. Author manuscript; available in PMC: 2009 Jul 21.

Published in final edited form as: Physiol Rev. 2009 Jan;89(1):73–120. doi: 10.1152/physrev.00015.2008

TABLE 2.

Pharmacological evidence for distinct functional nicotinic ACh receptor subtypes in brain slices

nAChR Current Types	Putative Subunits Involved	Neuron Types Expressing nAChRs	Choline as Agonist	Cytisine as Agonist	Choline as Antagonist	MLA Inhibition at 10 nM	DHβE Block at 10 µM	MEC Block at 1 µM	Bupropion Block at 1 µM	Nicotine Inhibition	Reference Nos.
Type IA	α7	Hippocampal interneurons; midbrain dopamine neurons; neurons from olfactory bulb and cortex	Full agonist	Yes, IC₅₀ = 37 µM	Full agonist	>95%	40%	<10%	0%	IC₅₀ = 100–1,500 nM	16, 18, 25, 27, 145, 154, 316, 504
Type II	α4β2	Hippocampal SLM interneurons; midbrain dopamine neurons; neurons from thalamus, IPn, and catecholaminergic nucleus	Not an agonist Agonist	Yes, IC₅₀ = 370 µM	Partial agonist	0%	>95%	ND	14%	IC₅₀ = 20–125 nM	16, 18, 504
Type III	α3β4β2	Glutamate axons to hippocampal interneurons; neurons from MHb, IPn, and dorsal medulla	Partial agonist	Yes, IC₅₀ = 15 µM	Full agonist	0%	33%	80%	54%	IC₅₀ = 13 nM	16, 18, 527
Type IV	α2β4/α4β4	Neurons from MHb and IPn	ND	ND	Full gonist	0%	0% in MHb; 36% at 1 µM	ND	ND	ND	527

Pharmacological classification of nAChRs in the rodent brain slices is based on patch-clamp analysis. ND, not determined; MHb, medial habenula; IPn, interpeduncular nucleus.