Adrenal glomerulosa mitotic stimulation by posterior pituitary hormones

Injection of posterior pituitary powder induces an intense mitotic stimulation in the zona glomerulosa of the adrenal gland of young rats. This effect is much more pronounced in females than in males. It is maximal at two days treatment. Longer periods result in a hypertrophied zona glomerulosa and lower mitotic activity. A search for the hormone responsible for the stimulation shows that vasopressin, and to a lesser extent oxytocin, are mitogenic. ACTH, alpha-MSH, beta-MSH and the pineal hormones have no effect. Renin (but not angiotensin) induces a significant stimulation. It is concluded that vasopressin exerts a potent influence on the glomerulosa. This is in contrast with the prevalent view that the glomerulosa is little affected by the hypophysis.