Dopamine is a catecholamine neurotransmitter that functions in the CNS to control locomotor, cognitive, emotional and neurendocrine processes, and in the periphery to modulate cardiovascular, renal and gastrointestinal processes. The biological activities of dopamine are mediated by a family of five GPCRs. The D1 and D5 subtypes couple to Gs to increase intracellular cAMP, whereas the D2, D3 and D4 subtypes couple to Gi to reduce cAMP. The hypertensive phenotype of mice with a targeted deletion of D5 indicates that D5 regulates central control of sympathetic vascular tone. In addition, D5 modulates locomotion and corticostriatal long-term depression.