| BackgroundAcute myocardial infarction(AMI)is a severe cardiovascular disease with high incidence in China and even in the world.It is also the main cause of sudden cardiac death.How to effectively prevent the occurrence of ischemic heart disease and reduce the degree of ischemic heart injury has been the research focus in the field of cardiac rehabilitation.In recent years,electroacupuncture pretreatment is one of the treatment methods for acupuncture "uring underlying diseases" under the modern medical mode.Acupuncture at "neiguan point" can resist myocardial ischemia injury through peripheral nervous system and central nervous system.However,the specific molecular mechanism of electroacupuncture at "neiguan point" pretreatment on myocardial ischemia is still unclear.ObjectThe purpose of this study was to investigate the effect of electroacupuncture"neiguan point" pretreatment on cardiac morphology and functional recovery after acute myocardial infarction injury in rats and the underlying molecular mechanism.MethodsIn the first part,adult male Sprague-Dawley(SD)rats were divided into sham group,model(M)group(without any other treatments),and electroacupuncture treatment group(EA+M).Rats in EA + M group were given EA stimulation of Neiguan(PC6)acupoint located inside the forelimb,and needles ware stabbed subcutaneously 2-3 mm into the two acupoints simultaneously using SDZ-Ⅱ type electroacupuncture treatment instrument(output voltage:2-4 V,output current:4-6 mA),30 min each time,once a day,with a total period of 7-day continuous EA before modeling.A rat model of acute myocardial infarction was established by permanent ligation of the left anterior descending coronary artery.Rats in the sham group were only threaded without ligation,which served as the control group.After successful modeling,transthoracic echocardiography was performed to compare the cardiac morphological and functional changes of rats in different treatment groups.All rats were then anesthetized and the serum and heart samples were collected.The concentrations of CK-MB and LDH were detected using ELISA kits,and the myocardial morphological changes arnd infarct size were observed through HE staining and TTC staining.In the second part,SD rats were divided into sham group,M group and EA+M group.The treatment of rats in each group is the same as in the first part.TUNEL staining was used to detect apoptosis of myocardial cells,and Transmission electron microscopy was employed to observe the autophagosome formation.The expression levels of autophagy-related proteins LC3 II/LC3 I,Beclin-1 and P62 were detected by western blotting.In the third part,SD rats were divided into sham group,M group,M+EA group,AMPK inhibitor Compound C(M+EA+CC)and AMPK inhibitor solvent control(M+EA+DMSO)group.The myocardial morphological changes and infarct size were observed through HE staining and TTC staining,and the concentrations of CK-MB and LDH were detected using ELISA kits.Transmission electron microscopy was employed to observe the autophagosome formation,and the expression of autophagy-related proteins(LC3 II/LC3 I,Beclin-1,Bcl-2 and P62)and AMPK-dependent autophagy-related proteins(p-AMPK,t-AMPK,p-mTOR and t-mTOR)were detected by immunohistochemistry and western blot.ResultsEA have a good protective effect on the AMI rat through ameliorating heart structure and function,and alleviating myocardial morphological damage and infarct size.EA could decrease the concentrations of CK-MB and LDH.Transmission electron microscopy showed that EA Ccould also regulate the AMPK-dependent autophagosome formation,and the AMPK-dependent autophagy-related protein expression.AMPK inhibitor Compound C could impair the effect of EA through regulating the concentrations of CK-MB and LDH,autophagosome formation,and autophagy-related protein expression.Molecular mechanism research found that EA could inhibit the apoptosis of cardiomyocytes,and promote autophagosomes formation in myocardium and the expressions of autophagy-related proteins LC3 I,LC3 II and Beclin-1,simultaneously inhibit Bcl-2 and P62 protein expressions.Further study found that EA could induce the up-regulation of p-AMPK expression and the down-regulation of p-mTOR.However,AMPK inhibitor compound C could resist the regulatory role of EA on AMPK-mediated autophagy-related protein expression and AMPK-dependent autophagosome formation,and thus reverse the protection of EA preconditioning at Neiguan(PC6)on AMI rats.ConclusionEA could improve myocardial infarction injury and induce autophagy,and AMPK-dependent autophagy might be involved in this process.. |
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