Abstract
We have used the synapses that isolated hippocampal cells in culture form onto themselves (autapses) to determine if some synapses lack functional AMPA receptors (AMPARs). A comparison of the synaptic variability of the AMPAR- and NMDAR-mediated evoked responses, as well as of miniature synaptic responses, indicates that a population of events exists that only contains an NMDAR component. Spillover of glutamate from adjacent synapses cannot explain these results because in single cell cultures all synaptic events mediated by AMPARs should be detected. Immunocytochemical analysis of these cultures clearly reveals a population of synapses with puncta for NR1 (NMDAR) but not for GluR1 (AMPAR). These results provide strong anatomical and physiological evidence for the existence of postsynaptically silent synapses.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Animals
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Animals, Newborn
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Cells, Cultured
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Evoked Potentials / drug effects
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Evoked Potentials / physiology*
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Excitatory Amino Acid Antagonists / pharmacology
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Hippocampus / cytology
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Hippocampus / physiology*
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Neurons / cytology
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Neurons / drug effects
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Neurons / physiology*
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Patch-Clamp Techniques
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Quinoxalines / pharmacology
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Rats
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Rats, Sprague-Dawley
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Receptors, AMPA / drug effects
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Receptors, AMPA / physiology*
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Receptors, N-Methyl-D-Aspartate / drug effects
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Receptors, N-Methyl-D-Aspartate / physiology*
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Synapses / drug effects
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Synapses / physiology*
Substances
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Excitatory Amino Acid Antagonists
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Quinoxalines
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Receptors, AMPA
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Receptors, N-Methyl-D-Aspartate
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2,3-dioxo-6-nitro-7-sulfamoylbenzo(f)quinoxaline
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glutamate receptor ionotropic, AMPA 1