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Expression of AMPA-glutamate Receptor B Subunit in Rat Hippocampal GABAergic Neurons

Authors

  • Claudia Racca,

    Corresponding author
    1. Abteilung Zellphysiologie, Max-Planck-Institut für medizinische Forschung
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      Laboratoire de Biologie Cellulaire de la Synapse (INSERM CJF 94-10), Ecole Normale Supérieure, 46, rue d'Ulm, F-75005 Paris, France

  • Maria Vincenza Catania,

    1. Zentrum für Molekulare Biologie Heidelberg Universität, D-69120 Heidelberg, Germany
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      CNR Istituto di Bioimmagine e Fisiopatologia del Sistema Nervoso Centrale, Piazza Roma 2, I-95123 Catania, Italy

  • Hannah Monyer,

    1. Zentrum für Molekulare Biologie Heidelberg Universität, D-69120 Heidelberg, Germany
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  • Bert Sakmann

    1. Abteilung Zellphysiologie, Max-Planck-Institut für medizinische Forschung
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Claudia Racca, Laboratoire de Biologie Cellulaire de la Synapse (INSERM CJF 94-10), Ecole Normale Supérieure, 46, rue d'Ulm, F-75005 Paris, France

Abstract

The physiological properties of α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA)-type glutamate receptor (GluR) channels are determined by their subunit composition. In particular, the expression of the GluR-B subunit determines the divalent ion selectivity of the channel. We studied the distribution of GluR-B mRNA and protein in adult rat hippocampal GABAergic neurons combining non-radioactive in situ hybridization with immunocytochemistry. The majority of GABAergic hippocampal neurons were GluR-B mRNA-positive, but overall the levels of GluR-B transcript were lower than in pyramidal and granule cells, which showed the highest hybridization signal. The different GluR-B mRNA expression levels in GABAergic versus principal neurons were also observed at the protein level. There was a paucity of GluR-B/C immunoreactivity in the vast majority of somata of the GABAergic neurons studied, which contrasted with the strong expression of GluR-B/C proteins in the hippocampal principal neurons. Our results demonstrate the general low expression of the GluR-B subunit mRNA and GluR-B/C proteins in GABAergic hippocampal neurons. Considering the dominant role of the GluR-B subunit in determining the divalent ion permeability of the receptor, it is likely that most GABAergic neurons express AMPA receptor channels with different calcium permeabilities.

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