Abstract
Metabotropic glutamate receptors (mGluRs) regulate transmitter release at mammalian central synapses. However, because of the difficulty of recording from mammalian presynaptic terminals, the mechanism underlying mGluR-mediated presynaptic inhibition is not known. Here, simultaneous recordings from a giant presynaptic terminal, the calyx of Held, and its postsynaptic target in the medial nucleus of the trapezoid body were obtained in rat brainstem slices. Agonists of mGluRs suppressed a high voltage-activated P/Q-type calcium conductance in the presynaptic terminal, thereby inhibiting transmitter release at this glutamatergic synapse. Because several forms of presynaptic modulation and plasticity are mediated by mGluRs, this identification of a target ion channel is a first step toward elucidation of their molecular mechanism.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Aminobutyrates / pharmacology
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Animals
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Brain Stem
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Cadmium / pharmacology
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Calcium / metabolism*
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Calcium Channel Blockers / pharmacology
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Calcium Channels / drug effects
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Calcium Channels / metabolism*
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Excitatory Amino Acid Agonists / pharmacology
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In Vitro Techniques
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Neurotransmitter Agents / metabolism
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Patch-Clamp Techniques
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Potassium / metabolism
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Potassium Channels / drug effects
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Potassium Channels / metabolism
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Presynaptic Terminals / metabolism*
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Rats
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Rats, Wistar
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Receptors, Metabotropic Glutamate / agonists
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Receptors, Metabotropic Glutamate / metabolism*
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Synapses / metabolism*
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Synaptic Transmission*
Substances
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Aminobutyrates
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Calcium Channel Blockers
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Calcium Channels
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Excitatory Amino Acid Agonists
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Neurotransmitter Agents
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Potassium Channels
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Receptors, Metabotropic Glutamate
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Cadmium
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2-amino-4-phosphonobutyric acid
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Potassium
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Calcium