IGF-1

IGF-1 acts by binding to the IGF-1 receptor (IGF-1R), a tyrosine kinase receptor expressed in virtually every tissue. Receptor activation triggers the PI3K/Akt and MAPK/ERK signaling cascades, which regulate cell growth, differentiation, survival, and metabolism. In muscle tissue, IGF-1 activates satellite cells and stimulates protein synthesis through mTOR pathway activation, promoting hypertrophy and repair. In bone, it stimulates osteoblast proliferation and collagen synthesis. IGF-1 also has insulin-like metabolic effects including glucose uptake promotion in peripheral tissues. In the brain it acts as a neurotrophic factor supporting neuronal survival and synaptic plasticity. Its signaling is modulated by a family of IGF-binding proteins (IGFBPs) that regulate bioavailability.