Combined effects of risperidone and ethyl pyruvate on ketamine-induced schizophrenia-like symptoms in mice

Objective: The underlying cause of schizophrenia is not fully understood. The disease is a neuropsychiatric disorder characterized by a decline in learning-memory functions. NMDA receptor antagonists have been shown to cause schizophrenia-like symptoms in experimental animals. The aim of this study was to investigate the effect of ketamine on memory functions at repeated doses, and also to show how therapeutic interactions with risperidone, currently used in the treatment of schizophrenia, are administered against EP and when combined with EP. Materials and Methods: Groups of 7-9 animals each received intraperitoneal injection daily for 14 days. Control; 0.9% salin solution, Ketamine: 25 mg/kg Ketamine, Ethyl Pyruvate: 50 mg/kg EP, Risperidone: 0,2 mg/kg RSP, Ket + EP: 25 mg/kg Ket + 50 mg/kg EP, Ket + RSP: 25 mg/kg Ket + 0,2 mg/kg RSP, Ket+ EP + RSP: 25 mg/kg Ket + 50 mg/kg EP + 0,2 mg/kg RSP. Psychopharmacological examinations were performed by open field, elevated plus maze, and passive avoidance testing. Lipid peroxidations were evaluated by examining the levels of malondialdehyde in the hippocampus. Results: Although there was no significant difference in malondialdehyde levels due to repeated ketamine applications, there was a significant decrease in spatial and emotional memory performances. Impaired memory functions were significantly improved by the combination of risperidone, ethyl pyruvate and the combination of these two drugs. Conclusion: It has been concluded that risperidone and ethyl pyruvate alone and in combination may provide therapeutic benefit in impaired learning and memory functions due to NMDA antagonism. Key Words: Risperidone, Ethyl Pyruvate, Schizophrenia, learning memory, antioxidant