Imbalance of Caveolin-1 and eNOS Expression in the Pulmonary Vasculature of Experimental Diaphragmatic Hernia

BACKGROUND: Caveolin-1 (Cav-1) exerts major regulatory functions on intracellular signaling pathways originating at the plasma membrane. Cav-1 is a key regulator in adverse lung remodeling and the development of pulmonary hypertension (PH) regulating vasomotor tone through its ability to reduce nitric oxide (NO) production. This low-output endothelial NO synthase (eNOS) derived NO maintains normal pulmonary vascular homeostasis. Cav-1 deficiency leads to increased bioavailability of NO, which has been linked to increased nitrosative stress. Inhibition of eNOS reduced oxidant production and reversed PH, supporting the concept that Cav-1 regulation of eNOS activity is crucial to endothelial homeostasis in lungs. We designed this study to investigate the hypothesis that expression of Cav-1 is downregulated while eNOS expression is upregulated by the pulmonary endothelium in the nitrofen-induced congenital diaphragmatic hernia (CDH). METHODS: Pregnant rats were exposed to nitrofen or vehicle on day 9.5 (D9.5). Fetuses were sacrificed on D21 and divided into nitrofen and control groups. Quantitative real-time polymerase chain reaction, Western blotting, and confocal immunofluorescence were performed to determine pulmonary gene expression levels and protein expression of Cav-1 and eNOS. RESULTS: Pulmonary Cav-1 gene expression levels were significantly decreased, while eNOS gene expression was significantly increased in nitrofen-induced CDH(+). Western blotting and confocal microscopy revealed decreased pulmonary Cav-1 protein expression, while eNOS protein expression was increased in CDH(+) compared to controls. CONCLUSION: The striking evidence of markedly decreased gene and protein expression of Cav-1 with concurrently increased eNOS gene and protein expression in the pulmonary vasculature suggests that activation of eNOS secondary to Cav-1 deficiency may play an important role in the pathogenesis of PH in the nitrofen-induced CDH. (C) 2014 Wiley Periodicals, Inc.