In utero exposure to nicotine causes genetic alterations that lead to the development of Attention Deficit Hyperactivity Disorder (ADHD).
Nicotine exposure during pregnancy is thought to trigger a large number of genetic changes affecting the formation of neural connections in children, and this for years after birth, according to a study from Yale University (United States) published in the journal Nature Neuroscience on Monday.
This discovery would explain, for the first time, the association between the exhibition in utero nicotine and its behavioral repercussions such as attention deficit hyperactivity disorder (ADHD), or addictive behaviors.
Nicotine and genetic activity
Consequences linked to the effect of nicotine on genes reveal this work carried out in mice. These show, in fact, that guinea pigs exposed to nicotine during their early development present disorders similar to ADHD.
By analyzing the DNA of mice, the researchers observed a larger-than-normal amount of a molecule that regulates gene activity. The latter acts on the compaction of DNA: the more compact it is, the less active the genes are, and vice versa. This is called an epigenetic phenomenon. This alteration particularly affects the genes responsible for forming the connections between neurons.
In addition, the researchers discovered that this modification persists in adult mice. By administering a drug that inhibits the regulatory molecule, the team observes that the animals are calmer and the disorders subside.
Acts even during childhood
To verify that this molecule is responsible for the appearance of behavioral disorders, the scientists stimulated its production in mice that had never been exposed to nicotine. Result: they also present disorders similar to ADHD.
“It’s exciting to discover a signal that can explain the long-term effects of nicotine on neuronal cell structure and behavior,” said Marina Picciotto, professor of psychiatry in the Department of Molecular Psychiatry at Yale University. and responsible for the work. But it is even more interesting to discover the molecule that influences the expression of certain genes after being stimulated by nicotine during development ”.
A French study published last September in Plos One has also shown the link between exposure to tobacco and the onset of these disorders in more than 5,200 children. In particular, she found that exposure to tobacco smoke in childhood increased the risk of developmental disabilities. The results presented on Monday seem to confirm the French observations.
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