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目的 研究大鼠大脑中动脉缺血再灌注时 ,DNA损伤随再灌注时程在各脑区的动态分布情况。方法 用线栓闭合大鼠大脑中动脉 30min ,然后分别再灌注 30min、1h、2h、4h、6h、12h、2 4h和 48h。采用原位PANT(DNA聚合酶Ⅰ介导的生物素标记的dATP缺口平移 )及原位TUNEL(末端脱氧核苷酸转移酶介导的dUTP末端标记 )分别检测DNA损伤的单链断裂 (SSBs)及双链断裂 (DSBs) ,分别观察SSBs细胞和DSBs细胞在大鼠前囟水平冠状切面的脑组织切片各区域的分布。结果 DNA单链断裂和双链断裂都首先发生在尾壳核 (CPU) ,而且在再灌注的各时间点 ,分布在尾壳核和梨状皮质 (PI)的PANT或TUNEL阳性细胞数量显著多于分布在额叶皮质 (FR)及顶叶皮质 (PA)的数量 (P <0 .0 5 )。DNA单链断裂比双链断裂发生要早。结论 尾壳核和梨状皮质是受缺血影响的中心区域 ,额叶和顶叶皮质是受缺血影响相对较轻的区域 ,可能是缺血半影区。
Objective To investigate the dynamic distribution of DNA damage during reperfusion in different brain regions during middle cerebral artery occlusion and reperfusion in rats. Methods The middle cerebral artery of rats were occluded for 30 min with thread plug, and then reperfused for 30 min, 1 h, 2 h, 4 h, 6 h, 12 h, 24 h and 48 h respectively. Single strand breaks (SSBs) of DNA damage were detected by in situ PANT (biotinylated dATP nick translation by DNA polymerase I) and in situ TUNEL (terminal deoxynucleotidyl transferase mediated dUTP end labeling) And double-strand breaks (DSBs). The distribution of SSBs and DSBs cells in each section of the coronal section of the rat bregma level was observed. Results Both DNA single strand breaks and double strand breaks first occurred in the caudate putamen (CPU). At each time point of reperfusion, the number of PANT or TUNEL positive cells distributed in the caudate putamen and piriform cortex (PI) was significantly higher In the frontal cortex (FR) and parietal cortex (PA) (P <0.05). DNA single strand breaks occur earlier than double strand breaks. Conclusions The caudate putamen and piriform cortex are the central areas affected by ischemia. The frontal and parietal cortex are relatively less affected by ischemia, which may be the ischemic penumbra.