Neuropharmacological investigations on muscimol, a psychotropic drug extracted from Amanita muscaria

Abstract

The effects of muscimol on the EEG and on the spontaneous and conditioned behavior of cats, rabbits, and rats were studied. High voltage 3 c/sec. waves appear in the EEG tracing of rabbits and rats treated with 0.5-1 mg/kg of the drug; after higher doses (2 mg/kg) spikes appear, intermingled with the slow waves. Administration of eserine (0.2 mg/kg) only slightly influences the EEG "synchronization" induced by muscimol. Muscimol-treated rabbits receiving small doses of diazepam or pentobarbital exhibit a flaccid paralysis accompanied by an EEG pattern similar to that of the deep stages of anesthesia. In cats and rabbits trained to an instrumental reward discrimination task, muscimol disrupts the conditioned performance at doses of 0.5-1 mg/kg. Spikes appear on the EEG of the cats treated with the drug and unable to perform the conditioned task. These results are discussed in relation to the hallucinogenic and confusional effects reported for muscimol in man. © 1969 Springer-Verlag.