Expression of placental growth factor in neonatal rat lungs after 85% hyperoxia exposure / 中华围产医学杂志

ABSTRACT

Objective To investigate the expression of placental growth factor (PlGF) protein and mRNA in lungs of neonatal rats exposed to 85%hyperoxia, and to establish the relationship between PlGF and bronchopulmonary dysplasia (BPD). Methods Forty-eight Sprague–Dawley neonatal rats were randomly exposed to air (control group)(n=24) and 85% hyperoxia (hyperoxia group)(n=24)within 12 h after birth. The rats were sacrificed at 3, 5 and 7 days after exposure (eight at each time) and their lungs were sampled. PlGF protein and mRNA expression in the lungs were determined by Western blot and real-time polymerase chain reaction (PCR) at 3, 5 and 7 days. Left lung tissue was used for morphological and histological observation with hematoxylin and eosin staining. Terminal air spaces and the secondary septa were counted manually under microscope. T-test was applied for statistics. Results Compared with the control group, morphological and histological analysis in the hyperoxia group revealed inflammatory cell infiltration, simplified alveolar structure, less alveolar, alveolar cavity expansion and thickened alveolar septum. Morphometric measurements showed that terminal air spaces and secondary septa were significantly fewer in the hyperoxia rats than those in the control group at 5 and 7 days (terminal air spaces23.6±8.2 vs 33.1±6.2 and 28.5±9.2 vs 38.4±10.1, t=1.91, 2.53, all P<0.05;secondary septa56.0±12.2 vs 78.3±8.2 and 75.4±12.2 vs 126.1±10.2, t=2.14, 2.72, all P<0.05). Real-time PCR showed that expression of PlGF mRNA increased significantly on day 3, 5 and 7 in the hyperoxia group compared with the control group (1.16±0.17, 1.34±0.15 and 1.65±0.19 vs 0.65±0.21, 0.47±0.11 and 0.46±0.17, respectively, t=1.93, 2.55, 2.79, all P<0.05). Western blot also showed that expression of PlGF protein on day 3, 5 and 7 in the hyperoxia group increased compared with the control group, but only being significant on day 3 (0.24±0.17 vs 0.09±0.01, t=2.44, P<0.05). Conclusions Hyperoxia (85%) exposure could increase PlGF protein and mRNA expression in the lungs of neonatal rats, likely contributing to pathogenesis of BPD, and might lead to pulmonary vascular developmental disorders in BPD.