Enhanced scratching elicited by a pruritogen and an algogen in a mouse model of contact hypersensitivity.
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.
Department of Anesthesiology, Yale University School of Medicine, New Haven, CT 06520, USA; Guangdong Province Key Laboratory of Pharmacodynamic Constituents of TCM and New Drugs Research, College of Pharmacy, Jinan University, Guangzhou 510632, Guangdong, China.
Kai
K
Fu
Department of Anesthesiology, Yale University School of Medicine, New Haven, CT 06520, USA.
Lintao
L
Qu
Department of Anesthesiology, Yale University School of Medicine, New Haven, CT 06520, USA.
Steven G
SG
Shimada
Guangdong Province Key Laboratory of Pharmacodynamic Constituents of TCM and New Drugs Research, College of Pharmacy, Jinan University, Guangzhou 510632, Guangdong, China. Electronic address: hongnie1970@163.com.
Hong
H
Nie
Department of Anesthesiology, Yale University School of Medicine, New Haven, CT 06520, USA. Electronic address: robert.lamotte@yale.edu.
Robert H
RH
LaMotte
D000485:Allergens; D000818:Animals; D001522:Behavior, Animal; D003503:Cyclobutanes; D017449:Dermatitis, Allergic Contact / Q000473:pathology / Q000523:psychology*; D004195:Disease Models, Animal; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D010446:Peptide Fragments; D011537:Pruritus / Q000139:chemically induced* / Q000523:psychology*
D000485:Allergens; D003503:Cyclobutanes; D010446:Peptide Fragments; C571042:bovine adrenal medulla 8-22; C020637:squaric acid dibutyl ester
Algogen; Contact hypersensitivity; Itch; Pain; Pruritogen