Potentiation of the hCRF-induced release of ACTH in man by an opioid antagonist.
Administration of synthetic human corticotropin-releasing factor (hCRF; 2 micrograms/kg body weight) to six normal male subjects produced a significant rise in plasma ACTH, followed by an increase in circulating cortisol. Simultaneous treatment with the opioid antagonist naloxone (1.6 mg i.v. bolus, followed by an infusion at a rate of 1.2 mg/h) significantly potentiated the hCRF-induced rise in ACTH and enhanced the cortisol response to hCRF. It is suggested that naloxone acts by antagonizing an inhibitory ultra-short-loop feedback effect of coreleased beta-endorphin on pituitary corticotrophs, thereby amplifying the net effect of hCRF, i.e., the release of ACTH.
D000324:Adrenocorticotropic Hormone / Q000097:blood*; D000328:Adult; D003346:Corticotropin-Releasing Hormone / Q000494:pharmacology*; D004357:Drug Synergism; D006728:Hormones / Q000494:pharmacology*; D006801:Humans; D007030:Hypothalamo-Hypophyseal System / Q000187:drug effects; D008297:Male; D009270:Naloxone / Q000494:pharmacology*; D010913:Pituitary-Adrenal System / Q000187:drug effects; D011957:Receptors, Opioid / Q000187:drug effects
D006728:Hormones; D011957:Receptors, Opioid; D009270:Naloxone; D000324:Adrenocorticotropic Hormone; D003346:Corticotropin-Releasing Hormone