Alcohol affects rat testicular interstitial fluid volume and testicular secretion of testosterone and beta-endorphin.

The effects of alcohol on testicular interstitial fluid (TIF) volume and the secretion of testosterone and beta-endorphin (beta E) into this important testicular compartment were assessed in the rat. Alcohol time- and dose-response curves were constructed for changes in TIF volume and the bioactive concentrations of testosterone and immunoreactive beta E (i-beta E). Alcohol (3 g/kg) decreased TIF volumes and increased TIF i-beta E secretion 0.5 to 6 hr after injection and decreased TIF testosterone 1 to 6 hr after injection. These effects were dose-related at 2 hr postinjection. The possible role of alcohol-induced reductions in serum luteinizing hormone and testosterone levels in mediating the effects of alcohol on TIF volume was also examined. We found that pretreating rats with human chorionic gonadotropin, which reversed alcohol-induced suppression in levels of serum gonadotropins and testosterone, failed to reverse the effects of alcohol on TIF volume and the secretion of testosterone and i-beta E. These results indicate that alcohol decreases TIF volume, inhibits TIF testosterone secretion and stimulates TIF i-beta E secretion and, furthermore, suggest that these effects are not indirectly mediated by decreased levels of gonadotropins or testosterone, but by direct effects of alcohol on gonadal function. The strong inverse correlation between TIF i-beta E and testosterone secretion after alcohol administration and previous evidence that testicular opioids inhibit the biosynthesis of testosterone suggest that alcohol may act through testicular beta E to suppress the synthesis and release of testosterone in the testes.