Intestinal Nutrient Transport Research Articles

Immunopathogenesis of Ascaridia galli infection in layer chicken

Gastro-intestinal nematode infections in mammals are associated with local T lymphocyte infiltrations, Th2 cytokine induction, and alterations in epithelial cell secretion and absorption. This study demonstrates that Ascaridia (A.) galli infection in chicken also elicits local gut-associated immune reactions and changes in the intestinal electrogenic nutrient transport. In A. galli-infected birds we observed infiltrations of different T cell populations in the intestinal lamina propria and accumulation of CD4+ lymphocytes in the epithelium. The Th2 cytokines IL-4 and IL-13 dominated the intestinal immune reactions following A. galli infection. A. galli-specific systemic IgY antibodies were detected after two weeks post infection, and did only poorly correlate with detected worm numbers. Electrogenic transport of alanin and glucose was impaired in A. galli-infected chicken. Our data provide circumstantial evidence that local immune responses and electro-physiological intestinal functions may be connected and contribute to the elimination of worm infection.

Role of Vagal Fibers in Weight Control and Nutrient Absorption

Role of Vagal Fibers in Weight Control and Nutrient Absorption

Epidermal growth factor upregulates serotonin transporter in human intestinal epithelial cells via transcriptional mechanisms

Serotonin transporter (SERT) regulates extracellular availability of serotonin and is a potential pharmacological target for gastrointestinal disorders. A decrease in SERT has been implicated in intestinal inflammatory and diarrheal disorders. However, little is known regarding regulation of SERT in the intestine. Epidermal growth factor (EGF) is known to influence intestinal electrolyte and nutrient transport processes and has protective effects on intestinal mucosa. Whether EGF regulates SERT in the human intestine is not known. The present studies examined the regulation of SERT by EGF, utilizing Caco-2 cells grown on Transwell inserts as an in vitro model. Treatment with EGF from the basolateral side (10 ng/ml, 24 h) significantly stimulated SERT activity (∼2-fold, P < 0.01) and mRNA levels compared with control. EGF increased the activities of the two alternate promoter constructs for human SERT gene: SERT promoter 1 (hSERTp1, upstream of exon 1a) and SERT promoter 2 (hSERTp2, upstream of exon 2). Inhibition of EGF receptor (EGFR) tyrosine kinase activity by PD168393 (1 nM) blocked the stimulatory effects of EGF on SERT promoters. Progressive deletions of the SERT promoter indicated that the putative EGF-responsive elements are present in the -672/-472 region of the hSERTp1 and regions spanning -1195/-738 and -152/+123 of hSERTp2. EGF markedly increased the binding of Caco-2 nuclear proteins to the potential AP-1 cis-elements present in EGF-responsive regions of hSERTp1 and p2. Overexpression of c-jun but not c-fos specifically transactivated hSERTp2, with no effects on hSERTp1. Our findings define novel mechanisms of transcriptional regulation of SERT by EGF via EGFR at the promoter level that may contribute to the beneficial effects of EGF in gut disorders.

Intestinal nutrient transport in the cradle of the Mediterranean Diet: 23rd EITG meeting report

Intestinal nutrient transport in the cradle of the Mediterranean Diet: 23rd EITG meeting report

Marked changes in endogenous antioxidant expression precede vitamin A-, C-, and E-protectable, radiation-induced reductions in small intestinal nutrient transport

Rapidly proliferating epithelial crypt cells of the small intestine are susceptible to radiation-induced oxidative stress, yet there is a dearth of data linking this stress to expression of antioxidant enzymes and to alterations in intestinal nutrient absorption. We previously showed that 5–14 days after acute γ-irradiation, intestinal sugar absorption decreased without change in antioxidant enzyme expression. In the present study, we measured antioxidant mRNA and protein expression in mouse intestines taken at early times postirradiation. Observed changes in antioxidant expression are characterized by a rapid decrease within 1 h postirradiation, followed by dramatic upregulation within 4 h and then downregulation a few days later. The cell type and location expressing the greatest changes in levels of the oxidative stress marker 4HNE and of antioxidant enzymes are, respectively, epithelial cells responsible for nutrient absorption and the crypt region comprising mainly undifferentiated cells. Consumption of a cocktail of antioxidant vitamins A, C, and E, before irradiation, prevents reductions in transport of intestinal sugars, amino acids, bile acids, and peptides. Ingestion of antioxidants may blunt radiation-induced decreases in nutrient transport, perhaps by reducing acute oxidative stress in crypt cells, thereby allowing the small intestine to retain its absorptive function when those cells migrate to the villus days after the insult.

The effect of glucagon-like peptide 2 injection on performance, small intestinal morphology, and nutrient transporter expression of stressed broiler chickens

An experiment was conducted to determine the effect of injecting glucagon-like peptide 2 (GLP-2) on the small intestinal weight, morphology, and nutrient transporter expression in pharmacologically stressed broiler chickens. A total of 144 seven-day-old birds were fed either a basal diet (CTRL) or a basal diet plus 30 mg of corticosterone (CORT)/kg of diet for a total of 14 d. Half of the birds from each group were injected daily with GLP-2 (6.7 nmol/kg of BW) or saline for 14 d. The average final BW, ADG, ADFI, and the ratio of feed intake to weight gain (F:G) was recorded over 21 d for the 4 groups of 36 birds, namely CTRL + saline, CTRL + GLP-2, CORT + saline, and CORT + GLP-2. In addition, the absolute and relative small intestinal weight, villus height (VH), and crypt depth (CD) of the duodenum and jejunum, as well as the abundance of sodium and glucose co-transporter 1 (SGLT-1), vitamin D-dependent calcium-binding protein-28,000 molecular weight (CaBP-D28k), and peptide transporter 1 (PepT-1) mRNA in the duodenum and of liver fatty acid-binding protein (L-FABP) mRNA in the jejunum. The total DNA, RNA, and protein content in small intestinal mucosa were also determined. The results showed that CORT administration significantly lowered average final BW, ADG, ADFI, absolute small intestinal weight, VH, and CD of duodenum and jejunum (P < 0.05) while increasing the relative small intestinal weight, F:G, relative abundance of SGLT-1, CaBP-D28k, PepT-1, and L-FABP mRNA (P < 0.05). Glucagon-like peptide 2 injection increased the average final BW, ADG, VH, and CD in duodenum and jejunum and relative abundance of SGLT-1, CaBP-28k, PepT1, and PepT1 mRNA of broiler chickens, respectively (P < 0.05), and decreased F:G (P < 0.05). In chickens fed basal diet plus CORT, injecting GLP-2 decreased F:G (P < 0.05); increased VH and CD of duodenum and CD of jejunum; and increased relative abundance of SGLT-1, CaBP-D28k, PepT-1, and L-FABP mRNA, RNA, and total protein content in small intestine compared with the injection of saline (P < 0.05). In birds fed the basal diet, GLP-2 injection decreased F:G (P < 0.05) and increased final BW, ADG, small bowel weight, CD of jejunum, and relative abundance of CaBP-D28k and PepT-1 mRNA compared with injecting saline (P < 0.05). In conclusion, GLP-2 injection reversed the negative effect of stress on the weight and morphology and the absorptive function of small bowel of broiler chickens. Glucagon-like peptide 2 injection also had a positive effect on the growth performance of healthy broiler chickens.

Approaches to Enhancing the Gastrointestinal Health of Calves

The gastrointestinal tract (GIT), as the largest immunological organ of the body, plays a pivotal role in calf health, growth, and long-term productivity. Important contributors to optimal gastrointestinal function of calves include colostrum status, a balanced intestinal flora, nutrition, intestinal immune factors, motility, and transport of nutrients. The promotion of GIT health of young calves through dietary manipulations, nutritional supplements, addition of immune components, oral antibiotics, and vaccinations are discussed. Antibiotic alternatives to improve growth and reduce enteric disease are plasma proteins, immunoglobulins, probiotic bacteria, yeast cultures, and oligosaccharides. To ascertain health, growth, and profitability from measures taken to improve intestinal immune function, outcome measurements, intestinal health parameters, and dietary composition should be monitored closely.

Defining conditions for the co-culture of Caco-2 and HT29-MTX cells using Taguchi design

Introduction The co-culture of Caco-2 and HT29 cells for testing intestinal drug and nutrient transport and metabolism provides the presence of both absorptive and goblet cells, both of which have different culture requirements for optimal growth and function. The research on the co-culture of Caco-2 and HT29 cells is very limited in respect to refining specific conditions that reduce intra- and inter-laboratory variations. In the present study we reported conditions that enable reproducible results to be obtained for drug permeability using in vitro co-culture of Caco-2 and HT29-MTX based on Taguchi experimental design. Methods The selection of four factors that specified cell culture conditions, namely culture medium, seeding time, seeding density, and Caco-2:HT29-MTX ratio on TEER value and individual permeability coefficients of propranolol, ketoprofen and furosemide was established. Based on the selected conditions for co-culture, we also confirmed the functionality of the final chosen culture condition using nitric oxide as an indicator of intestinal inflammation. Results Choice of cell culture time and culture medium represented two of the most important factors that affected TEER values and the permeability coefficients of the model drugs. On the other hand, the seeding density and the Caco-2:HT29-MTX ratio exerted no significant influence on TEER values and the drug permeability coefficients. No absolute optimal cell culture condition could be obtained for all drugs; however subsequent confirmation experiments concluded that excellent precision for TEER values and drug permeability coefficients was obtained from the two operators using the following combination of conditions, namely an initial seeding density of 1 × 10 5 Caco-2 and HT29-MTX cells/cm 2 at a ratio of 9:1, followed by a 21 day culture time in MEM medium. Finally, functionality of the co-culture model system using the above selected in vitro conditions resulted in comparable nitric oxide synthesis to that of a Caco-2 cell monolayer. Discussion Taguchi experimental design enabled us to define a combination of in vitro culture conditions that resulted in excellent operator reproducibility for determining drug permeability coefficients in a Caco-2 and HT29-MTX co-culture system. Moreover, the selected conditions used in co-culture of absorptive and goblet intestinal cells did not compromise the synthesis of nitric oxide, an indicator of inflammation, measured in Caco-2 monolayers.

Effect of Corticosterone Administration on Small Intestinal Weight and Expression of Small Intestinal Nutrient Transporter mRNA of Broiler Chickens

The effects of corticosterone (CORT) administration on the weight of small intestine and the expression of nutrient transporter mRNA in the small intestine of broiler chickens (Gallus gallus domesticus) were investigated. One hundred and eight seven-day-old birds were randomly divided into two equal groups comprising a control group (CTRL) and an experimental group (CORT). CTRL birds were fed a basal diet and the CORT birds were fed a basal diet containing 30 mg corticosterone/kg from d 8 to 21. At 21 d of age, average daily feed intake (ADFI), serum corticosterone level, small intestinal absolute wet weight and relative weight, and relative abundance of SGLT1, CaBP-D28k, PepTl mRNA in the duodenum and L-FABP mRNA in the jejunum were determined. The results showed that serum corticosterone level, liver weight and small intestinal relative weight (small intestinal wet weight/body weight) of CORT chickens were about 30.15%, 26.72% and 42.20% higher, respectively, than in the CTRL group (p<0.05). CORT birds had relative mRNA abundance of CaBP-D28k and PepT1 in the duodenum, and L-FABP in the jejunum which was 1.77, 1.37 and 1.94 fold higher, respectively, than in the CTRL group (p<0.05); the relative abundance of SGLT1 was 1.67 fold higher than in the CTRL group (p = 0.097). ADFI, small intestinal wet weight and length in CORT-treated broiler chickens was about 29.11%, 31.12% and 12.35% lower, respectively, than in the CTRL group (p<0.05). In conclusion, corticosterone administration lowered the wet weight but increased the relative weight of the small intestine and the expression of intestinal nutrient transporter mRNA of broiler chickens.

Soy formula and isoflavones and the developing intestine

Soy protein-based infant formulas (SF) are commonly used to feed infants during their first year of life. SF contains isoflavones, which influence cell proliferation, but their actions in the developing intestine have received little attention. Herein, the impact of soy isoflavones and SF on intestinal development and rotavirus (RV) infectivity is described. The isoflavone genistein has been found to reduce intestinal cell proliferation in vitro and in vivo in piglets without affecting intestinal enzyme activity or nutrient transport. However, isoflavones possess antiviral activity. The mix of isoflavones at the concentrations in SF, or genistin alone, inhibited RV infectivity by 40-60%. Thus, soy isoflavones are bioactive within the neonatal intestine and may reduce the severity of RV infections.

Bile acids: regulation of synthesis: Thematic Review Series: Bile Acids

Bile acids are physiological detergents that generate bile flow and facilitate intestinal absorption and transport of lipids, nutrients, and vitamins. Bile acids also are signaling molecules and inflammatory agents that rapidly activate nuclear receptors and cell signaling pathways that regulate lipid, glucose, and energy metabolism. The enterohepatic circulation of bile acids exerts important physiological functions not only in feedback inhibition of bile acid synthesis but also in control of whole-body lipid homeostasis. In the liver, bile acids activate a nuclear receptor, farnesoid X receptor (FXR), that induces an atypical nuclear receptor small heterodimer partner, which subsequently inhibits nuclear receptors, liver-related homolog-1, and hepatocyte nuclear factor 4alpha and results in inhibiting transcription of the critical regulatory gene in bile acid synthesis, cholesterol 7alpha-hydroxylase (CYP7A1). In the intestine, FXR induces an intestinal hormone, fibroblast growth factor 15 (FGF15; or FGF19 in human), which activates hepatic FGF receptor 4 (FGFR4) signaling to inhibit bile acid synthesis. However, the mechanism by which FXR/FGF19/FGFR4 signaling inhibits CYP7A1 remains unknown. Bile acids are able to induce FGF19 in human hepatocytes, and the FGF19 autocrine pathway may exist in the human livers. Bile acids and bile acid receptors are therapeutic targets for development of drugs for treatment of cholestatic liver diseases, fatty liver diseases, diabetes, obesity, and metabolic syndrome.

Fisiopatologia das diarréias em suínos

A diarréia é a principal manifestação clínica das infecções entéricas. O desequilíbrio entre os processos de absorção e secreção intestinal decorrentes de alterações no transporte de água e eletrólitos é determinante na patogênese dos processos diarréicos. Os mecanismos fisiopatológicos estão associados às características particulares de cada patógeno. Dessa forma, a interação específica entre os patógenos entéricos e o epitélio intestinal resulta em diferentes tipos de diarréias. Na produção de suínos, o conhecimento da fisiopatologia das infecções entéricas é fundamental no desenvolvimento de métodos de diagnóstico e, em um futuro próximo, na elaboração de estratégias de prevenção e controle dessas afecções. Com base nos processos fisiológicos característicos do trato gastrointestinal, esta revisão tem como objetivo descrever aspectos relevantes e atuais dos mecanismos fisiopatológicos das diarréias em suínos. Serão enfatizadas as alterações patológicas no transporte intestinal de íons e nutrientes decorrentes da ação de patógenos entéricos importantes na produção suinícola.

Amino acids in the rat intestinal lumen regulate their own absorption from a distant intestinal site

Intestinal nutrient transport is altered in response to changes in dietary conditions and luminal substrate level. It is not clear, however, whether an amino acid in the intestinal lumen can acutely affect its own absorption from a distant site. Our aim is to study the effect of an amino acid present in rat small intestinal segment on its own absorption from a proximal or distal site and elucidate the underlying mechanisms. The effect of instillation of alanine (Ala) in either jejunum or ileum on its own absorption at ileal or jejunal level was examined in vivo. The modulation of this intestinal regulatory loop by the following interventions was studied: tetrodotoxin (TTX) added to Ala, subdiaphragmatic vagotomy, chemical ablation of capsaicin-sensitive primary afferent (CSPA) fibers, and IV administration of calcitonin gene-related peptide (CGRP) antagonist. In addition, the kinetics of jejunal Ala absorption and the importance of Na+-dependent transport were studied in vitro after instilling Ala in the ileum. Basal jejunal Ala absorption [0.198 +/- 0.018 micromol x cm(-1) x 20 min(-1) (means +/- SD)] was significantly decreased with the instillation of 20 mM Ala in the ileum or in an adjacent distal jejunal segment (0.12 +/- 0.015; P < 0.0001 and 0.138 +/- 0.014; P < 0.002, respectively). Comparable inhibition was observed in the presence of proline in the ileum. Moreover, basal Ala absorption from the ileum (0.169 +/- 0.025) was significantly decreased by the presence of 20 mM Ala in the jejunum (0.103 +/- 0.027; P < 0.01). The inhibitory effect on jejunal Ala absorption was abolished by TTX, subdiaphragmatic vagotomy, neonatal capsaicin treatment, and CGRP antagonism. In vitro studies showed that Ala in the ileum affects Na+-mediated transport and increases K(m) without affecting Vmax. Intraluminal amino acids control their own absorption from a distant part of the intestine, by affecting the affinity of the Na+-mediated Ala transporter, through a neuronal mechanism that involves CSPA and CGRP.

Endurance swimming stimulates transepithelial calcium transport and alters the expression of genes related to calcium absorption in the intestine of rats

Endurance impact exercise, e.g., running, is known to enhance the intestinal calcium absorption. However, nonimpact exercise, e.g., swimming, is more appropriate for osteoporotic patients with cardiovascular diseases or disorders of bone and joint, but the effect of swimming on the intestinal calcium transport was unknown. This study, therefore, aimed to investigate the transepithelial calcium transport and the expression of related genes in the intestine of rats trained to swim nonstop 1 h/day, 5 days/wk for 2 wk. We found that endurance swimming stimulated calcium transport in the duodenum, proximal jejunum, and cecum, while decreasing that in the proximal colon. Swimming affected neither the transepithelial potential difference nor resistance. As demonstrated by real-time PCR, the small intestine, especially the duodenum, responded to swimming by upregulating a number of genes related to the transcellular calcium transport, i.e., TRPV5, TRPV6, calbindin-D9k, PMCA1b, and NCX1, and the paracellular calcium transport, i.e., ZO-1, ZO-2, ZO-3, cingulin, occludin, and claudins, as well as nuclear receptor of 1,25(OH)2D3. In contrast, swimming downregulated those genes in the colon. Microarray analysis showed that swimming also altered the expression of duodenal genes related to the transport of several ions and nutrients, e.g., Na+, K+, Cl-, glucose, and amino acids. In conclusion, endurance swimming enhanced intestinal calcium absorption, in part, by upregulating the calcium transporter genes. The present microarray study also provided relevant information for further investigations into the intestinal nutrient and electrolyte transport during nonimpact exercise.

Digestive physiology of the Burmese python: broad regulation of integrated performance

As an apparent adaptation to predictably long episodes of fasting, the sit-and-wait foraging Burmese python experiences unprecedented regulation of gastrointestinal and cardiovascular performance with feeding and fasting. The ingestion of a meal signals the quiescent gut tissues to start secreting digestive acid and enzymes, to upregulate intestinal brush-border enzymes and nutrient transporters, and to grow. An integrated phenomenon, digestion is also characterized by increases in the mass, and presumably the function, of the heart, pancreas, liver and kidneys. Once digestion is complete, the python's stomach and small intestine rapidly downregulate performance. Much of the modulation of intestinal function can be explained by the 5-fold increase in microvillus length and apical surface area with feeding, and the subsequent shortening of the microvilli after digestion has finished. Digestion for the Burmese python is a relatively expensive endeavor, evident by the as much as a 44-fold increase in metabolic rate and equivalent in cost to as much as 37% of the meal's energy. Their large metabolic response is supported by substantial increases in ventilation and cardiac output and the apparent catabolism of glucose and lipids. Unmatched in the magnitude of its numerous physiological responses to feeding, the Burmese python is a very attractive model for examining the capacities and regulatory mechanisms of physiological performance.

Matched regulation of gastrointestinal performance in the Burmese python,Python molurus

In Burmese pythons fasting and feeding cause dramatic regulation of gastric acid production and intestinal nutrient uptake. Predictably, other components of their gastrointestinal tract are similarly regulated with each meal. We therefore assessed the matched regulation of gastrointestinal performance by comparing the postprandial activities and capacities of gastric (pepsin), pancreatic (amylase and trypsin) and intestinal (aminopeptidase-N and maltase) enzymes, and intestinal nutrient uptake. Tissue samples were collected from pythons fasted and at 0.25, 0.5, 1, 2, 3, 4, 6, 10 and 15 days following their consumption of rodent meals equaling 25% of snake body mass. With feeding, pythons experience no significant change in stomach mass, whereas both the pancreas and small intestine doubled in mass. Feeding also triggered a depletion of gastric mucosal pepsinogen, a respective 5.7- and 20-fold increase in the peak activities of pancreatic trypsin and amylase, and a respective 2.3- and 5.5-fold increase in the peak activities of intestinal maltase and aminopeptidase-N. Enzyme activities peaked between 2 and 4 days postfeeding and returned to fasting levels by day 10. Independent of digestive stage, python intestine exhibited a proximal to distal decline in enzyme activity. For both sugars and proteins, intestinal capacities for enzyme activity were significantly correlated with nutrient uptake capacities. The concomitant postprandial upregulation of tissue morphology, intestinal nutrient transport rates and enzyme activities illustrate, for the python, the matched regulation of their gastrointestinal performance with each meal.

Fructan Supplementation and Infection Affect Food Intake, Fever, and Epithelial Sloughing from Salmonella Challenge in Weanling Puppies , ,3

Our objective was to examine the effects of fructan supplementation on the immune response of weanling puppies subjected to bacterial challenge. Previous studies in bacterial challenged neonatal piglets have reported benefits of fructan supplementation. Thirty hound-cross puppies (12 wk of age) were used in a 2 × 3 factorial randomized complete block design. Following a 7-d baseline period, puppies were assigned to diets containing: 1) no prebiotic, 2) 1% short-chain fructooligosaccharides (scFOS), or 3) 1% inulin. After 14 d on treatment diet, dogs received an oral gavage of: 1) Salmonella typhimurium DT104 (5 × 108 colony forming units) or 2) 0.9% saline. Food intake, fecal and activity scores, body temperature, body weight, blood chemistry, intestinal nutrient transport, intestinal morphology and pathology, and gut microbiota were measured. Food intake decreased (P < 0.01) and body temperature increased (P < 0.05) in infected puppies. However, the decrease in food intake was less (P < 0.05) in those consuming fructans. Infected puppies consuming fructans also had decreased (P = 0.05) severity of enterocyte sloughing than those fed the control diet. Ileal Na+-dependent glucose transport was decreased (P = 0.02) in infected vs. noninfected puppies consuming CON, whereas no changes occurred in fructan-supplemented animals. Puppies consuming inulin also had increased fecal acetate (P = 0.03) and total short-chain fatty acid (P = 0.06) concentrations than scFOS-fed puppies and controls. Finally, puppies fed inulin had an increase (P = 0.05) in Lactobacillus concentrations compared with scFOS and CON. In summary, fructan supplementation appeared to attenuate some of the negative responses associated with Salmonella challenge and may provide protection against infection in weanling puppies.

Developmental Regulation of Nutrient Transporter and Enzyme mRNA Abundance in the Small Intestine of Broilers

The objective of this study was to investigate intestinal nutrient transporter and enzyme mRNA in broilers selected on corn- and soybean-based (line A) or wheat-based (line B) diets. We investigated the peptide transporter PepT1, 10 amino acid transporters (rBAT, b(o,+)AT, ATB(o,+), CAT1, CAT2, LAT1, y(+)LAT1, y(+)LAT2, B(o)AT, and EAAT3), 4 sugar transporters (SGLT1, SGLT5, GLUT5, and GLUT2), and a digestive enzyme (aminopeptidase N). Intestine was collected at embryo d 18 and 20, day of hatch, and d 1, 3, 7, and 14 posthatch. The mRNA abundance of each gene was assayed using real-time PCR and the absolute quantification method. For PepT1, line B had greater quantities of mRNA compared with line A (P = 0.001), suggesting a greater capacity for absorption of amino acids as peptides. Levels of PepT1 mRNA were greatest in the duodenum (P < 0.05), whereas the abundances of SGLT1, GLUT5, and GLUT2 mRNA were greatest in the jejunum (P < 0.05). Abundances of EAAT3, b(o,+)AT, rBAT, B(o)AT, LAT1, CAT2, SGLT5, and aminopeptidase N mRNA were greatest in the ileum (P < 0.05). Quantities of PepT1, EAAT3, B(o)AT, SGLT1, GLUT5, and GLUT2 mRNA increased linearly (P < 0.01), whereas CAT1, CAT2, y(+)LAT1, and LAT1 mRNA decreased linearly (P < 0.05) with age. Abundance of y(+)LAT2 mRNA changed cubically (P = 0.002) with peaks of expression at day of hatch and d 7, and aminopeptidase N and SGLT5 mRNA changed quadratically (P = 0.005) with age. These results provide a comprehensive profile of the temporal and spatial expression of nutrient transporter mRNA in the small intestine of chicks.

Changes in small intestinal nutrient transport and barrier function after lipopolysaccharide exposure in two pig breeds1

Specific pig breeds with unique characteristics have been developed, and the current study sought to characterize some of these differences. Using modified Ussing chambers, electrophysiological mucosal transport of D-glucose, L-Gln, L-Pro, L-Arg, L-Thr, and glycylsarcosine was assessed in small intestinal tissues (duodenum, jejunum, ileum) taken from Yorkshire-based hybrid (BW = 142.4 +/- 2.0 kg; mean age = 8 mo) and Meishan (BW = 65.8 +/- 0.8 kg; mean age = 6 mo) female pigs after 4 h of lipopolysaccharide (LPS) exposure. Gilts were randomly assigned to control (saline infusion; n = 6 Yorkshires, n = 5 Meishans) or LPS (n = 7 Yorkshires, n = 5 Meishans) groups. Therefore, treatments were arranged in a 2 (breed) x 2 (LPS infusion) factorial. Four hours after infusions, pigs were euthanized, and intestinal segment samples were removed. Glucose transport in the ileum was decreased (P < 0.001) in Yorkshires with LPS but was increased (P < 0.001) by over 2-fold in Meishans with LPS. After LPS infusion, Pro transport was increased in duodenum (over 5-fold; P = 0.04) and ileum (over 10-fold; P < 0.001) of Meishans but was unaffected in Yorkshires. Arginine transport in the ileum of control Meishans was greater (P = 0.05) than Arg transport in control Yorkshires. Glycylsarcosine transport was greater (P = 0.02) in Meishans than Yorkshires (nearly 2-fold), regardless of LPS provision. Glycylsarcosine transport was increased (P = 0.003) over 2-fold by LPS, regardless of pig breed. Resistance (barrier function) was increased (P = 0.03) by LPS in Yorkshires but was unaffected in Meishans. The current study indicates that small intestinal function responded differently to LPS in Yorkshire and Meishan gilts and that these effects were nutrient- and segment-dependent.

Adaptive regulation of digestive performance in the genusPython

The adaptive interplay between feeding habits and digestive physiology is demonstrated by the Burmese python, which in response to feeding infrequently has evolved the capacity to widely regulate gastrointestinal performance with feeding and fasting. To explore the generality of this physiological trait among pythons, we compared the postprandial responses of metabolism and both intestinal morphology and function among five members of the genus Python: P. brongersmai, P. molurus, P. regius, P. reticulatus and P. sebae. These infrequently feeding pythons inhabit Africa, southeast Asia and Indonesia and vary in body shape from short and stout (P. brongersmai) to long and slender (P. reticulatus). Following the consumption of rodent meals equaling 25% of snake body mass, metabolic rates of pythons peaked at 1.5 days at levels 9.9- to 14.5-fold of standard metabolic rates before returning to prefeeding rates by day 6-8. Specific dynamic action of these meals (317-347 kJ) did not differ among species and equaled 23-27% of the ingested energy. For each species, feeding triggered significant upregulation of intestinal nutrient transport and aminopeptidase-N activity. Concurrently, intestinal mass doubled on average for the five species, in part due to an 85% increase in mucosal thickness, itself a product of 27-59% increases in enterocyte volume. The integrative response of intestinal functional upregulation and tissue hypertrophy enables each of these five python species, regardless of body shape, to modulate intestinal performance to meet the demands of their large infrequent meals.