Table 3.

Summary of the brain regions that demonstrate a significant density of each nAChR subunit throughout the mammalian brain.

Subunit	Brain region	Reference
α2	interpeduncular nucleus hippocampus subiculum	(Wada et al., 1989)
α3	medial habenula entorhinal cortex thalamus hypothalamus ventral tegmental area	(Wada et al., 1989; Champtiaux et al., 2002)
α4	amygdala hippocampus hypothalamus medial habenula substantia nigra pars compacta	(Wada et al., 1989)
α5	interpeduncular nucleus ventral tegmental area substantia nigra pars compacta	(Wada et al., 1990)
α6	substantia nigra pars compacta ventral tegmental area locus coeruleus medial habenula interpeduncular nucleus	(Le Novere et al., 1996)
α7	amygdala hypothalamus hippocampus	(Seguela et al., 1993)
α8	not expressed in mammalian brain?	(Gotti et al., 1997)
α9	not expressed in mammalian brain?	(Park et al., 1997)
α10	not expressed in mammalian brain?	(Elgoyhen et al., 2001)
α2	Thalamus substantia nigra pars compacta ventral tegmental area entorhinal cortex	(Wada et al., 1989)
α3	ventral tegmental area substantia nigra pars compacta thalamus medial habenula	(Deneris et al., 1989)
α4	interpeduncular nucleus medial habenula	(Wada et al., 1989)