Abstract
We examined the effects of carbachol, a muscarinic acetylcholine receptor agonist, on excitatory synaptic transmission at thalamo-amygdala synapses in rat brain slices. The application of a low concentration of carbachol (0.25 microM) produced a form of long-term potentiation (cLTP) and a transient suppression of synaptic responses, which was blocked by a muscarinic receptor antagonist, atropine (10 microM). M2 receptor agonist produced only a transient suppression, whereas M1 receptor agonist induced both a transient suppression and a long-term potentiation. Induction of cLTP required simultaneous low-frequency afferent stimulation, and was also dependent upon the activation of NMDA receptors. SQ22536 (50 microM), an adenylyl cyclase inhibitor completely blocked cLTP. Consistently, pretreatment with a maximal concentration of forskolin (10 microM) reduced cLTP.
Copyright 2004 Lippincott Williams and Wilkins
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Acetylcholine / metabolism*
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Adenylyl Cyclase Inhibitors
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Adenylyl Cyclases / metabolism
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Afferent Pathways / physiology
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Amygdala / cytology
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Amygdala / drug effects*
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Amygdala / metabolism
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Animals
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Atropine / pharmacology
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Carbachol / pharmacology*
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Cholinergic Agonists / pharmacology
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Colforsin / pharmacology
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Dose-Response Relationship, Drug
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Enzyme Inhibitors / pharmacology
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In Vitro Techniques
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Long-Term Potentiation / drug effects*
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Long-Term Potentiation / physiology
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Muscarinic Antagonists / pharmacology
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Neurons / drug effects*
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Neurons / metabolism
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Rats
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Rats, Sprague-Dawley
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Receptors, N-Methyl-D-Aspartate / agonists
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Receptors, N-Methyl-D-Aspartate / metabolism
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Synaptic Transmission / drug effects*
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Synaptic Transmission / physiology
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Thalamus / physiology
Substances
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Adenylyl Cyclase Inhibitors
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Cholinergic Agonists
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Enzyme Inhibitors
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Muscarinic Antagonists
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Receptors, N-Methyl-D-Aspartate
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Colforsin
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Atropine
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Carbachol
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Adenylyl Cyclases
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Acetylcholine