title: Different dorsal horn neurons responding to histamine and allergic itch stimuli.
abstract: We examined whether different itch signals converge on the same dorsal horn neurons in mice. Intradermal injections of histamine and SLIGRL-NH2 (protease-activated receptor-2 agonist) induced scratching in naive mice and so did mosquito allergen in sensitized mice. These stimuli induced Fos expression in cells in the superficial dorsal horn. Fos-positive cells were mainly distributed within the isolectin B4-labeled region (inner aspect of lamina II) after histamine injection. In contrast, they were in the region dorsal to the isolectin B4-labeled region after injections of SLIGRL-NH2 and mosquito allergen. These results suggest that allergic itch signal is mediated by primary afferents expressing protease-activated receptor-2 and the neurons receiving signals of protease-associated itch and allergy-associated itch are different from those of histamine-induced itch.
authors.affiliation: Department of Applied Pharmacology, University of Toyama, Toyama, Japan.
authors.forename: Tasuku
authors.initials: T
authors.lastname: Nakano
authors.forename: Tsugunobu
authors.initials: T
authors.lastname: Andoh
authors.forename: Jung-Bum
authors.initials: JB
authors.lastname: Lee
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Kuraishi
mesh_terms: D000344:Afferent Pathways / Q000166:cytology / Q000378:metabolism; D000818:Animals; D006632:Histamine / Q000494:pharmacology*; D006967:Hypersensitivity / Q000378:metabolism*; D007150:Immunohistochemistry; D051379:Mice; D008813:Mice, Inbred ICR; D020671:Posterior Horn Cells / Q000166:cytology* / Q000378:metabolism; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism; D011537:Pruritus / Q000209:etiology* / Q000378:metabolism; D044464:Receptor, PAR-2 / Q000378:metabolism; D012867:Skin / Q000294:innervation
chemical_list: D016760:Proto-Oncogene Proteins c-fos; D044464:Receptor, PAR-2; D006632:Histamine