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Even a Little Alcohol Affects the Brain

Receptors found impact impairment from moderate drinking

MONDAY, Nov. 17, 2003 (HealthDayNews) -- Even low levels of alcohol can impair brain function, says a study that found the specific areas affected by amounts of alcohol tantamount to social drinking.

Low levels of alcohol affect motor coordination, memory and lower social inhibitions at a blood alcohol level of 0.01 percent, far below the legal drinking and driving limit of 0.08 percent, says lead researcher Dr. Richard Olsen, a professor of pharmacology at the University of California at Los Angeles. "This is the effect one or two drinks will have," he adds.

In experiments with gamma aminobutyric acid (GABA) receptors in animal cells, Olsen and his colleagues found some receptors, namely GABA receptors with a beta-3 subunit and a delta subunit, responded when exposed to low levels of ethanol.

These GABA receptors responded to low levels of alcohol compared with other GABA receptors with subunits, such as gamma-2, that respond to much higher levels, far higher than achieved in social drinking, Olsen says.

The GABA receptors that respond to low levels of alcohol are in cellular areas and brain regions that control the effects of alcohol on behavior, he notes.

These areas include the cerebellum, which controls motor coordination, the hippocampal formation, which affects memory loss, and the thalamus, which is involved with sleep and effects of anesthetics.

The report appears in this week's issue of the Proceedings of the National Academy of Sciences.

Olsen says some of these receptors have not been tested for reaction to alcohol before. These receptors are also being looked at to see the effects of anesthetics.

This finding is useful because researchers may be able to effect the action of alcohol if they know exactly how it works at the molecular and cellular level on GABA receptors, he adds.

It is possible the changes that occur in the brain after chronic abuse of alcohol can involve changes in these receptors, and this may help scientists understand alcohol dependence and abuse. Researchers have some evidence that GABA receptors are indeed modified by continued exposure to alcohol, Olsen notes.

Currently, Olsen's team is taking the next step by trying to duplicate their findings in rats.

"If we understand the action of alcohol at the cellular and molecular level, it is helpful in treating the bad effects that alcohol may have," Olsen says.

"We may be able to develop antidotes or treatments for intoxication or overdoses and coma and life-threatening effects as well as being able to understand and treat alcohol abuse," he adds.

Dr. H. Scott Swartzwelder, a professor psychiatry of at Duke University, comments, "We have always known that alcohol has some kind of effect on GABA function, because GABA is involved in learning and sleep."

The results of this study are compelling because it shows concentrations that are relevant to the human experience, and there may be a specific target that will let researchers study the effects of alcohol, Swartzwelder adds.

"This is important because alcohol is a very dirty drug: it doesn't just do one thing; it affects many types of receptors in the brain," he says. "This finding could lead to the development of drugs that could block or reverse some of the effects of alcohol."

"We have hoped for a long time to find a drug that would counteract the acute effects of alcohol and also the chronic effects of alcohol. Chronic alcohol use does change the ways the GABA system works, and it stays changed. Knowing how alcohol affects the GABA system may lead to drugs that can reverse these changes," Swartzwelder speculates.

More information

To learn more about how alcohol affects the brain and alcohol abuse, visit the National Institute on Alcohol Abuse and Alcoholism or the American Medical Association.

SOURCES: Richard Olsen, Ph.D., professor, pharmacology, School of Medicine, University of California, Los Angeles; H. Scott Swartzwelder, Ph.D., senior Research career scientist, U.S. Department of Veterans Affairs, and professor, psychiatry, Duke University, Durham, N.C; Nov. 17-21, 2003, Proceedings of the National Academy of Sciences
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