Effects of uniform extracellular DC electric fields on excitability in rat hippocampal slices in vitro
Effects of uniform extracellular DC electric fields on excitability in rat hippocampal slices in vitro
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DOI：
10.1113/jphysiol.2003.055772
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发表时间：
2004-05-15
影响因子：
5.5
通讯作者：
Jefferys, JGR
中科院分区：
文献类型：
--
作者：
Bikson, M;Inoue, M;Jefferys, JGR
利用电场、细胞内和电压敏感染料记录，研究了均匀稳态（DC）细胞外电场对大鼠海马切片神经元兴奋性的影响。平行于躯体-树突轴施加小电场（< \40\ mV mm(-1)），诱导CA1锥体细胞极化；外加电场与感应极化呈线性关系（0.12 +/- 0.05 mVper mV mm(-1)）。膜极化的峰值振幅和时间常数（15 ~ 70 ms）沿神经元轴向变化，最大极化发生在基底树突和根尖树突尖端。中尖树突呈双相极化；在极性反转的位置有一个随时间的移动。直流电场改变了直流电刺激引起的动作电位阈值，并使动作电位的起始点沿根尖树突移动。大电场可触发神经元放电和癫痫样活动，并诱导神经元兴奋性的长期（bbb10 1 s）变化。垂直于顶-树突轴的电场不会诱导体细胞极化，但会调节正交反应，表明对传入神经有影响。这些结果表明，由于神经元室之间的相互作用、细胞膜的非线性特性以及对传入神经的影响，直流电场可以以一种时间依赖的方式调节神经元的兴奋性，没有明确的阈值。
The effects of uniform steady state (DC) extracellular electric fields on neuronal excitability were characterized in rat hippocampal slices using field, intracellular and voltage-sensitive dye recordings. Small electric fields (< \40\ mV mm(-1)), applied parallel to the somato-dendritic axis, induced polarization of CA1 pyramidal cells; the relationship between applied field and induced polarization was linear (0.12 +/- 0.05 mVper mV mm(-1) average sensitivity at the soma). The peak amplitude and time constant (15-70 ms) of membrane polarization varied along the axis of neurons with the maximal polarization observed at the tips of basal and apical dendrites. The polarization was biphasic in the mid-apical dendrites; there was a time-dependent shift in the polarity reversal site. DC fields altered the thresholds of action potentials evoked by orthodromic stimulation, and shifted their initiation site along the apical dendrites. Large electric fields could trigger neuronal firing and epileptiform activity, and induce long-term (> 1 s) changes in neuronal excitability. Electric fields perpendicular to the apical-dendritic axis did not induce somatic polarization, but did modulate orthodromic responses, indicating an effect on afferents. These results demonstrate that DC fields can modulate neuronal excitability in a time-dependent manner, with no clear threshold, as a result of interactions between neuronal compartments, the non-linear properties of the cell membrane, and effects on afferents.