Abstract
Abstract: :
Purpose: To find out whether different types of glutamate receptors are involved with different types of bipolar cells in the inner retina of a New World monkey, the marmoset, Callithrix jacchus. Methods: Vertical cryostat sections through central marmoset retina were double labelled with immunohistochemical markers for bipolar cell types (flat midget bipolar cells, diffuse bipolar cell types DB3 and DB6, and rod bipolar cells) and with antibodies specific for ionotropic glutamate receptor subunits. The AMPA receptor subunits GluR1, 2, 2/3 and 4, the kainate receptor subunits GluR6/7 and the NR1C2’ subunit of the NMDA receptor were studied. The axon terminals of bipolar cell types were reconstructed from confocal sections and the co-localized immunoreactive puncta were quantified. Results: For all bipolar cell types, immunoreactive puncta for the AMPA receptor subunits GluR2, 2/3 and 4 were found most frequently (between 20 and 55 puncta per axon terminal), whereas GluR1 immunoreactive puncta were expressed at very low densities (maximally 9 puncta per axon terminal). The kainate receptor subunits GluR6/7 were associated at low densities with DB6 and rod bipolar cells. The NMDA receptor subunit NR1C2’ was predominantly co-localized with the axon terminals of flat midget bipolar cells. Conclusions: These data suggest that bipolar cell types are presynaptic to multiple glutamate receptor subtypes in primate retina.
Keywords: retina: proximal(bipolar, amacrine, and gangli • excitatory amino acid receptors • microscopy: light/fluorescence/immunohistochem