Neonates with intrauterine growth restriction (IUGR) show lower efficiency of nutrient utilization compared to normal birth weight (NBW) newborns. This study was conducted using neonatal piglets as a model to test the hypothesis that IUGR affects the intestinal barrier function, intestinal structure, and antioxidant system development during the suckling period. The small intestinal mucosae were obtained from IUGR and NBW littermates in the suckling period (d 0, 3, 8, and 19 postnatal). The epithelial barrier function was assessed by FITC-dextran 4 (FD4) and horseradish peroxidase (HRP) fluxes across the epithelium, histomorphologic measurements, and expression of tight-junction proteins. Redox status represented by the glutathione disulfide/glutathione ratio and malondialdehyde concentrations was determined, whereas mRNA expressions of some redox-sensitive proteins were quantified. Results showed that IUGR piglets exhibited a 2-fold higher intestinal permeability in the proximal small intestine on d 0 (P < 0.05), and this difference between IUGR and NBW piglets was widened to 3 and 4 times for FD4 and HRP, respectively (P < 0.05), on d 3. In accordance, expression of occludin was down-regulated at the transcriptional level in IUGR piglets at d 0 and 19 (P < 0.01). Furthermore, the transcription of heme oxygenase 1, catalase, and thioredoxin reductase genes was down-regulated in IUGR piglets, mainly on postnatal d 0 and 19 (P < 0.01). It appears that IUGR subjects have a lower capacity to mount an antioxidant response in the early postnatal period. Collectively, these results add to our understanding of the mechanisms responsible for intestinal dysfunction in IUGR neonates.
Keywords: IUGR; antioxidant capacity; intestinal tight junction; occludin.
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