Good Doctor Research Institute, College of Medicine, Korea University, Seoul, South Korea.
Department of Physiology, College of Medicine and Neuroscience Research Institute, Korea University, Seoul, South Korea.
Biochem Biophys Res Commun. 2021 Feb 19;541:36-42. doi: 10.1016/j.bbrc.2021.01.008. Epub 2021 Jan 16.
Methylene blue (MB) is a blue cationic thiazine dye and currently used in different medical settings. Notably, there have been several attempts to introduce MB for attenuating pain in the last decade. Some clinical studies reported remarkable results, which, however, have been much debated. In addition, accumulating evidence have revealed that MB diminishes voltage-gated sodium channel currents. Accordingly, in the present study, we conducted in vivo experiments, including in vivo single nerve recording and behavioral test, to investigate whether MB dampens neural firing rates and ultimately contributes to pain relief. As a result, neural firing rates significantly decreased and finally converged to zero after MB administration. This event lasted longer than that of lidocaine and was dose-dependently modulated. Furthermore, there was a marked improvement in pain behaviors. The withdrawal threshold and latency of hind paws significantly rose post-MB administration. Therefore, these results demonstrate that MB lessens pain by significantly weakening neural excitability, which implies a strong possibility that this dye may be developed as a pain-relieving medication in the future. This is the first in vivo study to elucidate the effect of MB on nerves and pain relief.
亚甲蓝（MB）是一种蓝色阳离子噻嗪染料，目前在不同的医学环境中使用。值得注意的是，在过去十年中，已经有几项尝试将 MB 用于减轻疼痛。一些临床研究报告了显著的结果，但这些结果一直存在争议。此外，越来越多的证据表明，MB 可降低电压门控钠离子通道电流。因此，在本研究中，我们进行了体内实验，包括体内单神经记录和行为测试，以研究 MB 是否能降低神经放电率并最终缓解疼痛。结果显示，MB 给药后神经放电率显著降低，最终降至零。这一事件持续时间长于利多卡因，且呈剂量依赖性调节。此外，疼痛行为也有明显改善。MB 给药后后爪的退缩阈值和潜伏期明显升高。因此，这些结果表明，MB 通过显著减弱神经兴奋性来减轻疼痛，这意味着这种染料将来很有可能被开发为一种缓解疼痛的药物。这是首次阐明 MB 对神经和缓解疼痛影响的体内研究。
