Description
GHRP-2 is a synthetic hexapeptide growth hormone secretagogue, also known by its pharmaceutical name pralmorelin, developed as a second-generation GHSR-1a agonist with improved receptor selectivity relative to its predecessor GHRP-6. It activates the growth hormone secretagogue receptor type 1a (GHSR-1a) through Gq/11 protein coupling — triggering phospholipase C activation, IP3 and DAG generation, and intracellular calcium mobilization that drives GH-containing secretory granule exocytosis from anterior pituitary somatotrophs. Researchers studying GH axis signaling and ghrelin receptor pharmacology use GHRP-2 specifically when cleaner GHSR-1a activation — with reduced orexigenic and cortisol co-stimulation confounds — is the experimental priority.
Key Characteristics
- Higher GHSR-1a selectivity than GHRP-6 — binding studies show >1000-fold selectivity for GHSR-1a over opioid, melanocortin, and neuropeptide Y receptors, making it the preferred tool when the study requires isolating GH pulse dynamics from broader ghrelin receptor biology
- ACTH and cortisol co-stimulation is documented at research-relevant concentrations — this off-target activity is more pronounced than Ipamorelin but less than GHRP-6, positioning GHRP-2 in the middle of the GHRP selectivity spectrum and making ACTH pathway co-activation a variable researchers must account for in study design
- Orexigenic signaling is weaker than GHRP-6, where GHRP-6 produces strong hypothalamic NPY/AgRP-mediated appetite signaling. GHRP-2’s reduced activity at peripheral ghrelin pathways makes it more appropriate for GH-focused models, where food intake variability would confound results
- Synergizes with GHRH analogs through mechanistically independent receptor systems — combining GHRP-2 with CJC-1295 or Sermorelin activates both GHSR-1a and GHRHR simultaneously, with documented additive GH pulse amplitude that neither compound produces alone
- Approved in Japan as pralmorelin for GH deficiency diagnostic testing — one of the few GHRPs with any regulatory approval history, which has generated a clinical pharmacokinetic and safety data set that informs research design
Handling and Storage
Store as lyophilized powder under refrigeration, away from heat, moisture, and light. Reconstitute immediately before use and avoid repeated freeze-thaw cycles to maintain GHSR-1a binding activity across experimental batches.
FAQs
What is GHRP-2?
GHRP-2 (pralmorelin) is a synthetic hexapeptide GHSR-1a agonist that stimulates GH release from anterior pituitary somatotrophs through Gq/11-mediated phospholipase C activation and intracellular calcium mobilization. It is studied as a second-generation growth hormone secretagogue with higher GHSR-1a selectivity than GHRP-6 and lower orexigenic activity, making it useful in GH axis research models where appetite and cortisol confounds need to be minimized.
How does GHRP-2 differ from Ipamorelin in GHSR-1a research?
Both activate GHSR-1a through the same Gq/11 calcium cascade, but Ipamorelin is significantly more selective — it does not meaningfully activate ACTH or cortisol pathways at research-relevant concentrations, while GHRP-2 does produce measurable ACTH co-stimulation. Researchers select Ipamorelin when GHSR-1a isolation is the priority and GHRP-2 when studying how ghrelin receptor activation interacts with the broader hypothalamic-pituitary axis, including its ACTH-stimulating properties.
How does GHRP-2 compare to GHRP-6 in research selectivity?
GHRP-6 produces stronger orexigenic signaling through hypothalamic NPY/AgRP pathways and more pronounced cortisol and prolactin co-stimulation. GHRP-2 offers higher GHSR-1a selectivity with a cleaner GH pulse profile, making it preferable when the research question centers on somatotroph biology rather than the full breadth of ghrelin receptor pharmacology. GHRP-6 remains the appropriate choice when orexigenic signaling or broader ghrelin pathway activity is specifically what the study is designed to examine.
