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Nerves are key to longevity effect

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2:27pm, June 26, 2007
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The brain may be involved in triggering the life-extending effects of a calorie-restricted diet, new research shows.

Scientists first observed in the 1930s that feeding animals about 30 percent fewer calories than normal extended the animals' life spans by 30 to 40 percent. The effect emerged in several animal species, including roundworms, mice, dogs, and monkeys, and the cause seemed to be physiological changes in muscle and fat tissues.

But in roundworms, pairs of neurons in the animals' heads play a critical role too, according to research by Nicholas A. Bishop and Leonard Guarente of the Massachusetts Institute of Technology. Destroying the neurons with a laser prevented calorie restriction from having any effect on the worms' longevity, the scientists report in the May 31 Nature.

"It's the first indication that the brain is going to send that initial signal for longevity in response to calorie restriction," Guarente says. He adds that his team's next step is to determine whether hormones released by these neurons are responsible for the longevity effect.

The human brain area comparable to these neurons is the hypothalamus, Guarente says. However, life extension from calorie restriction has never been unambiguously demonstrated in people.

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