Medullary regions mediating atonia.

TitleMedullary regions mediating atonia.
Publication TypeJournal Article
Year of Publication1988
AuthorsLai, YY, Siegel JM
JournalThe Journal of neuroscience : the official journal of the Society for Neuroscience
Volume8
Issue12
Pagination4790-6
Date Published1988 Dec
ISSN0270-6474
Keywordsacetylcholine, Animals, Carbachol, Cats, Dipeptides, Glutamates, Glutamic Acid, Medulla Oblongata, Muscle Tonus, pons, Receptors, Cell Surface
Abstract

Electrical stimulation studies have implicated the medial medulla in the inhibition of muscle tone. In the present report we present evidence for suppression of muscle tone by chemical activation of the medial medulla. We find 2 distinct zones within the classically defined medial medullary inhibitory area. A rostral region corresponding to the nucleus magnocellularis (NMC) is sensitive to glutamate. Atonia produced by activation of this region is mediated by non-NMDA receptors. A caudal region, corresponding to the nucleus paramedianus (NPM) is sensitive to ACh. Atonia produced by activation of this region is mediated by muscarinic receptors. Activation of these regions both in acute decerebrate and intact cats suppresses muscle tone. We find that the cholinoceptive dorsolateral pontine region, previously implicated in atonia control, can be activated by glutamate-sensitive non-NMDA receptors. Microinjection of atropine into the NPM or of glutamylglycine into the NMC blocks atonia elicited by pontine carbachol injection. The medullary regions identified here are hypothesized to mediate the suppression of muscle tone that occurs in rapid eye movement sleep and in cataplexy and may have a role in postural control in waking.

Alternate JournalJ. Neurosci.