The Effect And Mechanism Of Quercetin On Atherosclerosis In ApoE^-/- Mouse

Objecivet: to investigate the effect and mechanism of anti-ASof quercetin Methods:1. to establish t`animal model of anti-AS of quercetin (1)dividing46normal-diet raised ApoE-/-mouse into five groups, each groupcontaining eight mouse of4to6-week-old. The five groups are: normal-dietgroup(3), control group(13), experimental group of low-dose quercetin(50mg/kg/d), median-dose quercetin (100mg/kg/d) and high-dose quercetin(50mg/kg/d),which have10mice in each group.(2) except the normal-dietgroup, all other groups are treated with high-fat diet for a period of12weeks.Then,3mice were killed in each group to investigate the AS by the method ofHE staining, transmissionelectronmicroscope and blood cholesterol.2. toinvestigate the expression of HMGB1and TLR4in gene and protein by themethod of immunohistochemical and RT-PCR.3. to investigate the expressionof HMGB1and TLR4protein in blood by ELISA. Results:1.after12weeks ofhigh-fat diet, the HE staining implies the thickness, plague formation andcholesterol crystal in intima of aorta and transmissionelectronmicroscopeexamination, aortic endothelial cells are swollen, the cell membrane is damagedand the structure of perinuclear space is expanded. The thickness of thetunicaelasticainterna and electron density are not uniform. The cholesterol inplasma increased significantly(P＜0.05).The animal model of AS is successfully established.2. after low-dose treatment of quercetin, HE stainingimplies the relief of thickness and cholesterol crystal deposit in intima of artery.Under transmissionelectronmicroscope examination, aortic endothelial cells arenot swollen, and the structure of perinuclear space is clear. The thickness of thetunicaelasticainterna and electron density are niform, but foreign bodies weredeposited on the surface of endothelium. The cholesterol in plasma did notreduce significantly (P>0.05).3. the immunohistochemical revealed that theexpression of HMGB1and TLR4is positive. With the dose of quercetinincreased, the expression of protein decreased. At8weeks, the expression ofHMGB1is not significantly different between low-dose group and medial-dosegroup, but significantly different between the low-dose group and high-dosegroup, medial-dose group and high-dose group.4. RT-PCR revealed theexpression of gene of HMGB1and TLR4decreased with the increased dose ofquercetin. At16weeks, significant difference exists in either both groups instudy (P <0.05).5. ELISA result revealed that the expression of HMGB1andTLR4is positive in control group. These proteins are decreased with theincreased dose of quercetin. At8weeks, the expression of HMGB1and TLR4is not significantly different between low-dose group and medial-dose group (P>0.05), but significantly different between the low-dose group and high-dosegroup, medial-dose group and high-dose group (P <0.05). All of the expressionof HMGB1and TLR4in different groups were showed in a time dependentmanner.(P <0.05). Conclusion: the quercetin has the effect of anti- arteriosclerosis (AS) and this effect is related to the dosage and time of use ofquercetin. The down-regulate of gene HMGB1and TLR4may be related to theanti-AS effect of quercetin.