尼古丁-血管紧张素Ⅱ诱导腹主动脉瘤模型小鼠血管弹力蛋白及肥大细胞的变化

The Variation of Elastic Protein Degradation and Mast Cell Degranulation in Abdominal Aortic Aneurysms Induced by Nicotine plus Angiotensin Ⅱ

目的:探讨尼古丁-血管紧张素Ⅱ诱导腹主动脉瘤模型小鼠腹主动脉壁弹力蛋白及肥大细胞的变化。方法:将40只10~12个月龄的雄性C57BL/6J小鼠随机分为对照组、尼古丁组、AngⅡ组和尼古丁联合AngⅡ组,分别予皮下泵注生理盐水、尼古丁、AngⅡ和尼古丁联合AngⅡ,持续28 d后处死小鼠,左心室穿刺取血,同时取腹主动脉组织;采用Verhoeff-Van Gieson(VVG)染色,显微镜下观察腹主动脉壁中膜弹力蛋白完整性,甲苯胺蓝染色法检测腹主动脉壁各层组织中肥大细胞数量及释放的颗粒,同时计数肥大细胞,ELISA法检测血清类胰蛋白酶浓度。结果:尼古丁联合AngⅡ模型组5只小鼠有腹主动脉瘤形成(50%成瘤),其余3组小鼠无动脉瘤形成;尼古丁、AngⅡ和尼古丁联合AngⅡ组小鼠的腹主动脉均有不同程度弹力蛋白破坏;与对照组相比,其余3组小鼠腹主动脉外膜浸润的肥大细胞明显增多(P<0.01),并发生脱颗粒,各组均未见中膜和内膜肥大细胞浸润;与对照组比较,尼古丁、AngⅡ和尼古丁联合AngⅡ组小鼠血清类胰蛋白酶浓度明显增加(P<0.01)。结论:尼古丁联合AngⅡ能诱导小鼠腹主动脉中弹力蛋白降解、肥大细胞浸润并脱颗粒,可能参与诱导腹主动脉瘤的形成。

Objective： To investigate the roles of the elastic protein degradation and mast cell degranulation in abdominal aortic aneurysms induced by nicotine plus angiotensin（ Ang） Ⅱ. Methods： 40 male C57 BL/6 J mice（ 10-12 months old） were randomly divided into four groups including contrastive,nicotine,Ang Ⅱ and co-treatment（ nicotine plus angiotensin Ⅱ） group,after subcutaneous injection with saline,nicotine,Ang Ⅱ and nicotine plus Ang Ⅱ respectively for 28 days,they were killed. Their ventriculus sinisters were punctured to get blood meanwhile abdominal aortic. Verhoeff-Van Gieson（ VVG） staining was used to observe the elastic protein in media. Toluidine blue staining was done to detect the recruited mast cells in aortic tissue. ELISA was done to test the serum level of tryptase in the mice. Results： 5 mice had the abdominal aortic aneurysms（ 50% with tumour） in the group of nicotine plus Ang Ⅱ while others had not. Three experiment groups（ nicotine,Ang Ⅱ and nicotine plus angiotensin Ⅱ group） showed the degradation of elastic protein in adventitia with a gap connecting to hematoma under adventitia because of the rupture of elastic fibers. Compared with the contrastive group,either nicotine or Angll,and the combination of both stimulated the recruitment and degranulation of mast cells into the adventitia of aortic tissue with a strong stimulation in the combination group（ P〈0. 01）. Additionally,either nicotine or Angll,and the combination of both stimulated the releasement of tryptase with a strong releasement in nicotine plus Ang Ⅱ group（ P〈0. 01）. Conclusions： The degradation of elastic protein and degranulation of mast cells might be involved in abdominal aortic aneurysms induced by nicotine plus Ang Ⅱ.