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目的动态观察高氧暴露新生早产大鼠肺组织肺泡上皮细胞(AEC)超微结构与细胞外基质(ECM)的变化,探讨其在高氧性肺损伤肺纤维化发病机制中的作用。方法将80只新生早产SD大鼠随机分为空气组和高氧组,空气组在空气中饲养,高氧组置于高氧箱(保持氧体积分数(950ml/L)中饲养,每组40只;每组又随机分为3、7、14、21d 4个亚组,每组10只。分别在第3、7、14、21天处死动物,收集肺组织标本。采用透射电镜观察各亚组大鼠AEC超微结构改变;采用碱水解法测定其肺组织匀浆羟脯氨酸(HYP)含量;采用免疫组织化学方法检测肺组织Ⅰ型与Ⅲ型胶原表达与分布;并用图像分析方法检测肺组织Ⅰ、Ⅲ型胶原阳性表达的PU值。结果高氧组第3天即出现AEC轻度损伤;第7天时AEC损伤加重,第14、21天时出现AEC-Ⅱ坏死,板层小体基本排空,AEC基底膜及气血屏障明显增厚,肺间质可见大量胶原原纤维。肺组织HYP含量随着高氧暴露时间的延长而逐渐增加,第21天时达最高,在第7、14、21天时均明显高于空气组。Ⅰ、Ⅲ型胶原均在第3天呈弱阳性表达,第14、21天呈强阳性表达。肺组织Ⅰ、Ⅲ型胶原阳性表达的PU值在第14、21天时明显高于空气组(P<0.01)。结论AEC损伤是早产大鼠长时间高氧暴露所致肺损伤的早期特征,而后期以肺间质ECM过度沉积为主。
Objective To observe the changes of ultrastructure and extracellular matrix (ECM) of alveolar epithelial cells (AEC) in lungs of neonatal rats with hyperoxia exposure and to explore their roles in the pathogenesis of pulmonary fibrosis induced by hyperoxia. Methods Eighty neonatal preterm SD rats were randomly divided into air group and hyperoxia group. The air group was housed in air. The hyperoxia group was housed in high oxygen chamber (keeping the volume of oxygen (950ml / L), 40 Only; each group were randomly divided into 4 subgroups of 3, 7, 14, 21d, each group of 10. Animals were sacrificed on the 3rd, 7th, 14th, and 21st days respectively, and lung tissue samples were collected.Transmission electron microscopy The ultrastructural changes of AEC in rats were observed. Hydroxyproline (HYP) content in lung tissue homogenate was determined by alkaline hydrolysis. The expression and distribution of type I and type III collagen in lung tissue were detected by immunohistochemistry. The PU of positive expression of type I and type III collagen in lung tissue was detected.Results AEC mild injury occurred in the third day of hyperoxia group, AEC injury increased on the 7th day, necrosis of AEC-II appeared on the 14th and 21st day, Basic emptying, AEC basement membrane and the blood-air barrier were significantly thicker, a large number of pulmonary interstitial collagen fibers can be seen.Hypoxia lung tissue HYP content gradually increased with the extension of exposure time, reaching the highest on the 21st, at the seventh, 14 and 21 days were significantly higher than air group Ⅰ and Ⅲ collagen were weakly positive expression on the 3rd day, 14th (P <0.01) .Conclusion AEC injury is caused by prolonged hyperoxia exposure in preterm rats. The PU value of positive expression of type I and type III collagen in lung tissue was significantly higher than that in air group on day 14 and 21 (P <0.01) The early features of lung injury, and later to interstitial ECM over-deposition-based.