中文摘要：

目的了解氯化镧（LaCl3）对内毒素／脂多糖（LPS）刺激的巨噬细胞诱导型一氧化氮合酶（iNOS）表达的影响，并探讨其机制。方法将小鼠巨噬细胞株RAW264．7分为空白对照组、LaCl、组、LPS组和LaCl3＋LPS组。前3组细胞分别用常规培养液、含2．50μmol／L LaCl3的培养液、含1mg／L LPS的培养液培养24h，LaCl3＋LPS组用含2．5μmol／LLaCl，的培养液培养24h后，换为含1mg／L LPS的培养液培养24h。采用免疫细胞化学染色法检测iNOS在各组细胞中的表达强度；蛋白质印迹法检测iNOS的蛋白表达水平；反转录一PCR测定iNOS的mRNA表达水平；硝酸还原酶法测定各组细胞培养上清液中一氧化氮（NO）含量。结果免疫细胞化学染色结果显示，iNOS主要分布于各组细胞的胞质中，空白对照组和LaCl3组荧光强度极弱；LPS组荧光强度最强，阳性细胞百分率为44．4％，明显高于LaCl3＋LPS组（11．8％，P〈0．05）。LPS组iNOS蛋白及其mRNA表达量和细胞培养上清液中NO含量均高于其余各组（P〈0．05）。结论LaCl3可在mRNA水平和蛋白水平抑制LPS诱导的iNOS过度表达，减少NO生成，提示LaCl3能拮抗LPS诱导的iNOS过度活化。

英文摘要：

Objective To explore the influence of lanthanum chloride（LaCl3 ） on inducible nitric oxide synthase （iNOS） expression in RAW264.7 macrnphages with lipopolysaccharide（ LPS ）induction, and to investigate its possible mechanisms. Methods The RAW264.7 macrophages were randomly divided into four groups： i. c, control group （without treatment） , LaCl3 group （with treatment of 2.5 μmol/L of LaCl3 for 24 hrs） , LaCl3 ＋ LPS group（ with treatment of 2.5μmol/L LaC13 for 24h） , and LPS group（ with treatment of lmg/L LPS for 24 hrs）. The iNOS protein expression was measured by immunofluoreseence and Western blot. iNOS gene expression was assayed by reverse transcription-polymerase chain reaction （RT-PCR）. NO production in culture supernatant was assayed by nitrate reductase method. Results lmmunofluorescence analysis showed that iNOS was located mainly in the cytoplasm. RAW264.7 cells with ovcrcxprcssion of iNOS accounted for 44.4% , which was obviously higher than that in LaCl3 ＋ LPS group （11. 8% , P 〈 O. 05 ） . There was a faint signal of FITC-labeled green tint in control group or LaCl3 group. The iNOS mRNA and protein expression, and the NO content in LPS group were significantly higher than those in control, LaCI3, and LaCI3 ＋ LPS groups （ P 〈0.05）. Conclusion LaCl3 can suppress LPS-induced iNOS overexpression at mRNA and protein level and reduce NO production , indicating that LaCl3 can antagonize the excessive activation of iNOS induced by LPS.