A National Legal-Action Antismoking Organization
Entirely Supported by Tax-Deductible Contributions
| Home | Search | About ASH | Why Join | Comment | Email page |
|
Action on Smoking and Health
A National Legal-Action Antismoking Organization Entirely Supported by Tax-Deductible Contributions
|
New Study: Prenatal Nicotine Exposure Primes Brain for Addiction [04/20-4]
Excerpts from: Prenatal Nicotine Primes Adolescent Brain for Addiction
Ascribe [04/19/04]
Prenatal exposure to nicotine inflicts lasting damage that might leave the brain
vulnerable to further injury and addiction upon later use of the drug, according
to animal research conducted by Duke University Medical Center pharmacologists.
The team found in rat studies that exposure to nicotine in fetal development
alters the brain structures and brain cell activity in regions critical to
learning, memory and reward.
In turn, those changes influence nicotine's effects on the brain during adolescence, a time when many smokers first take up the habit, the team found. The study in rats might provide a biological explanation for the high incidence of smoking among teens whose mothers smoked during pregnancy, the researchers said.
A pair of papers describing the findings, now available online, is set to appear in forthcoming issues of Neuropsychopharmacology. Philip Morris USA supported the research. The researchers have no financial ties to Philip Morris.
While maternal smoking rates have dropped in recent years, approximately 25 percent of individuals in the U.S. have mothers who smoked during pregnancy, Slotkin said. Epidemiological studies by other researchers have shown that such maternal smoking leaves children prone to smoke as adolescents, regardless of whether the parental smoking continues during childhood. That research was performed by researchers including Denise Kandel, Ph.D., of Columbia University, Marie Cornelius, Ph.D., of the University of Pittsburgh and Raymond Niaura, Ph.D., of Brown University.
In search of a biological explanation for the pattern, the Duke team administered nicotine or placebo to pregnant rats. The offspring then received a secondary exposure to the drug or placebo during adolescence via implanted osmotic minipumps designed to produce blood nicotine concentrations typical of smokers.
The rats exposed to nicotine before birth suffered loss of brain cells and a decline in brain activity that persisted throughout adolescence and into adulthood, the team found.
When given doses of nicotine for a two-week period as adolescents, the earlier exposed rats showed a weaker brain response in circuits using acetylcholine -- a natural chemical messenger that plays a critical role in learning and memory -- as compared to rats that did not experience the prenatal exposure. Nicotine's activity in the brain stems from its ability to mimic acetylcholine. The earlier exposure also worsened the decline in brain activity during nicotine withdrawal and led to an increase in the amount of brain cell injury induced by the drug, they reported.
Specifically, the team explained, the reduced response of acetylcholine systems in the adolescent brain following prenatal exposure might lead teens to self-administer nicotine in an attempt to replace the brain's functional loss. Furthermore, that deficient brain response might drive higher cigarette consumption.
Collaborators on the studies include Yael Abreu-Villaca, Ph.D., Frederic Seidler, Ph.D., Charlotte Tate and Mandy Cousins, all of Duke.
Behavioral and Neurochemical Vulnerability During Adolescence in Mice: Studies with Nicotine - Abstract
| Home Web Page | Search This Site | Learn About ASH | Why Join ASH | Comment on This | Email This Page |