Nitrofen dose-dependent gestational day-specific murine lung hypoplasia and left-sided diaphragmatic hernia

Abstract

2,4-Dichlorophenyl-p-nitrophenyl ether (nitrofen) is known to induce pulmonary hypoplasia (PH) with or without diaphragmatic hernias (DH) in rats and mice. We determined the timing of administration and dose of nitrofen needed to create left-sided DH and PH in fetal mice. Time-dated pregnant CD-1 mice were gavaged with various doses of nitrofen in the later one-half of gestational days (GD) 8-11. Fetuses were removed by laparotomy at GD 14, fixed, and evaluated histologically. Fetal lung size was inversely related to nitrofen dose. Morphometric analysis of normal and nitrofen-exposed hypoplastic lungs at the pseudoglandular stage revealed significant differences in lung length, surface area, and in the number of airways. Left-sided DH were observed in a "dorsolateral" position accompanied by PH in approximately 30% of GD 14 fetuses exposed to 25 mg nitrofen on GD 8. A minimal portion of liver was present in the hernia. The lungs of fetuses exposed on GD 9, 10, and 11 progressed to near normal size. Murine fetuses exposed to 25 mg nitrofen on GD 8 resulted in PH and DH, whereas other doses created dose-dependent PH alone or none at all on GD 11. Our study established that, to create left-sided DH and PH in murine fetuses, nitrofen dose specificity and time of administration during gestation were crucial.

Peristalsis of airway smooth muscle is developmentally regulated and uncoupled from hypoplastic lung growth

“…Timed-pregnant Sprague-Dawley rats (Charles River) were gavage fed 100 mg of nitrofen (Zheijang Chemicals) dissolved in olive oil on day 9.5 of gestation (vaginal plug ϭ day 0, term ϭ day 22.5) to induce left-sided CDH and pulmonary hypoplasia in newborn pups (6,16). Control animals received olive oil alone.…”

Etiology of Congenital Diaphragmatic Hernia: The Retinoid Hypothesis

“…3) (22-25). Further, heart development is particularly susceptible, as cardiac anomalies are the most common associated defect in infants with CDH (38) and are observed in the rat model of nitrofen-induced CDH (41)(42)(43). It is conceivable that the "safety margin" for retinoic acid mediated regulation of primordial diaphragm, lung and heart development is relatively low and thus more susceptible to perturbations compared with other tissues.…”

Impaired VEGF and nitric oxide signaling after nitrofen exposure in rat fetal lung explants

“…During the past two decades, a well-established model to study CDH in rodents has been developed through the use of the herbicide nitrofen (2,4-dichloro-p-nitrophenyl ether) (14,28,35,50). When a maternal rat or mouse is fed nitrofen at precise time points of lung embryogenesis (E9.5 in rats, E8.5 in mice), the fetus often develops features of CDH that include bilateral lung hypoplasia, with more severe changes on the left lung, and in many cases, diaphragmatic defects (6,14,23,25,35,50). Nitrofen exposure induces small lungs with reduced airway branching and septation, thickened interstitium, and reduced vascular density (10,35).…”

“…Interestingly, abnormal lung growth has been shown to precede the normal timing of diaphragm closure, suggesting that pulmonary hypoplasia is at least partly due to a direct teratogenic insult (14,25). Thus, prenatal nitrofen treatment provides a useful model for studies of molecular and biochemical mechanisms that may cause abnormalities of lung structure in CDH (14,42,45,46).…”