title: Trigeminal sensitization and desensitization in the nasal cavity: a study of cross interactions.
abstract: Chemical irritation in the human nasal cavity is poorly documented. In this field, an important issue concerns the differential responses produced by successive stimulation. Repeated identical chemical irritant stimuli can produce increases or decreases in responses (two phenomena known as self-sensitization or self-desensitization). In the same way, different molecules can interact and produce cross-sensitization or cross-desensitization. The aim of this study was to contribute to this question using two specific molecules, acetic acid (AA) and allyl isothiocyanate (AIC). As the self-sensitization and -desensitization for AIC is known, a first experiment in the present work investigated the response, acute effects and time course of sensitization or desensitization to acetic acid. A second experiment tested the responses of acetic acid after a previous stimulation with allyl isothiocyanate (mustard oil) and inversely with a short inter-stimulus interval (ISI of 45 s). A third experiment similar to the second used a long inter-stimulus interval (ISI of 3 min 30). Twelve healthy subjects participated in the study using psychophysical (intensity ratings) and psychophysiological (skin conductance response) measurements. Firstly, the results showed that repeated nasal stimulation with acetic acid produced a self-desensitization whatever the ISI. Secondly, the results showed a cross-desensitization of allyl isothiocyanate by previous acetic acid stimulation. In contrast, previous stimulation with allyl isothiocyanate had no effect on the following acetic acid response. These findings confirm that trigeminal sensitization and desensitization in the nasal cavity do not follow the same processes in relation to molecules used.
authors: Laboratoire de Neurosciences, Université de Franche-Comte, Place Leclerc, 25000 Besançon, France.
authors: Laurence
authors: L
authors: Jacquot
authors: Julie
authors: J
authors: Monnin
authors: Annie
authors: A
authors: Lucarz
authors: Gérard
authors: G
authors: Brand
mesh_terms: D019342:Acetic Acid / Q000494:pharmacology*; D000328:Adult; D004056:Differential Threshold / Q000502:physiology; D005260:Female; D005712:Galvanic Skin Response / Q000502:physiology; D006801:Humans; D007509:Irritants / Q000494:pharmacology*; D017879:Isothiocyanates / Q000494:pharmacology*; D008297:Male; D009296:Nasal Cavity / Q000187:drug effects / Q000294:innervation*; D011601:Psychophysics; D011603:Psychophysiology; D013268:Stimulation, Chemical; D013997:Time Factors; D014276:Trigeminal Nerve / Q000187:drug effects*
chemical_list: D007509:Irritants; D017879:Isothiocyanates; C004471:allyl isothiocyanate; D019342:Acetic Acid