Effects of ethanol and enzyme-inducing agents on the monooxygenation of testosterone and xenobiotics in rat liver microsomes.

The simultaneous production of multiple testosterone oxidation products in hepatic microsomal incubations was monitored after injection of a post-trichloroacetic acid supernatant directly onto a reverse-phase high-performance liquid chromatography column. Twelve testosterone-derived metabolite peaks were detected on the chromatogram and the relative proportions of these products were changed distinctively after pretreatment of rats with phenobarbitone, beta-naphthoflavone and pregnenolone 16 alpha-carbonitrile. Chronic ingestion of ethanol (35% of total energy in a nutritionally adequate liquid diet) modified oxidative testosterone metabolism differently from the other enzyme inducers and reduced plasma testosterone levels relative to values in animals pair-fed the control liquid diet. Modifications to the metabolism of xenobiotic substrates after ethanol treatment confirmed that ethanol had changed the types and amounts of cytochrome P-450 in microsomal preparations. Differences in testosterone metabolite profiles between control and ethanol-treated male and female rats suggested that these results were not a consequence of ethanol-induced decreases in circulating levels of testosterone influencing the constitutive cytochrome P-450 isoenzymes. These experiments confirm that analysis of testosterone metabolites by high-performance liquid chromatography is a useful approach for detecting and discriminating between the metabolic capacity of cytochrome P-450 in microsomal preparations. In addition, increases in the rates of some testosterone hydroxylations after ethanol ingestion, in conjunction with known effects of alcohol on testosterone homeostasis, may contribute to the hypogonadism seen in male chronic alcoholics.