Anticonvulsant, anxiolytic and hypnotic effects of Monodora myristica (Gaertn, Dunal.) dried seed essential oil in mice

Background: The seed of Monodora myristica (Gaertn, Dunal.) has been reported to be useful in the management of neuralgia, headaches, rheumatism, pain, cough and tonic among others, however, the central nervous system effect of the essential oil has not been investigated. This study was carried out to evaluate the anticonvulsant, anxiolytic and hypnotic effects of M. myristica dried seed essential oil in mice. Method: The essential oil of M. myristica (EMM) was obtained from the dried seeds by hydrodistillation, while the median lethal dose (LD ) was determined using Lorke's method. Doses of 50 EMM at 25, 50, 100 mg/kg, per oral were used for the novelty-induced behavior, anticonvulsant and hypnotic activities while lower doses of EMM at 6.25, 12.5, 25 mg/kg, per oral were used for the anxiolytic activities. The novelty-induced behaviours were determined in the open field test (OFT). The essential oil effect on amphetamine-induced hyperlocomotor response in the OFT was determined. The anticonvulsant effect was evaluated using chemoconvulsants such as pentylenetetrazole (PTZ) and strychnine (STR)–induced convulsion models. Potential anxiolytic effect was investigated using hole board (HB) and elevated plus maze (EPM) models. The hypnotic effect was determined using ketamine-induced sleep model where the sleep latency and the total sleeping time were assessed. Results: Oral LD of EMM was 283 mg/kg and EMM in the open field test caused significant (p<0.01) 50 dose-dependent decrease in locomotion, rearing and grooming activities suggesting that EMM possessed central nervous system depressant activity. It significantly (p<0.05) inhibited amphetamine￾induced hyperlocomotor behavio therefore suggesting that EMM may be useful in alleviating disorder related to hyperactivity. Oral administration of EMM signifi ant (p<0.05) delayed the onset of seizures induced by PTZ and STR but did not protect against seizures. EMM also caused significant (p<0.05) reduction in sleep latency and prolongation of total sleep time suggesting that it has hypnotic effect. EMM did not show any significant anxiolytic effects in HB and EPM models. Conclusion: The study showed that EMM possessed significant central inhibitory and hypnotic effects but has no anxiolytic properties.