GHRP-6
Growth Hormone Secretagogue (Ghrelin Mimetic)researchAlso known as: Growth Hormone Releasing Peptide-6, Growth Hormone Releasing Hexapeptide, SKF-110679, His-D-Trp-Ala-Trp-D-Phe-Lys-NH2
A synthetic hexapeptide growth hormone secretagogue that stimulates GH release through the ghrelin receptor (GHS-R1a), notable for its potent GH-releasing effects and strong appetite stimulation.
Overview
GHRP-6 (Growth Hormone Releasing Peptide-6) is one of the earliest synthetic growth hormone secretagogues, developed in the 1980s by Cyril Bowers' research group. It is a hexapeptide that stimulates growth hormone release by activating the ghrelin/growth hormone secretagogue receptor (GHS-R1a) on pituitary somatotrophs. GHRP-6 was instrumental in the discovery and characterization of the ghrelin receptor system. Compared to other GHRPs like Ipamorelin, GHRP-6 produces a more robust but less selective GH pulse, also elevating cortisol, prolactin, and strongly stimulating appetite through the ghrelin pathway. The strong appetite-stimulating effect makes it popular among bodybuilders seeking to increase caloric intake during bulking phases but less desirable for those focused on fat loss. GHRP-6 also has demonstrated gastroprotective and cardioprotective properties in preclinical studies.
Mechanism of Action
GHRP-6 stimulates GH release through several mechanisms: (1) Binds to the growth hormone secretagogue receptor (GHS-R1a) on pituitary somatotrophs, triggering GH release; (2) Acts at the hypothalamic level to stimulate GHRH release and suppress somatostatin; (3) Strongly activates the ghrelin signaling pathway, leading to potent appetite stimulation via hypothalamic NPY/AgRP neurons; (4) Triggers GH release through a pathway independent of and synergistic with GHRH; (5) Mildly stimulates ACTH/cortisol release through non-specific receptor interactions; (6) May transiently increase prolactin through pituitary cross-reactivity; (7) Demonstrates cytoprotective effects in gastric mucosa and cardiac tissue through ghrelin receptor-mediated signaling; (8) Promotes hepatic and local IGF-1 production secondary to GH elevation.
Molecular Formula
C46H56N12O6
Molecular Weight
873.01 g/mol
Sequence
His-D-Trp-Ala-Trp-D-Phe-Lys-NH2
Dosage Protocols
Dose Range
100mcg – 300mcg
Frequency
2-3 times daily
Route
subcutaneous
Cycle Length
8-16 weeks
Best taken on an empty stomach — food (especially fats and carbohydrates) significantly blunts GH response. Common timing: morning, post-workout, and before bed. 100mcg per dose is generally saturating for GH release.
Source: Clinical research and community protocols
Side Effects
| Effect | Severity |
|---|---|
| Intense hunger | moderate |
| Water retention | mild |
| Cortisol elevation | mild |
| Prolactin elevation | mild |
| Tingling/Numbness | mild |
| Injection site reactions | mild |
| Dizziness/Light-headedness | mild |
Pros & Cons
One of the most potent peptide GH secretagogues, producing robust growth hormone pulses
Highly synergistic with GHRH analogues, amplifying GH release significantly when combined
Strong appetite stimulation is beneficial for hard-gainers and bulking phases
Extensive research history dating back to the 1980s with well-characterized pharmacology
Demonstrated gastroprotective and cardioprotective properties in preclinical models
Less selective than Ipamorelin — elevates cortisol and prolactin in addition to GH
Intense appetite stimulation can be counterproductive for fat loss goals
Requires fasted state for optimal GH release, making meal timing complex with 2-3x daily dosing
Not FDA-approved; available only as a research chemical
Multiple daily injections needed for optimal results
Research Studies
Legal Status
Not FDA-approved. Available as a research chemical. Banned by WADA for competitive athletes. Has been used clinically in research settings to test GH reserve.
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