Sex-related differences in biotransformation of aniline hydroxylase in Sprague-Dawley rats.

A significant difference was found in the rate of aromatic hydroxylation of the type II substrate, aniline, between male and female rats of the Sprague-Dawley strain. In addition, microsomal cytochrome P-450 levels were significantly lower in female rats and aniline-induced spectral binding was significantly greater in microsomes isolated from male rats. Castration caused a significant reduction in aniline metabolism in male rats and testosterone treatment elevated this metabolism toward control level. Treatment of male rats with 17beta-estradiol significantly reduced aniline hydroxylase activity and female rats receiving testosterone for 1 month exhibited significantly increased rates of aniline metabolism over control females. Enzyme activities measured in immature male and in mature and immature female rats were all significantly lower than in mature male rats. These results suggest that the metabolism of aniline in Sprague-Dawley derived rats is controlled by androgen and, thus, is sex-dependent.