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J. Rad. Res. Appl. Sci., Vol. 5, No. 5, pp. 1059 – 1079 (2012)

Sex-dependent response of some rat biochemical, histological and embryological features to Squalene administration or/ and gamma radiation exposure M. F. Ibrahim, N. M. Abo-Zid and A. G. Ahmed Radiation Biology Department, National Centre for Radiation Research and Technology (NCRRT),Atomic Energy Authority, P.O. Box 29, Nasr City, Cairo, Egypt.

E-mail: [email protected] Received:14/ 06/2012. Accepted: 18/09/2012.

ABSTRACT Squalene, an intermediate of cholesterol biosynthesis, is known to possess potent antioxidant properties. The objective of the current study was to evaluate the influence of Squalene on some radiation-induced biochemical, histological and embryological changes in Sprague Dawley rats. Squalene was orally administered to rats (5 ml/kg/day) throughout 60 days before whole body gamma irradiation with 4Gy. In adult male & female rats, the results revealed that Squalene has modulated the radiation produced abrupt elevation of total cholesterol (TC), triglycerides (TG) & and low density lipoprotein-cholesterol (LDL-C) levels and reduction of high density lipoprotein-cholesterol (HDL-C) ones in both male & female serum and male liver samples whereas it could not control the abrupt increase of HDL-C and decline of LDL-C in female liver values. Also Squalene has modified the histopathological acquired radiation lesions of both male & female colonic & hepatic tissues yet the female tested colonic sections showed moderate regeneration of crypts & villi layers whereas the hepatic sections yet displayed apparent hemorrhage and fatty liver infiltration of inflammatory cells. However, in the mated male rats and their pregnant counterparts, Squalene considerably restored the radiation induced male and female sex hormonal abrupt changes especially in female rats. Squalene administration to pergnant rats before irradiation at gestational day 17 improved the fetal survival ability as identified by the disappearance of resorption sites in the tested maternal uteri. Hence, it could be concluded that Squalene radioprotective capability surpassed the adult male rats than the female ones though it specified the pregnant females

Ibrahim et al., J. Rad. Res. Appl. Sci., Vol. 5, No. 5 (2012) 1060

by protecting their growing embryos against radiation induced intrauterine fatal effect. Keywords, Squalene – radiation – male – female – pregnancy - lipid profile –

sex hormones - liver – colon -uterus -fetus.

INTRODUCTION

Squalene is unique oil high in Vitamins A and D. The most abundant source of Squalene is from the livers of deep sea sharks found at depths of as much as 1,500 metres. It occurs in Shark liver oils as the major component, comprising up to 85% of the oil.

It also occurs naturally within the human body where it supports natural lubrication for our skin and supports oxygen delivery and toxin removal within all our body's cells1.

However, caution has to be taken when Squalene is routinely consumed as health supplement since pure Squalene proved to be hypercholesterolemic when supplemented to hamsters in diets at the levels of 0.05, 0.1 and 0.5% as verified by elevated serum total cholesterol (TC) and triglycerides (TG) alongside with significant Squalene accumulation in the liver and adipose tissue2. Yet, when administered at 2% level along with feed for 45 days, Squalene was found to exert an antioxidant effect against myocardial infarction by blocking the induction of lipid peroxidation in plasma of experimental rats3.

In males, remarkable reduced levels of serum leptin together with improved reproductive performance have been monitored upon dietary supplementation with Squalene either at 10 mg /kg/ day (for 45 days) in meat type male chickens4 or at 20 mg/kg/day (for 60 days) in pig5.

Besides, dietary Squalene (1%) was found to possess a chemopreventive activity against colon carcinogenesis in male rats 6, while the activity of the Squalene epoxidase is regulated in livers of female ones7.

Also Squalene is an eminent vital part of the synthesis of steroid hormones in the body 8 as well as an intermediate of cholesterol biosynthesis which plays an essential role in normal embryogenesis9.

On the other hand, radiation has been indicted by numerous research studies for producing elevation in triglycerides and cholesterol levels10 & 11 . However, it has been noted that male and female mice exposed to gamma irradiation displayed a hormetic different response on the stress axis (the


hypothalamic-pituitary-adrenocortical axis)12

When male Wistar rats were exposed to 4 Gy of neutrons/γ whole-body irradiation (3.33 Gy of neutrons and 0.66 Gy of γ rays), plasma cholesterol and phospholipid levels increased up to 62 and 37%, respectively, at day 4 after irradiation13 .

In female rats the damaging effect of radiation (1 and 2 Gy) included sharp accumulation of products of lipid peroxide oxidation and suppression of the activities of such enzymes as cytochrome-c-oxidase, NAD.N-cytochrome-c-reductase, ATPase and RNAase in liver nuclei , the effects being intensified with increasing radiation doses14.

Moreover, whereas intraoperative irradiation of the rat colon with 10, 15, or 20 Gy demonstrated a late dose-related formation of perianastomotic fibrosis and adenocarcinoma with limited cell necrosis15, pathological investigation of Cobalt radiation (5 Gy) on the rat liver revealed areas of necrotic hepatocytes and cell swelling16.

It has also been reported that chronic exposure of rats to low doses of (137) Cs decreased the circulating 17beta-estradiol levels17 and that the rat growing embryo or fetus showed high radiosensitivity depending upon dose and developmental stage at irradiation18.

However, studies have shown that Squalene administration conferred some cellular and systemic radioprotection to mice receiving lethal whole-body radiation doses19. Adding Squalene into the diet of mice exposed to lethal dose of whole body gamma irradiation increased their survival rate from 0 to 100 percent20.

Consequently, the current study is proposed to discriminate between the male and female response to the Squalene protection potency against injury inflicted by gamma irradiation to some biochemical, histological and embryological aspects.

MATERIALS AND METHODS:

Experimental animals

Male and female mature Sprague Dawley albino rats weighing 120-150 g were maintained under controlled temperature and light conditions and fed on standard diet and water ad libitum. Cycle stages in female rats were assessed by daily inspection of vaginal smear cytology and all females were selected at the


meta-oestrus stage. Experiments were performed according to the international guidelines of animal handling and care 21 .

Squalene treatment

Squalene solution (M.W. = 410.7) has been purchased from M.P. Biomedicals, Inc., France. Squalene (2%) has been prepared for oral administration (using a stomach tube) to the experimental animals at a dose level of 5 ml/kg/day.

Irradiation Processing

Whole body gamma irradiation of animals was carried out using an indoor shielded AECL/Cesium 137 Gamma cell-40 biological irradiator installed in the “National Centre for Radiation Research and Technology (NCRRT)”, Atomic Energy Authority, Cairo, emitting a dose rate of 0.5 Gy/min. The rats were exposed to 4 Gy gamma-radiation.

Experimental Design

A total number of 24 rat of each sex were equally set into 4 different groups, one of which functioned as control (Group 1), another one was Squalene administered (5 ml/kg/day) for 60 consecutive days (Group 2), whereas the other 2 groups were either radiation exposed (4 Gy) (Group 3) or radiation exposed (4 Gy) subsequent to 60 days of Squalene administration (5 ml/kg/day) (Group 4).

An extra number of virgin females were randomly mated overnight where every two females were housed with a single male rat. Females that did not mate within 2 estrus cycles were excluded from the study whereas females with a vaginal plug were separated in the morning and marked as 0 day pregnant. 24 of each of the mated male rats and the pregnant ones were equally set into 4 different groups as follows:

Group 5: Control rats.

Group 6: Squalene administered rats (5 ml/kg/day) for 60 consecutive days (43 days before and 17 days following gestation for pregnant rats).

Group 7: Gamma irradiated rats (4Gy) (on the 17th gestational day for pregnant rats).

Group 8: Gamma irradiated rats (on the 17th gestational day for pregnant rats) subsequent to 60 days of Squalene administration (43 days before and 17 days following gestation for pregnant rats).


On the assigned day of sacrifice (3 days following every treatment), animals were fasted overnight for biochemical investigations and then anaesthetized with light ether. Intracardiac blood samples were collected from the 8 rat groups. Blood was allowed to clot and centrifuged where serum was obtained and then stored frozen at -20°C in small vials. Concomitantly, the rats of each experimental group are cut open.

Groups 1-4

For biochemical analysis, serum was used for the determination of total cholesterol (TC) according to Allain et al. (1974) 22 , triglycerides (TG) according to Fossati and Prencipe (1982)23 , HDL-cholesterol (HDL-C) according to Trinder (1969) 24. According to Friedewald’s formula25, LDL-cholesterol (LDL-C) has been evaluated by the following equation: LDL-cholesterol (mg/dl) = total cholesterol – (triglycerides/5 + HDL-cholesterol). Liver was then excised after dissection of each animal for the determination of lipid profile in its wet tissue.

For histological assessment, the colons and livers were removed and immediately fixed in buffered formol. Sections were processed routinely for paraffin embedding and sectioned at 6µ then stained with haematoxylin and eosin (HE) and mounted with Canada Balsam. They were then examined by Olympus light microscope to detect the histological or histopathological changes induced.

Groups 5-8

Hormones of mated male and pregnant female rats were determined by radioimmunoassay. Serum testosterone, progesterone and estradiol were assayed according to Albertini & Ekins 26 , Autrere & Benson 27 and Bergquist et al., 28 respectively.

For embryological study, the pregnant rats were all cut open on the 20th gestational day (1 day prior to parturition) and their uteri were removed and pictured.

Statistical Analysis

Student t-test was applied for the statistical analysis of the results obtained according to Snedecor and Cochran 29. Differences were considered statistically significant at P≤0.05.


RESULTS

Biochemical aspects

In male & female rats, the 60 days Squalene oral administration elicited elevated T-Cholesterol and reduced HDL-Cholesterol levels in serum and hepatic tissues together with non significant change in serum LDL-Cholesterol as compared to the control levels, the effect being more prominent in male treated animals. However the female rats showed distinguished decline in serum and hepatic Triglycerides and liver LDL-Cholesterol (Tables 1, 2, 3 & 4).

Even though radiation exposure alone (Group 3) resulted in the expected detrimental recorded consequences in all the tested parameters, yet Squalene administration prior to radiation exposure (Group 4) significantly modulated these abrupt detected lipid profile measurements either in serum (Tables 1 & 2) or in liver tissue (Tables 3 & 4) of the entire treated animal groups especially the male ones.

Regarding the male & pregnant female sex hormones, it has been found that Squalene induced higher augmentation rate in testosterone levels of male rats (+ 4.88%) than either estrogen (+2.11%) or progesterone hormones (+2.94 %) of their pregnant female counterparts versus the control values of the tested hormones (Table 5).

However, the unfavorable measurements of the hormonal levels recorded after merely radiating the rats of both sexes (Group 7) have been ameliorated when Squalene was administered before radiation exposure (Group 8), particularly in progesterone and estrogen hormones of the female rats (Table 5).

Histopathological Observations

Histological examination of the colon revealed no differences for most of the parameters between the control and the Squalene treated groups (Groups 1 and 2 respectively) either in male or female rats where the normal pattern of the mucosal layer and lamina propria was present and nearly no structural changes of the muscle layers and submucosa were observed in the anastomotic area (Figure 1: a, b, c & d).

Also, histological examination of both male and female control and Squalene treated (Groups 1 and 2 respectively) liver sections revealed normal hepatic architecture (Figure 2: a, b, c & d).


Upon radiation treatment (Group 3), the colon sections of the male rats displayed vacuolated and damaged mucosal and submucosal layers with intense merging of crypts and villi together with the emergence of some necrotic and karyolitic nuclei (Figure 1: e). However, the colon tissue of the female ones showed severely damaged mucosal layer and extinction of the lining columnar cells with unidentified villi and ragged crypts walls (Figure 1: f). Squalene administration previous to whole body gamma irradiation (Group 4) was able to partially improve the damaged radiation induced histopathological alterations, especially in the male colon sections (Figure 1: g).

In the same way, the histological hepatic complications associated with the 4 Gy gamma irradiation (Group 3) (Figure 2: e & f) have been reduced in the tested liver sections of the experimental animals that experienced the combination of Squalene and radiation treatment (Group 4) (Figure 2: g & h). Interestingly, the male hepatic sections were more compliant than the female ones to the Squalene potent ability of the hepatic repair as shown by the nearly regenerated hepatic cells and the recovered central vein (Figure 2: g).

Pertaining to the tested uteri of the pregnant rats excised 3 days following whole body gamma irradiation (day 20 of gestation) (Group 7) a remarkable fetal intrauterine mortality together with stunted growth of the live ones have been observed (Figure 3: c) versus the healthy uterus of either the control group or the Squalene supplemented one (Figure 3: a & b respectively) showing fully grown, normally developed and evenly distributed fetuses. It is worth mentioning that Group 8 showed modulations in the uterii of the examined mothers (Figure 3: d) supplemented with Squalene prior to gamma irradiation showing complete intrauterine fetal survival.


Table (1): Total cholesterol (TC), triglycerides (TG), high density lipoprotein-cholesterol (HDL-C) and low density lipoprotein-cholesterol (LDL-C) in serum of male rats following Squalene administration or/and 4 Gy whole body gamma irradiation.

TC (mg/dl)

TG (mg/dL)

HDL-C (mg/dL)

LDL-C (mg/dL)

Control (Group 1) Mean±SE 64.08±0.79 65.63±0.76 23.8±0.70 27.5±0.76

Squalene (Group 2)

Mean±SE

% of change from control

73.98±1.07ab

(+15.45%)

65.45±0.88b

(-0.27%)

13.32±0.55ab

(-44 %)

28.67±0.88

(+4.25%)

Radiation (Group 3)

Mean±SE


112.85±0.83a

(+76.11%)

90.85±0.83a

(+38.42%)

19.75±0.74a

(-17 %)

59.83±0.95a

(+117.56%)

Squalene+ Radiation (Group 4)

Mean±SE


89.77±0.76ab

(+40%)

64.85±0.80 b

(-1.2 %)

16.78±0.76ab

(-29.5 %)

47.5±0.76ab

(+72.7%)

Each value represents the mean ± SE (n=6). a: significance vs control group. b: significance vs radiation group.

Table (2): Total cholesterol (TC), triglycerides (TG), high density lipoprotein-cholesterol (HDL-C) and low density lipoprotein-cholesterol (LDL-C) in serum of female rats following Squalene administration or/and 4 Gy whole body gamma irradiation.

TC (mg/dl)

TG (mg/dL)

HDL-C (mg/dL)

LDL-C (mg/dL)


Squalene (Group 2)

Mean±SE % of change from control

76.5±0.64 ab

(+7.56%)

51±0.65 ab

(-22.34 %)

33.13±0.80 b

(-6.46 %)

23.6±1.17 b

(+1.37%)

Radiation (Group 3)

Mean±SE


104.85±0.6 a

(+47.2%)

81.12±0.77 a

(+23.5%)

27±0.70 a

(-23.77%)

62.48±0.52 a

(+168.4%)


Mean±SE


87.83±0.77 ab

(+23.5%)

67.1±0.37 b

(+2.2%)

31.81±0.63 ab

(-10.19 %)

37.03±0.68 ab

(+59%)

Legend in Table 1.


Table (3): Total cholesterol (TC), triglycerides (TG), high density lipoprotein-cholesterol (HDL-C) and low density lipoprotein-cholesterol (LDL-C) in liver of male rats following Squalene administration or/and 4 Gy whole body gamma irradiation.

TC (mg/dl)

TG (mg/dL)

HDL-C (mg/dL)

LDL-C (mg/dL)


Squalene (Group 2)


38.77±0.53 ab

(+6.48%)

81.0±0.74 b

(-0.3 %)

39.5±0.78 b

(-6.2 %)

81.02±0.7 ab

(-6.15 %)

Radiation (Group 3)

Mean±SE


48.96±0.7 a

(+34.5%)

93.07±0.79 a

(+14.5%)

72.17±0.43 a

(+71.4%)

116.95±0.76 a

(+35.5 %)


Mean±SE


38.7±0.58 ab

(+6.28%)

75.72±0.57 ab

(-6.8 %)

46.75±0.39 ab

(+11%)

105.02±0.79ab

(+21.64 %)

Legend in Table 1.

Table (4): Total cholesterol (TC), triglycerides (TG), high density lipoprotein-cholesterol (HDL-C) and low density lipoprotein-cholesterol (LDL-C) in liver of female rats following Squalene administration or/and 4 Gy whole body gamma irradiation.

TC (mg/dl)

TG (mg/dL)

HDL-C (mg/dL)

LDL-C (mg/dL)


Squalene (Group 2)


37.97±0.5 ab

(+6.44%)

74.78±1.61 b

(-3.5 %)

38.48±0.54 b

(-3.75 %)

22.97±0.75 a

(-14.95 %)

Radiation (Group 3)

Mean±SE


48.02±0.46 a

(+34.6%)

97.75±0.55 a

(+20.1%)

53.23±0.72 a

(+33.1%)

21.32±0.56 a

(-21.06 %)


Mean±SE


38.32±0.41 ab

(+7.42%)

81.45±0.56 ab

(+5.1%)

66.38±0.52 ab

(+66.1%)

18.88±0.78 ab

(-30.1 %)

Legend in Table 1.


Table (5): Male testosterone and pregnant female progesterone & estradiol hormone levels in serum of rats following Squalene administration or/and 4 Gy whole body gamma irradiation.

Male Testosterone ng/ml

Pregnant Female Progesterone

ng/ml

Pregnant Female Estradiol

ng/ml

Control (Group 5) Mean±SE 4.5±0.04 0.33 ± 0.014 9.46 ± 0.44

Squalene (Group 6)

Mean±SE


4.72 ± 0.09 b

(+4.88%)

0.35 ± 0.03 b

(+2.94%)

9.66 ± 0.39 b

(+2.11%)

Radiation (Group 7)

Mean±SE


3.56± 0.14 a

(-20.88 %)

0.82 ± 0.43 a

(+141.18 %)

12.4 ± 0.19 a

(+31.07%)


Mean±SE


3.78 ±0.06 a

(-16 %)

0.52 ± 0.02 ab

(+57.57%)

8.51± 0.13 ab

(-10.04 %)

Legend in Table 1.

a) Male Control Colon (x 200)

b) Female Control Colon (x 200)

c) Male Squalene-treated Colon (x 200)

d) Female Squalene-treated Colon (x 200)

e) Male Radiated Colon (x 100)

f) Female Radiated Colon (x 200)


g) Male Squalene-treated + Radiated Colon (x 200)

h) Female Squalene-treated + Radiated Colon (x 200)

Figure 1: Photomicrograph of colon sections of rats in [Group 1: a) Control male & b) Control female] and [Group 2: c) Squalene-treated male & d) Squalene-treated female] showing: Normal architecture of colon identified by typical mucosal and submucosal layers together with normal crypts and villi with the usual goblet cells (on the borders of the villi). [Group 3: e) Radiated male & f) Radiated female] showing: Severely damaged mucosal layer. Destructed unidentified villi layers alongside with torn crypts walls. Emergence of abnormal mass at the mucosal layer in the radiated male. [Group 4: g) Squalene + Radiated male & h) Squalene + Radiated female showing: Regenerated mucosal & submucosal layers with manifestation of some vacuoles in female tissue. Moderate regeneration of crypts & villi layers illustrated by unidentified details and sticking of some crypts & villi.

a) Male Control Liver (x 200) b) Female Control Liver (x 200)

c) Male Squalene-treated Liver (x 200) d) Female Squalene-treated Liver (x 200)

e) Male Radiated Liver (x 200) f) Female Radiated Liver (x 200)


g) Male Squalene-treated + Radiated Liver (x 200)

h) Female Squalene-treated + Radiated

Liver (x 200)

Figure (2): Photomicrograph of liver sections of rats in [Group 1: a) Control male & b) Control female] and [Group 2: c) Squalene-treated male & d) Squalene-treated female] showing: Normal architecture of hepatic cells with normal nuclei, central vein and blood sinusoids. [Group 3: e) Radiated male & f) Radiated female] showing: Ruptured and ill-defined hepatic cells. Infiltration of inflammatory cells in central vein. Extremely dilated and expanded central vein and blood sinusoids. Vacuolated hepatic cells with degenerated cell membrane of necrotic, karyolytic and pyknotic nuclei in the radiated females with death of the majority of the hepatic cells of male ones. [Group 4: g) Squalene + Radiated male] showing: Nearly normal hepatic architecture displaying regenerated hepatic cells with complete cell membranes and nuclei. Appearance of Kupffer cells. Many cells with mitosis. Improved central vein. [Group 4: h) Squalene + Radiated female] showing: Fatty liver Infiltration of inflammatory cells and hemorrhage.

a) Uterus of a control pregnant rat (x1) b) Uterus of a Squalene-treated pregnant

rat (x1)

c) Uterus of a radiated pregnant rat (x1)

d) Uterus of a Squalene-treated+Radiated pregnant rat (x1)


Figure (3): Photomicrograph of uteri on day 20 of gestation in Group 5 [a) Control rats] & Group 6 [b) Squalene treated rats] showing: healthy, alive normally distributed implanted embryos, Group 7 [c) Radiated rats] showing: undersized embryos, intrauterine pale appearance denoting embryonic death in addition to resorption sites and Group 8 [d) Squalene and radiated pregnant rats] showing: live healthy fetuses extending in both uterine horns showing discrepancy in sizes.

DISCUSSION:

Based on experiments and medical experiences by various herbal experts, Squalene, which constitutes 0.2-0.7% of Olive oil, is the main material in cholesterol biosynthesis in the body, which in turn functions as hormone builder30 .The average intake of Squalene is 30 mg/day in the United States, which with higher olive oil consumption as in Mediterranean countries, may reach 200-400 mg/day 31. Since Squalene is a poly-unsaturated hydrocarbon liquid (C30 H50), therefore in order to stabilize, it attaches hydrogen ions from water and acids in the body and frees oxygen to the body thus stimulating the metabolism of the body by supplying an abundance of oxygen to the tissues in such a manner that its highly beneficial action is not limited to a particular organ1.

Some animal studies have found that a potential daily dietary amount of Squalene increases cholesterol synthesis 32 and may raise blood cholesterol levels 33. This evidence has been corroborated by the present recorded hypercholesterolemic effect of Squalene upon 60 days of continuous oral submission (Tables 1, 2, 3 & 4) which might be attributed to the accumulation of Squalene in the liver and adipose tissue2 since hypercholesterolemia has been reported in mice overexpressing Squalene synthase in the liver 34 .

In the present work, the non significant elevation in serum testosterone , progesterone and estrogen levels of the male and pregnant female Squalene treated rats can be likely due to the dose level (5 ml/kg/day) manipulated and the duration exploited (60 days) in the contemporary experimental study. This consideration has been testified by former studies revealing that feeding with Squalene at 10 mg/kg/day was incapable of either increasing the serum testosterone levels or reducing the levels of leptin in boars as compared to the control values whereas feeding with a higher dose of Squalene have significantly done both4&5 .

However, the radiation triggered abrupt elevations in most of both serum and liver lipid profile parameters of either the male or female exposed


rats (Tables 1, 2, 3 & 4) might be ascribed to the radiation-induced vascular damage and markedly reduced body antioxidant stores16 .

Also the present 4 Gy gamma irradiation elicited significant histopathological changes in both the colon and liver tissues of male and female treated rats ranging from ragged crypts walls to necrotic invasion to the tested colon sections together with hepatic fatty degeneration or complete death of the majority of the hepatic cells. In accordance several epidemiological studies and animal experiments have implicated gamma irradiation as increasing the risk of colon cancers where dose-related changes included formation of adenocarcinomas and fibrosis in addition to mucosal ulcerations suggesting radiation-induced cell necrosis15. Similarly, radiation-induced liver injury resulted in sinusoidal congestion, hyperaemia and fatty infiltration, periportal fibrosis and disorganization of the lobular architecture 35 .

However, in the majority of the tested specimens of the present work the males proved to be more radiosensitive than their female counterparts since the males carried most of the radiation induced genetic burden 36. Supporting the same evidence, it has been previously indicated that male and female mice exposed to gamma radiation displayed a hormetic different response on the stress axis (the hypothalamic-pituitary-adrenocortical axis) since testosterone is known to be inhibitory, whereas estrogen is stimulatory12 .

It is worth mentioning that the present work specified the colonic and hepatic tissues for evaluating Squalene potential preventive properties against the imposed radiation induced lesions since the colon is known to be one of the major organs of elimination of toxins and waste from the body that have been associated with resistance to various chemotherapeutic agents 37 while the liver is actively involved in many metabolic functions and is the frequent target for a number of toxicants 38 .

Squalene daily continuous administration for 60 days prior to 4 Gy gamma irradiation was able to obviously ameliorate the induced serum and tissue undesirable deleterious consequences. Supporting evidence is provided by a number of experimental studies which have shown that Squalene conferred some cellular and systemic radioprotection even to mice receiving lethal whole-body radiation doses (6, 7 or 8 Gy) of whole body gamma-irradiation (Cesium-137) due to its chief attribute in affording cells protection from oxidation reactions19 .


Moreover, it has been stated that Squalene can effectively inhibit chemically-induced colon tumourigenesis in rodents due to its anti-oxidative activities especially when given before and/or during carcinogen treatment31. This assumption has been recently approved by the American Cancer Society 33

who declared that Squalene has been promoted as having cell-protecting abilities, which may reduce the side effects of chemotherapy.

Yet the present observations of Squalene radioprotective ability have been more expressed in the male experimental rats rather than the female ones. This phenomenon was endorsed by former studies indicating that Squalene modulates lesion development in a gender specific manner, and that accumulation of hepatic fat by liver is highly correlated with lesion progression in males. Hence, Squalene administration could be used as a safe alternative to correct hepatic steatosis and atherosclerosis particularly in males 39 .

Furthermore, the fetal intra-uterine death subsequent to prenatal whole body gamma irradiation induced during organogenesis (Figure 3: c) in the present work has been frequently reported by several research studies since the mammalian embryo and fetus are known to be highly radiosensitive 40,18.

However, the intrauterine radiated embryos were rescued by supplementing the dams with Squalene (Group 4) since Squalene acts as a particularly effective antioxidant in quenching the free radicals generated by radiation. It has been proved that adding Squalene into the diet of mice exposed to lethal dose of whole body gamma irradiation increased their survival rate from 0 to 100 percent20 .A similar observation has been monitored in Figure 3: d where all the embryos survived even after maternal irradiation despite their reduced growth rates.

Given that the cholesterol metabolism plays an essential role in normal embryogenesis and that the embryonic lethality of mice may result from cholesterol deficiency9 , thus it might be speculated that Squalene administration to female rats pre radiation exposure at the 17th gestational day has been able to act as a cholesterol-supplying system to their rapidly growing embryos whose placental system might have failed to function appropriately following the 4 Gy gamma irradiation at this highly sensitive developmental stage.

Although the exact mechanism of the radioprotective effect of Squalene is unknown41 yet some authors stated that Squalene reduces radiation induced


damage by its antioxidant activities and stabilized oxygen radicals42 & 43.

CONCLUSION

The present study aims to demonstrate the distinctive radioprotective capability of Squalene in a sex dependent manner, a merit that favors the male gender despite its well known proposed higher radiosensitivity. However, even though the male rats in the present study were privileged by the Squalene radioprotective potency yet the female pregnant mothers exhibited a higher sex hormonal response to Squalene ameliorating outcome, thus guarding their developing embryos against radiation imposed intrauterine death.

Presumably, further studies are needed to fully identify the radioprotective effect of Squalene, as well as its possible detrimental effects.

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اإلشعاعیةاإلشعاعیةبحوث بحوث مجلة المجلة ال والعلوم التطبیقیةوالعلوم التطبیقیة

)٢٠١٢( ١٠٧٩ – ١٠٥٩ ص ص ٥ عدد ٥ مجلد

البیوكیمیائیة والھیستولوجیة تغیراتاإلستجابة المشروطة بالجنس لبعض الو التعرض لإلشعاع الجامي في /أو الناجمة عن تعاطي السكوالین والجنینیة الجرذان

أمال أحمد غریب ـناھد أبو زید ـمھا فوزي إبراھیم

.مدینة نصر، القاھرة، مصر ٢٩ب .ع،صقسم بحوث بیولوجیا اإلشعاع،المركز القومي لبحوث وتكنولوجیا اإلشعا

من -التى تعتبر الوسیط الرئیسي للتخلیق الحیوي للكولیسترول في الدم -تعد مادة السكوالین وعلیھ فإن الدراسة الحالیة تھدف إلى تقییم تأثیر السكوالین على بعض التغیرات .المضادات القویة لألكسدة

ولذا فقد تم إعطاء .الناجمة عن التعرض الكلي لإلشعاع في الجرذانالبیوكیمیائیة والنسیجیة والجنینیة ٤(یومًا قبل تعریضھا لإلشعاع الجامي ٦٠لمدة ) یوم/ كج/ ملج ٥(السكوالین للجرذان عن طریق الفم

).جرايوقد أظھرت النتائج قدرة السكوالین على تحسین اإلرتفاع المفاجئ الذي سببھ اإلشعاع في

-LDL(والبروتین الدھني منخفض الكثافة ) TG(والشحوم الثالثیة ) TC(مستویات الكولیسترول الكلي C ( واإلنخفاض في البروتین الدھني عالي الكثافة)HDL-C (اث على في عینات الدم والكبد للذكور واإلن

و HDL-Cحد سواء، بینما لم تستطع مادة السكوالین السیطرة على الزیادة المفاجئة في مستوى ال .في كبد اإلناث المعرضة لإلشعاع LDL-C الھبوط في مستوي ال

كما أسفرت النتائج أیضًا على قدرة السكوالین في تعدیل التغییرات الھیستوباثولوجیة الناتجة لجامي سواء في أنسجة القولون أو الكبد للذكور واإلناث مع مالحظة التعدیل عن التعرض لإلشعاع ا

الجزئي فقط في طبقات أنسجة القولون في اإلناث كما لم تخلو قطاعات الكبد الدھني لإلناث من النزف .والتسلل الواضح للخالیا الدھنیة

ات الجنس في دم األزواج ومع ذلك فقد أثبتت مادة السكوالین فعالیتھا في تحسین تركیز ھرمون .من الذكوربل و أكثر في دم اإلناث الحوامل بعد التأثر السلبي باإلشعاع

١٧+ یوم قبل الحمل ٤٣(وبالتالي فقد لوحظ أنھ عند إعطاء مادة السكوالین للجرذان الحوامل تھم على البقاء من الحمل أنھ قد تحسنت قدرة أجن ١٧قبل تعریضھم لإلشعاع في الیوم ال) یوم بعد الحمل

.أحیاء كما ھو واضح من إختفاء مواقع اإلمتصاص في أرحام أمھاتھمالبالغة عن اإلناث في الجرذانوعلیھ فإنھ یمكن أن نخلص إلى أن السكوالین قد میز ذكور

قدرتھ على حمایة كلیھما من التأثیر الضار لإلشعاع على الرغم من أنھ میز الجرذان الحوامل من خالل . تھ على حمایة أجنتھم النامیة داخل أرحامھم من التأثیر القاتل لإلشعاعقدر

–الكبد -الھرمونات الجنسیة -الدھون - الحمل -انثى -ذكر - اإلشعاع -السكوالین : كلمات البحث .الجنین -الرحم -القولون

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