GHRP-6

Mechanism (as reported)

A study in hypothyroidism reported that the mechanism of GHRP-6 is unknown but noted evidence consistent with action as a functional somatostatin antagonist at the pituitary level; the study investigated GH responses after GHRP-6, GHRH, and combined administration in patients and controls (PMID(s): 9156038). A preclinical study on GHRP-6 hydrogel reported that treatment enhanced survival of renal tubular epithelial cells in an ischemic microenvironment by activating the mTOR-P70 pathway (PMID(s): 41327290).

Key findings (each cites a source)

• A study reported that a self-assembling GHRP-6 peptide hydrogel was designed to reprogram metabolism of renal tubular epithelial cells (TECs) and investigated effects in a mouse model of acute kidney injury, including metabolomic findings and enhanced TEC survival associated with activation of the mTOR-P70 pathway. [PMID 41327290]
• A study investigated GHRP-6 in the diagnosis of GH deficiency by measuring GH responses to i.v. administered GHRP-6 in children and adults with GH deficiency, and reported that GH response overlap occurred between groups but that pituitary stalk transection showed almost complete blockade of GH response to GHRP-6 (and also to GHRH plus GHRP-6). [PMID 8887178]
• A study reported that GHRP-6 attenuated pulmonary damages in mouse models of acute lung injury induced by LPS and/or ZYM plus PAF, including reported reductions in neutrophilic alveolitis, improvements in lung compliance failure and alveolar-capillary permeability, and reduced interleukin-1 beta serum levels in the acute scenario. [PMID 41534456]
• A study reported that in the chronic scenario of the same lung injury investigation, GHRP-6 preserved lung parenchymal integrity and was associated with meager collagen accumulation. [PMID 41534456]
• A study reported that in vitro, addition of GHRP-6 increased the rate of cell migration in intestinal epithelial (IEC-6) and human colonic cancer (HT29) cells without increasing proliferation (as assessed by [3H]thymidine incorporation). [PMID 16417467]
• A study reported that in vivo, GHRP-6 (alone or combined with EGF) reduced injury markers in hepatic and intestinal damage, including reported reductions in neutrophilic infiltration and lipid peroxidation in a multiple organ failure (MOF) in vivo model using hepatic vessel ischemia/reperfusion protocols. [PMID 16417467]
• A study (review-style overview) described GHRPs (growth hormone-releasing peptides) and non-peptides as GH secretagogues with a chemistry ranging from small synthetic peptides to peptidomimetics, reported to release GH in animals and humans via dual and complementary action on hypothalamus and pituitary, and discussed evidence and investigative interest in their physiological regulation. [PMID 9893708]
• A study described GHRP-6 (and related peptides) and reported that UHPLC-MS/MS methods were developed and validated for quantifying GHRP-6 in plasma, skin, and dissolving polymeric microneedle (MN) formulations, with method validation including detection limits and assessment of precision/accuracy and stability; applicability was demonstrated for transdermal delivery using GHRP-6-loaded MN patches applied to pig skin. [PMID 34215058]
• A synthesis study reported the preparation of N-aminoimidazolidin-2-one (Aid) peptidomimetics, including eight GHRP-6 analogues, and stated that the Aid scaffold was designed to rigidify the peptide backbone as an aza variant of a Freidinger-Veber lactam. [PMID 24697286]
• A clinical study in hypothyroidism investigated GH responses to GHRP-6, GHRH, and their combination, and reported that hypothyroid patients had markedly lower peak GH values after GHRH compared to controls, but showed significantly higher GH release after GHRP-6 than that obtained with GHRH; it also reported that when GHRP-6 was associated with GHRH, a significant increase in GH response was observed in these patients. [PMID 9156038]