Influence of olanzapine on cognitive functions and catalepsy in rats after single and chronic administration.

The aim of our investigations was to supplement the scarce information about behavioral effects of olanzapine and especially to find out if the effects change during prolonged treatment. It was established that at a dose of 0.5 mg/kg, which did not evoke sedation, olanzapine had distinct anxiolytic effects, both after acute and chronic treatment. Olanzapine improved memory in the maze test (food finding time), but only in chronic experiments after a lag of 14 days. Olanzapine at the dose of 0.5 mg/kg did not cause catalepsy but a higher dose of 1 mg/kg elicited strong sedating effects, which would interfere with the catalepsy test. The results of Porsolt's test (immobility time in swimming rats) were interesting because a shortening of immobility time occurred only after single drug injection. Our results are in agreement with the statement of other authors that olanzapine has greater potency in antagonizing responses mediated rather by 5-HT than D2 receptors.