title: Bipolar cell gap junctions serve major signaling pathways in the human retina.
abstract: Connexin36 (Cx36) constituent gap junctions (GJ) throughout the brain connect neurons into functional syncytia. In the retina they underlie the transmission, averaging and correlation of signals prior conveying visual information to the brain. This is the first study that describes retinal bipolar cell (BC) GJs in the human inner retina, whose function is enigmatic even in the examined animal models. Furthermore, a number of unique features (e.g. fovea, trichromacy, midget system) necessitate a reexamination of the animal model results in the human retina. Well-preserved postmortem human samples of this study are allowed to identify Cx36 expressing BCs neurochemically. Results reveal that both rod and cone pathway interneurons display strong Cx36 expression. Rod BC inputs to AII amacrine cells (AC) appear in juxtaposition to AII GJs, thus suggesting a strategic AII cell targeting by rod BCs. Cone BCs serving midget, parasol or koniocellular signaling pathways display a wealth of Cx36 expression to form homologously coupled arrays. In addition, they also establish heterologous GJ contacts to serve an exchange of information between parallel signaling streams. Interestingly, a prominent Cx36 expression was exhibited by midget system BCs that appear to maintain intimate contacts with bistratified BCs serving other pathways. These findings suggest that BC GJs in parallel signaling streams serve both an intra- and inter-pathway exchange of signals in the human retina.
authors.affiliation: Department of Neuroanatomy, Faculty of Medicine, Institute for Anatomy and Cell Biology, University of Freiburg, 79104, Freiburg, Germany.|MTA-PTE NAP B Retinal Electrical Synapses Research Group, Pécs, 7624, Hungary.|Department of Anatomy, Histology and Embryology, Semmelweis University, Budapest, 1094, Hungary.
authors.forename: Orsolya
authors.initials: O
authors.lastname: Kántor
authors.affiliation: Department of Anatomy, Histology and Embryology, Semmelweis University, Budapest, 1094, Hungary.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Varga
authors.affiliation: Life Imaging Center, Center for Biological Systems Analysis, University of Freiburg, 79104, Freiburg, Germany.|BIOSS Centre for Biological Signaling Studies, University of Freiburg, 79104, Freiburg, Germany.
authors.forename: Roland
authors.initials: R
authors.lastname: Nitschke
authors.affiliation: Life Imaging Center, Center for Biological Systems Analysis, University of Freiburg, 79104, Freiburg, Germany.|BIOSS Centre for Biological Signaling Studies, University of Freiburg, 79104, Freiburg, Germany.
authors.forename: Angela
authors.initials: A
authors.lastname: Naumann
authors.affiliation: Department of Anatomy, Histology and Embryology, Semmelweis University, Budapest, 1094, Hungary.|Department of Ophthalmology, Semmelweis University, Budapest, 1085, Hungary.
authors.forename: Anna
authors.initials: A
authors.lastname: Énzsöly
authors.affiliation: Department of Anatomy, Histology and Embryology, Semmelweis University, Budapest, 1094, Hungary.
authors.forename: Ákos
authors.initials: Á
authors.lastname: Lukáts
authors.affiliation: Department of Anatomy, Histology and Embryology, Semmelweis University, Budapest, 1094, Hungary.
authors.forename: Arnold
authors.initials: A
authors.lastname: Szabó
authors.affiliation: Department of Ophthalmology, Semmelweis University, Budapest, 1085, Hungary.
authors.forename: János
authors.initials: J
authors.lastname: Németh
authors.affiliation: MTA-PTE NAP B Retinal Electrical Synapses Research Group, Pécs, 7624, Hungary. volgyi01@gamma.ttk.pte.hu.|Department of Experimental Zoology and Neurobiology, University of Pécs, Pécs, 7624, Hungary. volgyi01@gamma.ttk.pte.hu.|János Szentágothai Research Center, University of Pécs, Ifjúság street 20, Pécs, 7624, Hungary. volgyi01@gamma.ttk.pte.hu.|Department of Ophthalmology, New York University Langone Medical Center, New York, NY, 10016, USA. volgyi01@gamma.ttk.pte.hu.
authors.forename: Béla
authors.initials: B
authors.lastname: Völgyi
mesh_terms: D000328:Adult; D017630:Connexins / Q000032:analysis; D054351:Electrical Synapses; D005260:Female; D017629:Gap Junctions / Q000737:chemistry / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009434:Neural Pathways / Q000737:chemistry / Q000502:physiology; D010641:Phenotype; D051245:Retinal Bipolar Cells / Q000737:chemistry / Q000502:physiology*; D017949:Retinal Cone Photoreceptor Cells / Q000737:chemistry / Q000502:physiology*; D009435:Synaptic Transmission; D000097004:Gap Junction delta-2 Protein
chemical_list: D017630:Connexins; D000097004:Gap Junction delta-2 Protein
keywords: Bipolar cell; Electrical synapse; Gap junction; Koniocellular pathway; Magnocellular pathway; Parvocellular pathway