大鼠脑缺血再灌注后水通道蛋白-4表达与弥散加权成像表观弥散系数的相关性研究

Correlation between expression of aquaporin-4 and the apparent diffusion coefficiem on diffusion-weighted imaging after focal cerebral ischemia/reperfusion in rats

目的探讨缺血再灌注后脑组织表观弥散系数（apparent diffusion coefficient，ADC）与水通道蛋白-4（aquaporin-4，AQP4）表达的相关性。方法线栓法建立右侧大脑中动脉闭塞（middle cerebral artery occlusion,MCAO）模型，70只Wistar大鼠随机分为假手术组、MCAO30 min组、MCAO30 min再灌注30min组、MCAO30 min再灌注60min、MCAO60 min组、MCAO60 min再灌注30min和MCAO60 min再灌注60min组，每组10只。各组大鼠分别行弥散加权成像（diffusion-weighted imaging,DWI）检测相对ADC（relativeADC，rADC），用红四氮唑（triphenyltetrazolium chloride，TTC）染色检测缺血区面积比，应用免疫组织化学、原位杂交和逆转录聚合酶链反应等检测AQP4表达。结果假手术组DWI未见异常信号，其他MCAO30 min组、MCAO60 min组、MCAO30 min再灌注30min组、MCAO30min灌注60 min、MCAO60 min再灌注30min和MCAO60min再灌注60min组DWI高信号病灶范围由小扩大，随后逐渐缩小，缺血面积呈相同改变。MCAO30min组和MCAO60min组AQP4表达量显著上调，再灌注后各组AQP4表达显著下降，与MCAO30min组和MCAO60min龃相比均差异显著（P均〈0．05），rADE与AQP4表达呈负相关（r=-0．72，P〈0．01）。结论缺血再灌注后脑组织AQP4表达与ADC变化密切相关，DWI可间接反映AQP4表达水平。

Objective To investigate the correlation between the apparent diffusion coefficient （ADC） and the expression of aquaporin-4 （AQP4） in brain tissue after ischemia/ reperfusion in rats. Methods A model of fight middle cerebral artery occlusion （MCAO） was induced by suture method. Seventy Wistar rats were randomly divided into 7 groups： shamoperation （A）, MCAO 30 min （B）, MCAO 30 min and reperfusion 30 min （D）, MCAO 30 rain and reperfusion 60 min （E）, MCAO 60 min （C）; MCAO 60 min and reperfusion 30 min （F）, and MCAO 60 rain and reperfusion 60 rain （G） groups （n = 10 in each group）. The rats in all groups underwent diffusion-weighted imaging （DWI）. The relative apparent diffusion coefficient （rADC） was calculated. Triphenyltetrazolium chloride （TTC） staining was used to detect the ratio of ischemic area. Immunohistochemistry, in site hybridization, and reverse transcription-polymerase chain reaction （RT-PCR） were used to detect the expressions of AQP4. Results No abnormal intensity signals were observed on DWI in sham-operation group. The ranges of the high signal intensity lesions on diffusion-weighted imaging （DWI） were from small to large in groups B, C, D, E, F, and G. Then it reduced gradually, so did the ischemic area. The AQP4 expression was up-regulated significantly in groups B and E. The AQP4 expression was decreased significantly after the reperfusion in all groups. There was significant difference between ischemic groups and reperfusion groups （all P 〈 0.05）. The expressions of rADC and AQP4 showed negative correlation （r = 0.72, P 〈 0.01 ）. Conclusions The AQP4 expression in brain tissue is closely associated with the changes of ADC after cerebral ischemia/reperfusion. DWI may indirectly reflect the levels of AQP4 expression.