Brattleboro rats have deficient adrenocorticotropin responses to activation of central α1-adrenoceptors

This experiment was designed to test further the hypothesis that vasopressin is the major mediator of the ACTH response to activation of central α1-adrenoceptors in the rat. The α1-adrenergic agonist methoxamine was given intracerebroventricularly to conscious vasopressin-deficient (homozygous Brattleboro) and normal rats bearing venous and intracerebroventricular cannulae. Methoxamine stimulated the secretion of ACTH in the normal, but not in the vasopressin-deficient, rats. The data confirm that vasopressin, rather than CRH-41 or oxytocin, is the major hypothalamic peptide that mediates the effects of central α1-adrenoceptors on the pituitary corticotrophs. © 1990 by The Endocrine Society.