摘要
目的 采用荧光示踪成像和磁示踪成像观察大鼠脑组织间液(ISF)引流路径及物质清除规律.方法 将33只雄性SD大鼠随机分为荧光示踪组(F组,n=18)和磁示踪成像组(MRI组,n=15),再细分为丘脑亚组、海马亚组和尾状核亚组.对F组大鼠注射伊文斯蓝并行心脏灌流,取脑组织制成冰冻切片,观察各亚组示踪剂引流路径;对MRI组大鼠分别于注射钆喷酸葡胺(Gd-DTPA)前、后行MR扫描,对比各亚组脑区ROI信号强度,计算单位信号比值并观察其变化趋势.结果 F组大鼠丘脑、海马、尾状核IFS引流分别存在优势路径,其到达相邻脑区及全脑的时间存在均差异.MRI组注射Gd-DTPA后4 h内丘脑、海马、尾状核示踪剂清除方向性及速率有所不同,表现为丘脑及海马区示踪剂向同侧皮层及侧脑室方向引流、尾状核区示踪剂向皮层和中脑方向扩散,且相邻引流脑区示踪剂信号达峰时间存在差异.结论 光磁双模态成像显示,大鼠丘脑、海马及尾状核ISF优势引流路径及其内小分子物质清除速率均存在差异.
Abstract
Objective To observe the drainage pathways of interstitial fluid(ISF)and substance clearance pattern in rat brain with fluorescence tracing imaging and treacer-based MRI.Methods Thirty-three male SD rats were randomly divided into fluorescence tracing group(F group,n=18)and treacer-based MRI group(MRI group,n=15),then further divided into thalamic,hippocampal and caudate nucleus subgroups,respectively.Evans blue was injected to rats in F group,and cardiac perfusion was performed after injection,then brain tissue was harvested,and frozen sections were made to observe the drainage pathways of IFS in different subgroups.MRI was performed on rats in MRI group before and after injection of gadolinium-diethylenetriamine pentaacetic acid(Gd-DTPA)to observe signal intensity in ROI of brain regions in different subgroups,the signal unit ratio was calculated,and the changing trend was explored.Results ISF in thalamus,hippocampus and caudate nucleus had different dominant drainage pathways,and the time of tracer reached to adjacent brain regions and whole brain in F group were different.In MRI group,within 4 h after injection of Gd-DTPA,there were differences in direction and clearance rate among tracer in thalamus,hippocampus and caudate nucleus,mainly manifesting as the tracer in thalamus and hippocampus drained to the ipsilateral cortex and lateral ventricle,while the tracer in the caudate nucleus diffused to the cortex and midbrain,and there were differences of the peak time of tracer signal among adjacent drainage brain regions.Conclusion Fluorescence and MR dual-mode imaging showed that there were differences in the dominant drainage pathways of IFS and clearance rates of small molecule substances among hypothalamus,hippocampus and caudate nucleus of rats.
维普
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