IGF-1 (LR3)

IGF 1 LR3 (Long R3 Insulin-like Growth Factor-I or Long R3IGF-I) is an 83 amino acid analog of human IGF-I actually comprising the complete human IGF 1 LR3 sequence but with the substitution of an Arg for the Glu at position 3, as well as a 13 amino acid extension peptide at the N-terminus. This makes Long R3IGF-I significantly more potent (2-3x) than IGF 1 LR3 in studies, because it has a lower affinity to be rendered inactive by IGF binding proteins, and consequently more potential activity in the body. IGF 1 LR3 1 consists of 70 amino acids in a single chain with three intramolecular disulfide bridges.

IGF 1 LR3 is a peptide roughly the same structure and size as insulin, or about 70 amino acids long. It belongs to the peptide family of substances identified as growth factors. It is a highly anabolic hormone released in the liver as well as in peripheral tissues such as skeletal muscle. In the body, IGF 1 is released in response to the presence of Human Growth Hormone (HGH). After intense resistance training, the body experiences a surge in GH and IGF 1 LR3, and this is one way that new muscle is built. Although GH is considered to be highly anabolic, in actuality, IGF 1 is suspected to be responsible for the primary anabolic activities of GH.

IGF 1 LR3 builds new muscle tissue by promoting nitrogen retention and protein synthesis. This causes the growth of muscles through both hyperplasia (which is an increase in number of muscle cells) and mitogenesis (which is the actual growth of new muscle fibres) IGF 1 LR3 effects are not limited to building new muscle, however. It has a potent effect on lipid (fat) metabolism, and helps the body burn fat at a significantly elevated rate. In addition, IGF 1 is both a neuroprotector and neuropromotor, which improves mental functions such as reflexes, memory, and learning ability. IGF is also important for production of connective tissue and insuring proper bone density.

What Is IGF-1 LR3 ?

IGF-1 LR3 (insulin-like growth factor-1 long arginine 3) is a synthetic, modified version of insulin-like growth factor-1. Because IGF-1 LR3 does not bind to IGF-1 binding proteins very well, it stays active up to 120 times longer than standard IGF-1. This leads to a longer half-life for the peptide and thus increased activity. IGF-1 LR3 boosts cell division and growth, speeds up fat metabolism, and increases muscle repair and growth by blocking myostatin. Recent research suggests that IGF-1 LR3 may also help improve lactation in mothers with young children.

Sequence: MFPAMPLSSL FVNGPRTLCG AELVDALQFV CGDRGFYFNK PTGYGSSSRR APQTGIVDEC CFRSCDLRRL EMYCAPLKPA KSA
Molecular Formula: C₄₀₀H₆₂₅N₁₁₁O₁₁₅S₉
Molecular Weight: 9117.5 g/mol
CAS Number: 946870-92-4

Cell Division

Like IGF-1, IGF1-LR3 is a strong trigger for cell division and growth. Its main effects are on connective tissues like muscle and bone, but it also boosts cell division in liver, kidney, nerve, skin, lung, and blood tissues. IGF-1 is best seen as a maturation hormone because it not only boosts cell growth but also cell specialization. IGF-1 causes cells to mature so they can perform their specific functions.

Unlike IGF-1, IGF1-LR3 stays in the bloodstream for long periods. This makes IGF1-LR3 a much stronger molecule. A dose of IGF1-LR3 provides about three times as much cell activation as a similar dose of IGF-1. Note that IGF1-LR3 and all IGF-1 versions do not make cells larger (hypertrophy), but instead boost cell division and growth (hyperplasia). For muscle, IGF1-LR3 does not make muscle cells bigger, but it does increase the total number of muscle cells.

Fat Metabolism and Diabetes

IGF1-LR3 boosts fat metabolism indirectly by binding to both the IGF-1R receptor and the insulin receptor. These actions increase glucose uptake from the blood by muscle, nerve, and liver cells. This leads to an overall drop in blood sugar levels, which then triggers fat tissue and the liver to break down glycogen and triglycerides. Overall, this creates a net decrease in fat tissue and a net energy use (net catabolism).

Given its role in lowering blood sugar levels, it should not surprise that IGF1-LR3 reduces insulin levels and the need for outside insulin in diabetes. In most cases, this means a 10% drop in insulin needs to keep the same blood sugar levels. This fact may help scientists understand how to lower insulin doses in people with reduced insulin sensitivity and may even offer insight into preventing type 2 diabetes.

Impairs Myostatin

Myostatin (also known as growth differentiation factor 8) is a muscle protein that mainly blocks the growth and specialization of muscle cells. While this function is important to prevent uncontrolled growth and ensure proper healing after injury, there are times when blocking myostatin could be helpful. Stopping myostatin from working could be useful in conditions like Duchenne muscle dystrophy (DMD) or in people who lose muscle during long periods of not moving. In these cases, blocking this natural enzyme could help slow muscle breakdown, keep strength, and reduce health issues.

In mouse models of DMD, IGF1-LR3 and other IGF-1 versions can counteract myostatin's negative effects to protect muscle cells and prevent cell death. IGF1-LR3, thanks to its long half-life, is highly effective at countering myostatin and seems to work by activating a muscle protein called MyoD. MyoD is the protein normally turned on by exercise (like weight lifting) or tissue damage and is responsible for muscle growth.

Longevity Research

IGF1-LR3 promotes tissue repair and maintenance throughout the body, making it a protective molecule against cell damage and aging effects. Research in cows and pigs shows that IGF1-LR3 administration may help offset cellular aging effects. Ongoing research in mice aims to see if IGF1-LR3 might help prevent a wide range of conditions like dementia, muscle wasting, and kidney disease. This research shows that IGF-1 administration can prolong life and reduce disability.

Glucocorticoid Signaling

Glucocorticoids, mainly made by the adrenal glands, are important clinical drugs used to control pain and reduce inflammation in autoimmune diseases, brain injury, cancer, and more. Unfortunately, glucocorticoids have several unwanted side effects like muscle wasting, fat gain, and bone density loss. There is interest in using IGF1-LR3 to reduce glucocorticoid side effects and allow for more effective therapy.