title: Functional anisotropic panglial networks in the lateral superior olive.
abstract: Astrocytes form large gap junctional networks that contribute to ion and neurotransmitter homeostasis. Astrocytes concentrate in the lateral superior olive (LSO), a prominent auditory brainstem center. Compared to the LSO, astrocyte density is lower in the region dorsal to the LSO (dLSO) and in the internuclear space between the LSO, the superior paraolivary nucleus (SPN). We questioned whether astrocyte networks exhibit certain properties that reflect the precise neuronal arrangement. Employing whole-cell patch-clamp and concomitant injection of a gap junction-permeable tracer, we analyzed size and orientation of astrocyte networks in LSO, dLSO, and SPN-LSO in acute brainstem slices of mice at postnatal days 10-20. The majority of LSO networks exhibited an oval topography oriented orthogonally to the tonotopic axis, whereas dLSO networks showed no preferred orientation. This correlated with the overall astrocyte morphology in both regions, i.e. LSO astrocyte processes were oriented mainly orthogonally to the tonotopic axis. To assess the spread of small ions within LSO networks, we analyzed the diffusion of Na(+) signals between cells using Na(+) imaging. We found that Na(+) not only diffused between SR101(+) astrocytes, but also from astrocytes into SR101(-) cells. Using PLP-GFP mice for tracing, we could show that LSO networks contained astrocytes and oligodendrocytes. Together, our results demonstrate that LSO astrocytes and LSO oligodendrocytes form functional anisotropic panglial networks that are oriented predominantly orthogonally to the tonotopic axis. Thus, our results point toward an anisotropic ion and metabolite diffusion and a limited glial crosstalk between neighboring isofrequency bands in the LSO. GLIA 2016;64:1892-1911.
authors.affiliation: Department of Biology, Animal Physiology Group, University of Kaiserslautern, Erwin Schroedinger-Strasse 13, Kaiserslautern, Germany.
authors.forename: Vanessa
authors.initials: V
authors.lastname: Augustin
authors.affiliation: Department of Biology, Animal Physiology Group, University of Kaiserslautern, Erwin Schroedinger-Strasse 13, Kaiserslautern, Germany.
authors.forename: Charlotte
authors.initials: C
authors.lastname: Bold
authors.affiliation: Department of Biology, Animal Physiology Group, University of Kaiserslautern, Erwin Schroedinger-Strasse 13, Kaiserslautern, Germany.
authors.forename: Simon L
authors.initials: SL
authors.lastname: Wadle
authors.affiliation: Institute of Neurobiology, Universitaetsstasse 1, Heinrich Heine University Duesseldorf, Duesseldorf, Germany.
authors.forename: Julia
authors.initials: J
authors.lastname: Langer
authors.affiliation: Medical Faculty, Institute of Cellular Neurosciences, University of Bonn, Sigmund-Freud-Strasse 25, Bonn, Germany.
authors.forename: Ronald
authors.initials: R
authors.lastname: Jabs
authors.affiliation: Medical Faculty, Institute of Cellular Neurosciences, University of Bonn, Sigmund-Freud-Strasse 25, Bonn, Germany.
authors.forename: Camille
authors.initials: C
authors.lastname: Philippot
authors.affiliation: Department of Biology, Animal Physiology Group, University of Kaiserslautern, Erwin Schroedinger-Strasse 13, Kaiserslautern, Germany.
authors.forename: Dennis J
authors.initials: DJ
authors.lastname: Weingarten
authors.affiliation: Institute of Neurobiology, Universitaetsstasse 1, Heinrich Heine University Duesseldorf, Duesseldorf, Germany.
authors.forename: Christine R
authors.initials: CR
authors.lastname: Rose
authors.affiliation: Medical Faculty, Institute of Cellular Neurosciences, University of Bonn, Sigmund-Freud-Strasse 25, Bonn, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Steinhäuser
authors.affiliation: Department of Biology, Animal Physiology Group, University of Kaiserslautern, Erwin Schroedinger-Strasse 13, Kaiserslautern, Germany. jonathan.stephan@bio.uni-kl.de.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Stephan
mesh_terms: D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D000831:Animals, Newborn; D001253:Astrocytes / Q000166:cytology / Q000378:metabolism / Q000502:physiology*; D001710:Biotin / Q000031:analogs & derivatives / Q000378:metabolism; D000075302:Connexin 30 / Q000378:metabolism; D018031:Connexin 43 / Q000378:metabolism; D005260:Female; D017629:Gap Junctions / Q000502:physiology; D018507:Gene Expression Regulation, Developmental; D050487:Glycine Plasma Membrane Transport Proteins / Q000378:metabolism; D006624:Hippocampus / Q000166:cytology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D018991:Myelin Proteolipid Protein / Q000235:genetics / Q000378:metabolism; D009415:Nerve Net / Q000166:cytology / Q000502:physiology*; D009836:Oligodendroglia / Q000502:physiology; D012964:Sodium / Q000378:metabolism; D065832:Superior Olivary Complex / Q000166:cytology*
chemical_list: D000075302:Connexin 30; D018031:Connexin 43; C100629:Gjb6 protein, mouse; D050487:Glycine Plasma Membrane Transport Proteins; D018991:Myelin Proteolipid Protein; C047516:Plp1 protein, mouse; C070614:neurobiotin; D001710:Biotin; D012964:Sodium
keywords: LSO; astrocytes; auditory brainstem; gap junctions; oligodendrocytes