Antagonism of alcohol-induced suppression of rat testosterone secretion by an inhibitor of nitric oxide synthase.

To examine whether nitric oxide (NO) mediates the suppression of testosterone secretion by alcohol (ethanol), adult male rats were pretreated with a NO synthase inhibitor, NG-nitro-L-arginine methyl ester (NAME), then treated with alcohol. Serum and testicular interstitial fluid (TIF) testosterone concentrations, serum luteinizing hormone (LH) concentrations, blood alcohol concentrations (BAC), and TIF volumes were measured 2 hr after alcohol treatment at a time of peak effects of alcohol and NAME on testosterone secretion. Pretreatment with NAME (30 or 100 mg/kg, subcutaneous) 30 min before alcohol treatment (0.5-3 g/kg, intraperitoneal) completely blocked the alcohol-induced suppression of testosterone secretion into the general circulation and into TIF without significantly altering blood alcohol concentrations (BAC) or TIF volumes. These results support the hypotheses that NO synthase inhibitors can antagonize alcohol-induced suppression of testicular steroidogenesis, that alcohol interacts with arginine-NO synthase systems that regulate testicular steroidogenesis, and that NO is involved in mediating alcohol's testicular and reproductive effects.