Institute of Neuroregeneration & Neurorehabilitation, School of Basic Medicine, Qingdao University, Qingdao, China.
Central Laboratory, Department of Neurology, Linyi People's Hospital, Qingdao University, Linyi, Shandong, China.
J Physiol. 2024 Mar;602(6):1175-1197. doi: 10.1113/JP285806. Epub 2024 Mar 3.
Non-invasive transcranial direct-current stimulation (tDCS) is a safe ischaemic stroke therapy. Cathodal bilateral tDCS (BtDCS) is a modified tDCS approach established by us recently. Because selenium (Se) plays a crucial role in cerebral ischaemic injury, we investigated whether cathodal BtDCS conferred neuroprotection via regulating Se-dependent signalling in rat cerebral ischaemia-reperfusion (I/R) injury. We first showed that the levels of Se and its transport protein selenoprotein P (SEPP1) were reduced in the rat cortical penumbra following I/R, whereas cathodal BtDCS prevented the reduction of Se and SEPP1. Interestingly, direct-current stimulation (DCS) increased SEPP1 level in cultured astrocytes subjected to oxygen-glucose deprivation reoxygenation (OGD/R) but had no effect on SEPP1 level in OGD/R-insulted neurons, indicating that DCS may increase Se in ischaemic neurons by enhancing the synthesis and secretion of SEPP1 in astrocytes. We then revealed that DCS reduced the number of injured mitochondria in OGD/R-insulted neurons cocultured with astrocytes. DCS and BtDCS prevented the reduction of the mitochondrial quality-control signalling, vesicle-associated membrane protein 2 (VAMP2) and syntaxin-4 (STX4), in OGD/R-insulted neurons cocultured with astrocytes and the ischaemic brain respectively. Under the same experimental conditions, downregulation of SEPP1 blocked DCS- and BtDCS-induced upregulation of VAMP2 and STX4. Finally, we demonstrated that cathodal BtDCS increased Se to reduce infract volume following I/R. Together, the present study uncovered a molecular mechanism by which cathodal BtDCS confers neuroprotection through increasing SEPP1 in astrocytes and subsequent upregulation of SEPP1/VAMP2/STX4 signalling in ischaemic neurons after rat cerebral I/R injury. KEY POINTS: Cathodal bilateral transcranial direct-current stimulation (BtDCS) prevents the reduction of selenium (Se) and selenoprotein P in the ischaemic penumbra. Se plays a crucial role in cerebral ischaemia injury. Direct-current stimulation reduces mitochondria injury and blocks the reduction of vesicle-associated membrane protein 2 (VAMP2) and syntaxin-4 (STX4) in oxygen-glucose deprivation reoxygenation-insulted neurons following coculturing with astrocytes. Cathodal BtDCS regulates Se/VAMP2/STX4 signalling to confer neuroprotection after ischaemia.
经颅直流电刺激（tDCS）是一种安全的缺血性脑卒中治疗方法。我们最近建立了一种改良的 tDCS 方法，即双侧阴极 tDCS（BtDCS）。由于硒（Se）在脑缺血损伤中起着至关重要的作用，我们研究了阴极 BtDCS 是否通过调节 Se 依赖性信号转导来保护大鼠脑缺血再灌注（I/R）损伤中的神经元。我们首先表明，在 I/R 后，大鼠皮质半影区的 Se 及其转运蛋白硒蛋白 P（SEPP1）水平降低，而阴极 BtDCS 可防止 Se 和 SEPP1 的减少。有趣的是，直流刺激（DCS）增加了培养的星形胶质细胞在氧葡萄糖剥夺复氧（OGD/R）后 SEPP1 的水平，但对 OGD/R 损伤神经元中的 SEPP1 水平没有影响，表明 DCS 可能通过增强星形胶质细胞中 SEPP1 的合成和分泌来增加缺血神经元中的 Se。然后，我们发现 DCS 减少了与星形胶质细胞共培养的 OGD/R 损伤神经元中受损线粒体的数量。DCS 和 BtDCS 分别防止了 OGD/R 损伤的神经元与星形胶质细胞共培养和缺血脑中线粒体质量控制信号、囊泡相关膜蛋白 2（VAMP2）和突触相关蛋白 4（STX4）的减少。在相同的实验条件下，下调 SEPP1 阻断了 DCS 和 BtDCS 诱导的 OGD/R 损伤神经元中 VAMP2 和 STX4 的上调。最后，我们证明了阴极 BtDCS 通过增加星形胶质细胞中的 SEPP1 并随后上调缺血神经元中的 SEPP1/VAMP2/STX4 信号，从而减少 I/R 后的梗死体积。总之，本研究揭示了阴极 BtDCS 通过增加星形胶质细胞中的 SEPP1 并随后上调缺血神经元中的 SEPP1/VAMP2/STX4 信号，从而在大鼠脑 I/R 损伤后发挥神经保护作用的分子机制。关键点：阴极双侧经颅直流电刺激（BtDCS）可防止缺血半影区硒（Se）和硒蛋白 P 的减少。Se 在脑缺血损伤中起着至关重要的作用。直流刺激可减少线粒体损伤，并阻止与星形胶质细胞共培养后的氧葡萄糖剥夺复氧损伤神经元中囊泡相关膜蛋白 2（VAMP2）和突触相关蛋白 4（STX4）的减少。阴极 BtDCS 通过调节 Se/VAMP2/STX4 信号来发挥神经保护作用，以防止缺血后发生。
