维甲酸治疗新生大鼠高氧肺发育受抑对肺组织基质金属蛋白酶及其组织抑制剂表达的影响

The therapeutic effect of retinoic acid on the expression of metalloproteinase and metalloproteinase in hyperoxic inhibition of lung development in newborn rats

目的 观察维甲酸(RA)对高氧抑制肺发育的影响,初步探讨其作用机制。方法 新生SD大鼠生后d2随机分为I空气+生理盐水组,Ⅱ高氧+生理盐水组,Ⅲ空气+RA组,Ⅳ高氧+RA组。Ⅱ、Ⅳ组持续暴露于85％氧气中,Ⅲ、Ⅳ组每日腹腔注射RA500μg/kg。生后14d行肺组织病理学检查,辐射状肺泡计数(RAC)和免疫组化法检测基质金属蛋白酶(MMP-2、MMP-9)及其组织抑制剂(TIMP-1、TIMP-2)的表达。结果Ⅱ、Ⅳ组肺组织显示肺泡生成受抑,RAC分别较I、Ⅲ组显著减少(P<0.01),但Ⅳ组RAC(8.3±0.8)较Ⅱ组(7.2±0.9)明显增加(P<0.01)。Ⅱ、Ⅳ组MMP-2、MMP-9、TIMP-1和TIMP-2的表达较I、Ⅲ组明显增强(P<0.01),但Ⅳ组MMP-2、MMP-9的表达(2.70±0.65,2.64±0.48)较Ⅱ组(3.36±0.59,3.04±0.72)减弱(P<0.05),而TIMP-1的表达(3.68±0.51)较Ⅱ组(3.32±0.63)增强(P<0.05),TIMP-2的表达无统计学差异。结论 RA可部分阻止高氧引起的肺发育进程阻滞,可能是通过纠正MMPs/TIMPs的失衡而发挥作用的。

Objective To investigate the effect of retinoic acid (RA) on hyperoxia-induced inhibition of lung development, and to explore its mechanism. Methods On the 2nd postnatal day SD newborn rats were randomly assigned to four groups: group one (air +NS), group two (hyperoxia+NS), group three (air+RA) , and group four (hyperoxia+RA). Group two and group four were exposed to about 85 % O2. Group three and group four were injected with RA intraperitoneally daily (500μg/kg). On 14 days after birth 6 rats in each group were killed. Lung histologic changes by HE staining, alveolarization by radical alveolar counts (RAC) and expression of MMP-2, MMP-9, TIMP-1 and TIMP-2 in lungs by immunohistochemistry were tested. Result Group two and group four showed inhibition of alveolar formation. In contrast to group one and group three, RAC in group two and four decreased dramatically ( P <0.01). But compared with RAC of group two (7.2±0.9), RAC in group four(8.3±0.8)increased significantly(P<0.01). The expression of MMP-2, MMP-9, TIMP-1 and TIMP-2 in group two and group four were stronger than that in group one and group three respectively(P<0.01). Compared with group two, group four showed lower expression of MMP-2, MMP-9 (2.70± 0.65, 2.64±0.48 vs 3.36±0.59, 3.04±0.72)( P<0.05), and higher TIMP-1 of TIMP-1(3.68±0.51 vs3.32±0.63)( P< 0.05), while TIMP-2 expression failed to reach significantly ( P>0.05). Conclusion Retinoic acid might partially prevent hyperoxi-ainduced arrest of lung development probably by correcting imbalance of MMPs/TIMPs.