Anxiolytic and memory improving activity of fluoxetine

The anxiolytic and memory improving effects of fluoxetine, a new antidepressant drug, were investigated in rats. Anxiolytic activity was examined using Crowley's "two compartment exploratory test". Memory was assayed in the response passive avoidance test (RPAT) and labyrinth test. Wistar rats were used in all experiments. They were given fluoxetine hydrochloride (5 mg/kg po) and scopolamine hydrobromide at the dose of 0.5 mg/kg, sc. It was found that the drug has a high anxiolytic activity after the first administration. Thereafter however, the anxiolytic effect gradually decreased and 28 days later it was no longer present. In memory testing experiments (RPAT and labyrinth test) fluoxetine improved the performance of memory task and up to 14 days there were no signs of tolerance development. The authors discuss the possibility of involvement of the anxiolytic and memory improving effects of fluoxetine in the antidepressant action of the drug.