Growth Hormone-releasing peptides are synthetic peptides that stimulate the release of growth hormones in animal test subjects. Scientists are yet to understand how they work. They propose a possible dual-site of action on both the pituitary and the hypothalamus.

Studies show that GHRPs may reduce inflammation because of their antioxidant effects, thereby exhibiting cardioprotective and cytoprotective benefits. This review summarizes the similarities and differences between two hexapeptides, namely: Hexarelin and Ghrp-6, their mechanism of action, and effects on the release of growth hormone.

WHAT IS HEXARELIN

Hexarelin is a new synthetic growth hormone-releasing peptide (GHRP), which is a synthetic analog of ghrelin (a 28 amino acid peptide) and is closely related to GHRP-6. However, it is more stable and more potent than ghrelin. It is a 6 amino acid peptide, with the sequence (His-D-2-methyl-Trp-Ala-Trp-D-Phe-Lys-NH2).

Its empirical formula is C₄₇H₅₈N₁₂O₆ and has a molecular weight of 887 g/mol.

MECHANISM OF ACTION

Hexarelin acts through specific receptors at both the pituitary and the hypothalamic level to stimulate growth hormone release in animal test subjects. It is thought to affect the release of the growth hormone through a phospholipid-dependent protein kinase (PKC) signaling. It mimics the action of ghrelin by binding to the growth hormone secretagogue receptor 1a (GHS-R1a). It also binds to and activates the cardiac receptors CD36.

WHAT IS GHRP-6

Growth hormone-releasing peptide-6 is a first-line synthetic hexapeptide and a met-enkephalin derivative that contains a chain of 6 unnatural D amino acids with the sequence (His-D-Trp-Ala-Trp-D-Phe-Lys-NH2).

It was the first hexapeptide studied in animal test subjects and was identified more than a decade ago.

It binds to specific receptors present at the pituitary or hypothalamic level. Studies showed that GHRP-6 receptors are also present in different peripheral tissues such as the heart, adrenal, ovary, testis, lung, and skeletal muscle.

Its empirical formula is C₄₆H₅₆N₁₂O₆ and has a molecular weight of 873 g/mol.

MECHANISM OF ACTION

Studies in animal test subjects show that GHRP-6 stimulates ghrelin which increases the production of growth hormone (GH) by acting at the level of the pituitary or hypothalamus through a specific receptor different from that of the endogenous Growth Hormone-Releasing Hormone (GHRH).

The four important parts of the test subjects that demonstrate the role of GHRP-6 include the pituitary gland, central nervous system, liver, and stomach.

EFFECTS OF HEXARELIN AND GHRP-6

The Growth hormone-releasing peptides hexarelin and GHRP-6 have similar effects as seen in animal research with few variations. They both cause weight loss, lean muscle growth, cardioprotection, improved recovery from injuries, etc.

However, hexarelin is rated better than GHRP-6 because it easily stimulates the secretion of GH, ACTH (adrenocorticotropic hormone), cortisol, and prolactin even during sleep. But plasma glucose, luteinizing hormone, follicle-stimulating hormone, thyroid-stimulating hormone, and insulin-like growth factor-1 are not affected by hexarelin administration. It also doesn’t cause an increase in ghrelin like GHRP-6. Its half-life is longer than that of GHRP-6.

CONCLUSION

The growing interest in GHRPs has evolved in recent times because they are better at increasing plasma GH levels in a physiologically pulsatile manner in animals. So whatever your choice is between hexarelin or GHRP-6, Loti Labs assures you of the highest quality USA-made peptides which are tested through HPLC and mass spectrometry. Buy peptides from us today!

References:

1. Berlanga-Acosta J, Abreu-Cruz A, Herrera DGB, et al. Synthetic Growth Hormone-Releasing Peptides (GHRPs): A Historical Appraisal of the Evidence Supporting Their Cytoprotective Effects. Clin Med Insights Cardiol. 2017;11:1179546817694558. Published 2017 Mar 2. doi:10.1177/1179546817694558

1. Bellone J, Bartolotta E, Sgattoni C, et al. Hexarelin, a synthetic GH-releasing peptide, is a powerful stimulus of GH secretion in pubertal children and adults but not in prepubertal children and elderly subjects. J Endocrinol Invest. 1998;21(8):494–500. doi:10.1007/BF03347334

1. Arvat E, Ramunni J, Bellone J, et al. The GH, prolactin, ACTH, and cortisol responses to Hexarelin, a synthetic hexapeptide, undergo different age-related variations. Eur J Endocrinol. 1997;137(6):635–642. doi:10.1530/eje.0.1370635

1. Settembrini B, Figueroa J, Gallardo M, Chiocchio S. Growth Hormone (GH) but not IGF-I-Secretion is Stimulated in Aged Rats by Chronic Hexarelin and GHRP-6 administration. Endocr Regul. 1998;32(1):17–26.

1. Bresson-Bepoldin L, Dufy-Barbe L. GHRP6-stimulated hormone secretion in somatotrophs: involvement of intracellular and extracellular calcium sources. J Neuroendocrinol. 1996;8(4):309–314. doi:10.1046/j.1365-2826.1996.04608.x