Ben Yakir-Blumkin M, Loboda Y, Schächter L, Finberg J P M
Department of Molecular Pharmacology, Rappaport Faculty of Medicine, Technion - Israel Institute of Technology, 31096 Haifa, Israel.
Faculty of Electrical Engineering, Technion - Israel Institute of Technology, 32000 Haifa, Israel.
Neuroscience. 2014 Oct 10;278:313-26. doi: 10.1016/j.neuroscience.2014.08.029. Epub 2014 Aug 27.
Low intensity static magnetic fields (SMFs) interact with various biological tissues including the CNS, thereby affecting key biological processes such as gene expression, cell proliferation and differentiation, as well as apoptosis. Previous studies describing the effect of SMFs on apoptotic cell death in several non-neuronal cell lines, emphasize the importance of such a potential modulation in the case of neurodegenerative disorders, where apoptosis constitutes a major route via which neurons degenerate and die. In this study, we examine the effect of SMFs on neuronal survival in primary cortical and hippocampal neurons that constitute a suitable experimental system for modeling the neurodegenerative state in vitro. We show that weak SMF exposure interferes with the apoptotic programing in rat primary cortical and hippocampal neurons, thereby providing protection against etoposide-induced apoptosis in a dose- and time-dependent manner. Primary cortical neurons exposed to SMF (50G) for 7days exhibited a 57.1±6.3% decrease in the percentage of cells undergoing apoptosis induced by etoposide (12μM), accompanied by a marked decrease in the expression of the pro-apoptotic markers: cleaved poly ADP ribose polymerase-1, cleaved caspase-3, active caspase-9 and the phospho-histone H2A variant (Ser139) by 41.0±5.0%, 81.2±5.0%, 72.9±6.4%, 42.75±2.9%, respectively, and by a 57.2±1.0% decrease in the extent of mitochondrial membrane potential collapse. Using the L-type voltage-gated Ca(2+) channel inhibitor nifedipine, which is selective to Ca(2+) influx through Cav1.2, we found that the anti-apoptotic effect of SMFs was mediated by Ca(2+) influx through these channels. Our findings demonstrating altered Ca(2+)-influx in response to thapsigargin stimulation in SMF-exposed cortical neurons, along with enhanced inhibition of KCl-induced Ca(2+)-influx through Cav1.2 channels and enhanced expression of Cav1.2 and Cav1.3 channels, allude to the involvement of voltage- and store-operated Ca(2+) channels in various aspects of the protective effect exerted by SMFs. These findings show the potential susceptibility of the CNS to weak SMF exposure and have implications for the design of novel strategies for the treatment and/or prevention of neurodegenerative diseases.
低强度静磁场(SMFs)与包括中枢神经系统(CNS)在内的各种生物组织相互作用,从而影响关键的生物过程,如基因表达、细胞增殖与分化以及细胞凋亡。先前关于SMFs对几种非神经元细胞系凋亡性细胞死亡影响的研究,强调了在神经退行性疾病中这种潜在调节作用的重要性,在神经退行性疾病中,细胞凋亡是神经元退化和死亡的主要途径。在本研究中,我们研究了SMFs对原代皮质神经元和海马神经元存活的影响,这些神经元构成了一个适合在体外模拟神经退行性状态的实验系统。我们发现,弱SMF暴露会干扰大鼠原代皮质神经元和海马神经元的凋亡程序,从而以剂量和时间依赖性方式提供针对依托泊苷诱导的细胞凋亡的保护作用。暴露于SMF(50G)7天的原代皮质神经元,在依托泊苷(12μM)诱导下发生凋亡的细胞百分比降低了57.1±6.3%,同时促凋亡标志物的表达显著降低:裂解的聚ADP核糖聚合酶-1、裂解的半胱天冬酶-3、活性半胱天冬酶-9和磷酸化组蛋白H2A变体(Ser139)分别降低了41.0±5.0%、81.2±5.0%、72.9±6.4%、42.75±2.9%,线粒体膜电位崩溃程度降低了57.2±1.0%。使用对通过Cav1.2的Ca(²⁺)内流具有选择性的L型电压门控Ca(²⁺)通道抑制剂硝苯地平,我们发现SMFs的抗凋亡作用是由通过这些通道的Ca(²⁺)内流介导 的。我们的研究结果表明,在暴露于SMF的皮质神经元中,对毒胡萝卜素刺激的反应中Ca(²⁺)内流发生了改变,同时对KCl诱导的通过Cav1.2通道的Ca(²⁺)内流的抑制增强,以及Cav1.2和Cav1.3通道的表达增强,这暗示电压门控和储存操纵的Ca(²⁺)通道参与了SMFs发挥的保护作用的各个方面。这些研究结果表明中枢神经系统对弱SMF暴露具有潜在易感性,并对治疗和/或预防神经退行性疾病的新策略设计具有启示意义。