The effects on motor behaviour and short-term memory tasks in mice following an acute administration of Mitragyna speciosa alkaloid extract and mitragynine

Abstract

Mitragyna speciosa Korth. leaves have been traditionally used by Malay and Thai natives for its opium-like effect and coca-like stimulant ability to enhance tolerance for hard work. Mitragynine is the major indole alkaloid in this plant. In the present study, we investigated the effects of the alkaloid extract of M. speciosa leaves and its major alkaloid mitragynine on exploratory behaviour, short-term memory and motor coordination in mice using Y-maze and rota-rod tests, respectively. Male Swiss albino mice were orally administrated with 20, 40 and 80 mg/kg alkaloid extract of M. speciosa leaves or mitragynine. Acute oral administration of the alkaloid extract or mitragynine significantly increased the total number of arm entries, rearing frequency and decreased grooming and immobility time in Y-maze test when compared to control group (P<0.05). However, the alkaloid extract or mitragynine did not affect short-term memory or motor coordination. These findings suggest that acute administration of M. speciosa alkaloid extract or mitragynine may enhance exploratory behaviour due to the decrease in stress to a novel environment.   Key words: Mitragyna speciosa, mitragynine, motor behaviour, short-term memory, Y-maze, rota-rod.