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1715786 
Journal Article 
Retinal dehydrogenase is inhibited by compounds that induce congenital diaphragmatic hernias in rodents 
Greer, JJ; Mey, J; Babiuk, RP; Clugston, R 
2002 
1 
Pediatric Research
ISSN: 0031-3998
EISSN: 1530-0447 
DART/TER/2001482 
51 
4 Pt 2 
English 
BACKGROUND: Congenital diaphragmatic hernia (CDH) is a serious developmental disorder in which the diaphragm muscle fails to form completely. Data derived from studies of the nitrofen rodent model of CDH suggest that the pathogenesis is linked to a malformation of the primordial diaphragm, the pleuroperitoneal fold. However, the etiology of CDH is completely unknown and there has been a lack of research directed specifically toward this important issue. Further, an understanding of the mechanisms underlying nitrofen's teratogenicity is lacking. Given the striking similarities between the pathologies observed in the nitrofen-induced rat models and infants with CDH, the possibility of there being a common underlying etiology certainly has to be considered. Our previous studies (Greer et al, 2001 SPR abstracts) demonstrated a direct interaction of nitrofen and the retinoid system using transgenic mice with a lacZ reporter linked to a retinoid response element (RARE). In this study, we take the next step by determining the specific stage in the retinoid cascade affected by nitrofen and other teratogens that induce diaphragmatic defects. OBJECTIVE: To test the hypothesis that teratogens which induce diaphragmatic defects similar to those observed in infants with congenital diaphragmatic hernia (CDH) act via the inhibition of retinal dehydrogenase 2 (RALDH2), a key enzyme necessary for the production of retinoic acid. DESIGN/METHODS: Inhibition of RALDH2 was assayed using IEF fractions of cytosolic extracts from an oligodendrocyte cell line that synthesizes RALDH2. The extracts confirmed to have RALDH2 activity were incubated with retinal and each of the teratogens at a range of concentrations. Then a sample from each well was incubated in wells with cells having a RARE-LacZ reporter gene and the level of RA production (RALDH2 inhibition) was measured colorimetrically. RESULTS: We demonstrate that the following compounds all induce posterolateral defects in the rat diaphragm; nitrofen, 4-biphenyl carboxylic acid, bisdiamine and SB-210661. Importantly, they all share the same common mechanism of inhibiting retinal dehydrogenase in a dose-dependent manner. CONCLUSIONS: These data provide an important component of mounting evidence suggesting that the retinoid system warrants consideration in future studies of the etiology of CDH.