Effects of systemicd-amphetamine on extracellular DA levels in the nucleus accumbens and on locomotor activity in WT and α1bAR-KO mice.d-amphetamine was injected 240 min after the introduction of the probe. A, B, Extracellular DA levels are expressed in function of WT mice basal DA values. *p < 0.05; **p < 0.01, significantly different from respective basal DA values (Dunnett's multiple test). C, D, Locomotor activities before and after d-amphetamine injections.E, Histograms of locomotor activities for 120 min after the d-amphetamine injections. *p < 0.05; ***p < 0.001, significantly different from WT mice (Student's t test) (N = 5–9 mice per group).