title: Analysis of ion channel expression by astrocytes in red nucleus brain stem slices of the rat.
abstract: The red nucleus (RN) has been widely used to study the formation and remodeling of synaptic connections during development and in post-lesion plasticity. Since glial cells are thought to contribute to synaptic plasticity, and information on functional properties of brain stem glia is missing, we analyzed voltage-gated ion channels as well as glutamate receptors expressed by glial cells of the RN. The patch-clamp technique was applied to identified cells in acute brain stem slices of 5- to 12-days-old rats. Based on their pattern of membrane currents, two types of glial cells could be distinguished. A first type was characterized by passive, symmetrical currents. The second population of cells, which was the focus of the present study, expressed a complex pattern of voltage-gated channels. These cells could be labeled with antibodies against glutamine synthetase and S100 beta, suggesting an astroglial origin. Depolarizing voltage steps activated transient and delayed rectifier K+ currents as well as Na+ currents. In addition, a subset of cells expressed Ba2+ sensitive inward rectifier K+ currents activated by hyperpolarization. All "complex" glial cells analyzed possessed ionotropic glutamate receptors of the alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) subtype, while functional kainate and N-methyl-D-aspartate (NMDA) receptors could not be detected. Receptor activation blocked outward rectifying K+ currents, similar to previous observations in glial cells of the hippocampus and the corpus callosum.
authors.affiliation: Department of Neurophysiology Friedrich-Schiller University Jena, Germany.
authors.forename: G
authors.initials: G
authors.lastname: Akopian
authors.forename: E
authors.initials: E
authors.lastname: Kuprijanova
authors.forename: K
authors.initials: K
authors.lastname: Kressin
authors.forename: C
authors.initials: C
authors.lastname: Steinhüser
mesh_terms: D000818:Animals; D001253:Astrocytes / Q000166:cytology / Q000502:physiology*; D001933:Brain Stem / Q000166:cytology / Q000502:physiology*; D004553:Electric Conductivity; D005260:Female; D015640:Ion Channel Gating; D007473:Ion Channels / Q000502:physiology*; D009457:Neuroglia / Q000166:cytology / Q000502:physiology; D011188:Potassium / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D017470:Receptors, Glutamate / Q000502:physiology; D012012:Red Nucleus / Q000502:physiology*; D012964:Sodium / Q000502:physiology; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid
chemical_list: D007473:Ion Channels; D017470:Receptors, Glutamate; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid; D012964:Sodium; D011188:Potassium