Role of the pituitary in modulating hepatic monoamine oxidase activity.

Abstract

The activity of monoamine oxidase was measured in a liver mitochondrial fraction from gonadectomized and hypophysectomized rats. The effects of 17β-estradiol and testosterone propionate administration on hepatic monoamine oxidase (MAO) activity in these animals were also studied. The regulation of hepatic MAO was studied using ectopic pituitary transplants under the kidney capsule of hypophysectomized, gonadectomized rats. MAO activity is normally 50% higher in adult females than in males. Ovariectomy has no effect on adult female MAO activity, but castration of the adult male increases MAO activity to the intact female level. The administration of testosterone propionate to the male castrate restores the intact male MAO level. Enzyme activity was elevated in both adult male and female rats after hypophysectomy, but the sex difference in MAO activity was maintained in the absence of the pituitary. Gonadectomy had no effect on these elevated levels. Transplantation of an age-matched pituitary (of male or f...