Vitamin D supplementation alleviates diabetic complications by increasing the amount of irisin in testicular tissues and blood of rats with experimental diabetes.

OBJECTIVE: Diabetes is an important endocrinological disease that has an increasing incidence in the world and affects all biological tissues including testicles. Therefore, this study aimed to reveal the histological and biochemical effects of vitamin D on irisin, apoptosis, total antioxidant status (TAS), and total oxidant status (TOS) in testicular tissues of rats with experimental diabetes. MATERIALS AND METHODS: 41 male Wistar rats, 8-10 weeks old, weighing between 200-220 g, were included in the study as the following groups: control group (n=7; no treatment), sham group [only sodium citrate buffer (SCB)] [n=7; single dose 0.1 Molar (M) SCB given intraperitoneally (i.p)], vitamin D group (n=7; 50 IU/day given orally), diabetes group [n=10; single dose 50 mg/kg Streptozotocin (STZ) dissolved in 0.1 M SCB and given i.p (tail vein blood glucose level above 250 mg/dl after 72 hours)] and diabetes+vitamin D group [n=10, single dose 50 mg/kg STZ, dissolved in 0.1 M SCB and given i.p (tail vein blood glucose level above 250 mg/dl after 72 hours) and when diabetes occurs, oral vitamin D administration of 50 IU/day)]. At the end of the 8 weeks experiment, blood was drawn from the tail vein of all rats, they were sacrificed and testicular tissues were taken. While the amount of irisin in the blood and testicular tissue supernatants was analyzed with the Enzyme-Linked Immunosorbent Assay (ELISA) method, TAS and TOS measurements were analyzed with the REL method, testicular tissues were analyzed histopathologically, immunohistochemically, and with the TUNEL method. RESULTS: When the diabetes group was compared with the control and sham groups, it was reported that the amounts of blood and tissue supernatant irisin and TAS significantly decreased and the TOS was significantly increased; a statistically significant increase in irisin and TAS of blood and tissue supernatants and a significant decrease in TOS were detected when diabetes+vitamin D and diabetes groups were compared among themselves. Similar results were obtained in the immunohistochemical studies. Tissue expressions of irisin decreased in the diabetes group compared to the control and sham groups, while the application of vitamin D increased the tissue expressions of irisin. Additionally, when the numbers of apoptotic cells were compared, it was reported that apoptotic cells in the diabetes group increased significantly compared to the control and sham groups, and vitamin D administration significantly decreased the number of apoptotic cells. CONCLUSIONS: Taken together, vitamin D administration to diabetic rats decreased the number of apoptotic cells and increased the amount of irisin. Vitamin D had an effective role in maintaining the physiological integrity of rat testicular tissues, so vitamin D may be a potent agent to be used in the treatment of diabetes in the future.

Existence of serotonin and neuropeptides-immunoreactive endocrine cells in the small and large intestines of the mole-rats (Spalax leucodon).

The present study was conducted to clarify the regional distribution and relative frequency of endocrine cells secreting serotonin, substance P (SP), cholecystokinin-8 (CCK-8), vasoactive intestinal polypeptide (VIP) and neurotensin in the small and large intestine of the mole-rats (Spalax leucodon), by specific immunohistochemical methods. In the small and large intestine of mole-rats (Spalax leucodon), serotonin, SP and VIP were identified with various frequencies, but CCK-8 and neurotensin were not observed. Most of the IR cells in the small and large intestine were located in the intestinal crypt and epithelium however, they were more frequency in the intestinal crypt. Serotonin-IR cells were detected throughout the whole intestinal tract, predominantly in the duodenum and colon. SP-IR cells were demonstrated throughout the whole intestinal tract except for the ileum and rectum with highest frequencies in the cecum. VIP-IR cells were found in all parts of the small intestine except for the large intestine. In conclusion, the general distribution patterns and relative frequency of intestinal endocrine cells of the mole-rats (Spalax leucodon) was similar to those of some rodent species. However, some species-dependent unique distributions and frequencies characteristics of endocrine cells were also observed in the present study.