S. Kaur et al., GABA IN LOCUS-COERULEUS REGULATES SPONTANEOUS RAPID EYE-MOVEMENT SLEEP BY ACTING ON GABA(A) RECEPTORS IN FREELY MOVING RATS, Neuroscience letters, 223(2), 1997, pp. 105-108
The aminergic neurons in the locus coeruleus are known to cease firing
during rapid eye movement sleep. Since electrical stimulation of locu
s coeruleus reduced, while carbachol stimulation increased rapid eye m
ovement sleep and gamma-aminobutyric acid (GABA) neurons as well as te
rminals are present in the locus coeruleus, we hypothesized that GABA
may be involved for cessation of locus coeruleus neuronal firing durin
g rapid eye movement sleep. Under surgical anaesthesia male Wistar rat
s (250-300 g) with bilateral guide cannulae targeting locus coeruleus
were prepared for chronic sleep-wakefulness recording. Electroencephal
ogram (EEG), electrooculogram (EGG), electromyogram (EMG) were recorde
d in normal, after 250 nl saline and after picrotoxin (250 ng in 250 n
l) injection bilaterally into the locus coeruleus. The results showed
that mean duration per episode of rapid eye movement sleep was signifi
cantly reduced, although its frequency of generation/h was not signifi
cantly affected. This study suggests that GABA in locus coeruleus is i
nvolved in tonic regulation of rapid eye movement sleep and the action
is mediated through GABAA receptor. (C) 1997 Elsevier Science Ireland
Ltd.