Short-chain fatty acids increase proglucagon and ornithine decarboxylase messenger RNAs after intestinal resection in rats

Microbiome analysis reveals gut microbiota alteration of early-weaned Yimeng black goats with the effect of milk replacer and age

Background

Colonization of intestinal microbiota in ruminant during the early life is important to host health, metabolism and immunity. Accumulating evidence revealed the ameliorative effect of milk replacer administration in the gut microbial development of early-weaned ruminants. Yimeng black goats (YBGs) inhabiting Shandong, China show a complex intestinal microbial ecosystem, but studies of their gut microbiota are still insufficient to report. Here, this study was performed to investigate how the gut microbiota develops in weaned YBGs with the effect of age and milk replacer.

Results

Results indicated that both age and milk replacer were important factors to change the gut microbiota of YBGs. Although the alpha diversity of gut microbiota did not change with the age of YBGs, the taxonomic compositions significantly changed. The relative abundance of some beneficial bacteria such as Lachnospiraceae, Ruminococcaceae, Ruminiclostridium, Eubacterium and Barnesiella significantly decreased and subsequently increase with age, which contributes to maintain the stability of intestinal environment and realize the diversity of intestinal functions. The relative abundance of Porphyromonas, Brevundimonas, Flavobacterium, Stenotrophomonas, Propionibacterium, Acinetobacter, Enterococcus and Clostridium belong to pathogenic bacteria in milk replacer-treated YBGs was significantly decreased. Additionally, some beneficial bacteria such as Ruminococcus, Ruminococcaceae, Christensenellaceae and Ruminiclostridium also display a trend of decreasing first followed by gradually increasing.

Conclusions

This study first revealed the gut bacterial community alterations in YBGs with the effect of age and milk replacer. This study also characterized the gut microbial distribution in YBGs with different ages and provided better insight into microbial population structure and diversity of YBGs. Moreover, milk replacer may serve as a good applicant for improving gut microbial development in early-weaned YBGs.

Short Bowel Syndrome: A Paradigm for Intestinal Adaptation to Nutrition?

Short bowel syndrome (SBS) is a rare disease that results from extensive resection of the intestine. When the remaining absorption surface of the intestine cannot absorb enough macronutrients, micronutrients, and water, SBS results in intestinal failure (IF). Patients with SBS who suffer from IF require parenteral nutrition for survival, but long-term parenteral nutrition may lead to complications such as catheter sepsis and metabolic diseases. Spontaneous intestinal adaptation occurs weeks to months after resection, resulting in hyperplasia of the remnant gut, modification of gut hormone levels, dysbiosis, and hyperphagia. Oral nutrition and presence of the colon are two major positive drivers for this adaptation. This review aims to summarize the current knowledge of the mechanisms underlying spontaneous intestinal adaptation, particularly in response to modifications of luminal content, including nutrients. In the future, dietary manipulations could be used to treat SBS.

Six-month outcomes of teduglutide treatment in adult patients with short bowel syndrome with chronic intestinal failure: A real-world French observational cohort study

BACKGROUND & AIMS

Teduglutide, a GLP-2-analog, has proven effective in two placebo-controlled studies in reducing parenteral support (PS) in patients with short bowel syndrome-associated intestinal failure (SBS-IF) after 24 weeks. The aim of this study was to describe in a real-life situation the effects of teduglutide treatment and their predictive factors.

METHODS

We included 54 consecutive SBS-IF patients treated with teduglutide in France for at least 6 months from 10 expert centers. Small bowel length was 62 ± 6 cm and 65% had colon in continuity. PS was 4.4 ±0 .2 infusions per week, started 9.8 ± 1.2 years before. Response (PS reduction ≥ 20%) and PS discontinuation rates were assessed at week 24. Adjusted p values of factors associated with response and weaning were calculated using a multivariate logistic regression model.

RESULTS

At week 24, 85% of patients were responders and 24% had been weaned off PS, with a 51% reduction of PS needs and 1.5 ± 0.2 days off PS per week. Response to teduglutide was influenced by a higher baseline oral intake (p = 0.02). Weaning off PS was influenced by the presence of colon (p = 0.04), a lower PS volume (p = 0.03) and a higher oral intake (p = 0.01). There were no differences based on age, bowel length or SBS-IF causes.

CONCLUSIONS

Our study confirms the effectiveness of teduglutide in reducing PS needs in SBS-IF patients. We associated reduced parenteral support volume with baseline parenteral volume support, bowel anatomy, and oral intake. These findings underline the role of nutritional optimization when starting the treatment.

Emerging treatments for short bowel syndrome in adult patients

Short bowel syndrome (SBS) is the major cause of chronic intestinal failure (IF), defined as 'the reduction of gut function below the minimum necessary for the absorption of macronutrients and/or water and electrolytes, such that intravenous supplementation is required to maintain health and/or growth'. Areas covered: Spontaneous intestinal adaptation, including increased hormonal secretion, development of hyperphagia and gut microbiota dysbiosis, occurs 2 years after resection, improving intestinal absorption and decreasing PN dependency. Hormonal treatments, promoting intestinal hyperadaptation, have been proposed in patients with SBS with chronic IF. Clinical studies showed teduglutide to increase urine production and reduce the need for parenteral support volume in these patients. According to the latest ESPEN Guidelines, if a growth factor treatment is considered, the GPL2 analog, teduglutide, should be the first-choice treatment. Expert opinion: These therapies underline the importance of patient monitoring at home and the complexity for HPN adaptation. A multidisciplinary approach should be a gold standard.

Cereal fructan extracts alter intestinal fermentation to reduce adiposity and increase mineral retention compared to oligofructose

PURPOSE

Intestinal fermentation of inulin-type fructans, including oligofructose, can modulate adiposity, improve energy regulation, and increase mineral absorption. We aimed to determine whether cereal fructans had greater effects on reducing adiposity and improving mineral absorption compared with oligofructose.

METHODS

Thirty-two male Sprague-Dawley rats were randomly assigned to one of four dietary treatments that contained 0% fructan (control), or 5% fructan provided by oligofructose (OF), a barley grain fraction (BGF), or a wheat stem fraction (WSF). After 1 week on the diets, mineral absorption and retention was assessed. At 4 weeks, blood samples were collected for gut hormone analysis, adipose depots were removed and weighed, and caecal digesta was analyzed for pH and short-chain fatty acids (SCFA).

RESULTS

The BGF and WSF, but not OF, had lower total visceral fat weights than the Control (p < 0.05). The fructan diets all lowered caecal pH and raised caecal digesta weight and total SCFA content, in comparison to the Control. Caecal propionate levels for OF were similar to the Control and higher for WSF (p < 0.05). Plasma peptide YY and glucagon-like peptide-1 levels were elevated for all fructan groups when compared to Control (p < 0.001) and gastric inhibitory peptide was lower for the WSF compared to the other groups (p < 0.05). The fructan diets improved calcium and magnesium retention, which was highest for WSF (p < 0.05). BGF and WSF in comparison to OF showed differential effects on fermentation, gut hormone levels, and adiposity.

CONCLUSIONS

Cereal fructan sources have favorable metabolic effects that suggest greater improvements in energy regulation and mineral status to those reported for oligofructose.

Butyrate stimulates the growth of human intestinal smooth muscle cells by activation of yes-associated protein

Intestinal smooth muscle cells play a critical role in the remodeling of intestinal structure and functional adaptation after bowel resection. Recent studies have shown that supplementation of butyrate (Bu) contributes to the compensatory expansion of a muscular layer of the residual intestine in a rodent model of short-bowel syndrome (SBS). However, the underlying mechanism remains elusive. In this study, we found that the growth of human intestinal smooth muscle cells (HISMCs) was significantly stimulated by Bu via activation of Yes-Associated Protein (YAP). Incubation with 0.5 mM Bu induced a distinct proliferative effect on HISMCs, as indicated by the promotion of cell cycle progression and increased DNA replication. Notably, YAP silencing by RNA interference or its specific inhibitor significantly abolished the proliferative effect of Bu on HISMCs. Furthermore, Bu induced YAP expression and enhanced the translocation of YAP from the cytoplasm to the nucleus, which led to changes in the expression of mitogenesis genes, including TEAD1, TEAD4, CTGF, and Cyr61. These results provide evidence that Bu stimulates the growth of human intestinal muscle cells by activation of YAP, which may be a potential treatment for improving intestinal adaptation.

Nutritional strategies to enhance adaptation in intestinal failure

PURPOSE OF REVIEW

This article summarizes the current and potential future nutritional approaches to stimulate adaptation in intestinal failure. Adaptation in this context usually refers to intestinal adaptation but also involves changes in whole body physiology as well as in eating/drinking behavior.

RECENT FINDINGS

Adaptation largely depends on residual functional anatomy. Luminal exposure to complex nutrients is the most important trigger for intestinal adaptation. Enteral fat as well as enteral or parenteral short chain fatty acids have a specific stimulatory effect. Zinc and vitamin A status need to be optimized for adaptation to proceed and be maintained. In the context of maintaining sodium and water homeostasis, flushing the remnant intestine because of uncontrolled thirst/drinking must be avoided. Complications of nutritional care such as malnutrition, intestinal failure-associated liver disease, and recurrent line sepsis also need optimal management.

SUMMARY

Stimulation by luminal nutrients as well as prophylaxis against and treatment of (nutritional) complications are the cornerstones of adaptation to the short bowel situation. Based on ample data from animal studies but only limited evidence in humans specific nutritional stimulators need to be studied more rigorously. As long as such data are missing they can be tried on an individual basis.

Gut microbiota, obesity and diabetes

The central role of the intestinal microbiota in the progression and, equally, prevention of metabolic dysfunction is becoming abundantly apparent. The symbiotic relationship between intestinal microbiota and host ensures appropriate development of the metabolic system in humans. However, disturbances in composition and, in turn, functionality of the intestinal microbiota can disrupt gut barrier function, a trip switch for metabolic endotoxemia. This low-grade chronic inflammation, brought about by the influx of inflammatory bacterial fragments into circulation through a malfunctioning gut barrier, has considerable knock-on effects for host adiposity and insulin resistance. Conversely, recent evidence suggests that there are certain bacterial species that may interact with host metabolism through metabolite-mediated stimulation of enteric hormones and other systems outside of the gastrointestinal tract, such as the endocannabinoid system. When the abundance of these keystone species begins to decline, we see a collapse of the symbiosis, reflected in a deterioration of host metabolic health. This review will investigate the intricate axis between the microbiota and host metabolism, while also addressing the promising and novel field of probiotics as metabolic therapies.

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.

Pathobiology and potential therapeutic value of intestinal short-chain fatty acids in gut inflammation and obesity

BACKGROUND

The lumen of the gastrointestinal tract contains many substances produced from the breakdown of foodstuffs, from salivary, esophageal, intestinal, hepatic, and pancreatic secretions, and from sloughed cells present in the gastrointestinal lumen. Although these substances were traditionally regarded as waste products, there is increasing realization that many can be biologically active, either as signalling compounds or as nutrients. For example, proteins are broken down into amino acids, which are then sensed by nutrient receptors. The gut microbiome, which is at highest abundance in the ileocecum, has powerful metabolic activity, digesting and breaking down unabsorbed carbohydrates, proteins, and other ingested nutrients into phenols, amines, volatile organic compounds, methane, carbon dioxide, hydrogen, and hydrogen sulfide into volatile fatty acids, also called short-chain fatty acids (SCFAs).

CONCLUSION

These latter substances are the topic of this review. In this review, we will briefly discuss recent advances in the understanding SCFA production, signalling, and absorption, followed by a detailed description and discussion of trials of SCFAs, probiotics, and prebiotics in the treatment of gastrointestinal disease, in particular ulcerative colitis (UC), pouchitis, short bowel syndrome, and obesity.

Intestinal microbiology in early life: specific prebiotics can have similar functionalities as human-milk oligosaccharides

Human milk is generally accepted as the best nutrition for newborns and has been shown to support the optimal growth and development of infants. On the basis of scientific insights from human-milk research, a specific mixture of nondigestible oligosaccharides has been developed, with the aim to improve the intestinal microbiota in early life. The mixture has been extensively studied and has been shown to be safe and to have potential health benefits that are similar to those of human milk. The specific mixture of short-chain galacto-oligosaccharides and long-chain fructo-oligosaccharides has been found to affect the development of early microbiota and to increase the Bifidobacterium amounts as observed in human-milk-fed infants. The resulting gut ecophysiology is characterized by high concentrations of lactate, a slightly acidic pH, and specific short-chain fatty acid profiles, which are high in acetate and low in butyrate and propionate. Here, we have summarized the main findings of dietary interventions with these specific oligosaccharides on the gut microbiota in early life. The gut ecophysiology in early life may have consequences for the metabolic, immunologic, and even neurologic development of the child because reports increasingly substantiate the important function of gut microbes in human health. This review highlights major findings in the field of early gut colonization and the potential impact of early nutrition in healthy growth and development.

A review of enteral strategies in infant short bowel syndrome: evidence-based or NICU culture?

INTRODUCTION

Short bowel syndrome (SBS) is an increasingly common condition encountered across neonatal intensive care units. Improvements in parenteral nutrition (PN), neonatal intensive care and surgical techniques, in addition to an improved understanding of SBS pathophysiology, have contributed in equal parts to the survival of this fragile subset of infants. Prevention of intestinal failure associated liver disease (IFALD) and promotion of intestinal adaptation are primary goals of all involved in the care of these patients. While enteral nutritional and pharmacological strategies are necessary to achieve these goals, there remains great variability in the application of therapeutic strategies in units that are not necessarily evidence-based.

MATERIALS AND METHODS

A search of major English language medical databases (SCOPUS, Index Medicus, Medline, and the Cochrane database) was conducted for the key words short bowel syndrome, medical management, nutritional management and intestinal adaptation. All pharmacological and nutritional agents encountered in the literature search were classified based on their effects on absorptive capacity, intestinal adaptation and bowel motility that are the three major strategies employed in the management of SBS. The Oxford Center for Evidence-Based Medicine (CEBM) classification for levels of evidence was used to develop grades of clinical recommendation for each variable studied.

RESULTS

We reviewed various medications used and nutritional strategies included soluble fiber, enteral fat, glutamine, probiotics and sodium supplementation. Most interventions have scientific rationale but little evidence to support their role in the management of infant SBS. While some of these agents symptomatically improve diarrhea, they can adversely influence pancreatico-biliary function or actually impair intestinal adaptation. Surgical anatomy and liver function are two important variables that should determine the selection of pharmacological and nutritional interventions.

DISCUSSION

There is a paucity of research investigating optimal clinical practice in infant SBS and the little evidence available is consistently of lower quality, resulting in a wide variation of clinical practices among NICUs. Prospective trials should be encouraged to bridge the evidence gap between research and clinical practice to promote further progress in the field.

Activation of enteroendocrine membrane progesterone receptors promotes incretin secretion and improves glucose tolerance in mice

Glucagon-like peptide-1 (GLP-1) secretion is classically regulated by ingested nutrients. To identify novel molecular targets controlling incretin secretion, we analyzed enteroendocrine cell pathways important for hormone biosynthesis and secretion. We demonstrate that progesterone increases GLP-1 secretion and extracellular signal-related kinase 1/2 (ERK1/2) phosphorylation in enteroendocrine GLUTag cells via mechanisms sensitive to the mitogen-activated protein kinase inhibitor U0126. The stimulatory effects of progesterone (P4) or the synthetic progestin R5020 on ERK1/2 phosphorylation were independent of the classical progesterone receptor antagonist RU486. Furthermore, a cell-impermeable BSA-progesterone conjugate rapidly increased ERK1/2 phosphorylation and GLP-1 secretion. Knockdown of the membrane progesterone receptors Paqr5 or Paqr7 in GLUTag cells eliminated the stimulatory effect of R5020 and progesterone on GLP-1 secretion. Enteral progesterone administration increased plasma levels of GLP-1, glucose-dependent insulinotropic polypeptide (GIP), and insulin, and improved oral glucose tolerance in an RU486-insensitve manner in mice: however, systemic progesterone exposure did not improve glucose homeostasis. Unexpectedly, the glucoregulatory actions of enteral progesterone did not require classical incretin receptor signaling and were preserved in Glp1r(-/-) and Glp1r(-/-):Gipr(-/-) mice. Intestine-restricted activation of membrane progesterone receptors may represent a novel approach for stimulation of incretin hormone secretion and control of glucose homeostasis.

Role of TCF7L2 risk variant and dietary fibre intake on incident type 2 diabetes

AIMS/HYPOTHESIS

The T allele of transcription factor 7-like 2 gene variant, TCF7L2 rs7903146, increases the risk of type 2 diabetes by 40-50%. As TCF7L2 rs7903146 has been associated with diminished incretin effect we investigated whether interaction between dietary intake of carbohydrate, fat, protein or fibre and this variant affects the risk of type 2 diabetes.

METHODS

A cohort of 24,799 non-diabetic individuals from the Malmö Diet and Cancer Study (MDCS), with dietary data obtained by a modified diet history method, were followed up for 12 years, with 1,649 recordings of incident type 2 diabetes made. Risk of type 2 diabetes in strata of diet quintiles was analysed prospectively adjusting for potential confounders. Cross-sectional analyses were performed on baseline fasting glucose and HbA(1c) levels in a subset of 5,216 randomly selected individuals from the MDCS.

RESULTS

The elevated risk of type 2 diabetes with rs7903146 (OR 1.44, 95% CI 1.33, 1.56, p = 4.6 × 10(-19)) increased with higher intake of dietary fibre (OR 1.24, 95% CI 1.04, 1.47 to OR 1.56, 95% CI 1.31, 1.86 from the lowest to highest quintile; p (interaction) = 0.049). High intake of dietary fibre was inversely associated with diabetes incidence only among CC genotype carriers (OR 0.74, 95% CI 0.58, 0.94 per quintile, p = 0.025). The T allele was associated with 0.027% elevated HbA(1c) (p = 0.02) and this effect increased with higher intake of fibre (from -0.021% to 0.079% for the lowest to the highest quintile, p (interaction) = 0.02). Each quintile of higher fibre intake was associated with lower HbA(1c) levels among CC and CT but not among TT genotype carriers (-0.036%, p = 6.5 × 10(-7); -0.023%, p = 0.009; and 0.012%, p = 0.52, respectively).

CONCLUSIONS/INTERPRETATION

Our study suggests that dietary fibre intake may modify the association between TCF7L2 rs7903146 and incidence of type 2 diabetes, and that higher fibre intake may associate with protection from type 2 diabetes only among non-risk allele carriers.

Intestinal adaptation is stimulated by partial enteral nutrition supplemented with the prebiotic short-chain fructooligosaccharide in a neonatal intestinal failure piglet model

BACKGROUND

Butyrate has been shown to stimulate intestinal adaptation when added to parenteral nutrition (PN) following small bowel resection but is not available in current PN formulations. The authors hypothesized that pre- and probiotic administration may be a clinically feasible method to administer butyrate and stimulate intestinal adaptation.

METHODS AND MATERIALS

Neonatal piglets (48 hours old, n = 87) underwent placement of a jugular catheter and an 80% jejunoileal resection and were randomized to one of the following treatment groups: control (20% standard enteral nutrition/80% standard PN), control plus prebiotic (10 g/L short-chain fructooligosaccharides [scFOS]), control plus probiotic (1 × 10(9) CFU Lactobacillus rhamnosus GG [LGG]), or control plus synbiotic (scFOS + LGG). Animals received infusions for 24 hours, 3 days, or 7 days, and markers of intestinal adaptation were assessed.

RESULTS

Prebiotic treatment increased ileal mucosa weight compared with all other treatments (P = .017) and ileal protein compared with control (P = .049), regardless of day. Ileal villus length increased in the prebiotic and synbiotic group (P = .011), regardless of day, specifically due to an increase in epithelial proliferation (P = .003). In the 7-day prebiotic group, peptide transport was upregulated in the jejunum (P = .026), whereas glutamine transport was increased in both the jejunum and colon (P = .001 and .003, respectively).

CONCLUSIONS

Prebiotic and/or synbiotic supplementation resulted in enhanced structure and function throughout the residual intestine. Identification of a synergistic prebiotic and probiotic combination may enhance the promising results obtained with prebiotic treatment alone.

Propionic acid affects immune status and metabolism in adipose tissue from overweight subjects

BACKGROUND

Adipose tissue is a primary site of obesity-induced inflammation, which is emerging as an important contributor to obesity-related diseases such as type 2 diabetes. Dietary fibre consumption appears to be protective. Short-chain fatty acids, e.g. propionic acid, are the principal products of the colonic fermentation of dietary fibre and may have beneficial effects on adipose tissue inflammation.

MATERIALS AND METHODS

Human omental adipose tissue explants were obtained from overweight (mean BMI 28·8) gynaecological patients who underwent surgery. Explants were incubated for 24 h with propionic acid. Human THP-1 monocytic cells were differentiated to macrophages and incubated with LPS in the presence and absence of propionic acid. Cytokine and chemokine production were determined by multiplex-ELISA, and mRNA expression of metabolic and macrophages genes was determined by RT-PCR.

RESULTS

Treatment of adipose tissue explants with propionic acid results in a significant down-regulation of several inflammatory cytokines and chemokines such as TNF-α and CCL5. In addition, expression of lipoprotein lipase and GLUT4, associated with lipogenesis and glucose uptake, respectively, increased. Similar effects on cytokine and chemokine production by macrophages were observed.

CONCLUSION

We show that propionic acid, normally produced in the colon, may have a direct beneficial effect on visceral adipose tissue, reducing obesity-associated inflammation and increasing lipogenesis and glucose uptake. Effects on adipose tissue as a whole are at least partially explained by effects on macrophages but likely also adipocytes are involved. This suggests that, in vivo, propionic acid and dietary fibres may have potential in preventing obesity-related inflammation and associated diseases.

Effects of different sources of fructans on body weight, blood metabolites and fecal bacteria in normal and obese non-diabetic and diabetic rats

Fructans contribute significantly to dietary fiber with beneficial effects on gastrointestinal physiology in healthy individuals and offer a promising approach to treating some diseases. Two experiments (Experiment 1 = rats with normal weight; Experiment 2 = obese rats) were developed to compare the effects of three fructan sources (Cichorium intybus L. Asteraceae, Helianthus tuberosus L. Asteraceae and Agave angustifolia ssp. tequilana Haw, Agavaceae) on body weight change, blood metabolites and fecal bacteria in non-diabetic (ND) and diabetic (D) rats. In Experiment 1 total body weight gain and daily feed intake in D and ND rats decreased (P < 0.05) with supplements of fructan. Only in D rats, blood glucose concentrations, fecal Clostrodium spp. counts, and liver steatosis decreased, while blood HDL concentrations and fecal Lactobacillus spp. and Bifidobacterium spp. counts increased due to fructans. In Experiment 2, total body weight gain and feed intake in ND and D rats were also decreased by fructans. In ND rats, fructan decreased blood glucose concentrations. In D rats, fructans from A. angustifolia ssp. tequilana decreased blood cholesterol and LDL and liver steatosis. For both ND and D rats, fecal Lactobacillus spp. and Bifidobacterium spp. counts were higher (P < 0.05) with fructan supplements.

Enteral feeding induces early intestinal adaptation in a parenterally fed neonatal piglet model of short bowel syndrome

BACKGROUND

Successful small intestinal (SI) adaptation following surgical resection is essential for optimizing newborn growth and development, but the potential for adaptation is unknown. The authors developed an SI resection model in neonatal piglets supported by intravenous and enteral nutrition.

METHODS

Piglets (n = 33, 12-13 days old) were randomized to 80% SI resection with parenteral nutrition feeding (R-PN), 80% SI resection with PN + enteral feeding (R-EN), or sham SI transection with PN + enteral feeding (sham-EN). In resected pigs, the distal 100 cm of ileum (residual SI) and 30 cm of proximal SI were left intact. All pigs received parenteral nutrition postsurgery. Enteral nutrition piglets received continuous gastric infusion of elemental diet from day 3 (40:60 parenteral nutrition:enteral nutrition). Piglets were killed 4, 6, or 10 days postsurgery.

RESULTS

By 10 days, R-EN piglets had longer residual SI than R-PN and sham-EN pigs (P < .05). At days 6 and 10, R-EN piglets had greater weight per length of intact SI (P < .05) and isolated mucosa (P < .05) compared to other groups. Greater gut weight in R-EN piglets was facilitated by a greater cellular proliferation index (P < .01) by 4 days compared to other groups and greater overall ornithine decarboxylase activity vs R-PN piglets (P < .05).

CONCLUSIONS

This new model demonstrated profound SI adaptation, initiated early postsurgery by polyamine synthesis and crypt cell proliferation and only in response to enteral feeding. These changes translated to greater gut mass and length within days, likely improving functional capacity long term.

Intestinal gene expression in pigs: effects of reduced feed intake during weaning and potential impact of dietary components

The weaning transition is characterised by morphological, histological and microbial changes, often leading to weaning-associated disorders. These intestinal changes can partly be ascribed to the lack of luminal nutrition arising from the reduced feed intake common in pigs after weaning. It is increasingly becoming clear that changes in the supply with enteral nutrients may have major impacts on intestinal gene expression. Furthermore, the major dietary constituents, i.e. carbohydrates, fatty acids and amino acids, participate in the regulation of intestinal gene expression. However, nutrients may also escape digestion by mammalian enzymes in the upper gastrointestinal tract. These nutrients can be used by the microflora, resulting in the production of bacterial metabolites, for example, SCFA, which may affect intestinal gene expression indirectly. The present review provides an insight on possible effects of reduced feed intake on intestinal gene expression, as it may occur post-weaning. Detailed knowledge on effects of reduced feed intake on intestinal gene expression may help to understand weaning-associated intestinal dysfunctions and diseases. Examples are given of intestinal genes which may be altered in their expression due to supply with specific nutrients. In that way, gene expression could be modulated by dietary means, thereby acting as a potential therapeutic tool. This could be achieved, for example, by influencing genes coding for digestive or absorptive proteins, thus optimising digestive function and metabolism, but also with regard to immune response, or by influencing proliferative processes, thereby enhancing mucosal repair. This would be of special interest when designing a diet to overcome weaning-associated problems.

Prebiotic fibres dose-dependently increase satiety hormones and alter Bacteroidetes and Firmicutes in lean and obese JCR:LA-cp rats

There is a growing interest in modulating gut microbiota with diet in the context of obesity. The purpose of the present study was to evaluate the dose-dependent effects of prebiotics (inulin and oligofructose) on gut satiety hormones, energy expenditure, gastric emptying and gut microbiota. Male lean and obese JCR:LA-cp rats were randomised to either of the following: lean 0 % fibre (LC), lean 10 % fibre (LF), lean 20 % fibre (LHF), obese 0 % fibre (OC), obese 10 % fibre (OF) or obese 20 % fibre (OHF). Body composition, gastric emptying, energy expenditure, plasma satiety hormone concentrations and gut microbiota (using quantitative PCR) were measured. Caecal proglucagon and peptide YY mRNA levels were up-regulated 2-fold in the LF, OF and OHF groups and 3-fold in the LHF group. Ghrelin O-acyltransferase mRNA levels were higher in obese v. lean rats and decreased in the OHF group. Plasma ghrelin response was attenuated in the LHF group. Microbial species measured in the Bacteroidetes division decreased, whereas those in the Firmicutes increased in obese v. lean rats and improved with prebiotic intake. Bifidobacterium and Lactobacillus increased in the OHF v. OC group. Bacteroides and total bacteria negatively correlated with percentage of body fat and body weight. Enterobacteriaceae increased in conjunction with glucose area under the curve (AUC) and glucagon-like peptide-1 AUC. Bacteroides and total bacteria correlated positively with ghrelin AUC yet negatively with insulin AUC and energy intake (P < 0·05). Several of the mechanisms through which prebiotics act (food intake, satiety hormones and alterations in gut microbiota) are regulated in a dose-dependent manner. The combined effects of prebiotics may have therapeutic potential for obesity.

[Intestinal microbiota in short bowel syndrome]

Short bowel syndrome (SBS) is the main cause of intestinal failure especially in children. The colon is a crucial partner for small intestine adaptation and function in patients who have undergone extensive small bowel resection. However, SBS predisposes the patient to small intestine bacterial overgrowth (SIBO), explaining its high prevalence in patients with this disorder. SIBO may significantly compromise digestive and absorptive functions and may delay or prevent weaning from total parenteral nutrition (TPN). Moreover, SIBO may be one of the causes of intestinal failure-associated liver disease, requiring liver transplantation in some cases. Traditional tests for assessing SIBO may be unreliable in SBS patients. Management of SIBO with antibiotic therapy as a first-line approach remains a matter of debate, while other approaches, including probiotics, offer potential based on experimental evidence, though only few data from human studies are available.

Biological effects of propionic acid in humans; metabolism, potential applications and underlying mechanisms

Undigested food is fermented in the colon by the microbiota and gives rise to various microbial metabolites. Short-chain fatty acids (SCFA), including acetic, propionic and butyric acid, are the principal metabolites produced. However, most of the literature focuses on butyrate and to a lesser extent on acetate; consequently, potential effects of propionic acid (PA) on physiology and pathology have long been underestimated. It has been demonstrated that PA lowers fatty acids content in liver and plasma, reduces food intake, exerts immunosuppressive actions and probably improves tissue insulin sensitivity. Thus increased production of PA by the microbiota might be considered beneficial in the context of prevention of obesity and diabetes type 2. The molecular mechanisms by which PA may exert this plethora of physiological effects are slowly being elucidated and include intestinal cyclooxygenase enzyme, the G-protein coupled receptors 41 and 43 and activation of the peroxisome proliferator-activated receptor γ, in turn inhibiting the sentinel transcription factor NF-κB and thus increasing the threshold for inflammatory responses in general. Taken together, PA emerges as a major mediator in the link between nutrition, gut microbiota and physiology.

The fermentable fibre inulin increases postprandial serum short-chain fatty acids and reduces free-fatty acids and ghrelin in healthy subjects

It is thought that diets high in dietary fibre are associated with reduced risk for type 2 diabetes, at least in part because the short-chain fatty acids (SCFAs) produced during the colonic fermentation of fibre beneficially influence circulating concentrations of free-fatty acids (FFAs) and gut hormones involved in the regulation of blood glucose and body mass. However, there is a paucity of data showing this sequence of events in humans. Thus, our objective was to determine the effect of the fermentable fibre inulin on postprandial glucose, insulin, SCFA, FFA, and gut hormone responses in healthy subjects. Overnight fasted healthy subjects (n = 12) were studied for 6 h after consuming 400 mL drinks, containing 80 g high-fructose corn syrup (80HFCS), 56 g HFCS (56HFCS), or 56 g HFCS plus 24 g inulin (Inulin), using a randomized, single-blind, crossover design. A standard lunch was served 4 h after the test drink. Glucose and insulin responses after Inulin did not differ significantly from those after 80HFCS or 56HFCS. Serum acetate, propionate, and butyrate were significantly higher after Inulin than after HFCS drinks from 4-6 h. FFAs fell at a similar rate after all 3 test drinks, but were lower after Inulin than after 56HFCS at 4 h (0.40 +/- 0.06 vs. 0.51 +/- 0.06 mmol*L-1; p < 0.05). Compared with 56HFCS, Inulin significantly increased plasma glucagon-like peptide-1 concentrations at 30 min, and reduced ghrelin at 4.5 h and 6 h. The results are consistent with the hypothesis that dietary fibre increases the production of colonic SCFAs, which may reduce type 2 diabetes risk by reducing postprandial FFAs and favorably affecting gut hormones, which regulate food intake.

Adaptation of colonic fermentation and glucagon-like peptide-1 secretion with increased wheat fibre intake for 1 year in hyperinsulinaemic human subjects

High cereal fibre intake is associated with reduced risk for type 2 diabetes, but wheat fibre had little or no effect on glycaemic control or oral glucose tolerance in clinical trials lasting 4–12 weeks. To explain this discrepancy, we hypothesised that colonic adaptation to increased wheat fibre intake takes many months but eventually results in increased SCFA production and glucagon-like peptide-1 (GLP-1) secretion. Thus, the primary objective was to determine the time-course of the effects of increased wheat fibre intake on plasma acetate, butyrate and GLP-1 concentrations in hyperinsulinaemic human subjects over 1 year. Subjects with fasting plasma insulin ≥ 40 pmol/l were randomly assigned by computer to receive either a high-wheat fibre cereal (fibre group; 24 g fibre/d; twenty assigned; six dropped out, fourteen included) or a low-fibre cereal (control group; twenty assigned; six dropped-out, fourteen included) daily for 1 year. Acetate, butyrate and GLP-1 were measured during 8 h metabolic profiles performed every 3 months. There were no differences in body weight in the fibre group compared with the control group. After 9 months baseline-adjusted mean 8 h acetate and butyrate concentrations were higher on the high-fibre than the control cereal (P < 0·05). After 12 months on the high-fibre cereal, baseline-adjusted mean plasma GLP-1 was 1·3 (95 % CI 0·4, 2·2) pmol/l (P < 0·05) higher than at baseline (about 25 % increase) and 1·4 (95 % CI 0·1, 2·7) pmol/l (P < 0·05) higher than after 12 months on control. It is concluded that wheat fibre increased SCFA production and GLP-1 secretion in hyperinsulinaemic humans, but these effects took 9–12 months to develop. Since GLP-1 may increase insulin sensitivity and secretion, these results may provide a mechanism for the epidemiological association between high cereal fibre intake and reduced risk for diabetes.

Weight loss during oligofructose supplementation is associated with decreased ghrelin and increased peptide YY in overweight and obese adults

BACKGROUND

Rodent studies show that oligofructose promotes weight loss, stimulates satiety hormone secretion, reduces energy intake, and improves lipid profiles.

OBJECTIVE

Our objective was to examine the effects of oligofructose supplementation on body weight and satiety hormone concentrations in overweight and obese adults.

DESIGN

This study was a randomized, double-blind, placebo-controlled trial. Forty-eight otherwise healthy adults with a body mass index (in kg/m2) > 25 were randomly assigned to receive 21 g oligofructose/d or a placebo (maltodextrin) for 12 wk. Body composition (by dual-energy X-ray absorptiometry); meal tolerance tests, including satiety hormone response; food intake; and subjective appetite ratings were determined.

RESULTS

There was a reduction in body weight of 1.03 +/- 0.43 kg with oligofructose supplementation, whereas the control group experienced an increase in body weight of 0.45 +/- 0.31 kg over 12 wk (P = 0.01). A lower area under the curve (AUC) for ghrelin (P = 0.004) and a higher AUC for peptide YY (PYY) with oligofructose (P = 0.03) coincided with a reduction in self-reported caloric intake (P < or = 0.05). Glucose decreased in the oligofructose group and increased in the control group between initial and final tests (P < or = 0.05). Insulin concentrations mirrored this pattern (P < or = 0.05). Oligofructose supplementation did not affect plasma active glucagon-like peptide 1 secretion. According to a visual analog scale designed to assess side effects, oligofructose was well tolerated.

CONCLUSIONS

Independent of other lifestyle changes, oligofructose supplementation has the potential to promote weight loss and improve glucose regulation in overweight adults. Suppressed ghrelin and enhanced PYY may contribute in part to the reduction in energy intake. The trial was registered at clinicaltrials.gov as NCT00522353.

Role of the colon in short bowel syndrome and intestinal transplantation

Colon is a crucial partner for small intestinal adaptation and function in patients who underwent extensive small intestinal resection or transplantation. This short review deals with the different properties and roles of the colon in these settings, involving fluid and electrolytes absorption, absorption of medium-chain triglycerides, and production of short-chain fatty acids for malabsorbed energy salvage. The colon may adapt after small intestinal resection, whereas it hosts the most important part of the intestinal microbiota, which plays a crucial role in intestinal function and health. Also, colon may be responsible for D-lactic acidosis as well, as it can be injured by noninfectious colitis. Finally, the relevance of a simultaneous colon grafting is discussed as it is occasionally considered in specific patients requiring intestinal transplantation.

Morphological, kinetic, membrane biochemical and genetic aspects of intestinal enteroplasticity

The process of intestinal adaptation (“enteroplasticity”) is complex and multifaceted. Although a number of trophic nutrients and non-nutritive factors have been identified in animal studies, successful, reproducible clinical trials in humans are awaited. Understanding mechanisms underlying this adaptive process may direct research toward strategies that maximize intestinal function and impart a true clinical benefit to patients with short bowel syndrome, or to persons in whom nutrient absorption needs to be maximized. In this review, we consider the morphological, kinetic and membrane biochemical aspects of enteroplasticity, focus on the importance of nutritional factors, provide an overview of the many hormones that may alter the adaptive process, and consider some of the possible molecular profiles. While most of the data is derived from rodent studies, wherever possible, the results of human studies of intestinal enteroplasticity are provided.

Dietary lipids alter the effect of steroids on the transport of fructose following intestinal resection in rats

BACKGROUND

Glucocorticosteroids alter intestinal morphology and transport. We tested the hypothesis that the desired intestinal adaptive response following intestinal resection may be enhanced further by the locally active steroid budesonide, and by feeding a saturated as compared with a polyunsaturated fatty acid diet.

METHODS

An in-vitro uptake method was used to assess intestinal fructose uptake by rats of semisynthetic diets enriched in saturated or polyunsaturated fatty acids, and injected with budesonide or control solution.

RESULTS

Budesonide increased ileal fructose uptake in chow and PUFA-fed animals, but reduced jejunal fructose uptake in rats fed SFA. GLUT5 and GLUT2 protein and mRNA did not correlate with changes in fructose uptake. Steroids reduced jejunal proglucagon expression in animals fed chow. Animals fed SFA and given budesonide had a reduction in jejunal ODC mRNA compared with those fed PUFA or chow.

CONCLUSIONS

(1) budesonide increases ileal fructose uptake following intestinal resection, and this beneficial effect is prevented by feeding SFA rather than PUFA; (2) fructose uptake does not correlate with GLUT5 and GLUT2 protein and mRNA; (3) ODC and proglucagon may be involved in this adaptive response.

The physiological relevance of the intestinal microbiota--contributions to human health

The intestinal commensal microbiota is a dynamic mixture of essential microbes that develops under key influences of genetics, environment, diet and disease. Population profiles differ along the gastrointestinal tract, from the lumen to the mucosa, and among individuals. The total microbiota population outnumbers the cells in the human body and accounts for 35-50% of the volume of the colonic content. Key physiological functions of the commensal microbiota include protective effects exerted directly by specific bacterial species, control of epithelial cell proliferation and differentiation, production of essential mucosal nutrients, such as short-chain fatty acids and amino acids, prevention of overgrowth of pathogenic organisms, and stimulation of intestinal immunity. Oral probiotics are living microorganisms that upon ingestion in specific numbers exert health benefits beyond those of inherent basic nutrition. Emerging evidence indicates prophylactic and therapeutic utility for probiotic consumption in gastrointestinal health and disease.

Resistin Is a Key Mediator of Glucose-dependent Insulinotropic Polypeptide (GIP) Stimulation of Lipoprotein Lipase (LPL) Activity in Adipocytes

Studies on the physiological roles of the incretin hormone, glucose-dependent insulinotropic polypeptide (GIP) have largely focused on its insulinotropic action and ability to regulate beta-cell mass. In previous studies on the stimulatory effect of GIP on adipocyte lipoprotein lipase (LPL), a pathway was identified involving increased phosphorylation of protein kinase B (PKB) and reduced phosphorylation of LKB1 and AMP-activated protein kinase (AMPK). The slow time of onset of the responses suggested that GIP may have induced release of an intermediary molecule, and the current studies focused on the possible contribution of the adipokine resistin. In differentiated 3T3-L1 adipocytes, GIP, in the presence of insulin, increased resistin secretion through a pathway involving p38 mitogen-activated protein kinase (p38 MAPK) and the stress-activated protein kinase/Jun amino-terminal kinase (SAPK/JNK). The other major incretin hormone, glucagon-like peptide-1 (GLP-1), exhibited no significant effects. Chronic elevation of circulating GIP levels in the Vancouver Diabetic Fatty (VDF) Zucker rat resulted in increases in circulating resistin levels and activation of p38 MAPK or SAPK/JNK in epididymal fat tissue, suggesting the existence of identical pathways in vivo as well as in vitro. Administration of resistin to 3T3-L1 adipocytes mimicked the effects of GIP on the PKB/LKB1/AMPK/LPL pathway: increasing phosphorylation of PKB, reducing levels of phosphorylated LKB1 and AMPK, and increasing LPL activity. Knockdown of resistin using RNA interference attenuated the effect of GIP on the PKB/LKB1/AMPK/LPL pathway in 3T3-L1 adipocytes, supporting a role for resistin as a mediator.

Insoluble cereal fiber reduces appetite and short-term food intake and glycemic response to food consumed 75 min later by healthy men

BACKGROUND

Insoluble fiber consumption is associated with reduced risk of obesity and diabetes, but its mechanisms of action are unknown.

OBJECTIVE

The objective was to describe the effect of insoluble fiber on appetite, short-term food intake, and blood glucose (BG) before and after a meal 75 min later in healthy men.

DESIGN

In a crossover design, high-fiber (HF; 33 g insoluble fiber) cereal, low-fiber (LF) cereal, white bread (WB), and water control were administered to young men after an overnight fast. Caloric treatments had similar energy, macronutrient content, volume, and weight. In the first experiment, subjective appetite and BG were measured at 15-min intervals before and after an ad libitum meal at 75 min. In the second experiment, a preset pizza meal (850 kcal) was consumed at 75 min. Appetite and blood glucose were measured for 150 min at fasting and at 15-min intervals before and after the fixed meal.

RESULTS

In experiment 1, ad libitum food intake was lower after the HF cereal and WB than after the LF cereal and water (937 +/- 86, 970 +/- 65, 1109 +/- 90, 1224 +/- 89 kcal, respectively; P < 0.001). Appetite was lower (P < 0.05) after the HF cereal than after the WB but not different from the LF cereal. The BG area under the curve (AUC) did not differ among the HF cereal, WB, and LF cereal from 0 to 75 min, but the postmeal BG increased after the WB and LF cereal but not after the HF cereal. In experiment 2, the HF cereal, but not the LF cereal or WB, increased fullness before and prevented an increase in the BG AUC after the preset meal (P < 0.05).

CONCLUSION

A serving of 33 g insoluble fiber reduced appetite, lowered food intake, and reduced glycemic response to a meal consumed 75 min later.

Oral polyamine administration modifies the ontogeny of hexose transporter gene expression in the postnatal rat intestine

Gastrointestinal mucosal polyamines influence enterocyte proliferation and differentiation during small intestinal maturation in the rat. Studies in postnatal rats have shown that ornithine decarboxylase (ODC) protein and mRNA peak before the maximal expression of brush-border membrane (BBM) sucrase-isomaltase (SI) and the sugar transporters sodium-dependent glucose transporter 1 (SGLT1) and glucose transporter 2 (GLUT2). This study was undertaken to test the hypothesis that the oral administration of spermidine in postnatal rats upregulates the expression of ODC, thereby enhancing the expression of SI and SGLT1 in the brush-border membrane as well as basolateral membrane-facilitative GLUT2 and Na(+)-K(+)-ATPase. Northern and Western blot analyses were performed with antibodies and cDNA probes specific for SI, SGLT1, GLUT2, alpha(1)- and beta(1)-subunits of Na(+)-K(+)-ATPase, and ODC. Postnatal rats fed 6 mumol spermidine daily for 3 days from days 7 to 9 were killed either on postnatal day 10 (Sp10) or day 13 following a 3-day washout period (Sp13). Sp10 rats showed a precocious increase in the abundance of mRNAs for SI, SGLT1, and GLUT2 and Na(+)-K(+)-ATPase activity and alpha(1)- and beta(1)-isoform gene expression compared with controls. ODC activity and protein and mRNA abundance were also increased in Sp10 animals. The increased expression of these genes was not sustained in Sp13 rats, suggesting that these effects were transient. Thus, 3 days of oral polyamine administration induces the precocious maturation of glucose transporters in the postnatal rat small intestine, which may be mediated by alterations in ODC expression.

Biology of incretins: GLP-1 and GIP

This review focuses on the mechanisms regulating the synthesis, secretion, biological actions, and therapeutic relevance of the incretin peptides glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1). The published literature was reviewed, with emphasis on recent advances in our understanding of the biology of GIP and GLP-1. GIP and GLP-1 are both secreted within minutes of nutrient ingestion and facilitate the rapid disposal of ingested nutrients. Both peptides share common actions on islet beta-cells acting through structurally distinct yet related receptors. Incretin-receptor activation leads to glucose-dependent insulin secretion, induction of beta-cell proliferation, and enhanced resistance to apoptosis. GIP also promotes energy storage via direct actions on adipose tissue, and enhances bone formation via stimulation of osteoblast proliferation and inhibition of apoptosis. In contrast, GLP-1 exerts glucoregulatory actions via slowing of gastric emptying and glucose-dependent inhibition of glucagon secretion. GLP-1 also promotes satiety and sustained GLP-1-receptor activation is associated with weight loss in both preclinical and clinical studies. The rapid degradation of both GIP and GLP-1 by the enzyme dipeptidyl peptidase-4 has led to the development of degradation-resistant GLP-1-receptor agonists and dipeptidyl peptidase-4 inhibitors for the treatment of type 2 diabetes. These agents decrease hemoglobin A1c (HbA1c) safely without weight gain in subjects with type 2 diabetes. GLP-1 and GIP integrate nutrient-derived signals to control food intake, energy absorption, and assimilation. Recently approved therapeutic agents based on potentiation of incretin action provide new physiologically based approaches for the treatment of type 2 diabetes.

Cecal infusion of butyrate increases intestinal cell proliferation in piglets

The effects of colon-derived butyrate on intestinal cell proliferation are controversial. In vitro studies suggest an inhibitory effect, and in vivo studies suggest the opposite, but neither type of study has been based on a physiologically relevant, intracolonic supply of butyrate. In this study, piglets (n = 24) were fed sow's milk replacement formula and randomized into 4 equal groups: 1) control; 2) cecal butyrate infusion at a rate equal to that produced in the colon; 3) inulin supplementation at a concentration previously found to lower cecal cell proliferation; and 4) butyrate infusion plus inulin supplementation. After 6 d of oral feeding, cecal butyrate infusions were initiated for a period of 4 d. Cecal, distal colonic, jejunal, and ileal cell proliferation, apoptosis, and morphology were evaluated and serum concentration of glucagon-like peptide-2 (GLP-2) was measured. Butyrate or inulin did not affect GLP-2, weight gain, apoptosis, intestinal injury scores, cecal or colon crypt depth, and jejunal or ileal villus height. For cell proliferation, there was a significant interaction between inulin, butyrate, and tissue (P = 0.007). Inulin modified the effect of butyrate (butyrate x inulin interaction in cecum, P = 0.001; in distal colon, P = 0.018; in ileum, P = 0.001; and in jejunum, P = 0.003). In the absence of inulin, butyrate caused a 78- 119% increase in cell proliferation in the ileum, distal colon, jejunum, and cecum (P < or = 0.002). Thus, at an entry rate into the colon within the physiological range, butyrate caused increased intestinal cell proliferation, but inulin tended to block this effect. Thus, intracolonic butyrate may enhance intestinal growth during infancy.

Influence of long-term administration of lactulose and Saccharomyces boulardii on the colonic generation of phenolic compounds in healthy human subjects

OBJECTIVE

Proteins are degraded in the colon by bacterial fermentation into potentially toxic metabolites such as phenolic compounds. The aim of the present study was to investigate whether long-term administration of lactulose or Saccharomyces boulardii cells would result in a lower protein degradation. In addition, the influence of a long-term dietary intake on different gastrointestinal parameters was investigated.

METHODS

The effect of long-term intervention of the substrates was evaluated in a randomized, cross-over study in 43 healthy volunteers. At the start of the study and at the end of each 4-week treatment period, urine was collected during 48 h in different fractions and faeces during 72 h. Breath test samples and blood samples were taken to study gastrointestinal parameters.

RESULTS

No influence of long-term administration of both substrates was found on GE, OCTT and serum lipids. A significant decrease in small intestinal permeability was found after long-term dietary intervention with lactulose. Long-term administration of lactulose significantly decreased urinary p-cresol excretion, but did not lower fecal p-cresol excretion. No significant effects were observed after S. boulardii intake.

CONCLUSION

The results obtained in present study have indicated that colonic amino acid fermentation can be reduced by the administration of lactulose as a fermentable carbohydrate.

Non–digestible oligosaccharides and defense functions: lessons learned from animal models

Animals are constantly exposed to a diversity of health challenges and the gastrointestinal tract (GIT) is a major, if not the principal, site of exposure. Animal models and a limited number of human clinical studies have shown that the assemblages and metabolic activities of the resident bacteria are important determinants of the effectiveness of the various host defense mechanisms and thereby influence the ability of animals to respond to health challenges. The assemblages of bacteria resident in the GIT provide a first line of defense that can exclude invading pathogens, reduce the proliferation of opportunistic pathogens already resident in the GIT, and reduce the availability, carcinogenicity, or toxicity of noxious chemicals. The mucosa of the GIT is a second, multilayered line of defense that includes the mucous and other secretions, the epithelial cells, and immune-associated cells scattered within and under the epithelium. The final line of defense contends with pathogens or noxious chemicals that transcend the mucosal barrier and enter the host and consists of the innate and acquired components of the systemic immune system and the xenobiotic metabolizing enzymes. The lactic acid producing bacteria (LAB) are considered to be immunomodulatory and directly or indirectly influence the GIT and systemic defense functions. Corresponding with this, supplementing the diet with inulin, oligofructose, or other nondigestible oligosaccharides that increase the densities and metabolic capacities of the LAB enhances defense mechanisms of the host, increases resistance to various health challenges, and accelerates recovery of the GIT after disturbances.

The role of gut hormones in glucose homeostasis

The gastrointestinal tract has a crucial role in the control of energy homeostasis through its role in the digestion, absorption, and assimilation of ingested nutrients. Furthermore, signals from the gastrointestinal tract are important regulators of gut motility and satiety, both of which have implications for the long-term control of body weight. Among the specialized cell types in the gastrointestinal mucosa, enteroendocrine cells have important roles in regulating energy intake and glucose homeostasis through their actions on peripheral target organs, including the endocrine pancreas. This article reviews the biological actions of gut hormones regulating glucose homeostasis, with an emphasis on mechanisms of action and the emerging therapeutic roles of gut hormones for the treatment of type 2 diabetes mellitus.

Intestinal mucosal adaptation

Intestinal failure is a condition characterized by malnutrition and/or dehydration as a result of the inadequate digestion and absorption of nutrients. The most common cause of intestinal failure is short bowel syndrome, which occurs when the functional gut mass is reduced below the level necessary for adequate nutrient and water absorption. This condition may be congenital, or may be acquired as a result of a massive resection of the small bowel. Following resection, the intestine is capable of adaptation in response to enteral nutrients as well as other trophic stimuli. Identifying factors that may enhance the process of intestinal adaptation is an exciting area of research with important potential clinical applications.

Mechanisms of enteral nutrient-enhanced intestinal adaptation

The role of enteral nutrients in maintaining small intestinal structure and function is well established. Evidence that enteral nutrients induce intestinal adaptation include the structural and functional gradient along the length of the healthy intestine, the atrophy and functional compromise induced by fasting and parenteral nutrition, and the enhanced adaptive capacity of the distal intestine following partial enterectomy. Key mechanisms contributing to enteral nutrient-induced intestinal adaptation include nonspecific luminal stimulation and that provided by specific nutrients, "functional workload" induced by polymeric nutrients, potential stimulation of pancreaticobiliary secretions, secretion of humoral mediators, and induction of intestinal hyperemia.

Glutamine alone or combined with short-chain fatty acids fails to enhance gut adaptation after massive enterectomy in rats

PURPOSE: To investigate the effect of oral glutamine alone or combined with short chain fatty acids (SCFA) in the intestinal adaptation of rats submitted to an massive enterectomy. METHODS: After receiving 70% small bowel resection, 30 Wistar rats were randomized to received either standard rat chow (control group, n=10) or the same diet supplemented with 3,05% of glutamine alone (glutamine group, n=10) or combined with a solution containing SCFA (glutamine+SCFA group, n=10). Animals were killed on the 14th postoperative day. Mucosal weight, crypt depth, villus height, wall width, and the mucosal content of DNA, were assessed in basal conditions (resected gut specimen) and compared to the small bowel specimen collected on the postoperative day 14, at both jejunum and ileum sites. RESULTS: All groups presented similar pattern in weight evolution. In all groups, both the morphological findings and the DNA content were significantly higher at the end of the experiment than in basal conditions, at both the jejunum and ileum. Except for the jejunum wall width that was higher in control group (808±95 µ) than in the other two groups (glutamine = 649±88 µ and glutamine+SCFA = 656±92; p<0.01), there was no difference among them in all variables at both intestinal sites after 14 days. CONCLUSION: All groups presented adaptation of the intestinal mucosa in the remnant gut. Glutamine combined or not with short chain fatty acids fails to influence the adaptive response of the small bowel.

Intestinal Adaptation in Short Bowel Syndrome

Short bowel syndrome occurs when there is insufficient length of the small intestine to maintain adequate nutrition and/or hydration status without supplemental support. This syndrome most frequently occurs following extensive surgical resection of the intestine, and the extent of adaptation depends on the anatomy of the resected bowel and the amount of bowel remaining. Following resection, the intestinal tissue undergoes morphologic and functional changes to compensate for the lost function of the resected bowel. These changes are mediated by multiple interactive factors, including intraluminal and parenteral nutrients, gastrointestinal secretions, hormones, cytokines, and growth factors, many of which have been well characterized in animal models. The amount of small bowel remaining is the most important predictor of adaptive potential; neither structural nor functional adaptative changes have been demonstrated in humans or animal models with more extreme resections resulting in an end-jejunostomy. The current understanding of these processes has led to the recent use of supplemental hormones, such as growth hormone and glucagon-like peptide 2, in intestinal rehabilitation programs and may lead to the development of pharmacologic agents designed to augment the innate adaptive response.

Glucagon-Like Peptide-2 and Short-Chain Fatty Acids: A New Twist to an Old Story

The nutritional regulation of intestinal adaptation extends beyond the route of nutrient administration as specific nutrients are known to mediate the adaptive response. Dietary carbohydrates are known to enhance intestinal adaptation in patients with short-bowel syndrome. This review discusses SCFA-induced adaptation in intestinal structure and function in adult rat and neonatal piglet models. Potential mechanisms relate to the salvage of energy as SCFA in the colon, direct mediation of intestinal adaptation by SCFA and stimulated release of glucagon-like peptide-2 (GLP-2) from enteroendocrine L cells by SCFA. Among the produced SCFA, butyrate appears to be responsible for increasing plasma GLP-2 concentration, in addition to the enterotrophic effects. Emerging evidence reveals that physiological concentrations of butyrate acutely upregulate the expression of key enterocyte-associated nutrient transporters. Focused experiments are needed to carefully identify the critical components of intestinal adaptation and yield conclusions regarding the relative contributions of SCFA and GLP-2 during the various phases of this process.

Fermentable fiber reduces recovery time and improves intestinal function in piglets following Salmonella typhimurium infection

Diarrhea is a leading cause of morbidity and mortality in infants. The addition of fiber to infant formulas reduces recovery time following pathogenic infection in infants > 6 mo old, but effects on neonates are unknown. The hypothesis that fermentable fiber reduces infection-associated symptoms and enhances intestinal structure and function in neonates was examined. Piglets (2 d old) were randomly assigned to receive formula alone (control) or formula containing methylcellulose (MCEL), soy polysaccharides (SPS) or fructooligosaccharides (FOS) for 14 d. On d 7, piglets were further randomly assigned to receive an oral gavage of Salmonella typhimurium or serve as noninfected controls. S. typhimurium infection produced diarrhea in controls and MCEL groups, but not in the SPS and FOS groups. Postinfection physical activity was lower (P = 0.0001) in the controls than in all other groups. Ileal lactase activity was reduced (P < 0.05) following infection in the control group but not in the MCEL, SPS and FOS groups. Ileal mucosal barrier function, measured as resistance, was impaired by infection (P < 0.05) in the control and SPS groups, but was unaltered in the jejunum and colon. Total ion transport and basal short-circuit current were higher (P < 0.05) in jejunum than in ileum and colon, irrespective of diet or infection. SPS and FOS increased (P < 0.05) ileal glutamine transport relative to piglets fed MCEL, irrespective of infection. Because fermentable fiber enhances intestinal function and reduces the severity of S. typhimurium infection-associated symptoms, it may be a cost-effective way in which to reduce the severity of pathogenic infection-associated symptoms in infants.

Dietary lipids alter the effect of steroids on transport of glucose after intestinal resection: Part II. Signalling of the response

BACKGROUND/PURPOSE

Glucocorticosteroids alter the function of the intestine. Budesonide (Bud) increases the jejunal D-glucose uptake, and this effect is prevented through a polyunsaturated fatty acid (PUFA) diet. This study was undertaken to assess the possible signalling effect of budesonide, prednisone (Pred), or dexamethasone (Dex) in animals with a 50% intestinal resection and fed chow or a diet enriched with saturated (SFA) or polyunsaturated fatty acids.

METHODS

Northern blots were performed.

RESULTS

Steroids reduced the jejunal but not the ileal expression of proglucagon. Ornithine decarboxylase (ODC) expression was reduced in the jejunum.

CONCLUSIONS

c-jun, ODC, and proglucagon may be involved in the adaptive response that occurs with steroids and variations in dietary lipids after intestinal resection.