卡托普利对高氧致新生大鼠慢性肺疾病的保护作用及机制探讨(英文)

Effects of Captopril on fibrosis in lung tissue of neonatal rats with CLD Induced by hyperoxia

目的观察高氧致CLD新生大鼠肺组织血管紧张素转换酶(ACE)、血管紧张素Ⅱ(AngⅡ)及Ⅰ型胶原含量的动态变化及卡托普利的保护机制。方法足月新生Wistar大鼠240只,随机分为模型组、空气对照组、卡托普利治疗组和盐水对照组,每组各60只。模型组、盐水对照组和卡托普利治疗组将足月新生Wistar大鼠(连同母鼠)生后即置于氧舱内持续吸入高浓度氧(FiO2:0.9),21d造成高氧肺损伤模型;空气对照组吸入空气;卡托普利治疗组于生后7d每天经胃管灌服卡托普利30mg/(kg·d),盐水对照组每天经胃管灌服等量生理盐水。每组分别于实验开始后的第1、3、7、14及21天随机选取6只麻醉后处死。采用酶联免疫吸附法(ELISA)测定肺组织的Ⅰ型胶原的含量,用日产7170全自动生化分析仪测定其ACE活性,用放免法测定其AngⅡ的含量。用逆转录聚合酶链反应(RT-PCR)检测肺组织ACE、AngⅡ、Ⅰ型胶原mRNA表达的动态变化并同时观察肺组织的形态学变化。结果模型组、盐水对照组及卡托普利治疗组的肺组织ACE、AngⅡ、Ⅰ型胶原的含量及mRNA的表达在实验后第1、3和7天与空气对照组比较差异无统计学意义(P>0.05);模型组、盐水对照组第14天明显升高,第21天达高峰(P<0.05或P<0.01);卡托普利治疗组肺组织AngⅡ、Ⅰ型胶原含量及mRNA表达第14天、第21天与模型组、盐水对照组比较明显降低(P<0.05或P<0.01),但仍高于空气对照组(P<0.05)。肺组织形态学改变:模型组、盐水对照组第1天同空气对照组,第3～7天肺泡壁毛细血管扩张,肺间隔水肿,肺间隔及肺泡腔内有中性粒细胞浸润,第14天部分肺泡腔变狭长,肺间隔增宽,肺间质细胞增多,出现肺组织纤维化改变。第21天正常肺泡结构消失,残留肺泡直径明显缩小,肺组织出现严重的纤维化。卡托普利治疗组肺组织纤维化病变明显减轻。结论高氧致CLD新生大鼠肺组织的ACE、AngⅡ、Ⅰ型胶原含量及mRNA表达在高氧后第14天、第21天明显增高,同时肺组织出现纤维化改变。而应用卡托普利干预后ACE、AngⅡ、Ⅰ型胶原含量及mRNA表达明显低于模型组及盐水对照组。肺组织形态学显示肺组织纤维化病变明显减轻,表明卡托普利对高氧肺损伤具有一定的保护作用。

[Objective] To observe the dynamic changes and the effects of rennin-angiotensin system and Captopril on interstitial fibrosis in lung of neonatal rats with CLD induced by hyperoxia. [Methods] 240 term neonatal Wistar rats were randomly assigned into air control, model, normal saline control and Captopril-treated groups （n=60 each）. The air control group was exposed to air （ FIO2=0.21 ）. The rest three groups were continuously exposed to hyperoxia （ FiO2=0.9 ）. During exposure the Captopril -treated group received Captopril （ 30 mg/kg·d ） by intragastric administration. The Normal saline control group was administrated with normal saline instead. The model group did not have treatment. At the Ist, 3rd, 7th, 14th day and 21st days of exposure, the subjects were sacrificed. The changes of Angiotesin Converting Enzyme（ACE）, Angiotensin Ⅱ （Ang Ⅱ ）, type Ⅰ collagen and mRNA expression were measured by enzyme-linked immunosorbentassay, radio-immunity technique and RT-PCR. The changes of lung histomorphology were observed. [Results] The ACE, Ang Ⅱ ,Type I Collagen levels and mRNA expression increased significantly in the model and normal saline control groups on the 14th and 21st days of exposure compared with those of the air control group （P 〈0.05, or P 〈0.01）. Captopril treatment reduced significantly the level and the expression of ACE, Ang Ⅱ ,Type I Collagen, and there was no significant difference on days 1st, 3rd, 7th in the model group and normal saline control group compared with those of the air control group（P 〉0.05）. But there were significant differences in the three results between the Captopril-treated and air control groups. The histopathological examination demonstrated different degrees of alveolitis, broaden interstitium and reduced alveolar quantity in the model group and normal saline control group compared with control group. [Conclusion] The changes of ACE, Ang Ⅱ, type I Collagen levels and mRNA expression were increased significantly on the 14th and 21st days in lung of neonatal rats with CLD induced by hyperoxia. The histopathological examination demonstrated different degrees of alveolitis, broaden interstitium and reduced alveolar quantity in the CLD induced by hyperoxia; Captopril may have protective effects on lung injury induced by hyperoxia.