U.S. researchers have developed an anti-obesity vaccine that significantly slowed weight gain and reduced body fat in rats without affecting their appetites, suggesting a whole new approach to weight loss.
The target of this vaccine is
ghrelin, a recently discovered hormone that decreases energy expenditure and fat breakdown, according to medai reports Wednesday.
Secreted primarily by the stomach, ghrelin can help regulate appetite, metabolism and weight.
Ghrelin levels rise before a meal, putting the brakes on calorie burning and fat breakdown, then decline after a person eats. The hormone promotes weight gain and fat storage.
Researchers created three ghrelin-recognizing antigens -- proteins that elicit an immune reaction, in order to drcrease the hormone's activity.
When researchers gave shots of antigens to mice, they found that two of the antigens were able to bind to the active form of ghrelin, which then triggered the animals' immune systems to produce antibodies against the hormone.
"We have enabled the immune system to recognize a molecule that it ordinarily won't recognize," explained study author Kim D. Janda, a professor of the Scripps Research Institute in La Jolla, California.
Despite having free access to food and eating as much as their unvaccinated mates, the immunized rats gained less weight and boasted leaner, less flabby physiques.
That the weight effects came without diet changes was a surprise, said Janda.
It means that the ghrelin vaccine acted on metabolism, and not appetite, he explained.
A lot of basic work must be done before the Scripps obesity vaccine will be tried in humans, Janda said. "We're going to look at some different flavors of antibodies, see how they work, and then try them in animals," he said. Enditem
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