title: Morphological and physiological properties of enhanced green fluorescent protein (EGFP)-expressing wide-field amacrine cells in the ChAT-EGFP mouse line.
abstract: Mammalian retinas comprise a variety of interneurons, among which amacrine cells represent the largest group, with more than 30 different cell types each exhibiting a rather distinctive morphology and carrying out a unique function in retinal processing. However, many amacrine types have not been studied systematically because, in particular, amacrine cells with large dendritic fields, i.e. wide-field amacrine cells, have a low abundance and are therefore difficult to target. Here, we used a transgenic mouse line expressing the coding sequence of enhanced green fluorescent protein under the promoter for choline acetyltransferase (ChAT-EGFP mouse) and characterized a single wide-field amacrine cell population monostratifying in layer 2/3 of the inner plexiform layer (WA-S2/3 cell). Somata of WA-S2/3 cells are located either in the inner nuclear layer or are displaced to the ganglion cell layer and exhibit a low cell density. Using immunohistochemistry, we show that WA-S2/3 cells are presumably GABAergic but may also release acetylcholine as their somata are weakly positive for ChAT. Two-photon-guided patch-clamp recordings from intact retinas revealed WA-S2/3 cells to be ON-OFF cells with a homogenous receptive field even larger than the dendritic field. The large spatial extent of the receptive field is most likely due to the extensive homologous and heterologous coupling among WA-S2/3 cells and to other amacrine cells, respectively, as indicated by tracer injections. In summary, we have characterized a novel type of GABAergic ON-OFF wide-field amacrine cell which is ideally suited to providing long-range inhibition to ganglion cells due to its strong coupling.
authors.affiliation: Neurobiology, University of Oldenburg, 26111, Oldenburg, Germany.
authors.forename: Gabriel C
authors.initials: GC
authors.lastname: Knop
authors.forename: Mark
authors.initials: M
authors.lastname: Pottek
authors.forename: Hannah
authors.initials: H
authors.lastname: Monyer
authors.forename: Reto
authors.initials: R
authors.lastname: Weiler
authors.forename: Karin
authors.initials: K
authors.lastname: Dedek
mesh_terms: D025042:Amacrine Cells / Q000166:cytology* / Q000502:physiology*; D000818:Animals; D002460:Cell Line; D002795:Choline O-Acetyltransferase / Q000235:genetics; D059330:GABAergic Neurons; D049452:Green Fluorescent Proteins / Q000032:analysis; D007150:Immunohistochemistry; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D018408:Patch-Clamp Techniques
chemical_list: C485184:enhanced green fluorescent protein; D049452:Green Fluorescent Proteins; D002795:Choline O-Acetyltransferase
keywords: acetylcholine; amacrine cell; choline acetyltransferase; light response; retina