Alterations in the intestinal wall due to protein malnutrition in rats: Evaluation of the rupture strength and the tissue's collagen

Victor Nakajima,Jair Cortez Montovani,Shoiti Kobayasi,Paulo Roberto Curi,Luís Eduardo Naresse,Celso Vieira De Souza Leite

doi:10.1590/s0102-86502008000500008

Abstract

To study the effect of protein malnutrition on the intestinal wall of rats by evaluating alterations in the rupture force and dosing tissue collagen in the ileum and distal colon. One hundred and twenty rats, that had an average weight of 100g, were used. They received water and a standard diet with 20% protein during 7 days for adaptation to the diet itself and to environmental conditions. After that period, the animals were randomly distributed in two groups of 60 rats each: Group 1 - the animals received a control diet with 20% casein for 21 days; Group 2 - hypoprotein diet with 2% casein for 21 days. After the adaptation period, 12 animals of each group were sacrificed at 5 moments: the beginning of experimental period (M0), 4 degrees day (M1), 7 degrees day (M2), 14 degrees day (M3) and 21 degrees day (M4). The diet to the other rats was maintained until the last sacrifice. The following variables were evaluated: body weight, blood albumin rate, tissue's hydroxyproline, hydroxyproline/total protein ratio and rupture strength in the intestinal wall of the ileum and the distal colon. It was observed that the rupture strength in the ileum segment and distal colon was lower in malnourished animals (Group 2); the loss of mechanical resistance was higher in the distal colon segment than in the ileum probably due to the smaller concentration of tissue collagen in the distal colon. Protein malnutrition induces the loss of mechanical resistance of the ileum and distal colon and may be associated with a smaller percentage of collagenous tissue formation in the intestinal wall.

Highlights

Malnutrition is regarded as a serious problem nationwide and, as a result, nutritional deficiencies have been broadly studied in the experimental field[1,2].The incidence of malnutrition in the hospitalized population is of 30 to 50%, and the frequency at which malnutrition occurs in this population is relatively constant despite the nature of the disease and the patient’s social and economic status
Malnutrition affects the progression of surgical wounds, favoring anastomosis dehiscence and infection in the peritoneal cavity[5,6], which may result in patient’s high morbidity and mortality rates
Most experimental studies focus on cicatrization under normal experimentation conditions when, in the clinic, various adverse factors are associated with the dehiscence of intestinal anastomosis, among them the malnutrition[9,10]

Summary

Introduction

The incidence of malnutrition in the hospitalized population is of 30 to 50%, and the frequency at which malnutrition occurs in this population is relatively constant despite the nature of the disease and the patient’s social and economic status. Malnutrition affects the progression of surgical wounds, favoring anastomosis dehiscence and infection in the peritoneal cavity[5,6], which may result in patient’s high morbidity and mortality rates. Dehiscence of anastomoses in the large intestine in particular is a frequent complication that is associated with high mortality[7] rates while those related to dehiscence of ileal anastomoses are low[8]. Most experimental studies focus on cicatrization under normal experimentation conditions when, in the clinic, various adverse factors are associated with the dehiscence of intestinal anastomosis, among them the malnutrition[9,10]

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Conclusion