Reducing body temperature extends life span of mice

WASHINGTON, Nov 3 (Reuters) Lowering the body temperature of mice extended their life span by up to 20 per cent, said scientists studying how to prolong life, but they said it was impractical to do this with people.

Researchers previously found that the life span of warm-blooded animals could be lengthened by cutting calories consumed.

But the mice used in the new study, published in the journal Science, were permitted to eat as much food as they wanted while their core body temperature was lowered modestly.

''We are showing that there is a way to obtain the benefit on life span and aging that are known to be conferred by calorie restrictions without necessarily undergoing calorie restrictions,'' lead researcher Bruno Conti of the Scripps Research Institute in La Jolla, California yesterday said in an interview.

Scientists have known of a link between body temperature and aging in cold-blooded animals, but this was the first study to show body temperature changes impact how long warm-blooded animals live.

Animals involved in the earlier studies involving calorie restriction experienced lower body temperatures as a side effect.

Researchers set out to discover whether it was the actual calorie restriction that was responsible for added longevity, with lower body temperature being incidental, or whether reduced body temperature itself was a key factor in life span.

Conti and his colleagues reduced mouse body temperatures by focusing on the hypothalamus, a brain structure that acts as the body's thermostat.

They found that mice with reduced body temperatures lived longer than those with normal temperatures. Median life span in females was extended by about 20 per cent and in males by about 12 per cent.

The male mice also weighed roughly 10 percent more, possibly due to the diminished energy needed to maintain a lower body temperature, researchers said.

But people wanting to live a decade or two longer are going to have to find another way, at least for now.

Conti said using the same technique in people was ''technically feasible,'' but there is too little information on the safety of such an approach. ''I'm afraid it's not too practical at this point,'' Conti added.

Reuters SHB DB1100