Some Aspects of Gastrointestinal Adaptation to Obstruction of the Small Intestine: Modulating Role of Diet

Laferla, Godfrey (1987) Some Aspects of Gastrointestinal Adaptation to Obstruction of the Small Intestine: Modulating Role of Diet. PhD thesis, University of Glasgow.

Abstract

The "well being" of the gastrointestinal tract is maintained by the interplay of several -factors, notably diet, pancreatic and biliary secretions and gastrointestinal hormones. These same factors may be responsible for enabling the organ to adapt to chanqing circumstances. To date, most of what is known about gastrointestinal adaptation has been derived from animal experimentation and the progress in this field has, to some extent, been limited by the suitability of the animal models. One such example is the adaptive response of the gastrointestinal tract to small intestinal obstruction. Whereas a wealth of information exists regarding adaptation to acute obstruction, knowledge of the changes to the chronic event is limited. The first aim of the thesis was therefore to further develop and modify a reproducible model of chronic small bowel obstruction in the rat. The study was then extended to investigate the changes in both the proximal (i.e. oesophagus, stomach and proximal small intestine) as well as the distal (i.e. distal small intestine) bowel to obstruction. In addition, the presence and absence of food bulk on these changes was also investigated. The gastrointestinal hormone profiles under each experimental condition were also identified. It was found that: 1. An increase in oesophageal weight occurred following a high small bowel obstruction. Other levels of small bowel obstruction had no noticeable effect on the oesophagus. 2. The response of the stomach to obstruction varied with the site of the small bowel obstruction. A high obstruction produced a marked dilatation of the stomach. A mid small intestinal obstruction generated marked gastric muscle hypertrophy. 3. The jejunum and the ileum behaved in a similar fashion in that both showed an increase in weight and and in luminal circumference in response to obstruction. However the magnitude of the ileal response was far greater. 4. The administration of a low residue diet did not result, during the time period of the experiment, in a reduction of the mucosal weight of the gastrointestinal tract. However a reduction in both the DNA and protein concentration was observed. When this low residue diet was administered to rats subjected to a small bowel obstruction, the hypertrophic response noted in chow-fed obstructed animals was abolished. 5. Disuse atrophy of the mucosa was seen in the ileum of rats with a mid small bowel obstruction fed on chow. Although some degree of atrophy did occur in similarly obstructed rats fed on a low residue diet, the degree of atrophy was significantly less than that in chow fed obstructed animals. 6. Hormonal assays showed that: a. Serum gastrin was raised following a high obstruction and following the administration of a low residue diet. b. Serum N-glucagon levels showed significant increases following mid and distal small bowel obstruction. c. Vasoactive intestinal peptide levels were increased following a distal obstruction.

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Keywords: Medicine
• Date of Award: 1987
• Depositing User: Enlighten Team
• Unique ID: glathesis:1987-77663
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 14 Jan 2020 11:53
• Last Modified: 14 Jan 2020 11:53
• URI: https://theses.gla.ac.uk/id/eprint/77663