Diet‐induced obesity and insulin resistance are associated with brown fat degeneration in SIRT 1‐deficient mice

OBJECTIVE: Recent studies have revealed that SIRT1 gain-of-function could promote adipose tissue browning for the adaptive thermogenesis under normal diet. This study investigated the role of SIRT1 loss-of-function in diet-induced obesity and insulin resistance and the mechanism involved in adipose tissue thermogenesis. METHODS: Male SIRT1(+/-) and wild-type (WT) mice were fed with a high-fat diet (HFD) for 16 weeks to induce obesity and insulin resistance, while mice on a chow diet were used as lean controls. The phenotype data were collected, and different adipose tissue depots were used for mechanism research. RESULTS: Compared with WT mice, SIRT1(+/-) mice exhibited increased adiposity and more severe insulin resistance with less thermogenesis under HFD challenge. Strikingly, SIRT1(+/-) mice displayed an exacerbated brown adipose tissue (BAT) degeneration phenotype, which was characterized by lower thermogenic activity, aggravated mitochondrial dysfunction, and more mitochondrial loss. In addition, SIRT1(+/-) mice showed aggravated inflammation and dysfunction in epididymal adipose tissue after HFD intervention, which also contributed to the systemic insulin resistance. CONCLUSIONS: Diet-induced obesity and insulin resistance are associated with BAT degeneration in SIRT1-deficient mice, which further underlined the beneficial role of SIRT1 in obesity-associated metabolic disorders.