Glucagon-like peptide 2 treatment may improve intestinal adaptation during weaning

Intestinal failure among adults and children: Similarities and differences

Intestinal failure (IF) is a complex medical condition that is caused by a constellation of disorders, resulting in the gut's inability to adequately absorb fluids and nutrients to sustain hydration, growth, and survival, thereby requiring the use of parenteral fluid and/or nutrition. Significant advancements in intestinal rehabilitation have resulted in improved survival rates for individuals with IF. There are distinct differences, however, related to etiology, adaptive potential and complications, and medical and surgical management when comparing children with adults. The purpose of this review is to contrast the similarities and differences between these two distinct groups and provide insight for future directions, as a growing population of pediatric patients will cross into the adult world for IF management.

Management of pediatric intestinal failure related to short bowel syndrome

Intestinal failure (IF) secondary to short bowel syndrome is a challenging and complex medical condition with significant risk for surgical and medical complications. Significant advancements in the care of this patient population have led to improved survival rates. Due to their intensive medical needs children with IF are at risk for long-term complications that require comprehensive management and close monitoring. The purpose of this paper is to review the available literature emphasizing the surgical aspects of care for children with IF secondary to short bowel syndrome. A key priority in the surgical care of this patient population includes strategies to preserve available bowel and maximize its function. Utilization of novel surgical techniques and autologous bowel reconstruction can have a significant impact on children with IF secondary to short bowel syndrome related to the function of their bowel and ability to achieve enteral autonomy. It is also important to understand the potential long-term complications to ensure strategies are put in place to mitigate risk with early detection to improve long-term outcomes.

Evaluating the efficacy of a ferrous-ion-chelating peptide from Alaska pollock frame for the improvement of iron nutritional status in rats

This study aimed to investigate the effects of ferrous-ion-chelating peptides from Alaska pollock frames (APFP-Fe) on iron deficiency in anaemic rats. We hydrolysed the Alaska pollock frames to obtain a peptide with an average molecular weight of 822 Da. The bioavailability of APFP-Fe was tested using animal experiments. Wistar rats were randomly divided into six groups: an iron deficiency control group, a normal control group, and iron deficiency groups treated with ferrous sulfate (FeSO₄) or low-, medium-, or high-dose APFP-Fe. Rats in the iron deficiency groups were fed an iron-deficient diet to establish the iron deficiency anaemia (IDA) model. After the model was established, different iron supplements were given to rats once per day via intragastric administration for 21 days. The results showed that APFP-Fe had restorative effects, returning the body weight, weight gain, height, and haematological parameters in IDA rats to normal levels. In addition, compared with FeSO₄, APFP-Fe promoted significant weight gain and effectively improved haemoglobin, serum iron and transferrin levels, and recovery of the capacity of iron binding with transferrin, especially at the medium and high doses. These findings suggest that APFP-Fe is an effective source of iron for improving the iron nutritional status in IDA rats and shows promise as a new source of iron supplementation.

Effects of pulse-dose ruminal infusion of butyrate on plasma glucagon-like peptide 1 and 2 concentrations in dairy calves

Feeding of butyrate was found to have a positive effects in enhancing gut development and improving growth performance of calves. Equally, glucagon-like peptide 1 and 2 (GLP-1 and GLP-2), secreted from gastrointestinal L-cells in response to nutrient intake, were found to play a significant role in regulating blood glucose homeostasis and improving gut health. However, limited information is available about the relationship between butyrate and release of GLP-1 and GLP-2 in dairy calves. The objective of this study was to evaluate the effects of a pulse-dose ruminal infusion of butyrate on plasma GLP-1 and GLP-2 concentrations in dairy calves. Five ruminally cannulated mature Holstein bull calves (7.2 ± 0.10 mo, and 330 ± 16.0 kg of body weight; mean ± standard deviation) were used in a 5 × 5 Latin square with 4-d periods. On d 1 of each period at 0800 h, calves were ruminally infused with 1 of 5 treatments: 0 (saline), 0.3, 0.6, 0.9, and 1.2 g of butyrate per kg of body weight. Before butyrate infusion, calves were not offered feed overnight, and sequential blood and rumen fluid samples were taken before and after infusion on d 1 of each period. Ruminal butyrate and total volatile fatty acid concentrations increased linearly (2.65, 12.19, 20.99, 30.19, and 36.30; 23.68, 33.07, 40.94, 51.13, and 56.31 µmol/mL, for butyrate and total volatile fatty acids, respectively) in a dose-dependent manner, whereas propionate and isobutyrate increased quadratically. Ruminal and plasma butyrate, β-hydroxybutyrate, GLP-1, GLP-2, insulin, and glucose concentrations were all affected by treatment, time (except GLP-2), and interaction of treatment with time (except GLP-1). The area under the curve (AUC) summarized at different time points relative to the baseline (AUC30, AUC60, AUC120, and AUC240) for ruminal and plasma butyrate, and BHB, increased linearly with the dose of butyrate infused. However, AUC30, AUC60, AUC120, and AUC240 for plasma GLP-2 concentration were affected in a cubic manner unlike the linear effect on AUC30 and AUC60 for GLP-1. Plasma GLP-2 was not correlated with plasma butyrate (r = 0.16), GLP-1 (r = 0.03), or BHB (r = -0.05). This findings suggest that pulse-dosing of butyrate slightly increased both GLP-1 and GLP-2 concentrations at specific time points and this might be promoted by direct or indirect effect of butyrate on the intestinal L-cells.

Effects of energy restriction during gilt development on milk nutrient profile, milk oligosaccharides, and progeny biomarkers

An ongoing study at the University of Nebraska-Lincoln (which included 14 batches of gilts; n = 90 gilts/batch) demonstrated that energy restriction during the developmental period of a gilt increases longevity and may also have beneficial effects on progeny health and growth, particularly, parity 1 progeny. Therefore, we hypothesized that energy restriction during gilt development may affect milk nutrient profile, milk oligosaccharides (OS), and postnatal progeny biomarkers. During the development period, batch 14 gilts (n = 128, 8 gilts/pen) were fed 3 dietary treatments including the following: 1) Control diet formulated to NRC (2012) specifications (CTL); 2) Restricted (20% energy restriction via addition of 40% soy hulls; RESTR); and 3) CTL diet plus addition of crystalline amino acids equivalent to the SID Lys:ME of the RESTR diet (CTL+). All diets were fed ad libitum and applied in a 3-phase feeding regimen during gilt development (days 123 to 230 of age). Average daily feed intake was used to estimate daily metabolizable energy intake (Mcal/d) during each phase (Phase 1: 10.13, 6.97, 9.95; Phase 2: 11.25, 8.05, 10.94; and Phase 3: 9.47, 7.95,11.07) for CTL, RESTR, and CTL+, respectively. After 230 d of age, gilts were bred and fed a common diet. Milk samples were collected from batch 14 gilts (n = 7 per treatment) on days 0 and 14 postfarrowing for compositional analysis of N, CP, dry matter (DM), GE, insulin, and OS. Piglet blood samples (n = 6 piglets/gilt) were obtained on days 1 and 15 postfarrowing for quantification of glucagon-like peptide-2 (GLP-2) and insulin. No effects of developmental diet were observed for milk N, CP, DM, or GE; however, N, CP, DM, and insulin were increased (P < 0.05) on day 1 compared with day 14. A total of 61 different milk OS were identified. Milk OS profile was significantly different for neutral and acidic OS (P < 0.05) on day 0, but there were no significant differences on day 14. For piglet GLP-2, a treatment by day interaction was observed (P < 0.009); specifically, on day 1 GLP concentrations were greater (P < 0.001) in CTL+ compared with RESTR (6.73 vs. 1.21 ng/mL). For serum insulin, a treatment by day interaction was observed (P < 0.01); specifically, insulin in RESTR progeny was greater (P < 0.03) than CTL on day 1. In conclusion, nutritional management of the developing gilt may affect milk nutrient composition, milk OS profile, and piglet serum biomarkers.

Effect of diet type and added copper on growth performance, carcass characteristics, energy digestibility, gut morphology, and mucosal mRNA expression of finishing pigs

A total of 757 pigs (PIC 337 × 1050; initially 27.6 kg BW) were used in a 117-d experiment to determine the effects of added Cu from tribasic copper chloride and diet type on growth performance, carcass characteristics, energy digestibility, gut morphology, and mucosal mRNA expression of finishing pigs. Pens of pigs were allotted to 1 of 4 dietary treatments, balanced on average pen weight in a randomized complete block design with 26 to 28 pigs per pen and 7 replications per treatment. Treatments were arranged in a 2 × 2 factorial with main effects of diet type, a corn-soybean meal-based diet (corn-soy) or a high by-product diet (by-product) with 30% distillers dried grains with solubles (DDGS) and 15% bakery meal, and added Cu (0 or 150 mg/kg added Cu). There were no Cu × diet type interactions for growth performance. Overall, neither added Cu nor diet type influenced growth performance. However, caloric efficiency was decreased (P = 0.001) for pigs fed the by-product diet compared to the corn-soy diet. Pigs fed the by-product diet had decreased (P < 0.05) carcass yield and carcass G:F) and marginally decreased (P < 0.07) HCW and carcass ADG compared to pigs fed the corn-soy diet. A Cu × diet type interaction (P < 0.05) existed for DM and GE digestibility during the early finishing period as added Cu improved (P < 0.05) digestibility of DM and GE in the corn-soy diet, but not in the by-product diet. During the late finishing period, added Cu marginally increased (P = 0.060) DM and GE digestibility while pigs fed the by-product diet had decreased DM and GE digestibility (P = 0.001) compared to those fed the corn-soy diet. For gut morphology, pigs fed added Cu had decreased crypt depth (P = 0.017) in the distal small intestine compared to those fed no added Cu. Furthermore, relative mRNA expression of intestinal fatty acid binding protein (iFABP) was decreased (P = 0.032) in pigs fed added Cu compared to those fed no added Cu. In summary, adding 150 mg/kg added Cu or including 30% DDGS and 15% bakery meal into a corn-soy diet did not influence growth performance. However, HCW ADG and HCW G:F were reduced in pigs fed the by-product diet compared to the corn-soy diet. Only minor differences in gut morphology or mRNA expression were observed from feeding diets with high levels of Cu or by-products compared to a corn-soy diet.

Oral Bifidobacterium longum expressing GLP-2 improves nutrient assimilation and nutritional homeostasis in mice

Bifidobacterium has been developed for the oral delivery of peptides and has the added beneficial effect on our bodies through its probiotic properties. Here, we utilize Bifidobacterium as a delivery system to orally deliver Glucagon like peptide-2 (GLP-2). We constructed vector derived from pET-31b(+) to construct a Bifidobacterium longum expressing GLP-2. We then determined the bioactivity of recombinant Bifidobacterium in Caco-2 cells. Finally, we quantified newly synthesized ApoB48 and chylomicron production in mice infused with exogenous GLP-2 or Bifidobacterium expressing GLP-2. Results based on secretion of the triglyceride (TG)-rich lipoprotein (TRL)-ApoB48 and secretion of chylomicron revealed that recombinant Bifidobacterium was efficient in treating intestinal dysfunction,suggesting an alternative way to use Bifidobacterium as a delivery system to deliver GLP-2 for gastrointestinal nutrition coordination.

Therapeutic effects of different doses of polyethylene glycosylated porcine glucagon-like peptide-2 on ulcerative colitis in male rats

BACKGROUND

Polyethylene glycosylated (PEGylated) porcine glucagon-like peptide-2 (pGLP-2) considerably increases half-life and stability compared with the native pGLP-2, but the effective dose for intestinal damage is still unclear. This study aims to evaluate the available dose of polyethylene glycosylated porcine glucagon-like peptide-2 (PEG-pGLP-2), a modified, long-acting form of pGLP-2 in an experimental rat model of ulcerative colitis.

METHODS

Thirty-five male rats were randomly assigned into five groups: control, dextran sodium sulphate (DSS), DSS + PEG-pGLP-2(L), DSS + PEG-pGLP-2(M) and DSS + PEG-pGLP-2(H). Rats in control group received only water; other rats were fed with 5% (w/v) DSS and intraperitoneally administered with 12.5, 25 and 100 nmol/kg PEG-pGLP-2 daily for 6 days.

RESULTS

Compared with the control treatment, DSS treatment significantly (p < 0.05) decreased body weight change, colonic length, duodenal villus height and expression of zonula occludens-1, whereas significantly (p < 0.05) increased colonic damage score and expression of claudin-1, interleukin (IL)-1, IL-7, IL-10, interferon-γ and tumour necrosis factor (TNF)-α in colon. However, the three doses of PEG-pGLP-2 all reduced these effects; these treatments significantly (p < 0.05) increased body weight change and duodenal villus height, whereas significantly (p < 0.05) decreased colonic damage score and expression of IL-1, IL-7 and TNF-α in colon. Specifically, low-dose (12.5 nmol/kg/d) PEG-pGLP-2 was effective.

CONCLUSIONS

These results indicated that PEG-pGLP-2 is a novel and potentially effective therapy for intestinal healing in a relatively low dose.

Generation of glucagon-like peptide-2-expressing Saccharomyces cerevisiae and its improvement of the intestinal health of weaned rats

We aimed to assess the feasibility of enhancing the intestinal development of weaned rats using glucagon-like peptide-2 (GLP-2)-expressing Saccharomyces cerevisiae (S. cerevisiae). GLP-2-expressing S. cerevisiae (GLP2-SC) was generated using a recombinant approach. The diet of weaned rats was supplemented with the GLP2-SC strain. The average daily gain (ADG), the intestinal morphology and the activities of the digestive enzymes in the jejunum were tested to assess the influence of the GLP2-SC strain on intestinal development. The proliferation of rat enterocytes was also assessed in vitro. The study revealed that the ADG of the weaned rats that received GLP2-SC was significantly greater than that of the controls fed a basal diet (Control) and S. cerevisiae harbouring an empty vector (EV-SC) (P < 0.05) but was equivalent to that of positive control rats fed recombinant human GLP-2 (rh-GLP2) (P > 0.05). Furthermore, GLP2-SC significantly increased villous height (P < 0.01) and digestive enzyme activity (P < 0.05) in the jejunum. Immunohistochemistry analysis further affirmed that enterocyte proliferation was stimulated in rats fed the GLP2-SC strain, as indicated by the greater number of enterocytes stained with proliferative cell nuclear antigen (P < 0.05). In vitro, the proliferation of rat enterocytes was also stimulated by GLP-2 expressed by the GLP2-SC strain (P < 0.01). Herein, the combination of the GLP-2 approach and probiotic delivery constitute a possible dietary supplement for animals after weaning.

Endocrine regulation of gut maturation in early life in pigs

After birth, the newborn must adapt to the acute challenges of circulatory changes, active respiration, thermoregulation, microbial colonization, and enteral nutrition. Whereas these processes normally occur without clinical complications in neonates born at term, birth at a preterm state of gestation is associated with high morbidity and mortality. In commercial pig production, perinatal mortality is higher than in any other mammalian species. Asphyxia, hypothermia, hypoglycemia, sepsis, and gut dysmotility, represent some of the most common findings. The intestine is a particularly sensitive organ after birth, as it must adapt acutely to enteral nutrition and microbial colonization. Likewise, during the weaning phase, the intestine must adapt to new diet types. Both critical phases are associated with high morbidity. This review focuses on the endocrine changes occurring around birth and weaning. There are a number of endocrine adaptations in late gestation and early postnatal life that are under influence of development stage and environmental factors such as diet. The review discusses general endocrine changes in perinatal life but specifically focuses on the role of glucagon-like peptide-2. This gut-derived hormone plays a key role in development and function of the intestine in early life.

Glucagon-like peptide 2 and its beneficial effects on gut function and health in production animals

Numerous endocrine cell subtypes exist within the intestinal mucosa and produce peptides contributing to the regulation of critical physiological processes including appetite, energy metabolism, gut function, and gut health. The mechanisms of action and the extent of the physiological effects of these enteric peptides are only beginning to be uncovered. One peptide in particular, glucagon-like peptide 2 (GLP-2) produced by enteroendocrine L cells, has been fairly well characterized in rodent and swine models in terms of its ability to improve nutrient absorption and healing of the gut after injury. In fact, a long-acting form of GLP-2 recently has been approved for the management and treatment of human conditions like inflammatory bowel disease and short bowel syndrome. However, novel functions of GLP-2 within the gut continue to be demonstrated, including its beneficial effects on intestinal barrier function and reducing intestinal inflammation. As knowledge continues to grow about GLP-2's effects on the gut and its mechanisms of release, the potential to use GLP-2 to improve gut function and health of food animals becomes increasingly more apparent. Thus, the purpose of this review is to summarize: (1) the current understanding of GLP-2's functions and mechanisms of action within the gut; (2) novel applications of GLP-2 (or stimulators of its release) to improve general health and production performance of food animals; and (3) recent findings, using dairy calves as a model, that suggest the therapeutic potential of GLP-2 to reduce the pathogenesis of intestinal protozoan infections.

Rapid gut growth but persistent delay in digestive function in the postnatal period of preterm pigs

Preterm infants often tolerate full enteral nutrition a few weeks after birth but it is not known how this is related to gut maturation. Using pigs as models, we hypothesized that intestinal structure and digestive function are similar in preterm and term individuals at 3-4 wk after birth and that early enteral nutrition promotes maturation. Preterm or term cesarean-delivered pigs were fed total parenteral nutrition, or partial enteral nutrition [Enteral (Ent), 16-64 ml·kg(-1)·day(-1) of bovine colostrum] for 5 days, followed by full enteral milk feeding until day 26 The intestine was collected for histological and biochemical analyses at days 0, 5, and 26 (n = 8-12 in each of 10 treatment groups). Intestinal weight (relative to body weight) was reduced in preterm pigs at 0-5 days but ENT feeding stimulated the mucosal volume and peptidase activities. Relative to term pigs, mucosal volume remained reduced in preterm pigs until 26 days although plasma glucagon-like peptide 2 (GLP-2) and glucose-dependent insulin-trophic peptide (GIP) levels were increased. Preterm pigs also showed reduced hexose absorptive capacity and brush-border enzyme (sucrase, maltase) activities at 26 days, relative to term pigs. Intestinal structure shows a remarkable growth adaptation in the first week after preterm birth, especially with enteral nutrition, whereas some digestive functions remain immature until at least 3-4 wk. It is important to identify feeding regimens that stimulate intestinal maturation in the postnatal period of preterm infants because some intestinal functions may show long-term developmental delay.

COMPARATIVE GUT PHYSIOLOGY SYMPOSIUM: Comparative physiology of glucagon-like peptide-2: Implications and applications for production and health of ruminants

Glucagon-like peptide-2 (GLP-2) is a 33-amino acid peptide derived from proteolytic cleavage of proglucagon by prohormone convertase 1/3 in enteroendocrine L cells. Studies conducted in humans, in rodent models, and in vitro indicate that GLP-2 is secreted in response to the presence of molecules in the intestinal lumen, including fatty acids, carbohydrates, amino acids, and bile acids, which are detected by luminal chemosensors. The physiological actions of GLP-2 are mediated by its G protein-coupled receptor expressed primarily in the intestinal tract on enteric neurons, enteroendocrine cells, and myofibroblasts. The biological activity of GLP-2 is further regulated by dipeptidyl peptidase IV, which rapidly cleaves the N-terminus of GLP-2 that is responsible for GLP-2 receptor activation. Within the gut, GLP-2 increases nutrient absorption, crypt cell proliferation, and mesenteric blood flow and decreases gut permeability and motility, epithelial cell apoptosis, and inflammation. Outside the gut, GLP-2 reduces bone resorption, can suppress appetite, and is cytoprotective in the lung. Thus, GLP-2 has been studied intensively as a therapeutic to improve intestinal function of humans during parenteral nutrition and following small bowel resection and, more recently, as a treatment for osteoporosis and obesity-related disorders and to reduce cellular damage associated with inflammation of the gut and lungs. Recent studies demonstrate that many biological actions and properties of GLP-2 in ruminants are similar to those in nonruminants, including the potential to reduce intestinal nitro-oxidative stress in calves caused by parasitic diseases such as coccidiosis. Because of its beneficial impacts on nutrient absorption, gut healing, and normal gut development, GLP-2 therapy offers significant opportunities to improve calf health and production efficiency. However, GLP-2 therapies require an extended time course to achieve desired physiological responses, as well as daily administration because of the hormone's short half-life. Thus, practical means of administration and alternative strategies to enhance basal GLP-2 secretion (e.g., through specific feed additives), which are more likely to achieve consumer acceptance, are needed. Opportunities to address these challenges are discussed.

Effects of a Tripeptide Iron on Iron-Deficiency Anemia in Rats

This study aims to investigate the effects of a tripeptide iron (REE-Fe) on iron-deficiency anemia rats. Sprague-Dawley rats were randomly divided into seven groups: a normal control group, an iron-deficiency control group, and iron-deficiency groups treated with ferrous sulfate (FeSO4), ferrous glycinate (Fe-Gly), or REE-Fe at low-, medium-, or high-dose groups. The rats in the iron-deficiency groups were fed on an iron-deficient diet to establish iron-deficiency anemia (IDA) model. After the model established, different iron supplements were given to the rats once a day by intragastric administration for 21 days. The results showed that REE-Fe had effective restorative action returning body weight, organ coefficients, and hematological parameters in IDA rats to normal level. In addition, comparing with FeSO4 or Fe-Gly, high-dose REE-Fe was more effective on improving the levels of renal coefficient, total iron-binding capacity, and transferrin. Furthermore, the liver hepcidin messenger RNA (mRNA) expression in the high-dose group was significantly higher (p < 0.05) than that in the FeSO4 or Fe-Gly group and showed no significant difference (p > 0.05) with the normal control group. The findings suggest that REE-Fe is an effective source of iron supplement for IDA rats and might be exploited as a new iron fortifier.

The Effects of Glucagon-like Peptide-2 on the Tight Junction and Barrier Function in IPEC-J2 Cells through Phosphatidylinositol 3-kinase-Protein Kinase B-Mammalian Target of Rapamycin Signaling Pathway

Glucagon-like peptide-2 (GLP-2) is important for intestinal barrier function and regulation of tight junction (TJ) proteins, but the intracellular mechanisms of action remain undefined. The purpose of this research was to determine the protective effect of GLP-2 mediated TJ and transepithelial electrical resistance (TER) in lipopolysaccharide (LPS) stressed IPEC-J2 cells and to test the hypothesis that GLP-2 regulate TJ and TER through the phosphatidylinositol 3-kinase (PI3K)-protein kinase B (Akt)-mammalian target of rapamycin (mTOR) signaling pathway in IPEC-J2 cells. Wortmannin and LY294002 are specific inhibitors of PI3K. The results showed that 100 μg/mL LPS stress decreased TER and TJ proteins occludin, claudin-1 and zonula occludens protein 1 (ZO-1) mRNA, proteins expressions (p<0.01) respectively. GLP-2 (100 nmol/L) promote TER and TJ proteins occludin, claudin-1, and zo-1 mRNA, proteins expressions in LPS stressed and normal IPEC-J2 cells (p<0.01) respectively. In normal cells, both wortmannin and LY294002, PI3K inhibitors, prevented the mRNA and protein expressions of Akt and mTOR increase induced by GLP-2 (p<0.01) following with the significant decreasing of occludin, claudin-1, ZO-1 mRNA and proteins expressions and TER (p<0.01). In conclusion, these results indicated that GLP-2 can promote TJ’s expression and TER in LPS stressed and normal IPEC-J2 cells and GLP-2 could regulate TJ and TER through the PI3K/Akt/mTOR pathway.

Glucagon-like peptide-2-loaded microspheres as treatment for ulcerative colitis in the murine model

Glucagon-like peptide-2 (GLP-2) is an intestinal hormone that promotes intestinal growth, but the rapid degradation by dipeptidyl peptidase-IV limits its applications. PLGA microsphere is a well-developed drug delivery system, while seldom been studied as a solution for prolonging in vivo effects of GLP-2. In this study, we encapsulated porcine GLP-2 (pGLP-2) into microspheres and investigated its therapeutic effects in dextran sulfate sodium (DSS)-treated mice. pGLP-2 microspheres showed 20.36% in initial burst and constant release for at least 9 d. In the DSS-treated mice, a single injection of GLP-2 microspheres significantly increased the body weight, colonic length, small intestinal weight and mRNA expression of Occludin, decreased the colonic damage score, mRNA expression of IL-6, IL-10, TNF-α and IFN-γ. In conclusion, pGLP-2 microspheres were resistant to degradation and decreased the severity of DSS-induced ulcerative colitis which suggested that GLP-2-loaded microspheres could be a proper candidate for the treatment of ulcerative colitis.

Bile acid mediated effects on gut integrity and performance of early-weaned piglets

Background

Early weaning (EW) results in a transient period of impaired integrity of the intestinal mucosa that may be associated with reduced plasma concentration of glucagon-like peptide-(GLP) 2. We have previously shown that intragastric infusion of chenodeoxycholic acid (CDC) increases circulating GLP-2 in early-weaned piglets. The aim of this study was to expand previous work to establish whether feeding piglets a cereal-based diet supplemented with CDC can improve gut integrity and animal performance immediately after EW. A cohort of 36 piglets weaned at 20 days of age, 6.2 ± 0.34 kg of body weight (BW) were randomly assigned (n = 18) to receive a standard prestarter diet or the same diet supplemented with 60 mg of CDC per kg of initial BW for ad libitum intake until day 14 postweaning. Thereafter, all pigs were fed the same untreated starter diet for 21 days until the end of the study on day 35. On days 1, 7 and 14 blood samples were collected from 6 pigs per treatment to measure plasma GLP-2. On day 15, 6 pigs per treatment were euthanized to obtain intestinal tissue samples for later histological and gene expression analyses.

Results

Supplementing the diet with CDC tended to increase plasma GLP-2 (P < 0.07; 39 %) and the weight of the large intestine (P < 0.10; 11 %), and increased ileal crypt depth (P < 0.04; 15 %) after 14 days of treatment exposure. Although feed intake and BW gain were not affected by treatments, feeding CDC induced the expression of the cytokines TNF-α (P < 0.02; 1.9 fold), IL-6 (P < 0.01; 2.4 fold), and IL-10 (P < 0.006; 2.2 fold) and the tight junctional protein ZON-1 (P < 0.02; 1.5 fold) in the distal small intestine.

Conclusions

This study showed that the oral administration of CDC to early-weaned pigs has the potential to improve the protection of the intestinal mucosa independently of relevant changes in gut growth.

PEGylated porcine glucagon-like peptide-2 improved the intestinal digestive function and prevented inflammation of weaning piglets challenged with LPS

This study was conducted to determine the effects on intestinal function, anti-inflammatory role and possible mechanism of polyethylene glycosylated (PEGylated) porcine glucagon-like peptide-2 (pGLP-2), a long-acting form of pGLP-2, in weaning piglets challenged with Escherichia coli lipopolysaccharide (LPS). We divided 18 weaned piglets on day 21 into three groups (control, LPS and LPS+PEG-pGLP-2; n=6). The piglets from the LPS+PEG-pGLP-2 group were injected with PEG-pGLP-2 at 10 nmol/kg BW from 5 to 7 days of the trials daily. On 8th day, the piglets in the LPS and LPS+PEG-pGLP-2 groups were intraperitoneally administered with 100 µg LPS/kg. The control group was administered with the same volume of saline solution. The piglets were then sacrificed on day 28. Afterwards, serum, duodenum, jejunum and ileum samples were collected for analysis of structural and functional endpoints. LPS+PEG-pGLP-2 treatment increased (P<0.05) lactase activities in the duodenum and the jejunum compared with LPS treatment. LPS+PEG-pGLP-2 treatment also significantly increased sucrase activity in the jejunum compared with LPS treatment. Furthermore, LPS treatment increased (P<0.05) the mRNA expression levels of interleukin (IL)-8, tumour necrosis factor-α (TNF-α) and IL-10 in the ileum compared with the control treatment. By contrast, LPS+PEG-pGLP-2 treatment decreased (P<0.05) the mRNA expression levels of IL-8, IL-10 and TNF-α in the ileum compared with the LPS treatment. LPS treatment also increased (P<0.05) the mRNA expression level of GLP-2 receptor (GLP-2R) and the percentage of GLP-2R-positive cells in the ileum; by comparison, these results were (P<0.05) reduced by LPS+PEG-pGLP-2 treatment. Moreover, LPS+PEG-pGLP-2 treatment increased (P<0.05) the content of serum keratinocyte growth factor compared with the control group and the LPS group. The protective effects of PEG-pGLP-2 on intestinal digestive function were associated with the release of GLP-2R mediator (keratinocyte growth factor) and the decrease in the expressions of intestinal pro-inflammatory cytokines.

Animal models of gastrointestinal and liver diseases. Animal models of infant short bowel syndrome: translational relevance and challenges

Intestinal failure (IF), due to short bowel syndrome (SBS), results from surgical resection of a major portion of the intestine, leading to reduced nutrient absorption and need for parenteral nutrition (PN). The incidence is highest in infants and relates to preterm birth, necrotizing enterocolitis, atresia, gastroschisis, volvulus, and aganglionosis. Patient outcomes have improved, but there is a need to develop new therapies for SBS and to understand intestinal adaptation after different diseases, resection types, and nutritional and pharmacological interventions. Animal studies are needed to carefully evaluate the cellular mechanisms, safety, and translational relevance of new procedures. Distal intestinal resection, without a functioning colon, results in the most severe complications and adaptation may depend on the age at resection (preterm, term, young, adult). Clinically relevant therapies have recently been suggested from studies in preterm and term PN-dependent SBS piglets, with or without a functional colon. Studies in rats and mice have specifically addressed the fundamental physiological processes underlying adaptation at the cellular level, such as regulation of mucosal proliferation, apoptosis, transport, and digestive enzyme expression, and easily allow exogenous or genetic manipulation of growth factors and their receptors (e.g., glucagon-like peptide 2, growth hormone, insulin-like growth factor 1, epidermal growth factor, keratinocyte growth factor). The greater size of rats, and especially young pigs, is an advantage for testing surgical procedures and nutritional interventions (e.g., PN, milk diets, long-/short-chain lipids, pre- and probiotics). Conversely, newborn pigs (preterm or term) and weanling rats provide better insights into the developmental aspects of treatment for SBS in infants owing to their immature intestines. The review shows that a balance among practical, economical, experimental, and ethical constraints will determine the choice of SBS model for each clinical or basic research question.