Mucin production and composition is altered in dextran sulfate sodium-induced colitis in rats

We evaluated the small and large intestinal mucin production in a rat model of human ulcerative colitis by measuring the in vivo fractional synthesis rate (FSR) and the expression of mucins. A chronic colitis was induced by oral administration of 5% dextran sulfate sodium (DSS) for 9 days followed by 2% DSS for 18 days. DSS-treated rats showed increased colonic MUC2,3 mRNA levels compared pair-fed controls. The mucin FSR was unaffected while mucin-containing goblet cells were depleted in the vicinity of lesions. In the small intestine, no inflammatory lesions were observed but ileal MUC2 mRNA levels and mucin FSR were decreased by 46% and 21%, respectively. Finally, DSS-treated rats showed a marked decrease in mucin's threonine + serine content all along the gut, which may lead to a reduction of potential O-glycosylation sites. Our data indicate that the chronic colitis may impair the mucus layer protective function all along the gut.