OBJECTIVETo explore the effect and mechanism of hirudin on atherosclerotic plaques in apolipoprotein E knockout (ApoE(-/-)) mice.

METHODSTotally 24 ApoE(-/-) mice, 7-8 weeks old were fed with high fat diets. They were randomly divided into the recombinant hirudin treatment group (drug group) and the model group according to body weight and different dens, 12 in each group. Twelve C57BL/6J mice, 7-8 weeks old fed with high fat diet were recruited as the normal control group. Recombinant hirudin (0.25 mg/kg) was intraperitoneally injected to mice in the drug group from the 10th week old once every other day for five successive weeks. Equal volume of normal saline was injected to mice in the model group. Mice in the normal control group received no treatment. All mice were sacrificed after fed with high fat diet until they were 20 weeks old. Serum levels of total cholesterol (TC), triglyceride (TG), low-density lipoprotein (LDL), high-density lipoprotein (HDL), high-sensitive C-reactive protein (hs-CRP), E-selectin, interleukin-6 (IL-6), and stromal metalloproteinase-2 (MMP-2) were detected. The plaque/lumen area and extracellular lipid composition/ plaque area were analyzed by HE staining and morphometry. Changes of signaling molecules in store-operated calcium channels, including stromal interacting molecule 1 (STIM1), Orail protein, and transient receptor potential channel 1 (TRPC1) were determined by Western blot. Results Lipid plaque formed in the aorta vessel wall of 20-week old mice in the model group. Compared with the normal control group, serum levels of TC, TG and LDL increased (P<0.01), hs-CRP, E-selction, IL-6, and MMP-2 obviously increased (P<0.01, P<0.05) in the model group; expression levels of STIM1, TRPC1, and Orail significantly increased (P<0.01). Compared with the model group, the plaque/lumen area and the extracellular lipid composition/plaque area significantly decreased in the drug group (P<0.05, P<0.01); serum levels of TC and LDL, hs-CRP, E-selction, IL-6, and MMP-2 obviously decreased (P<0.05, P<0.01); expression levels of STIM1, TRPC1, and Orail were significantly down-regulated (P<0.05, P<0.01).

CONCLUSIONHirudin could significantly improve lipids and endothelial functions of ApoE(-/-) mice, down-regulate expression levels of STIM1, Orai1, and TRPC1, and thus delaying the occurrence and development of atherosclerosis.