Modifications of the trophism of intestinal mucosa after intestinal and bilio-pancreatic diversion in the rat

Morphofunctional alterations to the intestinal mucosa are influenced by three main factors: food, bilio-pancreatic secretions, intestinal hormones. In order to assess the importance of each one, histological and histochemical tests were performed on different segments of intestine taken from rats which were sacrificed one month after the following procedure: gastrojejunal anastomosis on a Roux loop (Model I); same procedure plus biliopancreatic bypass into the jejunum (Model II). When compared to the controls, Model I duodenum samples revealed hypertrophy of the entire wall with 'bundles' of villi, while Model II samples showed a clear hypotrophy and reduction in the number of duodenal villi. To such modifications of the duodenum correspond longer, thinner villi in the other bowel segments, particularly in the jejunum and distal ileum. These results suggest that the predominant trophic effect derives from contact with biliopancreatic secretions at a proximal level. The modifications of the duodenal mucosa appear to regulate the trophism of the distal segments probably by the secretion of distant acting enterohormones.