Parvocells: A novel interneuron type in the pacemaker nucleus of a weakly electric fish
Parvocells: A novel interneuron type in the pacemaker nucleus of a weakly electric fish
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细小细胞：弱电鱼起搏核中的一种新型中间神经元
DOI：
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发表时间：
2000
期刊：
影响因子：
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通讯作者：
H. Zakon
中科院分区：
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作者：
G. Smith;Ying Lu;H. Zakon
裸子形弱电鱼产生电器官放电（EODs），在电定位和通信中起作用。EOD的指令信号由髓质起搏器核产生，其中包含两种特征明确的神经元类型：起搏器细胞和中继细胞。在这项研究中，我们描述了起搏器核中的第三种神经元类型。我们将这些神经元命名为细小细胞，它们比中继细胞和起搏器细胞更小（直径7-15 μm）。parvoccell用一种针对神经元钙结合蛋白（parvalbumin）的抗体标记，而不使用几种胶质特异性抗体标记。Parvocells有一到三个精细的突起，通常终止于中继和起搏器细胞体的外围。细小蛋白阳性末端与SV - 2的免疫反应性共定位，表明细小细胞在中继细胞和起搏器细胞上形成化学突触。细小蛋白阳性神经元通常是γ -氨基丁酸（GABA）能或甘氨酸能，并且细小细胞体细胞的细胞质对甘氨酸抗体有免疫反应。然而，针对甘氨酸受体和格phyrin的抗体在起搏器细胞核中没有标记任何细胞，这表明起搏器细胞核中不含有甘氨酸或GABA(A)受体。电镜显示了细小细胞膜和邻近的终端样结构之间的间隙连接。此外，将神经生物素注射到单个起搏器或中继细胞标记的parvoc细胞以及其他起搏器和中继细胞中，表明parvoc细胞与起搏器核中的其他神经元类型具有染料偶联性。这些发现表明，parvoc细胞在组织化学上不同于继电细胞和起搏器细胞，它们接受来自起搏器细胞和继电细胞的电紧张输入，并使化学突触返回到起搏器细胞和继电细胞。这些神经元在调节EOD中的作用有待进一步研究。[j] .中华神经科杂志，2002,23(3):427 - 439。©2000 Wiley‐Liss, Inc。
Gymnotiform weakly electric fish produce electric organ discharges (EODs) that function in electrolocation and communication. The command signal for the EOD is produced by the medullary pacemaker nucleus, which contains two well‐characterized neuron types: pacemaker cells and relay cells. In this study, we characterized a third neuron type in the pacemaker nucleus. These neurons, which we have named parvocells, were smaller (7–15 μm in diameter) than relay and pacemaker cells. The parvocells were labeled with an antibody against the neuronal calcium‐binding protein, parvalbumin, and were not labeled with several glial‐specific antibodies. Parvocells had one to three fine processes that often terminated at the periphery of relay and pacemaker cell bodies. The parvalbumin‐positive terminals of the parvocells colocalized with immunoreactivity for SV‐2, suggesting that the parvocells form chemical synapses on the relay and pacemaker cells. Parvalbumin‐positive neurons are frequently γ‐aminobutyric acid (GABA)ergic or glycinergic, and the cytoplasm of the parvocell somata was immunoreactive with a glycine antibody. Antibodies against glycine receptors and gephyrin, however, did not label any cells in the pacemaker nucleus, suggesting that the pacemaker nucleus does not contain glycine or GABA(A) receptors. Electron microscopy revealed gap junctions between the membranes of parvocells and adjacent terminal‐like structures. Furthermore, neurobiotin injected into individual pacemaker or relay cells labeled parvocells as well as other pacemaker and relay cells, demonstrating that the parvocells are dye‐coupled to the other neuron types in the pacemaker nucleus. These findings indicate that the parvocells are histochemically distinct from relay and pacemaker cells and that they receive electrotonic inputs from and make chemical synapses back onto pacemaker and relay cells. Further study is needed to investigate the function of these neurons in regulating the EOD. J. Comp. Neurol. 423:427–439, 2000. © 2000 Wiley‐Liss, Inc.