One of the great pastimes of the human species is getting together to have a couple of beers after work, going out for cocktails on the weekend, or ending your evening with a nightcap before bed. Alcohol is a part of many cultural norms, and is fine in moderation, but could promote health problems down the line if consumed in excess too often, or too early.
American adults of both sexes are no strangers to binge drinking; one out of every six Americans reports binge drinking four times per month, with a single binge-drinking episode involving approximately seven drinks. In fact, over 90% of Americans who say they drink excessively report having had a binge-drinking episode in the past month.
While binge drinking is twice as common in men, new research out of the University of Missouri School of Medicine suggests that women are more susceptible to liver injury, due to how it affects their epigenetics.
The Centers for Disease Control and Prevention highlight binge drinking as a serious public health problem, and call it out as the most expensive and dangerous pattern of excessive alcohol use. The worst part is that binge drinking among women is on the rise.
While previous studies had identified women as being more susceptible to alcoholic liver injury, gender differences in the harmful effects resulting from binge drinking have not been characterized until now.
In Vivo Alcohol Studies on Rats Illuminated Differences Between the Sexes
Dr. Shivendra Shukla and his team looked at a small cohort of four male and four female rats, to which they administered alcohol at 12-hour intervals three times. This was intended to mimic binge drinking episodes. Blood and liver tissue samples were then inspected four hours after the last binge drinking episode.
Despite the small sample size and relatively limited scope of binge drinking—closer to a one-time incidence versus the ongoing pattern of behavior present in adult humans—the findings were statistically significant. The female rats already had four times as much fatty build-up in the liver as did the male rats, which is important because fatty build-up in organs like the liver is a precursor for further inflammation and damage.
Dr. Shukla took this a step further and also looked at expression levels of particular proteins tied to chronic illness. Although there were alterations in the expression levels of several different proteins, most shockingly, diacylglycerol kinase-alpha (DGKa)—known to promote cancerous tumor growth—was elevated by 20% in males and by a whopping 95% in females.
Epigenetic Modifications Result from Binge Drinking, But Further Study is Needed
What is driving these changes in expression levels? Because of the relatively short timescale involved, it’s not like the fundamental genetic code was being changed; instead, something about the way this code is being translated into proteins in the rats’ cells is being changed. This led Dr. Shukla’s team to examine histone modifications. What they found is that in both sexes, the levels of acetylated H3AcK9 were increased, with this site being tied to oxidative stress.
It makes sense that epigenetic modifications are contributing to the individual responses to binge drinking. But while protein expression levels were found to differ between the sexes, there were no differences noted between the sexes in terms of histone modifications, at least under the sites studied by Dr. Shukla’s team. Further study is needed to pinpoint exactly what sequence of events takes place—and how it differs between males and females—to result in the stark contrast of physiological response to binge drinking. Increasing sample size will also be important to validating the data, as well as ultimately studying these patterns in humans, where the epigenetic sequence of events might be more nuanced and distinct than that observed in rats.
Source: Shukla S, et al. (2019) Binge Alcohol Is More Injurious to Liver in Female than in Male Rats: Histopathological, Pharmacologic, and Epigenetic Profiles. Journal of Pharmacology and Experimental Therapeutics.
Reference: Univ. of Missouri School of Medicine. Binge Drinking May be More Damaging to Women MUSOM Research News. 16 Aug 2019. Web.