老龄大鼠局灶性脑缺血周围区DNA损伤的研究

The study of DNA damage in the perifocal area after focal cerebral ischemia in aged rats

目的 探讨老龄大鼠局灶性脑缺血周围DNA损伤特点。方法 应用HE染色、原位末端标记法 (TUNEL)标记、原位分子杂交、免疫组织化学等方法 ,分别对缺血 4、2 4h和 5d组大鼠脑组织中坏死细胞、凋亡细胞、p5 3mR NA、p5 3蛋白阳性细胞密度及空间分布进行观察和比较。结果 不同时间点病灶周围每高倍视野TUNEL、p5 3蛋白、p5 3mRNA的阳性细胞数分别为 4h :8.0± 1.5、2 5 .1± 2 .6、10 .3± 1.9;2 4h :2 0 .5± 2 .4、6 0 .0± 4.8、2 2 .0± 1.8;5d :2 .1± 0 .4、3.6± 1.4、3.5± 0 .8。p5 3基因主要在形态完整和可逆性损伤细胞中表达、分布范围较TUNEL细胞广泛。结论 局灶性脑缺血后 ,缺血周围DNA损伤区大于凋亡区 ,p5 3基因表达范围可能代表病理意义上的半暗带 ;p5

Objective To investigate the characteristics of DNA damage in the perifocal area after focal cerebral ischemia in aged rats.Methods HE staining,TUNEL labeling,in situ hybridization and immunohistochemical technique were used to observe the density and distribution of necrosis,apoptosis and p53 positive cells 4 h ,24 h and 5 days after focal cerebral ischemia in aged rats.Results The number of apoptosis,p53 protein and p53 mRNA positive cells in the perifocal area at different time points after ischemia were 8.0±1.5,25.1± 2.6 and 10.3±1.9 at 4 h;20.5±2.4,60.0±4.8 and 22.0±1.8 at 24 h;2.1±0.4,3.6±1.4 and 3.5±0.8 on day 5. The area with p53 positive cells was broader than that with apoptosis and p53 gene was expressed mainly in normal or reversibly damaged cells.Conclusions The area with DNA damage was larger than that with apoptosis.p53 positive cell region may represent the pathological penumbra and p53 may be involved in repair of damaged DNA.