In an earlier report, we demonstrated an antipsychotic-like activity of a methanolic extract of Morinda citrifolia Linn fruit in mouse models and postulated the contribution of its bioactive principles, scopoletin and rutin. Moreover, the antidopaminergic activities of scopoletin and rutin were reported in isolated vas deferens preparations. In the present study, scopoletin and rutin were assessed for antipsychotic-like activity using apomorphine-induced climbing behavior and methamphetamine-induced stereotypy in mice. The results of this study revealed that scopoletin and rutin (0.05, 0.1, 0.5, and 1 mg/kg, p.o.) had a "U-shaped" dose-dependent effect on climbing and stereotyped behaviors induced by apomorphine and methamphetamine, respectively, in mice. A significant reduction in climbing and stereotyped behaviors caused by scopoletin and rutin was observed only at a dose 0.1 mg/kg. This study suggests that scopoletin and rutin can alleviate positive symptoms of schizophrenia only at a specific dose. Further studies evaluating the effects of scopoletin and rutin on animal models for negative symptoms of schizophrenia are required for a novel drug discovery in the treatment of neuropsychiatric diseases.
Keywords: climbing behavior; psychosis; rutin; scopoletin; stereotypy.