LAUSR

Rationale Second-generation antipsychotics are the first-line medications prescribed for schizophrenic patients; however, some of them, such as olanzapine and risperidone, may induce metabolic dysfunctions during short-term treatment. Metformin is an effective adjuvant that attenuates antipsychotic-induced metabolic dysfunctions (AIMD) in clinical practice. Whether metformin can reverse AIMD and whether metformin affects the therapeutic effects of antipsychotics in animal models of schizophrenia are questions that still need to be investigated. Methods In this study, an animal model of schizophrenia was established by consecutive injections of MK801 during the neurodevelopmental period. In adulthood, different dosages of olanzapine or risperidone treatment were administered to the schizophrenia model animals for 14 days. Both therapeutic effects and metabolic adverse effects were measured by behavioral tests, histopathological tests, and biochemical tests. The coadministration of different doses of metformin with olanzapine or risperidone was used to evaluate the effects of metformin on both AIMD and the therapeutic effect of those antipsychotics. Results The MK801-treated rats showed schizophrenia-like behavior and variations in the shape and volume of the hippocampus. Both olanzapine and risperidone reversed the MK801-induced behavioral abnormalities as the dosage increased; however, they degenerated the hepatocytes in the liver and influenced the blood lipid levels and blood glucose levels. The coadministration of metformin did not affect the therapeutic effects of olanzapine or risperidone on behavioral abnormalities but attenuated the metabolic dysfunctions induced by those antipsychotics. Conclusion Metformin attenuated the olanzapine- and risperidone-induced metabolic dysfunctions in MK801-induced schizophrenia-like rats without reducing the therapeutic effects of the antipsychotics.