Fish oil attenuates persistent inflammatory pain in rats through modulation of TNF-α and resolvins

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.AimsThis 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 methodsIP 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 (460 mg of EPA/360 mg of DHA and 690 mg of EPA/540 mg of DHA) and one group received natural FO (460 mg EPA/300 mg DHA), for 7 days before IP induction (pre-treatment) and 5 days after induction (treatment).Key findingsTNF-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%).SignificanceThe 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.