TRPA1 and TRPM8 activation in humans: effects of cinnamaldehyde and menthol.
The aim of this study was to evaluate the psychophysical effects of both TRPA1 and TRPM8 activation in humans by application of either cinnamaldehyde or menthol. We applied 10% cinnamaldehyde or 40% menthol solutions on the forearm in 10 study participants. Quantitative sensory testing and laser Doppler imaging was performed before and after exposure to the compounds. Cinnamaldehyde evoked significant spontaneous pain and induced heat and mechanical hyperalgesia, cold hypoalgesia and a neurogenic axon reflex erythema. In contrast, TRPM8 activation by menthol produced no axon reflex reaction and resulted in cold hyperalgesia. We conclude that agonists of TRPA1 and TRPM8 channels produce strikingly different psychophysical patterns.
Namer
Barbara
B
Department of Experimental Physiology and Pathophysiology, University of Erlangen-Nuremberg, Universitätsstrasse 17, 91054 Erlangen, Germany.
Seifert
Frank
F
Handwerker
Hermann Otto
HO
Maihöfner
Christian
C
D000171:Acrolein / Q000031:analogs & derivatives* / Q000494:pharmacology; D000328:Adult; D001369:Axons / Q000187:drug effects; D018592:Cross-Over Studies; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D006930:Hyperalgesia / Q000139:chemically induced; D007473:Ion Channels / Q000378:metabolism*; D017078:Laser-Doppler Flowmetry / Q000379:methods; D008297:Male; D008610:Menthol / Q000494:pharmacology*; D009363:Neoplasm Proteins / Q000378:metabolism*; D010146:Pain / Q000139:chemically induced / Q000503:physiopathology*; D010147:Pain Measurement / Q000379:methods; D017288:Pain Threshold / Q000187:drug effects*; D012018:Reflex / Q000187:drug effects; D050053:TRPM Cation Channels; D013997:Time Factors; D014664:Vasodilation / Q000187:drug effects
D007473:Ion Channels; D009363:Neoplasm Proteins; D050053:TRPM Cation Channels; C425966:TRPM8 protein, human; D008610:Menthol; D000171:Acrolein; C012843:cinnamaldehyde