Effect of Chronic Ethanol Feeding on Testicular Content of Enzymes Required for Testosteronogenesis

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Abstract
Ethanol is a known inducer of microsomal enzymes and a testicular toxin. To evaluate the effect of chronic ethanol ingestion on the microsomal enzymes required for testosterone synthesis, the activity of 4 testicular enzymes (3.beta.-hydroxysteroid dehydrogenase/isomerase, 17.alpha.-hydroxylase, 17,20-lyase and 17.beta.-hydroxysteroid dehydrogenase) was examined in 14 pairs of adult chronic alcohol-fed rats and their age-matched isocaloric controls. Ethanol feeding enhanced the activity of 17,20-lyase when expressed as activity/mg protein (P < 0.05) or activity/g testis (P < 0.025). The activity of 17.alpha.-hydroxylase was increased in testes of the alcohol-fed animals (P < 0.025) compared to controls. Chronic ethanol feeding reduced total activity of 3.beta.-hydroxysteroid dehydrogenase/isomerase in alcohol-fed animals (P < 0.05) compared to controls. No effect of ethanol feeding was seen on activity of 17.beta.-hydroxysteroid dehydrogenase. Chronic ethanol ingestion increased testicular 17.alpha.-hydroxylase and 17,20-lyase and reduced 3.beta.-hydroxysteroid dehydrogenase/isomerase in rat testicular microsomes. The major effect of chronic ethanol ingestion on the enzymes required for testosteronogenesis was the reduction of 3.beta.-hydroxysteroid dehydrogenase/isomerase activity, the rate limiting step in sex steroid production from pregnenolone.