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学科主题: 麻醉学
题名:
海马突触后NMDA受体在异氟烷麻醉后老年大鼠认知功能改变中的作用
作者: 李伦旭
答辩日期: 2016-11-23
导师: 郭向阳
专业: 麻醉学
授予单位: 北京大学
授予地点: 北京大学第三临床医学院
学位: 博士
关键词: 异氟烷 ; 认知功能损害 ; GluN2B ; arp2/3复合物 ; 树突棘
其他题名: Role of hippocampal postsynaptic NMDA receptors in cognitive function after isoflurane anesthesia in aged rats
分类号: R614.1
摘要:

背景:认知功能障碍是老年患者术后常见并发症。卤化吸入麻醉药在其中的作用一直倍受争议。NMDA受体既是卤化吸入麻醉药的重要抑制位点,又参与突触和树突棘可塑性及认知功能的调节。但卤化吸入麻醉药对NMDA受体的影响是否延续到术后并影响认知功能,目前鲜有报道。

目的:以老年大鼠为研究对象,观察异氟烷麻醉后海马突触内、外NMDA受体GluN2A/2B亚基表达的变化及其与认知功能变化的关系,以及NMDA受体亚基变化对arp2/3复合物表达和树突棘的影响,探讨异氟烷暴露对老年大鼠是否产生麻醉后的遗留效应及其可能的机制。

方法:

实验一 20月龄雄性SD大鼠,随机分为对照组,异氟烷组,异氟烷+GluN2B拮抗剂Ro25-6981组,及Ro25-6981组。 各组分为两个亚组,于干预后第1天或第30天起接受水迷宫实验。

实验二  20月龄雄性SD大鼠,分组同上,干预后第1、7、30天Western blot检测NMDA受体GluN2A、2B亚基和arp2/3表达;Golgi染色检测树突棘变化。

实验三 干预3小时末,行动脉血气分析和血糖检测。

结果:

1. 干预后第1周,异氟烷组Morris水迷宫实验中大鼠逃避潜伏期延长,在原平台象限内探索时间缩短; 1月后恢复到对照组水平;Ro25-6981可改善异氟烷引起的上述指标异常。

2. 干预后第1、7天,异氟烷组海马组织总GluN2B和突触外GluN2B表达增加; 1月后降至对照组水平。

3. 干预后第1、7天异氟烷组海马arp2/3表达减少,1月后与对照组水平相似; Ro25-6981可逆转异氟烷诱导的arp2/3表达下调。

4. 干预后第1、7天异氟烷组海马神经元树突棘减少,1月后与对照组水平相似; Ro25-6981可以缓解异氟烷引起的树突棘减少。

5. 本实验中干预措施未引起动物血气及血糖异常。

结论:

1. 异氟烷可引起老年大鼠可逆性认知功能障碍。

2. 异氟烷可通过引起老年大鼠突触外GluN2B表达增加导致海马树突棘减少;抑制突触外GluN2B,可以改善异氟烷引起的树突棘退变。

3. GluN2B可通过arp2/3对树突棘产生调节作用;抑制突触外GluN2B,可以改善异氟烷对arp2/3的抑制作用和继之而来的树突棘退变以及认知功能障碍。

英文摘要:

Backgrounds:Cognitive dysfunction is a common complication in elderly patients after surgery, and the role of halogenated inhaled anesthetics in these disorders has been controversial. The NMDAR was an important inhibitory site of these anesthetics, which has critical regulatory acters in synaptic and dendritic spine plasticity and learning and memory. However,there are few investigations about whether the effcts of these halogenated inhaled anesthetics on NMDAR can last to postoperative period and affect postoperative cognitive function.

Objectives:The study was undertaken in aged rats to investigate (1) the changes of NMDA receptor GluN2A/2B subunit expression in the hippocampus after isoflurane anesthesia and the relationships between the expressions of GluN2A/2B and the changes of cognitive function,(2) the effcts of GluN2A/2B expression changes on arp2/3 complex expression and dendritic spine density, to explore whether the effcts of the anesthetics on NMDAR last to postoperative period and lead to cognitive impairment, and its underlying mechanism.

Method:

Experiment 1

The 20-month-old male Sprague-Dawley rats were randomly allocated to control group, isoflurane group, isoflurane+GluN2B antagonist Ro25-6981 group and Ro25-6981 group. Each group was divided into two subgroups for  Morris water maze test beginning on the day 1 or day 30 after the intervention.

Experiment 2

The expression of GluN2A/2B and arp2/3 was detected by Westernblot on day 1,7 and 30 after the intervention,and Golgi staining was used to detect the changes of dendritic spine.

Experiment 3

Arterial blood gas analysis and blood glucose testing were performed during the course of intervention.

Result:

1. In the isoflurane group, the escape latency was prolonged, and the exploration time in the original platform quadrant was shortened in Morris Water Maze during the the first week after anesthesia; and all of them restored to similar level in control group after 1 month. Ro25-6981 could alleviate the abnormalities caused by isoflurane.

2. The expression of total GluN2B and extrasynaptic GluN2B in the hippocampus increased in the isoflurane group on the day 1 and day 7 after the intervention, and decreased to the level in the control group after 1 month.

3. The expression of arp2/3 in the hippocampus of the isoflurane group was decreased on the day 1 and day 7 after the intervention, and was restored to the level in the control group. Ro25-6981 can mitigate the down-regulated arp2/3 by isoflurane.

4. The dendritic spine density of hippocampal neurons in isoflurane group were decreased on the day 1 and day 7 after the intervention, and was restored to the level in the comtrol group after 1 month. Ro25-6981 could improve the degeneration of dendritic spine with isoflurane.

5. There were no significant differences in the values of arterial blood gas analysis and blood glucose test in our experiment.

Conclusion:

1. Isoflurane can cause reversible cognitive dysfunction in aged rats.

2. Isoflurane can up-regulate the expression of extrasynaptic GluN2B and decrease dendritic spine density in the hippocampus of aged rats. inhibiting extrasynaptic GluN2B can improve the degeneration of dendritic spines.

3. GluN2B can regulate dendritic spines through arp2/3; inhibition of extracellular extrasynaptic GluN2B can improve the downregulation of arp2/3 by isoflurane and the subsequent dendritic spine degeneration and cognitive dysfunction.

语种: 中文
相关网址: 查看原文
内容类型: 学位论文
URI标识: http://ir.bjmu.edu.cn/handle/400002259/124745
Appears in Collections:北京大学第三临床医学院_学位论文

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作者单位: 北京大学第三临床医学院

Recommended Citation:
李伦旭. 海马突触后NMDA受体在异氟烷麻醉后老年大鼠认知功能改变中的作用[D]. 北京大学第三临床医学院. 北京大学. 2016.
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