IGF-1 LR3Also known as: Insulin-like Growth Factor 1 Long R3, IGF-1 Long R3, LR3 IGF-1

Mechanism of Action

IGF-1 LR3 is a synthetic analog of IGF-1 with an extended half-life. It binds to IGF-1 receptors on muscle and other cells, activating anabolic signaling pathways that stimulate protein synthesis, cell growth (hyperplasia), and tissue regeneration. The extended structure of LR3 reduces binding to IGF binding proteins, increasing its bioavailability and duration of action compared to native IGF-1.

Reported Research Benefits

Primarily used in preclinical research for its effects on muscle hypertrophy, skeletal muscle regeneration, recovery from injury, insulin sensitivity studies, and investigations into aging mechanisms. It is also studied for its role in activating satellite cells and promoting extracellular matrix remodeling.

Dosing Protocol & Reconstitution

IGF-1 LR3 is supplied as a lyophilized powder that requires reconstitution with bacteriostatic water. Typical research dosing involves subcutaneous or intramuscular injection in controlled laboratory settings, with dosages carefully calculated often based on animal studies or in vitro concentrations. The peptide should be refrigerated (2–8°C) after reconstitution and used within 60 days.

Research Notes

IGF-1 LR3 has a significantly longer half-life than native IGF-1 (up to 20–30 hours vs. ~15 hours for IGF-1). Studies confirm its potent anabolic effects through enhancement of satellite cell activation and improved muscle repair. It is implicated in signaling pathways involving GH, mTOR, and insulin receptor systems, making it a potent candidate for studies of muscular diseases, sarcopenia, and metabolic regulation.

Research Summary

IGF-1 LR3 is a recombinant long arginine analog of insulin-like growth factor 1 with a 13 amino acid N-terminal extension that reduces IGF-binding protein affinity, resulting in a ~120-hour half-life versus 15 hours for native IGF-1. It drives protein synthesis, muscle satellite cell proliferation, fat oxidation, and tissue repair via PI3K/Akt and MAPK pathways. Used in preclinical muscle hypertrophy and wasting disease research.

Side Effects & Safety

Hypoglycemia risk (significant — must consume carbohydrates around dosing). Joint pain, headaches, water retention, and jaw/hand growth at high doses. Potential for tumor promotion given IGF-1's mitogenic activity. Contraindicated with active malignancy.

Stability & Storage

Refer to research notes

Molecular Data

Sequence: MGYLSGGDPEERKECLQLMVLGEVIRDSVQGTCYASNERRGIAQGILTVRKEGSGRGFQRIKSIVRYYIAQNLVGF
Molecular Formula: C370H601N103O115S7
Molecular Weight: 9118.7 g/mol
CAS Number: 946870-92-4
IUPAC Name: Lysinyl-(1)-des(1-3)-Insulin-like Growth Factor 1 Long Arg3 variant synthetic peptide

Primary literature: https://pubmed.ncbi.nlm.nih.gov/?term=IGF-1+LR3+insulin-like+growth+factor