Development of the technique for recording ionic currents at motor nerve terminals

运动神经末梢离子电流记录技术的开发

• 批准号: 62870004
• 负责人: KUNO Motoi
• 金额: $ 5.76万
• 依托单位: Kyoto University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Developmental Scientific Research
• 财政年份: 1987
• 资助国家: 日本
• 起止时间: 1987 至 1988
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-62870004/
• 关键词: Neuromuscular junctions; Nerve terminals; Sprouting; Ionic channels; Plasticity; CGRP

Nerve terminals are the site of growth or the formation of sprouts as well as the site of transmitter release. Therefore, nerve terminals are expected to have different ionic mechanisms from those for nerve fibers. However, the analysis of ionic mechanisms is difficult at nerve terminals because of their minute structure. In the present study, attempts were made to record local ionic currents from motor nerve terminals by the technique of loose-patch clamp and to expand the nerve terminal by the formation of terminal sprouts. During the course of this study, it was accidentally found that the formation of sprouts in motor nerve terminals is inhibited by calcitonin gene-related peptide (CGRP). Consequently, the study was further extended to analyze the mechanisms opf plastic changes at neuromuscular junctions. The experiments were made in abult rats. Under the visual control with Nomarski's optics, a microelectrode was firmyl placed on the surface of a motor nerve terminal in the extens … More or digitorum muscle dissected from the hind limb. In response to nerve stimulation, the motor nerve terminal showed a tetrodotoxin-sensitive inward sodium current followed by an outward potassium current. When the potassium current was blocked, the umderlying inward calcium current was also unmasked. When sprouts were formed in motor nerve terminals by chronic conduction block of the sciatic nerve, a similar inward sodium current was also detected in the terminal sprouts. The conduction velocity at terminal sprouts was about 0.2 m/sec. When CGRP was daily applied to the snimal curing the 10-day-period of conduction block of the sciatic nerve, the formation of terminal sprouts expected in the paralyzed hind limb muscle was almost completely inhibited. To our knowledge, CGRP is the first substance which is identified to inhibit the formation of terminal sprouts. In the past, an increase of transmitter release in the paralyzed muscle has been assumed to be due to the formation of terminal sprouts. However,CGRP did not prevent increased transnitter release in the paralyzed muscle, while the formation of terminal sprouts was blocked in the muscle. It is concluded that an increase in transmitter release and the formation of terminal sprouts observed in chronically paralyzed muscle are two independent processes. Less

神经末梢是生长或形成芽的部位以及递质释放的部位。因此，预期神经末梢具有与神经纤维不同的离子机制。然而，由于神经末梢的微小结构，离子机制的分析是困难的。本研究尝试用松式膜片钳技术记录运动神经末梢的局部离子电流，并通过形成末梢芽来扩张神经末梢。在本研究过程中，意外发现运动神经末梢芽的形成受到降钙素基因相关肽（CGRP）的抑制。因此，本研究进一步扩展到分析神经肌肉接头可塑性变化的机制。实验在成年大鼠中进行。在Nomarski光学系统的视觉控制下，将微电极牢固地放置在伸肌运动神经末梢的表面， ...更多信息 或从后肢上切下的趾肌在神经刺激的反应，运动神经末梢表现出河豚毒素敏感的内向钠电流，然后是外向钾电流。当钾电流被阻断时，大量内向钙电流也被暴露。当慢性坐骨神经传导阻滞在运动神经末梢形成芽时，在终末芽中也检测到类似的内向钠电流。末端芽的传导速度约为0.2米/秒。当CGRP每天应用于治疗坐骨神经传导阻滞10天的snacks时，在瘫痪的后肢肌肉中预期的终末芽的形成几乎完全被抑制。据我们所知，CGRP是第一种被鉴定为抑制终末芽形成的物质。过去，麻痹肌肉中递质释放的增加被认为是由于终末芽的形成。然而，CGRP并不能阻止麻痹肌肉中转氮素释放的增加，而肌肉中终末芽的形成也被阻止。它的结论是，在长期麻痹的肌肉中观察到的递质释放的增加和终端芽的形成是两个独立的过程。少

项目成果

Tsujimoto, T.; Kuno, M.: "Impulse propagation in nerve terminal sprouts induced at the rat neuromuscular junction" Neuroscience Research. Suppl. 5. 53 (1987)

辻本，T.；

Kuno,M.;Tsujimoto,T.;Umemiya,M.: Neuroscience Research. 9. (1989)

Kuno，M.；Tsujimoto，T.；Umemiya，M.：神经科学研究。

Kuno,M.;Tsujimoto,T.: "Terminal sprouting and functional plasticity at neuromuscular junctions.In:Brain Signal Transduction and Memory" Academic Press, (1989)

Kuno,M.；Tsujimoto,T.：“神经肌肉接头处的终端发芽和功能可塑性。In：脑信号转导和记忆”学术出版社，（1989）

Tsujimoto,T.;Kuno,M.: Neuroscience Research. suppl.5. S53 (1987)

Tsujimoto，T.；Kuno，M.：神经科学研究。

辻本哲宏,久野宗: 日本生理学雑誌. 50. 80 (1988)

Tetsuhiro Tsujimoto，So Kuno：日本生理学杂志 50. 80 (1988)。