SIRT1对早期脑缺血大鼠水通道蛋白4表达的影响

Effect of SIRT1 on dynamic expression of AQP4 in early stage of cerebral ischemia in rats

目的:检测水通道蛋白4(AQP4)及沉默信息调节因子1(SIRT1)在脑缺血大鼠脑组织中的表达变化,探究SIRT1对AQP4的调节作用,明确二者在脑缺血及脑水肿发生发展中的作用。方法:雄性SD大鼠随机分成假手术组(sham组)和脑缺血模型组(MCAO组),其中MCAO组又分为6 h、12 h、24 h和48 h 4个时点组别。采用线栓法阻塞大脑中动脉建立局灶性脑缺血模型,于相应时点进行神经症状评分,Morris水迷宫检测大鼠学习认知功能,TTC染色观察脑梗死体积,干湿重法检测脑含水量的变化,HE染色观察大脑皮层周围组织神经细胞形态学变化,Western blot检测AQP4、SIRT1和基质金属蛋白酶9(MMP-9)的表达情况。结果:与sham组相比较,随着再灌注时间增加,MCAO组大鼠神经功能评分、脑梗死体积、脑组织通透性和脑组织含水量均持续增加,而大鼠学习认知功能则降低显著,HE染色显示脑缺血大脑皮层周围组织神经元细胞形态不规则,数目减少;Western blot实验结果显示AQP4表达水平呈增高趋势,SIRT1表达降低,MMP-9表达增高,MCAO-48 h组与sham组比较差异最明显(P<0.01)。结论:脑缺血后,伴随脑组织损伤的加剧,SIRT1和MMP-9信号通路的表达激活影响了AQP4的表达活化,共同参与了脑水肿的形成。

AIM：To investigate the pathological changes of aquaporin 4 （AQP4） and related proteins in the rats with focal cerebral ischemia injury , and to observe the effect of silent information regulator 1 （ SIRT1） on the AQP4 ex-pression in order to explore the pathological mechanism of cerebral ischemia and brain edema .METHODS： Adult male SD rats were randomly divided into sham group and middle cerebral artery occlusion （ MCAO） model group.The MCAO model group was divided into the 4 time point （6 h, 12 h, 24 h and 48 h） subgroups.The animal model of MCAO was es-tablished by suture method in mature SD rats .The neural symptom score was measured at the corresponding time points . Morris water maze test was used to study the cognitive function .The cerebral infarction volume was evaluated by TTC stai-ning .The changes of brain water content was analyzed by a dry /wet weight method .The morphological changes of the brain tissues were observed under microscope with HE staining .The protein expression of SIRT 1, MMP-9 and AQP4 was deter-mined by Western blot .RESULTS： Compared with sham group , the neural function score of the rats in MCAO model group was significantly elevated .With the increasing reperfusion time , the cerebral infarction volume , brain tissue permea-bility and the brain water content were also increased .The increases in the protein levels of AQP 4 and the related proteins showed apparent changes .The protein expression of SIRT 1 was decreased , while the MMP-9 expression was increased .The most obvious differences of the protein level changes in MCAO-48 h model group were observed （P〈0.01）.CONCLU-SION：Accompanied with the aggravating cerebral injury after cerebral ischemia , the process of AQP4 expression is activa-ted with the increasing expression levels of MMP-9 and SIRT1.These factors are combined to induce the formation of brain edema.