Abstract

Among other uses, aqueous and alcohol extracts of Piliostigma thonningii (Schum) have been claimed by traditional herbal medical practitioners in Nigeria to be effective tranquilizers. In our efforts to establish some of the tradomedical uses of the plant, we designed the present study in order to test the effects of the extracts on the locomotor activity (LA) of rats. Male rats were administered 25 or 50 mg/kg of the aqueous (AE) or ethanol (EE) extracts with or without 2 mg/kg dexamphetamine (DEX). Results show that the lower doses of both extracts did not significantly increase LA but the higher doses significantly (P < 0.05) increased the 90 min cumulative locomotor score although far less than 2 mg/kg DEX alone. Doses of 50 mg/kg of EE but not AE also significantly (P < 0.05) increased the 90 min cumulative DEX-induced locomotor score. The increase in LA by 50 mg/kg of the extracts has led us to conclude that they may not have any tranquilizing potentials.

Key words: Piliostigma thonningii, locomotor activity, tranquilization.