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Comparative Study 2005; 26(6): 680-684 PubMed PMID: 16380707 Citation  Keywords:  Amyloid:administration & dosage, Animals, Cells, Cultured, Dose-Response Relationship, Drug, Injections, Intravenous, Injections, Intraventricular, Islet Amyloid Polypeptide, Male, Pituitary Gland:cytology, Prolactin:blood, Rats, Rats, Inbred WKY,.   

OBJECTIVE: Amylin is a 37-amino acid peptide that is secreted from the pancreatic beta cells. This peptide is cosecreted with insulin from the pancreas by glucose. Amylin plays a role in glucose homeostasis and in the regulation of lipid metabolism. Amylin receptors were identified in central nervous system of rats. There is no available data on the effects of amylin on the pituitary hormones secretion. The aim of this study was to evaluate the effect of amylin on prolactin release in vivo and in vitro experiments in male adult Wistar Kyoto rats.

METHODS: Amylin in a dose of 1 microg/5 microl was injected intraventricularly (i.c.v) during 5 min. using automatic pump. The control group received 5 microl cerebrospinal fluid. Amylin was injected intravenously (i.v) in a dose of 10 microg in 300 microl 0.9% NaCl. The control group received 300 microl 0.9% NaCl. In vitro experiment was performed in the pituitary cells culture conditions. Amylin was added to pituitary cell culture in a dose of 1, 10, 100 nM. Prolactin concentrations were determined using RIA methods.

RESULTS: Central or peripheral administration of amylin caused a significant decrease of serum PRL concentrations as compared with control after 120 min. After 240 minute incubation of the pituitary cells culture with amylin in doses of 10 nM and 100 nM a significant inhibition of the release of PRL was found. However we found that the effect of amylin on the release of PRL depended on dose and time of incubation. A significant increase of PRL level was observed in cultured media in the presence of 1 nM of amylin after 60 min.

CONCLUSION: Our results indicate that amylin administrated centrally and peripherally as well in the cell culture inhibits PRL release....

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Comparative Study 2005; 26(6): 843-847 PubMed PMID: 16380695 Citation  Keywords:  Animals, Anticonvulsants:toxicity, Female, Fertility:drug effects, Fetal Resorption:chemically induced, Fructose:analogs & derivatives, Male, Organ Size, Ovary:anatomy & histology, Pregnancy, Rats, Rats, Sprague-Dawley,.   

PURPOSE: The objectives of this study is to investigate the toxic effects of Topamax (100 mg/kg/body weight) on the reproductive system after administration to female Sprague-Dawley rats weighing 250-300 g for two time periods 4 and 12 weeks.

METHODS: Twenty adult female rats were divided into two groups and exposed to Topiramate diet at a concentration of 100 mg/kg/body weight for two periods of time. First group containing 10 rats received treatment for 4 weeks and a second group of 10 rats received the same dose of treatment for a period of 12 weeks and compared with twenty non-exposed female rats received vehicle treatment. Female rats were allowed mating with males after 10 days prior to the last administration dose. Animals were autopsied under light anesthesia after mating and several parameters were determined including: number of pregnant rats, body and reproductive organ weight, number of implantation sites, viable fetuses, and resorption sites. Assessment of pregnancies in females was measured and the significance of these results was calculated using student's 't' and Chi-square tests.

RESULTS: The effect of Topamax exposure on fertility was assessed in terms of pregnant rats number, implantation sites, viable fetuses, and resorption sites. Exposure to Topamax for 4 weeks did not have much effect on fertility. Significant decrease in the relative ovarian weights and embryo weights in rats exposed to Topamax were observed. Exposure to Topamax for a 12 weeks resulted in a reduction in the percentage of pregnancies and in the number of implantation sites, when compared with controls in both treatment periods. Rats receiving 12 weeks treatment showed an increase in ovarian weights and a decrease in viable fetuses number. These results indicate that long-term exposure of female rats to Topamax causes adverse effects on the reproductive system and fertility.

CONCLUSION: The results of the current study suggest that ingestion of Topamax by adult female rats causes adverse effects on fertility and reproduction....

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Journal Article 2005; 26(6): 823-829 PubMed PMID: 16380694 Citation  Keywords:  Aggression:drug effects, Androgen Antagonists:pharmacology, Animals, Behavior, Animal:drug effects, Female, Fertility:drug effects, Male, Organ Size, Plant Extracts:pharmacology, Rats, Ruta, Sexual Behavior, Animal:drug effects, Sperm Motility:drug effect.   

BACKGROUND: The Ruta graveolens L. is currently used by the Jordanian population systemically for its antispasmodic, diuretic, sedative, and analgesic effects and externally for its antirheumatic effect.

OBJECTIVE: To study plant effects on the reproductive system and fertility using adult male albino rats with special emphasis on the aggressive behavior and sex behavior. The aqueous extracts of Ruta graveolens L. solution was fed orally to male albino rats at a dose of 500 mg/kg body weight for 60 days.

RESULTS: This dose induces a significant decrease in the weight of reproductive organs (P<0.01) when compared to controls. The sperm motility and density in cauda epidydimides and testicular ducts were significantly decreased (P<0.01). A significant decreased (P<0.001) in spermatogenesis activity is observed in somniferous tubule. Treated rats testicular cell population showed a decrease in number of spermatocytes and spermatids (P<0.001) when compared to controls. Serum hormonal assay indicated a decrease in testosterone and follicular stimulating hormone levels in treated rats. A decrease in number of female rats impregnated by males receiving treatment was observed and demonstrated by a decrease in the implantation sites and viable fetuses number (P<0.01). The ingested extract also suppresses the sexual behavior in adult male rats expressed by a prolongation of first mount time, increase in intromission latency, decrease in intromissions number, and prolongation of the post-ejaculatory interval. This led to reduction of the ejaculation time and increase of the post ejaculatory intervals. Ingestion of R. graveolens markedly abolished aggressive behavior parameters in adult male treated rats namely, a suppression in lateralization, boxing bouts and ventral presenting postures.

CONCLUSION: The aqueous extracts of Ruta graveolens L might have adverse effects on territorial aggression and sexual behavior in male albino rats....

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Comparative Study 2005; 26(6): 795-798 PubMed PMID: 16380688 Citation  Keywords:  Animals, Antioxidants:metabolism, Brain:enzymology, Glutathione:metabolism, Hyperthyroidism:metabolism, Lipid Peroxidation:physiology, Liver:enzymology, Male, Malondialdehyde:metabolism, Myocardium:enzymology, Pineal Gland:physiology, Rats, Rats, Sprague-.   

OBJECTIVE: Thyroid hormones regulate energy metabolism and act on the mitochondria, which is an important source of free radicals in the cell. Reactive oxygen types play a significant role in physiological mechanisms, but in excessive amounts they can cause oxidative damage in molecules. The aim of the present study was to determine levels of lipid peroxidation caused by induced hyperthyroidism in cerebral, hepatic and cardiac tissues of pinealectomized rats.

METHODS: Experimental animals used in the study were allocated to three groups as general control group, hyperthyroidism-sham pinealectomy group and hyperthyroidism-pinealectomy group. GSH and MDA levels in cerebral, hepatic and cardiac tissues were evaluated at the end of the 3-week study period.

RESULTS: It was found that MDA levels in cerebral, hepatic and cardiac tissues were the highest in hyperthyroidism and pinealectomy group and that these values were higher in hyperthyroidism-sham pinealectomy group than in the control group (p<0.001). It was seen that tissue GSH levels significantly increased in hyperthyroidism-sham pinealectomy group (p<0.001) and that the increase in hyperthyroidism and pinealectomy group was higher than the increase in the control group only (p<0.001).

CONCLUSION: Results of our study show that MDA and GSH levels in cerebral, hepatic and cardiac tissues increased due to hyperthyroidism and that the increase in MDA levels became more evident and GSH levels were significantly suppressed after pinealectomy....

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Comparative Study 2005; 26(6): 806-810 PubMed PMID: 16380687 Citation  Keywords:  Animals, Glutathione:metabolism, Hyperthyroidism:chemically induced, Kidney:metabolism, Lipid Peroxidation, Male, Malondialdehyde:metabolism, Melatonin:metabolism, Oxidative Stress:physiology, Rats, Rats, Sprague-Dawley, Testis:metabolism, Thyroxine,.   

OBJECTIVE: The present study aimed at determining how 3-week intraperitoneal melatonin administration affected oxidative stress caused by experimental hyperthyroidism.

MATERIALS AND METHODS: The study was conducted on 30 male rats of Sprague-Dawley species. The experimental animals were divided to 3 groups (control, hyperthyroidism and hyperthyroidism+melatonin). The supplementation was continued for 3 weeks after which the animals were sacrificed and tissue malondyaldehyde (MDA) and glutathione (GSH) levels were determined.

RESULTS: MDA levels in kidney and testis tissues in hyperthyroidism group were higher than those in control and hyperthyroidism+melatonin administered groups (p<0.001) and levels in hyperthyroidism+melatonin administered group were higher than those in the control group (p<0.001). The highest GSH levels were obtained in hyperthyroidism+melatonin-administered group (p<0.001) and GSH levels in hyperthyroidism group were higher than those in the control group (p<0.001).

CONCLUSION: Results of the study demonstrate that hyperthyroidism induced by 3-week L-thyroxine administration increased oxidative stress in kidney and testis tissues and that although melatonin administration inhibited this stress to a certain extent, it could not bring the stress down to the level in controls....

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Comparative Study 2005; 26(6): 729-732 PubMed PMID: 16380686 Citation  Keywords:  Age Factors, Animals, Animals, Newborn, Longitudinal Studies, Male, Organ Size:drug effects, Rats, Rats, Sprague-Dawley, Selective Estrogen Receptor Modulators:pharmacology, Sexual Behavior, Animal:drug effects, Tamoxifen:pharmacology, Testis:cytology, Te.   

OBJECTIVE: In this study we examined the possibility that demasculinization produced by the neonatal administration of tamoxifen is accompanied by a decline in plasma levels of testosterone during adulthood.

METHODS: Wistar male rats received either a treatment with 12.5 microg/kg of tamoxifen during the first eight days of age or a treatment with 100 microg/kg of tamoxifen for five days. Each treatment had their respective control group. During adulthood their masculine sexual behavior was analyzed. At 8 months of age, males were killed by decapitation, trunk blood was collected and peripheral glands were dissected and weighed. Testosterone levels were measured by HPLC. Histological analysis of peripheral glands was performed.

RESULTS: Both neonatal tamoxifen treatments significantly decreased male sexual behavior when compared to control values. In addition, both treatments also showed a significant decrease in testicular weight when compared to control groups, as well as a decrease in seminal vesicle weight. In the microscopic analysis, a significant decrease in the diameter of the seminiferous tubules was observed, especially in the animals treated with 100 microg/kg of tamoxifen. However, no differences were observed between tamoxifen treated and control animals concerning plasma levels of testosterone.

CONCLUSION: The present results indicate that behavioral manifestations and changes in peripheral reproductive organs that accompanied demasculinization are not due to a deficit in testosterone secretion....

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Comparative Study 2005; 26(5): 468-472 PubMed PMID: 16264417 Citation  Keywords:  Animals, Cells, Cultured, Female, Galanin:administration & dosage, Injections, Intravenous, Injections, Intraventricular, Ovariectomy, Pituitary Gland:drug effects, Pituitary Hormones:blood, Rats, Rats, Inbred WKY,.   

OBJECTIVES: Galanin and its receptors are widely distributed within the central and peripheral nervous system, especially in hypothalamus including preoptic area, paraventricular nucleus (PVN), supraoptic nucleus (SON) and median eminence. Galanin plays an important role in the control of food intake, energy expenditure, reproduction, water balance and various neuroendocrine functions. Galanin may affect hormones release, but the exact mechanism of the peptide action remains unclear and possible direct effects of galanin on the pituitary are controversial. The aim of this study was to examine the effects of galanin on pituitary hormones release after the central and peripheral administration of the peptide.

MATERIAL AND METHODS: (i) Experiment I - Intracerebroventricular (icv) administration of galanin: Galanin at a concentration of 0.5 microg in 5microl vehicle (artificial cerebrospinal fluid) or equal volume of the vehicle was slowly (1microl/min) infused into the third ventricle with an automatic pump (CMA/100; Sweden) through an inner cannula inserted into the guide cannula. After the end of the infusion the rats were transferred to their home cages with free access to food and water. At 60 min after the infusion of galanin or vehicle, animals were decapitated and trunk blood was collected in plastic tubes containing 1000 IU aprotinin (inhibitor of protease) per each ml of blood. (ii) Experiment II - Intravenous (iv) injection of galanin: Galanin in a dose of 10 microg in 300 microl of saline or 300 microl of saline alone was injected into the tail vein. After the injection the animals were transferred to individual cages with free access to food and water. At 60 min after the injection of galanin or saline, animals were decapitated, and trunk blood was collected in plastic tubes containing 1000 IU of aprotinin (Trascolan). The blood samples were centrifuged (3000 rpm for 20 min at 4 degrees C). Serum samples were frozen until hormonal analyses were performed. Serum rLH, rFSH, rPRL, rGH, rTSH concentrations were measured with RIA methods.

RESULTS: Galanin administered icv increased significantly rPRL and rTSH levels (p<0.01, p<0.05, respectively). Plasma rPRL and rTSH concentrations were not changed after iv injection of galanin. Galanin injected centrally inhibited significantly rGH release (p<0.01), however, galanin given iv stimulated rGH (p<0.01). Serum rLH and rFSH concentrations were not changed after icv and iv injections of galanin.

CONCLUSION: Galanin may be involved in the modulating mechanism of pituitary hormones release....

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Journal Article 2005; 26(5): 511-514 PubMed PMID: 16264409 Citation  Keywords:  Aging:physiology, Animals, Animals, Newborn, Cell Count, Colon:pathology, Hyperplasia, Male, Neurosecretory Systems:pathology, Paraffin Embedding, Pineal Gland:physiology, Rats, Rats, Wistar,.   

OBJECTIVES: The diffuse neuroendocrine system (DNES) participates in the systemic homeostasis and may work as a unified system with integrated functions but anatomically disperse. However, the mechanisms that are involved in the integration of the distant parts of the DNES are poorly known. This study is aimed on the effects of a pinealectomy on the population of the neuroendocrine cells (NECs) in the colon of rats.

METHODS: A group of seven newborn rats and one of adult rats were submitted to a pinealectomy. The animals were sacrificed after 15 days and 90 days, respectively. The control groups of adult and newborn rats were subjected to a 'sham surgery' and then sacrificed after similar periods of time. Paraffin-included sections of the colon samples were stained by the Churukian-Schenk method in order to selectively stain the NECs. The NEC index was estimated by the expression: iNEC = NECs population per crypt/Total cell population of the crypt. The results were expressed as median and absolute range, and the statistical significance was demonstrated by the Mann-Whitney (U) test.

RESULTS: The morphometric analysis showed a significant increase in the number of colonic NECs of the adult rats subjected to a pinealectomy when compared to the controls. No statistical difference was observed between the iNECs of the newborn groups of rats.

CONCLUSION: This finding suggests the existence of regulatory mechanisms that integrate distant parts of the DNES, by adapting the population of the endocrine cells after the ablation of an important component of the system. Further studies on the mechanisms involved in the integration of the DNES may be facilitated by the simple experimental model that we propose....

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