不同缺血时程对小鼠脑缺血模型脑损伤的影响

Effects of different ischemic time on brain injury in brain ischemia model of mice

背景急性脑梗死患者首选治疗方法是溶栓治疗,而溶栓的早晚决定着患者的预后。目的该研究通过建立国际标准的小鼠大脑中动脉阻塞(MCAO)局灶性脑缺血模型,来观察不同脑缺血时程对脑组织损伤程度的影响,以明确再灌注的早晚与脑缺血损伤之间的关系。方法气体麻醉下,采用线栓法制备C57BL/6J小鼠的MCAO局灶性脑缺血-再灌注模型,缺血时间分别为30min(缺血30min组)和2h(缺血2h组),术中监测并控制平均动脉血压、动脉血气、肛温、脑血流。同时设置假手术组(栓线插入至颈内动脉,不进入大脑中动脉)。术后进行神经功能缺损评分,制备脑组织石蜡切片,分别行HE染色、尼氏染色和原位末端脱氧核苷酸转移酶标记染色。结果缺血2h组小鼠的各项生理参数(包括平均动脉血压、血气指标、体温)与缺血30min组之间差异无统计学意义(均P>0.05)。缺血2h组和30min组小鼠神经功能缺损评分分别为(2.67±0.82)和0分;脑缺血2h导致皮质与纹状体梗死,而脑缺血30min导致局限于纹状体的选择性神经元凋亡。结论脑缺血2h导致皮质、纹状体坏死性损伤,并遗留神经功能缺损体征,而脑缺血30min仅导致纹状体选择性神经元凋亡,未遗留神经功能缺损体征,表明早期再灌注是减轻脑梗死脑损伤的关键。

Background Earlier thrombolytic treatment was associated with reduced mortality and higher rates of independent ambulation at discharge following acute ischemic stroke. Objective To investigate the relationship between reperfusion time and cerebral ischemia iniury, a model of middle cerebral artery occlusion （MCAO） in mice was established, and the effects of different ischemic time on brain injury were observed. Methods The C57BL/6J mice were anesthetized with isoflurane via a facemask and subjected to transient focal brain ischemia （30 min or 2 h） by MCAO with a modification of intraluminal filament technique. Regional cerebral blood flow, rectal temperature, mean arterial blood pressure and arterial blood gas were analyzed before and after MCAO. The sham group was established by only occluding the internal carotid artery. The mice were examined for neurological deficits and then decapitated. Brain injury in the brain coronal sections were respectively assessed by HE staining,cresyl violet staining and terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling staining. Results The 2 h MCAO ischemic stroke mice developed reproducible infarcts involving the cerebral cortex and the striatum, and the neurological deficit score was （2.67±0.82}. At 72 h after the 30 min MCAO treatment, the mice developed selective neu- ronal injury in the striatum, and there was no residual neurological deficit. There were no differences in mean arterial blood pressure, PaO2, PaCO2, pH, rectal temperature, and body weight between the different animal groups （P〉0.05）. Conclusions The 2 h MCAO ischemic stroke mice developed reproducible neurological deficit and infarcts involving the cerebral cortex and the striatum. The 30 min MCAO ischemic stroke mice developed selective neuronal injury in the striatum, and none of them showed residual neurological deficit. These results suggest that early reperfusion after ischemic stroke may be associated with reduced neurological deficit.