Mere rodent turns into Mighty Mouse

Increasing the activity of a single gene turns a mere rodent into Mighty Mouse, according to a new study.

California scientists have genetically engineered an animal that has more muscle, less fat and more physical endurance than their littermates. The mice go twice as far as expected. They also seem protected against the inevitable weight gain that follows a high fat, high calorie diet.

"We were quite surprised," said Ronald M. Evans, a Howard Hughes Medical Institute investigator at the Salk Institute in La Jolla, Calif. "Most people think that increased endurance comes from training. But we've been able to re-create this entire exercise network by increasing the activity of a single protein."

Evans said that the findings could have implications for human athletes and others who shy away from exercise despite the known benefits for the cardiovascular system, the muscles and bones, and even the brain. "While it could be used for patients who can't exercise, it could also be abused by athletes to enhance performance," said Evans, writes Newsday.

One of the questions for the future is studying the impact this has on longevity," he said. "So far, there are no side effects other than that they are resistant to weight gain. They are fertile and they are able to give rise to the next generation of long-distance runners."

Other studies have led researchers to believe an "exercise pill" is possible. In 2002, researchers published a study in the journal Science showing that increasing production of an enzyme called calmodulin-dependent protein kinase or CaMK could have similar effects.

"There are several studies that have reported fiber-type switches," Evans said. "What is different about this one is we looked at what the consequences of that fiber-type switch are."

While Evans and colleagues used genetic manipulation, they said using a pill to create a similar effect is already possible.

They gave normal mice an experimental drug called GW501516 that also activates PPAR-delta. The drug is being developed by GlaxoSmithKline to treat people with fat metabolism disorders, informs Reuters.

"This may represent a significant role in exercise endurance," said Glaxo spokesman Rick Koening. After Evans' latest work was published on Monday, Koenig added a cautionary note: "We do not condone the pharmaceutical enhancement of athletes.", says Associated Press.