Source: Collective analysis of published data from Journal of Endocrinology, Growth Hormone & IGF Research, and pharmacokinetic reports on Long R3 IGF-1
To characterize the pharmacological profile of IGF-1 LR3 – a long-acting analog of human insulin-like growth factor 1 (IGF-I) – in order to determine its potential for research on muscle growth, metabolism, and cellular differentiation.
IGF-1 LR3 (Long R3 IGF-I) is a modified peptide in which glutamic acid at position 3 is replaced by arginine, and the N-terminus is extended by 13 amino acids. These modifications significantly reduce its binding to IGF-binding proteins (IGFBPs), increasing its bioavailability and duration of action.
Type: preclinical in vitro and in vivo studies
Models: myoblast cell lines, rodents, and primates
Interventions: systemic or local administration of IGF-1 LR3
Evaluated parameters: cell proliferation, protein synthesis, IGF-1R phosphorylation, insulin sensitivity
Pharmacokinetics
IGF-1 LR3 has an extended half-life (~20–30 hours) compared to endogenous IGF-I (~10–15 min).
Reduced binding to IGFBPs → greater free fraction and access to IGF-1 receptors.
Increased plasma stability and prolonged anabolic signaling.
Cellular and Tissue Effects
Stimulates phosphorylation of IGF-1R and the PI3K/Akt pathway, leading to enhanced protein synthesis and cellular growth.
Increases myoblast proliferation and activates satellite cells in animal models.
Maintains an anabolic state without the need for frequent administration.
Metabolic Effects
Moderately increases glucose uptake in muscles, but with lower hypoglycemic activity compared to insulin.
Supports lipolysis and improves insulin sensitivity in experimental models.
IGF-1 LR3 is a long-acting analog with enhanced biological activity and reduced binding to IGFBPs.
Maintains a stable anabolic effect and stimulates muscle growth in experimental models.
Suitable for research purposes related to muscle regeneration, metabolic diseases, and cellular signaling.
IGF-1 LR3 is a valuable tool for studying anabolic mechanisms and the role of IGF-1 in muscle homeostasis.
Requires careful dosing consideration in preclinical models due to potential effects on cell proliferation and glucose metabolism.