Study: Cocaine Scrambles Genes' Behavior in the Brain's Pleasure Center

By Andrew Moseman | January 11, 2010 2:01 pm

cocaineAddiction researchers constantly wade through the ways that drugs like cocaine change your brain, and a new study in Science has pointed to a new epigenetic factor. Cocaine, the researchers say, can scramble the way genes turn on and off in a key brain region associated with pleasure and reward.

Ian Maze said his team gave one group of mice repeated doses of cocaine and other group repeated doses of saline with just one blast of cocaine at the end to study the differences. The team paid particular attention to a protein called G9a, whose behavior in the nucleus accumbens region of the brain seems to be altered by cocaine use. The role of the protein appears to be to shut down genes that shouldn’t be on. One-time use of cocaine increases levels of G9a. But repeated use works the other way, suppressing the protein and reducing its overall control of gene activation [TIME]. The researchers found that the overactive genes caused brain cells in the region to grow more connections to each other. The growth of such neural connections can reflect learning. But in the case of addiction, that may involve learning to connect a place or a person with the desire for more drugs [TIME].

G9a changes in the cocaine-addicted mice were persistent, too. Maze showed that even after a week of abstinence, mice given a new dose of cocaine still had elevated levels of gene activation in the nucleus accumbens, meaning G9a levels were still low…. Maze also showed that when he intervened and raised G9a levels, the mice were less attracted to cocaine [TIME].

Though this was just a rodent study, National Institute on Drug Abuse director Nora Volkow said it could be a crucial piece of the cocaine addiction puzzle. “One of the questions we’ve had all along is, after discontinuing a drug, why do you continue to be addicted? This is one of the mechanisms that probably is responsible for these long-lasting modifications to the way people who are addicted to drugs perceive the world and react to it,” she said [Reuters]. Much more research is necessary, but the research could point the way to the development of addiction medications down the road.

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Image: iStockphoto

CATEGORIZED UNDER: Health & Medicine
  • ricochet rabbit

    I am not a coke head, but I know what it smells like. This study seems to shed light on why users associate with each other, bonding in a way that shuts non users out. Pot heads don’t withdraw socially as coke heads do, despite the fact that smokers need their fix too.

  • badnicolez

    Does anyone know if any studies have been done regarding cocaine addiction and obesity? I have a friend who is obese and I’m wondering if her prior cocaine use might have something to do with her current weight issues.

  • Stevie

    I’ve often wondered about addiction . I’ve more than ” dabbled in coke, in my youth , but i never became addicted , nor even craved it . The same with Booze…. There were many , many ” lost Week-ends , and weekdays , but, I never HAD to have it . I quit drinking completely 13 years ago , and never even think of it, other than maybe an Ice Cold beer on a hot summer day , but, Diet Coke worls just as well, lol..
    Smoking , well I smoked on and off for years, by choice . I Liked to smoke , so I choose to ; Vacations, weekends, I never smoked , and never wanted to I liked a smoke with a coffee in the morning , at lunch , the usual … Last January , I decided to quit , so I did . I smoked the last pack that I had, and that was it , I ;ve not even thought about it since . I smoked , on and off , for 35 years . I quit three major times, Once for 18 months , another for 2 years , another for about four months.
    In all cases, I did what I did , because I CHOOSE to , not because of any addiction . Pot , coke, Whatever , Nothing was , or is , addicting to me . Coffee , tea , Diet coke , what ever , any caffiene , no addiction there either . Don’t get me wtong , I LIKED all my vices, but they did not , by any means , own me …. Am I strange ? perhaps .. I just always thought that ” addictions ” were just an excuse to be lazy , and not keeping yourself in control of your body as well as your mind .
    Food too.. I like to eat .. I gain 10 – 15 lbs, my pants get tight , I simply cut back , till I dump the weight , usually within two weeks .
    It’s simply a matter of setting your mind to control your mind, and body . I do Meditate a lot, and do a little yoga ,
    I don’t know , I guess i’m just lucky …

  • geeta

    I like the comment #3 – I find it rediculous when people blame their bad habits on parts of their body and feel clean themselves. Even deadly criminals are bailed out of punishment with such excuses as bad genes/hormones, bad mental condition, and even bad childhood! There is something called learning/training oneself, getting over things and taking control of oneself and responsibility for one’s own actions.
    I do not use stuff that are known to me to be bad for me, nor do I buy when people say they do stuff because circumstances are such and/or they cannot stop. I neither meditate nor do yoga on a regular basis, but I think rationally :)

  • Cory

    Lawl, they addicted the mice to cocaine, people, it’s not like the mice had willpower issues. It’s a deeply physiological phenomenon. Doing coke and drinking hard occasionally will not get you addicted — going on weeklong coke benders or getting drunk most nights will.

  • ron hansing

    Hummmm. We should study #3 and #4.

    I smoked for ten years, thank you frank gifford, but you got a 16 year old hooked.

    After ten years, I decided to have just one cigarette. I thought I was over it. Not so, it was very difficult not to take that second fag.

    The reason some have addictive problems is due to biological variability. We are all different.

    It is disingenuous for #3 and #4 to be so critical of those who do have problems with addiction. Some compassion should be offered to those with “bad” genes… Regardless, it is not valid to offer justification for addiction. We are responsible for our own health.

    Albeit, count yourself lucky, that you do not have this problem… But perhaps, it is not all good, in that, you may not feel the emotional highs of drugs, also, you may not feel a similar euphoria, let’s say, to falling in love…. or holding, the birth of your newborn baby. So be careful to what you wish for.

    It’s easy to be judgmental…. but compassion and understanding makes you a better person. Again, could it mean you do not feel compassion to the degree of the addictors? And is that a plus or a minus? I don’t know the answer.

    Ron Hansing MD 1.10.10

  • Jeff S

    #6 – you are pretty much dead-on. #3, #4 – you sound like your assuming that all of us have the same genes and environment – definitely not the case. Another way of looking at this: I can run all day every day for years (almost did – got up to 16 miles at my peak) and I could never even make a collge long-distance team. Not even second team. Not becuase I’m lazy – I was one hell of a D1 wrestler in my days. I’m built differently. I feel differently (I don’t really like running, though I tried to escape when doing it, oh well). Get me the best coach int he world, best diet, etc, and I’m still nowhere near any of those runners. We are all different and addiction is very real – more for some than others for sure.

  • JD

    Sounds like Stevie and geeta have everything all figured out for the rest of the world.

    They did their thing and they recovered. Unfortunately, the rest of the world doesn’t run on sheer will power alone. Addiction is very real, and so are genetic differences between people which is why two people can process the same thing differently whether its interpreting art, our taste in food, or how we handle chemical dependency, and withdrawl afterwards.

    Great on Stevie and geeta for kicking their habits, but as science is starting to confirm, chemical addiction is real.

    Now, since apparently all of life’s problems can be resolved by just believing hard enough, I’m going to go see if I can just believe money will show up in my wallet and see what happens.

  • Angie

    What really fascinates me is, that less protein seems to lead to better connections between your nerve cells. Or have I gotten something wrong?

    As for taking drugs… I used to smoke (but not dope, just Malboro lights)… I got hooked at 18 and stopped at 21. Doesn´t that prove you US citizens are right about considering people younger than 21 a bunch of brats? I was kid at the age for sure (not only because of the smoking…)!

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