摘要
目的探讨维甲酸(RA)对高氧暴露下早产大鼠肺组织胰岛素样生长因子Ⅱ(IGF-Ⅱ)、Ⅱ型IGF受体(IGF-2R)及IGF结合蛋白2(IGFBP-2)mRNA和多肽表达的影响及其抗损伤机制。方法260只孕21d剖宫产鼠为早产鼠,生后第2天随机分为四组,Ⅰ组:空气+生理盐水;Ⅱ组:高氧(85%O2)+生理盐水;Ⅲ组:空气+RA;Ⅳ组:高氧+RA。Ⅱ、Ⅳ组持续暴露于85%氧气中,Ⅰ、Ⅲ组置于空气中;Ⅲ、Ⅳ组从生后第3天起每日腹腔注射RA,Ⅰ、Ⅱ组每日注射生理盐水。分别于生后4、7、10、14、21d记病死率,取肺标本作辐射状肺泡计数(RAC);测IGF-Ⅱ、IGF-2R和IGFBP-2mRNA表达强度(RT-PCR)或多肽表达强度(Western印迹)。结果(1)存活率:7d内四组差异无统计学意义;7d后各时间点Ⅱ、Ⅳ组明显低于Ⅰ、Ⅲ组(P<0.05或<0.01),但Ⅳ组明显高于Ⅱ组(P<0.01)。(2)RAC结果:4d时,Ⅱ、Ⅳ组RAC值即明显减少(P<0.01);随后与对应Ⅰ、Ⅲ组比较差异有统计学意义(P<0.01),但Ⅳ组明显高于Ⅱ组(P<0.01)。(3)RT-PCR结果:IGF-ⅡmRNA表达强度:与Ⅰ、Ⅲ组相比,Ⅱ、Ⅳ组4d时表达即增强(P<0.01);14d时,Ⅱ组较Ⅰ组、Ⅳ组较Ⅲ组表达差异有统计学意义(P<0.01);其中Ⅳ组表达较Ⅱ组相对降低(P<0.01);IGF-2RmRNA表达强度在4和14d时,Ⅱ、Ⅳ组明显高于Ⅰ、Ⅲ组(P均<0.01),而Ⅳ组明显低于Ⅱ组(P<0.01);IGFBP-2mRNA表达强度:Ⅱ、Ⅳ组明显强于相应的Ⅰ、Ⅲ组,但14d时Ⅳ组表达低于Ⅱ组(P<0.01)。肽表达强度结果:IGF-Ⅱ多肽、IGF-2R膜蛋白、IGFBP-2多肽的表达强度与其各自的mRNA表达变化相似。结论RA可部分逆转高氧引发的肺发育阻滞;RA下调高氧暴露下肺组织中IGFBP-2、IGF-Ⅱ和IGF-2R的表达可能是其干预肺损伤的机制之一。
Objective To explore the influence of retinoic acid （RA） on the expressions of insulin-like growth factor （IGF）-Ⅱ ,type 2 IGF receptor （IGF-2R） and IGF binding protein （IGFBP）-2 mRNA and polypeptides in lungs of hyperoxia-exposed premature rats and its possible molecular mechanism. Methods On the 2nd postnatal day, 260 Sprague-Dawley（SD）preterm rats were randomly divided into 4 groups. Group Ⅰ, air ＋ normal saline （NS） group; Group Ⅱ ,hyperoxia（85% O2） ＋ NS group; Group Ⅲ： air＋ RA group; Group Ⅳ： hyperoxia（85% O2） ＋ RA group. RA was injected to group Ⅲ , Ⅳ intraperitoneally （500μg/kg） since the 3rd day after birth, while NS was given to group Ⅰ, Ⅱ daily at the same time as group Ⅱ and Ⅳ. On day 4, 7, 10, 14 and 21 after birth, 8 rats in each group were killed. The mortality of preterm rats was recorded and lung radical alveolar counts （RAC） were examined. The mRNA analysis （RT-PCR） and polypeptides analysis （Western Blot） of IGF-Ⅱ , IGF-2R and IGFBP-2 were performed. Results 1. On the 4-7th day of exposure, the survival rate in all groups were similar. After 7 days of 85% O2 exposure, the survival rate in group Ⅱ , Ⅳ dropped sharply and there was a significant difference comparing to group Ⅰ , Ⅲ （P〈0.05, both）. After applying to RA, the rate in group Ⅳ was significantly higher than that in group Ⅱ （P〈0.05）. 2. On the 4th day of exposure, RACs in group Ⅱ ,Ⅳ were lower than those in group Ⅰ and Ⅲ （P%0.01; both）. Compared with group Ⅰ and Ⅲ , RACs in group Ⅱ and Ⅳ were significantly decreased （P〈0.01） after 7 days, but those in group Ⅳ were significantly higher than those in group Ⅱ （P〈0.01）. The expression of IGF-Ⅱ mRNA in group Ⅱ , IV was obviously increased（14 d： Ⅱ vs Ⅰ ,t =15.57, P〈0.01; Ⅳ vs Ⅲ, t=9.93, P%0.01）, but compared with in group II, the a bundance in group Ⅳ was obviously reduced （t =43.00, P〈0.01）. The expression of IGF-2R mRNA on the 4th and 14th day in group Ⅱ , Ⅳ was higher than those in group Ⅰ and Ⅲ （P〈0.01, both）, how-ever the expression in group Ⅳ was significantly lower than that in group Ⅱ （P〈0.01）. In group Ⅱ , Ⅳ, the expression of IGFBP-2 mRNA was markedly higher than that in group Ⅰ and Ⅲ （P%0.01）, but the expression in group Ⅳ was significantly lower than that of group Ⅱ, The expressions of IGF-Ⅱ , IGF-2R and IGFBP-2 polypeptides was similar to those of their mRNA in all 4 groups. Conclusions RA may partly prevent the retardation of fetal lung development caused by prolonged hyperoxia-exposure. The possible mechanism might be that RA down-regulates the expressions of IGF-Ⅱ , IGF-2R and IGFBP-2 in the fetal lung tissues under hyperoxia.
出处
《中华围产医学杂志》
CAS
2005年第4期259-263,共5页
Chinese Journal of Perinatal Medicine
基金
湖北省重点科技发展计划项目资助(20002P1601)
