培养海马神经元突触外NMDA受体通道电流在发育中的变化

THE DEVELOPMENTAL CHANGE OF EXTRASYNAPTIC NMDA RECEPTOR CHANNEL CURRENTS IN CULTURED HIPPOCAMPAL NEURONS

为观察培养大鼠海马神经元突触外NMDA受体通道电流在发育中的变化,本研究采用膜外面向外模式记录突触外NMDA受体介导的单通道电流。结果显示:培养2周神经元的电流幅度和开放概率比培养1周神经元大,但电导和翻转电位无显著差异。培养2周神经元只出现高电导开放,培养1周神经元同时出现高电导和低电导两种开放形式。NR2B受体亚型的特异性拮抗剂ifenprodil可降低培养1周和2周海马神经元的电流幅度、电导和开放概率,且对培养2周神经元开放概率的抑制作用更明显。以上结果表明,培养海马神经元突触外NMDA受体通道电流有发育变化,且培养1周神经元突触外NMDA受体的NR2亚型可能为NR2B和NR2D;而神经元培养到2同时,突触外主要为NR2B亚型,且数量有所增加。

To investigate the developmental changes of extrasynaptic NMDA receptor （NMDAR） channel currents in cultured hippocampal neurons, outside-out recordings of NMDAR mediated single channel current were performed. The present results showed that the amplitude and open probability in 2 weeks（w） cultured neurons were higher than those of 1 w, without any significant difference in the conductances and reversal potentials. There were both high- and low-conductance openings in 1 w neurons, but only high-conductance openings in 2 w cultured neurons. NR2B subtype specific blocker, ifenprodil, decreased high-conductance and open probability of cultured hlppocampal neurons in both 1 and 2 week groups, and the effect on open probability was more significant in latter one. The above results indicated that there were developmental changes of extrasynaptic NMDA receptor channel currents in cultured hippocampal neurons, and the NMDA receptor subtypes might be NR2B and NR2D in 1 w group, while the NR2B subtype was major in 2 w group and the number increased.