ABSTRACT
Growth hormone-releasing peptide-6 (GHRP-6) is believed to stimulate pulsatile GH release through the activation of a receptor distinct from the somatostatin and growth hormone-releasing hormone receptor (GHRH-R; 1-3). Following the discovery of GHRP-6 and its enhancement of GH release, several nonpeptidyl growth hormone secretagogues (GHSs) were developed, as exemplified by L-163, 191 (MK-0677; 4,5). Nonpeptidyl GHSs, similar to GHRP-6, stimulate GH release through inositol triphosphate (PI3)-coupled mechanisms that mediate intracellular Ca2 + release and depolarization, leading to exocytosis of GH-containing secretory vesicles (6-10).
