Combined treatment with aripiprazole and antidepressants reversed some MK-801-induced schizophrenia-like symptoms in mice.

BACKGROUND: Atypical antipsychotic drugs have some efficacy in alleviating the negative and some cognitive symptoms of schizophrenia but those effects are small and mechanisms of this action are still unknown A few clinical reports have suggested that antidepressants (ADs), are able to augment the activity of atypical antipsychotic drugs. Thus, in the present study, we aimed to evaluate the effect of ADs, escitalopram (ESC) or mirtazapine (MIR) and aripiprazole (an atypical antipsychotic drug) given separately or jointly, on the MK-801-induced positive and cognitive symptoms of schizophrenia in mice.

METHODS: The experiments were conducted on male Albino Swiss mice. ADs and aripiprazole were given 30min before MK-801 injection. Locomotor hyperactivity induced by MK-801 (0.3mg/kg) was measured for 30min, starting 30min after MK-801 administration. In the novel object recognition test, MK-801 (0.2mg/kg) was given 30min before the first introductory session. Memory retention was evaluated for 5min, starting 90min after the introductory session.

RESULTS: Aripiprazole (0.3mg/kg) reduced the locomotor hyperactivity induced by MK-801(0.3mg/kg). Co-treatment with an inactive dose of aripiprazole and ESC or MIR inhibited the effect of MK-801. Moreover, MK-801 (0.2mg/kg) decreased the memory retention. Aripiprazole (0.3mg/kg) reversed that effect. Co-treatment with an inactive dose of aripiprazole and ESC or MIR abolished the deficit of object recognition memory induced by MK-801.

CONCLUSIONS: The obtained results suggest that ADs may enhance the antipsychotic-like effect of aripiprazole in the animal tests used for evaluation of some positive and cognitive symptoms of schizophrenia.