Objective To investigate the differences between focused ultrasound combined with microbubbles and hyperosmolar solutions of mannitol in opening the blood-brain barrier(BBB) in rats. Methods A total of 115 SD rats were randomly divided into focused ultrasound combined with microbubbles group(A,n= 50),mannitol group(B,n = 50) and saline group(C,n= 15). The changes in blood-brain barrier permeability induced by different methods were assessed by contrast-enhanced magnetic resonance imaging(MKI), Exudations of Evans blue and fluorescent-tagged dextrans at two distinct molecular weights were observed with fluorescence microscopy and fluorescencespectrometer. Results The MRI showed local BBB opening from group A , while widespread from group B. The signal intensity enhancements peaked at 0 minute in group A,but 5 minutes in group B. Fluorescence distribution of 10 kDa dextran was more homogeneous and dense than that of 40 kDa dextran The content of Evans blue and fluorescent-tagged dextrans in group A was markedly greater than that of group B(P<0. 01). Conclusions As compared to mannitol infusion, focused ultrasound combined with microbubbles is a metheod of noinvasive , selective and localized opening BBB.%目的 对比聚焦超声联合微泡和高渗性甘露醇2种方法对开放大鼠血脑屏障(BBB)的影响.方法 将115只SD大鼠分为聚焦超声联合微泡组(A组)50只、甘露醇组(B组)50只、假手术组(C组)15只.拟开放BBB后用磁共振增强扫描观察其开放时间特点,用荧光显微镜观察伊文氏蓝和右旋糖酐脑内空间分布差异,荧光分光光度法进行定量分析.结果 A组BBB局部开放,B组弥散广泛开放;A组于0 min核磁信号增强达峰值,B组于5 min信号增强达峰值.10 kDa的右旋糖酐荧光信号较40 kDa的右旋糖酐强且弥散.A组脑组织内伊文氏蓝、10 kDa的右旋糖酐和40 kDa的右旋糖酐的含量均明显大于B组(P＜0.01).结论 聚焦超声联合微泡开放BBB的方法较甘露醇法开放BBB程度更大,开放范围局限,靶向性、可控性更好.
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