1. Involvement of a capsaicin-sensitive TRPV1-independent mechanism in lipopolysaccharide-induced fever in chickens
- Author
-
Hideki Nikami, Motamed Elsayed Mahmoud, Moustafa M. Ahmed, Reem Mahmoud Dosoky, Tadashi Takewaki, Yasutake Shimizu, and Takahiko Shiina
- Subjects
Lipopolysaccharides ,Male ,medicine.medical_specialty ,Time Factors ,Lipopolysaccharide ,Fever ,Physiology ,TRPV1 ,TRPV Cation Channels ,Nitric Oxide ,Biochemistry ,Body Temperature ,chemistry.chemical_compound ,Transient receptor potential channel ,Internal medicine ,medicine ,Animals ,Molecular Biology ,Cells, Cultured ,Nitrites ,Antagonist ,Analgesics, Non-Narcotic ,Endocrinology ,chemistry ,Animals, Newborn ,Capsaicin ,Macrophages, Peritoneal ,lipids (amino acids, peptides, and proteins) ,Capsazepine ,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.
- Published
- 2007