Different roles of capsaicin-sensitive and H1 histamine receptor-expressing sensory neurones in itch of mosquito allergy in mice.
Although mosquito allergy induces the release of histamine, the itch-related response, scratching, is not effectively suppressed by blockade of H1 histamine receptors. To address this question, we examined the effects of neonatal capsaicin treatment on allergic reactions and H1 histamine receptor-expressing sensory neurones in mice. Neonatal capsaicin treatment almost completely abolished allergy-associated scratching, without effects on plasma extravasation or increase in serum concentrations of immunoglobulins E and G1. An injection of edema contents from an animal exhibiting allergic reaction elicited scratching in naive animals, suggesting the production of pruritogen(s) by allergic reaction; this production was not suppressed by neonatal capsaicin treatment. This treatment markedly decreased the number of sensory neurones immunoreactive for TRPV1 capsaicin receptor, with little effect on sensory neurones immunoreactive for neurofilament 200, a marker of myelinated A-fibre neurones. In addition, there was a trend towards a reduction in numbers of sensory neurones immunoreactive for H1 histamine receptor. The results suggest that capsaicin-sensitive sensory neurones that lack H1 histamine receptors play a key role in signalling of allergic itch.
Nakano
Tasuku
T
Department of Applied Pharmacology, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama, Japan.
Andoh
Tsugunobu
T
Sasaki
Atsushi
A
Nojima
Hiroshi
H
Kuraishi
Yasushi
Y
D000818:Animals; D000831:Animals, Newborn; D000982:Antipruritics / Q000494:pharmacology*; D002211:Capsaicin / Q000494:pharmacology*; D009033:Culicidae; D006967:Hypersensitivity / Q000378:metabolism; D007279:Injections, Subcutaneous; D008297:Male; D051379:Mice; D011537:Pruritus / Q000188:drug therapy*; D011969:Receptors, Histamine H1 / Q000378:metabolism; D012469:Salivary Glands / Q000737:chemistry; D011984:Sensory Receptor Cells / Q000378:metabolism*; D050916:TRPV Cation Channels / Q000378:metabolism; D014020:Tissue Extracts / Q000008:administration & dosage
D000982:Antipruritics; D011969:Receptors, Histamine H1; D050916:TRPV Cation Channels; C493921:TRPV1 protein, mouse; D014020:Tissue Extracts; D002211:Capsaicin