Kynurenine metabolism in rats: Some hormonal factors affecting enzyme activities

Abstract

The effects of certain long-term hormonal treatments of male and female rats on the activities of several enzymes involved in kynurenine synthesis and degradation were determined to further rationalize previously observed sex differences. Treatment causing elevated tryptophan oxygenase activities (corticosteroid administration) did not consistently result in changes of kynurenine hydrolase and kynurenine aminotransferase activities like those seen with estrogen treatments. Differences in the latter enzyme activities caused by sex differences or treatment-induced changes in estrogen-androgen status were not consistently associated with altered oxygenase activities. Castration of male rats or treatment of female rats with androgen altered the kidney kynurenine aminotransferase activities toward those of the opposite sex, consistent with the view that differences in androgen-estrogen status during post-natal development satisfactorily account for the sex differences in enzyme activity.