Dose-related effects of metrazol on retention and EEG

The effects of various dose levels of Metrazol on retention and electrocorticogram (ECoG) were investigated. Mice given a subconvulsive 30 mg/kg or a convulsive 50 mg/kg dose of Metrazol 15 min before reversal training in a discriminated escape learning task showed retention impairment of reversal training retention. Lower dose levels (5 or 10 mg/kg) had no effect. The 30 mg/kg dose produced asymmetrical dissociation. The convulsive dose (50 mg/kg), previously reported to result in symmetrical dissociation, produced ECoG changes that were still evident 15 min following the injection, i.e. at the time when training or testing usually took place. With lower doses (10 or 30 mg/kg), no apparent ECoG effects were observed at this interval. The implications of the findings were discussed with respect to the state-dependent learning hypothesis.