Hepatic hydroxylation of 3beta-hydroxy-5-androsten-17-one in orchiectomized or adrenalectomized rats exposed to a reversed light cycle, constant light, or constant darkness.

The oxidative metabolism of 3beta-hydroxy-5-androsten-17-one (DHA)2 by liver microsomes in vitro was studied in sham-operated, castrated, or adrenalectomized rats maintained for 21 days in a normal light cycle, a reverse light cycle, constant light, or constant darkness and killed either at 0600 or 1800 h. Statistical analysis of the data (3-way analysis of variance) indicated the following significant effects: 1) exposure to a reverse light cycle resulted in lower body weights and increased rates of formaation of 7alpha-OH-DHA and 7-oxo-DHA; 2) despite an increase in microsomal protein content, livers from rats in constant light had the lowest rates of formation of all DHA products; 3) rats kept in constant darkness exhibited the highest rates of DHA metabolism; 4) castration decreased the microsomal protein content and the rates of formation of 16alpha-OH-DHA, 7alpha-OH-DHA, and 7-oxo-DHA; 5) adrenalectomized rats exhibited high rates of 7alpha-OH-DHA formation although microsomal protein and liver and body weights decreased; and 6) the formation of 7-oxygenated products of DHA was greater in the rats killed at 1800 than at 0600 h. We conclude that the type of illumination is quantitatively more important in determining the magnitude of DHA metabolism by the adult male rat liver than either the adrenals or the testes.