Peptide reference
IGF-1 LR3
Long R3 IGF-1 ·Long Arg3 IGF-1 ·LongR3-IGF-I ·LR3-IGF-1
What cited sources report about IGF-1 LR3
Long R3 IGF-1 (IGF-1 LR3) is a recombinant 83-amino-acid analog of human insulin-like growth factor-1 carrying a 13-residue N-terminal extension (MFPAMPLSSLFVN) and an arginine substitution for glutamate at position 3 of the native IGF-1 sequence. The modifications were originally engineered at the University of Adelaide to reduce affinity for IGF-binding proteins and increase potency in cell-culture applications. IGF-1 LR3 has no FDA-approved indication and no marketing authorization in any major jurisdiction; it is sold as a research reagent and is also distributed in the gray-market peptide trade for off-label bodybuilding use. The summaries below report what individual cited sources state; this page does not assert claims beyond what those sources report.
White et al. (2024/2025) — American Journal of Physiology — Endocrinology and Metabolism
A study from the University of Colorado and University of Arizona used a placental-insufficiency fetal-sheep model and reported that direct infusion of IGF-1 LR3 (1.17 ± 0.12 μg·kg⁻¹·h⁻¹) into growth-restricted fetal circulation for one week did not increase fetal body weight or improve glucose-stimulated insulin secretion compared with vehicle. The authors observed that branched-chain amino-acid concentrations decreased in the LR3 group, suggesting accelerated amino-acid utilization without anabolic gain.
IGF-1 LR3 treatment administered directly into growth-restricted fetal sheep circulation did not improve fetal growth or attenuate circulating insulin or fetal GSIS.
Yavuz et al. (2025) — International Journal of Biological Macromolecules
A 2025 tissue-engineering study described a decellularized Alstroemeria stem nerve conduit functionalized with GelMA hydrogel and controlled-release IGF-1 LR3, evaluated in a rat sciatic-nerve transection model. The authors reported improved histologic and functional regeneration markers in the IGF-1 LR3-loaded conduits relative to peptide-free controls.
PubChem CID 16131201 — National Center for Biotechnology Information
The PubChem record for Long R3 IGF-1 catalogues the 83-residue analog with the 13-residue N-terminal extension and Arg3 substitution. The record aggregates synonyms used in research-reagent and laboratory cell-culture catalogs and links to the underlying biochemical literature.
DrugBank — IGF-1 reference
The DrugBank entry for native human IGF-1 (mecasermin, marketed as Increlex) summarizes the FDA-approved indication for severe primary IGF-1 deficiency. The LR3 analog is characterized as a research-only IGF-1 variant designed for reduced IGF-binding-protein affinity; no LR3 product holds marketing authorization.
Coverage notes
Independent peer-reviewed clinical literature on IGF-1 LR3 in humans is essentially absent: PubMed-indexed studies are dominated by cell-culture and animal-model uses where LR3 functions as a research reagent rather than a candidate therapeutic. No completed or active human trial of IGF-1 LR3 is registered on ClinicalTrials.gov as of this writing.