The effect of varenicline on binge-like ethanol consumption in mice is β4 nicotinic acetylcholine receptor-independent.

BACKGROUND: Our laboratory has previously shown that the smoking-cessation agent varenicline, an agonist/partial agonist of α4β2*, α3β4*, α3β2*, α6β2* (* indicates the possibility of additional subunits) and α7 subunits of nicotinic acetylcholine receptors (nAChRs), reduces ethanol consumption in rats only after long-term exposure (12 weeks). As compounds having partial agonistic activity on α3β4* nAChRs were shown to decrease ethanol consumption in rodents, we assessed here the involvement of the β4 subunit in the effect of varenicline in the reduction of short- and long-term binge-like ethanol drinking in mice.
METHODS: We used the well-validated drinking-in-the-dark (DID) paradigm to model chronic binge-like ethanol drinking in β4-/- and β4+/+ littermate mice and compare the effect of intraperitoneal injection of varenicline (2mg/kg) on ethanol intake following short- (4 weeks) or long-term (12 weeks) exposure.
RESULTS: Drinking pattern and amounts of ethanol intake were similar in β4-/- and β4+/+ mice. Interestingly, our results showed that varenicline reduces ethanol consumption following short- and long-term ethanol exposure in the DID. Although the effect of varenicline on the reduction of ethanol consumption was slightly more pronounced in β4-/- mice than their β4+/+ littermates no significant differences were observed between genotypes.
CONCLUSION: In mice, varenicline reduces binge-like ethanol consumption both after short- and long-term exposure in the DID and this effect is independent of β4 nAChR subunit.