The success of Ondansetron in market leads to further research into 5-ht3 receptor antagonist and rapid development of research on the structure-activity relationship of 5-ht3 receptor antagonist.

OBJECTIVE:To elucidate the effect of ondansetron(OND), a 5-HT3 receptor antagonist, on the morphine-induced conditioned place preference(CPP) in mice and its possible mechanism.