The study was published last week…” story continued here at ScienceDaily.

"Mmm, tar."

…Wait a minute, people still smoke cigarettes?

Okay, okay, I’m not that naive — about 1 in 5 adults in the U.S. smokes cigarettes, despite those awesome Truth commercials and the fairly common knowledge that smoking leads to cancer, heart disease, lung disease, and tons of other health problems that no one wants.

Well, cigarette smokers everywhere have just been handed their gazillionth reason not to smoke – because it apparently makes your body want cocaine. More specifically, research published today says that the nicotine in cigarettes can make long-term changes in your genetics that will make you more likely to become a coke addict.

Gateway drug, indeed.

Sucks to be a research mouse.

So, how did scientists figure this one out? In keeping with the harsh realities of disease research, it involved doing some messed up things to mice. Researchers in China gave nicotine to mice, and a week later gave them cocaine. The result was that, compared to mice who had cocaine only, the mice who had nicotine beforehand showed 98% more physical activity and a 78% increased probability of going back to the place where they got the cocaine. (No such effect was seen if the order of drugs was reversed, i.e., cocaine given a week before nicotine.)

To explain the biology of why nicotine made the mice more susceptible to cocaine’s effects, I need to briefly talk about epigenetics, which is the process by which the expression of your genes can be changed in a long-lasting way. As it turns out, our DNA isn’t just floating around in that cool twisted-ladder shape that you see on Wikipedia. It’s actually packaged in a really neat way:

In this crude diagram made on the fly using Paint, you’ll see the classic Biology 101 chromosome. This is a very high-level packaging of DNA; if you zoom in on this chromosome, there is a spaghetti-like configuration of DNA that’s still pretty compact. Zoom in further and there are “beads on a string,” which is DNA wrapping itself around these proteins called histones, and histones actually make all this packaging possible. Finally, zoom in one more time and you’ve got the double helix we all know and love.

All of this is to help make the point that nicotine loosens up the DNA that’s wrapped around the histones. When DNA is less tightly wrapped around histones, the genes in that bit of DNA can be expressed more easily. In the case of nicotine use, one of those genes with increased expression appears to be FosB, a gene that is often associated with drug addiction and whose levels have been shown to increase with each dose of cocaine.

Short version of this post

This work definitely raises interesting questions: Since epigenetic changes to DNA are potentially heritable, are these finding relevant to the offspring of smokers (or babies exposed to nicotine in utero)? Should campaigns against nicotine be even more aggressive, given this new damning evidence for nicotine-induced susceptibility to a bigger and badder drug? Do other substances, like alcohol and marijuana, induce any sort of “gateway drug” effect similar to the one shown here for nicotine?

Time (and more research) will tell. In the mean time, Try Nerdy only needs 8 more Facebook “likes” to become an official page! How awesome would that be???

Stay nerdy.

Levine, A., Huang, Y., Drisaldi, B., Griffin, E., Pollak, D., Xu, S., Yin, D., Schaffran, C., Kandel, D., & Kandel, E. (2011). Molecular Mechanism for a Gateway Drug: Epigenetic Changes Initiated by Nicotine Prime Gene Expression by Cocaine Science Translational Medicine, 3 (107), 107-107 DOI: 10.1126/scitranslmed.3003062