Two months sodium nitrate supplementation alleviates testicular injury in streptozotocin-induced diabetic male rats

What is the central question of this study?Can low-dose inorganic nitrate supplementation prevent testicular structural and functional alterations in streptozotocin-induced type 1 diabetic male rats? What is the main finding and it's important?Treatment with a low dose of inorganic nitrate for 2 months had protective effects on the male reproductive system in diabetic rats including improved body weight loss, sperm and testis parameters, spermatogenesis index and testicular histology as well as increased serum testosterone levels. These favourable effects may be associated with increased serum insulin and decreased serum glucose, and with modulation of apoptosis in testis. Inorganic nitrate supplementation is a possible therapeutic agent in diabetes. The aim of this study was to evaluate the effect of nitrate on the reproductive system in streptozotocin-induced diabetic male rats. Fifty male Wistar rats were allocated randomly to five groups: control (C), control plus nitrate (CN), diabetic (D), diabetic plus insulin (DI) and diabetic plus nitrate (DN). Sodium nitrate was administered for 2 months in the drinking water (100 mg l(-1)) of the CN and DN groups. Insulin was injected at 2-4 U daily in the DI group. Serum glucose level and body weight were measured at the beginning of the study and at regular intervals. At the end of the study, serum levels of glucose, insulin, nitrogen oxides (NOx), luteinizing hormone (LH), follicle-stimulating hormone (FSH) and testosterone were assessed as well as sperm parameters, testis morphometry and histology, and testicular miR-34b and p53 mRNA expression. Nitrate treatment in diabetic rats significantly improved sperm parameters, epididymal weight, spermatogenesis and testicular histology as well as decreasing serum glucose and testicular p53 gene and miR-34b expression, although it had no effect on serum LH and FSH levels. In diabetic rats, serum insulin and NOx, body weight, testicular and epididymal weight, sperm count and motility, testis morphology, spermatogenesis indices, Johnsen's score, and testosterone were significantly lower than in controls. Nitrate administration increased serum insulin, NOx and testosterone levels in the DN group. Consuming water supplemented with sodium nitrate could improve diabetes-induced testicular functional and structural disorders; these favourable effects may be related to increased serum insulin and decreased serum glucose, as well as modulation of apoptosis in testis.