Ipamorelin Research
Ipamorelin is a selective pentapeptide ghrelin-receptor (GHS-R) agonist studied in laboratory and in-vitro models as the first highly GH-selective growth-hormone secretagogue. For research use only.
Also known as: NNC 26-0161 · CAS 170851-70-4
Ipamorelin (Aib-His-D-2-Nal-D-Phe-Lys-NH2) is a GHRP-class pentapeptide that activates the growth-hormone secretagogue receptor (GHS-R1a), the ghrelin receptor, on pituitary cells. In experimental models it stimulates GH release with minimal effect on ACTH, cortisol, or prolactin, distinguishing it from earlier GHRPs such as GHRP-6.
Mechanism of Action
Ipamorelin is a synthetic pentapeptide derived from the GHRP-1 scaffold that acts as an agonist at the growth-hormone secretagogue receptor (GHS-R1a), the same Gq-coupled GPCR targeted by endogenous ghrelin. In experimental models, receptor activation drives phospholipase-C signaling, intracellular calcium mobilization, and GH release from pituitary somatotrophs. Its defining characteristic in the research literature is selectivity: in experimental studies, ipamorelin released GH at potency comparable to GHRP-6 but did not meaningfully raise ACTH or cortisol even at doses far above its GH ED50. This makes it a valuable tool peptide for isolating ghrelin-receptor-mediated GH effects from broader neuroendocrine activation.
Research Applications
Ipamorelin is used in laboratory work as a clean, GH-selective GHS-R probe. Reported research areas include gastrointestinal motility, where experimental post-operative ileus models examined ghrelin-receptor-mediated, cholinergic-dependent acceleration of gastric emptying and colonic transit; bone-formation studies in experimental models, including counter-regulation of glucocorticoid-induced bone loss; and characterization of GH pulse selectivity versus ACTH/cortisol/prolactin sparing. It is also employed in receptor cross-talk studies alongside GHRH analogs. All described applications are confined to in-vitro and experimental research and make no human performance or body-composition claims.
Synergy & Stacks (research context)
Because ipamorelin acts through the ghrelin receptor while GHRH analogs (tesamorelin, CJC-1295) act through the distinct GHRH receptor, the two classes are commonly paired in experimental designs to study convergent GH-release pathways. Published experimental and in-vitro observations report that combined GHS-R and GHRH-receptor activation can produce greater GH output than either agonist alone, and ipamorelin's selectivity makes it useful for attributing GH effects specifically to the ghrelin arm. This is presented strictly as research context summarizing laboratory findings on receptor co-activation; it is not a usage guide and carries no implication for human administration.
Applications at a glance
- Selective GHS-R / ghrelin-receptor agonism studies
- Experimental gastrointestinal-motility and post-operative ileus models
- Laboratory bone-formation and glucocorticoid-bone-loss research
- GH-pulse selectivity vs ACTH/cortisol-sparing characterization