Pathogenesis of nitrofen-induced congenital diaphragmatic hernia in fetal rats

Abstract

Congenital diaphragmatic hernia (CDH) is a developmental anomaly characterized by the malformation of the diaphragm and impaired lung development. In the present study, we tested several hypotheses regarding the pathogenesis of CDH, including those suggesting that the primary defect is due to abnormal 1) lung development, 2) phrenic nerve formation, 3) developmental processes underlying diaphragmatic myotube formation, 4) pleuroperitoneal canal closure, or 5) formation of the primordial diaphragm within the pleuroperitoneal fold. The 2,4-dichloro-phenyl-p-nitrophenyl ether (nitrofen)-induced CDH rat model was used for this study. The following parameters were compared between normal and herniated fetal rats at various stages of development: 1) weight, protein, and DNA content of lungs; 2) phrenic nerve diameter, axonal number, and motoneuron distribution; 3) formation of the phrenic nerve intramuscular branching pattern and diaphragmatic myotube formation; and 4) formation of the precursor of the diaphragmatic musculature, the pleuroperitoneal fold. We demonstrated that previously proposed theories regarding the primary role of the lung, phrenic nerve, myotube formation, and the closure of pleuroperitoneal canal in the pathogenesis of CDH are incorrect. Rather, the primary defect associated with CDH, at least in the nitrofen rat model, occurs at the earliest stage of diaphragm development, the formation of the pleuroperitoneal fold.

Retinal Dehydrogenase-2 Is Inhibited by Compounds that Induce Congenital Diaphragmatic Hernias in Rodents

“…The number of diaphragmatic defects produced by each of the compounds and data regarding the location of the diaphragmatic defects are contained in Table 1. As reported previously, 18 a single dose of nitrofen administered on E8 results in ϳ50% of the embryos having hernias, with a predominance of left-sided defects. Past studies have also demonstrated that single doses of nitrofen administered beyond E11 induced solely right-sided defects.…”

“…In some cases, immunolabeling for neural cell adhesion molecule was performed to delineate the orientation of myotubes and/or phrenic nerve intramuscular branches. 18 Photographs of the diaphragms were taken with a Nikon 990 digital camera mounted on a Leica research microscope.…”

The transcriptome of nitrofen-induced pulmonary hypoplasia in the rat model of congenital diaphragmatic hernia

“…Whether the nitrofen-rat model shares the same pathogenesis with human CDH remains to be determined. Some hypotheses suggest that nitrofen influences diaphragm and lung development in rodent embryos similar to the human condition (6)(7)(8). Thus far, the transcriptomic changes associated with nitrofen-modulated developmental signaling have not been characterized in the lung.…”

Effect of nitrofen in the final stages of development of the diaphragm muscle in rats

“…CDH occurs approximately in 1 in every 3000 live births 2 , totaling about 8% of major congenital anomalies, with mortality rates ranging from 62% to 79% 3 . This high mortality is mainly attributed to pulmonary hypoplasia and hypertension, especially due to the biochemical and structural immaturity that occurs secondary to intrathoracic occupation by abdominal viscera 4 .…”