CORTICOTROP IN RELEASING FACTOR (CRF): EFFECTS ON THE RELEASE UF PRO-OPIOMELANOCORTIN (POMC)-RELATED PEHTIDES BY HUMAN ANTERIOR PITUITARY CELLS IN VITRO

Abstract

The effect of synthetic ovine corticotropin-releasing factor (oCRF), alpha-melanotropin (alpha-MSH) and arginine-vasopressin (AVP) on the release of pro-opiomelanocortin (POMC)-related peptides (beta-endorphin, beta-lipotropin, adrenocorticotropin, and the 12K N-terminal) was studied in primary cultures of human anterior pituitary (HAP) cells. The peptides released into the medium were measured by specific radioimmunoassays. HAP cells responded to oCRF at concentrations as low as 10 ng/ml by significantly increasing peptide secretion (p less than 0.005). AVP was also effective, but, it is only 0.1% as potent as oCRF. alpha-MSH was ineffective even at a dose of 10 micrograms/ml. Immunoreactive (IR)-beta EP, IR-beta LPH, IR-ACTH, and IR-HNT were released in approximately equimolar ratios. Partial characterization of the peptides released by HAP cells with gel chromatography on Sephadex G-50 superfine revealed two peaks of IR-beta EP (as beta EP and beta-LPH), two peaks of IR-beta LPH (as beta-LPH and gamma-LPH), one peak of IR-ACTH, and two peaks of IR-HNT. In conclusion, oCRF is a potent secretagogue for the equimolar release of ACTH, HNT and related peptides in the human pituitary gland.