促红细胞生成素对脑缺血再灌注大鼠血脑屏障紧密连接的影响。
Effects of erythropoietin on blood-brain barrier tight junctions in ischemia-reperfusion rats.
机构信息
Department of Neurobiology, College of Basic Medicine, China Medical University, Shenyang, Liaoning province, China, 110001.
出版信息
J Mol Neurosci. 2013 Feb;49(2):369-79. doi: 10.1007/s12031-012-9883-5. Epub 2012 Sep 22.
Administration of recombinant human erythropoietin (rhEPO) protects neurons from injury after brain ischemia-reperfusion (I/R), which is in part mediated by ameliorating the blood-brain barrier (BBB) leakage. But the mechanism of rhEPO's protective effects on BBB remains unclear. This study aims to investigate the effects of rhEPO on BBB integrity and the expressions of tight junctions (TJs) associated proteins of zonula occluden-1 (ZO-1), occludin, and claudin-5 in cerebral I/R rats. These rats underwent 2 h of ischemia and then were reperfused for up to 3 and 72 h. Animals were randomly divided into five groups: sham-operated group, I/R 3 h and I/R 72 h group (2 ml saline was injected intraperitoneally just before the onset of ischemia), rhEPO +I/R 3 h, and rhEPO +I/R 72 h group (5,000 U/kg rhEPO diluted in 2 ml saline solution was injected intraperitoneally just before the onset of ischemia). We verified that rhEPO could decrease the BBB leakage induced by I/R injury detected by Evans blue extravasation. 2, 3, 5-Triphenyltetrazolium chloride staining results showed that rhEPO decreased infarct volume after cerebral I/R. TJ integrity was partly restored by rhEPO observed by transmission electron microscopy. The mRNA and protein expression levels of ZO-1, occludin, and claudin-5 were significantly increased compared with I/R groups at the same reperfusion time point by reverse transcriptase-polymerase chain reaction and Western blot assays. The treatment of rhEPO induced the redistribution of ZO-1, occludin, and claudin-5 in cerebral microvessels observed by immunohistochemical staining. Compared with I/R groups, the mRNA level of tumor necrosis factor-alpha (TNF-α) in cerebral microvessels decreased markedly after rhEPO treatment, accompanied with reduced TNF-α protein level and nuclear factor-кB (NF-кB) p65 activation detected by enzyme-linked immunosorbent assay. These results suggested that the protective mechanism of rhEPO on BBB after cerebral I/R injury was associated with the upregulation of TJ-associated proteins. The downregulated TNF-α levels and NF-кB activation induced by rhEPO might be involved in this process.
重组人促红细胞生成素(rhEPO)的给药可减轻血脑屏障(BBB)的渗漏,从而对脑缺血再灌注(I/R)后的神经元损伤起到保护作用。然而,rhEPO 对 BBB 保护作用的机制尚不清楚。本研究旨在探讨 rhEPO 对脑 I/R 大鼠 BBB 完整性和紧密连接(TJ)相关蛋白闭锁蛋白-1(ZO-1)、occludin 和 Claudin-5 表达的影响。这些大鼠经历 2 小时的缺血,然后再灌注长达 3 和 72 小时。动物随机分为五组:假手术组、I/R 3 小时和 I/R 72 小时组(缺血前 2 毫升生理盐水腹腔注射)、rhEPO+I/R 3 小时和 rhEPO+I/R 72 小时组(缺血前 2 毫升生理盐水稀释的 5000 U/kg rhEPO 腹腔注射)。我们验证了 rhEPO 可以降低由 I/R 损伤引起的 BBB 渗漏,通过 Evans 蓝渗出检测。2,3,5-三苯基四唑氯化物染色结果表明,rhEPO 降低了脑 I/R 后的梗死体积。透射电镜观察到 TJ 完整性部分恢复。逆转录-聚合酶链反应和 Western blot 检测结果显示,与同一再灌注时间点的 I/R 组相比,rhEPO 可显著增加 ZO-1、occludin 和 Claudin-5 的 mRNA 和蛋白表达水平。免疫组织化学染色观察到 rhEPO 诱导脑微血管中 ZO-1、occludin 和 Claudin-5 的重新分布。与 I/R 组相比,rhEPO 处理后脑微血管中肿瘤坏死因子-α(TNF-α)的 mRNA 水平显著降低,酶联免疫吸附试验检测到 TNF-α 蛋白水平和核因子-кB(NF-кB)p65 激活降低。这些结果表明,rhEPO 对脑 I/R 损伤后 BBB 的保护机制与 TJ 相关蛋白的上调有关。rhEPO 诱导的 TNF-α 水平降低和 NF-кB 激活可能参与了这一过程。