The old adage says that most things are fine to consume in moderation. But new research has shown that just one alcoholic drink can affect the brain in a permanent way. With fruit fly and mouse models, researchers investigated the impact of alcohol on neural synapses, where neurons meet and send signals. They found that mitochondrial and synaptic activity was altered after the administration of alcohol, and produced a rewarding effect. The findings, which have suggested that a single alcoholic drink can lay the foundation for alcohol addiction, have been reported in the Proceedings of the National Academy of Sciences (PNAS).
When scientists have studied the impact of alcohol, they have typically used models of chronic alcohol intake. This team was interested in other factors, such as initial experiences with alcohol. They were focused on molecular changes that accompanies ethanol intake, and the cellular changes that resulted after one instance of acute ethanol intoxication. The impact was examined at the molecular and behavioral levels, said Professor Dr. Henrike Scholz, to see if a positive feeling was then associated with alcohol.
Mitochondria are organelles that are popularly known as cellular powerhouses; they generate energy, along with several other crucial functions. Mitochondria in nerve cells move around so that energy is supplied efficiently. But after alcohol intake, the movement of mitochondria became disrupted. That disturbance was not temporary, either - it was permanent. There were behavioral changes that accompanied these mitochondrial alterations too; the mouse and fruit fly models increased their consumption of alcohol and had a predisposition for later relapse.
Neurons can change, and it's thought that neural plasticity is critical to learning. The researchers suggested that some of the changes that were observed might be influencing the formation of memories. Taken together with the mitochondrial changes, the study authors suggested that this may lay the basis for addiction-related behaviors, and it may be applicable to humans. A single experience with intoxication could influence alcohol intake in later in life.
"It is remarkable that the cellular processes contributing to such complex reward behavior are conserved across species, suggesting a similar role in humans," said Scholz. "It could be a possible general cellular process essential for learning and memory."
Researchers have found that the first experience of alcohol intoxication affects a person's risk for alcoholism. This study may help explain that finding, and that "identifying lasting ethanol-dependent changes is an important first step in understanding how acute drinking can turn into chronic alcohol abuse," noted Scholz.
Sources: University of Cologne, Proceedings of the National Academy of Sciences
