sildenafil-citrate and nitrofen

The etiology of pulmonary vascular abnormalities in CDH is incompletely understood. Studies have demonstrated improvement in pulmonary vasculature with prenatal therapy in animal models. We hypothesize that prenatal sildenafil may attenuate defective pulmonary vascular development via modulation of vSMC phenotype from undifferentiated, proliferative phenotype to differentiated, contractile phenotype. We utilized the nitrofen model of CDH to examine the effect of IA sildenafil on pulmonary vSMC phenotype during lung development. Timed-pregnant CD-1 mice were gavage fed 25 mg nitrofen or olive oil (control) at E8.5 of gestation. Single IA injections of Sildenafil (Revatio; 10 µL of 4 mg/4 ml solution) or dextrose control were performed at E12.5. Mice were sacrificed on various gestational days for embryonic lung harvest. Markers of vSMC development of undifferentiated and differentiated phenotypes were analyzed by immunostaining and western blot. Across all time points in gestation, nitrofen-treated embryonic lungs demonstrated increased vSMC expression of NOTCH3, Hes-5, PDGFR-β, desmin and α-SMA and decreased expression of calponin and SMMHC, compared to oil controls. IA dextrose treatment had no effect on expression levels. However, IA Sildenafil treatment resulted in down-regulation of NOTCH3, Hes-5, PDGFR-β, desmin and α-SMA and upregulation of calponin and SMMHC, comparable to oil controls. In the nitrofen model, vSMC express markers consistent with more undifferentiated proliferative phenotype, resulting in hypermuscularization of intrapulmonary arterioles in CDH. A single dose of IA Sildenafil treatment early in gestation, results in sustained normalization of vSMC phenotype. Pharmacologic modulation of the vSMC phenotype at key gestational points may have therapeutic potential.

Topics: Amnion; Animals; Female; Hernias, Diaphragmatic, Congenital; Injections; Lung; Mice; Muscle, Smooth, Vascular; Phenotype; Phenyl Ethers; Pregnancy; Sildenafil Citrate; Vasodilator Agents

Pulmonary hypoplasia and hypertension is a leading cause of morbidity and mortality in congenital diaphragmatic hernia (CDH). The etiologic insult occurs early in gestation highlighting the potential of prenatal interventions. We evaluated prenatal pharmacologic therapies in the nitrofen CDH model.. Olive oil or nitrofen were administered alone or with dexamethasone (DM), sildenafil, or DM+sildenafil to pregnant rats. Newborn pups were assessed for lung function, structure and pulmonary artery (PA) flow and resistance.. Prenatal DM treatment of CDH pups increased alveolar volume density (Vva), decreased interalveloar septal thickness, increased tidal volumes and improved ventilation without improving oxygenation or PA resistance. Sildenafil decreased PA resistance and improved oxygenation without improving ventilation or resulting in significant histologic changes. DM+sildenafil decreased PA resistance, improved oxygenation and ventilation while increasing Vva and decreasing interalveolar septal and pulmonary arteriole medial wall thickness. Lung and body weights were decreased in pups treated with DM and/or sildenafil.. Prenatal DM or sildenafil treatment increased pulmonary compliance and decreased pulmonary vascular resistance respectively, and was associated with improved neonatal gas exchange but had a detrimental effect on lung and fetal growth. This study highlights the potential of individual and combined prenatal pharmacologic therapies for CDH management.

Topics: Animals; Arterioles; Body Weight; Dexamethasone; Female; Hernias, Diaphragmatic, Congenital; Hypertension, Pulmonary; Lung; Olive Oil; Organ Size; Oxygen; Phenyl Ethers; Pregnancy; Pregnancy, Animal; Pulmonary Artery; Rats; Rats, Sprague-Dawley; Respiratory Function Tests; Respiratory Physiological Phenomena; Sildenafil Citrate; Stroke Volume; Trachea

Patients with congenital diaphragmatic hernia (CDH) suffer from severe pulmonary hypertension attributable to altered development of the pulmonary vasculature, which is often resistant to vasodilator therapy. Present treatment starts postnatally even though significant differences in the pulmonary vasculature are already present early during pregnancy. We examined the effects of prenatal treatment with the phosphodiesterase-5 inhibitor sildenafil on pulmonary vascular development in experimental CDH starting at a clinically relevant time. The well-established, nitrofen-induced CDH rodent model was treated daily with 100 mg/kg sildenafil from day 17.5 until day 20.5 of gestation (E17.5-20.5). Importantly, this timing perfectly corresponds to the developmental stage of the lung at 20 wk of human gestation, when CDH is detectable by 2D-ultrasonography and/or MRI. At E21.5 pups were delivered by caesarean section and euthanized by lethal injection of pentobarbital. The lungs were isolated and subsequently analyzed using immunostaining, real-time PCR, and volume measurements. Prenatal treatment with sildenafil improved lung morphology and attenuated vascular remodeling with reduced muscularization of the smaller vessels. Pulmonary vascular volume was not affected by sildenafil treatment. We show that prenatal treatment with sildenafil within a clinically relevant period improves pulmonary vascular development in an experimental CDH model. This may have important implications for the management of this disease and related pulmonary vascular diseases in human.

Topics: Animals; Drug Evaluation, Preclinical; Female; Hernias, Diaphragmatic, Congenital; Lung; Maternal Exposure; Maternal-Fetal Exchange; Phenyl Ethers; Phosphodiesterase 5 Inhibitors; Pregnancy; Rats, Sprague-Dawley; Sildenafil Citrate; Vascular Remodeling

Lung hypoplasia, pulmonary persistent hypertension of the newborn and its morphological changes are the main features in congenital diaphragmatic hernia (CDH). This study was undertaken to investigate if antenatal use of sildenafil and/or bosentan attenuates vascular remodeling, promotes branching, and improves alveolarization in experimental nitrofeninduced CDH.. Nitrofen (100 mg) was gavage-fed to pregnant rats at post conception day (PCD) 9 to induce CDH. The rats were randomized to 5 groups: 1) control; 2) nitrofen; 3) nitrofen+sildenafil 100 mg/kg per day at PCD 16-20; 4) nitrofen+bosentan 30 mg/kg per day, at PCD 16-20, and 5) nitrofen+bosentan+sildenafil, same doses and administration days. After cesarean delivery, the offsprings were sacrificed. The diaphragmatic defect and pulmonary hypoplasia were identified, and the lungs were dissected. Arterial wall thickness, bronchiolar density and alveolarization were assessed.. The offsprings with CDH were characterized by severe pulmonary hypoplasia (lung weight-to-body weight ratio: 0.0263 [95% confidence interval (CI) 0.0242-0.0278)] in the nitrofen group versus 0.0385 (95% CI 0.0355-0.0424) in the control group (P=0.0001). Pulmonary arterial wall thickness was decreased to 3.0 (95% CI 2.8-3.7) μm in the nitrofen+sildenafil group versus 5.0 (95% CI 4.1-4.9) μm in the nitrofen group (P=0.02). Terminal bronchioles increased to 13.7 (95% CI 10.7-15.2) μm in the nitrofen+bosentan group in contrast to 8.7 (95% CI 7.2-9.4) μm in the nitrofen group (P=0.002). More significant differences (P=0.0001) were seen in terminal bronchioles in the nitrofen+sildenafil+bosentan group than in the nitrofen group [14.0 (95% CI 12.5-15.4) μm versus 8.5 (95% CI 7.1-9.3) μm]. Pulmonary arterial wall thickness was also decreased in the former group.. In this rat model, antenatal treatment with sildenafil attenuates vascular remodeling. Bosentan promotes the development of terminal bronchioles in nitrofen-induced CDH.

Topics: Animals; Bosentan; Disease Models, Animal; Female; Hernias, Diaphragmatic, Congenital; Lung; Lung Diseases; Phenyl Ethers; Piperazines; Pregnancy; Purines; Random Allocation; Rats; Rats, Wistar; Sildenafil Citrate; Sulfonamides; Vascular Remodeling

Lung hypoplasia and persistent pulmonary hypertension of the newborn limit survival in congenital diaphragmatic hernia (CDH). Unlike other diseases resulting in persistent pulmonary hypertension of the newborn, infants with CDH are refractory to inhaled nitric oxide (NO). Nitric oxide mediates pulmonary vasodilatation at birth in part via cyclic GMP production. Phosphodiesterase type 5 (PDE5) limits the effects of NO by inactivation of cyclic GMP. Because of the limited success in postnatal management of CDH, we hypothesized that antenatal PDE5 inhibition would attenuate pulmonary artery remodeling in experimental nitrofen-induced CDH.. Nitrofen administered at embryonic day 9.5 to pregnant rats resulted in a 60% incidence of CDH in the offspring and recapitulated features seen in human CDH, including structural abnormalities (lung hypoplasia, decreased pulmonary vascular density, pulmonary artery remodeling, right ventricular hypertrophy), and functional abnormalities (decreased pulmonary artery relaxation in response to the NO donor 2-(N,N-diethylamino)-diazenolate-2-oxide). Antenatal sildenafil administered to the pregnant rat from embryonic day 11.5 to embryonic day 20.5 crossed the placenta, increased fetal lung cyclic GMP and decreased active PDE5 expression. Antenatal sildenafil improved lung structure, increased pulmonary vessel density, reduced right ventricular hypertrophy, and improved postnatal NO donor 2-(N,N-diethylamino)-diazenolate-2-oxide-induced pulmonary artery relaxation. This was associated with increased lung endothelial NO synthase and vascular endothelial growth factor protein expression. Antenatal sildenafil had no adverse effect on retinal structure/function and brain development.. Antenatal sildenafil improves pathological features of persistent pulmonary hypertension of the newborn in experimental CDH and does not alter the development of other PDE5-expressing organs. Given the high mortality/morbidity of CDH, the potential benefit of prenatal PDE5 inhibition in improving the outcome for infants with CDH warrants further studies.

Topics: Animals; Body Weight; Brain; Cyclic GMP; Cyclic Nucleotide Phosphodiesterases, Type 5; Disease Models, Animal; Female; Hernia, Diaphragmatic; Hernias, Diaphragmatic, Congenital; Hypertension, Pulmonary; Lung; Nitric Oxide; Phenyl Ethers; Phosphodiesterase 5 Inhibitors; Piperazines; Pregnancy; Pulmonary Artery; Purines; Rats; Rats, Sprague-Dawley; Sildenafil Citrate; Sulfones