In humans, vulnerability to tobacco addiction has been linked to variations in the gene encoding the α5 nicotinic acetylcholine receptor subunit, but the functional mechanisms linking gene to behaviour are unknown. Using a combination of knockout mice, lentiviral rescue, and RNAi knockdown in rats, this study shows that manipulating the levels of this subunit alters the drive to obtain nicotine, particularly at high doses that are aversive to wild-type animals. Furthermore, these subunits are implicated in the projection between medial habenula and interpeduncular nucleus in integrating negative side effects of high doses of nicotine and reward signals. It is proposed that this projection provides a negative motivational signal that limits nicotine consumption.
- Christie D. Fowler
- Qun Lu
- Paul J. Kenny