IGF-1 LR3, which stands for insulin-like growth factor-1 long arginine 3, is a member of the family of insulin-like growth factors (IGFs), which are potent growth factors in mammals. All IGF analogues share similarities in their amino acid sequences with the protein insulin. They have prominent roles in everything from physiologic growth to cell division and even cellular communication1 .
Insulin-Like Growth Factor 1 Function
IFG-1, which is made primarily by the liver, is produced in response to growth hormone. It plays critical roles in cell growth, programmed cell death (apoptosis), and cell division. In fact, IGF-1 actively encourages cells to divide while inhibiting apoptosis. The combined effect is maximal cell proliferation.
Though IGF-1 is associated with cell growth and division throughout most of the body, it has an opposite effect on adipose (fat) tissue. Individuals with IGF-1 deficiency tend to be obese, with underdeveloped muscle and skeletal tissue. A finding supported by recent research, which that IGF-1 levels are inversely correlated with body mass index (BMI)2 . IGF-1 is currently being investigated as a potential mechanism for countering the obesity epidemic as administration tends to burn fat and build muscle.
Because IGF-1 regulates cell division, there has been a push to develop synthetic analogues of the naturally occurring molecule. These analogues have the potential to be powerful anti-cancer agents, decrease obesity rates, and even treat chronic muscle diseases. Currently, the most potent IGF-1 analogue is IFG-1 LR3 (a.k.a. IGF-1-LR3, LR3-IGF-1, IGF-1 Long Arginine 3).
This peptide is identical to IGF-1 with the exception of a 13-amino-acid addition to the N-terminal end of the molecule and the conversion of the third glutamine residue to arginine. As a result of these changes, IGF-1 LR3 does not bind as strongly to IGF binding proteins (IGFBPs), which degrade naturally occurring IGF-1 and thus reduce its half-life and potency. As a result of the modifications discussed above, IGF-1 LR3 remains in the bloodstream for longer periods of time than IGF-1 and thus has a longer duration of action3 . IFG-1 has a half-life of about 15 minutes while its counterpart has a half-life closer to 30 hours (1 day).
Clinical Trials of IGF-1 and Its Derivatives
Several large-scale clinical trials have been conducted using IGF-1 and its analogues. The first of these studies investigated the use of the molecule in ALS (Lou Gehrig’s Disease) as well as Duchene Muscular Dystrophy (DMD). The DMD trial was carried out by the Children’s Hospital Medical Center in Cincinnati, Ohio. The study compared the effects of IGF-1 to those of corticosteroids. Results suggest that IGF-1 provides for better growth in boys with DMD without producing any serious neurological or cardiovascular side effects4 .
Additional clinical trials have studied the effects of IGF-1 in ALS, Rett syndrome, and autism. The results from the latter two trials are not yet available. IGF-1 provides no benefit in ALS, which isn’t surprising given the low dosage of the drug used and the fact that ALS is primarily a motorneuron disease and not a muscle-wasting disease. So, the question becomes where to buy IGF-1 LR3?
- Pollak, M. The Insulin Receptor/Insulin-Like Growth Factor Receptor Family as a Therapeutic Target in Oncology. Clin. Cancer Res.18, 40-50 (2012).
- Alderete, T. L. et al. Relationships Between IGF-1 and IGFBP-1 and Adiposity in Obese African-American and Latino Adolescents. Obesity19, 933-938 (2011).
- Laajoki, L., Francis, G., Wallace, J., Carver, J. & Keniry, M. Solution Structure and Backbone Dynamics of Long-[Arg 3 ]insulin-like Growth Factor-I*. J. Biol. Chem.275, 10009-10015 (2000).
- Rutter, M. M. et al. Growth hormone treatment in boys with Duchenne muscular dystrophy and glucocorticoid-induced growth failure. Neuromuscul. Disord. NMD22, 1046-1056 (2012).