Vulnerability to addictions lies in a delicate brain balance between the functions of the limbic system, where impulses occur, and the cerebral cortex, which controls rational activity.
In the case of food dependence, a group of epigenetic markers (those capable of modifying genes) called microRNAs, which are small RNA molecules that regulate gene expression in a complex manner, function in this area.
A team of Spanish scientists, led by Rafael Maldonado López of Pompeu Fabra University in Barcelona, Spain, identified these markers, first in a mouse model and then in humans, which are involved in compulsivity, motivation, and resistance to punishment, behaviors associated with food addiction.
Maldonado gave a distance lecture at the Seminar on Neurosciences and Addictions of the Cannabinoids Laboratory of the Faculty of Medicine of the UNAM, whose presentation was in charge of the professor of that academic entity, Óscar Prospero García.
"The criteria for food addiction is defined based on the criteria for drug addiction, in that behavioral alteration. It consists of persistence to the response, the insistence in the food search, with an enormous motivation and consumption despite its negative consequences," Maldonado Lopez said.
He explained that in the study they compared two populations of mice, one addicted to food and the other not, and found microRNAs with higher expression in the addicted rodents. When they replicated the study in humans, they identified that the same microRNAs affected in those animals were also altered in people.
"The similarities between the results in mice and humans bring great importance to the study, as the role of epigenetics in vulnerability to food addiction opens the door to be able to identify biomarkers for early diagnosis, and to be able to develop future therapies by modifying the expression of microRNAs," he said.
The three markers identified are miR 29C, miR 137, and miR 665, and it was shown that the expression of these molecules is associated in both groups (mice and humans) with food addiction.
In the first part of the research, the Spanish scientists detected the neurobiological mechanisms that allow the development of food addiction behavior. Specifically, certain cortical areas in the brain are involved in the loss of control of meal intake.
The experts wondered why there are resilient individuals, while others are addicted. They found the answer in epigenetic factors, i.e. those external to the environment that modify gene expression.
In a study currently in progress, Maldonado and his collaborators are studying the intestinal microbiota, specifically the function of some bacteria present in our body that are related to food addiction.
So far, they have found that there is a relationship between the gut and the brain and that the microbiota could contribute to some specific brain functions.