高氧对新生大鼠肺血管发育及肺组织血管生成素1表达的影响

目的 观察持续吸入85％氧气对新生大鼠肺血管发育和肺组织血管生成素1(Ang-1)表达的影响,探讨高氧肺损伤新生大鼠的肺血管发育情况及可能的发生机制.方法 将96只新生SD大鼠在生后6h内,随机分为高氧组和空气组,高氧组将大鼠置于自制密闭氧箱,FiO2=0.85.在实验3、7、14d每组各随机取16只处死,采集标本.采用HE染色进行肺组织形态学分析,放射状肺泡计数评价肺泡化程度,肺动脉钡剂造影及肺动脉密度检测评价肺血管的发育,免疫组织化学法检测肺组织Ang-1的表达,荧光定量PCR和Western blot技术检测肺组织Ang-1的mRNA和蛋白表达水平.结果 (1)新生大鼠高氧暴露14 d,肺组织的病理表现与早产儿支气管肺发育不良(BPD)的病理表现相似.(2)高氧组7 d RAC值显著低于空气组(10.55±0.13):(11.74 ±0.19),P＜0.05],在14d时差异更显著(12.47±0.05):( 15.03±0.16),P＜0.01].(3)肺动脉钡剂造影显示,高氧组14 d大鼠肺动脉主干变细,肺小动脉显影减少,肺动脉密度显著低于空气组(3.55±0.09):(6.03±0.16),P＜0.05].(4)免疫组化染色显示,高氧组7d和14 d,肺组织Ang-1的表达均显著低于同时间点空气组 (4.27±0.34):(3.10 ±0.29),P＜0.05,(5.65±0.49)∶(3.21±0.28),P＜0.01].(5)荧光定量PCR及Western blot结果显示,高氧组7d和14 d,Ang-1的mRNA水平显著低于空气组(0.85±0.14)∶(0.44±0.21),P＜0.05,(0.87±0.24)∶(0.24±0.05),P＜0.01],Ang-1的蛋白水平也显著低于空气组(0.88±0.31)∶(0.41 ±0.12),P＜0.05,(0.90 ±0.29):(0.21 ±0.06),P＜0.01].结论 持续吸入高浓度氧导致新生大鼠的肺血管发育障碍,Ang-1的表达下调可能参与了早产儿BPD血管发育受阻的发生机制.

Effects of hyperoxia on lung vascular development and expression of angiopoietin-1 in neonatal rat lungs

Objective To study the effects of prolonged 85％ oxygen exposure on lung vascular development and the expression of angiopoietin-1 (Ang-1) in the neonatal rat lungs.Methods Ninety-six Sprague-Dawley rat pups were randomly exposed to air (control group) and 85％ oxygen (experimental group) 6 hrs after birth.The rats were sacrificed 3,7 and 14 days after exposure and their lungs were sampled.The lung sections were stained with hematoxylin and eosin for histological evaluation and analysis of vessel volume density.Expressions of angiopoietin-1 (Ang-1) in lung tissue were measured by immunohistochemistry.Expression of Ang-1 protein and mRNA was detected by Western Blot and Real timePCR.Results After being exposed to 85％ oxygen for 14 days,lung tissues had pathological changes as "new" bronchopulmonary dysplasia (BPD).The RAC on day 7 and day 14 in experimental group decreased significantly as compared with the control group ( 10.55 ±0.13 ) vs.( 1 1.74 ±0.19),( 12.47 ±0.05 )vs.( 15.03 ±0.16),P ＜0.05].The X-ray showed that the diameter of lung vessel was much smaller and the vessels had less branches in experimental group compared with the control group on day 14.The vessel volume density on day 14 in experimental group decreased significantly as compared with the control group (3.55 ± 0.09) vs.(6.03 ± 0.16 ),P ＜ 0.05 ].Immunohistochemistry and Western blotting showed that the expressions of Ang-1 protein on day 7 and day 14 in the experimental group decreased significantly as compared with the control group (4.27 ± 0.34 ) vs.( 3.10 ± 0.29 ),P ＜ 0.05,( 5.65 ± 0.49 ) vs.(3.21±0.28),P＜0.01],(0.88±0.31) vs.(0.41±0.12),P＜0.05,(0.90±0.29) vs.(0.21±0.06),P＜0.01 ].The expressions of Ang-1 mRNA on day 7 and day 14 in the experimental group also decreased significantly as compared with the control group (0.85 ±0.14) vs.(0.44 ±0.21 ),P ＜0.05,(0.87 ± 0.24 ) vs.(0.24 ± 0.05 ),P ＜ 0.01 ].Conclusions Prolonged exposure of high concentration of oxygen may cause impairment of lung vascular development by inhibiting expression of Ang-1 in neonatal rats,which is likely to contribute to pathogenesis of BPD.