Neuroscientists don’t fully understand the mechanisms in the brain that drive people to drink alcohol compulsively. But researchers have now learned that reducing expression of one protein, an ion channel subunit, can increase binge drinking in mice (Proc. Natl. Acad. Sci. USA 2015, DOI: 10.1073/pnas.1416146112). Candice Contet of Scripps Research Institute California and colleagues studied mice genetically engineered to not produce GIRK3, one member of a family of potassium ion channels. The team set up what Contet calls a mouse happy hour: For two hours every day, the researchers added a bottle filled with an ethanol solution to the animals’ cages. Over several days, the mice started to binge drink from the ethanol bottle and get tipsy, with GIRK3-free mice drinking 30% more than unmodified mice. The scientists could curb the modified mice’s drinking by injecting a virus containing the GIRK3 gene into the ventral tegmental area (VTA) of the brain. This region is part of the brain circuitry that controls reward-seeking behavior. How the loss of GIRK3 leads to increased bingeing is still unknown, but Contet’s team showed that, unlike in unmodified mice, GIRK3-free VTA neurons do not respond to ethanol.