Choy Ker Woon, Lau Yeh Siang, Murugan Dharmani, Mustafa Mohd Rais
Department of Pharmacology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia.
PLoS One. 2017 May 31;12(5):e0178365. doi: 10.1371/journal.pone.0178365. eCollection 2017.
Endoplasmic reticulum (ER) stress leads to endothelial dysfunction which is commonly associated in the pathogenesis of several cardiovascular diseases. We explored the vascular protective effects of chronic treatment with paeonol (2'-hydroxy-4'-methoxyacetophenone), the major compound from the root bark of Paeonia suffruticosa on ER stress-induced endothelial dysfunction in mice. Male C57BL/6J mice were injected intraperitoneally with ER stress inducer, tunicamycin (1 mg/kg/week) for 2 weeks to induce ER stress. The animals were co-administered with or without paeonol (20 mg/kg/oral gavage), reactive oxygen species (ROS) scavenger, tempol (20 mg/kg/day) or ER stress inhibitor, tauroursodeoxycholic acid (TUDCA, 150 mg/kg/day) respectively. Blood pressure and body weight were monitored weekly and at the end of treatment, the aorta was isolated for isometric force measurement. Protein associated with ER stress (GRP78, ATF6 and p-eIF2α) and oxidative stress (NOX2 and nitrotyrosine) were evaluated using Western blotting. Nitric oxide (NO) bioavailability were determined using total nitrate/nitrite assay and western blotting (phosphorylation of eNOS protein). ROS production was assessed by en face dihydroethidium staining and lucigenin-enhanced chemiluminescence assay, respectively. Our results revealed that mice treated with tunicamycin showed an increased blood pressure, reduction in body weight and impairment of endothelium-dependent relaxations (EDRs) of aorta, which were ameliorated by co-treatment with either paeonol, TUDCA and tempol. Furthermore, paeonol reduced the ROS level in the mouse aorta and improved NO bioavailability in tunicamycin treated mice. These beneficial effects of paeonol observed were comparable to those produced by TUDCA and tempol, suggesting that the actions of paeonol may involve inhibition of ER stress-mediated oxidative stress pathway. Taken together, the present results suggest that chronic treatment with paeonol preserved endothelial function and normalized blood pressure in mice induced by tunicamycin in vivo through the inhibition of ER stress-associated ROS.
内质网（ER）应激会导致内皮功能障碍，这在几种心血管疾病的发病机制中普遍存在。我们探讨了用丹皮酚（2'-羟基-4'-甲氧基苯乙酮）进行长期治疗的血管保护作用，丹皮酚是牡丹根皮中的主要化合物，对小鼠内质网应激诱导的内皮功能障碍的影响。雄性C57BL/6J小鼠腹腔注射内质网应激诱导剂衣霉素（1毫克/千克/周），持续2周以诱导内质网应激。动物分别同时给予或不给予丹皮酚（20毫克/千克/灌胃）、活性氧（ROS）清除剂tempol（20毫克/千克/天）或内质网应激抑制剂牛磺熊去氧胆酸（TUDCA，150毫克/千克/天）。每周监测血压和体重，在治疗结束时，分离主动脉进行等长力测量。使用蛋白质印迹法评估与内质网应激相关的蛋白质（GRP78、ATF6和p-eIF2α）和氧化应激相关的蛋白质（NOX2和硝基酪氨酸）。使用总硝酸盐/亚硝酸盐测定法和蛋白质印迹法（eNOS蛋白的磷酸化）测定一氧化氮（NO）的生物利用度。分别通过表面二氢乙锭染色和光泽精增强化学发光测定法评估ROS的产生。我们的结果显示，用衣霉素治疗的小鼠血压升高、体重减轻且主动脉内皮依赖性舒张（EDR）受损，而与丹皮酚、TUDCA和tempol联合治疗可改善这些情况。此外，丹皮酚降低了小鼠主动脉中的ROS水平，并改善了衣霉素处理小鼠的NO生物利用度。观察到的丹皮酚的这些有益作用与TUDCA和tempol产生的作用相当，表明丹皮酚的作用可能涉及抑制内质网应激介导的氧化应激途径。综上所述，目前的结果表明，在体内，丹皮酚长期治疗可通过抑制内质网应激相关的ROS来维持内皮功能并使衣霉素诱导的小鼠血压正常化。
