Sex Difference in Adrenocortical Structure and Function. VII. Adrenal Sterol Ester Hydrolase Activity in the Rat and its Dependence on Gonadal Hormones

Summary

The effect of gonadectomy and gonadal hormone replacement on the activity of sterol ester hydrolase, steroid 5α-reductase and corticosterone output was studied in the adrenals of rats of both sexes.

It was found that the specific activity of sterol ester hydrolase in 105,000 × g supernatant of the adrenal homogenates was higher in male than in female rats. On the contrary, corticosterone production by full adrenal homogenates, and adrenal steroid 5α-reductase activity was lower in male than in female rats.

Eight weeks after orchiectomy no change in the activity of sterol ester hydrolase was found in the adrenal cortex, and testosterone replacement caused no appreciable differences in the enzymic activity as compared with the intact and orchiectomized animals. Ovariectomy resulted in an increase in the activity of sterol ester hydrolase whereas estradiol replacement caused a decrease in the enzymic activity to the level observed in the control group.

In gonadectomized animals these changes accompanied an increase of steroid 5α-reductase activity in the adrenal glands, and after removal of the gonads no changes were found in corticosterone production by adrenal homogenates. Upon testosterone or estradiol replacement a substantial decrease in adrenal steroid 5α-reductase activity was noted.

The results showed a marked sex difference in adrenal sterol ester hydrolase activity and indicate diverse effects of both testosterone and estradiol on various steps of steroidogenesis in rat adrenals.

Key-Words:

Rat Adrenal Sterol Ester Hydrolase - Sex Differences - Gonadectomy - Gonadal Hormone Replacement