Dynamic changes in hypothalamic monoamines during sleep/wake cycles assessed by parallel EEG and microdialysis in the...

Monoaminergic changes during sleep/wake cycles were investigated in the rostral hypothalamic areas since feeding, metabolism and sleep were shown to be causally related. Thus, the microdialysis probe was located stereotaxically in the ventromedial and paraventricular nuclei and cemented together with cortical electrodes for EEG sleep recordings. The monoaminergic changes were extensively investigated. Sampling of dialysates 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 appears that this method of investigation, extended in the future to other candidate areas and other dialysable substances, may provide us with a dynamic picture that characterizes the sleep/wake cycle.