Hormonal Dependence of Cholesterol Ester Hydrolase in the Corpus Luteum and Adrenal[*]

Abstract

Hypophysectomy reduced the specific activity of cholesterol esterase in luteal (-30%) and adrenal (-26%) tissue (p<.05) from gonadotrophin-treated immature rats. Replacement therapy with prolactin or ACTH maintained luteal and adrenal cholesterol esterase levels respectively, at levels similar to animals with an intact pituitary but, the alternate hormone had no trophic effect. Ovarian (-63%) and adrenal (-50%) weight was severely depressed (p<.005) after hypophysectomy but prolactin and ACTH replacement respectively, prevented this atrophy. Thus, the trophic effect of prolactin or ACTH on total esterase activity was magnified. The specific activity of cholesterol esterase was about 18 times greater ( p<.001) in luteal and adrenal tissue than in liver and may be correlated to the steroidogenic potential of the former tissues. Cholesteryl palmitate was hydrolyzed at 50% of the rate (p<.01) of cholesteryl oleate and linoleate by luteal cholesterol esterase and may indicate a specificity for ester hydrolysis. These data indicate that cholesterol esterase activity in both the corpus luteum and the adrenal is under direct control of specific pituitary hormones and regulation of this enzyme is directly associated with function of these tissues.

Key words

Cholesterol Esterase - Corpus Luteum - Adrenal Gland - Hypophysectomy - Prolactin - ACTH

1 Supported by NIH Grants 69-2214, HD-03736 and The Ford Foundation.

1 Supported by NIH Grants 69-2214, HD-03736 and The Ford Foundation.