IGF-1 LR3
experimentalAlso known as: Long R3 IGF-1, Long Arg3 IGF-1
**Mechanism of Action** IGF-1 LR3 (Long R3 IGF-1) is a synthetic analog of insulin-like growth factor-1 engineered with an arginine substitution at position 3 and a 13-amino-acid N-terminal extension. This modification significantly reduces binding to IGF-binding proteins (IGFBPs), thereby prolonging its half-life and enhancing bioavailability. The peptide acts primarily through the IGF-1 receptor (IGF-1R), activating downstream PI3K/Akt and MAPK/ERK signaling pathways. This promotes protein synthesis, satellite cell proliferation, and myogenic differentiation, leading to skeletal muscle hypertrophy and reduced catabolism. **Key Research Findings** Preclinical studies (PubMed-indexed) demonstrate that IGF-1 LR3 induces greater myotube hypertrophy in vitro compared to native IGF-1, with sustained receptor activation over 24–48 hours. In rodent models, systemic administration increases lean body mass and muscle fiber cross-sectional area, particularly in type II fibers, while attenuating atrophy in cachexia models. However, prolonged IGF-1R activation has been linked to mitogenic effects in non-muscle tissues, raising concerns about potential tumor growth promotion. No human clinical trials have been published; all data derive from animal or cellular models. **Clinical Relevance** IGF-1 LR3 remains an experimental compound with no approved therapeutic indications. Its potential applications include muscle-wasting diseases (e.g., sarcopenia, cachexia) and recovery from injury, but safety concerns—such as hypoglycemia, acromegaly-like effects, and neoplastic risk—preclude clinical use. Current evidence is insufficient to support human administration outside controlled research settings. For research purposes only — not medical advice.
Key data
Research & studies
Commonly encountered peptides include GHRH analogues, GHS, GH fragment AOD9604, and IGF-1 analogues.; Reported adverse effects include endocrine/metabolic disturbances, fluid retention, musculoskeletal symptoms, and injection-site reactions.; Evidence tiers range from regulatory-grade trial data to complete absence of human studies.; A clinically oriented assessment algorithm is proposed for exposure history, symptom triage, and risk communication.
First-ever decellularized plant-based nerve conduit fabricated from Alstroemeria stem material.; Conduit integrated with GelMA and controlled release of IGF-1 LR3 enhanced axonal regeneration.; Performance comparable to autologous nerve grafts in a 1 cm rat sciatic nerve defect.; No systemic toxicity observed with the IGF-1 LR3-controlled releasing decellularized conduit.
IGF-1 LR3 treatment did not increase fetal body weight in growth-restricted sheep.; Plasma insulin, glucose, oxygen, and glucose-stimulated insulin secretion were unchanged between groups.; Circulating amino acids, including branched-chain amino acids, decreased with IGF-1 LR3 treatment.; Maintaining amino acid or other nutrient levels may be necessary for IGF-1 LR3 to promote growth in FGR.
Intranasal LR3-IGF-1 did not significantly alter cognitive symptoms in male 5XFAD mice.; LR3 treatment reduced filamentous plaques and increased inert plaques in the cortex.; LR3-IGF-1 enhanced uptake of Aβ1-42 by BV2 microglial cells in vitro.; LR3 promoted gene pathways related to actin remodeling and endocytosis.
IGF-1 and LR3 IGF-1 were successfully expressed in P. pastoris using xylanase fusion.; Purified IGF-1 and LR3 IGF-1 showed bioactivity equivalent to standard IGF-1.; Fermentation in a 15-L bioreactor yielded up to 0.5 g/L XynCDBFV-IGF-1 and 1 g/L XynCDBFV-TEV-LR3 IGF-1.
Fetal plasma insulin decreased during IGF-1 LR3 infusion.; In vivo GSIS was 66% lower with IGF-1 LR3 versus control.; Insulin secretion from isolated islets was not different between groups.; Acute IGF-1 LR3 may directly suppress insulin secretion, but islets can recover GSIS in vitro.
Loss of N-glycosylation in CHO cells alters cell surface expression of integrin subunits and reduces IGF-1R and IQGAP1 levels.; In silico docking indicates IQGAP1's IQ domain interacts with the kinase domain of IGF-1R.; IGF-1 stimulation fails to phosphorylate ERK1/2 in N-glycosylation-deficient cells.; Proper glycosylation by MGAT1 and MGAT5 is essential for IGF-1R processing and downstream ERK signaling.
IGF-1 LR3 infusion lowered fetal plasma insulin and glucose concentrations.; Fetal glucose-stimulated insulin secretion was reduced during hyperglycemic clamp.; Islets isolated from IGF-1-treated fetuses showed decreased insulin secretion in vitro.; Pancreatic insulin content was not different between groups, indicating a functional islet defect.
Frequently asked questions
What is IGF-1 LR3?
**Mechanism of Action** IGF-1 LR3 (Long R3 IGF-1) is a synthetic analog of insulin-like growth factor-1 engineered with an arginine substitution at position 3 and a 13-amino-acid N-terminal extension. This modification significantly reduces binding to IGF-binding proteins (IGFBPs), thereby prolonging its half-life and
How does IGF-1 LR3 work?
Long-acting IGF-1 analog with reduced IGFBP binding, prolonging activation of the IGF-1 receptor to drive muscle hypertrophy.
What is the research status of IGF-1 LR3?
IGF-1 LR3 is currently classified as experimental, with 16 research references on record. This is for research purposes only and is not medical advice.
Related peptides
Mechanically activated IGF-1 splice variant that activates muscle satellite cells for repair and hypertrophy.
Truncated IGF-1 variant with high local potency and short half-life, studied for site-specific muscle growth.
Activin-binding glycoprotein that antagonizes myostatin (GDF-8) to release the brake on skeletal muscle growth.
Soluble ActRIIB-Fc decoy receptor that sequesters myostatin and related ligands; trialed in muscular dystrophy before discontinuation.
Build on IGF-1 LR3 data programmatically
Structured peptide data, semantic search, and AI summaries via one API.
Get a free API key