AbstractsBiology & Animal Science

Protein synthesis and gastrointestinal pathophysiology in a piglet model of colitis: importance of nutrition and probiotics

by Scott Vincent Harding




Institution: McGill University
Department: School of Dietetics and Human Nutrition
Degree: PhD
Year: 2007
Keywords: Health Sciences - Nutrition
Record ID: 1793354
Full text PDF: http://digitool.library.mcgill.ca/thesisfile18281.pdf


Abstract

THESIS ABSTRACT Objectives. Adequate nutrition and probiotics have both been shown to reduce the severity of colitis but their impact on hepatic and gastrointestinal protein metabolism has not been studied. Our primary objective was to compare the independent effect of probiotics vs. providing adequate nutrition on protein synthesis in a macronutrient-restricted piglet model of colitis. The secondary outcomes of this study were to determine histological contrasts and changes in oxidative stress markers resulting from probiotics in the malnourished state or providing adequate nutrition. Finally, we also measured mass balance and plasma concentrations of copper, iron and zinc over 5 days of colitis to determine how trace element nutrition is impacted by both colitis and probiotics. Design and Analysis. Twenty-four piglets, receiving 1g•kg-1•d-1 dextran sulphate (DS), were randomized to receive a 50% macronutrient restricted diet without (MR) and with probiotics (MR+PRO) or a diet providing 100% NRC requirements for growing piglets (WN). Eight other piglets were randomized into a well-nourished group without colitis (REF) for histological and trace element comparisons. A primed constant infusion of the tracer L-[ring-2H5]phenylalanine was performed to determine the protein synthesis in small intestinal mucosa, colon, liver and of plasma proteins. Standard, in situ and immunohistological staining techniques were used for histological assessment and the ferric reducing antioxidant power assay, ELISA F2-isoprostane assay and plasma copper:zinc ratio were used as oxidative stress markers. Results. Providing adequate nutrition increased protein synthesis in colon, liver and plasma albumin pool and decreased colitis severity. Probiotics stimulated protein synthesis in the liver as well as synthesis of all liver-derived plasma proteins, without affecting GI protein synthesis. Iron and zinc appear to be affected by both colitis and colitis with superimposed Objectifs La bonne nutrition et les probiotiques ont prouvé réduire la sévérité de la colite. Cependant, leur impact sur le métabolisme des protéines gastro-intestinales et hépatiques n’a pas encore été étudié. Notre objectif premier était de comparer l’effet indépendant des probiotiques à celui d’un régime alimentaire adéquat, sur la synthèse des protéines, chez le porcelet présentant une colite, recevant une diète restreinte en macronutriments. Le but secondaire de cette étude était de déterminer les contrastes histologiques ainsi que les variations au niveau des marqueurs du stress oxydatif, résultant de l’effet des probiotiques dans les deux cas de malnutrition et de nutrition adéquate. Nous avons aussi mesuré l’équilibre et les concentrations de cuivre, fer et zinc dans le plasma durant les 5 jours de colite, dans le but de déterminer comment les probiotiques et la colite affectent tous deux la balance des oligo-éléments. Méthodes et analyses Vingt-quatre porcelets, recevant 1g/kg/jour de sulphate de dextran (DS), ont été randomisés en quatre groupes :…