Abstract
GABA(A) receptors can mediate both 'phasic' synaptic inhibition and a persistent 'tonic' form of signaling. We show that, in the presence of intact GABA uptake, guinea pig hippocampal interneurons, but not pyramidal cells, express a tonic GABA(A) receptor-mediated conductance. This conductance was pharmacologically distinct from spontaneous inhibitory postsynaptic currents (IPSCs). Inhibiting GABA uptake resulted in the expression of a comparable GABA(A) receptor-mediated tonic conductance in pyramidal cells. Reducing the tonic conductance in interneurons enhanced their excitability and the inhibitory drive to pyramidal cells. These results point to a role for cell type-dependent tonic inhibition in regulating cortical excitability.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Animals
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GABA Antagonists / metabolism
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GABA Antagonists / pharmacology
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GABA-A Receptor Agonists
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GABA-A Receptor Antagonists
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Guinea Pigs
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Hippocampus / cytology
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Hippocampus / drug effects
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Hippocampus / metabolism
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Interneurons / drug effects
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Interneurons / metabolism*
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Neural Inhibition / drug effects
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Neural Inhibition / physiology*
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Pyramidal Cells / drug effects
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Pyramidal Cells / metabolism*
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Receptors, GABA-A / metabolism*
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Synaptic Transmission / drug effects
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Synaptic Transmission / physiology
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gamma-Aminobutyric Acid / metabolism*
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gamma-Aminobutyric Acid / physiology
Substances
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GABA Antagonists
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GABA-A Receptor Agonists
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GABA-A Receptor Antagonists
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Receptors, GABA-A
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gamma-Aminobutyric Acid