How drinking affects brain stem cells

We all know that too much alcohol is bad for us, but do we know what it actually does to our brains? New research suggests that long-term, heavy alcohol consumption kills off brain stem cells, which play a key role in supporting healthy cognitive function.

According to data provided by the National Institute on Alcohol Abuse and Alcoholism (NIAAA), in the United States, approximately 88,0008 adults die each year due to alcohol consumption. The NIAAA add that alcohol is "the third leading preventable cause of death" in the country.

Research has also repeatedly tied alcohol abuse with the risk of developing liver disease, as well as with neurodegeneration.

And now, researchers are investigating the impact of alcohol on neural stem cells (NSCs), which are undifferentiated cells in the central nervous system that have the ability to specialize as and when needed.

Dr. Ping Wu — from the University of Texas Medical Branch in Galveston — and team performed a series of experiments involving mice. They found that alcohol alters NSC differentiation and affects cell survival. They also noticed a different impact in females compared with males.

"The discovery that the adult brain produces stem cells that create new nerve cells provides a new way of approaching the problem of alcohol-related changes in the brain," says Dr. Wu.

"However, before the new approaches can be developed, we need to understand how alcohol impacts the brain stem cells at different stages in their growth, in different brain regions, and in the brains of both males and females."

Dr. Ping Wu

The study's results were recently published in the journal Stem Cell Reports.

Alcohol attacks stem cells

To study the fate of NSCs in laboratory mice exposed to long-term alcohol consumption, the team used the latest genetic inducible fate mapping techniques. These provide a means of observing what happens to NSCs over time, including how the cells migrate and how they become specialized.

They found that, of the subventricular zone, the subgranular zone, and the tanycyte layer — the three brain regions known or believed to contain NSCs — the subventricular zone of the lateral ventricles was the one most affected by chronic exposure to alcohol.

In this region, the stem cells "were most susceptible to the effects of ethanol," which disrupted their process of differentiation.

However, Dr. Wu and team note that chronic alcohol consumption appeared to kill most NSCs. After long-term exposure, the pool of stem cells had greatly decreased across the board.

Females most exposed

Additionally, the researchers found that female mice were more susceptible to the effects of excess alcohol than their male counterparts.

"Ethanol females displayed more severe symptoms of intoxication and escalated in severity at a higher rate than males," the study authors report.

Not only that, but the number of stem cells was also reduced more drastically in the brains of females compared with those of males.

"Probably the most interesting finding from this work," the authors say, "is that regional location and sex played pivotal roles in determination of NSC response to ethanol consumption."

Still, certain underlying mechanisms and reasons behind the greater susceptibility of females to alcohol require further investigation.

"If males and females produce varying levels of ethanol metabolites [the enzymes that help break down alcohol molecules in the system], these metabolites could be affecting the [central nervous system] more than males," the authors say.

In future studies, the team hopes to reveal more information about the mechanism at play in the interaction between alcohol and NSCs. This would allow them to uncover better strategies for addressing alcohol abuse.