Hexarelin

Hexarelin is a synthetic hexapeptide growth hormone secretagogue (GHS) belonging to the GHRP family. It is an analog of GHRP-6 with the sequence His-D-2-Methyl-Trp-Ala-Trp-D-Phe-Lys-NH2.

Development

Developed in the 1990s through structure-activity relationship studies, hexarelin was investigated for its properties as a GHS. Among GHRPs like GHRP-6, GHRP-2, and ipamorelin, hexarelin has been observed in studies to be a potent stimulator of growth hormone release.

Receptor Interactions

Research has shown that hexarelin interacts with the growth hormone secretagogue receptor (GHS-R1a), but also demonstrates activity that is independent of this receptor. Studies in animal models indicated that some of hexarelin's observed effects on cardiac tissue occurred even when GH secretion was blocked or in tissues that do not express GHS-R1a.

Hexarelin's observed activities are understood to occur through two primary receptor targets with distinct signaling mechanisms.

GHS-R1a Receptor Activation

The first mechanism involves binding to the growth hormone secretagogue receptor type 1a (GHS-R1a), the receptor for the endogenous ligand ghrelin. Hexarelin binds to GHS-R1a on pituitary somatotroph cells, initiating a signaling cascade involving Gq proteins, phospholipase C, and intracellular calcium mobilization, which leads to the exocytosis of growth hormone from secretory granules.

Pituitary and Hypothalamic Actions

Like other GHRPs, hexarelin is thought to act at both the pituitary and hypothalamic levels, by directly stimulating somatotrophs and by influencing the release of somatostatin. The subsequent release of GH leads to increased circulating levels of GH and stimulation of IGF-1 production, primarily in the liver.

CD36 Receptor Interaction

The second mechanism involves binding to CD36, a class B scavenger receptor. CD36 is a multifunctional receptor involved in cellular processes such as fatty acid transport, signaling, and angiogenesis. Hexarelin's interaction with CD36 has been shown to activate intracellular signaling pathways including MAPK cascades and PI3K/Akt pathways in laboratory models.

These CD36-mediated activities have been investigated in numerous preclinical studies, particularly in the context of cardiovascular models. Research suggests these activities occur independently of GH secretion, as they have been observed in animal models where the GH axis was suppressed.

Published nonclinical literature relevant to this material's molecular targets and experimental models is listed below for independent review. Findings involving other preparations or experimental systems should not be attributed to this research material.

This material is supplied solely for in vitro and other nonclinical laboratory research. It is not for human or veterinary use, consumption, administration, therapeutic use, or diagnostic use.

Laboratory Handling

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Research Limitations

Published observations involving other preparations, experimental systems, or study populations do not establish the identity, performance, or suitability of this research material for any particular experiment.