Protective Effect Of Electroacupuncture On Brain Injury After Resuscitation In Rats With Asphyxiated Cardiac Arrest

Cardiac arrest(CA)is urgent and serious.Although the popularization of cardiopulmonary resuscitation(CPR)and other auxiliary measures have improved the success rate of resuscitation,the effect of brain protection is still unsatisfactory.How to effectively repair the injured neurons,alleviating the complications of neurological,and improving the survival rate and patients'quality of life after cardiopulmonary resuscitation are still serious clinical medical problems which need to be solved urgently.Electroacupuncture has the advantages of simple operation,convenient control,easy to master and small side effects.A large number of studies have shown that electroacupuncture can reduce the infarct volume after cerebral infarction in rats and improving the neurological function defects that caused by cerebral ischemia,while,inhibiting inflammatory media plays a very important role in the process of electroacupuncture brain protection.Cardiac arrest causes cerebral ischemia,and inflammatory reactions can occur in brain tissue within a short period of time.After the recovery of autonomic circulation,cerebral ischemia and reperfusion also produce excessive inflammatory factors.Poor perfusion causes cerebral ischemia and hypoxia,triggering inflammatory cell aggregation,producing a series of inflammatory cascades,leading to severe damage to the central nervous system.Therefore,this study first takes the asphyxiating cardiac arrest rats as the model to simulate the accident of cardiac arrest caused by airway obstruction in the anesthesia process.The effects of electricity on brain injury after resuscitation in rats were observed and demonstrated by behavioral,morphological and molecular biochemical techniques.In addition,as a key regulator of the inflammatory response,the receptors in the cholinergic anti-inflammatory pathway act an important role in the anti-inflammatory process.The content of proinflammatory cytokines increased in mice with?7nAChR gene knockout,and the up-regulation of?7nAChR reduced the infarct volume and neuronal apoptosis in ischemic reperfusion mice.Animal experiments have also confirmed that electroacupuncture can improve the learning,memory and cognitive impairment of rats with ischemia reperfusion and dementia.The mechanism may be related to the up-regulation of?7nAChR to reduce the release of inflammatory factors.In the second part of this experiment,the role of?7nAChR receptor and inflammatory factor in reducing brain injury after cardiac arrest was observed,and its mechanism was preliminarily discussed,which provided a new treatment idea for cerebral injury after cardiac arrest.Experiment 1Protective effect of electroacupuncture on brain injury after cardiopulmonaryresuscitation in ratsObjective:To investigate the protective effect of electroacupuncture(EA)on brain injury in rats after CPR and the difference between the different acupointsMethods:Rats were divided into Sham,CA,EA1(EA at the Baihui and Shuigou),EA2(EA at the Neiguan and Shuigou),EA3(EA at the tail).Rats were asphyxiated for 8min before CPR.At the same time,the EA1,EA2 and EA3 groups were inserted the filiform needles in the points as show below and received the stimulation.The survival rate of rat resuscitation was calculated and the recovery time of spontaneous circulation was recorded.We measured Neurological Deficit Score(NDS)at 24h and 72h after resuscitation.The spatial learning and memory ability of each group was tested by water maze.Neuronal morphology and survival in hippocampus were observed by Nissl staining.Results:We observed that the difference about success rate of CPR among EA1,EA2,EA3 and CA was statistically insignificant.Compared with Sham group,24?72h NDS were reduced significantly,the number of neurons in the hippocampus CA1 region was also significantly reduced,and the spatial learning and memory ability of rats was weakened in other groups.However the number of surviving neurons in the hippocampus,the target quadrant retention time and 24?72 h NDS were increased in EA1 and EA2compared with CA,meanwhile,the difference between the two groups was not significant.It is noteworthy that EA1 shortened the escape latency during the second day of training,while EA2 was on the third day of training.There is no statistical difference in the above indicators between EA3 and CA.Therefore,we explored the mechanism by choosing Baihui and Shuigou.Conclusion:Combined stimulation of Baihui,Shuigou as well as stimulation of Shuigou and Neiguan can improve brain damage in rats after cardiopulmonary resuscitation,and the former is better than the latter in improving learning and memory in rats.Experiment 2Electroacupuncture attenuates inflammatory response by activating?7nAChR toalleviate brain damage in rats after cardiopulmonary resuscitationObjective:This study was designed to investigate whether?7nAChR is involved in the neuroprotective effect induced by electroacupuncture(EA)in the asphyxiated cardiac arrest(CA)rat model.Methods:The animals were divided into Sham,CA,EA,EA+MLA.Cardiopulmonary resuscitation was performed after 8 minutes of asphyxia in rats.The EA group was inserted into the filiform needles at Baihui and Shuigou during the resuscitation,then stimulated by electroacupuncture.Rats in the EA+MLA group received methyllycaconitine which is an antagonist of?7nAChR,after EA treatment by intraperitoneal injection.The expression of?7nAChR at rats~'hippocampal and cortical in each group was detected by immunofluorescence and western blot,and the expression of inflammatory factors IL-1?IL-6?TNF-a and Iba-1 which is microglial cell surface marker was detected by western blot.Result:Immunofluorescence and Western blot show that the expression of?7nAChR receptor was decreased in the hippocampus and cortex of rats after cardiac arrest.Compared with the sham group the expression of?7nAChR was decreased and the levels of IL-1?IL-6?TNF-a and Iba-1 expression in other groups were significantly increased.EA inhibited the down-regulation of?7nAChR in rats after CPR,alleviating release of inflammatory factors TNF-?,IL-1,IL-6 and decreasing production of microglia/macrophage compared with CA.However,when the?7nAChR antagonist MLA is used,the effect of the EA is reversed.Conclusion:The present study demonstrates that EA is able to improve brain damage after cardiopulmonary resuscitation via activation of?7nAChR,which significantly cut down the inflammatory response in brain.