Ondansetron fails to attenuate a scopolamineinduced deficit in a Stone maze task

THE 5-HT, receptor antagonist ondansetron has previously been reported to improve cognition in the mouse, rat and marmoset in a variety of behavioural paradigms. The present study used the Stone maze to test the effect of ondansetron on the deficit caused by scopolamine in the performance of a highly complex spatial memory task in the rat. Ondansetron administered over a large dose range (1.0 ng kg-1.0 mU kg, i.p., b.d.) for a period of 10–15 days failed to attenuate the scopolamine deficit. Indeed at one dose level ondansetron (100 ng kg, i.p., b.d.) administered in combination with scopolamine (0.5 mg kg, i.p.) significantly potentiated the deficit, compared with the performance of rats receiving scopolamine alone.