The D1-like receptors (D1, D5) are most common in striatum, caudo-putamen, nucleus accumbens, SN pars reticulata, or olfactory bulb. These receptors play a role in the reward system, locomotor activity, learning, and memory. By the activation of guanosine nucleotide-binding proteins (G proteins), D1 receptors foster the simulation of adenylyl cyclase (AC), and also generate cyclic AMP for its secondary messengers. D1 receptors are also linked with neuropsychiatric disorders.