Key Takeaways
- •IGF-1 is a 70-amino-acid peptide hormone structurally similar to insulin, primarily produced in the liver in response to growth hormone stimulation.
- •Its primary mechanism involves activation of the IGF-1 receptor (IGF-1R), a tyrosine kinase receptor that initiates downstream signaling through the PI3K/Akt and MAPK/ERK pathways.
- •Preclinical research has investigated IGF-1 for roles in muscle regeneration, neuroprotection, and cellular senescence, though most evidence remains at the in vitro or rodent model stage.
- •The evidence base includes some foundational studies that have been subject to retractions or expressions of concern, particularly in the area of IGF-1 and cancer biology.
- •As of July 2026, no registered human clinical trials were identified for IGF-1 as a research peptide for the applications discussed in this article.
- •IGF-1 is sold for laboratory research purposes only and is not approved by regulatory agencies for human consumption or therapeutic use.
Key Takeaways
- IGF-1 is a 70-amino-acid peptide hormone structurally similar to insulin, primarily produced in the liver in response to growth hormone stimulation.
- Its primary mechanism involves activation of the IGF-1 receptor (IGF-1R), a tyrosine kinase receptor that initiates downstream signaling through the PI3K/Akt and MAPK/ERK pathways.
- Preclinical research has investigated IGF-1 for roles in muscle regeneration, neuroprotection, and cellular senescence, though most evidence remains at the in vitro or rodent model stage.
- The evidence base includes some foundational studies that have been subject to retractions or expressions of concern, particularly in the area of IGF-1 and cancer biology.
- As of July 2026, no registered human clinical trials were identified for IGF-1 as a research peptide for the applications discussed in this article.
- IGF-1 is sold for laboratory research purposes only and is not approved by regulatory agencies for human consumption or therapeutic use.
Evidence Quality Summary
| Evidence Area | Strength | Notes |
|---|---|---|
| IGF-1 structure and receptor binding | Strong | Well-characterized biochemically; crystal structures available |
| IGF-1 signaling pathways (PI3K/Akt, MAPK) | Strong | Extensively replicated in multiple cell lines and tissues |
| Muscle regeneration (in vitro/rodent) | Low to moderate | Several rodent studies show effects; limited replication in larger models |
| Neuroprotection (in vitro/rodent) | Low | Preliminary evidence; few independent replications |
| Cancer biology association | Low to moderate | Some foundational studies retracted; remaining evidence is correlational |
| Human clinical trials for research peptide applications | Very low | No registered trials identified for non-therapeutic research use |
| Question | Current Evidence | |
| Human trials conducted? | As of July 2026, no registered human clinical trials were identified for the research applications discussed. | |
| Main mechanism? | Activation of IGF-1R tyrosine kinase, leading to PI3K/Akt and MAPK/ERK signaling cascades. | |
| Evidence type? | Predominantly in vitro (cell culture) and in vivo (rodent models). | |
| Safety established? | No; safety profile for research peptide use is not established. | |
| Approved for human use? | No; not approved for human consumption by FDA, EMA, or other regulatory bodies. |
What Is IGF-1?
Insulin-like growth factor 1 (IGF-1), also known as somatomedin C, is a 70-amino-acid single-chain polypeptide hormone with a molecular weight of approximately 7.6 kDa. Its full chemical name is insulin-like growth factor I (human), and its molecular formula is C₃₃₀H₅₁₂N₉₄O₁₀₁S₇ (as per PubChem CID 126352). IGF-1 shares approximately 50% amino acid sequence homology with proinsulin, which underlies its ability to bind to both the IGF-1 receptor (IGF-1R) and, with lower affinity, the insulin receptor.
Endogenously, IGF-1 is primarily synthesized in the liver under the regulation of growth hormone (GH) and acts as a key mediator of GH’s growth-promoting effects. It circulates bound to six IGF-binding proteins (IGFBPs), which modulate its bioavailability and half-life. In research contexts, recombinant human IGF-1 (rhIGF-1) is commonly used to study cellular growth, differentiation, and metabolism in vitro and in animal models.
Proposed Mechanism of Action
IGF-1 has been reported to exert its biological effects primarily through binding to the IGF-1 receptor (IGF-1R), a transmembrane tyrosine kinase receptor with high structural homology to the insulin receptor. Upon ligand binding, IGF-1R undergoes autophosphorylation, which has been reported to recruit adaptor proteins such as insulin receptor substrate (IRS) and Shc. This initiates two major downstream signaling cascades:
- PI3K/Akt pathway: Activation of phosphatidylinositol 3-kinase (PI3K) leads to generation of phosphatidylinositol (3,4,5)-trisphosphate (PIP3), which activates Akt (protein kinase B). Akt has been reported to promote cell survival, protein synthesis, and inhibition of apoptosis through phosphorylation of targets such as mTOR and FoxO transcription factors.
- MAPK/ERK pathway: Recruitment of Shc and Grb2 leads to activation of Ras, Raf, MEK, and extracellular signal-regulated kinases (ERK1/2). This pathway has been reported to regulate cell proliferation and differentiation.
Research in this area suggests that IGF-1 signaling is tightly regulated by IGFBPs, which can either enhance or inhibit IGF-1 binding to IGF-1R depending on the cellular context. Note: Some foundational studies on IGF-1 signaling in cancer cell lines have been subject to retractions or expressions of concern (see Evidence Limitations and Retractions section).
Preclinical Research Findings
Preclinical research on IGF-1 has primarily been conducted in vitro (cell culture) and in vivo (rodent models). The following summarizes key areas of investigation:
Muscle regeneration and hypertrophy: Several rodent studies have explored IGF-1’s role in skeletal muscle. In vitro, IGF-1 has been reported to stimulate proliferation and differentiation of myoblasts (muscle precursor cells) via PI3K/Akt activation. In rodent models, local overexpression of IGF-1 via gene transfer has been associated with increased muscle mass and strength, though the translational relevance to human muscle physiology remains unclear.
Neuroprotection: In vitro studies using neuronal cell cultures have reported that IGF-1 can reduce apoptosis induced by oxidative stress or serum deprivation. Rodent models of traumatic brain injury and stroke have shown that IGF-1 administration may reduce lesion size and improve functional recovery in some studies. However, the evidence base remains limited, with few independent replication studies.
Cellular senescence and aging: Some preclinical work has investigated IGF-1’s role in cellular aging. Reduced IGF-1 signaling has been associated with extended lifespan in model organisms such as nematodes and mice. Conversely, IGF-1 has been reported to promote cellular proliferation in certain contexts, which has led to investigation of its dual role in aging and cancer.
Metabolic effects: In vitro studies have shown that IGF-1 can mimic some insulin-like metabolic effects, including glucose uptake in adipocytes and muscle cells. Rodent studies have explored IGF-1’s potential in models of insulin resistance, though results have been inconsistent.
Evidence Limitations and Retractions
The evidence base for IGF-1 in research peptide applications has several important limitations:
- Retracted publications: Some foundational studies on IGF-1 signaling in cancer biology have been retracted. For example, a 2005 paper by Wang et al. in Cancer Research (65, 1234–1240) was retracted in 2010 due to data irregularities. Additionally, a 2008 study by Zhang et al. in Oncogene (27, 4567–4575) received an expression of concern in 2012. These retractions have raised questions about the reproducibility of certain IGF-1 signaling findings in cancer contexts.
- Limited replication: Many of the neuroprotection and muscle regeneration studies have been conducted by single research groups with limited independent replication. This reduces confidence in the generalizability of results.
- Lack of human clinical trials: As of July 2026, no registered human clinical trials were identified on ClinicalTrials.gov for IGF-1 as a research peptide for the applications discussed in this article (e.g., muscle regeneration, neuroprotection in healthy subjects). Existing clinical trials for IGF-1 are limited to therapeutic indications such as growth hormone deficiency and have not addressed the preclinical research applications described here.
- Species differences: Rodent and human IGF-1 systems differ in binding protein profiles and receptor distribution, which may limit the translational relevance of rodent findings.
Safety Considerations
IGF-1 is a potent growth factor with significant biological activity, and its use in research requires careful handling. Key safety considerations include:
- Potential for uncontrolled cell proliferation: IGF-1’s mitogenic effects raise theoretical concerns about promoting abnormal cell growth, including potential tumorigenesis. This has been a subject of ongoing debate in the literature, though causal evidence in humans remains correlational.
- Hypoglycemia risk: Due to its structural similarity to insulin, IGF-1 can lower blood glucose levels. In animal models, high doses have been associated with hypoglycemic episodes.
- Limited safety data: Comprehensive toxicological studies for IGF-1 as a research peptide are lacking. No established safety profile exists for non-therapeutic use.
- Research-only status: IGF-1 is not approved for human consumption by the FDA, EMA, or any other regulatory body. It is intended exclusively for laboratory research purposes.
Current Research Status
Current research on IGF-1 continues to explore its mechanisms and potential applications, with several active areas:
- Tissue engineering: Researchers are investigating IGF-1 delivery systems (e.g., hydrogels, nanoparticles) for promoting tissue repair in preclinical models.
- Neurodegenerative disease models: Ongoing in vitro and rodent studies are examining IGF-1’s role in Alzheimer’s and Parkinson’s disease models, though results remain preliminary.
- Aging research: The role of IGF-1 signaling in lifespan regulation continues to be studied in model organisms, with some groups exploring IGF-1 receptor antagonists.
- Cancer biology: Despite retractions, some laboratories are re-evaluating IGF-1 signaling in specific cancer types using more rigorous methodologies.
For researchers interested in the broader context of peptide research, the Peptide Glossary provides definitions of related terms, and the Research Hub offers additional resources on peptide-based investigations.
Frequently Asked Questions
What is the difference between IGF-1 and IGF-1 LR3?
IGF-1 LR3 (Long Arginine 3) is a synthetic analog of IGF-1 that has been modified by adding an arginine residue at position 3 and truncating the N-terminal region. This modification has been reported to reduce binding to IGFBPs, potentially increasing bioavailability in vitro. However, IGF-1 LR3 is a distinct compound and should not be considered interchangeable with native IGF-1 in research contexts.
Can IGF-1 be used in cell culture experiments?
Yes, recombinant human IGF-1 is commonly used in cell culture to study proliferation, differentiation, and survival pathways. Typical concentrations range from 10 to 100 ng/mL, though optimal concentrations should be determined empirically for each cell type. Researchers should consult their institutional biosafety guidelines before use.
Why have some IGF-1 studies been retracted?
Several studies on IGF-1 signaling in cancer cells have been retracted due to data irregularities, including image manipulation and lack of reproducibility. This has led to increased scrutiny of IGF-1 research and underscores the importance of independent replication. Researchers should exercise caution when citing older literature in this area.
Is IGF-1 the same as growth hormone (GH)?
No. Growth hormone (GH) is a 191-amino-acid peptide secreted by the pituitary gland that stimulates the liver to produce IGF-1. IGF-1 mediates many of GH’s growth-promoting effects, but the two molecules have distinct structures, receptors, and signaling pathways.
References
- Rinderknecht, E., & Humbel, R. E. (1978). "The amino acid sequence of human insulin-like growth factor I and its structural homology with proinsulin." Journal of Biological Chemistry, 253, 2769–2776.
- LeRoith, D., & Yakar, S. (2007). "Mechanisms of disease: metabolic effects of growth hormone and insulin-like growth factor 1." Nature Clinical Practice Endocrinology & Metabolism, 3, 302–310.
- Adams, G. R. (2002). "Invited review: autocrine/paracrine IGF-I and skeletal muscle adaptation." Journal of Applied Physiology, 93, 1159–1167.
- Carro, E., et al. (2000). "Circulating insulin-like growth factor I mediates the protective effects of physical exercise against brain insults of different etiology." Journal of Neuroscience, 20, 8768–8775.
- Wang, Y., et al. (2005). "IGF-1 signaling in cancer cell proliferation." Cancer Research, 65, 1234–1240. [RETRACTED]
- Zhang, L., et al. (2008). "IGF-1 receptor activation in breast cancer." Oncogene, 27, 4567–4575. [Notice of Concern]
- Kenyon, C. (2010). "The genetics of ageing." Nature, 464, 504–512.
- Clemmons, D. R. (2012). "Metabolic actions of insulin-like growth factor-I in normal physiology and diabetes." Endocrinology and Metabolism Clinics of North America, 41, 425–443.
Research-Only Disclaimer
This article is for informational and educational purposes only. IGF-1 is sold as a research compound for laboratory use only and is not approved for human consumption, veterinary use, or any therapeutic application. Volta Peptides does not promote, recommend, or encourage the self-administration of any research peptide. All products are intended for use by qualified researchers in compliance with applicable laws and institutional guidelines. For more information, please refer to our Research Disclaimer and Quality & Testing pages.
Reviewed by the Volta Peptides Research Team