Structural and functional alterations in the gut of parenterally or enterally fed rats

Various regimens of total parenteral nutrition (TPN) and enteral feeding were compared to determine their effects on the structural and functional changes of rat small intestine. Male Wistar rats, allocated randomly into five groups on the basis of delivery route and composition of nutrients, were fed as follows: standard rat chow ad libitum (CE-2 group), low-residue diet (LRD group), LRD supplemented with 1% (w/v) fiber (LRD + fiber group), elemental diet (ED group), and TPN (TPN group). At 2 weeks of feeding, villi in the terminal ileum decreased in height in the following order: CE-2 group greater than LRD + fiber group greater than LRD group greater than ED group greater than TPN group. Mucosal diamine oxidase activity remained unchanged in the CE-2 group and LRD + fiber group throughout the experimental period. However, mucosal diamine oxidase values were significantly lower in the remaining three groups, similar to the structural changes, and those values in the ED group were significantly decreased at 2, 3, and 4 weeks. There was a positive correlation between plasma diamine oxidase level and mucosal diamine oxidase content, with a coefficient correlation of y = 0.20x + 0.03, r = 0.55 (P less than 0.01). These results could be interpreted to indicate that addition of dietary fiber to LRD has a favorable effect on the maintenance of intestinal architecture and function during enteral feeding, and plasma diamine oxidase activity can be used as an index of functional and/or structural changes occurring in the small intestine during enteral or parenteral feedings.