Tracheal occlusion and ventilation changes the nitric oxide pathway in congenital diaphragmatic hernia model.

BACKGROUND: Congenital diaphragmatic hernia (CDH) is associated with lung hypoplasia and pulmonary hypertension. Tracheal occlusion (TO) stimulates fetal lung growth and maturation and reverse vascular changes responsible for pulmonary hypertension, which are related to mechanisms involving nitric oxide (NO) in CDH. We aim to evaluate the effect of TO and ventilation on NO pathways. METHODS: Eight groups were created: (1) control; (2) control ventilated (CV); (3) CDH (CDH); (4) CDH ventilated (CDHV); (5) TO control; (6) TO ventilated; (7) TO + CDH; and (8) TO + CDH ventilated (CDHTOV). Fetuses were weighed, and volume ventilated for 30 min after harvested. Total lung weight and the ratio of total lung weight to body weight, thickness of the middle layer of the pulmonary arteriole, and the air space diameter were measured. The NO synthase inducible and NO synthase inducible were performed by immunohistochemistry and Western blotting. RESULTS: The total lung weight and the ratio of total lung weight to body weight decreased in animals with nitrofen and also after ventilation for all groups (P < 0.05). The thickness of the middle layer of the pulmonary arteriole decreased in all groups with TO when compared with controls (P < 0.001). The air space diameter decreased after ventilation in the CDHTOV compared to the TO + nitrofen-induced CDH (P < 0.001). Compared to nonventilated cohorts, NO synthase inducible increased in CV and TO ventilated (P < 0.001) and decreased in CDHV and CDHTOV (P < 0.001). NO synthase inducible increased in CV and CDHV (P < 0.001) and decreased in the TO control and CDHTOV (P < 0.001). CONCLUSIONS: TO and ventilation alter the NO pathway with possible implications in reducing the pulmonary hypertension in CDH.

Temporal profile of intestinal tissue expression of intestinal fatty acid-binding protein in a rat model of necrotizing enterocolitis.

OBJECTIVES: Necrotizing enterocolitis is a severe multifactorial intestinal disorder that primarily affects preterm newborns, causing 20-40% mortality and morbidity. Intestinal fatty acid-binding protein has been reported to be a biomarker for the detection of intestinal injuries. Our aim was to assess intestinal tissue injury and the molecular expression of intestinal fatty acid-binding protein over time in a necrotizing enterocolitis model. METHODS: A total of 144 Newborn rats were divided into two groups: 1) Control, which received breastfeeding (n=72) and 2) Necrotizing Enterocolitis, which received formula feeding and underwent hypoxia and hypothermia (n=72). A total of six time points of ischemia (2 times a day for 3 days; 12 pups for each time point) were examined. Samples were collected for analysis of body weight, morphological and histological characteristics, intestinal weight, intestinal weight/body weight ratio, injury grade, and intestinal fatty acid-binding protein levels. RESULTS: Body and intestinal weights were lower in the Necrotizing Enterocolitis group than in the Control group (p<0.005 and p<0.0005, respectively). The intestinal weight/body weight ratio was higher in the Necrotizing Enterocolitis group than in the Control group (p<0.005) only at the sixth ischemia time point. The Necrotizing Enterocolitis group displayed higher expression of intestinal fatty acid-binding protein (p<0.0005) and showed greater tissue damage than the Control group. CONCLUSION: Intestinal fatty acid-binding protein was an efficient marker of ischemic injury to the intestine and a good correlation was demonstrated between the time of ischemic injury and the grade of intestinal injury.

Temporal profile of intestinal tissue expression of intestinal fatty acid-binding protein in a rat model of necrotizing enterocolitis

OBJECTIVES: Necrotizing enterocolitis is a severe multifactorial intestinal disorder that primarily affects preterm newborns, causing 20-40% mortality and morbidity. Intestinal fatty acid-binding protein has been reported to be a biomarker for the detection of intestinal injuries. Our aim was to assess intestinal tissue injury and the molecular expression of intestinal fatty acid-binding protein over time in a necrotizing enterocolitis model. METHODS: A total of 144 Newborn rats were divided into two groups: 1) Control, which received breastfeeding (n=72) and 2) Necrotizing Enterocolitis, which received formula feeding and underwent hypoxia and hypothermia (n=72). A total of six time points of ischemia (2 times a day for 3 days; 12 pups for each time point) were examined. Samples were collected for analysis of body weight, morphological and histological characteristics, intestinal weight, intestinal weight/body weight ratio, injury grade, and intestinal fatty acid-binding protein levels. RESULTS: Body and intestinal weights were lower in the Necrotizing Enterocolitis group than in the Control group (p<0.005 and p<0.0005, respectively). The intestinal weight/body weight ratio was higher in the Necrotizing Enterocolitis group than in the Control group (p<0.005) only at the sixth ischemia time point. The Necrotizing Enterocolitis group displayed higher expression of intestinal fatty acid-binding protein (p<0.0005) and showed greater tissue damage than the Control group. CONCLUSION: Intestinal fatty acid-binding protein was an efficient marker of ischemic injury to the intestine and a good correlation was demonstrated between the time of ischemic injury and the grade of intestinal injury.

Combined antenatal therapy with retinoic acid and tracheal occlusion in a rat model of congenital diaphragmatic hernia.

AIM: To investigate the effect of combined prenatal treatment with retinoic acid (RA) and tracheal occlusion (TO) on the pulmonary vascular morphology and expression of vascular endothelial growth factors (VEGF) and its receptors in a rat model of congenital diaphragmatic hernia (CDH). MATERIAL AND METHODS: Rats were given nitrofen at 9 days of gestation followed by no treatment (CDH), RA (CDH + RA), TO (CDH + TO), or both (CDH + RA + TO) (n = 16). We measured the median wall thickness of the pulmonary arterioles (MWT) and analyzed the expression of VEGF and its receptors (VEGFR1 and VEGFR2). RESULTS: Compared to control animals, CDH had increased MWT (44 ± 15 vs. 58 ± 7; p < 0.05) and decreased expression of VEGF, VEGFR1, and VEGFR2 (p < 0.05). Treatment with RA or TO alone, and RA + TO reduced the MWT (46 ± 9, 42 ± 11, 46 ± 8, respectively) and improved the expression of VEGF, VEGFR1, and VEGFR2 compared to CDH (p < 0.05). However, the combination of RA + TO did not confer additional benefit in the reduction of the MWT or in increasing the VEGF and its receptors compared to either treatment alone. CONCLUSION: Antenatal treatment with either RA or TO improved the MWT and expression of VEGF and its receptors in a CDH rat model. However, combined treatment with RA + TO was not superior to either treatment alone.

Evaluation of the expression of I-FABP and L-FABP in a necrotizing enterocolitis model after the use of Lactobacillus acidophilus.

BACKGROUND/PURPOSE: Necrotizing enterocolitis (NEC) is a severe intestinal disease that primarily affects premature babies, leading to high mortality and morbidity. Probiotics represent an important alternative prophylaxis for NEC but its mechanism of action is poorly understood. Moreover, intestinal and liver-type fatty acid-binding proteins (I-FABP and L-FABP) may be utilized because markers of intestinal injury, including NEC. We aimed to evaluate the protection induced by the Lactobacillus acidophilus on the intestines of newborn rats submitted to experimental NEC using I-FABP and L-FABP as biomarkers. METHODS: Sprague-Dawley newborn rats were divided into three groups: (1) C (control)-breast-fed; (2) NEC-subjected to NEC protocol and (3) NECP-NEC+probiotic. Morphometric, intestinal lesion, immunohistochemistry and Western blotting analysis were performed. Statistical significant differences were considered when p<0.05. RESULTS: Intestinal weight was lower in NEC and NECP compared to C (p<0.05). Intestinal injury was lower in NECP compared to NEC. Prophylactic probiotic recovered mucosa and muscular layers' thickness to C levels (p<0.05). I-FABP and L-FABP expressions in NECP showed intermediate values between C and NEC. CONCLUSION: L. acidophilus had a protective effect on the development of NEC and FABPs could demonstrate the degree of tissular damage of the intestine.

Ventilation causes pulmonary vascular dilation and modulates the NOS and VEGF pathway on newborn rats with CDH.

BACKGROUND/PURPOSE: Congenital diaphragmatic hernia (CDH) is a defect that presents high mortality because of pulmonary hypoplasia and hypertension. Mechanical ventilation changes signaling pathways, such as nitric oxide and VEGF in the pulmonary arterioles. We investigated the production of NOS2 and NOS3 and expression of VEGF and its receptors after ventilation in rat fetuses with CDH. METHODS: CDH was induced by Nitrofen. The fetuses were divided into 6 groups: 1) control (C); 2) control ventilated (CV); 3) exposed to nitrofen (N-); 4) exposed to nitrofen ventilated (N-V), 5) CDH and 6) CDH ventilated (CDHV). Fetuses were harvested and ventilated. We assessed body weight (BW), total lung weight (TLW), TLW/BW ratio, the median pulmonary arteriolar wall thickness (MWT). We analyzed the expression of NOS2, NOS3, VEGF and its receptors by immunohistochemistry and Western blotting. RESULTS: BW, TLW, and TLW/BW ratio were greater on C than on N- and CDH (p<0.05). The MWT was higher in CDH than in CDHV (p<0.001). CDHV showed increased expression of NOS3 (p<0.05) and VEGFR1 (p<0.05), but decreased expression of NOS2 (p<0.05) and VEGFR2 (p<0.001) compared to CDH. CONCLUSION: Ventilation caused pulmonary vasodilation and changed the expression of NOS and VEGF receptors.

Effect of corticosteroids and lung ventilation in the VEGF and NO pathways in congenital diaphragmatic hernia in rats.

PURPOSE: The use of dexamethasone (Dx) stimulates growth, fetal lung maturation and can improve pulmonary hypertension in congenital diaphragmatic hernia (CDH). Our aim was to evaluate the effect of Dx on the lung after fetal pulmonary ventilation in the CDH rat model. METHODS: Some groups underwent prenatal treatment with dexamethasone (0.4 mg/kg) that was given at 18.5 gestational day (GD). Sprague-Dawley rat fetuses were divided into groups: control (C); ventilated control (CV); control exposed to dexamethasone (CDx); ventilated control exposed to dexamethasone (CVDx); congenital diaphragmatic hernia (CDH), ventilated CDH (CDHV), CDH exposed to dexamethasone (CDHDx) and ventilated CDH exposed to dexamethasone (CDHVDx). At 21.5 GD fetuses were delivered by C-section, weighed and ventilated for 30 min. We analyzed the lung morphometry by Masson's Trichrome stain, and VEGF, VEGFR1, VEGFR2 and NOS3 expression by immunohistochemistry. RESULTS: All fetuses with CDH, with or without prenatal dexamethasone showed lung and body weight lower than control fetuses (p < 0.05). All groups that received dexamethasone showed a decrease in the medial muscular layer of arterioles, the internal diameter of the air spaces (Lma) and length of parenchymal transection/airspace ratio (p < 0.05). In the immunohistochemistry, VEGF decreased more in CDHDV group (p < 0.05). VEGFR1 showed no difference, whereas VEGFR2 decreased significantly in the CDHDV group (p < 0.05). NOS3 increased in the group CDHDV (p < 0.05). CONCLUSION: The use of prenatal dexamethasone added to ventilation alters the VEGF and NO pathways.

L-FABP and I-FABP expression in newborn rats changes inversely in the model of necrotizing enterocolitis.

PURPOSE: To determine the expression of hepatic L-FABP and intestinal I-FABP in an experimental model of necrotizing enterocolitis (NEC) in neonatal rats. METHODS: Newborn Sprague-Dawley rats were divided into four groups: Control (C1) - exclusive breastfeeding at the first and sixth procedures (C6), NEC1 - fed formula milk and submitted to hypoxia and hypothermia at the first and sixth procedures (NEC6). The newborn pups were fed twice a day for three days, for a total of six procedures. Samples were collected for morphometric evaluation (body weight, liver weight, liver weight/body weight ratio, intestinal weight and intestinal/body weight ratio) and for immunohistochemical and Western blotting analysis. The values obtained were analyzed statistically, with the level of significance set at p<0.05. RESULTS: Morphometric measurements showed reduction of body and liver weights in the NEC group (p<0.05). Both immunohistochemistry and western blotting revealed that L-FABP expression in the liver was decreased and I-FABP expression in the ileum was increased in the NEC group (p<0.05). CONCLUSION: L-FABP and I-FABP expression changed inversely in the rat NEC model. These findings can contribute to a better diagnosis of NEC in human newborns.

Standardization of pulmonary ventilation technique using volume-controlled ventilators in rats with congenital diaphragmatic hernia.

OBJECTIVE: To standardize a technique for ventilating rat fetuses with Congenital Diaphragmatic Hernia (CDH) using a volume-controlled ventilator. METHODS: Pregnant rats were divided into the following groups: a) control (C); b) exposed to nitrofen with CDH (CDH); and c) exposed to nitrofen without CDH (N-). Fetuses of the three groups were randomly divided into the subgroups ventilated (V) and non-ventilated (N-V). Fetuses were collected on day 21.5 of gestation, weighed and ventilated for 30 minutes using a volume-controlled ventilator. Then the lungs were collected for histological study. We evaluated: body weight (BW), total lung weight (TLW), left lung weight (LLW), ratios TLW / BW and LLW / BW, morphological histology of the airways and causes of failures of ventilation. RESULTS: BW, TLW, LLW, TLW / BW and LLW / BW were higher in C compared with N- (p <0.05) and CDH (p <0.05), but no differences were found between the subgroups V and N-V (p> 0.05). The morphology of the pulmonary airways showed hypoplasia in groups N- and CDH, with no difference between V and N-V (p <0.05). The C and N- groups could be successfully ventilated using a tidal volume of 75 ìl, but the failure of ventilation in the CDH group decreased only when ventilated with 50 ìl. CONCLUSION: Volume ventilation is possible in rats with CDH for a short period and does not alter fetal or lung morphology.

Standardization of pulmonary ventilation technique using volume-controlled ventilators in rats with congenital diaphragmatic hernia / Padronização da técnica de ventilação pulmonar utilizando ventiladores com volume controlado em ratos com hérnia diafragmática congênita

OBJECTIVE: To standardize a technique for ventilating rat fetuses with Congenital Diaphragmatic Hernia (CDH) using a volume-controlled ventilator. METHODS: Pregnant rats were divided into the following groups: a) control (C); b) exposed to nitrofen with CDH (CDH); and c) exposed to nitrofen without CDH (N-). Fetuses of the three groups were randomly divided into the subgroups ventilated (V) and non-ventilated (N-V). Fetuses were collected on day 21.5 of gestation, weighed and ventilated for 30 minutes using a volume-controlled ventilator. Then the lungs were collected for histological study. We evaluated: body weight (BW), total lung weight (TLW), left lung weight (LLW), ratios TLW / BW and LLW / BW, morphological histology of the airways and causes of failures of ventilation. RESULTS: BW, TLW, LLW, TLW / BW and LLW / BW were higher in C compared with N- (p <0.05) and CDH (p <0.05), but no differences were found between the subgroups V and N-V (p> 0.05). The morphology of the pulmonary airways showed hypoplasia in groups N- and CDH, with no difference between V and N-V (p <0.05). The C and N- groups could be successfully ventilated using a tidal volume of 75 ìl, but the failure of ventilation in the CDH group decreased only when ventilated with 50 ìl. CONCLUSION: Volume ventilation is possible in rats with CDH for a short period and does not alter fetal or lung morphology. .

OBJETIVO: padronizar uma técnica para ventilar fetos de rato com HDC usando um ventilador volume-controlado. MÉTODOS: ratas grávidas foram distribuídas em: a) Controle (C); e b) Expostos a Nitrofen com HDC e sem HDC (N-). Fetos dos três grupos foram divididos aleatoriamente em subgrupos ventilados (V) ou não ventilados (NV). Os fetos foram coletados no dia 21,5 da gestação, pesados e ventilados por 30 minutos usando um ventilador volume-controlado. A seguir os pulmões foram coletados para estudo histológico. Nós avaliamos: peso corporal (PC), peso pulmonar total (PPT), peso do pulmão esquerdo (PPE), razão PPT/PC e PPE/PC, histologia morfológica das vias aéreas e as causas das falhas da ventilação. RESULTADOS: PC, PPT, PPE, LLW, PPT/PC e PPE/PC foram maiores em C em relação a N- (p<0,05) e a HDC (p<0,05), mas não houve diferenças entre os subgrupos V e NV (p>0,05). A morfologia das vias aéreas pulmonares mostrou hipoplasia nos grupos N- e HDC, não havendo diferença entre V e NV (p<0,05). Os grupos C e N- puderam ser ventilados com sucesso usando o volume corrente de 75ìl, mas a falha de ventilação no grupo HDC só diminuiu quando ventilados com 50ìl. . CONCLUSÃO: a ventilação a volume de ratos com HDC por um curto período é possível e não altera a morfologia fetal ou pulmonar. .

L-FABP and I-FABP expression in newborn rats changes inversely in the model of necrotizing enterocolitis

PURPOSE: To determine the expression of hepatic L-FABP and intestinal I-FABP in an experimental model of necrotizing enterocolitis (NEC) in neonatal rats. METHODS: Newborn Sprague-Dawley rats were divided into four groups: Control (C1) - exclusive breastfeeding at the first and sixth procedures (C6), NEC1 - fed formula milk and submitted to hypoxia and hypothermia at the first and sixth procedures (NEC6). The newborn pups were fed twice a day for three days, for a total of six procedures. Samples were collected for morphometric evaluation (body weight, liver weight, liver weight/body weight ratio, intestinal weight and intestinal/body weight ratio) and for immunohistochemical and Western blotting analysis. The values obtained were analyzed statistically, with the level of significance set at p<0.05. RESULTS: Morphometric measurements showed reduction of body and liver weights in the NEC group (p<0.05). Both immunohistochemistry and western blotting revealed that L-FABP expression in the liver was decreased and I-FABP expression in the ileum was increased in the NEC group (p<0.05). CONCLUSION: L-FABP and I-FABP expression changed inversely in the rat NEC model. These findings can contribute to a better diagnosis of NEC in human newborns. .

The role of gut-liver axis in the restriction of intrauterine growth in a model of experimental gastroschisis.

PURPOSE: To evaluate the intrauterine growth restriction (IUGR) by the expression of IR-ß, IRS-1, IRS-2, IGF-IRß and Ikappaß in experimental model of gastroschisis. METHODS: Pregnant rats at 18.5 days of gestation were submitted to surgery to create experimental fetal gastroschisis (term = 22 days) were divided in three groups: gastroschisis (G), control (C) and sham (S). Fetuses were evaluated for body weight (BW), intestinal (IW), liver (LW) and their relations IW/BW and LW/BW. IR-ß and IGF-IRß receptors, IRS-1 and IRS-2 substrates and Ikappaß protein were analyzed by western blotting. RESULTS: BW was lower in G, the IW and IW / BW were greater than C and S (p<0.05) groups. The liver showed no differences between groups. In fetuses with gastroschisis, compared with control fetuses, the expression of IGF-IRß (p<0.001) and Ikappaß (p<0.001) increased in the liver and intestine, as well as IR-ß (p<0.001) which decreased in both. In contrast to the intestine, IRS-1 (p<0.001) increased in the liver and IRS-2 decreased (p<0.01). CONCLUSION: The axis of the intestine liver has an important role in inflammation, with consequent changes in the metabolic pathway of glucose can contribute to the IUGR in fetuses with gastroschisis.

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.

Effect of nitrofen in the final stages of development of the diaphragm muscle in rats.

PURPOSE: To evaluate the expression of myosin in muscle fibers of the diaphragm in experimental congenital diaphragmatic hernia (CDH). METHODS: Fetuses of pregnant rats were divided into four groups: External Control (EC), composed of non-manipulated rats; Nitrofen, composed of pregnant rats that received 100 mg of nitrofen (2,4-dichloro-4'nitrodiphenyl ether) diluted in olive oil on gestational day (GD) 9.5, whose fetuses developed CDH (N+) or not (N-), and Olive Oil Placebo (OO), composed of pregnant rats that received the oil on the same GD. The fetuses were collected on GD 18.5, 19.5, 20.5 and 21.5 (term = 22 days). We obtained body weight (BW) and photographed the diaphragm area (DA), hernia area (HA) and subsequent calculated the HA/DA ratio in N+ group. Samples of Diaphragm muscle were processed for histological staining with H/E and immunohistochemistry (IHQ) for myosin. RESULTS: The fetuses of N- and N+ groups had decreased BW and DA compared to EC and OO groups (p < 0.001). HA was decreased on GD 18.5 compared to 21.5 (p < 0.001) and the HA/DA ratio showed no difference. IHQ showed decreased expression of myosin in nitrofen groups. CONCLUSION: CDH induced by nitrofen model contributes to the understanding of muscularization in the formation of the diaphragm where the myosin expression is decreased.

Validation of protocol of experimental necrotizing enterocolitis in rats and the pitfalls during the procedure.

PURPOSE: To describe the difficulties of implementing the protocol of experimental necrotizing enterocolitis (NEC) in order to obtain a larger number of newborns affected with the disease and a lower mortality. METHODS: Term Sprague-Dawley newborns rats (22 days) were divided into four groups of 12 fetuses each (n = 48): EC--breastfed newborns; IH--breastfed newborns and subjected to a stress protocol by ischemia and hypothermia; ESB--formula-fed newborns (Esbilac®, PetAg, Hampshire, IL, USA) and NEC--formula-fed newborns and subjected to stress protocol. The parameters set for the study protocol were: milk concentration (0.19 g ml or 0.34 g/ml), diet instilled volume (according to body weight--200 kcal/day/Kg--or progressive, according to acceptance), weight (gain, loss or maintenance) and duration of the experiment (72 hours or 96 hours). Data of body weight (BW), intestinal weight (IW) and the IW/BW ratio were obtained. Samples of terminal ileum were collected and analyzed by the degree of injury to the intestinal wall. Statistically significance was set to p<0.05. RESULTS: The established protocol with less mortality and increased number of NEC was with Esbilac® at a concentration of 0.19 g/ml of diet instilled volume of 0.1 ml, every 3 hours, for 72 hours. All infants fed with artificial milk lost weight. In the degree score of intestinal injury, the ESB, IH and NEC groups were considered positive for NEC with greater histological injury in the latter. CONCLUSION: The described NEC protocol in rats allowed a greater survival of puppies with a greater number of animals affected by the disease.

Evaluation of histological changes after tracheal occlusion at different gestational ages in a fetal rat model.

OBJECTIVES: To evaluate the histological changes of tracheal cartilage and epithelium caused by tracheal occlusion at different gestational ages in a fetal rat model. METHODS: Rat fetuses were divided into two groups: a) External control, composed of non-operated rats, and b) Interventional group, composed of rats operated upon on gestational day 18.5 (term = 22 days), divided into triads: 1) Tracheal occlusion, 2) Internal control and 3) Sham (manipulated but not operated). Morphological data for body weight, total lung weight and total lung weight/body weight ratio were collected and measured on gestational days 19.5, 20.5 and 21.5. Tracheal samples were histologically processed, and epithelial, chondral and total tracheal thicknesses were measured on each gestational day. RESULTS: The tracheal occlusion group exhibited an increase in total lung weight/body weight ratio (p<0.001). Histologically, this group had a thicker epithelial thickness (p<0.05) and thinner chondral (p<0.05) and total tracheal thicknesses (p<0.001). These differences were more prominent on gestational days 20.5 and 21.5. CONCLUSION: Tracheal occlusion changed tracheal morphology, increased epithelial thickness and considerably decreased total tracheal thickness. These changes in the tracheal wall could explain the development of tracheomegaly, recently reported in some human fetuses subjected to tracheal occlusion.

Evaluation of histological changes after tracheal occlusion at different gestational ages in a fetal rat model

OBJECTIVES: To evaluate the histological changes of tracheal cartilage and epithelium caused by tracheal occlusion at different gestational ages in a fetal rat model. METHODS: Rat fetuses were divided into two groups: a) External control, composed of non-operated rats, and b) Interventional group, composed of rats operated upon on gestational day 18.5 (term = 22 days), divided into triads: 1) Tracheal occlusion, 2) Internal control and 3) Sham (manipulated but not operated). Morphological data for body weight, total lung weight and total lung weight/body weight ratio were collected and measured on gestational days 19.5, 20.5 and 21.5. Tracheal samples were histologically processed, and epithelial, chondral and total tracheal thicknesses were measured on each gestational day. RESULTS: The tracheal occlusion group exhibited an increase in total lung weight/body weight ratio (p<0.001). Histologically, this group had a thicker epithelial thickness (p<0.05) and thinner chondral (p<0.05) and total tracheal thicknesses (p<0.001). These differences were more prominent on gestational days 20.5 and 21.5. CONCLUSION: Tracheal occlusion changed tracheal morphology, increased epithelial thickness and considerably decreased total tracheal thickness. These changes in the tracheal wall could explain the development of tracheomegaly, recently reported in some human fetuses subjected to tracheal occlusion.

Increased contractility and impaired relaxation of the left pulmonary artery in a rabbit model of congenital diaphragmatic hernia.

PURPOSE: Congenital diaphragmatic hernia (CDH) is associated with pulmonary hypertension which is often difficult to manage and a significant cause of morbidity and mortality. Our aim was to study the pulmonary artery reactivity in an animal model of CDH. METHODS: To investigate the reactivity of the aorta and left pulmonary artery in a rabbit model of CDH, we studied the in vitro responses to the α1-adrenoceptor agonist phenylephrine (PE) and to both the muscarinic receptor agonist (ACh) and the nitric oxide (NO) donor sodium nitroprusside (SNP). Rabbits underwent surgery at 25 days of gestation. CDH was created in one fetus per horn (n = 8). Remaining fetuses were considered controls (n = 18). At term (30 days), the lung, left pulmonary artery, and aorta were dissected. In a separate group, endothelium was mechanically removed. RESULTS: There were no differences in the contractile and relaxing responses of aorta in all groups. In left pulmonary artery, PE-induced contractions were significantly greater (p < 0.05) in CDH when compared with control group. The increased responsiveness to PE in CDH group was similar to that found in pulmonary artery without endothelium. The ACh-induced pulmonary artery relaxation was markedly reduced in CDH when compared with control group (p < 0.05), whereas no differences were found for SNP. CONCLUSION: Our results show increased contractility and impairment in endothelium-dependent relaxation of pulmonary artery in CDH, mimicking an endothelial dysfunction, with preserved response to endothelium-independent mechanism.

The role of gut-liver axis in the restriction of intrauterine growth in a model of experimental gastroschisis / O papel do eixo intestino-fígado na restrição de crescimento intra-uterino em um modelo de gastrosquise experimental

PURPOSE: To evaluate the intrauterine growth restriction (IUGR) by the expression of IR-β, IRS-1, IRS-2, IGF-IRβ and Ikappaβ in experimental model of gastroschisis. METHODS: Pregnant rats at 18.5 days of gestation were submitted to surgery to create experimental fetal gastroschisis (term = 22 days) were divided in three groups: gastroschisis (G), control (C) and sham (S). Fetuses were evaluated for body weight (BW), intestinal (IW), liver (LW) and their relations IW/BW and LW/BW. IR-β and IGF-IRβ receptors, IRS-1 and IRS-2 substrates and Ikappaβ protein were analyzed by western blotting. RESULTS: BW was lower in G, the IW and IW / BW were greater than C and S (p<0.05) groups. The liver showed no differences between groups. In fetuses with gastroschisis, compared with control fetuses, the expression of IGF-IRβ (p<0.001) and Ikappaβ (p<0.001) increased in the liver and intestine, as well as IR-β (p<0.001) which decreased in both. In contrast to the intestine, IRS-1 (p<0.001) increased in the liver and IRS-2 decreased (p<0.01). CONCLUSION: The axis of the intestine liver has an important role in inflammation, with consequent changes in the metabolic pathway of glucose can contribute to the IUGR in fetuses with gastroschisis.

OBJETIVO: Avaliar a restrição de crescimento intra-uterino (RCIU) pela expressão de IR-β, IRS-1, IRS-2, IGF-IRβ e a via inflamatória do Ikappaβ no modelo de gastrosquise experimental. MÉTODOS: Ratas grávidas com 18,5 dias de gestação foram submetidas a cirurgia experimental para criar gastrosquise fetal (termo = 22 dias) e os fetos foram divididos em três grupos: gastrosquise (G), controle (C) e sham (S). Os fetos foram avaliados quanto ao peso corporal (BW), intestinal (IW), fígado (LW) e suas relações IW/BW e LW/BW. Os receptores IR-β e IGF-IRβ, os substratos IRS-1 e IRS-2 e a proteína Ikappaβ foram analisados por western blotting. RESULTADOS: O BW de G foi menor, o IW e IW/BW foram superiores a C e S (p < 0.05). O fígado não apresentou diferenças entre os grupos. Nos fetos com gastrosquise, quando comparados com fetos controles, a expressão de IGF-IRβ (p<0.001) e Ikappaβ (p<0.001) aumentou no fígado e intestino, assim como IR-β (p<0.001) que diminuiu em ambos. Inversamente ao intestino, IRS-1 (p<0.001) aumentou no fígado e IRS-2 diminuiu (p<0.01). CONCLUSÃO: O eixo do intestino fígado tem um papel importante na inflamação, com consequentes alterações na via metabólica de glicose que pode contribuir para a RCIU em fetos com gastrosquise.

Corticosteroid effect upon intestinal and hepatic interleukin profile in a gastroschisis rat model / Efeito do corticoesteróide sobre o perfil das interleucinas intestinais e hepáticas no modelo de gastrosquise em ratos

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.

OBJETIVO: Avaliar a ação do corticosteroide no perfil de interleucinas intestinais e hepáticas no modelo experimental de gastrosquise em fetos de ratos. MÉTODOS: Ratas Sprague-Dawley com 19,5 dias de gestação tiveram fetos operados para criação de gastrosquise. Dois grupos de fetos foram estudados: com e sem administração materna de dexametasona. Cada grupo foi composto por fetos submetidos a gastrosquise (G), fetos controles sem manipulação (C) e fetos sham (S). Realizou-se a dosagem das seguintes interleucinas no tecido intestinal e hepático fetal: IL-1, IL-6, IL-10, fator de necrose tumoral-alfa (TNF-α) e interferon-gama (IFN-γ). As diferenças entre os grupos e subgrupos foram testadas pelo teste de ANOVA com pós-teste de Tukey, com valores significativos de p<0,05. RESULTADOS: A dexametasona levou a um aumento da IL-6 intestinal e hepática (p<0,05) e a uma diminuição do TNF-α intestinal (p<0,001) em fetos com gastrosquise. CONCLUSÃO: O corticosteróide apresentou efeito sobre o perfil de IL intestinal e pouco na hepática, devido a imaturidade imunológica dos fetos e também dos fetos com gastrosquise a ação do esteróide pode não ser exclusivamente anti-inflamatória, mas também pró inflamatória.