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

Abstract

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. 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. 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. 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. .