Ethanol-induced inhibition of testicular steroidogenesis in vitro: prevention by pyrazole.

Using isolated Leydig cells prepared from adult rat testes, the effects of ethanol on testicular steroido genesis were examined in vitro. Ethanol over a dosage range of 25 to 1000 mg 3⁄4 markedly inhibited gona dotropin-stimulated testosterone production in a dose-dependent fashion. As little as 25 mg 3⁄4 (ca. 6 mM) ethanol was effective in reducing testosterone synthesis by 50%. By using 0.5 mM 4-methylpyrazole (4-MP) to block the metabolism of ethanol, the inhibitory effects of ethanol on testosterone synthesis were prevented at each of the ethanol doses used. At concentrations ≥ I .0 mM, 4-MP, per se, inhibited testoster one production. These observations demonstrate that under acute in vitro conditions, the inhibitory effects of ethanol on testicular steroidogenesis are secondary to ethanol metabolism and 4-MP, at low doses shown not to inhibit steroidogenesis directly, prevents completely the ethanol induced inhibition of testos terone synthesis.