GHRH

GHRH stands for growth hormone-releasing hormone, a 44-amino-acid peptide produced primarily in the arcuate nucleus of the hypothalamus. It is secreted into the hypothalamic-hypophyseal portal circulation, reaches the anterior pituitary, and stimulates somatotroph cells to synthesize and release growth hormone (GH). GHRH was first isolated from human pancreatic tumors that caused acromegaly, and its structure was characterized in 1982; that discovery completed the hypothalamic-pituitary axis for growth hormone by identifying the positive-regulatory peptide that is balanced by somatostatin (Guillemin et al., Science 1982 (NLM 6812267); Rivier et al., Nature 1982 (NLM 6812246)).

Receptor and signaling

GHRH signals through the growth hormone-releasing hormone receptor (GHRHR), a class B G-protein-coupled receptor expressed principally on pituitary somatotrophs. Receptor engagement activates Gs, elevates intracellular cAMP, and stimulates both GH synthesis and GH release. The first 29 residues of GHRH are sufficient for full agonist activity, and the GHRH(1-29)-NH2 fragment (sometimes called sermorelin in the pharmaceutical literature) is the commonly studied truncated agonist. The short circulating half-life of native GHRH - on the order of minutes, driven in part by DPP-4 cleavage of the N-terminal dipeptide - is the main reason longer-acting analogs such as tesamorelin exist. The receptor pharmacology is reviewed in Mayo et al., Recent Prog. Horm. Res. 1995 (NLM 7740178).

GHRH in research contexts

In RUO research, GHRH and its truncated and modified analogs are used as reference agonists to study GHRHR signaling in pituitary-derived cell lines and in recombinant receptor systems, and as tool peptides in studies of the growth hormone axis. Characterization of a GHRH-family research peptide should confirm intact mass by LC-MS, HPLC purity, and the amidation state of the C-terminus (GHRH(1-29) is biologically active as the C-terminal amide; the free acid has reduced activity). Net-peptide content and counterion information are important because the reported potency in a binding or functional assay depends on the actual mass of peptide in the vial, not on the nominal label mass.

How Open Assay catalogs GHRH-family peptides

Open Assay indexes GHRH, GHRH(1-29)-NH2, tesamorelin, and related analogs separately because they are distinct molecules with distinct purity and identity considerations. Listings link to the published characterization of each peptide and present COA fields (HPLC purity, mass confirmation, net-peptide content, endotoxin) on a consistent basis so a reader can compare like with like across suppliers.