The disruption of the blood–brain barrier (BBB) plays a critical event in the pathogenesis of ischemia stroke. TGR5 is recognized as a potential target for the treatment for neurologic disorders. This study investigated the roles of TGR5 activation in attenuating BBB damage and underlying mechanisms after middle cerebral artery occlusion (MCAO). Sprague-Dawley rats were subjected to model of MCAO and TGR5 agonist, INT777, was administered intranasally. Small interfering RNA (siRNA) for TGR5 and BRCA1 were administered through intracerebroventricular injection 48 h before MCAO. Infarct volumes, brain water content, BBB permeability, neurological scores, Western blot, immunofluorescence staining and co- immunoprecipitation were evaluated. Endogenous TGR5 and BRCA1 were upregulated in the injured hemisphere after MCAO and TGR5 expressed in endothelial cells. Treatment with INT777 alleviated brain water content and BBB permeability, reduced infarction volume and improved neurological scores at 24 h and 72 h after ischemia. INT777 administration increased BRCA1 and Sirt1 expression, as well as upregulated expressions of tight junction proteins. Ischemic damage induced interaction of TGR5 with BRCA1. TGR5 siRNA and BRCA1 siRNA significantly inhibited expressions of BRCA1 and Sirt1, aggravated BBB permeability and exacerbated stroke outcomes after MCAO. The protective effects of INT777 at 24 h after MCAO were also abolished by TGR5 siRNA or BRCA1 siRNA. Our findings demonstrate that activating TGR5 could reduce BBB breakdown and improve neurological functions through BRCA1/Sirt1 signaling pathway after MCAO. TGR5 may serve as a potential new candidate to relieve brain injury after MCAO.

中文翻译：

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TGR5的激活可通过大鼠大脑中动脉闭塞后的BRCA1 / Sirt1途径保护血脑屏障

血脑屏障（BBB）的破坏在缺血性中风的发病机制中起着关键作用。TGR5被认为是治疗神经系统疾病的潜在靶标。这项研究调查了TGR5激活在减轻大脑中动脉闭塞（MCAO）后BBB损伤和潜在机制中的作用。对Sprague-Dawley大鼠进行MCAO模型治疗，并经鼻内施用TGR5激动剂INT777。TGF5和BRCA1的小干扰RNA（siRNA）在MCAO前48小时通过脑室内注射给予。评估梗死体积，脑含水量，血脑屏障通透性，神经学评分，蛋白质印迹，免疫荧光染色和免疫共沉淀。MCAO和TGR5在内皮细胞中表达后，内源性TGR5和BRCA1在受伤的半球中被上调。INT777的治疗减轻了缺血后24小时和72小时的脑水含量和BBB通透性，减少了梗塞体积并改善了神经学评分。INT777管理增加了BRCA1和Sirt1的表达，以及紧密连接蛋白的表达上调。缺血性损伤诱导TGR5与BRCA1相互作用。TGR5 siRNA和BRCA1 siRNA显着抑制了MCAO后BRCA1和Sirt1的表达，加剧了BBB的通透性，并加重了卒中预后。TGR5 siRNA或BRCA1 siRNA也消除了MCAO后24小时INT777的保护作用。我们的研究结果表明，激活TGR5可以减少MCAO后通过BRCA1 / Sirt1信号通路引起的BBB分解并改善神经功能。TGR5可能是缓解MCAO后脑损伤的潜在新候选者。