Naloxone-Induced Acth Release in Man Is Inhibited by Clonidine

1. Adrenergic mechanisms play an important role in regulation of ACTH release. We used the α‐adrenergic agonist, clonidine, as a central nervous system inhibitor of ACTH release to see if it would alter naloxone‐induced ACTH secretion in normal human volunteers. 2. There was a significant blunting of the mean peak level of ACTH and the mean peak change of ACTH from basal as well as the area under the ACTH‐time curve when clonidine was given prior to naloxone. 3. We conclude that clonidine, by blocking central noradrenergic pathways, which stimulate corticotropin‐releasing hormone secretion, inhibits naloxone‐induced ACTH secretion. This suggests that naloxone causes ACTH release through these same central noradrenergic pathways