Regulation of autophagy by tea polyphenols in diabetic cardiomyopathy.

OBJECTIVE: To investigate the effect of tea polyphenols on cardiac function in rats with diabetic cardiomyopathy, and the mechanism by which tea polyphenols regulate autophagy in diabetic cardiomyopathy. METHODS: Sixty Sprague-Dawley (SD) rats were randomly divided into six groups: a normal control group (NC), an obesity group (OB), a diabetic cardiomyopathy group (DCM), a tea polyphenol group (TP), an obesity tea polyphenol treatment group (OB-TP), and a diabetic cardiomyopathy tea polyphenol treatment group (DCM-TP). After successful modeling, serum glucose, cholesterol, and triglyceride levels were determined; cardiac structure and function were inspected by ultrasonic cardiography; myocardial pathology was examined by staining with hematoxylin-eosin; transmission electron microscopy was used to observe the morphology and quantity of autophagosomes; and expression levels of autophagy-related proteins LC3-II, SQSTM1/p62, and Beclin-1 were determined by Western blotting. RESULTS: Compared to the NC group, the OB group had normal blood glucose and a high level of blood lipids; both blood glucose and lipids were increased in the DCM group; ultrasonic cardiograms showed that the fraction shortening was reduced in the DCM group. However, these were improved significantly in the DCM-TP group. Hematoxylin-eosin staining showed disordered cardiomyocytes and hypertrophy in the DCM group; however, no differences were found among the remaining groups. Transmission electron microscopy revealed that the numbers of autophagosomes in the DCM and OB-TP groups were obviously increased compared to the NC and OB groups; the number of autophagosomes in the DCM-TP group was reduced. Western blotting showed that the expression of LC3-II/I and Beclin-1 increased obviously, whereas the expression of SQSTM1/p62 was decreased in the DCM and OB-TP groups (P<0.05). CONCLUSIONS: Tea polyphenols had an effect on diabetic cardiomyopathy in rat cardiac function and may alter the levels of autophagy to improve glucose and lipid metabolism in diabetes.

Effects of total flavones from Dendranthema morifolium on vasocontraction and proliferation of vascular smooth muscle cells.

Pharmacological studies have shown that the active components in Dendranthema morifolium exhibit protective effects against ischemia/reperfusion injury; however, its pharmacological action on blood vessels has not yet been investigated. The purpose of the present study was to assess the effects of the total flavones extracted from D. morifolium (Ramat.) Tzvel. cv. Hangju (FDM) on the vasocontraction and proliferation of vascular smooth muscle cells (VSMCs). The tension of rat thoracic aortic rings was measured using a mechanical force transducer attached to a recording system. FDM induced a dose­dependent relaxation of rings with endothelium pre­contracted by either phenylephrine (PE; 10(­6) mol/l) or a high concentration of potassium chloride (KCl; 60 mmol/l). FDM did not significantly affect the vasorelaxant effects on mechanically removed endothelium. In endothelium­denuded aortic rings depolarized by 60 mmol/l KCl, FDM inhibited the contraction induced by Ca2+. FDM reduced the transient contraction caused by PE in a Ca2+­free solution, but did not affect the contraction induced by phorbol ester. Furthermore, FDM inhibited the proliferation of VSMCs with or without growth stimulation by insulin. In conclusion, that the vasorelaxation induced by FDM in rat aortic rings is not dependent on the endothelium but is mediated via a reduction of the influx of extracellular Ca2+ through the voltage­dependent and receptor­operated channels and via the inhibition of the release of intracellular Ca2+ in VSMCs. The anti­proliferative activity of FDM suggests that it may be beneficial in inhibiting atherosclerosis.