To study the effects of
buspirone, a selective anxiolytic drugs, on
acquisition and retention, mice were trained and tested
on step through passive
avoidance and two way active avoidance learning tasks. In the step through passive avoidance task, buspirone did not alter performance of passive avoidance response when given 30 min before the training trial in the dose range of 0.3-10 mg·kg -1 , but retention was significantly disrupted by 0.3 and 1 mg·kg -1 doses when buspirone was administered immediately after the training trial. Similar results were obtained when buspirone was administered 10 min prior to each session for 4 continuous days in the two way active avoidance learning task. On d 1, buspirone markedly increased the rate of
acquisition of the avoidance responses in the dose range of 0.3-10 mg·kg -1 , but on the following days, percentage of avoidance responses significantly and progressively reduced in all doses except at 0.3 mg·kg -1 . In the meantime, only a higher dose of buspirone (10 mg·kg -1 )markedly prolonged the escape latency and decreased locomotor activity in mice, suggesting this dose impair performance by depressing motor activity and shock sensitivity. These experiments demonstrate that buspirone disrupt retention but facilitate or not affect acquisition.