海马REV-ERBα在大鼠术后认知功能障碍中的作用

Role of hippocampal REV-ERBαin postoperative cognitive dysfunction in rats

目的评价海马REV-ERBα在大鼠术后认知功能障碍(POCD)中的作用。方法SPF级健康雄性SD大鼠32只,体重360~380 g,12~14周龄,采用随机数字表法分为4组(n=8):对照组(C组)、手术组(S组)、手术+二甲基亚砜组(SD组)和手术+SR9009组(SS组)。S组、SD组和SS组在七氟烷麻醉下进行剖腹探查术;SD组于剖腹探查术前1 h时于海马CA1区注射含0.1%二甲基亚砜的生理盐水,每侧2μl;S+SR9009组于剖腹探查术前1 h时于海马CA1区注射REV-ERBα激动剂SR9009(溶于含0.1%二甲基亚砜的生理盐水中),每侧2μl。分别于术后1和3 d时行Morris水迷宫实验。术后3 d水迷宫实验结束后1 h时处死大鼠,取海马组织,采用Western blot法检测REV-ERBα、脑和肌肉ARANT样蛋白1(BMAL1)、突触素(SYN)、突触后密度蛋白95(PSD95)和N-甲基-D-天冬氨酸受体2B亚基(GRIN2B)表达水平;采用尼氏染色观察海马神经元及尼氏小体形态,并行存活神经元计数。结果与C组比较,S组和SD组术后1和3 d时目标象限停留时间百分比降低,穿越平台次数减少,海马REV-ERBα、BMAL1、PSD95、SYN和GRIN2B表达下调,CA1区存活神经元计数降低(P<0.05);与S组和SD比较,SS组术后1和3 d时目标象限停留时间百分比升高,穿越平台次数增多,海马REV-ERBα和PSD95表达上调,CA1区存活神经元计数升高(P<0.05),BMAL1、SYN和GRIN2B表达无统计学意义(P>0.05)。S组和SD组上述各指标比较差异无统计学意义(P>0.05)。结论REV-ERBα激活可改善大鼠POCD,其机制可能与上调海马PSD95表达,减轻神经元损伤有关。

Objective To evaluate the role of hippocampal REV-ERBαin postoperative cognitive dysfunction in rats.Methods Thirty-two SPF healthy male Sprague-Dawley rats,aged 12-14 weeks,weighing 360-380 g,were divided into 4 groups(n=8 each)using a random number table method:control group(group C),surgery group(group S),surgery+dimethyl sulfoxide(DMSO)group(group SD),and surgery+SR9009 group(group SS).Exploratory laparotomy was performed under sevoflurane anesthesia in S,SD and SS groups.Normal saline containing 0.1%DMSO was injected into hippocampal CA1 area at 1 h before laparotomy,with 2μl on each side in group SD,and REV-ERBαagonist SR9009(in normal saline containing 0.1%DMSO)was injected into hippocampal CA1 area at 1 h before laparotomy,with 2μl on each side in group S+SR9009.Morris water maze test was performed at 1 and 3 days after operation.Rats were sacrificed at 1 h after the end of Morris water maze test on day 3 after surgery,and the hippocampal tissues were obtained for determination of the expression of REV-ERBα,Brain and Muscle ARNT-Like 1(BMAL1)protein,synaptophysin(SYN),postsynaptic density(PSD)-95 protein and N-methyl-D-aspartate receptor 2B subunit(GRIN2B)(by Western blot)and microscopic examination of the morphology of hippocampal neurons and Nissl bodies(by Nissl staining),and the viable neurons were counted.Results Compared with group C,the percentage of time of staying at the target quadrant was significantly decreased,and the number of crossing platform was reduced on days 1 and 3 after exploratory laparotomy,the expression of REV-ERBα,BMAL1,PSD95,SYN and GRIN2B was down-regulated,and the number of viable neurons was decreased in group S and group SD(P<0.05).Compared with group S and group SD,the percentage of time of staying at the target quadrant and the number of crossing platform were significantly increased on days 1 and 3 after exploratory laparotomy,the expression of REV-ERBαand PSD95 was up-regulated,the number of viable neurons was increased(P<0.05),and no significant change was found in the expression of BMAL1,SYN and GRIN2B in group SS(P>0.05).There was no significant difference in the indexes mentioned above between group S and group SD(P>0.05).Conclusions Activation of REV-ERBαcan improve postoperative cognitive dysfunction,and the mechanism may be related to up-regulation of PSD95 expression in hippocampus and reduction of neuronal damage in rats.