Vitamin E administration does not ameliorate tramadol-associated impairment of testicular function in Wistar rats.

Tramadol is widely abused in Nigeria and has been reported to cause fertility decline via testicular oxidative stress. This study investigated the effect of vitamin E, an antioxidant on some reproductive parameters in male Wistar rats administered tramadol. Twenty male Wistar rats (180-200 g) were randomly assigned into four groups (n = 5) thus: Control (0.2 ml vehicle: olive oil), tramadol-treated (20 mg/kg of tramadol), vitamin E-treated (100 mg/kg of vitamin E) and tramadol + vitamin E-treated (received tramadol and vitamin E) groups. Drugs were administered orally and daily for 28 days. Sperm count, Johnsen's score, germinal epithelial height and serum testosterone, follicle-stimulating hormone (FSH) and luteinising hormone (LH) concentrations were significantly (p < .05) decreased in tramadol-treated and tramadol + vitamin E compared with control and vitamin E-treated groups. Sperm motility, morphology, viability, seminiferous tubular diameter, Leydig cell count, Sertoli cell count and malondialdehyde, superoxide dismutase, glutathione peroxidase and catalase concentrations were not significantly different among the groups. Histology of testis and epididymis in all groups showed no toxicity but decreased sperm population in tramadol-treated and tramadol + vitamin E-treated groups. Tramadol did not cause testicular oxidative stress but impaired testicular function by suppressing testosterone, FSH and LH secretion. Vitamin E administration could not attenuate this impairment in testicular function.