Figure 3.

Spontaneous hyperlocomotion and attenuated cocaine-induced locomotion in DAT knockout mice. Locomotor activities were recorded for 1-hr periods in wild type (+/+, open bars) and heterozygous (+/−, gray bars) and homozygous (−/−, black bars) DAT knockout mice placed into an activity monitor cage to which they had not been previously exposed at the time 3 hr before injection with cocaine (10 mg/kg s.c.) at the arrow (time 0). Homozygous knockout mice show greater locomotor activity when placed in a novel environment, but less locomotor response to cocaine. Values represent mean ± SEM; ∗, P < 0.05 versus wild-type group; #, P < 0.05 versus the locomotor activity before injection; n = 7–14 mice per genotype.