Effect of pharmacological doses of niacin on testicular structure and function in normal and diabetic rats

Male diabetic patients may experience adverse changes in testicular functions or structure. Niacin has antidyslipidemic properties in diabetic patients. We aimed to clarify the effect of pharmacological doses of niacin on testicular structure and function of normal and diabetic rats. Sixty adult male rats were treated as follows. Healthy control (HC); diabetic control (DC); NL and NH groups: normal rats that received niacin at 800 and 4,000 mg/kg of diet; DL and DH groups: diabetic rats that received niacin at 800 and 4,000 mg/kg diet for 50 days. In normal rats, obvious increase in serum testosterone especially in NL group associated with improved antioxidant status of testicular tissue was observed. In diabetic rats, niacin resulted in higher testicular weight/body weight and improved some histological parameters without affecting blood glucose, testosterone and sperm count. Testicular MDA content decreased. In conclusion, niacin especially at 800 mg/kg diet improves serum testosterone levels and antioxidant status of testes in normal rats. In diabetic rats, despite positive changes in histological features and antioxidant status of testes reproductive outcome including sperm count or testosterone levels were not improved. This study set the scene for further investigations on the effect of niacin on male reproductive system.