title: Effect of 2,3,7,8-tetrachlorodibenzo-p-dioxin on scratching behavior in mice.
abstract: The present study was performed to study the effect of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on scratching behavior in hairless mice, which are highly sensitive to pruritogens (mediators causing itching), except for histamine, and are suitable for time-course studies due to their hairless skin. TCDD is a well-known environmental pollutant that causes skin diseases with itching; therefore, we examined whether TCDD induced itching. Oral administration of TCDD caused no increase in scratching behavior when used alone, whereas TCDD in combination with distilled water or acetone/olive oil application caused a significant increase in scratching behavior. Furthermore, nerve growth factor (NGF) content in the skin increased significantly. A single administration of chlorpheniramine (histamine H1 receptor antagonist), tranilast (chemical mediator release inhibitor) and olopatadine (histamine H1 receptor antagonist) had no effect on scratching behavior induced by TCDD in combination with acetone/olive oil application. With repeated administration for 7 days, chlorpheniramine and tranilast had no effect on scratching behavior, whereas olopatadine significantly inhibited scratching behavior. In addition, only olopatadine significantly inhibited NGF content in the skin. From these findings, it can be concluded that TCDD is not a pruritogen but causes alloknesis (itchy skin) with the simultaneous use of trivial external stimulation. In addition, it was found that drugs which decreased skin NGF contents may inhibit this scratching behavior.
authors.affiliation: Department of Medicinal Pharmacology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan.
authors.forename: Rie
authors.initials: R
authors.lastname: Ono
authors.forename: Yoto
authors.initials: Y
authors.lastname: Kagawa
authors.forename: Yuji
authors.initials: Y
authors.lastname: Takahashi
authors.forename: Masaki
authors.initials: M
authors.lastname: Akagi
authors.forename: Chiaki
authors.initials: C
authors.lastname: Kamei
mesh_terms: D000096:Acetone / Q000494:pharmacology; D000818:Animals; D000982:Antipruritics / Q000494:pharmacology; D001522:Behavior, Animal / Q000187:drug effects; D004785:Environmental Pollutants / Q000633:toxicity*; D006634:Histamine H1 Antagonists / Q000494:pharmacology; D007509:Irritants; D008297:Male; D051379:Mice; D008812:Mice, Hairless; D020932:Nerve Growth Factor / Q000378:metabolism; D000069463:Olive Oil; D010938:Plant Oils / Q000494:pharmacology; D000072317:Polychlorinated Dibenzodioxins / Q000633:toxicity*; D011537:Pruritus / Q000139:chemically induced* / Q000523:psychology*; D012867:Skin / Q000737:chemistry / Q000378:metabolism
chemical_list: D000982:Antipruritics; D004785:Environmental Pollutants; D006634:Histamine H1 Antagonists; D007509:Irritants; D000069463:Olive Oil; D010938:Plant Oils; D000072317:Polychlorinated Dibenzodioxins; D000096:Acetone; D020932:Nerve Growth Factor