That alcohol consumption is harmful to health is something that has been proven in numerous scientific studies, which have shown that it is a risk factor that contributes to the appearance of diseases such as various types of cancer, hepatitis, fatty liver or cirrhosis, among others. It also has very negative consequences for the brain, to the point that a single dose of alcohol (ethanol) can permanently alter the brain by changing the morphology of neurons, reveals a new study by researchers at the University of Cologne and the Universities of Mannheim and Heidelberg.
Researchers have concluded that a single dose of alcohol influences the structure of synapses and the movement of mitochondria – the powerhouses of nerve cells in the brain – and that the changes it causes influence reward learning in the brain. brain, reducing the rewarding effect of alcohol and could lead to later alcohol addiction. The study has been published in PNAS.
From sporadic alcohol consumption to dependence
The group of researchers wanted to find out what changes occur in the brain so that occasional alcohol consumption becomes chronic alcohol abuse. Most scientific studies have looked at the effects of chronic alcohol consumption on the hippocampus, the brain’s control center, and thus the acute neural interrelationships of key risk factors, such as first alcohol intoxication at at a young age, explained Dr. Henrike Scholz of the University of Cologne: “We set out to discover ethanol-dependent molecular changes. These, in turn, form the basis for permanent cellular changes after a single acute ethanol intoxication.”
“Identifying persistent ethanol-dependent changes is an important first step in understanding how acute alcohol use can evolve into chronic alcohol abuse”
To test their hypothesis, they carried out studies in the genetic model Drosophila melanogaster, a fruit fly, and in the mouse model, and identified changes caused by ethanol in two areas: the so-called mitochondrial dynamics and the balance between the synapses of the nerve cells. Mitochondria provide energy to cells – especially nerve cells – and in order to perform their function optimally, mitochondria move. The movement of mitochondria was altered in the ethanol-treated cells, and the chemical balance between certain synapses was also altered. These changes were permanently maintained and could be confirmed in the behavioral changes of the animals: mice and fruit flies consumed more alcohol and had relapses to alcohol later in life.
The morphological rearrangement of nerve cells is a well-known basis for learning and memory, and these mechanisms of cellular plasticity, which are fundamental to learning and memory, are also thought to be key to the formation of associative memories for individuals. drug-related rewards. Therefore, some of the morphological changes found could influence ethanol-related memory formation. In the researchers’ opinion, these ethanol-dependent cellular changes are crucial underpinnings for the development of addictive behaviors, along with the migration of mitochondria in nerve cells, which are also important for synaptic transmission and plasticity.
“It is remarkable that the cellular processes that contribute to such complex reward behavior are conserved across species, suggesting a similar role in humans,” says Henrike Scholz. “It could be a possible general cellular process that is essential for learning and memory.”
These two mechanisms could explain observations in mice that revealed that a single intoxication can increase alcohol consumption and alcohol relapse later in life. “These mechanisms could even be important for the observation in humans that a young age of first alcohol intoxication is a critical risk factor for subsequent alcohol intoxication behavior and the development of alcohol dependence,” explains Professor Henrike Scholz. “Identifying persistent ethanol-dependent changes is therefore an important first step in understanding how acute alcohol use can evolve into chronic alcohol abuse.”
.
