Enhanced scratching elicited by a pruritogen and an algogen in a mouse model of contact hypersensitivity

• Published in: Neuroscience letters Vol. 579; pp. 190 - 194
• Main Authors: Fu, Kai, Qu, Lintao, Shimada, Steven G., Nie, Hong, LaMotte, Robert H.
• Format: Journal Article
• Language: English
• Published: Ireland Elsevier Ireland Ltd 05.09.2014
• Subjects: Algogen; Allergens; Animals; Behavior, Animal; Contact hypersensitivity; Cyclobutanes; Dermatitis, Allergic Contact - pathology; Dermatitis, Allergic Contact - psychology; Disease Models, Animal; Itch; Male; Mice; Mice, Inbred C57BL; Pain; Peptide Fragments; Pruritogen; Pruritus - chemically induced; Pruritus - psychology; Itch; Algogen; Pain; Pruritogen; Contact hypersensitivity
• ISSN: 0304-3940; 1872-7972
• DOI: 10.1016/j.neulet.2014.03.062

•Contact hypersensitivity (CHS) altered chemically evoked behaviors in mice.•CHS enhanced itch and pain behaviors evoked by BAM8-22.•CHS enhanced the itch but not the pain behaviors evoked by bradykinin.•CHS had no effect on the behaviors evoked by histamine. Chemical pruritogens and algogens evoke primarily itch and pain, respectively, when administered to the skin of healthy human subjects. However, the dominant sensory quality elicited by an algesic chemical stimulus may change in patients with chronic itch where bradykinin, elicits itch in addition to pain. Here we tested whether normally pruritic and algesic chemicals evoked abnormal itch- or pain-like behaviors in the mouse after the development of contact hypersensitivity (CHS), an animal model of allergic contact dermatitis. Mice previously sensitized to a hapten (squaric acid dibutylester) applied to the abdomen, exhibited spontaneous itch-like scratching and pain-like wiping directed to the site on the cheek of the CHS elicited by a subsequent challenge with the same hapten. In comparison with responses of control mice, CHS mice exhibited a significant increase in the scratching evoked by bovine adrenal medulla 8-22, a peptide that elicits a histamine-independent itch, but did not alter the scratching to histamine. Bradykinin, an algogen that elicited only wiping in control mice, additionally evoked significant scratching in CHS mice. Thus, within an area of CHS, histamine-independent itch is enhanced and chemically evoked pain is accompanied by itch.