUG CHALLENGE

B. General experimental time-line


Saline/No CVS Saline/CVS Cocaine/No CVS Cocaine/CVS0

10000

20000

30000

40000

Saline

Cocaine (10 mg/kg)

*

*#

Treatment (x 14 days)

Co

cain

e-In

du

ced

Act

ivit

y (T

ota

lP

ho

tob

eam

Bre

aks)

CHRONIC VARIABLE STRESS ACROSS A PERIOD OF COCAINE ADMINISTRATION POTENTIATES COCAINE-INDUCED LOCOMOTOR

SENSITIZATION

• CVS across a period of cocaine administration augments cocaine-induced locomotor sensitization

• CVS does not produce locomotor sensitization when delivered in the absence of cocaine

Withdrawal D12 Challenge:


CHRONIC VARIABLE STRESS DURING BUT NOT AFTER A PERIOD OF COCAINE SA AUGMENTS LATER COCAINE-INDUCED

REINSTATEMENT

#

##


Corticotropin Releasing Hormone/Factor PVN of the Hypothalamus

KIDNEYAdrenocorticotropic Hormone

The Hypothalamic Pituitary Adrenal (HPA) Axis

Corticosterone (in rats)

WHY GLUCOCORTICOIDS?

• Glucocorticoids = mediate adaptational responses to stressors (physiological and behavioral)

• Neurocircuitry underlying drug-seeking behavior is a direct and indirect target of glucocorticoids

STRESS

Peak Nadir Post-EFS0

100

200

300Sham ADX+CORT

*

SAMPLE TIME

PL

AS

MA

CO

RT

(n

g/m

l)

CIRCADIAN AND EFS-INDUCED CORT SECRETION IN ADX RATS WITH DIURNAL CORT REPLACEMENT AND SHAM-TREATED CONTROLS

• Surgical adrenalectomy• Subcutaneous 25% CORT Pellet Implantation• Inclusion of CORT (0.25%) in drinking water (0.9% NaCl)

• Sham surgery• 100% cholesterol pellet• 0.9% NaCl for drinking water


BAS0

5

10

15

20

25

30

35

40

45

50

SHAM NO EFS

SHAM + EFS

1 2 3 4 5 6 7 8 9 10 11 12 13 14

* * * ** *

ADX/C + EFS

ADX/C + NO EFS


Infu

sio

ns/

Ses

sio

n

THE ESCALATION OF COCAINE SELF-ADMINISTRATION BY REPEATED STRESS REQUIRES STRESSOR-INDUCED

GLUCOCORTICOID SECRETION

ADX/C = surgical adrenalectomy with diurnal CORT replacement


BAS0

5

10

15

20

25

30

35

40

45

50EFS + CORT

NO EFS + CORT

1 2 3 4 5 6 7 8 9 10 11 12 13 14

EFS + NO CORTNO EFS + NOCORT

******


Infu

sio

ns/

Se

ssio

nCORT ADMINISTRATION RESTORES BUT DOES NOT REPRODUCE

THE ESCALATING EFFECTS OF EFS ON SA IN ADX/C RATS

• IP CORT (3.0 mg/kg) to ADX/C rats alone or prior to EFS

• IP CORT does not escalate cocaine SA by itself

• IP CORT given along with EFS restores the escalating effects of EFS on cocaine SA

ADX/C +:

0 4 8 12 16 20 240

100

200

300

400

500

HOURS POST-INJECTION

Pla

sma

CO

RT

(ng

/ml)

Plasma CORT after3.0 mg/kg IP CORT Injection


• Stress promotes cocaine-induced neuroplasticity that may be pathogenic for addiction:

1.Repeated exposure to a stressor (EFS) produces a context/timing-dependent escalation of cocaine SA that is specific to drug-seeking behavior.

2.Exposure to chronic variable stress (CVS) across a period of experimenter-delivered or self-administered cocaine exposure augments the expression of behavioral sensitization or cocaine-induced reinstatement after a stress-free withdrawal period.

• The escalating effects of repeated EFS are prevented by eliminating the corticosterone response to EFS.

• EFS-induced corticosterone secretion is necessary but not sufficient for the escalation of cocaine SA by repeated EFS.

• Corticosterone functions as an “enabler” that permits stressors to promote cocaine-seeking behavior and addiction.

• Cocaine-induced corticosterone secretion is NOT required for the escalation of cocaine SA under LgA conditions but does facilitate SA under long-access conditions.

• CORT is likely functioning as an enabler of stressor-induced neuroplasticity and appears to be working in concert with other neurobiological mediators that are active during periods of stress.

Summary


EFFECTS OF COCAINE ON STRESS RESPONSES

VICIOUS CYCLE OF ADDICTION

COCAINE USE

WITHDRAWAL

STRESS

Cocaine-Induced Neuroplasticity: Long-Term Effects of Cocaine SA on Responses to Stressors

BAS 1 2 3 4 5 6 7 8 9 10 11 12 13 140

20

40

60

80

ShA SA (Short-Access, 2 hrs daily)LgA SA (Long-Access, 6 hrs daily)

*******

****


Coc

aine

Int

ake

(mg/

kgpe

r se

ssio

n)

Studying Cocaine-Induced Neuroplasticity Using the Long-Access Cocaine Self-Administration Model

References:Ahmed and Koob, 1998Ahmed and Koob, 1999Mantsch et al 2004



50

100

150

ShA SALgA SA*

#

*

ACTIVE LEVER INACTIVE LEVER

*#

Res

po

nse

s/2-

h S

essi

on

LgA Cocaine SA Produces a Persistently Heightened Susceptibility to Cocaine and Stressor-Induces Reinstatement

Mantsch et al Neuropsychopharmacology, submitted


700h 900h 1300h0

50

100

150

200

250

300

BasLgA SAShA SA

ShA SA

LgA SA

Time

Pla

sma

CO

RT

(n

g/m

l)

GroupSAL ShA LgA

Body Weight (g) 424.71 11.06 435.17 7.56 406.93 9.47Adrenal Weight (mg) 33.56 4.67 48.78 5.22* 52.38 5.78*

Adr Wt/100 g Body Wt 0.82 0.12 1.13 0.10 1.29 0.15*Thymus Weight (mg) 242.72 16.19 250.59 18.13 191.24 14.87**

Thy Wt/100 g Body Wt 5.73 0.36 5.75 0.41 4.70 0.38

Activation of the HPA Axis by ShA and LgA Cocaine SA

Lights off

• Acute cocaine SA increases plasma CORT

• Chronic cocaine SA produces adrenal hypertrophy and reduces thymus mass

21 days after 14 days of daily ShA, LgA or saline SA

Peak Nadir0

100

200

300ShamADX+CORT

SAMPLE TIME

PL

AS

MA

CO

RT

(n

g/m

l)

700h 900h 1300h0

50

100

150

200

250

300ADX/CSham

LgA SA

TimeP

lasm

a C

OR

T (

ng

/ml)

ADX with Diurnal CORT Replacement Reproduces Circadian Fluctuations in CORT Levels but Prevents SA-Induced Increases in

CORT Secretion



BAS 1 2 3 4 5 6 7 8 9 10 11 12 13 140

20

40

60

80

ShA/ADX Sham

LgA/ADX ShamShA/ADX-CLgA/ ADX-C

* ** * * * * * * *

#

## # #

# ##

## #

@@@ @ @ @

@


Co

cain

e In

fusi

on

s/S

essi

on

Eliminating SA-Induced Increases in CORT Slows but Does Not Prevent Escalating SA Patterns in LgA Rats and Has No Effect on

ShA SA




50

100

150 ADX ShamPre-ADX

*

#* *

#

ShA LgA

Post-SA ADX/C

*

*

*

* *

Res

po

nse

s/2-

h S

essi

on

ADX/C Prior To But Not After Repeated LgA SA Prevents the Augmentation of Cocaine- or EFS-Induced Reinstatement Without

Altering Reinstatement in ShA Rats

Mantsch et al Neuropsychopharmacology, 2007


700h 900h 1300h 1900h0

50

100

150

200

250

300

IP CORT + ShA SA

BasLgA SAShA SA

ShA SA

LgA SA

IP CORT

Time

Pla

sma

CO

RT

(n

g/m

l)

Administration of 2.0 mg/kg CORT Immediately Prior to ShA SA Mimics the Effects of LgA SA on Plasma CORT



SAL COC0

25

50

75ShA + NoCORTShA +CORT

Reinstatment Condition

Res

pons

es/S

essi

on

B 1 2 3 4 5 6 7 8 9 10 11 12 13 140

5

10

15

20

25

30ShA + No CORT (n=17)ShA + CORT (n=7)


Coc

aine

Infu

sion

s/2-

hS

essi

on

Reproduction of LgA-Induced Increases in Plasma CORT is Insufficient to Produce Escalation or Augment Reinstatement in

ShA Rats



Summary• Daily cocaine SA under LgA conditions results in a progressive escalation of daily cocaine

intake and a long-term heightened susceptibility to cocaine- and stressor-induced reinstatement.

• These effects of LgA SA are the consequence of cocaine-induced neuroplasticity that likely contributes to addiction.

• Elevated CORT lat the time of SA testing is at least partly required for cocaine-induced neuroplasticity in LgA rats but is not necessary for the acute reinforcing or reinstating effect of cocaine and/or stressors.

• Administration of CORT using doses that reproduce increases in circulating CORT level observed in LgA rats alone is insufficient to induce escalate drug use or augment later cocaine-induced reinstatement.

• CORT is likely functioning as an enabler of cocaine-induced neuroplasticity and appears to be working in concert with other neurobiological mediators that are active during LgA cocaine SA. .

SAL ShA LgA0

10

20

30

40

50

60

70

80

90

Tim

e S

pe

nt

in O

pe

nA

rms

(s

ec

on

ds

) *

Elevated Plus Maze

OPEN-ARM ACTIVITY ON THE ELEVATED PLUS MAZE IS INCREASED 2 WEEKS AFTER LONG-ACCESS COCAINE SELF-ADMINISTRATION

ShA = short-access ratsLgA = long-accessSAL = saline SA controls

Mantsch et al Pychopharmacology, Submitted

Sal ShA LgA0

50

100

150

200

250

300

350

400

450

*

Group

Lat

ency

to

En

ter

Lig

ht

Co

mp

artm

ent

(sec

)

Sal ShA LgA0

50

100

150

200

250 *

Group

Tim

e S

pen

t in

Lig

ht

Co

mp

artm

ent

(sec

)

Sal ShA LgA0

1

2

3

4

5

6

7

8

9 *

Group

Lig

ht

Co

mp

artm

ent

En

trie

s/ 1

0 M

in


SA Produces An Augmentation of Exploratory Behavior Measured Using the Light-Dark Box Model 2 Weeks After SA Repeated SA Testing

Latency to Enter Light Time Spent in Light Number of Light Entries

Light-Dark Box

First 30 Min Second 30 Min0

250

500

750*

ShA LgASal

Time

Cen

ter

Tim

e (S

ec)

1 30 600

500

1000

1500

2000

2500LgA

ShASAL

Time (Min)

To

tal

Dis

tan

ce (

cm)

1 30 600

200

400

600

800

1000

1200LgA

ShASal

*

Time (Min)

Cen

ter

Dis

tan

ce (

cm)

Center

SA Increases Center Activity, But Not Total Activity, Within A Novel Environment Measured 2 Weeks After Repeated SA

Time Spent in CenterCenter ActivityTotal Activity


CRF mediates behavioral responses to stressors (Dunn and Berridge 1990, Brain Res Rev 15: 71-100).

CRF underlies stressor-induced reinstatement of cocaine seeking (Sarnyai et al 2001, Pharmacol Rev 53:209-243).

Potential sites of CRF-induced drug seeking include:•The CeA (Richter and Weiss 1999, Synapse 32: 254-261; Fu et al 2007, J Neurophysiol 97: 937-41)•The BNST via CRF projections originating in the CeA (Erb et al 2001, Psychopharm 158: 360-65; Erb et al 1999; J Neurosci 19: RC35)•The VTA presumably via CRF projections originating in the CeA (Wang et al 2005; J Neurosci 25: 5389-5396)

Role of Corticotropin Releasing Factor (CRF)

CeA vlBNST al/dl BNST0

10

20

30

40

50 Sal ShA LgA

Po

st-R

estr

ain

t C

RF

mR

NA

(m

CG

L)

Post-Restraint CRF mRNA in the BNST is not Altered As a Consequence of Prior Cocaine SA

Unpublished findings (J Mantsch, D Ziegler, W Cullinan)

Determined using in situ hybridization

Guide Cannula

Lateral Ventricle

Reinstatement by ICV CRF is Augmented in LgA Rats

Sal ShA LgA Sal ShA LgA0

10

20

30

40

50

60

70

80

90

100

1.0 g CRF

0.5 g CRF

Veh

Sham

*

*

*#

Active Lever Inactive Lever

Res

po

nse

s/S

essi

on


Summary• Cocaine SA alters anxiety-related behaviors in a manner dependent on the amount and/or

pattern of cocaine intake.

• When measured several weeks into withdrawal SA promotes a shift from a more passive response pattern when confronted with a stressful situation to a more active reponses patterns as measured using:

1.The elevated plus maze2.The light-dark box3.Testing in a novel environment

• This more active response pattern during times of stress may be manifest as drug use/drug-seeking behavior.

• Changes in stressor-responsiveness may be attributable to altered responsiveness to CRF.

• Reinstatement by ICV CRF was augmented by LgA cocaine SA, suggesting a recruitment or augmentation of CRF regulation of neurocircuitry underlying cocaine-seeking behavior.

EFFECTS OF COCAINE ON STRESSOR-INDUCED HPA FUNCTION

SAL COC0

10

20

30

40BASALRESTRAINT *

14-DAY TREATMENT GROUP

PV

N C

RH

mR

NA

(Mea

n C

orr

ecte

d G

ray

Le

ve

l)

BASAL RESTRAINT 1.5HR POST0

100

200

300

400

500

14 x Daily SAL14 x Daily COC (30 mg/kg, IP)

*

#

#

Pla

sma

Cor

ticos

tero

ne(n

g/m

l)Glucocorticoid and PVN CRH mRNA Responses to Restraint are

Augmented During Acute (24-h) Withdrawal from Chronic Experimenter-Delivered Cocaine Administration

Plasma CORT

PVN CRH mRNAMantsch et al Neurosci Lett 2007

Restraint Dex0

100

200

300

400

500

SALShALgA

**

*

PL

AS

MA

CO

RT

(%

BA

S)

Basal Restraint Dex0

50

100

150

200

250

300

350

SALShALgA

**

*

PL

AS

MA

CO

RT

(n

g/m

l)

Mantsch et al submitted Brain Res

Cocaine SA Intake-Dependently Augments the Stressor-Induced

CORT Secretion and Impair Dexamethasone Suppression of

Plasma CORT Levels

Measured approx 3 weeks after SA testing

SAL ShA LgA0

25

50

75

100

125

Sal

ShA

LgA

*

98 kD GRLgAShASal

GR

Den

sity

Exp

ress

edas

% S

AL

Co

ntr

ol

GR Protein is Selectively Reduced in the Doromedial Hypothalamus (includes the PVN) of LgA

Other Regions Examined: Ventromedial Hypothalamus, Pituitary, Amygdala, Dorsal Hippocampus, Ventral Subiculum, Medial Prefrontal Cortex


Sal ShA LgA0

25

50

75

100No Restraint Restraint

SA GROUP

Mea

n C

orr

ecte

d G

ray

Lev

el

No Res Res0

25

50

75

Mea

n C

orr

ecte

d G

ray

Lev

el

*

Basal or Restraint-Induced Increases in CRH mRNA in the PVN

is not Altered by Cocaine SA

• Measured 1.5 hrs after 30 min of restraint• 21 day after 14 days of ShA, LgA, or SAL SA


Summary

• The response of the HPA axis to stressors is augmented by prior cocaine exposure.

• Long-term augmentation of HPA responsiveness to stressors may be partly attributable to impaired negative feedback regulation due to reduced GR protein expression in the hypothalamus.

• However long-term augmentation of stressor-induce CRH mRNA in the PVN measured at a single time-point following restraint was not oberved.

• Augmented HPA responsiveness during times of stress may promote glucocorticoid-dependent plasticity, thus fueling the addiction cycle.

Acknowledgements

NIDA Grant Number DA 15758

CollaboratorsDavid BakerWilliam CullinanM. Behnam GhasemzadehDana Ziegler

Research AssistantsLee TangEric KatzMichael Hoks

StudentsTayyiba KhanDavid FrancisJoe SergeTanveer SajanLoren Cooper

Ventral Tegmental AreaCRF-R2 Receptor

Medial Prefrontal Cortex Nucleus Accumbens

DOPAMINEGLUTAMATE

CRF,GLUCORTICOIDS

DRUG-SEEKINGBEHAVIOR

Nucleus Accumbens

Ventral Tegmental AreaCRF-R2 Receptor

Medial Prefrontal Cortex

GLUTAMATE

DOPAMINE

DRUG CRAVING/USE

CRF,GLUCORTICOIDS

STRESS

Glucocorticoid-Dependent Neuroplasticity: Fueling the Cycle of Stress and Addiction John Mantsch,...

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