The myenteric plexus of the esophagus is abnormal in an experimental congenital diaphragmatic hernia model.

BACKGROUND/AIM: Infants surviving congenital diaphragmatic hernia (CDH) suffer from anatomical and functional esophageal abnormalities. Previous work in the nitrofen animal model of CDH demonstrated malformations in neural crest-derived structures, including the vagus and recurrent laryngeal nerves. The aim of the present study was to assess whether the esophageal myenteric plexus is abnormal in rats with CDH. METHODS: We used the nitrofen-induced CDH fetal rat model. Two sections of the proximal, medium and distal esophagus from both groups were processed for immunohistochemical staining with anti-neuron specific enolase and anti-S-100 antibodies; the number of stained areas was recorded for each group. Whole-mount preparations of the entire esophagus of Control and CDH animals were histochemically stained for acetylcholinesterase; the density and area of the ganglia and the number of cells/ganglia were determined. Comparisons between groups were made by standard statistical methods. RESULTS: The number of immunohistochemically stained areas in transversal sections were decreased in CDH animals for anti-enolase (11.5+/-6.06 vs. 1.93+/-1.49, control vs. CDH, p<0.001) and anti S-100 antibodies (8.57+/-4.1 vs. 4.06+/-2.82, p<0.001). In whole-mount preparations the number of ganglia per high power field (35.16+/-6.57 vs. 29.29+/-10.26, p<0.05), the number of cells per ganglia (11.85+/-3.52 vs. 2.28+/-4.61, p<0.0001) and the relative area of the ganglia (0.35+/-0.32 vs. 0.18+/-0.42%, p<0.001), were also significantly decreased in CDH animals compared with Controls. CONCLUSIONS: Esophageal intrinsic innervation is defective in rat fetuses with CDH. If patients with CDH bear the same anomalies, this may explain some of their esophageal motility disorders. Finally, these findings support the concept of neural crest involvement in the pathogenic pathways of CDH.

Los genes Hox en la etiología de la hernia diafragmática congénita y la atresia de esófago / The etiology of congenital diaphragmatic hernia and esophageal atresia: the Hox genes

Introducción: La administración de adriamicina o nitrofena las ratas gestantes produce en su descencencia, respectivamente, atresiaesofágica (AE) con asociación VACTERL o hernia diafragmática congénita (HDC). La etiología de estas acciones no está clara, y han sido involucrados algunos genes como el Sonic hedgehog, la familia Gli, la cascada de los retinoides y algunos genes homeóticos. Los genes Hox son los encargados de la segmentación del embrión y de controlar aspectos fundamentales del desarrollo. Los ratones con pérdida de función para Hoxa3, Hoxb3, Hoxc3, Hoxc4 y Hoxa5 muestran fenotipos compatibles con la asociación VACTERL, malformaciones cardiacas, bronquiales y pulmonares, atresia esofágica y malformaciones diafragmáticas. El presente trabajo resume nuestros hallazgos en las alteraciones de expresión de estos genes en ambos modelos experimentales. Material y métodos: Para el modelo de AE usamos ratonas gestantes a las que se administró 4 mg/kg de adriamicina intraperitoneal en los días 7,5 y 8,5 de gestación (término=19 días). En el caso de la HDC se usó el mismo modelo, administrando nitrofen por vía intragástrica en el día 8. En ambos casos se usaron como grupo control animales alos que se dio por la misma vía el mismo volumen tan solo de excipiente. Los embriones fueron recuperados en los días 13, 14, 15 y 16 en el caso de la AE y en los días 14, 16 y 19 en el caso de la HDC. Los animales completos o sus pulmones y corazones se procesaron para técnicas morfológicas, inmunohistoquímicas y de biología molecular (RTPCR, reacción en cadena de la polimerasa a tiempo real), centrándonos en los genes Hoxa3, Hoxa5, Hoxb3, Hoxb5, Hoxc4 y Hoxd3.Resultados: AE: La inmunohistoquímica reveló grandes diferencias entre los fetos expuestos a adriaminica y los controles en la captación de los anticuerpos para Hoxa3, Hoxb3 y Hoxd3 en todos los tejidos salvo el corazón. La RT-PCR mostró una disminución en la expresión de esos genes en los pulmones pero no en el corazón en los animales tratados con el teratógeno. Lo mismo ocurrió además con Hoxc4.HDC: la expresión de Hoxa3 y Hoxb5 fue similar en los corazones delos 2 grupos. Sin embargo el nitrofen ocasionó un incremento en la expresión de Hoxa5 y Hoxb3 en el corazón de los fetos expuestos enlos días 14 y 19 y una disminución en el 16. En el análisis inmunohistoquímicono se encontraron diferencias entre los grupos. Conclusiones: En ambos modelos experimentales son evidentes las alteraciones de los genes Hox estudiados, especialmente en tejido pulmonar cardiaco. Las malformaciones de estos órganos asociadas a la AE y la HDC pueden ser debidas, entre otras causas, a alteraciones en la expresión de determinados genes Hox. Debido a su específica participación en la morfogénesis pulmonar y del intestino anterior, su estudio nos podría conducir a una mejor comprensión de la etiología de estas entidades (AU

Background: SP renatal administration of adriamycin ornitrofen to pregnant mice produce in the embryos, respectively, esophagealatresia/VACTERL association (EA) or congenital diaphragmatichernia (CDH). Various genes and signalling pathways like sonic hedgehog, Gli family, retinoic acid and homeotic genes have been pointed out in the origin of these malformations. Hox genes are master regulatory genes involved in embryo segmentation and other main development processes. Hoxa3, Hoxb3, Hoxc3, Hoxc4 and Hoxa5 knock-out mice show cardiac, tracheal, lung and diaphragmatic malformations, EA and phenotypes that resemble that of VACTERL syndrome. We present herein some of our findings in the expression of these genes in both experimental models. Material and methods: Pregnant mice were exposed either to 4 mg/kg of adriamycin or vehicle on embryonic days 7,5 and 8,5; embryos were recovered at four endpoints (E13 to 16). On the other hand, nitrofen was given to pregnant mice on embryonic day 8th and embryos were recovered at E14, E16 and E19. The embryos or, separately, their lungs and hearts, were randomly processed for immunohistochemical or molecularbiology studies (RT-PCR). We used antibodies for Hoxa3, Hoxb3and Hoxd3 proteins and specific primers for Hoxa3, Hoxa5, Hoxb3,Hoxb5, Hoxc4 and Hoxd3 genes. Results: EA: Upon immunohistochemistry, adriamycin-exposed embryos showed a severe decrease in expression of Hoxa3, Hoxb3 and Hoxb3proteins in heart, skin, foregut but not in the heart. RT-PCR studies showed a statistically significant decrease of the four genes studied in the lungs of OA mice when compared to controls. CDH: Upon RT-PCRassessment the expression of Hoxa5 and Hoxb3 were higher in nitrofen-exposed mice than in controls on E14 and E19 and weaker on E16.As regards immunohistochemical localization, expression of the three genes was similar in nitrofen and control animals. Conclusions: Both experimental models exhibit an alteration in the expression of several proximal Hox genes, specially in lung and cardiac tissues. The malformations in these organs associated with CDH and EA could be in part caused by these alterations. Due to their specific participation in lung and foregut morphogenesis, their study could let us to better understand the mechanisms of CDH and EA (AU)

[The etiology of congenital diaphragmatic hernia and esophageal atresia: the Hox genes]. / Los genes Hox en la etiología de la hernia diafragmática congénita y la atresia de esófago.

BACKGROUND: Prenatal administration of adriamycin or nitrofen to pregnant mice produce in the embryos, respectively, esophageal atresia/VACTERL association (EA) or congenital diaphragmatic hernia (CDH). Various genes and signalling pathways like sonic hedgehog, Gli family, retinoic acid and homeotic genes have been pointed out in the origin of these malformations. Hox genes are master regulatory genes involved in embryo segmentation and other main development processes. Hoxa3, Hoxb3, Hoxc3, Hoxc4 and Hoxa5 knock-out mice show cardiac, tracheal, lung and diaphragmatic malformations, EA and phenotypes that resemble that of VACTERL syndrome. We present herein some of our findings in the expression of these genes in both experimental models. MATERIAL AND METHODS: Pregnant mice were exposed either to 4 mg/kg of adriamycin or vehicle on embryonic days 7,5 and 8,5; embryos were recovered at four endpoints (E13 to 16). On the other hand, nitrofen was given to pregnant mice on embryonic day 8th and embryos were recovered at E14, E16 and E19. The embryos or, separately, their lungs and hearts, were randomly processed for immunohistochemical or molecular biology studies (RT-PCR). We used antibodies for Hoxa3, Hoxb3 and Hoxd3 proteins and specific primers for Hoxa3, Hoxa5, Hoxb3, Hoxb5, Hoxc4 and Hoxd3 genes. RESULTS: EA: Upon immunohistochemistry, adriamycin-exposed embryos showed a severe decrease in expression of Hoxa3, Hoxb3 and Hoxb3 proteins in heart, skin, foregut but not in the heart. RT-PCR studies showed a statistically significant decrease of the four genes studied in the lungs of OA mice when compared to controls. CDH: Upon RT-PCR assessment the expression of Hoxa5 and Hoxb3 were higher in nitrofen-exposed mice than in controls on E14 and E19 and weaker on E16. As regards immunohistochemical localization, expression of the three genes was similar in nitrofen and control animals. CONCLUSIONS: Both experimental models exhibit an alteration in the expression of several proximal Hox genes, specially in lung and car- diac tissues. The malformations in these organs associated with CDH and EA could be in part caused by these alterations. Due to their specific participation in lung and foregut morphogenesis, their study could let us to better understand the mechanisms of CDH and EA.

Reconstrucción digital tridimensional para el análisis de las malformaciones intratorácicas congénitas inducidas con nitrofen / Aplication of a ·D reconstruction model for the analysis of nitrofeninduced intrathoracic malformations

Introducción. Los distintos modelos informáticos de reconstrucción tridimensional ofrecen múltiples ventajas a la hora de analizar y comparar diferentes procesos biológicos y estructuras anatómicas. El modelo experimental en roedores de hernia diafragmática congénita (HDC) inducida por nitrofen ocasiona múltiples anomalías en estructuras derivadas de la cresta neural. El objetivo de este trabajo es analizar mediante un método de reconstrucción tridimensional las posibles alteraciones de los nervios vago y recurrente laríngeo en esta malformación. Material y métodos. Se usó el modelo experimental de HDC en ratas. Se estudiaron 9 fetos control y otros 9 con HDC. En cada uno se obtuvo un bloque torácico (desde laringe a la bifurcación traqueal) que fue seccionado seriadamente. Se tiñeron uno de cada 10 cortes y las imágenes resultantes (de 90 a 120 en cada feto) se digitalizaron usando un software biológico específico que permitió la reconstrucción tridimensional (TDR-3dbase®) de las estructuras señaladas (nervios vago y recurrente laríngeo, tráquea, esófago y grandes vasos). Resultados. Se encontraron diferencias en la anatomía nerviosa de los fetos con HDC comparados con los controles: 1) Ausencia de uno de los nervios vagos (4/9). 2) Ausencia de uno de los recurrentes laríngeos (6/9). 3) Hipoplasia evidente de los nervios vagos (2/9). 4) Desviaciones anatómicas groseras del recorrido de los nervios. Conclusiones. La reconstrucción tridimensional permitió un análisis detallado y proporcionó una aproximación real a la anatomía de las malformaciones. Los fetos con HDC presentaron anomalías de los nervios vago y recurrente laríngeo que apoyan la teoría de una alteración en la organogénesis mediada por la cresta neural en el origen de esta enfermedad (AU)

Background. Three dimensional computer-assisted reconstruction offers some adventages for analysis and comparison of biological phenomena and anatomical structures. The CDH nitrofen-induced animal model associates multiple anomalies in neural-crest derived tissues. The goal of this study is to analyse by a 3-D reconstruction software the malformations in the extrinsic innervation of the esophagus in this model. Methods. Nine control fetuses from 4 dams and 9 fetuses with CDH from 7 dams were studied. A thoracic block from the larynx to tracheal bifurcation was serially sectioned in the horizontal plane in every embryo. One in every 10 sections was stained with HE. The image was digitalized using biological software (TDR-3dbase®). Vagus and recurrent laryngeal nerves, trachea, esophagus and the great vessels were examined. In order to obtain the 3-D reconstructions, 90 to 120 consecutive images were used. Results. In comparison with controls there were striking abnormalities of these nerves in fetuses with CDH: 1) Absence of the left (2/9) or right (2/9) vagus nerves. 2) Absence of the left (3/9) or right (3/9) recurrent laryngeal nerves. 3) Marked hypoplasia of the trunk of the vagus (2/9). 4) Deviations of their normal course and change of normal anatomical relationships into the mediastinum (2/9). Conclusions. To fullfill our goals 3-D reconstructions allow a detailed analysis and provide a precise insight into the real anatomy. Rat fetuses with CDH have anomalies of the vagus and recurrent laryngeal nerves that support the concept of a neural crest involvement in the origin of this malformation. These observations may explain esophageal motility disorders in CDH (AU)

Pax3 mRNA is decreased in the hearts of rats with experimental diaphragmatic hernia.

Rats with nitrofen-induced congenital diaphragmatic hernia (CDH) have heart hypoplasia and cardiovascular malformations. The mechanism of action of nitrofen involves changes in neural crest signaling. Pax3 function is required for cardiac neural crest cells to complete their migration to the developing heart. The aim of this study was to examine whether Pa x 3 expression is changed at two gestational endpoints in rat embryos or fetuses exposed to nitrofen. On day E9.5 of gestation, pregnant rats received either 100 mg of nitrofen (n=10) or vehicle alone (control, n=10). The fetuses were recovered on E15 or E21. Their hearts were dissected out and weighed. Pax3 mRNA expression was determined by real-time polymerase chain reaction. We used two-tailed Student's t-tests to compare groups, with a threshold of significance of p<0.05. Compared with controls, nitrofen-exposed fetuses had heart hypoplasia in terms of heart/body weight ratio (0.62+/-0.10% vs. 0.77+/-0.17%, p<0.05). Pax3 mRNA expression in the heart was significantly decreased on E15 in nitrofen-treated embryos (32.94+/-17.11 U vs. 55.09+/-11.56 U, p<0.05), and it was still decreased, although not significantly, in the hearts of nitrofen-exposed fetuses recovered on E21 (15.67+/-5.56 U vs. 20.51+/-5.92 U, not significant). In conclusion, Pax3 is underexpressed in the hearts of nitrofen-exposed embryonal rats before the end of gestation. The mechanism of action of Pax3 should be further investigated because it could be one of the targets for future prenatal transplacental intervention.

[Aplication of a 3D reconstruction model for the analysis of nitrofen induced intrathoracic malformations]. / Reconstrucción digital tridimensional para el análisis de las malformaciones intratorácicas congénitas inducidas con nitrofen.

BACKGROUND: Three dimensional computer-assisted reconstruction offers some adventages for analysis and comparison of biological phenomena and anatomical structures. The CDH nitrofen-induced animal model associates multiple anomalies in neural-crest derived tissues. The goal of this study is to analyse by a 3-D reconstruction software the malformations in the extrinsic innervation of the esophagus in this model. METHODS: Nine control fetuses from 4 dams and 9 fetuses with CDH from 7 dams were studied. A thoracic block from the larynx to tracheal bifurcation was serially sectioned in the horizontal plane in every embryo. One in every 10 sections was stained with HE. The image was digitalized using biological software (TDR-3dbase). Vagus and recurrent laryngeal nerves, trachea, esophagus and the great vessels were examined. In order to obtain the 3-D reconstructions, 90 to 120 consecutive images were used. RESULTS: In comparison with controls there were striking abnormalities of these nerves in fetuses with CDH: 1) Absence of the left (2/9) or right (2/9) vagus nerves. 2) Absence of the left (3/9) or right (3/9) recurrent laryngeal nerves. 3) Marked hypoplasia of the trunk of the vagus (2/9). 4) Deviations of their normal course and change of normal anatomical relationships into the mediastinum (2/9). CONCLUSIONS: To fullfill our goals 3-D reconstructions allow a detailed analysis and provide a precise insight into the real anatomy. Rat fetuses with CDH have anomalies of the vagus and recurrent laryngeal nerves that support the concept of a neural crest involvement in the origin of this malformation. These observations may explain esophageal motility disorders in CDH.