Description
GHRP-6 (Growth Hormone Releasing Peptide-6) is a synthetic hexapeptide and one of the oldest compounds within the GH secretagogue class. Like GHRP-2, GHRP-6 acts as an agonist at the ghrelin receptor (GHSR-1a) and triggers pulsatile GH release from somatotrope cells of the anterior pituitary.
The central difference from GHRP-2 and ipamorelin lies in the pronounced hunger-stimulating effect. GHRP-6 shows effects on appetite behavior in preclinical studies that most closely resemble natural ghrelin activity. Ghrelin itself is characterized as the “hunger hormone,” and GHRP-6 reflects this profile more clearly than the more selective compounds of the GHRP family.
This characteristic makes GHRP-6 a distinct research tool. While ipamorelin is preferred for clean GH research without appetite confounding, GHRP-6 is interesting for research questions that explicitly investigate the ghrelin-hunger pathway or where increased food intake is relevant as a secondary observation.
In animal models, substantial increases in GH secretion as well as changes in feeding behavior have been documented with GHRP-6. With a half-life of approximately 15-30 minutes, it is short, comparable to other GHRPs.
GHRP-6 has a substantial research history reaching back into the 1980s and has substantially contributed to the understanding of the ghrelin axis. In modern research setups, switching to newer compounds is common, but GHRP-6 remains relevant for ghrelin-specific research questions.
GHRP-6 is available in 5mg vials as 10-vial packs.
This information is for research and educational purposes only. No medical recommendations.
Risks & Safety
GHRP-6 is considered well tolerated per study reports. As a ghrelin receptor agonist, the compound stimulates the body’s own GH secretion, but shows the most pronounced hunger-stimulating effect among the GHRPs.
Observed in research and user reports:
- Injection site: mild redness, pressure or transient irritation at the injection site is the most common observation with subcutaneous use.
- Pronounced hunger effect: GHRP-6 reflects the natural ghrelin profile more clearly than more selective compounds and is associated in studies with markedly increased food intake.
- GH-typical effects: as is common with GH secretagogues, the literature describes transient water retention as well as numbness or tingling in the hands (carpal-tunnel-type symptoms), usually dose-dependent and reversible.
- Cortisol and prolactin: like other non-selective GHRPs, GHRP-6 shows a moderate elevation of cortisol and prolactin in studies.
- No long-term data: robust long-term human studies for research use do not exist. The profile rests primarily on short-term studies and anecdotal experience.
This classification does not replace medical advice. Risk and responsibility for any actual use lie entirely with the buyer.
Studies
- On the in vitro and in vivo activity of a new synthetic hexapeptide that acts on the pituitary to specifically release growth hormone - Endocrinology 1984: First description of the hexapeptide: it released GH dose-dependently in vitro and in several animal species without a concomitant release of LH, FSH, TSH or prolactin.
- A receptor in pituitary and hypothalamus that functions in growth hormone release - Science 1996: Cloning of the G protein-coupled receptor in pituitary and hypothalamus that is the target of the synthetic GH secretagogues.
- Ghrelin is a growth-hormone-releasing acylated peptide from stomach - Nature 1999: Discovery of ghrelin as the endogenous ligand of this receptor: a 28-amino-acid peptide from the stomach, octanoylated at serine 3, that releases GH.
- Acute central ghrelin and GH secretagogues induce feeding and activate brain appetite centers - Endocrinology 2002: Centrally administered ghrelin or GHRP-6 increased food intake in rats and activated appetite centers in the hypothalamus and brainstem. An NPY Y1 antagonist blocked the effect.
- Synthetic Growth Hormone-Releasing Peptides (GHRPs): A Historical Appraisal of the Evidences Supporting Their Cytoprotective Effects - Clinical Medicine Insights: Cardiology 2017: Review of the cytoprotective effects of GHRPs in preclinical models, mediated via the receptors GHS-R1a and CD36, for example in cardiac, neuronal, gastrointestinal and hepatic cells.
