Inhibitory effects of lappaconitine on the neuronal isoforms of voltage-gated sodium channels
Inhibitory effects of lappaconitine on the neuronal isoforms of voltage-gated sodium channels
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高乌头碱对电压门控钠通道神经元亚型的抑制作用
DOI：
10.1038/s41401-018-0067-x
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发表时间：
2019-04-01
影响因子：
8.2
通讯作者：
Gao, Zhao-bing
中科院分区：
文献类型：
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作者：
Li, Yan-fen;Zheng, Yue-ming;Gao, Zhao-bing
高乌甲素（LA）已被广泛用于术后和癌症疼痛控制。LA具有良好的镇痛活性，有效时间比普通局麻药如丁卡因和布比卡因长。然而，LA的特征性镇痛活性的潜在机制在很大程度上仍然未知。在这里，我们报告说，LA是电压门控钠通道1.7（Nav1.7）的抑制剂稳定表达在人胚肾（HEK 293）细胞。LA以电压依赖性方式抑制Nav1.7，当细胞被夹在−70 mV时，IC 50值（95%置信限）为27.67（15.68-39.66）µmol/L。与丁卡因和布比卡因对Nav1.7的快速可逆抑制相比，LA的抑制作用相当缓慢且不可逆。当给予LA（300 µmol/L）时，需要超过10 min才能达到稳态抑制。与丁卡因和布比卡因不同，LA既不影响电压依赖性激活，也不影响通道的失活。据报道，结构域III和结构域IV中的五个残基对于两种局部麻醉剂对Nav通道的作用至关重要。但我们的突变体研究表明，只有两个残基（F1737，N1742）位于结构域IV是必需的抑制活性的LA。LA对Nav1.7通道的抑制作用与局麻药不同，但起效缓慢，不可逆，对通道的激活和失活无影响。这些结果有助于了解LA的镇痛活性，从而有利于其在临床上的应用和未来的药物开发。
Lappaconitine (LA) has been widely used for postoperative and cancer pain control. LA exhibits excellent analgesic activity with a longer effective time than common local anesthetics such as tetracaine and bupivacaine. However, the mechanisms underlying the featured analgesic activity of LA remain largely unknown. Here, we report that LA is an inhibitor of voltage-gated sodium channel 1.7 (Nav1.7) stably expressed in human embryonic kidney (HEK293) cells. LA inhibited Nav1.7 in a voltage-dependent manner with an IC50value (with 95% confidence limits) of 27.67 (15.68–39.66) µmol/L when the cell was clamped at −70 mV. In comparison with the quick and reversible inhibition of Nav1.7 by tetracaine and bupivacaine, the inhibitory effect of LA was rather slow and irreversible. It took more than 10 min to achieve steady-state inhibition when LA (300 µmol/L) was administered. Unlike tetracaine and bupivacaine, LA affected neither the voltage-dependent activation nor the inactivation of the channels. Five residues in domain III and domain IV have been reported to be critical for the effects of the two local anesthetics on Nav channels. But our mutant study revealed that only two residues (F1737, N1742) located in domain IV were necessary for the inhibitory activity of LA. The slow onset, irreversibility, and lack of influence on channel activation and inactivation accompanied with the different molecular determinants suggest that LA may inhibit Nav1.7 channels in a manner different from local anesthetics. These results may help to understand the featured analgesic activity of LA, thus benefiting its application in the clinic and future drug development.