Growth hormone releasing hexapeptide, or GHRP-6, belongs to a group of synthetic peptides developed with the potential to stimulate the secretion and regulate growth hormone levels. GHRP-6 is a small, low molecular weight, synthetic peptide, which has been researched for its potential in growth hormone stimulation. (2)
Initially, growth hormone releasing peptides (GHRP) were developed with the intention of mimicing the mechanism of action of growth hormone releasing hormones (GHRHs). When GHRH was first isolated in 1984, scientists hypothesized that these compounds might operate diversely; with GHRPs exhibiting an apparent affinity to bind with ghrelin receptors (3). Researchers suspected GHRPs, like the endogenously found hormone ghrelin, appear to govern action via hypothalamic stimulation and may have the potential to influence various functions, including metabolism and nutrient absorption.
Research was conducted to determine if GHRP-6 requires endogenous GHRH presence in order to exert its potential. In one clinical study (4), nine subjects between 20 and 30 years were either given GHRH antagonist or saline, followed by GHRP-6 after 20 minutes. Blood samples were collected incrementally for the next few hours and the concentrations of growth hormones was measured. Following the study, the researchers suggested that HGH levels were lower in subjects who were presented with GHRH antagonist. They posited further that endogenous GHRH may be necessary for GHRP-6 to exert potential action.
While the mechanism of GHRP-6 remains under study (4), research trials have suggested that GHRPs may act by binding with two receptors, GHS-R1a, and CD36. In addition to HGH release, GHRP-6 also appears to have the potential to reduce cellular death through binding with CD36 receptors, possibly stimulating prosurvival cellular pathways (2). This remains under investigation.
Earlier it was hypothesized that GHRP-6 may work through a double mechanism, producing possible activities at the pituitary gland and hypothalamus. In a study to investigate this mechanism of action (5), 23 subjects were studied, 12 with hypothalamus-pituitary disconnection and 11 control. Each subject was either presented GHRH, GHRP-6, or a combination of both. After presentation, the HGH levels were measured in all 23 subjects. In the control group, the highest levels of HGH were found in subjects given both GHRH and GHRP-6, followed by GHRP-6 subjects, and lastly the GHRH subjects. These results appeared to be converse in the subjects with hypothalamic pituitary disconnection, with the least levels of HGH reported in subjects presented with both GHRP-6 and GHRH. The GHRH subjects appeared to have the same levels of HGH as controls, whereas the HGH levels were reportedly reduced in subjects given GHRP-6 alone. Two hypotheses were extended by the researchers from this study – first, GHRP-6 action may be induced primarily in the presence of GHRH and second, that GHRP-6 may act on hypothalamic pituitary axis in order to produce its potential.
Research and Clinical Studies
GHRP-6 Peptide and Hypothyroidism
Hypothyroidism is typically characterized by reduced levels of growth hormone secretion in the body. The main aim of this study (7) was to determine whether GHRP-6, a supposed HGH release stimulating agent, might be used to mitigate HGH level reduction. Subjects presenting hypothyroidism were randomly given three concentrations of GHRH, and GHRP-6. Following the completion of the study, it was observed by the researchers that the subjects presented with GHRP-6 alone and with combination of GHRP-6 and GHRH appeared to induce significantly higher levels of growth hormones than GHRH alone. The possible reasoning behind this is that GHRP-6 may differ from GHRH, with the potential as a functional antagonist of somatostatin at the pituitary level, which may be potentially why GHRP-6 may exert possibly increased action on hypothyroidism compared to GHRH.
GHRP-6 Peptide and Cortisol Hormone Release
In this clinical study (8), the action of GHRP-6 peptide on the hormone release and sleep electroencephalogram (EEG) during the night time was studied. Male subjects were presented with either the GHRP-6 peptide or a placebo. After the peptide, it was observed by the researchers that GHRP-6 appeared to induce higher secretion of both growth hormones and cortisol (ACTH) hormones. Throughout the night, particularly during the first half, cortisol hormone release and stage 2 sleep appeared to be enhanced, while the other sleep EEG variables remained apparently unchanged. This study suggested that not only may GHRP-6 possibly induce growth hormone release, but it also may act on the hypothalamus and pituitary gland axis, mobilizing cortisol hormone release.
GHRP-6 Peptide and Organ Function
The main goal of this study (9) was to determine the action of GHRP-6, either alone or in combination with epidermal growth factor (EGF), on multiple organ failure. The first iteration of this study was conducted on the experimental models of injury and multiple organ failure, while the second iteration of the study was conducted on rat intestine and colonic cancer cells. The first study suggested that GHRP-6 may impact the gut epithelial cells and increase cell migration by three times a control rate, without an apparent impact on cell proliferation. In the second model, multiple organ failure caused severe hepatic and intestinal damage and lipid peroxidation. Presentation of GHRP-6 appeared to reduce these damages by a reported 50-85%, with additional activity when GHRP-6 was presented in combination with EGF.
GHRP-6 Peptide and GI transit
The main aim of this study (10) was to investigate the potential of GHRP-6 on delayed gastrointestinal (GI) transit induced by diabetes. An experimental mouse model, with alloxan-induced diabetes, was used for this study. Alloxan is a synthetic uric acid derivative compound, commonly used for experiments, which induces diabetes upon presentation. (14) All experimental mice were presented with GHRP-6 at interval concentrations. Based on the study analysis, researchers posited that the diabetes appeared to reduce the levels of gastric emptying (GE), intestinal transit (IT) and colonic transit (CT) in mice. Upon GHRP-6 presentation, the levels of GE and IT reportedly improved, with no reported fluctuation in CT levels.
GHRP-6 peptide is available for research and laboratory purposes only. Please review and adhere to our Terms and Conditions before ordering.
1. Hintz, Raymond L. “Growth hormone: uses and abuses.” BMJ (Clinical research ed.) vol. 328,7445 (2004): 907-8. doi:10.1136/bmj.328.7445.907. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC390151/
2. Berlanga-Acosta, Jorge et al. “Synthetic Growth Hormone-Releasing Peptides (GHRPs): A Historical Appraisal of the Evidences Supporting Their Cytoprotective Effects.” Clinical Medicine Insights. Cardiology vol. 11 1179546817694558. 2 Mar. 2017, doi:10.1177/1179546817694558. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5392015/
3. Bowers, C.Y., et al (2012). Ghrelin: A history of its discovery. In Ghrelin in Health and Disaeas (pp. 1-35), Human press Inc. https://mayoclinic.pure.elsevier.com/en/publications/ghrelin-a-history-of-its-discovery
4. Naushira Pandya, Roberta DeMott-Friberg, Cyril Y. Bowers, Ariel L. Barkan, Craig A. Jaffe, Growth Hormone (GH)-Releasing Peptide-6 Requires Endogenous Hypothalamic GH-Releasing Hormone for Maximal GH Stimulation, The Journal of Clinical Endocrinology & Metabolism, Volume 83, Issue 4, 1 April 1998, Pages 1186–1189. https://academic.oup.com/jcem/article/83/4/1186/2865313
5. Popovic V, Damjanovic S, Micic D, Djurovic M, Dieguez C, Casanueva FF. Blocked growth hormone-releasing peptide (GHRP-6)-induced GH secretion and absence of the synergic action of GHRP-6 plus GH-releasing hormone in patients with hypothalamopituitary disconnection: evidence that GHRP-6 main action is exerted at the hypothalamic level. J Clin Endocrinol Metab. 1995 Mar;80(3):942-7. doi: 10.1210/jcem.80.3.7883854. PMID: 7883854. https://pubmed.ncbi.nlm.nih.gov/7883854/
6. Bellone J, Ghizzoni L, Aimaretti G, Volta C, Boghen MF, Bernasconi S, Ghigo E. Growth hormone-releasing effect of oral growth hormone-releasing peptide 6 (GHRP-6) administration in children with short stature. Eur J Endocrinol. 1995 Oct;133(4):425-9. doi: 10.1530/eje.0.1330425. https://pubmed.ncbi.nlm.nih.gov/7581965/
7. Pimentel-Filho FR, Ramos-Dias JC, Ninno FB, Façanha CF, Liberman B, Lengyel AM. Growth hormone responses to GH-releasing peptide (GHRP-6) in hypothyroidism. Clin Endocrinol (Oxf). 1997 Mar;46(3):295-300. doi: 10.1046/j.1365-2265.1997.1270942.x. https://pubmed.ncbi.nlm.nih.gov/9156038/
8. Frieboes RM, Murck H, Maier P, Schier T, Holsboer F, Steiger A. Growth hormone-releasing peptide-6 stimulates sleep, growth hormone, ACTH and cortisol release in normal man. Neuroendocrinology. 1995 May;61(5):584-9. https://doi.org/10.1159/000126883
9. Cibrián D, Ajamieh H, Berlanga J, León OS, Alba JS, Kim MJ, Marchbank T, Boyle JJ, Freyre F, Garcia Del Barco D, Lopez-Saura P, Guillen G, Ghosh S, Goodlad RA, Playford RJ. Use of growth-hormone-releasing peptide-6 (GHRP-6) for the prevention of multiple organ failure. Clin Sci (Lond). 2006 May;110(5):563-73. https://pubmed.ncbi.nlm.nih.gov/16417467/
10. Zheng, Q., Qiu, W. C., Yan, J., Wang, W. G., Yu, S., Wang, Z. G., & Ai, K. X. (2008). Prokinetic effects of a ghrelin receptor agonist GHRP-6 in diabetic mice. World journal of gastroenterology, 14(30), 4795–4799. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2739343/
11. Cabrales A, Gil J, Fernández E, Valenzuela C, Hernández F, García I, Hernández A, Besada V, Reyes O, Padrón G, Berlanga J, Guillén G, González LJ. Pharmacokinetic study of Growth Hormone-Releasing Peptide 6 (GHRP-6) in nine male healthy volunteers. Eur J Pharm Sci. 2013 Jan 23;48(1-2):40-6. https://pubmed.ncbi.nlm.nih.gov/23099431/
12. Frieboes RM, Murck H, Antonijevic IA, Steiger A. Effects of growth hormone-releasing peptide-6 on the nocturnal secretion of GH, ACTH and cortisol and on the sleep EEG in man: role of routes of administration. J Neuroendocrinol. 1999 Jun;11(6):473-8. https://pubmed.ncbi.nlm.nih.gov/10336729/
13. 2021 WADA Prohibited list. https://www.wada-ama.org/en/
14. Kristina Szabadfi, et al., Therapeutic Areas I: Central Nervous System, Pain, Metabolic Syndrome, Urology, Gastrointestinal and Cardiovascular, in Comprehensive Medicinal Chemistry II, 2007. https://www.sciencedirect.com/topics/medicine-and-dentistry/alloxan
15. HGH Side effects and other hazards. https://www.webmd.com/fitness-exercise/human-growth-hormone
Synonyms/Aliases: GHRP-6, Growth Hormone-Releasing Peptide 6, Growth Hormone-Releasing hexapeptide
NOTE: These products are intended for laboratory research use only. GHRP-6 for sale is not intended for personal use. Please review and adhere to our Terms and Conditions before ordering.
Dr. Marinov (MD, Ph.D.) is a researcher and chief assistant professor in Preventative Medicine & Public Health. Prior to his professorship, Dr. Marinov practiced preventative, evidence-based medicine with an emphasis on Nutrition and Dietetics. He is widely published in international peer-reviewed scientific journals and specializes in peptide therapy research.