Love may be intoxicating. But when mixed with alcohol, the hormone that love spurs in humans seems to have the opposite effect: It’s downright sobering.

A new study finds the much-ballyhooed “love hormone,” oxytocin, appears to dampen the effects of alcohol, and suggests it could someday play a role in treating alcohol dependence and withdrawal.

Oxytocin surges in new mothers, inducing childbirth and breastfeeding. In partnered men, it reduces straying behavior. When puffed up the noses of experimental subjects of all sorts, oxytocin consistently enhances trust, promotes sociability and fosters nurturing behavior. It’s even seen as a promising way to help those with autism learn social skills.

But new research finds that, in male rats at least, oxytocin also blunts the inebriating effects of moderately heavy doses of alcohol. It does so, the study found, by suppressing the activity of receptors in the brain--GABA receptors, which respond to the neurotransmitter gamma-aminobutyric acid--that are key nodes in the circuitry of reward-related behaviors and addiction.


That finding prompted the study’s authors to suggest the intriguing proposition that oxytocin might reduce cravings across a range of addictive behaviors.

To explore the interaction between oxytocin and alcohol, researchers at the University of Sydney in Australia first gave young adult male rats an infusion of oxytocin and then administered a dose of alcohol roughly equivalent to a human drinking a bottle of wine over a few hours. On a battery of tests, a comparison group of rats that got no oxytocin was clearly drunk: their movements slowed, their muscle tone failed them, and when deposited on their backs, they had difficulty in performing the usually simple act of righting themselves.

But the rats that got the oxytocin first showed virtually no signs of intoxication.

Even oxytocin did not negate the effects of a much higher dose of alcohol on the rats, however: When researchers doubled the amount of alcohol infused into mice, those treated with oxytocin lost their motor control.


The newest research comes against the backdrop of some other recent findings on oxytocin and alcohol, suggesting that the love drug also reduces alcohol consumption, cravings and withdrawal symptoms--not only in rats, but in alcohol-dependent humans as well.

Rats are not people, and until the anti-alcohol effects of oxytocin are shown in humans, its effectiveness in treating alcoholism or reversing alcohol intoxication is far from demonstrated. But if further studies bear out the properties seen in rats, it really may be that the love hormone conquors all.

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