成年小鼠七氟醚麻醉手术后海马突触结合蛋白-Ⅰ表达的变化

Changes in expression of synaptotagmin-Ⅰ after sevoflurance anesthesia in adult mice

目的 评价突触结合蛋白-Ⅰ（synaptotagmin-Ⅰ,syt-Ⅰ）在七氟醚麻醉的成年小鼠海马中的表达变化. 方法 成年雄性C57BL/6小鼠120只,16周龄,体重（21.2＆#177;2.2）g,采用随机数字表法分为4组（每组30只）：吸氧＋生理盐水＋戊巴比妥钠组（C组）、吸氧＋生理盐水＋腹腔探查术＋戊巴比妥钠组（S组）、七氟醚麻醉＋腹腔探查术＋生理盐水组（SS组）和七氟醚＋腹腔探查术＋地塞米松组（SD组）.麻醉前1h,SD组腹腔注射地塞米松（2 mg/kg）,余3组腹腔注射等量生理盐水.C组、S组1.5％戊巴比妥钠腹腔注射麻醉,SS组、SD组3.4％～3.6％七氟醚麻醉,S组、SS组、SD组行腹腔探查术.麻醉手术结束24 h后,水迷宫训练后测定各组的潜伏期、穿越平台次数、目标象限游泳时间.水迷宫测试结束后2h进行条件恐惧训练,条件恐惧训练结束24 h后进行场景恐惧和条件恐惧测试.行为学测试结束后取小鼠海马组织,Western blot检测syt-Ⅰ、IL-1β、S100A8含量,RT-PCR检测S100A8、Toll样受体4（toll-like receptor 4,TLR4）、IL-6、IL-1β、TNF-α,mRNA含量. 结果 与C组比较,S组和SS组第3、4、5天潜伏期延长、穿越平台次数减少、目标象限游泳时间缩短、场景恐惧时间下降（P均＜0.05）;与SS组比较,SD组潜伏期缩短、穿越平台次数增加、目标象限游泳时间增加、场景恐惧时间增加（P均＜0.05）.4组条件恐惧僵直反应差异无统计学意义（P＞0.05）.与C组比较：S组和SS组IL-1β和S100A8蛋白及其mRNA表达增加,TNF-α mRNA表达增加（P＜0.05）;SS组syt-Ⅰ及TLR4 mRNA含量降低,IL-1β和S100A8蛋白及其mRNA表达增加（P＜0.05）. 结论 syt-Ⅰ表达下降参与了七氟醚麻醉手术后成年小鼠认知功能障碍.

Objective To investigate the changes of synaptotagmin-Ⅰ （syt-Ⅰ） in in adult mice after sevoflurance anesthesia.Methods One hundred and twenty 16-week male C57BL/6 mice,weighing （21.2＆#177;2.2） g,were randomly divided into 4 groups （n=30）using a random number table：group O2＋normal saline ＋pelltobarbitalum natricum （group C）,group O2＋normal saline ＋laparotomy surgery＋pelltobarbitalum natricum （group S）,group sevoflurance anesthesia＋laparotomy surgery＋normal saline （group SS） and group sevoflurance anesthesia＋laparotomy surgery＋dexamethasone （group SD）.Animals in group SD were subjected to an administration of dexamethasone （2 mg/kg）,other groups were subjected to isochoric normal saline 1 h before anesthesia.Group C and group S were anesthetized with pelltobarbitalum natricum（1.5%,0.1 ml/20 g）.Group SS and group SD were anesthetized with sevoflurane（3.4%～3.6%）.Group C was subjected to no surgery,while other 3 groups were subjected to laparotomy surgery.The Morris water maze test were performed at 24 h after the anesthesia and surgery,and record the escape latency,frequency of crossing the original platform,and duration of swimming spent at the target quadrant,the fear conditioning training was performed 2 h later.The contextual and cued fear conditioning test were peformed at 24 h after training.The hippocampus was harvested after the behavioral test immediately to determine the expression of syt-Ⅰ,IL-1β and S100A8 （by Western blot） and the expression of mRNA of S100A8,toll-like receptor 4 （TLR4）,IL-6,IL-1β,TNF-α （by RT-PCR）.Results Compared with group C,the escape latency was increased in Day 3,Day 4 and Day 5 （P〈0.05）,the crossing platform times were decreased,crossing platform quadrant time,the freezing time in the contextual fear conditioning test were shortened in both group S and group SS （P〈0.05）.Compared with group SS,the frequency of crossing the original platform,duration of swimming spent at the target quadrant,and freezing time in the contextual fear conditioning test were increased （P〈0.05）,the escape latency was shortened in group SD （P〈0.05）.There was no significant difference in the freezing time in the cued fear conditioning test among the four groups.Compared with group C,the content of IL-1β and S100A8 protein were increased（P〈0.05）,and IL-1β,S100A8,TNF-α mRNA were increased（P〈0.05） in the group S and group SS.Compared with group C,the content of syt-Ⅰ and TLR4 mRNA was decreased （P〈0.05）,and S100A8 mRNA and IL-1β mRNA were expressed more in group SS （P〈0.05）.Conclusions Down regulation of syt-Ⅰ in hippocampal neurons is involved in cognitive dysfunction caused by single sevoflurance anesthesia of high concentration and surgery.