The Possible Role of TASK Channels in Rank-Ordered Recruitment of Motoneurons in the Dorsolateral Part of the Trigeminal Motor Nucleus.
The Possible Role of TASK Channels in Rank-Ordered Recruitment of Motoneurons in the Dorsolateral Part of the Trigeminal Motor Nucleus.
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DOI：
10.1523/eneuro.0138-16.2016
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发表时间：
2016-05
期刊：
影响因子：
3.4
通讯作者：
Kang Y
中科院分区：
文献类型：
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作者：
Okamoto K;Emura N;Sato H;Fukatsu Y;Saito M;Tanaka C;Morita Y;Nishimura K;Kuramoto E;Xu Yin D;Furutani K;Okazawa M;Kurachi Y;Kaneko T;Maeda Y;Yamashiro T;Takada K;Toyoda H;Kang Y
由于运动单位的有序募集发生在闭口肌的等长收缩过程中，闭嘴运动神经元(MN)的募集方式可能取决于它们的胞体大小或输入阻力(IR)。在大鼠三叉神经运动核背外侧区(dl-TMN)，MNS大量表达TWIK(双孔区弱内向整流钾通道)相关的酸敏K+通道(TASK)-1和TASK3通道，它们决定IR和静息膜电位。在这里，我们用多种方法研究了任务通道如何参与大鼠dl-TMN中IR依赖的MN的激活/招募。实时荧光定量聚合酶链式反应研究表明，单个大的MN(35μm)比单个小的MN(15-20μm)表达更丰富的TASK1和TASK3mRNAs。免疫组织化学显示，TASK1和TASK3通道分别互补分布于MNS的胞体和树突中。TASK1通道的密度随着胞体直径的减小而增加，而胞体大小与IR、静息膜电位和峰阈值呈负相关。从较小的和较大的MN获得的双重全细胞记录显示，MN的招募取决于它们对假定的Ia传入的重复刺激的IR反应。8-溴鸟苷-cGMP降低了小MN的IRS，但对大MN的IRS几乎没有影响，并随后缩小了小MN和大MN之间的棘波起始潜伏期的差异，导致MN的同步激活。这些结果表明，任务通道在dl-tmn中对MN的等级顺序招募起着关键作用。
Because a rank-ordered recruitment of motor units occurs during isometric contraction of jaw-closing muscles, jaw-closing motoneurons (MNs) may be recruited in a manner dependent on their soma sizes or input resistances (IRs). In the dorsolateral part of the trigeminal motor nucleus (dl-TMN) in rats, MNs abundantly express TWIK (two-pore domain weak inwardly rectifying K channel)-related acid-sensitive-K+ channel (TASK)-1 and TASK3 channels, which determine the IR and resting membrane potential. Here we examined how TASK channels are involved in IR-dependent activation/recruitment of MNs in the rat dl-TMN by using multiple methods. The real-time PCR study revealed that single large MNs (>35 μm) expressed TASK1 and TASK3 mRNAs more abundantly compared with single small MNs (15–20 μm). The immunohistochemistry revealed that TASK1 and TASK3 channels were complementarily distributed in somata and dendrites of MNs, respectively. The density of TASK1 channels seemed to increase with a decrease in soma diameter while there were inverse relationships between the soma size of MNs and IR, resting membrane potential, or spike threshold. Dual whole-cell recordings obtained from smaller and larger MNs revealed that the recruitment of MNs depends on their IRs in response to repetitive stimulation of the presumed Ia afferents. 8-Bromoguanosine-cGMP decreased IRs in small MNs, while it hardly changed those in large MNs, and subsequently decreased the difference in spike-onset latency between the smaller and larger MNs, causing a synchronous activation of MNs. These results suggest that TASK channels play critical roles in rank-ordered recruitment of MNs in the dl-TMN.