GHRH (Growth Hormone-Releasing Hormone)

GHRH (Growth Hormone-Releasing Hormone, or somatoliberin) is a 44-amino acid hypothalamic hormone that constitutes the main signal stimulating growth hormone (GH) secretion by the anterior pituitary. Discovered in 1982 by Guillemin and Rivier, it forms with somatostatin (inhibitor) and ghrelin (alternative stimulator) the regulatory trio of the somatotropic axis.

GHRH binds to a specific receptor (GHRH-R) expressed on the surface of pituitary somatotropic cells. This receptor, a member of the class B GPCR family, primarily activates the cAMP-PKA pathway, leading to pulsatile GH secretion. Repeated activation also sensitizes somatotropic cells to ghrelin and synchronizes the characteristic nocturnal pulses, the period during which most daily GH is released in healthy humans.

Pharmacological interest in GHRH was quickly limited by its extremely short half-life (less than 10 minutes), linked to rapid degradation by DPP-4 and aminopeptidases. Developed analogues circumvent this limitation. Sermorelin is the active GHRH(1-29) fragment retaining complete activity. Tesamorelin adds an N-terminal modification (trans-3-hexenoyl) resistant to DPP-4 and extending half-life to approximately 26 minutes. CJC-1295 represents the most sophisticated evolution: it combines four substitutions with non-natural amino acids (D-Ala, Gln, Ala, Leu) to resist enzymatic degradation, and in its DAC (Drug Affinity Complex) version carries a maleimide that covalently binds to serum albumin, extending half-life to 6 to 8 days.

In exploratory research, GHRH analogues enable study of several fundamental questions. First, the architecture of the somatotropic axis: how is GHRH pulsatility decoded by the pituitary to generate GH secretion profiles? Next, the desensitization mechanisms of the GHRH-R receptor during continuous versus intermittent administration. Finally, the distal metabolic effects of GH itself (lipolysis, protein anabolism, cellular differentiation) studied through its stable amplification by GHRH analogues.

On lab-peptides-france.com, available GHRH analogues include CJC-1295 DAC, CJC-1295 without DAC and sermorelin. These compounds are marketed exclusively for research use (RUO, Research Use Only) and must never be used on humans outside authorized clinical trials. They enable laboratories to explore the biology of the GHRH/GH/IGF-1 axis with high analytical quality pharmacological tools.