6AA Limited Human
GHRP-6
First synthetic hexapeptide to trigger pulsatile GH release via the ghrelin receptor — potent, broad-spectrum, with 35+ years of research behind it.
In Plain English:
GHRP-6 is a six-amino-acid synthetic peptide that mimics ghrelin, the body's own hunger and GH-trigger hormone. It binds the ghrelin receptor (GHS-R1a) in the pituitary and hypothalamus, firing off a strong pulse of growth hormone within minutes. Because it uses the same receptor as ghrelin, it also sharpens appetite and — at a separate receptor (CD36) — shows substantial organ-protective effects in preclinical models. Roughly 778 PubMed-indexed papers span three decades of research, making it one of the most studied GH secretagogues. It is not approved for human therapeutic use in any jurisdiction and remains a research compound.
Research Maturity
Limited Human (778 PubMed-indexed publications (1984-2026); limited human data, no Phase 3 RCTs+ Studies)
Focus
Body Composition
Hormone Signaling
Metabolic Research
Origin
Synthetic hexapeptide first described by Cyril Bowers and colleagues in 1984 as the prototypical growth hormone secretagogue. Derived from structural modification of met-enkephalin analogues incorporating unnatural D-amino acids (D-Trp, D-Phe). Served as the template from which ipamorelin, GHRP-2, hexarelin, and MK-677 were subsequently developed.
Mechanism
Full agonist at GHS-R1a (ghrelin receptor), a Gq-coupled GPCR expressed on pituitary somatotrophs and hypothalamic neurons. Binding activates phospholipase C → IP3/DAG → intracellular Ca²⁺ mobilisation and PKC activation → pulsatile GH secretion. Simultaneously activates CD36 scavenger receptor, engaging the PI3K/AKT prosurvival pathway independent of GH signalling, accounting for cytoprotective effects in cardiac, hepatic, renal, and intestinal tissue. Non-selective: also elevates ACTH/cortisol and prolactin alongside GH, distinguishing it from selective secretagogues like ipamorelin.
Outcome
Peak serum GH and GH-AUC, serum IGF-1, appetite/caloric intake (ghrelin pathway), cortisol and prolactin co-secretion, left ventricular ejection fraction (cardioprotection models), organ ischemia/reperfusion injury scores, reactive oxygen species markers, Bcl-2/Bax ratio.
