also tested and did not show a significant difference in ethanol intake when compared to wild-type controls (data not shown). An advantage of testing mice in the dark phase under limited access conditions is that mice will drink to intoxication. To confirm that the AlkKO mice drank intoxicating levels of alcohol, we tested the BEC of mice immediately following the final drinking session. Mice had blood ethanol levels greater than 0.04% (Figure 5B). Moreover, the AlkKO mice reached BEC levels significantly higher (>0.08%) than wild-type controls. To determine whether loss of Alk function might generally affect fluid consumption, we tested AlkKO mice for water intake using the same conditions used for ethanol consumption. No differences were observed between wild-type controls and AlkKO mice (Figure 5C). In conclusion, Alk negatively regulates alcohol consumption in mice without affecting general fluid consumption, suggesting that the normal function of Alk may be to curb excessive alcohol intake.
