Differential pulse voltammetric determination of 5-hydroxyindoles in four raphe nuclei of chronic freely moving rats simultaneously recorded by polygraphic technique: physiological changes with vigilance states.

Nuclei raphe dorsalis ( RDN ), centralis (RCN), pontis (RPN) and magnus ( RMN ) were separately studied using differential pulse voltammetry ( DPV ) in chronic freely moving rats during the recording of their sleep-waking cycle by polygraphic technique. In each of these nuclei the height of the electrochemical signal appearing at +300 mV (peak 3) was maximum during waking (W), lower during slow-wave sleep (SWS) and minimum during paradoxical sleep (PS). Some pharmacological treatments indicated that in each of these nuclei the peak 3 represents the oxidation of the 5-hydroxyindoles. DPV measurements performed during specific behavioral states (eating, grooming, washing, drinking) called active waking (AW) or manipulations (handling, tail-pinch) demonstrated that this technique enables detection of changes occurring in animals under physiological conditions.