AIM:To investigate the effects of losartan on lipopolysaccharide (LPS)-induced glial fibrillary acidic protein (GFAP) expression,and to determine whether adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK) activation is involved in the mechanism.METHODS:Adult male KM mice were divided into control group,LPS model group,losartan treatment group,and losartan and Compound C co-treatment group.To establish a model of central nervous system inflammation,the mice received daily intracerebroventricular injection of LPS (24 μg/d) for 2 d.Daily losartan administration (0.5,1 or 5 mg · kg-1 · d-1,ip) initiated at 14 d prior to LPS injection.Compound C (10 mg/kg,ip),a selective AMPK inhibitor,started to be injected daily at 2 d prior to LPS injection.The hippocampal tissues in each group were isolated at 3 d after the last LPS injection,and then the protein levels of GFAP,AMPK,p-AMPK,mammalian target of rapamycin (mTOR) and p-mTOR were determined by Western blot.RESULTS:Twice LPS injections significantly increased the expression of GFAP in the hippocampus (P ＜ 0.01).Losartan inhibited LPS-induced GFAP expression in a concentration-dependent way,and losartan at 5 mg· kg-1 · d-1 significantly inhibited GFAP expression and AMPK activation (P ＜ 0.05),but it had no obvious effect on mTOR activation.Furthermore,Compound C significantly reversed the effect of losartan treatment on LPS-induced GFAP expression and AMPK phosphorylation (P ＜ 0.05).CONCLUSION:Losartan inhibits LPS-induced GFAP expression in the mouse hippocampus,and AMPK activation but not mTOR,is involved in the mechanism.%目的:探讨氯沙坦对脂多糖(LPS)诱导的星形胶质细胞活化标志物胶质纤维酸性蛋白(GFAP)表达的影响,以及其机制是否与激活腺苷酸活化蛋白激酶(AMPK)有关.方法:将成年雄性昆明小鼠分为正常对照组、LPS模型组、氯沙坦给药组及氯沙坦与compound C合用组.侧脑室注射相同剂量LPS(24 μg/d,每天1次,共2次),以建立中枢神经炎症损伤模型;氯沙坦(0,5、1或5 mg· kg-1 ·d-1)于LPS注射前14 d开始连续每日腹腔注射给药;AMPK抑制剂Compound C(10 mg·kg-1·d-1)于LPS注射前2d开始连续每日腹腔注射给药.在LPS末次注射后的第3天取各组小鼠的海马脑区组织,利用Western blot法检测GFAP、AMPK、p-AMPK、哺乳动物雷帕霉素靶蛋白(mTOR)和p-mTOR的蛋白水平.结果:2次LPS注射后可显著诱导GFAP在海马脑区的表达(P＜0.01),而氯沙坦可浓度依赖地抑制LPS诱导的GFAP表达,当氯沙坦剂量为5 mg·kg-1·d-1时可显著抑制GFAP表达(P＜0.05),同时,在该剂量下,氯沙坦显著提高了AMPK的磷酸化水平(P＜0.01),但对mTOR的磷酸化水平无明显调节作用;而AMPK抑制剂Compound C可显著逆转氯沙坦对GFAP表达及AMPK磷酸化的调节作用(P＜0.05).结论:氯沙坦可抑制LPS诱导的海马GFAP表达,该作用可能与其激活AMPK有关,但并不依赖于mTOR信号通路.
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