activation of the cold-receptor TRPM8 by low levels of menthol in tobacco products

Introduction:
This article discusses a study that investigates the activation of the cold-receptor TRPM8 by low levels of menthol in tobacco products. The study aims to determine the minimum menthol contents in cigarettes required for TRPM8 activation and whether such minor contents would be sufficient to trigger a measurable activation of TRPM8. The study also discusses the potential implications of TRPM8 activation in tobacco products for smoking initiation and addiction.

Key points:

* The study used a bioassay to determine the minimum concentrations of selected agonists to activate the TRPM8 receptor in cultured cells.
* The data confirm menthol as the strongest natural agonist investigated and estimate both the minimum menthol concentrations in cigarette smoke and in tobacco that are expected to trigger measurable physiological effects.
* The study found that TRPM8 activation is likely to occur when cigarettes contain more than 50 micrograms of menthol.
* Menthol contents in cigarettes far below the typical levels that require declaration as "mentholated" would be sufficient to activate sensory receptors.
* Menthol cigarettes had been classified as starter products that are likely to facilitate product's addictiveness in adolescents.
* Menthol might increase addictiveness indirectly by impairing physiological resistance against inhalation of irritating fumes and altering individual smoking habits.
* according to new European regulation, menthol will be restricted as a potential characterizing flavor, and menthol levels far below the typical contents of declared menthol cigarettes are sufficient to activate TRPM8 via inhalation.

Main message:
The study highlights the potential risks associated with TRPM8 activation in tobacco products. Menthol cigarettes are classified as starter products that are likely to facilitate product's addictiveness in adolescents. Menthol might increase addictiveness indirectly by impairing physiological resistance against inhalation of irritating fumes and altering individual smoking habits. Therefore, the study suggests that physiologically active levels of menthol or other TRPM8 agonists need to be expected in conventional smoking tobacco products that are not sold as "menthol cigarettes." The new European regulation restricting menthol as a potential characterizing flavor is a step in the right direction, but more needs to be done to regulate menthol levels in tobacco products.

Paschke, Meike, anna Tkachenko, Katja ackermann, Christoph hutzler, Frank henkler, and andreas Luch. “activation of the Cold-Receptor TRPM8 by Low Levels of Menthol in Tobacco Products.” Toxicology Letters 271 (april 2017): 50–57. https://doi.org/10.1016/j.toxlet.2017.02.020.