研究表明 基因或是导致中年发福的原因
U.S. researchers said Tuesday that they have identified an enzyme that may play a central role in the development of obesity in mid-life. In two groups of mice being fed high-fat foods, those who received an inhibitor that blocked the enzyme had a 40 percent decrease in weight gain compared with those that did not receive the drug. The findings, published in the U.S. journal Cell Metabolism, could upend current notions about why people gain weight as they age, and could one day lead to more effective weight-loss medications. "Our society attributes the weight gain and lack of exercise at mid-life (approximately 30 to 60 years) primarily to poor lifestyle choices and lack of will power, but this study shows that there is a genetic program driven by an overactive enzyme that promotes weight gain and loss of exercise capacity at mid-life," said lead study author Jay H. Chung, head of the Laboratory of Obesity and Aging Research at the National Heart, Lung, and Blood Institute (NHLBI), part of the U.S. National Institutes of Health. Chung and his associates searched for biochemical changes that occurred in middle-aged animals that are equivalent to 45 years in humans. They found that an enzyme called DNA-dependent protein kinase, or DNA-PK, increases in activity with age. Further work showed that DNA-PK promotes conversion of nutrients to fat and decreases the number of mitochondria, tiny organelles in the cells that turn fat into energy to fuel the body. Mitochondria can be found in abundance among young people, but the numbers drop considerably in older people. Researchers know that decreased mitochondria can promote obesity as well as loss of exercise capacity. |