Making Mice Fat or Thin with an Injection

Stressed mice get fat, according to a study out of GeorgetownUniversity Medical Center. And now they know the mechanism that doesit; in fact, they can manipulate that mechanism to make the micefat, or they can block the mechanism and keep the mice from gettingfat no matter how stressed they may be.

Dr. Zofia Zukowska, who led the study, stressed out her mice for twoweeks by making them stand in cold water or forcing them to face anaggressive alpha mouse. She found that the stressed mice, when feda high fat "junk food" diet, gained twice as much fat as expectedfrom their intake, all of it around their belly.

Not only did the stressed mice get twice as fat as non-stressedmice on the same diet, but they also showed signs of metabolicsyndrome, including glucose intolerance, high blood pressure,inflamed blood vessels, and fat in their livers and muscles.

The researchers not only used stress to make the mice fat; they alsodiscovered, and then played with, the mechanism by which stressleads to weight gain in mice. Stress activates a neurotransmittercalled Neuropeptide Y (NPY) to bind to its receptor, calledNeuropeptide Y Receptor (Y2R), in fat tissue, causing the fat cellsto swell in both size and number and leading to apple-shaped obesityand metabolic syndrome.

By injecting mice with NPY, the researchers were able to generatefat in mice wherever they wanted it. And by injecting Y2R blockerinto the mice's abdominal fat, they were able to shrink the fataccumulation by fifty percent in only two weeks and eliminate themetabolic syndrome.

Plastic surgeons, of course, are excited about eventually using anNPY injection to build fat in wrinkled lips and using a Y2Rinjection to melt away fat without surgery. That peculiar prospectaside, the findings should comfort those of us who are stressed outand seem to grow fat out of all proportion to the amount we eat. Inaddition to eating right, activities that lower stress may help getrid of that spare tire.

Source: EurekAlert
Georgetown Medical Center news release

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