高血压大鼠局灶脑缺血再灌注后X线修复交叉互补组1蛋白表达及DNA片段化损伤

目的　观察肾性高血压大鼠局灶脑缺血再灌注后DNA修复蛋白X线修复交叉互补组 1(XRCC1)蛋白的表达及与DNA片段化损伤的关系。方法　采用双肾双夹法建立肾性高血压大鼠模型 ,在此基础上采用线栓法制作大脑中动脉闭塞模型 ,采用免疫组织化学方法观察假手术组和缺血再灌注后 3h、6h、12h、2 4hXRCC1蛋白表达 ,采用TUNEL方法检测DNA片段化损伤。结果　免疫组织化学染色显示 ,假手术组大脑皮质和海马区出现大量XRCC1表达的阳性细胞 ,再灌注 3h缺血区皮质和海马CA1区XRCC1表达阳性细胞减少 ,即缺血区皮质和海马CA1区XRCC1灰度值升高 ,并一直持续到缺血再灌注 2 4h。缺血再灌注后 3h、6h、12h和 2 4h与假手术组相比差异有显著意义 (P <0 0 5 )。TUNEL染色显示 ,假手术组大脑皮质和海马CA1区未见阳性细胞 ,再灌注 2 4h缺血区皮质和海马CA1区可见较多阳性细胞。结论　脑缺血再灌注后XRCC1蛋白免疫活性下降和DNA修复机制的失败与DNA的片段化损伤及凋亡的发生有关。

Experiment study on XRCC1 and DNA fragmentation after cerebral ischemia/reperfusion of renovascular hypertensive rats

Objective To explore the relationship between the expression of DNA repair protein X ray repair cross complementing group 1(XRCC1) and DNA fregmentation in neuronal cell after cerebral ischemia/reperfusion of renovascular hypertensive rats(RHR).Methods The 2 kinney,2 clip method was used to induce hypertension in male healthy Sprague Dawley rats with the ring shaped sliver clips.The model of the middle cerebral artery occlussion(MCAO) was established with introluminal filament occlusion.Immunohistochemistry staining was used to facilitate the observation of XRCC1 protein expression in the brain tissues following the sham operation group and focal cerebral ischemia/reperfusion(FCI/R) group at 3h,6h,12h and 24h,respectively.DNA damage was evaluated by terminal deoxynucleotidyl transferase mediated uridine 5' triphosphate biotin nick end labeling(TUNEL).Results Immunohistochemistry showed the nuclear expression of XRCC1 in all regions of the sham operation group.The gray value of XRCC1 was increased in ischemic cortex and CA 1 region of hippocampus as early as 3 hours after FCI/R and remained increased until 24 hours after FCI/R.There was inverse proportion between the expression quantities of XRCC1 and gray value.Compared with sham operation group,gray value of XRCC1 in focal cerebral ischemia group at reperfusion 3h,6h,12h and 24h was significantly highter(P<0.05).DNA fregmentation was detected by TUNEL 24 hours after FCI/R.Conclusion Our results suggest that the early decrease of XRCC1 and the faiture of DNA repairing mechanism may contribute to the DNA fragmention and the apoptosis after FCI/R.