Binge drinking, where large amounts of alcohol is drank in a short period of time, could be linked to a brain protein. The study, published in the journal Proceedings of the National Academy of Sciences, found that deleting this brain protein in mice increased binge-drinking behavior.
Scientists at The Scripps Research Institute (TSRI) studied the role of GIRK (G protein-gated inwardly rectifying potassium channels) on the behavioral effects of ethanol. GIRK channels can be found throughout the nervous system and control the excitability of neurons, reducing the likelihood of them firing off. Knowing GIRK channels can be ‘activated’ by alcohol, researchers examined the behavioral effects in genetically modified mice with and without GIRK3 channels; a sub-unit of GIRK.
The study set up a mock ‘happy hour,’ where mice were only allowed to drink ethanol for two hours a day. During this period, the mice without GIRK3 consumed a lot more alcohol than those with GIRK3. When researchers allowed both groups of mice to drink alcohol anytime throughout the day, they found no difference in overall consumption, which suggests GIRK3 could be specifically associated with binge drinking.
“Alcohol hits a lot of different targets in our brain, which makes disentangling the in vivo effects of alcohol quite complicated,” said TSRI biologist Candice Contet, senior author of the study, in a statement. “Our study sheds light on the molecular mechanisms implicated in binge drinking.”
Researchers found that once alcohol was introduced to mice without GIRK3, the neural pathways that mediate reward-seeking behavior, which originates in the ventral tegmental area (VTA) of the brain, became insensitive to the activating effect of alcohol. Researchers suggest that mice without GIRK3 could be binge drinking ethanol to boost alcohol’s rewarding effect in other neural pathways.
“The dramatic effect of GIRK3 deletion on the ability of alcohol to excite VTA neurons was surprising,” said Melissa Herman, a research associate in the laboratory of TSRI Professor Marisa Roberto and first author of the study, in a statement. “Even when applied at a very high concentration, alcohol was unable to alter the firing of neurons missing GIRK3.”
The study suggests GIRK3 could be ‘critical gatekeepers’ and that a removal of GIRK3 could promote the motivation to seek the rewarding effects of alcohol, leading to binge drinking. When researchers reintroduced GIRK3 into the mice without it, they consumed less alcohol.
Binge drinking is defined by the National Institute on Alcohol Abuse and Alcoholism as having a blood alcohol concentration of 0.08 grams percent or above. For men, this is drinking five or more drinks, and for women it’s four or more, in a two hour period. While drinking in moderation is fine, drinking in excessive amounts can lead to serious health complications, such as alcohol poisoning, cardiovascular disease and liver disease.