Svensson Erik, Jeffreys Hugo, Li Wen-Chang
School of Psychology and Neuroscience, University of St Andrews, St Andrews, Fife, United Kingdom
School of Psychology and Neuroscience, University of St Andrews, St Andrews, Fife, United Kingdom.
J Neurophysiol. 2017 Jul 1;118(1):121-130. doi: 10.1152/jn.00755.2016. Epub 2017 Mar 22.
Persistent sodium currents () are common in neuronal circuitries and have been implicated in several diseases, such as amyotrophic lateral sclerosis (ALS) and epilepsy. However, the role of in the regulation of specific behaviors is still poorly understood. In this study we have characterized and investigated its role in the swimming and struggling behavior of tadpoles. was identified in three groups of neurons, namely, sensory Rohon-Beard neurons (RB neurons), descending interneurons (dINs), and non-dINs (neurons rhythmically active in swimming). All groups of neurons expressed , but the currents differed in decay time constants, amplitudes, and the membrane potential at which peaked. Low concentrations (1 µM) of the blocker riluzole blocked ~30% and decreased the excitability of the three neuron groups without affecting spike amplitudes or cellular input resistances. Riluzole reduced the number of rebound spikes in dINs and depressed repetitive firing in RB neurons and non-dINs. At the behavior level, riluzole at 1 µM shortened fictive swimming episodes. It also reduced the number of action potentials neurons fired on each struggling cycle. The results show that may play important modulatory roles in motor behaviors. We have characterized persistent sodium currents in three groups of spinal neurons and their role in shaping spiking activity in the tadpole. We then attempted to evaluate the role of persistent sodium currents in regulating tadpole swimming and struggling motor outputs by using low concentrations of the persistent sodium current antagonist riluzole.
持续性钠电流（）在神经回路中很常见，并与多种疾病有关，如肌萎缩侧索硬化症（ALS）和癫痫。然而，其在特定行为调节中的作用仍知之甚少。在本研究中，我们对持续性钠电流进行了表征，并研究了其在非洲爪蟾蝌蚪游泳和挣扎行为中的作用。在三组神经元中鉴定出了持续性钠电流，即感觉性罗霍恩-比尔兹神经元（RB神经元）、下行中间神经元（dINs）和非dINs（在游泳时有节律性活动的神经元）。所有神经元组均表达持续性钠电流，但电流在衰减时间常数、幅度以及电流峰值时的膜电位方面存在差异。低浓度（1 μM）的持续性钠电流阻滞剂利鲁唑可阻断约30%的持续性钠电流，并降低这三组神经元的兴奋性，而不影响动作电位幅度或细胞输入电阻。利鲁唑减少了dINs中的反弹动作电位数量，并抑制了RB神经元和非dINs中的重复放电。在行为水平上，1 μM的利鲁唑缩短了虚拟游泳发作时间。它还减少了每个挣扎周期中神经元发放的动作电位数量。结果表明，持续性钠电流可能在运动行为中发挥重要的调节作用。我们对三组脊髓神经元中的持续性钠电流及其在塑造非洲爪蟾蝌蚪动作电位发放活动中的作用进行了表征。然后，我们试图通过使用低浓度的持续性钠电流拮抗剂利鲁唑来评估持续性钠电流在调节蝌蚪游泳和挣扎运动输出中的作用。
