| Objective and background of experiment :As one of common full body diseases, atherosclerosis has already threatened human's health seriously. There is a hot spot of today medicine research to prevent and treat the formation and development of atherosclerosis. The stability of atherosclerotic plaque depends on the character of plaque but not the size. The rupture of coronary atherosclerotic vulnerable plaque can touch off the thrombus formation and result in acute coronary syndrome. The effective stabilization of unstable plaque can prevent and reduce the formation of acute coronary syndrome. Although many factors can result in the unstabilization of plaque,animal experiment and clinic test has already proven the fact that the heighten of matrix metalloproteinases'level plays a more important role.Some researches find matrix metalloproteinases (MMPs) participate in all process of the reconstruction to atherosclerosis. MMPs which belong to the Zn2 +dependent protease family, are now known to have 23 family members, specific degradation of extracellular matrix, plaque rupture often occurre in the fibrous cap shoulder, its fibrous cap is the thinnest, collagen content and glucan less fibrous cap bear the large tension, anti-poor rupture, which is one of the important factors of MMPs expression and activation. Matrix metalloproteinases mainly come from the foam cells in plaque, and by inflammatory cytokines that increase the expression of pressure, secretion and activation.The matrix metalloproteinases - 2,9 (MMP– 2,9) with the extracellular matrix degradate strongly.Ⅳof the basement membrane and collagen fibers atherosclerotic plaque are the important component of the cap, MMP - 2,9 promote degradation of smooth muscle cells in the membrane which migration to the endometrium, and accelerate the process of atherosclerosis.Low density lipoprotein (ox-LDL) which is an important factor relate to atherosclerosis has a series of functions lead to atherosclerosis.It can induce macrophage cells into foam cells, impair endothelial cells,promote monocyte to attach to the endothelia. Ox-LDL also can enhance the activity of MMPs to promote the thrombus formation.C-reactive protein(CRP) is a sensitive sign of atherosclerotic inflammatory reactive.It can promote atherosclerotic inflammatory reactive by many ways and the hoist of CRP has close connection with atherosclerotic inflammation.There is a study discover that CRP can inhibit the activatory macrophage cells to secrete MMPs and the inducement of ox-LDL to MMPs.To inhibit the activation of MMPs , promote the stability of atherosclerotic plaque and prevent the rupture of atherosclerotic plaque which has already formed in coronary artery,is a important measure decreasing acute coronary syndrome. At present, there are a lot of the synthetic inhibitors of MMPs.They can suppress the role of MMPs, but the drug side effects are obvious,and disassemble soon in vivo . So they can not be used in clinical coronary heart disease patients.So far, not one safe and effectiveTIMPs has been found which can be used in ACS patients.Astragalus membranaceus is one of Chinese traditional medicine ,with small side effect , cheap price, and upstanding applications.Recently,there is little report about the inhibition of astragalus membranaceus of atherosclerosis. We start the research by application of astragalus membranaceus to probe into the inhibitory of the expression of matrix metalloproteinase-2,9 , oxidated low density lipoprotein, C-reactive protein ,thromboxanes B2 in rabbit atherosclerotic model .So as to reveal the effect of stabilize the atherosclerosis plaque.Methods:First step was to establish rabbit atherosclerotic model.12 male or female New Zealand rabbits were randomized into two groups .And they were injected into bovine serum albumin with otic vein. The two groups were all fed with high fat diet containing 1% cholesterol +8% bovine grease +7.5% yolk powder+83.5% common feedstuff+ursodeoxycholic acid(2mg/kg/d)+ propylthiouracil(4mg/kg/d). At the same time the astragalus membranaceus group took astragalus membranaceus in water orally(0.4g/kg/d).At the 12th weekend,all rabbits were killed then serum was separated and aortic organizations was cut.Then next step was to detect the consistence of fat in serum and MMP-2,9 ,ox-LDL ,CRP,TXB2 level of optical density(OD) in serum were detected by Enzyme-linked Immunosorbent Assays(ELISA) method.It could confer the consistence in serum of protein by the proportion. Plaque samples in HE staining,and pathological changes were observed, MMP-2 and MMP-9 expression in plaques were detected by immunohistochemical methods, using computer software measurement immunoprecipitation of integral optical density value in order to give the degree of staining quantitative analysis.Result:The astragalus membranaceus group serum MMP-2,9 ,ox-LDL ,CRP,TXB2 consistence comparing with the high fat group was not significantly lower ,and the results had no statistic meaing.Comparing with the astragalus membranaceus group, lumen of the high fat group's general sample was roughness and was seen the uplift of the big piece of white-shaped plaque.HE staining results showed that: artery lumen of the high-fat group was thinker and atherosclerosis plaque containing a larger number of foam cells than that of astragalus membranaceus group. Immunohistochemical staining results showed that:the anti-MMP-2 ,9 antibodies brown granules in atherosclerosis plaques in astragalus membranaceus group were less than that of high-fat group.Immunoprecipitation of gray value of plaques MMP-2(1189.560±609.953) in astragalus membranaceus group were lower than that of high-fat group(708.569±486.176), and the results had statistic meaing. Immunoprecipitation of gray value of plaques MMP-9(1392.355±657.912) in astragalus membranaceus group were lower than that of high-fat group(946.069±359.151), and the results had no statistic meaing.Conclusions:1. Astragalus membranaceus can lower the expressions of plaques MMP-2,9 in atherosclerotic rabbits,and stabilize the aortic atherosclerosis plaque in rabbits.2. Astragalus membranaceus has little obvious effect on the expressions of the consistence of fat and MMP-2,9 ,ox-LDL ,CRP,TXB2 level in serum of atherosclerotic rabbits and the formation of atherosclerosis.3.Astragalus membranaceus can inhibit the expressions of MMPs of aortic atherosclerotic plaque tissues,and it will be expected to be used in clinical practice as a inhibitor of matrix metalloproteinase.Innovation:The experiment can discover new pharmacological mechanism of astragalus membranaceus,and apply to prevent or treat coronary atherosclerotic heart disease.Applied value:There is an advantage with small side effect and cheap price of astragalus membranaceus which one of traditional medicine.If it can be used in clinical practice abroad as a inhibitor of matrix metalloproteinase to make atherosclerotic plaque stable and to prevent or treat cardiovascular and cerebrovascular disease,it can produce enormous economic and social benefit.
|
PDF Full Text Request