Effects of prenatal dexamethasone on the intestine of rats with gastroschisis.

BACKGROUND/PURPOSE: Intestinal lesions observed in gastroschisis (Gx) are accompanied by neonatal gastrointestinal dysfunction. This study examines the effects of transplacental dexamethasone on the eviscerated intestine of fetal rats with Gx.

METHODS: Gx was created surgically in rat fetuses on gestational day 18, and the dams were treated either with 0.4 mg/kg intraperitoneal dexamethasone or with vehicle only on days 19 and 20. The intestine recovered on day 21 were processed for total DNA and protein. Immuno-histochemical staining for ki-67, TUNEL, and synaptophysin were used for assessing the proportions of proliferating and apoptotic cells and the density of intramural ganglia. Analysis of variance (ANOVA) was used for comparison among groups. Significance level was set at P less than.05.

RESULTS: Body weight was reduced in Gx fetuses in comparison with controls. Intestinal weight per centimeter and mucosal and seromuscular layer thicknesses were increased in Gx and Gx + dexa groups. Total intestinal DNA was diminished in Gx animals but it was near normal in Gx + dexa ones. Total intestinal protein was similar in all groups. DNA and protein per centimeter of bowel were very increased in Gx animals but only slightly in Gx + dexa ones. Proliferating cells were decreased in Gx animals and increased in Gx+dexa ones, whereas the opposite was observed for apoptosis. Density of intramural ganglia was decreased significantly in both Gx groups.

CONCLUSIONS: Late intrauterine exposure to dexamethasone of rat fetuses with Gx decreased wall thickening, normalized total DNA, and induced proliferation in the exposed bowel while limiting apoptosis. This medication could have some yet incompletely defined beneficial effects on the wall of the eviscerated bowel in Gx.