Thymol, a phenolic monoterpene, is well known for its antimicrobial, antifungal and antioxidant properties. In spite of wide use in oral care products, pharmaceutical and cosmetic preparation and in food industry, the effects of thymol on the neuronal activity and intrinsic properties have not been well studied. We studied the effects of thymol on the spontaneous activity and action potential properties of central neurons of snail Caucasotachea atrolabiata. Thymol (1 mM) altered action potentials characteristics and provoked epileptiform burst firing in snail neurons, which were partially reversible after washout. Before burst firing, action potentials had lower amplitude and maximum rising slope, while the threshold voltage was raised. These results suggest the inhibition of ion channels underlying action potential initiation and upstroke. The maximum falling slope and afterhyperpolarization were also considerably reduced, suggesting the inhibition of potassium channels. Thymol (0.5 mM) that was not able to induce burst firing in snail neurons, synergistically acted with potassium channel blocker, tetraethyl ammonium, to induce burst firing, which also supports the importance of potassium channel inhibition, especially delayed rectifier potassium channels, to the thymol-induced alteration of firing pattern. The thymol-induced burst firing seems to be dependent on both sodium and calcium currents. Our findings provide evidences for the ability of thymol in altering the firing mode of central neurons of snail, which apparently involves the inhibition of calcium and potassium currents. These results further support the interaction of thymol with ion channels and emphasize on the vulnerability of nervous system to this compound.

中文翻译：

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百里香酚在蜗牛Caucasotachea atrolabiata的神经元中激发动作电位爆发。

百里酚，一种酚类单萜，以其抗微生物，抗真菌和抗氧化性能而闻名。尽管广泛用于口腔护理产品，药物和化妆品制剂以及食品工业中，百里酚对神经元活性和内在特性的影响尚未得到很好的研究。我们研究了百里酚对蜗牛Caucasotachea atrolabiata中枢神经元的自发活动和动作电位特性的影响。百里酚（1 mM）改变了蜗牛神经元的动作电位特征并引起了癫痫样发作，其冲刷后可部分逆转。在爆发放电之前，动作电位具有较低的幅度和最大的上升斜率，而阈值电压却升高了。这些结果表明抑制了潜在的动作电位引发和上冲的离子通道。最大下降斜率和超极化后也大大减少，表明钾通道的抑制作用。不能在蜗牛神经元中引起猝发放电的百里香酚（0.5 mM）与钾通道阻滞剂四乙基铵协同作用，引起猝发放电，这也支持了钾通道抑制的重要性，特别是延迟的整流钾通道，对于百里香酚引起的射击方式改变。百里酚引起的猝发放电似乎既依赖于钠电流，又依赖于钙电流。我们的发现为百里酚改变蜗牛中枢神经元放电模式的能力提供了证据，这显然涉及抑制钙和钾电流。