Gamma hydroxybutyrate: Correlation of serum and cerebrospinal fluid levels with electroencephalographic and behavioral effects

Gamma hydroxybutyrate was administered to adult cats by intravenous infusion at varying dosages while an electroencephalogram (EEG) was recorded from electrodes placed stereotactically in the right and left hippocampus and thalamic intralaminar nucleus and from cortical electrodes. Blood and cerebrospinal fluid samples were assayed for gamma hydroxybutyrate. The first EEG change, slowing with occasional spikes, was seen at serum levels of 75 µg per milliliter. Changes in the recordings progressed through a number of stages, culminating in bursts of poly spiking interspersed among periods of electrical silence first seen at 350 µg per milliliter. Behavior was characterized by a progressively deepening trancelike state punctuated at higher serum levels by spontaneous and stimulus-induced myoclonic jerks. These changes were correlated with serum levels and are more similar to petit mal stupor than any kind of natural sleep-like state previously used to describe them.