Effect of Polygonatum sibiricum polysaccharides on myocardial fibrosis in rats with diabetes

Objective To observe the effect of Polygonatum sibiricum polysaccharides(PSP) on myocardial fibrosis in diabetic cardiomyopathy rats and to explore its possible mechanism.Methods Healthy male Sprague-Dawkey rats were randomly divided into normal group,model group,and 250,500,1000 mg/kg PSP groups and all the rats were fed with normal diet for 12 consecutive weeks.General conditions of the rats in each group were observed;fasting blood glucose (FBG),blood biochemical indexes,hemodynamic indexes were detected and heart mass index (HMI),left ventricular mass index (LVMI),and left ventricular end-diastolic pressure (LVEDP)were determined.Hematoxylin-eosin staining was used to observe the changes of myocardial morphology;Masson staining was used to observe the distribution of collagen fiber;the expressions of the bone morphogenetic protein-7(BMP-7),transforming growth factor beta 1 (TGF-β1),Smad2/3 and Smad7 were detected with immunohistochemistry.Results Compared with those of the control group,the FBG (24.81±2.30 mmol/L),HMI (4.16±1.14),LVMI (2.85±0.09) and LVEDP of the rats in the model group were increased (all P < 0.05).Immunohistochemistry results showed that the expressions of TGF-β1 and Smad2/3 protein were significantly increased (P < 0.05);the expressions of BMP-7 and Smad7 protein were significantly reduced(P < 0.05);HE and Masson staining showed that the cardiac tissues were serious damaged for the rats in the model group.Compared with those of the model group,the FBG (13.28±2.08 mmol/L),HMI (3.21±0.07),LVMI (2.09±0.02),and LVEDP were decreased (all P < 0.05);the expressions of TGF-β1 and Smad2/3 protein were significantly reduced (both P < 0.05);the expressions of BMP-7 and Smad7 protein were significantly increased (both P < 0.05);and the pathological changes of cardiac tissue were improved for the rats in 1 000 mg/kg PSP treatment group.Conclusion PSP can improve myocardial fibrosis in diabetic rats and its mechanism may be related to the promoted expression of BMP-7 in cardiac tissue,which affects the TGF-β1 /Smads signal pathway.