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首页> 外文期刊>The European Journal of Neuroscience >Transient Ca2+-permeable AMPA receptors in postnatal rat primary auditory neurons.
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Transient Ca2+-permeable AMPA receptors in postnatal rat primary auditory neurons.

机译：产后大鼠原发性听觉神经元中的Ca2 +渗透性瞬时AMPA受体。

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摘要

Fast excitatory transmission in the nervous system is mostly mediated by alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptors whose subunit composition governs physiological characteristics such as ligand affinity and ion conductance properties. Here, we report that AMPA receptors at inner hair cell (IHC) synapses lack the GluR2 subunit and are transiently Ca2+-permeable before hearing onset as evidenced using agonist-induced Co2+ accumulation, Western blots and GluR2 confocal microscopy in the rat cochlea. AMPA (100 microM) induced Co2+ accumulation in primary auditory neurons until postnatal day (PND) 10. This accumulation was concentration-dependent, strengthened by cyclothiazide (50 microM) and blocked by GYKI 52466 (80 microM) and Joro spider toxin (1 microM). It was unaffected by D-AP5 (50 microM), and it could not be elicited by 56 mM K+ or 1 mM NMDA + 10 microM glycine. Western blots showed that GluR1 immunoreactivity, present in homogenates of immature cochleas, had disappeared by PND12. GluR2 immunoreactivity was not detected until PND10 and GluR3 and GluR4 immunoreactivities were detected at all the ages examined. Confocal microscopy confirmed that the GluR2 immunofluorescence was not located postsynaptically to IHCs before PND10. In conclusion, AMPA receptors on maturing primary auditory neurons differ from those on adult neurons. They are probably composed of GluR1, GluR3 and GluR4 subunits and have a high Ca2+ permeability. The postsynaptic expression of GluR2 subunits may be continuously regulated by the presynaptic activity allowing for variations in the Ca2+ permeability and physiological properties of the receptor.
机译：神经系统中的快速兴奋性传递主要由α-氨基-3-羟基-5-羟基-5-甲基-4-异恶唑丙酸（AMPA）受体介导，其亚基组成决定着生理特性，如配体亲和力和离子电导特性。在这里，我们报道内耳细胞（IHC）突触处的AMPA受体缺乏GluR2亚基，并且在听力发作之前是Ca2 +可渗透的，这是通过激动剂诱导的Co2 +积累，Western印迹和GluR2共聚焦显微镜在大鼠耳蜗中得到证明的。 AMPA（100 microM）诱导初级听觉神经元中的Co2 +积累，直到出生后第10天（PND）。这种积累是浓度依赖性的，被环噻嗪（50 microM）增强，并被GYKI 52466（80 microM）和Joro蜘蛛毒素（1 microM）阻止。 ）。它不受D-AP5（50 microM）的影响，而不能被56 mM K +或1 mM NMDA + 10 microM甘氨酸诱导。 Western印迹显示，存在于未成熟耳蜗匀浆中的GluR1免疫反应性已被PND12消失。直到在所有检查的年龄都检测到PND10以及GluR3和GluR4免疫反应性，才检测到GluR2免疫反应性。共聚焦显微镜证实，PND10之前，GluR2免疫荧光未与IHC突触后定位。总之，成熟的初级听觉神经元上的AMPA受体与成人神经元上的AMPA受体不同。它们可能由GluR1，GluR3和GluR4亚基组成，并具有较高的Ca2 +渗透性。 GluR2亚基的突触后表达可以通过突触前活性连续调节，从而允许受体的Ca2 +渗透性和生理特性发生变化。

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