Rationale: The plasma membrane dopamine transporter (DAT) transports dopamine into neurons. Striatal synaptosomes from DAT-KO mice show no uptake of radiolabelled dopamine (Fig. 1d). Fast-scan cyclic voltammetry (carbon-fibre amperometry) after electrical stimulation in striatal DAT-KO slices reveals a 100times longer time for dopamine clearance in comparison to wildtype slices (Fig. 5). These findings indicate a defect in dopamine re-uptake in DAT-KO mice.. Experimental description: We have produced, by means of in vivo homologous recombination, a strain of mice in which the gene encoding the DAT has been disrupted.