Synthetic ovine corticotropin-releasing hormone: simultaneous release of proopiolipomelanocortin peptides in man.
The response of plasma proopiolipomelanocortin-derived peptide levels to synthetic ovine corticotropin-releasing hormone (CRH) was studied in six normal men. CRH was given as a 30-sec iv injection of 30 micrograms/kg body weight in the late afternoon, and blood samples were drawn for up to 16 h thereafter. Low levels of immunoreactive (IR)-ACTH, IR-beta-endorphin and IR-lipotropins (LPH) were measured before CRH administration. All subjects had prompt, concomitant, biphasic, and prolonged release of all of these proopiolipomelanocortin-derived peptides. The plasma levels of these IR-peptides rose in all subjects by 5 min after CRH, reached a first peak at 10-15 min, fell until 90 min, rose to a second peak at 2-4 h, and then gradually declined over several hours. The molar concentrations of the IR-peptides closely paralleled one another at all times, especially during the first 90 min after CRH administration. Later, IR-LPH increased slightly more and remained slightly higher than did the other IR-peptides, although the difference was not significant. This observation probably reflects the longer plasma disappearance half-life of IR-LPH. The maximum change (mean +/- SEM) in the concentration of these IR-peptides was similar: IR-ACTH, 18.0 +/- 4.0; IR-LPH, 20.5 +/- 4.0; and IR-beta-endorphin, 16.9 +/- 3.2 fmol/ml. The next morning's circadian rise in IR-peptides was blocked, presumably due to negative feedback inhibition of the hypothalamic-pituitary-adrenal axis by the prolonged high plasma cortisol levels stimulated by CRH the previous evening.
D000324:Adrenocorticotropic Hormone / Q000097:blood; D000328:Adult; D000818:Animals; D002940:Circadian Rhythm; D003346:Corticotropin-Releasing Hormone / Q000494:pharmacology*; D004723:Endorphins / Q000097:blood; D006801:Humans; D008297:Male; D010446:Peptide Fragments / Q000097:blood*; D010907:Pituitary Hormones / Q000097:blood*; D011333:Pro-Opiomelanocortin; D011863:Radioimmunoassay; D012756:Sheep; D001615:beta-Endorphin; D008083:beta-Lipotropin / Q000097:blood
D004723:Endorphins; D010446:Peptide Fragments; D010907:Pituitary Hormones; C028182:proopiocortin fragments; D001615:beta-Endorphin; D011333:Pro-Opiomelanocortin; D000324:Adrenocorticotropic Hormone; D003346:Corticotropin-Releasing Hormone; D008083:beta-Lipotropin