| Objective:1. To observe whether high-calorie and high-cholesterol diet(HCD) can inducevascular endothelial damages and the pathological changes in C57BL/6mice, andfurther to investigate the beneficial effects of fenofibrate(FF).2. To investigate whether palmitate(PA) can induce endoplasmic reticulum stress(ER stress) and cell apoptosis in mouse aortic endothelial cells (MAEC), and further toinvestigate the beneficial effects of fenofibric acid (FA).Methods：1. In-vivo studies: The mice were randomly divided into standard chow diet (SCD)group, HCD group and HCD+FF treatment group. The model of metabolic syndromeusing C57BL/6mice was established with HCD for3months, and treated withfenofibrate by gavage. Glucose tolerance test(GTT) and insulin tolerance test(ITT)were performed to test insulin sensitivity. The levels of biochemical indices includingserum TG, TC, HDL-C, LDL-C, FFA, inflammation indices including TNF-α, MCP-1and IL-6, and endothelial dysfunction indicators including NO, ET-1was determined.The ultrastructure of pathologic changes of MAEC in thoracic aorta was observed. Insitu apoptosis of endothelial cells in thoracic aorta were also detected by TUNELassay.2. In-vitro studies: MAEC were assigned into normal control(NC)group, palmitategroup(PA) and PA+FA group. Cell proliferation in each group were determined by methyl thiazolyl tetrazolium(MTT) arrays. ROS and the apoptotic cells labeled withAnnexin V-FITC/PI.were detected by flow cytometry(FCM). The protein expression ofCHOP and its intracellular localization was examined by immunofluoresence and. Theprotein expression of GRP78was evaluated by Western blot.Results:1. In vivo studies: After three months of HCD feeding, the weight of mice in HCDgroup was increased remarkably as compared with mice in SCD group. The results ofITT and GTT indicated that the insulin sensitivity of mice in HCD group wasdecreased significantly, as compared with SCD group, while FF improved insulinsensitivity obviously. The ultrastructure of MAEC in the thoracic aorta showedpathological changes including swollen mitochondria and an extended endoplasmicreticulum in HCD-fed mice, while these pathological changes were obviouslyameliorated in FF treatment group. The results of TUNEL indicated that HCD couldsignificantly induce apoptosis of MAEC in HCD-fed mice which could be obviouslyinverted by FF treatment.2. In vitro studies: Compared with the NC group, PA exhibited a proliferationinhibition effect on MAEC and the most appropriate concentration and time was0.5mmol/l for24h.50μmol/L FA(medium-concentration group) pretreatment increasedcellular proliferation in PA-treated group. PA significantly increased the intracellularlevels of ROS and FA pretreatment could significantly decrease the ROS levels. Thecell apoptosis were obviously increased in PA group compared with NC group.Compared with PA group, the cell apoptosis significantly decreased in FA medium-and high-concentration group. PA upregulated protein expression of CHOP whichmainly shifted into the nucleus after expression, which was significantly decreased byFA pretreatment. PA significantly induced protein expression of GRP78which wereobviously inverted by FA pretreatment. Conclusion:1. HCD diet for3months successfully induced the model of metabolic syndromepathological damage of mitochondria and endoplasmic reticulum in endothelial cells ofthoracic aorta, which probably suggested the existence of oxidative stress and ERstress, fenofibrate could significantly relieve the symptoms.2. PA could inhibit the cellular proliferation, induce apoptosis, oxidative stress and ERstress in MAEC. The beneficial effect of FA probably involve the mechanisms above. |
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