The effects of dermorphin on the endocrine system in man

This paper summarizes the results of our recent studies in a group of healthy subjects on the endocrine effects of the new potent opioid peptide, dermorphin (H-Tyr-D-Ala-Phe-Gly-Tyr-Pro-Ser-NH2), originally isolated from amphibian skin. Intravenous infusion (5.5 microgram/kg/min for 30 min) of dermorphin (D) significantly increased plasma levels of prolactin (PRL), growth hormone (GH), thyrotropin (TSH) and renin activity (PRA), but decreased plasma levels of cortisol. D produced a small decrease in ACTH, and a small increase in plasma aldosterone. Pretreatment with the opioid receptor antagonist naloxone (N) suppressed the PRL and TSH response to D, blunted the D-induced GH and PRA increase, and completely prevented the D-induced plasma cortisol decrease, but enhanced plasma cortisol and ACTH levels. These data indicate that the action of D is mediated through opioid receptors, and are consistent with the conclusion that: (1) D, a new opioid peptide, can stimulate PRL, GH and TSH release in humans; (2) D increases PRA levels, perhaps via activation of the sympathetic nervous system, providing evidence that opioid peptides may exert an influence on renin secretion; (3) D suppresses plasma cortisol levels, by affecting ACTH secretion, corroborating previous observations that opioid peptides might affect the function of the pituitary-adrenocortical axis.