RESUMEN
UNLABELLED: Fish oil (FO), source of omega-3 fatty acids (FA), has been widely studied in the treatment of inflammatory diseases and inflammatory pain (IP). Omega-3 FA give rise to eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids, metabolized to eicosanoids and converted to resolvins with important anti-inflammatory action. AIMS: This study investigates the effects of oral doses of omega-3 FA from FO and concentrated fish oil (CFO) in a model of sub-chronic IP, induced by Complete Freund's Adjuvant (CFA). MAIN METHODS: IP was induced by intraplantar injection of CFA into the right hind paw of Wistar rats. Three groups were pre-treated with omega-3 FA: two groups received CFO (460mg of EPA/360mg of DHA and 690mg of EPA/540mg of DHA) and one group received natural FO (460mg EPA/300mg DHA), for 7days before IP induction (pre-treatment) and 5days after induction (treatment). KEY FINDINGS: TNF-α levels were reduced by CFO 690 (67.9%; p<0.01), CFO 460 (57.7%; p<0.01), FO 460 (26.2%), compared to the augment promoted by CFA (549.7%; p<0.001). Resolvin levels were increased in treated groups with respect to the CFA control group (CFO 690=3196.3%, p<0.01; CFO 460=3347.1%, p<0.01; FO=1653.5%). SIGNIFICANCE: The results indicate that the tested doses reduced inflammatory pain effectively in a short pre-treatment period, through modulation of TNF-α and resolvins and that CFO presented better results than FO. Therefore, Ω-3 FA from FO can be proposed for use as complementary medicine in the treatment of painful and inflammatory diseases.