Objectives: Restoration of blood circulation within "time window" is the principal treating goal for treating acute ischemic stroke. Previous studies revealed that delayed recanalization might cause serious ischemia/reperfusion injury. However, plenty of evidences showed delayed recanalization improved neurological outcomes in acute ischemic stroke. This study aims to explore the role of delayed recanalization on blood-brain barrier (BBB) in the penumbra (surrounding ischemic core) and neurological outcomes after middle cerebral artery occlusion (MCAO).
Methods: Recanalization was performed on the 3rd day after MCAO. BBB disruption was tested by Western blotting, Evans blue dye, and immunofluorescence staining. Infarct volume and neurological outcomes were evaluated on the 7th day after MCAO. The expression of fibroblast growth factor 21 (FGF21), fibroblast growth factor receptor 1 (FGFR1), phosphatidylinositol-3-kinase (PI3K), and serine/threonine kinase (Akt) in the penumbra were observed by immunofluorescence staining and/or Western blotting.
Results: The extraversion of Evans blue, IgG, and albumin increased surrounding ischemic core after MCAO, but significantly decreased after recanalization. The expression of Claudin-5, Occludin, and zona occludens 1 (ZO-1) decreased surrounding ischemic core after MCAO, but significantly increased after recanalization. Infarct volume reduced and neurological outcomes improved following recanalization (on the 7th day after MCAO). The expressions of Claudin-5, Occludin, and ZO-1 decreased surrounding ischemic core following MCAO, which were up-regulated corresponding to the increases of FGF21, p-FGFR1, PI3K, and p-Akt after recanalization. Intra-cerebroventricular injection of FGFR1 inhibitor SU5402 down-regulated the expression of PI3K, p-Akt, Occludin, Claudin-5, and ZO-1 in the penumbra, which weakened the beneficial effects of recanalization on neurological outcomes after MCAO.
Conclusions: Delayed recanalization on the 3rd day after MCAO increases endogenous FGF21 in the penumbra and activates FGFR1/PI3K/Akt pathway, which attenuates BBB disruption in the penumbra and improves neurobehavior in MCAO rats.
目的: 在“时间窗”内恢复闭塞大动脉的血流是急性缺血性卒中的主要治疗策略。既往研究表明“时间窗”后的血管再通治疗可导致严重的缺血/再灌注损伤。然而，大量临床证据提示“时间窗”后的血管再通治疗仍可改善急性缺血性卒中的神经功能转归。本研究探讨大脑中动脉闭塞(middle cerebral artery occlusion，MCAO)后血管再通治疗对缺血半暗带血脑屏障(blood-brain barrier，BBB)的影响及分子机制。方法: MCAO后第3天行血管再通治疗术，通过蛋白质印迹法、伊文思蓝染色和免疫荧光染色检测BBB损伤。MCAO后第7天评估梗死体积和神经功能转归。采用免疫荧光染色和/或蛋白质印迹法观察缺血半暗带中成纤维细胞生长因子21(fibroblast growth factor 21，FGF21)、成纤维细胞生长因子受体1(fibroblast growth factor receptor 1，FGFR1)、磷脂酰肌醇3激酶(phosphatidylinositol-3-kinase，PI3K)和丝氨酸/苏氨酸激酶(serine/threonine kinase，Akt)的表达及其对BBB的影响。结果: MCAO后缺血半暗带伊文思蓝、IgG和白蛋白的外渗增加，但在血管再通后显著下降；Claudin-5、Occludin和紧密连接蛋白ZO-1表达降低，但在血管再通后表达升高，与FGF21、p-FGFR1、PI3K和p-Akt蛋白升高一致。MCAO后第7天，梗死体积缩小，神经功能改善。侧脑室注射FGFR1抑制剂SU5402可下调缺血半暗带区PI3K、p-Akt、Occludin、Claudin-5和ZO-1的表达，减弱血管再通治疗对MCAO大鼠神经功能转归的有利作用。结论: MCAO后第3天的血管再通治疗增加缺血半暗带内源性FGF21的表达，并可通过激活FGFR1/PI3K/Akt通路减轻缺血半暗带BBB损伤，改善MCAO大鼠的神经功能。.
目的: 在“时间窗”内恢复闭塞大动脉的血流是急性缺血性卒中的主要治疗策略。既往研究表明“时间窗”后的血管再通治疗可导致严重的缺血/再灌注损伤。然而，大量临床证据提示“时间窗”后的血管再通治疗仍可改善急性缺血性卒中的神经功能转归。本研究探讨大脑中动脉闭塞(middle cerebral artery occlusion，MCAO)后血管再通治疗对缺血半暗带血脑屏障(blood-brain barrier，BBB)的影响及分子机制。
方法: MCAO后第3天行血管再通治疗术，通过蛋白质印迹法、伊文思蓝染色和免疫荧光染色检测BBB损伤。MCAO后第7天评估梗死体积和神经功能转归。采用免疫荧光染色和/或蛋白质印迹法观察缺血半暗带中成纤维细胞生长因子21(fibroblast growth factor 21，FGF21)、成纤维细胞生长因子受体1(fibroblast growth factor receptor 1，FGFR1)、磷脂酰肌醇3激酶(phosphatidylinositol-3-kinase，PI3K)和丝氨酸/苏氨酸激酶(serine/threonine kinase，Akt)的表达及其对BBB的影响。
结果: MCAO后缺血半暗带伊文思蓝、IgG和白蛋白的外渗增加，但在血管再通后显著下降；Claudin-5、Occludin和紧密连接蛋白ZO-1表达降低，但在血管再通后表达升高，与FGF21、p-FGFR1、PI3K和p-Akt蛋白升高一致。MCAO后第7天，梗死体积缩小，神经功能改善。侧脑室注射FGFR1抑制剂SU5402可下调缺血半暗带区PI3K、p-Akt、Occludin、Claudin-5和ZO-1的表达，减弱血管再通治疗对MCAO大鼠神经功能转归的有利作用。
结论: MCAO后第3天的血管再通治疗增加缺血半暗带内源性FGF21的表达，并可通过激活FGFR1/PI3K/Akt通路减轻缺血半暗带BBB损伤，改善MCAO大鼠的神经功能。
Keywords: blood-brain barrier disruption; delayed recanalization; fibroblast growth factor 21; ischemia/reperfusion injury; middle cerebral artery occlusion.