坎地沙坦预防家兔动脉粥样硬化斑块破裂的研究

Prevention of rupture of atherosclerotic plaque by Candesartan in rabbit model

目的检测坎地沙坦是否具有稳定动脉粥样硬化斑块、预防斑块破裂的作用，并探讨其机制。方法34只新西兰雄性大白兔，随机分为正常组、模型组、坎地沙坦干预组。正常组普通饲料喂养，后两组高胆固醇（1％胆固醇）喂养，一周后行腹主动脉内膜剥脱术，坎地沙坦组于腹主动脉内膜剥脱术前2d给予坎地沙坦（0．5mg·k^-1·d^-1）干预。12周末对模型组和干预组行药物诱发不稳定粥样斑块破裂，取腹主动脉行病理形态学观察和基质金属蛋白酶9（MMP-9）、巨噬细胞、胶原的免疫组织化学分析，Westernblot法测定主动脉斑块内MMP-9蛋白表达。结果模型组9个主动脉血管标本中有7个标本共12处发生斑块破裂及血栓形成，干预组lO个标本中有2个标本3处发生斑块破裂，两组斑块破裂数量差异有统计学意义（P〈0．05），正常组中未见斑块破裂及血栓形成；干预组斑块内MMP-9面积比较模型组显著降低（12．35％±4．28％比32．58％±9．16％，P〈0．05）；干预组斑块内巨噬细胞面积比较模型组显著降低（13．87％±4．91％比23．8％±7．45％，P〈0．05）；干预组斑块内胶原面积比较模型组显著增加（30．27％±11．36％比4．18％±1．28％，P〈0．01）；干预组斑块中MMP-9蛋白表达水平较模型组明显降低（P〈0．01）。结论坎地沙坦具有稳定斑块、预防斑块破裂的作用，其机制可能是坎地沙坦降低粥样斑块内MMP-9的表达、减少斑块内巨噬细胞聚集和增加斑块内胶原含量。

Objective To evaluate Candesartan therapeutic effect against atherosclerotic plaque rupture and to explore the related mechanisms. Methods Thirty-four New Zealand White male rabbits were randomly divided into three groups： the control group, the model control group and the Candesartan intervention group. The control group rabbits were fed with a normal diet. Rabbits of the latter two groups were fed with a 1% high-cholesterol diet and received a balloon catheter injury respectively one week after the cholesterol feeding. Candesartan （0. 5 mg·k^-1·d^-1） was given to the Candesartan group rabbits 2 days before the performance of the balloon catheter injury. By the end of 12^th week of the experiment, Russell＇s viper venom was used for rabbits of both the model control and the Candesartan groups in order to induce rupture of the plaques developed and followed by sacrifice of all the rabbits of the 3 groups. The aortas were removed and fixed for histological evaluation. Immunohistochemistry of MMP-9, macrophage markers and collagen were performed. The protein expression of MMP-9 was determined using Western blot analysis. Results In the model control group, 7 of 9 rabbits with a total of 12 plaques developed rupture and thrombosis of the plaques after the induction. In contrast, only 2 of 10 rabbits with a total of 3 plaques demonstrated rupture and thrombosis in the Candesartan group （ P 〈 0. 05 ）. The control group rabbits did not have plaque rupture and thrombosis. Compared with the model group, both the percentage area of MMP- 9 and macrophages in the plaques were significantly decreased in the Candesartan group （12. 35% ± 4. 28% vs32.58% ±9.16%, P〈0.05; 13.87% ±4.91% vs 23.8% ±7.45%, P 〈0.05）. There was an increased percentage of collagen content in total plaques of the Candesartan group （30. 27% ± 11.36% vs 4. 18%±1.28%, P 〈 0. 01 ）. Compared with the model group, the protein expression of MMP-9 was significantly decreased in the Candesartan group （ P 〈 0. 01 ）. Conclusion Candesartan has a preventive value against atherosclerotic plaque rupture in hypercholesterolemic rabbits, likely through its reduction of MMP-9 expression, inhibition of macrophage accumulation and increase of collagen content within the plaques.