Purpose. Most excitatory synapses in the monkey retina are thought to use glutamate as their neurotransmitter. To define further the neurochemical phenotype of various retinal neuron types, we analyzed the cellular distribution of several glutamate receptor subunit proteins using specific monoclonal antibodies to AMPA subunits GluR2 and GluR2/3, and NMDA subunits NR1 and NR2A. The patterns of colocalization of these GluRs with other markers of retinal neuron subtypes were also analyzed. Methods. The retinas from 15 monkeys were obtained after perfusion of the animals, separated from the eyecup, and small samples were dissected out from the central and peripheral regions. These samples were stained with subunit-specific antibodies to GluRs. Double labeling experiments were performed using polyclonal antibodies to the calcium-binding poteins (CaBPs) parvalbumin (PV), calbindin (CB) and calretinin (CR). The distribution of ganglion cells was also studied using a monoclonal antibody to neurofilament protein (NFP). Results. All classes of GluRs studied were present in large ganglion neurons in all retinal regions. These neurons displayed a morphology similar to that of NFP-containing ganglion cells. Subsets of amacrine neurons demonstrated light labeling for GluR2, NR1 and NR2A that was colocalized in many cases with CR labeling. GluR2/3 and NR1 labeling was also present in the inner nuclear layer where it colocalized with some PV-positive, large horizontal cells. CB was present in a large subset of bipolar neurons that also showed faint GluR2 labeling. Conclusions. These results reveal the existence of cell-type specific distribution of GluRs in the monkey as well as select patterns of colocalization with CaBPs and NFP. These cellular patterns could be related to the involvement of glutamate-mediated excitotoxic mechanisms and the differential neuronal vulnerability of retinal neuron subtypes that occur in glaucoma.
|Original language||English (US)|
|Journal||Investigative Ophthalmology and Visual Science|
|State||Published - Feb 15 1996|
ASJC Scopus subject areas