New Health Benefits Of Exercise, An international team of scientists has isolated a natural hormone or chemical messenger in muscle cells that triggers a quantity of the important health benefits of exercise. They have named it "irisin", after the Greek messenger goddess, & think it is a promising candidate for developing drugs to treat diabetes, obesity & perhaps even cancer.
For this study, the researchers used lab cultures and mice to show that irisin has a direct and powerful effect on white adipose tissue, the subcutaneous deposits of white overweight that store excess calories and contribute to obesity.
When humans and mice exercise, levels of irisin in the muscles go up, and this switches on a gene that triggers conversion of white overweight in to "good" brown overweight.
Brown overweight is called "good" overweight because it burns off more excess calories than exercise alone. Since researchers like Spiegelman discovered this, there has been a surge of interest in it.
A similar thing happened when the researchers injected modest amounts of irisin in to sedentary mice that were overweight and pre-diabetic It mimicked the effect of exercise, except that their energy expenditure went up "with no changes in movement or food intake".
Adult humans don't carryover much brown overweight, while kids have much more, possibly a hangover from when our evolutionary ancestors used to hibernate, like lots of mammals descended from those ancestors do today.
As well as triggering the conversion of white overweight in to brown overweight, the researchers showed that irisin improved glucose tolerance in mice kept on a high-fat diet. Improved glucose tolerance is a key indicator of metabolic health, and the better a person's metabolic health, the lower their risk of developing cardiovascular diseases and diabetes.
He and his colleagues conclude:
The mice developed this improved glucose tolerance with ten days of treatment, and they also lost a small amount of weight. Spiegelman thinks the effect might have been greater if the treatment had lasted longer.
"Irisin could be therapeutic for human metabolic illness and other disorders that are improved with exercise."
However, Spiegelman warns that this does not insinuate people will be able to forego the gym and build muscle by taking irisin supplements. The hormone doesn't appear to work like that: it might stimulate conversion of white overweight in to brown overweight, and increase "thermogenesis" (burn off calories), but it doesn't make muscles stronger.
Because irisin is a natural substance and the mouse and human forms are the same, Spiegelman reckons clinical testing of a drug based on the protein could be happening in the next years.
As they predicted, since they kept the irisin doses to within levels that would usually occur with exercise, the researchers said they observed no poisonous or side effects.
The discovery has already been licensed for drug development to Ember Therapeutics, a company co-founded by Spiegelman.
Meanwhile, the team is exploring the hormone's other potential benefits, not only in treating diabetes, insulin resistance, and obesity, but also neurodegenerative diseases like Parkinson's.
Spiegelman says drugs based on irisin may have potential to prevent and treat cancer as well, in the light of growing proof that lack of physical activity and obesity contributes to its development.
