大鼠脑局部星形细胞肿胀模型的CT灌注成像及病理学研究

CT Perfusion and Histopathology Research of Local Cerebral Astrocyte Swelling in Rats

目的 :研究脑局部星形细胞肿胀对局部脑血流的影响。方法 :选取体重在 2 5 0～ 3 0 0g雄性Wistar大鼠 2 1只 ,随机分为三组。将代谢型谷氨酸受体激动剂tACPD(实验组 )或生理盐水 (对照组 ) 2 μl注入右侧尾状核 ,6h及 2 4h后观察动物旋转运动情况 ,并行CT灌注成像检查后处死动物 ,测量左右尾状核干湿重并进行光镜和电镜观察。结果 :实验组动物注射后 6h出现向对侧旋转运动 ,右侧尾状核水含量与对侧及对照组比较差异有显著性意义 (P <0 .0 5 ) ,CT灌注成像均可见脑局部rCBF、rCBV明显下降 ,5例MTT及TTP延长。光镜HE染色及电镜组织学检查可见星形细胞肿胀、小血管受压等改变。注射后 2 4h实验组动物旋转活动、CT灌注成像及病理学检查均恢复正常。结论 :星形细胞肿胀可引起局部脑血流量下降 ,CT灌注成像可以清楚地反映局部脑血流动力学变化。当星形细胞肿胀恢复后 ,局部血流量可以恢复 ,CT灌注指标亦恢复正常。

Objective:To evaluate the influence to cerebral local blood flow after astrocyte swelling.Methods:21 male Wistar rats weighting from 250～300g were randomly individed into 3 groups:the contrast group,6h and 24h group.In experimental group,tACPD (the agonist of mGluRs) was microinjected into the right caudatum.After 6 and 24 hours,the rotation per 5 minutes was calculated.Brain water content was measured by a wet/dry weight technique.Dynamic CT perfusion images were achieved from personal computer aided mapping.Histopathology study was performed by both light and electron microscopy.Results:The injection of tACPD induced brain edema after 6h.The swelling of astrocyte could be shown in both light and electron microscopy examination.In perfusion CT images all the animal showed the decrease of rCBF and rCBV,5 of 7 showed the slowdown of MTT and TTP.In brain water content and rotation there were statistically significant difference between operated and contrast group,P<0.05.In 24h group all the animals recovered to normal.Conclusion:Astrocytic swelling can induce or deteriorate decrease of cerebral blood flow,but when astrocytic swelling recovered,the cerebral blood flow recovered as well.