The study investigated the effects of different doses of methanol extract of leaf, stem bark and root of Ximenia americana (X .a) plant on neuromuscular behavior of Wister rats. 120 rats were divided into four groups (control, leaf, stem bark and root) consisting of 30 rats each. Each group was further divided into three sub-groups consisting of 10 rats per sub-group. Each rat was administered orally methanol extracts of either leaf, stem bark or root of X .a at doses of 10, 100 or 1000 mg/kg body weight, respectively, every two days for two weeks of the study period. The control group was given equivalent of 0.2 ml of sterile water per rat. The result of neuromuscular behaviour recorded after the administration of the extracts showed that X .a had an inhibitory effect on locomotor activity and excitability of the rats. The inhibitory effect of the extract was dose dependant and the effect increased significantly (P<0.05) with the duration of the study. The methanol extract from the root of X .a had the highest (P<0.05) inhibitory effect, compared with the leaf or stem bark. The inhibitory effect of the extract was due to the sedative, spasmolytic and pro-oxidant effects of some substances like tannins, flavonoids, saponnins, anthraquinones, alkaloids and terpenoids found in the methanol extract of X .a. In conclusion, the inhibitory effect of the methanol extract on neuromuscular behaviour suggested that it should be used with great caution in animals and humans, especially in individuals engaged with various machine operations.
