Increase in adrenal monoamine oxidase activity in hypophysectomized rats after ACTH

Abstract

Adrenal corticotropic hormone (ACTH) treatment of hypophysectomized rats caused no changes in adrenal catecholamine content but caused a significant increase in the activity of adrenal monoamine oxidase, catechol- O-methyl transferase and other medullary enzymes. Dexamethasone treatment of such animals, on the other hand, caused an increase in adrenal catecholamine content and in adrenal phenylethanol-N-methyl transferase activity only; the activity of adrenal tyrosine hydroxylase, monoamine oxidase and catechol- O-methyl transferase remained reduced after dexamethasone. It appears that enhanced activity of monoamine oxidase and probably catechol- O-methyl transferase in the adrenal gland is responsible for the failure of adrenal catecholamine to rise after ACTH treatment in hypophysectomized rats.