Control of epinephrine synthesis in the adrenal medulla by the adrenal cortex: hormonal specificity and dose-response characteristics.

Abstract

Hypophysectomy in the rat is followed by a decline in the activity of phenylethanolamine- N-methyl transferase (PNMT), the adrenal medullary enzyme which synthesizes epinephrine. This decline, as well as the consequent fall in adrenal epinephrine content, can be corrected by treatment with ACTH. The PNMT activity of hypophysectomized rats is also elevated by glucocorticoids, but is unaffected by FSH, LH, prolactin, TSH, growth hormone, estrogen, or testosterone. The doses of ACTH required to restore epinephrine biosynthesis are of the same order of magnitude as those needed to maintain adrenal weight. However, the doses of exogenous glucocorticoid needed for this effect are at least 100-fold greater than the usual steroid “replacement doses.” A dose of ACTH which is equally effective with a given amount of hydrocortisone in depressing splenic weight is much more effective in restoring PNMT activity. Since the action of ACTH on the epinephrineforming enzyme is known to be mediated by its stimulation of glu...