What is GHRH? (Peptide Glossary)

GHRH is the hypothalamus's signal to the pituitary to release growth hormone. The native human form is 44 amino acids, but its biological activity lives in the first 29 residues - which is why the research compounds derived from it are fragments and analogs: sermorelin (GHRH 1-29), CJC-1295 / Modified GRF 1-29 (stabilized substitutions), and tesamorelin (full 44-mer with a stabilizing modification).

GHRH-class peptides work with the body's own regulatory machinery rather than overriding it. They stimulate the pituitary to release GH in its natural pulsatile pattern, and negative feedback loops remain intact. This contrasts with administering growth hormone itself and is the mechanistic reason the class attracts research interest.

For researchers, the GHRH family illustrates how small molecular changes create different research tools: sermorelin's 10-20 minute half-life suits pulsatile studies, CJC-1295 DAC's week-long half-life suits sustained-elevation models, and tesamorelin brings full human clinical trial data from its FDA approval. Compound selection in GH axis research starts with matching the analog's pharmacokinetics to the research question.