§ Glossary · biology

GHS receptor (GHSR-1a)

The growth-hormone secretagogue receptor — also called the ghrelin receptor.

GHSR-1a is the G-protein-coupled receptor that binds ghrelin (the endogenous hunger hormone) and synthetic growth-hormone secretagogues (GHS) including ipamorelin, GHRP-2, GHRP-6, hexarelin, and the orally-active MK-677 (ibutamoren). Activation triggers immediate GH release from pituitary somatotrophs. The receptor is also expressed in the hypothalamus (appetite) and across cardiovascular tissues — which explains why some early GHS compounds (hexarelin, GHRP-2) had unwanted appetite and cardiovascular effects. Ipamorelin was specifically engineered for GHSR-1a selectivity to minimise cross-reactivity.

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