目的 探讨吸入高浓度氧对大鼠肺组织β-防御素-2 mRNA(BD-2 mRNA)表达的影响.方法 出生21 d的雄性SD大鼠40只,体重50～60 g,随机分为5组(n=8):对照组(C组)吸入空气72 h;高浓度氧气组(H1组～H4组)分别吸入92%～94%氧气12、24、48和72 h.于吸入空气或氧气结束时取大鼠肺组织,计算湿/干重(W/D)比,观察肺组织病理学结果,行病理学评分;采用荧光定量PCR法和Western b1ot法分别检测肺组织BD-2 mRNA及总NF-κB p65和细胞核NF-κB p65的表达水平,计算NF-κB的活化水平.结果 与C组比较,H3组和H4组肺组织W/D比升高,H1组～H4组病理学评分升高,肺组织BD-2 mRNA表达下调,NF-κB活化水平升高(P＜0.05);H1组～H4组肺组织W/D比、病理学评分逐渐升高,BD-2 mRNA表达逐渐下调,H1组～H3组肺组织NF-κB活化水平逐渐升高,H4组肺组织NF-κB活化水平低于H3组(P＜0.05).结论 吸入高浓度氧可通过下调大鼠肺组织BD-2 mRNA的表达,导致肺损伤,该作用可能与NF-κB信号转导通路无关.
Objective To investigate the effects of hyperoxia on the expression of β-defensin-2 mRNA in the lungs in rats. Methods Forty 21-day old male SD rats weighing 50-60 g were randomly divided into 5 groups ( n = 8 each): control group breathing room air (group C) and 4 hyperoxia groups breathing high concentration of oxygen (92%-94% O2 ) for 12, 24, 48 and 72 h respectively (group H1-4 ). The animals were sarificed at the end of O2 breathing. The lungs were removed for microscopic examination and determination of wet/dry lung weight ratio and expression of β-defensin-2 mRNA (by RT-PCR), total NF-κB p65 protein and NF-κB p65 protein in cell nucleus (by Western blot analysis). The level of activation of NF-κB was calculated. Results The W/D lung weight ratio was significantly higher in group H3 and H4than in group C. The lung injury scores were significantly increased and β-defensin-2 mRNA expression was significantly down-regulated in group H1-4 as compared with groups in a duration of hyperoxia dependent manner. The level of activation of NF-κB was up-regulated in group H1-4 compared with group C and peaked at 48 h of hyperoxia (group H3 ). Conclusion Inhalation of high concentration of O2 can induce lung injury by down-regulating lung β-defensin 2 mRNA expression. NF-κB signal transductinn pathway may not be involved in the underlying mechanism.