Some people who try smoking get hooked ever. Now scientists have found that these people are less susceptible to tobacco addiction because their bodies decompose under its addictive component, nicotine. The results, reported in tomorrow's issue of Nature , may lead to drugs that block the metabolism of nicotine and help addicted smokers quit.
In previous studies targeting the molecular roots of nicotine addiction, pharmacologist Rachel Tyndale of the University of Toronto and colleagues identified an enzyme called CYP2A6, which breaks down more than 48% of the nicotine To smoke. Because an estimated 18.5% of the population carries one or two defective copies of CYP2A6 gene and can not metabolize nicotine well, the team wonders if these people were protected dependence nicotine. This is because nicotine addicts seeking because their bodies are so effective in breaking the chemical.
To see which versions of the enzyme CYP2A6 smokers are, the researchers extracted CYP2A6 genes from white blood cells of 244 smokers and 184 people who had tried cigarettes, but which do to have developed a habit, became non-smoking. After millions of copies of the genes, they sort with enzymes that cut variants in different sizes. The researchers found that non-smokers who have not become addicted were 51% more likely to have defective CYP2A6 variants that smokers. Smoking with defective CYP2A6 enzymes 23% smoked fewer cigarettes each week, suggesting that inhibitors of these enzymes may one day help smokers reduce the number of cigarettes they smoke.
"This is the first study to demonstrate a genetic mechanism that could make you more vulnerable to nicotine addiction," says Alan Leshner, director of the National Institute on Drug Abuse. Enzymes may also help explain why some smokers can not just quit cold turkey, said oral pathologist Brad Rodu of the University of Alabama, Birmingham. the fact that drugs that block CYP2A6 can help these "inveterate smokers' cut and QUIT, Rodu added, "is very exciting and very interesting."
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