The influence of a chemical diet on the intestinal mucosa after jejuno-ileal bypass in the rat.

Loss of functioning small intestine (by resection or bypass) is followed by adaptive hypertrophic changes in the remaining functioning part of the small bowel. These changes are usually referred to as "compensatory". The mechanism behind these changes is unknown. In order to clarify the importance of a chemically defined diet (Vivasorb) on the development of the hypertrophic changes, rats operated upon with jejuno-ileal bypass, excluding about 85% of the small intestine, were divided into two groups. One group was nourished with standard pellet food and the other with Vivasorb. Control animals with simple laparotomy were also divided into the corresponding two dietary groups. After 2 weeks, wet and dry weight per 3 cm intestine and villus height was determined. In both diet groups the result was hypertrophy of the functioning part of the small intestine and atrophy of the blind loop with significantly cahnged villus heights as compared with controls on the same diet. The results indicate that a chemically defined, virtually bulk-free diet is capable of stimulating the mucosa of the small intestine to develop compensatory adaptive changes in the rat.