STUDIES OF THE SECRETION OF CORTICOTROPIN-RELEASING FACTOR AND ARGININE-VASOPRESSIN INTO THE HYPOPHYSEAL-PORTAL CIRCULATION OF THE CONSCIOUS SHEEP .2. THE CENTRAL NORADRENERGIC AND NEUROPEPTIDE-Y PATHWAYS CAUSE IMMEDIATE AND PROLONGED HYPOTHALAMIC-PITUITARY-ADRENAL ACTIVATION - POTENTIAL INVOLVEMENT IN THE PSEUDO-CUSHINGS SYNDROME OF ENDOGENOUS-DEPRESSION AND ANOREXIA-NERVOSA

Abstract

Studies were performed to determine the effects of intracerebroventricular norepinephrine (NE) or neuropeptide Y (NPY) on the ovine hypothalamic-pituitary-adrenal (HPA) axis. NE (50 micrograms) increased mean hypophysial-portal corticotropin-releasing factor (CRF) and arginine vasopressin (AVP) levels (1 h, 1.3- and 2.9-fold; 4 h, 2.2- and 5.7-fold) and caused acute and sustained increases in mean plasma ACTH and cortisol. NPY (50 microgram) also increased mean CRF and AVP levels (1 h, 1.4- and 4.2-fold; 4 h, 1.1- and 1.9-fold), increased pituitary-adrenal activity at 1 h, and caused ACTH hypersecretion at 4 h. When added to cultured ovine anterior pituitary cells, NPY neither increased basa..