基因沉默对缺血脑组织水通道蛋白4表达的影响

AQP4 expression of the cerebral ischemic tissue following its mRNA silence in rat

研究基因沉默对缺血性脑组织水通道蛋白4（AQP4）表达的干预效果。方法：选成年Wistar大鼠，随机分为缺血组、对照组、干扰组，每组再分0．25、0．5、1、2、4及6h组。分别进行右侧大脑中动脉栓塞（MCA（）I缺血组）、注射无意义短发夹（shorthairpin）RNA-AQP4脂质体（shRNA-AQP4＋MCA（）_对照组）及干扰剂（siRNA-AQP4＋MCAO-干扰组），随后进行右侧基底节组织的病理观察、免疫组织化学、荧光定量PCR及免疫印迹检测。结果：对照组与缺血组的AQP4表达差异无统计学意义，AQP4在0．25h出现表达增强，2h内快速增加，4～6h期间缓慢上升。干扰组与对照组对比，0．25、6h时AQP4表达差异无统计学意义，0．5～4h期间AQP4表达轻度上调，差异有统计学意义，4～6hAQP4表达回升。病理显示对照组与缺血组相似，在2h内的病理改变为细胞内水肿，4～6h出现血管源性水肿。干扰组在2h内的细胞内水肿明显减轻，4h后的血管源性水肿无明显改善。结论：AQP4表达上调是缺血性细胞内水肿的分子基础，AQP4基因沉默能有效减轻细胞内水肿，但对血管源性水肿的AQP4表达干扰作用下降。

To investigate the effect of RNA interference targeting AQP4 on its expression in the cerebral ischemic tissues. Methods： Total 108 Wistar rats were divided into three groups randomly： ischemic groups （MCAO）, control group （shRNA-AQP4＋MCAO） and interference groups （siRNA-AQP4 ＋ MCAO）. Each group was subdivided into six sub- groups according to the different interval of time points： 0. 25 h, 0. 5 h, 1 h, 2 h, 4 h and 6 h （n = 6 for each group）. The right middle cerebral artery of rats was unilaterally occluded （MCAO） in ischemic groups. The reagent including nonsense short hairpin （shRNA） liposomes and short interference （siRNA）-AQP4 liposomes were injected to the right basal ganglia of the rats of MCAO served as a control group and an interference group, respectively. The animals were sacrificed and per- fused with the mixture solution consisting formalin. The right basal ganglia tissues were examined with pathology, immuno- histochemistry, real time fluorescence quantitative reverse transcript polymerase chain reaction （RT-PCR） and Western blot- ting. Results： There was no significant change in AQP4 expression between the control group and the ischemic group. The expression of AQP4 increased rapidly within 2 h, and then increased slowly during 4-6 h. Whereas, there was no significant change in AQP4 expression between the control group and the interference group at 0. 25 h and 6 h after MCAO. But there was significant change in AQP4 expression between the control group and the interference group during 0. 5-4 h. The AQP4 expression could be inhibited efficiently by RNA silencing technique during 0. 5-4 h, but it became unconspicuous during 4-6 h. The corresponding histological changes within 4 h were intracellular edema in the ischemic group and the control group, but this pathological change was obviously mitigated in the interference group during the same period of time. With the pro- gress of the time （4-6 h）, The vasogenic brain edema was mostly observed in histological changes. Conclusion： The results imply that the up-regulation of AQP4 expression may be the molecular mechanism of the intracelluar edema, AQP4 expres- sion in cerebral ischemic tissues as well as intracellular edema can be effectively inhibited by RNA silencing. However, it be- comes ineffectively in the stage of vasogenic brain edema.