Role of α_2-adrenoreceptor on the excitability of trigeminal root ganglion neurons : Patch-clamp and Single-cell RT-PCR analysis

α_2-肾上腺素受体对三叉神经根神经节神经元兴奋性的作用：膜片钳和单细胞 RT-PCR 分析

• 批准号: 13671953
• 负责人: TAKEDA Mamoru
• 金额: $ 1.92万
• 依托单位: Nippon Dental 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-13671953/
• 关键词: trigeminal root ganglion; perforated patch-clamp; Reverse transcription-Polymerase chain reaction; α_2-adrenoreceptors; I_h; Whole-cell patch-clamp; nociception; Single-cell; 穿孔パッチ法; I_h電流; クロニジン

The aim of the study was to mauiine the effects of α_2-adrerioreceptar agonists on the excitability of teigeminalroot ganglion (TRG) neurons using the perforated-patch damp technique, and to deternine wither these neurons express mRNA for α_2-adrenoreceptors. In cunent-clamp mode, the testing membrane potential was -57.4 ± 1.2 mV(n=26). Most neurons (71%) were hyperpolarized by clonidine (5-50μM) in a concentration-dependent manner. The response was associated with an increase of cell input resistance. In addition, clonidine reduced the repetitive firing evoked by depolarizing current pulses. An α_2-adrenergic agonist UK14,304 (10-20μM) also hyperpolarized TRG neurons. The donidine- and UK14, 304- induced hyperpdarizatian was blocked by idazoxan (α_2-adrenoreoeptor antagonist). In voltage-damp, donidine (1-50μM) reversibly reduced the hyperpolarization- and -time dependent cationic current. The effect was mimicked by UK13,304 (10-20μM), and antagonized by idazoxan. Hyperpoiarization-activated cationic current was blocked by extracelluar Cs^+ (2mM) or a specific blocker, ZD7288 (20μM). Analysis of taii-cinrcnts revealed that a reversal potential of the clonidine sensitive component of hyperpolarization-activated cationic current was -46mV. Single cell reverse transcription-polymerase chain reaction analysis demonstrated the expression of mRNA for α_<2A> and α_<2C> adrenoreceptors.These results demonstrate that activation of α_2-adrenoreceptors can hyperpolarize TRG neurons, and that the in hibitory effect is associated with inhibition of hyperpolarization-activated cationic current. Our results suggest that activation of α_2-adrenoreceptors in the absence of nerve injury may have an inhibitory effect on nociceptive transmission in the trigeminal system at the level of both TRG neuronal cell bodies and primary afferent terminals.

本研究旨在用膜片钳技术观察α_2-肾上腺素受体激动剂对三叉神经根节（TRG）神经元兴奋性的影响，并检测这些神经元是否表达α_2-肾上腺素受体mRNA。在电流钳模式下，测试膜电位为-57.4 ± 1.2 mV（n=26）。可乐定（5-50μM）可使大多数神经元（71%）呈浓度依赖性超极化。该反应与细胞输入电阻的增加有关。此外，可乐定减少去极化电流脉冲引起的重复放电。α_2-肾上腺素能激动剂UK 14，304（10-20μM）也使TRG神经元超极化。α_2-肾上腺素能受体拮抗剂咪唑克生（idazoxan）可阻断多奈定（donidine）和UK 14，304引起的肾上腺皮质功能亢进。在电压阻尼下，多尼丁（1-50μM）可逆地降低超极化和时间依赖性阳离子电流。UK 13，304（10-20μM）可模拟此作用，咪唑克生可拮抗此作用。超极化激活的阳离子电流被细胞外Cs^+（2 mM）或特异性阻断剂ZD 7288（20μM）阻断。尾电流分析表明，超极化激活的阳离子电流的可乐定敏感组分的反转电位为-46mV。单细胞逆转录-聚合酶链反应（RT-PCR）分析表明，α_2-肾上腺素<2A>能受体和α<2C>_2-肾上腺素能受体的mRNA均有表达，提示激活α_2-肾上腺素能受体可使TRG神经元兴奋，其抑制作用与抑制超极化激活的阳离子电流有关。结果提示，在无神经损伤的情况下，α_2-肾上腺素能受体的激活可能在TRG神经元胞体和初级传入终末水平上对三叉神经系统伤害性信息传递产生抑制作用。

项目成果

M. Takeda, M. Ikeda, T. Tanimoto, J. Lipski, S.Matsumoto: "Changes of excitability of rat trigeminal ganglion neurons evoked by α_2-adrenoreceptors"Neuroscience. 115. 731-741 (2002)

M. Takeda、M. Ikeda、T. Tanimoto、J. Lipski、S. Matsumoto：“α_2-肾上腺素受体诱发的大鼠三叉神经节神经元的兴奋性变化”神经科学。 115. 731-741 (2002)

M.Takeda, M.Ikeda, T.Tanimoto, J.Lipski, S.Matsumoto: "Changes of excitability of rat trigeminal ganglion neurons evoked by α_2-adrenoreceptors"Neuroscience. 115. 731-741 (2002)

M.Takeda、M.Ikeda、T.Tanimoto、J.Lipski、S.Matsumoto：“α_2-肾上腺素受体诱发的大鼠三叉神经节神经元的兴奋性变化”神经科学 115. 731-741 (2002)。

M.Takeda, M.Ikeda, T.Tanimoto, J.Lipski, S.Matsumoto: "Changes of excitability of rat trigeminal ganglion neurons evoked by α2-adrenoreceptors"Neuroscience. 115. 731-741 (2002)

M.Takeda、M.Ikeda、T.Tanimoto、J.Lipski、S.Matsumoto：“α2-肾上腺素受体诱发的大鼠三叉神经节神经元的兴奋性变化”神经科学 115. 731-741 (2002)。