Koh Eun-Ji, Yoon Seong-Jin, Lee Sun-Mee
School of Pharmacy, Sungkyunkwan University, Suwon, Korea.
Br J Pharmacol. 2013 Jul;169(6):1404-16. doi: 10.1111/bph.12229.
BACKGROUND AND PURPOSE: PPAR-γ has been reported to be a protective regulator in ischaemia/reperfusion (I/R) injury. The receptor for advanced glycation end-products (RAGE) plays a major role in the innate immune response, and its expression is associated with PPAR-γ activation. Several angiotensin receptor blockers possess partial agonist activities towards PPAR-γ. Therefore, this study investigated the action of losartan, particularly with regard to PPAR-γ activation and RAGE signalling pathways during hepatic I/R. EXPERIMENTAL APPROACH: Mice were subjected to 60 min of ischaemia followed by 6 h of reperfusion. Losartan (0.1, 1, 3 and 10 mg · kg⁻¹) was administered 1 h prior to ischaemia and immediately before reperfusion. GW9662, a PPAR-γ antagonist, was administered 30 min prior to first pretreatment with losartan. KEY RESULTS: Losartan enhanced the DNA-binding activity of PPAR-γ in I/R. Losartan attenuated the increased serum alanine aminotransferase activity, TNF-α and IL-6 levels, and nuclear concentrations of NF-κB in I/R. GW9662 reversed these beneficial effects. Losartan caused a decrease in apoptosis as assessed by TUNEL assay, in release of cytochrome c and in cleavage of caspase-3, and these effects were abolished by GW9662 administration. Losartan attenuated not only I/R-induced RAGE overexpression, but also its downstream early growth response protein-1-dependent macrophage inflammatory protein 2 level; phosphorylation of p38, ERK and JNK; and subsequent c-Jun phosphorylation. GW9662 reversed these effects of losartan administration. CONCLUSIONS AND IMPLICATIONS: Our findings suggest that losartan ameliorates I/R-induced liver damage through PPAR-γ activation and down-regulation of the RAGE signalling pathway.
背景与目的:据报道,过氧化物酶体增殖物激活受体γ(PPAR-γ)是缺血/再灌注(I/R)损伤中的一种保护性调节因子。晚期糖基化终产物受体(RAGE)在先天性免疫反应中起主要作用,其表达与PPAR-γ激活相关。几种血管紧张素受体阻滞剂对PPAR-γ具有部分激动活性。因此,本研究探讨了氯沙坦的作用,特别是在肝脏I/R期间对PPAR-γ激活和RAGE信号通路的影响。 实验方法:小鼠经历60分钟缺血,随后再灌注6小时。氯沙坦(0.1、1、3和10mg·kg⁻¹)在缺血前1小时和再灌注前立即给药。PPAR-γ拮抗剂GW9662在首次用氯沙坦预处理前30分钟给药。 主要结果:氯沙坦增强了I/R中PPAR-γ的DNA结合活性。氯沙坦减轻了I/R中血清丙氨酸转氨酶活性、肿瘤坏死因子-α和白细胞介素-6水平以及核因子κB核浓度的升高。GW9662逆转了这些有益作用。通过TUNEL检测、细胞色素c释放和半胱天冬酶-3裂解评估,氯沙坦导致细胞凋亡减少,这些作用在给予GW9662后被消除。氯沙坦不仅减弱了I/R诱导的RAGE过表达,还减弱了其下游早期生长反应蛋白-1依赖性巨噬细胞炎性蛋白2水平;p38、细胞外信号调节激酶和应激活化蛋白激酶的磷酸化;以及随后的c-Jun磷酸化。GW9662逆转了氯沙坦给药的这些作用。 结论与意义:我们的研究结果表明,氯沙坦通过激活PPAR-γ和下调RAGE信号通路改善I/R诱导的肝损伤。
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