以局麻药毒性靶标TASK通道为导向的新型弱毒性局麻药开发

With the rapid development of precision medicine and comfortable care, local anesthetics are increasingly applied in clinic. Although local anesthetics are generally safe, risks persist and toxic reactions remain a problem. FDA reports the mortality ranges from 2% to 5% induced by the toxicity of classical local anesthetics. The mechanism underlying the toxicity by local anesthetics remains unclear. There is no effective special antidote for the toxicity. Our previous findings showed knockout of TASK-1 and TASK-3 reduced the sensitivity to seizure by local anesthetics, and alleviated ECG disturbances and mortality in mice, suggesting TASK channel is an important molecular target for the CNS and cardiac toxicity by local anesthetics. Based on the clinical need and our previous results, the aim of this project is to develop novel local anesthetic with lower toxicity by creating TASK channel modeling and docking model of screened compounds to the voltage-gated sodium (Nav) channel (regional anesthesia action target) and TASK channels (a toxicity target), modifying screened compound that could selectively block Nav channel while shows lower inhibition of TASK channels. We will test the efficacy and safety of the compounds using animal in vivo regional anesthesia model and toxicity model as well as electrophysiological recordings. Our most recent recordings showed T93 and T198 amino acids are important targets for local anesthetic gating of TASK channels. We also found com-13 showed significantly lower inhibition of TASK channel as compared with bupivacaine, which can be an initial compound among the screened and modified highly selective sodium channel blockers. Those findings lay a solid foundation for successful conducting of this project.

随着精准、舒适化医疗的快速发展，局麻药的应用日益广泛，但也存在较严重的毒性反应，FDA数据显示经典局麻药毒性反应致死率在2-5%。目前局麻药的毒性反应机制尚不清楚，也无特效解救药。本课题组前期研究发现1）敲除TASK-1和TASK-3基因降低小鼠对局麻药致惊厥的敏感性2）敲除TASK-1基因减轻局麻药所致小鼠心电异常及死亡率。这表明TASK通道是局麻药CNS和心脏毒性的一个重要靶标。基于临床需求及我们前期研究，本项目拟通过同源建模和分子对接分析局麻药与麻醉靶标Nav和毒性靶标TASK的相互作用，以其结构信息指导选择性抑制剂的设计，结合电生理和动物在体实验等进行新型弱毒性局麻药的开发。我们最近的电生理实验证实：T93和T198是局麻药与TASK通道作用的重要位点；化合物com-13对TASK通道的抑制效应较布比卡因显著减小，可作为初始化合物。这些结果为本项目顺利开展奠定良好基础。

随着精准、舒适化医疗的快速发展，局麻药的应用日益广泛，但也存在较严重的毒性反应，FDA数据显示经典局麻药毒性反应致死率在2-5%，临床尚无局麻药中毒特效解救药，因此迫切需要开发新型弱毒性局麻药。我们的前期研究表明TASK通道是局麻药产生CNS毒性反应的一个重要靶标。本研究旨在确定局麻药与其毒性靶位TASK通道相互作用的关键位点，基于此结构机制研发与毒性作用靶位弱且具有局麻效应的新型弱毒性局麻药。本项目通过同源建模、构建多个TASK位点突变体及电生理实验证实了：1）F125、L122-L239是局麻药布比卡因、罗哌卡因、利多卡因与TASK通道（TASK-3和TASK-1）的关键作用位点；2）基于结构获得的化合物1对TASK通道的IC50显著低于经典局麻药。同时在动物实验进一步证实：1）所设计化合物1具有局部麻醉效应，在大鼠坐骨神经周围注射可产生感觉和运动神经阻滞效应；2）所设计化合物1与经典局麻药相比其CNS毒性致惊厥ED50显著增高；3）所设计化合物1与经典局麻药相比其半数致死量LD50显著增大。本项目在电生理水平和动物实验水平上验证了围绕局麻药毒性作用靶位设计新型弱毒性局麻药开发思路的科学性和可行性，最终开发并验证了化合物1有作为一种新型弱毒性局麻药的潜能。从理论上而言，本项目研究结果为进一步解读局麻药的毒性发生机制提供新的理论依据；从临床应用方面而言，目前随着加速康复外科理念的快速推广，伴随的是局麻药使用的巨大需求，但目前其毒性反应仍是其临床应用的一大隐患，我们所开发的化合物1作为新型弱毒性局麻药为从源头上解决临床上这一问题奠定实验基础。新型弱毒性局麻药化合物1值得进行进一步的临床前研究。