Protein hydrolysate vs free amino acid-based diets on the nutritional recovery of the starved rat.

BACKGROUND AND AIMS: To test the hypothesis that a peptide-based enteral product was equivalent to a low-fat, free amino acid-based formula in the nutritional and functional recovery of the starved rat. METHODS: Sixteen male Wistar rats were starved for 3 days. Then, rats were randomised to a whey protein hydrolysate-based diet or a free amino acid-based diet and refed for 3 days. The experiment was designed to provide the same energy intake in both groups. The parameters studied included body weight gain, nitrogen retention, plasma free amino acid concentrations, muscle glutamine concentrations and glutathione levels in gut mucosa and liver. RESULTS: Weight gain was statistically higher on the peptide-based diet than on the elemental diet after the refeeding period. This difference in weight gain was associated with a statistically higher nitrogen retention. Plasma and muscle free glutamine concentrations were higher in rats fed the whey protein hydrolysate-based diet than those in rats refed the free amino acid-based diet, even though the glutamine intake was higher in the latter group. Glutathione concentrations in liver and gut mucosa were similar in the groups. CONCLUSION: We conclude that enteral diets containing peptides were more effective than a diet containing free amino acids in the nutritional recovery of the starved rat.

Food deprivation and refeeding influence growth, nutrient retention and functional recovery of rats.

The objective of this work was to determine the effects of starvation and refeeding on growth, nutritional recovery and intestinal repair in starved rats. Male Wistar rats, weighing 200 g, were starved for 3 d, then refed a soy-based diet for another 3 d. Normally fed rats were given the same diet and used as controls. The variables assessed were as follows: body weight gain and nitrogen retention during recovery after starvation; muscle glutamine concentration; tissue protein content; gut mucosa and liver glutathione levels; intestinal permeability to ovalbumin, lactulose and mannitol; and intestinal tissue apoptosis. Starvation was associated with lower muscle glutamine levels and intestinal mucosa impairment, including a lower content of mucosal protein, a higher level of oxidized glutathione, enhanced permeability to macromolecules and greater numbers of apoptotic cells. Refeeding for 3 d resulted in rapid repair of gut atrophy and normalization of not only intestinal permeability but also of the majority of metabolic markers assessed in other tissues. In conclusion, with the use of severely starved rats, we have established a reversible experimental animal model of malnutrition that might prove useful in comparing the effectiveness of different enteral diets.