大黄素影响巨噬细胞升高[Ca2+]i 和释放TNF-α的作用特征

为了研究大黄素（emodin)对正常的和细菌脂多糖（LPS）刺激的大鼠腹腔巨噬细胞（PMφ）释放肿瘤坏死因子α（TNF－α）和升高Ca^2 ]i的影响，应用L929细胞系和MTT法检测TNF－α量，同时用激光共焦扫描显微术检测单细胞Ca^2 ]i变化动力学。结果显示大黄素能轻度促进正常PMφ释放TNF－α，并发现大黄素诱发PMφCa^2 ]i变化呈振荡波模式。大黄紫显著抑制LPS刺激PMφ过度释放TNF－α和升高Ca^2 ]i，10^-5mol/L大黄素抑制了10mg/L LPS刺激的TNF－α峰值的50％和Ca^2 ]i峰值的68％。LPS诱发MPφCa^2 ]i变化呈现高幅值的“平台期”，大黄素使之转变为低幅值的波动变化。以上结果说明，大黄素对PMφ释放TNF－α和升高Ca^2 ]i表现出的双向调节作用之间有一定的相关性，大黄素对LPS诱发的Ca^2 ]i升高的调制，可能是抑制LPS刺激PMφ释放TNF－α的信号传导通路中的重要环节。

THE EFFECT OF EMODIN ON THE INCREASE OF [Ca2+]i AND TNF-α PRODUCTION IN LIPOLYSACCHARIDE-STIMULATED RAT MACROPHAGES

To explore the role of emodin on increase in Ca²⁺]_i and TNF-α production in normal and lipopolysaccharide (LPS)-stimulated rat peritoneal macrophages (PMφ), TNF-α production was determined using TNF-α-sensitive L929 cell line and by MTT method and the kinetics of intracellular free Ca²⁺ concentration (Ca²⁺]_i) in a single cell were monitored continuously by confocal laser scanning microscope. The results showed that 10^-5 mol/L emodin could elevate TNF-α production slightly, and caused forming low amplitude Ca²⁺]_ioscillation in normal single PMφ. Emodin could inhibit both excessive release of TNF-α and increase in Ca²⁺]_i when PMφ was stimulated by LPS. 10^-5 mol/L emodin inhibited TNF-α production by 50% and Ca²⁺]_i increase by 68% respectively. Interestingly, emodin could transform the high amplitude "plateau-like" Ca²⁺]_i induced by LPS into fluctuation that has low amplitude. These results indicate that the biphase characteristics of modulation of Emodin on TNF-α production correlate with Ca²⁺]_i changing. The modulation of emodin on Ca²⁺]_i may be a main way that emodin inhibits TNF-α production in LPS stimulated PMφ.