Background: Tamsulosin is an inhibitory factor of alpha-adrenergic receptors that is used for relieving of the clinical symptoms and management of acute urinary retention. Objective: The aim of this study was to evaluate the effects of tamsulosin on the endocrine axis and testicular tissue in adult male rats. Materials and Methods: In this experimental study, 30 adult male Wistar rats (weighing 250-300 gr) were divided into three groups: 1) control (received distilled water), 2) experimental 1 (received 0.2 mg/kg/day tamsulosin) and 3) experimental 2 (received 0.4 mg/kg/day tamsulosin) through oral gavage for 28 days. Serum hormones level and testicular histopathology were evaluated at the end of the experiment. Results: In this study, the testicular weight decreased significantly in the experimental groups compared to the control group. A significant decrease was seen in testicular weight (p = 0.004) and the number of Leydig cells in tamsulosin-treated groups (p = 0.012). Tamsulosin improved the hormone profile in experimental groups. Also, higher dose of tamsulosin significantly changed the number of Leydig, spermatogonia cells, the thickness of germinal layer, and the diameter of the seminiferous tubules. Conclusion: Results showed that using tamsulosin, possibly reduces the testosterone concentration through adrenergic axis system and in turn has destructive effects on proliferative activity of germ cells. Key words: Tamsulosin, Seminiferous tubules, Histopathology, Rat, Testis.

Background: Formaldehyde (F) is a chemical component that has an extensive usage on fixation of tissues and produces different types of reactive oxygen species (ROS) in our body. Studies have shown that long exposure to F damages the eyes, nose and throat; in addition it has adverse effects on body organs such as the urinary system. Vitamins can reduce free ROS. Objectives: The aim of this study was evaluating the protective effect of vitamin E on the kidney damaged by formaldehyde. Materials and Methods: Male adult wistar rats were divided into three groups. Group A (control): rats received vehicle (normal saline) for two weeks. Group E1 (formaldehyde): rats received formaldehyde (10 mg/kg) for two weeks. Group E2 (formaldehyde + vitamin E): rats received formaldehyde (10 mg/kg) and vitamin E (30 mg/kg) for two weeks. After two weeks, all rats were killed, and the kidneys were dissected and processed for routine histological staining. Results: Comparison of the control and formaldehyde groups with the vitamin E group revealed that there were significant differences in lumen size and nuclear color of proximal tubules in rats treated by vitamin E (P < 0.05). Cell degeneration, lumen size, number and size of nucleus of distal tubules were statistically different among the three groups. In the vitamin E treated group observed histological changes were improved compared to the formaldehyde group. Conclusions: According to the results of this study, vitamin E probably improves the harmful effects of formaldehyde on rat kidney tissue.