EEG and behavioral effects of gamma-hydroxybutyrate in the rabbit.

The effects of gamma-hydroxybutyrate (GHB) upon sleep wakefulness patterns and quantified nuchal muscle activity were examined in the rabbit in a dose-response paradigm (25-1,000 mg/kg). Relative to control (saline) values, there was no facilitation of sleep onset or epileptogenic activity at any of the dosages studied. However, at the higher GHB concentrations, slow wave sleep and tonic muscle activity were enhanced and a high amplitude, slow activity was superimposed on background EEG patterns. The highest concentration of GHB (1,000 mg/kg) was associated with depression of motor activity. An enhancement of paradoxical sleep observed at lower GHB levels in other species occurred in attenuated form in the rabbit. The results indicate dose-related effects on both sleep and motor activation in the rabbit, but the absence of seizure activity for the concentrations of GHB studied.