2006年VOA标准英语-Scientists Develop Vaccine Against Weight Gain（在线收听）

By Jessica Berman
Washington
31 July 2006
 
It could be the dream of anyone who has spent years trying to lose weight. Scientists have developed a vaccine that causes and maintains weight loss. So far, the drug has only been tested in rats. But researchers say it has the potential to help millions of obese people worldwide who are at risk for early death.

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As anyone who has tried to lose a significant amount of weight knows, it can be hard to do.

In 1999, scientists found out why. They discovered ghrelin, a growth hormone that regulates appetite and energy metabolism. When people cut back on calories to try to lose weight, levels of ghrelin increase dramatically to maintain existing fat stores. It's the body's way of preventing starvation. Ghrelin drops when eating returns to normal.

Since the discovery, researchers have been trying to find a way to manipulate ghrelin so people can lose weight.

Diagram of how vaccine works (Photo courtesy Michael Meijler)   
  
A team of researchers led by Kim Janda at Scripps Research Institute in La Jolla, California have taken a novel approach to harnessing ghrelin. Janda says they made a vaccine that prompts the body's immune system to attack ghrelin as if it were bacteria.

"And so what we had to do was make molecules such that the immune system was in a sense tricked into recognizing ghrelin as being foreign, and thus bind to it and not allow it to get to the central nervous system and get to the hypothalamus where it can impart its properties," he explained.

Researchers developed three versions of the vaccine and applied them to rats, which were given the same amount of food and drink. Janda says two of them showed promise.

The rats in this study were a normal weight. In the future, Janda says, researchers plan to look at how well the vaccine works on obese rats.

"I think what this does is it shows a new avenue of research," he said. "I'm not saying it's going to be a cure all to everything. But it will put (make) people start thinking about using this type of approach for treating a problem that's basically become an epidemic."

  
  
Janda says he could rush the vaccine through the approval process within a year but first wants to make sure it is safe.

The article, "Vaccination against weight gain," is published in the journal proceedings of the National Academy of Sciences.