Abstract
Metabotropic gamma-aminobutyric acid type B (GABAB) and glutamate receptors (mGluRs) are postsynaptically co-expressed at cerebellar parallel fiber (PF)-Purkinje cell (PC) excitatory synapses, but their functional interactions are unclear. We found that mGluR1 agonist-induced currents and [Ca2+]i increases in PCs were enhanced following co-activation of GABAB receptors. A GABAB antagonist and a G-protein uncoupler suppressed these effects. Low-concentration baclofen, a GABAB agonist, augmented mGluR1-mediated excitatory synaptic current produced by stimulating PFs. These results indicate that postsynaptic GABAB receptors functionally interact with mGluR1 and enhance mGluR1-mediated excitatory transmission at PF-PC synapses. The interaction between the two types of metabotropic receptors provides a likely mechanism for regulating cerebellar synaptic plasticity.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Animals
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Calcium / metabolism
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Calcium Signaling / drug effects
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Calcium Signaling / physiology
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Dendrites / drug effects
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Dendrites / metabolism*
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Dose-Response Relationship, Drug
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Electric Stimulation
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Enzyme Inhibitors / 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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GABA Agonists / pharmacology
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GABA Antagonists / pharmacology
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GABA-B Receptor Agonists
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GABA-B Receptor Antagonists
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GTP-Binding Proteins / antagonists & inhibitors
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GTP-Binding Proteins / metabolism
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Glutamic Acid / metabolism
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Mice
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Neural Inhibition / drug effects
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Neural Inhibition / physiology
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Neuronal Plasticity / drug effects
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Neuronal Plasticity / physiology
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Presynaptic Terminals / drug effects
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Presynaptic Terminals / metabolism*
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Purkinje Cells / drug effects
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Purkinje Cells / metabolism*
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Receptors, GABA-B / metabolism*
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Receptors, Metabotropic Glutamate / drug effects
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Receptors, Metabotropic Glutamate / metabolism*
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Synaptic Transmission / physiology*
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gamma-Aminobutyric Acid / metabolism
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gamma-Aminobutyric Acid / pharmacology
Substances
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Enzyme Inhibitors
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Excitatory Amino Acid Agonists
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Excitatory Amino Acid Antagonists
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GABA Agonists
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GABA Antagonists
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GABA-B Receptor Agonists
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GABA-B Receptor Antagonists
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Receptors, GABA-B
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Receptors, Metabotropic Glutamate
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metabotropic glutamate receptor type 1
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Glutamic Acid
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gamma-Aminobutyric Acid
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GTP-Binding Proteins
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Calcium