Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)This study aims to explore the contribution of endocannabinoids on the cascade of mediators involved in LPS-induced fever and to verify the participation of prostaglandins and endogenous opioids in fever induced by anandamide (AEA). Body temperature (Tc) of male Wistar rats was recorded over 6 h, using a thermistor probe. Cerebrospinal fluid concentration of PGE(2) and beta-endorphin were measured by ELISA after the administration of AEA. Intracerebroventricular administration of the CBI receptor antagonist AM251 (5 pig, i.c.v.), reduced the fever induced by IL-1 beta (3 ng, i.c.v.), TNF-alpha (250 ng, i.c.v.), IL-6 (300 ng, i.c.v.), corticotrophin release factor (CRH; 2.5 mu g, i.c.v.) and endothelin (ET)-1 (1 pmol, i.c.v.), but not the fever induced by PGE(2) (250 ng, i.c.v.) or PGF(2 alpha), (250 ng, i.c.v.). Systemic administration of indomethacin (2 mg kg(-1), i.p.) or celecoxib (5 mg kg(-1), p.o.) reduced the fever induced by AEA (1 mu g, i.c.v.), while naloxone (1 mg kg(-1), s.c.) abolished it. The increases of PGE(2) and beta-endorphin concentration in the CSF induced by AEA were abolished by the pretreatment of rats with AM251. These results suggest that endocannabinoids are intrinsically involved in the pyretic activity of cytokines (IL-1 beta, TNF-alpha, IL-6), CRH and ET-1 but not the PGE(2) or PGF(2 alpha), induced fevers. However, anandamide via CB1 receptor activation induces fever that is dependent on the synthesis of prostaglandin and opioids. (C) 2015 Elsevier Inc. All rights reserved.51 204211Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)CNPq [CNPq 304627/2007-0]FAPESP [FAPESP 2007/04791-1]