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Neurodevelopmental Reflex Testing in Neonatal Rat Pups
Published on: April 24, 2017
Early dietary antigens delay the development of gut mucosal barrier in preweaning rats
T Arvola1, I Rantala, A Marttinen
1University of Tampere, Department of Clinical Sciences, Finland.
Insights
Early exposure to cow's milk antigens in rat pups delayed gut closure, increasing macromolecule absorption. This suggests antigen insult enhances endocytosis as a host response, impacting gastrointestinal barrier maturation.
Area of Science:
- Gastroenterology
- Immunology
- Pediatric Nutrition
Background:
- The gastrointestinal mucosal barrier is crucial for nutrient absorption and pathogen exclusion.
- Gut closure, a developmental process, typically occurs around 21 days in rats, limiting macromolecule absorption.
- Early life antigen exposure can influence immune system development and gut barrier function.
Purpose of the Study:
- To investigate the impact of early antigen exposure on the maturation of the gastrointestinal mucosal barrier in rat pups.
- To determine if cow's milk or whey protein hydrolysate affects gut closure and intestinal permeability.
- To elucidate the mechanisms underlying changes in gut barrier function following antigen exposure.
Main Methods:
- Rat pups were divided into three groups: cow's milk (CM), whey protein hydrolysate (PH), and controls.
- Experimental feeding occurred from day 14 to 20, with controls receiving only maternal milk.
- Intestinal absorption of horseradish peroxidase (HRP) was measured in vitro using Ussing chambers at day 21.
- Electron microscopy was used to examine epithelial cell and intercellular space morphology.
Main Results:
- Intact HRP absorption was significantly higher in the cow's milk group compared to the whey protein hydrolysate and control groups.
- Absorption of degraded HRP was similar across all groups.
- No significant changes in electrical parameters indicated increased mucosal permeability.
- Electron microscopy revealed HRP accumulation in epithelial cells and intercellular spaces without altering cell junctions in the cow's milk group.
Conclusions:
- Early administration of cow's milk antigens delays the process of gut closure in developing rats.
- Enhanced endocytosis of macromolecules is induced by mucosal insult from antigens, acting as a host response.
- Maternal milk provides some protection, but early antigen exposure can still impact gut barrier maturation.
Abstract:
To determine the effects of early antigen exposure on the maturation of the gastrointestinal mucosal barrier, rat pups were divided into three groups at the age of 14 d. In addition to normal maternal milk, group CM (n = 24) received daily a gavage feed of cow's milk and group PH (n = 20) a whey protein hydrolysate during the experimental feeding period (14-20 d). Controls (n = 15) remained on maternal milk only. At 21 d, when "gut closure" normally occurs, intestinal absorption of horseradish peroxidase (HRP), was examined in vitro in Ussing chambers. The absorption of intact HRP [geometric mean (95% confidence interval)] was significantly higher in group CM [35.3 (16.7, 74.7) ng.h-1.cm-2] than in group PH [5.2 (1.4, 19.5) ng.h-1.cm-2] and in controls [3.4 (0.8, 15.1) ng.h-1.cm-2; F = 5.54, p = 0.006]. The absorption of degraded HRP was comparable in all groups. There were no modifications in electrical parameters in association with increased mucosal permeability to HRP. Furthermore, in group CM electron-microscopic studies disclosed accumulation of HRP in the cytoplasm of the epithelial cells and in the intercellular spaces where cell junctions remained unaltered. These results indicate that early administration of antigens delays the process of gut closure. They further suggest that continuously enhanced endocytosis of macro-molecules is induced by an insult to the mucosa as part of the host response to these antigens, irrespective of the protection afforded by maternal milk.
