Structural and functional studies on the transformation of the intestinal mucosa in rats with experimental diabetes

Twenty days after the onset of alloxan-induced diabetes, a villous hyperplasia has developed in the intestines of rats having free access to food. The transformation is characterised by a considerable increase in the area of the villous surface, caused by an enhanced mitotic activity in the crypts. The absorption of glucose or methionine by jejunal loops, whether expressed in terms of serosal area or villous area, is unchanged at this stage. On the other hand, the specific activity of certain disaccharidases and dipeptidases in crude mucosal homogenates is greater in diabetic animals, but quantitative histochemistry revealed no changes in the activities of alkaline phosphatase, leucine amino-peptidase and non-specific esterase in the individual enterocytes. Thus the biochemical changes may simply reflect the hyperplasia of the mucosa. The blood sugar level does not appear to be directly responsible for the mucosal transformation; however, the positive correlation between the daily food intake and the villus height suggests a role of hyperphagia and consequent increased luminal nutrition in the development of the hyperplasia.