Overview
Following subcutaneous or intramuscular administration, GHRP-3 has a very short plasma half-life (~15-20 minutes) due to rapid proteolytic degradation. Despite this, it generates a GH pulse lasting approximately 90-180 minutes. Peak GH concentrations typically occur 15-30 minutes post-injection. Elevated GH stimulates hepatic IGF-1 synthesis over 4-8 hours. Chronic administration (weeks to months) leads to sustained elevation of mean 24-hour GH and IGF-1 levels, driving downstream anabolic, lipolytic, and tissue-repair pathways. Importantly, GHRP-3 preserves the pulsatile physiological pattern of GH secretion rather than producing the supraphysiological continuous elevation seen with exogenous recombinant GH.
Proposed mechanism
GHRP-3 binds to the growth hormone secretagogue receptor type 1a (GHS-R1a), a G-protein coupled receptor expressed predominantly in the hypothalamus and pituitary gland, triggering intracellular signaling cascades involving phospholipase C, IP3, and intracellular calcium mobilization that promote somatotroph cell GH release. It also acts at the hypothalamic level to suppress somatostatin (growth hormone inhibiting hormone) tone and amplify GHRH-mediated signaling, resulting in synergistic GH pulse augmentation. Unlike ghrelin itself, GHRP-3 is more selective for GH release with comparatively reduced effects on appetite and cortisol stimulation relative to earlier-generation GHRPs.
What the evidence supports
Most data comes from preclinical animal studies. Human clinical trial evidence is limited or absent.
Graded Animal
Evidence drawn from in vivo animal models or in vitro systems. Mechanistically informative; translation to humans is unproven.
Key citations
Representative primary sources, including results that did not favour the compound.
- [1]
Growth hormone-releasing peptides and their analogs
· Frontiers in Neuroendocrinology, 19(1):47-72 — Bowers CY · 1998
- [2]
Ghrelin: much more than a hunger hormone
· Current Opinion in Clinical Nutrition & Metabolic Care, 15(5):428-434 · 2012
- [3]
The GH secretagogue receptor: its intracellular signaling and regulation
· Trends in Endocrinology and Metabolism, 18(4):128-135 · 2007
- [4]
Growth hormone secretagogues: mechanism of action and use in cardiac cachexia
· Endocrine, 22(1):65-70 · 2003
Citation records in this build are illustrative placeholders for the design.
Reference information for research purposes. Not medical advice, and not a recommendation to use any compound. Many entries describe substances that are not approved for human use.