Document Detail

Rhythmical oral-motor activity recorded in an in vitro brainstem preparation.
MedLine Citation:
PMID:  8725647     Owner:  NLM     Status:  MEDLINE    
The present study employed the neonatal rat isolated brainstem preparation to determine whether oral-motor rhythmical activity, a substrate for the complex behaviors of suckling and chewing, could be elicited in vitro by path application of excitatory amino acids (EAAs). Bath application of EAA agonists (kainate [KA], [+/-]-a-amino-3-hydroxy-5-methylisoxazole-4-propionic acid [AMPA], N-methyl-D, L-aspartate [NMA]), in conjunction with the gamma-aminobutyric acid antagonist bicuculline, either failed to induce rhythmic activity (n = 17 preparations) or induced a low-amplitude, low-frequency burst discharge (< 1 Hz, n = 10 preparations) from the motor branches of the trigeminal nerves when the brainstem was contiguous from the spinomedullary junction to the superior colliculus. Burst activity was in most cases bilaterally synchronous. However, when a discrete coronal transection was made at the level of the facial colliculus, between the trigeminal and facial motor nuclei, the rhythmic bursts produced by the resultant 3- to 5-mm block of tissue following bath application of EAA agonists increased in amplitude and frequency (4-8 Hz, n = 35). Application of 6-cyano-7-nitroquinoxaline-2, 3-dione (CNQX), a non-N-methyl-D-aspartate (non-NMDA) receptor antagonist, blocked the rhythm induced by non-NMDA receptor agonist (n = 4) but was less effective in suppressing NMA-induced rhythmicity. In contrast, D, L-2-amino-5-phosphonovaleric acid (APV) blocked by both NMA-induced (n = 5) and, in most cases, KA-induced (n = 5) rhythmicity, suggesting an essential role for NMA receptors in production of EAA-induced rhythmical oral-motor activity in the neonatal rat. The present data demonstrate that a narrow, bilaterally distributed region of brainstem surrounding the trigeminal motor nucleus contains sufficient neuronal circuitry for the production of oral-motor rhythmogenesis.
M Kogo; G D Funk; S H Chandler
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Publication Detail:
Type:  In Vitro; Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Somatosensory & motor research     Volume:  13     ISSN:  0899-0220     ISO Abbreviation:  Somatosens Mot Res     Publication Date:  1996  
Date Detail:
Created Date:  1996-11-06     Completed Date:  1996-11-06     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  8904127     Medline TA:  Somatosens Mot Res     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  39-48     Citation Subset:  IM    
Department of Physiological Science, University of California at Los Angeles 90095, USA.
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MeSH Terms
Animals, Newborn
Brain Mapping
Brain Stem / physiology*
Excitatory Amino Acids / physiology*
Mastication / physiology*
Masticatory Muscles / innervation
Motor Neurons / physiology
Receptors, N-Methyl-D-Aspartate / physiology
Spinal Cord / physiology
Sucking Behavior / physiology*
Trigeminal Nuclei / physiology
Grant Support
Reg. No./Substance:
0/Excitatory Amino Acids; 0/Receptors, N-Methyl-D-Aspartate

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