脱氧鬼臼毒素对美洲大蠊背侧不成对中间神经元膜电位的影响及其与钠通道的关系

目的 研究脱氧鬼臼毒素(deoxypodophyllotoxin,DOP)对美洲大蠊背侧不成对中间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DOP作用于荧光染料DiBAC4(3)标记的美洲大蠊背侧不成对中间神经元,在激光共聚焦显微镜上检测神经元膜电位的实时动态变化,并观察钠通道阻断剂河豚毒素(tetrodotoxin,TTX)对DOP膜电位效应的影响.结果 加入DOP后美洲大蠊背侧不成对中间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、125 μmol/L的DOP作用5 min后,所测得的荧光强度值分别为69.6±3.0、72.1±2.7、77.8±3.6、86.2±3.1,DOP处理组和空白对照组相比,差异均有统计学意义(P＜0.01).1μmol/L TTX与美洲大蠊背侧不成对中间神经元共孵育20 min后再加入25 μmol/L DOP,神经元内荧光强度与对照组相比差异无统计学意义(P＞0.05),说明钠通道是DOP的作用靶标,DOP的膜电位效应可被TFX完全抑制.结论 DOP可引起美洲大蠊背侧不成对中间神经元膜电位去极化,且其效应在1～125 μmol/L范围内随浓度增加而增大,钠通道可能参与了这一过程.

Effect of deoxypodophyllotoxin on membrane potential of dorsal unpaired median neurons and its relationship with sodium channel

Objective To investigate the effect ofdeoxypodophyllotoxin(DOP)on membrane potential of dorsal unpaired median neurons (DUM, neurons) and its correlation with sodium channel.Methods DUM 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 tetrodotoxin (TTX) 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 69.6 ±3.0,72.1 ±2.7,77.8±3.6,86.2±3.1 in cells which were treated with 1, 5, 25, 125 μ mol/LDOP, respectively. These numbers were significantly lower than those from untreated control cells (P＜0.01).When DUM neurons were co-incubated with 1 μ mol/L TTX for 20 min, then treated with 25 μmol/L DOP, the intensity changed to 63.6±5.4, which was similar to that of the control (P＞0.05). This indicated that the effect of DOP could be completely inhibited by TTX. Conclusion DOP induced membrane depolarization of DUM neurons in the range of 1～ 125 μmol/L andthe sodium channel should be involved in this process.