The Mechanism Of GABA_A Receptors Mediated Needle Pretreatment Of The Parietal Nucleus Of The Cerebellum To Regulate Sympathetic Nerve Activity And Reduce Myocardial Ischemia-Reperfusion Injury

Object:To observe the effects of electroacupuncture（EA）preconditioning on cardiac function,sympathetic nerve activity,indexes related to myocardial injury,and GABA_Areceptor in fastigial nucleus（FN）of rats with myocardial ischemia-reperfusion injury（MIRI）.To explore how EA preconditioning can alleviate MIRI through neural regulation mechanism.Methods:Male SD rats were randomly divided into sham operation group,model group,Electroacupuncture Shenmen point group（EA group）,Electroacupuncture at Fuliu（control group）,GABA_Areceptor agonist group（agonist group）,GABA_Areceptor inhibitor group（inhibitor group）,Normal saline+model group,Normal saline+electroacupuncture group,GABA_Areceptor agonist（agonist）+EA group,with12 rats in each group.The MIRI model was prepared using a ligation the anterior descending coronary artery.In the EA group and the agonist+EA group,EA was applied to bilateral“Shenmen”（HT7）and“Tongli”（HT5）for 30min,once daily for consecutive7 days before modeling.Control group was applied to bilateral“Fuliu”（KI7）and“Zhubin”（KI9）for 30min,once daily for consecutive 7 days before modeling.In the agonist group,the GABA_Areceptor agonist Muscone was injected into the FN for 7consecutive days prior to modeling.In the inhibitor group,the GABA_Areceptor inhibitor Bicuculline was injected into the FN for 7 consecutive days prior to modeling.Normal saline+model group,normal saline was injected into the FN for 7 consecutive days prior to modeling.Normal saline+electroacupuncture group,Normal saline was injected into the FN 30 min prior to each EA.In the agonist+EA group,Muscone was injected into the FN 30 min prior to each EA.The ECG data of each group of rats were collected with the Power Lab StandardⅡlead system,and the changes in ST-segment displacement values and Heart Rate Variability（HRV）were analyzed.Pathological changes in rat myocardial tissue observed by Hematoxylin-Eosin staining（HE）.The area of myocardial infarction in rats was observed by Triphenyltetrazolium chloride（TTC）.The levels of Creatine Kinase-MB（CK-MB）,cardiac troponin I（c Tn I）and noradrenaline（NE）in serum were measured by ELISA.Immunohistochemistry,immunofluorescence and q PCR detected positive expression of GABA_A,GABA_BR1and GABA_BR2receptors in rat FN.Results:1.HE staining results showed that the myocardial cells in the sham operation group were orderly arranged with relatively complete edges;In the model group,the myocardial fibers were obviously broken and the interstitial edema was serious,The degree of myocardial tissue damage in the electroacupuncture group was reduced,while there was significant inflammatory cell infiltration in the myocardial tissue in the electroacupuncture control group.Compared with the sham group,the ST segment displacement value of rats in the model group increased（P<0.01）,myocardial infarction area increased（P<0.01）,serum CK-MB,c Tn I and NE content increased（P<0.01）,LF/HF ratio increased significantly（P<0.01）,and HRV frequency domain analysis showed that sympathetic excitability was enhanced;Compared with the model group,the ST segment displacement value of rats in the electroacupuncture group decreased（P<0.01）,the myocardial infarction area decreased（P<0.01）,the serum CK-MB,c Tn I,and NE contents decreased（P<0.01）,the LF/HF ratio was significantly reduced（P<0.01）,and the frequency domain analysis of HRV showed that sympathetic excitability was reduced;Compared with the electroacupuncture group,the ST segment displacement value of rats in the electro-targeted illumination group increased（P<0.01）,myocardial infarction area increased（P<0.01）,serum CK-MB,c Tn I and NE content increased（P<0.01）,LF/HF ratio increased significantly（P<0.01）,and HRV frequency domain analysis showed that sympathetic excitability was enhanced.2.2.Compared with the sham group,the positive expression of FN GABA_A,GABA_B1Rand GABA_B2Rreceptors in the model group was increased（P<0.01）,compared with the model group,the positive expression of FN GABA_Areceptor in the electroacupuncture group decreased（P<0.01）,and there was no significant difference in the positive expression of FN GABA_B1Rand GABA_B2Rreceptors in the electroacupuncture group（P>0.05）.Compared with the model group,the serum NE content of rats in the model+poonyine group decreased（P<0.01）,the LF/HF ratio was significantly reduced（P<0.01）,HRV frequency domain analysis showed that sympathetic excitability was reduced,and there was no significant difference between model+saline group and model+musk ketone group（P>0.05）;Compared with the model+muskone group,the serum NE content of rats in the model+purse peony group decreased（P<0.01）,the LF/HF ratio was significantly reduced（P<0.01）,HRV frequency domain analysis showed that sympathetic excitability was reduced,and the difference between model+saline group was not statistically significant（P>0.05）;Compared with the model+purse peony group,the serum NE content of rats in the model+normal saline group increased（P<0.01）,the LF/HF ratio increased significantly（P<0.01）,and HRV frequency domain analysis showed that sympathetic excitability was enhanced.3.The results of HE staining showed that the nuclei of the electroacupuncture group were uniformly colored,the inflammation distribution was less,and the myocardial fibers were less broken.The cells of the electroacupuncture+muskone group were arranged chaotically,the myocardial fibers were obviously ruptured,and the fine interstitial edema was serious.The arrangement of cardiomyocytes in the electroacupuncture+saline group was more neat and orderly,and myocardial fibers were less broken.Compared with the electroacupuncture group,the ST segment displacement value of rats in the electroacupuncture+muskone group increased（P<0.01）,the myocardial infarction area increased（P<0.01）,the serum CK-MB,c Tn I,and NE contents increased（P<0.01）,the LF/HF ratio increased significantly（P<0.01）,and the frequency domain analysis of HRV showed that sympathetic excitability was enhanced,and there was no significant difference between electroacupuncture+saline group（P>0.05）;Compared with the electroacupuncture+muskone group,the ST segment displacement value of rats in the electroacupuncture+saline group decreased（P<0.01）,myocardial infarction area decreased（P<0.01）,serum CK-MB,c Tn I and NE contents decreased（P<0.01）,LF/HF ratio was significantly reduced（P<0.01）,and HRV frequency domain analysis showed that sympathetic excitability was reduced.Conclusion:1.Electroacupuncture pretreatment improves sympathetic tension and reduces MIRI damage.2.Electroacupuncture pretreatment inhibits the expression of GABA_Areceptor in the parietal nucleus of the cerebellum and improves sympathetic tone in MIRI rats.3.GABA_Amediated conductive needle pretreatment of the cerebellar parietal nucleus regulates sympathetic nerve activity and alleviates myocardial ischemia-reperfusion injury.