Release of endogenous serotonin from "encéphale isolé" cats. II - Correlations with raphe neuronal activity and sleep and wakefulness.

The discharge pattern of single neurons localized in raphe nuclei dorsalis and centralis superior was recorded in "encéphale isolé" cats, during sleep and wakefulness episodes occurring spontaneously or triggered by vago-aortic stimulation. In both nuclei, a similar and progressive decrease in frequency of discharges is generally observed during shifts between wakefulness, the transitional phase of sleep and paradoxical sleep. In addition, the release of serotonin (5-HT) has been studied with push-pull cannulae (caudate nucleus level) and superfusion techniques (cortical associative area) in relation to the different stages of consciousness. The results showed a clear diminution of endogenous 5-HT released during spontaneously occurring or vago-aortic triggered sleep.