A Link Found Between the Brain’s Immune System and Nighttime Alcohol Cravings

Researchers at the University of Adelaide found a link between the brain’s immune system and the desire to drink alcohol. Brain, Behavior, and Immunity published this study, one of the first investigations to show a link between the brain’s motivation to drink alcohol at night and brain immunity.

In a study using laboratory mice, researchers were able to stop the desire to drink alcohol by administering a drug that blocked a specific response from the immune system in the mice’s brains.

This is an important study helping us understand the biological mechanism driving the need to consume alcohol, described as the world’s most widely consumed addictive substance.

The Desire to Drink Alcohol Is Greater in the Dark

Our body’s circadian rhythm affects the functioning of the brain’s reward center and immune system. Reward-related behaviors and immune responses have been found to be more active in darkness. Both the brain’s reward behavior and immune response have a shared element: Toll-like receptor 4 (TLR4)!

Toll-like receptor 4 is a protein located in the cell membrane and encoded by the TLR4 gene. The main function of this protein receptor is to recognize harmful microorganisms, activate the immune system and initiate inflammation . This receptor is also known to be responsible for the effects of opioid painkillers sold with red and green prescriptions (such as morphine), and for the tolerance (reduced effectiveness) that develops to these drugs over time. Therefore, for example, drugs (antagonists) that inhibit TLR4 function are used in opioid poisoning or overuse. An example of these antagonist drugs is naloxone. Naloxone is an intravenously administered TLR4 blocker; Ethylex, the tablet form of naltrexone, a drug similar to naloxone, is also used in treatments for alcohol and substance dependence.

It is interesting that TLR4 is related to both pleasure and the immune system. Interpreting this relationship, it appears that excessive stimulation of pleasure may lead to chronic inflammation and inflammation-related health problems, while insufficient stimulation may lead to a weakened immune system (for example, shingles).

In the study, to identify the role of the brain’s immune system in the desire to drink alcohol and to try to switch off the reward mechanism, a different TLR4 antagonist was used: “(+) - Naltrexone”

In conclusion, this study found a relationship between the immune system and nighttime motivation to drink alcohol for the first time. After (+)-Naltrexone was administered to mice, a significant decrease in alcohol-drinking behavior was observed, especially at night. In other words, blocking part of the brain’s immune system was found to significantly reduce mice’s motivation to drink alcohol in the evenings. This study represents a promising development for health and measures against alcohol dependence.

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