A Comparison of Oral Sensory Effects of Three TRPA1 Agonists in Young Adult Smokers and Non-smokers

Abstract

This study profiled intra-oral somatosensory and vasomotor responses to three different transient receptor potential (TRP) channels, subfamily A, member 1 (TRPA1) agonists (menthol, nicotine, and cinnamaldehyde) in smoking and non-smoking young adults. Healthy non-smokers (N = 30) and otherwise healthy smokers (N = 25) participated in a randomized, double-blinded, cross-over study consisting of three experimental sessions in which they received menthol (30 mg), nicotine (4 mg), or cinnamaldehyde (25 mg) chewing gum. Throughout a standardized 10 min chewing regime, burning, cooling, and irritation intensities, and location were recorded. In addition, blood pressure, heart rate and intra-oral temperature were assessed before, during, and after chewing. Basal intra-oral temperature was lower in smokers (35.2°C ± 1.58) as compared to non-smokers (35.9°C ± 1.61) [F(1, 52) = 8.5, P = 0.005, post hoc, p = 0.005]. However, the increase in temperature, heart rate, and blood pressure in response to chewing menthol, nicotine, and cinnamaldehyde gums were similar between smokers and non-smokers. Although smoking status did not influence the intensity of burning, cooling, and irritation, smokers did report nicotine burn more often (92%) than non-smokers (63%) [χ(1, textN=55)2 = 6.208, P = 0.013]. Reports of nicotine burn consistently occurred at the back of the throat and cinnamaldehyde burn on the tongue. The cooling sensation of menthol was more widely distributed in the mouth of non-smokers as compared to smokers. Smoking alters thermoregulation, somatosensory, and possibly TRPA1 receptor responsiveness and suggests that accumulated exposure of nicotine by way of cigarette smoke alters oral sensory and vasomotor sensitivity.

Mammalian Transient Receptor Potential TRPA1 Channels: From Structure to Disease

“…When applied topically on the skin, cinnamaldehyde produces spontaneous pain, heat and mechanical hyperalgesia, cold hypoalgesia, neurogenic axon reflex erythema, intensified warm sensations, reduced heat pain threshold, moderate itch, flare, hyperkinesis, allokinesis, and increased skin blood flow and temperature (30,53,135,322,575,630,740). In the human tongue, cinnamaldehyde enhances both heat-and cold-induced pain (14,685), increases the local temperature (353), and produces burning sensation (301). When applied to human airways, this compound produces smart (stinging pain) ( 16), cough (365), and weak burning sensation (134).…”

Harmful chemicals emitted from electronic cigarettes and potential deleterious effects in the oral cavity

“…This preliminary study reported subjects sensitized to the aldehyde reporting more burning complaints when exposed to nicotine. Both cinnamaldehyde and nicotine also alter the vasomotor activity in the oral and pharyngeal mucosa, and chronic exposure may modify pain reception in these areas 118 . To our knowledge, no publication has addressed this effect in e-cig users.…”

Herbs for Voice Database: Developing a Rational Approach to the Study of Herbal Remedies Used in Voice Care

“…TRPA1 channel has been identified in many cell types in the airways, principally in airway sensory neurons (spinal dorsal root ganglia, nasal trigeminal, and vagal neurons), but also in lung fibroblasts, airway smooth muscle cells, bronchial and alveolar epithelium cells. 11,20 TRPA1 channel is considered an important part of the lungs defense system and immunohistochemical studies have identified TRPA1 also in oropharynx and larynx. 21 The vagal and trigeminal ganglia innervating airways show appreciable TRPA1 expression.…”