for National Geographic News
Scientists say they've made a cool discovery about living longer.
Mice genetically engineered to have lower body temperatures live substantially longer than normal mice, researchers report in tomorrow's issue of the journal Science.
The newfangled mice are only slightly cooler than standardjust 0.5 to 0.9 degree Fahrenheit (0.3 to 0.5 degree Celsius), an effect that occurs only during waking hours.
But the temperature drop significantly increases the rodents' life spans, scientists say. Altered male mice live 12 percent longer on average, while females live 20 percent longer than regular mice.
"We've demonstrated that a modest but prolonged reduction of core body temperature can contribute to increased longevity," said lead study author Bruno Conti, a biologist and neuroscientist at the Scripps Research Institute in La Jolla, California.
(See a National Geographic magazine feature on "The Secrets of Longevity.")
To create the "cool mice," investigators used genetic engineering to fool the rodents' central thermostat, which is found in the hypothalamus region of the brain.
By targeting a specific protein, the scientists caused a small cluster of neurons to heat up, duping the nearby thermostat to turn down the rodents' body heat.
Despite lower body temperatures, the mice appear to be as physically active as, and eat the same amount of food as, normal mice.
Precisely why these cool mice live longer remains unclear, investigators say. But they suspect the rodents produce fewer free radicals over time.
The chemical by-products of metabolism, free radicals damage DNA and other cell structures, an erosion linked to disease and aging.
SOURCES AND RELATED WEB SITES