Objective: To investigate whether the water extractives of regulating qi and blood prescription (WQBP) had effects on early atherosclerosis of apolipoprotein E-deficient mice (ApoE^- mice) at the age of 19 weeks or not, and to explore the possible mechanisms. 

Methods: Forty ApoE^- mice, six weeks of age, were given high-fat diet and randomly divided into four groups: high-dose WQBP-treated group (360 mg/kg), low-dose WQBP-treated group (72 mg/kg), simvastatin-treated group (25 mg/kg) and untreated group, with ten mice in each group. Meanwhile, ten C57BL/6 mice of same genetic background were allocated to normal control group. Mice in the high- and low-dose WQBP-treated groups and simvastatin-treated group were administered with corresponding drugs from the 15 to 19 weeks. Mice in the untreated and normal control groups were administered with isovolumic water. Sacrificed at 19 weeks, the level of blood-lipid, the plaque construction, plaque integral, and the contents of plaque macrophages and vessel smooth muscle cells of the mice were analyzed by immunohistochemical method and a computer picture processing system.

Results: Compared to the untreated group, high-dose WQBP group could obviously decrease the level of low-density lipoprotein cholesterol (LDL-C). Simvastatin group could decrease the levels of LDL-C and total cholesterol (TC) (P＜0.01). In high-dose WQBP-treated group and simvastatin-treated group, the thickness of fiber cap and the quantities of vessel smooth muscle cells increased (P＜0.05), the quantities of plaque macrophages and the ratio of lipid and plaque reduced (P＜0.01). 

Conclusion: WQBP and simvastatin can interfere in early atherosclerosis of ApoE^- mice, attenuate and stabilize plaque in some extent. The mechanisms may include adjusting blood lipid, decreasing macrophage number and increasing the quantities of vessel smooth muscle cells.

Key words: knockout mice, arteriosclerosis, low density lipoprotein-cholesterol, total cholesterol