Bcl-2过度表达对全脑缺血再灌注后大鼠海马回P53蛋白表达的影响

Effect of overexpression of Bcl-2 on expression of P53 protein in hippocampal gyrus after global cerebral ischemia-reperfusion in rats

目的：研究过度表达Bc-l2的大鼠全脑缺血再灌注后P53在海马回的表达,探讨Bc-l2的抗凋亡作用及机制。方法：雄性健康SD大鼠随机分为3组（n=30）。缺血再灌注组（IR组）,采用4-血管法建立全脑缺血再灌注模型,6 min缺血后给予再灌注;假手术组（SO组）,只暴露血管而不夹闭;Bc-l2过度表达组（Bc-l2组）,Bc-l2过度表达大鼠模型造模成功后处理同IR组。所有动物于6、12、24、48、72及96 h行4%多聚甲醛灌注处理,将脑组织切片行免疫组化染色、原位末端标记法和HE染色,光镜下观察P53在海马回CA1和CA3区的表达、神经元形态及结构的变化以及凋亡神经细胞数,结果行统计学分析。结果：①全脑缺血再灌注后24 h,IR组CA1区P53蛋白开始表达,程度较弱,随后逐渐增加,于72 h达高峰后下降,主要位于胞核;CA3区于再灌注后48 h才出现P53蛋白的表达,72 h达高峰,但表达强度较CA1区弱（P〈0.05）。Bc-l2组CA1和CA3区P53蛋白表达强度均弱于IR组（P〈0.05）,主要位于胞浆。②HE染色：全脑缺血再灌注后72 h,IR组CA1区有明显组织水肿,神经元数目降低,排列紊乱,核膜不清晰,未见核仁;CA3区神经元损伤程度较CA1区轻（P〈0.05）;Bc-l 2组神经元损伤较IR组轻（P〈0.05）。③原位末端标记法染色：与SO组比较,IR组海马CA1区全脑缺血再灌注后24~48 h凋亡细胞数最多（P〈0.01）,再灌注后72 h海马CA1区凋亡细胞数开始减少;与IR组比较,Bc-l2组凋亡细胞均较少（P〈0.05）。结论：Bc-l2过度表达可抑制大鼠全脑缺血再灌注后P53在海马回的表达。

Objective To investigate the expression of P53 protein in hippocampal gyrus in rats with Bcl-2 overexpression after global cerebral ischemia/reperfusion and discuss the effect and mechanism of anti-apoptosis of Bcl-2. Methods 90 healthy male SD rats were randomly divided into 3 groups（n=30）. Ischemia-reperfusion group （IR group）： global cerebral ischemia-reperfusion model was produced by 4-VO method. Reperfusion were performed 6 min after cerebral ischemia~ sham operation group（SO group）; the blood vessels were just exposed without occlusion; Bcl-2 overexpression group（Bcl-2 group）： the rats were dealed as the same as IR group after establishment of the model of rats with Bcl-2 overexpression. All the animals were executed at 6, 12, 24, 48,72 and 96 h by 4 % poly-formaldehyde perfusion. Immunohistoehemical staining, TUNEL staining and HE staining of brain tissue section were performed. The changes of neuron form of hippocampal gyrus, the expression of P53 in CA1 and CA3, and the number of apoptotic cells were observed with light microscope. All the data was analyzed by SPSS 10. 0. Results ①24 h after global cerebral ischemia-reperfusion, the P53 protein expressed weakly in CA1, increased gradually and peaked at 72 h, then decreased; and mainly localized in cell nucleus. The expression of P53 protein in CA3 appeared at 48 h after global cerebral ischemia-reperfusion, peaked at 72 h, which were weaker than that in CA1. The expressions of P53 protein in CA1 and CA3 in Bcl-2 group were much weaker than those in IR group（P〈0.05）. ② HE staining showed the number of neuron in CA1 in IR group was decreased at 72 h after global cerebral ischemia-reperfusion, companying with neuron disarrangement, nucleus membrane indistinction and nucleolus disappearance. The change in CA3 was slighter than that in CA1 （P〈0. 05） and the changes in Bcl-2 group was slighter than that in IR group（P〈0.05）. ③ TUNEL staining showed the number of apoptotic cells peaked at 24 h after global cerebral ischemia-reperfusion in CA1 of hippocampus（P〈0.01）, continued until 72 h in 1R group compared with SO group. While the positive cells appeared mainly at 72 h in CA3 compared with IR group. The number of apoptotic cells in Bcl-2 group was less（P〈0. 05）. Conclusion Overexpression of Bcl-2 can inhibit the expression of P53 in hippocampal gyrus after global cerebral ischemia-reperfusion in rats.