颈总与颈外插线构建大脑中动脉栓塞大鼠模型脑微循环灌注的比较

Comparison of cerebral microcirculation perfusion in rat models of middle cerebral artery occlusion prepared through common carotid artery insertion and external carotid artery insertion

背景:颈总插线法和颈外插线法制备的大脑中动脉栓塞模型是脑缺血临床前研究常使用的模型,但既往关于2种插线方法在模型制备难易度、缺血性脑损伤中微循环灌注量的差异及其相关机制的对比研究较少。目的:比较颈总动脉和颈外动脉插线制备的大脑中动脉栓塞模型在模型制备难易度以及微循环灌注量的差异。方法:SD雄性大鼠随机分为3组,颈总动脉插线组和颈外动脉插线组分别应用颈总动脉和颈外动脉插线法制备大脑中动脉栓塞模型;假手术组大鼠麻醉后除不结扎血管和插入线栓,其他操作与上述2种方法相同。记录各组大鼠插线时间、插线成功率、模型术后死亡率以及造模成功率。插线后采用激光散斑成像技术观察大鼠缺血90 min内和再灌注90 min内缺血半球脑血流灌注量以及缺血半暗带血管直径的变化;LONGA法和改良神经功能缺损评分法分别评价术后2,24,48,72 h大鼠神经功能缺缺损情况;TTC染色法、干湿质量法以及伊文思蓝染色法分别计算术后72 h大鼠脑梗死率、脑组织含水量以及血脑屏障通透性;ELISA法检测大鼠术后72 h血清内皮素1、降钙素基因肽、环磷酸腺苷、前列腺素E2和一氧化氮表达水平。结果与结论:①与颈外动脉插线组相比,颈总动脉插线组手术操作时间明显缩短(P<0.01),模型成功率更高(P<0.05);且颈总动脉插线组再灌注后缺血半球脑血流灌注量和血管直径均显著小于颈外动脉插线组(P<0.05),血清环磷酸腺苷水平也显著降低(P<0.05);②但颈外动脉插线组和颈总动脉插线组在脑梗死率、脑组织含水量、血脑屏障通透性以及血清内皮素1、降钙素基因肽、前列腺素E2和一氧化氮水平方面差异均无显著性意义(P>0.05);③提示相对于颈外动脉插线法,颈总动脉插线法操作简单、模型成功率高,但再灌注后大脑皮质存在明显的微循环血流灌注障碍;微循环血流的灌注不足可能与血清环磷酸腺苷水平的降低有关。

BACKGROUND:Animal models of middle cerebral artery occlusion(MCAO)prepared by common carotid artery insertion or external carotid artery insertion are commonly used in preclinical studies of cerebral ischemia.However,there are few comparative studies on the difficulty of model preparation and microcirculatory perfusion during ischemic brain injury between the two methods of insertion.OBJECTIVE:To compare the MCAO models prepared by the common carotid artery insertion approach(CCAIA group)and external carotid artery insertion approach(ECAIA group)in the difficulty of model preparation and the differences in microcirculation perfusion.METHODS:Sprague-Dawley rats were randomly divided into sham-operated group,CCAIA group,and ECAIA group.Rats in the sham-operated group were anesthetized but without blood vessel ligation and suture insertion,and the other operations were the same as the above two methods.The modeling time,success rate of insertion,postoperative mortality and success rate of modeling were recorded.After the middle cerebral artery was blocked by suturing,laser speckle imaging technique was used to observe the changes of cerebral blood flow in the ischemic hemisphere and blood vessel diameter in the ischemic penumbra within 90 minutes after ischemia and ischemia-reperfusion.The neurological deficit score was evaluated by Longa’s method and modified neurological severity score at 2,24,48,and 72 hours postoperatively.TTC staining,dry-wet weight method,and Evans blue staining were used to calculate cerebral infarction rate,brain water content,and blood-brain barrier permeability at 72 hours postoperatively.Levels of endothelin-1,calcitonin gene-related peptide,cyclic adenosine monophosphate,prostaglandin E2,and nitric oxide in serum were determined by ELISA.RESULTS AND CONCLUSION:Compared with the ECAIA group,the CCAIA group had shorter operation time(P<0.01)and higher success rate of modeling(P<0.05).The cerebral blood flow,blood vessel diameter,and cyclic adenosine monophosphate level after reperfusion were significantly lower in the CCAIA group than the ECAIA group(P<0.05).However,there was no significant difference between ECAIA and CCAIA groups in cerebral infarction rate,brain water content and blood-brain barrier permeability as well as in the serum levels of endothelin-1,calcitonin gene-related peptide,prostaglandin E2 and nitric oxide content(P>0.05).To conclude,compared with the external carotid artery insertion,the common carotid artery insertion has the advantages of simple operation and high success rate of modeling,but results in an obvious microcirculation perfusion disorder in the cerebral cortex after reperfusion.Insufficient microcirculatory perfusion may be related to the decreased cyclic adenosine monophosphate level in serum.