GHRP-6

What Is GHRP-6?

GHRP-6 (Growth Hormone Releasing Peptide-6) is a synthetic hexapeptide and potent stimulator of endogenous growth hormone (GH) release from the anterior pituitary. It is a ghrelin receptor (GHSR-1a) agonist and one of several ghrelin analogues developed over recent decades.

Preclinical studies indicate that GHRP-6 may influence:

• Cardiac myocytes and post–myocardial infarction remodeling
• Learning, memory, and hippocampal neurogenesis
• Wound healing, scar formation, and skin appearance
• Dopaminergic neurons implicated in Parkinson’s disease
• Sexual motivation and mood-related behaviors

GHRP-6 is orally and sublingually active in animal models and shows moderate-to-high receptor selectivity.

GHRP-6 Structure

• Sequence: His–D-Trp–Ala–Trp–D-Phe–Lys–NH₂

GHRP-6 – Key Research Findings

1. Memory and Learning

Animal research suggests that GHRP-6 plays a role in consolidating newly formed memories and supporting the conversion of short-term memories into long-term storage. Studies in rodents indicate:

• Enhanced memory encoding and retrieval via ghrelin signaling [1–3].
• A role in spatial learning tasks, consistent with the high density of ghrelin receptors in memory-associated brain regions.

These findings support the hypothesis that some exercise-induced cognitive benefits may be mediated indirectly via ghrelin and growth hormone secretagogues such as GHRP-6.

2. Neuroprotection in Ischemic Injury

In animal models of stroke, GHRP-6 has been investigated for its potential to protect central nervous system tissue from ischemia:

• Reduction of neuronal apoptosis (programmed cell death) and neuroinflammation [4][5].
• Partial rescue of post-stroke memory deficits when administered within an appropriate therapeutic window [4].

These effects are thought to be mediated by ghrelin receptor–dependent pathways that enhance neuronal survival.

3. Protection of Dopaminergic Neurons in Parkinsonian Models

Research into Parkinson’s disease models has highlighted the importance of ghrelin receptors on dopaminergic neurons in the substantia nigra:

• Decreased expression of ghrelin receptors in this region has been associated with Parkinsonian motor deficits [6].
• Ghrelin agonists such as GHRP-6 may help reduce apoptosis of substantia nigra neurons, potentially slowing or modifying disease processes in preclinical models.

4. Wound Healing, Skin Quality, and Scar Reduction

GHRP-6 has demonstrated several effects on wound repair and skin structure in animal and early clinical studies:

• Reduced apoptosis in multiple cell types involved in wound healing.
• Accelerated neovascularization (blood vessel growth) and improved wound closure rates [7].
• Enhanced extracellular matrix (ECM) protein deposition, including collagen, resulting in improved mechanical strength and cosmetic outcome of healed tissue [7][8].
• Prevention or attenuation of hypertrophic and keloid-like scarring in preclinical models [8].

These data suggest a potential role for GHRP-6 as a modulator of tissue repair and scar formation under experimental conditions.

5. Cardioprotection After Myocardial Infarction

Porcine models of acute myocardial infarction have been used to test GHRP-6 in the setting of ischemia–reperfusion injury:

• GHRP-6 reduced oxidant-induced cytotoxicity and limited myocardial necrosis when administered after the ischemic event [9].
• This cardioprotective effect may help preserve vulnerable but still viable myocardium in preclinical models.

6. Effects on Sex Motivation and Mood

Central ghrelin receptor signaling has been implicated in reward and motivation circuitry:

• Stimulation of ghrelin receptors in specific brain regions increases sexual motivation in male rats [10].
• GHRP-6 and related peptides (e.g., GHRP-2) appear to share similar properties in animal studies.
• Additional work indicates that ghrelin/GHSR signaling can modulate mood-related behaviors and may reduce depression-like manifestations under chronic stress in mice [11].

These findings have led to interest in ghrelin agonists as potential tools for investigating motivation, reward, stress, and mood regulation in experimental models.

Safety and Research Use

In animal studies, GHRP-6 has shown:

• Minimal to moderate side effects
• Low oral and excellent subcutaneous bioavailability in mice

Important:
Doses and effects observed in animal models do not translate directly to humans. GHRP-6 offered by Peptide Sciences is provided strictly for laboratory and scientific research purposes only. It is not for human consumption, medical, or veterinary use. Purchase is restricted to qualified, licensed research professionals.

Article Author

This summary was researched, edited, and organized by Dr. Logan, M.D. Dr. Logan holds a doctorate from Case Western Reserve University School of Medicine and a B.S. in Molecular Biology.

Scientific Journal Author Acknowledgment

Professor Marta Korbonits obtained her medical degree in Budapest and completed early clinical training at the Internal Medicine Clinic of the Postgraduate Medical School in Budapest. She then joined the Department of Endocrinology at St. Bartholomew’s Hospital under Professors Ashley Grossman and Steve Bloom.

Her MD and PhD work significantly advanced understanding of:

• Growth hormone secretagogues and their impact on hypothalamic hormone release
• Molecular mechanisms underlying pituitary tumorigenesis
• The regulation of the ghrelin axis and pathways of hormonal excess

As an MRC Clinician Scientist Fellow, she contributed to:

• Identification of mutations in the AIP gene (aryl hydrocarbon receptor–interacting protein), a tumor suppressor
• Insights into glucocorticoid-related regulation of metabolism

In 2008, Professor Korbonits became Professor of Endocrinology and Metabolism at Queen Mary University of London and has led the Centre of Endocrinology at Barts and The London School of Medicine. In 2016, she was appointed Deputy Head of the William Harvey Research Institute. She continues to integrate human studies with laboratory-based research and has been a pioneer in translational endocrine medicine.

Important Notice:
Professor Marta Korbonits is referenced as one of the prominent scientists whose work has contributed to the scientific understanding of GHRP-6 and related growth hormone secretagogues [12]. She does not endorse, support, or have any affiliation with Peptide Sciences or the sale, purchase, or use of this product. The reference is provided solely to credit her peer-reviewed research contributions.

References

1. Huang, C.-C., Chou, D., Yeh, C.-M., & Hsu, K.-S. "Acute food deprivation enhances fear extinction but inhibits long-term depression in the lateral amygdala via ghrelin signaling." Neuropharmacology, 101, 36–45 (2016).
2. Beheshti, S., & Shahrokhi, S. "Blocking the ghrelin receptor type 1a in the rat brain impairs memory encoding." Neuropeptides, 52, 97–102 (2015).
3. Tóth, K., Laszlo, K., & Lenard, L. "Role of intraamygdaloid acylated-ghrelin in spatial learning." Brain Res. Bull., 81(1), 33–37 (2010).
4. Sucháč, N. et al. "Assessment of dose-effect and therapeutic time window in preclinical studies of nIGF-1 and GHRP-6 coadministration for stroke therapy." Neurol. Res., 38(3), 187–195 (2016).
5. Spencer, S. J., Miller, A. A., & Andrews, Z. B. "The Role of Ghrelin in Neuroprotection after Ischemic Brain Injury." Brain Sci., 3(1), 344–359 (2013).
6. Sutra, Y. et al. "Down-regulation of ghrelin receptors on dopaminergic neurons in the substantia nigra contributes to Parkinson's disease-like motor dysfunction." Mol. Brain, 11(1), 6 (2018).
7. Mendoza-Mari, Y. et al. "Growth Hormone-Releasing Peptide-6 Enhances the Healing Process and Improves the Esthetic Outcome of the Wound." Plastic Surgery International, 2016, 4361702.
8. Fernández-Mayola, M. et al. "Growth hormone releasing peptide 6 prevents cutaneous hypertrophic scarring: early mechanistic data from a proteome study." Int. Wound J., 15(4), 538–546 (2018).
9. Berlanga, J. et al. "Growth hormone-releasing peptide 6 (GHRP-6) prevents oxidant cytotoxicity and reduces myocardial necrosis in a model of acute myocardial infarction." Clin. Sci. (Lond.), 112(4), 241–250 (2007).
10. Hyland, L. et al. "Central ghrelin receptor stimulation modulates sex motivation in male rats in a site dependent manner." Horm. Behav., 97, 56–66 (2018).
11. Huang, H. J. et al. "The protective effects of Ghrelin/GHSR on hippocampal neurogenesis in CUMS mice." Neuropharmacology (2019).
12. Korbonits, M., & Grossman, A. B. "Growth Hormone-Releasing Peptide and Its Analogues." Trends in Endocrinology & Metabolism, 6(2), 43–49 (1995).