突触内NMDAR通道电流在培养神经元发育中的变化

Developmental Changes of Synatpic NMDA Receptor Channel Currents in Cultured-hippocampal Neurons

【目的】观察培养大鼠海马神经元突触内NMDA受体(NMDAR)通道电流在发育中的变化。【方法】取新生1dSD大鼠海马制成细胞悬液,接种在培养板上进行培养。培养到1周和2周时,采用膜片钳全细胞模式记录神经元突触内自发的微小兴奋性突触后电流(mEPSC)。【结果】培养2周海马神经元突触内NMDA受体介导的mEPSC(mEPSCNMDA)幅度比培养1周神经元小,对NR2B的特异拮抗剂ifenprodil的敏感性降低。Ifenprodil对培养1周神经元mEPSCNMDA的抑制作用达到(80.47±6.12)%,却只抑制(12.27±2.02)%培养2周神经元的mEPSCNMDA。【结论】培养海马神经元突触内NMDA受体通道电流有发育变化,提示培养1周神经元突触内NMDA受体NR2亚单位主要为NR2B;而神经元培养到2周时,突触内NR2B亚单位逐渐被NR2A取代。

[Objective] To investigate developmental changes of synaptic NMDAR mediated-currents in cuhured-hippocampal neurons. [Methods] Hippocampal neurons of PO SD rats were dissociated and cultured. Whole-cell recordings were performed to record miniature excited postsynaptic currents （mEPSC） after neurons were cultured for 1 week and 2 weeks. [Results] The amplitude of NMDAR mediated mEPSC （mEPSCNMDA） decreased in 2 weeks cultivation compared to that of 1 week, and was less sensitive to selective NR2B blocker ifenprodil. Ifenprodil decreased （80.47±6.12）% of mEPSCNMDA in 1 week neurons, while only （12.27±2.02）% in 2 weeks. [Conclusion] There are developmental changes of synatpic NMDAR channel currents in cuhured-hippocampal neurons. The results indicate that different NR2 subtypes are expressed in synaptic regions during development of cuhured-hippocampal neurons. In immature neurons, NR2B are prominent, then replaced by NR2A when neurons become older.