The difference from giving growth hormone (somatropin) is fundamental: the secretagogue does not supply GH, it stimulates the pituitary to release what it produces, largely respecting the axis's own control mechanisms, such as IGF-1 feedback and somatostatin.
There are two main classes, acting on different receptors. GHRH analogues (sermorelin, tesamorelin, CJC-1295) activate the GHRH receptor. GHRPs and ghrelin mimetics (ipamorelin, GHRP-2, GHRP-6 and, orally, the non-peptide MK-677) activate the GHS-R1a receptor.
The two pathways reinforce each other: GHRH increases the amount of GH released in each pulse, and GHRPs amplify the pulse and counteract somatostatin. That is why combinations such as CJC-1295 + ipamorelin are studied in research.
Selectivity matters: ipamorelin is characterised by stimulating GH with little or no rise in cortisol or prolactin, unlike older GHRPs. It is a common criterion when comparing compounds in this class.
Related terms
Learn it in depth at the Peptide University
- GHRPs, ghrelin mimetics and synergy · Module 5
- Repair and somatotropic axis (6–10) · Module 14
- Safety profiles by class · Module 10
- G protein-coupled receptors: desensitization and tolerance · Module 2
- Physiology of the GH/IGF-1 axis · Module 5
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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).