Hypothalamo-neurohypophysial involvement in the corticotrophic action of acetylcholine.

Acetylcholine produced a fall of blood eosinophils and adrenal ascorbic acid in normal rats; these effects did not occur in hypophysectomized animals or in hypophysectomized animals bearing a pituitary homotransplant in the anterior chamber of the eye. Acetylcholine had a striking and long-lasting antidiuretic effect in normal rats, which was abolished by hypophysectomy. In normal dogs, intravenous injections of acetylcholine raised the concentration of posterior pituitary antidiuretic hormone in the cerebrospinal fluid. These results are discussed in connexion with the hypothesis that posterior pituitary antidiuretic hormone may be the neurohumoral substance involved in the hypothalamic control of the anterior pituitary.