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September 7, 2008 9:54 PM
By Maggie Fox
WASHINGTON - Researchers who genetically engineered "marathon mice" that could run for hours have found two pills that can mimic the effects - and they have already developed a test for the drugs in case athletes try to cheat with them.
The drugs reproduce many of the biological benefits of exercise, helping cells burn fat better and boosting endurance, said Ronald Evans, a Howard Hughes Medical Institute researcher at the Salk Institute for Biological Studies in California.
One of the pills may some day help people enhance their exercise or training, while the other might be more suited for couch potatoes who need to kick-start themselves, Evans and
colleagues reported in the journal Cell.
"If you like exercise, you like the idea of getting more bang
for your buck," Evans said. "If you don't like exercise, you
love the idea of getting the benefits from a pill."
In 2004, Evans and his colleagues genetically engineered
mice by tweaking a gene called PPAR-delta, a master regulator
of different genes. Gene-engineered mice could run twice as far
as normal mice and stayed lean even when fed a high-fat diet.
The next step was to find a drug that might mimic these
effects.
Evans tested a compound called GW1516, one of a family of
compounds that researchers are looking at as obesity and
diabetes drugs. But even though it affected the genes of the
mice, it did not affect their metabolism.
"There was no change at all in running performance. Nothing
- not even a per cent," Evans said in a statement.
MIMICKING LIFE
Then the researchers thought about what happens in real
life.
"If you're out of shape - and most of us are - and you
want to change, you have to do some exercise. The way we
reprogram muscle in adults is by training."
So they trained the mice while some were on the drug and
others were not.
All the mice became more athletic but those given GW1516
ran 68 per cent longer than those that had only done the
exercise training. "The dramatic effect of the drug was
stunning," Evans said.
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