不同浓度褪黑激素对新生大鼠海马神经元电压门控性瞬时外向钾电流的影响

目的 探讨不同浓度褪黑激素对新生大鼠海马神经元电压门控性瞬时外向钾电流(I_A)的影响.方法 原代培养新生Wistar大鼠(出生时间<12 h)海马锥体神经元7～12 d.配制褪黑激素溶液,终浓度依次为1 nmol/L、10 nmol/L、100 nmol/L、1 μmol/L、10 μmol/L、100 μmol/L和1 mmol/L,选择胞体清晰、光晕良好、轴突明显的锥体神经元采用膜片钳全细胞记录模式记录I_A的基本电生理特点,记录不同浓度褪黑激素作用下I_A的动力学.结果 与褪黑激素作用前比较,1、10 nmol/L褪黑激素作用后海马锥体神经元I_A幅度升高(P<0.05),其余浓度褪黑激素作用前后海马锥体神经元I_A幅度比较差异无统计学意义(P>0.05);10 nmol/L褪黑激素作用后海马椎体神经元电压门控性瞬时外向钾通道激活曲线的半数激活膜电位及曲线斜率因子与褪黑激素作用前比较差异无统计学意义(P>0.05).结论 生理浓度褪黑激素可增加体外新生大鼠海马椎体神经元I_A.

Effects of different concentrations of melatonin on the voltage-gated transient outward potassium currents in cultured hippocampal pyramidal neurons of new-born rats in vitro

Objective To investigate the effects of different concentrations of melatonin on the voltage-gated transient outward potassium currents (I_A) in cultured hippocampal pyramidal neurons of new-born rats in vitro. Methods The hippocampal pyramidal neurons were isolated from new-born Wistar rats (<12 h) and cultured for 7-12 days. The whole-cell configuration of the conventional patch-clamp technique was used to record the I_A to analyze the electrophysiological characteristics. Neurons were divided into 7 groups and exposed to different concentrations of melatonin 1 nmol/L, 10 nmol/L, 100 nmol/L, 1 μmol/L, 10 μmol/L, 100 μmol/L and 1 mmol/L. The effects of melatonin on the amplitudes and kinetics of I_A were investigated. Results The effect of melatonin on I_A was rapid and reversible. Melatonin 1 and 10 nmol/L increased the amplitude of I_A, while the other concentrations of melatonin had no effects on the amplitude of I_A. The V_(1/2) of the activation curve and the slop factor (κ) had no change after giving melatonin 10 nmol/L. Conclusion Melatonin within the physiological concentration ranges can reversibly increase I_A in hippocampal pyramidal neurons of new-born rats.