More Than Flavor: Menthol Cigarettes Desensitize Lung Airways

Posted in GUMC Stories

NOVEMBER 17, 2014 – Georgetown neuroscientists say menthol and nicotine work together to desensitize receptors in the lungs’ airways, possibly encouraging people to inhale menthol cigarettes more deeply and exposing them to more toxins.

The U.S. Food and Drug Administration (FDA) is considering restrictions on menthol cigarettes because they are likely associated with increased initiation of smoking, greater dependence and reduced success in smoking cessation, especially among African Americans.

“The issue may be that menthol in the presence of nicotine may reduce the irritation enough that a smoker can inhale more deeply, bringing not just nicotine but toxic smoke products farther into the lungs,” says co-investigator Gerard Ahern, PhD , an associate professor of pharmacology at Georgetown University Medical Center (GUMC). “While beyond the scope of this study, it is possible that such deeper inhalation of menthol cigarettes, to the extent it occurs, increases the already substantial health harms from smoking.”

Hoai Ton , a GUMC post-doctoral researcher, presented the study yesterday at the Society for Neuroscience’s annual meeting in Washington, D.C.

“We know that a menthol cough drop soothes a scratchy, sore throat,” says study author Kenneth Kellar, PhD , a GUMC professor of pharmacology. “The question we looked at is if and how it works when the irritant is nicotine. This study supports the notion that menthol is not just a flavoring, but has a pharmacologic effect.”

Though the FDA’s July 2013 review of available research on menthol cigarettes concluded that menthol in cigarettes is not associated with an increased disease risk, use of them is high among African-American smokers, who have a higher rate of lung cancer.

The researchers say their study provides a better understanding of how menthol affects the function of one of the most prevalent nicotinic acetylcholine receptors expressed in the peripheral nervous system. These receptors are expressed in airway sensory nerves as well as other neurons.

“These receptors are also found in the brain, but we don’t know yet what effect menthol has on those receptors or whether they contribute, in any way, to nicotine addiction,” Kellar says.

Study contributors also include research assistant Thao Olson . For more information on the study, click here .

National Institutes of Health grant (DA012976) funded the research.