The central nervous effects of Mitragyna africanus (Willd) stembark extract in rats.

The acute toxicity and the central effects of Mitragyna africanus (M. africanus) stembark methanol extract were studied in rats. The extract did not produce any death in the treated rats even at the highest dose (6400 mg kg(-1)) used. It produced depressant effects on the central nervous system. The stembark extract potentiated amylobarbitone sleeping time in rats dose-dependently, induced sleep in rats and also produced significant local anaesthetic effect on rabbits, the effects being comparable to that of xylocaine. The extract protected rats treated with a convulsive dose of strychnine (2 mg kg(-1)) and increased the period of onset of convulsions and decreased the number of spasms.