Nicotinic acetylcholine receptors containing the ?4 subunit modulate alcohol reward.

ABSTRACT: Nicotine and alcohol are the two most co-abused drugs in the world, suggesting a common mechanism of action might underlie their rewarding properties. Although nicotine elicits reward by activating ventral tegmental area dopaminergic (DAergic) neurons via high-affinity neuronal nicotinic acetylcholine receptors (nAChRs), the mechanism by which alcohol activates these neurons is unclear.Because most high-affinity nAChRs expressed in ventral tegmental area DAergic neurons contain the ?4 subunit, we measured ethanol-induced activation of DAergic neurons in midbrain slices from two complementary mouse models, an ?4 knock-out (KO) mouse line and a knock-in line (Leu9'Ala) expressing ?4 subunit-containing nAChRs hypersensitive to agonist compared with wild-type (WT). Activation of DAergic neurons by ethanol was analyzed with both biophysical and immunohistochemical approaches in midbrain slices. The ability of alcohol to condition a place preference in each mouse model was also measured.At intoxicating concentrations, ethanol activation of DAergic neurons was significantly reduced in ?4 KO mice compared with WT. Conversely, in Leu9'Ala mice, DAergic neurons were activated by low ethanol concentrations that did not increase activity of WT neurons. In addition, alcohol potentiated the response to ACh in DAergic neurons, an effect reduced in ?4 KO mice. Rewarding alcohol doses failed to condition a place preference in ?4 KO mice, paralleling alcohol effects on DAergic neuron activity, whereas a sub-rewarding alcohol dose was sufficient to condition a place preference in Leu9'Ala mice.Together, these data indicate that nAChRs containing the ?4 subunit modulate alcohol reward.

SUBMITTER: Liu L 

PROVIDER: S-EPMC4501776 | biostudies-literature | 2013 Apr

REPOSITORIES: biostudies-literature