The Effect Of Electroacupuncture Pretreatment On The Expression Of Bcl-2 And Bax In Hippocampal Neurons In Aged Rats With Sevoflurane-induced Postoperative Cognitive Dysfunction

Objectives:Postoperative cognitive dysfunction?POCD?is a common complication of central nervous system in elderly patients.Sevoflurane as a new kind of inhalation anesthetics,can induce the occurrence of POCD in elderly patients,apoptosis of hippocampal neurons is one of the important mechanisms of sevoflurane-induced POCD.It has been found that electroacupuncture preconditioning can improve cognitive function in aged rats with sevoflurane-induced POCD,but the research on improving cognitive impairment using electroacupuncture pretreatment by inhibiting apoptosis of hippocampal neurons is less.Therefore,this study intends to evaluate the efficacy of electroacupuncture pretreatment on apoptosis of hippocampal neurons in aged rats with sevoflurane-induced POCD,and to provide a reference for clinical research.Methods:One hundred and twenty healthy male Sprague-Dawley rats,18 months old,weighting 500⁵50g,were randomly divided into 3 groups?n=40?:control group?group C?,model group?POCD group?and electroacupuncture group?EA group?.The rats in EA group received electric needle stimulation five days before the anesthesia,Baihui and Dazhui point were selected,stimulation lasted for 30min,once a day,over 5days.Then rats of the POCD and EA group continuously inhaled 3%sevoflorane for 3 hours.The group C did not perform any operation on it.In the 1^st day before anesthesia and the 3^rd and 7^th days after anesthesia,the Morris water maze test was conducted to determine the cognitive function of rats;flow cytometry to detect the hippocampus neuron apoptosis rate,Western blot method to detect the expression of Caspase-3 and Cyt-c in hippocampal neurons,RT-PCR method to detect the level of Bcl-2 mRNA and Bax rnRNA in hippocampal neurons,transmission electron microscope observed and recorded the ultrastructure of hippocampal neurons.Results:Compared with the 1^st day before anesthesia,group POCD and group EA in the 3^rd and 7^th days after anesthesia,the escape latency was increased;the frequency of crossing the original platform was decreased;neuron apoptosis rate was increased;the expression of caspase-3 and Cyt-c was increased,the level of Bax mRNA wsa decreased,the level of Bcl-2 mRNA was decreased,and the ratio of Bax/bcl-2 was increased?P<0.05?.Compared with group C,group POCD and group EA in the 3^rd and 7^thh days after anesthesia,the escape latency was increased;the frequency of crossing the original platform was decreased;neuron apoptosis rate was increased;the expression of caspase-3 and Cyt-c was increased,the level of Bax mRNA wsa decreased,the level of Bcl-2 mRNA was decreased,and the ratio of Bax/bcl-2 was increased?P<0.05?.Compared with group POCD,group EA in the 3^rd and 7^th days after anesthesia,the escape latency was decreased;the frequency of crossing the original platform was increased;neuron apoptosis rate was decreased;the expression of caspase-3 and Cyt-c was decreased,the level of Bax mRNA wsa decreased,the level of Bcl-2 mRNA was increased,and the ratio of Bax/bcl-2was decreased?P<0.05?.Pictures under the transmission electron microscope,showed that there was no obvious abnormality in the ultrastructure of hippocampal neurons in group C at all time points.Both POCD and EA groups showed pathological damage in hippocampal neurons after anesthesia,but group EA were lighter than the group POCD.Conclusion:1.Electroacupuncture pretreatment can improve the cognitive function in aged rats with sevoflurane-induced POCD,and its mechanism is related to inhibiting apoptosis of hippocampal neurons.2.The mechanism of electroacupuncture pretreatment to improve the cognitive function in aged rats with sevoflurane-induced POCD is related to inhibiting apoptosis of hippocampal neurons.3.Electroacupuncture pretreatment can regulate bcl-2 and Bax gene,reduce the ratio of Bax/bcl-2 mRNA,predominate the anti-apoptotic gene,inhibit the apoptosis of hippocampal neurons.