P2X2 receptors on ganglion and amacrine cells in cone pathways of the XXXX retina.

@entity1246 @entity1877 @entity842 @entity35 @entity669 @entity855
Extracellular @entity855 is known to mediate fast, excitatory neurotransmission through activation of ionotropic P2X receptors. In this study, the localization of the P2X(2) receptor (P2X(2)R) subunit was studied in @entity35 retina by using immunofluorescence immunohistochemistry and preembedding immunoelectron microscopy. The P2X(2)R was observed in large ganglion cells as well as in a subset of amacrine cells. Double labeling revealed that 96% of all P2X(2)R-immunoreactive amacrine cells showed @entity1246 ( @entity1246 ) immunoreactivity. Subsets of P2X(2)R-immunoreactive amacrine cells expressed @entity842 synthase and substance P; however, no colocalization was observed with @entity1877 acetyltransferase, vasoactive intestinal peptide, or @entity669 hydroxylase. Nearest-neighbor analysis confirmed that P2X(2)Rs were expressed by a heterogeneous population of amacrine cells. The synaptic connectivity of P2X(2)R amacrine cells was also investigated. It was interesting that P2X(2)R-immunoreactive amacrine cell dendrites stratified in the sublaminae of the inner plexiform layer occupied by cone, but not rod bipolar cell axon terminals. Immunoelectron microscopy revealed that P2X(2)-immunoreactive amacrine cell processes were associated with cone bipolar cell axon terminals as well as other conventional synapses in the inner plexiform layer. Taken together, these data provide further evidence for the involvement of extracellular @entity855 in neuronal signaling in the retina, particularly within cone pathways.
