The research into the effects of increased FGF21 hormone, which is produced by the liver, could be key to someday treating drunkenness in humans.
Scientists have been able to quickly sober up inebriated mice by boosting their levels of a naturally produced hormone they share with humans, giving hope for a potential hangover cure.
The research, led by scientists from the University of Texas Southwestern Medical Center in the US, could be key to someday treating drunkenness in humans.
The hormone, which is called FGF21, has drawn scientists' attention for years: it is produced by the liver and plays a significant role in helping - both humans and mice - process certain foods, particularly alcohol.
Previous studies have found that FGF21 helps different species battle the harmful consequences of ethanol exposure.
The hormone suppresses the craving for alcohol in mice and monkeys when drunk, stimulates thirst for water (presumably to protect against the dehydration caused by alcohol consumption), and protects against alcohol-induced liver injury.
For humans, alcohol is the most potent inducer of the hormone.
Experiments with the drunken mice
After 15 years working with FGF21, Steven Kliewer - senior author of the study - and his team were "curious about what FGF21 might do in the context of a binge dose of alcohol… a dose that knocks them [mice] unconscious," he told Euronews Next.
The scientists set out to compare what happened after giving a single binge dose of alcohol to two different groups of mice. One group was genetically engineered to lack the hormone, and the other had normal FGF21 production.
The experiments also evaluated the outcome of giving regular mice an extra shot of the FGF21 hormone while under the influence of alcohol.
Drunkenness was defined as the loss of the "righting reflex," meaning the mouse’s ability to get upright after being placed on its back.
After being given a single binge dose of alcohol, scientists found mice from both groups metabolised ethanol at the same rate. But interestingly, those without the FGF21 hormone stayed drunk for longer.
Similarly, when the researchers gave the drunk mice an extra dose of FGF21, they sobered up faster than the others, on average an hour and a half faster.
"We were able to cause an acceleration in the recovery from intoxication," said Kliewer, "and that came as a bit of a surprise because these mice already had FGF21".
The study, published in the scientific journal Cell, also revealed that the FGF21 hormone stimulates the noradrenergic nervous system, a specific part of the brain that controls alertness.
The noradrenergic nervous system allows, for example, to protect mice against the loss of balance experienced after consuming alcohol.
“You can imagine there would be important evolutionary benefits of remaining more alert in the context of being exposed to alcohol out in the wild,” Kliewer said.
It is unlikely that a mouse or other animal would be exposed to ethanol levels that would make them unconscious, "but even low levels of alcohol can affect our judgment, our mobility," he explained.
Some animals, including mice, consume fruit and nectar that, when fermented, transforms into alcohol.
Scientists have known “for a long time” the role of the liver metabolising ethanol, "but now we know that it is also releasing this hormone that, at least in mice, acts on the brain to keep them alert," Kliewer added.
Could the experiments be replicated to sober up drunken humans?
"We are obviously very interested in doing that," he told Euronews Next.
"And a couple of pieces of evidence suggest that this pathway is likely to be present in people… the FGF21 hormone is triggered by drinking only a couple of drinks in humans. We also know that alcohol triggers the same part of the brain activated by the hormone in mice".
What remains to be proven is whether the hormone has the same positive effect in treating drunkenness in humans.
The application of the experiment in humans is "beyond the scope of our laboratory," says Kliewer, "but we hope that we'll be able to team up with clinicians to look at this in the future".
Future research will need to map the neural pathways activated in response to FGF21.
"Intoxication is not well understood, and so this provides us with a new means, a toehold, to better understand intoxication as a whole," he said.
The idea would be that physicians in emergency rooms might be able to use the hormone to protect and treat patients who come in with acute alcohol intoxication, says the study’s lead scientist.
"Ultimately, we want to benefit humanity. We're doing these experiments to try to make the world a better place," Kliewer said.