Anticonvulsant activity of ginseng on seizures induced by chemical convulsants.

PURPOSE: To test the anticonvulsant activity of three preparations of American ginseng: whole root extract, whole leaves/stems extract, and a partially purified extract that concentrates the Rb ginsenosides (Rb extract).

METHODS: One hour after treatment with normal saline, or one of the three ginseng preparations, seizures were induced in adult, male, Sprague-Dawley rats with kainic acid (KA; 10 mg/kg), pilocarpine (300 mg/kg, preceded by methylscopolamine, 1 mg/kg, s.c.), or pentylenetetrazol (PTZ, 50 mg/kg). Time to onset of seizure activity, duration of seizure activity for PTZ, seizure severity, and weight change for KA and pilocarpine were determined for each animal. The brains from animals who had received KA or pilocarpine were examined for severe neuronal stress, by using immunoreactivity for heat-shock protein (HSP)72.

RESULTS: The Rb extract had a dose-dependent anticonvulsant effect in all three models of chemically induced seizures: increasing the latency to the seizures; decreasing the seizure score, weight loss, and subsequent neuronal damage after pilocarpine; and shortening the seizure duration and reducing mortality after PTZ. The Rb extract also significantly reduced the effects of KA, including completely blocking behavioral seizures. The root preparation increased the mortality rate after administration of pilocarpine, but had no other significant effects. The leaves/stems preparation, at 120 mg/kg, reduced the weight loss after pilocarpine, but had no other significant effects.

CONCLUSIONS: Ginseng extract made from either the root or leaves/stems is ineffective against chemically induced seizures. A partial purification of the whole extract that concentrates the Rb1 and Rb3 ginsenosides has significant anticonvulsant properties.