Simple Motor System of the Ascidian Larva: Neuronal Complex Comprising Putative Cholinergic and GABAergic/Glycinergic Neurons
Simple Motor System of the Ascidian Larva: Neuronal Complex Comprising Putative Cholinergic and GABAergic/Glycinergic Neurons
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DOI：
10.2108/zsj.27.181
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发表时间：
2010-02-01
影响因子：
0.9
通讯作者：
Tsuda, Motoyuki
中科院分区：
文献类型：
--
作者：
Horie, Takeo;Nakagawa, Masashi;Tsuda, Motoyuki
海鞘幼虫是研究脊索动物功能组织和神经回路的极好模型，因为其非常简单的中枢神经系统（CNS），由大约100个神经元组成。然而，迄今为止，海鞘幼虫中的各种神经元的身份，特别是它们的神经递质表型，没有很好地建立。乙酰胆碱、GABA和甘氨酸是许多动物运动的关键神经递质。我们可视化假定的胆碱能神经元和GABA能/甘氨酸能神经元的海鞘幼虫的免疫荧光染色使用囊泡乙酰胆碱转运蛋白（VACHT）和囊泡GABA/甘氨酸转运蛋白（VGAT）的抗体，分别。在脑泡和内脏神经节中发现了表达胆碱能表型的神经元。内脏神经节内有5对VACHT阳性神经元。这些假定的胆碱能神经元向后延伸其轴突，并在尾部最前部的肌细胞近端形成神经末梢。VGAT阳性神经元位于脑泡、内脏神经节和前神经索。两对不同的VGAT阳性神经元，沿前神经索两侧沿着排列，轴突向前延伸，靠近对侧VACHT阳性神经元的轴突。VGAT阳性神经元的胞体位于这些神经束上。神经元复合体，包括运动神经元与胆碱能表型和一些GABA/甘氨酸能中间神经元，具有结构特征，是兼容的中央模式发生器（CPG）产生的节奏运动的尾巴。海鞘幼虫的简单CPG可能代表了脊椎动物运动系统的祖先状态。
The ascidian larva is an excellent model for studies of the functional organization and neuronal circuits of chordates due to its remarkably simple central nervous system (CNS), comprised of about 100 neurons. To date, however, the identities of the various neurons in the ascidian larva, particularly their neurotransmitter phenotypes, are not well established. Acetylcholine, GABA, and glycine are critical neurotransmitters for locomotion in many animals. We visualized putative cholinergic neurons and GABAergic/glycinergic neurons in the ascidian larva by immunofluorescent staining using antibodies against vesicular acetylcholine transporter (VACHT) and vesicular GABA/glycine transporter ( VGAT), respectively. Neurons expressing a cholinergic phenotype were found in the brain vesicle and the visceral ganglion. Five pairs of VACHT-positive neurons were located in the visceral ganglion. These putative cholinergic neurons extended their axons posteriorly and formed nerve terminals proximal to the most anterior muscle cells in the tail. VGAT-positive neurons were located in the brain vesicle, the visceral ganglion, and the anterior nerve cord. Two distinct pairs of VGAT-positive neurons, bilaterally aligned along the anterior nerve cord, extended axons anteriorly, near to the axons of the contralateral VACHT-positive neurons. Cell bodies of the VGAT-positive neurons lay on these nerve tracts. The neuronal complex, comprising motor neurons with a cholinergic phenotype and some of the GABA/glycinergic interneurons, has structural features that are compatible with a central pattern generator (CPG) producing a rhythmic movement of the tail. The simple CPG of the ascidian larva may represent the ancestral state of the vertebrate motor system.