七氟烷对老年大鼠认知功能和海马突触可塑性的影响

Effects of Sevoflurane on Cognitive Function and Hippocampus Synaptic Plasticity in Aged Rats

目的观察七氟烷对老年大鼠认知功能和海马突触可塑性的影响。方法30只老年SD大鼠随机分为对照组(C组)和七氟烷组(S组),每组15只,S组暴露于3%七氟烷、30%O2、5%CO_2环境,C组暴露于30%O_2和5%CO_2环境,每天干预2 h,连续3 d。于干预结束前1 h(T0)、干预停止(T1)、干预停止后1 h(T2)、干预停止后2 h(T3)测试大鼠大脑中动脉收缩期最大流速(peak systolic velocity,PSV)、舒张末期血流速度(end diastolic velocity,EDV)和阻力指数(resistance index,RI)的变化,观察大脑中动脉血流动力学情况;于干预停止后24 h(T4)、48 h(T5)、72 h(T6)应用水迷宫和旷场实验测试大鼠的认知功能和情绪状态;并用透视电子显微镜观察大鼠的突触面积和囊泡面积。结果大脑中动脉血流动力学显示,与C组比较,S组T0大脑中动脉血管RI、PSV、EDV降低,T1以后大脑中动脉血流阻力逐渐恢复;七氟烷暴露后3 d,与C组比较,S组T4、T5潜伏期增加,寻找平台时间延长,穿梭次数减少(P<0.05);旷场实验显示,七氟烷干预后,与C组比较,S组T4、T5周围格活动增加,中央格活动时间减少,直立次数增加(P<0.05);透射电子显微镜显示,与C组比较,S组大鼠的突触面积、囊泡面积减少(P<0.05)。结论七氟烷暴露可扩张大脑中动脉,扩张血管的作用很快就消失;重复暴露于七氟烷的SD老年大鼠可出现认知功能损害,并容易发生焦虑;七氟烷通过改变神经元突触的可塑性而损伤SD老年大鼠海马的认知功能。

Objective To observe the sevoflurane intervention on cognitive function and synaptic plasticity in hippocampus of aged rats.Methods 30 SD aged rats were randomly divided into the control group(group C)and sevoflurane group(group S),with 15 rats in each group.Group S was exposed to 3%sevoflurane,30%oxygen,5%CO2,group C was exposed to 30%oxygen,5%CO2for 2 hours,3 days in total.The peak systolic velocity(PSV),end diastolic velocity(EDV),resistance index(RI)were measure to test middle cerebral artery velocity on 1 hour before the end of sevoflurane intervention(T0),immediate end of sevoflurane intervention(T1),1 hour after the end of sevoflurane intervention(T2),2 hour after the end of sevoflurane intervention(T3).The cognitive function and emotional state were measured by water maze test and open field test on24 hours(T4),48 hours(T5)and 72 hours(T6)after the end of sevoflurane intervention,and hippocampus synaptic vesicles and area was measured by transmission electron microscopy.Results Hemodynamics of the middle cerebral artery showed that,compared with group C,RI,PSV and EDV of middle cerebral artery in group S decreased on T0,middle cerebral artery resistance gradually restored after T1.Compared with group C,the latency on T4 and T5 increased,platform searching time increased,the crossing times reduced in group S after 3 days of sevoflurane exposure(P<0.05).Open field experiments showed that,compared with group C,the peripheral lattice activity time increased,central lattice activity time decreased,the number of standing time was increased on T4 and T5 in group S after 3 days of sevoflurane exposure(P<0.05).Transmission electron microscopy showed hippocampus synaptic area,vesicle size decreased in group S compared with group C(P<0.05).Conclusion Exposure to sevoflurane can dilate the middle cerebral artery and the vessel dilating effect soon disappeared.The repeated exposure to sevoflurane can impair cognitive function on aged SD rats,and the aged SD rats were prone to anxiety.Sevoflurane could impair cognitive function of aged SD rats by altering the synaptic plasticity on hippocampal neurons.