EFFECT OF DIETARY FIBER AT WEANING ON PROTEIN GLYCOSYLATION IN THE RAT SMALL-INTESTINE

Changes in protein glycosylation which can be modulated by dietary factors are observed in the rat intestinal mucosa at the weaning period. Experiments were performed to evaluate the involvement of dietary fibers in the regulation of such modifications. Groups of rats were abruptly weaned at 19 days of age on semi-synthetic diets differing in dietary fiber content (fiber-free, 10% pectin or 10% cellulose) given for 4 and 10 days. Glycoprotein sugars, activities of the fucosylation pathway and caecal contents were analyzed. Neutral sugar contents in glycoproteins of the small intestinal mucosa were increased in the fiber-fed groups as compared to fiber-free group, only after 4 days but not after 10 days of diet. Diet-induced modifications in the glycoprotein fucose content of the small intestinal mucosa are partly explained by the coordinated evolution of different activities involved in the fucosylation pathway (GDP-fucose production and breakdown, fucosyltransferase and fucosyltransferase inhibitor). Caecal contents of short chain fatty acids were significantly different between the three groups after 4 but not after 10 days of diet. There was no correlation between caecal short chain fatty acid contents and activities involved in the fucosylation pathway. The introduction of dietary fibers at weaning induced marked but transient changes in glycoprotein sugars and the fucosylation pathway. The results demonstrate that fucosylation is regulated in several ways including changes in fucosyltransferase activity but that caecal fermentation of dietary fibers was not directly responsible for the observed changes.