Molecular and electrophysiological characterization of the sensory neuron-specific Na channels

感觉神经元特异性Na通道的分子和电生理学特征

基本信息

批准号：
13670043
负责人：
OGAT Nobukuni
金额：
$ 2.11万
依托单位：
HIROSHIMA UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2002
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-13670043/
关键词：
sodium channel dorsal root ganglion tetrodotoxin channel conductance voltage-clamp patch-clamp

项目摘要

Sensory neurons in dorsal root ganglia (DRG) express at least seven isoforms of voltage-gated sodium channel (VGSC) α-subunits. These isoforms show localized distribution within the primary sensory path-way and probably mediate multiple types of sodium currents (I-Na) with different kinetic properties, giving rise to fast, slow or persistent I-Nas. However, little is known as to which isoform is responsible for a particular I-Na in DRG neurons. We have recently identified two types persistent I-Nas: one is resistant to tetrodotoxin (TTX) and found exclusvely in small DRG neurons (I-TTX-R/persist),and theother is sensitive to TTX and found in medium / large DRG neurons (I-TTX-S / persist). Available data suggest that the former is most likely to be mediated by NaVl.9, while the latter may be mediated by NaV1.6. To confirm these possibilities, we performed single cell nested RT-PCR combined with concurrent patch clamp recording and investigated the correlation between mRNA expression and … More phenotype of I-NA in an identified DRG neuron. I-TTX-R / persist was recorded in isolation from small DRG neurons of NaV1.8-null mutant mice in the presence of TTX. Most of the small neurons, which were associated with NaV1.9 transcript, manifested I-TTX-R / persist, confirming that the isoform mediating I-TTX-R / persist is probably Nav1.9 Unexpectedly, however, Nav1.9 was evident also in a considerable number of medium / large neurons that were totally devoid of I-TTX-R / persist. These results indicate that I-TTX-R / persist is not solely dependent on the level of Nav1.9 transcript. An intriguing finding was that Nav1.9 transcript was often absent in small DRG neurons from naive mice while the same transcript was evident in most of the small DRG neurons from mutants. Expression of NaV1.6 transcript was demonstrated in a considerable portion of the medium / large neurons from both naive and mutant mice. However, these neurons did not consistently manifest I-TTX-S / persist suggesting that I-TTX-S / persist may not be carried b NaV1.6. Less

背根神经节 (DRG) 中的感觉神经元表达至少七种电压门控钠通道 (VGSC) α 亚基同工型，这些同工型在主要感觉通路中表现出局部分布，并可能介导多种类型的钠电流 (I-)。 Na）具有不同的动力学特性，产生快速、缓慢或持久的 I-Na。然而，我们最近对 DRG 神经元中特定的 I-Na 的亚型负责却知之甚少。确定了两种类型的持久性 I-Nas：一种对河豚毒素（TTX）具有抗性，仅在小 DRG 神经元中发现（I-TTX-R/persist），另一种对 TTX 敏感，在中/大 DRG 神经元中发现（I-TTX-R/persist）。 -TTX-S/持续）。现有数据表明前者最有可能由NaV1.9介导，而后者可能由NaV1.6介导。为了证实这些可能性，我们进行了单细胞实验。巢式 RT-PCR 结合并发膜片钳记录，并研究了从 NaV1.8 的小 DRG 神经元中分离记录的已识别 DRG 神经元中 mRNA 表达和 I-NA 表型之间的相关性。 -无效突变小鼠在存在TTX时，与NaV1.9转录物相关的大多数小神经元表现出I-TTX-R/持续，证实介导I-TTX-R/持续的亚型可能是Nav1.9 然而，出乎意料的是，Nav1.9 在相当数量的完全缺乏 I-TTX-R/持续的中/大神经元中也很明显。这些结果表明 I-TTX-R/持续不是唯一依赖的。一个有趣的发现是，Nav1.9 转录本在幼稚小鼠的小 DRG 神经元中经常缺失，而在大多数突变体的小 DRG 神经元中却有明显的表达。 NaV1.6 转录物在幼稚小鼠和突变小鼠的相当一部分中/大神经元中得到证实，但是，这些神经元并未一致地表现出 I-TTX-S/持续，这表明 I-TTX-S/持续可能不是。携带 b NaV1.6。