title: Involvement of a capsaicin-sensitive TRPV1-independent mechanism in lipopolysaccharide-induced fever in chickens.
abstract: It has been demonstrated that capsaicin blocks lipopolysaccharide (LPS)-induced fever in mammals. In this study, we investigated TRPV1 (transient receptor potential ion channel of vanilloid subtype-1)-independent action of capsaicin on LPS-induced fever in chickens. The chicken is a valuable model for this purpose because chicken TRPV1 has been shown to be insensitive to capsaicin and thus the effects of capsaicin can be attributed to TRPV1-independent mechanisms. Administration of capsaicin (10 mg/kg, iv) to conscious unrestrained chicks at 5 days of age caused a transient decrease in body temperature. This effect of capsaicin was not observed in chicks that had been pretreated twice with capsaicin, indicating that the capsaicin-sensitive pathway can be desensitized. LPS (2 mg/kg, ip) induced fever that lasted for about 2.5 h, but fever was not induced in chicks that had been pretreated with capsaicin for 2 days. The preventive effect of capsaicin on LPS-induced fever was not blocked by capsazepine, an antagonist for TRPV1, but the antagonist per se blocked the febrile response to LPS. These findings suggest that a capsaicin-sensitive TRPV1-independent mechanism may be involved in LPS-induced fever.
authors.affiliation: Department of Basic Veterinary Science, Laboratory of Physiology, The United Graduate School of Veterinary Sciences, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan.
authors.forename: Motamed Elsayed
authors.initials: ME
authors.lastname: Mahmoud
authors.forename: Yasutake
authors.initials: Y
authors.lastname: Shimizu
authors.forename: Takahiko
authors.initials: T
authors.lastname: Shiina
authors.forename: Hideki
authors.initials: H
authors.lastname: Nikami
authors.forename: Reem Mahmoud
authors.initials: RM
authors.lastname: Dosoky
authors.forename: Moustafa Mohamed
authors.initials: MM
authors.lastname: Ahmed
authors.forename: Tadashi
authors.initials: T
authors.lastname: Takewaki
mesh_terms: D018712:Analgesics, Non-Narcotic / Q000494:pharmacology* / Q000627:therapeutic use; D000818:Animals; D000831:Animals, Newborn; D001831:Body Temperature / Q000187:drug effects*; D002211:Capsaicin / Q000031:analogs & derivatives / Q000494:pharmacology* / Q000627:therapeutic use; D002478:Cells, Cultured; D002645:Chickens; D005334:Fever / Q000139:chemically induced / Q000378:metabolism / Q000503:physiopathology / Q000517:prevention & control*; D008070:Lipopolysaccharides; D017737:Macrophages, Peritoneal / Q000187:drug effects / Q000378:metabolism; D008297:Male; D009569:Nitric Oxide / Q000378:metabolism; D009573:Nitrites / Q000378:metabolism; D050916:TRPV Cation Channels / Q000037:antagonists & inhibitors / Q000378:metabolism*; D013997:Time Factors
chemical_list: D018712:Analgesics, Non-Narcotic; D008070:Lipopolysaccharides; D009573:Nitrites; D050916:TRPV Cation Channels; C440499:lipopolysaccharide, Escherichia coli O111 B4; D009569:Nitric Oxide; C071423:capsazepine; D002211:Capsaicin