Description
Hexarelin Peptide
Hexarelin is a growth hormone releasing peptide (GHRP) with a potential parallel action to peptide GHRP-6 (1). Hexarelin, also called Examorelin, is a six amino acid-containing synthetic peptide (2). Ghrelin is a natural, 28 amino acid containing peptide that is considered by scientists to incite growth hormone releasing activity. Several synthetic compounds exhibiting potential similar actions to ghrelin activity, including Hexarelin, were developed more than 25 years ago (3). Since then, synthetic studies and research have continued to date to fully examine peptide action and potential.
Overview
A study (4) was conducted on infant and adult rats to understand the mechanism of Hexarelin. In this study, pups aged 10 days old were passively immunized against the natural growth hormone releasing hormone (GHRH) from birth. These pups were then presented Hexarelin twice a day for 3 to 10 days. The peptide reportedly led to an increase in growth hormone levels in the subject plasma. Furthermore, adult male rats underwent the surgical removal of their anterior pituitary tissue (i.e., mediobasal hypothalamus removal.) These operated models were presented Hexarelin twice a day 5 days prior to the surgery. The peptide during this time did not apparently exhibit significant changes in the concentrations of growth hormone, according to research results. However, when these operated rats were presented with GHRH, it appeared to have the potential to induce high levels of growth hormones within 7 days after. After 30 days, both Hexarelin and GHRH appeared to have induced similar rises in the hormone plasma levels. Based on this study, researchers posited that Hexarelin may work via three different mechanisms:
(a) possibly acting on the pituitary gland,
(b) possibly acting via stimulating GHRH release, and
(c) potentially releasing an ‘unknown’ hypothalamic factor that might lead to GH release in plasma.
Analogous to other GHRPs, it is suggested that Hexarelin may stimulate the release of prolactin and adrenocorticotropin (ACTH) hormones. To understand the mechanism of Hexarelin, a clinical study (5) was conducted on seven subjects who were either presented with Hexarelin, corticotropin releasing hormone hCRH, or arginine. All these compounds were either given solo or in combination. Upon analysis, researchers indicated that all three compounds individually appeared to induce increased levels of ACTH hormones, with all three exhibiting similar potential. When given in combination, hCRH and arginine reportedly exhibited synergistic effects, however, combination with Hexarelin exhibited no apparent changes in ACTH release.
Research and Clinical studies
Hexarelin Peptide and Growth Hormone Release
This clinical study (6) was conducted on 12 subjects (six of pubertal age, six of prepubertal age), 12 subjects (22 to 30 years), and 12 elderly subjects (53 to 79 years) to evaluate the GH releasing potential of the peptide. All subjects were either presented with Hexarelin, with GHRH alone, or in combination with arginine. In prepubertal children, the GH levels were reportedly elevated by GHRH + arginine combination, while GH levels were not reported to be raised by Hexarelin alone. On the other hand, Hexarelin appeared to induce higher GH levels than the increased GH levels induced by GHRH alone and GHRH + arginine combination in pubertal and adult subjects. In elderly subjects, Hexarelin reportedly induced higher GH levels in comparison to GHRH, however, the GH levels were apparently lower than GHRH + arginine combination. These results suggest that Hexarelin may potentially elevate GH levels in pubertal and adult subjects. While it might increase GH levels in elderly and prepubertal subjects, there were no reported significant effects.
Hexarelin Peptide and GH1 Cell Lines
The main aim of this study (7) was to determine the potential of Hexarelin on GH1 rat tumor cell line, which may be insensitive towards GHRH. Furthermore, this study monitored the involvement of GHRH in the possible action of Hexarelin on the GH1 rat cells. Hexarelin was presented in both normal control rat cells, and GH1 rat cells. Researchers reported that GHRH appeared to increase GH levels in the control rat cells, it without presenting any apparent effects on GH1 cells. What’s more, when presented with Hexarelin, GHRH appeared to cause no impact on GH release. These results suggest that GHRPs and GHRHs may act on two distinct sites and GHRPs, such as Hexarelin, may have the potential to act on cells that are not sensitive to GHRH effects.
Hexarelin and Cardiovascular Activities
Clinical studies (8) have suggested that the acute presentation of Hexarelin may induce positive inotropic activity in the cardiovascular system. When presented to seven male subjects, the peptide reportedly increased LVEF ejection rate, possibly without affecting blood pressure. When presented to 24 male subjects with coronary artery disease undergoing surgery while under anesthesia, the Hexarelin reportedly exhibited potential to increase cardiac output and increase arterial pressure with no change in heart rate. Furthermore, when presented in ischemic rat hearts, Hexarelin possibly restored the electrophysiological properties of the heart cells and inhibited cell apoptosis, thereby producing positive inotropic activity and potentially promoting heart cell survival (9).
Another study (10) was conducted where Hexarelin was presented daily to male rat hearts that were experimentally induced to undergo myocardial infarction. The results suggested that the peptide had the potential to increased stroke volume and increase cardiac output, while decreasing peripheral resistance.
Hexarelin Peptide and Composition
The main aim of this clinical study (11) was to determine possible fluctuation of gender-based body composition with the growth hormone releasing potential of Hexarelin. This study was conducted on 28 subjects (both male and female) aged between 60 to 81 years. All subjects were presented with Hexarelin, and upon analyzing the blood samples, researchers suggested that the peak growth hormone release appeared to be negatively correlated to fat mass. Increased fat mass may lead to reduction in GH release. Gender reportedly exhibited no significant impact on GH release.
Hexarelin peptide is available for research and laboratory purposes only. Please review and adhere to our Terms and Conditions before ordering.
References:
1. Giustina A, Bonfanti C, Licini M, Ragni G, Stefana B. Hexarelin, a novel GHRP-6 analog, stimulates growth hormone (GH) release in a GH-secreting rat cell line (GH1) insensitive to GH-releasing hormone. Regul Pept. 1997 May 14;70(1):49-54. https://pubmed.ncbi.nlm.nih.gov/9250581/
2. National Center for Biotechnology Information (2021). PubChem Compound Summary for CID 6918297, Examorelin. Retrieved August 19, 2021 from https://pubchem.ncbi.nlm.nih.gov/compound/Examorelin
3. Fabio Broglio et al, Ghrelin: Much more than a natural growth hormone secretagogue. Division of Endocrinology and Metabolism, Department of Internal Medicine; Division of Pathological Anatomy, Department of Biomedical Sciences and Oncology https://www.ima.org.il/FilesUploadPublic/IMAJ/0/56/28152.pdf
4. Torsello A, Grilli R, Luoni M, Guidi M, Ghigo MC, Wehrenberg WB, Deghenghi R, Müller EE, Locatelli V. Mechanism of action of Hexarelin. I. Growth hormone-releasing activity in the rat. Eur J Endocrinol. 1996 Oct;135(4):481-8. https://pubmed.ncbi.nlm.nih.gov/8921832/
5. Arvat E, Maccagno B, Ramunni J, Di Vito L, Broglio F, Deghenghi R, Camanni F, Ghigo E. Hexarelin, a synthetic growth-hormone releasing peptide, shows no interaction with corticotropin-releasing hormone and vasopressin on adrenocorticotropin and cortisol secretion in humans. Neuroendocrinology. 1997 Dec;66(6):432-8. https://pubmed.ncbi.nlm.nih.gov/9430449/
6. Bellone J, Bartolotta E, Sgattoni C, Aimaretti G, Arvat E, Bellone S, Deghenghi R, Ghigo E. Hexarelin, a synthetic GH-releasing peptide, is a powerful stimulus of GH secretion in pubertal children and in adults but not in prepubertal children and in elderly subjects. J Endocrinol Invest. 1998 Sep;21(8):494-500. https://pubmed.ncbi.nlm.nih.gov/9801989/
7. Giustina A, Bonfanti C, Licini M, Ragni G, Stefana B. Hexarelin, a novel GHRP-6 analog, stimulates growth hormone (GH) release in a GH-secreting rat cell line (GH1) insensitive to GH-releasing hormone. Regul Pept. 1997 May 14;70(1):49-54. https://pubmed.ncbi.nlm.nih.gov/9250581/
8. Mao, Yuanjie et al. “The cardiovascular action of hexarelin.” Journal of geriatric cardiology : JGC vol. 11,3 (2014): 253-8. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4178518/
9. Ma Y, Zhang L, Edwards JN, Launikonis BS, Chen C. Growth hormone secretagogues protect mouse cardiomyocytes from in vitro ischemia/reperfusion injury through regulation of intracellular calcium. PLoS One. 2012;7(4):e35265. https://pubmed.ncbi.nlm.nih.gov/22493744/
10. Tivesten A, Bollano E, Caidahl K, Kujacic V, Sun XY, Hedner T, Hjalmarson A, Bengtsson BA, Isgaard J. The growth hormone secretagogue hexarelin improves cardiac function in rats after experimental myocardial infarction. Endocrinology. 2000 Jan;141(1):60-6. https://pubmed.ncbi.nlm.nih.gov/10614623/
11. Rahim A, O’Neill P, Shalet SM. The effect of body composition on hexarelin-induced growth hormone release in normal elderly subjects. Clin Endocrinol (Oxf). 1998 Nov;49(5):659-64. https://pubmed.ncbi.nlm.nih.gov/10197083/
12. Massoud AF, Hindmarsh PC, Matthews DR, Brook CG. The effect of repeated administration of hexarelin, a growth hormone releasing peptide, and growth hormone releasing hormone on growth hormone responsivity. Clin Endocrinol (Oxf). 1996 May;44(5):555-62. https://pubmed.ncbi.nlm.nih.gov/8762732/
13. Imbimbo, B.P., Mant, T., Edwards, M. et al. Growth hormone-releasing activity of hexarelin in humans. Eur J Clin Pharmacol 46, 421–425 (1994). https://doi.org/10.1007/BF00191904
14. 2021 WADA Prohibited list. https://www.wada-ama.org/en/
Hexarelin Research
Get more research details by reading our latest Hexarelin Review blog post.
Synonyms/Aliases: Hexarelin, Examorelin
NOTE: These products are intended for laboratory research use only. Hexarelin for sale is not 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.
