Abstract
In the mammalian olfactory bulb, signal processing is mediated by synaptic interactions between dendrites. Glutamate released from mitral cell dendrites excites dendritic spines of granule cells, which in turn release GABA back onto the mitral cell dendrites, forming a reciprocal synaptic pair. This feedback synaptic circuit was shown to be mediated predominantly by NMDA receptors. We further utilized caged Ca2+ compounds to obtain insight into the mechanism that couples NMDA receptor activation to GABA release. Feedback inhibition elicited by photo-release of caged Ca2+ in mitral cell secondary dendrites persisted when voltage-gated Ca2+ channels were blocked by cadmium (Cd2+) and nickel (Ni2+). These results indicate that Ca2+ influx through NMDA receptors can directly trigger presynaptic GABA release for local dendrodendritic feedback inhibition.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, Non-P.H.S.
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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2-Amino-5-phosphonovalerate / pharmacology
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6-Cyano-7-nitroquinoxaline-2,3-dione / pharmacology
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Acetates / pharmacology
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Animals
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Cadmium / pharmacology
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Calcium / metabolism
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Calcium Channels / physiology
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Chelating Agents / pharmacology
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Dendrites / chemistry
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Dendrites / metabolism
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Enzyme Inhibitors / pharmacology
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Ethylenediamines / pharmacology
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Excitatory Amino Acid Agonists / pharmacology
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Excitatory Amino Acid Antagonists / pharmacology
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Excitatory Postsynaptic Potentials / drug effects
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Excitatory Postsynaptic Potentials / physiology
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Feedback / physiology
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Membrane Potentials / drug effects
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Membrane Potentials / physiology
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Neural Inhibition / physiology
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Neurotransmitter Agents / metabolism
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Nickel / pharmacology
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Olfactory Bulb / cytology
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Olfactory Bulb / metabolism*
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Rats
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Rats, Sprague-Dawley
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Receptors, N-Methyl-D-Aspartate / metabolism*
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Signal Transduction / drug effects
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Signal Transduction / physiology
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Synapses / metabolism*
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Thapsigargin / pharmacology
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gamma-Aminobutyric Acid / metabolism*
Substances
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Acetates
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Calcium Channels
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Chelating Agents
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Enzyme Inhibitors
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Ethylenediamines
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Excitatory Amino Acid Agonists
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Excitatory Amino Acid Antagonists
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Neurotransmitter Agents
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Receptors, N-Methyl-D-Aspartate
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Cadmium
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DM-nitrophen
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gamma-Aminobutyric Acid
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Thapsigargin
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6-Cyano-7-nitroquinoxaline-2,3-dione
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2-Amino-5-phosphonovalerate
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Nickel
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Calcium