Alcohol, like any other substance that reinforces behaviour, such as another drug of abuse or even food, has a certain capacity to enhance social memory, that is, the ability to remember other individuals. If a mouse is administered alcohol immediately after being introduced to another animal of its own kind, the former will recognise the latter sooner.
This phenomenon, which has significant implications when it comes to understanding the process underlying alcohol addiction, does not have a definitive explanation. However, a team of researchers from the Psychobiology Department at the University Jaume I (Spain) has revealed a part of the mystery, since they have proved that the substance responsible for enhancing social memory is not ethanol, but another compound derived from alcohol metabolism in the brain, namely, acetaldehyde.
The UJI team, headed by Psychobiology Professor Carlos González Aragón, has been working for years conducting experiments to prove that alcohol is metabolised not only in the liver but also in certain areas of the brain where important amounts of ethanol are processed through the action of an enzyme known as catalase. The substance derived from these reactions, acetaldehyde, is involved in many of the changes of behaviour typically associated to alcohol. Catalase metabolises alcohol in the brain and gives rise to a certain amount of acetaldehyde that, according to the researchers, would be responsible for the effects attributed to ethanol. If substances that enhance the action of catalase are administered, a higher production of acetaldehyde and a boost in its effects are observed, while acetaldehyde and most of the effects of ethanol are not produced when catalase inhibitors are used after having consumed a certain amount of alcohol.
Up to now, however, researchers had proved that brain catalase was involved in the stimulating effect of ethanol, but its role in complex cognitive processes such as learning and memory had not been dealt with. The work that we are now bringing to light, and which is the main point in the thesis of researcher Héctor Marín, proves this involvement. By administering catalase enhancers and inhibitors to mice, Marín has shown how the enzyme intervenes in the reinforcement of social memory.
“This is the first study that demonstrates that the manipulation of brain catalase activity and, therefore, the presumable production of acetaldehyde in the brain, modifies the effects of ethanol on memory. In other words, the facilitating effect that ethanol has on social memory needs to previously metabolise it into acetaldehyde with the mediation of the catalase enzyme in the brain”, explains Héctor Marín.