Abstract

The activities of the 3 enzymes involved in the biosynthesis of corticosterone from Δ5-3β-hydroxysteroids in the rat adrenal have been measured in experimental adrenal cortical hyperplasia produced by an inhibitor of 3β-dehydrogenation and by an inhibitor of 11β-hydroxylation. Cyanotrimethylandrostenolone reduced both the specific activity per unit adrenal protein, and the total activity of the glands of 3β-ol dehydrogenase. These changes were accompanied by significant rises in the total activities of 11- and 21-hydroxylase, although their specific activities were unaffected. Nineteen hr after a second dose, metyrapone produced a rise in the total activity of all 3 enzymes, determined by the adrenal homogenate technique, without an observable effect on their specific activities. However, it was possible to demonstrate a deficient conversion of 11-desoxycorticosterone to corticosterone by quartered adrenals of animals given 30 mg/kg metyrapone, and virtually no biosynthesis of corticosterone from either 11-desoxy corticosterone or 11β-hydroxy progesterone by quartered adrenals of animals given 300 mg/kg metyrapone. These experiments suggest that the abnormally large amounts of certain steroid hormones produced by patients with genetic deficiencies of single steroidogenic enzymes result from an increase in the weight of adrenal tissue rather than from any increase in specific activity of any of the enzymes involved in their biosynthesis.

This content is only available as a PDF.
You do not currently have access to this article.