【作者】 何占平；

【导师】 鲁宏；

【作者基本信息】 遵义医学院 ， 影像学与核医学， 2010， 硕士

【摘要】 目的探讨siRNA-AQP4干扰水通道蛋白-4(AQP4)对早期缺血性脑水肿的影响与磁共振成像的关系。方法将64只Wistar大鼠,随机分为4组,即正常组1只、假手术组3只、对照组(采用Benses法行MCAO手术)30只和治疗组(MCAO+SiRNAAQP4基底节注射)30只。将后2组再进一步分为6小组(每小组各5只),在术后15min、30 min、1h、2h、4h及6h应用DWI图像分析技术测定缺血区面积(rs-DWI)、ADC值、采用免疫组化、原位杂交、RT-PCR、Westen Blotting测定AQP4的表达水平,同时用光镜和透射电镜(TEM)进行对应部位的病理观察。结果正常组与假手术组的MRI未见异常,脑组织无病理改变,AQP4表达无明显变化。对照组：在缺血后15min-6h在DWI上出现高信号,rs-DWI在15min-1h内快速增加,2h-6h缓慢增加；AQP4蛋白表达均见明显增加；在1h内增加最为迅速；治疗组：在缺血后15min-6h亦在DWI上出现高信号,随着时间延长,rs-DWI逐渐增加,ADC值在15min开始逐渐下降,2h降至最低点后逐渐上升。治疗组与对照组比较,30min-4h时间段rs-DWI、AQP4蛋白表达治疗组均减少,两组间具有明显差异(P<0.05)。15min及6h时间点内两组间未见明显差异(P>0.05)。结论DWI能及时、快速、准确的反映早期缺血性脑水肿的病理过程。AQP4表达上调是缺血性胶质细胞内水肿时rADC值下降分子基础,AQP4 mRNAi沉默技术能有效的抑制AQP4表达上调,减轻胶质细胞内水肿程度,逆转半暗带组织,从而缩小DWI高信号范围。RNA干扰(RNAi)AQP4在30min-4h时间内可以使脑组织内AQP4 mRNA及AQP4蛋白表达减少,并且在相应时间点内脑水肿程度减轻,对照组缺血面积较治疗组缺血面积减小(P<0.05)。15min及6h治疗组缺血面积比手术组缺血面积影响未见明显变化(P>0.05),治疗组r-DWI比手术组r-DWI在30min、1h、2h及4h时间内rADC值明显升高(P<0.05);15min及6h未见明显变化(P>0.05)。AQP4蛋白表达与rs-DWI呈明显正相关；AQP4蛋白表达在15min-2h与rADC呈明显负相关。更多还原

【Abstract】 Objective The aim of this study was to investigate siRNA-AQP4 interference of water channel protein-4 (AQP4) in early ischemic brain edema and the diagnostic values of diffusion-weighted imaging (DWI).Methods The 64 Wistar rats were randomly divided into 4groups:The normal group(n=1), sham operation group(n=3), the control group(MCAO) and treatment group (MCAO+SiRNA),After the two groups would be further divided into 6 groups (n=5 for each group). In after 15 min,30 min,1 h,2h,4h and 6 h time point were used immunohistochemistry, in situ hybridization, RT-PCR, Westen Blotting and MRI image analysis technique in determining the expression level of AQP4 infarct area and infarct size determination, and at the same time light and transmission electron microscopy (TEM) for the corresponding parts of the observation.Results Normal group and sham operation group of the MRI were normal, no pathological changes in brain tissue, AQP4 expression was not changed significantly. Control group:in ischemia and 15 min-6h after appearing in the DWI high signal rs-DWI is increasing rapidly, AQP4 protein expression was markedly increased, rs-DWI is a rapid increase, Treatment group:15 min-6 h after ischemia has also appeared on DWI high signal, with time, rs-DWI gradually increased, ADC value decreased gradually, Between treatment group with control group,30min-4-hour time segment rs-DWI, AQP4 protein expression between the two groups with significant difference (P<0.05). Within 15min arid 6h time points no significant difference between the two groups (P> 0.05).Conclusion The results imply that the up-regulating of the AQP4 expression is the molecular mechanism of the acute ischemic edema, which is result in the decreasing of the rADC. RANi might be effective technique for treat IP. But it become ineffectively With the progress of the time(4 h-6 h) after MCAO, which the pathologic changes in the stage was mixedema. The DWI could provide valuable imaging information for diagnostic the acute ischemic edema.RNA interference (RNAi) AQP4 in 30min, 1h,2h and 4h time can make brain tissue mRNA and AQP4 protein expression was decreased, and the corresponding time period in brain edema, the treatment group than the surgery group ischemic area of ischemic area reduced; 15min and 6h the impact on the brain edema was no significant change in the treatment group rs-DWI rs-DWI than the surgical group no significant change. AQP4 protein expression and rs-DWI was positively correlated. AQP4 protein expression was negatively correlated with the rADC.更多还原