Neuroprotective effect of agomelatine in rat model of psychosis: Behavioural and histological evidence

Abstract

• Ketamine caused hyper-locomotion, increased stereotypy, ataxia, and decreased social withdrawal. • Agomelatine reversed the behavioural effects of ketamine. • Ketamine decreased neuronal count in the hippocampus and increased it in the amygdala. • The ketamine effects on neuronal count were reversed by agomelatine. • Agomelatine has the potential to alleviate negative symptoms of schizophrenia. Schizophrenia is a complex psychiatric disorder associated with positive (delusion, hallucination, and disorganised speech) and negative (affective flatering, avolition and social withdrawal) symptoms. Agomelatine (AGO) has been used as an anti-depressant to improve the negative symptoms in schizophrenia patients with co-morbid major depressive disorder. Therefore, the present study aimed to investigate the anti-psychotic effect of AGO in ketamine (KET)-induced psychosis rat model. Four groups ( n = 12/ group) of wistar rats were administered normal saline, KET (20 m/kg, i.p) and KET + AGO (20 and 40 mg/kg, i.p) for seven days. Behavioural tests were conducted on the seventh day after drug administration. Seven days administration of AGO at two different doses decreased the KET induced stereotypic and ataxic behaviour as compared with KET treated rats. In addition, AGO increased the social interaction time and decreased the horizontal and vertical locomotor behaviour in KET treated rats. Histologically, KET adminstration decreased hippocampal and increased basolateral amygdala (BLA) neuronal counts. AGO administration (at two different doses) significantly reversed the KET induced neuronal loss in the two brain areas. These findings suggest that AGO has a protective effect against KET-induced psychosis in this rat model. This study warrants further research to delineate the possible role of AGO in experimental model of psychosis particularly neurochemical and neuromolecular aspects.