Possible beneficial effects of melatonin supplementation on arsenic-induced oxidative stress in Wistar rats

The effects of melatonin on arsenic-induced changes on cellular antioxidant system were studied in male rats of the Wistar strain. Arsenic treatment (i.p. as sodium arsenite) was done at a dose of 5.55 mg/kg body weight (equivalent to 35% of LD50) per day for a period of 30 days, while melatonin supplementation (i.p.) was performed at a dose of 10 mg/kg body weight per day for the last 5 days prior to sacrifice. Melatonin supplementation reversed the arsenic-mediated changes in reduced glutathione (GSH) level and lipid peroxidation in liver and kidney. Arsenic-induced decreased glutathione reductase activity in liver and increased activity in kidney was appreciably counteracted by melatonin. Melatonin also inhibited arsenic-induced free hydroxyl radical production in the tissues. The decreased superoxide dismutase (SOD) activity in liver and kidney and that of catalase in liver due to arsenic treatment were also counteracted by melatonin. It is suggested that melatonin acts as a protective agent against arsenic-induced cellular oxidative stress.     

褪黑素对多柔比星所致肾病的保护作用

本研究旨在观察褪黑素 ( MT)对大鼠“阿霉素肾病”的保护作用 .将所有受试动物分为 5组 ,即正常组 ,MT( d0 - d7,5mg·kg-1·d-1,ig)组 ,多柔比星模型组 ( d 1 ,Dox,5mg· kg-1,iv)组和MT( d 0 - d 7,0 .5,5mg· kg-1· d-1) + Dox( d 1 ,5mg· kg-1,iv)组 .检测大鼠 d7,d1 4,d2 1和 d2 8时尿蛋白 ,尿丙二醛排泄量和 d 2 8时血浆生化指标 .结果显示 ,Dox组大鼠呈典型的肾病综合征 ,MT+ Dox组大鼠尿蛋白减少 ,血浆蛋白明显回升 ,血脂降低 ;同时 ,Dox组动物尿丙二醛显著增加 ,MT+ Dox组丙二醛降低 .这些结果表明 ,MT可减轻“阿霉素肾病”大鼠肾损害 .     

Role of melatonin in mitigating chemotherapy-induced testicular dysfunction in Wistar rats

Testicular cancer is the most common cancer affecting men of reproductive age, and its incidence is increasing steadily. A regimen of cisplatin (P), vinblastin (V) and bleomycin (B) (PVB) is the standard chemotherapy for testicular cancer. Though PVB-based chemotherapy has been widely used against germ cell tumors, it is associated with induction of oxidative toxicity and a transient or permanent loss of fertility. However, the mechanism of action of PVB on the testis is not thoroughly elucidated. Using a rat model, we investigated the persistence of the effects of PVB on steroidogenesis, spermatogenesis and testicular oxidative status and architecture. Further, we have also studied whether administration of melatonin has any protective effect on testicular physiology in the PVB-treated rats, since melatonin exerts influence on the antioxidant defense system. The body weight of the PVB-treated rats did not show significant change as compared with the control group. Significant decrease in the weight of the testis was observed with a reduction in volume in the PVB-treated rats. Administration of PVB caused a reduction in the testicular steroidogenesis and spermatogenesis. The circulatory levels of testosterone were also significantly reduced with an elevation of FSH and LH in the PVB-treated rats. Testicular architecture was severely affected with a reduction in seminiferous tubule diameter and epithelial height. The activities of superoxide dismutase and catalase were decreased while the levels of lipid peroxidation increased significantly in the testis of the PVB-treated rats indicating depletion of antioxidant defence system and elevation of oxidative stress. Co-administration of melatonin mitigated these changes in the PVB-treated rats.     

Prospective protective role of melatonin against arsenic-induced metabolic toxicity in Wistar rats

Subchronic exposure to arsenic is associated with alteration of glucose homeostasis. Arsenic treatment (as sodium arsenite) of male Wistar rats (weighing 130-150 g) at a dose of 5.55 mg kg(-1) body weight (equivalent to 35% of LD(50)) (i.p.) per day for a period of 30 days produced hypoglycemia, with associated increased urinary excretion of glucose and depletion of liver glycogen and pyruvic acid contents. Mobilization of free amino acids from kidney to liver was facilitated by arsenic treatment. Arsenic exposure significantly decreased the glutamate-pyruvate transaminase activity in kidney. Glucose 6-phosphatase activity in liver tissue was also significantly decreased after arsenic treatment. In addition to these, liver lactate dehydrogenase activity was elevated due to arsenic treatment. Melatonin supplementation (i.p.) at a dose of 10 mg kg(-1) day(-1) for last five days prior to sacrifice reversed most of the above changes caused by arsenic. Melatonin, being a potent free radical scavenger may reduce arsenic-induced free radical production, and thereby, eliminating its toxic effects. So, arsenic-induced hypoglycemia, with associated glycogenolytic as well as glycolytic activities of liver can be partially counteracted by melatonin supplementation. Accordingly, it may be suggested that melatonin can serve as a prospective protective agent against arsenic-induced metabolic toxicity.     

Reproductive adverse effects of fipronil in Wistar rats

The purpose of the present study was to investigate possible reproductive adverse effects of fipronil (Frontline TopSpot) in female Wistar rats. The pesticide was topically applied to rats (single dose) at different concentrations (70, 140 and 280 mg/kg) and hormonal analysis, estrous cycle, and pregnancy and outcome data were determined. Treatment with fipronil altered cyclicity of female rats lengthening the estrous cycle (days) after a single topic administration of 70 mg/kg (9.7+/-1.18) or 280 mg/kg (14.5+/-1.45) when compared to control (4.8+/-0.17). In the mating study fipronil reduced the pregnancy index (67%) in the highest dose group (280 mg/kg). Plasma progesterone and estradiol levels, obtained in different periods after treatment with fipronil (70 mg/kg), were significantly different 96 h after treatment, when compared to controls. In summary, the results of the present study indicate that fipronil may alter the normal functioning of the endocrine system and cause adverse reproductive effects in female rats.     

Teratogenic effects of diphenyl diselenide in Wistar rats

Diphenyl diselenide is an organoselenium compound with potential therapeutic use. The present study evaluates the effects of single maternal subcutaneous injection of 50 and 100 mg/kg diphenyl diselenide [(PhSe)₂] at gestational days (GD) 6, 10 or 17 in Wistar rats. The highest dose of (PhSe)₂ was also administered at GD 7–12. External and internal fetal soft-tissue examination was performed at GD 20. No mortality was observed in fetuses or dams at any (PhSe)₂ treatment group. Neither did exposure to (PhSe)₂ cause significant changes to fetal body weight, organ weight, or fetal size when administered at GD 6–8, 10–12 or 17. Exposure to 100 mg/kg (PhSe)₂ at GD 9 produced significant changes in fetal biometry (crown-rump (CR) length) and body weight. No significant increase in the proportion of fetuses with external visible abnormalities was observed in groups exposed to (PhSe)₂. Skeletal anomalies were observed in fetuses in the GD 9–11 treatment groups and included incomplete ossification of cranial bones, misshapen and incomplete ossification of sternebrae, reduced sternebrae number, wavy and extra ribs, incomplete ossification of fore and hindpaw bones and incomplete ossification of sacral and caudal bones. We conclude that maternal administration of (PhSe)₂ during GD 7–12 led to increased incidences of these skeletal variations or anomalies, but did not cause externally visible malformations in rat fetuses.     

海马内微量注射褪黑素的免疫调节作用

研究褪黑素（ＭＴ）经海马对大鼠免疫系统的影响。微量注射ＭＴ１μｇ至双侧海马，可显著地增强脾淋巴细胞ＣｏｎＡ诱导的增殖反应，其量效曲线呈钟罩形。连续３ｄ注射ＭＴ，能明显提高脾细胞产生ＩＬ－２和腹腔巨噬细胞产生ＩＬ－１，还能增强ＮＫ细胞活性。提示，ＭＴ能通过海马调节免疫功能。     

Citrinin and endosulfan induced teratogenic effects in Wistar rats

Dietary exposures to food pollutants such as mycotoxin(s) or pesticide(s) are most significant due to their adverse effects on the production and reproduction in animals and the human population. The present investigation was conducted to evaluate the teratogenic potential of citrinin (CIT) and endosulfan either alone or in combination in pregnant rats during gestational days 6-20. Endosulfan (1 mg kg(-1) body weight, by oral intubation) and CIT (10 mg kg(-1) feed, through diet) when administered either alone or in combination in pregnant rats caused significant teratogenic effects in the developing fetuses. There was no maternal mortality, however, reduced maternal weight gain and number of live fetuses and increased fetal resorptions were recorded in all the treated groups. The fetal body weights and crown to rump lengths were significantly decreased and the per cent gross, visceral and skeletal anomalies were significantly increased in the fetuses of dams of all the treated groups. The internal hydrocephalus, cerebellar hypoplasia, microphthalmia, contracted and notched kidneys, multilobulated liver, dilated renal pelvis, incomplete ossification of skull bones, rib anomalies and sacral and caudal vertebrae agenesis were the important fetal malformations. The occurrence of fetal gross, skeletal and visceral malformations was more severe in the combination group, suggesting an additive interaction of CIT and endosulfan in inducing developmental toxicity in Wistar rats.     

Toxicological effects of cadmium during pregnancy in Wistar albino rats

Cadmium is a heavy metal and widespread environmental toxicant. This study investigated the effects of prenatal Cd exposure on fetal growth and limb development in rats. Pregnant rats were given 0, 4 or 8 mg/kg/day (equivalent to ≈ 0, 30 or 60 ppm) of cadmium as CdSO₄ in their drinking water from conception to gestation day 20. Cd significantly (p<0.001) and dose-dependently inhibited maternal weight gain and caused abortion of pregnancy. In addition, Cd significantly (p<0.001) decreased fetal body weight, forelimb and hindlimb bone lengths, compared to controls. These effects were sex-dependent, greater in the female offspring. Furthermore, there were reductions in the weights, and alterations in the histology of maternal placenta, ovary and liver of Cd-exposed rats. The results indicate that cadmium will cause abortion of pregnancy and sex-dependent impairment of fetal growth and limb development, which may be consequent upon alterations in ovarian and placental functions.     

Reproductive effects of dietary soy in female Wistar rats.

This study was designed to assess the effects of administration of dietary soy on reproductive function and fertility of female Wistar rats. Four groups, each of 20 females, were used. Control animals were fed a standard cereal-based diet for rats. Treated animals were fed a standard diet supplemented with 0.7%, 1.2% or 2.4% of a soy extract. Treatment started at weaning and continued until day 7 post-partum (day of sacrifice). Growth depression was seen in the 2.4% soy group. Vaginal opening occurred earlier in females receiving soy supplemented feed when compared with controls. Analysis of vaginal smears revealed that all animals were cycling, although an increase in the mean duration of each cycle was seen in the 2.4% soy group. Uterine effects were observed in high-dose females and included increases in weight, oedema, endothelial hyperplasia and leucocytic infiltration. Vaginal modifications (i.e. inflammation, hyperkeratosis and dyskeratosis) and alterations in the distribution of follicular size in the ovaries were also observed among treated animals. These data suggest that long-term exposure to high doses of phytoestrogens can produce significant agonistic actions in several oestrogen-dependent tissues and parameters, even though in this model no clear influence on reproductive processes was observed.     

Effect of 17beta-estradiol on haloperidol effects in Wistar rats

It is established that the haloperidol catalepsy is much less pronounced in Wistar females than in males. Estradiol (10 mg/kg, i.p.) decreased intensity of the haloperidol catalepsy, reduced the haloperidol-induced increase in the dopamine turnover, and decreased the level of dopamine metabolites in nucleus accumbens of both female and male test animals. However, these effects are also more pronounced in females.     

Evaluation of hepatotoxicity and clastogenicity of carbofuran in male Wistar rats

Carbofuran based pesticides have gained wide usage in Nigeria recently. Consequently, animals and human populations are exposed to them in the environment. Information on in vivo toxicity of carbofuran in experimental models is scanty. The present study therefore examined the hepatotoxicity and clastogenic effects of carbofuran in rats. Male Wistar rats were exposed to carbofuran (p.o) at 0–5 mg/kg bw for 5 weeks. Carbofuran induced significant (p < 0.05) increase in the serum activity of gamma-glutamyltransferase when compared with the negative control, but not activity of serum alanine and aspartate aminotransferases. It also significantly (p < 0.05) induced micronucleated polychromatic erythrocytes formation in the bone marrow as compared with the control. The level of induction is dose dependent in both cases. In addition, there was significant (p < 0.05) higher number of hepatic cells in the cell/mm² assay for the group treated with carbofuran. Histopathological analysis of liver samples from the treated groups revealed lesions ranging from general congestion (portal, central venous and sinusoidal), mild periportal cellular infiltration, diffused sinusoidal congestion and hepatic necrosis to severe congestion. Findings from this study suggest that carbofuran has clastogenic and hepatotoxic effects in rats. It therefore may constitute an environmental health risks in individuals so exposed.     

Nitrosation of quaternary ammonium compounds in vivo in the Wistar rat

1. Animals dosed orally with nitrite (1.5 × 10^?3 mol/kg) and nonyl dimethylbenzylammonium bromide (2.9 × 10^?4 mol/kg) exhibit liver damage within two hours; cetyl trimethylammonium bromide plus nitrite was not significantly hepatotoxic.

2. Both nonyl dimethylbenzyl ammonium bromide and cetyl trimethylammonium bromide were demethylated by rat-liver microsomal preparations; substrate concentrations of 1 mM or more were inhibitory.

3. Bile from rats given i.p. doses of cetyl trimethylammonium bromide, nonyl dimethylbenzylammonium bromide or dodecyl dimethylbenzylammonium bromide contains only metabolites, no unchanged compounds were detected.     

Nitrosation of quaternary ammonium compounds in vivo in the Wistar rat

Animals dosed orally with nitrite (1.5 X 10(-3) mol/kg) and nonyl dimethylbenzylammonium bromide (2.9 X 10(-4) mol/kg) exhibit liver damage within two hours; cetyl trimethylammonium bromide plus nitrite was not significantly hepatotoxic. Both nonyl dimethylbenzyl ammonium bromide and cetyl trimethylammonium bromide were demethylated by rat-liver microsomal preparations; substrate concentrations of 1 mM or more were inhibitory. Bile from rats given i.p. doses of cetyl trimethylammonium bromide, nonyl dimethylbenzylammonium bromide or dodecyl dimethylbenzylammonium bromide contains only metabolites, no unchanged compounds were detected.     

Effects of melatonin on the levels of antioxidants and lipid peroxidation products in rats treated with ammonium acetate

The antioxidant potential of melatonin (MLT) on hyperammonemia (induced by ammonium acetate treatment) were studied in rats. The levels of circulatory ammonia, urea and non-protein nitrogen increased significantly in ammonium acetate treated rats and decreased significantly in rats treated with melatonin and ammonium acetate. In brain tissues, the same pattern of alterations across groups was observed in the levels of thiobarbituric acid reactive substances and lipid profile variables (free fatty acids, triglycerides, phospholipids, and cholesterol). Further, enzymatic (superoxide dismutase, catalase and glutathione peroxidase) and non-enzymatic (reduced glutathione) antioxidants in brain tissues decreased significantly in ammonium acetate treated rats and increased significantly in rats treated with melatonin and ammonium acetate. These biochemical alterations could be due to the ability of melatonin to (i) scavenge a variety of radicals and reactive oxygen species (ii) induce antioxidative enzymes which reduce steady state levels of reactive oxygen species and (iii) stabilize cell membranes which assist them in reducing oxidative damage and thus could prevent oxidative stress in rats.     

地塞米松的诱导效应对环磷酰胺大鼠毒性的影响

目的:观察地塞米松(dexamethasone,DEx)对大鼠细胞色素P450的诱导效应致环磷酰胺(cyclophos-phamide,CPA)对肝脏、肾脏、骨髓和膀胱毒性的影响.方法:雄性Wistar大鼠用DEX 50mg·kg-1·d-1诱导4d后,d5分别ip CPA 0,150和200mg·kg-1后36h,观察实验动物肝脏、肾脏、骨髓和膀胱毒性表现.结果:单独DEX诱导具有轻微的肝脏毒性.CPA单次给药造成骨髓细胞G2M期细胞的比例稍有升高,出现明显的尿蛋白和尿潜血.DEX的诱导作用增加了CPA的毒性:对肝毒性的增强作用主要表现在血浆ALT升高,肝脏总巯基和蛋白巯基含量降低,肝脏组织肝窦狭窄,肝小叶空泡变性;对肾脏毒性增强表现在血浆BUN和Cr升高,尿液蛋白和潜血增加,肾近端小管变性和髓质出血.DEX和CPA 200mg·kg-1合并用药组骨髓细胞的G0/G1期细胞增多,S期细胞明显减少.病理检查表明DEX和CPA合并用药组膀胱发生炎症和出血.结论:DEX诱导后使CPA对大鼠的肾脏、膀胱和骨髓毒性进一步增强,而DEX具有一定的肝脏毒性,与CPA合并给药后肝毒性有增强趋势.     

The effects of sub-chronic exposure of Wistar rats to the herbicide Glyphosate-Biocarb

The object of this study was to analyze the hepatic effects of the herbicide Glyphosate-Biocarb (as commercialized in Brazil) in Wistar rats. Animals were treated orally with water or 4.87, 48.7, or 487 mg/kg of glyphosate each 2 days, during 75 days. Sub-chronic treatment of animals starting from the lowest dose of glyphosate induced the leakage of hepatic intracellular enzymes, alanine aminotransferase (ALT) and aspartate aminotransferase (AST), suggesting irreversible damage in hepatocytes. We observed the increase of Kupffer cells in hepatic sinusoid of glyphosate-treated animals. This was followed by large deposition of reticulin fibers, composed mainly of collagen type III. We may conclude that Glyphosate-Biocarb may induce hepatic histological changes as well as AST and ALT leaking from liver to serum in experimental models.     

褪黑素对大鼠急性脑缺血再灌注损伤保护作用研究

目的　探讨褪黑素 (melatonin ,MT)对急性脑缺血再灌注损伤的保护作用及机制。方法　用线栓法制备大鼠大脑中动脉急性缺血再灌注损伤模型 ,再灌注 2 4h后测定大鼠脑组织中丙二醛 (malondialdehyde ,MDA)含量、超氧化物歧化酶 (superoxidedismutase,SOD)和髓化过氧化物酶(myeloperoxidaseMPO)活性以及血浆中血栓素B2 (throm boxaneB2 ,TXB2 )、6 酮 前列腺素F1α( 6 keto prostaglandinF1α,6 酮 PGF1α)含量。结果　MT 10、2 0mg·kg-1能保护SOD活性、减缓脑组织中MDA的升高 ,2 0mg·kg-1还可恢复血浆中TXB2 与 6 酮 PGF1α的平衡 ,减缓脑组织中MPO的升高。结论　MT对大鼠急性脑缺血再灌注损伤的保护作用与其提高抗氧化酶活性 ,抗脂质过氧化损伤及抗炎作用有关     

Induced PKU in rats: effects of age and melatonin treatment

Newborn rats injected on Days 1-8 of life with L-phenylalanine (2 g/kg) and p-chlorophenylalanine (80 mg/kg) displayed biochemical symptoms analogous to human phenylketonuria (PKU) and maze learning impairments. The behavioral effects were less evident in rats treated on Days 9-16 or 7-24. None of the symptoms observed were alleviated by simultaneous administration of melatonin (10 mg/kg/day).