Glossary
GHRH
GHRH is a 44-residue hypothalamic peptide that acts on GHRHR in pituitary somatotrophs. Why its analogs end at residue 29 and how those analogs differ.
GHRH, growth hormone-releasing hormone, is a peptide of 44 amino acids secreted in bursts by the arcuate nucleus of the hypothalamus. It travels to the anterior pituitary via the hypophyseal portal vessels and binds GHRHR, a class B GPCR on somatotrophs; the resulting rise in cAMP sets off both production and release of growth hormone.
Why the analogs end at residue 29
The activity lies in the N-terminal section: GHRH(1-29), called sermorelin, keeps practically all of the potency. DPP-4 quickly cuts native GHRH at Ala2, leaving a plasma half-life of just a few minutes, so research analogs alter that position. CJC-1295 without DAC (Mod GRF 1-29) has four substitutions that protect it from DPP-4 and trypsin, whereas Tesamorelin attaches a trans-3-hexenoyl group to the N-terminus of the complete 44-residue chain.
Upstream action and pairing
Because GHRH analogs work higher up the axis, at the pituitary, the release they trigger stays pulsatile and remains under somatostatin feedback — mechanistically a different starting point from supplying growth hormone itself. Published studies often combine them with a GHRP, since the two use different receptors.
Related terms
growth hormone secretagogue · IGF-1. Browse GHRH analogs, see Sermorelin, or compare in Tesamorelin vs Sermorelin.