HEALTH

How addiction happens

RUNNING into a former drinking buddy or passing a once-favourite bar can cause recovering alcoholics to relapse.
But the biology behind why those setbacks happen was a mystery to scientists until just recently.
Researchers from the Perelman School of Medicine at the University of Pennsylvania, United States, found that alcohol directly affects the brain’s learning and memory system through a test on mice.
Drinking actually helps people’s brains “learn” alcohol – the bar they’re drinking in, the street they’re on and the people they’re with – said Dr Shelley Berger, a cell and developmental biology professor, who is the study’s senior author.
This learning can make people want to drink more when they’re in certain environments or with groups of people.
And unravelling how the learning happens opens the possibility of someday having treatments to block that action.
Prof Berger’s research is the latest addition to a growing body of research that alcohol and drugs can cause genetic changes that may reinforce addiction and affect future generations.
Earlier this year (2019), researchers from Rutgers University found that binge drinking can trigger genetic changes that make people crave alcohol even more.
In the new study, published recently in the journal Nature, researchers found that when alcohol is consumed, it goes to the liver, where it’s processed into the by-product acetate.
Acetate then travels to the brain, where it turns certain genes on and off in a cell by attaching to histones, the proteins that package DNA in a cell’s nucleus, said Prof Berger.
“DNA is about two feet long in every cell and it’s all folded up into the nucleus,” she said.
“There’s a packaging material that organises it in a really orderly way, and it turns the right genes on and off through these little chemical groups. Acetate is one of those chemical groups.”
It turns out that the enzyme responsible for depositing acetate into cells, called ACSS2, activates key memory genes important for learning.
To test this, researchers exposed mice to two differently patterned chambers – one with alcohol and one without.
After a “learning period”, the mice were allowed to roam freely between the two. They preferred the chamber that was paired with alcohol.
But after lowering the levels of ACSS2 in the mice’s brains, the researchers found that they spent an equal amount of time in both chambers.
Researchers also found that when a pregnant mouse consumed alcohol, acetate was delivered through the placenta and into the foetus’ developing brain.
This finding could lead to better understanding of foetal alcohol syndrome, said Prof Berger.
She said that this was the first empirical evidence showing that alcohol consumption affects how genes are expressed in the brain.
She’s now interested in using the information to make a drug that could be used to stop people from “learning” alcohol.
“When we learn something, there’s a process called reconsolidation,” Prof Berger said.
“That’s when something is really solidified and we feel that we really understand it now.
“We want to disrupt that after someone has been exposed to alcohol, but before they reconsolidate the information.”
Penn’s Center for Studies on Addiction director Dr Henry Kranzler said Prof Berger’s research is “intriguing” because it offers the potential of “filling in a missing piece in our understanding of the development and maintenance of heavy drinking”.
“Her research is consistent with the idea that addiction is a learned process,” he said.
“Importantly, it opens up the potential to identify specific targets in the brain to be modified therapeutically with medications, and perhaps also genetically, at some point.”
In other words, researchers may be able to make drugs to treat addiction that target specific areas of the brain that are affected by alcohol. – The Philadelphia Inquirer/Tribune News Service

‘Genetically wired’ to avoid veges

HATE eating certain vegetables? It could be down to your genes, say United States scientists who have done some new research.
Inheriting two copies of the unpleasant taste gene provides a “ruin-your-day level of bitterness” to foods like broccoli and sprouts, they say.
It could explain why some people find it difficult to include enough vegetables in their diet, they suggest.
The gene may also make beer, coffee and dark chocolate taste unpleasant.
In evolutionary terms, being sensitive to bitter taste may be beneficial – protecting humans from eating things that could be poisonous.
But Dr Jennifer Smith and colleagues from the University of Kentucky School of Medicine say it can also mean some people struggle to eat their recommended five-a-day of fresh fruit and veg.
Everyone inherits two copies of a taste gene called TAS2R38.
It encodes for a protein in the taste receptors on the tongue which allows us to taste bitterness.
People who inherit two copies of a variant of the gene TAS2R38, called AVI, are not sensitive to bitter tastes from certain chemicals.
Those with one copy of AVI and another called PAV perceive bitter tastes of these chemicals, but not to such an extreme degree as individuals with two copies of PAV, often called “super-tasters”, who find the same foods exceptionally bitter.
The scientists studied 175 people and found those with two copies of the bitter taste PAV version of the gene ate only small amounts of leafy green vegetables, which are good for the heart.
Dr Smith told medics at a meeting of the American Heart Association: “You have to consider how things taste if you really want your patient to follow nutrition guidelines.”
The researchers hope to explore whether using spices could help mask the bitter taste and make vegetables more appealing for people who are hard-wired to dislike certain varieties. -BBC

Toxic exposure from feminhygiene products

A RECENT study has shown that products used by women for feminine hygiene can leech highly toxic chemical compounds into their systems.
The study, which was published in the Journal of Women’s Health, used data from 2,432 women aged 20 to 49.
Researchers used the participants’ biomarkers to establish a link between the use of feminine hygiene products and exposure to volatile organic compounds (VOCs).
VOCs are chemicals used in a wide range of products, including deodorants, nail polish and paint.
Some of these chemicals have been associated with respiratory symptoms, some cancers and neurological disorders, as well as deleterious effects on the reproductive system.
The feminine products studied included the soaps in vaginal douches, deodorising vaginal powders and sprays, as well as tampons and sanitary pads.
Focusing on the potentially carcinogenic VOC 1,4-dichlorobenzene, the study showed that women who used a vaginal douche two or more times per month had concentrations 81% higher than non-users.
Participants who restricted their douching practice to an average of once a month saw a concentration of 18% higher than women who abstain.
The use of deodorising vaginal powders in the last 12 months was associated with higher blood levels (36%) of ethylbenzene, a compound that is highly toxic if inhaled.
Though additional research is still required, the researchers advised women follow the recommendation from the American Society for Obstetricians and Gynecologist not to use certain products such as vaginal douches and feminine powders. – AFP Relaxnews