Chronic ethanol feeding impairs human chorionic gonadotropin-stimulated testicular testosterone responses of dogs.

To investigate the effects of ethanol on gonadal function, 24 male dogs were divided into four groups: the control group received no ethanol and the other three groups were fed varying amounts of ethanol for 30 days. Plasma concentrations of testosterone and luteinizing hormone (LH) were measured by radioimmunoassay after 30 days of ethanol or control feeding. At the conclusion of the experimental period the testes of each dog were examined for unstimulated and human chorionic gonadotropin (hCG)-stimulated testosterone production by means of an in vivo perfusion method. None of the dogs lost weight or had abnormal liver histology as a result of ethanol feeding. Control dogs and dogs fed ethanol (0.64 g/kg of body weight) showed no changes in gonadal function. Dogs fed ethanol (1.28 g/kg and 1.92 g/kg of body weight) had no decreases in peripheral concentrations of testosterone or LH, but hCG-stimulated testicular testosterone production was significantly impaired in both groups (P less than 0.005 and P less than 0.025, respectively). In addition, the dogs receiving ethanol at 1.92 g/kg of body weight had significantly (P less than 0.05) decreased unstimulated testicular testosterone production. It is concluded that a) daily ingestion of small amounts of ethanol does not cause obvious changes in gonadal function, b) peripheral concentrations of testosterone and LH may not accurately reflect early ethanol-induced gonadal dysfunction, c) hCG-stimulated testicular testosterone production is impaired when daily ethanol consumption is 1.28 g/kg of body weight or greater for 30 days, and d) these changes occur in the absence of weight loss or obvious liver pathology.