Downregulation of insulin-like growth factor binding protein 3 and 5 in nitrofen-induced pulmonary hypoplasia.
OBJECTIVE
The high mortality in congenital diaphragmatic hernia (CDH) is mainly attributed to pulmonary hypoplasia. Recent studies suggest that retinoid signaling pathway (RSP) is inhibited in the nitrofen-induced hypoplastic lung. The insulin-like growth factor (IGF) system plays a crucial role in fetal lung development by interaction of IGFBP-3 and IGFBP-5 with RSP. We hypothesized that pulmonary IGFBP-3 and IGFBP-5 gene expression levels are downregulated in the nitrofen-induced pulmonary hypoplasia.


METHODS
Pregnant rats were exposed to either olive oil or 100 mg nitrofen on day 9.5 (D9.5) of gestation. Fetal lungs were harvested on D18 and D21 and divided into control and nitrofen groups. IGFBP-3 and IGFBP-5 pulmonary gene and protein expression were determined using real-time RT-PCR and immunohistochemistry.


RESULTS
Relative levels of IGFBP-3 mRNA were significantly decreased in the nitrofen group (8.00 +/- 14.44) in D21 compared to controls (14.81 +/- 16.11; p < 0.05). Expression levels of IGFBP-5 mRNA were also significantly decreased in nitrofen group (10.66 +/- 4.83) on D18 compared to controls (17.92 +/- 4.77). Immunohistochemistry showed decreased IGFBP-3 expression on D21 and decreased IGFBP-5 immunoreactivity on D18 in hypoplastic lungs compared to controls.


CONCLUSIONS
Downregulation of IGFBP-3 and IGFBP-5 gene expression may cause pulmonary hypoplasia in the nitrofen-induced CDH model by interfering with retinoid signaling pathway.
The Children's Research Centre, Our Lady's Children's Hospital, University College Dublin, Dublin 12, Ireland.
Elke
E
Ruttenstock
Takashi
T
Doi
Jens
J
Dingemann
Prem
P
Puri
D000818:Animals; D004195:Disease Models, Animal; D015536:Down-Regulation; D005260:Female; D006548:Hernia, Diaphragmatic / Q000196:embryology / Q000209:etiology; D007150:Immunohistochemistry; D018972:Insulin-Like Growth Factor Binding Protein 3 / Q000235:genetics* / Q000378:metabolism; D018975:Insulin-Like Growth Factor Binding Protein 5 / Q000235:genetics* / Q000378:metabolism; D008168:Lung / Q000002:abnormalities* / Q000196:embryology / Q000378:metabolism; D008171:Lung Diseases / Q000150:complications / Q000196:embryology / Q000235:genetics*; D010647:Phenyl Ethers / Q000633:toxicity; D011247:Pregnancy; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics*; D051381:Rats; D017207:Rats, Sprague-Dawley; D020133:Reverse Transcriptase Polymerase Chain Reaction
D018972:Insulin-Like Growth Factor Binding Protein 3; D018975:Insulin-Like Growth Factor Binding Protein 5; D010647:Phenyl Ethers; D012333:RNA, Messenger; C007350:nitrofen