DYNAMIC CHANGES IN HYPOTHALAMIC MONOAMINES DURING SLEEP-WAKE CYCLES ASSESSED BY PARALLEL EEG AND MICRODIALYSIS IN THE RAT

Monoaminergic changes during sleep/wake cycles were investigated in th e rostral hypothalamic areas since feeding, metabolism and sleep were shown to be causally related, Thus, the microdialysis probe was locate d stereotaxically in the ventromedial and paraventricular nuclei and c emented together with cortical electrodes for EEG sleep recordings, Th e monoaminergic changes were extensively investigated. Sampling of dia lysates over six minutes in freely behaving rats showed an increase in 5-HT and its metabolite 5-HIAA during wakefulness. DOPAC rose during PS. The two other monoamines, DA and NA, remained unchanged. It appear s that this method of investigation, extended in the future to other c andidate areas and other dialysable substances, may provide us with a dynamic picture that characterizes the sleep/wake cycle.