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

Changes in protein glycosylation which can be modulated by dietary fac tors are observed in the rat intestinal mucosa at the weaning period. Experiments were performed to evaluate the involvement of dietary fibe rs in the regulation of such modifications. Groups of rats were abrupt ly weaned at 19 days of age on semi-synthetic diets differing in dieta ry fiber content (fiber-free, 10% pectin or 10% cellulose) given for 4 and 10 days. Glycoprotein sugars, activities of the fucosylation path way and caecal contents were analyzed. Neutral sugar contents in glyco proteins of the small intestinal mucosa were increased in the fiber-fe d groups as compared to fiber-free group, only after 4 days but not af ter 10 days of diet. Diet-induced modifications in the glycoprotein fu cose content of the small intestinal mucosa are partly explained by th e coordinated evolution of different activities involved in the fucosy lation pathway (GDP-fucose production and breakdown, fucosyltransferas e and fucosyltransferase inhibitor). Caecal contents of short chain fa tty acids were significantly different between the three groups after 4 but not after 10 days of diet. There was no correlation between caec al short chain fatty acid contents and activities involved in the fuco sylation pathway. The introduction of dietary fibers at weaning induce d marked but transient changes in glycoprotein sugars and the fucosyla tion pathway. The results demonstrate that fucosylation is regulated i n several ways including changes in fucosyltransferase activity but th at caecal fermentation of dietary fibers was not directly responsible for the observed changes.