マウス網膜におけるNMDA型受容体チャネルGluRε1サブユニットの分布と機能
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概要
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Glutamate is the main excitatory neurotransmitter in the vertical signal pathway in the vertebrate retina. There are a variety of glutamate receptors (GluRs) in the retina, out of which NMDA receptor is known to regulate synaptic neurotransmission. In order to clarify its function in the retina, I selected GluRε1, one of four NMDA receptor ε subunits, and analyzed the GluRε1 subunit knockout mouse. Immunohistochemistry showed GluRε1, ε2, ζ1 subunit expressions in the outer two-fifth of the inner plexiform layer (IPL) where bipolar cells transfer mostly the OFF signal to amacrine and ganglion cells, suggesting that these subunits were expressed in ganglion and amacrine cells and might participate mainly in the OFF pathways. Physiological functions of the retina were analyzed by electroretinogram (ERG). No significant difference was observed in the amplitude and implicit time of b-wave and amplitude of OPs between wild-type and GluRε1 knockout mice, although there are some reports showing that NMDA receptors are involved in ERG b-wave and oscillatory potentials (OPs). The phenomenon that NMDA currents were reduced but remained in the area where GluRε1 and ε2 were co-localized suggests that GluRε2 subunit might have compensated for the deletion of GluRε1. This is the first study applying ERG in the functional analysis of GluRε1 in retina.
- 2005-10-10