环磷酸腺苷葡甲胺预先给药对内毒素致大鼠急性肺损伤的影响

Effects of meglumine cyclic adenylate pretreatment on acute lung injury induced by lipopolysaccharide in rats

目的 探讨环磷酸腺苷葡甲胺预先给药对内毒素（LPS）致大鼠急性肺损伤（ALI）的影响.方法 健康成年雄性SD大鼠54只,2-3月龄,体重200 - 250 g,采用随机数字表法,将其分为3组（n=18）：对照组（C组）、LPS组和环磷酸腺苷葡甲胺预先给药组（MCA组）.LPS组和MCA组股静脉注射LPS 10 mg/kg制备大鼠ALI模型,C组注射等容量生理盐水.MCA组于LPS注射前20 min时股静脉注射环磷酸腺苷葡甲胺2 mg/kg,C组和LPS组注射等容量生理盐水.于LPS注射前即刻、注射后2和4h时各取6只大鼠,采集腹主动脉血样行血气分析,记录PaO2和PaCO2,采用ELISA法测定血浆TNF-α和IL-10浓度.于LPS注射后4h时处死6只大鼠,取肺组织,电镜下观察病理学改变,采用ELISA法测定环磷酸腺苷（cAMP）的活性,采用Western blot法检测核蛋白NF-κB p65表达水平.结果 与C组比较,LPS组PaO2和肺组织cAMP活性降低,PaCO2、血浆TNF-α和IL-10的浓度及肺组织核蛋白NF-κB p65表达水平升高（P＜0.05）.与LPS组比较,MCA组PaO2、肺组织cAMP活性与血浆IL-10浓度升高,PaCO2、血浆TNF-α浓度和肺组织核蛋白NF-κB p65表达水平降低（P＜0.05）,病理学损伤减轻.结论 环磷酸腺苷葡甲胺预先给药可减轻LPS致大鼠ALI,其机制可能与增强肺组织细胞内cAMP水平,激活cAMP信号通路,抑制NF-κB活性,减轻炎性反应有关.

Objective To evaluate the effects of meglumine cyclic adenylate （MCA） pretreatment on acute lung injury （ALI） induced by lipopolysaccharide （LPS） in rats.Methods Fifty-four adult male Sprague Dawley rats,aged 2-3 months,weighing 200-250 g,were randomly divided into 3 groups （n =18 each） using a random number table：control group （group C）,ALI group and MCA pretreatment group （group MCA）.ALI was induced with LPS 10 mg/kg injected via the femoral vein in ALI and MCA groups.In group MCA,MCA 2 mg/kg was injected via the femoral vein at 20 min before LPS injection,while the equal volume of normal saline was given in C and LPS groups.Immediately before LPS injection and at 2 and 4 h after LPS injection,the blood samples were taken from the abdominal aorta for determination of PaO2,PaCO2 and plasma concentrations of tumor necrosis factor-alpha （TNF-α） and interleukin-10 （IL-10）.Six rats were sacrificed at 4 h after LPS injection and pulmonary specimens were obtained for microscopic examination of the pathological changes and for determination of cyclic adenosine monophosphate （cAMP） activity （by ELISA） and NF-κB p65 expression in nucleus （by Western blot）.Results Compared with group C,PaO2 and cAMP activity in lung tissues were significantly decreased,and PaCO2,plasma concentrations of IL-10 and TNF-α and NF-κB p65 expression in nucleus in lung tissues were increased in group LPS.Compared with group LPS,PaO2,cAMP activity in lung tissues and plasma concentrations of IL-10 were significantly increased,and PaCO2,plasma concentration of TNF-α and NF-κB p65 expression in nucleus in lung tissues were decreased and the pathologic changes of lungs were attenuated in group MCA.Conclusion MCA pretreatment can attenuate ALI induced by LPS,and the mechanism is related to increased level of cAMP,activated cAMP signaling pathway,inhibited NF-κB activity and reduced inflammatory responses in lung tissues of rats.