IGF-1
Category: Hormones · Last updated
IGF-1 (Insulin-like Growth Factor 1, also called somatomedin C) is a 70-amino-acid peptide hormone structurally related to insulin. It is produced primarily by the liver in response to pituitary growth-hormone stimulation and mediates most of the systemic anabolic effects attributed to GH.
Action
IGF-1 binds the IGF-1 receptor (IGF1R), a transmembrane tyrosine kinase, activating PI3K-Akt and Ras-MAPK pathways. Downstream effects include:
- Increased protein synthesis in skeletal muscle and other tissues
- Increased cellular proliferation and differentiation
- Crosstalk with insulin signaling (IGF1R shares >50% sequence identity with the insulin receptor)
Plasma measurement
Clinical labs measure total IGF-1 plasma concentration as a stable readout of GH-axis activity (GH itself fluctuates pulsatilely; IGF-1 has a longer half-life).
Relevance to research peptides
- Tesamorelin · the FDA Phase 3 program reported substantial IGF-1 elevation following 26 weeks of treatment (Falutz et al., JCEM 2010; PMID 20554713)
- CJC-1295 · the original ConjuChem trials reported sustained IGF-1 elevation with the With-DAC variant (Teichman et al., JCEM 2006)
- Ipamorelin · GH pulses produce downstream IGF-1 rise