Dopamine D2 receptor (DRD2) and Dopamine D3 receptor (DRD3) (DRD2/DRD3)

Dopamine D2 and D3 receptors are G protein-coupled receptors (GPCRs) belonging to the D2-like family, characterized by their coupling to Gi/Go proteins which inhibit adenylyl cyclase and decrease intracellular cAMP levels [4, 6, 15]. These receptors are essential mediators of dopaminergic signaling in the brain, with D2 receptors primarily located in the striatum, external globus pallidus, and pituitary gland, while D3 receptors are concentrated in limbic regions such as the nucleus accumbens [6, 12, 19]. Biologically, they regulate a wide array of functions including voluntary motor control, reward-related behavior, motivation, and the inhibition of prolactin secretion [10, 14, 15]. In disease states, D2 and D3 receptor dysfunction is central to the pathophysiology of Parkinson's disease, schizophrenia, and various forms of addiction [5, 6, 18]. Dopamine agonists are pharmacological agents designed to activate these receptors, effectively mimicking the action of endogenous dopamine to treat motor deficits in Parkinson's disease and restless legs syndrome [8, 14, 20]. However, their clinical use is often limited by significant safety concerns, most notably impulse control disorders and sudden sleep attacks, which arise from the receptors' roles in the brain's reward and arousal systems [14, 20, 21]. Additionally, ergot-derived agonists have been associated with cardiac valvulopathy, leading to a preference for non-ergoline compounds in chronic therapy [14, 20].

Other names

D2RD3RD2DRD3DRDopamine receptor D2Dopamine receptor D3

Dopamine agonists activate D2 and D3 receptors, which are coupled to Gi/Go proteins [6, 15]. This activation inhibits adenylyl cyclase, leading to a decrease in intracellular cyclic AMP (cAMP) levels [4, 6, 15]. Furthermore, these receptors modulate ion channels, such as activating G protein-coupled inwardly rectifying potassium (GIRK) channels and inhibiting voltage-gated calcium channels, which collectively reduces neuronal excitability and regulates neurotransmitter release [10, 15, 17].