Anticonvulsant effect of Hypericum perforatum: role of nitric oxide.

Hypericum perforatum L. is used in traditional medicine for its anticonvulsant property. We studied the anticonvulsant activity of the aqueous and ethanolic extracts of Hypericum perforatum aerial parts in mice in order to evaluate the traditional use of this plant. The pentylenetetrazole (PTZ) and the maximal electroshock seizure (MES) tests were used for assessing the anticonvulsive effects of this plant. In the PTZ test, the extracts (0.1-1g/kg, i.p.) delayed the onset of tonic convulsions and protected mice against mortality. In the MES test, both extracts did not showed an antiseizure activity. L-NAME (1-10 mg/kg, i.p.), a nitric oxide (NO) synthase inhibitor, reduced the anticonvulsant activity of the extracts. The results of this study indicate that the extracts of Hypericum perforatum aerial parts could contribute to the control of petit mal seizure and this effect may be partially mediated by nitric oxide pathway.