title: GABA(B) receptor activation enhances mGluR-mediated responses at cerebellar excitatory synapses.
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.
authors.affiliation: Department of Molecular Neurobiology, Advanced Research Institute for Science and Engineering, Waseda University, Tokyo 169-8555, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Hirono
authors.forename: T
authors.initials: T
authors.lastname: Yoshioka
authors.forename: S
authors.initials: S
authors.lastname: Konishi
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology; D003712:Dendrites / Q000187:drug effects / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004558:Electric Stimulation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects / Q000502:physiology*; D018755:GABA Agonists / Q000494:pharmacology; D018756:GABA Antagonists / Q000494:pharmacology; D058786:GABA-B Receptor Agonists; D058788:GABA-B Receptor Antagonists; D019204:GTP-Binding Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D018698:Glutamic Acid / Q000378:metabolism; D051379:Mice; D009433:Neural Inhibition / Q000187:drug effects / Q000502:physiology; D009473:Neuronal Plasticity / Q000187:drug effects / Q000502:physiology; D017729:Presynaptic Terminals / Q000187:drug effects / Q000378:metabolism*; D011689:Purkinje Cells / Q000187:drug effects / Q000378:metabolism*; D018080:Receptors, GABA-B / Q000378:metabolism*; D018094:Receptors, Metabotropic Glutamate / Q000187:drug effects / Q000378:metabolism*; D009435:Synaptic Transmission / Q000502:physiology*; D005680:gamma-Aminobutyric Acid / Q000378:metabolism / Q000494:pharmacology
chemical_list: D004791:Enzyme Inhibitors; D018690:Excitatory Amino Acid Agonists; D018691:Excitatory Amino Acid Antagonists; D018755:GABA Agonists; D018756:GABA Antagonists; D058786:GABA-B Receptor Agonists; D058788:GABA-B Receptor Antagonists; D018080:Receptors, GABA-B; D018094:Receptors, Metabotropic Glutamate; C104077:metabotropic glutamate receptor type 1; D018698:Glutamic Acid; D005680:gamma-Aminobutyric Acid; D019204:GTP-Binding Proteins; D002118:Calcium