Cool mice live long and prosper
Lowering the body temperature of mice without limiting the amount of food they eat can prolong their lives, a new study shows.
According to a study in the latest issue of the journal Science, female mice live up to 20% and males 12% longer.
"Our study shows it is possible to increase life span in mice by modest but prolonged lowering of core body temperature," says Bruno Conti, an associate professor at Scripps Research Institute in California, who led the study.
But it will take a long time to determine if the same applies to humans, the researchers say.
Scientists know that body temperature and ageing are linked in reptiles and other cold-blooded animals.
They also know that the life span of warm-blooded creatures can be extended by reducing the number of calories they eat, which in turn lowers the body temperature by slowing down the metabolism.
So, the researchers carried out the study to determine whether calorie reduction is indeed responsible for extending animals' life, with a lowering of the body temperature being a secondary effect, or whether the latter is actually the cause of the increased longevity.
They found that the increased life span is due to the lower body temperature, independent of the amount the mice eat.
Cooling down a mouse
In the study, the researchers lowered the body temperature of the mice 0.3-0.5°C by genetically manipulating them.
They created mice that produce large amounts of a type of protein in the brain. This acts to heat up the brain's thermostat, a region of the hypothalamus. And the thermostat responds by reducing the core body temperature.
What about humans?
Professor Clifford Saper from the Beth Israel Deaconess Medical Center says that if core body temperature is critical in extending the life spans of mammals, "one might wonder whether 37°C is indeed the optimal body temperature for humans, and why evolution has not selected for a lower body temperature and longer life span".
But before we look at manipulating how long humans live, he says "one would certainly want to know the consequences of hypothermia before pursuing it as a way to increase life span".