Electrophysiological evidence that noradrenergic neurons of the rat locus coeruleus are tonically inhibited by GABA during sleep

It is well known that noradrenergic locus coeruleus (LC) neurons decrease their activity during slow wave sleep (SWS) and are virtually quiescent during paradoxical sleep (PS). It has been proposed that a GABAergic input could be directly responsible for this sleep‐dependent neuronal inactivation. T...

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Bibliographic Details
Published in:The European journal of neuroscience 1998-03, Vol.10 (3), p.964-970
Main Authors: Gervasoni, D., Darracq, L., Fort, P., Soulière, F., Chouvet, G., Luppi, P-H.
Format: Article
Language:English
Subjects:
Animals
bicuculline
Bicuculline - administration & dosage
Bicuculline - pharmacology
Electrophysiology
GABA Antagonists - administration & dosage
GABA Antagonists - pharmacology
gamma-Aminobutyric Acid - pharmacology
head-restrained rat
Iontophoresis
Life Sciences
Locus Coeruleus - cytology
Locus Coeruleus - drug effects
Locus Coeruleus - physiology
Male
Neurons - drug effects
Neurons - physiology
Neurons and Cognition
Norepinephrine - physiology
paradoxical sleep
polygraphic recordings
Polysomnography - drug effects
Rats
Rats, Sprague-Dawley
Restraint, Physical
single unit recordings
Sleep - physiology
Space life sciences
Wakefulness - drug effects
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Summary:It is well known that noradrenergic locus coeruleus (LC) neurons decrease their activity during slow wave sleep (SWS) and are virtually quiescent during paradoxical sleep (PS). It has been proposed that a GABAergic input could be directly responsible for this sleep‐dependent neuronal inactivation. To test this hypothesis, we used a new method combining polygraphic recordings, microiontophoresis and single‐unit extracellular recordings in unanaesthetized head‐restrained rats. We found that iontophoretic application of bicuculline, a specific GABAA‐receptor antagonist, during PS and SWS restore a tonic firing in the LC noradrenergic neurons. We further observed that the application of bicuculline during wakefulness (W) induced an increase of the discharge rate. Of particular importance for the interpretation of these results, using the microdialysis technique, Nitz and Siegel (Neuroscience 1997; 78: 795) recently found an increase of the GABA release in the cat LC during SWS and PS as compared with waking values. Based on these and our results, we therefore propose that during W, the LC cells are under a GABAergic inhibitory tone which progressively increases at the entrance and during SWS and PS and is responsible for the inactivation of these neurons during these states.
ISSN:0953-816X
1460-9568
DOI:10.1046/j.1460-9568.1998.00106.x