EFFECTS OF PAEONOL ON ELECTROCARDIOGRAM, MYOCARDIAL CELL APOPTOSIS AND MYOCARDIAL FIBROSIS IN RATS WITH MYOCARDIAL INFARCTION

Yuehua Ji¹, Jun Huang^{1, *}, Hui Hu², Jianghua Yang³,

¹Department of Electrocardiogram Room, Huzhou Central Hospital, Huzhou 313000, Zhejiang Province, China - ²Department of Cardiology, Huzhou Central Hospital, Huzhou 313000, Zhejiang Province, China - ³Department of Radiology, Huzhou Central Hospital, Huzhou 313000, Zhejiang Province, China

Objective: To analyze the effects of paeonol on electrocardiogram (ECG), myocardial cell apoptosis and myocardial fibrosis in rats with myocardial infarction. 

Methods: Forty healthy SPF male SD mice were selected and divided into control group, model group, low-dose group and high-dose group. The model group and low-dose group were created by ligation of left anterior descending coronary artery (LAD) by thoracotomy. Three days after modeling, mice in low-dose and high-dose groups were intraperitoneally injected with paeonol 10 and 15 mg / kg for 4 weeks. ECG changes were observed at 10, 30, 60 and 24 h before and after the experiment. H&E staining and Masson staining were used to look at the mice’s hearts. TUNEL staining was used to detect the apoptosis of cardiomyocytes. Western blot was used to detect the expression of TGF - β/Smad pathway-related proteins. 

Results: At 10, 30, 60 min and 2 h after operation, the ECG J point of model group was significantly higher than that of control group, and that of low- and high-dose groups was significantly lower than that of model group (P<0.05). H&E staining showed that the myocardial cells in the control group were evenly stained, orderly arranged, with clear cytoplasm, without obvious pathological changes; the cardiomyocytes in the model group were significantly hypertrophied, with nuclear pyknosis, narrowing of intercellular space, disordered arrangement and cytoplasmic loss; the cardiomyocytes of low- and high-dose groups were orderly and evenly arranged, and obvious pathological changes were improved. Masson staining showed that there were no obvious pathological changes in the control group; the cells in the model group were significantly hypertrophic and the proliferation of collagen fibers was serious; the degree of fibrosis in the low- and high-dose groups was significantly improved compared with the model group. The apoptosis rate of the model group was significantly higher than that of the control group, and the apoptosis rate of the low- and high-dose groups was significantly lower than that of the model group. The higher the dose, the lower the apoptosis rate (P<0.05). The expression of Bax protein in the model group was significantly higher than in the control group, and the protein expression of Bcl-2 and C-caspase-3 was significantly lower than that of the control group. The expression of Bax protein in the low- and high-dose groups was significantly lower than in the model group, and the expression of Bcl-2 and C-caspase-3 was significantly higher than that of the model group (P<0.05). The expression of TGF - β 1 and Smad2 proteins in the model group was significantly higher than in the control group, and the protein expression of TGF - β 1 and Smad2 in the low- and high-dose groups was significantly lower than in the model group (P<0.05). 

Conclusion: Paeonol can improve cardiac function, reduce the apoptosis rate of myocardial cells and improve myocardial fibrosis in mice with myocardial infarction. The mechanism may be related to the regulation of TGF-β / Smad pathway-related proteins by paeonol.