GHRP-2 vs IGF-2

Synthetic hexapeptide that stimulates pulsatile growth hormone release from the anterior pituitary by acting on the ghrelin receptor (GHSR-1a). Commonly stacked with GHRH analogs such as CJC-1295 or Sermorelin to amplify GH output synergistically.

GHRP-2 (growth hormone-releasing peptide-2; pralmorelin; KP-102) is a synthetic hexapeptide (D-Ala-D-2Nal-Ala-Trp-D-Phe-Lys-NH2) and potent ghrelin receptor (GHS-R1a) agonist developed as a GH secretagogue with established efficacy in stimulating pulsatile GH release from pituitary somatotrophs, characterized by potent GH stimulation alongside non-selective co-stimulation of cortisol and prolactin secretion. As a first-generation GHRP, GHRP-2 achieves its GH-secretory effect through direct GHS-R1a agonism with amplification by endogenous GHRH; it is distinguished from later selective GHRPs such as ipamorelin by its non-selective endocrine profile, and synergistic GH stimulation is observed when combined with GHRH analogs in diagnostic protocols. GHRP-2 has been validated as a diagnostic agent for the GHRP-2 stimulation test used in Japan to assess GH secretion capacity in adults with suspected hypopituitarism or post-surgical pituitary dysfunction, with published human clinical data supporting its reliability as a GH stimulation tool in endocrine diagnostic practice. GHRP-2 has no FDA approval for any therapeutic or diagnostic indication in the United States; it is used diagnostically in Japan and as a research compound elsewhere, with no approved indication for GH enhancement, performance, or anti-aging applications, and its non-selective endocrine stimulation profile represents a relevant consideration versus more selective GH secretagogues. GHRP-2 dosage in research contexts: doses of 100–300 mcg per subcutaneous injection are documented across research protocols, typically administered 2–3 times daily. Co-administration with a GHRH analog (such as CJC-1295 or sermorelin) produces synergistic GH release and is studied in combination protocols for this reason. Administration is by subcutaneous injection following reconstitution with bacteriostatic water. GHRP-2 vs GHRP-6 vs ipamorelin: GHRP-2 produces potent GH release but with co-stimulation of cortisol and prolactin, similar to GHRP-6. The key distinguishing feature of GHRP-6 is stronger appetite stimulation (ghrelin-like effect); GHRP-2 produces less appetite stimulation with comparable or slightly greater GH output per dose. Both are non-selective compared to ipamorelin, which was developed specifically to achieve GH stimulation without the cortisol and prolactin co-elevation that characterizes first-generation GHRPs. For research contexts prioritizing GH selectivity, ipamorelin is generally preferred; GHRP-2 is used where its diagnostic validation and potent GH stimulation profile are the research objectives.

Binds IGF-1R and insulin receptor variant A; promotes anabolic signaling in muscle and fat; activates PI3K/Akt/mTOR pathway; different receptor binding profile than IGF-1

Insulin-like growth factor 2 (IGF-2) is a naturally occurring peptide growth factor structurally homologous to IGF-1 that plays a central role in embryonic development and remains expressed in adult skeletal muscle, where it functions as an autocrine regulator of myoblast differentiation and myocyte maturation downstream of MyoD activation. IGF-2 binds both the IGF-1 receptor (IGF-1R), which mediates PI3K/Akt anabolic signaling, and the mannose-6-phosphate/IGF-2 receptor (M6P/IGF-2R), which targets bound ligand for lysosomal degradation rather than intracellular signal transduction; the balance between these receptor populations influences net downstream anabolic signaling. Preclinical and cell biology research demonstrates that autocrine IGF-2 signaling through IGF-1R is required for normal myocyte maturation, and that TGF-β-mediated suppression of IGF-2 autocrine pathways impairs skeletal muscle differentiation, establishing IGF-2 as a functionally important endogenous anabolic signal in muscle regeneration. IGF-2 has no FDA-approved applications in performance enhancement or muscle anabolism; exogenous administration as a research compound is investigational and no human clinical trials have established safety or efficacy for these uses.