迷走神经对血管紧张素Ⅱ介导的小鼠高血压心脏纤维化进程的抑制作用研究

Vagus nerve inhibits angiotensin Ⅱ-mediated cardiac fibrosis in hypertensive mice

目的观察迷走神经对血管紧张素Ⅱ(AngⅡ)介导的小鼠高血压心脏纤维化进程的抑制作用。方法选择雄性12周龄C57BL/6J小鼠36只,按照随机数字表法分为4组:假手术+0.9%氯化钠溶液灌注组(A组)、左侧迷走神经切除+0.9%氯化钠溶液灌注组(B组)、假手术+AngⅡ灌注组(C组)、左侧迷走神经切除+AngⅡ灌注组(D组)。采用Masson法观察4组小鼠心脏间质中胶原的沉积,采用苏木精-伊红和麦胚凝集素染色法检测心肌细胞肥厚面积,采用实时荧光定量聚合酶链反应法检测心脏组织中肿瘤坏死因子α、白细胞介素1β、白细胞介素6的表达。结果与A组和B组比较,C组和D组术后1～7 d收缩压均显著升高(均P<0.05)。D组小鼠心脏纤维化面积大于C组[(6.40±0.53)%比(4.30±0.25)%],小鼠心脏组织α-平滑肌肌动蛋白mRNA、转化生长因子βmRNA表达均高于C组[(0.59+0.06)%比(0.38+0.03)%,(0.029 0±0.003 5)%比(0.018 0±0.002 2)%],小鼠心肌细胞面积和β心肌肌球蛋白重链7阳性表达大于/高于C组[(318±14)μm比(226±31)μm,(0.081±0.002)%比(0.052±0.004)%],差异均有统计学意义(均P<0.05)。实时荧光定量聚合酶链反应检测结果显示,D组小鼠心脏组织中白细胞介素6、白细胞介素1β、肿瘤坏死因子α的mRNA表达均显著高于C组[(2.80±0.33)比(1.01±0.05),(2.10±0.41)比(1.03±0.06),(3.70±0.51)比(1.00±0.07)];免疫组织化学和流式细胞检测显示,D组小鼠心脏组织中CD_(45)^+白细胞浸润显著高于C组[(6.30±0.46)比(3.80±0.17)],差异均有统计学意义(均P<0.05)。结论单侧迷走神经切除促进AngⅡ介导的高血压心脏中胶原沉积、心肌肥厚和炎症因子的增加,CD_(45)^+白细胞浸润增加,迷走神经可抑制AngⅡ介导的高血压心脏纤维化进程。

Objective To observe the inhibitory effect of vagus nerve on cardiac fibrosis mediated by angiotensin Ⅱ（AngⅡ） in hypertensive mice. Methods Thirty-six male, 12 weeks old C57BL/6 mice were randomly divided into 4 groups： sham operation＋0.9% sodium chloride solution infusion（group A）, left vagotomy＋0.9% sodium chloride solution infusion（group B）, sham operation＋AngⅡ infusion（group C）, left vagotomy＋AngⅡ infusion（group D）. Collagen deposition in cardiac mesenchyma was observed by Masson staining. Cardiomyocyte hypertrophy was observed by hematoxylin-eosin staining and wheat germ agglutinin staining. Expressions of tumor necrosis factor-α, interleukin-1β and interleukin-6 in heart tissue were tested by real-time fluorescence quantitative polymerase chain reaction（PCR）. Results Systolic pressures of mice during 1-7 d after operation in group C and D were significantly higher than those in group A and B（P＜0.05）. Cardiac fibrosis area in group D was significantly larger than that in group C［（6.40±0.53）% vs （4.30±0.25）%］; expressions of α-smooth muscle actin mRNA and transforming growth factor-β mRNA in heart tissue of mice in group D were significantly higher than those in group C［（0.59＋0.06）% vs （0.38＋0.03）%， （0.029 0±0.003 5）% vs （0.018 0±0.002 2）%］; cardiomyocyte area and expression of β-cardiac myosin heavy chain-7 in group D were significantly larger/higher than those in group C［（318±14）μm vs （226±31）μm， （0.081±0.002）% vs （0.052±0.004）%］（all P＜0.05）. PCR showed that expressions of interleukin-6, interleukin-1β and tumor necrosis factor-α mRNA in heart tissue of mice in group D were significantly higher than those in group C［（2.80±0.33） vs （1.01±0.05）, （2.10±0.41） vs （1.03±0.06）, （3.70±0.51） vs （1.00±0.07）］（P＜0.05）. Immunohistochemistry and flow cytometry showed that CD＋45 leukocyte infiltration in group D was significantly higher than that in group C［（6.30±0.46） vs （3.80±0.17）］（P＜0.05）. Conclusions Unilateral vagotomy promotes AngⅡ-mediated cardiac collagen deposition, myocardial hypertrophy, inflammatory response and CD＋45 leukocyte infiltration in hypertensive mice. Vagus nerve can inhibit the progress of angiotensin Ⅱ-mediated hypertensive cardiac fibrosis.