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P2X 2 receptors on ganglion and amacrine cells in cone pathways of the rat retina
Author(s) -
Puthussery Theresa,
Fletcher Erica L.
Publication year - 2006
Publication title -
journal of comparative neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.855
H-Index - 209
eISSN - 1096-9861
pISSN - 0021-9967
DOI - 10.1002/cne.20889
Subject(s) - inner plexiform layer , amacrine cell , retina , biology , immunoelectron microscopy , microbiology and biotechnology , neuroscience , ganglion cell layer , colocalization , population , axon , chemistry , immunohistochemistry , medicine , immunology , environmental health
Abstract Extracellular ATP 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 rat 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 γ‐aminobutyric acid (GABA) immunoreactivity. Subsets of P2X 2 R‐immunoreactive amacrine cells expressed nitric oxide synthase and substance P; however, no colocalization was observed with choline acetyltransferase, vasoactive intestinal peptide, or tyrosine 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 ATP in neuronal signaling in the retina, particularly within cone pathways. J. Comp. Neurol. 496:595–609, 2006. © 2006 Wiley‐Liss, Inc.