Smith G Troy, Unguez Graciela A, Weber Christopher M
Department of Biology, Program in Neuroscience, and Center for the Integrative Study of Animal Behavior, Indiana University, Bloomington, 47405, USA.
J Neurobiol. 2006 Aug;66(9):1011-31. doi: 10.1002/neu.20283.
The electromotor and electrosensory systems of the weakly electric fish Apteronotus leptorhynchus are model systems for studying mechanisms of high-frequency motor pattern generation and sensory processing. Voltage-dependent ionic currents, including low-threshold potassium currents, influence excitability of neurons in these circuits and thereby regulate motor output and sensory filtering. Although Kv1-like potassium channels are likely to carry low-threshold potassium currents in electromotor and electrosensory neurons, the distribution of Kv1 alpha subunits in A. leptorhynchus is unknown. In this study, we used immunohistochemistry with six different antibodies raised against specific mammalian Kv1 alpha subunits (Kv1.1-Kv1.6) to characterize the distribution of Kv1-like channels in electromotor and electrosensory structures. Each Kv1 antibody labeled a distinct subset of neurons, fibers, and/or dendrites in electromotor and electrosensory nuclei. Kv1-like immunoreactivity in the electrosensory lateral line lobe (ELL) and pacemaker nucleus are particularly relevant in light of previous studies suggesting that potassium currents carried by Kv1 channels regulate neuronal excitability in these regions. Immunoreactivity of pyramidal cells in the ELL with several Kv1 antibodies is consistent with Kv1 channels carrying low-threshold outward currents that regulate spike waveform in these cells (Fernandez et al., J Neurosci 2005;25:363-371). Similarly, Kv1-like immunoreactivity in the pacemaker nucleus is consistent with a role of Kv1 channels in spontaneous high-frequency firing in pacemaker neurons. Robust Kv1-like immunoreactivity in several other structures, including the dorsal torus semicircularis, tuberous electroreceptors, and the electric organ, indicates that Kv1 channels are broadly expressed and are likely to contribute significantly to generating the electric organ discharge and processing electrosensory inputs.
弱电鱼线翎电鳗的电动和电感觉系统是用于研究高频运动模式生成和感觉处理机制的模型系统。电压依赖性离子电流，包括低阈值钾电流，影响这些回路中神经元的兴奋性，从而调节运动输出和感觉滤波。虽然Kv1样钾通道可能在电动和电感觉神经元中携带低阈值钾电流，但线翎电鳗中Kv1α亚基的分布尚不清楚。在本研究中，我们使用针对特定哺乳动物Kv1α亚基（Kv1.1-Kv1.6）产生的六种不同抗体进行免疫组织化学，以表征Kv1样通道在电动和电感觉结构中的分布。每种Kv1抗体标记电动和电感觉核中神经元、纤维和/或树突的不同子集。鉴于先前的研究表明Kv1通道携带的钾电流调节这些区域的神经元兴奋性，电感觉侧线叶（ELL）和起搏器核中的Kv1样免疫反应性尤其相关。ELL中锥体细胞与几种Kv1抗体的免疫反应性与Kv1通道携带调节这些细胞中尖峰波形的低阈值外向电流一致（Fernandez等人，《神经科学杂志》2005年；25:363-371）。同样，起搏器核中的Kv1样免疫反应性与Kv1通道在起搏器神经元自发高频放电中的作用一致。在其他几个结构中，包括背侧半规管、结节状电感受器和电器官，都有强大的Kv1样免疫反应性，这表明Kv1通道广泛表达，可能对产生电器官放电和处理电感觉输入有重大贡献。
