Age-related response of the small intestine to severe starvation and refeeding in rats

Restoration of anthropometric, biochemical and histopathological alterations by Lactobacillus casei supplementation in Giardia intestinalis infected renourished BALB/c mice

The present study describes the in vivo ameliorating effect of Lactobacillus casei supplementation in renourished Giardia intestinalis infected BALB/c mice. It was observed that daily administration of probiotic 7 days prior to Giardia-infection to renourished mice, efficiently reduced the excretion of Giardia cysts and trophozoite counts, along with significant increased fecal lactobacilli counts compared with Giardia-infected mice. It was also observed that oral feeding of probiotic to renourished-Giardia-infected mice abrogated all the anthropometric and biochemical anomalies. Histologically, morphological and cellular alteration of microvillus membrane integrity revealed that probiotic administration further ameliorated the mucosal damage in renourished-probiotic-Giardia-infected mice compared to severe microvillus atrophy, oedematous, vacuolated epithelial cells and ileitis in renourished-Giardia and Giardia-infected mice. Thus, it is suggested that probiotic used as the functional food helps in restoration of anthropometric, biochemical alterations and atrophied gut by enhancing the goblet cells and reducing the giardiasis.

Starvation-induced proximal gut mucosal atrophy diminished with aging

BACKGROUND

Starvation induces small bowel atrophy with increased intestinal epithelial apoptosis and decreased proliferation. The authors examined these parameters after starvation in aged animals.

METHODS

Sixty-four 6-week-old and 26-month-old C57BL/6 mice were randomly assigned to either an ad libitum fed or fasted group. The small bowel was harvested at 12, 48, and 72 hours following starvation. Proximal gut mucosal height was measured and epithelial cells counted. Apoptosis was identified by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) staining. Proliferation was determined by immunohistochemical staining for proliferating cell nuclear antigen. Comparison of fed vs fasted and adult vs old groups was done by one-way ANOVA with Tukey's test and unpaired Student's t test. Significance was accepted at P < .05.

RESULTS

Aged mice had higher proximal gut weights, mucosal heights, and cell numbers at baseline compared with the adult group (P < .05). The rate of apoptosis was lower in the aged (P < .05), but proliferation was not different between groups before starvation. After starvation, proximal gut wet weight decreased only in adult mice (P < .05). Gut mucosal height and mucosal cell number decreased more in adult than in aged mice (P < .05). This was related to decreased proliferation only in the adult group (P < .05). The fold of epithelial apoptosis that increased was higher in the aged group than in the adult group after starvation (P < .05).

CONCLUSIONS

Gut mucosal kinetics change with age and have lower rates of apoptosis and greater mucosal mass; the character of starvation-induced atrophy is diminished with aging.

Rapid restoration of colonic goblet cells induced by a hydrolyzed diet containing probiotics in experimental malnutrition

PURPOSE

To investigate the effects of the addition of probiotic bacteria to a hydrolyzed diet on the recovery of goblet cells during renutrition in an animal model of malnutrition.

METHODS

Twenty-six male Wistar rats (200-250g) were included in the study. Six were kept under normal conditions (sham group) while twenty received an aproteic diet for 15 days, and were randomized thereafter to receive a hydrolyzed diet containing (n=6; probiotic group) or not (n=6; hydrolyzed group) probiotics (10(6) cfu/g of Streptococcus thermophilus e Lactobacillus helveticus); or immediately killed (n=8; aproteic group). Histological slides containing cecal and sigmoid biopsies were used to counting the number of goblet cells and the goblet cells/colonocytes ratio.

RESULTS

Malnutrition diminished the population of goblet cells in all sites. Goblet cells/colonocytes ratio of the probiotic group was significantly greater than hydrolyzed group at the ceccum (0.39 +/- 0.03 vs. 0.34 +/-0.02; p=0.02). Only rats fed with probiotics showed complete restoration of the normal goblet cells/colonocytes ratio at the sigmoid (0.37 +/- 0,02 vs. 0.22 +/- 0,03; p<0,001).

CONCLUSION

Streptococcus thermophilus and Lactobacillus helveticus added to a renutrition diet enhance the recovery of mucosal atrophy induced by malnutrition and especially induce a rapid restoration of goblet cells population in the malnourished colonic mucosa.

Chronic low intake of protein or vitamins increases the intestinal epithelial cell apoptosis in Wistar/NIN rats

OBJECTIVE

Malnutrition decreases antioxidant defense and increases oxidative stress in the intestine. We studied the effects of long-term restriction of food, protein, and vitamins on intestinal epithelial cell (IEC) apoptosis and the underlying mechanisms.

METHODS

Weanling, Wistar/NIN male rats were fed ad libitum with a control diet, 75% protein-restricted diet, or 50% vitamin-restricted diet for 20 wk. The food-restricted group received 50% of the diet consumed by control rats. IEC apoptosis was monitored by morphometry, Annexin V binding, M30 CytoDeath assay, and DNA fragmentation. Structural and functional integrity of the villus were assessed by the ratio of villus height to crypt depth, and alkaline phosphatase and lys, ala-dipeptidyl aminopeptidase activities, respectively. Oxidative stress parameters, caspase-3 activity, and expression of Bcl-2 and Bax were determined to assess the probable mechanisms of altered apoptosis.

RESULTS

Protein and vitamin restrictions but not food restriction significantly increased IEC apoptosis and only vitamin restriction altered structural and functional integrity of villi. Increased levels of protein carbonyls, thiobarbituric acid reactive substances, and caspase-3 activity along with decreased glutathione levels and Bcl-2 expression were observed in IECs of these rats, whereas food restriction did not affect these parameters.

CONCLUSIONS

Protein restriction increased only IEC apoptosis, whereas vitamin restriction also affected the structure and function of villi. Modulation of the pathway mediated by mitochondria through increased oxidative stress appears to be the probable mechanism underlying this effect.

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.

Severe dietary restriction initiated in aged rats: evidence for poor adaptation in terms of protein metabolism and intestinal functions

BACKGROUND

Protein energy malnutrition is a common finding in elderly people, increasing morbidity and mortality in aged inpatients. Investigations need to be developed to counteract malnutrition-induced alterations early and to avoid potential irreversible lesions. The aim of this experimental study was to evaluate time-response to severe dietary restriction (DR) initiated in aged rats in terms of protein metabolism and digestive trophicity.

MATERIALS AND METHODS

After the acclimatization period, 22-month-old male rats were randomized into six groups: three control groups, fed ad libitum for 3, 6 or 12 weeks with a standard diet and three corresponding dietary-restricted groups fed for the same periods with only 50% of the spontaneous intake. Intestinal mucosa, liver and skeletal muscles (soleus, extensor digitorum longus and tibialis anterior muscle) were removed when the rats were killed.

RESULTS

DR induced dramatic body weight loss (up to 50% of initial body weight after 12 weeks DR). Protein metabolism was affected in terms of nitrogen balance (P < 0.01) and protein content, in particular at the splanchnic level. Morphometrically, the intestine structure was altered after 12 weeks of DR (P < 0.01), and this atrophy was correlated with malabsorption of mannitol (P < 0. 01). Ileal hydrolase activities were decreased throughout the 12 weeks of DR.

CONCLUSIONS

Aged rats clearly exhibit a defect of adaptation to long-term DR initiated at an advanced age. Severe DR leads to malnutrition, which becomes of major importance after 12 weeks, in particular at the intestine level. Hence, application of these experimental results to elderly, malnourished people may contribute to a better knowledge of denutrition-induced disorders.