美國之音2007標準下半年AScientists Find Link Between Stress and Obesit

所屬教程:美國之音2007標準下半年A

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Scientists Find Link Between Stress and Obesity

By Carol Pearson
Washington
16 July 2007

Scientists have known for a long time about a link between chronic stress and obesity. Now researchers at Georgetown University in Washington, D.C., recently have made what they call a "stunning" advance.

"The stunning thing is that we have actually discover(ed) the exact mechanism by which people get fat when they are stressed and eat (a) high fat, high sugar diet. And by knowing the mechanism, we can now manipulate the fat."

Dr. Zukowska and her colleagues put laboratory mice under the same type of stress they would experience in the wild such as meeting up with a more aggressive mouse. They then fed these mice an equivalent of a fast food diet. The mice became obese.

Dr. Zukowska and her colleagues found an increased amount of a chemical called neuropeptide Y in these mice. This chemical is activated by stress and helps stimulate the growth of fat cells. "So now you have a constellation of more vessels supplying nutrients to the fat, fat cells multiplying and growing."

And the fat in mice grew around their middle, just as it does in humans. Midsection fat is the most dangerous kind because it affects the heart and liver, causing heart disease, adding to cholesterol levels, high blood pressure, diabetes and stroke. But the researchers found they could block the fat-causing neuropeptide Y, or N.P.Y., for short, with a different chemical.

"We found that in addition to reducing the abdominal fat, we also improved the metabolism. And all those problems that the mice had such as hypertension and glucose intolerance and fatty liver, it became markedly reduced or prevented" .

What is more, N.P.Y. seems to work in the human body much like it does in mice. If so, Dr. Zofia Zukowska says it would be a major advance in the battle against obesity. "We think we not only are able to manipulate fat composition and maybe make the body more beautiful, but also actually treat obesity and metabolic syndrome."

The researchers say many more studies need to be done before human trials can begin.