Growth Hormone-Releasing Peptides Explained: GHRH Analogs, GHRPs and Ghrelin Mimetics

Many peptides in research catalogs act on the growth hormone axis. This guide explains the biology and the difference between GHRH analogs, GHRPs and related fragments.

Research Peptide Guide

Key takeaways

  • Growth hormone release from the pituitary is stimulated by GHRH and ghrelin and inhibited by somatostatin.
  • GHRH analogs such as sermorelin and CJC-1295 act on the GHRH receptor, while GHRPs and ipamorelin act on the ghrelin receptor.
  • IGF-1 and its variants are downstream of growth hormone and are a separate group of research peptides.

The growth hormone axis

In the pituitary, somatotroph cells release growth hormone (GH) in pulses. The hypothalamus controls this through two opposing peptides: GHRH (growth hormone-releasing hormone), which stimulates release, and somatostatin, which inhibits it. A third input is ghrelin, a stomach-derived hormone that stimulates GH release by acting on the growth hormone secretagogue receptor, GHS-R1a. GH in turn drives the liver and other tissues to produce IGF-1.

GHRH analogs

These peptides are built from the sequence of GHRH and act on the GHRH receptor.

  • Sermorelin: a 29-amino-acid fragment (GHRH 1–29), the shortest fragment that retains full activity.
  • CJC-1295: a modified GHRH(1–29) analog. Without DAC (also called Mod GRF 1-29) it is short-acting. With DAC it binds albumin and stays active much longer.
  • Tesamorelin: a 44-amino-acid GHRH analog with a trans-3-hexenoyl group added at the N-terminus.

GHRPs and ghrelin mimetics

These synthetic compounds act on the ghrelin receptor instead of the GHRH receptor.

  • GHRP-6 and GHRP-2: synthetic hexapeptides among the earliest growth hormone-releasing peptides.
  • Hexarelin: a synthetic hexapeptide in the same family.
  • Ipamorelin: a pentapeptide described in early pharmacology studies as more selective for GH release than some earlier GHRPs.

Fragments and downstream peptides

  • AOD-9604 and related fragments are based on the C-terminal region of GH (residues 176–191).
  • IGF-1 LR3 is an 83-amino-acid IGF-1 analog with an extended N-terminus and an arginine substitution, and IGF-1 DES is a truncated form missing its first three amino acids.
  • MGF (mechano growth factor) is a splice variant of IGF-1.

Why combinations are studied

Because GHRH analogs and ghrelin mimetics act on different receptors, researchers sometimes study them together, which is why many peptide blends pair a GHRH analog with a ghrelin mimetic. This guide is educational only; it makes no claims about use in people.

Browse the Peptides collection or the blends to see available compounds.

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Frequently asked questions

What is a growth hormone secretagogue?
It is a compound that stimulates the release of growth hormone, either by acting on the GHRH receptor or on the ghrelin receptor (GHS-R1a).
What is the difference between CJC-1295 with DAC and without DAC?
DAC stands for drug affinity complex, a chemical modification that lets the peptide bind albumin and remain active far longer. The version without DAC, also called Mod GRF 1-29, has a much shorter duration of action.
Is ipamorelin a GHRH analog?
No. Ipamorelin is a pentapeptide that acts as a ghrelin receptor agonist, whereas GHRH analogs act on the GHRH receptor.

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