脂多糖通过MAPK通路影响星形胶质细胞的谷胱苷肽和肿瘤坏死因子生成

Lipopolysaccharides affect the production of glutathione and TNF-α of astrocytes through MAPK pathway

目的研究脂多糖(LPS)对原代培养的星形胶质细胞(AC)代谢的影响及其可能机制。方法原代培养AC,予以LPS作用30min、24、48和72h后,观察AC的生存率、肿瘤坏死因子α(TNF-α)、谷胱苷肽(GSH)和谷胱苷肽过氧化物酶(GPx)含量的变化,Western blot检测AC磷酸化MAPK家族信号蛋白P-p38的表达,观察MAPK通路抑制剂对TNF-α分泌的影响。结果低剂量LPS促进AC增殖,高剂量抑制。LPS(10μg/ml)作用72h后细胞内GPx活性降低,GSH含量下降。TNF-α的含量随LPS作用时间延长而升高,48h后与对照组相比有显著性差异,P-p38蛋白高峰出现在24h,随后下降。MAPK通路抑制剂可阻断TNF-α的升高。结论LPS激活的AC下调GSH的表达,增加TNF-α的分泌,其可能的分子机制是激活MAPK通路。

Objective To investigate the effects of lipopolysaccharide（LPS） on metabolism of the astrocytes and possible mechanism. Methods After LPS was applied to rat astrocytes for 30min, 24 h, 48 h and 72 h, the change of astrocytes growth was analyzed. Tumor necrosis factor alpha （TNF-α） secreted by astrocytes, glutathione peroxidase （GPx） activity and glutathione （GSH） in astrocytes were detected,and phospho-p38 protein expressed in astrocytes was assayed with Western blot. Moreover, the effect of MAPK inhibitor on TNF-α was studied. Results LPS of low concentration promoted proliferation of astrocyte while high concentration inhibited. Among all the different time points, the GPx activity and GSH amount decreased only at 72 h compared to those of the control （P〈0. 05）. The TNF-α secreted by astrocytes increased as time went on, and P-p38 protein expressed most intensely at 24 h, and decreased subsequently. Pretreatment with PD98059 （inhibitor of MAPK） could block the increase of TNF-α. Conclusion LPS can promote astrocytes to secrete TNF-α and decrease the release of GSH. The molecular mechanism of the changes may be related to the expression of p38.