Dose-related suppression of REM sleep and PGO waves by the serotonin-1 agonist eltoprazine.

Parental administration of the serotonin-1 agonist eltoprazine (0.0625 to 4.0 mg/kg [0.0002 to 0.016 mmol/kg]) in freely moving cats produced significant suppression of electrophysiologic rapid eye movement (REM) sleep signs, ponto-geniculo-occipital (PGO) activity, and REM sleep behavior. The virtual total suppression of REM sleep (0.4%, 4.0 mg/kg) and PGO wave activity (2 to 4 mg/kg) in exchange for increasing amounts of non-REM (NREM) slow-wave sleep was a dose-dependent function of the amount of eltoprazine administered. Wakefulness was unaffected by eltoprazine regardless of dose. Concurrent with this dose-dependent suppression of REM was a dose-dependent increase in electroencephalographic synchrony and mean electromyographic amplitude. Since eltoprazine was found to shift the balance between REM and NREM sleep but did not change the balance between sleep and waking, it is a potentially useful tool for the investigation of serotonergic-cholinergic interaction.