Abstract:Aim To investigate the effect and potential mechanisms of tetramethylpyrazine (TMP) on atherosclerotic plaques. Methods 43 ApoE－/－ mice were used to establish the animal model of atherosclerosis (As) by high-fat diet for 8 weeks, 3 of which were used for model outcome verification, and another 40 model mice were randomly divided into model group, TMP low dose (25 mg/kg) group, TMP medium dose (50 mg/kg) group, TMP high dose (100 mg/kg) group and atorvastatin (AT, 2.6 mg/kg) group, with 8 mice in each group; another 8 C57BL/6J mice were set as control group. After gavaging administration for 8 weeks, the levels of total cholesterol (TC), triglyceride (TG), low density lipoprotein (LDL), high density lipoprotein (HDL) in the serum were detected by biochemical methods, and the As index was calculated. The levels of oxidized low density lipoprotein (ox-LDL), tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), monocyte chemoattractant protein-1 (MCP-1), intercellular adhesion molecule-1 (ICAM-1) in serum were detected by ELISA method. The pathological changes of aorta was evaluated by HE staining. The aortic plaque formation was evaluated by oil red O staining, and the plaque area percentage was calculated. The aortic fibrosis was evaluated by Masson staining, and the collagen area percentage was calculated. The expression of monocyte macrophage antibody-2 (MOMA-2) and α-smooth muscle actin (α-SMA) in the aorta was detected by immunohistochemistry (IHC) method, and the plaque vulnerability index was calculated. The mRNA and protein expression of peroxisome proliferator-activated receptor γ (PPARγ), nuclear factor-κB p65 (NF-κB p65) in aorta were detected by RT-qPCR or Western blot method. Results Compared with control group, the levels of TC, TG, LDL, ox-LDL, TNF-α, IL-1β, MCP-1, ICAM-1 in serum and As index of the mice were significantly increased in model group, while the level of HDL was significantly decreased (P＜0.05). The aorta showed pathological changes such as uneven thickening of the intima, accumulation of foam cells and fat cells, formation of a large number of plaques, lumen stenosis and infiltration of inflammatory cells; the percentage of aortic plaque area, percentage of collagen area, MOMA-2 and α-SMA positive area, plaque vulnerability index were all significantly increased (P＜0.05). The mRNA and protein expression of PPARγ in aorta were significantly decreased, and the mRNA and protein expression of NF-κB p65 were significantly increased (P＜0.05). Compared with model group, the levels of TC, TG, LDL, ox-LDL, TNF-α, IL-1β, MCP-1, ICAM-1 in serum and As index of the mice were significantly decreased in the TMP medium, high dose group and AT group, the level of HDL was significantly increased (P＜0.05). The pathological changes of aorta were significantly improved. The plaque area percentage, collagen area percentage, MOMA-2 positive area percentage and plaque vulnerability index were significantly decreased, and the α-SMA positive area percentage was significantly increased (P＜0.05). The mRNA and protein expression of PPARγ in aorta were significantly increased, the mRNA and protein expression of NF-κB p65 were significantly decreased (P＜0.05). Moreover, TMP exhibited a certain dose-dependent effect on various detection indicators (except MCP-1) in As mice. The regulatory effect of TMP high dose group on various detection indicators (except LDL and As index) in As mice was comparable or superior to those of AT group. Conclusion TMP can reduce the area of As plaque and improve the stability of vulnerable plaque in As mice, its mechanism may be related to regulating PPARγ/NF-κB signaling pathway, improving lipid metabolism and inhibiting inflammatory response.
