低频超声开放大鼠血脑屏障的研究

目的探讨1MHz低频超声在不同功率、不同照射时间对大鼠脑细胞及血脑屏障的影响,寻求开放血脑屏障的最佳条件。方法119只Wistar大鼠颅顶右前方开窗后超声照射,采用伊文思蓝(EB)法检测血脑屏障通透性的变化;应用透射电镜观察内皮细胞紧密连接的变化。结果1MHz、12mW照射20s或30s,照射后3hrs,血脑屏障通透性均显著高于对照组(P<0.05),电镜下微血管内皮紧密连接呈开放状态,照射时间30s时,可见部分神经元核膜变形;照射后12hrs,与对照组相比血脑屏障通透性无明显差异(P<0.05),且部分神经元核膜的变形无明显恢复。1MHz、8mW照射的各组与对照组比较血脑屏障通透性无明显差异(P<0.05)。结论1MHz、12mW、照射时间20s可能是可逆性地开放血脑屏障的适宜条件。

The Effect of Low Frequency Ultrasound on Opening Blood-brain Barrier in Rat

Objective To investigate the effect of low frequency ultrasound at 1MHz with different power and illumination time on the blood-brain barrier (BBB)and the cortic neurons of rats to seek the optimum sonication condition to open BBB. Method The ultrasonic illumination was performed through the window on the anterior right part of the cranium in 119 Wistar rats, the BBB permeability was measured by Evans blue assay and the state of the interendothelilal tight junction of capillaries was observed with transmission electron microscope (TEM). Results Compared with the normal control, BBB permeability increased and interendothelilal tight junction of capillaries opened 3 hours after illumination with the power of 12mW for 20s or 30s, but the abnormalities of nucleo-membrane of neurons was seen while the illumination time was 30s. However,there was no obvious difference for BBB permeability and no recovery for the abnormal nucleo-membrane 12hrs after illumination, compared with the control(P<0.05).Moreover,There was no obvious difference for BBB permeability while using 1Mhz at 8mW compared with the control (P<0.05) .Conclusion The frequncy of 1 MHz,the power of 12mW and the illumination time of 20s may be the optimum conditions for opening BBB reversibly.