Effect of aqueous and lipid-soluble extracts of kava on the conditioned avoidance response in rats.

The aqueous, pyrone-free extract from kava (Piper methysticum) and the lipid-soluble extract (kava resin) were tested for their effect on amphetamine-induced hypermotility in mice and on conditioned avoidance response behavior in rats in a shelf-jump apparatus. Both kava extracts reduced amphetamine-induced hypermotility. Aqueous kava extract in i.p. doses of 30 mg/kg to 500 mg/kg had no effect on conditioned avoidance responses. At or below 100 mg/kg i.p. kava resin also failed to modify the number of conditioned avoidance responses obtained. However, 125 mg/kg of resin significantly reduced the number of conditioned avoidance responses by 18%. Increasing the dose of kava to 150 mg/kg caused ataxia and sedation which was so marked that a modified protocol was necessary. Only a marginally greater effect on conditioned avoidance response was obtained under these conditions. The effect of kava extract was slight compared to that of the standard antipsychotic drugs chlorpromazine and haloperidol in our procedure.