| Quercetin is one of the most common flavonols witch presents in many plants as food for human beings and herbal medicine.Quercetin can be used as effective medicine in order to prevent and/or treat many diseases,such as cardiovascular disease,osteoporosis,pulmonary disease,some cancers,aging,and so on.Atherosclerosis is a mainly basic pathologic change in many cardiac-cerebral vascular disease.It is a key pointof controllingthe occurrence and development ofatherosclerosis to treat the cardiac-cerebral vascular disease,which is of great significance to reduce the death risk of cardiac-cerebral vascular disease.In this research,animal atherosclerosis model was induced by intraperitoneal injection of vitamin D3(VD3)combined with high fat diet,to explore the therapeutic effect of quercetin given by mouth on the atherosclerosis in rats.The immunohistochemistry,western blotting and RT-PCR were applied to detect the major protein of PI3K/Akt/NF-κB pathway in theaortic walls of atherosclerosis rats,and preliminary discussed the mechanism of quercetin protection on atherosclerosisin vivo.The vascular smooth muscle cells(VSMCs)were cultured and an over-proliferation model was induced by oxidized low density lipoprotein(oxLDL).We used MTT,flow cytometry,western blotting and other experimental methods to observe the effect of quercetin on the VSMCs over-proliferation,and the effect on PI3K/Akt/NF-κB pathway in vitro.We found that the increasement of the body weight of atherosclerosis model in rats was slower obviously compared with the control group from 2 weeks to the end of the experiment in vivo(P<0.05).All the rats of atherosclerosis by 12 weeks treatment were divided into four group,they are the atherosclerosis model group,the quercetin high and the low dose treatment group,and the simvastatin treatment group.After treatment with quercetin low dose,quercetin high dose or simvastain,the body weight of rats in quercetin low dose group increased obviously compared with that of the atherosclerosis model group since quercetin low dose treatment of 3 weeks(P<0.05).At the end of the experiment,the serum,the liver,the kidney,the heart and the aortawere collected.We found that the liver index in atherosclerosis model group was increased compared with the control group(P<0.05).We also examined the triglycerol(TG),total cholesterol(TC),low density lipid(LDL),and high density lipid(HDL)in serum in all groups.The results showed that the TG,TC,and LDL levels were significantly increased and HDL levels were decreased significantly in the atherosclerosis model group than those in the control group(P<0.05).In the rats aorta of the atherosclerosis model group,intimal protrusion,the middle layer smooth muscle cells proliferation,disordered arrangement;and even typical pathological changes of atherosclerosis,such as severe calcification,inflammatory cells infiltration,smooth muscle cell proliferation,foam cells,and so on can be seen.In the low and high dose quercetin groups and simvastatin group,all the pathological changes above mentioned is more alleviative than atherosclerosis model group.Besides this,the serum TG,TC,and LDL levels of quercetin groups and simvastatin group were obviously decreased compared to the atherosclerosis model group(P<0.05).The serum HDL levels in the low dose and high dose quercetin group were significantly increased compared to the atherosclerosis model group(P<0.05).We can get the conclusion that quercetin not only modified the lipid metabolism disorders caused by atherosclerosis,but also delayed the pathological changes of atherosclerosis.The immunohistochemistry staining of the rat thoracic aorta showed that the collagen I(Col I),alpha-smooth muscle actin(α-SMA)and vimentin expression significantly increased in the atherosclerosis model group than that of the control group(P<0.05).Compared with the atherosclerotic model group,the expression of Col I,α-SMA and vimentin in the quercetin low and high dose treatment group were significantly decreased(P<0.05).These results suggested that quercetin can significantly inhibit VSMCS and fibroblast proliferation,inhibit the collagen increasing,and delay atherosclerosis progression.Cell proliferation of the human VSMCs in vitro was examined with MTT method.The results showed that the proliferation increased significantly after induced 24 h and 48 h by ox-LDL than control group(P<0.05),however,the proliferation in the quercetin treatment group was decreased comparing with that of the ox-LDL treated group(P<0.05).These results suggested that quercetin can inhibit the VSMCs proliferation,which is the most important effect cell of atherosclerosis.The immunohistochemistry,western blotting and the fluorescence quantitativeRT-PCR technique were applied to detect the PI3 K,Akt and NF-κb expression in atherosclerosis of aorta in vivo and VSMCs culture in vitro.The results showed that the PI3 K and Akt m RNA expression was increased significantly in the atherosclerosis model group than control group(P<0.05),and was decreased obviously in quercetin low and high dose group compared with that in the atherosclerosis model group(P<0.05)in vivo and in vitro.The p-PI3 K and p-Akt protein expression by western blotting in the atherosclerosis model group were increased obviously than control group(P<0.05),however,the quercetin low and high dose group decreased obviously than the atherosclerosis model group(P<0.05).The immunohistochemistry staining showed that NF-κb protein expression increased in the atherosclerosis model group than that in the control group(P<0.05),and the expression of NF-κb protein decreased significantly in quercetin treatment group than the atherosclerosis model group(P<0.05).Furthermore,we examined the nuclear and plasm expression of NF-κb in VSMCS culture in vitro.The results showed that the expression ratio of NF-κb in the ox-LDL treated group was higher signifantly than control group(P<0.05).However,the expression ratio of NF-κb in the quercetin treatment group was decreased significantly than the ox-LDL treated group(P<0.05).All these results showed that the PI3K/Akt/NF-κb pathway may be activated in athreosclersis.The quercetin prevention from the atherosclerosis may be through interventing the key proteins of PI3K/Akt/NF-κb pathway and inhibiting the NF-κb transferring.The main conclusions of this study are as follows:(1)Quercetin can decrease the serum levels of TG and TC in atherosclerosis rats,and can increase the relative concentration of HDL by changing the ratio of LDL/HDL,which achieve the effect of anti atherosclerosis.(2)Quercetin can inhibit fibroblast and VSMCs proliferation,inhibit the collagen synthesis of the rat arterial wall,and play an important role in maintaining the elasticity of the arterial wall.(3)The activation of PI3K/Akt/NF-κb pathway may be involved in atherosclerosis.The quercetin prevention from the atherosclerosis may be through interventing the key proteins of PI3K/Akt/NF-κb pathway and inhibiting the NF-κb transferring.The characteristic of this study is that quercetin has a certain effect of anti atherosclerosis,and the definite target may be related to the PI3K/Akt/NF-κb pathway. |
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