Treatment effect of l-Norvaline on the sexual performance of male rats with streptozotocin induced diabetes

Sexual impairment is an established risk factor in diabetes mellitus affecting about 75% of male diabetic population. In diabetes overexpression of arginase leads to decreased production of NO and diminished erectile response. Inhibition of arginase enzyme can lead to improvement in diabetes induced sexual dysfunction. In the present study diabetes mellitus was induced in adult male rats by intraperitoneal injection of single dose of streptozotocin (65 mg/kg) in 0.1 M Citrate buffer pH 4.5 and after 72 h fasting serum glucose level was checked by glucose oxidase–peroxidase method and those animals showing FSG above 250 mg/dl were selected. Diabetic animals were divided into four groups comprising six animals in each. l-Norvaline, potent arginase inhibitor was administered at a dose of 10 mg/kg ip to the different groups of diabetic animals for a period of 30 days. Sildenafil at a dose of 5 mg/kg orally was used as a standard drug. Mating behavior tests were performed at 0, 15th and 30th days. After 30 days, various biochemical and hormonal parameters (nitrates, LDH, urea, testosterone), testicular parameters (total protein, nitrates, LDH, total cholesterol, LDL, triglycerides, VLDL, HDL) were evaluated to find out the effect of l-Norvaline in sexual impairment. Sperm analysis was also carried out for the treated rats. l-Norvaline showed significant improvement in serum nitrates, urea, LDH, testosterone and testicular protein level as compared with diabetic group. It also improved sperm motility, count and viability in diabetic rats. Sildenafil showed no improvement in above parameters except restoration in serum nitrates level.