IGF-1 LR3

Key Benefits#

• Direct muscle hypertrophy via IGF-1R stimulation
• Muscle hyperplasia (new fiber formation) — unique among peptides
• Rapid gains in lean muscle mass
• Accelerated recovery from training and injury
• Increased nutrient uptake by muscle cells
• Fat oxidation enhancement
• Bone density improvement
• Cartilage and connective tissue repair

Mechanism of Action#

IGF-1 LR3 is a modified version of IGF-1 with an arginine substitution at position 3 and a 13-amino-acid extension peptide that reduces binding to IGF-binding proteins (IGFBPs), extending its half-life from ~10 minutes to ~20-30 hours. It binds IGF-1 receptors on muscle cells, activating PI3K/Akt/mTOR pathways that drive protein synthesis, muscle hypertrophy, and satellite cell activation for hyperplasia (new muscle cell formation). Unlike GH, it does not require liver conversion.

Dosing Protocols#

Side Effects#

• Hypoglycemia (significant risk — insulin-like activity)
• Acromegaly-like effects with excessive long-term use
• Jaw and hand swelling
• Organ hypertrophy with extreme doses
• Lipohypertrophy at injection sites
• Headache

Contraindications#

Active cancer or history of cancer (IGF-1 is a potent growth factor and may accelerate tumor growth). Diabetes with hypoglycemia risk. Pregnancy or breastfeeding. Acromegaly.

Storage#

Lyophilized powder: store at −20°C. Reconstituted: refrigerate at 2–8°C, use within 30 days. Acetic acid (0.1%) used as reconstitution solvent.

Featured In Stacks#

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   Provisional Treatment of Volumetric Muscle Loss With Insulin-like Growth Factor 1 Releasing Muscle Void Fillers

   Clark AR, Adams AT, McKinley TO, Natoli RM, Dearth CL, Goldman SM · The Journal of surgical research · 2026PubMed Verified

2. 2.
   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, Erginer M, Barlas FB, Sakarya D et al. · International journal of biological macromolecules · 2025PubMed Verified

3. 3.
   IGF-1 LR3 does not promote growth in late-gestation growth-restricted fetal sheep

   White A, Stremming J, Wesolowski SR, Al-Juboori SI, Dobrinskikh E, Limesand SW et al. · American journal of physiology. Endocrinology and metabolism · 2025PubMed Verified

4. 4.
   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, Branch CA, Zhang X, Gandy SE et al. · Journal of Alzheimer's disease : JAD · 2025PubMed Verified

5. 5.
   Recombinant expression of IGF-1 and LR3 IGF-1 fused with xylanase in Pichia pastoris

   Lu Z, Liu N, Huang H, Wang Y, Tu T, Qin X et al. · Applied microbiology and biotechnology · 2023PubMed Verified

6. 6.
   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, Rozance PJ · Journal of developmental origins of health and disease · 2023PubMed Verified

7. 7.
   N-Linked Glycosylation in Chinese Hamster Ovary Cells Is Critical for Insulin-like Growth Factor 1 Signaling

   Salvi R, Kumar C, Brahmbhatt K, Subedi R, Idicula-Thomas S, Madan T et al. · International journal of molecular sciences · 2022PubMed Verified

8. 8.
   Sheep recombinant IGF-1 promotes organ-specific growth in fetal sheep

   Stremming J, White A, Donthi A, Batt DG, Hetrick B, Chang EI et al. · Frontiers in physiology · 2022PubMed Verified

9. 9.
   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, Chang EI, Jonker SS, Wesolowski SR et al. · American journal of physiology. Endocrinology and metabolism · 2021PubMed Verified

10. 10.
    IGF-1 infusion to fetal sheep increases organ growth but not by stimulating nutrient transfer to the fetus

    Stremming J, Heard S, White A, Chang EI, Shaw SC, Wesolowski SR et al. · American journal of physiology. Endocrinology and metabolism · 2021PubMed Verified

11. 11.
    Coronary vascular growth matches IGF-1-stimulated cardiac growth in fetal sheep

    Jonker SS, Giraud GD, Chang EI, Elman MR, Louey S · FASEB journal : official publication of the Federation of American Societies for Experimental Biology · 2020PubMed Verified

12. 12.
    Inhibition of activin-like kinase 4/5 attenuates cancer cachexia associated muscle wasting

    Levolger S, Wiemer EAC, van Vugt JLA, Huisman SA, van Vledder MG, van Damme-van Engel S et al. · Scientific reports · 2019PubMed Verified

13. 13.
    Epidermal growth factor receptor is required for estradiol-stimulated bovine satellite cell proliferation

    Reiter BC, Kamanga-Sollo E, Pampusch MS, White ME, Dayton WR · Domestic animal endocrinology · 2014PubMed Verified

14. 14.
    Na+ transport across rumen epithelium of hay-fed sheep is acutely stimulated by the peptide IGF-1 in vitro

    Shen Z, Martens H, Schweigel-Röntgen M · Experimental physiology · 2012PubMed Verified

15. 15.
    Potentiation of growth factor signaling by insulin-like growth factor-binding protein-3 in breast epithelial cells requires sphingosine kinase activity

    Martin JL, Lin MZ, McGowan EM, Baxter RC · The Journal of biological chemistry · 2009PubMed Verified

16. 16.
    Enhancement of maternal lactation performance during prolonged lactation in the mouse by mouse GH and long-R3-IGF-I is linked to changes in mammary signaling and gene expression

    Hadsell DL, Parlow AF, Torres D, George J, Olea W · The Journal of endocrinology · 2008PubMed Verified

17. 17.
    Effects of IGF-I bioavailability on bovine preantral follicular development in vitro

    Thomas FH, Campbell BK, Armstrong DG, Telfer EE · Reproduction (Cambridge, England) · 2007PubMed Verified

18. 18.
    Leptin in the bovine corpus luteum: receptor expression and effects on progesterone production

    Nicklin LT, Robinson RS, Marsters P, Campbell BK, Mann GE, Hunter MG · Molecular reproduction and development · 2007PubMed Verified

19. 19.
    In vitro and in vivo antitumor effects of the dual insulin-like growth factor-I/insulin receptor inhibitor, BMS-554417

    Haluska P, Carboni JM, Loegering DA, Lee FY, Wittman M, Saulnier MG et al. · Cancer research · 2006PubMed Verified

20. 20.
    Enhanced response of granulosa and theca cells from sheep carriers of the FecB mutation in vitro to gonadotropins and bone morphogenic protein-2, -4, and -6

    Campbell BK, Souza CJ, Skinner AJ, Webb R, Baird DT · Endocrinology · 2006PubMed Verified

21. 21.
    The local expression and abundance of insulin-like growth factor (IGF) binding proteins in skeletal muscle are regulated by age and gender but not local IGF-I in vivo

    Oliver WT, Rosenberger J, Lopez R, Gomez A, Cummings KK, Fiorotto ML · Endocrinology · 2005PubMed Verified

22. 22.
    Interaction of bovine granulosa and theca cells in a novel serum-free co-culture system

    Allegrucci C, Hunter MG, Webb R, Luck MR · Reproduction (Cambridge, England) · 2003PubMed Verified

23. 23.
    Extracellular signal-regulated kinase and phosphoinositol-3 kinase mediate IGF-1 induced proliferation of fetal sheep cardiomyocytes

    Sundgren NC, Giraud GD, Schultz JM, Lasarev MR, Stork PJ, Thornburg KL · American journal of physiology. Regulatory, integrative and comparative physiology · 2003PubMed Verified

24. 24.
    Paracrine effects of oocyte secreted factors and stem cell factor on porcine granulosa and theca cells in vitro

    Brankin V, Mitchell MR, Webb B, Hunter MG · Reproductive biology and endocrinology : RB&E · 2003PubMed Verified

25. 25.
    Oocyte-mediated suppression of follicle-stimulating hormone- and insulin-like growth factor-induced secretion of steroids and inhibin-related proteins by bovine granulosa cells in vitro: possible role of transforming growth factor alpha

    Glister C, Groome NP, Knight PG · Biology of reproduction · 2003PubMed Verified

26. 26.
    IGF-I and IGFBP-3 transport in the rat heart

    Boes M, Dake BL, Booth BA, Sandra A, Bateman M, Knudtson KL et al. · American journal of physiology. Endocrinology and metabolism · 2003PubMed Verified

27. 27.
    Insulin-like growth factor-I and analogues increase growth in artificially-reared neonatal pigs

    Dunshea FR, Chung CS, Owens PC, Ballard JF, Walton PE · The British journal of nutrition · 2002PubMed Verified

28. 28.
    Modulatory effects of gonadotrophins and insulin-like growth factor on the secretion of inhibin A and progesterone by granulosa cells from chicken preovulatory (F1-F3) follicles

    Lovell TM, Gladwell RT, Groome NP, Knight PG · Reproduction (Cambridge, England) · 2002PubMed Verified

29. 29.
    Interactions between follicle-stimulating hormone and growth factors in modulating secretion of steroids and inhibin-related peptides by nonluteinized bovine granulosa cells

    Glister C, Tannetta DS, Groome NP, Knight PG · Biology of reproduction · 2001PubMed Verified

30. 30.
    Granulosa cells of the cumulus oophorus are different from mural granulosa cells in their response to gonadotrophins and IGF-I

    Khamsi F, Roberge S · The Journal of endocrinology · 2001PubMed Verified

31. 31.
    Physicochemical characteristics of LR3-IGF1 protein inclusion bodies: electrophoretic mobility studies

    Wangsa-Wirawan ND, O'Neill BK, Middelberg AP · Biotechnology progress · 2001PubMed Verified

32. 32.
    The effect of insulin-like growth factor analogs on turkey satellite cell and embryonic myoblast proliferation

    Pesall JE, McFarland DC, McMurtry JP, Clapper JA, Francis GL, Gilkerson KK · Poultry science · 2001PubMed Verified

33. 33.
    Differential effects of insulin-like growth factor-I and gonadotropins on the proliferative activity of two subgroups of granulosa cells: cumulus oophorus and mural granulosa cells

    Khamsi F, Roberge S · Fertility and sterility · 2001RCTPubMed Verified

34. 34.
    Insulin-like growth factor I (IGF-I) and long R(3)IGF-I differently affect development and messenger ribonucleic acid abundance for IGF-binding proteins and type I IGF receptors in in vitro produced bovine embryos

    Prelle K, Stojkovic M, Boxhammer K, Motlik J, Ewald D, Arnold GJ et al. · Endocrinology · 2001PubMed Verified

35. 35.
    Novel studies on influence of gonadotropins and insulin-like growth factor-I on growth of cumulus oophorus in the rat

    Khamsi F, Roberge S · Endocrine · 2000PubMed Verified

36. 36.
    The modulation of gonadotrophic hormone action on the ovary by paracrine and autocrine factors

    Campbell BK · Anatomia, histologia, embryologia · 1999PubMed Verified

37. 37.
    The role of insulin-like growth factors in small intestinal cell growth and development

    MacDonald RS · Hormone and metabolic research = Hormon- und Stoffwechselforschung = Hormones et metabolisme · 1999ReviewPubMed Verified

38. 38.
    Clearance of IGFs and insulin from wounds: effect of IGF-binding protein interactions

    Robertson JG, Belford DA, Ballard FJ · The American journal of physiology · 1999PubMed Verified

39. 39.
    Effects of dose of LH on androgen production and luteinization of ovine theca cells cultured in a serum-free system

    Campbell BK, Baird DT, Webb R · Journal of reproduction and fertility · 1998PubMed Verified

40. 40.
    Interactions between follicle-stimulating hormone and growth factors in regulation of deoxyribonucleic acid synthesis in bovine granulosa cells

    Khamsi F, Armstrong DT · Biology of reproduction · 1997PubMed Verified

41. 41.
    The role of IGFBP-3 in the regulation of IGFBP-4 proteolysis

    Donnelly MJ, Holly JM · The Journal of endocrinology · 1996PubMed Verified

42. 42.
    Effects of insulin and insulin-like growth factors on protein and energy metabolism in tumour-bearing rats

    Tomas FM, Chandler CS, Coyle P, Bourgeois CS, Burgoyne JL, Rofe AM · The Biochemical journal · 1994PubMed Verified

43. 43.
    Insulin-like growth factor-I and more potent variants restore growth of diabetic rats without inducing all characteristic insulin effects

    Tomas FM, Knowles SE, Owens PC, Chandler CS, Francis GL, Ballard FJ · The Biochemical journal · 1993PubMed Verified