低频脉冲磁场对大鼠海马血脑屏障通透性的影响

目的 探讨不同磁场强度脉冲磁辐射对Sprague-Dawley大鼠海马组织血脑屏障（blood brain barrier，BBB）通透性的影响。方法 选取72只成年雄性SD大鼠，完全随机分组法分为假暴露对照组、阳性对照组（肾上腺素，100 μg/kg）和4个不同磁场强度处理组（100、400、800、1 200 mT，每组脉冲次数为30个）。动物辐射后3 h取材，采用HE染色观察海马组织形态学结构；免疫组织化学法检测大鼠海马组织内微血管周围白蛋白渗出；伊文斯蓝（Evans blue，EB）荧光法观察微血管周围EB渗出情况；Western blot法检测脉冲磁场辐射后BBB紧密连接（tight junction，TJ）相关蛋白ZO-1和Occludin的表达变化。结果 与假暴露对照组相比，不同磁场强度脉冲磁辐射组大鼠大脑海马组织结构无明显变化，脑微血管周围未见白蛋白和EB明显渗出，ZO-1蛋白水平在1 200 mT暴露组与假暴露对照组相比显著降低（t=14.26，P<0.05），Occludin蛋白水平及其他磁场强度暴露组的ZO-1水平未见明显变化（P>0.05）。结论 低频脉冲磁场暴露对白蛋白通过BBB的通透性无明显影响，但是ZO-1蛋白水平的降低提示BBB完整性受到损伤。

Effect of low-frequency pulsed magnetic field on blood-brain barrier permeability of rat hippocampus

Objective To investigate the effect of pulsed magnetic radiation on BBB permeability of hippocampus in Sprague-Dawley rats at different exposure intensity. Methods A total of 72 male SD rats were randomly divided into sham exposure group, positive control group and magnetic field treatment groups (100, 400, 800, 1 200 mT, 30 pulses each group). At three hours after exposure, the morphological structure of hippocampus was evaluated by HE staining, the extravasation of albumin around microvessels in rat hippocampus was detected immunohistochemically, the EB extravasation around microvessels was observed with Evans blue (EB) fluorescence method, and the levels of BBB-related protein ZO-1 and Occludin in hippocampus were measured with Western blot assay. Results Compared with the control group, no significant change in the hippocampus morphology structure, the extravasation of albumin and EB around the microvessels were observed after the pulsed magnetic exposures. The protein levels of ZO-1 and Occludin had no changes in the exposed groups(P>0.05) except that ZO-1 was significantly reduced in 1 200 mT exposure group(t=14.26,P<0.05). Conclusions Low-frequency pulsed magnetic field could not affect the permeability of BBB in SD rats but impairs the integrity of BBB at 1 200 mT.