Objective: To investigate the effect of Buyang Huanwu Tang(BYHWT) on the vulnerable plaques in atherosclerosis in ApoE-/- mice with high-fat diet. Method:The 8-week-old ApoE-/- mice were fed with high-fat diet for 12 weeks to reproduce the atherosclerosis(AS) vulnerable plaque model

and C57/BL-6J mice were used as normal control group and given normal drinking water. A total of four mice were randomly selected to make pathological sections of the brachiocephalic arteries and the aortic arch. The successful modeling was verified by calculating the plaque area and its vulnerability index. 72 ApoE-/- mice were randomly divided into the following groups:model group

low-dose BYHWT group:5 g·kg-1 BYHWT for 8 weeks

middle-dose BYHWT group:10 g·kg-1 BYHWT for 8 weeks

high-dose BYHWT group:20 g·kg-1 BYHWT for 8 weeks

autophagy inducer group:rapamycin 4 mg·kg-1 for 8 weeks

control group:continue to give normal diet drinking water. After 8 weeks

the mice were put to death

and the thoracic aorta was dissociated to the end of the abdominal aorta. Some prepared vascular tissue samples were used for the determination of the vulnerability index of the plaque.PCR analysis and Western blot were used to analyze the formation of autophagosomes. Result:ApoE-/- mice were fed with high-fat diet for 16 weeks to successfully induce the AS vulnerable plaque model. The model group showed obvious AS plaque formation. The index of plaque vulnerability was significantly higher than that in the normal group (P<0.01). Each dose of BYHWT significantly reduced the plaque area

and the index of vulnerability was decreased to some extent compared with that of model group (P<0.05). The levels of matrix metalloproteinase(MMP)-1

MMP-2 and MMP-3 mRNA in the model group were significantly higher than those in the blank group. The levels of MMP-1

MMP-2 and MMP-3 mRNA in different doses of BYHWT and rapamycin group were significantly lower than those in model group (P<0.05

P<0.01). The level of LC3-Ⅱ/LC3-Ⅰ in the model group was significantly lower than that in the blank group; compared with the model group

different doses of BYHWT and rapamycin group significantly increased LC3-Ⅱ/LC3-Ⅰ level(P<0.05). Conclusion:BYHWT can reduce the area of AS plaque

decrease the expression of matrix metalloproteinase in blood vessel

and regulate macrophage autophagy in plaque

thus reducing the vulnerability index of plaque and improving the stability of AS plaque.