A. Python et al., Extracellular serotonin variations during vigilance states in the preopticarea of rats: a microdialysis study, BRAIN RES, 910(1-2), 2001, pp. 49-54
Numerous studies have shown that serotonergic transmission decreases from w
aking (W) to slow wave sleep (SWS) to paradoxical sleep (PS), suggesting an
active role of serotonin (5-HT) in W but not in sleep. Conversely, the inh
ibition of 5-HT activity produces insomnia. This insomnia can be reversed b
y injections of 5-hydroxytryptophan in the preoptic area (POA), suggesting
that 5-HT is necessary in this cerebral structure for sleep. Using microdia
lysis, we studied, 5-HT variations in the POA of rats in relation to vigila
nce states. 5-HT levels were higher during W than during during SWS and PS.
5-HT increased just before the rats fell asleep and then decreased during
sleep. A decreased 5-HT transmission was also observed from SWS to PS. Thes
e data document a positive correlation between 5-HT levels in POA and wakef
ulness. Moreover, these observations are in favour of a permissive role of
5-HT in the POA during PS. A comparison between the POA and the prefrontal
cortex in the sleep-wake cycle is discussed. (C) 2001 Elsevier Science B.V.
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