N-乙酰半胱氨酸对脂多糖诱导的小鼠肝MAPK磷酸化的影响

Effects of N-acetylcysteine on the lipopolysaccharide-induced MAPK phosphorylation in mouse liver

目的:探讨N-乙酰半胱氨酸(NAC)对脂多糖(LPS)诱导的肝MAPK磷酸化的影响。方法:雄性昆明种小鼠54只随机分为对照组(n=6):0.9%NaCl0.2mLip;LPS组(n=24):LPS5mgip;NAC+LPS组(n=24):NAC150mg·kg-1.d-1ip,连续3d;第3dNAC灌胃后1h时,LPS5mgip。将小鼠分别在注射LPS或生理盐水后0.5h、1h、2h和6h时,在戊巴比妥钠麻醉下开腹取肝,测定肝MDA和还原型谷胱甘肽(GSH)含量;Western blotting方法测定肝脏MEK1/2、ERK1/2、p38MAPK磷酸化水平,放免法测定肝TNF-α含量。结果:NAC预处理使肝MDA含量明显下降,使肝GSH含量升高。NAC预处理显著抑制了LPS所致的肝MEK1/2、ERK1/2、p38MAPK磷酸化,同时使肝TNF-α水平显著降低。结论:在LPS诱导的急性肝损伤过程中,活性氧(ROS)在激活MAPK信号转导中起重要作用。NAC通过其抗氧化作用部分抑制了LPS诱导的MAPK磷酸化,使TNF-α生成减少,从而发挥抗损伤作用。

AIM： To investigate the effects of antioxidant N -acetylcysteine （NAC） on the lipopolysaccharide （LPS） -induced MAPK phosphorylation in mouse liver. METHODS： 54 male mice were divided into three groups： control （n =6） , 0. 9% sodium chloride 0. 2 mL ip; LPS group （n =24） ： LPS 5 mg ip; NAC ＋ LPS group （n =24） ： NAC 150 mg·kg^-1·d^-1ip, for 3 d; LPS 5 mg ip after 1 h of NAC administration at 3rd day. The liver was excised with carbrital anesthesia after LPS or 0. 9 % sodium chloride injection at 0.5 h, 1 h, 2 h and 6 h for GSH and MDA assays. The protein extracted from liver was assayed for the phosphorylation of MEK1/2, ERK1/2, p38 MAPK by Western blotting. TNF - α in liver was assayed by radioimmunoassay. RESULTS ： MDA in the liver was decreased remarkably and the GSH in the liver was increased significantly by NAC pretreatment. The phosphorylation of MEK1/2, ERK1/2 and p38 MAPK in liver were inhibited significantly by NAC pretreatment after LPS challenge. Meanwhile, TNF - α in liver was decreased markedly. CONCLUSION ： Reactive oxygen species plays a critical role in MAPK signaling during the LPS induced acute liver injury. NAC partially inhibits LPS - induced MAPK signaling by antioxidant effect and decreases TNF - α production.