Morphological changes in the small intestine following jejuno-ileal shunt in parenterally fed rats

In order to study the importance of the presence of food in the intestinal lumen during the process of adaptation occurring after diminished absorptive surface, four groups of rats were operated upon. In two experimental groups a jejuno-ileal bypass was created, which excluded about 85% of the small intestine. The two control groups underwent laparotomy and suture-marking of the intestine. One experimental and one control group received standard oral nutrition. The other two groups were solely nourished by total parenteral nutrition (TPN). Two weeks after operation the animals were sacrificed; intestinal wet and dry weight per 3 cm and villus height were determined from five small intestinal segments. The functioning part of the small intestine of the shunt-operated animals was hypertrophic in both the orally fed and the TPN groups as compared with the sham-operated controls with the corresponding nutrition. The hypertrophy comprised significant changes of wet and dry weight and villus height. These values were, however, more increased in the orally fed animals, expressed in absolute figures. The percentual increase of villus height was greater in the TPN animals. The experiments demonstrated that rats with adequate parenteral nutrition two weeks after 85% small intestinal bypass operation develop hypertrophic changes of the intestinal mucosa. This indicates the existence of a non-food-dependent mechanism in the development of adaptive mucosa changes, nevertheless the presence of food seems to stimulate quantitatively higher changes. The presence of food is also of importance for maintaining the intestinal mass.