Menthol attenuates respiratory irritation and elevates blood cotinine in cigarette smoke exposed mice.


Addition of menthol to cigarettes may be associated with increased initiation of smoking. The potential mechanisms underlying this association are not known. Menthol, likely due to its effects on cold-sensing peripheral sensory neurons, is known to inhibit the sensation of irritation elicited by respiratory irritants. However, it remains unclear whether menthol modulates cigarette smoke irritancy and nicotine absorption during initial exposures to cigarettes, thereby facilitating smoking initiation. Using plethysmography in a C57Bl/6J mouse model, we examined the effects of L-menthol, the menthol isomer added to cigarettes, on the respiratory sensory irritation response to primary smoke irritants (acrolein and cyclohexanone) and smoke of Kentucky reference 2R4 cigarettes. We also studied L-menthol's effect on blood levels of the nicotine metabolite, cotinine, immediately after exposure to cigarette smoke. L-menthol suppressed the irritation response to acrolein with an apparent IC₅₀ of 4 ppm. Suppression was observed even at acrolein levels well above those necessary to produce a maximal response. Cigarette smoke, at exposure levels of 10 mg/m³ or higher, caused an immediate and marked sensory irritation response in mice. This response was significantly suppressed by L-menthol even at smoke concentrations as high as 300 mg/m³. Counterirritation by L-menthol was abolished by treatment with a selective inhibitor of Transient Receptor Potential Melastatin 8 (TRPM8), the neuronal cold/menthol receptor. Inclusion of menthol in the cigarette smoke resulted in roughly a 1.5-fold increase in plasma cotinine levels over those observed in mice exposed to smoke without added menthol. These findings document that, L-menthol, through TRPM8, is a strong suppressor of respiratory irritation responses, even during highly noxious exposures to cigarette smoke or smoke irritants, and increases blood cotinine. Therefore, L-menthol, as a cigarette additive, may promote smoking initiation and nicotine addiction.





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Publication Info

Ha, Michael A, Gregory J Smith, Joseph A Cichocki, Lu Fan, Yi-Shiuan Liu, Ana I Caceres, Sven Eric Jordt, John B Morris, et al. (2015). Menthol attenuates respiratory irritation and elevates blood cotinine in cigarette smoke exposed mice. PLoS One, 10(2). p. e0117128. 10.1371/journal.pone.0117128 Retrieved from

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De Caceres Bustos

Anabel De Caceres Bustos

Research Scientist, Senior

Sven Eric Jordt

Associate Professor in Anesthesiology

Research in the Jordt laboratory focuses on the mechanisms that enable humans and animals to sense touch, pain and irritation. These fundamental sensations originate in peripheral sensory neurons which contain signaling pathways that translate environmental physical and chemical stimuli into neural activity. Our aims are to identify the molecular components of these pathways and to understand how sensory neurons become activated and sensitized during injury, inflammation and chronic painful conditions. The lab uses molecular, genetic and physiological techniques with a focus on models that closely mimic human conditions.

Current projects focus on:

1)   Ion channels and New Targets in Pain: The Jordt lab investigates the role of Transient Receptor Potential (TRP) ion channels, a group of ion channels that activate sensory neurons and pain sensations in response to thermal (hot, cold) and chemical stimuli. TRP channels were identified through their interactions with natural products such as capsaicin (in chili peppers), mustard oil (in mustard and wasabi) and menthol (in peppermint), and were shown to be involved in many painful conditions, including arthritis, diabetes and infections. The Jordt lab is studying the actions of TRP channel inhibitors in pain models and investigates mechanisms through which natural products such as menthol and eucalyptol inhibit acute and inflammatory pain.

2)   Allergies, Asthma and Itch: Sensory neurons mediate the sensations of itch, irritation and respiratory discomfort in allergic conditions. Research in the Jordt laboratory has revealed that blocking sensory nerves by targeting their receptors alleviates asthmatic conditions and also diminishes itch and inflammation in allergic contact dermatitis. We developed a unique model of poison ivy contact dermatitis we study to identify novel treatments to suppress itch in conditions unresponsive to antihistamines.

3)   Chemical Exposure Injuries and Tear Gas Agents: Supported by the National Institute of Environmental Health Sciences (NIEHS) and the NIH Countermeasures Against Chemical Threats Program (CounterACT)since 2006, the Jordt laboratory has made key contributions to research understanding the injury mechanisms following toxic chemical exposures. We identified TRPA1 as a target of chlorine gas and many other toxic exposures eliciting incapacitating pain, inflammation and organ injury. The Jordt laboratory is actively working with federal agencies and industry partners to identify additional targets and develop countermeasures that improve health outcomes following chemical exposures. Other studies focus on tear gas agents (CS, CN) and their potentially toxic effects, a topic Dr. Jordt has been interviewed on frequently by the public press.

4)   Tobacco Regulatory Science: Menthol cigarettes are increasingly popular, especially with adolescent beginning smokers. Applying our expertise in chemical sensory biology the Jordt lab demonstrated that menthol reduces the irritation sensed when inhaling smoke and increases markers of nicotine uptake. These effects are mediated by TRPM8, the cold/menthol receptor in sensory neurons innervating the respiratory system. This work is funded by programs from the FDA Center for Tobacco Products (CTP) and the National Institute on Drug Abuse (NIDA) through a Tobacco Center of Regulatory Science (TCORS) in collaboration with Yale University, also supporting studies on flavor additives in electronic cigarettes and smokeless tobacco. 

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