Synaptic localization of NMDA receptor subunits in the rat retina

Abstract

The distribution and synaptic clustering of N-methyl-D-aspartate (NMDA) receptors were studied in the rat retina by using subunit specific antisera. A punctate immunofluorescence was observed in the inner plexiform layer (IPL) for all subunits tested, and electron microscopy confirmed that the immunoreactive puncta represent labeling of receptors clustered at postsynaptic sites. Double labeling of sections revealed that NMDA receptor clusters within the IPL are composed of different subunit combinations: NR1/NR2A, NR1/NR2B, and in a small number of synapses NR1/NR2A/NR2B. The majority of NMDA receptor clusters were colocalized with the postsynaptic density proteins PSD-95, PSD-93, and SAP 10..