Sleep Regulation After Reduction of Brain Serotonin: Effect of p-Chlorophenylalanine Combined with Sleep Deprivation in the Rat

Abstract

Sleep was recorded in the rat after combined treatment with pchlorophenylalanine (PCPA; 300 mg/kg) and 24-h sleep deprivation (SD) and then compared with sleep recorded after either treatment alone. PCPA alone reduced total sleep (TS), rapid eye movement sleep (REMS) per TS, as well as the power density of the EEG delta band 0.25–4.00 Hz) of non-REM sleep (NREMS). SD enhanced these sleep parameters and reduced the frequency of wake episodes. The combined treatment with PCPA and SD reduced TS and REMS/TS to a level similar to that induced by PCPA alone, and it increased delta activity to a level similar to that induced by SD alone. The frequency of wake episodes was reduced. It is concluded that essential aspects of sleep regulation are still functional during PCPA-induced insomnia. The sleep-inhibiting action of PCP A may be related to the hyperresponsiveness to stimuli rather than to the impairment of sleep regulation itself.