IGF-1 LR3 vs Ipamorelin

IGF-1 LR3

IGF-1 LR3 (Long R3 Insulin-like Growth Factor-1) is a modified 83-amino acid analogue of human IGF-1 in which glutamic acid at position 3 is replaced with arginine, and a 13-amino acid N-terminal extension peptide is added. These modifications significantly reduce binding to IGF-binding proteins (IGFBPs), resulting in a much higher proportion of free, bioactive peptide in circulation compared to native IGF-1. The mechanism of action involves binding to the IGF-1 receptor (IGF-1R), a tyrosine kinase receptor that activates the PI3K/Akt and MAPK/ERK signaling cascades to promote cell proliferation, differentiation, and survival. Research demonstrates that IGF-1 LR3 has approximately 2-3 times the potency of native IGF-1 in cell culture proliferation assays due to its reduced IGFBP sequestration (Francis et al., Journal of Molecular Endocrinology, 1992). In muscle biology research, IGF-1 signaling promotes satellite cell activation and myofiber hypertrophy while simultaneously inhibiting myostatin-mediated atrophy pathways. Studies also indicate IGF-1 LR3 promotes both hyperplasia (new cell formation) and hypertrophy (cell enlargement), distinguishing it from GH secretagogues that primarily drive hypertrophy. Compared to native IGF-1, LR3 has a significantly extended half-life of approximately 20-30 hours versus 12-15 minutes, making it substantially more practical for research applications. Store lyophilized powder at -20C; reconstitute with 0.1M acetic acid or bacteriostatic water and refrigerate at 2-8C, using reconstituted material within 30 days. IGF-1 LR3 is studied by cell biology laboratories, muscle physiology researchers, cancer biology departments investigating IGF-1R signaling, and metabolic research institutions.

Ipamorelin

Ipamorelin is a synthetic pentapeptide (Aib-His-D-2Nal-D-Phe-Lys-NH2) that acts as a selective agonist of the growth hormone secretagogue receptor (GHS-R1a/ghrelin receptor). Its mechanism involves binding the ghrelin receptor on anterior pituitary somatotrophs to trigger calcium influx and GH granule exocytosis. What distinguishes ipamorelin from earlier ghrelin mimetics is its remarkable selectivity: clinical studies by Raun et al. (European Journal of Endocrinology, 1998) demonstrated that ipamorelin stimulates GH release in a concentration-dependent manner without significantly affecting cortisol, prolactin, FSH, LH, or TSH levels, even at high concentrations. This selectivity profile makes it one of the cleanest GH secretagogues available for research. In bone metabolism research, Anderson et al. (Bone, 2001) showed that ipamorelin use in ovariectomized rat models increased bone mineral content and bone formation markers, suggesting anabolic effects on skeletal tissue independent of IGF-1 elevation. The peptide has also been studied in post-operative recovery models, where it demonstrated prokinetic effects on gastric motility. Compared to GHRP-6 and GHRP-2, which also activate the ghrelin receptor but additionally stimulate appetite and affect cortisol/prolactin levels, ipamorelin provides a more isolated GH response. Store lyophilized powder at -20C; reconstitute with bacteriostatic water and refrigerate at 2-8C for up to 28 days. Ipamorelin is investigated by endocrinology labs, bone metabolism research centers, orthopedic research departments, and gastrointestinal motility researchers.

Frequently Asked Questions