Locomotor activity is increased in A2AR-Gpr88 mice whereas D1R-Gpr88 mice show lack of locomotor habituation. When placed individually in a dimly lit open field for 30-min daily sessions during 5 d, both CMV-Gpr88 (A) and A2AR-Gpr88 (C) but not D1R-Gpr88 (B) mice traveled a longer distance then their control littermates. D1R-Gpr88 mice, however, present similar total locomotion when compared to their control littermates (B). When comparing locomotion between the first (1) and last session (5), CMV-Gpr88 mice, in contrast to CMV-CTL, traveled a longer distance in the last compared to the first day. In contrast to their control littermates, D1R-Gpr88 mice show similar locomotion in the first and last open field session. Regardless of their hyperlocomotion, A2AR-Gpr88 mice habituated to the open field presenting decreased overall locomotion in the last test session. Line graphs show the distance traveled (cm) in 5-min bins over a 30-min session. Bar graphs show the average total distance traveled (cm) over the 30-min sessions period. Data are represented as mean ± SEM. A, n = 21 CMV-CTL; n = 21 CMV-Gpr88. B, N = 13 D1R-CTL, N = 12 D1R-Gpr88. C, n = 17 A2AR-CTL; n = 10 A2AR-Gpr88. Open stars: one star p < 0.05; two stars p < 0.01 (RM two-way ANOVA).