BI215-A: Principles of Genetics

Consuming alcohol leads to epigenetic changes in brain memory centers

Neuroscience News: https://neurosciencenews.com/alcohol-epigenetics-memory-15113/amp/

Egervari, PM. (2019) Alcohol metabolism contributes to brain histone acetylation. Nature. Retrieved from https://www.nature.com/articles/s41586-019-1700-7

Microbe that got man drunk could help explain common liver disease: https://www.sciencemag.org/news/2019/09/microbe-got-man-drunk-could-help-explain-common-liver-disease

Rios-Covian, D. (2016) Intestinal Short Chain Fatty Acids and their Link with Diet and Human Health. Front. Microbiol. 7:185. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4756104/

HISTONE ACETYLATION

Very recently, it was discovered in a study done by the University of Pennsylvania, that a breakdown product of alcohol (called acetate) is able to alter proteins that regulate DNA function in the brain’s learning system, in a mouse model. The breakdown of alcohol in the liver results in a high level of acetate in the blood. Neurons are able to undergo histone acetylation, a form of epigenetic marking. If this marking occurs in the learning center of the brain, it can have an effect on behavior.

It has long been known that recovering/recovered alcoholics can be triggered into a drinking relapse by everyday experiences which remind them of alcohol use. However, it has not been known how this occurs biologically.

ALCOHOL EXPERIMENT & FUTURE THERAPIES

This study shows that alcohol can upregulate the expression of certain genes, ultimately affecting how mice behave when given alcohol reward cues. After a training period where mice were given alcohol, and their neural histones were acetylated, the mice showed a future preference for the alcohol stimulus as opposed to a neutral stimulus. Without the neural histone acetylation, the alcohol preference was not observed. This latest study suggests a direct link between alcohol use and gene regulation in neurons, through histone acetylation.

Even more, in a pregnant mouse model, exposure of radioactively labelled alcohol revealed histone acetylation in the developing fetal brain.

The enzyme that deposits the acetyl groups onto neural histones, ACSS2, is now a target of possible human drug therapy, in an attempt to limit alcohol cravings in recovering alcoholics.

GUT MICROBIOME

In an interesting twist, certain species of bacteria found in the gut microbiome naturally make acetate as a by-product. In addition to acetate, bacteria can also make butyrate and propionate. These bacterial products are called short-chain fatty acids, or SCFAs. SCFAs are commonly used as an energy source or as signaling molecules for the host, as well as a factor that shapes the gut microbiome population. The Bacteroides genus is one common producer of acetate. Klebsiella pneumoniae is another species of bacteria able to make acetate.

DRUNK OFF OF GLUCOSE

A recent study published revealed that people with certain strains of K. pneumoniae that ferment high amounts of alcohol within their gut can actually have high blood alcohol levels without ever consuming a drop of alcohol! These people typically suffer from nonalcoholic steatohepatitis (NASH) or Non-alcoholic fatty liver disease (NAFLD). When these individuals consume large amounts of glucose or carbohydrates, like the amount in a soda, they become the most intoxicated. They also present with a 900-fold increase of K. pneumonia in their stool samples.

1 +1 = 2

So, if someone has a gut microbiome enriched for Klebsiella pneumonia or Bacteroides genus bacteria, could it be possible that consumption of carbohydrates and/or glucose/fructose/sucrose is epigenetically marking their learning neurons and altering their behavior to crave the foods/beverages that induce higher acetate levels?

For this forum, I want you to reflect on your own personal food choices and preferences. Do you prefer salty snacks or sweet snacks? Do you crave bread or sugar? Or, potato chips and French fries? Now, think about your immediate family. What are their food/behavior/addiction patterns? (By the way, you share inherited bacteria from them). For example, I grew up with a Mom who constantly baked sweets. This was to satisfy her cravings, but it influenced our family who also consumed them as children. Think about the disease patterns you see in your family as they age. Maybe they have addictions. You do not have to share personal information, just reflect on this ;)

Now, if it’s possible that these addictions/patterns are learned through epigenetic tagging, what can you do to protect yourself from the same future diseases/addictions? How do you think this might affect your children one day if you decide to have biological children? Can your food/beverage selections now potentially affect the behavior and even diseases your children might have? Could this information potentially influence your decision to consume alcohol in the future? Due: Monday, 4/13/2020 at 11:59 pm.

Note: you can use the references I listed at the beginning, if you do not have any other to contribute for your answer!