Alcohol has been a drink of choice for people for thousands of years, but scientists still do not know just how the stuff affects brain function when people become intoxicated. New research reveals that genetic change in a single nucleotide is enough to heighten alcohol sensitivity in rats and could help scientists design novel therapeutic approaches for alcoholism.

Researchers from the University of California at Los Angeles led by H. Jacob Hanchar and Paul D. Dodson tested how rats reacted to varying doses of alcohol. The team tested animals that had a naturally occurring gene mutation--a single nucleotide difference that in turn changes one amino acid in the receptor proteins for GABA neurotransmitters--and compared them to rats without the mutation. After imbibing, the animals performed a balancing task and underwent blood-alcohol testing. The animals with the mutation fell off a rolling log much sooner than the control animals did, which suggests that the mutation left them much less tolerant to alcohol's effects. Although the blood-alcohol levels of the mutants (which were equivalent to those of the control animals) indicated that they should have been slightly intoxicated , their behavior was significantly more impaired.

GABA receptors in humans and rats are very similar and the fact that the mutation occurs naturally suggests that people, too, may be genetically predisposed to be hypersensitive to alcohol's effects. Study co-author Thomas Otis notes that the findings could guide researchers in their quest to develop new drugs for treating alcohol addiction or for acute cases of alcohol poisoning. The findings appear online today in the journal Nature Neuroscience.

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