Scientific Reference
IGF-1 LR3 (Long R3 IGF-1)
Evidence profile: Controlled human evidence
IGF-1 LR3 is a synthetic 83-amino acid analog of insulin-like growth factor-1 (IGF-1), modified with an arginine substitution at position 3 and an extended N-terminal sequence. These modifications significantly reduce binding to IGF-binding proteins (IGFBPs), resulting in prolonged circulation and increased bioavailability. Unlike native IGF-1, which has a short half-life, IGF-1 LR3 exhibits a substantially extended half-life (~20–30 hours), allowing sustained activation of IGF-1 receptors. Despite its potency and widespread research use, it has never been approved for human use and lacks clinical trial data, remaining strictly a research compound.
Mechanism of Action
IGF-1 LR3 acts as a full agonist of the IGF-1 receptor, activating downstream PI3K/Akt/mTOR and MAPK/ERK signaling pathways. Its structural modifications reduce interaction with IGF-binding proteins, allowing higher levels of free circulating peptide and prolonged receptor activation. This results in enhanced anabolic signaling, cellular proliferation, and tissue growth.
Molecular Information
- Type: Modified IGF-1 analog
- Length: 83 amino acids
Published Research
Prolonged stimulation of growth hormone (GH) and insulin-like growth factor I secretion by CJC-1295, a long-acting analog of GH-releasing hormone, in healthy adults
Teichman SL et al. · The Journal of clinical endocrinology and metabolism · 2006 · Clinical
PMID 16352683 — View on PubMedPlace of cabergoline in acromegaly: a meta-analysis
Sandret L et al. · The Journal of clinical endocrinology and metabolism · 2011 · Review
PMID 21325455 — View on PubMed