Nicotine Causes Epigenetic Changes in Mice that Spur Cocaine Addiction

What’s the News: Epidemiologists have long noticed that people with drug addictions often start out smoking cigarettes before moving on to harder stuff. Whether that’s because there’s something about cigarettes that makes people vulnerable to other drugs or because certain kinds of people are predisposed to addiction (or for some other reason entirely) is an open question,Canada Goose and the idea of so-called “ gateway drugs” has been a controversial topic in addiction for years. Now, an elegant new study in mice has discovered a mechanism that could explain the gateway drug effect: nicotine actually changes the expression of genes linked to addiction.

How the Heck:

    * First, the researchers (including biologist Denise Kandel and her Nobel laureate husband,Snow Mantra Eric Kandel) gave mice nicotine to mimic the effects of cigarette addiction before giving them several injections of cocaine.
    * Watching their behavior, the team saw that mice that had been given nicotine for many days returned again and again to locations where they had been given cocaine, far more—nearly double the frequency—than mice who had only received nicotine for 24 hours. In studies with drugs,Belstaff this is a well-established sign of addiction.
    * Opening up the brains of the mice, they found that the neuronal pathway that delivers cocaine’s rewards was much more strongly activated in mice that had had days of nicotine. This suggests that nicotine actually enhances the pleasure derived from cocaine.
    * Looking deeper at the brain cells implicated in addiction and reward, they found that FosB, a gene whose expression helps cement addiction,Belstaff Outlet was expressed at levels 74% higher than in mice who hadn’t had nicotine.
    * Investigating how nicotine could have this effect, they discovered that it was acting at an  epigenetic level—in other words, changing the chemical packing of DNA. Here’s how:
    * When certain chemical tags are present on DNA, the double helix unfurls a bit, making it easier for the cellular machinery to get a hold of a gene, read off its code, and translate it into a protein. When mice were exposed to nicotine for many days, an enzyme that removes those tags and thus keeps certain genes out of circulation was knocked down. That was how nicotine caused FosB production,Canada Goose Jackor and thus, addiction, to go into overdrive.
    * Importantly, the team found that this relationship was a one-way street: giving cocaine before nicotine did nothing. For this effect to take place, nicotine has to come first.