κ-阿片受体在改善高脂血症引起的血管内皮功能失调中的作用及其机制

Endothelial dysfunction induced by hyperlipidemia is recognized as one of the pivotal parts in the pathogenesis of metabolic syndrome and a variety of cardiovascular and cerebrovascular complications. Previous researches have demonstrated that hyperlipidemia-induced endothelial dysfunction is characterized by the imbalance between the secretion of vasoconstrictor and vasodilator as well as vasculitis. Our former experiments have indicated that κ-opioid receptor (κ-OR) agonist U50,488H relaxes the aorta in an endothelium-dependent manner, elevates NO level, decreases the expression of ET-1 and AngII, and improves the endothelial dysfunction of pulmonary arteries subjected to hypoxia. Moreover, the activation of κ-OR may inhibit myocardial ischemia-induced inflammation. The effects mentioned above are all associated with NO pathways. However, it is still unclear the role of κ-OR in the regulation of endothelial dysfunction in hyperlipidemia. Based on our previous study, the present research intends to further study the mechanisms by which the activation of κ-OR improves endothelial function, from organism, vessel and cell levels, by employing vascular tone measurement, Western-Blot, PCR, immunohistochemistry, co-immunoprecipitation, cell primary culture and siRNA interference. Our goal is to illuminate how NO signal pathways assist κ-OR in improving endothelial dysfunction, and to provide theoretical basis for the prevention and treatment of hyperlipidemia, metabolic syndrome and some other inflammation-associated diseases.

高脂血症导致的内皮功能失调是引起代谢综合征及各种心脑血管疾病并发症的关键环节之一。研究认为高脂血症导致血管内皮损伤后，主要表现为血管内皮分泌的血管舒缩因子平衡失调及血管炎症反应等。我们前期研究表明激活κ-阿片受体（κ-OR）可内皮依赖性的舒张主动脉、提高NO水平、降低ET-1和AngII的表达，并可改善低氧时肺动脉内皮功能失调。另外，激活κ-OR还可抑制心肌缺血引起的炎症反应，以上作用均与NO信号途径密切相关。然而有关κ-OR在高脂血症引起的内皮功能失调中的调节作用及机制尚不清楚。本课题拟在前期研究基础上，利用血管张力测定、Western-Blot、PCR、免疫组化、免疫共沉淀、细胞原代培养和siRNA干扰等技术，从整体、血管和细胞三个水平研究激活κ-OR通过NO信号途径改善高脂血症引起的血管内皮功能失调中的作用及机制，进而为防治高脂血症、代谢综合征及其他炎症相关性疾病提供新的理论依据。

高脂血症及其引起的血管内皮功能障碍是多种心脑血管疾病的重要发病机制。 因此，积极寻找有效的办法防治血管内皮功能障碍可为临床防治心脑血管疾病提供有力的措施。本课题基于高脂血症大鼠模型及高脂诱导的血管内皮细胞损伤模型，利用生理学、分子生物学、免疫组织化学等多种方法深入系统地研究了κ-阿片受体激动剂U50,488H改善高脂血症引起的血管内皮细胞损伤的作用及机制。研究发现：在整体动物水平，κ-阿片受体激动剂U50,488H可显著改善高脂血症引起的血管内皮功能障碍及组织超微结构损伤，此种改善作用与激活PI3K/Akt/eNOS/NO信号通路、抑制iNOS活性及抑制血管组织氧化应激有关，但U50,488H没有调控血脂的作用。在细胞模型水平，U50,488H可显著改善高脂刺激引起的血管内皮细胞凋亡和提高细胞生存率，应用信号通路工具药和转染针对κ-阿片受体及Akt的siRNA等证实了上述作用也与激活PI3K/Akt/eNOS/NO信号通路和抑制caveolin-1有关。U50,488H还可显著降低高脂刺激导致的血管内皮细胞炎症因子和黏附分子表达，并减少中性粒细胞及单个核细胞黏附，从而改善局部炎症反应。综上所述，本课题研究首次揭示了激动κ-阿片受体可通过PI3K/Akt/eNOS/NO 信号通路显著改善高脂血症导致的血管内皮结构和功能损伤，降低局部炎症反应，抑制血管内皮细胞凋亡。研究结果为临床应用κ-阿片受体激动剂治疗高脂血症并将其作为潜在的心血管候选药物提供了新的实验依据。