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E. Ivanova, S. Majumdar, J. Weiss, H. Wassle; Glycine Receptors in the Mouse Retina . Invest. Ophthalmol. Vis. Sci. 2006;47(13):2273.
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© ARVO (1962-2015); The Authors (2016-present)
Glycinergic amacrine cells are small field cells with vertically oriented and often bistratified dendrites. They are engaged in local interactions between the different sublayers of the inner plexiform layer. Their output synapses contact bipolar cells, other amacrine cells and ganglion cells. Here we evaluated the functional properties and subunit composition of glycine receptors (GlyRs) in bipolar, amacrine and ganglion cells.
Patch–clamp recordings were performed from retinal slices and wholemounts of wildtype, Glrα1(–/–) and Glrα3(–/–) mice. Whole–cell currents following glycine application and glycinergic inhibitory postsynaptic currents (IPSCs) were analyzed. During the recordings the cells were filled with Alexa488 and unequivocally identified.
Glycine–induced currents of bipolar cells were picrotoxinin insensitive and thus represent heteromeric α/ß channels. OFF–cone bipolar and rod bipolar cells showed prominent glycine–induced currents and frequent IPSCs with short decay time constants. By comparing IPSCs in wildtype and Glrα3(–/–) mice, no statistically significant difference was found, however, glycine–induced currents and glycinergic IPSCs were absent from all bipolar cells of Glrα1(–/–) mice. We did not observe glycinergic IPSCs in ON–cone bipolar cells and could elicit only small, if any, glycinergic currents. In contrast to bipolar cells, amacrine cells exhibited a wider range of generally slower IPSCs. Relatively fast IPSCs were recorded preferentially in AII cells. No difference was found between glycine–evoked currents and IPSCs of wildtype and Glrα1(–/–) mice.
All three alpha subunits seem to be expressed in ganglion cells. Alpha–ganglion cells exhibited fast IPSCs, comparable to those of bipolar cells. Other types of the ganglion cells showed a broad range of kinetics of IPSCs.
Retinal neurons forming the fast vertical signal pathway such as bipolar cells and alpha–ganglion cells receive glycinergic input through fast, α1–containing channels. Cells, carrying more modulatory functions, such as most amacrine and ganglion cells express slower α2–, α3–containing channels.
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