Resveratrol a molecule found in the skin of red grapes, may offer some protection against diabetes.

     Dr. Roberto Coppari, (Assistant Professor of Internal Medicine at UT South Western Medical Centre and senior author of the study.) noted that the brain plays an important role in mediating resveratrol's anti-diabetic actions, and it does so independent of changes in food intake and body weight.

     For this study researchers selected mice and they injected resveratrol directly into the brain; another group received a saline-based placebo. All the surgically treated animals consumed a high-fat diet before and after the surgery. Dr. Coppari said the insulin levels of the animals treated with the placebo solution rose increasingly higher post-surgery. "That's a normal outcome because insulin sensitivity decreases the longer you keep an animal on a high-fat diet."

     Insulin levels in the mice given resveratrol, however, actually started to drop and were halfway to normal by the end of the five-week study period, even though the animals remained on a high-fat diet.

     The researchers wanted to know what happens when resveratrol acts only in the brain. Specifically, they investigated whether resveratrol injected in the brain activated a group of proteins called sirtuins, which are found throughout the body and thought to underlie many of the beneficial effects of calorie restriction. Previous animal research has shown that when these proteins are activated by resveratrol, diabetes is improved. In addition, drugs activating sirtuins currently are being tested as anti-diabetic medications in human trials.

     Dr. Coppari concluded that his study does not support the theory that consuming products made from red grapes, such as red wine, could alleviate diabetes. His team's findings conclude that the brain plays an important role in mediating the beneficial effects of resveratrol and that manipulation of brain sirtuins also may have other beneficial outcomes. "By knowing that the central nervous system is involved, pharmaceutical companies can begin to focus on developing drugs that selectively target sirtuins in the brain," he said.

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