[Effect of different electrical current intensities of electroacupuncture preconditioning on cardiac function and macrophage polarization in mice with acute myocardial ischemia].

To observe the effect of different intensities of electroacupuncture (EA) preconditioning on car-diac function and polarization state of macrophages in mice with acute myocardial ischemia (AMI), so as to explore its possible mechanism underlying improvement of AMI.A total of 50 male C57BL/6J mice were randomly divided into sham ope-ration, AMI model, and EA pretreatment groups (0.5 mA, 1 mA, 3 mA subgroups), with 10 mice in each group/subgroup. The mice in the EA pretreatment groups were subjected to EA stimulation of bilateral "Neiguan"(PC6) with 0.5, 1.0 and 3 mA respectively and frequency of 2 Hz/15 Hz for 20 min, once a day, for 3 days. The acute myocardial ischemia model was established by ligating the anterior descending branch (ADB) of the left coronary artery, while the sham operation only had a surgical suture trans-passed below the ADB but without ligation. The myocardial infarction area was measured after TTC staining, and the cardiac function ［left ventricular ejection fraction (EF), short-axis contraction rate (FS)］ was detected by using echocardiography. The M1 macrophages were labeled with CD11b+F480+CD206low, M2 macrophages were labeled with CD11b+F480+CD206high and detected by using flow cytometry, and the expression levels of myocardial interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), Toll-like receptor-4 (TLR4) proteins were detected by using Western blot.Compared with the sham operation group, the model group had a significant increase in the infarction area (P<0.000 1), number of cardiac macrophages and percentage of M1 type macrophages (P<0.000 1), and the expression levels of myocardial IL-1β, TNF-α, TLR4 proteins (P<0.001, P<0.01), and a remarkable decrease in the levels of EF, FS and the percentage of M2 type macrophages (P<0.000 1). In contrast to those of the model group, the area of myocardial infarction (P<0.000 1, P<0.01), expression levels of myocardial IL-1β, TNF-α, TLR4 proteins (P<0.01, P<0.05, P<0.001) in the 0.5 mA, 1 mA and 3 mA groups, number of macrophages and percentage of M1 macrophages (P<0.05) in the 1 mA group were significantly decreased, while the levels of EF and FS (P<0.000 1, P<0.05, P<0.001) in the 3 EA groups, and percentage of M2 macrophage (P<0.05) in the 1 mA group were significantly increased. Comparison among the 3 EA groups displayed that the effects of 1 mA group were significantly superior to those of 0.5 and 3 mA groups in up-regulating EF and FS (P<0.01, P<0.001), and in down-regulating the area of infarct myocardium (P<0.01, P<0.000 1), and the expression of TLR4 protein (P<0.01), and 0.5 mA group in the expression of IL-1β and TNF-α proteins (P<0.05).EA preconditioning with electrical current intensities of 0.5 mA, 1 mA and 3 mA can effectively reduce myocardial infarction size, improve cardiac function in mice with AMI, which may be related with its effects in reducing the number of cardiac macrophages and down-regulating the expression of myocardial IL-1β, TNF-α and TLR4 proteins. The therapeutic effect of 1 mA is better than that of 0.5 and 3 mA.目的：观察不同强度电针预处理对急性心肌缺血（AMI）小鼠心功能影响的效应差异，并探讨其可能的作用机制。方法：C57BL/6J小鼠随机分为假手术组、模型组、电针预处理组(0.5 mA组、1 mA组、3 mA组)，每组10只。各电针预处理组采用0.5、1、3 mA电流强度分别电针小鼠双侧“内关”，每次20 min，每日1次，连续干预3 d后造模。采用结扎心脏冠状动脉左前降支法建立AMI小鼠模型。采用超声心动评价各组小鼠心脏功能，TTC染色法检测心肌梗死面积百分比，流式细胞技术检测心脏巨噬细胞数量和M1/M2巨噬细胞极化状态，Western blot法检测心肌组织白细胞介素-1β(IL-1β)、肿瘤坏死因子α(TNF-α)、Toll样受体4(TLR4)蛋白表达水平。结果：与假手术组比较，模型组左心室射血分数(EF)和短轴收缩率(FS)降低(P<0.000 1)，心肌梗死面积百分比升高(P<0.000 1)，心脏巨噬细胞数量增加(P<0.000 1)，且以M1型为主，心肌组织IL-1β、TNF-α、TLR4蛋白表达水平升高(P<0.001, P<0.01)。与模型组比较，0.5 mA组、1 mA组和3 mA组EF和FS均明显升高(P<0.000 1，P<0.05，P<0.001)，心肌梗死面积百分比明显降低(P<0.000 1，P<0.01)，心肌组织IL-1β、TNF-α、TLR4蛋白表达水平均降低(P<0.01，P<0.05，P<0.001)，1 mA组心脏巨噬细胞数量降低(P<0.05)，且以M1型为主。与1 mA组比较，0.5 mA组和3 mA组EF和FS降低(P<0.01，P<0.000 1)，心肌梗死面积百分比升高(P<0.01，P<0.000 1)，心肌组织TLR4蛋白表达水平升高(P<0.01)，0.5 mA组心肌组织IL-1β、TNF-α蛋白表达水平升高(P<0.05)。结论：0.5、1、3 mA电针预处理均能有效改善AMI小鼠心功能，减少AMI小鼠心肌梗死面积和心脏巨噬细胞数量，下调心肌组织IL-1β、TNF-α、TLR4蛋白表达；其中1 mA组效应最佳，可能与其促进心肌巨噬细胞由M1型向M2型极化有关。.