Researchers suggest nicotine could protect against brain aging.
Dr. Ursula Winzer-Serhan, an associate professor at the Texas A&M College of Medicine, and colleagues report their findings in the Journal of Toxicology.
Previous animal and human studies have shown that nicotine has possible cognitive benefits; the chemical binds to and activates nicotinic acetylcholine receptors (nAChRs) in the brain, which has been found to reduce neurodegeneration.
"Thus, medicinal use of nicotine or related nAChR agonists could have great beneficial effects for human health," the authors note.
However, the underlying mechanisms of this association are unclear, and given nicotine's well-known addictive properties, it is no surprise that concerns have been raised about using the chemical as a treatment for neurodegenerative disorders.
For their study, Dr. Winzer-Serhan and team used mouse models to investigate the effects of nicotine at various doses on appetite, weight, anxiety, and levels of nAChRs in the brain.
"Some people say that nicotine decreases anxiety, which is why people smoke, but others say it increases anxiety," says Dr. Winzer-Serhan. "The last thing you would want in a drug that is given chronically would be a negative change in behavior."
High nicotine dose did not increase anxiety
The researchers added nicotine to the drinking water of mice at either low, medium, or high doses.
On assessing the mice that received low and medium doses of nicotine, the researchers identified no traces of the drug in their blood, and there were no changes in food intake, weight, or nAChRs.
Mice that received the high nicotine dose, however, showed a reduction in food intake and body weight and an increase in nAChR levels. Additionally, the researchers identified no signs of increased anxiety in the high-dose mice.
The researchers say they plan to conduct further studies to investigate the effects of nicotine against neurodegeneration in aged mice, and they also want to determine whether nicotine's ability to reduce appetite and weight gain explains its possible protective effect against brain aging.
Still, the current results indicate that nicotine treatment is unlikely to alter behavior, bringing researchers one step closer to determining the safety of nicotine as a treatment for neurodegenerative disorders.
That said, Dr. Winzer-Serhan stresses that their findings should not encourage the use of cigarettes and other nicotine-containing products.
"At the end of the day, we haven't proven that this addictive drug is safe - and it certainly isn't during childhood or adolescence - or that the benefits outweigh the potential risks," she adds.
"Even if these weren't very preliminary results, smoking results in so many health problems that any possible benefit of the nicotine would be more than canceled out.
However, smoking is only one possible route of administration of the drug, and our work shows that we shouldn't write-off nicotine completely."
Dr. Ursula Winzer-Serhan