DUAL CONTROL OF ADRENOCORTICOTROPHIN RELEASE*

Abstract

The ACTH response to systemic (epinephrine, cold, histamine) and to neurotropic (sound, immobilization) stimuli was compared in rats following separation of the adenohypophysis from the hypothalamic centers through homotransplantation of the gland into the anterior chamber of the eye. These animals, along with normal controls, were stimulated at weekly intervals and the fall of the circulating blood eosinophils used as an index of ACTH release. Epinephrine, cold and histamine brought about a definite eosinopenia in normal and grafted animals. Sound and immobilization induced a marked fall of the eosinophils in the intact and 1 of the grafted animals. These results suggest a dual regulation of ACTH release, one purely humoral, in response to systemic stimuli, the other, probably neuro-humoral, mediated by the hypothalamohypophyseal neurovascular pathways, and coming into play under the influence of nervous and emotional stimuli.