Abstract
Electroencephalographic effects of ID-690 were investigated in unanesthetized, unrestrained rabbits with chronic electrode implants, and compared with those of diazepam. ID-690, in a does of 0.05 ?? 0.2 mg/kg i.v., revealed a drowsy pattern in spontaneous EEG, i.e. high voltage slow waves and spindle bursts increased in the neocortex and amygdaloid complex, while the hippocampal theta rhythm was desynchronized. In addition, low voltage fast waves appeared particularly in cortical EEG. This is charasteristic of benzodiazepines. The EEG arousal response to auditory stimulation was markedly depressed by ID-690. The arousal response to electric stimulation of the posterior hypothalamus was more strongly inhibited by ID-690 than that to mesencephalic reticular stimulation. The EEG effects of diazepam were qualitatively similar but less potent than those of ID-690. ID-690 and diazepam showed no effect on the photic driving response elicited by flash light in the visual cortex. The recruiting response was slightly enhanced by ID-690 and diazepam. ID-690 was much more potent than diazepam in depressing hippocampal and amygdaloid afterdischarges.
