电针“内关”预处理通过LKB1/AMPK/PFK2对心肌缺血大鼠细胞自噬的影响

Effect of electroacupuncture preconditioning of “Neiguan”(PC6) on myocardial LKB1/AMPK/PFK2 pathway in myocardial ischemia rats

目的:观察电针预处理对急性心肌缺血(AMI)大鼠心肌细胞自噬相关蛋白肝酶蛋白(LKB1)、AMP活化蛋白激酶(AMPK)、6-磷酸果糖激酶-2(PFK2)表达的影响,探讨"内关"穴对心肌损伤的保护机制。方法:Wistar大鼠随机分为伪手术组、模型组、针刺组,每组10只。采用冠状动脉左前降支结扎法复制大鼠AMI模型,造模前连续电针刺激"内关"14 d,每次30 min,每日1次。HE染色观察大鼠心肌组织病理形态学改变,ELISA法检测血清乳酸脱氢酶(LDH)的变化,Western blot法检测心肌组织中LKB1、AMPKa1、AMPKa2、PFK2蛋白的相对表达量,荧光定量PCR法检测LKB1、AMPKa1、AMPKa2、PFK2 mRNA在心肌组织中的表达水平。结果:与伪手术组比较,模型组大鼠血清LDH含量明显升高(P<0.01);心肌细胞肿胀,心肌纤维排列紊乱,肌纤维明显断裂,间质有炎性浸润、出血;心肌组织中AMPKa2、PFK2蛋白和mRNA表达水平显著升高(P<0.01),LKB1、AMPKa1蛋白和mRNA表达水平升高(P<0.05)。与模型组比较,针刺组血清LDH含量显著降低(P<0.01);心肌纤维断裂减少,细胞肿胀减轻,有少量间质出血及炎性细胞浸润;大鼠心肌组织中LKB1、AMPKa1、PFK2蛋白和mRNA表达水平皆明显升高(P<0.01),AMPKa2蛋白表达水平下降(P<0.01),AMPKa2蛋白和mRNA表达水平降低(P<0.01)。结论:电针预处理可加强LKB1/AMPK/PFK2信号通路激活自噬,改善心肌细胞凋亡、坏死,促进受损心肌细胞生存。

Objective To observe the effect of electroacupuncture(EA) preconditioning on the expression of liver protein kinase 1(LKB1), adenosine 5’-monophosphate(AMP)-activated protein kinase(AMPK) and 6-phosphofructo-2-kinase(PFK2) in cardiomyocytes of rats with acute myocardial ischemia(AMI), so as to explore its mechanisms underlying cardioprotective effect. Methods Thirty male Wistar rats were randomly divided into sham-operation, model and EA pretreatment groups(n=10 rats per group). The AMI model was established by ligation of the left anterior descending branch of coronary artery. Before modeling, EA preconditioning(2 Hz/15 Hz, 1 mA) was applied to bilateral "Neiguan"(PC6) for 30 min, once daily for 14 days. Histopathological changes of myocardium was observed by microscope after H.E. staining. The level of lactate dehydrogenase(LDH) in serum was detected by ELISA. The expression of autophagy-associated proteins and mRNAs as LKB1, AMPKa1, AMPKa2 and PFK2 were detected by Western blot and real-time PCR, respectively. Results Compared with the sham-operation group, serum LDH content, and expression levels of myocardial AMPKa2 and PFK2 proteins and mRNAs were significantly up-regulated(P<0.01), and those of LKB1 and AMPKa1 proteins and mRNAs were increased in the model group(P<0.05). Following the intervention, serum LDH were apparently down-regulated(P<0.01), and expression levels of myocardial LKB1, AMPKa1 and PFK2 proteins and mRNAs were apparently up-regulated(P<0.01), but that of AMPKa2 protein and mRNA was remarkably down-regulated in the EA group(P<0.01). H.E. staining showed cell swelling, disordered arrangement of myocardial fibers with obvious rupture, interstitial bleeding and inflammatory infiltration, which was relatively milder in the EA preconditioning group. Conclusion EA pretreatment can trigger LKB1/AMPK/PFK2 signaling pathway in AMI rats, which may contribute to its cardioprotective effect against ischemic myocardial injury by activating autophagy of cardiomyocytes.