Electroacupuncture improves long-term survival of myocardial infarction mice by promoting myocardial angiogenesis and inhibiting ventricular remodeling

Abstract

To investigate the mechanism of electroacupuncture (EA) in improving the long-term survival rate of mice after myocardial infarction by promoting angiogenesis and inhibiting ventricular remodeling. A total of 102 male C57BL/6 mice were randomly divided into sham operation, model and EA groups (n=34 /group). The myocardial infarction model was established by permanent ligation of the anterior descending branch of the left coronary artery. Beginning from the 3rd day after ligation, EA (2 Hz/20 Hz) was applied to bilateral "Neiguan" (PC6) and "Ximen" (PC4) for 30 min, once a day for 28 days. The survival rate in 140 d was recorded and the left ventricular ejection fraction (EF) calculated by using echocardiography after the treatment. The left cardiac ventricular tissue was cut into sections to be stained with Masson's trichrome, wheat germ agglutinin (WGA) or α-smooth muscle actin (α-SMA) immunohistochemistry method, followed by measuring the collagen area in the marginal region of myocardial infarction and calculating the collagen volume fraction (for assessing the severity of myocardial fibrosis), measuring the sectional area of cardiomyocytes (for assessing the degree of myocardial hypertrophy), and ob-serving the newborn blood vessels and calculating the ratio of neovascularization area (for assessing the state of angiogenesis). The expression of vascular endothelial growth factor (VEGF) and hypoxia-inducible factor (HIF)-1α protein in the boundary area of myocardial infarction were detected by Western blot. After modeling, the survival rate, EF, and the thickness of the left cardiac ventricle were significantly decreased (P<0.01), whereas the percentage of collagen deposition area, sectional area of cardiomyocyte, percentage of angiogenesis area, and the expression levels of VEGF and HIF-1α proteins were significantly increased (P<0.01) in the model group relevant to the sham operation group. Compared with the model group, the survival rate, EF, the thickness of the left cardiac ventricle, the percentage of angiogenesis area, and the expression levels of VEGF and HIF-1α proteins were significantly increased (P<0.05, P<0.01), while the percentage of collagen deposition area and the sectional area of the cardiomyocyte were considerably decreased in the EA group (P<0.01, P<0.05). EA of PC6 and PC4 can significantly improve the cardiac function and long-term survival rate in mice with myocardial infarction, which may be related to its functions in up-regulating the expression of HIF-1α and VEGF to promote angiogenesis and in inhibiting ventricular remodeling.