Study on the Dye Leakage Response of Nasal Mucosa Following Topical, Capsaicin Challenge in Guinea Pigs

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Abstract
We examined the serial changes of intravenously applied dye leakage and preliminary examined histamine release into nasal lavage fluid after topical stimulation with capsaicin in guinea pigs. A significant increase in the dye leakage response was detected for 30-40 min, with the maximum response occurring between 5 and 10 min after topical capsaicin stimulation. The dye leakage response to nasal capsaicin challenge was abolished by pretreatment with topical lidocaine, general substance P analogue, topical or general high dosage capsaicin. The dye leakage response to topical capsaicin challenge was significantly reduced following pretreatment with antihistamine, diphenhydramine or atropine sulfate, although it was not affected by pretreatment with an anti-leukotriene, FPL 55712. Topical methacholine challenge did not induce a dye leakage response. An increase in the concentration of histamine in the nasal lavage fluid was noted at 5 min after topical capsaicin challenge. The concentrations of released histamine tended to be positively correlated with those of leaked dye in the nasal lavage fluids. The histamine release induced by topical stimulation with capsaicin tended to be reduced following general and topical pretreatments with high dosage of capsaicin, and was almost completely abolished following atropine pretreatment. From this study it was concluded that nasal capsaicin stimulation can reflexively induce an intravenously applied dye leakage into the nasal cavity, and that C-fiber related cholinergic nerve reflex and histamine release might, at least partially, be related to this response.