Cerebrovascular Diseases Research Institute, Xuanwu Hospital of Capital Medical University, 45 Changchun Street, Beijing, 100053, China.
J Neuroimmune Pharmacol. 2015 Mar;10(1):153-61. doi: 10.1007/s11481-014-9571-z. Epub 2015 Jan 28.
Local infusion of low dose erythropoietin (EPO) alleviates cerebral ischemia and reperfusion (I/R) injury in rats; however, the underlying molecular mechanisms are still unclear. The present study investigated the effect of low dose EPO treatment on I/R-induced endoplasmic reticulum (ER) stress in brain tissue and isolated microvessels in rodents. Sprague-Dawley rats were subjected to 2 h ischemia/24 h reperfusion by middle cerebral artery (MCA) occlusion, then administered fluorescein isothiocyanate-labeled EPO via MCA infusion (MCAI) or subcutaneous injection (SI) to compare the efficiency of two modes of delivery. Neurobehavioral deficits and infarct volume, and the expression of ER stress-associated proteins and apoptosis in brain tissue or isolated microvessels, as well as the transcriptional activity of 16 factors involved in ER stress and the unfolded protein response in brain tissue was asscessed. A higher EPO level in cerebrospinal fluid and brain tissue was observed in rats treated with EPO by MCAI (800 IU/kg) than by SI (5000 IU/kg). Moreover, neurobehavioral deficits and infarct volume were reduced in rats treated with EPO by MCAI and salubrinal. EPO suppressed the expression of ER stress signals glucose-regulated protein 78, activating transcription factor (ATF) 6α, and CCAAT enhancer-binding protein homologous protein (CHOP), as well as that of the pro-apoptotic protein caspase-3 in brain microvessels, and decreased the number of CHOP-positive, apoptotic neurons. EPO treatment also reduced the transcriptional activities of CHOP, forkhead box protein O1, and ATF4. These results provide evidence that low dose EPO treatment via MCAI provides neuroprotection following acute ischemic stroke by inhibiting the ER stress response.
局部输注小剂量促红细胞生成素（EPO）可减轻大鼠脑缺血再灌注（I/R）损伤；然而，其潜在的分子机制尚不清楚。本研究探讨了小剂量 EPO 治疗对脑组织和分离的微血管中 I/R 诱导的内质网（ER）应激的影响。通过大脑中动脉（MCA）闭塞使 Sprague-Dawley 大鼠发生 2 h 缺血/24 h 再灌注，然后通过 MCA 输注（MCAI）或皮下注射（SI）给予荧光素异硫氰酸酯标记的 EPO，以比较两种给药方式的效率。评估了脑损伤或分离的微血管中与 ER 应激相关的蛋白和细胞凋亡的表达、神经行为学缺陷和梗死体积，以及脑组织中涉及 ER 应激和未折叠蛋白反应的 16 个因子的转录活性。MCAI（800IU/kg）治疗的大鼠脑脊液和脑组织中 EPO 水平高于 SI（5000IU/kg）治疗的大鼠。此外，MCAI 和 salubrinal 治疗的 EPO 可减轻大鼠的神经行为学缺陷和梗死体积。EPO 抑制了 ER 应激信号葡萄糖调节蛋白 78、激活转录因子（ATF）6α和 CCAAT 增强子结合蛋白同源蛋白（CHOP），以及脑微血管中促凋亡蛋白 caspase-3 的表达，并减少了 CHOP 阳性、凋亡神经元的数量。EPO 处理还降低了 CHOP、叉头框蛋白 O1 和 ATF4 的转录活性。这些结果为通过 MCAI 给予小剂量 EPO 治疗通过抑制 ER 应激反应为急性缺血性脑卒中提供神经保护提供了证据。
