New research conducted at The Rockefeller University, Washington University School of Medicine and the Max Delbrück Center for Molecular Medicine in Berlin published in the Sept. 30, 2013, edition of the journal Proceedings of the National Academy of Sciences indicates that the brain may be wired toward nicotine addiction.
Previous studies have shown that nicotine binds to nicotinic acetylcholine receptors (nAChRs) in the brain. The nicotinic acetylcholine receptors are primarily located in the medial habenula region of the brain. The scientists found three primary gene subunits are involved in nicotine addiction and withdrawal. The α3, β4 and α5 subunits of the nAChR play a key role in heavy tobacco use and relapse.
More α3, β4 and α5 receptor subunits are located in the medial habenula than any other area of the brain.
The researchers found that nicotine addicted mice had developed a genetic change that promotes rhythmic electrical pulses in the brain. Disruption of these pacemaker channels produced nicotine withdrawal symptoms in mice that had never been exposed to nicotine.
The same pacemaker system doubled in activity in mice that were exposed to nicotine, had withdrawn, and were exposed to nicotine again.
These findings explain the difficulty people have in quitting smoking and also explain the greater difficulty people that relapse into nicotine use after quitting have a harder time quitting again.
The research gives scientists a physical location and a set of chemical substances to use to create more effective nicotine cessation therapies.