Washington - Scientists know that having colder blood tends to make animals live longer, but they don't know why.
Researchers at the University of Michigan have identified a “programme” in the genes that might help answer the question and also provide a clue about the longevity of humans exposed to cold.
The genetic programme promotes longevity of roundworms in cold environments. The scientists say it also exists in warm-blooded animals, including humans.
Scientists had long assumed that animals live longer in cold environments because of a passive thermodynamic process, reasoning that low temperatures reduce the rate of chemical reactions and thereby slow the rate of aging.
“But now, at least in roundworms, the extended lifespan observed at a low temperature cannot be simply explained by a reduced rate of chemical reactions,” Shawn Xu said. “It's in fact an active process that is regulated by genes.”
Xu found that cold air activates a receptor known as the TRPA1 channel, found in nerve and fat cells in nematodes. TRPA1 then passes calcium into cells. A resulting reaction ultimately reaches a gene associated with longevity.
Mutant worms that lacked TRPA1 did not live longer. They actually had shorter life spans at lower temperatures.
“This raises the intriguing possibility that exposure to cold air - or pharmacological stimulation of the cold-sensitive genetic programme - may promote longevity in mammals,” said Xu, a faculty member at the University of Michigan's Life Sciences Institute.
The research was published online this month in the journal Cell. It was announced at the annual meeting of the American Association for the Advancement of Science in Boston.
Researchers long have known that lowering the core body temperature of warm-blooded animals, such as mice, by 0.5 degrees Celsius can extend lifespan by 20 percent, but it hasn't been practical for humans to attempt to lower the core body temperature, Xu said.
Because the mechanisms identified by Xu and his collaborators also exist in a range of other organisms, including humans, the research suggests that a similar effect might be possible in them.
The study also links calcium signaling to longevity for the first time and makes a novel connection between fat tissue and temperature response.
Xu said in addition to cool temperatures, the spicy condiment wasabi activates TRPA1 as well and feeding wasabi to nematodes increases their life spans.
“Maybe we should be going to sushi restaurants more often,” he said. - Sapa-dpa