Hypothalamo-pituitary regulation of liver function

Sex differences exist in the metabolism of histidine, drugs and steroids by the liver. These differences are controlled, at least in the rat, by the hypothalamus-pituitary axis. Histidase is controlled by growth hormone, giving an increase in the male to the female level. Drug and steroid metabolism are controlled directly from the pituitary in the female rat by means of an unidentified hormone designated 'feminizing factor'. In the male rat, androgens derived from the testes and adrenals are involved in the regulation of liver function, probably by a feedback action on the pituitary secretion of feminizing factor. The thyroid glands are involved in the control of liver function in both males and females. Regulation of lactogenic receptors in rat liver is very similar to that of drug and steroid metabolism. The secretion of feminizing factor is regulated by the hypothalamus and probably involves higher centres, notably the amygdala.