TABLE1.

Classification, function, and localization of dopamine receptors in the brain as well as the relevant signaling pathway.

	Dopamine receptor subtypes
	D1-like receptor		D2-like receptor
	D1 receptor	D5 receptor	D2 receptor	D3 receptor	D4 receptor
Second messenger effect	Increase AC	Increase AC	Decrease AC	Decrease AC	Decrease AC
Cognate G protein	Gαs/olf	Gαs/olf	Gαi/o	Gαi/o	Gαi/o
cAMP production	Stimulate	Stimulate	Inhibit	Inhibit	Inhibit
Localization	Striatum	Ventral tegmental area	Nucleus accumbens	Olfactory nodules	Prefrontal cortex
	Nucleus accumbens	Striatum	Olfactory nodules	Nucleus accumbens	Anterior motor cortex
	Prefrontal cortex	Thalamus	Striatum	Striatum	Cingulate cortex
	Substantia nigra	Hippocampus	Islands of Calleja	Amygdala	Substantia nigra
	Amygdala	Olfactory nodule	Substantia nigra	Hypothalamus	Hypothalamus
	Hippocampus	Substantia nigra	Ventral tegmental area	Islands of Calleja	Hippocampus
	Thalamus		Hippocampus	Ventral tegmental area	Caudate nucleus
			Pituitary	Basal ganglia	Nucleus accumbens
				Prefrontal cortex	Ventral tegmental area
Relevant pathway	cAMP/PKA signaling	cAMP/PKA signaling	cAMP/PKA signaling	cAMP/PKA signaling	cAMP/PKA signaling
	DARPP-32 signaling	DARPP-32 signaling	DARPP-32 signaling	DARPP-32 signaling	DARPP-32 signaling
	ERK signaling	ERK signaling	GSK-3β signaling	GSK-3β signaling	GSK-3β signaling
	MAPK signaling	MAPK signaling	PI3K/AKT signaling	PI3K/AKT signaling	PI3K/AKT signaling

Note: AC, Adenylyl cyclase; cAMP, cyclic adenosine monophosphate; PKA, protein kinase A; DARPP-32, dopamine- and cAMP-regulated neuronal phosphoprotein; ERK, Extracellular signal-regulated kinases; GSK-3β, Glycogen synthase kinase-3beta; MAPK, mitogen-activated protein kinases; PI3K, phosphoinositide 3-kinase; Akt, protein kinase B.