FURTHER STUDIES ON THE SEX DIFFERENCE IN 3²-HYDROXYSTEROID DEHYDROGENASE ACTIVITY OF RAT LIVERS1

Abstract

Conditions have been established for quantitative assay of rat liver 3²-hydroxysteroid dehydrogenase activity in order to investigate further the difference previously demonstrated (1) in the ratio obtained of epiandrosterone/androsterone, depending on the sex of the animal from which the liver was taken. Livers of male rats have been shown to demonstrate more activity than livers of female rats, whether assays were made using crude homogenates, fractions obtained by differential centrifugation, or acetone-dried preparations. Data were also obtained indicating that rat liver contains separable 3²-hydroxysteroid dehydrogenase activities associated with particulate and soluble material, and the sex difference lies in a greater activity of the 3²-hydroxystcroid dehydrogenase associated with the particulate matter. The activity of the enzj’me associated with the particulate matter can be increased in livers of female rats by administration of testosterone propionate.