STUDIES ON TESTOSTERONE HYDROXYLATION AND PENTOBARBITAL OXIDATION BY RAT LIVER MICROSOMES - SELECTIVE EFFECTS OF AGE SEX CASTRATION AND TESTOSTERONE PROPIONATE TREATMENT

The effect of sex, age, castration and testosterone propionate treatment on the metabolism of testosterone and pentobarbital by rat liver microsomes have been studied. The adult male rat metabolized testosterone primarily to a polar ultraviolet absorbing fraction composed of hydroxylated products. The rates of 6β-, 7α- and 16α-hydroxylation of testosterone by liver microsomes of male rats varied independently as a function of age, castration and testosterone propionate treatment. Changes in the rate of pentobarbital oxidation most closely paralleled changes in the rate of the 16α-hydroxylation reaction. These data suggest that a single component in liver microsomes cannot alone determine the specificity in the 6β-, 7α- and 16α-hydroxylation of testosterone. In the female rat, little metabolism of testosterone to polar ultraviolet absorbing products occurred and castration and/or testosterone propionate treatment had little or no effect on this pathway. © 1968.