The drug chemically triggers a gene switch called PPAR-delta which in turn activates the same fat-burning process that occurs during exercise.
According to lead researcher Dr. Ronald Evans of the Salk Institute in San Diego, the same effect could occur in humans.
The potential weight-loss drug when it was used on mice in the form of a liquid or powder, revved up their cellular metabolism in much the same way as heavy physical activity.
Evans says the drug protected the mice against weight gain on high-fat and high-caloric diets and enabled them to exercise twice as long, turning them into "marathon mice.
Evans says the drug has potential for use with people.
The pill is intended to prevent disease rather than build muscles and could hopefully be used to treat people at risk of obesity-related diseases such as diabetes and could present a medical solution for people who must lose weight.
The pill could also offer an alternative to those who for whom diets and exercise do not work or are unable to lose enough weight that way.
There have been diet pills on the market for many years but they have significant side effects and are not always effective.
Although the drug could well become an 'exercise pill', experts say it is unlikely to provide all the benefits of a real physical exercise programme.
Evans says the drug would be more effective in the context of a healthy diet and exercise and would then offer the maximum benefit.
Nutritionists have expressed caution and say though exciting, the research is very preliminary and it remains to be seen if it can translate into something useful for humans.
The Salk Institute team presented their work this week at Experimental Biology 2007 in Washington D.C.
Dr. Prockop believes these results suggest possible new treatments for people with diabetes - there would be no problem getting healthy stem cells from their bone marrow , and especially for the 8 million people in the United States alone whose worsening diabetes is causing kidney failure.
Dr. Prockop also is pleased that the studies are explaining the mechanisms by which the cells work, in animals and in the more than 1,000 cardiovascular and other patients in the United States believed to be enrolled in clinical trials using these cells taken from their bone marrow. For such patients, the experimental treatment is their only option, but as the treatments are made available to larger numbers of people across a variety of different diseases it will be increasingly necessary to proceed carefully, says Dr. Prockop, and good basic science research will be critical. The Tulane Center for Gene Therapy is the only National Institutes of Health-designated center to distribute human stem cells (taken from healthy volunteers who give small samples of bone marrow from which to clone the cells) and from mice. Currently more than 270 scientists in the United States and other countries are working with the Tulane cells, meaning that research studies all are using well-standardized cells.
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