大鼠视皮层两类神经元的NMDA及GABA_A受体介导的突触后电流电学特性研究

Properties of the postsynaptic currents mediated by NMDA receptors or GAB_A receptors recorded in the pyramidal or granular neurons of rat visual cortex

目的在视觉发育可塑性关键期内，探讨大鼠视皮层神经元的细胞类型与兴奋性和抑制性突触后反应的关系。方法对出生后14—28d龄正常大鼠进行视皮层脑片膜片钳全细胞记录，分别采用神经药理学方法分离和记录谷氨酸和N-甲基-D-天冬氨酸（N-methyl-D-aspartate，NMDA）受体介导的兴奋性突触后电流（excitatory postsynaptic currents，EPSCs）以及γ-氨基丁酸（gamma-aminobutyric acid，GABAA）受体介导的抑制性突触后电流（inhibitory postsynaptic currents，IPSCs），并进行神经元细胞内标记、免疫细胞化学染色。结果锥体细胞和颗粒细胞的NMDA受体介导的EPSCs峰值、上升时间、下降时间及NMDA／谷氨酸电流比率并无显著性差异（P〉0．05）；锥体细胞GABAA受体介导的IPSCs下降时间较颗粒细胞的短（P〈0．05），而峰值和上升时间并无显著性差异（P〉0．05）。结论在视觉发育可塑性关键期内，GABAA受体在大鼠视皮层不同神经元的突触传递中可能发挥不同的作用．而NMDA受体在不同神经元的突触传递中具有同质性。

Objective To investigate the relationship of the neuron shape of rat visual cortex with the properties of excitatory postsynaptic currents （EPSCs） mediated by N-methyl-D-aspartate （NMDA） receptors and inhibitory postsynaptic currents （IPSCs） mediated by γ-aminobutyric acid （GABAA ） receptors during the critical period of visual development. Methods We recorded the postsynaptic currents in the visual cortex slices of Wistar rats at postnatal days 14 to 28 by using whole-cell patch, and recorded pharmaceutically the postsynaptic currents mediated by NMDA receptors or GABAA receptors, and performed the intracellular labelling. Results The peak value, rise time and decay time of EPSCs mediated by NMDA receptors and the NMDA/Glutamate ratio of pyramidal neurons in the visual cortex were similar to that of granular neurons （P 〉 0. 05 ） ; The decay time of IPSCs of pyramidal neurons in the visual cortex was shorter than that of granular neurons （P 〈 0. 05 ）, but the peak value and rise time did not change markedly （P 〉 0. 05 ）. Conclusion During the critical period of visual development, GABAA receptors play the various role in the synaptic transmission of different rat visual cortical neurons, but NMDA receptors has the homogeneous property.