Improved Gut Morphology Research Articles

Trace Mineral Supplementation for the Intestinal Health of Young Monogastric Animals.

Growth performance and feed efficiency are essential parameters when evaluating profitability of livestock. However, animal performance does not always reflect optimal gut health. Decades of research have supported the theory that improved animal performance such as average daily gain and feed efficiency can be impacted by intestinal health or the ability of the intestinal mucosa to absorb nutrients, but dysfunction may be found when the animal is stressed. Most of the early research focused on enteric infections causing diarrhea and nutritional alternatives to antibiotics which has led to findings related to pharmacological supplementation of trace minerals above the nutrient requirements for non-ruminants. While pharmacological concentrations of copper (Cu) have been shown to enhance growth, the mechanism in the gut is elusive. High concentrations of zinc (Zn) fed to newly weaned nursery pigs reduced the incidence of diarrhea from the proliferation of enterotoxigenic Escherichia coli (E. coli) and Clostridium and improve gut morphology. There are numerous publications where pharmacological supplementation of Zn as zinc oxide (ZnO) were fed to newly weaned pigs. Pharmacological Zn has been reported to shape the intestinal microflora as well as the diversity of the microflora during the first 2 weeks post-weaning. Both Fe deficiency and fortification impact bacterial growth in the intestine. Therefore, this paper will focus on the role of trace minerals that potentially impact optimal gut health of young monogastric animals.

Dietary arginine affects growth, gut morphology, oxidation resistance and immunity of hybrid grouper (Epinephelus fuscoguttatus♀×Epinephelus lanceolatus♂) juveniles.

An 8-week growth trial was conducted to evaluate the effects of dietary arginine (Arg) levels on growth, gut morphology, oxidation resistance and immunity of hybrid grouper (Epinephelus fuscoguttatus♀×Epinephelus lanceolatus♂) juveniles. Seven isoenergetic (1465 kJ (350 kcal)/100-g DM), isoproteic (53·5 % of DM) and isolipidic (7 % of DM) experimental diets were formulated to contain graded Arg levels ranging from 1·9 to 4·7 % (dry weight) at approximately 0·5 % increments. Each diet was randomly assigned to triplicate groups of 16 juvenile fish (average initial body weight: 11·7 (sd 0·1) g) and was administered twice daily (08.00 and 16.00 hours). After the growth trial, all remaining fish were fed their prescribed diets for 2 d and then exposed to 4·5 mg Cu2+/l water for 36 h. Results showed that growth performance and feed utilisation of experimental fish were significantly affected by different dietary Arg levels. Weight gain % (WG%) of fish was increased as dietary Arg increased, reaching a peak value at 3·8 % dietary Arg level, and when dietary Arg level increased to 4·7 % WG% was reduced. Fish fed 1·9 and 2·2 % dietary Arg levels had higher daily feed intake compared with fish fed other dietary Arg levels. Feed conversion ratios in fish fed 1·9, 2·2, 2·7 and 4·7 % dietary Arg levels were higher than those in fish fed 3·1, 3·8 and 4·1 % dietary Arg levels. Protein efficiency ratio and protein productive value (PPV) increased with an increase in dietary Arg, up to a peak value at 3·8 % dietary Arg level, above which these parameters declined. On the basis of quadratic regression analysis of weight gain % (WG%) or PPV against dietary Arg levels, the optimal dietary Arg requirement for hybrid grouper was estimated to be 3·65 %. Fish fed 3·8 % dietary Arg had higher whole-body and muscle protein contents compared with fish fed other dietary Arg levels. Fish fed 3·8 and 4·1 % dietary Arg levels had higher levels of mRNA for insulin-like growth factor-I and target of rapamycin in the liver compared with fish fed other dietary Arg levels. Hepatic S6 kinase 1 mRNA expression in fish fed 3·8 % dietary Arg level was higher than that in fish fed any of the other dietary Arg levels. Gut morphology, hepatic antioxidant indices and immune indices in serum and head kidney were significantly influenced by dietary Arg levels. In conclusion, the optimal dietary Arg requirement for hybrid grouper was estimated to be 3·65 %, and suitable dietary Arg supplementations improved gut morphology and oxidation resistance of hybrid grouper.

Dihydrocapsiate supplementation prevented high-fat diet–induced adiposity, hepatic steatosis, glucose intolerance, and gut morphological alterations in mice

Despite the lipolytic and thermogenic properties of capsaicin, its putative use as a weight-lowering dietary supplement has been limited because of the burning sensation caused by capsaicin when it comes in contact with mucous membranes. A potential alternative to capsaicin are the capsinoids, nonpungent capsaicin analogs that exhibit effects similar to capsaicin. Whereas the antiobesity properties of capsinoids have been reported, the effectiveness of FDA-approved synthetic dihydrocapsiate has not yet been investigated. In the present study, we hypothesized that dihydrocapsiate might ameliorate high-fat diet (HFD)–induced metabolic disorders in a manner similar to capsaicin and therefore can be its nonpungent alternative. To test this hypothesis, HFD-fed mice were orally administered dihydrocapsiate (2 and 10mg/kg body weight) for 12weeks. Dihydrocapsiate modestly reduced the HFD-induced weight gain and significantly prevented the associated hyperglyceridemia and hyperinsulinemia while improving glucose tolerance. Histological and gene expression analysis showed that dihydrocapsiate significantly prevented the lipid accumulation in white adipose tissue and brown adipose tissue via targeting genes involved in energy expenditure and mitochondrial biogenesis, respectively. Dihydrocapsiate corrected hepatic triglyceride concentrations and normalized expression of genes regulating hepatic lipid and glucose metabolism. Moreover, dihydrocapsiate administration significantly improved gut morphology and altered gut microbial composition, resulting in reduced host energy availability. Collectively, these results indicate that dihydrocapsiate administration improved glucose tolerance, prevented adiposity and hepatic steatosis, as well as improved HFD-induced gut alterations, positing dihydrocapsiate as a potential food ingredient for the dietary management of HFD-induced metabolic alterations.

Effects of Acidified Yeast and Whey Powder on Performance, Organ Weights, Intestinal Microflora, and Gut Morphology of Male Broilers

ABSTRACT In the present study, we investigated the effects of acidified dried whey and acidified yeast product and their combination on broiler growth characteristics, intestinal microflora and gut morphology. Seven hundred and fifty day-old Ross 308 male broilers were fed one of 10 dietary treatments with 5 replicates in a randomized design. A corn-soybean meal based diet (control group) was supplemented with 3 levels (0.15, 0.30 and 0.45%) of acidified whey powder (AW), acidified yeast product (AY), and acidified whey powder and yeast product (AWY). Acidified yeast product improved ADG and FCR at d 42, but the effects of additives on productive performance were not significant across the entire rearing period. The highest level of AY increased the population of Lactobacillus spp., decreased that of E. coli and did not affect the bacterial total count at d 42. Birds fed 0.45% AY showed higher villus height and better gut morphology compared to control birds. In conclusion, acidified yeast product increased the population of Lactobacillus, inhibited the growth of E. coli and improved gut morphology and structure, but did not affect growth performance and relative organ weight.

Identification of the protective effects of traditional medicinal plants against SDS-induced Drosophila gut damage

Traditional medicinal plants are widely used as immunomodulatory medicines that help improve health. A total of 50 different plants used for the treatment of toxicity were screened for their in vivo protective effects. Flies were fed a standard cornmeal-yeast medium (control group) or the standard medium containing medicinal plant extracts (experimental groups). Assessment of the survival rate was performed by feeding flies with toxic compounds. Gut epithelial cells were analyzed for cell proliferation and death by green fluorescent protein antibodies and 7-aminoactinomycin D staining under the microscope. The expression of antimicrobial peptides (AMPs) was evaluated by the quantitative polymerase chain reaction and the results revealed that after feeding the flies with toxic compounds, aqueous extracts from Codonopsis pilosula (Franch.) Nannf (C. pilosula), Saussurea lappa (Decne.) C.B.Clarke (S. lappa), Imperata cylindrica Beauv.var.major (Nees) C.E. Hubb. (I. cylindrical var. major) and Melia toosendan Sied. Et Zucc. (M.toosendan) increased the fly survival rate, reduced epithelial cell death and improved gut morphology. In addition, C. pilosula extracts induced the antimicrobial peptide levels (Dpt and Mtk) following treatment with sodium dodecyl sulfate (SDS). However, these extracts were not observed to increase SDS-induced cell proliferation in vivo. These results indicate that there are strong protective effects in extracts of C. pilosula, S. lappa, I. cylindrical var. major and M. toosendan on Drosophila intestinal cells among 50 medicinal plants.

The effect of moderate levels of finely ground insoluble fibre on small intestine morphology, nutrient digestibility and performance of broiler chickens

This experiment was carried out to assess the following hypothesis: feeding broiler to fine insoluble fibre in the diet will result in improved gut morphology and enhanced performance. In this experiment, 200 broiler chickens in 20 pen cages with wood shaving-lined floors were exposed to five treatment groups with four pens/treatment: control diet, diets contained 0.75 or 1.5% barley hulls or diets contained 0.75 or 1.5% rice hulls in a completely randomised design with five treatment, four replicate and 20 chicks each. Type of fibre influenced the performance and digestive traits of broilers with effects varying in accordance with the level of fibre. Rice hulls inclusion consistently improved growth performance and crude protein (CP) digestibility in broilers regardless of dietary inclusion level (p < 0.05). However, barley hulls at 1.5% level improved crypt depth: villous height (VH) ratio and feed conversion ratio had an opposite effect on VH (p < 0.05). The beneficial effects of hulls were more obvious with the 1.5% dietary inclusion level than the 0.75% level. The useful effects of rice hulls inclusion on broiler efficiency was mainly because of its effect on CP digestibility while barley hulls at 1.5% level positively changed jejunum morphology. The data suggest that broilers may have a nominal requirement for insoluble fibre, however, the source and dietary inclusion rate of fibre might be important factors to satisfy dietary fibre requirements in birds.

Effects of dietary supplementation with lysine-yielding Bacillus subtilis on gut morphology, cecal microflora, and intestinal immune response of Linwu ducks1

The effects of dietary supplementation with lysine-yielding Bacillus subtilis on gut morphology, cecal microflora, and expression of intestinal cytokine mRNA of Linwu ducks (a Chinese local domesticated duck) were investigated after a 63-d feeding trial. Two hundred forty 1-d-old female ducklings were randomly assigned to 1 of 4 dietary treatments, and there were 60 birds per treatment replicated 6 times with 10 birds each. The experimental diets consisted of a basal diet containing no antibiotic or growth promoters, the basal diet supplemented with 150 mg Aureomycin per kg feed, and 2 others supplemented with 5.0 × 108 and 5.0 × 1010 cfu B. subtilis/kg feed, respectively. Birds fed the diets supplemented with B. subtilis had increased (P < 0.001) villi height in the jejunum and ileum and reduced (P < 0.001) crypt depth in the jejunum compared with birds fed the control diet. Greatest (P < 0.01) villus height:crypt depth ratio was obtained with the jejunum and ileum of birds fed the diet supplemented with 5.0 × 1010 cfu B. subtilis/kg feed. Dietary supplementation with B. subtilis resulted in increased (P < 0.05) cecal counts of Megasphaera elsdenii. Greater cecal Lactobacillus counts were obtained in ducks fed the diets supplemented with Aureomycin and B. subtilis. Ducks fed the diets supplemented with B. subtilis showed suppressed (P < 0.001) expression of interleukin (IL)-1β, IL-2, and IL-10 in their jejunum. When compared with the control, the expression of interferon (IFN)-γ in the jejunum of ducks fed the diet supplemented with 5.0 × 108 cfu B. subtilis/kg feed was significantly increased (P < 0.05). Dietary supplementation with B. subtilis or Aureomycin reduced (P < 0.001) ileal expression of IL-10. When compared with the control, the expression of IL-2 and IL-8 in the ileum of ducks fed the diet supplemented with 5.0 × 1010 cfu B. subtilis/kg feed showed a significant decrease (P < 0.05). In conclusion, dietary supplementation with lysine-yielding B. subtilis improved gut morphology, increased the population of beneficial gut microflora, and stimulated increased intestinal immune response of Linwu ducks.

Maternal supplementation of seaweed-derived polysaccharides improves intestinal health and immune status of suckling piglets.

The experiment investigated the effect of maternal dietary supplementation of seaweed-derived polysaccharides (SDP) (-SDP v. +SDP, n 20) from day 83 of gestation until weaning (day 28) on selected sow faeces and piglet digesta microbiota populations, piglet small-intestinal morphology, and intestinal nutrient transporter and inflammatory cytokine gene expression at birth, 48h after birth and weaning. The effect of maternal dietary treatment on the piglet gene expression profile of inflammatory cytokines in the colon following a lipopolysaccharide (LPS) challenge was also investigated. Dietary SDP reduced sow faecal Enterobacteriaceae gene numbers at parturition. Small-intestinal morphology, nutrient transporter and cytokine gene expression in newborn piglets did not differ between maternal dietary treatments (P>0·10). At 48h after birth, sodium-glucose-linked transporter 1 gene expression was down-regulated in the ileum of piglets suckling the SDP-supplemented sows compared with those suckling the basal sows (P=0·050). There was a SDP×LPS challenge interaction on IL-1 and IL-6 gene expression in the colon of piglets (P<0·05). The gene expression of IL-1 and IL-6 was down-regulated in the LPS-challenged colon of piglets suckling the SDP sows compared with those suckling the basal sows (P<0·05). However, there was no difference in IL-1 and IL-6 gene expression in the unchallenged colon between treatment groups. At weaning, piglets suckling the SDP-supplemented sows had increased villus height in the jejunum and ileum compared with those suckling the basal-fed sows (P<0·05). In conclusion, maternal dietary SDP supplementation enhanced the immune response of suckling piglets and improved gut morphology, making them more immune competent to deal with post-weaning adversities.

Evaluation of effects of EarlyBird associated with FloraMax-B11 on Salmonella Enteritidis, intestinal morphology, and performance of broiler chickens

A posthatch fasting period of 24 to 72 h is a common and inevitable practice in commercial poultry production. This delay in start of feed intake has been reported to negatively affect yolk utilization, gastrointestinal development, slaughter weight, breast meat yield, performance, and to also depress immunological development, making the birds more susceptible to infection from pathogens such as Salmonella. Furthermore, public concerns regarding the considerable human rates of illness reported and the emergence of antibiotic-resistant strains of Salmonella have doubled the challenge on the poultry industry to find alternative means of Salmonella control. In the present study, we evaluated the effects of a combination of early feeding with probiotic supplementation on morphological development of mucosa, control of Salmonella, and overall performance in broiler chickens. We used a blend of a commercially available perinatal supplement, EarlyBird (EB; Pacific Vet Group USA Inc., Fayetteville, AR), and a successful probiotic supplement, FloraMax-B11 (FM; Pacific Vet Group USA Inc.), to evaluate the effects on gut morphology, Salmonella intestinal colonization, and horizontal transmission, along with its effects on BW and related performance in broiler chickens under simulated commercial hatching management and shipping conditions. Morphometric analysis showed increased villus height, villus width, villus to crypt ratio, and villus surface area index in chickens treated with EB + FM groups. Significant reductions in Salmonella recovery, incidence, and horizontal transmission were also observed among the same groups, suggesting beneficial effects of early feeding and competitive exclusion by probiotic bacteria. Improved gut morphology and Salmonella exclusion was very well supported by BW data with significantly lower early BW loss and overall BW gains in birds treated with EB + FM mixture. The results of this study demonstrated that the combination of EB and FM improved gut morphology, reduced the amount of Salmonella that could be recovered, as well as improved BW when compared with controls and each product individually. These data address both animal welfare and food safety concerns faced by the poultry industry.

Effect of Glutamine Supplementation Associated with Probiotics on Salmonella Typhimurium and Nitric Oxide or Glutamine with Perinatal Supplement on Growth Performance and Intestinal Morphology in Broiler Chickens

Glutamine-enriched diets have been linked with favorable intestinal effects including structure maintenance of gut barrier against bacteria attacks and enterocyte differentiation. Although post hatch, immaturity of the GIT in the first week is a limiting factor, early nutrition has shown to be an alternative to alleviate the adverse performance effects of post-hatch starvation. In addition, both live and spore based probiotics have earned tremendous attention as a viable control of enteric pathogens. Present studies were carried out with objectives of evaluating the influence of nutrition and synergistic effects of Gln supplementation in combination with FloraMax-B11 (FM), a defined lactic acid bacteria (LAB) probiotic product; PHL-NP-122, a heat-resistant spore-forming Bacillus subtilis (BS); and EarlyBird (EB), a natural hydration and nutrition supplement for neonatal broilers and poults, on Salmonella Typhimurium colonization. Morphometric analysis showed increased (P<0.05) villus height, villus width, and villus surface area index in chickens treated with all combination groups. A reduction (P<0.05) on nitric oxide (NO) produced was observed in the explant tissues of all the treated groups in comparison with the control group and a synergistic effect (P<0.05) in the groups treated with Gln and BS (HPL-NP-122). Reductions in Salmonella recovery incidence (P<0.05) and colonization (P< 0.05 to P<0.001) were also observed among the treated groups, suggesting beneficial effects of these combinational feed supplements. Improved gut morphology and Salmonella exclusion was very well supported by body weight (BW) data with lower (P<0.05) early BW loss and overall BW gains in birds treated with treated groups. Considering the fact that the feed costs represents from 70 to 80% of the poultry production and the integrity of the epithelial cells of the mucosa, hence ensured good performance and production, is dependent of feed and feed supplements, these studies hold their relevance and importance as beneficial in more than one aspect to the poultry industry.

The effect of in ovo administration of mannan oligosaccharide on small intestine development during the pre- and posthatch periods in chickens

Early intestinal development is essential for chicken embryos to fulfill their maximal growth potential. Mannan oligosaccharide (MOS) is known to improve gut morphology, function, and innate immunity; therefore, we hypothesized that its administration in the prehatch period to the sterile intestine of embryos would affect intestinal development and functionality without mediation of gut microflora. The MOS was administered by in ovo feeding procedure to embryos 3 d before hatch. the effects of MOS administration on intestinal morphology, activity of the brush-border enzymes amino peptidase (AP) and sucrase isomaltase (SI) and mRNA abundance of AP, SI, sodium-dependent glucose cotransporter 1 (SGLT1), peptide transporter 1 (PepT1), secreted mucin (MUC2), and toll-like receptors (TLR2 and TLR4) were examined and compared with saline-injected and noninjected controls. Results show that on embryonic d 20 the only parameter affected was MUC2 mRNA abundance, which exhibited a 3-fold increase in the MOS group versus controls. On day of hatch more parameters were affected: a 20 to 32% increase in villus area was found in the MOS group compared with controls; crypt depth and number of goblet cells per villus were higher by 20 and 50%, respectively, compared with the saline group; and AP and SI activities were higher by 44 and 36%, respectively, compared with the noninjected control. In addition, an increase in fold change mRNA abundance of AP, SI, and TLR4 was observed in the MOS group compared with controls. However, on d 3 posthatch, a decrease in MOS effects was noted, indicating a temporally limited effect after administration of 1 dose. In ovo administration of MOS prehatch resulted in a hatching chick with more mature enterocytes and enhanced epithelial barrier and digestive and absorptive capacity at day of hatch. Results imply that the mechanism underlying the observed changes is not mediated through gut microflora but rather involves a direct effect of MOS on intestinal cells.

Dietary mannan oligosaccharide supplementation modulates intestinal microbial ecology and improves gut morphology of rainbow trout, Oncorhynchus mykiss (Walbaum)

A study was conducted to investigate the effect of mannan oligosaccharide (MOS) on the gut microbiota and intestinal morphology of rainbow trout under commercial farming conditions. Juvenile (mean initial BW 38.2 +/- 1.7 g) and subadult (111.7 +/- 11.6 g) trout were fed 2 dietary treatments for 111 and 58 d, respectively. The control treatment consisted of a standard commercial diet, and the MOS treatment consisted of the control diet supplemented with 0.2% MOS. Morphology of the anterior and the posterior intestine was examined with light and electron microscopy. Light microscopy demonstrated increased gut absorptive surface area in the subadult MOS group. Additionally, electron microscopy revealed an increase in microvilli length and density in the subadult MOS group compared with the control (P < 0.05). However, no significant improvements were detected in the juvenile group. Culture-based evaluation of the intestinal microbiota showed that MOS significantly reduced (P < 0.05) the viable intestinal bacterial populations (by approximately 2 log scales in all cases). Levels of Aeromonas/Vibrio spp. were significantly decreased (P < 0.05) in the juvenile MOS group (9% of the total microbiota) compared with the juvenile control group (37%). Additionally, analysis of microbial communities was conducted using denaturing gradient gel electrophoresis of PCR-amplified 16S rDNA. The denaturing gradient gel electrophoresis fingerprinting revealed an alteration of bacterial populations; analysis of similarity, similarity percentages, and nonmetric multidimensional scaling analysis showed that MOS reduced species richness and increased similarity of bacterial populations found within the subadult and juvenile groups. The current study shows that MOS modulates intestinal microbial communities, which subsequently improve gut morphology and epithelial brush border.

Intestinal morphology and enzymatic activity in newly weaned pigs fed contrasting fiber concentrations and fiber properties1

The main objective of this study was to determine the effect of fiber source and concentration on morphological characteristics, mucin staining pattern, and mucosal enzyme activities in the gastrointestinal tract of pigs. The experiment included 50 pigs from 10 litters weaned at 4 wk of age (BW 8.6 +/- 1.4 kg) and divided into 5 treatment groups. Diets containing fiber of various physico-chemical properties and concentrations were formulated to contain 73, 104, or 145 g of dietary fiber/kg of DM. The diets were based on raw wheat and barley flours. Pectin and barley hulls, representing soluble and insoluble fiber sources, respectively, were used to increase the fiber concentration. The pigs were fed the experimental diets for 9 d, and then the pigs were euthanized and the entire gastrointestinal tract was removed. Tissue samples were taken from the mid and distal small intestine and from the mid colon. Inclusion of pectin in the diets significantly decreased (P < 0.001) ADFI and ADG compared with pigs fed no pectin. The villi and the crypts were shorter in pigs fed pectin-containing diets, but the villous height/crypt depth ratio was unaltered. Pectin significantly decreased the area of mucins in the crypts of the small intestine, indicating that the pigs fed the pectin-containing diet would probably be more susceptible to pathogenic bacteria, although this cannot be separated from the impact on ADFI. The lectin-binding pattern of the intestinal mucosa was unaffected by diet. The activity of lactase and maltase was increased in pigs fed diets with high fiber content, whereas sucrase activity was increased in pigs fed the pectin-containing diets. The activity of the peptidases, aminopeptidase N and dipeptidylpeptidase IV, was increased when feeding high fiber diets, whereas the activity of gamma-glutamyl transpeptidase remained unaffected by the experimental diets. In conclusion, the reduced feed intake observed with the pectin-containing diets could explain the lower villous height and crypt depth observed in this study. However, direct effects of pectin also are possible, and thus further study is warranted. Feeding pigs high insoluble fiber diets improved gut morphology by increasing villi length and increased mucosal enzyme activity when compared with pigs fed pectin-containing diets. The mucin content as determined by staining characteristics suggests that pigs fed high insoluble fiber diets might be better protected against pathogenic bacteria than pigs fed diets high in soluble fiber.

Comparative effects of dietary nucleoside-nucleotide mixture and its components on endotoxin induced bacterial translocation and small intestinal injury in protein deficient mice.

Nucleoside-nucleotide mixture has been shown to improve gut morphology and reduce the incidence of bacterial translocation in protein deficient mice. To compare the reparative effect of nucleoside-nucleotide mixture and their individual components on maintenance of gut integrity and bacterial translocation based on their differential metabolism and utilisation. ICR (CD-1) mice were randomised into eight groups of 10 animals each and fed 20% casein diet (control), protein free diet, or protein free diet supplemented with 3 M cytidine, uridine, thymidine, inosine, guanosine monophosphate, or nucleoside-nucleotide mixture for four weeks. On the fourth week, each mouse was injected lipopolysaccharide intraperitoneally (50 micrograms/500 microliters) and the incidence of bacterial translocation, caecal bacterial populations, and the ileal histology, noted 48 hours later. The death rate in the control group was 40% compared with 10% in the nucleoside-nucleotide mixture and 20% each in the individual components groups, respectively. Bacterial translocation to the mesenteric lymph node did occur in 100% of the surviving mice fed the control diet in comparison with 44% (nucleoside-nucleotide), 50% (cytidine), 75% (thymidine), 75% (uridine), 63% (inosine), and 63% (guanosine monophosphate). Histologically, the damage to the gut was more distinct in the protein free diet group. Villous height, crypt depth, and wall thickness in the nucleoside-nucleotide mixture group mean (SEM) (5.01 (0.34); 0.87 (0.14); 0.33 (0.10)), were respectively, higher compared with the protein free diet (3.34 (0.34); 0.61 (0.03); 0.18 (0.04)) group. In the cytidine group, crypt depth (0.86) (0.08)), and wall thickness (0.30 (0.002)) were higher. The same measurements in the components groups tended to be higher than the protein free diet group. Caecal bacterial populations were, however, similar in all groups. These results suggest that dietary nucleosides and nucleotides are essential nutrients for intestinal repair; nucleotides or cytidine provide a better response.

Glutamine and Its Effects on the Intestine

Glutamine, an amino acid, is the principal energy substrate for small intestinal cells. It also acts as a nitrogen carrier through its amide nitrogen. Arterial glutamine is supported by net synthesis in skeletal muscle. Glutamine is rapidly metabolized by the intestine, whether supplied from the lumen or from the arterial circulation. Intestinal uptake of glutamine increases after trauma and operative stress. The consumption of glutamine by the gut may in large part be dependent on mucosal glutaminase activity and on enterocyte glutamine transport. Glutaminc has been shown to improve gut morphology and outcome in animal models of encerocolitis. It may play a similar role in aiding repair of human intestinal injury in persons with sufficient glutamine in their diet compared to those who arc glutamine deficient. Glutamine may have a positive effect on the immune function of the intestinal mucosal-associated lymphoid tissue. Glutamine is not currently available in nutritional preparations for routine clinical use, yet it has recently been shown to benefit maintenance of nitrogen balance in humans. Due to the instability and low solubility of glutamine, dipeptides have been studied. L-alanyl-L-glutamine seems to be the most promising glutamine precursor for parenteral use in humans, as it is safe and rapidly hydrolyzed in vivo to release free glutamine. The exact role of glutamine as a therapeutic agent to promote intetitinal well-being has yet to be determined. However, preliminary evidence suggests that glutaminc will be helpful in a variety of clinical scenarios.