Abstract
In rat brainstem slice preparations, intracellular recording from neurons (n = 39) in the compact formation of the nucleus ambiguus (AMBc) revealed spontaneous and miniature excitatory postsynaptic potentials (EPSPs; n = 11) that, along with acetylcholine-induced depolarization, were enhanced by physostigmine (10 microM; n = 2) and blocked by dihydro-beta-erythroidine 1-5 pmol (n = 4). Retrograde neuronal tracing combined with choline acetyltransferase immunocytochemistry demonstrated that the AMBc receives a projection from a subpopulation of cholinergic neurons in the zona intermedialis reticularis parvicellularis. Electrical stimulation of this region in slices evoked fast EPSPs in AMBc neurons (n = 23) that were inhibited by dihydro-beta-erythroidine 2-5 pmol (n = 8), but not by methscopolamine 1 pmol (n = 2). The present findings strongly support the existence of a cholinergic nicotinic synapse mediating fast transmission in brainstem vagal motoneurons.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Acetylcholine / pharmacology
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Animals
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Brain Stem / cytology
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Brain Stem / physiology
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Choline O-Acetyltransferase / immunology
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Choline O-Acetyltransferase / metabolism
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Dihydro-beta-Erythroidine / pharmacology
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Electric Stimulation
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Evoked Potentials / drug effects
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Immunohistochemistry
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In Vitro Techniques
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Iontophoresis
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Male
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Medulla Oblongata / cytology
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Medulla Oblongata / drug effects
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Medulla Oblongata / physiology*
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Motor Neurons / drug effects
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N-Methylscopolamine
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Neurons / enzymology
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Neurons / physiology
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Parasympatholytics / pharmacology
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Physostigmine / pharmacology
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Rats
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Rats, Sprague-Dawley
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Receptors, Nicotinic / drug effects
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Receptors, Nicotinic / physiology*
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Reticular Formation / drug effects
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Reticular Formation / physiology
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Scopolamine Derivatives / pharmacology
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Synapses / drug effects*
Substances
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Parasympatholytics
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Receptors, Nicotinic
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Scopolamine Derivatives
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Dihydro-beta-Erythroidine
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Physostigmine
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Choline O-Acetyltransferase
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Acetylcholine
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N-Methylscopolamine