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Browse CatalogFebruary 26, 2025
Growth hormone secretagogues (GHS) are a class of peptides and small molecules that stimulate the secretion of growth hormone (GH) from the anterior pituitary gland. Unlike exogenous growth hormone administration, which bypasses the physiological regulatory mechanisms, secretagogues work by activating the growth hormone secretagogue receptor (GHS-R1a), also known as the ghrelin receptor, to promote pulsatile GH release that more closely mimics the natural secretory pattern. This class of compounds includes synthetic peptides such as growth hormone-releasing peptide-2 (GHRP-2), GHRP-6, hexarelin, and ipamorelin, each exhibiting distinct pharmacological profiles in terms of GH release potency, selectivity, and secondary effects on other hormonal axes.
Growth hormone secretagogues exert their effects through the GHS-R1a receptor, a seven-transmembrane domain G-protein-coupled receptor that signals through the Gq/11 pathway, leading to intracellular calcium mobilization and subsequent GH release from somatotroph cells. The GHS-R1a receptor is expressed not only in the pituitary but also in the hypothalamus, hippocampus, and peripheral tissues, suggesting that GHS peptides may have biological effects beyond GH secretion. Research has shown that different GHS peptides exhibit varying degrees of receptor selectivity. For example, ipamorelin demonstrates high selectivity for GH release with minimal effects on cortisol and prolactin, while GHRP-6 and GHRP-2 can stimulate cortisol and prolactin release at higher doses, likely through interactions with additional receptor systems.
Research with growth hormone secretagogue peptides spans multiple disciplines including endocrinology, metabolism, aging biology, and musculoskeletal science. Preclinical studies have investigated the potential roles of GHS peptides in promoting nitrogen retention, influencing body composition, modulating sleep architecture, and affecting appetite regulation through ghrelin-related pathways. The pulsatile GH release pattern induced by secretagogues, as opposed to the continuous elevation from exogenous GH, is of particular interest to researchers studying the physiological significance of GH pulse dynamics. Researchers working with GHS peptides should be aware that these compounds are regulated substances in many jurisdictions and are strictly for laboratory research use, requiring appropriate institutional approvals and compliance with applicable regulations.