Complete elucidation of mechanisms of actions of antitussives for developing novel cough-regulating drugs desired by aged peoples

彻底阐明镇咳药作用机制，开发老年人所需的新型止咳药物

基本信息

批准号：
13557223
负责人：
TAKAHAMA Kazuo
金额：
$ 1.41万
依托单位：
Kumamoto University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
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

项目摘要

In this project, at first, we investigated the actions of various centrally-acting antitussives on various currents mediated by 5-HT_<1A>, GABA_B or adrenergic α_2 receptors, in single brain neurons using whole cell and nystatin-perforated patch clamp techniques. Secondarily, we investigated the action of bradykinin (BK) on paratracheal ganglion (PTG) neurons, and further whether BK modified muscarinic and nicotinic responses in PTG neurons using the same techniques. [Results] 1) All non-narcotic centrally-acting antitussives studied inhibited 5-HT_<1A> receptor mediated inward current (I_H<5-HT>) in dorsal raphe (DR) neurons. This action was suggested to be due to inhibition of G-protein coupled inwardly rectifying K^+ channels (GIRK) coupled to 5-HT_<1A> receptor, because these antitussives effectively inhibited GIRK currents irreversibly activated by 5-HT under condition of intracellular perfusion of GTP-γS. 2) δ-Antagonists, naltriben (Nal) and naltrindole, which have an antitussive action, also have the same action on the currents. 3) Badofen, a GABA_B receptor agonist, also activated GIRK currents in DR neurons. 4) DM, cloperastine (Clo) and Nal also inhibited GABA_B receptor mediated currents in a concentration-dependent manner, with IC_<50>s of 8.23 × 10^<-6>M, 1.36 × 10^<-6>M and 4.36 × 10^<-6>M, respectively. 5) DM, do and Nal inhibited not only I_<5-HT> and I_<bac>. But also GIRK currents mediated by α2-adrenoceptor at almost the same concentration. 6) BK strongly activated PTG neurons through inhibition of M-channels. 7) In PTG neurons, BK caused additive effect on muscarinic responses and synergistic effect on nicotinic responses.

在该项目中，首先，我们使用全细胞和制霉菌素穿孔膜片钳技术，研究了各种中枢镇咳药对单脑神经元中 5-HT_1A、GABA_B 或肾上腺素能 α_2 受体介导的各种电流的作用。其次，我们研究了缓激肽 (BK) 对气管旁神经节 (PTG) 神经元的作用，并进一步研究了 BK 是否修饰毒蕈碱和[结果] 1) 研究的所有非麻醉性中枢镇咳药均抑制中缝背侧 (DR) 神经元中 5-HT_<1A> 受体介导的内向电流 (I_H<5-HT>)。该作用被认为是由于与5-HT_<1A>偶联的内向整流K^+通道(GIRK)的G蛋白的抑制。受体，因为这些镇咳药在细胞内灌注 GTP-γS 的情况下，可有效抑制 5-HT 不可逆激活的 GIRK 电流。 2) 具有镇咳作用的 δ-拮抗剂纳曲苯 (Nal) 和纳曲吲哚也具有相同的作用。 3) Badofen，一种 GABA_B 受体激动剂，也激活 DR 神经元中的 GIRK 电流。 DM、氯哌斯汀（Clo）和Nal也以浓度依赖性方式抑制GABA_B受体介导的电流，IC_<50>s分别为8.23×10^<-6>M、1.36×10^<-6>M和分别为4.36×10^-6M 5)DM、do和Nal不仅抑制I_<5-HT>和。 I_<bac>。但几乎相同浓度的 α2-肾上腺素受体介导的 GIRK 电流 6) BK 通过抑制 M 通道激活 PTG 神经元 7) 在 PTG 神经元中，BK 对毒蕈碱反应产生累加效应和协同效应。烟碱反应。