脑动脉微栓子诱发非梗死性脑损伤大鼠模型的建立

Establishment of a brain injury model without infarction induced by cerebral artery microemboli in rats

目的为探讨脑动脉微栓子的神经损伤机制,建立脑梗死阈值下脑动脉微栓子诱发脑损伤的大鼠模型。方法 24只SD大鼠随机分为微栓子组和假手术组。造模后,每组又分为3d和7d组,每组6只大鼠。经左侧颈内动脉分别注入25～50μm大小的全血凝块微栓子100个/300μl或等量的等渗盐水。于造模后3d和7d,采用HE染色观察有无梗死灶、TUNEL染色和Caspase-3蛋白免疫组化染色定量分析神经细胞凋亡的变化。结果微栓子组和假手术组所有大鼠HE染色未发现缺血梗死灶。TUNEL染色显示假手术组仅见少量凋亡细胞,而微栓子组凋亡细胞数量明显增多(P<0.001),并且随时间的延长而明显增加,7d组较3d组更明显(P<0.001)。蛋白免疫组化染色显示,假手术组仅见零星Caspase-3蛋白阳性表达,而微栓子组明显增加(P<0.001),并且7d组比3d组更明显(P<0.001)。结论 25～50μm的全血凝块微栓子以100个/300μl的浓度缓慢注入到大鼠颈内动脉,不一定能造成脑梗死,但可以导致神经细胞凋亡。

Objective To investigate the mechanisms of neurological injury of cerebral artery microemboli and establish a brain injury rat model induced by cerebral artery microemboli under the threshold of cerebral infarction. Methods Twenty-four SD rats were randomly assigned to microemboli group and sham operation group. Each rat in the microemboli group was injected 100 microemboli of 25 - 50 μm whole blood clot/300 μl. In the sham operation group or the same volume of normal saline was injected via left internal carotid artery. HE staining was used to observe whether there were infarction lesions or not at 3 and 7 days after surgery. The TUNEL staining and the Caspase-3 immunohistochemical staining were used to quantitatively analyze the changes of neuronal apoptosis. Results No isehmnie infarction was detected with HE staining in all the rats both in the sham-operation group and the microemboli group. TUNEL staining only showed a few apoptotic cells in the sham-operation group, and the number of apoptotic cells in the mieroemboli group increased significantly （P 〈 0. 001 ）, and significantly increased with time, and the 7- day group was more obvious than the 3-day group（ P 〈 0.001 ）. Protein immunohistologic staining showed that only sporadic positively expressed Caspase-3 proteins were observed in the sham operation group, while they increased significantly in the microemboli group （P 〈0. 001 ）. The 7-day group was more obvious than the 3-day group （ P 〈 0. 001 ）. Conclusion Injection of 100 microemboli of 25 - 50 μm whole blood clot/300 μl slowly into the rat internal carotid artery may not necessarily induce cerebral infarction, but it may result in neuronal apoptosis.