Researchers have discovered a new link between the brain’s immune system and the desire to drink alcohol.

A team from the University of Adelaide has successfully turned off the impulse to drink alcohol in mice by giving them a drug that blocks a specific response from the immune system in the brain, the first to show a link between the brain’s immunity and the motivation to drink alcohol.

“Alcohol is the world's most commonly consumed drug and there is a greater need than ever to understand the biological mechanisms that drive our need to drink alcohol,” lead author Jon Jacobsen, a Ph.D. student in the University of Adelaide's Discipline of Pharmacology, said in a statement. “Our body's circadian rhythms affect the 'reward' signals we receive in the brain from drug-related behavior and the peak time for this reward typically occurs during the evening or dark phase.

“We wanted to test what the role of the brain's immune system might have on that reward and whether or not we could switch it off.”

The researchers gave the mice (+)-Naltrexone to block the immune receptor Toll-like receptor 4 (TLR4).

“Our studies showed a significant reduction in alcohol drinking behavior by mice that had been given (+)-Naltrexone, specifically at night time when the reward for drug-related behavior is usually at its greatest,” Jacobsen said. “We concluded that blocking a specific part of the brain's immune system did in fact substantially decrease the motivation of mice to drink alcohol in the evening.”

The results indicate that further studies are needed to fully understand the implications for drinking behavior in humans.

“Our study is part of an emerging field which highlights the importance of the brain's immune system in the desire to drink alcohol,” Senior author Professor Mark Hutchinson, Director of the ARC Centre of Excellence for Nanoscale BioPhotonics at the University of Adelaide and leader of the Neuroimmunopharmacology lab, said in a statement.

“Given the drinking culture that exists in many nations around the world, including Australia, with associated addiction to alcohol and related health and societal issues, we hope our findings will lead to further studies.”