title: Expression of AMPA-glutamate receptor B subunit in rat hippocampal GABAergic neurons.
abstract: The physiological properties of alpha-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.
authors.affiliation: Abteilung Zellphysiologie, Max-Planck-Institut für medizinische Forschung, Heidelberg Universität, Germany.
authors.forename: C
authors.initials: C
authors.lastname: Racca
authors.forename: M V
authors.initials: MV
authors.lastname: Catania
authors.forename: H
authors.initials: H
authors.lastname: Monyer
authors.forename: B
authors.initials: B
authors.lastname: Sakmann
mesh_terms: D000818:Animals; D005968:Glutamate Decarboxylase / Q000032:analysis / Q000235:genetics; D006624:Hippocampus / Q000737:chemistry* / Q000166:cytology; D007150:Immunohistochemistry; D007395:Interneurons / Q000737:chemistry*; D008297:Male; D009474:Neurons / Q000737:chemistry*; D010446:Peptide Fragments / Q000032:analysis*; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017207:Rats, Sprague-Dawley; D018091:Receptors, AMPA / Q000737:chemistry*; D005680:gamma-Aminobutyric Acid / Q000502:physiology*
chemical_list: D010446:Peptide Fragments; D012333:RNA, Messenger; D018091:Receptors, AMPA; D005680:gamma-Aminobutyric Acid; D005968:Glutamate Decarboxylase