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Characterization of the glycinergic input to bipolar cells of the mouse retina
Author(s) -
Ivanova Elena,
Müller Ulrike,
Wässle Heinz
Publication year - 2006
Publication title -
european journal of neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.346
H-Index - 206
eISSN - 1460-9568
pISSN - 0953-816X
DOI - 10.1111/j.1460-9568.2005.04557.x
Subject(s) - glycine receptor , glycine , inhibitory postsynaptic potential , neuroscience , postsynaptic current , patch clamp , chemistry , strychnine , gabaergic , retina , protein subunit , electrophysiology , biophysics , biology , biochemistry , amino acid , gene
Glycine and γ‐aminobutyric acid (GABA) are the major inhibitory transmitters of the mammalian retina, and bipolar cells receive GABAergic and glycinergic inhibition from multiple amacrine cell types. Here we evaluated the functional properties and subunit composition of glycine receptors (GlyRs) in bipolar cells. Patch‐clamp recordings were performed from retinal slices of wild‐type, GlyRα1‐deficient ( Glra1 spd‐ot ) and GlyRα3‐deficient ( Glra3 –/– ) mice. Whole‐cell currents following glycine application and spontaneous inhibitory postsynaptic currents (IPSCs) were analysed. During the recordings the cells were filled with Alexa 488 and, thus, unequivocally identified. Glycine‐induced currents of bipolar cells were picrotoxinin‐insensitive and thus represent heteromeric channels composed of α and β subunits. Glycine‐induced currents and IPSCs were absent from all bipolar cells of Glra1 spd‐ot mice, indicating that GlyRα1 is an essential subunit of bipolar cell GlyRs. By comparing IPSCs of bipolar cells in wild‐type and Glra3 –/– mice, no statistically significant differences were found. OFF‐cone bipolar (CB) cells receive a strong glycinergic input from AII amacrine cells, that is preferentially based on the fast α1β‐containing channels (mean decay time constant τ = 5.9 ± 1.4 ms). We did not observe glycinergic IPSCs in ON‐CB cells and could elicit only small, if any, glycinergic currents. Rod bipolar cells receive a prominent glycinergic input that is mainly mediated by α1β‐containing channels (τ = 5.5 ± 1.6 ms). Slow IPSCs, the characteristic of GlyRs containing the α2 subunit, were not observed in bipolar cells. Thus, different bipolar cell types receive kinetically fast glycinergic inputs, preferentially mediated by GlyRs composed of α1 and β subunits.