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yufei liu, Harris Ripps, wen shen; Localization of Pannexin-Mediated Electrical Coupling in the Amphibian Retinal Cone Pathway. Invest. Ophthalmol. Vis. Sci. 2011;52(14):4556.
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© ARVO (1962-2015); The Authors (2016-present)
To localize pannexin gap junction proteins in the vertebrate retina. To assess the function of pannexin in the retinal circuitry.
Standard single- and double-antibody labeling techniques were applied in both 12 micron-thick frozen sections and flat-mounted tiger salamander retinas. An antibody specific for pannexin 1, pan1 (Millipore) was used to locate this gap junction protein in the retina. The specificity of the antibody in control mouse and salamander retinas was verified by Western blotting; antibodies for Goα and EAAT2B were used to label On- and Off-bipolar cells, respectively. Both Alex488 and Cy3 fluorescent-conjugated secondary antibodies (Invitrogen) were used to bind with the primary antibodies and to visualize their labeling pattern. Antibody labeling in retinal tissues was detected with a confocal microscope system.
Anti-pan 1 labeling showed that the pannexin protein was present in a group of bipolar cells that were also Goa positive, indicating that the neurons were On-bipolar cells; punctuate labeling was also detected in the distal sublamina b of the inner plexiform layer (IPL) in which most cone-dominant On-bipolar cells are located. The pan1 antibody also labeled some of processes in the IPL, which were colocalized with a glycine antibody in double-labeled retinal sections, suggesting that pannexins might also be present on the processes of glycinergic amacrine cells.
Our results suggest that glycinergic amacrine cells might communicate with cone-dominant On-bipolar cells via pannexin-mediated electrical coupling. A similar mechanism has been described in the mammalian retina where rod bipolar cells transmit signals to ON cone bipolar cells through the A2 amacrine cells using connexin gap junctional proteins. The results of this study suggest that a comparable pannexin-mediated gap-junctional pathway may be present in the inner retina of amphibia.
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