Vaccine Keeps Rats Slim, May Lead to Human Obesity Treatment
Aug. 1 (Bloomberg) -- A series of shots kept rats trim even as they chowed down, a finding that may lead to an obesity treatment for humans, a group of scientists reported.
Researchers vaccinated 17 rats, tricking their bodies into rendering a protein linked to weight gain ineffective and causing the rats to put on less weight than untreated animals. Humans have the same protein, according to the study published yesterday in the Proceedings of the National Academy of Sciences.
``This looks like a serious workable solution to the problem,'' Kim Janda, a researcher at the Scripps Research Institute said in an accompanying statement. ``We're not claiming our study answers the question of obesity treatment once and for all.''
Obesity among Americans has doubled since the late 1970s to around 31 percent of the population, and about 65 percent of the nation is now considered overweight, according to the U.S. government. Currently, two prescription diet drugs on the market, Abbott Laboratories' Meridia and Roche Holding AG's Xenical, have side effects that limit their use. Glaxo is planning to sell Xenical as a non-prescription treatment, branded as Alli.
In the study, three groups of rats each were repeatedly given different vaccines against the protein, called ghrelin. They ate normally, and once the vaccination started working, they gained less weight and less body fat than animals which hadn't been immunized. This means their bodies had become less effective at metabolizing food.
The animals whose blood showed the vaccine working most effectively gained the least amount of weight, about 0.8 grams a day, compared to a weight gain of around 1.6 grams for the control group.
Diets, As Well
The vaccination was effective when the rats ate low-fat, low-energy, ``less palatable'' diets, the researchers said. It may not reverse obesity, as high-fat, energy-dense ``Western'' diets could render the shot ineffective, as could corpulence itself, the researchers said.
Ghrelin, which was only discovered seven years ago, is thought to be the body's evolutionary response to fluctuating food supplies, making those genetically predisposed to store fat more likely to survive.
Over the years, demand by doctors has been high for even moderately effective diet drugs because obesity is so closely tied to diabetes, heart disease, stroke, cancer and arthritis. An adult male 20 percent over the maximum desirable weight for his height is considered obese, U.S. guidelines say.
Sanofi-Aventis SA may introduce the weight loss drug Acomplia in the U.S. in the second half of the year. Glaxo is planning to sell Roche's Xenical as a non-prescription treatment, branded as Alli.
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