title: Morphological and physiological analysis of type-5 and other bipolar cells in the Mouse Retina.
abstract: Retinal bipolar cells are second-order neurons in the visual system, which initiate multiple image feature-based neural streams. Among more than ten types of bipolar cells, type-5 cells are thought to play a role in motion detection pathways. Multiple subsets of type-5 cells have been reported; however, detailed characteristics of each subset have not yet been elucidated. Here, we found that they exhibit distinct morphological features as well as unique voltage-gated channel expression. We have conducted electrophysiological and immunohistochemical analysis of retinal bipolar cells. We defined type-5 cells by their axon terminal ramification in the inner plexiform layer between the border of ON/OFF sublaminae and the ON choline acetyltransferase (ChAT) band. We found three subsets of type-5 cells: XBCs had the widest axon terminals that stratified at a close approximation of the ON ChAT band as well as exhibiting large voltage-gated Na(+) channel activity, type-5-1 cells had compact terminals and no Na(+) channel activity, and type-5-2 cells contained umbrella-shaped terminals as well as large voltage-gated Na(+) channel activity. Hyperpolarization-activated cyclic nucleotide-gated (HCN) currents were also evoked in all type-5 bipolar cells. We found that XBCs and type-5-2 cells exhibited larger HCN currents than type-5-1 cells. Furthermore, the former two types showed stronger HCN1 expression than the latter. Our previous observations (Ichinose et al., 2014) match the current study: low temporal tuning cells that we named 5S corresponded to 5-1 in this study, while high temporal tuning 5f cells from the previous study corresponded to 5-2 cells. Taken together, we found three subsets of type-5 bipolar cells based on their morphologies and physiological features.
authors.affiliation: Department of Anatomy and Cell Biology, Wayne State University School of Medicine, Detroit, MI 48201, United States.
authors.forename: C B
authors.initials: CB
authors.lastname: Hellmer
authors.affiliation: Department of Otolaryngology, Wayne State University School of Medicine, Detroit, MI 48201, United States.
authors.forename: Y
authors.initials: Y
authors.lastname: Zhou
authors.affiliation: Department of Anatomy and Cell Biology, Wayne State University School of Medicine, Detroit, MI 48201, United States.
authors.forename: B
authors.initials: B
authors.lastname: Fyk-Kolodziej
authors.affiliation: Department of Otolaryngology, Wayne State University School of Medicine, Detroit, MI 48201, United States.
authors.forename: Z
authors.initials: Z
authors.lastname: Hu
authors.affiliation: Department of Anatomy and Cell Biology, Wayne State University School of Medicine, Detroit, MI 48201, United States; Department of Ophthalmology, Wayne State University School of Medicine, Detroit, MI 48201, United States. Electronic address: tichinos@med.wayne.edu.
authors.forename: T
authors.initials: T
authors.lastname: Ichinose
mesh_terms: D000818:Animals; D001369:Axons / Q000187:drug effects / Q000502:physiology; D015153:Blotting, Western; D002795:Choline O-Acetyltransferase / Q000378:metabolism; D064428:Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels / Q000378:metabolism; D007150:Immunohistochemistry; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D008810:Mice, Inbred C57BL; D018408:Patch-Clamp Techniques; D015221:Potassium Channels / Q000378:metabolism; D051245:Retinal Bipolar Cells / Q000166:cytology* / Q000187:drug effects / Q000502:physiology*; D026941:Sodium Channel Blockers / Q000494:pharmacology; D015222:Sodium Channels / Q000378:metabolism; D013779:Tetrodotoxin / Q000494:pharmacology; D046509:Tissue Culture Techniques
chemical_list: C578666:Hcn1 protein, mouse; D064428:Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels; D015221:Potassium Channels; D026941:Sodium Channel Blockers; D015222:Sodium Channels; D013779:Tetrodotoxin; D002795:Choline O-Acetyltransferase
keywords: ChAT band; HCN1 channel; bipolar cells; patch clamp; voltage-gated Na(+) channel