The Ritchie Centre, Monash Institute of Medical Research, Monash University, Clayton, Victoria, Australia.
Pediatr Res. 2012 Jun;71(6):689-96. doi: 10.1038/pr.2012.19. Epub 2012 Feb 15.
Intrauterine growth restriction (IUGR) is associated with high rates of neonatal morbidity. IUGR babies are often born preterm and are, therefore, exposed to antenatal glucocorticoids. Antenatal glucocorticoids significantly improve overall survival rates of preterm infants, but there is a paucity of information about their effects on IUGR Infants.
We induced IUGR in sheep by single umbilical artery ligation (SUAL), or sham in control fetuses. To half the ewes, we administered betamethasone (BM) on d 5 (BM1) and 6 (BM2) following surgery, and collected fetal lung tissue on d 7.
SUAL alone was associated with higher circulating fetal cortisol levels (2.8 ± 0.4 vs. 1.0 ± 0.4, P = 0.001) as compared with controls but not with changes in lung morphology or surfactant protein (SP) gene expression. BM was associated with a significant reduction in lung tissue density (P = 0.048). There were no significant differences between groups in lung DNA concentration or septal crest density. SP-A, SP-B, and SP-C gene expressions were significantly increased in control and SUAL fetuses that were administered BM.
These results show that in SUAL fetuses, maternal BM is associated with acceleration of fetal lung structure, as occurs in normally grown fetuses, and that BM induces SP production, an effect not observed in SUAL-induced IUGR fetuses alone.
宫内生长受限（IUGR）与新生儿高发病率有关。IUGR 婴儿通常早产，因此暴露于产前糖皮质激素中。产前糖皮质激素可显著提高早产儿的总体存活率，但关于其对 IUGR 婴儿的影响的信息很少。
我们通过单脐动脉结扎（SUAL）诱导绵羊 IUGR，或在对照胎儿中进行假手术。对一半的母羊，我们在手术后第 5 天（BM1）和第 6 天（BM2）给予倍他米松（BM），并在第 7 天收集胎儿肺组织。
与对照组相比，SUAL 单独与更高的循环胎儿皮质醇水平（2.8 ± 0.4 对 1.0 ± 0.4，P = 0.001）相关，但与肺形态或表面活性蛋白（SP）基因表达的变化无关。BM 与肺组织密度的显著降低相关（P = 0.048）。各组之间肺 DNA 浓度或隔嵴密度无显著差异。在接受 BM 治疗的对照组和 SUAL 胎儿中，SP-A、SP-B 和 SP-C 基因表达均显著增加。
这些结果表明，在 SUAL 胎儿中，母体 BM 与正常生长胎儿中发生的胎儿肺结构加速有关，并且 BM 诱导 SP 产生，这一效应在单独的 SUAL 诱导 IUGR 胎儿中未观察到。
