Differential pulse voltammetry: parallel peak 3 changes with vigilance states in raphe dorsalis and raphe magnus of chronic freely moving rats and evidence for a 5-HT contribution to these peaks after monoamine oxidase inhibitors.

Nuclei raphe dorsalis (RDN) and magnus (RMN) were simultaneously studied using the differential pulse voltammetry (DPV) technique in chronic freely moving rats during their sleep-waking cycle. Parallel variations in peak 3 (due to 5-hydroxyindoles) were observed in both these areas: the peak 3 heights were maximum in both RDN and RMN during waking (W), decreased in slow wave sleep (SWS) and were minimum in paradoxical sleep (PS). Monoamine oxidase inhibitor (MAOI) treatments induce at first a decrease of peak 3 (-50% compared to the control values), but there was a subsequent increase (+100% compared to the control values). This suggests that 5-hydroxytryptamine (5-HT) can contribute to peak 3 measured in vivo.