Years ago an anti-smoking advertisement showed a young son following behind his father and imitating all of the dad’s behaviors – including smoking a cigarette. Since then, science has shown that children not only mimic their parents’ addictive behaviors, there seems to be a genetic component as well. Now a mice study has turned some of the human research on its head. Male mice exposed to large amounts of alcohol have male offspring with little taste for booze.
Human Alcoholism Patterns Suggest Heredity Component
Human research shows that alcohol addiction is a problem that frequently repeats generation after generation in families, suggesting a biological link. So far scientists have not been able to identify a strong gene marker for alcohol addiction, although some gene variants have been linked to it.
The mouse study is interesting insofar as it examines the role of heredity in drinking behaviors. The researchers do not believe that drinking even copious amounts of alcohol mutates gene sequencing, but they do hypothesize that it may affect how the gene operates. This modification of gene activity is referred to as epigenetics. This animal study appears to confirm that an alteration in gene expression occurs, but curiously only in male offspring.
Two researchers involved with the study – Andrey Finegersh, M.D. and Ph.D. and Gregg Homanics, Ph.D. – expected to find that male mice chronically exposed to alcohol would sire offspring with heavy alcohol use tendencies, but what they actually found was the opposite.
Alcohol-Exposed Mice Sire Sober Offspring
Dr. Homanics and Dr. Finegersh exposed male mice in the laboratory to significant levels of ethanol vapor off and on for a five-week period. The mice received enough exposure each time to achieve blood alcohol levels just above the amount that would be considered the legal limit for people driving a car. After five weeks of repeated exposure the researchers then mated the male mice with female mice that had never had alcohol exposure.
After the mice bred, offspring of the pairs were compared to offspring of mated mice with no alcohol exposure on either side. The adult male sires of the alcohol-exposed fathers showed less interest in consuming alcohol and in fact opted to drink water rather than alcohol much of the time. Dr. Finegersh and Dr. Homanics also found that these offspring appeared to feel the effects of alcohol consumption more severely compared with the adult offspring of alcohol-free couplings. The mice whose fathers had been exposed to ethanol demonstrated less motor control and more drastic reductions in anxiety after consuming alcohol compared to the control offspring mice.
Thus, the results were the reverse of what the researchers had anticipated, which was that offspring of exposed fathers would have a strong preference for alcohol.
Why the Difference Between Mice and Men?
The findings are so distinct from human research conclusions that the researchers are eager to return to the lab and learn what made the outcomes so different for mice. Possible explanations include: the drinking model employed or differences that may exist between species. Of course, one other question begging further investigation: Why does father exposure affect only male offspring, not female?
According to the National Institute on Drug Abuse (NIDA) nearly one-third (28 percent) of Americans drink in a way that puts them at risk for alcoholism. A significant number of problem drinkers are young people (ages 12 to 20). Among that age group NIDA suggests there are 2 million heavy drinkers and 4.4 million binge drinkers. The number one risk factor for drinking problems in humans is family history. Youth with a family history of alcohol abuse are more apt to drink early and to become alcohol-dependent.
The study was conducted under the auspices of the University of Pittsburgh School of Medicine and appeared in greater detail in the professional online journal PLOS ONE.