异氟醚致老年大鼠认知能力下降与大脑神经元NMDAR2B及GABAR1的表达相关

发布时间：2018-09-07 07:47

【摘要】：术后认知功能障碍(postoperative cognitive dysfunction,POCD)是一种于麻醉及手术后出现的认知功能退化的中枢神经系统并发症,尤其以老年患者多见。其主要临床表现为人格的改变、记忆的损伤以及社交减退。POCD可延长老年患者的住院时间,增加患者的病死率,严重的影响了患者术后的生活质量。本研究拟通过探究不同浓度及不同持续时间的异氟醚吸入对老年大鼠认知功能障碍以及不同脑区NMDAR2B和GABAR1表达的影响。本研究通过对100只雄性SD老年大鼠,随机分组,分别为对照组(C组20只)和实验组(S组80只)。各组大鼠均于处理前进行为期五天的水迷宫实验,以使其能够产生稳定记忆。对照组吸入室温空气,实验组按照药物浓度和吸入持续时间分为S1组(1.5%-2h),S2组(2.5%-2h),S3组(1.5%-4h),S4组(2.5%-4h)。C组和S组均分别在吸入室温空气和不同浓度药物后1、7 d进行Morris水迷宫实验来测试其学习记忆能力,并在测试结束两小时后进行开颅取脑,采用实时荧光定量多聚核苷酸链式反应和免疫荧光技术检测海马及颞叶的GABAR1和NMDAR2B的mRNA的转录水平和蛋白表达水平。通过Morris水迷宫测试结果,我们发现吸入异氟醚1d后的各实验组大鼠的穿越平台次数与对照组相比有明显下降,且随着药物浓度的增高和吸入持续时间的增加,大鼠学习记忆能力下降程度越明显;各实验组大鼠的逃避潜伏期与对照组相比出现延长,且与药物浓度增高和药物持续时间的增加有一定相关性。吸入异氟醚7 d后,S1,S2,S3组大鼠的穿越平台次数和逃避潜伏期与对照组差异无统计学意义,但S4组大鼠穿越次数明显低于对照组和其他三组,逃避潜伏期时间明显长于对照组和其他三组。并且大鼠这种改变与我们应用免疫荧光及实时荧光PCR检测出来的结果是一致的。免疫荧光及实时荧光定量PCR显示,吸入异氟醚1d后的各实验组大鼠颞叶及海马中GABAR1的蛋白含量及转录水平与对照组相比明显上调,且随着药物浓度的增高和吸入持续时间的增加上调的越明显。吸入异氟醚7d后的S1,S2,S3组中GABAR1的蛋白含量及转录水平与对照组相比差异无统计学意义,而S4组有明显上调。另外,免疫荧光及实时荧光定量PCR还显示,吸入异氟醚1d后的各实验组大鼠颞叶及海马中NMDAR2B的蛋白含量及转录水平与对照组相比明显下调,且随着药物浓度的增高和吸入持续时间的增加下调的越明显。吸入异氟醚7d后的S1,S2,S3组中NMDAR2B的蛋白含量及转录水平与对照组相比差异无统计学意义,而S4组有明显下调。进而我们也就得出了结论,持续吸入异氟醚对短期空间记忆能力的影响显著,且长时间高浓度的吸入造成的影响时间较长;异氟醚影响空间记忆能力的改变与NMDAR2B表达的下调及GABAR1表达的上调相关;吸入异氟醚麻醉不仅造成了海马区相关蛋白的改变,而且在颞叶也发生了与海马相似的改变,我们推测术后认知功能障碍可能是由多脑叶及多脑区共同参与的。
[Abstract]:Postoperative cognitive dysfunction (POCD) is a central nervous system complication that occurs after anesthesia and surgery, especially in elderly patients. This study was designed to investigate the effects of isoflurane inhalation with different concentrations and duration on cognitive impairment and the expression of NMDAR2B and GABAR1 in different brain regions in aged rats. The control group inhaled room temperature air. The experimental group was divided into S1 group (1.5% - 2h), S2 group (2.5% - 2h), S3 group (1.5% - 4h), S4 group (2.5% - 4h), C group (2.5% - 4h) and S group (2.5% - 4h). Morris water maze test was performed at 1,7 days after inhalation of air at room temperature and different concentrations of drugs to test their learning and memory abilities. Brain samples were taken two hours after the test. The transcriptional levels of GABAR1 and NMDAR2B mRNA in hippocampus and temporal lobe were detected by real-time fluorescence quantitative polymerase chain reaction and immunofluorescence technique. The results of Morris water maze test showed that the number of crossing platforms in rats inhaled isoflurane decreased significantly compared with the control group one day after inhalation, and with the increase of drug concentration and inhalation duration, the ability of learning and memory of rats decreased more significantly; escape potential of rats in each experimental group After 7 days inhalation of isoflurane, there was no significant difference in the number of crossing platforms and escape latencies between S1, S2 and S3 groups and the control group, but the number of crossing platforms and escape latencies in S4 group were significantly lower than those in the control group and the other three groups. The incubation period was significantly longer than that of the control group and the other three groups, and the changes were consistent with the results detected by immunofluorescence and real-time fluorescence PCR. Immunofluorescence and real-time fluorescence quantitative PCR showed that GABAR1 protein content and transcription level in temporal lobe and hippocampus of rats inhaled isoflurane 1 day after inhalation were compared with the control group. The protein content and transcription level of GABAR1 in S1, S2, S3 groups after inhalation of isoflurane were not significantly different from those in control group, but significantly increased in S4 group. The protein content and transcription level of NMDAR2B in temporal lobe and hippocampus of rats in each experimental group were significantly lower than those in the control group one day after isoflurane inhalation, and the decrease was more obvious with the increase of drug concentration and inhalation duration. The protein content and transcription level of NMDAR2B in S1, S2, S3 groups were lower than those in the control group seven days after isoflurane inhalation. There was no significant difference between the two groups, but the expression of NMDAR2B was down-regulated in group S4. We also concluded that isoflurane inhalation had a significant effect on short-term spatial memory, and the effect of long-term high concentration inhalation was longer; the change of isoflurane on spatial memory was related to the down-regulated expression of NMDAR2B and the up-regulated expression of GABAR1. Inhaled isoflurane anesthesia not only caused changes in hippocampal related proteins, but also similar changes in the temporal lobe and hippocampus. We speculate that postoperative cognitive impairment may be caused by multiple lobes and multiple brain regions.
【学位授予单位】：河北北方学院
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：R614

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