Glutamate receptor channels in hippocampal neurons and their development

哺乳动物中枢神经系统中的谷氨酸受体通道分为三种亚型：NMDA、AMPA/红藻氨酸（KA）和KA选择性受体通道。AMPA/KA受体通道被AMPA和KA激活。本研究主要研究了17 ~ 19日龄大鼠胚胎海马神经元AMPA/KA受体的特性及其发育。结果总结如下。1)培养的海马神经元在接种后7天内对KA和AMPA变得敏感。这是由于AMPA/KA受体的发育，而不是KA选择性受体的发育。此后，KA或AMPA诱导的电流幅度逐渐增加。2)AMPA/KA受体可分为两类。I型受体表现出外向整流的电流-电压（I-V）关系，几乎没有Ca^2+渗透性。与此相反，II型受体的特征是显著的内向整流和显著的Ca^2+渗透性。C ...更多信息 结合全细胞膜片钳记录和从单个神经元收集的mRNA的PCR扩增，我们确定了海马神经元中表达的I型和II型AMPA/KA受体的亚基组成。I型受体由GluR 1和GluR 2亚基组成，而II型受体由GluR 1和GluR 4亚基组成。3)II型AMPA/KA受体在接种后1-5周仅出现在具有椭圆形胞体和细神经突的小神经元中。这些神经元似乎是GABA能中间神经元，因为在这些神经元中检测到GAD。4)当CA 1区锥体细胞与CA 3/CA 4区神经元建立兴奋性突触时，在突触后CA 1区神经元的顶树突上可观察到高密度的AMPA斑点。快速EPSC和AMPA在这些斑点上的响应都呈现几乎线性的I-V关系。这表明I型AMPA/KA受体比II型AMPA/KA受体更负责在该兴奋性突触中产生快速EPSC。少

Glutamate receptor channels in the mammalian central nervous system are classified into three subtypes; NMDA, AMPA/kainate (KA) and KA-selective receptor channels. AMPA/KA receptor channels are activated by both AMPA and KA. In this study, we investigated mainly the properties of AMPA/KA receptors and their development in cultured rat hippocampal neurons prepared from 17- to 19-day-old rat embryos. The results are summarized as follows. 1) Cultured hippocampal neurons became sensitive to KA and AMPA within 7 days after plating. This is due to the development of AMPA/KA receptors, but not of KA-selective receptors. Thereafter, the amplitude of KA- or AMPA-induced current increased gradually. 2) AMPA/KA receptors were classified into two types. The type I receptor exhibited an outwardly-rectifying current-voltage (I-V) relation with little Ca^<2+> permeability. In contrast, the type II receptor was characterized by a remarkable inward rectification and a prominent Ca^<2+> permeability. C … More ombining whole-cell patch-clamp recordings and the PCR amplification of the mRNA harvested from a single neuron, we determined the subunit composition of the type I and type II AMPA/KA receptors expressed in hippocampal neurons. The type I receptor was composed of the GluR1 and GluR2 subunits, whereas the type II receptor of the GluR1 and GluR4 subunits. 3) The type II AMPA/KA receptor appeared exclusively in small neurons with elliptical somata and fine neurites throughout 1-5 weeks after plating. These neurons seem to be GABA ergic interneurons, since GAD was detected in these neurons. 4) When the excitatory synapse was established between dissociated CA1 pyramidal cells and neurons from the CA3/CA4 regions, high-density AMPA spots were detected on the apical dendrite of the postsynaptic CA1 neuron. Both the fast EPSC and the AMPA response on these spots showed almost linear I-V relations. This suggests that the type I AMPA/KA receptor is more responsible for generating the fast EPSC in this excitatory synapse than the type II AMPA/KA receptor. Less