Inhibition of ketamine-induced hyperlocomotion in mice by the essential oil of Alpinia zerumbet: possible involvement of an antioxidant effect

Objectives The antipsychotic, hypnotic, myorelaxant and antioxidant effects of the essential oil of Alpinia zerumbet (EOAZ) were studied. Methods EOAZ (50, 100 and 200 mg/kg i.p.) was administered once to mice for the determination of antipsychotic activity (evaluated by ketamine-induced hyperlocomotion), hypnotic activity (induced by sodium pentobarbital, 40 mg/kg i.p.), motor coordination (rotarod test), antioxidant effects (determination of lipid peroxidation and GSH levels), as well as alterations in nitric oxide levels (determination of nitrite content). Key findings EOAZ at doses of 100 and 200 mg/kg prevented ketamine hyperlocomotion, as did haloperidol (0.2 mg/kg i.p). EOAZ at a dose of 200 mg/kg decreased sleep latency, while all doses increased sleeping time. There was no effect on motor coordination. The in-vitro antioxidant capacity of the oil caused a decrease in lipid peroxidation and increase in GSH levels. EOAZ also prevented the decrease in nitrite content caused by oxidative stress. Conclusions The results suggest antipsychotic and antioxidant effects for the EOAZ that may have promising efficacy for the treatment of schizophrenia.