Fig. 1

Effects of acute administration of mitragynine and diazepam on the number of entries into the central zone (a), the percentage of time spent in centre (b) and the total distance travelled (c) in the open-field. Animals were orally treated with Tween 20 (5 ml/kg), mitragynine (10, 20 and 40 mg/kg) or diazepam (10 mg/kg) 60 min before testing. Each bar represents mean ± SEM. n = 8. *p < 0.05, **p < 0.01 and ***p < 0.001 when compared to control group