The Influence of Static Magnetic Fields on Brain tissue

流行病学研究表明，暴露在高压交流输电线路系统产生的电磁场中可能会对生物系统产生不利影响。虽然大多数关于磁场效应的研究都集中在交流场上，但静磁场也存在于人类环境中。它们被用于工业和医学，许多报告描述了静磁场(SMF)对生物系统的影响。高压直流传输线中的电流与交流传输线相反，不会迅速变化，也不能在导体中感应电流。因此，它们与生物系统的可能相互作用将不同于交流电场。本研究的目的是评估SMF对小鼠海马片诱发电位的影响。自从对人类受试者的术前评估表明SMF可能会在海马区引发癫痫活动后，海马区就被选择了。此外，基本的海马电生理学和形态是众所周知的，细胞和纤维的排列创造了一个潜在的易于磁场作用的环境。我们的初步结果表明，SMF(2-3mT强度)调节从小鼠海马片记录的群体峰的大小。在SMF作用期间观察到的切片电位的最初下降之后是恢复/放大阶段，该阶段在终止SMF作用后开始。在这一阶段，种群峰值超过了施加磁场之前观察到的幅度。NMDA受体拮抗剂不影响磁场的作用模式。细胞内Cat+通道的阻断剂丹曲林抑制该电位的上升期，提示细胞内钙通道参与了SMF的作用机制。SMF效应仅限于顺向驱动电位。我们的假设是，SMF调节钙离子在细胞膜中的移动。暴露在SMF中的切片对放射性钙的累积将被测定。SMF对参与突触机制的蛋白激酶C(PKC)活性的影响将被确定。研究计划比较对照和SMF处理的切片中谷氨酸(一种被测试的神经递质)的释放和摄取。通过细胞内记录，SMF对单个神经元活动的影响是有计划的。将研究暴露于SMF的脑片的细胞兴奋性、突触效率和动作电位。并对未来的研究方向进行了展望。

Epidemiological studies have suggested that exposure to electromagnetic fields generated by high-voltage, alternating current (AC) transmission line systems may have adverse effects on the biological systems. Although most of the work on magnetic field effects focused on AC fields, static magnetic fields (SMF) are also present in human environment. They are used in the industry and medicine and number of reports describes the effects of static magnetic fields (SMF) on biological systems. The current in high-voltage DC transmission lines, in opposite to AC lines, do not vary rapidly and is unable to induce current in conducting objects. Therefore, their possible interaction with biological systems would be different than AC fields. The objective of proposed research is to evaluate the influence of SMF on the evoked potentials recorded from mouse hippocampal slices. Hippocampus has been selected since presurgical evaluation of human subjects demonstrated that SMF may trigger epileptic activity in the hippocampus. Additionally, basic hippocampal electrophysiology and morphology is well known and arrangement of cells and fibers creates an environment potentially prone to magnetic fields action. Our preliminary results show that SMF (2-3 mT of intensity) modulate the magnitude of the population spike recorded from mouse hippocampal slices. The initial decline in the potential observed during exposure of the slices to SMF was followed by a recovery/amplification phase, which began after terminating the SMF action. During that phase the population spike exceeded the amplitude observed before application of the magnetic fields. The pattern of magnetic fields influence was not affected by antagonists of NMDA receptor. The inhibition of the rising phase of the potential by dantrolene, an inhibitor of intracellular Cat+ channels suggests that intracellular calcium channels participate in the mechanism of SMF action. The SMF effects were limited to orthodromically driven potentials. Our hypothesis is that SMF modulate the movement of Ca2+ ions through cellular membranes. The accumulation of radioactive Ca2+ by slices exposed to SMF will be determined. The influence of SMF on the activity of protein kinase C (PKC) which participates in synaptic mechanisms will be determined. Studies are planned to compare release and uptake of glutamate (a neurotransmitter in a tested pathway) in control and SMF-treated slices. The influence of SMF on individual neurons activity using intracellular recordings are planned. The cell excitability, synaptic efficiency and action potentials recorded from the slices exposed to SMF will be studied. The directions of alternative and future research are delineated.