α-Melanocyte-Stimulating Hormone Stimulation of Aldosterone Secretion in Hypophysectomized Rats*

Publisher Website
Google Scholar
Abstract
Intact and hypophysectomized male rats on low and high Na diets were treated with s.c. infused ACTH and .alpha.MSH; the levels of aldosterone and corticosterone were determined in truncal blood. Plasma aldosterone levels were lower in hypophysectomized animals on the low Na diet than in intact animals on the low Na diet. .alpha.MSH (8 .mu.g/day) restored plasma levels of aldosterone to normal in hypophysectomized rats on the low Na diet. ACTH (6 .mu.g/day) did not cause significant changes in plasma levels of aldosterone in hypophysectomized animals. ACTH restored plasma corticosterone to normal in hypophysectomized rats. .alpha.MSH had no effect on corticosterone. .alpha.MSH did not increase plasma aldosterone levels in intact rats. Thus, .alpha.MSH may be important in the regulation of aldosterone secretion in the rat and zona glomerulosa responsiveness to .alpha.MSH in vivo is increased by hypophysectomy. The mechanisms of .alpha.MSH action on glomerulosa cells are different from those of ACTH.