Cool down ? you may live longer

11:20 03 November 2006
NewScientist.com news service
Roxanne Khamsi

The refrigerator is used to lengthen the life of your food, and a new study suggests a similar principle could prolong your life, too.

Researchers have found that lowering the body temperature of mice by just 0.5°C extends their lifespan by around 15%. In the future, people might be able to take a drug to achieve a similar effect on body temperature and enjoy a longer life, they say.

The only previously proven method of significantly increasing the lifespan of an animal has been through a restricted calorie diet.

Bruno Conti at Scripps Research Institute in La Jolla, California, US, and colleagues designed genetically engineered mice with a specific brain-cell defect in a region called the lateral hypothalamus. The defect forces brain cells into "overdrive", causing the region to heat up and become warmer than in a normal mouse.
Female benefit

Since, in mice, the lateral hypothalamus sits just 0.8 millimetres away from the brain’s body-temperature-controlling thermostat – called the preoptic area – it was tricked into thinking its body temperature was too high, causing the mouse to cool down.

The average body temperature of the genetically engineered mice was about 0.6°C lower than that of their control counterparts.

Even this small decrease in body temperature appeared to have a noticeable effect on lifespan, extending their lives by 12% to 20%. And the decrease in body temperature extended the lifespan of female mice more than male mice, the team found, although they are unsure why.
Free radicals

Caloric restriction, another method shown to extend animals’ lives, also causes a decrease in body temperature, Conti notes. In his study, both groups of mice ate about the same amount. In fact, the genetically engineered male mice ended up about 10% heavier than the normal male mice.

Conti says the findings show it is the lowering of body temperature – and not necessarily the consumption of fewer calories – that plays the most important role in extending lifespan.

This may be because the body burns less fuel when it is at a lower temperature, which results in the production of fewer free-radical compounds that damage cells and promote the wear and tear of ageing. Previous studies have shown that worms and fish that have decreased body temperatures live longer.

Conti says that in the future people might be able to take a drug that specifically targets the preoptic “thermostat” area in their brains to trick the body into cooling down slightly. Coming up with such a drug “will be very challenging”, but he hopes it would allow people to live longer without cutting back on the calories.

Journal reference: Science (DOI: 10.1126/science.1132191)