The dog in the photo is supermuscular because of naturally occurring mutations that silence both versions of the myostatin gene. Called bully whippets, these dogs are rarely champion racers. However, animals with one mutated and one normal version of the gene are more muscular than typical animals and are among the breed’s fastest racers. Credit: Stuart Isett, Polaris
Mice given the new drug show a 30 to 60 percent increase in muscle mass, and mice with a version of muscular dystrophy show increased grip strength, a standard measure of rodent strength. Preliminary results from primate studies show that the animals on the drug bulk up at similar rates to those seen in rodents. "Before I became involved with Acceleron, if someone had told me you could increase muscle mass by up to 60 percent in a month, I never would have believed it," says CEO John Knopf.
While it's not yet clear if similar rates will be seen in humans, high doses of anabolic steroids, which carry serious side effects, increase muscle mass by a maximum of 15 to 20 percent. And because myostatin is found only in muscle, knocking it out does not appear to have the adverse effects of broader-acting steroids.
Says Evans, "I think these drugs, perhaps used in combo with exercise, might have great potential in reversing the trend toward increasing obesity and decreasing muscle mass."
In the previous studies on the genes being set, the aging of muscles was actually stopped. This did not increase life expectancy but there would be less of the problems of someone old suffering serious reduction in muscle.
Results of experiments with adult mice who received injections of the gene into their muscles. The inoculations prevented muscle deterioration in mice as old as 2 years -- 80 years in human terms. The shots even regenerated muscle, restoring some of the lost strength and size.
Old mice regained 27 percent of muscle lost to age; younger mice experienced a 15 percent increase, Sweeney reported. "You build muscle mass and strength even without exercise," he says.
Netbook Technology News