Dopamine receptor D5 deficiency results in a selective reduction of hippocampal NMDA receptor subunit NR2B expression and impaired memory.

Pharmacological evidence associates type I dopamine receptors, including subtypes D1 and D5, with learning and memory. Analyses using genetic approaches have determined the relative contribution of dopamine receptor D1 (D1R) in cognitive tasks. However, the lack of drugs that can discriminate between D1R and D5R has made the pharmacological distinction between the two receptors difficult.