Antianxiety profile of ondansetron, a selective 5-HT3 antagonist, in a novel animal model.

The profile of action of ondansetron was assessed in a novel animal model of anxiety. The mirrored chamber is a nonpunishing quantitative model of anxiety which measures approach-conflict behavior. Ondansetron in all the doses tested (0.01, 0.1 and 1 mg/kg i.p.) showed significant anxiolytic action as compared to naive mice, but it was less potent as compared to a well-known anxiolytic, diazepam (1 mg/kg). These results suggest that ondansetron has anxiolytic efficacy in nonconflict paradigms of anxiety, a response not mediated by the conventional neurotransmitter receptors. GABA-benzodiazepine as flumazenil (4 mg/kg), a benzodiazepine receptor antagonist, failed to reverse the behavioral parameters evoked by ondansetron.