Natural GHRH has 44 amino acids, but all of its activity lies in the first 29: the GHRH(1-29) fragment, which is the basis of sermorelin. The analogues studied today are built on that fragment.
Tesamorelin adds a chemical group at the N-terminus that protects it from breakdown and is approved as a medicine for a specific indication. Mod GRF 1-29 (CJC-1295 without DAC) replaces four amino acids to better resist enzymes. CJC-1295 with DAC adds to those substitutions a complex that binds it to albumin and extends its half-life to several days.
GHRH works in balance with somatostatin, which holds back GH release. The alternation between them produces the pulsatile secretion of growth hormone, with the largest pulses during deep sleep.
All GHRH analogues act on the same receptor; what changes is how long they last. That difference determines whether the signal is pulsatile (sermorelin, Mod GRF) or sustained (CJC-1295 with DAC).
Related terms
Learn it in depth at the Peptide University
- Repair and somatotropic axis (6–10) · Module 14
- GHRH analogs · Module 5
- Somatotropic, neuro and others (11–15) · Module 14
- GHRPs, ghrelin mimetics and synergy · Module 5
- G protein-coupled receptors: desensitization and tolerance · Module 2
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Definition for educational and scientific purposes. It is not medical advice or a recommendation for use. NeoPeptidos products are sold labelled for research use only (RUO).