全脑缺血损伤大鼠大脑海马CA1区神经细胞的死亡机制研究

Cell death mechanism in hippocampal CA1 region of rat with global cerebral ischemic injury

摘要:

目的： 探讨全脑缺血损伤时大鼠大脑海马CA1区神经细胞的死亡机制。方法：采用双侧颈总动脉夹闭的方法制作大鼠全脑缺血模型，成功制造模型后分别于缺血0、5、10、15、20、25、30 min进行取材。采用TTC染色和脑组织含水量进行模型鉴定；采用光学、电子显微镜技术观察全脑缺血大鼠的大脑海马CA1区的形态学变化；分别采用免疫组化和免疫印迹方法检测大鼠大脑海马CA1区的多聚二磷酸腺苷核糖聚合酶-1（poly adenosine diphosphate ribose polymerase-1，PARP-1）和半胱氨酸蛋白酶-3（Caspase-3）蛋白的表达情况。结果：PARP-1阳性表达定位于海马CA1区神经细胞核，Caspase-3阳性表达定位于细胞质。PARP-1的免疫印迹在缺血0 min组大脑海马CA1区呈微弱表达（0.023 3±0.035 1），而5 min时PARP -1的表达增强（0.710 0±0.112 7），至15 min时呈高表达（1.063 3±0.090 7），持续至30 min（1.490 0±0.183 3），且与0 min组比较差异有统计学意义（P=0.000）。而缺血0 min时大脑海马CA1区Caspase-3则呈阴性表达，于缺血5 min时可见阳性表达（0.080 0±0.020 0），持续至30 min（0.270 0±0.052 9），且与0 min组比较差异有统计学意义（P=0.006）。结论：细胞胀亡参与了全脑缺血性损伤大鼠海马CA1区神经细胞死亡，其原因是由PARP-1的过度激活所导致。

Abstract:

Objective：To explore the cell death mechanism in hippocampal CA1 region of rats with global cerebral ischemic injury. Methods：Global cerebral ischemia model was established using bilateral carotid artery occlusion method and samples were acquired at 0，5，10，15，20，25，30 min respectively after model establishment. Model identification was made by TTC staining and brain wa－ter content detection. Morphological changes in hippocampal CA1 region of rats with global cerebral ischemic injury were observed by optical and electron microscopy. Immunohistochemistry and immunoblotting were used to detect the protein expression of poly adeno－sine diphosphate ribose polymerase-1（PARP-1） and Caspase-3 in hippocampal CA1 region of rats. Results：Positive expression of PARP-1 was located in nerve nucleus in hippocampal CA1 region and positive expression of Caspase-3 was located in the cyto－plasm. PARP-1 expressed mildly in hippocampal CA1 region at 0 min（0.023 3±0.035 1），obviously enhanced at 5 min（1.063 3±0.090 7 and continued until 30 min（1.490 0±0.183 3），which was different from that of 0 min（P=0.000）. Caspase-3 expressed neg－atively at 0 min of ischemia and expressed positively at 5 min of ischemia（0.080 0±0.020 0） and lastes for 30 min. there were sta－tistical differences in expression of Caspase-3 at 5 min and 0 min（P=0.006）. Conclusions：Oncosis involves in the cell death of glob－al cerebral ischemic injury and the reason is excessive activation of PARP-1 after ischemic brain injury.