Abstract
Synapses throughout the brain are modified through associative mechanisms in which one input provides an instructive signal for changes in the strength of a second coactivated input. In cerebellar Purkinje cells, climbing fiber synapses provide an instructive signal for plasticity at parallel fiber synapses. Here, we show that noradrenaline activates alpha2-adrenergic receptors to control short-term and long-term associative plasticity of parallel fiber synapses. This regulation of plasticity does not reflect a conventional direct modulation of the postsynaptic Purkinje cell or presynaptic parallel fibers. Instead, noradrenaline reduces associative plasticity by selectively decreasing the probability of release at the climbing fiber synapse, which in turn decreases climbing fiber-evoked dendritic calcium signals. These findings raise the possibility that targeted presynaptic modulation of instructive synapses could provide a general mechanism for dynamic context-dependent modulation of associative plasticity.
Publication types
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Research Support, N.I.H., Extramural
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Research Support, Non-U.S. Gov't
MeSH terms
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Adrenergic alpha-2 Receptor Agonists
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Adrenergic alpha-2 Receptor Antagonists
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Animals
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Animals, Newborn
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Biophysics
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Brimonidine Tartrate
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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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Cerebellum / cytology
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Electric Stimulation / methods
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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 Antagonists / pharmacology
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Glycine / analogs & derivatives
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Glycine / pharmacology
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In Vitro Techniques
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Long-Term Synaptic Depression / drug effects
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Long-Term Synaptic Depression / physiology
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Neural Pathways / drug effects
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Neural Pathways / physiology
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Neuronal Plasticity / drug effects
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Neuronal Plasticity / physiology*
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Norepinephrine / metabolism*
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Norepinephrine / pharmacology
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Patch-Clamp Techniques / methods
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Phosphinic Acids / pharmacology
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Piperidines / pharmacology
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Propanolamines / pharmacology
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Purinergic P1 Receptor Antagonists
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Purkinje Cells / drug effects
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Purkinje Cells / physiology*
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Pyrazoles / pharmacology
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Quinoxalines / pharmacology
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Rats
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Rats, Sprague-Dawley
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Receptors, Adrenergic, alpha-2 / physiology
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Synapses / drug effects
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Synapses / physiology*
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Xanthines / pharmacology
Substances
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Adrenergic alpha-2 Receptor Agonists
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Adrenergic alpha-2 Receptor Antagonists
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Excitatory Amino Acid Antagonists
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GABA Antagonists
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Phosphinic Acids
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Piperidines
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Propanolamines
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Purinergic P1 Receptor Antagonists
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Pyrazoles
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Quinoxalines
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Receptors, Adrenergic, alpha-2
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Xanthines
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methyl-(4-carboxyphenyl)glycine
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CGP 55845A
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AM 251
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Brimonidine Tartrate
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1,3-dipropyl-8-cyclopentylxanthine
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Calcium
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Glycine
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Norepinephrine