Effect of ACTH, α-MSH, and β-Lipotropin on Calcium and Phosphorus Metabolism in the Rabbit

Abstract

Studies were undertaken to investigate the effects of synthetic 1-24 ACTH, bovine .alpha. melanocyte-stimulating hormone (.alpha.-MSH) and ovine beta lipotropin (.beta.-LPH) on plasma and phosphate in rabbits. Equimolar concentrations of these hormones were infused i.v. in intact and thyroidectomized animals. ACTH was similarly administered to adrenalectomized rabbits. ACTH, .alpha.-MSH and .beta.-LPH all lowered plasma Ca and raised plasma phosphate. These changes were not prevented by prior thyroidectomy. ACTH was equally effective in inducing hypocalcemia and hyperphosphatemia in the absence of the adrenal glands, while adrenalectomy alone raised plasma Ca. ACTH, .alpha.-MSH and .beta.-LPH affect phosphate and Ca metabolism. These hormones do not act by releasing calcitonin. ACTH exerts its hypocalcemic-hyperphosphatemic effect, at least in part, independently of its trophic action on the adrenal glands.