Morphological and physiological analysis of type-5 and other bipolar cells in the Mouse Retina.
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.
['Hellmer|C B|CB|', 'Zhou|Y|Y|', 'Fyk-Kolodziej|B|B|', 'Hu|Z|Z|', 'Ichinose|T|T|']
D000818:Animals D001369:Axons D015153:Blotting, Western D002795:Choline O-Acetyltransferase D064428:Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels D007150:Immunohistochemistry D008297:Male D008564:Membrane Potentials D008810:Mice, Inbred C57BL D018408:Patch-Clamp Techniques D015221:Potassium Channels D051245:Retinal Bipolar Cells D026941:Sodium Channel Blockers D015222:Sodium Channels D013779:Tetrodotoxin D046509:Tissue Culture Techniques
bipolar cells ChAT band voltage-gated Na(+) channel HCN1 channel patch clamp