The effects of the combined administration of gamma-hydroxybutyrate and diazepam on sleep parameters in the rat.

The actions of diazepam and gamma-hydroxybutyrate (GHB) were assessed on the sleep-wakefulness cycle of male Wistar rats. One and 2 mg/kg diazepam and 12.5 mg/kg GHB had no effects on the sleep variables. After 25 mg/kg GHB, slow wave sleep (SWS2) was significantly increased. Following the combined administration of non-effective doses of GHB and diazepam, significantly higher amounts of SWS2 at the expense of wakefulness were obtained. The injection of a subconvulsant dose of bicuculline (2.5 mg/kg) prior to treatments which significantly increased SWS2 prevented this effect to show up. It is suggested that the actions of GHB and diazepam on the sleep-awake cycle are related to the same neurotransmitter system.