In the new study, oxytocin, the "love hormone," appeared to prevent the impaired coordination experienced in drunkenness.
In our recent Valentine's Day-themed Spotlight, we took a look at the various properties of oxytocin, a hormone produced in larger amounts during acts of intimacy, including sex, holding hands, looking into another person's eyes, giving birth and nursing young.
Oxytocin is also known to interact with the reward system in the human brain in a similar way to drugs that produce euphoria and cravings such as nicotine, cocaine and heroin.
Some experts think the reason why humans hug and touch often when in a relationship is because this mechanism maintains a high level of oxytocin in the brains of people in love.
In the new study, published in the Proceedings of the National Academy of Sciences, the researchers investigated the interaction between oxytocin and alcohol in rats.
The researchers infused oxytocin into the rats' brains and then administered a dose of alcohol to the animals. Interestingly, the oxytocin appeared to prevent the impaired coordination commonly experienced in drunkenness.
Rats passed sobriety test 'with flying colors'
"In the rat equivalent of a sobriety test, the rats given alcohol and oxytocin passed with flying colors, while those given alcohol without oxytocin were seriously impaired," explains Dr. Michael Bowen, from the University of Sydney's School of Psychology and lead author of the study.
The video below shows the different behaviors of rats who had received alcohol and oxytocin, rats who had received alcohol and no oxytocin, and control rats who did not receive alcohol or oxytocin.
Dr. Bowen and colleagues found that oxytocin prevented alcohol from accessing delta-subunit GABAA receptors - brain regions implicated in the intoxicating effects of alcohol:
"Alcohol impairs your coordination by inhibiting the activity of brain regions that provide fine motor control. Oxytocin prevents this effect to the point where we can't tell from their behavior that the rats are actually drunk. It's a truly remarkable effect."
Next, the team will attempt to replicate their findings in humans. However, to do this, the researchers need to develop a method of delivering sufficient amounts of oxytocin to the brain.
"If we can do that, we suspect that oxytocin could also leave speech and cognition much less impaired after relatively high levels of alcohol consumption," Dr. Bowen says.
Although oxytocin could be effective at reducing intoxication, it will not, however, reduce blood alcohol level. "This is because the oxytocin is preventing the alcohol from accessing the sites in the brain that make you intoxicated," explains Dr. Bowen, "it is not causing the alcohol to leave your system any faster."
In separate experiments by the researchers that have been replicated by other groups of scientists, oxytocin was also found to reduce alcohol craving and consumption in both rats and humans. This finding may allay fears that an oxytocin-based drug could be developed that would encourage drinkers to consume much more alcohol.
"We believe that the effects of oxytocin on alcohol consumption and craving act through a similar mechanism in the brain to the one identified in our research," says Dr. Bowen.
The researchers hope that their findings could prompt the development of new treatments for alcohol use disorders based on oxytocin.