七氟醚不同麻醉时间对大鼠认知功能的影响及机制

Effects of different duration of sevoflurane anesthesia on cognitive function of rats

目的观察七氟醚不同麻醉时间对大鼠认知功能及海马神经元α7乙酰胆碱受体(α7-n AchR)表达的影响。方法将96只SD大鼠随机分成七氟醚1、2、3组和对照组各24只,对照组吸入空气,七氟醚1、2、3组分别吸入3%七氟醚1、3、5 h。四组分别于麻醉前完成为期5 d的定位航行实验,麻醉后1、7 d各取12只大鼠进行空间探索实验,记录逃避潜伏期、目标象限持续时间、目标象限路程、总路程、穿越平台次数,计算原平台所在象限时间占总时间比、原平台所在象限路程占总路程比。空间探索实验结束后麻醉大鼠,开颅取海马组织标本,采用Western blotting法检测α7-n AchR蛋白表达,实时荧光定量PCR法检测α7-n AchR mRNA表达。结果与对照组比较,七氟醚1、2、3组各时点目标象限持续时间均缩短,原平台所在象限时间占总时间比、原平台所在象限路程占总路程比均下降(P均<0.05);与七氟醚1、2组比较,七氟醚3组麻醉后1 d目标象限路程、目标象限持续时间均缩短,原平台所在象限时间占总时间比、原平台所在象限路程占总路程比下降(P均<0.05);与对照组比较,七氟醚1、2、3组各时点α7-n AchR蛋白和mRNA表达量均下降(P均<0.05);七氟醚1、2、3组各时点进行组间比较,α7-n AchR蛋白和mRNA表达呈下降趋势,但差异无统计学意义(P均>0.05)。结论吸入3%七氟醚麻醉1、3、5 h均可导致大鼠认知功能减退,麻醉5 h导致的认知功能减退更明显;其机制可能与α7-n AchR蛋白和mRNA表达下调有关。

Objective To observe the effects of different duration of sevoflurane anesthesia on the cognitive function and the expression of α7-acetylcholine receptor（ α7-n AchR） in hippocampal neuron of rats. Methods Ninety-six SD rats were randomly divided into four groups（ n = 24） ： the control group（ C） which inhaled air,and three other groups which were exposed to 3% sevoflurane for 1（ S1）,3（ S2）,and 5 h（ S3）,respectively. All rats were trained 5 days by the orientation navigation experiment before anesthesia,12 rats in each group were tested by space exploration experiment at 1 and7 days after anesthesia,and we recorded escape latency,the duration of staying in the target quadrant,the swimming distance in target quadrant,total distance,number of crossing platforms,and calculated the ratio of the duration in the original platform quadrant to the total duration,and the ratio of the distance in the original platform quadrant to the total distance. All rats were executed at 1 and 7 days after anesthesia,the hippocampal tissues were obtained for determination of the protein and mRNA expression of α7-n AchR by Western blotting and real-time fluorescent quantitative PCR,respectively. Results Compared with the group C,the duration of staying in the target quadrant,the ratio of the duration in the original platform quadrant to the total duration,and the ratio of the distance in the original platform quadrant to the total distance were significantly decreased at 1 and 7 days after anesthesia in the S1,S2,and S3 groups（ all P〈0. 05）. Compared with the S1,S2 groups,the distance of swimming in the target quadrant,the duration of staying in the target quadrant,the ratio of the duration in the original platform quadrant to the total duration,and the ratio of the distance in the original platform quadrant to the total distance were significantly decreased at 1 day after anesthesia in the S3 group（ all P〈0. 05）.Moreover,compared with the group C,the protein and mRNA expression of α7-n AchR was significantly down-regulated at1 and 7 d after anesthesia in the S1,S2,S3 groups（ P〈0. 05）. In the S1,S2,S3 groups,the expression of α7-n AchR protein and mRNA showed a decreasing trend,but no significant differences in the protein and mRNA expression of α7-n AchR was found（ all P〈0. 05）. Conclusion Inhalation of 3% sevoflurane anesthesia for 1,3,and 5 h can lead to cognitive decline in rats,cognitive decline caused by anesthesia for 5 h is more obvious; its mechanism may be related to the down-regulation of α7-n AchR protein and mRNA expression.