Gastrosquise experimental em fetos de ratas : avaliação da inflamação intestinal e contratilidade gástrica

Abstract

Introduction: Gastroschisis is a congenital defect of the abdominal wall closure, with herniation of the intestines, getting in contact with amniotic fluid (AF). Structural changes and intestinal dysmotility are well described in animal models of gastroschisis. However, little is known about gastric motility in fetuses with gastroschisis. Objective: To determine the influence of time of exposure of the bowel and efficacy of corticosteroid therapy on morphometric parameters and evaluate the gastric contractility in fetal rats with experimental gastroschisis. Methods: We used the experimental model of gastroschisis in fetal Wistar. To evaluate the exposure time of the bowel to AF on morphometric parameters, two groups of fetuses were studied: fetuses of rats operated at 18.5 and 19.5 days of gestation. To evaluate the efficacy of corticosteroid therapy on morphometric parameters, two groups of fetuses were studied: fetuses of rats operated at 18.5 days of pregnancy with and without dexamethasone treatment. To evaluate the activity of the enzyme myeloperoxidase (MPO) and gastric contractility were studied fetuses of rats operated at 18.5 days of pregnancy without treatment. Each group was composed of subgroups of fetuses undergoing gastroschisis (G), control (C) and sham (Sh). Morphometrics: We evaluated the body mass (BM), mass (IM) and intestinal length (IL). MPO activity: We measured MPO activity in the intestine and stomach. Gastric Contractility: contractility was assessed in segments of background and gastric antrum. Differences between groups and subgroups were tested using ANOVA (p <0.05). Results: Exposure time: no significant difference between the morphometric variables analyzed, comparing the groups with different time of exposure days. Glucocorticoid therapy: maternal treatment with dexamethasone prevented the shortening of intestinal fetuses with gastroschisis. MPO activity: Fetuses with gastroschisis undergoing gastroschisis with 18.5 days showed elevated intestinal MPO activity, and there was no difference in gastric MPO activity between subgroups. Gastric Contractility: At baseline, spontaneous oscillatory contractions of the antrum and fund G, Sh and C were similar. The cumulative concentrations of carbachol (CCh) produced a significant increase in amplitude and frequency of spontaneous contractions and antral smooth muscle tonicity a sustained increase in fundic segments. There was no significant difference in the frequency or amplitude observed in antral tissues. Also, in fundic smooth muscle, no significant difference was observed comparing the contractility of the groups with the curve of CCh induced following a typical sigmoid shape, dependent on increasing concentrations. Conclusions: The time did not interfere in morphometric changes of experimental fetuses with gastroschisis. Steroid therapy was beneficial in reducing morphometric damage in fetuses with experimental gastroschisis. The gastric contractile responses to CCh are preserved in rat fetuses subjected to experimental gastroschisis. These results do not support the theory that gastric dilation can only occur secondary to intestinal inflammation.