Overview
GHRP-4 has a very short plasma half-life of approximately 15-30 minutes due to rapid proteolytic degradation. Peak GH secretion is observed within 15-30 minutes post-injection. The pulsatile nature of induced GH secretion mimics endogenous physiological patterns, preserving pituitary feedback sensitivity and avoiding the downregulation associated with continuous GH infusion. At the tissue level, elevated GH increases lipolysis via hormone-sensitive lipase activation and upregulates IGF-1 receptor signaling in skeletal muscle, promoting nitrogen retention and satellite cell proliferation. Concurrent cortisol and prolactin elevation — mediated by GHS-R1a expression on corticotrophs and lactotrophs — represent key off-target effects that may attenuate the anabolic benefit at supraphysiological doses.
Proposed mechanism
GHRP-4 acts as an agonist at the growth hormone secretagogue receptor type 1a (GHS-R1a), a G-protein coupled receptor predominantly expressed on somatotroph cells in the anterior pituitary. Binding to GHS-R1a triggers a Gq/11-mediated intracellular signaling cascade that elevates intracellular calcium via phospholipase C and IP3, ultimately causing pulsatile release of endogenous growth hormone. This mechanism is distinct from GHRH, allowing synergistic GH stimulation when both pathways are activated simultaneously.
What the evidence supports
Evidence rests primarily on self-reported experience. Controlled studies are lacking.
Graded Anecdotal
Case reports, clinician notes, and user-reported outcomes. Recorded for completeness and labelled plainly so it is never mistaken for data.
Key citations
Representative primary sources, including results that did not favour the compound.
- [1]
Synthetic peptides as growth hormone secretagogues
· Endocrine Reviews, Bowers CY · 1996
- [2]
Ghrelin: a growth-hormone-releasing acylated peptide from stomach
· Nature, Kojima M et al., doi:10.1038/45230 · 1999
- [3]
The growth hormone secretagogue receptor
· Vitamins and Hormones, Chollet C et al. · 2007
- [4]
Growth hormone secretagogues: mechanisms of action and use in clinical practice
· Reviews in Endocrine and Metabolic Disorders · 2010
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.