Washington, Aug 1 : Hitting the gym twice in a day to fight that extra flab? Well, you can now forget the painful exertion, courtesy the treadmills and spin classes, for a group of researchers have identified a pill that tricks the muscles into thinking they have been working out furiously.
Scientists at the Salk Institute for Biological Studies have identified two signaling pathways that are activated in response to exercise and converge to dramatically increase endurance.
The team of scientists, led by Howard Hughes Medical Investigator Ronald M. Evans, Ph.D., a professor in the Salk Institute's Gene Expression Laboratory report in the July 31 advance online edition of the journal Cell that simultaneously triggering both pathways with oral drugs, turned laboratory mice into long-distance runners and conferred many of exercise's other benefits.
In addition to their allure for endurance athletes, drugs that mimic the effects of exercise have therapeutic potential in treating certain muscle diseases, such as wasting and frailty, hospital patients unable to exercise, veterans and others with disabilities as well as obesity and a slew of associated metabolic disorders where exercise is known to be beneficial.
Previous work with genetically engineered mice in the Evans lab had revealed that permanently activating a genetic switch known as PPAR delta turned mice into indefatigable marathon runners.
In addition to their super-endurance, the altered mice were resistant to weight gain, even when fed a high-fat diet that caused obesity in ordinary mice. On top of their lean and mean physique, their response to insulin improved, lowering levels of circulating glucose.
"We wanted to know whether a drug specific for PPAR delta would have the same beneficial effects," says Evans.
"Genetic engineering in humans, commonly known as gene doping when mentioned in connection with athletic performance, is certainly feasible but very impractical," adds Evans.
An investigational drug, identified only as GW1516 (and not commercially available), fit the bill. When postdoctoral researcher and lead author Vihang A. Narkar, Ph.D., fed the substance to laboratory mice over a period of four weeks, the researchers were in for a surprise.
"We got the expected benefits in lowering fatty acids and blood glucose levels but no effect, absolutely none, on exercise performance," says Narkar.
Undeterred, he put mice treated with GW1516 on a regular exercise regimen and every day had them run up to 50 minutes on a treadmill.
Now the exact same drug that had shown no effect in sedentary animals improved endurance by 77 percent over exercise alone and increased the portion of "non-fatiguing" or "slow twitch" muscle fibers by 38 percent.