Memory enhancing effects of granisetron (BRL 43694) in a passive avoidance task.

Recent evidence suggests that serotonin plays an important role in learning and memory processes in animals. The present study examined the effect of the 5-HT3 receptor antagonist, granisetron (BRL 43694), on acquisition, retention and retrieval of a passive avoidance response in mice. Granisetron (1 and 10 micrograms/kg) administered 30 min before presentation of footshock increased the step-down latency when tested 24 h after footshock. The acquisition process was not affected by a dose of 100 micrograms/kg. Granisetron (10 and 100 micrograms/kg) produced a significant increase in latency to step out of the safety zone, when administered immediately after or 23.5 h after footshock. However, at 1 microgram/kg, granisetron had no effect. These results confirm the important role played by 5-HT in the process of learning and memory, and also suggest that memory enhancement may be possible with non-cholinergic treatments.