Document Detail

Presynaptic GABAergic control of the locomotor drive in the isolated spinal cord of neonatal rats.
MedLine Citation:
PMID:  10051758     Owner:  NLM     Status:  MEDLINE    
The in vitro newborn rat isolated brain stem/spinal cord preparation was used to study the involvement of presynaptic inhibition in the control of the synaptic locomotor drive. The recording chamber was partitioned with Vaseline walls to separate the L1-L2 locomotor network from the motoneurons in the lower segments. When locomotor like activity was induced by bath applying a mixture of N-methyl-D-L-aspartate and serotonin to the L1-L2 segments, intracellular recordings of L3-L5 motoneurons show an alternating pattern of monosynaptic excitatory glutamatergic and inhibitory glycinergic inputs known as the locomotor drive. Gamma-aminobutyric acid (GABA), baclofen and muscimol (respectively GABA(B) and GABA(A) agonists) superfused on the L3-L5 segments depressed the synaptic locomotor drive of motoneurons during the ongoing activity. On the contrary, the GABA(B) receptor antagonist CGP35348 enhanced the locomotor drive, which suggests that an endogenous release of GABA occurs during locomotor-like activity. Baclofen, unlike muscimol and GABA, did not affect the passive membrane properties and the firing discharge of synaptically isolated motoneurons. Baclofen and muscimol acted on the two phases (inhibitory and excitatory) of the synaptic drive. The effects of GABAergic agonists on the whole locomotor activity were tested. When superfused on the L3-L5 part of the cord, they affected only the L5 burst amplitude. When bath-applied to the L1-L2 network, GABA and muscimol decreased the amplitude of the L2 and L5 bursts and increased the locomotor period while baclofen had significant effects only on the period. It was concluded that GABA modulates the information conveyed by the L1-L2 network to its target motoneurons presynaptically via GABA(B) and possibly GABA(A) receptors and postsynaptically, via GABA(A) receptors.
S Bertrand; J R Cazalets
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  The European journal of neuroscience     Volume:  11     ISSN:  0953-816X     ISO Abbreviation:  Eur. J. Neurosci.     Publication Date:  1999 Feb 
Date Detail:
Created Date:  1999-04-21     Completed Date:  1999-04-21     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  8918110     Medline TA:  Eur J Neurosci     Country:  FRANCE    
Other Details:
Languages:  eng     Pagination:  583-92     Citation Subset:  IM    
CNRS Laboratoire de Neurobiologie et Mouvements, Marseille, France.
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MeSH Terms
Animals, Newborn
Baclofen / pharmacology
Excitatory Amino Acid Agonists / pharmacology
Free Radical Scavengers / pharmacology
GABA Agonists / pharmacology
GABA Antagonists / pharmacology
Locomotion / physiology*
Membrane Potentials / drug effects,  physiology
Mephenesin / pharmacology
Muscimol / pharmacology
Muscle Relaxants, Central / pharmacology
N-Methylaspartate / pharmacology
Neural Inhibition / drug effects,  physiology
Organophosphorus Compounds / pharmacology
Presynaptic Terminals / drug effects,  physiology
Rats, Wistar
Receptors, GABA-A / physiology
Receptors, GABA-B / physiology
Serotonin / pharmacology
Spinal Cord / chemistry,  physiology*
Tetrodotoxin / pharmacology
gamma-Aminobutyric Acid / pharmacology,  physiology*
Reg. No./Substance:
0/Excitatory Amino Acid Agonists; 0/Free Radical Scavengers; 0/GABA Agonists; 0/GABA Antagonists; 0/Muscle Relaxants, Central; 0/Organophosphorus Compounds; 0/Receptors, GABA-A; 0/Receptors, GABA-B; 1134-47-0/Baclofen; 123690-79-9/CGP 35348; 2763-96-4/Muscimol; 4368-28-9/Tetrodotoxin; 50-67-9/Serotonin; 56-12-2/gamma-Aminobutyric Acid; 59-47-2/Mephenesin; 6384-92-5/N-Methylaspartate

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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