Polydatin ameliorates diabetic cardiomyopathy via Sirt3 activation

Background: Diabetic cardiomyopathy is identified as cardiac ventricular dysfunction induced by an insulin shortage in diabetic patients. Our previous studies have shown that Polydatin (PD) alleviates cardiac dysfunction after myocardial infarction (MI) injury. Nevertheless, the mechanism by which PD regulates diabetic cardiomyopathy has not been reported. Methods: In this study, we demonstrated the effects and described the mechanisms of PD in diabetic cardiomyopathy in both adult mouse hearts and neonatal mouse cardiomyocytes. We injected streptozotocin (STZ) to induce the DM model in wild-type (WT) and Sirt3 knockout (Sirt3(-/-)) mice. Mitochondrial bioenergetics in diabetic mice were detected by measuring citrate synthase activity and ATP content. The extent of autophagy regulation by PD was investigated by detecting the levels of Beclin 1, Atg5, LC3 and p62. Results: Compared to the WT mouse hearts, hearts from the diabetic mice exhibited better cardiac function and a higher level of autophagy. Moreover, mitochondrial function in the diabetic mouse hearts was improved after PD treatment. However, PD treatment had no effect on the Sirt3 knockout diabetic mouse hearts. Additionally, PD increased autophagy flux in the cardiomyocytes that were cultured in high-glucose medium for 48 h. In addition, PD had no effects on the cardiomyocytes under high-glucose conditions when we down-regulated Sirt3. Conclusions: Altogether, PD attenuated cardiac dysfunction, increased autophagy flux and improved mitochondrial bioenergetics by up-regulating Sirt3 in the diabetic mice. (C) 2017 Elsevier Inc. All rights reserved.