The ghrelin receptor — the second pathway through which growth hormone can be stimulated, separate from the GHRH pathway.A G protein-coupled receptor expressed in the pituitary, hypothalamus, and peripheral tissues. Activated by ghrelin (the endogenous ligand) and synthetic GH secretagogues: ipamorelin, hexarelin, GHRP-2, GHRP-6, and MK-677. GHS-R1a agonism stimulates GH secretion and also stimulates appetite — ghrelin is the "hunger hormone." The dual GHRH+GHS-R1a stimulation approach amplifies GH release because both pathways converge on the same pituitary cells via different receptors.