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

Abstract

The effect of gonadectomy and gonadal hormone replacement on the activity of sterol ester hydrolase, steroid 5a-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 x 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 5a-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 5a-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 5a-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.

Steroid 5α-reductase type 1 immunolocalized in the adrenal gland of normal, gonadectomized, and sex hormone-supplemented rats

“…The immunoreactive cells were localized in the zonae fasciculata and reticularis in the rat adrenal cortex, and the immunoreactivity was increased after gonadectomy and decreased by testosterone or estradiol supplement. Our findings are compatible with previous biochemical data showing that sex hormones regulate 5α-reductase activity in the adrenal gland (Kitay et al 1970;Colby and Kitay 1972;Trzeciak and Malendowicz 1981;Nussdorfer 1986;Ando et al 1989). The amount of adrenal 5α-reductase mRNA was shown to be negatively regulated by sex hormones in both sexes (Lephart et al 1991).…”

“…Although corticosterone has a low affinity for 5αreductase (Andersson and Russell 1990), the content of corticosterone in the adrenal cortex is so great that this steroid is reduced in large quantities to 5α-dihydrocorticosterone, a biologically inactive form. Gonadectomy increases the output of 5α-reduced metabolites of corticosterone, and, concomitantly, decreases the output of corticosterone from the adrenal gland of both sexes (Kitay et al 1970;Colby and Kitay 1972;Trzeciak and Malendowicz 1981). The present finding that 5α-reductase immunoreactivity in the adrenal cortex increased markedly after gonadectomy fully explains these biochemical findings.…”

“…In rats of both sexes, gonadectomy reduces the output of corticosterone, a major glucocorticoid in rodents, from the adrenal gland (Kitay 1963;Colby and Kitay 1972;Trzeciak and Malendowicz 1981;Nussdorfer 1986). It is suggested that this gonadectomy-induced repression of adre-nal corticosterone secretion is caused by steroid 5α-reductase (Nussdorfer 1986).…”

Adrenal Neutral Cholesteryl Ester Hydrolase: Identification, Subcellular Distribution, and Sex Differences

“…Previous workers have documented that neutral CEH activity in the adrenal was higher in male rats compared with females (26). Our findings show that there are no differences in the expression of HSL protein in the adrenals of male and female rats, nor are there any differences in the subcellular distribution of HSL protein in the adrenals of male and female rats; HSL immunoreactive protein is enriched to a similar degree within the microsomal fraction of both male and female rats.…”

“…Male rats have greater than 2-fold the adrenal CEH specific activity of females (26), although steroid output is lower in male rats (14). Following gonadectomy, the levels of adrenal CEH in males is unaltered, whereas in females it tends to increase (26).…”