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

Abstract

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. Key words: Melatonin; Potassium channels,voltage-gated; Hippocampns; Neurons