预输注青年大鼠血浆对七氟烷诱发老龄大鼠认知功能障碍的影响及ERK-CREB信号通路在其中的作用

Effect of pre-infusion of young rat plasma on cognitive dysfunction induced by sevoflurane in aged rats and role of ERK-CREB signaling pathway

目的评价预输注青年大鼠血浆对七氟烷诱发老龄大鼠认知功能障碍的影响及细胞外调节蛋白激酶(ERK)-环磷腺苷效应元件结合蛋白(CREB)信号通路在其中的作用。方法SPF级健康雄性Wistar大鼠120只,18月龄,体重550~650 g,采用随机数字表法分为4组(n=30):对照组(C组)、七氟烷麻醉组(S组)、青年大鼠血浆组(P组)和ERK抑制剂SL327组(SL组)。P组和SL组尾静脉注射经过处理的3月龄青年大鼠血浆100μl/次,C组和S组尾静脉注射等容量生理盐水,2次/周,共4周。注射完毕后S组、P组和SL组大鼠吸入3%七氟烷麻醉3 h,麻醉前SL组尾静脉注射ERK抑制剂SL32750 mg/kg。于麻醉前1 d和麻醉后3、7 d行Morris水迷宫实验评估大鼠认知功能;随后处死大鼠分离海马组织,采用Western blot法测定磷酸化ERK(p-ERK)、磷酸化CREB(p-CREB)、突触蛋白、突触素Ⅰ和突触囊泡蛋白的表达水平,透射电镜下观察海马神经元超微结构并记录突触数量。结果与C组比较,其余3组大鼠麻醉后各时点逃避潜伏期延长,穿越原平台次数减少,海马p-ERK、p-CREB、突触蛋白、突触素Ⅰ和突触囊泡蛋白的表达下调,突触数量减少(P<0.05)。与S组比较,P和SL组大鼠麻醉后各时点逃避潜伏期缩短,穿越原平台次数增加,海马p-ERK、p-CREB、突触蛋白、突触素Ⅰ和突触囊泡蛋白的表达上调,突触数量增加(P<0.05)。与P组比较,SL组大鼠麻醉后各时点逃避潜伏期延长,穿越原平台次数减少,海马p-ERK、p-CREB、突触蛋白、突触素Ⅰ和突触囊泡蛋白的表达下调,突触数量减少(P<0.05)。结论预输注青年大鼠血浆减轻可减轻七氟烷诱发老龄大鼠认知功能障碍,其机制与激活ERK-CREB信号通路,改善海马突触可塑性有关。

Objective To evaluate the effect of pre-infusion of young rat plasma on cognitive dysfunction induced by sevoflurane in aged rats and the role of extracellular regulated protein kinase(ERK)-cyclic adenosine monophosphate effector binding protein(CREB)signaling pathway.Methods One hundred and twenty SPF healthy male Wistar rats,aged 18 months,weighing 550-650 g,were divided into 4 groups(n=30 each)using a random number table method:control group(group C),sevoflurane anesthesia group(group S),young rat plasma group(group P)and ERK inhibitor SL327 group(group SL).The teated plasma 100μl from 3-month-old young rats was injected via the tail vein in group P and group SL,while the equal volume of normal saline was given via the tail vein in group C and group S,twice a week,for 4 weeks.In S,P and SL groups,3%sevoflurane was inhaled for 3 h at the end of injection,and ERK inhibitor SL32750 mg/kg was injected via the tail vein before anesthesia in group SL.The cognitive function was evaluated by Morris water maze test at 1 day before anesthesia and at 3 and 7 days after anesthesia.The rats were sacrificed,and their hippocampi were isolated for determination of the expression of phosphorylated ERK(p-ERK),p-CREB,synapsin,synapsinⅠand synaptophysin and for examination of the ultrastructure of neurons(by transmission electron microscopy).The number of synapses was recorded.Results Compared with group C,the escape latency was significantly prolonged,the number of crossing the original platform was reduced,the expression of p-ERK,p-CREB,synapsin,synapsinⅠand synaptophysin was down-regulated,and the number of synapses was decreased at each time point after anesthesia in the other 3 groups(P<0.05).Compared with group S,the escape latency was significantly shortened,the number of crossing the original platform was increased,the expression of p-ERK,p-CREB,synapsin,synapsinⅠand synaptophysin was up-regulated,and the number of synapses was increased at each time point after anesthesia in P and SL groups(P<0.05).Compared with group P,the escape latency was significantly prolonged,the number of crossing the original platform was reduced,the expression of p-ERK,p-CREB,synapsin,synapsinⅠand synaptophysin was down-regulated,and the number of synapses was decreased in group SL(P<0.05).Conclusion Pre-infusion of young rat plasma can reduce cognitive dysfunction induced by sevoflurane in aged rats,and the mechanism is related to activation of ERK-CREB signaling pathway and improvement of synaptic plasticity.