新生大鼠脑缺氧缺血后半胱天冬酶-3激活与DNA损伤的关系

The relationship of caspase-3 activation and DNA damage in the neonatal rat cerebral hypoxia-ischemia

目的 :探讨未成熟脑在缺氧缺血 (H1)后海马神经细胞半胱天冬酶 3的激活与DNA损伤之间的关系。方法 :采用 7日龄新生大鼠脑缺氧缺血模型 ,观察HI后不同时间点脑组织海马CA1、CA3区半胱天冬酶 3活性亚单位p17阳性细胞及检测DNA双链断裂的寡核苷酸探针 (HPP)标记阳性细胞的分布。结果 :HI后 3h在海马CAl、CA3区即可检测到p17及HPP阳性细胞 ,并随HI时间延长而增加。在CAl区阳性细胞计数 2 4h达到峰值 ,而在CA3区 72h仍有较多阳性细胞 ,p17和HPP标记的阳性细胞在各时间点具有相同的变化规律。双重染色证实 ,p17和HPP在海马神经元中同时表达。结论 :未成熟脑HI后海马区半胱天冬酶 3被激活并伴随DNA双链的断裂 。

Objective: To study the relationship of caspase 3 activation and DNA damage in the immature rat brain with hypoxia-ischemia(HI).Methods: 7 day rat pups with HI were studied. The temporal pattern of caspase 3 pl7 immunoactivity and DNA double strand breaks which was detected by hairpin oligonuclieotides probes (HPP) were examined in the hippocampus CAI and CA3.Results: Caspase 3 pl7 and HPP positive cells could be found in the CAI and CA3 areas of hippocampus at 3 h post HI and the number of positive cells increased with the prolongation of reperfusion. It reached peak at 24 h in CAI . It reached peak at 3d in CA3 however. Both of them had similar changes at different timepoints afier HI. Double labeling of caspase 3 pl7 and HPP showed they colocalized well at all the timepoints.Conclusion: Caspase 3 was activated, which was accompanied with DNA double strands breaks (apoptosis) in the hippocampus after HI. Both caspase 3 pl7 and HPP were sensitive and specific markers for detecting apoptosis.