Open field locomotor activity. (A) Distance traveled over time. Repeated measures analysis of variance (ANOVA) reveals a significant difference in locomotor activity in the first 5 min of testing between the diesel exhaust particles (DEP)-treated group (n = 24) and the controls (n = 24) (F1,46 = 10.919, P = 0.002). (B) Total distance traveled in 20 min. One way ANOVA showed a significant main effect of treatment on locomotor activity (F1,46 = 5.997, P = 0.018). No significant difference was observed in the amount of time spent in the center area of the open field apparatus between control and DEP-treated animals (F1,46 = 0.723, P = 0.400). Data are presented as mean ± SEM.