GHRP-6 is a hexapeptide GHS-R1a agonist and the founding GHRP compound — studied in preclinical models for GH release, significant appetite stimulation, and cortisol co-stimulation via ghrelin receptor activation.
Product definition
What is GHRP-6 Acetate?
GHRP-6 is a hexapeptide GHS-R1a agonist and the founding GHRP compound — studied in preclinical models for GH release, significant appetite stimulation, and cortisol co-stimulation via ghrelin receptor activation.
GHRP-6 (His-D-Trp-Ala-Trp-D-Phe-Lys-NH2) was synthesized by Cyril Bowers' group at Tulane University and represents the first synthetic hexapeptide GH secretagogue to be broadly characterized in the literature. It established the GHRP pharmacological class before the ghrelin receptor (GHS-R1a) was cloned, and its characterization helped identify the endogenous receptor that ghrelin (discovered later) naturally activates.
The compound's appetitive effects emerge from GHS-R1a distribution in hypothalamic feeding circuits — the same receptor population that mediates ghrelin's orexigenic effects. At doses that produce robust GH release, GHRP-6 simultaneously activates hypothalamic GHS-R1a to stimulate food intake in rodent models. This dual GH/appetite axis engagement is pharmacologically distinct from the other major GHRPs and provides a research rationale for GHRP-6 in appetite biology studies that is not replicated by ipamorelin or GHRP-2.
Research context
How is GHRP-6 Acetate described in the research literature?
GHRP-6 activates GHS-R1a (ghrelin receptor) on pituitary somatotropes (GH release) and hypothalamic feeding circuits (appetite stimulation). Unlike ipamorelin, it produces significant cortisol and prolactin co-stimulation at GH-effective doses. Its ghrelin-mimetic appetite effect is the most pronounced of any characterized GHRP, making it valuable for appetite and feeding behavior research.
Compound profile
Key facts about GHRP-6 Acetate
- Class
- Founding hexapeptide GHRP / GHS-R1a agonist
- Amino acids
- 6
- Molecular weight
- ~873 Da
- Half-life
- ~15–20 minutes in vivo
- CAS
- 87616-84-0
- Selectivity
- Non-selective — GH + cortisol + prolactin + appetite
- Discovery
- Bowers et al., Tulane University, 1980s
- Research category
- GH secretagogue, appetite regulation, ghrelin receptor biology
- Storage
- Lyophilized: −20°C. Reconstituted: 2–8°C, use within 30 days
Research areas
What research areas is GHRP-6 Acetate associated with?
- Founding GHRP — first characterized synthetic hexapeptide GH secretagogue with the longest published research history
- Most pronounced appetite stimulation of any characterized GHRP — ghrelin-mimetic food intake effects via hypothalamic GHS-R1a
- GHS-R1a agonism across both GH-releasing and appetitive receptor populations — broad physiological GHRP research coverage
- Studied for GH release, cortisol co-stimulation, prolactin elevation, and appetite in the same published datasets
- Decades of published animal and human data — largest historical GHRP literature base
- Reference 'non-selective' GHRP for comparison against ipamorelin's selective profile across both GH and appetitive endpoints
Research audience
Who researches GHRP-6 Acetate?
GHRP-6 is used by researchers studying GHS-R1a pharmacology, appetite and feeding behavior, ghrelin receptor biology, GH secretagogue history and mechanism, and hypothalamic feeding circuit pharmacology. It is the reference founding GHRP for any research requiring the full physiological GHS-R1a activation profile.
Preclinical research overview
What does the preclinical literature say about GHRP-6 Acetate?
GHRP-6 was developed in Bowers' lab as part of a systematic program to identify non-peptide GH secretagogues for clinical development. The original GHRP program at Tulane characterized GHRP-6 and its structure-activity relationships, established the receptor class that would later be identified as GHS-R1a, and provided the pharmacological framework for subsequent GHRP development including GHRP-2, ipamorelin, and hexarelin.
The appetite stimulation research emerged from observations that GHRP-6-treated animals exhibited increased food intake independently of GH levels. This observation paralleled the subsequent discovery of ghrelin (the endogenous GHS-R1a ligand, also a hunger signal) — establishing that the GHRP class activates the endogenous appetite-regulating receptor. GHRP-6 remains the standard research tool for studying this appetite dimension of GHS-R1a pharmacology because its effects are the most pronounced in this dimension compared to other GHRPs.
In the historical context, GHRP-6 is the compound that demonstrated GH could be pharmacologically stimulated via a synthetic non-GHRH peptide — a finding that opened the entire GH secretagogue drug development field and ultimately led to the discovery of ghrelin, the ghrelin receptor, and the subsequent therapeutic applications in obesity and metabolic disease.
Common questions
Frequently asked about GHRP-6 Acetate
Why is GHRP-6 still used given the availability of more selective compounds?
Selectivity is valuable when isolated GH-axis effects are needed — ipamorelin is appropriate there. GHRP-6's non-selectivity is itself the research value for two reasons: (1) it is the best characterized full-spectrum GHS-R1a agonist with the most extensive published literature; (2) its appetite-stimulating effects, more pronounced than any other GHRP, make it indispensable for ghrelin receptor appetite research. If the research question involves the full physiological GHS-R1a activation profile including appetite, GHRP-6 is the correct tool.
How does GHRP-6 compare to GHRP-2 in potency?
Both are non-selective GHS-R1a agonists that stimulate GH, cortisol, and prolactin. GHRP-2 generally produces higher peak GH responses at equivalent molar doses in direct comparison studies. GHRP-6 produces more pronounced food intake stimulation at equivalent doses. For maximal GH output research, GHRP-2 is the more potent agent; for appetite/feeding behavior research, GHRP-6's orexigenic effects are the stronger research signal.
What is GHRP-6 acetate — is it different from GHRP-6?
GHRP-6 acetate is the same peptide in acetate salt form, which is the standard commercial presentation for lyophilized peptide supply. The acetate counterion facilitates lyophilization and storage stability but does not alter the pharmacological activity of the peptide itself. The active peptide sequence and receptor pharmacology are identical to free-base GHRP-6.
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