Daniel Bittencourt

Maturity of the myenteric plexus is decreased in the gastroschisis rat model.

Background: Amniotic fluid (AF) and its components, such as fetal urine and meconium, may lead to intestinal alterations in gastroschisis, which cause immaturity of the myenteric plexus and consequent intestinal hypomotility and malabsorption. In this study we identified morphological and histological alterations of the intestine and the myenteric plexus with two different times of exposure to AF. Methods: The experimental gastroschisis was achieved at two different gestational ages, on day 18.5 (E18.5) and day 19.5 (E19.5) of gestation, in fetal rats which were divided into 3 subgroups: control, sham and gastroschisis. We measured fetal body weight (BW), intestinal weight (IW) and intestinal length (IL). The layers of intestinal wall and myenteric plexus were evaluated by hematoxylin and eosin staining (HE staining) and immunofluorescence (α-internexin), respectively. Results: BW was not significantly different among the control, sham and gastroschisis groups at both ages. IW and IL were larger and shorter, respectively, in the gastroschisis fetuses (p < 0.001) at both ages. Intestinal diameters and wall layers presented significant differences among control, sham and gastroschisis fetuses at both ages (p < 0.001), but the time of exposure to AF compromised the serous membrane, D-II (diameter II, p < 0.001) and IL (p = 0.001). α-Internexin presented more intensive immunoreactivity in gastroschisis fetuses at E18.5. Conclusions: In gastroschisis, the longer the time of exposure to AF, the more severe bowel impairment will be, especially with regard to IL and the serous layer, and the more immature the myenteric plexus will be.

Inflammatory response in a rat model of gastroschisis is associated with an increase of NF-kappaB.

Babies with gastroschisis have high morbidity, which is associated with inflammatory bowel injury caused by exposure to amniotic fluid. The objective of this study was to identify components of the inflammatory response in the intestine and liver in an experimental model of gastroschisis in rats. The model was surgically created at 18.5 days of gestation. The fetuses were exposed through a hysterotomy and an incision at the right of the umbilicus was made, exposing the fetal bowel. Then, the fetus was placed back into the uterus until term. The bowel in this model had macro- and microscopic characteristics similar to those observed in gastroschisis. The study was conducted on three groups of 20 fetuses each: gastroschisis, control, and sham fetuses. Fetal body, intestine and liver weights and intestine length were measured. IL-1beta, IL-6, IL-10, TNF-alpha, IFN-gamma and NF-kappaB levels were assessed by ELISA. Data were analyzed statistically by ANOVA followed by the Tukey post-test. Gastroschisis fetuses had a decreased intestine length (means +/- SD, 125 +/- 25 vs 216 +/- 13.9; P < 0.005) and increased intestine weight (0.29 +/- 0.05 vs 0.24 +/- 0.04; P < 0.005). Intestine length correlated with liver weight only in gastroschisis fetuses (Pearsons correlation coefficient, r = 0.518, P = 0.019). There were no significant differences in the concentrations of IL-1beta, TNF-alpha or IFN-gamma in the intestine, whereas the concentration of NF-kappaB was increased in both the intestine and liver of fetuses with gastroschisis. These results show that the inflammatory response in the liver and intestine of the rat model of gastroschisis is accompanied by an increase in the amount of NF-kappaB in the intestine and liver.

Aminiotic Fluid and Intrauterine Growth Restriction in a Gastroschisis Fetal Rat Model

Fetuses with digestive anomalies such as gastroschisis may present intrauterine growth restriction (IUGR) and shortened intestines. Objective: The aim of this study was to assess the influence caused by amniotic fluid (AF) in intestinal length and somatic growth in an experimental gastroschisis fetal model at two distinct gestational ages. Material and Method: Fetal rats were operated according to Correia-Pinto on 2 different days of gestation: day 18.5 (group I) and day 19.5 (group II). Each group was divided into three sub-groups: fetuses with gastroschisis (G), control (C) and sham(S). Body measurements and histological analysis were done. Result: Body measurement analysis showed: average body weight (g) in group I was G = 5.32, C = 5.68, S = 5.86; group II was G = 5.32, C = 5.80, S = 5.66. Average intestine weight (g) in group I was G = 0.283, C = 0.238, S = 0.231; group II was G = 0.272, C = 0.231, S = 0.233. Average intestine length (mm) in group I was G = 125, C = 216, S = 209; group II was G = 148, C = 226, S = 226. Histological analysis showed a decrease in the number and size of the intestinal microvillae and a light edema of serosa. Conclusion: Gastroschisis had a direct correlation with IUGR and the time of exposure of the fetuses to AF had no influence on body weight in gastroschisis fetuses but did interfere with intestinal length.

Arnold-Chiari in a Fetal Rat Model of Dysraphism

Dysraphism is a defect in neural tube development, leading to dysplastic growth of the spinal cord and meninges. Myelomeningocele (MM) is just one of its forms. Hydrocephalus is among the most important alterations in MM and occurs as a consequence of Arnold-Chiari malformation (AC). Experimental models have been developed in sheep, rabbits and rats to study MM physiopathology, allowing a more detailed evaluation of clinical parameters involved in this anomaly. Objective: Using the experimental model of dysraphism in fetal rats, the aim of this study was to evaluate the relevance of AC malformations, clinical parameters and grade of histological lesions. Materials and Methods: Three groups with 16 fetuses in each were compared, MM, Control and Sham, after intrauterine surgical creation of MM on day 18.5 of gestation (term = 22 days). AC was evaluated by photographic comparison of sagittal cuts of fetal heads. Clinical and histological evaluations were also made. Results: 88% of AC (14/16) in MM fetuses were obtained, besides 100% of clinical alterations. Necrosis and erosion of the spinal cord exposed to amniotic fluid were verified in histology. Conclusion: The presence of AC in the dysraphism rat model was high. These results allowed the use of this model to study alterations and intrauterine evolution of MM in a fashion similar to those observed in humans.

Corticosteroid effect upon intestinal and hepatic interleukin profile in a gastroschisis rat model

PURPOSE To evaluate the effect of corticosteroids on intestinal and liver interleukin profile in an experimental model of gastroschisis in fetal rats. METHODS Sprague-Dawley rats at 19.5 days of gestation had its fetuses operated for the creation of gastroschisis. Two groups of fetuses were studied with and without maternal administration of dexamethasone. Each group was composed of fetuses who underwent gastroschisis (G), control fetuses without manipulation (C) and sham fetuses (S). A dosage of the following interleukins was carried out in fetal intestinal and liver tissues: IL-1, IL-6, IL-10, tumor necrosis factor-alpha (TNF-α) and interferon-gamma (IFN-γ). The differences between the groups and subgroups were tested by ANOVA with Tukey post-test, with significant values of p<0.05. RESULTS Dexamethasone led to an increase in intestinal and liver IL-6 (p<0.05) and a decrease in intestinal TNF-α (p<0.001) in fetuses with gastroschisis. CONCLUSION Corticosteroids had an effect on the intestinal interleukin profile and a small effect on the liver interleukin profile due to immunological immaturity of the fetus, and also of fetuses with gastroschisis. The steroid action may not be exclusively anti-inflammatory, but also pro-inflammatory, varying with time of pregnancy.