线粒体抗氧化肽对脓毒性脑病小鼠认知功能和线粒体功能的影响

Effects of mitochondrial-targeted peptide on cognitive and mitochondrial functions in a mouse model of sepsis-associated encephalopathy

目的观察线粒体抗氧化肽SS-31对脓毒性脑病小鼠认知功能和线粒体功能的影响。方法成年雄性C57BL/6小鼠60只随机分为四组:假手术+生理盐水组(SN组,n=10)、假手术+SS-31组(SS组,n=10)、盲肠结扎穿孔(CLP)+生理盐水组(CN组,n=20)和CLP+SS-31组(CS组,n=20)。术毕每天腹腔注射5mg/kg SS-31(SS、CS组)或等容生理盐水(SN、CN组),连续6d。术后第7、8天,行条件性恐惧实验;行为学测试后处死小鼠,取海马组织检测活性氧自由基(ROS)及三磷酸腺苷(ATP)水平,提取线粒体检测线粒体电子传递链复合物Ⅰ、Ⅱ、Ⅲ、Ⅳ酶活性及线粒体膜电位(MMP)水平。结果与CN组比较,SN、SS和CS组24h场景实验僵直时间明显增加(P<0.05),ROS水平明显降低,ATP、MMP及复合物Ⅰ和Ⅲ酶活性明显升高(P<0.05)。与CS组比较,SN和SS组ROS水平明显降低,ATP、MMP及复合物Ⅰ和Ⅲ酶活性明显升高(P<0.05)。结论线粒体抗氧化肽SS-31可改善脓毒性脑病小鼠认知功能,其机制可能与减轻线粒体损伤有关。

Objective To observe the effects of mitochondrial-targeted peptide SS-31 on cognitive and mitochondrial functions in a mouse model of sepsis-associated encephalopathy （SAE）.Methods Sixty C57BL/6 male mice were randomized into 4 groups：sham operation＋normal saline group （group SN,n=10）,sham operation＋SS-31 group （group SS,n=10）,cecal ligation and puncture （CLP） ＋ normal saline group （group CN,n=20）,and CLP＋SS-31 group （group CS,n=20）.Mice received an administration of SS-31 （5 mg/kg） or equal volume saline immediately and once daily for 6 consecutive days after operation.Fear conditioning test （FCT） was performed on days 7 and 8 on the survived mice.The hippocampal tissues were harvested after behavioral tests and homogenized for measuring levels of reactive oxygen species （ROS） and adenosine-5＇-triphosphate （ATP）.Mitochondria were freshly isolated for measuring enzymes activities of mitochondrial electron transport chain and mitochondrial membrane potential （MMP）.Results Compared with group CN,freezing time at 24 h in the context test,activities of complexes Ⅰ and Ⅲ,ATP and MMP levels increased while ROS level decreased in group SN,SS and CS （P＜0.05）.Compared with group CS,ROS level decreased while ATP and MMP levels and activities of complexes Ⅰ and Ⅲ increased significantly in group SN and SS（P＜0.05）.Conclusion Consecutive administration of SS31 can improve cognitive deficits probably via reversing mitochondrial dysfunction in a mouse model of SAE.