脱氧鬼臼毒素对大鼠背根神经节神经元膜电位的影响及其与钠通道的关系

Effect of deoxypodophyllotoxin on membrane potential of DRG neurons and its relation to sodium channel

目的：研究脱氧鬼臼毒素对大鼠背根神经节神经元膜电位的影响及其与钠通道的关系。方法：分别用终浓度为1、5、25、125μmol/L的脱氧鬼臼毒素作用于荧光染料DiBAC4（3）标记的大鼠背根神经节神经元,在激光共聚焦显微镜上监测神经元膜电位的实时动态变化,并观察钠通道阻断剂TTX（tetrodotoxin）对脱氧鬼臼毒素膜电位效应的影响。结果：加入脱氧鬼臼毒素后大鼠背根神经节神经元膜电位呈去极化改变,5 min后达到最大水平,8 min内趋于稳定。1、5、25、125μmol/L的脱氧鬼臼毒素作用5 min后,所测得的荧光强度值分别为62.3±2.1、63.8±3.6、68.5±3.8、88.1±5.4,和空白对照组相比差异均有显著性（P〈0.01）。1μmol/L TTX与大鼠背根神经节神经元共孵育20 min后再加入25μmol/ml脱氧鬼臼毒素所测值为57.5±2.3,与对照组相比无显著差异（P〉0.05）,说明脱氧鬼臼毒素的膜电位效应可被TTX完全抑制。结论：脱氧鬼臼毒素可引起大鼠背根神经节神经元膜电位去极化,且其效应在1~125μmol/L范围内随浓度增加而增大,钠通道可能参与了这一过程。

Objective：To investigate the effect of deoxypodophyllotoxin（DOP）on membrane potential of dorsal root ganglion（DRG） neurons and its correlation with sodium channel.Methods：DRG neurons were labeled with DiBAC4（3）.Laser scanning confocal microscope was used to monitor the changes of membrane potential at real time on these neurons that were treated with different concentrations of the DOP.The effect of sodium channel blocker TTX（tetrodotoxin） on the changes was also observed.Results：Membrane potential depolarization induced by the DOP peaked at 5 min and became stabilized after 8min.After compared with fluorescence intensity without treatment,the normalized fluorescence intensity was 62.3±2.1,63.8±3.6,68.5±3.8,88.1±5.4 in cells which were treated with 1,5,25,125 μmol/L DOP,respectively.These numbers are significantly lower than those from untreated control cells（P0.01）.When DRG neurons were co-incubated with 1 μmol/L TTX for 20 min,then treated with 25 μmol/L DOP,the intensity changed to 57.5±2.3,which was similar to that of the control（P0.05）.This indicated that the effect of DOP could be completely inhibited by TTX.Conclusion：DOP induces membrane depolarization of DRG neurons in the range of 1-125 μmol/L and the sodium channel should be involved in this process.