(Original article: “Insight Into the Way Nicotine Works in the Brain.”, ScienceDaily, March 29, 2009)
Nicotine binds to brain receptors, and as is fairly common knowledge, is an addictive substance.
Nicotine binds to a type of acetylcholine receptor in neurones (brain cells). This same type of acetylcholine receptor is also prevalent in muscle cells. Nicotine binds to the neurones’ acetylcholine receptors. If it were to bind to the muscle cells’ equivalent, the smoker, in this scenario, would be paralyse or die from violent muscular contractions.
Research from the California Institute of Technology, led by Professor Dennis Dougherty, has indicated that the reason smokers don’t perish in violent fits of muscular spasm upon taking a drag, is of a genetic nature; a genetic mutation is responsible.
Even though the acetylcholine receptors in brain and muscle cells are essentially the same, their structures are slightly different. Chemical interactions are important in a receptor’s shape and how a chemical binds to it. A cation π interaction explains how acetylcholine bind to acetylcholine receptors in muscle cells.
In muscle cells, nicotine is not capable of doing so. However, in the brain’s neurones’ acetylcholine receptors, nicotine can bind. Nicotine, in brain cells, can make strong cation π interactions and strong hydrogen bonds.
This is all because of a mutation in the receptors. The mutation in the brain cells’ receptors, allows nicotine to “fit” closely with tryptophan, to all the cation π interaction. Nicotine and the receptors’ tryptophan can be closer in the brain cells than in muscle cells.
Dougherty concludes that this is the reason for nicotine’s addictiveness.
So, negatively, this genetic mutation creates addicts out of some persons who indulge in cigarettes, but on a positive note, saves those who do so from violent, and potentially lethal muscular contractions.
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References:
California Institute of Technology (2009, March 29). Insight Into The Way Nicotine Works In The Brain. ScienceDaily. Retrieved March 29, 2009, from http://www.sciencedaily.com¬ /releases/2009/03/090323161121.htm [Accessed 29th March, 2009]
Journal reference:
1. Xiu et al. Nicotine binding to brain receptors requires a strong cation–π interaction. Nature, March 26, 2009; DOI: 10.1038/nature07768 Adapted from materials provided by California Institute of Technology, via EurekAlert!, a service of AAAS.
