french_muscle
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interesting....
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When IGF-I is bound to binding protein-3 (BP3), as it is in nature, it does not display these acute limitations. Furthermore, BP3 appears to be critical in the regulation of the release of IGF-I to target tissue sites, where the hormone is active only when needed. There is some confusion among athletes that IGF-1 binding proteins actually limit the effectiveness of IGF-1. In reality, IGFBP3 is necessary to prevent IGF-1 from being cleared from the system. IGFBP3 extends IGF-1's half-life from minutes to hours. BP3 is also a necessary part of the existing system which uses the binding protein and an acid labile subunit (ALS) which is broken down at target tissue, releasing the IGF-1 when and where it is needed.
So what is Somatokine? A company called Celtrix pharmeceuticals produces only one product, namely Somatokine. In fact, the company hasn’t even received FDA approval yet, though late phase testing is proving to be very promising (Data privately held by Celtrix). According to Celtrix feasibility studies looking at muscle function, muscle wasting, diabetes, osteoporosis, and cardiac function all show promise with minimal to insignificant side effects. Celtrix is gambling their entire financial future on this drug. Somatokine is simply an rhIGF-1 peptide complexed with the IGFBP3 protein and the ALS.
Until Somatokine or similar product becomes available, using isolated rhIGF-1 for muscle growth is simply impractical, ineffective, and certainly not cost effective. The only exception might be as a locally applied anabolic. In a study using rats (11), a relatively "unloaded" muscle, the anterior tibialis, was injection with 0.9 - 1.9 MICROGRAMS/kg/day of rhIGF-1 which then mimicked the effects of physically loading the muscle, increasing its mass by ~9% without exercise. There was an increase in protein content, cross sectional area and DNA content. The increase in muscle DNA is presumed to be a result of increased proliferation and differentiation of satellite cells which donate their nuclei upon fusion with damaged or hypertrophying muscle cells. Take note that the quantities of IGF-1 used in the injections were extremely small, much smaller than studies that have shown relatively poor results from administering IGF-1 systemically which range from 1.0 to 6.9 milligrams/kg/day.
Getting IGF-1 inside the muscle as apposed to in the blood has shown to be extremely anabolic in another exciting animal study using viral mediated gene therapy (12). In this study, a recombinant adeno-associated virus, directing overexpression of insulin-like growth factor I (IGF-I) in mature muscle fibers, was injected into the muscles of mice. The DNA that was originally in the virus was removed along with markers that stimulate immune response. DNA coding for IGF-1 was then put into the virus along with a promoter gene to ensure high rates of transcription. The results were dramatic causing a 15% increase in muscle mass and a 14% increase in strength in young adult mice, once again, without additional exercise. Obviously this technology is not going to be available to bodybuilders any time soon, nevertheless, it’s exciting to consider the possibilities.
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When IGF-I is bound to binding protein-3 (BP3), as it is in nature, it does not display these acute limitations. Furthermore, BP3 appears to be critical in the regulation of the release of IGF-I to target tissue sites, where the hormone is active only when needed. There is some confusion among athletes that IGF-1 binding proteins actually limit the effectiveness of IGF-1. In reality, IGFBP3 is necessary to prevent IGF-1 from being cleared from the system. IGFBP3 extends IGF-1's half-life from minutes to hours. BP3 is also a necessary part of the existing system which uses the binding protein and an acid labile subunit (ALS) which is broken down at target tissue, releasing the IGF-1 when and where it is needed.
So what is Somatokine? A company called Celtrix pharmeceuticals produces only one product, namely Somatokine. In fact, the company hasn’t even received FDA approval yet, though late phase testing is proving to be very promising (Data privately held by Celtrix). According to Celtrix feasibility studies looking at muscle function, muscle wasting, diabetes, osteoporosis, and cardiac function all show promise with minimal to insignificant side effects. Celtrix is gambling their entire financial future on this drug. Somatokine is simply an rhIGF-1 peptide complexed with the IGFBP3 protein and the ALS.
Until Somatokine or similar product becomes available, using isolated rhIGF-1 for muscle growth is simply impractical, ineffective, and certainly not cost effective. The only exception might be as a locally applied anabolic. In a study using rats (11), a relatively "unloaded" muscle, the anterior tibialis, was injection with 0.9 - 1.9 MICROGRAMS/kg/day of rhIGF-1 which then mimicked the effects of physically loading the muscle, increasing its mass by ~9% without exercise. There was an increase in protein content, cross sectional area and DNA content. The increase in muscle DNA is presumed to be a result of increased proliferation and differentiation of satellite cells which donate their nuclei upon fusion with damaged or hypertrophying muscle cells. Take note that the quantities of IGF-1 used in the injections were extremely small, much smaller than studies that have shown relatively poor results from administering IGF-1 systemically which range from 1.0 to 6.9 milligrams/kg/day.
Getting IGF-1 inside the muscle as apposed to in the blood has shown to be extremely anabolic in another exciting animal study using viral mediated gene therapy (12). In this study, a recombinant adeno-associated virus, directing overexpression of insulin-like growth factor I (IGF-I) in mature muscle fibers, was injected into the muscles of mice. The DNA that was originally in the virus was removed along with markers that stimulate immune response. DNA coding for IGF-1 was then put into the virus along with a promoter gene to ensure high rates of transcription. The results were dramatic causing a 15% increase in muscle mass and a 14% increase in strength in young adult mice, once again, without additional exercise. Obviously this technology is not going to be available to bodybuilders any time soon, nevertheless, it’s exciting to consider the possibilities.