Effect of Fat Supplementation on the Maintenance of Gut Integrity in Elemental Diet-Fed Rats

Abstract

The aims of this study were to investigate the mechanism of atrophic change in ileal mucosa supplied with an elemental diet (ED) and to assess the value of supplemented fat emulsion in the prevention of atrophic change. In experiment 1, 25 male Wistar rats with a body weight of 160-180 g were divided into 3 groups. The first group was fed regular rat chow (Control group, n=5). The second group was given ED containing 0.6% long-chain triglycerides (ED group, n=10). The third group was provided with fat-enriched ED (FED) containing 3.5% long-chain triglycerides (FED group, n=10). Each group received an isocaloric diet (300 kcal/kg/day). 4 weeks later, after euthanization, ileal samples were taken for light and electron microscopic examinations. The morphological changes of the intestinal mucosa and the crypt cell proliferation rate (CCPR) were determined. In experiment 2, to determine the site of fat absorption, 9 rats were fed ED for 1 week. After 24 h of food deprivation, all rats were given 2 ml of FED through a gastric tube. Then 1, 2, and 3 h(s) later, groups of 3 rats each were euthanized, and the total small intestine was obtained from each rat. The proximal and distal jejunum and distal ileum were stained with oil red O. In experiment 1, the samples had almost the same morphological appearance irrespective of the type of feeding. The CCPR was significantly diminished in the ED group compared with the Control group, while there was no statistical difference between the FED and Control groups. In experiment 2, the oil red O stain was positive in the proximal and distal jejunum, but was completely negative in the distal ileum. The introduction of ED does not soon result in an atrophic morphological change of the ileum but will decrease the CCPR. An additive fat emulsion which was rapidly absorbed by the distal jejunum could play a role in maintaining ileal mucosa integrity through some mechanism independent of absorption.