Upregulation of Slit-2 and Slit-3 gene expressions in the nitrofen-induced hypoplastic lung.

PURPOSE: The pathogenesis of pulmonary hypoplasia in the nitrofen-induced congenital diaphragmatic hernia (CDH) is not clearly understood. Slit-2 and Slit-3 are expressed in fetal lung and play a key role in directing the functional organization and differentiation of lung mesenchyme during branching morphogenesis. We hypothesized that the pulmonary gene expression levels of Slit genes are altered in the nitrofen-induced CDH. MATERIALS AND METHODS: Pregnant rats were exposed to either olive oil or nitrofen on day 9 of gestation (D9). Fetal lungs were harvested on D15 and D21 and divided into 2 groups as follows: CDH (n = 9 at each time-point) and control (n = 9 at each time-point). The pulmonary gene expression levels of Slit-2, Slit-3, Robo1, and Robo2 were analyzed by real time reverse transcription polymerase chain reaction. Student's t test or Mann-Whitney U test was used for statistical analysis. RESULTS: Relative messenger RNA expression levels of Slit-2 and Slit-3 were significantly increased in CDH lungs compared to control at both D15 and D21 (P < .05). However, there were no significant differences between CDH and controls in the pulmonary gene expression levels of Robo1 and Robo2 at each time-point. CONCLUSION: Our results provide evidence, for the first time, that Slit genes are upregulated in nitrofen-induced hypoplastic lungs in both early and late stages of lung development. Altered pulmonary Slit gene expression may disrupt branching lung morphogenesis resulting in pulmonary hypoplasia.