DA receptors belong to the G-protein coupled receptors superfamily, and are prominent in the vertebrate central nervous system (CNS) as well as the peripheral nervous system (PNS). The neurotransmitter dopamine, a precursor of noradrenaline and adrenaline, is one of the main endogenous catecholamine ligand for DA receptors. There are at least five subtypes of dopamine receptors, D1, D2, D3, D4, and D5, based on their sequence homology, pharmacology and functional properties. Several neuropsychiatric disorders are derived from abnormal dopamine receptor signaling and dopaminergic nerve dysfunction.