Effects of Age, Adrenocorticotropin, and Dexamethasone on a Male-Specific Cytochrome P450 Localized in the Inner Zone of the Guinea Pig Adrenal*

Abstract

Guinea pig adrenal microsomes have a capacity for xenobiotic metabolism which is localized to the inner zone, greater in adult males then females, greater in older than in younger males, and suppressed by ACTH. In this paper we show that a cytochrome P450 distinct from P450(21) and P450(17) alpha, which is localized to the inner zone, is male specific, increases with age, and is suppressed by ACTH. This is the first report of a sex-dependent cytochrome P450 in the adrenal. It is immunochemically related to the two members of the P450I family, P450 c and d, neither of which has been reported to be hormonally regulated. The correlation of this cytochrome P450 with the ability of the microsomes to metabolize ethylmorphine suggests that it accounts for this capacity. Whether metabolism of foreign compounds and/or male-specific steroid hydroxylation are its functions in vivo remains to be determined.