STUDIES OF THE REGULATION OF THE HYPOTHALAMIC-PITUITARY-ADRENAL AXIS IN SHEEP WITH HYPOTHALAMIC-PITUITARY DISCONNECTION .1. EFFECT OF AN AUDIOVISUAL STIMULUS AND INSULIN-INDUCED HYPOGLYCEMIA

Abstract

These studies were undertaken to characterize the secretion of adrenocorticotropin (ACTH), immunoreactive (ir) beta-endorphin (ir-beta-EP) and ir alpha-melanocyte-stimulating hormone (ir-alpha-MSH) from the surgically isolated ovine pituitary in response to an audiovisual stress (barking dog, 3 min) and insulin hypoglycemia. The studies were performed in 4 ovariectomized, hypothalamo-pituitary-disconnected (HPD) and 4 sham-HPD ewes bearing indwelling jugular venous catheters. Basal concentrations of the three pro-opiomelanocortin (POMC) peptides and plasma cortisol were significantly increased in the HPD animals. When the control ewes were exposed to the audiovisual stimulus, plasma ACTH, ir..