Abstract: ObjectiveTo observe the protective effects and antioxidant mechanism of docosahexaenoic acid(DHA)on lipopolysaccharide(LPS)-induced acute lung injury(ALI)in mice.MethodsMale Kunming mice were randomly divided into low dose DHA+LPS group,high dose DHA+LPS group,DHA group,LPS group,and control group.The mice of low and high dose DHA+LPS groups were treated with DHA at dosage of 250 and 500 mg/kg·bw.The mice of DHA group were treated with 500 mg/kg·bw and those in control group with equivalent corn oil by gavage daily for 10 days.At the 11th day,the mice in LPS groups were given 6 mg/kg·bw LPS by intraperitoneal injection to develop ALI model,and the mice in another two groups were treated with equivalent saline.Sixteen hours later,the lung pathologic changes together with the oxidation and antioxidant parameters in bronchial-alveolar lavage fluid(BALF)and lung tissues were detected.ResultsThe results showed that the DHA could ameliorate lung pathologic changes such as alveolar interval thickening and inflammatory neutrophilic exudates induced by LPS.LPS treatment also impaired oxidation-antioxidation balance of lung tissues.Compared to the LPS group,the medulary peroxidase(MPO)activities decreased by 12.2% (P<0.05)and 27.6% (P<0.01)and the levels of malondialdehyde(MDA)decreased by 12.5% (P<0.05)and 25.5% (P<0.01)in lung tissues following 250 mg/kg·bw and 500 mg/kg·bw treatment,respectively.The superoxide dismutase(SOD)activities were increased by 13.2% (P<0.05)and 23.0% (P<0.01)for BALF,19.9% (P<0.01)and 36.1% (P<0.01)for lung tissue.Glutathione peroxidase(GSH-P_X)activities were also upregulated by 20.2% (P<0.01)and 33.1% (P<0.01),and total antioxidant capacity(T-AOC)increased by 48.5% (P<0.01)and 102.4% (P<0.01)after 250 mg/kg·bw and 500 mg/kg·b DHA administration,respectively.ConclusionDHA treatment could reduce LPS-induced lung tissue injury,and the oxidative stress amelioration might account for its preventive effects in mice.