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

Purpose: 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.

Methods: 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.

Results: 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.

Conclusion: 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.