Ketamine-enhanced immobility in forced swim test: A possible animal model for the negative symptoms of schizophrenia

► Effects of ketamine on immobility time in forced swim test (FST) were evaluated. ► Repeated Ketamine administration enhanced the duration of immobility in FST. ► The enhanced immobility time persisted for 21 days after withdrawal ketamine. ► Clozapine and risperidone attenuated the ketamine-enhanced immobility time. ► Ketamine-enhanced immobility in FST is a possible animal model for schizophrenia.