GABAergic synaptic transmission modulates swimming in the ascidian larva
GABAergic synaptic transmission modulates swimming in the ascidian larva
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DOI：
10.1111/j.1460-9568.2005.04420.x
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发表时间：
2005-11-01
影响因子：
3.4
通讯作者：
Okamura, Y
中科院分区：
文献类型：
--
作者：
Brown, ER;Nishino, A;Okamura, Y
为了研究氨基酸GABA在基础脊索动物运动中的作用，我们研究了游泳的药理学和GABA免疫阳性神经元的形态学在蝌蚪幼虫的海鞘玻璃海鞘和玻璃海鞘。我们通过使用高速视频记录将电信号与尾拍相关联，验证了尾部的电记录反映了游泳过程中交替的肌肉活动。GABA可逆地减少了游泳周期，单尾抽搐，而印防己毒素增加的频率和持续时间的电活动与自发游泳期。GABA的免疫细胞化学显示广泛的标签在整个幼虫的中枢神经系统。两个强烈标记的区域两侧的感觉囊泡连接的弧标记的纤维，从该纤维束尾向延伸到内脏神经节。纤维束延伸腹侧从第三，更内侧区域的后感觉囊泡。内脏神经节内有两排免疫反应阳性胞体，突起延伸至神经索内，神经索内可见静脉曲张。因此，推测GABA能神经元形成一个网络，可以在游泳过程中释放GABA，参与调节自发游泳的时间过程和频率。内脏神经节中的GABA能神经元和运动神经元可以在其细胞体水平和/或通过进入神经索的推测的GABA能纤维相互作用。幼虫的游泳网络似乎具有脊椎动物的脊椎网络的一些特性，而在同一时间可能显示出一种类似于在一些原口动物的外周神经支配。
To examine the role of the amino acid GABA in the locomotion of basal chordates, we investigated the pharmacology of swimming and the morphology of GABA-immunopositive neurones in tadpole larvae of the ascidians Ciona intestinalis and Ciona savignyi. We verified that electrical recording from the tail reflects alternating muscle activity during swimming by correlating electrical signals with tail beats using high-speed video recording. GABA reversibly reduced swimming periods to single tail twitches, while picrotoxin increased the frequency and duration of electrical activity associated with spontaneous swimming periods. Immunocytochemistry for GABA revealed extensive labelling throughout the larval central nervous system. Two strongly labelled regions on either side of the sensory vesicle were connected by an arc of labelled fibres, from which fibre tracts extended caudally into the visceral ganglion. Fibre tracts extended ventrally from a third, more medial region in the posterior sensory vesicle. Two rows of immunoreactive cell bodies in the visceral ganglion extended neurites into the nerve cord, where varicosities were seen. Thus, presumed GABAergic neurones form a network that could release GABA during swimming that is involved in modulating the time course and frequency of periods of spontaneous swimming. GABAergic and motor neurones in the visceral ganglion could interact at the level of their cell bodies and/or through the presumed GABAergic fibres that enter the nerve cord. The larval swimming network appears to possess some of the properties of spinal networks in vertebrates, while at the same time possibly showing a type of peripheral innervation resembling that in some protostomes.