芦荟大黄素对LPS诱导的RAW264.7细胞NO生成及iNOS表达的影响

目的观察芦荟大黄素(aloe-emodin)对脂多糖(LPS)诱导的RAW264.7细胞一氧化氮(NO)生成及诱生型一氧化氮合酶(iNOS)mRNA表达的作用。方法采用LPS诱导的RAW264.7细胞株建立细胞炎症反应模型。采用Griess试剂法测定NO释放量;采用硝普钠释放NO法测定NO自由基含量的变化;采用反转录聚合酶链反应(RT-PCR)分析iNOS mRNA表达改变。结果芦荟大黄素在0.69～2.50mg·L-1剂量范围内可抑制LPS诱导的RAW264.7细胞NO的释放,并呈剂量和时间依赖关系;芦荟大黄素在0.63～5.00mg·L-1剂量范围内可下调LPS诱导的RAW264.7细胞iNOS mRNA含量;而此范围内芦荟大黄素无直接清除NO自由基作用,不影响iNOS活性。结论芦荟大黄素可明显降低LPS诱导的RAW264.7细胞NO释放,呈时间和剂量依赖关系,此作用并非通过捕捉NO或抑制iNOS活性来实现,而是通过抑制iNOS mRNA表达发挥作用的。

Effect of lipopolysaccharide-induced expression of inducible nitric oxide synthase by aloe-emodin in RAW264.7 cells

Aim To investigate the effect of aloe-emodin on lipopolysaccharide(LPS)-induced production of nitric oxide and expression of inducible nitric oxide synthase in RAW264.7 cells.Methods RAW264.7 macrophage line in mice was induced by LPS to set up the inflammatory model.Nitric oxide(NO)production was examined by Griess reaction;the expression of iNOS mRNA was detected by RT-PCR analysis;NO radical generation was tested by sodium nitroprusside method.Results Aloe-emodin at the dose of 0.69～2.5 mg·L~(-1) exhibited the inhibitory effect on LPS-induced NO production in a dose-dependent and time-dependent manner;aloe-emodin at the dose of 0.63～5.00 mg·L~(-1) suppressed LPS-induced iNOS mRNA expression in RAW 264.7 cells.However,aloe-emodin had no scavenging effect on sodium nitroprusside-triggered NO production,and didn't affect iNOS enzyme activity.Conclusion Aloe-emodin inhibited signifi-cantly LPS-induced NO production through suppressing inducible NO synthase(iNOS)expression at mRNA level in a dose-dependent and time-dependent manner,but failed to affect sodium nitroprusside-triggered NO production and iNOS enzyme activity.