The study, by researchers at the Chinese Academy of Sciences in Shanghai, showed that resveratrol activates an enzyme called SIRT1. This enzyme, in turn, suppresses the activity of a molecule called PTP1B, which ordinarily works to decrease insulin activity. SIRT1 levels were reduced in the animals’ insulin-resistant cells. Increasing SIRT1 activity with resveratrol improved insulin sensitivity by acting on PTP1B.
“When you suppress PTP1B, insulin activity improves,” said Young-Bum Kim, an assistant professor of medicine at Beth Israel Deaconess Medical Center in Boston, one author of an accompanying editorial in the journal.
“SIRT1 has a variety of functions in the body,” Kim said. “Now we can move on to other tissues, such as the brain. It is possible that regulating the hypothalamus with SIRT1 can prevent diet-induced obesity.”
That is clearly a long-term goal, said Janice M. Zabolotny, an instructor in medicine at Beth Israel Deaconess, and the other author of the editorial.
“But it can make animals want less food and lower body weight,” she said. “By activating SIRT1, you could block the expression of PTP1B and get the same hopeful benefit. Further studies are needed by other researchers and on different tissues in animals,” Zabolotny said.
One striking finding was that much lower levels of resveratrol than in previous trials were able to increase the animals’ sensitivity to insulin.
The study is published in the October issue of Cell Metabolism.