<b>Neuron-like cells in the chick spinal accessory lobe express neuronal-type voltage-gated sodium </b><b>channels </b>

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Author(s)

    • MATSUSHITA Yumi
    • Laboratory of Veterinary Physiology, Faculty of Agriculture, Tottori University
    • KITAMURA Naoki
    • Laboratory of Veterinary Physiology, Faculty of Agriculture, Tottori University
    • HIGUCHI Masashi
    • Laboratory of Veterinary Biochemistry, Faculty of Agriculture, Tottori University
    • Z HOSAKA Yoshinao
    • Laboratory of Veterinary Anatomy, Faculty of Agriculture, Tottori University
    • SHIBUYA Izumi
    • Laboratory of Veterinary Physiology, Faculty of Agriculture, Tottori University

Abstract

<p>Ten pairs of protrusions, called accessory lobes (ALs), exist at the lateral sides of the avian lumbosacral spinal cord. Histological evidence indicates that neuron-like cells gather in the ALs, and behavioral evidence suggests that the ALs act as a sensory organ of equilibrium during bipedal walking. Recently, using an electrophysiological method, we reported that cells showing Na<sup>+</sup> currents and action potentials exist among cells that were dissociated from the ALs. However, it was unclear which isoforms of the voltage-gated sodium channel (VGSC) are expressed in the ALs and whether cells having neuronal morphology in the ALs express VGSCs. To elucidate these points, RT-PCR and immunohistochemical experiments were performed. In RT-PCR analysis, PCR products for Na<sub>v</sub> 1.1–1.7 were detected in the ALs. The signal intensities of the Na<sub>v</sub> 1.1 and 1.6 isoforms were stronger than those of the other isoforms. We confirmed that an antibody raised against an epitope peptide of the rat VGSC had cross-reactivity to chick tissues by Western blotting, and we performed immunofluorescence staining using the antibody. The AL contained cells having neuron-like morphology and VGSC-like immunoreactivity at their cytoplasm and/or cell membranes. Filament-like structures showing GFAP-like immunoreactivity infilled intercellular spaces. The VGSC- and GFAP-like immunoreactivities did not overlap. These results indicate that the neuronal isoforms of the VGSC are mainly expressed in the AL and that the neuron-like cells in the ALs express VGSCs. Our findings indicate that AL neurons generate action potentials and send sensory information to the motor systems on the contralateral side of the spinal segment.</p>

Journal

  • Biomedical Research

    Biomedical Research 39(4), 189-196, 2018

    Biomedical Research Press

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