T Nation

Mechano Growth Factor


Has anyone out there heard of this IGF-1 isoform? Prof. Goldspink seems to be the only guy working on it and Novartis seems to have taken an interest, I'm wondering if the trainers/athletes are paying attention. You can get gobs of it cheaply and everything I hear about it (mostly Goldspink) is Holy Grail type of stuff (25% increases in local muscle mass, 20% increases in strength both in less than 10 wks.)


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Short answer:
No, this isn't regular pharmaceutical IGF-1 I'm talking about, it's an isoform (same gene, different protein).

Long answer:
Muscle has an intrinsic ability to change its mass and phenotype in response to activity. This process involves quantitative and qualitative changes by alternative splicing in gene expression, including that of the myosin heavy chain isogenes that encode different types of molecular motors.

This, and the differential expression of metabolic genes, results in altered fatigue resistance and power output. The regulation of muscle mass involves autocrine as well as systemic factors. We have cloned the cDNAs of local and systemic isoforms of insulin-like growth factor-I (IGF-I) from exercised muscle. Although different isoforms are derived from the IGF-I gene, the RNA transcript of one of them is only detectable following injury and/or mechanical activity. Thus this protein has been called mechano growth factor (MGF).

Because of a reading-frame shift, MGF has a different 3' sequence and a different mode of action compared
with systemic or liver IGF-I. Although MGF has been called a growth factor, it may be regulated as a local repair factor.

-G. Goldspink, Gene Expression In Skeletal Muscle, Biochemical Society Transactions (2002) Volume 30, part 2 285-290.


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Generally correct, to call it "IGF-1 from exercised muscle" is a bit simplistic, but you've got the gist. The current pharmaceutical crop is liver or systemic IGF-1.

I'm not sure about the dose (a decent dose of hGH is 25 ug), but 100ug for $100 is a pretty reasonable/average price.


Maybe I should've been more explicit, the best analogy I can think of is my brother and I. We both came from the same genetic material, but he's 6'1" 185# and can run for miles. I, on the other hand, am 5'8" 215# and can't run 800m. The difference between us is that we got different snippets of the same genetic material, it's the same with IGF1 and MGF. IGF1 has effects on internal organs, smooth, cardiac, and skeletal muscle, MGF has shown to have little/no effect on anything but skeletal muscle and has shown some stimulatory effect. The data indicates that it is responsible for initiating satellite cell differentiation (unlike myostatin which stops this differentiation, MGF drives it). Also, Goldspink hasn't said as much (that I know of) but in his data, he indicates that this is THE (preeminent) molecule linking muscle damage to repair/hypertrophy. I just don't get why no one knows/has heard of/uses this molecule.