Remodeling of membrane properties and dendritic architecture accompanies the postembryonic conversion of a slow into a fast motoneuron
Remodeling of membrane properties and dendritic architecture accompanies the postembryonic conversion of a slow into a fast motoneuron
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DOI：
10.1523/jneurosci.20-18-06950.2000
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发表时间：
2000-09-15
影响因子：
5.3
通讯作者：
Levine, RB
中科院分区：
文献类型：
--
作者：
Duch, C;Levine, RB
行为的胚胎后获得需要神经元回路的改变，这最终必须被理解为神经元结构、膜特性和突触连接的特定变化。本研究通过描述已确定的运动神经元 MN5 的兴奋性和树突形态的胚胎后重塑来实现这一目标，MN5 在天蛾 (L.) 的变态过程中从参与幼虫爬行行为的缓慢运动神经元转变为快速成虫飞行运动神经元。五倍低的输入电阻、更高的放电阈值和电压激活的 K+ 电流的增加导致成年 MN5 的兴奋性降低，这是其新获得行为角色的先决条件。此外，成年 MN5 显示出更大的 Ca2+ 电流。 MN5 的树突经历了广泛的重塑。幼虫树突在蛹早期急剧退化，随后新树突快速生长。兴奋性的关键变化发生在成年树突形成的开始期间。当树突重塑最剧烈时，幼虫Ca2+电流不存在，但在后期发育过程中显着增加。 Ca2+ 和 K+ 电流的变化遵循不同的时间进程，使得当新的树突分支停止时，在蛹阶段短暂地出现 Ca2+ 尖峰。 K+ 电流减少后，成年 MN5 可以产生延长的 Ca2+ 尖峰。我们认为 Ca2+ 和 K+ 电流的改变对于 MN5 参与飞行行为是必要的，并且 Ca2+ 尖峰的瞬时产生可能会影响胚胎后树突重塑。
The postembryonic acquisition of behavior requires alterations in neuronal circuitry, which ultimately must be understood as specific changes in neuronal structure, membrane properties, and synaptic connectivity. This study addresses this goal by describing the postembryonic remodeling of the excitability and dendritic morphology of an identified motoneuron, MN5, which during the metamorphosis of Manduca sexta (L.) changes from a slow motoneuron that is involved in larval-crawling behavior into a fast adult flight motoneuron. A fivefold lower input resistance, a higher firing threshold, and an increase in voltage-activated K+ current contribute to a lower excitability of the adult MN5, which is a prerequisite for its newly acquired behavioral role. In addition, the adult MN5 displays larger Ca2+ currents. The dendrites of MN5 undergo extensive remodeling. Drastic regression of larval dendrites during early pupal stages is followed by rapid growth of new dendrites. Critical changes in excitability take place during the onset of adult dendrite formation. Larval Ca2+ currents are absent when dendritic remodeling is most dramatic but increase markedly during later development. Changes in Ca2+ and K+ currents follow different time courses, allowing the transient occurrence of Ca2+ spikes during pupal stages when new dendritic branching ceases. The adult MN5 can produce prolonged Ca2+ spikes after K+ currents are reduced. We suggest that alterations in Ca2+ and K+ currents are necessary for the participation of MN5 in flight behavior and that the transient production of Ca2+ spikes may influence postembryonic dendritic remodeling.