Dopamine D2, D3, and D4 receptors (D2R, D3R, D4R)

Dopamine receptor D2, D3, and D4 are integral membrane proteins and part of the D2-like dopamine receptor subfamily. All are G protein-coupled receptors (GPCRs) characterized by seven transmembrane domains and by their coupling to Gi/o proteins, which inhibit adenylyl cyclase and reduce intracellular cAMP. They are widely expressed in the central nervous system and peripheral tissues. D2 receptors exist in short (presynaptic, autoreceptor) and long (postsynaptic) isoforms. D3 and D4 are less abundant, with D3 mainly in the limbic regions and D4 highly variable, especially in the prefrontal cortex and hippocampus[1][2][4][5][6][7]. These receptors are critical regulators of motor control, mood, cognition, neuroendocrine function, and are primary drug targets in schizophrenia, Parkinson's disease, and other neuropsychiatric disorders. Numerous antipsychotic drugs act by blocking D2 receptors, and ongoing research targets D3 and D4 for more selective therapies with fewer adverse effects. Genetic variations in DRD4, especially the D4.7 allele, are linked to increased risk for ADHD and possibly other behavioral traits[4][7].

Other names

D2-like dopamine receptorsD2 receptorDRD2D3 receptorDRD3D4 receptorDRD4Dopamine receptor subtype D2/D3/D4

Antagonism or inverse agonism (block dopamine binding, reducing dopamine signaling); Partial agonism (some antipsychotics, e.g., aripiprazole); Modulate cAMP pathway via Gi/o proteins; Autoreceptor inhibition (D2-short pre-synaptically); Affect potassium channels and downstream neurotransmitter release