Liu Zhongjie, Zhao Wei, Yuan Pengfei, Zhu Pian, Fan Keke, Xia Zhengyuan, Xu Shiyuan
Department of Anesthesiology, Zhujiang Hospital, Southern Medical University, Industrial Avenue Central 253, Guangzhou, 510282, Guangdong Province, China.
Department of Anesthesiology, University of Hong Kong, Hong Kong, China; Department of Anesthesiology and Pain Medicine, University of California Davis Health System, Sacramento, CA, 95817, USA.
Free Radic Biol Med. 2020 May 20;152:363-374. doi: 10.1016/j.freeradbiomed.2020.04.002. Epub 2020 Apr 7.
Ca/calmodulin dependent protein kinase2α (CaMK2α) is a serine/threonine protein kinase in neurons and leads to neuronal injury when it is activated abnormally. Bupivacaine, a local anesthetic commonly used in regional nerve block, could induce neurotoxicity via apoptotic injury. Whether or not CaMK2α is involved in bupivacaine-induced neurotoxicity and it is regulated remains unclear. In this study, bupivacaine was administered for intrathecal injection in C57BL/6 mice for building vivo injury model and was used to culture human neuroblastoma (SH-SY5Y) cells for building vitro injury model. The results showed that bupivacaine induced mitochondrial oxidative stress and neurons apoptotic injury, promoted phosphorylation of CaMK2α and cAMP-response element binding protein (CREB), and elevated mitochondrial Ca uniporter (MCU) expression. Furthermore, it induced CaMK2α phosphorylation at Thr286 which phosphorylated CREB at Ser133 and up-regulated MCU transcriptional expression. Inhibition of CaMK2α-MCU signaling with knock-down of CaMK2α and MCU or with inhibitors (KN93 and Ru360) significantly mitigated bupivacaine-induced neurotoxic injury. Over-expression of CaMK2α significantly enhanced above oxidative injury. Activated MCU with agonist (spermine) reversed protective effect of siCaMK2α on bupivacaine-induced mitochondrial oxidative stress. Our data revealed that CaMK2α-MCU-mitochondrial oxidative stress pathway is a major mechanism whereby bupivacaine induces neurotoxicity and inhibition of above signaling could be a therapeutic strategy in the treatment of bupivacaine-induced neurotoxicity.
钙/钙调蛋白依赖性蛋白激酶2α（CaMK2α）是神经元中的一种丝氨酸/苏氨酸蛋白激酶，当其异常激活时会导致神经元损伤。布比卡因是一种常用于区域神经阻滞的局部麻醉药，可通过凋亡性损伤诱导神经毒性。CaMK2α是否参与布比卡因诱导的神经毒性及其调控机制尚不清楚。在本研究中，将布比卡因鞘内注射到C57BL/6小鼠体内以建立体内损伤模型，并用于培养人神经母细胞瘤（SH-SY5Y）细胞以建立体外损伤模型。结果表明，布比卡因诱导线粒体氧化应激和神经元凋亡性损伤，促进CaMK2α和环磷酸腺苷反应元件结合蛋白（CREB）的磷酸化，并升高线粒体钙单向转运体（MCU）的表达。此外，它诱导CaMK2α在苏氨酸286位点磷酸化，该位点使CREB在丝氨酸133位点磷酸化并上调MCU的转录表达。通过敲低CaMK2α和MCU或使用抑制剂（KN93和Ru360）抑制CaMK2α-MCU信号通路可显著减轻布比卡因诱导的神经毒性损伤。CaMK2α的过表达显著增强上述氧化损伤。用激动剂（精胺）激活MCU可逆转siCaMK2α对布比卡因诱导的线粒体氧化应激的保护作用。我们的数据表明，CaMK2α-MCU-线粒体氧化应激途径是布比卡因诱导神经毒性的主要机制，抑制上述信号通路可能是治疗布比卡因诱导的神经毒性的一种治疗策略。
