Objective：To explore the antioxidant mechanisms of DHA in the brain of aged rats.Methods：Wistar male rats were randomly divided into four groups including 7-month-old adult group,20-month-old aged group,and low-dose and high-dose DHA-treated 20-month-old aged groups at the respective doses of 180 mg/（kg·d） and 360 mg/（kg·d）（administered by gavage for 42 consecutive days）.At the end of the administration period,all rats were sacrificed and the activities of superoxide dismutase（SOD）,gtutathione peroxidase（GSH-Px） and catalase（CAT） and the level of malondialdehyde（MDA） were assayed in brain.In addition,the fatty acid profile in brain was analyzed by gas chromatography-mass spectrometry,and the phospholipid composition was also analyzed by thin layer chromatography and phosphomolybdate methods.Results：Compared with the aged group,the activities of SOD,GSH-Px and CAT in the brain of the DHA-treated groups were significantly increased and MDA content was significantly decreased.Fatty acid analysis showed that DHA-treated rats exhibited an obvious increase in the ratio of total n-3 fatty acids to total n-6 fatty acids and the ratio of DHA to arachidonic acid（AA） and an obvious reduction in AA level.It was also revealed that DHA could improve the levels of phosphatidylcholine,phosphatidylethanolamine,phosphatidylinositol,phosphatidylserine and sphingomgelins in the brain of rats.Conclusion：DHA can obviously improve antioxidant capacity in aged rats and its antioxidant mechanism may be due to DHA-induced change of fatty acid profile in the brain.%目的：研究二十二碳六烯酸（DHA）改善老年大鼠抗氧化的可能机制。方法：动物分为青年组（7月龄青年雄性大鼠）、老年组（20月龄雄性大鼠）、DHA低剂量组（灌喂20月龄雄性大鼠DHA 180mg/（kg.d）42d）、DHA高剂量组（灌喂20月龄雄性大鼠360mg/（kg.d）42d）,处死大鼠后测定脑组织中超氧化物歧化酶（SOD）、谷胱甘肽过氧化物酶（GSH-Px）、过氧化氢酶（CAT）活力、丙二醛（MDA）含量,然后用气相色谱-质谱联用分析法分析脑脂肪酸组成及含量,最后用薄层层析和磷钼酸法分析磷脂构成。结
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