ABSTRACT
<p><b>OBJECTIVE</b>To explore the effects of astragali radix extract on the expressions of matrix metalloproteinase 9 (MMP-9) and the formation of atherosclerotic plaque in aortic atherosclerotic plaques of apolipoprotein E-deficient mice (ApoE-/-).</p><p><b>METHODS</b>Male 8-week-old ApoE-/- mice fed with high fat diet were randomly divided into four groups (n=12 each): control group (saline 0.2 ml/d), atorvastatin group (atorvastatin 10 mg×kg(-1)×d(-1)), low-dose astragali radix extract group (1.25 g×kg(-1)×d(-1)) and high-dose astragali radix extract group (5 g×kg(-1)×d(-1)). After 12 weeks, serum oxLDL was measured by the method of ELISA. The formation of atherosclerotic plaque was determined in HE and oil red O stained aortic slice. The expressions of macrophage and MMP-9 in the aortic plaque were detected by immune fluorescence and immunohistochemistry staining method.</p><p><b>RESULTS</b>Similarly as atorvastatin, astragali radix extract significantly decreased the level of serum oxLDL in ApoE-/-1 mice in a dose-dependent manner. The level of oxLDL in the high-dose astragali radix extract group [(5.2±6.1) µg/ml] was significantly lower than that in the control group [(15.8±5.4) µg/ml, P<0.01]. The area of atherosclerosis plaques was smaller (17.24%±4.22% vs. 49.87%±9.37%, P<0.01) and the penetration degree of plaques in the arterial wall was relieved in the high-dose astragali radix extract group compared to those in the control group (P<0.01). The expressions of Mac3 in atherosclerosis plaques of the high-dose astragali radix extract group was also significantly lower than in the control group (P<0.01). The mean absorbance value of the expression of MMP-9 in the high-dose astragali radix extract group (0.0154±0.0014)was significantly lower than that in the control group (0.0263±0.0065) (P<0.01).</p><p><b>CONCLUSIONS</b>Similar as atorvastatin, astragali radix extract can dose-dependently inhibit the expression of MMP-9 and the formation of the atherosclerotic plaque in ApoE-/- mouse, probably by reducing the serum oxLDL, inhibiting macrophage infiltration, migration and secretion of MMP-9.</p>