IGF-1 LR3 Research Evidence
The IGF-1 LR3 evidence base: trials, journals, and what the data does not yet show.
Key Findings at a Glance
• IGF-1 LR3 has approximately 100-fold reduced affinity for IGF-binding proteins compared to native IGF-1, resulting in 3-fold greater biological potency and an extended half-life of 20-30 hours. • The PI3K/Akt/mTOR pathway activated by IGF-1 LR3 simultaneously increases protein synthesis through p70S6K and decreases protein degradation through FOXO1 suppression, creating a dual anabolic mechanism. • In cell culture studies, Long R3 IGF-1 at 10 ng/mL is sufficient to induce significant myotube hypertrophy through Akt-dependent signaling, with effects blocked by myostatin co-expression. • Systemic Long R3 IGF-1 infusion in animal models suppresses endogenous GH, IGF-1, and IGFBP-3 through hypothalamic-pituitary negative feedback, highlighting the distinction between local and systemic administration effects.
Metabolic Effects
IGF-1 LR3 influences glucose metabolism through activation of insulin receptor substrate signaling pathways shared with insulin, promoting glucose uptake and glycogen synthesis in skeletal muscle tissue. However, systemic administration of Long R3 IGF-1 in animal models has demonstrated complex metabolic effects including suppression of endogenous growth hormone secretion through negative feedback on the hypothalamic-pituitary axis. Studies in pigs receiving Long R3 IGF-1 infusion documented reduced plasma concentrations of GH, endogenous IGF-1, IGFBP-3, and insulin, indicating significant hypothalamic-pituitary feedback inhibition at higher systemic doses. In guinea pig models, 7-day infusion of Long R3 IGF-1 at 120-360 micrograms per day increased plasma IGF levels but produced modest effects on body composition, highlighting the complexity of systemic IGF-1 analog administration. These findings underscore the importance of dose optimization and the distinction between local and systemic IGF-1 LR3 effects in research settings.
Trials and reviews
- Renehan IGF-1 cancer metaLancet2004
elevated IGF-1 tied to higher prostate / breast / colorectal cancer risk · meta-analysis
References
- Insulin-like growth factor I and muscle growth · Adams GR · 2002
- Intranasal long R3 insulin-like growth factor-1 treatment promotes amyloid plaque remodeling in cerebral cortex but fails to preserve cognitive function in male 5XFAD mice. · Engel MG, Narayan S, Cui MH et al. · 2025
- Insulin-Like Growth Factor-1 (IGF-1) and Its Monitoring in Medical ... · Bailes J, Soloviev M · 2021
- IGF-1 LR3 does not promote growth in late-gestation growth-restricted fetal sheep. · White A, Stremming J, Wesolowski SR et al. · 2025
- IGF-1 Has Plaque-Stabilizing Effects in Atherosclerosis by Altering ... · von der Thüsen JH, Borensztajn KS, Moimas S, van Heiningen S, Teeling P, van Berkel TJ, Biessen EA · 2011
- Revolutionary decellularized Alstroemeria stem-based nerve conduit integrated with GelMA and controlled IGF-1 LR3 release for enhanced rat sciatic nerve regeneration. · Yavuz E, Sağır MS, Ercan A et al. · 2025
- Recombinant expression of IGF-1 and LR3 IGF-1 fused ... - PubMed · Lu Z, Liu N, Huang H, Wang Y, Tu T, Qin X, Wang X, Zhang J, Su X, Tian J, Bai Y, Luo H, Yao B, Zhang H · 2023
- Attenuated glucose-stimulated insulin secretion during an acute IGF-1 LR3 infusion into fetal sheep does not persist in isolated islets. · White A, Stremming J, Brown LD et al. · 2023
- Use of Growth Hormone, IGF-I, and Insulin for Anabolic Purpose: Pharmacological Basis, Methods of Detection, and Adverse Effects · Anderson LJ, Tamayose JM, Garcia JM · 2018
- IGF-1 infusion to fetal sheep increases organ growth but not by stimulating nutrient transfer to the fetus. · Stremming J, Heard S, White A et al. · 2021
- The IGF-1/PI3K/Akt Pathway Prevents Expression of Muscle Atrophy ...
- Reduced glucose-stimulated insulin secretion following a 1-wk IGF-1 infusion in late gestation fetal sheep is due to an intrinsic islet defect. · White A, Stremming J, Boehmer BH et al. · 2021
- Performance Enhancing Hormone Doping in Sport - Endotext - NCBI