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Sample records for intestinal peptide transporter

  1. In vitro studies on intestinal peptide transport in horses.

    PubMed

    Cehak, A; Schröder, B; Feige, K; Breves, G

    2013-11-01

    Published data on the physiology of nutrient transport across the equine intestine are limited, and the existence and relevance of peptide transporters are still unknown in the horse. In the present study, the equine intestinal peptide transport was investigated by Ussing chamber experiments using the radioisotope tracer technique and by uptake studies into brush border membrane vesicles (BBMV). Jejunal mucosae of 16 healthy adult horses were used. Tissue samples were mounted in Ussing chambers, and electrophysiological parameters as well as unidirectional flux rates of the radiolabelled dipeptide glycylglutamine (Gly-Gln) were determined. The short-circuit current (Isc) response to the luminal addition of Gly-Gln was significantly greater compared to the Isc response to glycylsarcosine (Gly-Sar) addition (P<0.01). Positive net flux rates were determined indicating absorption of the dipeptide. The addition of Gly-Sar reduced the flux rates significantly (P<0.01), suggesting that both peptides compete for the same transport system. The flux rates were not affected by changes in luminal pH value. Uptake studies into BBMV demonstrated an uphill transport in both the absence and the presence of an inwardly directed H+-gradient with the H+-mediated uphill transport being significantly greater than the transport under equilibrium conditions (P<0.001). A Na+-gradient did not cause an uphill transport. The Gly-Gln uptakes displayed Michaelis-Menten kinetics with the Km value for the H+-dependent Gly-Gln uptake being significantly different from the Km value for the Gly-Gln uptake under equilibrium conditions (P<0.05). In conclusion, the study demonstrated for the first time that dipeptides are transcellularly transported across the equine small intestine. The results indicate the presence of at least 2 transport systems for peptide absorption in the horse: 1 secondary active H+-mediated cotransport and 1 that is capable of an uphill transport energized by a mechanism other

  2. Transport of Antihypertensive Peptide RVPSL, Ovotransferrin 328-332, in Human Intestinal Caco-2 Cell Monolayers.

    PubMed

    Ding, Long; Wang, Liying; Zhang, Yan; Liu, Jingbo

    2015-09-23

    The objective of this study was to investigate the transepithelial transport of RVPSL (Arg-Val-Pro-Ser-Leu), an egg-white-derived peptide with angiotensin I-converting enzyme (ACE) inhibitory and antihypertensive activity, in human intestinal Caco-2 cell monolayers. Results revealed that RVPSL could be passively transported across Caco-2 cell monolayers. However, during the process of transport, 36.31% ± 1.22% of the initial RVPSL added to the apical side was degraded, but this degradation decreased to 23.49% ± 0.68% when the Caco-2 cell monolayers were preincubated with diprotin A (P < 0.001), suggesting that RVPSL had a low resistance to various brush border membrane peptidases. When transport from the apical side to the basolateral side was investigated, the apparent permeability coefficient (Papp) was (6.97 ± 1.11) × 10(-6) cm/s. The transport route of RVPSL appears to be the paracellular pathway via tight junctions, as only cytochalasin D, a disruptor of tight junctions (TJs), significantly increased the transport rate (P < 0.001). In addition, the relationship between the structure of RVPSL and transport across Caco-2 cell monolayers was studied by mutation of RVPSL. It was found that N-terminal Pro residues were more beneficial for transport of pentapeptides across Caco-2 cell monolayers than Arg and Val. Furthermore, RVPSL could be more easily transported as smaller peptides, especially in the form of dipeptides and tripeptides.

  3. Effects of cysteamine supplementation on the intestinal expression of amino acid and peptide transporters and intestinal health in finishing pigs.

    PubMed

    Zhou, Ping; Luo, Yiqiu; Zhang, Lin; Li, Jiaolong; Zhang, Bolin; Xing, Shen; Zhu, Yuping; Gao, Feng; Zhou, Guanghong

    2017-02-01

    This study aimed to evaluate the effects of cysteamine supplementation on the expression of jejunal amino acid and peptide transporters and intestinal health in finishing pigs. Sixty barrows were allocated into two experimental diets consisting of a basal control diet supplemented with 0 or 142 mg/kg cysteamine. After 41 days, 10 pigs per treatment were slaughtered. The results showed that cysteamine supplementation increased the apparent digestibility of crude protein (CP) (P < 0.05) and the trypsin activity in jejunal digesta (P < 0.01). Cysteamine supplementation also increased the messenger RNA abundance of SLC7A7, SLC7A9 and SLC15A1, occludin, claudin-1 and zonula occludens protein-1 (P < 0.001) in the jejunum mucosa. Increased glutathione content (P < 0.01) and glutathione peroxidase activity (P < 0.05) and decreased malondialdehyde content (P < 0.01) were observed in pigs receiving cysteamine. Additionally, cysteamine supplementation increased the concentrations of secretory immunoglobulin A (IgA) (P < 0.05), IgM (P < 0.001) and IgG (P < 0.001) in the jejunal mucosa. It is concluded that cysteamine supplementation could influence protein digestion and absorption via increasing trypsin activity, enhancing the digestibility of CP, and promoting the expression of jejunal amino acid and peptide transporters. Moreover, cysteamine improved intestinal integrity, antioxidant capacity and immune function in the jejunum, which were beneficial for intestinal health.

  4. Salinity-Dependent Shift in the Localization of Three Peptide Transporters along the Intestine of the Mozambique Tilapia (Oreochromis mossambicus)

    PubMed Central

    Con, Pazit; Nitzan, Tali; Cnaani, Avner

    2017-01-01

    The peptide transporter (PepT) systems are well-known for their importance to protein absorption in all vertebrate species. These symporters use H+ gradient at the apical membrane of the intestinal epithelial cells to mediate the absorption of small peptides. In fish, the intestine is a multifunctional organ, involved in osmoregulation, acid-base regulation, and nutrient absorption. Therefore, we expected environmental stimuli to affect peptide absorption. We examined the effect of three environmental factors; salinity, pH and feeding, on the expression, activity and localization of three PepT transporters (PepT1a, PepT1b, PepT2) along the intestine of the Mozambique tilapia (Oreochromis mossambicus). Quantitative real time PCR (qPCR) analysis demonstrated that the two PepT1 variants are typical to the proximal intestinal section while PepT2 is typical to the distal intestinal sections. Immunofluorescence analysis with custom-made antibodies supported the qPCR results, localized both transporters on the apical membrane of enterocytes and provided the first evidence for the participation of PepT2 in nutrient absorption. This first description of segment-specific expression and localization points to a complementary role of the different peptide transporters, corresponding to the changes in nutrient availability along the intestine. Both gene expression and absorption activity assays showed that an increase in water salinity shifted the localization of the PepT genes transcription and activity down along the intestinal tract. Additionally, an unexpected pH effect was found on the absorption of small peptides, with increased activity at higher pH levels. This work emphasizes the relationships between different functions of the fish intestine and how they are affected by environmental conditions. PMID:28167916

  5. Glycans in the intestinal peptide transporter PEPT1 contribute to function and protect from proteolysis.

    PubMed

    Stelzl, Tamara; Geillinger-Kästle, Kerstin Elisabeth; Stolz, Jürgen; Daniel, Hannelore

    2017-03-23

    Despite the fact that many membrane proteins carry extracellular glycans, little is known about whether the glycan chains also affect protein function. We recently demonstrated that the proton-coupled oligopeptide transporter 1 (PEPT1) in the intestine is glycosylated at six asparagine residues (N50, N406, N439, N510, N515, N532). Mutagenesis-induced disruption of the individual N-glycosylation site N50, which is highly conserved among mammals, was detected to significantly enhance the PEPT1 mediated inward transport of peptides. Here, we show for the murine protein, that the inhibition of glycosylation at sequon N50 by substituting N50 with glutamine, lysine or cysteine, or by replacing S52 with alanine, equally altered PEPT1 transport kinetics in oocytes. Further, we provide evidence that the uptake of [(14)C]-glycyl-sarcosine in immortalized murine small intestinal (Mode-K) or colonic epithelial (PTK-6) cells stably expressing the PEPT1 transporter N50Q is also significantly increased relative to the wild type protein. By using electrophysiological recordings and tracer flux studies, we further demonstrate that the rise in transport velocity observed for PEPT1 N50Q is bidirectional. In line with these findings, we show that attachment of biotin derivatives, comparable in weight to 2-4 monosaccharides, to the PEPT1 N50C transporter slows down the transport velocity. In addition, our experiments provide strong evidence that glycosylation of PEPT1 confers resistance against proteolytic cleavage by proteinase K, while a remarkable intrinsic stability against trypsin, even in absence of N-linked glycans, was detected.

  6. Enteroendocrine-derived glucagon-like peptide-2 controls intestinal amino acid transport.

    PubMed

    Lee, Jennifer; Koehler, Jacqueline; Yusta, Bernardo; Bahrami, Jasmine; Matthews, Dianne; Rafii, Mahroukh; Pencharz, Paul B; Drucker, Daniel J

    2017-03-01

    Glucagon-like peptide-2 (GLP-2) is co-secreted with GLP-1 from gut endocrine cells, and both peptides act as growth factors to expand the surface area of the mucosal epithelium. Notably, GLP-2 also enhances glucose and lipid transport in enterocytes; however, its actions on control of amino acid (AA) transport remain unclear. Here we examined the mechanisms linking gain and loss of GLP-2 receptor (GLP-2R) signaling to control of intestinal amino acid absorption in mice. Absorption, transport, and clearance of essential AAs, specifically lysine, were measured in vivo by Liquid Chromatography triple quadrupole Mass Spectrometry (LC-MS/MS) and ex vivo with Ussing chambers using intestinal preparations from Glp2r(+/+) and Glp2r(-/-) mice. Immunoblotting determined jejunal levels of protein components of signaling pathways (PI3K-AKT, and mTORC1-pS6-p4E-BP1) following administration of GLP-2, protein gavage, and rapamycin to fasted Glp2r(+/+) and Glp2r(-/-) mice. Expression of AA transporters from full thickness jejunum and 4F2hc from brush border membrane vesicles (BBMVs) was measured by real-time PCR and immunoblotting, respectively. Acute administration of GLP-2 increased basal AA absorption in vivo and augmented basal lysine transport ex vivo. GLP-2-stimulated lysine transport was attenuated by co-incubation with wortmannin, rapamycin, or tetrodotoxin ex vivo. Phosphorylation of mTORC1 effector proteins S6 and 4E-BP1 was significantly increased in wild-type mice in response to GLP-2 alone, or when co-administered with protein gavage, and abolished following oral gavage of rapamycin. In contrast, activation of GLP-1R signaling did not enhance S6 phosphorylation. Disruption of GLP-2 action in Glp2r(-/-) mice reduced lysine transport ex vivo and attenuated the phosphorylation of S6 and 4E-BP1 in response to oral protein. Moreover, the expression of cationic AA transporter slc7a9 in response to refeeding, and the abundance of 4F2hc in BBMVs following protein gavage

  7. Expression of an antimicrobial peptide, digestive enzymes and nutrient transporters in the intestine of E. praecox-infected chickens

    USDA-ARS?s Scientific Manuscript database

    Coccidiosis is a major intestinal disease of poultry, caused by several species of the protozoan Eimeria. The objective of this study was to examine changes in expression of digestive enzymes, nutrient transporters and an antimicrobial peptide following an Eimeria praecox challenge of chickens at d...

  8. Guanylin peptides regulate electrolyte and fluid transport in the Gulf toadfish (Opsanus beta) posterior intestine.

    PubMed

    Ruhr, Ilan M; Bodinier, Charlotte; Mager, Edward M; Esbaugh, Andrew J; Williams, Cameron; Takei, Yoshio; Grosell, Martin

    2014-11-01

    The physiological effects of guanylin (GN) and uroguanylin (UGN) on fluid and electrolyte transport in the teleost fish intestine have yet to be thoroughly investigated. In the present study, the effects of GN, UGN, and renoguanylin (RGN; a GN and UGN homolog) on short-circuit current (Isc) and the transport of Cl-, Na+, bicarbonate (HCO3-), and fluid in the Gulf toadfish (Opsanus beta) intestine were determined using Ussing chambers, pH-stat titration, and intestinal sac experiments. GN, UGN, and RGN reversed the Isc of the posterior intestine (absorptive-to-secretory), but not of the anterior intestine. RGN decreased baseline HCO3- secretion, but increased Cl- and fluid secretion in the posterior intestine. The secretory response of the posterior intestine coincides with the presence of basolateral NKCC1 and apical cystic fibrosis transmembrane conductance regulator (CFTR), the latter of which is lacking in the anterior intestine and is not permeable to HCO3- in the posterior intestine. However, the response to RGN by the posterior intestine is counterintuitive given the known role of the marine teleost intestine as a salt- and water-absorbing organ. These data demonstrate that marine teleosts possess a tissue-specific secretory response, apparently associated with seawater adaptation, the exact role of which remains to be determined. Copyright © 2014 the American Physiological Society.

  9. Intestinal expression of peptide transporter 1 (PEPT1) at different life stages of Japanese eel, Anguilla japonica.

    PubMed

    Ahn, Hyojin; Yamada, Yoshiaki; Okamura, Akihiro; Tsukamoto, Katsumi; Kaneko, Toyoji; Watanabe, Soichi

    2013-10-01

    The expression of peptide transporter 1 (PEPT1) was investigated at the different life stages of Japanese eel, Anguilla japonica. The cDNA encoding Japanese eel PEPT1 was cloned and sequenced. The hydrophilicity plot analysis of its deduced amino acid sequence showed high similarities with topological features of known PEPT1 molecules in other species. Tissue distribution analysis confirmed that PEPT1 mRNA was detected specifically in the anterior and posterior intestines of adult eel. In eel larvae at 13days post hatching (dph), PEPT1 mRNA expression was mainly detected in the intestinal tract regions. The trypsinogen mRNA was only detected in the gastric region including the pancreas. Intense immunoreaction for PEPT1 was observed in the apical membrane of the intestinal epithelial cells of both larval and adult eel. These results indicated that PEPT1 was an intestine-specific transporter, which was localized at the luminal side of the epithelial cells, suggesting that di/tri-peptide absorption via PEPT1 takes place in the eel intestine. According to the ontogenetic analyses by quantitative PCR, PEPT1 and trypsinogen mRNA expressions were simultaneously increased at 5-7 dph. It is thus assumed that nutrient absorption systems in the intestinal tracts of larvae become functional at this age.

  10. The Intestinal Peptide Transporter PEPT1 Is Involved in Food Intake Regulation in Mice Fed a High-Protein Diet

    PubMed Central

    Sailer, Manuela; Daniel, Hannelore

    2011-01-01

    High-protein diets are effective in achieving weight loss which is mainly explained by increased satiety and thermogenic effects. Recent studies suggest that the effects of protein-rich diets on satiety could be mediated by amino acids like leucine or arginine. Although high-protein diets require increased intestinal amino acid absorption, amino acid and peptide absorption has not yet been considered to contribute to satiety effects. We here demonstrate a novel finding that links intestinal peptide transport processes to food intake, but only when a protein-rich diet is provided. When mice lacking the intestinal peptide transporter PEPT1 were fed diets containing 8 or 21 energy% of protein, no differences in food intake and weight gain were observed. However, upon feeding a high-protein (45 energy%) diet, Pept1−/− mice reduced food intake much more pronounced than control animals. Although there was a regain in food consumption after a few days, no weight gain was observed which was associated with a reduced intestinal energy assimilation and increased fecal energy losses. Pept1−/− mice on high-protein diet displayed markedly reduced plasma leptin levels during the period of very low food intake, suggesting a failure of leptin signaling to increase energy intake. This together with an almost two-fold elevated plasma arginine level in Pept1−/− but not wildtype mice, suggests that a cross-talk of arginine with leptin signaling in brain, as described previously, could cause these striking effects on food intake. PMID:22031831

  11. Oral peptide specific egg antibody to intestinal sodium-dependent phosphate co-transporter-2b is effective at altering phosphate transport in vitro and in vivo.

    PubMed

    Bobeck, Elizabeth A; Hellestad, Erica M; Sand, Jordan M; Piccione, Michelle L; Bishop, Jeff W; Helvig, Christian; Petkovich, Martin; Cook, Mark E

    2015-06-01

    Hyperimmunized hens are an effective means of generating large quantities of antigen specific egg antibodies that have use as oral supplements. In this study, we attempted to create a peptide specific antibody that produced outcomes similar to those of the human pharmaceutical, sevelamer HCl, used in the treatment of hyperphosphatemia (a sequela of chronic renal disease). Egg antibodies were generated against 8 different human intestinal sodium-dependent phosphate cotransporter 2b (NaPi2b) peptides, and hNaPi2b peptide egg antibodies were screened for their ability to inhibit phosphate transport in human intestinal Caco-2 cell line. Antibody produced against human peptide sequence TSPSLCWT (anti-h16) was specific for its peptide sequence, and significantly reduced phosphate transport in human Caco-2 cells to 25.3±11.5% of control nonspecific antibody, when compared to nicotinamide, a known inhibitor of phosphate transport (P≤0.05). Antibody was then produced against the mouse-specific peptide h16 counterpart (mouse sequence TSPSYCWT, anti-m16) for further analysis in a murine model. When anti-m16 was fed to mice (1% of diet as dried egg yolk powder), egg yolk immunoglobulin (IgY) was detected using immunohistochemical staining in mouse ileum, and egg anti-m16 IgY colocalized with a commercial goat anti-NaPi2b antibody. The effectiveness of anti-m16 egg antibody in reducing serum phosphate, when compared to sevelamer HCl, was determined in a mouse feeding study. Serum phosphate was reduced 18% (P<0.02) in mice fed anti-m16 (1% as dried egg yolk powder) and 30% (P<0.0001) in mice fed sevelamer HCl (1% of diet) when compared to mice fed nonspecific egg immunoglobulin. The methods described and the findings reported show that oral egg antibodies are useful and easy to prepare reagents for the study and possible treatment of select diseases.

  12. Role of Vagal Innervation in Diurnal Rhythm of Intestinal Peptide Transporter 1 (PEPT1)

    PubMed Central

    Qandeel, Hisham G.; Alonso, Fernando; Hernandez, David J.; Duenes, Judith A.; Zheng, Ye; Scow, Jeffrey S.; Sarr, Michael G.

    2010-01-01

    BACKGROUND: Protein is absorbed predominantly as di/tripeptides via H+/peptide cotransporter-1 (PEPT1). We demonstrated previously diurnal variations in expression and function of duodenal and jejunal but not ileal PEPT1; neural regulation of this pattern is unexplored. HYPOTHESIS: Complete abdominal vagotomy abolishes diurnal variations in gene expression and transport function of PEPT1. METHODS: 24 rats maintained in a 12-h light/dark room [6AM-6PM] underwent abdominal vagotomy; 24 other rats were controls. Four weeks later, mucosal levels of mRNA and protein were measured at 9AM, 3PM, 9PM, and 3AM (n=6 each) by quantitative real time-PCR and Western blots, respectively; transporter-mediated uptake of di-peptide (Gly-Sar) was measured by the everted-sleeve technique. RESULTS: Diurnal variation in mRNA, as in controls, was retained post-vagotomy in duodenum and jejunum (peak at 3PM, p<0.05) but not in ileum. Diurnal variations in expression of protein and Gly-Sar uptake, however, were absent post-vagotomy (p>0.3). Similar to controls, maximal uptake was in jejunum after vagotomy (Vmax-nmol/cm/min: jejunum vs. duodenum and ileum; 163 vs. 88 and 71 at 3AM; p<0.04); Km remained unchanged. CONCLUSIONS: Vagal innervation appears to mediate in part diurnal variations in protein expression and transport function of PEPT1, but not diurnal variation in mRNA expression of PEPT1. PMID:19707837

  13. Characteristics of transmural potential changes associated with the proton-peptide co-transport in toad small intestine.

    PubMed

    Abe, M; Hoshi, T; Tajima, A

    1987-12-01

    1. Ionic dependence and kinetic properties of the peptide-evoked potentials across everted toad intestine were investigated with eighteen dipeptides and four tripeptides. All peptides evoked saturable increases in the mucosal negativity regardless of the presence of Na+. 2. The peptide-evoked potentials recorded in the absence of Na+ were sensitive to external pH (pHo); lowering pHo from 7.4 to 6.5 and 5.5 caused stepwise increases in their amplitude. 3. Loading epithelial cells with 9-aminoacridine or acetate caused a significant increase or decrease in amplitude of the Gly-Gly-evoked potential, suggesting intracellular alkalinization or acidification also has a great influence on the peptide-evoked potential. 4. Kinetically, Na+-independent peptide-evoked potentials conformed to simple Michaelis-Menten kinetics, and lowering pHo caused a decrease of the half-saturation concentration (Kt) for Gly-Gly without changing the maximum potential difference increase. Similar affinity-type kinetic effect was also seen for Gly-Gly influx. 5. Simultaneous measurements of Gly-Gly-induced increase in short-circuit current and Gly-Gly influx revealed that the coupling ratio of H+ and Gly-Gly flows was 1.78 +/- 0.12, suggesting the stoichiometry of the H+-peptide co-transport being 2:1. 6. Kinetic analyses of the peptide-evoked potentials indicated that all glycyl-dipeptides tested (Gly-Gly, Gly-Pro, Gly-Sar, Gly-Leu, Gly-Phe) and other dipeptides (Ala-Ala, Ala-Phe, Phe-Ala) shared a common carrier. Gly-Gly-Gly and Ala-Ala-Ala were also found to share the same carrier, while Phe-Phe, Leu-Leu and Phe-Leu appeared to be transported by a different carrier. 7. Kt values for di- and tripeptides, which apparently shared a common carrier, fell in a narrow range (0.5-2.2 mM). There was no clear correlation between 1/Kt value and molecular weight.

  14. The mRNA expression of amino acid transporters, aminopeptidase, and the di- and tri-peptide transporter PepT1 in the intestine and liver of post-hatch broiler chicks

    USDA-ARS?s Scientific Manuscript database

    Amino acid transporter (AAT) proteins are responsible for the movement of amino acids (AA) in and out of cells. Aminopeptidase (APN) cleaves AAs from the N terminus of polypeptides making them available for transport, while PepT1 is a di- and tri- peptide transporter. In the intestine, these prote...

  15. PI3K p110α/Akt signaling negatively regulates secretion of the intestinal peptide neurotensin through interference of granule transport.

    PubMed

    Li, Jing; Song, Jun; Cassidy, Margaret G; Rychahou, Piotr; Starr, Marlene E; Liu, Jianyu; Li, Xin; Epperly, Garretson; Weiss, Heidi L; Townsend, Courtney M; Gao, Tianyan; Evers, B Mark

    2012-08-01

    Neurotensin (NT), an intestinal peptide secreted from N cells in the small bowel, regulates a variety of physiological functions of the gastrointestinal tract, including secretion, gut motility, and intestinal growth. The class IA phosphatidylinositol 3-kinase (PI3K) family, which comprised of p110 catalytic (α, β and δ) and p85 regulatory subunits, has been implicated in the regulation of hormone secretion from endocrine cells. However, the underlying mechanisms remain poorly understood. In particular, the role of PI3K in intestinal peptide secretion is not known. Here, we show that PI3K catalytic subunit, p110α, negatively regulates NT secretion in vitro and in vivo. We demonstrate that inhibition of p110α, but not p110β, induces NT release in BON, a human endocrine cell line, which expresses NT mRNA and produces NT peptide in a manner analogous to N cells, and QGP-1, a pancreatic endocrine cell line that produces NT peptide. In contrast, overexpression of p110α decreases NT secretion. Consistently, p110α-inhibition increases plasma NT levels in mice. To further delineate the mechanisms contributing to this effect, we demonstrate that inhibition of p110α increases NT granule trafficking by up-regulating α-tubulin acetylation; NT secretion is prevented by overexpression of HDAC6, an α-tubulin deacetylase. Moreover, ras-related protein Rab27A (a small G protein) and kinase D-interacting substrate of 220 kDa (Kidins220), which are associated with NT granules, play a negative and positive role, respectively, in p110α-inhibition-induced NT secretion. Our findings identify the critical role and novel mechanisms for the PI3K signaling pathway in the control of intestinal hormone granule transport and release.

  16. PI3K p110α/Akt Signaling Negatively Regulates Secretion of the Intestinal Peptide Neurotensin Through Interference of Granule Transport

    PubMed Central

    Li, Jing; Song, Jun; Cassidy, Margaret G.; Rychahou, Piotr; Starr, Marlene E.; Liu, Jianyu; Li, Xin; Epperly, Garretson; Weiss, Heidi L.; Townsend, Courtney M.; Gao, Tianyan

    2012-01-01

    Neurotensin (NT), an intestinal peptide secreted from N cells in the small bowel, regulates a variety of physiological functions of the gastrointestinal tract, including secretion, gut motility, and intestinal growth. The class IA phosphatidylinositol 3-kinase (PI3K) family, which comprised of p110 catalytic (α, β and δ) and p85 regulatory subunits, has been implicated in the regulation of hormone secretion from endocrine cells. However, the underlying mechanisms remain poorly understood. In particular, the role of PI3K in intestinal peptide secretion is not known. Here, we show that PI3K catalytic subunit, p110α, negatively regulates NT secretion in vitro and in vivo. We demonstrate that inhibition of p110α, but not p110β, induces NT release in BON, a human endocrine cell line, which expresses NT mRNA and produces NT peptide in a manner analogous to N cells, and QGP-1, a pancreatic endocrine cell line that produces NT peptide. In contrast, overexpression of p110α decreases NT secretion. Consistently, p110α-inhibition increases plasma NT levels in mice. To further delineate the mechanisms contributing to this effect, we demonstrate that inhibition of p110α increases NT granule trafficking by up-regulating α-tubulin acetylation; NT secretion is prevented by overexpression of HDAC6, an α-tubulin deacetylase. Moreover, ras-related protein Rab27A (a small G protein) and kinase D-interacting substrate of 220 kDa (Kidins220), which are associated with NT granules, play a negative and positive role, respectively, in p110α-inhibition-induced NT secretion. Our findings identify the critical role and novel mechanisms for the PI3K signaling pathway in the control of intestinal hormone granule transport and release. PMID:22700584

  17. Dietary protein composition influences abundance of peptide and amino acid transporter messenger ribonucleic acid in the small intestine of 2 lines of broiler chicks.

    PubMed

    Gilbert, E R; Li, H; Emmerson, D A; Webb, K E; Wong, E A

    2010-08-01

    This study evaluated the effect of dietary protein composition on mRNA abundance of a peptide transporter (peptide transporter 1, PepT1), amino acid (AA) transporters [Na(+)-independent cationic and zwitterionic AA transporter (b(o,+)AT), excitatory AA transporter 3 (EAAT3), Na(+)-independent cationic and Na(+)-dependent neutral AA transporter 2 (y(+)LAT2), L-type AA transporter 1 (LAT1), and cationic AA transporter 1 (CAT1)], and a digestive enzyme (aminopeptidase N) in 2 lines (A and B) of broilers that differentially express PepT1 mRNA (line B > line A). From d 8 to 15 posthatch, birds were fed 1 of 3 diets. Protein sources included whey protein concentrate, a whey partial hydrolysate (WPH), or a mixture of free AA (AA) identical to the composition of whey. Quantities of mRNA were assayed by real-time PCR in the small intestine of males at d 8, 9, 11, 13, and 15. For all genes except LAT1, abundance of mRNA was greatest in line B birds that consumed the WPH diet (P < 0.006). When mRNA abundance was normalized to beta-actin quantities, this effect disappeared, demonstrating a generalized effect on gene expression in line B birds that consumed the hydrolysate. There was a greater villus height:crypt depth ratio (P < 0.05) in line B birds fed the WPH diet as compared with line A. In conclusion, line B birds, which express greater PepT1, displayed enhanced intestinal mucosal absorptive surface area and differential regulation of PepT1, AA transporters, and aminopeptidase N in response to dietary protein composition.

  18. Supplementation with branched-chain amino acids to a low-protein diet regulates intestinal expression of amino acid and peptide transporters in weanling pigs.

    PubMed

    Zhang, Shihai; Qiao, Shiyan; Ren, Man; Zeng, Xiangfang; Ma, Xi; Wu, Zhenlong; Thacker, Philip; Wu, Guoyao

    2013-11-01

    This study determined the effects of dietary branched-chain amino acids (AA) (BCAA) on growth performance, expression of jejunal AA and peptide transporters, and the colonic microflora of weanling piglets fed a low-protein (LP) diet. One hundred and eight Large White × Landrace × Duroc piglets (weaned at 28 days of age) were fed a normal protein diet (NP, 20.9 % crude protein), an LP diet (LP, 17.1 % crude protein), or an LP diet supplemented with BCAA (LP + BCAA, 17.9 % crude protein) for 14 days. Dietary protein restriction reduced piglet growth performance and small-intestinal villous height, which were restored by BCAA supplementation to the LP diet to values for the NP diet. Serum concentrations of BCAA were reduced in piglets fed the LP diet while those in piglets fed the LP + BCAA diet were similar to values for the NP group. mRNA levels for Na(+)-neutral AA exchanger-2, cationic AA transporter-1, b(0,+) AA transporter, and 4F2 heavy chain were more abundant in piglets fed the LP + BCAA diet than the LP diet. However, mRNA and protein levels for peptide transporter-1 were lower in piglets fed the LP + BCAA diet as compared to the LP diet. The colonic microflora did not differ among the three groups of pigs. In conclusion, growth performance, intestinal development, and intestinal expression of AA transporters in weanling piglets are enhanced by BCAA supplementation to LP diets. Our findings provide a new molecular basis for further understanding of BCAA as functional AA in animal nutrition.

  19. Bile acid-regulated peroxisome proliferator-activated receptor-α (PPARα) activity underlies circadian expression of intestinal peptide absorption transporter PepT1/Slc15a1.

    PubMed

    Okamura, Ayako; Koyanagi, Satoru; Dilxiat, Adila; Kusunose, Naoki; Chen, Jia Jun; Matsunaga, Naoya; Shibata, Shigenobu; Ohdo, Shigehiro

    2014-09-05

    Digested proteins are mainly absorbed as small peptides composed of two or three amino acids. The intestinal absorption of small peptides is mediated via only one transport system: the proton-coupled peptide transporter-1 (PepT1) encoded from the soluble carrier protein Slc15a1. In mammals, intestinal expression of PepT1/Slc15a1 oscillates during the daily feeding cycle. Although the oscillation in the intestinal expression of PepT1/Slc15a1 is suggested to be controlled by molecular components of circadian clock, we demonstrated here that bile acids regulated the oscillation of PepT1/Slc15a1 expression through modulating the activity of peroxisome proliferator-activated receptor α (PPARα). Nocturnally active mice mainly consumed their food during the dark phase. PPARα activated the intestinal expression of Slc15a1 mRNA during the light period, and protein levels of PepT1 peaked before the start of the dark phase. After food intake, bile acids accumulated in intestinal epithelial cells. Intestinal accumulated bile acids interfered with recruitment of co-transcriptional activator CREB-binding protein/p300 on the promoter region of Slc15a1 gene, thereby suppressing PPARα-mediated transactivation of Slc15a1. The time-dependent suppression of PPARα-mediated transactivation by bile acids caused an oscillation in the intestinal expression of PepT1/Slc15a1 during the daily feeding cycle that led to circadian changes in the intestinal absorption of small peptides. These findings suggest a molecular clock-independent mechanism by which bile acid-regulated PPARα activity governs the circadian expression of intestinal peptide transporter.

  20. Peptide cotransporter 1 in intestine and organic anion transporters in kidney are targets of interaction between JBP485 and lisinopril in rats.

    PubMed

    Guo, Xinjin; Meng, Qiang; Liu, Qi; Wang, Changyuan; Mao, Qi; Sun, Huijun; Peng, Jinyong; Kaku, Taiichi; Liu, Kexin

    2012-01-01

    The purpose of this study was to clarify the pharmacokinetic mechanism of interaction between JBP485 (cyclo-trans-4-L-hydroxyprolyl-L-serine, a dipeptide with antihepatitis activity) and lisinopril (an angiotensin-converting enzyme inhibitor) in vitro and in vivo. When JBP485 and lisinopril were administered orally simultaneously, the plasma concentrations of the two drugs were decreased significantly, but few changes were observed after simultaneous intravenous administration of the two drugs. The uptake of JBP485 and lisinopril in everted intestinal sacs and in HeLa cells transfected with human peptide cotransporter 1 (PEPT1), as well as absorption of JBP485 and lisinopril after jejunal perfusion were reduced after simultaneous drug administration, which suggested that the first target of drug interaction was PEPT1 in the intestine during the absorption process. The cumulative urinary excretions and renal clearance of the two drugs were decreased after intravenous co-administration, while uptakes of the two drugs in kidney slices and hOAT1/hOAT3-transfected HEK293 cells were decreased. These results indicated that the second target of drug-drug interaction was located in the kidney. These findings confirmed that the pharmacokinetic mechanism of interaction between JBP485 and lisinopril could be explained by their inhibition of the same transporters in the intestinal mucosa (PEPT1) and kidneys (OATs).

  1. In Vitro and Clinical Evaluations of the Drug-Drug Interaction Potential of a Metabotropic Glutamate 2/3 Receptor Agonist Prodrug with Intestinal Peptide Transporter 1

    PubMed Central

    Long, Amanda J.; Annes, William F.; Witcher, Jennifer W.; Knadler, Mary Pat; Ayan-Oshodi, Mosun A.; Mitchell, Malcolm I.; Leese, Phillip; Hillgren, Kathleen M.

    2017-01-01

    Despite peptide transporter 1 (PEPT1) being responsible for the bioavailability for a variety of drugs, there has been little study of its potential involvement in drug-drug interactions. Pomaglumetad methionil, a metabotropic glutamate 2/3 receptor agonist prodrug, utilizes PEPT1 to enhance absorption and bioavailability. In vitro studies were conducted to guide the decision to conduct a clinical drug interaction study and to inform the clinical study design. In vitro investigations determined the prodrug (LY2140023 monohydrate) is a substrate of PEPT1 with Km value of approximately 30 µM, whereas the active moiety (LY404039) is not a PEPT1 substrate. In addition, among the eight known PEPT1 substrates evaluated in vitro, valacyclovir was the most potent inhibitor (IC50 = 0.46 mM) of PEPT1-mediated uptake of the prodrug. Therefore, a clinical drug interaction study was conducted to evaluate the potential interaction between the prodrug and valacyclovir in healthy subjects. No effect of coadministration was observed on the pharmacokinetics of the prodrug, valacyclovir, or either of their active moieties. Although in vitro studies showed potential for the prodrug and valacyclovir interaction via PEPT1, an in vivo study showed no interaction between these two drugs. PEPT1 does not appear to easily saturate because of its high capacity and expression in the intestine. Thus, a clinical interaction at PEPT1 is unlikely even with a compound with high affinity for the transporter. PMID:27895114

  2. cis-Peptide Bonds: A Key for Intestinal Permeability of Peptides? .

    PubMed

    Marelli, Udaya Kiran; Ovadia, Oded; Frank, Andreas Oliver; Chatterjee, Jayanta; Gilon, Chaim; Hoffman, Amnon; Kessler, Horst

    2015-10-19

    Recent structural studies on libraries of cyclic hexapeptides led to the identification of common backbone conformations that may be instrumental to the oral availability of peptides. Furthermore, the observation of differential Caco-2 permeabilities of enantiomeric pairs of some of these peptides strongly supports the concept of conformational specificity driven uptake and also suggests a pivotal role of carrier-mediated pathways for peptide transport, especially for scaffolds of polar nature. This work presents investigations on the Caco-2 and PAMPA permeability profiles of 13 selected N-methylated cyclic pentaalanine peptides derived from the basic cyclo(-D-Ala-Ala4 -) template. These molecules generally showed moderate to low transport in intestinal epithelia with a few of them exhibiting a Caco-2 permeability equal to or slightly higher than that of mannitol, a marker for paracellular permeability. We identified that the majority of the permeable cyclic penta- and hexapeptides possess an N-methylated cis-peptide bond, a structural feature that is also present in the orally available peptides cyclosporine A and the tri-N-methylated analogue of the Veber-Hirschmann peptide. Based on these observations it appears that the presence of N-methylated cis-peptide bonds at certain locations may promote the intestinal permeability of peptides through a suitable conformational preorganization. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Vasoactive intestinal peptide stimulates tracheal submucosal gland secretion in ferret

    SciTech Connect

    Peatfield, A.C.; Barnes, P.J.; Bratcher, C.; Nadel, J.A.; Davis, B.

    1983-07-01

    We studied the effect of vasoactive intestinal peptide (VIP) on the output of 35S-labeled macromolecules from ferret tracheal explants either placed in beakers or suspended in modified Ussing chambers. In Ussing chamber experiments, the radiolabel precursor, sodium (35S)sulfate, and all drugs were placed on the submucosal side of the tissue. Washings were collected at 30-min intervals from the luminal side and were dialyzed to remove unbound 35S, leaving radiolabeled macromolecules. Vasoactive intestinal peptide at 3 X 10(-7) M stimulated bound 35S output by a mean of + 252.6% (n . 14). The VIP response was dose-dependent with a near maximal response and a half maximal response at approximately 10(-6) M and 10(-8), M, respectively. The VIP effect was not inhibited by a mixture of tetrodotoxin, atropine, I-propranolol, and phentolamine. Vasoactive intestinal peptide had no effect on the electrical properties of the of the tissues. We conclude that VIP stimulates output of sulfated-macromolecules from ferret tracheal submucosal glands without stimulating ion transport. Our studies also suggest that VIP acts on submucosal glands via specific VIP receptors. Vasoactive intestinal peptide has been shown to increase intracellular levels of cyclic AMP, and we suggest that this may be the mechanism for its effect on the output of macromolecules. This mechanism may be important in the neural regulation of submucosal gland secretion.

  4. Intestinal digestive resistance of immunodominant gliadin peptides.

    PubMed

    Hausch, Felix; Shan, Lu; Santiago, Nilda A; Gray, Gary M; Khosla, Chaitan

    2002-10-01

    Two recently identified immunodominant epitopes from alpha-gliadin account for most of the stimulatory activity of dietary gluten on intestinal and peripheral T lymphocytes in patients with celiac sprue. The proteolytic kinetics of peptides containing these epitopes were analyzed in vitro using soluble proteases from bovine and porcine pancreas and brush-border membrane vesicles from adult rat intestine. We showed that these proline-glutamine-rich epitopes are exceptionally resistant to enzymatic processing. Moreover, as estimated from the residual peptide structure and confirmed by exogenous peptidase supplementation, dipeptidyl peptidase IV and dipeptidyl carboxypeptidase I were identified as the rate-limiting enzymes in the digestive breakdown of these peptides. A similar conclusion also emerged from analogous studies with brush-border membrane from a human intestinal biopsy. Supplementation of rat brush-border membrane with trace quantities of a bacterial prolyl endopeptidase led to the rapid destruction of the immunodominant epitopes in these peptides. These results suggest a possible enzyme therapy strategy for celiac sprue, for which the only current therapeutic option is strict exclusion of gluten-containing food.

  5. Models to predict intestinal absorption of therapeutic peptides and proteins.

    PubMed

    Antunes, Filipa; Andrade, Fernanda; Ferreira, Domingos; Nielsen, Hanne Morck; Sarmento, Bruno

    2013-01-01

    Prediction of human intestinal absorption is a major goal in the design, optimization, and selection of drugs intended for oral delivery, in particular proteins, which possess intrinsic poor transport across intestinal epithelium. There are various techniques currently employed to evaluate the extension of protein absorption in the different phases of drug discovery and development. Screening protocols to evaluate protein absorption include a range of preclinical methodologies like in silico, in vitro, in situ, ex vivo and in vivo. It is the careful and critical use of these techniques that can help to identify drug candidates, which most probably will be well absorbed from the human intestinal tract. It is well recognized that the human intestinal permeability cannot be accurately predicted based on a single preclinical method. However, the present social and scientific concerns about the animal well care as well as the pharmaceutical industries need for rapid, cheap and reliable models predicting bioavailability give reasons for using methods providing an appropriate correlation between results of in vivo and in vitro drug absorption. The aim of this review is to describe and compare in silico, in vitro, in situ, ex vivo and in vivo methods used to predict human intestinal absorption, giving a special attention to the intestinal absorption of therapeutic peptides and proteins.

  6. Vasoactive intestinal peptide (VIP) receptors in the canine gastrointestinal tract

    SciTech Connect

    Zimmerman, R.P.; Gates, T.S.; Mantyh, C.R.; Vigna, S.R.; Boehmer, C.G.; Mantyh, P.W.

    1988-11-01

    Vasoactive intestinal peptide (VIP) is a putative neurotransmitter in both the brain and peripheral tissues. To define possible target tissues of VIP we have used quantitative receptor autoradiography to localize and quantify the distribution of /sup 125/I-VIP receptor binding sites in the canine gastrointestinal tract. While the distribution of VIP binding sites was different for each segment examined, specific VIP binding sites were localized to the mucosa, the muscularis mucosa, the smooth muscle of submucosal arterioles, lymph nodules, and the circular and longitudinal smooth muscle of the muscularis externa. These results identify putative target tissues of VIP action in the canine gastrointestinal tract. In correlation with physiological data, VIP sites appear to be involved in the regulation of a variety of gastrointestinal functions including epithelial ion transport, gastric secretion, hemodynamic regulation, immune response, esophageal, gastric and intestinal motility.

  7. Structural Design of Oligopeptides for Intestinal Transport Model.

    PubMed

    Hong, Seong-Min; Tanaka, Mitsuru; Koyanagi, Riho; Shen, Weilin; Matsui, Toshiro

    2016-03-16

    Glycyl-sarcosine (Gly-Sar) is a well-known model substrate for the intestinal uptake of dipeptides through peptide transporter 1 (PepT1). However, there are no other model peptides larger than tripeptides to evaluate their intestinal transport ability. In this study, we designed new oligopeptides based on the Gly-Sar structure in terms of protease resistance. Gly-Sar-Sar was found to be an appropriate transport model for tripeptides because it does not degrade during the transport across the rat intestinal membrane, while Gly-Gly-Sar was degraded to Gly-Sar during the 60 min transport. Caco-2 cell transport experiments revealed that the designed oligopeptides based on Gly-Sar-Sar showed a significantly (p < 0.05) lower transport ability by factors of 1/10-, 1/25-, and 1/40-fold for Gly-Sar-Sar, Gly-Sar-Sar-Sar, and Gly-Sar-Sar-Sar-Sar, respectively, compared to Gly-Sar (apparent permeability coefficient: 38.6 ± 11.4 cm/s). Cell experiments also showed that the designed tripeptide and Gly-Sar were transported across Caco-2 cell via PepT1, whereas the tetra- and pentapeptides were transported through the paracellular tight-junction pathway.

  8. Assaying peptide translocation by the peptide transporter TAP.

    PubMed

    Jongsma, Marlieke L M; Neefjes, Jacques

    2013-01-01

    MHC class I molecules display peptides at the cell surface that are mostly derived from cytosolic or nuclear proteins. Since peptide loading of MHC class I molecules occurs in the ER lumen, cytosolic peptides have to pass the ER membrane. The peptide transporter TAP translocates peptides over this ER membrane which is critical for successful MHC class I antigen presentation. How peptide translocation by TAP can be assayed and inhibitors of chemical or viral origin can be identified, will be described here.

  9. Mice lacking the intestinal peptide transporter display reduced energy intake and a subtle maldigestion/malabsorption that protects them from diet-induced obesity.

    PubMed

    Kolodziejczak, Dominika; Spanier, Britta; Pais, Ramona; Kraiczy, Judith; Stelzl, Tamara; Gedrich, Kurt; Scherling, Christian; Zietek, Tamara; Daniel, Hannelore

    2013-05-15

    The intestinal transporter PEPT1 mediates the absorption of di- and tripeptides originating from breakdown of dietary proteins. Whereas mice lacking PEPT1 did not display any obvious changes in phenotype on a high-carbohydrate control diet (HCD), Pept1(-/-) mice fed a high-fat diet (HFD) showed a markedly reduced weight gain and reduced body fat stores. They were additionally protected from hyperglycemia and hyperinsulinemia. Energy balance studies revealed that Pept1(-/-) mice on HFD have a reduced caloric intake, no changes in energy expenditure, but increased energy content in feces. Cecal biomass in Pept1(-/-) mice was as well increased twofold on both diets, suggesting a limited capacity in digesting and/or absorbing the dietary constituents in the small intestine. GC-MS-based metabolite profiling of cecal contents revealed high levels and a broad spectrum of sugars in PEPT1-deficient mice on HCD, whereas animals fed HFD were characterized by high levels of free fatty acids and absence of sugars. In search of the origin of the impaired digestion/absorption, we observed that Pept1(-/-) mice lack the adaptation of the upper small intestinal mucosa to the trophic effects of the diet. Whereas wild-type mice on HFD adapt to diet with increased villus length and surface area, Pept1(-/-) mice failed to show this response. In search for the origin of this, we recorded markedly reduced systemic IL-6 levels in all Pept1(-/-) mice, suggesting that IL-6 could contribute to the lack of adaptation of the mucosal architecture to the diets.

  10. Impact of peptide transporter 1 on the intestinal absorption and pharmacokinetics of valacyclovir after oral dose escalation in wild-type and PepT1 knockout mice.

    PubMed

    Yang, Bei; Hu, Yongjun; Smith, David E

    2013-10-01

    The primary objective of this study was to determine the in vivo absorption properties of valacyclovir, including the potential for saturable proton-coupled oligopeptide transporter 1 (PepT1)-mediated intestinal uptake, after escalating oral doses of prodrug within the clinical dose range. A secondary aim was to characterize the role of PepT1 on the tissue distribution of its active metabolite, acyclovir. [³H]Valacyclovir was administered to wild-type (WT) and PepT1 knockout (KO) mice by oral gavage at doses of 10, 25, 50, and 100 nmol/g. Serial blood samples were collected over 180 minutes, and tissue distribution studies were performed 20 minutes after a 25-nmol/g oral dose of valacyclovir. We found that the C(max) and area under the curve (AUC)₀₋₁₈₀ of acyclovir were 4- to 6-fold and 2- to 3-fold lower, respectively, in KO mice for all four oral doses of valacyclovir. The time to peak concentration of acyclovir was 3- to 10-fold longer in KO compared with WT mice. There was dose proportionality in the C(max) and AUC₀₋₁₈₀ of acyclovir in WT and KO mice over the valacyclovir oral dose range of 10-100 nmol/g (i.e., linear absorption kinetics). No differences were observed in the peripheral tissue distribution of acyclovir once these tissues were adjusted for differences in perfusing drug concentrations in the systemic circulation. In contrast, some differences were observed between genotypes in the concentrations of acyclovir in the distal intestine. Collectively, the findings demonstrate a critical role of intestinal PepT1 in improving the rate and extent of oral absorption for valacyclovir. Moreover, this study provides definitive evidence for the rational development of a PepT1-targeted prodrug strategy.

  11. Digesting New Elements in Peptide Transport.

    PubMed

    Lyons, Joseph A; Nissen, Poul

    2015-10-06

    In this issue of Structure, Beale et al. (2015) define structurally and functionally a large extracellular domain unique to mammalian peptide transporters and its implications for the transport of basic di- and tri-peptides (Beale et al., 2015).

  12. Recent advances in structural biology of peptide transporters.

    PubMed

    Terada, Tomohiro; Inui, Ken-ichi

    2012-01-01

    Peptide transporters localized at brush-border membranes of intestinal and renal epithelial cells mediate the membrane transport of di- and tripeptides, and play important roles in protein absorption and the conservation of peptide-bound amino nitrogen. Peptide-like drugs that show structural similarities to di- and tripeptides are also recognized by peptide transporters. The energy for transport of small peptides and peptide-like drugs is provided by the proton gradient across the cell membrane. Since the cloning of H(+)/peptide cotransporter (PEPT1, SLC15A1), there have been advances in the molecular biology, biochemistry, biophysics and structural determination of PEPT1. By integrating these advances, much effort has been made to understand the relationship between structure and function. In silico experimental strategies are classified as (1) construction of kinetic models, (2) computer modeling of PEPT1 structure and (3) homology modeling of PEPT1 with crystal structures of bacterial transporters. The hypotheses regarding the structure-function relationship produced by these strategies have been confirmed by in vitro mutagenesis including cysteine-scanning mutagenesis. Recently, the crystal structure of PepT(So), a functionally similar prokaryotic homolog of the mammalian peptide transporters from Shewanella oneidensis, was classified, and the previous hypotheses regarding the structure-function relationship of PEPT1 have been re-evaluated. This review highlights the recent advances in our knowledge of the structural biology of PEPT1. Copyright © 2012 Elsevier Inc. All rights reserved.

  13. Development of intestinal transport function in mammals.

    PubMed

    Pácha, J

    2000-10-01

    Considerable progress has been made over the last decade in the understanding of mechanisms responsible for the ontogenetic changes of mammalian intestine. This review presents the current knowledge about the development of intestinal transport function in the context of intestinal mucosa ontogeny. The review predominantly focuses on signals that trigger and/or modulate the developmental changes of intestinal transport. After an overview of the proliferation and differentiation of intestinal mucosa, data about the bidirectional traffic (absorption and secretion) across the developing intestinal epithelium are presented. The largest part of the review is devoted to the description of developmental patterns concerning the absorption of nutrients, ions, water, vitamins, trace elements, and milk-borne biologically active substances. Furthermore, the review examines the development of intestinal secretion that has a variety of functions including maintenance of the fluidity of the intestinal content, lubrication of mucosal surface, and mucosal protection. The age-dependent shifts of absorption and secretion are the subject of integrated regulatory mechanisms, and hence, the input of hormonal, nervous, immune, and dietary signals is reviewed. Finally, the utilization of energy for transport processes in the developing intestine is highlighted, and the interactions between various sources of energy are discussed. The review ends with suggestions concerning possible directions of future research.

  14. Structural specificity of mucosal-cell transport and metabolism of peptide drugs: implication for oral peptide drug delivery

    NASA Technical Reports Server (NTRS)

    Bai, J. P.; Amidon, G. L.

    1992-01-01

    The brush border membrane of intestinal mucosal cells contains a peptide carrier system with rather broad substrate specificity and various endo- and exopeptidase activities. Small peptide (di-/tripeptide)-type drugs with or without an N-terminal alpha-amino group, including beta-lactam antibiotics and angiotensin-converting enzyme (ACE) inhibitors, are transported by the peptide transporter. Polypeptide drugs are hydrolyzed by brush border membrane proteolytic enzymes to di-/tripeptides and amino acids. Therefore, while the intestinal brush border membrane has a carrier system facilitating the absorption of di-/tripeptide drugs, it is a major barrier limiting oral availability of polypeptide drugs. In this paper, the specificity of peptide transport and metabolism in the intestinal brush border membrane is reviewed.

  15. Structural specificity of mucosal-cell transport and metabolism of peptide drugs: implication for oral peptide drug delivery

    NASA Technical Reports Server (NTRS)

    Bai, J. P.; Amidon, G. L.

    1992-01-01

    The brush border membrane of intestinal mucosal cells contains a peptide carrier system with rather broad substrate specificity and various endo- and exopeptidase activities. Small peptide (di-/tripeptide)-type drugs with or without an N-terminal alpha-amino group, including beta-lactam antibiotics and angiotensin-converting enzyme (ACE) inhibitors, are transported by the peptide transporter. Polypeptide drugs are hydrolyzed by brush border membrane proteolytic enzymes to di-/tripeptides and amino acids. Therefore, while the intestinal brush border membrane has a carrier system facilitating the absorption of di-/tripeptide drugs, it is a major barrier limiting oral availability of polypeptide drugs. In this paper, the specificity of peptide transport and metabolism in the intestinal brush border membrane is reviewed.

  16. Pharmaceutical and pharmacological importance of peptide transporters.

    PubMed

    Brandsch, Matthias; Knütter, Ilka; Bosse-Doenecke, Eva

    2008-05-01

    Peptide transport is currently a prominent topic in membrane research. The transport proteins involved are under intense investigation because of their physiological importance in protein absorption and also because peptide transporters are possible vehicles for drug delivery. Moreover, in many tissues peptide carriers transduce peptidic signals across membranes that are relevant in information processing. The focus of this review is on the pharmaceutical relevance of the human peptide transporters PEPT1 and PEPT2. In addition to their physiological substrates, both carriers transport many beta-lactam antibiotics, valaciclovir and other drugs and prodrugs because of their sterical resemblance to di- and tripeptides. The primary structure, tissue distribution and substrate specificity of PEPT1 and PEPT2 have been well characterized. However, there is a dearth of knowledge on the substrate binding sites and the three-dimensional structure of these proteins. Until this pivotal information becomes available by X-ray crystallography, the development of new drug substrates relies on classical transport studies combined with molecular modelling. In more than thirty years of research, data on the interaction of well over 700 di- and tripeptides, amino acid and peptide derivatives, drugs and prodrugs with peptide transporters have been gathered. The aim of this review is to put the reports on peptide transporter-mediated drug uptake into perspective. We also review the current knowledge on pharmacogenomics and clinical relevance of human peptide transporters. Finally, the reader's attention is drawn to other known or proposed human peptide-transporting proteins.

  17. Adaptive regulation of intestinal nutrient transporters.

    PubMed Central

    Diamond, J M; Karasov, W H

    1987-01-01

    Because most eukaryotic somatic cells are bathed in a constant internal milieu, most of their proteins are constitutive, unlike the adaptive enzymes of bacteria. However, intestinal mucosal cells, like bacteria, face a varying milieu. Hence, we tested for adaptive regulation of intestinal nutrient transporters, sought its functional significance, and compared it with regulation of bacterial proteins. All 12 transporters studied proved to be regulated by dietary substrate levels. Regulation in the intestine is slower than in bacteria and shows lower peak-to-basal activity levels. Regulatory patterns vary greatly among transporters: two sugars and two nonessential amino acids monotonically up-regulate their transporters, two vitamins and three minerals monotonically down-regulate their transporters, and two transporters of essential amino acids respond nonmonotonically to levels of their substrates. These varied patterns arise from trade-offs among four factors: transporter costs, calories yielded by metabolizable substrates, fixed daily requirements of essential nutrients, and toxicity of certain nutrients in large amounts. Based on these trade-offs, we predict the form of regulatory pattern for intestinal transporters not yet studied. PMID:3470788

  18. The mRNA expression of amino acid and sugar transporters, aminopeptidase, as well as the di- and tri-peptide transporter PepT1 in the intestines of Eimeria infected broiler chickens.

    PubMed

    Miska, K B; Fetterer, R H

    2017-02-01

    Coccidiosis in chickens is caused by infection of gut epithelial cells with protozoan parasites of the genus Eimeria This disease causes losses to the poultry industry since infected birds fail to gain weight as rapidly as non-infected birds and efficiency of feed conversion is compromised. For the present study the effect of Eimeria on expression of components of amino acid and sugar uptake mechanisms was determined. Broiler chicks were infected with Eimeria maxima, which infects the jejunum; Eimeria acervulina, which infects the duodenum; or Eimeria tenella, which infects the ceca. Sections of the jejunum, duodenum, and ceca (depending on species of Eimeria) were taken at several time points between d zero and 14 post infection (PI) for mRNA expression analysis. Genes examined included one digestive enzyme, 7 peptide and amino acid transporters located on the brush border, 8 transporters located at the basolateral surface of the gut epithelium, and 5 sugar transporters. All 3 Eimeria species examined caused decrease in expression of brush border transporters particularly at d 5 to 7 PI, which corresponds to the time when pathology is greatest. The same pattern was seen in expression of sugar transporters. However, the expression of basolateral transporters differed among species. Eimeria tenella infection resulted in decreased expression of all basolateral transporters, while E. maxima infection caused increased expression of 2 genes and slight decrease in expression of the remaining 5 genes. Infection with E. acervulina resulted in increased expression at the height of infection of all but one basolateral transporter. In conclusion, Eimeria infection causes a general decrease in gene expression of sugar transporter and brush border AATs at the height of infection. However the expression of basolateral transporters is increased in E. maxima and E. acervulina infected birds. It is possible that decreased expression of brush border transporters in combination with

  19. Peptide hydrolase activities of the mucosa of human small intestine

    PubMed Central

    Heizer, William D.; Laster, Leonard

    1969-01-01

    Few studies have been published on peptide hydrolase activities of human small intestine mucosa. We developed methods to screen tissue extracts for such enzymes and to quantitate hydrolase activities for dipeptides containing the aromatic amino acid L-phenylalanine. The screening procedure indicated glycyl-L-proline hydrolase activity was reduced in biopsy specimens from patients with flattened intestinal mucosa. To explore this further, we established optimal assay conditions for hydrolase activities (a) glycyl-L-proline, (b) L-phenylalanyl-L-proline, (c) L-alanyl-L-phenylalanine, and (d) L-phenylalanylglycine. Biopsy specimens from patients with various intestinal disorders, but without flattened mucosa, and from three patients with flattened mucosa, showed a disproportionate reduction in activities (a) and (b), with the reduction being significantly more marked in the latter patients. We suggest that intestinal imidopeptide hydrolase activities, such as (a) and (b), are sensitive to changes in intestinal disease generally, particularly to the altered physiology associated with flattening of the mucosa, and are secondary to, rather than a cause of, the intestinal pathology. Our finding that intestinal alkaline phosphatase activity tended to parallel imidopeptide hydrolase activity, and that activity (a) was partially localized to the particulate fraction of mucosal homogenate, suggested that imidopeptide hydrolase activities may be located in the microvilli of the intestinal epithelium and that, like alkaline phosphatase activity, they may be reduced in flattened mucosae, in part at least because of the pathologic changes in the microvilli. In our studies of control subjects we did not detect peptide hydrolase activity deficiency analogous to asymptomatic disaccharidase deficiency. Images PMID:5765024

  20. Food derived bioactive peptides and intestinal barrier function.

    PubMed

    Martínez-Augustin, Olga; Rivero-Gutiérrez, Belén; Mascaraque, Cristina; Sánchez de Medina, Fermín

    2014-12-09

    A wide range of food-derived bioactive peptides have been shown to exert health-promoting actions and are therefore considered functional foods or nutraceuticals. Some of these actions are related to the maintenance, reinforcement or repairment of the intestinal barrier function (IBF) whose role is to selectively allow the absorption of water, nutrients and ions while preventing the influx of microorganisms from the intestinal lumen. Alterations in the IBF have been related to many disorders, such as inflammatory bowel disease or metabolic syndrome. Components of IBF are the intestinal epithelium, the mucus layer, secretory immunoglobulin A and cells of the innate and adaptive immune systems. Here we review the effects of food derived bioactive peptides on these IBF components. In vitro and in vivo effects, both in healthy and disease states, have been reviewed. Although limited, the available information indicates a potential for food-derived peptides to modify IBF and to contribute to disease treatment, but further research is needed to better isolate responsible peptides, and to help define their mode of action.

  1. Food Derived Bioactive Peptides and Intestinal Barrier Function

    PubMed Central

    Martínez-Augustin, Olga; Rivero-Gutiérrez, Belén; Mascaraque, Cristina; Sánchez de Medina, Fermín

    2014-01-01

    A wide range of food-derived bioactive peptides have been shown to exert health-promoting actions and are therefore considered functional foods or nutraceuticals. Some of these actions are related to the maintenance, reinforcement or repairment of the intestinal barrier function (IBF) whose role is to selectively allow the absorption of water, nutrients and ions while preventing the influx of microorganisms from the intestinal lumen. Alterations in the IBF have been related to many disorders, such as inflammatory bowel disease or metabolic syndrome. Components of IBF are the intestinal epithelium, the mucus layer, secretory immunoglobulin A and cells of the innate and adaptive immune systems. Here we review the effects of food derived bioactive peptides on these IBF components. In vitro and in vivo effects, both in healthy and disease states, have been reviewed. Although limited, the available information indicates a potential for food-derived peptides to modify IBF and to contribute to disease treatment, but further research is needed to better isolate responsible peptides, and to help define their mode of action. PMID:25501338

  2. Intestinal nutrient transport during ontogeny of vertebrates.

    PubMed

    Buddington, R K

    1992-09-01

    Patterns of transporter development are known for 12 species of vertebrates (2 fish, 1 amphibian, 1 bird, and 8 mammals), ranging from early gestation to adulthood. Although transporters for some nutrients (amino acids and some sugars) appear before the onset of external feeding, species differ in when and which transporters appear. Postnatal changes in the activities of different transporters are twofold: corresponding with shifts in the composition of a species' evolutionary diet, and the need to absorb ever-increasing quantities of food for growth and metabolism. The mechanisms responsible for the age-related shifts in rates of transport include changes in the densities, distribution, and types of transporters for specific nutrients and changes in the physiochemical characteristics of the intestinal brush-border membrane. The signals that trigger the age-related changes originate from internal preprogrammed sources and external sources, with both acting in concert to mediate intestinal development. Although much more is known for the brush-border hydrolases, recent studies with the pig suggest the ontogenetic development of hydrolases and transporters are regulated independently during early development.

  3. Comparative gene expression profiles of intestinal transporters in mice, rats and humans.

    PubMed

    Kim, Hye-Ryoung; Park, Sung-Won; Cho, Hee-Jung; Chae, Kyung-Ae; Sung, Ji-Min; Kim, Jin-Suk; Landowski, Christopher P; Sun, Duxin; Abd El-Aty, A M; Amidon, Gordon L; Shin, Ho-Chul

    2007-09-01

    We have studied gene expression profiles of intestinal transporters in model animals and humans. Total RNA was isolated from duodenum and the mRNA expression was measured using Affymetrix GeneChip oligonucleotide arrays. Detected genes from the intestine of mice, rats, and humans were about 60% of 22,690 sequences, 40% of 8739, and 47% of 12,559, respectively. A total of 86 genes involving transporters expressed in mice, 50 genes in rats, and 61 genes in humans were detected. Mice exhibited abundant mRNA expressions for peptide transporter HPT1, amino acid transporters CSNU3, CT1 and ASC1, nucleoside transporter CNT2, organic cation transporter SFXN1, organic anion transporter NBC3, glucose transporter SGLT1, and fatty acid transporters FABP1 and FABP2. Rats showed high expression profiles of peptide transporter PEPT1, amino acid transporters CSNU1 and 4F2HC, nucleoside transporter CNT2, organic cation transporter OCT5, organic anion transporter SDCT1, glucose transporter GLUT2 and GLUT5, and folate carrier FOLT. In humans, the highly expressed genes were peptide transporter HPT1, amino acid transporters LAT3, 4F2HC and PROT, nucleoside transporter CNT2, organic cation transporter OCTN2, organic anion transporters NADC1, NBC1 and SBC2, glucose transporters SGLT1 and GLUT5, multidrug resistance-associated protein RHO12, fatty acid transporters FABP1 and FABP2, and phosphate carrier PHC. Overall these data reveal diverse transcriptomic profiles for intestinal transporters among these species. Therefore, this transcriptional data may lead to more effective use of the laboratory animals as a model for oral drug development.

  4. Intestinal Transport of Weak Electrolytes

    PubMed Central

    Jackson, Michael J.; Shiau, Yih-Fu; Bane, Susan; Fox, Margaret

    1974-01-01

    A study has been made of the transmural fluxes of benzoic, phenylacetic, and pentanoic acids, benzylamine, hexylamine, and D-amphetamine across rat jejunum incubated in vitro. The M to S fluxes of the weak acids were greater than their corresponding S to M fluxes, and the S to M fluxes of the weak bases were larger than their M to S fluxes. These patterns of asymmetric movements were observed when the transmural electrical potential difference was clamped at 0 mV, and when the pH values of the mucosal and serosal fluids were identical. The effects of a weak acid on the fluxes of other weak electrolytes were qualitatively similar when the effector weak acid was added to the mucosal fluid, and when it was added to the serosal fluid. But the effects of a weak base on the fluxes of other weak electrolytes were dependent upon its location, and the interactions observed when the effector weak base was added to the mucosal fluid were qualitatively different than those seen when it was added to the serosal fluid. The interactions between weak electrolytes could readily be explained in terms of the function of a system of three compartments in series, in which the pH of the intermediate compartment is greater than that of the bulk phases. But these observations could not be explained in terms of an analogous system involving an intermediate compartment of low pH, or in terms of a carrier mediated system. The transport function of the three-compartment system can be described in the form of an equation, and it is found that a pH difference of less than 0.5 unit may explain our observations on weak electrolyte transport. PMID:4812635

  5. Theaflavins, dimeric catechins, inhibit peptide transport across Caco-2 cell monolayers via down-regulation of AMP-activated protein kinase-mediated peptide transporter PEPT1.

    PubMed

    Takeda, Junko; Park, Ha-Young; Kunitake, Yuri; Yoshiura, Keiko; Matsui, Toshiro

    2013-06-15

    In the small intestine, peptide transporter 1 (PEPT1) plays a role in the transport of di- and tripeptides. In this study, we investigated whether theaflavins (TFs) affect the absorption of small peptides in human intestinal Caco-2 cells, since TFs do not penetrate through the cells and might be involved in intestinal transport systems. In transport experiments, the transport of glycyl-sarcosine (Gly-Sar, a model molecule for PEPT1 transport) and other dipeptides (Val-Tyr and Ile-Phe) were significantly reduced (P<0.05) in TFs-pretreated cells. In TF 3'-O-gallate-pretreated cells, Western blot analysis revealed attenuated expression of PEPT1 transporter and Gly-Sar transport was completely ameliorated by 10 μM Compound C, an AMP-activated protein kinase (AMPK) inhibitor. In conclusion, the present study demonstrated that TFs inhibit peptide transport across Caco-2 cell monolayers, probably through suppression of AMPK-mediated PEPT1 expression, which should be considered a new bioactivity of TFs in black tea. Copyright © 2012 Elsevier Ltd. All rights reserved.

  6. Intestinal transport and metabolism of bile acids

    PubMed Central

    Dawson, Paul A.; Karpen, Saul J.

    2015-01-01

    In addition to their classical roles as detergents to aid in the process of digestion, bile acids have been identified as important signaling molecules that function through various nuclear and G protein-coupled receptors to regulate a myriad of cellular and molecular functions across both metabolic and nonmetabolic pathways. Signaling via these pathways will vary depending on the tissue and the concentration and chemical structure of the bile acid species. Important determinants of the size and composition of the bile acid pool are their efficient enterohepatic recirculation, their host and microbial metabolism, and the homeostatic feedback mechanisms connecting hepatocytes, enterocytes, and the luminal microbiota. This review focuses on the mammalian intestine, discussing the physiology of bile acid transport, the metabolism of bile acids in the gut, and new developments in our understanding of how intestinal metabolism, particularly by the gut microbiota, affects bile acid signaling. PMID:25210150

  7. Intestinal immunomodulation. Role of regulative peptides and promising pharmacological activities.

    PubMed

    Motilva, V; Talero, E; Calvo, J R; Villegas, I; Alarcón-de-la-Lastra, C; Sánchez-Fidalgo, S

    2008-01-01

    About 50 peptides, and a similar number of peptide receptors, are known to be present in the gut and this amount is likely to rise significantly over the next few years. While there has been a massive research effort to define their functions and their anatomical distribution in the central nervous system (CNS), the understanding of their roles in the gut is far more limited. Classically, the physiological functions include the control of motility, fluids, electrolytes, and digestive enzymes secretion, or vascular and visceral pain function, and more recently, the role-played in cell proliferation and survival, and in immune-inflammatory responses. The term inflammatory bowel disease (IBD) that encompasses Crohn's disease and ulcerative colitis, is clearly an inflammatory disease where several mediators such as cytokines, chemokines, prostanoids, nitric oxide or free radicals, produced by infiltrating cells, play a critical role in intestine tissue alteration. Some peptides, initially known for their neuroregulative properties, have been suggested to act as endogenous immune factors, with predominant antiinflammatory effects. Based on these actions, these molecules are proposed as potential agents for the treatment of IBD and selective peptide analogs are being developed as novel therapeutic strategies for IBD patients. Patients with IBD have an increased risk for developing colorectal cancer (CRC). Up to the present time, no known genetic basis has been identified to explain CRC predisposition in these IBD. Instead, it is assumed that chronic inflammation is what causes cancer. This is supported by the fact that colon cancer risk increases with longer duration of colitis, greater anatomic extent of colitis, the concomitant presence of other inflammatory manifestations, and the fact that certain drugs used to treat inflammation, may prevent the development of CRC. However, though different regulative peptides play a beneficial role in experimental IBD, an

  8. Vasoactive Intestinal Peptide: A Possible Transmitter of Nonadrenergic Relaxation of Guinea Pig Airways

    NASA Astrophysics Data System (ADS)

    Matsuzaki, Yoshikazu; Hamasaki, Yuhei; Said, Sami I.

    1980-12-01

    Vasoactive intestinal peptide, a smooth-muscle relaxant neuropeptide with neurotransmitter properties, was released during electrical field stimulation of guinea pig trachea. The amount released correlated with the degree of relaxation, and the release was blocked by tetrodotoxin. Prior incubation of the trachea with antiserum to vasoactive intestinal peptide reduced the relaxation. Thus vasoactive intestinal peptide may mediate the nonadrenergic relaxation of tracheal smooth muscle.

  9. Electron Transport in Short Peptide Single Molecules

    NASA Astrophysics Data System (ADS)

    Cui, Jing; Brisendine, Joseph; Ng, Fay; Nuckolls, Colin; Koder, Ronald; Venkarataman, Latha

    We present a study of the electron transport through a series of short peptides using scanning tunneling microscope-based break junction method. Our work is motivated by the need to gain a better understanding of how various levels of protein structure contribute to the remarkable capacity of proteins to transport charge in biophysical processes such as respiration and photosynthesis. We focus here on short mono, di and tri-peptides, and probe their conductance when bound to gold electrodes in a native buffer environment. We first show that these peptides can bind to gold through amine, carboxyl, thiol and methyl-sulfide termini. We then focus on two systems (glycine and alanine) and show that their conductance decays faster than alkanes terminated by the same linkers. Importantly, our results show that the peptide bond is less conductive than a sigma carbon-carbon bond. This work was supported in part by NSF-DMR 1507440.

  10. Vasoactive intestinal peptide and electrical activity influence neuronal survival

    SciTech Connect

    Brenneman, D.E.; Eiden, L.E.

    1986-02-01

    Blockage of electrical activity in dissociated spinal cord cultures results in a significant loss of neurons during a critical period in development. Decreases in neuronal cell numbers and SVI-labeled tetanus toxin fixation produced by electrical blockage with tetrodotoxin (TTX) were prevented by addition of vasoactive intestinal peptide (VIP) to the nutrient medium. The most effective concentration of VIP was 0.1 nM. At higher concentrations, the survival-enhancing effect of VIP on TTX-treated cultures was attenuated. Addition of the peptide alone had no significant effect on neuronal cell counts or tetanus toxin fixation. With the same experimental conditions, two closely related peptides, PHI-27 (peptide, histidyl-isoleucine amide) and secretin, were found not to increase the number of neurons in TTX-treated cultures. Interference with VIP action by VIP antiserum resulted in neuronal losses that were not significantly different from those observed after TTX treatment. These data indicate that under conditions of electrical blockade a neurotrophic action of VIP on neuronal survival can be demonstrated.

  11. Intestinal transport as a potential determinant of drug bioavailability.

    PubMed

    Nauli, Andromeda M; Nauli, Surya M

    2013-08-01

    Orally administered drugs are generally absorbed by the small intestine and transported either to the lymphatic system or to the hepatic portal system. In general, lipid soluble drugs and vitamins are transported by the small intestine to the lymphatics, and water-soluble drugs are transported to the hepatic portal system. By avoiding the early hepatic first pass effect, the lymphatic transport system may increase drug bioavailability. In addition to its transport systems, the small intestine may affect drug bioavailability through drug uptake, intestinal first pass effect, recruitment of drugs by chylomicrons, formation and secretion of chylomicrons, and enterohepatic circulation. All of these factors should be considered when formulating orally administered lipophilic drugs. Our data also suggest that Caco-2 cells may serve as a valuable in vitro model to study the intestinal transport of orally administered drugs.

  12. Cloning and expression of the human vasoactive intestinal peptide receptor.

    PubMed Central

    Sreedharan, S P; Robichon, A; Peterson, K E; Goetzl, E J

    1991-01-01

    Vasoactive intestinal peptide (VIP) is a neuroendocrine mediator found in the central and peripheral nervous system. Distinct subsets of neural, respiratory, gastrointestinal, and immune cells bear specific high-affinity receptors for VIP, which are associated with a guanine nucleotide-binding (G) protein capable of activating adenylate cyclase. A cDNA clone (GPRN1) encoding the human VIP receptor was identified in libraries prepared from the Nalm 6 line of leukemic pre-B lymphoblasts and the HT-29 line of colon carcinoma cells. The deduced 362-amino acid polypeptide sequence encoded by GPRN1 shares a seven-transmembrane-segment hydropathicity profile with other G protein-coupled receptors. Northern blot analyses identified a 2.7-kilobase transcript of the VIP receptor in Nalm 6 and HT-29 cells as well as in tissues from rat brain, colon, heart, lung, kidney, spleen, and small intestine. COS-6 cells transfected with GPRN1 bound 125I-labeled VIP specifically with a dissociation constant (Kd) of 2.5 nM. VIP--and less effectively secretin, peptide histidine isoleucine (PHI), and glucagon competitively displaced bound 125I-VIP from transfected COS-6 cells, with potencies in the order VIP greater than secretin = PHI much greater than glucagon. VIP stimulated adenylate cyclase activity in stably transfected Chinese hamster ovary K1 cells, inducing a 3-fold increase in the intracellular level of cAMP. When the antisense orientation of the VIP receptor clone was introduced into HT-29 cells, there was a 50% suppression of the specific binding of 125I-VIP and of the VIP-induced increase in cAMP level, relative to untransfected cells. The VIP receptor cloned exhibits less than or equal to 24% homology with other receptors in the same superfamily and thus represents a subset of G protein-coupled receptors for peptide ligands. Images PMID:1675791

  13. Intestinal fructose transport and malabsorption in humans.

    PubMed

    Jones, Hilary F; Butler, Ross N; Brooks, Doug A

    2011-02-01

    Fructose is a hexose sugar that is being increasingly consumed in its monosaccharide form. Patients who exhibit fructose malabsorption can present with gastrointestinal symptoms that include chronic diarrhea and abdominal pain. However, with no clearly established gastrointestinal mechanism for fructose malabsorption, patient analysis by the proxy of a breath hydrogen test (BHT) is controversial. The major transporter for fructose in intestinal epithelial cells is thought to be the facilitative transporter GLUT5. Consistent with a facilitative transport system, we show here by analysis of past studies on healthy adults that there is a significant relationship between fructose malabsorption and fructose dose (r = 0.86, P < 0.001). Thus there is a dose-dependent and limited absorption capacity even in healthy individuals. Changes in fructose malabsorption with age have been observed in human infants, and this may parallel the developmental regulation of GLUT5 expression. Moreover, a GLUT5 knockout mouse has displayed the hallmarks associated with profound fructose malabsorption. Fructose malabsorption appears to be partially modulated by the amount of glucose ingested. Although solvent drag and passive diffusion have been proposed to explain the effect of glucose on fructose malabsorption, this could possibly be a result of the facilitative transporter GLUT2. GLUT5 and GLUT2 mRNA have been shown to be rapidly upregulated by the presence of fructose and GLUT2 mRNA is also upregulated by glucose, but in humans the distribution and role of GLUT2 in the brush border membrane are yet to be definitively decided. Understanding the relative roles of these transporters in humans will be crucial for establishing a mechanistic basis for fructose malabsorption in gastrointestinal patients.

  14. Characterization of autoantibodies to vasoactive intestinal peptide in asthma.

    PubMed

    Paul, S; Said, S I; Thompson, A B; Volle, D J; Agrawal, D K; Foda, H; de la Rocha, S

    1989-07-01

    Vasoactive intestinal peptide (VIP) is a potent relaxant of the airway smooth muscle. In this study, VIP-binding autoantibodies were observed in the plasma of 18% asthma patients and 16% healthy subjects. Immunoprecipitation studies and chromatography on DEAE-cellulose and immobilized protein G indicated that the plasma VIP-binding activity was largely due to IgG antibodies. Saturation analysis of VIP binding by the plasmas suggested the presence of one or two classes of autoantibodies, distinguished by their apparent equilibrium affinity constants (Ka). The autoantibodies from asthma patients exhibited a larger VIP-binding affinity compared to those from healthy subjects (Ka 7.8 x 10(9) M-1 and 0.13 x 10(9) M-1, respectively; P less than 0.005). The antibodies were specific for VIP, judged by their poor reaction with peptides bearing partial sequence homology with VIP (peptide histidine isoleucine, growth hormone releasing factor and secretin). IgG prepared from the plasma of an antibody-positive asthma patient inhibited the saturable binding of 125I-VIP by receptors in guinea pig lung membranes (by 39-59%; P less than 0.001). These observations are consistent with a role for the VIP autoantibodies in the airway hyperresponsiveness of asthma.

  15. Human intestine luminal ACE2 and amino acid transporter expression increased by ACE-inhibitors.

    PubMed

    Vuille-dit-Bille, Raphael N; Camargo, Simone M; Emmenegger, Luca; Sasse, Tom; Kummer, Eva; Jando, Julia; Hamie, Qeumars M; Meier, Chantal F; Hunziker, Schirin; Forras-Kaufmann, Zsofia; Kuyumcu, Sena; Fox, Mark; Schwizer, Werner; Fried, Michael; Lindenmeyer, Maja; Götze, Oliver; Verrey, François

    2015-04-01

    Sodium-dependent neutral amino acid transporter B(0)AT1 (SLC6A19) and imino acid (proline) transporter SIT1 (SLC6A20) are expressed at the luminal membrane of small intestine enterocytes and proximal tubule kidney cells where they exert key functions for amino acid (re)absorption as documented by their role in Hartnup disorder and iminoglycinuria, respectively. Expression of B(0)AT1 was shown in rodent intestine to depend on the presence of the carboxypeptidase angiotensin-converting enzyme 2 (ACE2). This enzyme belongs to the renin-angiotensin system and its expression is induced by treatment with ACE-inhibitors (ACEIs) or angiotensin II AT1 receptor blockers (ARBs) in many rodent tissues. We show here in the Xenopus laevis oocyte expression system that human ACE2 also functionally interacts with SIT1. To investigate in human intestine the potential effect of ACEIs or ARBs on ACE2, we analysed intestinal biopsies taken during routine gastroduodenoscopy and ileocolonoscopy from 46 patients of which 9 were under ACEI and 13 ARB treatment. Analysis of transcript expression by real-time PCR and of proteins by immunofluorescence showed a co-localization of SIT1 and B(0)AT1 with ACE2 in the brush-border membrane of human small intestine enterocytes and a distinct axial expression pattern of the tested gene products along the intestine. Patients treated with ACEIs displayed in comparison with untreated controls increased intestinal mRNA levels of ACE2, peptide transporter PEPT1 (SLC15A1) and AA transporters B(0)AT1 and PAT1 (SLC36A1). This study unravels in human intestine the localization and distribution of intestinal transporters involved in amino acid absorption and suggests that ACEIs impact on their expression.

  16. Glucagon-like peptide-2 induces rapid digestive adaptation following intestinal resection in preterm neonates

    USDA-ARS?s Scientific Manuscript database

    Short bowel syndrome (SBS) is a frequent complication after intestinal resection in infants suffering from intestinal disease. We tested whether treatment with the intestinotrophic hormone glucagon-like peptide-2 (GLP-2) increases intestinal volume and function in the period immediately following in...

  17. The role of vasoactive intestinal peptide in scavenging singlet oxygen

    SciTech Connect

    Misra, B.R.; Misra, H.P. )

    1990-02-26

    The neuropeptide vasoactive intestinal peptide (VIP), a highly basic 28 amino acid peptide, has a widespread distribution in the body. The functional specificity of this peptide not only includes its potent vasodilatory activity, but also its role in protecting lungs against acute injury, in preventing T-lymphocyte proliferation and in modulating immune function. The purpose of this study was to examine the possible antioxidant properties of VIP. The authors found that VIP up to 50 {mu}g/ml had no inhibitory effect on its reduction of cytochrome C by xanthine and xanthine oxidase, indicating that the peptide does not have significant O{sub 2} scavenging ability. However, VIP was found to inhibit, in a dose-dependent manner, the {sup 1}O{sub 2} dependent 2, 2, 6, 6 tetramethyl piperidine oxide (TEMPO) formation. {sup 1}O{sub 2} was produced by rose benzal photosensitizing system and was detected as TEMP-{sup 1}O{sub 2} adduct (TEMPO) by electron paramagnetic resonance (EPR) spectroscopic technique. The formation of TEMPO signal was strongly inhibited by {beta}-carotene, histidine as well as azide, but not by superoxide dismutase (48 {mu}g/ml), catalase (20 {mu}g/ml) and mannitol (6mM), indicating that TEMPO signal was a TEMP-{sup 1}O{sub 2} adduct. These results indicate that VIP has potent antioxidant activity and may serve as a singlet O{sub 2} scavenger, thus it may modulate the oxidative tissue injury caused by this reactive oxygen species.

  18. Expression pattern of peptide and amino acid genes in digestive tract of transporter juvenile turbot ( Scophthalmus maximus L.)

    NASA Astrophysics Data System (ADS)

    Xu, Dandan; He, Gen; Mai, Kangsen; Zhou, Huihui; Xu, Wei; Song, Fei

    2016-04-01

    Turbot ( Scophthalmus maximus L.), a carnivorous fish species with high dietary protein requirement, was chosen to examine the expression pattern of peptide and amino acid transporter genes along its digestive tract which was divided into six segments including stomach, pyloric caeca, rectum, and three equal parts of the remainder of the intestine. The results showed that the expression of two peptide and eleven amino acid transporters genes exhibited distinct patterns. Peptide transporter 1 (PepT1) was rich in proximal intestine while peptide transporter 2 (PepT2) was abundant in distal intestine. A number of neutral and cationic amino acid transporters expressed richly in whole intestine including B0-type amino acid transporter 1 (B0AT1), L-type amino acid transporter 2 (LAT2), T-type amino acid transporter 1 (TAT1), proton-coupled amino acid transporter 1 (PAT1), y+L-type amino acid transporter 1 (y+LAT1), and cationic amino acid transporter 2 (CAT2) while ASC amino acid transporter 2 (ASCT2), sodium-coupled neutral amino acid transporter 2 (SNAT2), and y+L-type amino acid transporter 2 (y+LAT2) abundantly expressed in stomach. In addition, system b0,+ transporters (rBAT and b0,+AT) existed richly in distal intestine. These findings comprehensively characterized the distribution of solute carrier family proteins, which revealed the relative importance of peptide and amino acid absorption through luminal membrane. Our findings are helpful to understand the mechanism of the utilization of dietary protein in fish with a short digestive tract.

  19. Expression and localization of VPAC1, the major receptor of vasoactive intestinal peptide along the length of the intestine.

    PubMed

    Jayawardena, Dulari; Guzman, Grace; Gill, Ravinder K; Alrefai, Waddah A; Onyuksel, Hayat; Dudeja, Pradeep K

    2017-07-01

    Vasoactive intestinal peptide (VIP) is an endogenous neuropeptide with a broad array of physiological functions in many organs including the intestine. Its actions are mediated via G protein-coupled receptors, and vasoactive intestinal peptide receptor 1 (VPAC1) is the key receptor responsible for majority of VIP's biological activity. The distribution of VPAC1 along the length of the gastrointestinal tract and its subcellular localization in intestinal epithelial cells have not been fully characterized. The current studies were undertaken to determine VPAC1 distribution and localization so that VIP-based therapies can be targeted to specific regions of the intestine. The results indicated that the mRNA levels of VPAC1 showed an abundance pattern of colon > ileum > jejunum in the mouse intestine. In parallel, the VPAC1 protein levels were higher in the mouse colon, followed by the ileum and jejunum. Immunofluorescence studies in mouse colon demonstrated that the receptor was specifically localized to the luminal surface, as was evident by colocalization with the apical marker villin but not with the basolateral marker Na(+)/K(+)-ATPase. In the human intestine, VPAC1 mRNA expression exhibited a distribution similar to that in mouse intestine and was highest in the sigmoid colon. Furthermore, in the human colon, VPAC1 also showed predominantly apical localization. The physiological relevance of the expression and apical localization of VPAC1 remains elusive. We speculate that apical VPAC1 in intestinal epithelial cells may have relevance in recognizing secreted peptides in the intestinal lumen and therefore supports the feasibility of potential therapeutic and targeting use of VIP formulations via oral route to treat gastrointestinal diseases.NEW & NOTEWORTHY These studies for the first time present comprehensive data on the relative characterization of vasoactive intestinal peptide (VIP) receptors in the intestinal mucosa. Vasoactive intestinal peptide receptor 1

  20. Electrogenic, proton-coupled, intestinal dipeptide transport in herbivorous and carnivorous teleosts.

    PubMed

    Thamotharan, M; Gomme, J; Zonno, V; Maffia, M; Storelli, C; Ahearn, G A

    1996-05-01

    In both herbivorous tilapia (Oreochromis mossambicus) and carnivorous rockfish (Sebastes caurinus) intestinal and pyloric cecal brush-border membrane vesicles (BBMV), [14C]glycylsarcosine ([14C]Gly-Sar) uptake was stimulated by a transmembrane proton gradient. A transmembrane K(+)-diffusion potential (inside negative) stimulated [14C]Gly-Sar uptake above that observed with short-circuited vesicles, whereas an inwardly directed Na+ gradient in both fishes had no effect on peptide uptake. In tilapia, [14C]Gly-Sar influx occurred by the combination of 1) a high-affinity, saturable, proton gradient-dependent carrier system [Kt [concentration that equals one-half of maximum influx (Jmax)] = 0.56 +/- 0.08 mM; Jmax = 1,945.0 +/- 174.6 pmol.mg protein-1.10 s-1]; 2) a low-affinity, nonsaturable (within 1-10 mM), proton gradient-dependent carrier system (nonsaturable carrier-mediated transport component = 4,514.0 +/- 28.1 pmol.mg protein-1.10 s-1.mM-1); and 3) a diffusional component accounting for < 10% of total influx within the concentration range tested. Influx (10 s) of 1-10 mM [14C]Gly-Sar in tilapia intestine was significantly (P < 0.01) inhibited by 10 mM diethylpyrocarbonate, a specific inhibitor of proton-coupled peptide transport systems. [14C]Gly-Sar influx into tilapia BBMV showed cis-inhibition and trans-stimulation by Gly-Pro, suggesting that [14C]Gly-Sar and Gly-Pro shared the same mucosal peptide transporter in fish. These observations strongly suggest that intestinal transport of peptides in herbivorous and carnivorous fishes is proton gradient dependent, electrogenic, sodium independent, and qualitatively resembles the peptide transport paradigm proposed for mammals.

  1. Trigeminal ganglion cells cocultured with gut express vasoactive intestinal peptide.

    PubMed

    Davis, J P; Epstein, M L

    1987-12-01

    The plasticity of neural crest cells for the expression of adrenergic and cholinergic transmitter phenotypes has been well studied. The object of this study was to determine if cells of a sensory ganglion are capable of neuropeptide transmitter plasticity. We studied whether cells of the trigeminal ganglion, which do not express the neuropeptide vasoactive intestinal peptide (VIP) in vivo, would express this peptide when grown with a tissue the gut, that contains large numbers of VIP neurons. Embryonic aneural chick rectum was explanted with the embryonic quail trigeminal ganglion on the chorioallantoic membrane of chick hosts for 7-8 days. The explants were fixed, sectioned, and stained for VIP immunoreactivity (IR), for neurofilament protein immunoreactivity, and for the quail nucleolar marker. In sections of the explants we observed two populations of quail neurons: small (10-13 microns) VIP-IR cells and large (25-32 microns) cells lacking VIP-IR and resembling native trigeminal neurons. Trigeminal ganglia explanted with embryonic heart or trigeminal ganglia explanted alone lacked small VIP-IR cells but contained large VIP-negative neurons. These results show that cells of the trigeminal ganglion grown with the gut can express a neuropeptide they do not express in the absence of the gut or in vivo. Thus the embryonic trigeminal ganglion contains cells that are plastic with respect to neuropeptide expression.

  2. The Responses of Rat Intestinal Brush Border and Cytosol Peptide Hydrolase Activities to Variation in Dietary Protein Content DIETARY REGULATION OF INTESTINAL PEPTIDE HYDROLASES

    PubMed Central

    Nicholson, J. Alex; McCarthy, Denis M.; Kim, Young S.

    1974-01-01

    The effects of variation in dietary protein content on small intestinal brush border and cytosol peptide hydrolase activities have been investigated. One group of rats was fed a high protein diet (55% casein) and another group was fed a low protein diet (10% casein). After 1 wk, brush border peptide hydrolase activity (L-leucyl-β-naphthylamide as substrate) and cytosol peptide hydrolase activity (L-prolyl-L-leucine as substrate) were determined in mucosae taken from the proximal, middle, and distal small intestine. As judged by several parameters, brush border peptide hydrolase activity was significantly greater in rats fed the high protein diet when data for corresponding segments were compared. In contrast, no significant difference was seen in cytosol peptide hydrolase activity. In a second study, brush border and cytosol peptide hydrolase activities were determined in the proximal intestine by utilizing an additional three peptide substrates: L-leucyl-L-alanine, L-phenylalanylglycine, and glycyl-L-phenylalanine. Sucrase, maltase, and alkaline phosphatase activities were also determined. As before, brush border peptide hydrolase activities were significantly greater in rats fed the high protein diet. However, activities of the nonproteolytic brush border enzymes did not vary significantly with diet. In contrast to the results obtained with L-prolyl-L-leucine as substrate for the cytosol enzymes, cytosol activity against the three additional peptide substrates was greater in rats fed the high protein diet. It is suggested that the brush border peptide hydrolase response to variation in dietary protein content represents a functional adaptation analogous to the regulation of intestinal disaccharidases by dietary carbohydrates. The implication of the differential responses of the cytosol peptide hydrolases is uncertain, since little is known of the functional role of these nonorgan-specific enzymes. PMID:4430719

  3. Actions of vasoactive intestinal peptide and secretin on chief cells prepared from guinea pig stomach

    SciTech Connect

    Sutliff, V.E.; Raufman, J.P.; Jensen, R.T.; Gardner, J.D.

    1986-07-01

    Vasoactive intestinal peptide and secretin increased cellular cAMP and pepsinogen secretion in dispersed chief cells from guinea pig gastric mucosa. With each peptide there was a close correlation between the dose-response curve for changes in cellular cAMP and that for changes in pepsinogen secretion. Vasoactive intestinal peptide- (10-28) and secretin- (5-27) had no agonist activity and antagonized the actions of vasoactive intestinal peptide and secretin on cellular cAMP and pepsinogen secretion. Studies of binding of SVI-vasoactive intestinal peptide and of SV-secretin indicated that gastric chief cells possess four classes of binding sites for vasoactive intestinal peptide and secretin and that occupation of two of these classes of binding sites correlates with the abilities of vasoactive intestinal peptide and secretin to increase cellular cAMP and pepsinogen secretion. What function, in any, is mediated by occupation by the other two classes of binding sites remains to be determined.

  4. Development and physiological regulation of intestinal lipid absorption. III. Intestinal transporters and cholesterol absorption.

    PubMed

    Hui, David Y; Labonté, Eric D; Howles, Philip N

    2008-04-01

    Intestinal cholesterol absorption is modulated by transport proteins in enterocytes. Cholesterol uptake from intestinal lumen requires several proteins on apical brush-border membranes, including Niemann-Pick C1-like 1 (NPC1L1), scavenger receptor B-I, and CD36, whereas two ATP-binding cassette half transporters, ABCG5 and ABCG8, on apical membranes work together for cholesterol efflux back to the intestinal lumen to limit cholesterol absorption. NPC1L1 is essential for cholesterol absorption, but its function as a cell surface transporter or an intracellular cholesterol transport protein needs clarification. Another ATP transporter, ABCA1, is present in the basolateral membrane to mediate HDL secretion from enterocytes.

  5. Peptide-size dependent active transport in the proteasome

    NASA Astrophysics Data System (ADS)

    Zaikin, A.; Pöschel, T.

    2005-03-01

    We investigate the transport of proteins inside the proteasome and propose an active-transport mechanism based on a spatially asymmetric interaction potential of peptide chains. The transport is driven by fluctuations which are always present in such systems. We compute the peptide-size dependent transport rate which is essential for the functioning of the proteasome. In agreement with recent experiments, varying temperature changes the transport mechanism qualitatively.

  6. Cholinergic regulation of epithelial ion transport in the mammalian intestine

    PubMed Central

    Hirota, C L; McKay, D M

    2006-01-01

    Acetylcholine (ACh) is critical in controlling epithelial ion transport and hence water movements for gut hydration. Here we review the mechanism of cholinergic control of epithelial ion transport across the mammalian intestine. The cholinergic nervous system affects basal ion flux and can evoke increased active ion transport events. Most studies rely on measuring increases in short-circuit current (ISC = active ion transport) evoked by adding ACh or cholinomimetics to intestinal tissue mounted in Ussing chambers. Despite subtle species and gut regional differences, most data indicate that, under normal circumstances, the effect of ACh on intestinal ion transport is mainly an increase in Cl- secretion due to interaction with epithelial M3 muscarinic ACh receptors (mAChRs) and, to a lesser extent, neuronal M1 mAChRs; however, AChR pharmacology has been plagued by a lack of good receptor subtype-selective compounds. Mice lacking M3 mAChRs display intact cholinergically-mediated intestinal ion transport, suggesting a possible compensatory mechanism. Inflamed tissues often display perturbations in the enteric cholinergic system and reduced intestinal ion transport responses to cholinomimetics. The mechanism(s) underlying this hyporesponsiveness are not fully defined. Inflammation-evoked loss of mAChR-mediated control of epithelial ion transport in the mouse reveals a role for neuronal nicotinic AChRs, representing a hitherto unappreciated braking system to limit ACh-evoked Cl- secretion. We suggest that: i) pharmacological analyses should be supported by the use of more selective compounds and supplemented with molecular biology techniques targeting specific ACh receptors and signalling molecules, and ii) assessment of ion transport in normal tissue must be complemented with investigations of tissues from patients or animals with intestinal disease to reveal control mechanisms that may go undetected by focusing on healthy tissue only. PMID:16981004

  7. Intestinal organoids for assessing nutrient transport, sensing and incretin secretion

    PubMed Central

    Zietek, Tamara; Rath, Eva; Haller, Dirk; Daniel, Hannelore

    2015-01-01

    Intestinal nutrient transport and sensing are of emerging interest in research on obesity and diabetes and as drug targets. Appropriate in vitro models are lacking that allow both, studies on transport processes as well as sensing and subsequent incretin hormone secretion including intracellular signaling. We here demonstrate that murine small-intestinal organoids are the first in vitro model system enabling concurrent investigations of nutrient and drug transport, sensing and incretin hormone secretion as well as fluorescent live-cell imaging of intracellular signaling processes. By generating organoid cultures from wild type mice and animals lacking different nutrient transporters, we show that organoids preserve the main phenotypic features and functional characteristics of the intestine. This turns them into the best in vitro model currently available and opens new avenues for basic as well as medical research. PMID:26582215

  8. Intestinal organoids for assessing nutrient transport, sensing and incretin secretion.

    PubMed

    Zietek, Tamara; Rath, Eva; Haller, Dirk; Daniel, Hannelore

    2015-11-19

    Intestinal nutrient transport and sensing are of emerging interest in research on obesity and diabetes and as drug targets. Appropriate in vitro models are lacking that allow both, studies on transport processes as well as sensing and subsequent incretin hormone secretion including intracellular signaling. We here demonstrate that murine small-intestinal organoids are the first in vitro model system enabling concurrent investigations of nutrient and drug transport, sensing and incretin hormone secretion as well as fluorescent live-cell imaging of intracellular signaling processes. By generating organoid cultures from wild type mice and animals lacking different nutrient transporters, we show that organoids preserve the main phenotypic features and functional characteristics of the intestine. This turns them into the best in vitro model currently available and opens new avenues for basic as well as medical research.

  9. INTESTINAL DIGESTION AND ABSORPTION OF SUGARS AND PEPTIDES.

    DTIC Science & Technology

    Mammalian intestinal sucrase is activated by sodium in different ways in different species. The sodium-activation constants have been determined...Sodium-activation does not follow any compulsory reaction sequence. No diffusion barrier can be detected between lumen and intestinal sucrase ...Trehalase also shows a cooperative interaction between substrate sites. It is not activated by sodium. The intestinal sucrase -isomaltase complex can be

  10. Stapled Vasoactive Intestinal Peptide (VIP) Derivatives Improve VPAC2 Agonism and Glucose-Dependent Insulin Secretion.

    PubMed

    Giordanetto, Fabrizio; Revell, Jefferson D; Knerr, Laurent; Hostettler, Marie; Paunovic, Amalia; Priest, Claire; Janefeldt, Annika; Gill, Adrian

    2013-12-12

    Agonists of vasoactive intestinal peptide receptor 2 (VPAC2) stimulate glucose-dependent insulin secretion, making them attractive candidates for the treatment of hyperglycaemia and type-II diabetes. Vasoactive intestinal peptide (VIP) is an endogenous peptide hormone that potently agonizes VPAC2. However, VIP has a short serum half-life and poor pharmacokinetics in vivo and is susceptible to proteolytic degradation, making its development as a therapeutic agent challenging. Here, we investigated two peptide cyclization strategies, lactamisation and olefin-metathesis stapling, and their effects on VPAC2 agonism, peptide secondary structure, protease stability, and cell membrane permeability. VIP analogues showing significantly enhanced VPAC2 agonist potency, glucose-dependent insulin secretion activity, and increased helical content were discovered; however, neither cyclization strategy appeared to effect proteolytic stability or cell permeability of the resulting peptides.

  11. Transepithelial transport of PAMAM dendrimers across isolated intestinal tissue

    NASA Astrophysics Data System (ADS)

    Hubbard, Dallin A.

    Poly(amido amine) (PAMAM) dendrimers have shown potential to carry poorly absorbed drugs across the intestinal barrier and into systemic circulation, reducing the need for intravenous injections. Much of the in vitro transepithelial transport of PAMAM dendrimers to date has been investigated using Caco-2 monolayers which lack the microvilli morphology and enzymes present in isolated intestinal tissues. In addition, a challenge in predicting oral absorption is establishing a correlation between transport across rodent and human intestinal tissues. This dissertation focused on investigating the transepithelial transport of PAMAM dendrimers across rat and human isolated intestinal tissues. Permeability values in isolated tissues were compared with those across Caco-2 cell monolayers. Results indicate a difference in transport of PAMAM dendrimers, morphological changes and transepithelial electrical resistance between Caco-2 cell monolayers, rat and human intestinal tissue models. A relatively high transport rate across the tissues, given the macromolecular nature of PAMAM dendrimers, shows promise for use of these constructs for oral delivery in human.

  12. Protein Mediators of Sterol Transport Across Intestinal Brush Border Membrane

    PubMed Central

    Brown, J. Mark; Yu, Liqing

    2012-01-01

    Dysregulation of cholesterol balance contributes significantly to atherosclerotic cardiovascular disease (ASCVD), the leading cause of death in the United States. The intestine has the unique capability to act as a gatekeeper for entry of cholesterol into the body, and inhibition of intestinal cholesterol absorption is now widely regarded as an attractive non-statin therapeutic strategy for ASCVD prevention. In this chapter we discuss the current state of knowledge regarding sterol transport across the intestinal brush border membrane. The purpose of this work is to summarize substantial progress made in the last decade in regards to protein-mediated sterol trafficking, and to discuss this in the context of human disease. PMID:20213550

  13. The Mesenteric Lymph Duct Cannulated Rat Model: Application to the Assessment of Intestinal Lymphatic Drug Transport

    PubMed Central

    Trevaskis, Natalie L.; Hu, Luojuan; Caliph, Suzanne M.; Han, Sifei; Porter, Christopher J.H.

    2015-01-01

    The intestinal lymphatic system plays key roles in fluid transport, lipid absorption and immune function. Lymph flows directly from the small intestine via a series of lymphatic vessels and nodes that converge at the superior mesenteric lymph duct. Cannulation of the mesenteric lymph duct thus enables the collection of mesenteric lymph flowing from the intestine. Mesenteric lymph consists of a cellular fraction of immune cells (99% lymphocytes), aqueous fraction (fluid, peptides and proteins such as cytokines and gut hormones) and lipoprotein fraction (lipids, lipophilic molecules and apo-proteins). The mesenteric lymph duct cannulation model can therefore be used to measure the concentration and rate of transport of a range of factors from the intestine via the lymphatic system. Changes to these factors in response to different challenges (e.g., diets, antigens, drugs) and in disease (e.g., inflammatory bowel disease, HIV, diabetes) can also be determined. An area of expanding interest is the role of lymphatic transport in the absorption of orally administered lipophilic drugs and prodrugs that associate with intestinal lipid absorption pathways. Here we describe, in detail, a mesenteric lymph duct cannulated rat model which enables evaluation of the rate and extent of lipid and drug transport via the lymphatic system for several hours following intestinal delivery. The method is easily adaptable to the measurement of other parameters in lymph. We provide detailed descriptions of the difficulties that may be encountered when establishing this complex surgical method, as well as representative data from failed and successful experiments to provide instruction on how to confirm experimental success and interpret the data obtained. PMID:25866901

  14. Expression and Function of Intestinal Hexose Transporters after Small Intestinal Denervation

    PubMed Central

    Iqbal, Corey W.; Fatima, Javairiah; Duenes, Judith; Houghton, Scott G.; Kasparek, Michael S.; Sarr, Michael G.

    2009-01-01

    Background The role of neural regulation in expression and function of intestinal hexose transporters is unknown. Aim To determine the role of intestinal innervation in gene expression and function of the membrane hexose transporters, SGLT1, GLUT2, and GLUT5 in the enterocyte. Hypothesis Denervation of the small intestine decreases expression of hexose transporters leading to decreased glucose absorption. Methods Six groups of Lewis rats were studied (n=6 each): control, 1 wk after sham laparotomy, 1 and 8 wk after syngeneic (no immune rejection) orthotopic small bowel transplantation (SBT) (SBT1, SBT8) to induce complete extrinsic denervation, and 1 and 8 wk after selective disruption of intrinsic neural continuity to jejunoileum by gut transection and reanastomosis (T/A1, T/A8). All tissue was harvested between 8AM and 10AM. In duodenum, jejunum, and ileum, mucosal mRNA levels were quantitated by real time PCR, protein by Western blotting, and transporter-mediated glucose absorption using the everted sleeve technique. Results Across the six groups, relative gene expression of hexose transporter mRNA and protein levels were unchanged and no difference in transporter-mediated glucose uptake was evident in any region. Glucose transporter affinity (Km) and functional transporter levels (Vmax) calculated for duodenum and jejunum showed no difference between the six groups. Conclusion Baseline regulation of hexose transporter function is not mediated tonically by intrinsic or extrinsic neural continuity to the jejunoileum. PMID:19541015

  15. Interaction of Food Additives with Intestinal Efflux Transporters.

    PubMed

    Sjöstedt, Noora; Deng, Feng; Rauvala, Oskari; Tepponen, Tuomas; Kidron, Heidi

    2017-10-05

    Breast cancer resistance protein (BCRP), multidrug resistance associated protein 2 (MRP2) and P-glycoprotein (P-gp) are ABC transporters that are expressed in the intestine, where they are involved in the efflux of many drugs from enterocytes back into the intestinal lumen. The inhibition of BCRP, MRP2, and P-gp can result in enhanced absorption and exposure of substrate drugs. Food additives are widely used by the food industry to improve the stability, flavor, and consistency of food products. Although they are considered safe for consumption, their interactions with intestinal transporters are poorly characterized. Therefore, in this study, selected food additives, including preservatives, colorants, and sweeteners, were studied in vitro for their inhibitory effects on intestinal ABC transporters. Among the studied compounds, several colorants were able to inhibit BCRP and MRP2, whereas P-gp was fairly insensitive to inhibition. Additionally, one sweetener was identified as a potent inhibitor of BCRP. Dose-response studies revealed that the IC50 values of the inhibitors were lower than the estimated intestinal concentrations after the consumption of beverages containing food colorants. This suggests that there is potential for previously unrecognized transporter-mediated food additive-drug interactions.

  16. Regulation of Intestinal Glucose Absorption by Ion Channels and Transporters

    PubMed Central

    Chen, Lihong; Tuo, Biguang; Dong, Hui

    2016-01-01

    The absorption of glucose is electrogenic in the small intestinal epithelium. The major route for the transport of dietary glucose from intestinal lumen into enterocytes is the Na+/glucose cotransporter (SGLT1), although glucose transporter type 2 (GLUT2) may also play a role. The membrane potential of small intestinal epithelial cells (IEC) is important to regulate the activity of SGLT1. The maintenance of membrane potential mainly depends on the activities of cation channels and transporters. While the importance of SGLT1 in glucose absorption has been systemically studied in detail, little is currently known about the regulation of SGLT1 activity by cation channels and transporters. A growing line of evidence suggests that cytosolic calcium ([Ca2+]cyt) can regulate the absorption of glucose by adjusting GLUT2 and SGLT1. Moreover, the absorption of glucose and homeostasis of Ca2+ in IEC are regulated by cation channels and transporters, such as Ca2+ channels, K+ channels, Na+/Ca2+ exchangers, and Na+/H+ exchangers. In this review, we consider the involvement of these cation channels and transporters in the regulation of glucose uptake in the small intestine. Modulation of them may be a potential strategy for the management of obesity and diabetes. PMID:26784222

  17. Acylation of Glucagon-Like Peptide-2: Interaction with Lipid Membranes and In Vitro Intestinal Permeability

    PubMed Central

    Trier, Sofie; Linderoth, Lars; Bjerregaard, Simon; Andresen, Thomas Lars; Rahbek, Ulrik Lytt

    2014-01-01

    Background Acylation of peptide drugs with fatty acid chains has proven beneficial for prolonging systemic circulation as well as increasing enzymatic stability without disrupting biological potency. Acylation has furthermore been shown to increase interactions with the lipid membranes of mammalian cells. The extent to which such interactions hinder or benefit delivery of acylated peptide drugs across cellular barriers such as the intestinal epithelia is currently unknown. The present study investigates the effect of acylating peptide drugs from a drug delivery perspective. Purpose We hypothesize that the membrane interaction is an important parameter for intestinal translocation, which may be used to optimize the acylation chain length for intestinal permeation. This work aims to characterize acylated analogues of the intestinotrophic Glucagon-like peptide-2 by systematically increasing acyl chain length, in order to elucidate its influence on membrane interaction and intestinal cell translocation in vitro. Results Peptide self-association and binding to both model lipid and cell membranes was found to increase gradually with acyl chain length, whereas translocation across Caco-2 cells depended non-linearly on chain length. Short and medium acyl chains increased translocation compared to the native peptide, but long chain acylation displayed no improvement in translocation. Co-administration of a paracellular absorption enhancer was found to increase translocation irrespective of acyl chain length, whereas a transcellular enhancer displayed increased synergy with the long chain acylation. Conclusions These results show that membrane interactions play a prominent role during intestinal translocation of an acylated peptide. Acylation benefits permeation for shorter and medium chains due to increased membrane interactions, however, for longer chains insertion in the membrane becomes dominant and hinders translocation, i.e. the peptides get ‘stuck’ in the cell

  18. Acylation of Glucagon-like peptide-2: interaction with lipid membranes and in vitro intestinal permeability.

    PubMed

    Trier, Sofie; Linderoth, Lars; Bjerregaard, Simon; Andresen, Thomas Lars; Rahbek, Ulrik Lytt

    2014-01-01

    Acylation of peptide drugs with fatty acid chains has proven beneficial for prolonging systemic circulation as well as increasing enzymatic stability without disrupting biological potency. Acylation has furthermore been shown to increase interactions with the lipid membranes of mammalian cells. The extent to which such interactions hinder or benefit delivery of acylated peptide drugs across cellular barriers such as the intestinal epithelia is currently unknown. The present study investigates the effect of acylating peptide drugs from a drug delivery perspective. We hypothesize that the membrane interaction is an important parameter for intestinal translocation, which may be used to optimize the acylation chain length for intestinal permeation. This work aims to characterize acylated analogues of the intestinotrophic Glucagon-like peptide-2 by systematically increasing acyl chain length, in order to elucidate its influence on membrane interaction and intestinal cell translocation in vitro. Peptide self-association and binding to both model lipid and cell membranes was found to increase gradually with acyl chain length, whereas translocation across Caco-2 cells depended non-linearly on chain length. Short and medium acyl chains increased translocation compared to the native peptide, but long chain acylation displayed no improvement in translocation. Co-administration of a paracellular absorption enhancer was found to increase translocation irrespective of acyl chain length, whereas a transcellular enhancer displayed increased synergy with the long chain acylation. These results show that membrane interactions play a prominent role during intestinal translocation of an acylated peptide. Acylation benefits permeation for shorter and medium chains due to increased membrane interactions, however, for longer chains insertion in the membrane becomes dominant and hinders translocation, i.e. the peptides get 'stuck' in the cell membrane. Applying a transcellular absorption

  19. Intestinal absorption of the intact peptide carnosine in man, and comparison with intestinal permeability to lactulose.

    PubMed Central

    Gardner, M L; Illingworth, K M; Kelleher, J; Wood, D

    1991-01-01

    1. Healthy humans ingested the dipeptide carnosine (L-beta-alanyl-L-histidine). Their plasma levels and urinary outputs of carnosine and beta-alanine were monitored over the following 5 h. 2. Large amounts of intact carnosine (up to 14% of the ingested dose) were recovered in the urine over the 5 h after ingestion. However, carnosine was undetectable in the plasma unless precautions were taken to inhibit blood carnosinase activity ex vivo during and after blood collection. 3. The amount of carnosine recovered in urine varied substantially between subjects. It correlated negatively with carnosinase enzymic activity in the plasma. Highest carnosinase activities were observed in those subjects who regularly underwent physical training. 4. Urinary recovery of the disaccharide lactulose also varied considerably between subjects, but was substantially lower than that of carnosine. There was no significant correlation between the recoveries of carnosine and lactulose. 5. When lactulose was ingested with a hypertonic solution, the urinary recovery of lactulose was generally increased. When carnosine was ingested with a hypertonic solution, the urinary recovery of carnosine was reduced: hence the paracellular route probably is not dominant for absorption of intact carnosine. 6. Intact carnosine must have crossed the intestine to an extent much greater than hitherto recognized. Rapid post-absorptive hydrolysis is a severe obstacle to quantification of intact peptide absorption. PMID:1910085

  20. Synthesis and secretion of glucagon-like peptide-1 by fetal rat intestinal cells in culture.

    PubMed

    Jackson Huang, T H; Brubaker, P L

    1995-07-01

    Secretion of the intestinal proglucagon-derived peptides (PGDPs) including the incretin glucagon-like peptide-1 (GLP-1) is regulated, at least in part, by the duodenal hormone glucose-dependent insulinotropic peptide (GIP) through a protein kinase (PK) A-dependent pathway. It has been demonstrated that the activation of PKA increases the synthesis of some intestinal PGDPs, particularly the glucagon-like immunoreactive (GLI) peptides glicentin and oxyntomodulin. However, the effects of GIP on GLI and GLP-1 synthesis are not known. Fetal rat intestinal cells in culture were therefore treated for up to 24 h with 5MM: dbcAMP or 10(-6) M: GIP and the changes in glicentin, oxyntomodulin, GLP-1(x-37) and GLP-1(x-36NH2) secretion and synthesis were examined by RIA and HPLC. Both dbcAMP and GIP increased the acute (2 h; to 224±21 and 256±20% of controls, respectively,P<0.001) and chronic (24 h; to 230±22 and 130±6% of controls, respectively,P<0.001) secretion of intestinal PGDPs. In contrast, the total culture content of PGDPs was increased only after 24 h of incubation (to 156±15 and 125±7% of controls for dbcAMP and GIP, respectively,P<0.01). HPLC analysis confirmed that the intestinal cultures produced the GLI peptides glicentin and oxyntomodulin, as well as the biologically active forms of GLP-1, GLP-7(7-37) and GLP-1(7-36NH2). The relative proportion of these peptides was not altered by treatment with dbcAMP or GIP. Thus, in addition to its effects on GLP-1 release from the rat intestine, GIP appears to be an important regulator of the synthesis of this insulinotropic peptide.

  1. Intestinal glucose transport and salinity adaptation in a euryhaline teleost

    SciTech Connect

    Reshkin, S.J.; Ahearn, G.A.

    1987-03-01

    Glucose transport by upper and lower intestinal brush-border membrane vesicles of the African tilapia (Oreochromis mossambicus) was characterized in fish acclimated to either freshwater of full-strength sea water. D-(/sup 3/H)-glucose uptake by vesicles was stimulated by a transmembrane Na gradient, was electrogenic, and was enhanced by countertransport of either D-glucose or D-galactose. Glucose transport was greater in the upper intestine than in the lower intestine and in sea water animals rather than in fish acclimated to freshwater. Glucose influx (10-s uptake) involved both saturable and nonsaturable transport components. Sea water adaptation increased apparent glucose influx K/sub t/, J/sub max/, apparent diffusional permeability (P), and the apparent Na affinity of the cotransport system in both intestinal segments, but the stoichiometry of Na-glucose transfer (1:1) was unaffected by differential saline conditions or gut region. It is suggested that increased sugar transport in sea water animals is due to the combination of enhanced Na-binding properties and an increase in number or transfer rate of the transport proteins. Freshwater animals compensate for reduced Na affinity of the coupled process by markedly increasing the protein affinity for glucose.

  2. Taste and move: glucose and peptide transporters in the gastrointestinal tract.

    PubMed

    Daniel, Hannelore; Zietek, Tamara

    2015-12-01

    What is the topic of this review? Nutrient absorption in the gastrointestinal tract requires membrane proteins embedded in the apical membrane of epithelial cells that allow bulk quantities of nutrients, such as monosaccharides and amino acids, to be moved into epithelial cells. Very recently, a new function of the transporters as nutrient sensors mediating peptide hormone release from enteroendocrine cells has been discovered. What advances does it highlight? The review covers recent advances in membrane transporter functions for the absorption and sensing of dietary peptides and sugars and their putative interplay. Nutrient transporters are integral membrane proteins responsible for uptake into enterocytes and release of nutrients into the circulation. Absorption of food breakdown products, such as fatty acids, monosaccharides or amino acids, requires high-capacity transporters. In the case of glucose, amino acids and peptides, the transporters are electrogenic in nature, coupling substrate flux to ion movement. While glucose absorption is mediated by the Na(+)-dependent SGLT1 protein, uptake of short-chain peptides is mediated by the H(+)-coupled PEPT1 protein. Interestingly, both transporters were recently shown to fulfil an additional role as intestinal 'sensors' in enteroendocrine cells, mediating the release of gastrointestinal peptide hormones into the circulation. Sensing of D-glucose and of di- and tripeptides is particularly relevant for the secretion of the incretins glucose-dependent insulinotrophic polypeptide and glucagon-like peptide 1 that promote insulin output from β-cells and mediate β-cell protection. In addition to these sensing pathways, a variety of G-protein-coupled receptors are involved in sensing of intestinal contents. D-Glucose is sensed not only by SGLT1 but also by the sweet taste receptor T1R2/3 expressed in enteroendocrine cells. Activation of T1R2/3 increases SGLT1 levels and intestinal glucose absorption. Although T1R2

  3. Tumor suppressor gene adenomatous polyposis coli downregulates intestinal transport.

    PubMed

    Rexhepaj, Rexhep; Rotte, Anand; Gu, Shuchen; Michael, Diana; Pasham, Venkanna; Wang, Kan; Kempe, Daniela S; Ackermann, Teresa F; Brücher, Björn; Fend, Falko; Föller, Michael; Lang, Florian

    2011-05-01

    Loss of function mutations of the tumor suppressor gene adenomatous polyposis coli (APC) underly the familial adenomatous polyposis. Mice carrying an inactivating mutation in the apc gene (apc (Min/+)) similarly develop intestinal polyposis. APC is effective at least in part by degrading β-catenin and lack of APC leads to markedly enhanced cellular β-catenin levels. β-Catenin has most recently been shown to upregulate the Na+/K+ ATPase. The present study, thus, explored the possibility that APC could influence intestinal transport. The abundance and localization of β-catenin were determined utilizing Western blotting and confocal microscopy, the activity of the electrogenic glucose carrier (SGLT1) was estimated from the glucose-induced current in jejunal segments utilizing Ussing chamber experiments and the Na+/H+ exchanger (NHE3) activity from Na+ -dependent re-alkalinization of cytosolic pH (ΔpH(i)) following an ammonium pulse employing BCECF fluorescence. As a result, β-catenin abundance in intestinal tissue was significantly higher in apc (Min/+) mice than in wild-type mice (apc (+/+)). The β-catenin protein was localized in the basolateral membrane. Both, the glucose-induced current and ΔpH(i) were significantly higher in apc (Min/+) mice than in apc (+/+) mice. In conclusion, intestinal electrogenic transport of glucose and intestinal Na+/H+ exchanger activity are both significantly enhanced in apc (Min/+) mice, pointing to a role of APC in the regulation of epithelial transport.

  4. Vasoactive intestinal peptide, a promising agent for myopia?

    PubMed Central

    Cakmak, Ayse Idil; Basmak, Hikmet; Gursoy, Huseyin; Ozkurt, Mete; Yildirim, Nilgun; Erkasap, Nilufer; Bilgec, Mustafa Deger; Tuncel, Nese; Colak, Ertugrul

    2017-01-01

    AIM To investigate the role of vasoactive intestinal peptide (VIP) in form-deprivation myopia (FDM). METHODS FDM was created in three groups of eight chicks by placing a translucent diffuser on their right eyes. Intravitreal injections of saline and VIP were applied once a day into the occluded eyes of groups 2 and 3, respectively. Retinoscopy and axial length (AL) measurements were performed on the first and 8th days of diffuser wear. The retina mRNA levels of the VIP receptors and the ZENK protein in right eyes of the three groups and left eyes of the first group on day 8 were determined using real time polymerase chain reaction (PCR). RESULTS The median final refraction (D) in right eyes were -13.75 (-16.00, -12.00), -11.50 (-12.50, -7.50), and -1.50 (-4.75, -0.75) in groups 1, 2, and 3, respectively (P<0.001). The median AL (mm) in right eyes were 10.65 (10.00, 11.10), 9.90 (9.70, 10.00), and 9.20 (9.15, 9.25) in groups 1, 2, and 3, respectively (P<0.001). The median delta-delta cycle threshold (CT) values for the VIP2 receptors were 1.07 (0.82, 1.43), 1.22 (0.98, 1.65), 0.29 (0.22, 0.45) in right eyes of groups 1, 2, and 3, and 1.18 (0.90, 1.37) in left eyes of group 1, respectively (P=0.001). The median delta-delta CT values for the ZENK protein were 1.07 (0.63, 5.03), 3.55 (2.20, 5.55), undetectable in right eyes of groups 1, 2, and 3 and 1.89 (0.21, 4.73) in left eyes of group 1, respectively (P=0.001). CONCLUSION VIP has potential inhibitory effects in the development of FDM. PMID:28251078

  5. Transmembrane transport of peptide type compounds: prospects for oral delivery

    NASA Technical Reports Server (NTRS)

    Lipka, E.; Crison, J.; Amidon, G. L.

    1996-01-01

    Synthesis and delivery of potential therapeutic peptides and peptidomimetic compounds has been the focus of intense research over the last 10 years. While it is widely recognized that numerous limitations apply to oral delivery of peptides, some of the limiting factors have been addressed and their mechanisms elucidated, which has lead to promising strategies. This article will briefly summarize the challenges, results and current approaches of oral peptide delivery and give some insight on future strategies. The barriers determining peptide bioavailability after oral administration are intestinal membrane permability, size limitations, intestinal and hepatic metabolism and in some cases solubility limitations. Poor membrane permeabilities of hydrophilic peptides might be overcome by structurally modifying the compounds, thus increasing their membrane partition characteristics and/or their affinity to carrier proteins. Another approach is the site-specific delivery of the peptide to the most permeable parts of the intestine. The current view on size limitation for oral drug delivery has neglected partition considerations. Recent studies suggest that compounds with a molecular weight up to 4000 might be significantly absorbed, assuming appropriate partition behavior and stability. Metabolism, probably the most significant factor in the absorption fate of peptides, might be controlled by coadministration of competitive enzyme inhibitors, structural modifications and administration of the compound as a well absorbed prodrug that is converted into the therapeutically active agent after its absorption. For some peptides poor solubility might present a limitation to oral absorption, an issue that has been addressed by mechanistically defining and therefore improving formulation parameters. Effective oral peptide delivery requires further development in understanding these complex mechanisms in order to maximize the therapeutic potential of this class of compounds.

  6. Effect of incubation temperature on nutrient transporters and small intestine morphology of broiler chickens.

    PubMed

    Barri, A; Honaker, C F; Sottosanti, J R; Hulet, R M; McElroy, A P

    2011-01-01

    This study evaluated the effects of elevated incubation temperature on posthatch nutrient transporter gene expression, integrity of the intestinal epithelium, organ development, and performance in Ross 308 broiler chickens. Ross × Ross 308 fertile eggs (n = 900) were incubated at different eggshell temperatures during development. From embryonic day (ED) 1 to ED12, all eggs were incubated at 37.1°C, whereas from ED13 to ED21, the eggs were divided into 2 groups for incubation at 37.4°C (S) or 39.6°C (H). Performance characteristics were measured at day of hatch (DOH) and d 7, 14, 21, 30, and 42. Small intestine and residual yolk sacs were collected at DOH and d 2, 4, 6, and 10 and weighed individually. Intestinal samples from the duodenum, jejunum, and ileum were evaluated for mucosal morphology and relative nutrient transporter gene expression. No significant differences were found in performance or organ weights. The intestinal morphology results showed a temperature × age interaction in duodenum villus height (P = 0.02) and crypt depth (P = 0.05) and in ileum villus height-to-crypt depth ratios (P = 0.02). There was a main effect of temperature, resulting in deeper crypts (P = 0.02) in the jejunum of chicks incubated at H compared with S. In the nutrient gene expression evaluation, peptide transporter (PepT1) showed a temperature × age interaction. On DOH and d 2, 4, and 10, PepT1 expression was similar between chicks incubated at S and H. However, on d 6, chicks incubated at S had significantly higher expression of PepT1 than those incubated at H. This study presents the effects of elevated incubation temperature on small intestine morphology and relative expression of nutrient transporter mRNA in high-yield broiler chicks, which can be important for the availability of nutrients and distribution of energy.

  7. Enhanced visualization of small peptides absorbed in rat small intestine by phytic-acid-aided matrix-assisted laser desorption/ionization-imaging mass spectrometry.

    PubMed

    Hong, Seong-Min; Tanaka, Mitsuru; Yoshii, Saori; Mine, Yoshinori; Matsui, Toshiro

    2013-11-05

    Enhanced visualization of small peptides absorbed through a rat intestinal membrane was achieved by matrix-assisted laser desorption/ionization time-of-flight imaging mass spectrometry (MALDI-IMS) with the aid of phytic acid as a matrix additive. Penetrants through intestinal peptide transporter 1, i.e., glycyl-sarcosine (Gly-Sar, 147.1 m/z) and antihypertensive dipeptide, Val-Tyr (281.2 m/z), were chosen for MALDI-IMS. The signal-to-noise (S/N) ratios of dipeptides Gly-Sar and Val-Tyr were seen to increase by 2.4- and 8.0-fold, respectively, when using a 2',4',6'-trihydroxyacetophenone (THAP) matrix containing 5.0 mM phytic acid, instead of the THAP matrix alone. Owing to the phytic-acid-aided MALDI-IMS method, Gly-Sar and Val-Tyr absorbed in the rat intestinal membrane were successfully visualized. The proposed imaging method also provided useful information on intestinal peptide absorption; to some extent, Val-Tyr was rapidly hydrolyzed to Tyr by peptidases located at the intestinal microvillus during the absorption process. In conclusion, the strongly acidic additive, phytic acid, is beneficial for enhancing the visualization of small peptides using MALDI-IMS, owing to the suppression of ionization-interfering salts in the tissue.

  8. Thermodynamic evidence for a dual transport mechanism in a POT peptide transporter.

    PubMed

    Parker, Joanne L; Mindell, Joseph A; Newstead, Simon

    2014-12-02

    Peptide transport plays an important role in cellular homeostasis as a key route for nitrogen acquisition in mammalian cells. PepT1 and PepT2, the mammalian proton coupled peptide transporters (POTs), function to assimilate and retain diet-derived peptides and play important roles in drug pharmacokinetics. A key characteristic of the POT family is the mechanism of peptide selectivity, with members able to recognise and transport >8000 different peptides. In this study, we present thermodynamic evidence that in the bacterial POT family transporter PepTSt, from Streptococcus thermophilus, at least two alternative transport mechanisms operate to move peptides into the cell. Whilst tri-peptides are transported with a proton:peptide stoichiometry of 3:1, di-peptides are co-transported with either 4 or 5 protons. This is the first thermodynamic study of proton:peptide stoichiometry in the POT family and reveals that secondary active transporters can evolve different coupling mechanisms to accommodate and transport chemically and physically diverse ligands across the membrane.

  9. Dietary and developmental regulation of intestinal sugar transport.

    PubMed Central

    Ferraris, R P

    2001-01-01

    The Na(+)-dependent glucose transporter SGLT1 and the facilitated fructose transporter GLUT5 absorb sugars from the intestinal lumen across the brush-border membrane into the cells. The activity of these transport systems is known to be regulated primarily by diet and development. The cloning of these transporters has led to a surge of studies on cellular mechanisms regulating intestinal sugar transport. However, the small intestine can be a difficult organ to study, because its cells are continuously differentiating along the villus, and because the function of absorptive cells depends on both their state of maturity and their location along the villus axis. In this review, I describe the typical patterns of regulation of transport activity by dietary carbohydrate, Na(+) and fibre, how these patterns are influenced by circadian rhythms, and how they vary in different species and during development. I then describe the molecular mechanisms underlying these regulatory patterns. The expression of these transporters is tightly linked to the villus architecture; hence, I also review the regulatory processes occurring along the crypt-villus axis. Regulation of glucose transport by diet may involve increased transcription of SGLT1 mainly in crypt cells. As cells migrate to the villus, the mRNA is degraded, and transporter proteins are then inserted into the membrane, leading to increases in glucose transport about a day after an increase in carbohydrate levels. In the SGLT1 model, transport activity in villus cells cannot be modulated by diet. In contrast, GLUT5 regulation by the diet seems to involve de novo synthesis of GLUT5 mRNA synthesis and protein in cells lining the villus, leading to increases in fructose transport a few hours after consumption of diets containing fructose. In the GLUT5 model, transport activity can be reprogrammed in mature enterocytes lining the villus column. Innovative experimental approaches are needed to increase our understanding of sugar

  10. Heat Stress Reduces Intestinal Barrier Integrity and Favors Intestinal Glucose Transport in Growing Pigs

    PubMed Central

    Pearce, Sarah C.; Mani, Venkatesh; Boddicker, Rebecca L.; Johnson, Jay S.; Weber, Thomas E.; Ross, Jason W.; Rhoads, Robert P.; Baumgard, Lance H.; Gabler, Nicholas K.

    2013-01-01

    Excessive heat exposure reduces intestinal integrity and post-absorptive energetics that can inhibit wellbeing and be fatal. Therefore, our objectives were to examine how acute heat stress (HS) alters intestinal integrity and metabolism in growing pigs. Animals were exposed to either thermal neutral (TN, 21°C; 35–50% humidity; n = 8) or HS conditions (35°C; 24–43% humidity; n = 8) for 24 h. Compared to TN, rectal temperatures in HS pigs increased by 1.6°C and respiration rates by 2-fold (P<0.05). As expected, HS decreased feed intake by 53% (P<0.05) and body weight (P<0.05) compared to TN pigs. Ileum heat shock protein 70 expression increased (P<0.05), while intestinal integrity was compromised in the HS pigs (ileum and colon TER decreased; P<0.05). Furthermore, HS increased serum endotoxin concentrations (P = 0.05). Intestinal permeability was accompanied by an increase in protein expression of myosin light chain kinase (P<0.05) and casein kinase II-α (P = 0.06). Protein expression of tight junction (TJ) proteins in the ileum revealed claudin 3 and occludin expression to be increased overall due to HS (P<0.05), while there were no differences in claudin 1 expression. Intestinal glucose transport and blood glucose were elevated due to HS (P<0.05). This was supported by increased ileum Na+/K+ ATPase activity in HS pigs. SGLT-1 protein expression was unaltered; however, HS increased ileal GLUT-2 protein expression (P = 0.06). Altogether, these data indicate that HS reduce intestinal integrity and increase intestinal stress and glucose transport. PMID:23936392

  11. Fermentable dietary fiber increases GLP-1 secretion and improves glucose homeostasis despite increased intestinal glucose transport capacity in healthy dogs.

    PubMed

    Massimino, S P; McBurney, M I; Field, C J; Thomson, A B; Keelan, M; Hayek, M G; Sunvold, G D

    1998-10-01

    Ileal proglucagon gene expression and postprandial plasma concentrations of proglucagon-derived peptides are reported to change with the type and quantity of dietary fiber ingested by rats. Within the intestine, proglucagon encodes several proglucagon-derived peptides known to modulate intestinal absorption capacity and pancreatic insulin secretion. To determine whether the chronic ingestion of fermentable dietary fiber regulates the expression and synthesis of proglucagon-derived peptides in the distal intestine to modulate glucose homeostasis, the following study was conducted: 16 adult dogs (23 +/- 2 kg) were fed isoenergetic, isonitrogenous diets containing a mixture of high fermentable dietary fibers (HFF) or low fermentable (LFF) wood cellulose for 14 d in a randomized cross-over design. Food was withheld for 16 h before an oral glucose tolerance test was conducted supplying 2 g of glucose/kg body wt, and peripheral blood was collected via a hind-leg catheter at 0, 15, 30, 45, 60, 90 and 120 min for plasma glucose, insulin and glucagon-like peptide-1(7-36)NH2 (GLP-1) analyses. Intestinal samples were collected after the second dietary treatment. Ileal proglucagon mRNA, intestinal (GLP-1) concentrations and the integrated area under the curves (AUC) for plasma GLP-1 and insulin were greater and plasma glucose AUC was reduced when dogs were fed the HFF diet compared to the LFF diet (P < 0.05). Intestinal villi heights, brush border and basolateral glucose transporter protein abundance and jejunal transport capacities were significantly greater when dogs were fed the HFF diet than when fed the LFF diet. In conclusion, improvements in glucose homeostasis are observed in healthy dogs when they ingest fermentable fibers.

  12. Inhibition of Intestinal Thiamin Transport in Rat Model of Sepsis

    PubMed Central

    Sassoon, Catherine S.; Zhu, Ercheng; Fang, Liwei; Subramanian, Veedamali S.; Said, Hamid M.

    2016-01-01

    Objective Thiamin deficiency is highly prevalent in patients with sepsis, but the mechanism by which sepsis induces thiamin deficiency is unknown. This study aimed to determine the influence of various severity of sepsis on carrier-mediated intestinal thiamin uptake, level of expressions of thiamin transporters (thiamin transporter-1 (THTR-1) and thiamin transporter-2 (THTR-2)), and mitochondrial thiamin pyrophosphate transporter (MTPPT). Design Randomized, controlled study Setting Research laboratory at a Veterans Affairs Medical Center Subjects Twenty-four Sprague-Dawley rats were randomized into controls, mild, moderate and severe sepsis with equal number of animals in each group. Measurements and Main Results Sepsis was induced by cecal ligation and puncture with the cecum ligated below the cecal valve at 25 %, 50 % and 75 % of cecal length, defined as severe, moderate and mild sepsis, respectively. Control animals underwent laparotomy only. After 2 days of induced sepsis, carrier-mediated intestinal thiamin uptake was measured using [3H]thiamin. Expressions of THTR-1, THTR-2, and MTPPT proteins and mRNA were measured. Proinflammatory cytokines (IL-1β and IL-6), and adenosine triphosphate (ATP) were also measured. Sepsis inhibited [3H]thiamin uptake and the inhibition was a function of sepsis severity. Both cell membranes thiamin transporters and MTPPT expression levels were suppressed; also levels of ATP in the intestine of animals with moderate and severe sepsis were significantly lower than that of sham operated controls. Conclusions For the first time we demonstrated that sepsis inhibited carrier-mediated intestinal thiamin uptake as a function of sepsis severity, suppressed thiamin transporters and MTPPT, leading to ATP depletion. PMID:27065466

  13. Effects of exogenous glucagon-like peptide-2 and distal bowel resection on intestinal and systemic adaptive responses in rats.

    PubMed

    Lai, Sarah W; de Heuvel, Elaine; Wallace, Laurie E; Hartmann, Bolette; Holst, Jens J; Brindle, Mary E; Chelikani, Prasanth K; Sigalet, David L

    2017-01-01

    To determine the effects of exogenous glucagon-like peptide-2 (GLP-2), with or without massive distal bowel resection, on adaptation of jejunal mucosa, enteric neurons, gut hormones and tissue reserves in rats. GLP-2 is a gut hormone known to be trophic for small bowel mucosa, and to mimic intestinal adaptation in short bowel syndrome (SBS). However, the effects of exogenous GLP-2 and SBS on enteric neurons are unclear. Sprague Dawley rats were randomized to four treatments: Transected Bowel (TB) (n = 8), TB + GLP-2 (2.5 nmol/kg/h, n = 8), SBS (n = 5), or SBS + GLP-2 (2.5 nmol/kg/h, n = 9). SBS groups underwent a 60% jejunoileal resection with cecectomy and jejunocolic anastomosis. All rats were maintained on parenteral nutrition for 7 d. Parameters measured included gut morphometry, qPCR for hexose transporter (SGLT-1, GLUT-2, GLUT-5) and GLP-2 receptor mRNA, whole mount immunohistochemistry for neurons (HuC/D, VIP, nNOS), plasma glucose, gut hormones, and body composition. Resection increased the proportion of nNOS immunopositive myenteric neurons, intestinal muscularis propria thickness and crypt cell proliferation, which were not recapitulated by GLP-2 therapy. Exogenous GLP-2 increased jejunal mucosal surface area without affecting enteric VIP or nNOS neuronal immunopositivity, attenuated resection-induced reductions in jejunal hexose transporter abundance (SGLT-1, GLUT-2), increased plasma amylin and decreased peptide YY concentrations. Exogenous GLP-2 attenuated resection-induced increases in blood glucose and body fat loss. Exogenous GLP-2 stimulates jejunal adaptation independent of enteric neuronal VIP or nNOS changes, and has divergent effects on plasma amylin and peptide YY concentrations. The novel ability of exogenous GLP-2 to modulate resection-induced changes in peripheral glucose and lipid reserves may be important in understanding the whole-body response following intestinal resection, and is worthy of further study.

  14. The role and pathophysiological relevance of membrane transporter PepT1 in intestinal inflammation and inflammatory bowel disease.

    PubMed

    Ingersoll, Sarah A; Ayyadurai, Saravanan; Charania, Moiz A; Laroui, Hamed; Yan, Yutao; Merlin, Didier

    2012-03-01

    Intestinal inflammation is characterized by epithelial disruption, leading to loss of barrier function and the recruitment of immune cells, including neutrophils. Although the mechanisms are not yet completely understood, interactions between environmental and immunological factors are thought to be critical in the initiation and progression of intestinal inflammation. In recent years, it has become apparent that the di/tripeptide transporter PepT1 may play an important role in the pathogenesis of such inflammation. In healthy individuals, PepT1 is primarily expressed in the small intestine and transports di/tripeptides for metabolic purposes. However, during chronic inflammation such as that associated with inflammatory bowel disease, PepT1 expression is upregulated in the colon, wherein the protein is normally expressed either minimally or not at all. Several recent studies have shown that PepT1 binds to and transports various bacterial di/tripeptides into colon cells, leading to activation of downstream proinflammatory responses via peptide interactions with innate immune receptors. In the present review, we examine the relationship between colonic PepT1-mediated peptide transport in the colon and activation of innate immune responses during disease. It is important to understand the mechanisms of PepT1 action during chronic intestinal inflammation to develop future therapies addressing inappropriate immune activation in the colon.

  15. Dual system of intestinal thiamine transport in humans

    SciTech Connect

    Hoyumpa, A.M. Jr.; Strickland, R.; Sheehan, J.J.; Yarborough, G.; Nichols, S.

    1982-05-01

    The transport of thiamine across the intestine has been characterized in rats but has not been adequately studied in humans. To determine the kinetics of thiamine intestinal transport directly in humans, mucosal tissues were obtained during routine endoscopy from normal-appearing sites at the second portion of the duodenum. With 3H-dextran as the marker of adherent volume, the uptake of 14C-thiamine hydrochloride by the excised mucosa was measured in vitro. By this method thiamine uptake was linear with tissue weight and with incubation time up to 5 min. Results showed that at low thiamine concentrations (0.2 to 2.0 microM), uptake was saturable whereas at high concentrations (5 to 50 microM), uptake was linear with thiamine concentrations. Pyrithiamine, anoxia, N-ethylmaleimide, and replacement of sodium chloride by mannitol reduced the uptake of 0.5 microM thiamine by 42%, 37%, 32% and 35%, respectively (p less than 0.05) but had no effect on the uptake of 20 microM thiamine. These data suggest that, as in the rat, the intestinal transport of thiamine in humans proceeds by a coexistent dual system. At physiologic concentrations, thiamine is transported primarily by an energy-requiring, sodium-dependent active process, whereas at higher pharmacologic concentrations thiamine uptake is predominantly a passive process.

  16. Dual system of intestinal thiamine transport in humans.

    PubMed

    Hoyumpa, A M; Strickland, R; Sheehan, J J; Yarborough, G; Nichols, S

    1982-05-01

    The transport of thiamine across the intestine has been characterized in rats but has not been adequately studied in humans. To determine the kinetics of thiamine intestinal transport directly in humans, mucosal tissues were obtained during routine endoscopy from normal-appearing sites at the second portion of the duodenum. With 3H-dextran as the marker of adherent volume, the uptake of 14C-thiamine hydrochloride by the excised mucosa was measured in vitro. By this method thiamine uptake was linear with tissue weight and with incubation time up to 5 min. Results showed that at low thiamine concentrations (0.2 to 2.0 microM), uptake was saturable whereas at high concentrations (5 to 50 microM), uptake was linear with thiamine concentrations. Pyrithiamine, anoxia, N-ethylmaleimide, and replacement of sodium chloride by mannitol reduced the uptake of 0.5 microM thiamine by 42%, 37%, 32% and 35%, respectively (p less than 0.05) but had no effect on the uptake of 20 microM thiamine. These data suggest that, as in the rat, the intestinal transport of thiamine in humans proceeds by a coexistent dual system. At physiologic concentrations, thiamine is transported primarily by an energy-requiring, sodium-dependent active process, whereas at higher pharmacologic concentrations thiamine uptake is predominantly a passive process.

  17. Intestinal Permeability and Glucagon-Like Peptide-2 in Children with Autism: A Controlled Pilot Study

    ERIC Educational Resources Information Center

    Robertson, Marli A.; Sigalet, David L.; Holst, Jens J.; Meddings, Jon B.; Wood, Julie; Sharkey, Keith A.

    2008-01-01

    We measured small intestinal permeability using a lactulose:mannitol sugar permeability test in a group of children with autism, with current or previous gastrointestinal complaints. Secondly, we examined whether children with autism had an abnormal glucagon-like peptide-2 (GLP-2) response to feeding. Results were compared with sibling controls…

  18. Intestinal Permeability and Glucagon-Like Peptide-2 in Children with Autism: A Controlled Pilot Study

    ERIC Educational Resources Information Center

    Robertson, Marli A.; Sigalet, David L.; Holst, Jens J.; Meddings, Jon B.; Wood, Julie; Sharkey, Keith A.

    2008-01-01

    We measured small intestinal permeability using a lactulose:mannitol sugar permeability test in a group of children with autism, with current or previous gastrointestinal complaints. Secondly, we examined whether children with autism had an abnormal glucagon-like peptide-2 (GLP-2) response to feeding. Results were compared with sibling controls…

  19. Salmonella infection inhibits intestinal biotin transport: cellular and molecular mechanisms.

    PubMed

    Ghosal, Abhisek; Jellbauer, Stefan; Kapadia, Rubina; Raffatellu, Manuela; Said, Hamid M

    2015-07-15

    Infection with the nontyphoidal Salmonella is a common cause of food-borne disease that leads to acute gastroenteritis/diarrhea. Severe/prolonged cases of Salmonella infection could also impact host nutritional status, but little is known about its effect on intestinal absorption of vitamins, including biotin. We examined the effect of Salmonella enterica serovar Typhimurium (S. typhimurium) infection on intestinal biotin uptake using in vivo (streptomycin-pretreated mice) and in vitro [mouse (YAMC) and human (NCM460) colonic epithelial cells, and human intestinal epithelial Caco-2 cells] models. The results showed that infecting mice with wild-type S. typhimurium, but not with its nonpathogenic isogenic invA spiB mutant, leads to a significant inhibition in jejunal/colonic biotin uptake and in level of expression of the biotin transporter, sodium-dependent multivitamin transporter. In contrast, infecting YAMC, NCM460, and Caco-2 cells with S. typhimurium did not affect biotin uptake. These findings suggest that the effect of S. typhimurium infection is indirect and is likely mediated by proinflammatory cytokines, the levels of which were markedly induced in the intestine of S. typhimurium-infected mice. Consistent with this hypothesis, exposure of NCM460 cells to the proinflammatory cytokines TNF-α and IFN-γ led to a significant inhibition of biotin uptake, sodium-dependent multivitamin transporter expression, and activity of the SLC5A6 promoter. The latter effects appear to be mediated, at least in part, via the NF-κB signaling pathway. These results demonstrate that S. typhimurium infection inhibits intestinal biotin uptake, and that the inhibition is mediated via the action of proinflammatory cytokines.

  20. Salmonella infection inhibits intestinal biotin transport: cellular and molecular mechanisms

    PubMed Central

    Ghosal, Abhisek; Jellbauer, Stefan; Kapadia, Rubina; Raffatellu, Manuela

    2015-01-01

    Infection with the nontyphoidal Salmonella is a common cause of food-borne disease that leads to acute gastroenteritis/diarrhea. Severe/prolonged cases of Salmonella infection could also impact host nutritional status, but little is known about its effect on intestinal absorption of vitamins, including biotin. We examined the effect of Salmonella enterica serovar Typhimurium (S. typhimurium) infection on intestinal biotin uptake using in vivo (streptomycin-pretreated mice) and in vitro [mouse (YAMC) and human (NCM460) colonic epithelial cells, and human intestinal epithelial Caco-2 cells] models. The results showed that infecting mice with wild-type S. typhimurium, but not with its nonpathogenic isogenic invA spiB mutant, leads to a significant inhibition in jejunal/colonic biotin uptake and in level of expression of the biotin transporter, sodium-dependent multivitamin transporter. In contrast, infecting YAMC, NCM460, and Caco-2 cells with S. typhimurium did not affect biotin uptake. These findings suggest that the effect of S. typhimurium infection is indirect and is likely mediated by proinflammatory cytokines, the levels of which were markedly induced in the intestine of S. typhimurium-infected mice. Consistent with this hypothesis, exposure of NCM460 cells to the proinflammatory cytokines TNF-α and IFN-γ led to a significant inhibition of biotin uptake, sodium-dependent multivitamin transporter expression, and activity of the SLC5A6 promoter. The latter effects appear to be mediated, at least in part, via the NF-κB signaling pathway. These results demonstrate that S. typhimurium infection inhibits intestinal biotin uptake, and that the inhibition is mediated via the action of proinflammatory cytokines. PMID:25999427

  1. Transport characteristics of a novel peptide transporter 1 substrate, antihypotensive drug midodrine, and its amino acid derivatives.

    PubMed

    Tsuda, Masahiro; Terada, Tomohiro; Irie, Megumi; Katsura, Toshiya; Niida, Ayumu; Tomita, Kenji; Fujii, Nobutaka; Inui, Ken-ichi

    2006-07-01

    Midodrine is an oral drug for orthostatic hypotension. This drug is almost completely absorbed after oral administration and converted into its active form, 1-(2',5'-dimethoxyphenyl)-2-aminoethanol) (DMAE), by the cleavage of a glycine residue. The intestinal H+-coupled peptide transporter 1 (PEPT1) transports various peptide-like drugs and has been used as a target molecule for improving the intestinal absorption of poorly absorbed drugs through amino acid modifications. Because midodrine meets these requirements, we examined whether midodrine can be a substrate for PEPT1. The uptake of midodrine, but not DMAE, was markedly increased in PEPT1-expressing oocytes compared with water-injected oocytes. Midodrine uptake by Caco-2 cells was saturable and was inhibited by various PEPT1 substrates. Midodrine absorption from the rat intestine was very rapid and was significantly inhibited by the high-affinity PEPT1 substrate cyclacillin, assessed by the alteration of the area under the blood concentration-time curve for 30 min and the maximal concentration. Some amino acid derivatives of DMAE were transported by PEPT1, and their transport was dependent on the amino acids modified. In contrast to neutral substrates, cationic midodrine was taken up extensively at alkaline pH, and this pH profile was reproduced by a 14-state model of PEPT1, which we recently reported. These findings indicate that PEPT1 can transport midodrine and contributes to the high bioavailability of this drug and that Gly modification of DMAE is desirable for a prodrug of DMAE.

  2. Transepithelial Transport of PAMAM Dendrimers Across Isolated Human Intestinal Tissue.

    PubMed

    Hubbard, Dallin; Enda, Michael; Bond, Tanner; Moghaddam, Seyyed Pouya Hadipour; Conarton, Josh; Scaife, Courtney; Volckmann, Eric; Ghandehari, Hamidreza

    2015-11-02

    Poly(amido amine) (PAMAM) dendrimers have shown transepithelial transport across intestinal epithelial barrier in rats and across Caco-2 cell monolayers. Caco-2 models innately lack mucous barriers, and rat isolated intestinal tissue has been shown to overestimate human permeability. This study is the first report of transport of PAMAM dendrimers across isolated human intestinal epithelium. It was observed that FITC labeled G4-NH2 and G3.5-COOH PAMAM dendrimers at 1 mM concentration do not have a statistically higher permeability compared to free FITC controls in isolated human jejunum and colonic tissues. Mannitol permeability was increased at 10 mM concentrations of G3.5-COOH and G4-NH2 dendrimers. Significant histological changes in human colonic and jejunal tissues were observed at G3.5-COOH and G4-NH2 concentrations of 10 mM implying that dose limiting toxicity may occur at similar concentrations in vivo. The permeability through human isolated intestinal tissue in this study was compared to previous rat and Caco-2 permeability data. This study implicates that PAMAM dendrimer oral drug delivery may be feasible, but it may be limited to highly potent drugs.

  3. Cell-penetrating peptides transport therapeutics into cells.

    PubMed

    Ramsey, Joshua D; Flynn, Nicholas H

    2015-10-01

    Nearly 30years ago, certain small, relatively nontoxic peptides were discovered to be capable of traversing the cell membrane. These cell-penetrating peptides, as they are now called, have been shown to not only be capable of crossing the cell membrane themselves but can also carry many different therapeutic agents into cells, including small molecules, plasmid DNA, siRNA, therapeutic proteins, viruses, imaging agents, and other various nanoparticles. Many cell-penetrating peptides have been derived from natural proteins, but several other cell-penetrating peptides have been developed that are either chimeric or completely synthetic. How cell-penetrating peptides are internalized into cells has been a topic of debate, with some peptides seemingly entering cells through an endocytic mechanism and others by directly penetrating the cell membrane. Although the entry mechanism is still not entirely understood, it seems to be dependent on the peptide type, the peptide concentration, the cargo the peptide transports, and the cell type tested. With new intracellular disease targets being discovered, cell-penetrating peptides offer an exciting approach for delivering drugs to these intracellular targets. There are hundreds of cell-penetrating peptides being studied for drug delivery, and ongoing studies are demonstrating their success both in vitro and in vivo.

  4. Carrier-mediated intestinal absorption of valacyclovir, the L-valyl ester prodrug of acyclovir: 1. Interactions with peptides, organic anions and organic cations in rats.

    PubMed

    Sinko, P J; Balimane, P V

    1998-05-01

    The mechanism of intestinal transport of valacyclovir (VACV), the L-valyl ester prodrug of acyclovir, was investigated in rats using an in situ intestinal perfusion technique. VACV demonstrates an oral bioavailability that is three to five time greater than acyclovir, concentration dependent, and saturable in humans. Homogenate and perfused buffer stability results demonstrated that VACV was increasingly unstable with increasing pH. VACV was converted to ACV in a concentration dependent manner during a single pass through the intestinal segment. Perfusions were performed at 37 degrees C, pH 6.5, and under iso-osmotic conditions (290 +/- 10 mOsm L-1). Intestinal outlet concentrations were corrected for VACV that was converted to ACV during the perfusion. The effective dimensionless intestinal permeability (P*e) of VACV was concentration dependent, saturable (intrinsic Km = 1.2 +/- 0.7 mM), and significantly reduced (p < 0.05) in the presence of peptide analogues (amoxicillin, ampicillin, cefadroxil, and cephradine), by the organic anion, p-amino hippuric acid and by the organic cation quinine. VACV transport was not inhibited by classical nucleoside competitive substrates or inhibitors or by valine. These results suggest that H(+)-oligopeptide, H(+)-organic cation, and organic anion transporters are involved in the small intestinal uptake of VACV. The permeability of VACV in the colon was very low, indicating that VACV is predominantly absorbed from the small intestine. VACV P*e was not altered in the presence of glucose-induced convective fluid flow, suggesting that carrier-mediated, transcellular uptake is the predominant absorption pathway of VACV in rat small intestine. Based on these results, the oral bioavailability of VACV appears to be significantly influenced by the preabsorptive conversion of VACV to the poorly absorbed ACV, by the involvement of multiple transporters in VACV small-intestinal uptake, and by the low permeability of VACV in the colon.

  5. Intestinal Digestion and Absorption of Sugars and Peptides.

    DTIC Science & Technology

    The sucrase -isomaltase complex, as prepared from the small intestine by papain solubilisation and Sephadex chromatography, has a ml. wt. of...approximately 190 000 and is composed of 6 subunits. Its amino acid composition, its content in SH and SS groups have been determined. The sucrase -isomaltase

  6. Peptide-based optical contrast agents for targeting of intestinal malignancies

    NASA Astrophysics Data System (ADS)

    Röckendorf, Niels; Helfmann, Jürgen; Fujimoto, Naho; Wehry, Katrin; Bürger, Mario; Frey, Andreas

    2007-07-01

    Intestinal tumors exhibit cell surface properties that differ from neighboring healthy epithelia and thus allow tumor cell-specific molecular targeting. Ganglioside G M1 is such a discriminatory target. Although expressed in the apical membrane of all intestinal epithelial cells it is accessible for particle conjugated ligands on tumor cells only. In order to exploit this phenomenon we want to develop a nanoparticulate optical contrast agent equipped with a peptidic G M1 binding ligand. For identification of ligand peptides a novel screening platform was devised where potential ganglioside GM1-binding peptides are generated on glass capillary plates using microfluidic non-contact arraying techniques and screened in situ for binding of fluorophor-labeled G M1. These three-dimensional supports are easy to handle and show better sensitivity than either flat glass or membrane supports because of their large inner surface and low interference with readout systems. A custom fluorescence reader was designed to comply with the specific optical behaviour of peptide arrays synthesized on microcapillary plates. This reader uses a small numerical aperture for excitation and a large numerical aperture for detection in epifluorescence-mode. Background noise from fluorescence and Raman scattering is reduced by time gated photon counting. Peptides showing affinity to ganglioside G M1 will be conjugated to a nano-particulate carrier bearing a fluorescent dye. The resulting optical contrast agent shall be used for fluorescence endoscopic intestinal tumor screening.

  7. Genetic evidence for role of DPP IV in intestinal hydrolysis and assimilation of prolyl peptides.

    PubMed

    Tiruppathi, C; Miyamoto, Y; Ganapathy, V; Leibach, F H

    1993-07-01

    The functional role of dipeptidyl peptidase IV (DPP IV) in the intestinal hydrolysis and assimilation of prolyl peptides was investigated using Japan F344 rats, which genetically lack this enzyme. USA F344 rats possess normal activity of this enzyme and served as matched controls. Intestinal brush-border membranes from the control rats were able to hydrolyze several proline-containing peptides. The hydrolytic ability of the brush-border membranes from the Japan rats against these peptides was markedly low. The difference in the hydrolytic activities between the two groups of rats was solely due to the absence of DPP IV in the Japan rats. There was no difference in the growth rate between the two groups of rats fed a reference diet whose protein constituents were not rich in proline. When the protein source was changed to gliadin, a proline-rich protein, USA F344 rats maintained their body weight for a 4-wk period on this diet, whereas the Japan rats experienced a significant weight loss under similar conditions. In situ perfusion experiments in intact animals revealed that the ability of morphiceptin (a peptide primarily hydrolyzable by DPP IV), when administered into the intestinal lumen, to block the cholera toxin-induced water secretion was significantly greater in Japan F344 rats than in USA F344 rats, indicating the resistance of morphiceptin to hydrolytic breakdown in the intestinal lumen of the Japan rats. It is concluded that the intestinal DPP IV plays a significant role in the hydrolysis of prolyl peptides and assimilation of proline-rich proteins.

  8. Intestinal calcium transport: An ion microscopic imaging study

    SciTech Connect

    Fullmer, C.S.; Chandra, S.; Smith, C.A.; Morrison, G.H.; Wasserman, R.H. )

    1990-02-26

    Ion microscopy is a direct imaging mass spectrometry technique which reveals elemental (mass) distribution in relation to tissue morphology. The influence of vitamin D on intestinal Ca transport was examined in parallel experiments by injecting either {sup 47}Ca or {sup 44}Ca into the duodenal lumen of vitamin D-deficient ({minus}D) and vitamin D-replete (+D) chicks for varying periods of time. {sup 47}Ca data provided a quantitative index of tissue retention and absorption, whereas {sup 44}Ca imaging allowed visual localization of Ca specifically in transit from the lumen versus ambient tissue {sup 40}Ca which was also imaged. Luminally-administered Ca rapidly (2.5 minutes) entered the intestinal cells in both the {minus}D and +D chicks, localizing primarily in the area subjacent to the limiting membrane. For the +D chicks, the concentration of {sup 44}Ca in this region dissipated with time, leading to a more homogeneous intracellular distribution as transport proceeded. In contrast, {sup 44}Ca continued to accumulate in the apical cell region in the {minus}D chicks for up to 20 minutes, although a slight inwardly-directed gradient developed. These approaches provide unique information concerning the sequential localization of Ca during intestinal transport and the dynamics of the action of vitamin D thereon.

  9. INTESTINAL DIGESTION AND ABSORPTION OF SUGARS AND PEPTIDES.

    DTIC Science & Technology

    The allosteric properties of sucrase were investigated. There is an evident homologous interaction between Na-sites and between substrate-sites... Sucrase , which has no mutarotase activity, liberates glucose in its alpha form. The beta forms of glucose and of some of its derivatives are absorbed...preferentially. Human and rabbit intestinal sucrases were isolated. Antibodies against them were prepared. A new procedure for the measurement of

  10. Protein transport across the small intestine in food allergy.

    PubMed

    Reitsma, Marit; Westerhout, Joost; Wichers, Harry J; Wortelboer, Heleen M; Verhoeckx, Kitty C M

    2014-01-01

    In view of the imminent deficiency of protein sources for human consumption in the near future, new protein sources need to be identified. However, safety issues such as the risk of allergenicity are often a bottleneck, due to the absence of predictive, validated and accepted methods for risk assessment. The current strategy to assess the allergenic potential of proteins focuses mainly on homology, stability and cross-reactivity, although other factors such as intestinal transport might be of added value too. In this review, we present an overview of the knowledge of protein transport across the intestinal wall and the methods currently being used to measure this. A literature study reveals that protein transport in sensitised persons occurs para-cellularly with the involvement of mast cells, and trans-cellularly via enterocytes, while in non-sensitised persons micro-fold cells and enterocytes are considered most important. However, there is a lack of comparable systematic studies on transport of allergenic proteins. Knowledge of the multiple protein transport pathways and which model system can be useful to study these processes may be of added value in the risk assessment of food allergenicity.

  11. Characterization of the rabbit intestinal fructose transporter (GLUT5).

    PubMed Central

    Miyamoto, K; Tatsumi, S; Morimoto, A; Minami, H; Yamamoto, H; Sone, K; Taketani, Y; Nakabou, Y; Oka, T; Takeda, E

    1994-01-01

    Recent studies suggest that the jejunal/kidney-type facilitative glucose transporter (GLUT5) functions as a high-affinity D-fructose transporter. However, its precise role in the small intestine is not clear. In an attempt to identify the fructose transporter in the small intestine, we measured fructose uptake in Xenopus oocytes expressing jejunal mRNA from five species (rat, mouse, rabbit, hamster and guinea-pig). Only jejunal mRNA from the rabbit significantly increased fructose uptake. We also cloned a rabbit GLUT5 cDNA from a jejunal library The predicted amino acid sequence of the 487-residue rabbit GLUT5 showed 72.3 and 67.1% identity with human and rat GLUT5 respectively. Northern-blot analysis revealed GLUT5 transcripts in rabbit duodenum, jejunum and, to a lesser extent, kidney. After separation of rabbit jejunal mRNA on a sucrose density gradient, the fractions that conferred D-fructose transport activity in oocytes also hybridized with rabbit GLUT5 cDNA. Hybrid depletion of jejunal mRNA with a GLUT5 antisense oligonucleotide markedly inhibited the mRNA-induced fructose uptake in oocytes. Immunoblot analysis indicated that GLUT5 (49 kDa) is located in the brush-border membrane of rabbit intestinal epithelial cells. Xenopus oocytes injected with rabbit GLUT5 cRNA exhibited fructose uptake activity with a Km of 11 mM for D-fructose. D-Fructose transport by GLUT5 was significantly inhibited by D-glucose and D-galactose. D-Fructose uptake in brush-border membrane vesicles shows a Km similar to that of GLUT5, but was not inhibited by D-glucose or D-galactose. Finally, cytochalasin B photolabelled a 49 kDa protein in rabbit brush-border-membrane preparations that was immunoprecipitated by antibodies to GLUT5. Our results suggest that GLUT5 functions as a fructose transporter in rabbit small intestine. However, biochemical properties of fructose transport in Xenopus oocytes injected with GLUT5 cRNA differed from those in rabbit jejunal vesicles. Images Figure 2

  12. Acylation of salmon calcitonin modulates in vitro intestinal peptide flux through membrane permeability enhancement.

    PubMed

    Trier, Sofie; Linderoth, Lars; Bjerregaard, Simon; Strauss, Holger M; Rahbek, Ulrik L; Andresen, Thomas L

    2015-10-01

    Acylation of peptide drugs with fatty acid chains has proven beneficial for prolonging systemic circulation, as well as increasing enzymatic stability and interactions with lipid cell membranes. Thus, acylation offers several potential benefits for oral delivery of therapeutic peptides, and we hypothesize that tailoring the acylation may be used to optimize intestinal translocation. This work aims to characterize acylated analogues of the therapeutic peptide salmon calcitonin (sCT), which lowers blood calcium, by systematically increasing acyl chain length at two positions, in order to elucidate its influence on intestinal cell translocation and membrane interaction. We find that acylation drastically increases in vitro intestinal peptide flux and confers a transient permeability enhancing effect on the cell layer. The analogues permeabilize model lipid membranes, indicating that the effect is due to a solubilization of the cell membrane, similar to transcellular oral permeation enhancers. The effect is dependent on pH, with larger effect at lower pH, and is impacted by acylation chain length and position. Compared to the unacylated peptide backbone, N-terminal acylation with a short chain provides 6- or 9-fold increase in peptide translocation at pH 7.4 and 5.5, respectively. Prolonging the chain length appears to hamper translocation, possibly due to self-association or aggregation, although the long chain acylated analogues remain superior to the unacylated peptide. For K(18)-acylation a short chain provides a moderate improvement, whereas medium and long chain analogues are highly efficient, with a 12-fold increase in permeability compared to the unacylated peptide backbone, on par with currently employed oral permeation enhancers. For K(18)-acylation the medium chain acylation appears to be optimal, as elongating the chain causes greater binding to the cell membrane but similar permeability, and we speculate that increasing the chain length further may

  13. Protein transport and processing by human HT29-19A intestinal cells: effect of interferon γ

    PubMed Central

    Terpend, K; Boisgerault, F; Blaton, M; Desjeux, J; Heyman, M

    1998-01-01

    Background—The nature of the breakdown products produced in enterocytes during epithelial transport of intact proteins may be critical in determining the functional consequences of protein absorption. 
Aim—(a) To measure the transepithelial transport of horseradish peroxidase (HRP) and to identify the nature of HRP breakdown products released on the basal side of enterocytes and (b) to assess the role of interferon γ (IFNγ) on HRP transport and processing. 
Methods—HT29-19A intestinal cells were used to assess transepithelial transport of HRP in Ussing chambers, and the nature of breakdown products in the basal compartment was analysed by high performance liquid chromatography (HPLC). 
Results—(1) In control conditions, [3H]HRP equivalent fluxes (3135 (219) ng/h per cm2; mean (SEM)) comprised 50% amino acids, 40% peptides, and 10% intact HRP. Steric exclusion HPLC of the breakdown products indicated a wide range of molecular masses including a major peptide of about 1150 Da. Lysosomal aspartyl and thiol proteases were expressed but no HLA-DR surface expression was noted. (2) At 48 to 72 hours after IFNγ stimulation, [3H]HRP equivalent fluxes increased significantly (7392 (1433) ng/h per cm2) without modification of the relative proportions of amino acids, peptides, and intact HRP, and without modification of the distribution of breakdown products in HPLC. Lysosomal protease activities were not modified by IFNγ but HLA-DR expression was increased. 
Conclusion—Intestinal cells are able to process HRP into peptides potentially capable of stimulating the immune system. IFNγ stimulates the transport and processing of HRP thus increasing the antigenic load in the intestinal mucosa. 

 Keywords: enterocyte; transcytosis; macromolecular degradation; HPLC; mucosal immunity PMID:9616317

  14. Glucagon-like peptide-2 induces rapid digestive adaptation following intestinal resection in preterm neonates

    PubMed Central

    Vegge, Andreas; Thymann, Thomas; Lund, Pernille; Stoll, Barbara; Bering, Stine B.; Hartmann, Bolette; Jelsing, Jacob; Qvist, Niels; Burrin, Douglas G.; Jeppesen, Palle B.; Holst, Jens J.

    2013-01-01

    Short bowel syndrome (SBS) is a frequent complication after intestinal resection in infants suffering from intestinal disease. We tested whether treatment with the intestinotrophic hormone glucagon-like peptide-2 (GLP-2) increases intestinal volume and function in the period immediately following intestinal resection in preterm pigs. Preterm pigs were fed enterally for 48 h before undergoing resection of 50% of the small intestine and establishment of a jejunostomy. Following resection, pigs were maintained on total parenteral nutrition (TPN) without (SBS, n = 8) or with GLP-2 treatment (3.5 μg/kg body wt per h, SBS+GLP-2, n = 7) and compared with a group of unresected preterm pigs (control, n = 5). After 5 days of TPN, all piglets were fed enterally for 24 h, and a nutrient balance study was performed. Intestinal resection was associated with markedly reduced endogenous GLP-2 levels. GLP-2 increased the relative absorption of wet weight (46 vs. 22%), energy (79 vs. 64%), and all macronutrients (all parameters P < 0.05). These findings were supported by a 200% increase in sucrase and maltase activities, a 50% increase in small intestinal epithelial volume (P < 0.05), as well as increased DNA and protein contents and increased total protein synthesis rate in SBS+GLP-2 vs. SBS pigs (+100%, P < 0.05). Following intestinal resection in preterm pigs, GLP-2 induced structural and functional adaptation, resulting in a higher relative absorption of fluid and macronutrients. GLP-2 treatment may be a promising therapy to enhance intestinal adaptation and improve digestive function in preterm infants with jejunostomy following intestinal resection. PMID:23764891

  15. Intestinal transport of sugars and amino acids in diabetic rats

    PubMed Central

    Olsen, Ward A.; Rosenberg, Irwin H.

    1970-01-01

    The specificity and mechanism of altered intestinal transport of diabetic rats was studied with an everted ring technique. Increased intracellular accumulation of amino acids, as well as galactose and 3-O-methylglucose, was demonstrated in diabetes. The greater accumulation by diabetic intestine could not be attributed to a direct effect of the agent used to induce diabetes or to an alteration in food consumption. Although the changes were related to the severity of diabetes and could be reversed with treatment with insulin, they could not be modified by addition of insulin in vitro. The changes could not be induced in control intestine either with hyperglycemia from glucose infusion or preincubation with glucose in vitro. Although the higher concentration gradients of amino acids, galactose, and 3-O-methylglucose could result from increased energy utilization by diabetic intestine, an alteration of cell membrane function, as well, is suggested by the demonstration with kinetic studies of increased influx with an increase in Vmax. PMID:5409812

  16. Intestinal growth in parenterally-fed rats induced by the combined effects of glucagon-like peptide 2 and epidermal growth factor.

    PubMed

    Kitchen, Paul A; Goodlad, Robert A; FitzGerald, Anthony J; Mandir, Nikki; Ghatei, Mohammed A; Bloom, Stephen R; Berlanga-Acosta, Jorge; Playford, Raymond J; Forbes, Alastair; Walters, Julian R F

    2005-01-01

    Parenteral nutrition and the absence of luminal feeding result in impaired intestinal growth and differentiation of enterocytes. Glucagon-like peptide 2 (GLP-2) and epidermal growth factor (EGF) have each been shown to have trophic effects on the intestine, and thus have the potential to benefit patients fed parenterally, such as those with intestinal failure from short bowel syndrome. We report studies aimed to determine whether there may be synergistic effects of these 2 peptides. Rats were established on parenteral nutrition (PN) and infused for 6 days with GLP-2 (20 microg/d), EGF (20 microg/d), or GLP-2 + EGF (20 microg/d of each). These groups were compared with untreated PN-fed and orally-fed controls. Tissue was obtained from small intestine and colon to determine growth, proliferation, and representative gene expression. Small intestinal weight was increased by 75%, 43%, and 116% in the GLP-2, EGF, and GLP-2 + EGF groups, respectively, compared with PN controls (all p < .001). Cell proliferation increased with GLP-2, EGF, and GLP-2 + EGF in proximal small intestine by factors of 2.3, 1.7, and 3.4 respectively (p < .001). A synergistic effect on villous and crypt area was observed in the proximal small intestine when GLP-2 and EGF were combined (p < .05). GLP-2 had no effect in the colon, unlike EGF. Further studies showed GLP-2 + EGF significantly increased expression in distal small intestine of transcripts for the bile acid transport protein IBABP (p < .05) and showed a significant correlation between the expression of IBABP and the transcription factor HNF-4. Both GLP-2 and EGF upregulate growth of the small intestine, and this is augmented when GLP-2 and EGF are combined. These findings may lead to improved treatment of patients receiving PN.

  17. Thiamine transport across the rat intestine. I. Normal characteristics.

    PubMed

    Hoyumpa, A M; Middleton, H M; Wilson, F A; Schenker, S

    1975-05-01

    The characteristics of normal thiamine transport across the intestine were studied in rats using intact intestinal loops and everted jejunal segments. In vivo studies with [35-S]-thiamine hydrochloride revealed, in all segments of small intestine, saturation kinetics for low thiamine concentrations (0.06 to 1.5 muM), but a linear relationship between high concentrations (2 to 560 muM) and absorption. Moreover, in vitro studies of net transmural flux using everted jejunal sacs demonstrated movement of [14-C]-thiamine hydrochloride against a concentration gradient only when low, but not when high, thiamine concentration was used, so that the serosal to mucosal ratio became significantly greater than the initial value of one. Pyrithiamine, 2 muM, dinitrophenol, 200 muM, norethylmaleimide, 100 muM, and ouabain, 10 muM, reduced the net transmural flux of 0.2 muM thiamine. In contrast, these inhibitors had no effect on 20 muM thiamine. When unidirectional flux across the jejunum was measured, saturation kinetics was again demonstrated for low thiamine concentrations. This phenomenon, however, was abolished by the addition of pyrithiamine, which exerted competitive inhibition on thiamine absorption. Anoxia and sodium lack reduced intestinal uptake of 0.5 muM thiamine to 58% and 74% of normal, respectively, but did not affect uptake of 50 muM thiamine. Lowering the marked with low thiamine concentrations (O10, 1.648) than with high concentration (Q10, 1.127). Stirring of the water layer reduced Km to 59% of unstirred value, while Vmax and permeability coefficient remained unchanged. Finally, movement of low concentration thiamine against an electrical gradient was observed under conditions of electrical short circuiting and zero potential difference. In contrast, no such effect was seen with high concentrations. These studies suggest that there exists in the rat a dual system of intestinal thiamine transport. At low concentrations, thiamine is absorbed by an active process

  18. Intestinal-fatty acid binding protein and lipid transport in human intestinal epithelial cells

    SciTech Connect

    Montoudis, Alain; Delvin, Edgard; Menard, Daniel

    2006-01-06

    Intestinal-fatty acid binding protein (I-FABP) is a 14-15 kDa cytoplasmic molecule highly expressed in the enterocyte. Although different functions have been proposed for various FABP family members, the specific function of I-FABP in human intestine remains unclear. Here, we studied the role of I-FABP in molecularly modified normal human intestinal epithelial cells (HIEC-6). cDNA transfection resulted in 90-fold I-FABP overexpression compared to cells treated with empty pQCXIP vector. The high-resolution immunogold technique revealed labeling mainly in the cytosol and confirmed the marked phenotype abundance of I-FABP in cDNA transfected cells. I-FABP overexpression was not associated with alterations in cell proliferation and viability. Studies using these transfected cells cultured with [{sup 14}C]oleic acid did not reveal higher efficiency in de novo synthesis or secretion of triglycerides, phospholipids, and cholesteryl esters compared to cells treated with empty pQCXIP vector only. Similarly, the incubation with [{sup 35}S]methionine did not disclose a superiority in the biogenesis of apolipoproteins (apo) A-I, A-IV, B-48, and B-100. Finally, cells transfected with I-FABP did not exhibit an increased production of chylomicrons, VLDL, LDL, and HDL. Our observations establish that I-FABP overexpression in normal HIEC-6 is not related to cell proliferation, lipid esterification, apo synthesis, and lipoprotein assembly, and, therefore, exclude its role in intestinal fat transport.

  19. Expression of sweet receptor components in equine small intestine: relevance to intestinal glucose transport.

    PubMed

    Daly, Kristian; Al-Rammahi, Miran; Arora, Daleep K; Moran, Andrew W; Proudman, Christopher J; Ninomiya, Yuzo; Shirazi-Beechey, Soraya P

    2012-07-15

    The heteromeric sweet taste receptor T1R2-T1R3 is expressed on the luminal membrane of certain populations of enteroendocrine cells. Sensing of sugars and other sweet compounds by this receptor activates a pathway in enteroendocrine cells, resulting in secretion of a number of gut hormones, including glucagon-like peptide 2 (GLP-2). This subsequently leads to upregulation in the expression of intestinal Na(+)/glucose cotransporter, SGLT1, and increased intestinal glucose absorption. On the basis of the current information available on the horse genome sequence, it has been proposed that the gene for T1R2 (Tas1R2) is absent in the horse. We show here, however, that horses express both the mRNA and protein for T1R2. Equine T1R2 is most closely homologous to that in the pig and the cow. T1R2 protein, along with T1R3, α-gustducin, and GLP-2 proteins are coexpressed in equine intestinal endocrine cells. Intravenous administration of GLP-2, in rats and pigs, leads to an increase in the expression of SGLT1 in absorptive enterocytes and enhancement in blood glucose concentrations. GLP-2 receptor is expressed in enteric neurons, excluding the direct effect of GLP-2 on enterocytes. However, electric stimulation of enteric neurons generates a neural response leading to SGLT1 upregulation, suggesting that sugar in the intestine activates a reflex increase in the functional expression of SGLT1. Horses possess the ability to upregulate SGLT1 expression in response to increased dietary carbohydrates, and to enhance the capacity of the gut to absorb glucose. The gut sweet receptor provides an accessible target for manipulating the equine gut to absorb glucose (and water), allowing greater energy uptake and hydration for hard-working horses.

  20. Intestinotrophic Glucagon-Like Peptide-2 (GLP-2) Activates Intestinal Gene Expression and Growth Factor-Dependent Pathways Independent of the Vasoactive Intestinal Peptide Gene in Mice

    PubMed Central

    Yusta, Bernardo; Holland, Dianne; Waschek, James A.

    2012-01-01

    The enteroendocrine and enteric nervous systems convey signals through an overlapping network of regulatory peptides that act either as circulating hormones or as localized neurotransmitters within the gastrointestinal tract. Because recent studies invoke an important role for vasoactive intestinal peptide (VIP) as a downstream mediator of glucagon-like peptide-2 (GLP-2) action in the gut, we examined the importance of the VIP-GLP-2 interaction through analysis of Vip−/− mice. Unexpectedly, we detected abnormal villous architecture, expansion of the crypt compartment, increased crypt cell proliferation, enhanced Igf1 and Kgf gene expression, and reduced expression of Paneth cell products in the Vip−/− small bowel. These abnormalities were not reproduced by antagonizing VIP action in wild-type mice, and VIP administration did not reverse the intestinal phenotype of Vip−/− mice. Exogenous administration of GLP-2 induced the expression of ErbB ligands and immediate-early genes to similar levels in Vip+/+ vs. Vip−/− mice. Moreover, GLP-2 significantly increased crypt cell proliferation and small bowel growth to comparable levels in Vip+/+ vs. Vip−/− mice. Unexpectedly, exogenous GLP-2 administration had no therapeutic effect in mice with dextran sulfate-induced colitis; the severity of colonic injury and weight loss was modestly reduced in female but not male Vip−/− mice. Taken together, these findings extend our understanding of the complex intestinal phenotype arising from loss of the Vip gene. Furthermore, although VIP action may be important for the antiinflammatory actions of GLP-2, the Vip gene is not required for induction of a gene expression program linked to small bowel growth after enhancement of GLP-2 receptor signaling. PMID:22535770

  1. Intestinal absorption of amino acids and peptides in Hartnup disorder.

    PubMed

    Leonard, J V; Marrs, T C; Addison, J M; Burston, D; Clegg, K M; Lloyd, J K; Matthews, D M; Seakins, J W

    1976-04-01

    Absorption of free and peptide-bound amino acids was investigated in a girl with Hartnup disorder aged 26 months. Plasma levels of amino acids were followed after oral administration of (1) an amino acid mixture simulating casein and (2) an equivalent dose of a partial enzymic hydrolysate of casein containing oligopeptides in addition to free amino acids. The results suggested that many neutral amino acids were poorly absorbed when given in the free form, but much more readily absorbed when given as peptides. Unexpectedly, the results also suggested that glutamic acid was poorly absorbed when given in the free form. The results obtained with threonine could not be interpreted. There was an increased renal clearance of many neutral amino acids, including glycine, but clearance of proline was not increased. Most amino acids with an increased renal clearance also appeared to be poorly absorbed when given by mouth in the free form.

  2. Digestion of gliadin peptides by intestinal mucosa from control or coeliac children.

    PubMed

    Carchon, H; Serrus, M; Eggermont, E

    1979-01-01

    Gliadin, subsequently treated with pepsin, trypsin and pancreatic extract was further digested by small-intestinal mucosal homogenates from 10 control or 8 coeliac children. The amino acids liberated in the incubation mixture were measured and corrected for mucosal damage. In accordance with the data from the literature on adults, the total amount of amino acids released from gliadin peptides by the intestinal mucosa from children with active coeliac disease is significantly lower than that by the mucosa from control subjects. Qualitatively, however, no significant differences for the individual amino acids are observed with the exception of glutamine and proline, so that damaged coeliac mucosa liberates relatively more glutamine but less proline.

  3. Calcium glycerophosphate preserves transepithelial integrity in the Caco-2 model of intestinal transport

    PubMed Central

    Datta, Palika; Weis, Margaret T

    2015-01-01

    AIM: To assess the direct effects of ischemia on intestinal epithelial integrity. Furthermore, clinical efforts at mitigating the effect of hypoperfusion on gut permeability have focused on restoring gut vascular function. METHODS: We report that, in the Caco-2 cell model of transepithelial transport, calcium glycerophosphate (CGP), an inhibitor of intestinal alkaline phosphatase F3, has a significant effect to preserve transepithelial electrical resistance (TEER) and to attenuate increases in mannitol flux rates during hypoxia or cytokine stimulation. RESULTS: The effect was observable even at concentrations as low as 1 μmol/L. As celiac disease is also marked by a loss of gut epithelial integrity, the effect of CGP to attenuate the effect of the α-gliadin peptide 31-55 was also examined. In this instance, CGP exerted little effect of preservation of TEER, but significantly attenuated peptide induced increase in mannitol flux. CONCLUSION: It appears that CGP treatment might synergize with other therapies to preserve gut epithelial integrity. PMID:26290632

  4. The effect of ferrous-chelating hairtail peptides on iron deficiency and intestinal flora in rats.

    PubMed

    Lin, Hui-Min; Deng, Shang-Gui; Huang, Sai-Bo; Li, Ying-Jie; Song, Ru

    2016-06-01

    Chelating agents, such as small peptides, can decrease free iron content and increase iron bioavailability. They may have promising therapeutic potential and may prevent the pro-oxidant effects of low molecular weight iron. Hairtail is a species of fish that is rich in easily digestible proteins. We extended this strategy for iron delivery by using an enzymatic hydrolysate of hairtail as the chelating agent and found that the ferrous-chelating hairtail peptides have anti-anaemic activity in Sprague-Dawley rats with anaemia. The anti-anaemic activity of ferrous-chelating hairtail peptides prepared by enzymatic hydrolysis of the hairtail and ferrous chelation was studied in rat models of iron deficiency anaemia. After the end of the 35 d experiment, we noted significant differences in haemoglobin, mean corpuscular volume, haemoglobin distribution width, and ferritin concentrations between those animals supplemented with ferrous-chelating hairtail peptides and FeSO4 and healthy animals. There were no negative side effects on the animals' growth or behaviour. There was no obvious inflammation in the intestinal mucosa lamina propria and no unbalance of intestinal flora. The novel ferrous-chelating hairtail peptides may be a suitable fortificant for improving iron-deficiency status. Our findings demonstrated that this multi-tracer technique has many applications in nutritional research. © 2015 Society of Chemical Industry. © 2015 Society of Chemical Industry.

  5. Acute interactions between intestinal sugar and calcium transport in vitro.

    PubMed

    Tharabenjasin, Phuntila; Douard, Veronique; Patel, Chirag; Krishnamra, Nateetip; Johnson, Richard J; Zuo, Jian; Ferraris, Ronaldo P

    2014-01-01

    Fructose consumption by Americans has increased markedly, whereas Ca(2+) intake has decreased below recommended levels. Because fructose metabolism decreases enterocyte ATP concentrations, we tested the hypothesis that luminal fructose acutely reduces active, diet-inducible Ca(2+) transport in the small intestine. We confirmed that the decrease in ATP concentrations was indeed greater in fructose- compared with glucose-incubated mucosal homogenates from wild-type and was prevented in fructose-incubated homogenates from ketohexokinase (KHK)(-/-) mice. We then induced active Ca(2+) transport by chronically feeding wild-type, fructose transporter glucose transporter 5 (GLUT5)(-/-), as well as KHK(-/-) mice a low Ca(2+) diet and measured transepithelial Ca(2+) transport in everted duodenal sacs incubated in solutions containing glucose, fructose, or their nonmetabolizable analogs. The diet-induced increase in active Ca(2+) transport was proportional to dramatic increases in expression of the Ca(2+)-selective channel transient receptor potential vanilloid family calcium channel 6 as well as of the Ca(2+)-binding protein 9k (CaBP9k) but not that of the voltage-dependent L-type channel Ca(v)1.3. Crypt-villus distribution of CaBP9k seems heterogeneous, but low Ca(2+) diets induce expression in more cells. In contrast, KHK distribution is homogeneous, suggesting that fructose metabolism can occur in all enterocytes. Diet-induced Ca(2+) transport was not enhanced by addition of the enterocyte fuel glutamine and was always greater in sacs of wild-type, GLUT5(-/-), and KHK(-/-) mice incubated with fructose or nonmetabolizable sugars than those incubated with glucose. Thus duodenal Ca(2+) transport is not affected by fructose and enterocyte ATP concentrations but instead may decrease with glucose metabolism, as Ca(2+) transport remains high with 3-O-methylglucose that is also transported by sodium-glucose cotransporter 1 but cannot be metabolized.

  6. Growth of embryo and gene expression of nutrient transporters in the small intestine of the domestic pigeon (Columba livia)*

    PubMed Central

    Chen, Ming-xia; Li, Xiang-guang; Yang, Jun-xian; Gao, Chun-qi; Wang, Bin; Wang, Xiu-qi; Yan, Hui-chao

    2015-01-01

    The objective of this study was to investigate the relationship between gene expression of nutrient (amino acid, peptide, sodium and proton) transporters in the small intestine and embryonic growth in domestic pigeons (Columba livia). One hundred and twenty-five fertilized eggs were randomly assigned into five groups and were incubated under optimal conditions (temperature of 38.1 °C and relative humidity of 55%). Twenty embryos/birds from each group were sacrificed by cervical dislocation on embryonic day (E) 9, 11, 13, 15 and day of hatch (DOH). The eggs, embryos (without yolk sac), and organs (head, brain, heart, liver, lungs, kidney, gizzard, small intestine, legs, and thorax) were dissected, cleaned, and weighed. Small intestine samples were collected for RNA isolation. The mRNA abundance of intestinal nutrient transporters was evaluated by real-time reverse transcription-polymerase chain reaction (RT-PCR). We classified these ten organs into four types according to the changes in relative weight during embryonic development. In addition, the gene expression of nutrient transporters was differentially regulated by embryonic day. The mRNA abundances of b0,+AT, EAAT3, y+LAT2, PepT1, LAT4, NHE2, and NHE3 increased linearly with age, whereas mRNA abundances of CAT1, CAT2, LAT1, EAAT2, SNAT1, and SNAT2 were increased to higher levels on E9 or E11 and then decreased to lower levels until DOH. The results of correlation analysis showed that the gene expressions of b0,+AT, EAAT3, PepT1, LAT4, NHE2, NHE3, and y+LAT2 had positive correlations with body weight (0.71intestinal weight (0.80intestinal weight (−0.84

  7. Growth of embryo and gene expression of nutrient transporters in the small intestine of the domestic pigeon (Columba livia).

    PubMed

    Chen, Ming-xia; Li, Xiang-guang; Yang, Jun-xian; Gao, Chun-qi; Wang, Bin; Wang, Xiu-qi; Yan, Hui-chao

    2015-06-01

    The objective of this study was to investigate the relationship between gene expression of nutrient (amino acid, peptide, sodium and proton) transporters in the small intestine and embryonic growth in domestic pigeons (Columba livia). One hundred and twenty-five fertilized eggs were randomly assigned into five groups and were incubated under optimal conditions (temperature of 38.1 °C and relative humidity of 55%). Twenty embryos/birds from each group were sacrificed by cervical dislocation on embryonic day (E) 9, 11, 13, 15 and day of hatch (DOH). The eggs, embryos (without yolk sac), and organs (head, brain, heart, liver, lungs, kidney, gizzard, small intestine, legs, and thorax) were dissected, cleaned, and weighed. Small intestine samples were collected for RNA isolation. The mRNA abundance of intestinal nutrient transporters was evaluated by real-time reverse transcription-polymerase chain reaction (RT-PCR). We classified these ten organs into four types according to the changes in relative weight during embryonic development. In addition, the gene expression of nutrient transporters was differentially regulated by embryonic day. The mRNA abundances of b(0,+)AT, EAAT3, y(+)LAT2, PepT1, LAT4, NHE2, and NHE3 increased linearly with age, whereas mRNA abundances of CAT1, CAT2, LAT1, EAAT2, SNAT1, and SNAT2 were increased to higher levels on E9 or E11 and then decreased to lower levels until DOH. The results of correlation analysis showed that the gene expressions of b(0,+)AT, EAAT3, PepT1, LAT4, NHE2, NHE3, and y(+)LAT2 had positive correlations with body weight (0.71intestinal weight (0.80intestinal weight (-0

  8. Vasoactive Intestinal Peptide Inhibits Human Small-Cell Lung Cancer Proliferation in vitro and in vivo

    NASA Astrophysics Data System (ADS)

    Maruno, Kaname; Absood, Afaf; Said, Sami I.

    1998-11-01

    Small-cell lung carcinoma (SCLC) is an aggressive, rapidly growing and metastasizing, and highly fatal neoplasm. We report that vasoactive intestinal peptide inhibits the proliferation of SCLC cells in culture and dramatically suppresses the growth of SCLC tumor-cell implants in athymic nude mice. In both cases, the inhibition was mediated apparently by a cAMP-dependent mechanism, because the inhibition was enhanced by the adenylate cyclase activator forskolin and the phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine in proportion to increases in intracellular cAMP levels, and the inhibition was abolished by selective inhibition of cAMP-dependent protein kinase. If confirmed in clinical trials, this antiproliferative action of vasoactive intestinal peptide may offer a new and promising means of suppressing SCLC in human subjects, without the toxic side effects of chemotherapeutic agents.

  9. Vasoactive intestinal peptide may participate in the vasodilation of the dog hepatic artery

    SciTech Connect

    Varga, G.; Kiss, J.Z.; Papp, M.; Vizi, E.S.

    1986-08-01

    The possible direct action of vasoactive intestinal peptide (VIP) on dog hepatic arterial wall or on the noradrenergic innervation of the artery was investigated in vitro. In addition, VIP-containing nerve fibers and terminals were located in the wall of the artery with immunochemical staining. Direct evidence showed that VIP did not affect the release of (TH)norepinephrine but reduced the response of the isolated hepatic artery to electrical field stimulation and exogenous norepinephrine. This suggest that the effect of VIP is postjunctional on the smooth muscle of the artery. VIP-containing nerve fibers and varicosities were observed in the adventitial and medial layer of the arterial wall. These findings strongly support the hypothesis that vasoactive intestinal peptide is a physiological mediator of vasodilation in the hepatic artery.

  10. Identification of intestinal ion transport defects in microvillus inclusion disease.

    PubMed

    Kravtsov, Dmitri V; Ahsan, Md Kaimul; Kumari, Vandana; van Ijzendoorn, Sven C D; Reyes-Mugica, Miguel; Kumar, Anoop; Gujral, Tarunmeet; Dudeja, Pradeep K; Ameen, Nadia A

    2016-07-01

    Loss of function mutations in the actin motor myosin Vb (Myo5b) lead to microvillus inclusion disease (MVID) and death in newborns and children. MVID results in secretory diarrhea, brush border (BB) defects, villus atrophy, and microvillus inclusions (MVIs) in enterocytes. How loss of Myo5b results in increased stool loss of chloride (Cl(-)) and sodium (Na(+)) is unknown. The present study used Myo5b loss-of-function human MVID intestine, polarized intestinal cell models of secretory crypt (T84) and villus resembling (CaCo2BBe, C2BBe) enterocytes lacking Myo5b in conjunction with immunofluorescence confocal stimulated emission depletion (gSTED) imaging, immunohistochemical staining, transmission electron microscopy, shRNA silencing, immunoblots, and electrophysiological approaches to examine the distribution, expression, and function of the major BB ion transporters NHE3 (Na(+)), CFTR (Cl(-)), and SLC26A3 (DRA) (Cl(-)/HCO3 (-)) that control intestinal fluid transport. We hypothesized that enterocyte maturation defects lead villus atrophy with immature secretory cryptlike enterocytes in the MVID epithelium. We investigated the role of Myo5b in enterocyte maturation. NHE3 and DRA localization and function were markedly reduced on the BB membrane of human MVID enterocytes and Myo5bKD C2BBe cells, while CFTR localization was preserved. Forskolin-stimulated CFTR ion transport in Myo5bKD T84 cells resembled that of control. Loss of Myo5b led to YAP1 nuclear retention, retarded enterocyte maturation, and a cryptlike phenotype. We conclude that preservation of functional CFTR in immature enterocytes, reduced functional expression of NHE3, and DRA contribute to Cl(-) and Na(+) stool loss in MVID diarrhea.

  11. Phosphate transport by rat intestinal basolateral-membrane vesicles.

    PubMed Central

    Ghishan, F K; Kikuchi, K; Arab, N

    1987-01-01

    The characteristics of phosphate transport across intestinal basolateral membranes of the rat were determined by using enriched preparations in which uphill Na+-dependent D-glucose transport could not be demonstrated, but ATP-dependent Ca2+ transport was present. Phosphate transport was saturable, Na+-dependent and exhibited Michaelis-Menten kinetics. Vmax. was 51.1 +/- 4.2 pmol/10 s per mg of protein and Km was 14 +/- 3.9 microM. The transport process was electroneutral. Tracer-exchange experiments and counter-transport studies confirmed the presence of a Na+-Pi carrier at the basolateral membrane. The presence of inside-positive membrane potential did not enhance phosphate uptake, indicating that the Na+ effect is secondary to the presence of the Na+-Pi carrier rather than an induction of positive membrane potential. The stoichiometry of this carrier at pH 7.4 was 2 Na+:1 phosphate, as shown by direct studies utilizing the static-head method. These studies are the first to determine the presence of a phosphate carrier at the basolateral membrane. PMID:3663094

  12. Nutrient-intake-level-dependent regulation of intestinal development in newborn intrauterine growth-restricted piglets via glucagon-like peptide-2.

    PubMed

    Liu, J; Liu, Z; Gao, L; Chen, L; Zhang, H

    2016-10-01

    The objective of the present study was to investigate the intestinal development of newborn intrauterine growth-restricted (IUGR) piglets subjected to normal nutrient intake (NNI) or restricted nutrient intake (RNI). Newborn normal birth weight (NBW) and IUGR piglets were allotted to NNI or RNI levels for 4 weeks from day 8 postnatal. IUGR piglets receiving NNI had similar growth performance compared with that of NBW piglets. Small intestine length and villous height were greater in IUGR piglets fed the NNI than that of piglets fed the RNI. Lactase activity was increased in piglets fed the NNI compared with piglets fed the RNI. Absorptive function, represented by active glucose transport by the Ussing chamber method and messenger RNA (mRNA) expressions of two main intestinal glucose transporters, Na+-dependent glucose transporter 1 (SGLT1) and glucose transporter 2 (GLUT2), were greater in IUGR piglets fed the NNI compared with piglets fed the RNI regimen. The apoptotic process, characterized by caspase-3 activity (a sign of activated apoptotic cells) and mRNA expressions of p53 (pro-apoptotic), bcl-2-like protein 4 (Bax) (pro-apoptotic) and B-cell lymphoma-2 (Bcl-2) (anti-apoptotic), were improved in IUGR piglets fed the NNI regimen. To test the hypothesis that improvements in intestinal development of IUGR piglets fed NNI might be mediated through circulating glucagon-like peptide-2 (GLP-2), GLP-2 was injected subcutaneously to IUGR piglets fed the RNI from day 8 to day 15 postnatal. Although the intestinal development of IUGR piglets fed the RNI regimen was suppressed compared with those fed the NNI regimen, an exogenous injection of GLP-2 was able to bring intestinal development to similar levels as NNI-fed IUGR piglets. Collectively, our results demonstrate that IUGR neonates that have NNI levels could improve intestinal function via the regulation of GLP-2.

  13. Transepithelial transport of flavanone in intestinal Caco-2 cell monolayers

    SciTech Connect

    Kobayashi, Shoko; Konishi, Yutaka

    2008-03-28

    Our recent study [S. Kobayashi, S. Tanabe, M. Sugiyama, Y. Konishi, Transepithelial transport of hesperetin and hesperidin in intestinal Caco-2 cell monolayers, Biochim. Biophys. Acta, 1778 (2008) 33-41] shows that the mechanism of absorption of hesperetin involves both proton-coupled active transport and transcellular passive diffusion. Here, as well as analyzing the cell permeability of hesperetin, we also study the transport of other flavanones, naringenin and eriodictyol, using Caco-2 cell monolayers. Similar to hesperetin mentioned, naringenin and eriodictyol showed proton-coupled polarized transport in apical-to-basolateral direction in non-saturable manner, constant permeation in the apical-to-basolateral direction (J{sub ap{yields}}{sub bl}) irrespective of the transepithelial electrical resistance (TER), and preferable distribution into the basolateral side after apical loading in the presence of a proton gradient. Furthermore, the proton-coupled J{sub ap{yields}}{sub bl} of hesperetin, naringenin and eriodictyol, were inhibited by substrates of the monocarboxylic acid transporter (MCT), such as benzoic acid, but not by ferulic acid. In contrast, both benzoic and ferulic acids have no stimulatory effect on J{sub ap{yields}}{sub bl} of each flavanone by trans-stimulation analysis. These results indicates that proton-driven active transport is commonly participated in the absorption of flavanone in general, and that its transport is presumed to be unique other than MCT-mediated transport for absorption of phenolic acids (PAs), sodium-dependent MCT (SMCT) nor anion exchanger-mediated transport.

  14. Steric and interactive barrier properties of intestinal mucus elucidated by particle diffusion and peptide permeation.

    PubMed

    Boegh, Marie; García-Díaz, María; Müllertz, Anette; Nielsen, Hanne Mørck

    2015-09-01

    The mucus lining of the gastrointestinal tract epithelium is recognized as a barrier to efficient oral drug delivery. Recently, a new in vitro model for assessment of drug permeation across intestinal mucosa was established by applying a biosimilar mucus matrix to the surface of Caco-2 cell monolayers. The aim of the present study was to gain more insight into the steric and interactive barrier properties of intestinal mucus by studying the permeation of peptides and model compounds across the biosimilar mucus as well as across porcine intestinal mucus (PIM). As PIM disrupted the Caco-2 cell monolayers, a cell-free mucus barrier model was implemented in the studies. Both the biosimilar mucus and the PIM reduced the permeation of the selected peptide drugs to varying degrees illustrating the interactive properties of both mucus matrices. The reduction in peptide permeation was decreased depending on the cationicity and H-bonding capacity of the permeant clearly demonstrated by using the biosimilar mucus, whereas the larger inter sample variation of the PIM matrix obstructed similarly clear conclusions. Thus, for mechanistic studies of permeation across mucus and mucosa the biosimilar mucus offers a relevant and reproducible alternative to native mucus. Copyright © 2015 Elsevier B.V. All rights reserved.

  15. Glucagon-like peptide-2 protects impaired intestinal mucosal barriers in obstructive jaundice rats

    PubMed Central

    Chen, Jun; Dong, Jia-Tian; Li, Xiao-Jing; Gu, Ye; Cheng, Zhi-Jian; Cai, Yuan-Kun

    2015-01-01

    AIM: To observe the protective effect of glucagon-like peptide-2 (GLP-2) on the intestinal barrier of rats with obstructive jaundice and determine the possible mechanisms of action involved in the protective effect. METHODS: Thirty-six Sprague-Dawley rats were randomly divided into a sham operation group, an obstructive jaundice group, and a GLP-2 group; each group consisted of 12 rats. The GLP-2 group was treated with GLP-2 after the day of surgery, whereas the other two groups were treated with the same concentration of normal saline. Alanine aminotransferase (ALT), total bilirubin, and endotoxin levels were recorded at 1, 3, 7, 10 and 14 d. Furthermore, on the 14th day, body weight, the wet weight of the small intestine, pathological changes of the small intestine and the immunoglobulin A (IgA) expressed by plasma cells located in the small intestinal lamina propria were recorded for each group. RESULTS: In the rat model, jaundice was obvious, and the rats’ activity decreased 4-6 d post bile duct ligation. Compared with the sham operation group, the obstructive jaundice group displayed increased yellow staining of abdominal visceral serosa, decreased small intestine wet weight, thinning of the intestinal muscle layer and villi, villous atrophy, uneven height, fusion, partial villous epithelial cell shedding, substantial inflammatory cell infiltration and significantly reduced IgA expression. However, no significant gross changes were noted between the GLP-2 and sham groups. With time, the levels of ALT, endotoxin and bilirubin in the GLP-2 group were significantly increased compared with the sham group (P < 0.01). The increasing levels of the aforementioned markers were more significant in the obstructive jaundice group than in the GLP-2 group (P < 0.01). CONCLUSION: GLP-2 reduces intestinal mucosal injuries in obstructive jaundice rats, which might be attributed to increased intestinal IgA and reduced bilirubin and endotoxin. PMID:25593463

  16. Glucagon-like peptide-2 protects impaired intestinal mucosal barriers in obstructive jaundice rats.

    PubMed

    Chen, Jun; Dong, Jia-Tian; Li, Xiao-Jing; Gu, Ye; Cheng, Zhi-Jian; Cai, Yuan-Kun

    2015-01-14

    To observe the protective effect of glucagon-like peptide-2 (GLP-2) on the intestinal barrier of rats with obstructive jaundice and determine the possible mechanisms of action involved in the protective effect. Thirty-six Sprague-Dawley rats were randomly divided into a sham operation group, an obstructive jaundice group, and a GLP-2 group; each group consisted of 12 rats. The GLP-2 group was treated with GLP-2 after the day of surgery, whereas the other two groups were treated with the same concentration of normal saline. Alanine aminotransferase (ALT), total bilirubin, and endotoxin levels were recorded at 1, 3, 7, 10 and 14 d. Furthermore, on the 14(th) day, body weight, the wet weight of the small intestine, pathological changes of the small intestine and the immunoglobulin A (IgA) expressed by plasma cells located in the small intestinal lamina propria were recorded for each group. In the rat model, jaundice was obvious, and the rats' activity decreased 4-6 d post bile duct ligation. Compared with the sham operation group, the obstructive jaundice group displayed increased yellow staining of abdominal visceral serosa, decreased small intestine wet weight, thinning of the intestinal muscle layer and villi, villous atrophy, uneven height, fusion, partial villous epithelial cell shedding, substantial inflammatory cell infiltration and significantly reduced IgA expression. However, no significant gross changes were noted between the GLP-2 and sham groups. With time, the levels of ALT, endotoxin and bilirubin in the GLP-2 group were significantly increased compared with the sham group (P < 0.01). The increasing levels of the aforementioned markers were more significant in the obstructive jaundice group than in the GLP-2 group (P < 0.01). GLP-2 reduces intestinal mucosal injuries in obstructive jaundice rats, which might be attributed to increased intestinal IgA and reduced bilirubin and endotoxin.

  17. Intestinal transport of hexoses in the rat following chronic heat exposure

    NASA Technical Reports Server (NTRS)

    Carpenter, M.; Musacchia, X. J.

    1979-01-01

    The study examines intestinal transport of sugars (D-glucose and D-galactose) in vitro and assesses organ maintenance in chronically heat-exposed rats. The results suggest that the response of intestinal absorption to heat exposure in the rat involves changes in intestinal weight and in glucose utilization. Despite the reduction in total intestinal weight, the ability of intestinal tissue to transport hexose per unit weight remains stable. Differences in intestinal weight and glucose utilization between pair-fed and heat-exposed animals suggest that the intestinal response to chronic heat exposure is not solely a function of the amount of food consumed. Alterations of hexose transport appear to be related to altered glucose metabolism and not altered transport capacity.

  18. Accelerated intestinal glucose absorption in morbidly obese humans: relationship to glucose transporters, incretin hormones, and glycemia.

    PubMed

    Nguyen, Nam Q; Debreceni, Tamara L; Bambrick, Jenna E; Chia, Bridgette; Wishart, Judith; Deane, Adam M; Rayner, Chris K; Horowitz, Michael; Young, Richard L

    2015-03-01

    Intestinal glucose absorption is mediated by sodium-dependent glucose transporter 1 (SGLT-1) and glucose transporter 2 (GLUT2), which are linked to sweet taste receptor (STR) signaling and incretin responses. This study aimed to examine intestinal glucose absorption in morbidly obese humans and its relationship to the expression of STR and glucose transporters, glycemia, and incretin responses. Seventeen nondiabetic, morbidly obese subjects (body mass index [BMI], 48 ± 4 kg/m(2)) and 11 lean controls (BMI, 25 ± 1 kg/m(2)) underwent endoscopic duodenal biopsies before and after a 30-minute intraduodenal glucose infusion (30 g glucose and 3 g 3-O-methylglucose [3-OMG]). Blood glucose and plasma concentrations of 3-OMG, glucose-dependent insulinotropic polypeptide (GIP), glucagon-like peptide 1 (GLP-1), insulin, and glucagon were measured over 270 minutes. Expression of duodenal SGLT-1, GLUT2, and STR (T1R2) was quantified by PCR. The increase in plasma 3-OMG (P < .001) and blood glucose (P < .0001) were greater in obese than lean subjects. Plasma 3-OMG correlated directly with blood glucose (r = 0.78, P < .01). In response to intraduodenal glucose, plasma GIP (P < .001), glucagon (P < .001), and insulin (P < .001) were higher, but GLP-1 (P < .001) was less in the obese compared with lean. Expression of SGLT-1 (P = .035), but not GLUT2 or T1R2, was higher in the obese, and related to peak plasma 3-OMG (r = 0.60, P = .01), GIP (r = 0.67, P = .003), and insulin (r = 0.58, P = .02). In morbid obesity, proximal intestine glucose absorption is accelerated and related to increased SGLT-1 expression, leading to an incretin-glucagon profile promoting hyperinsulinemia and hyperglycemia. These findings are consistent with the concept that accelerated glucose absorption in the proximal gut underlies the foregut theory of obesity and type 2 diabetes.

  19. Interactions among secretory immunoglobulin A, CD71, and transglutaminase-2 affect permeability of intestinal epithelial cells to gliadin peptides.

    PubMed

    Lebreton, Corinne; Ménard, Sandrine; Abed, Juliette; Moura, Ivan Cruz; Coppo, Rosanna; Dugave, Christophe; Monteiro, Renato C; Fricot, Aurélie; Traore, Meriem Garfa; Griffin, Martin; Cellier, Christophe; Malamut, Georgia; Cerf-Bensussan, Nadine; Heyman, Martine

    2012-09-01

    The transferrin receptor (CD71) is up-regulated in duodenal biopsy samples from patients with active celiac disease and promotes retrotransport of secretory immunoglobulin A (SIgA)-gliadin complexes. We studied intestinal epithelial cell lines that overexpress CD71 to determine how interactions between SIgA and CD71 promote transepithelial transport of gliadin peptides. We analyzed duodenal biopsy specimens from 8 adults and 1 child with active celiac disease. Caco-2 and HT29-19A epithelial cell lines were transfected with fluorescence-labeled small interfering RNAs against CD71. Interactions among IgA, CD71, and transglutaminase 2 (Tgase2) were analyzed by flow cytometry, immunoprecipitation, and confocal microscopy. Transcytosis of SIgA-CD71 complexes and intestinal permeability to the gliadin 3H-p31-49 peptide were analyzed in polarized monolayers of Caco-2 cells. Using fluorescence resonance energy transfer and in situ proximity ligation assays, we observed physical interactions between SIgA and CD71 or CD71 and Tgase2 at the apical surface of enterocytes in biopsy samples and monolayers of Caco-2 cells. CD71 and Tgase2 were co-precipitated with SIgA, bound to the surface of Caco-2 cells. SIgA-CD71 complexes were internalized and localized in early endosomes and recycling compartments but not in lysosomes. In the presence of celiac IgA or SIgA against p31-49, transport of intact 3H-p31-49 increased significantly across Caco-2 monolayers; this transport was inhibited by soluble CD71 or Tgase2 inhibitors. Upon binding to apical CD71, SIgA (with or without gliadin peptides) enters a recycling pathway and avoids lysosomal degradation; this process allows apical-basal transcytosis of bound peptides. This mechanism is facilitated by Tgase2 and might be involved in the pathogenesis of celiac disease. Copyright © 2012 AGA Institute. Published by Elsevier Inc. All rights reserved.

  20. Insulin stimulates transport of organic anion compounds mediated by organic anion transporting polypeptide 2B1 in the human intestinal cell line Caco-2.

    PubMed

    Kobayashi, Taku; Koizumi, Takahiro; Kobayashi, Masaki; Ogura, Jiro; Horiuchi, Yuichi; Kimura, Yuki; Kondo, Ayuko; Furugen, Ayako; Narumi, Katsuya; Takahashi, Natsuko; Iseki, Ken

    2017-04-01

    Organic anion transporting polypeptide 2B1 (OATP2B1) is the major uptake transporter in the intestine, and transports various clinically used therapeutic agents. Insulin acts through the insulin receptor in targeted cells, and Rab8A is one of the insulin signaling pathways. The small intestine in humans also expresses insulin receptor and Rab8A. It has been reported that insulin stimulates peptide transporter 1 (PEPT1) expression at the apical membrane and increases uptake of PEPT1 substrates in small intestine epithelial model cells (Caco-2 cells). However, the effect of insulin on OATP2B1 in the small intestine has not been fully investigated. We found that Rab8A was associated with OATP2B1-mediated estrone-3-sulfate (E3S) uptake. Insulin stimulated the uptake of E3S by Caco-2 cells and the enhancement was sustained for 120 min. The Vmax value of E3S uptake significantly increased upon insulin exposure. Caco-2 cells treated with insulin showed increased OATP2B1 expression at the cell surface. The apical-to-basal transport of E3S was also increased by insulin. The increase of E3S transport was inhibited by the cold condition (4 °C) or the OATP2B1 inhibitor, taurocholate. These results indicate that insulin acts on the small intestine to increase OATP2B1-mediated absorption. Copyright © 2016 The Japanese Society for the Study of Xenobiotics. Published by Elsevier Ltd. All rights reserved.

  1. Transepithelial transport of glutathione in isolated perfused small intestine

    SciTech Connect

    Hagen, T.M.; Jones, D.P.

    1986-03-01

    Uptake of GSH was studied in isolated perfused segment of jejunum in the adult rat. Krebs-Henseleit buffer was infused through the superior mesenteric artery and fractions were collected from the portal vein. The maintenance of vascular and epithelial integrity was established by lack of transfer of /sup 14/C-inulin or /sup 14/C-polyethylene glycol from the lumen to the perfusate. (glycine-2-/sup 3/H)GSH was introduced in the lumen and perfusate fractions collected every min. With 1 mM GSH and 10 mM Gly in the lumen, transport into the perfusate was 220 nmol/min. Analysis by HPLC showed that 80% was at the intact tripeptide, GSH. No cysteinylgylcine was detected in the perfusate. Pretreatment of the segment with 0.25 mM acivicin and 1 mM buthionine sulfoximine had no significant effect on GSH transport rate, thus showing that degradation and resynthesis of GSH did not contribute to the appearance of GSH in the perfusate. GSH transport was inhibited 50% by replacing lumenal NaCl with choline Cl. Addition of 10 mM ..gamma..-Clu-Glu or 10 mM ophthalmic acid decreased the rat of transport by 60-70%. These results establish that transepithelial transport of intact GSH occurs in rat small intestine. This may allow utilization of dietary GSH or reutilization of biliary GSH. In addition, the results suggest that oral GSH may be of therapeutic benefit.

  2. Radiation-induced reductions in transporter mRNA levels parallel reductions in intestinal sugar transport

    PubMed Central

    Roche, Marjolaine; Neti, Prasad V. S. V.; Kemp, Francis W.; Agrawal, Amit; Attanasio, Alicia; Douard, Véronique; Muduli, Anjali; Azzam, Edouard I.; Norkus, Edward; Brimacombe, Michael; Howell, Roger W.

    2010-01-01

    More than a century ago, ionizing radiation was observed to damage the radiosensitive small intestine. Although a large number of studies has since shown that radiation reduces rates of intestinal digestion and absorption of nutrients, no study has determined whether radiation affects mRNA expression and dietary regulation of nutrient transporters. Since radiation generates free radicals and disrupts DNA replication, we tested the hypotheses that at doses known to reduce sugar absorption, radiation decreases the mRNA abundance of sugar transporters SGLT1 and GLUT5, prevents substrate regulation of sugar transporter expression, and causes reductions in sugar absorption that can be prevented by consumption of the antioxidant vitamin A, previously shown by us to radioprotect the testes. Mice were acutely irradiated with 137Cs gamma rays at doses of 0, 7, 8.5, or 10 Gy over the whole body. Mice were fed with vitamin A-supplemented diet (100× the control diet) for 5 days prior to irradiation after which the diet was continued until death. Intestinal sugar transport was studied at days 2, 5, 8, and 14 postirradiation. By day 8, d-glucose uptake decreased by ∼10–20% and d-fructose uptake by 25–85%. With increasing radiation dose, the quantity of heterogeneous nuclear RNA increased for both transporters, whereas mRNA levels decreased, paralleling reductions in transport. Enterocytes of mice fed the vitamin A supplement had ≥ 6-fold retinol concentrations than those of mice fed control diets, confirming considerable intestinal vitamin A uptake. However, vitamin A supplementation had no effect on clinical or transport parameters and afforded no protection against radiation-induced changes in intestinal sugar transport. Radiation markedly reduced GLUT5 activity and mRNA abundance, but high-d-fructose diets enhanced GLUT5 activity and mRNA expression in both unirradiated and irradiated mice. In conclusion, the effect of radiation may be posttranscriptional, and

  3. Radiation-induced reductions in transporter mRNA levels parallel reductions in intestinal sugar transport.

    PubMed

    Roche, Marjolaine; Neti, Prasad V S V; Kemp, Francis W; Agrawal, Amit; Attanasio, Alicia; Douard, Véronique; Muduli, Anjali; Azzam, Edouard I; Norkus, Edward; Brimacombe, Michael; Howell, Roger W; Ferraris, Ronaldo P

    2010-01-01

    More than a century ago, ionizing radiation was observed to damage the radiosensitive small intestine. Although a large number of studies has since shown that radiation reduces rates of intestinal digestion and absorption of nutrients, no study has determined whether radiation affects mRNA expression and dietary regulation of nutrient transporters. Since radiation generates free radicals and disrupts DNA replication, we tested the hypotheses that at doses known to reduce sugar absorption, radiation decreases the mRNA abundance of sugar transporters SGLT1 and GLUT5, prevents substrate regulation of sugar transporter expression, and causes reductions in sugar absorption that can be prevented by consumption of the antioxidant vitamin A, previously shown by us to radioprotect the testes. Mice were acutely irradiated with (137)Cs gamma rays at doses of 0, 7, 8.5, or 10 Gy over the whole body. Mice were fed with vitamin A-supplemented diet (100x the control diet) for 5 days prior to irradiation after which the diet was continued until death. Intestinal sugar transport was studied at days 2, 5, 8, and 14 postirradiation. By day 8, d-glucose uptake decreased by approximately 10-20% and d-fructose uptake by 25-85%. With increasing radiation dose, the quantity of heterogeneous nuclear RNA increased for both transporters, whereas mRNA levels decreased, paralleling reductions in transport. Enterocytes of mice fed the vitamin A supplement had > or = 6-fold retinol concentrations than those of mice fed control diets, confirming considerable intestinal vitamin A uptake. However, vitamin A supplementation had no effect on clinical or transport parameters and afforded no protection against radiation-induced changes in intestinal sugar transport. Radiation markedly reduced GLUT5 activity and mRNA abundance, but high-d-fructose diets enhanced GLUT5 activity and mRNA expression in both unirradiated and irradiated mice. In conclusion, the effect of radiation may be posttranscriptional

  4. Metformin Transport by a Newly Cloned Proton-Stimulated Organic Cation Transporter (Plasma Membrane Monoamine Transporter) Expressed in Human Intestine

    PubMed Central

    Zhou, Mingyan; Xia, Li; Wang, Joanne

    2009-01-01

    Metformin is a widely used oral antihyperglycemic drug for the treatment of type II diabetes mellitus. The intestinal absorption of metformin is dose-dependent and involves an active, saturable uptake process. Metformin has been shown to be transported by the human organic cation transporters 1 and 2 (hOCT1–2). We recently cloned and characterized a novel proton-activated organic cation transporter, plasma membrane monoamine transporter (PMAT). We previously showed that PMAT transports many classic organic cations (e.g., monoamine neurotransmitters, 1-methyl-4-phenylpyridinium) in a pH-dependent manner and its mRNA is expressed in multiple human tissues. The goal of this study is to investigate whether metformin is a substrate of PMAT and whether PMAT plays a role in the intestinal uptake of metformin. Using Madin-Darby canine kidney cells stably expressing human PMAT, we showed that metformin is avidly transported by PMAT, with an apparent affinity (Km = 1.32 mM) comparable to those reported for hOCT1–2. Interestingly, the concentration-velocity profile of PMAT-mediated metformin uptake is sigmoidal, with a Hill coefficient of 2.64. PMAT-mediated metformin transport is greatly stimulated by acidic pH, with the uptake rate being ~4-fold higher at pH 6.6 than at pH 7.4. Using a polyclonal antibody against PMAT, we showed that the PMAT protein (58 kDa) was expressed in human small intestine and concentrated on the tips of the mucosal epithelial layer. Taken together, our results suggest that PMAT transports metformin, is expressed in human intestine, and may play a role in the intestinal absorption of metformin and possibly other cationic drugs. PMID:17600084

  5. Differential Effects on Intestinal Adaptation Following Exogenous Glucagon-Like Peptide 2 Therapy With and Without Enteral Nutrition in Neonatal Short Bowel Syndrome [Formula: see text].

    PubMed

    Lim, David W; Diané, Abdoulaye; Muto, Mitsuru; Vine, Donna F; Nation, Patrick N; Wizzard, Pamela R; Sigalet, David L; Bigam, David L; Pencharz, Paul B; Turner, Justine M; Wales, Paul W

    2017-02-01

    We aim to study the efficacy of exogenously administered glucagon-like peptide 2 (GLP-2) on intestinal adaptation in 2 preclinical models of neonatal short bowel syndrome (SBS) according to remnant intestinal anatomy, with and without ileum. Furthermore, we aim to determine if this adaptive effect was potentiated with enteral nutrition (EN). Neonatal piglets were block-randomized to 75% mid-intestinal (JI group, retains ileum) or distal-intestinal (JC group, has no ileum) resection or no resection (sham control) and GLP-2 treatment (11 nmol/kg/d) or saline control for 7 days. Piglets received nutrition support, either 100% parenteral nutrition (PN; 0% EN, n = 32 in total) or 80% PN + 40% EN (n = 28 in total). Adaptation was assessed by morphological and histological changes, as well as RT quantitative polymerase chain reaction of nutrient transporters and tight junctional proteins and fat absorption. Data are analyzed by 3-way analysis of variance (ANOVA) and 2-way ANOVA per EN level. GLP-2 treatment lengthened villi, deepened crypts, and improved intestinal weight in the remnant intestine of JC piglets. EN was a more potent adaptive stimulus for JI piglets. Small intestinal lengthening occurred only in the JI group, when given EN. There was no difference in total fat absorption and messenger RNA expression of nutrient transporters and tight junctional proteins. GLP-2 administration augmented structural adaptation in JC piglets with distal intestinal resection. Given JI anatomy, further stimulation by GLP-2 treatment over innate adaptation and stimulation by EN was modest and restricted to ileum. The differential effect of GLP-2 in neonatal SBS, depending on remnant anatomy, has important implications for clinical translation and planning of clinical trials.

  6. Intestinal Metrnl released into the gut lumen acts as a local regulator for gut antimicrobial peptides.

    PubMed

    Li, Zhi-Yong; Fan, Mao-Bing; Zhang, Sai-Long; Qu, Yi; Zheng, Si-Li; Song, Jie; Miao, Chao-Yu

    2016-11-01

    Metrnl is a novel secreted protein, but its physiological roles remain elusive. In this study, we investigated the tissue expression pattern of Metrnl in humans and explored its possible physiological role in the tissues with most highly expressed levels. A human tissue microarray containing 19 types of tissues from 69 donors was used to examine the tissue expression pattern of Metrnl, and the expression pattern was further verified in fresh human and mouse tissues. Intestinal epithelial cell-specific Metrnl knockout mice were generated, which were used to analyze the physiological roles of Metrnl. Metrnl was the most highly expressed in the human gastrointestinal tract, and was specifically expressed in the intestinal epithelium. Consistent with this, Metrnl mRNA was also most highly expressed in the mouse gastrointestinal tract among the 14 types of tissues tested. In the intestinal epithelial cell-specific Metrnl knockout mice, the Metrnl levels in the gut fluid were significantly reduced, whereas the Metrnl serum levels showed a trend towards a reduction, but this change was not statistically significant. This cell-specific deletion of Metrnl did not affect body weight, food intake, blood glucose, colon length and histology, intestinal permeability, mucus content or mucin 2 expression under physiological conditions, but statistically decreased the expression of antimicrobial peptides, such as regenerating islet-derived 3 gamma (Reg3g) and lactotransferrin. Metrnl is highly expressed in the intestinal epithelial cells of humans and mice, which mainly contributes to the local gut Metrnl levels and affects the serum Metrnl level to a lesser extent. Metrnl plays a role in maintaining gut antimicrobial peptides.

  7. Thiamine transport across the rat intestine. II. Effect of ethanol.

    PubMed

    Hoyumpa, A M; Breen, K J; Schenker, S; Wilson, F A

    1975-11-01

    We have previously investigated the normal characteristics of thiamine intestinal transport in rats and found that a very low concentrations (0.06 to 2.0 muM) thiamine transport is a saturable, carrier-mediated, active process while at high concentrations (greater than 2.0 muM) transport proceeds by simple diffusion. The present studies were undertaken to characterize the effect of ethanol on thiamine transport. Intact isolated loops were used to measure rates of 35S-thiamine hydrochloride absorption into the circulation in vivo, and everted jejunal segments to measure net transmural flux, unidirectional uptake, and cellular exit of 14C-thiamine hydrochloride in vitro. Intragastric administration of ethanol (50 to 750 mg. per 100 grams of weight) reduced absorption of low thiamine concentration in vivo to 65.44 per cent of control value. A similar inhibition was noted after intravenous ethanol. Once attained, the inhibition of thiamine absorption was not related to the ethanol dose or to ethanol concentration in the blood or in the intestinal lumen; this inhibition was reversible. In contrast, ethanol did not affect absorption of high concentrations of thiamine. These findings were confirmed by the in vitro results. In transmural flux studies, the movement of low, but not high, thiamine concentration against a concentration gradient was inhibited by ethanol, so that the normal serosal/mucosal ratio of 1.5 was reduced to 1.0. Ethanol did not affect unidirectional uptake into the mucosa of either low or high thiamine concentrations, but blocked cellular exit of low thiamine concentrations from the cells into the serosal compartment. Exit of high thiamine concentrations was not affected. Ouabain, like ethanol, markedly reduced cellular exit but did not influence uptake of low thiamine concentrations. The present studies suggest that ethanol adversely affects the active, but not the passive, component of thiamine transport. Moreover, ethanol appears to block thiamine

  8. Functions of Ion Transport Peptide and Ion Transport Peptide-Like in the Red Flour Beetle Tribolium castaneum

    USDA-ARS?s Scientific Manuscript database

    Ion transport peptide (ITP) and ITP-like (ITPL) are highly conserved neuropeptides in insects and crustaceans. We investigated the alternatively spliced variants of ITP/ITPL in Tribolium castaneum to understand their functions. We identified three alternatively spliced transcripts named itp, itpl-...

  9. INFLUENCE OF DIETARY SUBSTANCES ON INTESTINAL DRUG METABOLISM AND TRANSPORT

    PubMed Central

    Won, Christina S.; Oberlies, Nicholas H.; Paine, Mary F.

    2011-01-01

    Successful delivery of promising new chemical entities via the oral route is rife with challenges, some of which cannot be explained or foreseen during drug development. Further complicating an already multifaceted problem is the obvious, yet often overlooked, effect of dietary substances on drug disposition and response. Some dietary substances, particularly fruit juices, have been shown to inhibit biochemical processes in the intestine, leading to altered pharmacokinetic (PK), and potentially pharmacodynamic (PD), outcomes. Inhibition of intestinal CYP3A-mediated metabolism is the major mechanism by which fruit juices, including grapefruit juice, enhances systemic exposure to new and already marketed drugs. Inhibition of intestinal non-CYP3A enzymes and apically-located transport proteins represent recently identified mechanisms that can alter PK and PD. Several fruit juices have been shown to inhibit these processes in vitro, but some interactions have not translated to the clinic. The lack of in vitro-in vivo concordance is due largely to a lack of rigorous methods to elucidate causative ingredients prior to clinical testing. Identification of specific components and underlying mechanisms is challenging, as dietary substances frequently contain multiple, often unknown, bioactive ingredients that vary in composition and bioactivity. A translational research approach, combining expertise from clinical pharmacologists and natural products chemists, is needed to develop robust models describing PK/PD relationships between a given dietary substance and drug of interest. Validation of these models through well-designed clinical trials would facilitate development of common practice guidelines for managing drug-dietary substance interactions appropriately. PMID:21189136

  10. Role of Quercetin in Modulating Chloride Transport in the Intestine

    PubMed Central

    Yu, Bo; Jiang, Yu; Jin, Lingling; Ma, Tonghui; Yang, Hong

    2016-01-01

    Epithelial chloride channels provide the pathways for fluid secretion in the intestine. Cystic fibrosis transmembrane conductance regulator (CFTR) and calcium-activated chloride channels (CaCCs) are the main chloride channels in the luminal membrane of enterocytes. These transmembrane proteins play important roles in many physiological processes. In this study, we have identified a flavonoid quercetin as a modulator of CaCC chloride channel activity. Fluorescence quenching assay showed that quercetin activated Cl− transport in a dose-dependent manner, with EC50 ~37 μM. Short-circuit current analysis confirmed that quercetin activated CaCC-mediated Cl− currents in HT-29 cells that can be abolished by CaCCinh-A01. Ex vivo studies indicated that application of quercetin to mouse ileum and colon on serosal side resulted in activation of CFTR and CaCC-mediated Cl− currents. Notably, we found that quercetin exhibited inhibitory effect against ANO1 chloride channel activity in ANO1-expressing FRT cells and decreased mouse intestinal motility. Quercetin-stimulated short-circuit currents in mouse ileum was multi-component, which included elevation of Ca2+ concentration through L-type calcium channel and activation of basolateral NKCC, Na+/K+-ATPase, and K+ channels. In vivo studies further revealed that quercetin promoted fluid secretion in mouse ileum. The modulatory effect of quercetin on CaCC chloirde channels may therefore represent a potential therapeutic strategy for treating CaCC-related diseases like constipation, secretory diarrhea and hypertension. The inverse effects of quercetin on CaCCs provided evidence that ANO1 and intestinal epithelial CaCCs are different calcium-activated chloride channels. PMID:27932986

  11. [Responses of peptide hydrolases of the small and large intestines in rats on the administration of antibiotics].

    PubMed

    Borshchëv, Iu Iu; Gromova, L V; Ermolenko, E I; Grefner, N M; Borshchëva, I Iu; Gruzdkov, A A

    2012-06-01

    Effects of antibiotics on the structure and functional state of the intestine are not clear. We investigated some structural parameters of the small and large intestine, and activities of two intestinal peptide hydrolases in rats after administration of ampicillin and metronidazole during 3 and 5 days. After 3 days of antibiotic administration a decrease in the weight of mucosa in the small intestine, accompanied with a reduction in the villous height and width in this part of the intestine, and in the weight ofmucosa in the colon occured. At the same time the number of goblet cells in the small intestinal epithelium was increased. Specific activities of aminopeptidase M, and glycyl-L-leucine dipeptidase (micromol/min per g) in the mucosa of the small intestine were increased, and the total activities (micromol/min calculated per a part of the intestine) of the same enzymes did not change. The administration of antibiotics for 5 days resulted in increase of specific activity ofaminopeptidase M in the mucosa of the proximal part of the small intestine. In the chyme of the small intestine and colon, activities of the same enzymes (micromol/min calculated per a part of the intestine) were increased on the third and fifth days of the antibiotic administration. Thus, the application ofampicillin and metronidazole within 3-5 days causes a disturbance of the structural and functional parameters in the small and large intestines, which is most pronounced on the third day of the drug administration.

  12. Glucagonlike peptide 2 analogue teduglutide: stimulation of proliferation but reduction of differentiation in human Caco-2 intestinal epithelial cells.

    PubMed

    Chaturvedi, Lakshmi S; Basson, Marc D

    2013-11-01

    Short bowel syndrome occurs when a shortened intestine cannot absorb sufficient nutrients or fluids. Teduglutide is a recombinant analogue of human glucagonlike peptide 2 that reduces dependence on parenteral nutrition in patients with short bowel syndrome by promoting enterocytic proliferation, increasing the absorptive surface area. However, enterocyte function depends not only on the number of cells that are present but also on differentiated features that facilitate nutrient absorption and digestion. To test the hypothesis that teduglutide impairs human intestinal epithelial differentiation. We investigated the effects of teduglutide in the modulation of proliferation and differentiation in human Caco-2 intestinal epithelial cells at a basic science laboratory. This was an in vitro study using Caco-2 cells, a human-derived intestinal epithelial cell line commonly used to model enterocytic biology. Cells were exposed to teduglutide or vehicle control. We analyzed the cell cycle by bromodeoxyuridine incorporation or propidium iodide staining and flow cytometry and measured cell proliferation by 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) assay. We used quantitative reverse transcription-polymerase chain reaction to assay the expression of the enterocytic differentiation markers villin, sucrase-isomaltase, glucose transporter 2 (GLUT2), and dipeptidyl peptidase 4 (DPP-4), as well as that of the putative differentiation signals schlafen 12 (SLFN12) and caudal-related homeobox intestine-specific transcription factor (Cdx2). Villin promoter activity was measured by a luciferase-based assay. The MTS assay demonstrated that teduglutide increased cell numbers by a mean (SD) of 10% (2%) over untreated controls at a maximal 500 nM (n = 6, P < .05). Teduglutide increased bromodeoxyuridine-positive cells vs untreated controls by a mean (SD) of 19.4% (2.3%) vs 12.0% (0.8%) (n = 6, P < .05) and increased the S-phase fraction

  13. Transport of nattokinase across the rat intestinal tract.

    PubMed

    Fujita, M; Hong, K; Ito, Y; Misawa, S; Takeuchi, N; Kariya, K; Nishimuro, S

    1995-09-01

    Intraduodenal administration of nattokinase (NK) at a dose of 80 mg/kg, resulted in the degradation of fibrinogen in plasma suggesting transport of NK across the intestinal tract in normal rats. The action of NK on the cleavage of fibrinogen in the plasma from blood samples drawn at intervals after intraduodenal administration of the enzyme was investigated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and Western blotting analysis with an anti-fibrinogen gamma chain antibody. The 270 kDa fragment carrying antigenic sites for the binding of the anti-fibrinogen gamma chain antibody appeared within 0.5 h and was then degraded gradually to a 105 kDa fragment via a 200 kDa fragment. This suggests that fibrinogen was degraded to a 105 kDa fragment via several intermediates (270 and 200 kDa). In parallel with the degradation process, plasma recalcification times were remarkably prolonged NK was also detected in the plasma from blood samples drawn 3 and 5 h after administration of the enzyme by SDS-PAGE and Western blotting analysis with an anti-NK antibody. The results indicate that NK is absorbed from the rat intestinal tract and that NK cleaves fibrinogen in plasma after intraduodenal administration of the enzyme.

  14. Vitamin D and intestinal calcium transport: facts, speculations and hypotheses.

    PubMed

    Wasserman, R H; Fullmer, C S

    1995-07-01

    The intestinal absorption of Ca2+ occurs by both a saturable, transcellular process and a nonsaturable, paracellular path. The transcellular path is a multistep process, comprised of the transfer of luminal Ca2+ into the enterocyte, the translocation of Ca2+ from point of entry (the microvillus border or membrane) to the basolateral membrane, and the active extrusion from the cell into the circulatory system. Each step in the transcellular movement of Ca2+ has a vitamin D-dependent component. The paracellular path also appears to be affected by vitamin D status. This review emphasizes some aspects of the Ca2+ absorptive process that require resolution and/or further experimental support. The following are discussed: evidence for participation in the active transport of Ca2+ by all segments of the small intestine; a hypothetical model for the feedback control of entry of luminal Ca2+; the current views on vitamin D-dependent movement of Ca2+ through the cytosolic compartment of the enterocyte; the stimulated synthesis of the plasma membrane Ca2+ pump and its gene expression by vitamin D; and the vitamin D-dependency of the paracellular transfer of Ca2+ with a comment on the physiological significance of the rapid response of the Ca2+ absorptive system in vitamin D-replete animals to 1,25-dihydroxyvitamin D.

  15. Effects of composite antimicrobial peptides in weanling piglets challenged with deoxynivalenol: II. Intestinal morphology and function.

    PubMed

    Xiao, H; Tan, B E; Wu, M M; Yin, Y L; Li, T J; Yuan, D X; Li, L

    2013-10-01

    Deoxynivalenol (DON) affects animal and human health and targets the gastrointestinal tract. The objective of this study was to evaluate the ability of composite antimicrobial peptides (CAP) to repair intestinal injury in piglets challenged with DON. A total of 28 piglets (Duroc × Landrace × Large Yorkshire) weaned at 28 d of age were randomly assigned to receive 1 of 4 treatments (7 pigs/treatment): negative control, basal diet (NC), basal diet + 0.4% composite antimicrobial peptide (CAP), basal diet + 4 mg/kg DON (DON), and basal diet + 4 mg/kg DON + 0.4% CAP (DON + CAP). After an adaptation period of 7 d, blood samples were collected on d 15 and 30 after the initiation of treatment for determinations of the concentrations of D-lactate and diamine oxidase. At the end of the study, all piglets were slaughtered to obtain small intestines for the determination of intestinal morphology, epithelial cell proliferation, and protein expression in the mammalian target of rapamycin (mTOR) signaling pathway. The results showed that DON increased serum concentrations of D-lactate and diamine oxidase, and these values in the CAP and DON + CAP treatments were less than those in the NC and DON treatments, respectively (P < 0.05). The villous height/crypt depth in the jejunum and ileum and the goblet cell number in the ileum in the CAP and DON + CAP treatments were greater than those in the NC and DON treatments (P < 0.05). The proliferating cell nuclear antigen (PCNA) labeling indexes for the jejunum and ileum in the DON + CAP treatment were greater than those in the DON treatment (P < 0.05). The DON decreased (P < 0.05) the relative protein expression of phosphorylated Akt (Protein Kinase B) and mTOR in the jejunal and ileal mucosa and of phosphorylated 4E-binding protein 1 (p-4EBP1) in the jejunal mucosa, whereas CAP increased (P < 0.05) the protein expression of p-4EBP1 in the jejunum. These findings showed that DON could enhance intestinal permeability, damage villi

  16. Microvillus-Specific Protein Tyrosine Phosphatase SAP-1 Plays a Role in Regulating the Intestinal Paracellular Transport of Macromolecules.

    PubMed

    Mori, Shingo; Kamei, Noriyasu; Murata, Yoji; Takayama, Kozo; Matozaki, Takashi; Takeda-Morishita, Mariko

    2017-09-01

    The stomach cancer-associated protein tyrosine phosphatase 1 (SAP-1) is a receptor-type protein tyrosine phosphatase that is specifically expressed on the apical membrane of the intestinal epithelium. SAP-1 is known to maintain the balance of phosphorylation of proteins together with protein kinases; however, its biological function and impact on pharmacokinetics in the intestine remain unclear. The present study, therefore, aimed at clarifying the relationship between SAP-1 and the intestinal absorption behaviors of typical transporter substrates and macromolecules. The endogenous levels of glucose and total cholesterol in the blood were similar between wild-type and SAP-1-deficient mice (Sap1(-/-)), suggesting no contribution of SAP-1 to biogenic influx. Moreover, in vitro transport study with everted ileal sacs demonstrated that there was no difference in the absorption of breast cancer resistance protein, P-glycoprotein, and peptide transporter substrates between both mice. However, absorptive clearance of macromolecular model dextrans (FD-4 and FD-10) in Sap1(-/-) mice was significantly higher than that in wild-type mice, and this was confirmed by the trend of increased FD-4 absorption from colonic loops of Sap1(-/-) mice. Therefore, the results of this study suggest the partial contribution of SAP-1 to the regulated transport of hydrophilic macromolecules through paracellular tight junctions. Copyright © 2017 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

  17. Acetylcholine-producing T cells in the intestine regulate antimicrobial peptide expression and microbial diversity.

    PubMed

    Dhawan, Shobhit; De Palma, Giada; Willemze, Rose A; Hilbers, Francisca W; Verseijden, Caroline; Luyer, Misha D; Nuding, Sabine; Wehkamp, Jan; Souwer, Yuri; de Jong, Esther C; Seppen, J; van den Wijngaard, René M; Wehner, Sven; Verdu, Elena; Bercik, Premek; de Jonge, Wouter J

    2016-11-01

    The cholinergic anti-inflammatory pathway reduces systemic tumor necrosis factor (TNF) via acetylcholine-producing memory T cells in the spleen. These choline acetyltransferase (ChAT)-expressing T cells are also found in the intestine, where their function is unclear. We aimed to characterize these cells in mouse and human intestine and delineate their function. We made use of the ChAT-enhanced green fluorescent protein (eGFP) reporter mice. CD4(Cre) mice were crossed to ChAT(fl/fl) mice to achieve specific deletion of ChAT in CD4(+) T cells. We observed that the majority of ChAT-expressing T cells in the human and mouse intestine have characteristics of Th17 cells and coexpress IL17A, IL22, and RORC The generation of ChAT-expressing T cells was skewed by dendritic cells after activation of their adrenergic receptor β2 To evaluate ChAT T cell function, we generated CD4-specific ChAT-deficient mice. CD4ChAT(-/-) mice showed a reduced level of epithelial antimicrobial peptides lysozyme, defensin A, and ang4, which was associated with an enhanced bacterial diversity and richness in the small intestinal lumen in CD4ChAT(-/-) mice. We conclude that ChAT-expressing T cells in the gut are stimulated by adrenergic receptor activation on dendritic cells. ChAT-expressing T cells may function to mediate the host AMP secretion, microbial growth and expansion.

  18. Expression of small intestinal nutrient transporters in embryonic and posthatch turkeys.

    PubMed

    Weintraut, M L; Kim, S; Dalloul, R A; Wong, E A

    2016-01-01

    Nutrients are absorbed in the small intestine through a variety of transporter proteins, which have not been as well characterized in turkeys as in chickens. The objective of this study was to profile the mRNA expression of amino acid and monosaccharide transporters in the small intestine of male and female turkeys. Jejunum was collected during embryonic development (embryonic d 21 and 24, and d of hatch (DOH)) and duodenum, jejunum, and ileum were collected in a separate experiment during posthatch development (DOH, d 7, 14, 21, and 28). Real-time PCR was used to determine expression of aminopeptidase N (APN), one peptide (PepT1), 6 amino acid (ASCT1, b(o,+)AT, CAT1, EAAT3, LAT1, y(+)LAT2) and 3 monosaccharide (GLUT2, GLUT5, SGLT1) transporters. Data were analyzed by ANOVA using JMP Pro 11.0. APN, b(o,+)AT, PepT1, y(+)LAT2, GLUT5, and SGLT1 showed increased expression from embryonic d 21 and 24 to DOH. During posthatch, all genes except GLUT2 and SGLT1 were expressed greater in females than males. GLUT2 was expressed the same in males as females and SGLT1 was expressed greater in males than females. All basolateral membrane transporters were expressed greater during early development then decreased with age, while the brush border membrane transporters EAAT3, GLUT5, and SGLT1 showed increased expression later in development. Because turkeys showed high-level expression of the anionic amino acid transporter EAAT3, a direct comparison of tissue-specific expression of EAAT3 between chicken and turkey was conducted. The anionic amino acid transporter EAAT3 showed 6-fold greater expression in the ileum of turkeys at d 14 compared to chickens. This new knowledge can be used not only to better formulate turkey diets to accommodate increased glutamate transport, but also to optimize nutrition for both sexes. © 2015 Poultry Science Association Inc.

  19. A unified nomenclature of NITRATE TRANSPORTER 1/PEPTIDE TRANSPORTER family members in plants.

    PubMed

    Léran, Sophie; Varala, Kranthi; Boyer, Jean-Christophe; Chiurazzi, Maurizio; Crawford, Nigel; Daniel-Vedele, Françoise; David, Laure; Dickstein, Rebecca; Fernandez, Emilio; Forde, Brian; Gassmann, Walter; Geiger, Dietmar; Gojon, Alain; Gong, Ji-Ming; Halkier, Barbara A; Harris, Jeanne M; Hedrich, Rainer; Limami, Anis M; Rentsch, Doris; Seo, Mitsunori; Tsay, Yi-Fang; Zhang, Mingyong; Coruzzi, Gloria; Lacombe, Benoît

    2014-01-01

    Members of the plant NITRATE TRANSPORTER 1/PEPTIDE TRANSPORTER (NRT1/PTR) family display protein sequence homology with the SLC15/PepT/PTR/POT family of peptide transporters in animals. In comparison to their animal and bacterial counterparts, these plant proteins transport a wide variety of substrates: nitrate, peptides, amino acids, dicarboxylates, glucosinolates, IAA, and ABA. The phylogenetic relationship of the members of the NRT1/PTR family in 31 fully sequenced plant genomes allowed the identification of unambiguous clades, defining eight subfamilies. The phylogenetic tree was used to determine a unified nomenclature of this family named NPF, for NRT1/PTR FAMILY. We propose that the members should be named accordingly: NPFX.Y, where X denotes the subfamily and Y the individual member within the species. Copyright © 2013 Elsevier Ltd. All rights reserved.

  20. [Role of antimicrobial peptides (AMP) and pattern recognition receptors (PRR) in the intestinal mucosa homeostasis].

    PubMed

    Lapis, Károly

    2009-11-22

    Homeostasis and integrity of bowel mucosa is assured by well controlled mechanical, biochemical and immunological mechanisms. First line of defense is presented by the antimicrobial peptides (AMP), which form a continuous layer on the bowel surface, produced by intestinal specific (Paneth) and non-specific epithelial cells. AMPs have a significant antimicrobial, antifungal and antiviral, as well as immunomodulatory effects. Next line of defense is the pattern recognition receptors (PRR), which allows identifying conservative molecular patterns of different pathogens, and starts antimicrobial and inflammatory mechanisms through gene-expression induction. We review the most recent knowledge and studies concerning these mechanisms.

  1. Deficient Vasoactive Intestinal Peptide Innervation in the Sweat Glands of Cystic Fibrosis Patients

    NASA Astrophysics Data System (ADS)

    Heinz-Erian, Peter; Dey, Richard D.; Flux, Marinus; Said, Sami I.

    1985-09-01

    The innervation of acini and ducts of eccrine sweat glands by immunoreactive, vasoactive intestinal peptide--containing nerve fibers was sharply reduced in seven patients with cystic fibrosis compared to eight normal subjects. The decrease in innervation by this neuropeptide, which has been shown to promote blood flow and the movement of water and chloride across epithelial surfaces in other systems, may be a basic mechanism for the decreased water content and relative impermeability of the epithelium to chloride and other ions that characterize cystic fibrosis.

  2. Effect of dietary lead on intestinal nutrient transporters mRNA expression in broiler chickens.

    PubMed

    Ebrahimi, Roohollah; Faseleh Jahromi, Mohammad; Liang, Juan Boo; Soleimani Farjam, Abdoreza; Shokryazdan, Parisa; Idrus, Zulkifli

    2015-01-01

    Lead- (Pb-) induced oxidative stress is known to suppress growth performance and feed efficiency in broiler chickens. In an attempt to describe the specific underlying mechanisms of such phenomenon we carried out the current study. Ninety-six one-day-old broiler chicks were randomly assigned to 2 dietary treatment groups of 6 pen replicates, namely, (i) basal diet containing no lead supplement (control) and (ii) basal diet containing 200 mg lead acetate/kg of diet. Following 3 weeks of experimental period, jejunum samples were collected to examine the changes in gene expression of several nutrient transporters, antioxidant enzymes, and heat shock protein 70 (Hsp70) using quantitative real-time PCR. The results showed that addition of lead significantly decreased feed intake, body weight gain, and feed efficiency. Moreover, with the exception of GLUT5, the expression of all sugar, peptide, and amino acid transporters was significantly downregulated in the birds under Pb induced oxidative stress. Exposure to Pb also upregulated the antioxidant enzymes gene expression together with the downregulation of glutathione S-transferase and Hsp70. In conclusion, it appears that Pb-induced oxidative stress adversely suppresses feed efficiency and growth performance in chicken and the possible underlying mechanism for such phenomenon is downregulation of major nutrient transporter genes in small intestine.

  3. Genetic and biochemical analysis of peptide transport in Escherichia coli

    SciTech Connect

    Andrews, J.C.

    1986-01-01

    E. coli peptide transport mutants have been isolated based on their resistance to toxic tripeptides. These genetic defects were found to map in two distinct chromosomal locations. The transport systems which require expression of the trp-linked opp genes and the oppE gene(s) for activity were shown to have different substrate preferences. Growth of E. coli in medium containing leucine results in increased entry of exogenously supplied tripeptides into the bacterial cell. This leucine-mediated elevation of peptide transport required expression of the trp-linked opp operon and was accompanied by increased sensitivity to toxic tripeptides, by an enhanced capacity to utilize nutritional peptides, and by an increase in both the velocity and apparent steady-state level of L-(U-/sup 14/C)alanyl-L-alanyl-L-alanine accumulation for E. coli grown in leucine-containing medium relative to these parameters of peptide transport measured with bacteria grown in media lacking leucine. Direct measurement of opp operon expression by pulse-labeling experiments demonstrated that growth of E. coli in the presence of leucine resulted in increased synthesis of the oppA-encoded periplasmic binding protein. The transcriptional regulation of the trp-linked opp operon of E. coli was investigated using lambda placMu51-generated lac operon fusions. Synthesis of ..beta..-galactosidase by strains harboring oppA-lac, oppB-lac, and oppD-lac fusions occurred at a basal level when the fusion-containing strains were grown in minimal medium.

  4. Investigation of the cytotoxicity of eukaryotic and prokaryotic antimicrobial peptides in intestinal epithelial cells in vitro.

    PubMed

    Maher, Sam; McClean, Siobhán

    2006-04-28

    Antimicrobial peptides (AMPs) are a diverse group of proteinaceous compounds ranging in size, complexity and antimicrobial spectrum. The activity of AMPs against gut pathogens warrants the study of the interaction of AMPs with the mammalian gastrointestinal tract. In particular, the investigation of the in vitro cytotoxicity of these peptides is critical before they can be considered in clinical infections. The cytotoxicity of gallidermin, nisin A, natural magainin peptides, and melittin was investigated in two gastrointestinal cell models (HT29 and Caco-2) with the MTT conversion assay, neutral red dye uptake assay and compared with that of vancomycin. The hemolytic activities were also investigated in sheep erythrocytes and the effect of AMPs on paracellular permeability was examined by transepithelial resistance (TEER) and TEM. Gallidermin was the least cytotoxic AMP followed by nisin A, magainin I, magainin II and melittin. Melittin and nisin were the only peptides to result in significant hemolysis. However, while nisin caused hemolysis at concentrations which were 1000-fold higher than those required for antimicrobial activity, melittin was hemolytic at concentrations in the same order of magnitude as its antimicrobial activity. Melittin was the only AMP to affect paracellular permeability. Long term melittin treatment also resulted in loss of microvilli, an increase in cell debris and destruction of intestinal tight junctions and cell-cell adhesion. Gallidermin shows most promise as a therapeutic agent, with relatively low cytotoxicity and potent antimicrobial activities. Melittin, while showing little potential as an antimicrobial agent, may have potential in delivery of poorly bioavailable drugs.

  5. Cosecretion of peptide histidine methionine (PHM) and vasoactive intestinal peptide (VIP) in patients with VIP-producing tumors.

    PubMed

    Fahrenkrug, J; Pedersen, J H

    1986-01-01

    Regional specific antibodies and chromatography were used to analyze the concentration and molecular forms of vasoactive intestinal peptide (VIP) and peptide histidine methionine (PHM) in plasma from 39 patients with VIP-producing tumors. Plasma VIP concentrations ranged from 29 to 2550 pmol/l and the corresponding PHM immunoreactive values measured with C-terminally directed antibody were 42 to 2100 pmol/l which correlated closely with the VIP concentrations. N-terminal PHM concentrations were significantly higher than the C-terminal values ranging from 92 to 5850 pmol/l and correlated poorly with the corresponding VIP concentrations. Infusion experiments with PHM disclosed that the higher levels of N-terminal immunoreactivity could not be explained by slower metabolic clearance or by degradation to smaller N-terminal immunoreactive forms. N-terminally directed PHM antibody revealed, in addition to intact PHM, a larger immunoreactive form in patient plasma which constituted the major proportion of the total immunoreactivity. In conclusion, VIP and PHM are cosecreted from VIPomas and measurement of PHM, especially N-terminal immunoreactivity, may be useful in this condition.

  6. Epithelial cell extrusion during fluid transport in canine small intestine.

    PubMed

    Lee, J S

    1977-04-01

    Epithelial cell extrusion during fluid transport was studied under both in vitro and in vivo conditions. The rate of cell extrusion from the villus tips in vitro increased by about onefold in the villi with obstruction of lymph flow associated with the increase of lymph and tissue fluid pressure. When lymph pressure in the jejunal and ileal villi was increased to 6.4 +/- .2 and 12.3 +/- .5 mmHg, respectively, by injection of Ringer solution into the central lacteals, fluid leaked out of the villi and a shedding of epithelium occurred. Vigorous villus spasmodic contraction induced by cocaine or atropine also caused a shedding of epithelium. Cells always appeared in the lumen of intestine in vivo either during fluid absorption or secretion. A copious secretion of fluid, increase of cell loss, and congestion of blood in the villi occurred by the action of cholera toxin, MgSO4, and choline chloride. The rate of cell loss was highest during fluid secretion induced by an elevation of tissue fluid pressure such as at high venous pressure or during intra-arterial histamine infusion. It is thus concluded that elevated tissue fluid pressure is involved in epithelial cell extrusion during fluid transport.

  7. Intestinal transport of zinc and folic acid: a mutual inhibitory effect

    SciTech Connect

    Ghishan, F.K.; Said, H.M.; Wilson, P.C.; Murrell, J.E.; Greene, H.L.

    1986-02-01

    Recent observations suggest an inverse relationship between folic acid intake and zinc nutriture and indicate an interaction between folic acid and zinc at the intestinal level. To define that interaction, we designed in vivo and in vitro transport studies in which folic acid transport in the presence of zinc, as well as zinc transport in the presence of folic acid was examined. These studies show that zinc transport is significantly decreased when folate is present in the intestinal lumen. Similarly folic acid transport is significantly decreased with the presence of zinc. To determine whether this intestinal inhibition is secondary to zinc and folate-forming complexes, charcoal-binding studies were performed. These studies indicate that zinc and folate from complexes at pH 2.0, but that at pH 6.0, these complexes dissolve. Therefore, our studies suggest that under normal physiological conditions a mutual inhibition between folate and zinc exists at the site of intestinal transport.

  8. Transport mechanisms of nicotine across the human intestinal epithelial cell line Caco-2.

    PubMed

    Fukada, Atsuko; Saito, Hideyuki; Inui, Ken-Ichi

    2002-08-01

    Ulcerative colitis is a disease more commonly seen in nonsmokers. Because nicotine was postulated to be a beneficial component of tobacco smoke for ulcerative colitis, various formulations of nicotine have been developed to improve the local bioavailability within the gastrointestinal tissue. In the present study, to characterize the disposition of nicotine in the intestines, we investigated intestinal nicotine transport using Caco-2 cells. Nicotine was predominantly transported across Caco-2 cell monolayers in a unidirectional mode, corresponding to intestinal secretion, by pH-dependent specific transport systems. The specific uptake systems appear to be distinct from organic cation transporters and the transport system for tertiary amines, in terms of its substrate specificity and the pattern of the interaction. These transport systems could play a role in the intestinal accumulation of nicotine from plasma and could also be responsible for the topical delivery of nicotine for ulcerative colitis therapy. These findings could provide useful information for the design of effective nicotine delivery.

  9. The functional evaluation of human peptide/histidine transporter 1 (hPHT1) in transiently transfected COS-7 cells.

    PubMed

    Bhardwaj, Rajinder K; Herrera-Ruiz, Dea; Eltoukhy, Nesreen; Saad, Maha; Knipp, Gregory T

    2006-04-01

    Recently, the expression of the human peptide/histidine transporter (hPHT1, SLC15A4) mRNA was observed in the GI tract and in Caco-2 cells, suggesting that it may participate in the intestinal absorption of peptide-based agents. This study aims to elucidate the: (i) protein expression pattern of hPHT1 (SLC15A4) in human small intestine; (ii) cloning of the hPHT1 full-length sequence; (iii) functional characterization of hPHT1 in transiently transfected COS-7 cells. The expression of hPHT1 was measured using Western blot and immunohistochemical analysis. The hPHT1 full-sequence was amplified from BeWo cells, inserted into the pcDNA3.1-V5/His TOPO plasmid and transiently transfected into COS-7 cells to investigate the uptake kinetics of [3H]histidine and [3H]carnosine. Time, pH and sodium-dependent uptake studies were performed in mock (empty vector) and hPHT1-COS-7 cells. Results demonstrated hPHT1 protein expression in different intestinal regions. Histidine and carnosine uptake was linear in hPHT1-COS-7 cells over 15 min and was found to be pH-dependent. These substrates and valacyclovir showed significantly higher uptake at pH 5.0 in the hPHT1 transients when contrasted to the mock COS-7 cells, whereas glycylsarcosine uptake was significantly lower and unaffected by pH. Other di- and tripeptides also showed affinity for hPHT1. This study presents the initial functional characterization, the protein expression of the hPHT1 transporter and provides insight into a potentially different route for increasing peptide and peptide-based drug transport.

  10. Importance of Large Intestine in Regulating Bile Acids and Glucagon-Like Peptide-1 in Germ-Free Mice

    PubMed Central

    Selwyn, Felcy Pavithra; Csanaky, Iván L.; Zhang, Youcai

    2015-01-01

    It is known that 1) elevated serum bile acids (BAs) are associated with decreased body weight, 2) elevated glucagon-like peptide-1 (GLP-1) levels can decrease body weight, and 3) germ-free (GF) mice are resistant to diet-induced obesity. The purpose of this study was to test the hypothesis that a lack of intestinal microbiota results in more BAs in the body, resulting in increased BA-mediated transmembrane G protein–coupled receptor 5 (TGR5) signaling and increased serum GLP-1 as a mechanism of resistance of GF mice to diet-induced obesity. GF mice had 2- to 4-fold increased total BAs in the serum, liver, bile, and ileum. Fecal excretion of BAs was 63% less in GF mice. GF mice had decreased secondary BAs and increased taurine-conjugated BAs, as anticipated. Surprisingly, there was an increase in non–12α-OH BAs, namely, β-muricholic acid, ursodeoxycholic acid (UDCA), and their taurine conjugates, in GF mice. Further, in vitro experiments confirmed that UDCA is a primary BA in mice. There were minimal changes in the mRNA of farnesoid X receptor target genes in the ileum (Fibroblast growth factor 15, small heterodimer protein, and ileal bile acid–binding protein), in the liver (small heterodimer protein, liver receptor homolog-1, and cytochrome P450 7a1), and BA transporters (apical sodium dependent bile acid transporter, organic solute transporter α, and organic solute transporter β) in the ileum of GF mice. Surprisingly, there were marked increases in BA transporters in the large intestine. Increased GLP-1 levels and gallbladder size were observed in GF mice, suggesting activation of TGR5 signaling. In summary, the GF condition results in increased expression of BA transporters in the colon, resulting in 1) an increase in total BA concentrations in tissues, 2) a change in BA composition to favor an increase in non–12α-OH BAs, and 3) activation of TGR5 signaling with increased gallbladder size and GLP-1. PMID:26199423

  11. Functional characterization of folic acid transport in the intestine of the laying hen using the everted intestinal sac model.

    PubMed

    Tactacan, G B; Rodriguez-Lecompte, J C; Karmin, O; House, J D

    2011-01-01

    Absorption at the level of the intestine is likely a primary regulatory mechanism for the deposition of dietary supplemented folic acid into the chicken egg. Therefore, factors affecting the intestinal transport of folic acid in the laying hen may influence the level of egg folate concentrations. To this end, a series of experiments using intestinal everted sacs were conducted to characterize intestinal folic acid absorption processes in laying hens. Effects of naturally occurring folate derivatives (5-methyl and 10-formyltetrahydrofolate) as well as heme on folic acid absorption were also investigated. Folic acid absorption was measured based on the rate of uptake of (3)H-labeled folic acid in the everted sac from various segments of the small and large intestines. Folic acid concentration, incubation length, and pH condition were optimized before the performance of uptake experiments. The distribution profile of folic acid transport along the intestine was highest in the upper half of the small intestine. Maximum uptake rate (nmol·100 g tissue(-1)·min(-1)) was observed in the duodenum (20.6 ± 1.9) and jejunum (22.3 ± 2.0) and decreased significantly in the ileum (15.3 ± 1.1) and cecum (9.3 ± 0.9). Transport increased proportionately (P < 0.05) between 0.0001 and 0.1 µM folic acid. Above 0.1 µM, the slope of the regression line was not significantly different from zero (P < 0.137). Folic acid uptake in the jejunum showed a maximum rate of transport at pH 6.0, but was lowest at pH 7.5. The presence of 5-methyl and 10-formyltetrahydrofolate as well as heme impeded folic acid uptake, reducing intestinal folic acid absorption when added at concentrations ranging from 0 to 100 µM. Overall, these data indicated the presence of a folic acid transport system in the entire intestine of the laying hen. Uptake of folic acid in the cecum raises the likelihood of absorption of bacterial-derived folate.

  12. Glucose Transport into Everted Sacks of Intestine of Mice: A Model for the Study of Active Transport.

    ERIC Educational Resources Information Center

    Deyrup-Olsen, Ingrith; Linder, Alison R.

    1979-01-01

    Described is a laboratory procedure which uses the small intestines of mice as models for the transport of glucose and other solutes. Demonstrations are suitable for either introductory or advanced physiology courses. (RE)

  13. Glucose Transport into Everted Sacks of Intestine of Mice: A Model for the Study of Active Transport.

    ERIC Educational Resources Information Center

    Deyrup-Olsen, Ingrith; Linder, Alison R.

    1979-01-01

    Described is a laboratory procedure which uses the small intestines of mice as models for the transport of glucose and other solutes. Demonstrations are suitable for either introductory or advanced physiology courses. (RE)

  14. Effects of pig antibacterial peptides on growth performance and intestine mucosal immune of broiler chickens.

    PubMed

    Bao, H; She, R; Liu, T; Zhang, Y; Peng, K S; Luo, D; Yue, Z; Ding, Y; Hu, Y; Liu, W; Zhai, L

    2009-02-01

    Currently, substitutions for antibiotic growth promoters in animals are attracting interest. This study investigated the effects of pig antibacterial peptides (PABP) on growth performance and small intestine mucosal immune responses in broilers. Three hundred 1-d-old Arbor Acre male broiler chickens were randomly allocated to 5 groups with 60 birds per group. The groups were control group; PABP administered in drinking water at 20 and 30 mg/L of water; or PABP supplemented in feed at 150 and 200 mg/kg of diet. The birds were fed a corn-soybean based diet for 6 wk. Chickens were weighed weekly and killed after 42 d of feeding, and growth performance was measured. Samples of the duodenum and jejunum were collected. The villus height, mucosa thickness, alkaline phosphatase activity, and numbers of secreting IgA and goblet cells were evaluated. The PABP-treated groups had greater BW and average daily gain, greater height of villus and thickness of gut mucosa, greater activity of alkaline phosphatase, higher ratio of secreting IgA, and a greater number of goblet cells compared with the control group (P<0.05). In conclusion, PABP can improve the growth performance, increase the intestinal ability to absorb nutrients, and improve the mucosal immunity of the intestine.

  15. Interaction of Drug or Food with Drug Transporters in Intestine and Liver.

    PubMed

    Nakanishi, Takeo; Tamai, Ikumi

    2015-01-01

    Oral bioavailability (F) is determined as fraction of the drug dose absorbed through the gastrointestinal membranes (Fa), the unmetabolized fraction of the absorbed dose that passes through the gut into the portal blood (Fg), and the hepatic first pass availability (Fh), namely F is expressed as the product of Fa, Fg and Fh (F = Fa.Fg.Fh). Current evidence suggests that transporter proteins play a role in intestinal absorption and hepatobiliary clearance of drugs. Among those transporters, this review will focus on PEPT1 and OATP2B1 as influx transporter and p-glycoprotein (P-gp) and BCRP as efflux transporter in intestinal epithelial cells, and on OATP1B1 and 1B3 as influx transporter and MRP2 as efflux transporter in hepatocytes, respectively, because drug-drug (DDI) and -food (DFI) interactions on these transporter are considered to affect bioavailability of their substrate drugs. DDI and DFI may reduce systemic exposure to drug by blocking influx transporters in intestine, but increase it by modulating influx and efflux transporters in liver and efflux transporters in intestines. Namely, drug disposition and efficacy are likely affected by DDI and DFI, resulting in treatment failures or increase in adverse effect. Therefore, it is of significantly importance to understand precise mechanism of DDI and DFI. This review will present information about transporter-based DDI and DFI in the processes of intestinal absorption and hepatic clearance of drugs, and discuss about their clinical implication.

  16. Characteristic Analysis of Intestinal Transport in Enterocyte-Like Cells Differentiated from Human Induced Pluripotent Stem Cells.

    PubMed

    Kodama, Nao; Iwao, Takahiro; Katano, Takahiro; Ohta, Kinya; Yuasa, Hiroaki; Matsunaga, Tamihide

    2016-10-01

    We previously demonstrated that differentiated enterocytes from human induced pluripotent stem (iPS) cells exhibited drug-metabolizing activities and cytochrome P450 CYP3A4 inducibility. The aim of this study was to apply human iPS cell-derived enterocytes in pharmacokinetic studies by investigating the characteristics of drug transport into enterocyte-like cells. Human iPS cells cultured on feeder cells were differentiated into endodermal cells using activin A. These endodermal-like cells were then differentiated into intestinal stem cells by fibroblast growth factor 2. Finally, epidermal growth factor and small-molecule compounds induced the maturation of the intestinal stem cell-like cells. After differentiation, we performed transepithelial electrical resistance (TEER) measurements, immunofluorescence staining, and transport studies. TEER values increased in a time-dependent manner and reached approximately 100 Ω × cm(2) Efflux transport of Hoechst 33342, a substrate of breast cancer resistance protein (BCRP), was observed and inhibited by the BCRP inhibitor Ko143. The uptake of peptide transporter 1 substrate glycylsarcosine was also confirmed and suppressed when the temperature was lowered to 4°C. Using immunofluorescence staining, villin and Na(+)-K(+) ATPase were expressed. These results suggest that human iPS cell-derived enterocytes had loose tight junctions, polarity, as well as uptake and efflux transport functions. In addition, the rank order of apparent membrane permeability coefficient (Papp) values of these test compounds across the enterocyte-like cell membrane corresponded to the fraction absorbance (Fa) values. Therefore, differentiated enterocytes from human iPS cells may provide a useful comprehensive evaluation model of drug transport and metabolism in the small intestine.

  17. Nutrient availability, the microbiome, and intestinal transport during pregnancy.

    PubMed

    Astbury, Stuart; Mostyn, Alison; Symonds, Michael E; Bell, Rhonda C

    2015-11-01

    Adequate adaptation of the gastrointestinal tract is important during pregnancy to ensure that the increased metabolic demands by the developing fetus are met. These include changes in surface area mediated by villus hypertrophy and enhanced functional capacity of individual nutrient receptors, including those transporting glucose, fructose, leucine, and calcium. These processes are regulated either by the enhanced nutrient demand or are facilitated by changes in the secretion of pregnancy hormones. Our review also covers recent research into the microbiome, and how pregnancy could lead to microbial adaptations, which are beneficial to the mother, yet are also similar to those seen in the metabolic syndrome. The potential role of diet in modulating the microbiome during pregnancy, as well as the potential for the intestinal microbiota to induce pregnancy complications, are examined. Gaps in the current literature are highlighted, including those where only historical evidence is available, and we suggest areas that should be a priority for further research. In summary, although a significant degree of adaptation has been described, there are both well-established processes and more recent discoveries, such as changes within the maternal microbiome, that pose new questions as to how the gastrointestinal tract effectively adapts to pregnancy, especially in conjunction with maternal obesity.

  18. Transport of chitosan-DNA nanoparticles in human intestinal M-cell model versus normal intestinal enterocytes.

    PubMed

    Kadiyala, Irina; Loo, Yihua; Roy, Krishnendu; Rice, Janet; Leong, Kam W

    2010-01-31

    Oral vaccination is one of the most promising applications of polymeric nanoparticles. Using two different in vitro cellular models to partially reproduce the characteristics of intestinal enterocytes and M-cells, this study demonstrates that nanoparticle transport through the M-cell co-culture model is 5-fold that of the intestinal epithelial monolayer, with at least 80% of the chitosan-DNA nanoparticles uptaken in the first 30 min. Among the properties of nanoparticles studied, ligand decoration has the most dramatic effect on the transcytosis rate: transferrin modification enhances transport through both models by 3- to 5-fold. The stability of the nanoparticles also affects transport kinetics. Factors which de-stabilize the nanoparticles, such as low charge (N/P) ratio and addition of serum, result in aggregation and in turn decreases transport efficiency. Of these stability factors, luminal pH is of great interest as an increase in pH from 5.5 to 6.4 and 7.4 leads to a 3- and 10-fold drop in nanoparticle transport, respectively. Since soluble chitosan can act as an enhancer to increase paracellular transport by up to 60%, this decrease is partially attributed to the soluble chitosan precipitating near neutral pH. The implication that chitosan-DNA nanoparticles are more stable in the upper regions of the small intestine suggests that higher uptake rates may occur in the duodenum compared to the ileum and the colon. Copyright 2009 Elsevier B.V. All rights reserved.

  19. Vasoactive intestinal peptide prevents lung injury due to xanthine/xanthine oxidase.

    PubMed

    Berisha, H; Foda, H; Sakakibara, H; Trotz, M; Pakbaz, H; Said, S I

    1990-08-01

    Reactive oxygen species mediate injury and inflammation in many tissues. The addition of xanthine and xanthine oxidase to perfused rat lungs led to increases in peak airway pressure and perfusion pressure, pulmonary edema, and increased protein content in bronchoalveolar lavage fluid. Treatment with 1-10 micrograms.kg-1.min-1 of vasoactive intestinal peptide (VIP), a widely distributed neuropeptide, markedly reduced or totally prevented all signs of injury. Simultaneously, VIP also diminished or abolished the associated generation of arachidonate products. Similar protection was provided by catalase (100 micrograms/ml) but not by the VIP-related peptides secretin or glucagon. The pulmonary vasodilator papaverine (0.15 mg/ml) was also ineffective. Injured lungs that were not treated with VIP released large amounts of this peptide in the perfusate. The results indicate that VIP has potent protective activity against injury triggered by xanthine/xanthine oxidase and may be a physiological modulator of inflammatory tissue damage associated with toxic oxygen metabolites.

  20. Glucagon-like peptide-2 and mouse intestinal adaptation to a high-fat diet.

    PubMed

    Baldassano, Sara; Amato, Antonella; Cappello, Francesco; Rappa, Francesca; Mulè, Flavia

    2013-04-01

    Endogenous glucagon-like peptide-2 (GLP2) is a key mediator of refeeding-induced and resection-induced intestinal adaptive growth. This study investigated the potential role of GLP2 in mediating the mucosal responses to a chronic high-fat diet (HFD). In this view, the murine small intestine adaptive response to a HFD was analyzed and a possible involvement of endogenous GLP2 was verified using GLP2 (3-33) as GLP2 receptor (GLP2R) antagonist. In comparison with animals fed a standard diet, mice fed a HFD for 14 weeks exhibited an increase in crypt-villus mean height (duodenum, 27.5±3.0%; jejunum, 36.5±2.9%; P<0.01), in the cell number per villus (duodenum, 28.4±2.2%; jejunum, 32.0±2.9%; P<0.01), and in Ki67-positive cell number per crypt. No change in the percent of caspase-3-positive cell in the villus-crypt was observed. The chronic exposure to a HFD also caused a significant increase in GLP2 plasma levels and in GLP2R intestinal expression. Daily administration of GLP2 (3-33) (30-60  ng) for 4 weeks did not modify the crypt-villus height in control mice. In HFD-fed mice, chronic treatment with GLP2 (3-33) reduced the increase in crypt-villus height and in the cell number per villus through reduction of cell proliferation and increase in apoptosis. This study provides the first experimental evidence for a role of endogenous GLP2 in the intestinal adaptation to HFD in obese mice and for a dysregulation of the GLP2/GLP2R system after a prolonged HFD.

  1. Listeria monocytogenes Inhibits Serotonin Transporter in Human Intestinal Caco-2 Cells.

    PubMed

    Latorre, E; Pradilla, A; Chueca, B; Pagán, R; Layunta, E; Alcalde, A I; Mesonero, J E

    2016-10-01

    Listeria monocytogenes is a Gram-positive bacterium that can cause a serious infection. Intestinal microorganisms have been demonstrated to contribute to intestinal physiology not only through immunological responses but also by modulating the intestinal serotonergic system. Serotonin (5-HT) is a neuromodulator that is synthesized in the intestinal epithelium and regulates the whole intestinal physiology. The serotonin transporter (SERT), located in enterocytes, controls intestinal 5-HT availability and therefore serotonin's effects. Infections caused by L. monocytogenes are well described as being due to the invasion of intestinal epithelial cells; however, the effect of L. monocytogenes on the intestinal epithelium remains unknown. The main aim of this work, therefore, was to study the effect of L. monocytogenes on SERT. Caco2/TC7 cell line was used as an enterocyte-like in vitro model, and SERT functional and molecular expression assays were performed. Our results demonstrate that living L. monocytogenes inhibits serotonin uptake by reducing SERT expression at the brush border membrane. However, neither inactivated L. monocytogenes nor soluble metabolites were able to affect SERT. The results also demonstrate that L. monocytogenes yields TLR2 and TLR10 transcriptional changes in intestinal epithelial cells and suggest that TLR10 is potentially involved in the inhibitory effect observed on SERT. Therefore, L. monocytogenes, through TLR10-mediated SERT inhibition, may induce increased intestinal serotonin availability and potentially contributing to intestinal physiological changes and the initiation of the inflammatory response.

  2. Intestinal transport of gentamicin with a novel, glycosteroid drug transport agent

    NASA Technical Reports Server (NTRS)

    Axelrod, H. R.; Kim, J. S.; Longley, C. B.; Lipka, E.; Amidon, G. L.; Kakarla, R.; Hui, Y. W.; Weber, S. J.; Choe, S.; Sofia, M. J.

    1998-01-01

    PURPOSE: The objective was to investigate the ability of a glycosteroid (TC002) to increase the oral bioavailability of gentamicin. METHODS: Admixtures of gentamicin and TC002 were administered to the rat ileum by injection and to dogs by ileal or jejunal externalized ports, or PO. Bioavailability of gentamicin was determined by HPLC. 3H-TC002 was injected via externalized cannulas into rat ileum or jejunum, or PO and its distribution and elimination was determined. The metabolism of TC002 in rats was evaluated by solid phase extraction and HPLC analysis of plasma, urine and feces following oral or intestinal administration. RESULTS: The bioavailability of gentamicin was substantially increased in the presence of TC002 in both rats and dogs. The level of absorption was dependent on the concentration of TC002 and site of administration. Greatest absorption occurred following ileal orjejunal administration. TC002 was significantly more efficacious than sodium taurocholate, but similar in cytotoxicity. TC002 remained primarily in the GI tract following oral or intestinal administration and cleared rapidly from the body. It was only partly metabolized in the GI tract, but was rapidly and completely converted to its metabolite in plasma and urine. CONCLUSIONS: TC002 shows promise as a new drug transport agent for promoting intestinal absorption of polar molecules such as gentamicin.

  3. Intestinal transport of gentamicin with a novel, glycosteroid drug transport agent

    NASA Technical Reports Server (NTRS)

    Axelrod, H. R.; Kim, J. S.; Longley, C. B.; Lipka, E.; Amidon, G. L.; Kakarla, R.; Hui, Y. W.; Weber, S. J.; Choe, S.; Sofia, M. J.

    1998-01-01

    PURPOSE: The objective was to investigate the ability of a glycosteroid (TC002) to increase the oral bioavailability of gentamicin. METHODS: Admixtures of gentamicin and TC002 were administered to the rat ileum by injection and to dogs by ileal or jejunal externalized ports, or PO. Bioavailability of gentamicin was determined by HPLC. 3H-TC002 was injected via externalized cannulas into rat ileum or jejunum, or PO and its distribution and elimination was determined. The metabolism of TC002 in rats was evaluated by solid phase extraction and HPLC analysis of plasma, urine and feces following oral or intestinal administration. RESULTS: The bioavailability of gentamicin was substantially increased in the presence of TC002 in both rats and dogs. The level of absorption was dependent on the concentration of TC002 and site of administration. Greatest absorption occurred following ileal orjejunal administration. TC002 was significantly more efficacious than sodium taurocholate, but similar in cytotoxicity. TC002 remained primarily in the GI tract following oral or intestinal administration and cleared rapidly from the body. It was only partly metabolized in the GI tract, but was rapidly and completely converted to its metabolite in plasma and urine. CONCLUSIONS: TC002 shows promise as a new drug transport agent for promoting intestinal absorption of polar molecules such as gentamicin.

  4. Molecular forms of peptide histidine isoleucine-like immunoreactivity in the gastrointestinal tract. Nonequimolar levels of peptide histidine isoleucine and vasoactive intestinal peptide in the stomach explained by the presence of a big peptide histidine isoleucine-like molecule.

    PubMed

    Yiangou, Y; Christofides, N D; Blank, M A; Yanaihara, N; Tatemoto, K; Bishop, A E; Polak, J M; Bloom, S R

    1985-09-01

    Regional specific antibodies and chromatography were used to analyze the distributions and molecular forms of peptide histidine isoleucine (PHI) and vasoactive intestinal peptide (VIP) in the porcine intestine. Both peptides were present along the entire length of the intestine, the highest concentrations occurring in the colon. Concentrations of PHI immunoreactivity, measured with three different antisera, and VIP immunoreactivity were approximately equal in all parts of the gastrointestinal tract except in the stomach. In the stomach, the concentration of PHI immunoreactivity, measured with the N-terminally directed antibody R8403, although equal to the corresponding VIP concentration, was two to four times higher than the PHI immunoreactivity detected with the two C-terminally directed PHI antisera T33 and T41. Chromatographic analysis on Sephadex G-50 superfine of gastric extracts revealed only one VIP immunoreactive peak that eluted in the same position as the porcine VIP standard, at Kav 0.53. A PHI immunoreactive peak was also detected with the C-terminally directed PHI antisera in the same position as porcine PHI standard. However, with the N-terminally directed PHI antiserum R8403, an additional PHI immunoreactive peak was detected in gastric extracts constituting the predominant form present, and this peak eluted earlier at Kav 0.37. The PHI immunoreactive material that eluted earlier was present in the rest of the intestine in only small amounts. As VIP and PHI are believed to be derived from a common precursor, it is suggested that in the stomach the posttranslational enzymic processing of the precursor is different from that in the other parts of the intestine.

  5. Intestine.

    PubMed

    Smith, J M; Skeans, M A; Horslen, S P; Edwards, E B; Harper, A M; Snyder, J J; Israni, A K; Kasiske, B L

    2016-01-01

    Intestine and intestine-liver transplant plays an important role in the treatment of intestinal failure, despite decreased morbidity associated with parenteral nutrition. In 2014, 210 new patients were added to the intestine transplant waiting list. Among prevalent patients on the list at the end of 2014, 65% were waiting for an intestine transplant and 35% were waiting for an intestine-liver transplant. The pretransplant mortality rate decreased dramatically over time for all age groups. Pretransplant mortality was highest for adult candidates, at 22.1 per 100 waitlist years compared with less than 3 per 100 waitlist years for pediatric candidates, and notably higher for candidates for intestine-liver transplant than for candidates for intestine transplant without a liver. Numbers of intestine transplants without a liver increased from a low of 51 in 2013 to 67 in 2014. Intestine-liver transplants increased from a low of 44 in 2012 to 72 in 2014. Short-gut syndrome (congenital and other) was the main cause of disease leading to both intestine and intestine-liver transplant. Graft survival improved over the past decade. Patient survival was lowest for adult intestine-liver recipients and highest for pediatric intestine recipients. © Copyright 2015 The American Society of Transplantation and the American Society of Transplant Surgeons.

  6. Receptors for vasoactive intestinal peptide in rat anterior pituitary glands: Localization of binding to lactotropes

    SciTech Connect

    Wanke, I.E.; Rorstad, O.P. )

    1990-04-01

    Vasoactive intestinal peptide (VIP) has been implicated as a physiological PRL-releasing factor; however, characterization of VIP receptors on normal pituitaries using radioligand-binding methods has been problematic. In this study we demonstrated specific receptors for VIP in anterior pituitary glands of female rats using HPLC-purified monoiodinated (Tyr(125I)10)VIP. Binding of VIP was reversible, saturable to receptor and radioligand, regulated by guanine nucleotides, and dependent on time and temperature. Scatchard analysis of competitive binding studies indicated high and low affinity binding sites, with equilibrium dissociation constants (Kd) of 0.19 +/- 0.03 and 28 +/- 16 nM, respectively. The corresponding maximum numbers of binding sites were 158 +/- 34 fmol/mg and 11.7 +/- 6.9 pmol/mg. Binding was specific, as peptides with structural homology to VIP were less than 100th as potent as VIP. The rank order of potency of the peptides tested was VIP greater than rat (r) peptide histidine isoleucine = human (h) PHI greater than rGRF greater than bovine GRF = porcine PHI = VIP-(10-28) greater than hGRF greater than secretin greater than apamin greater than glucagon. Radioligand binding was associated primarily with lactotrope-enriched fractions prepared by unit gravity sedimentation of dispersed anterior pituitary cells. VIP stimulated PRL release from cultured rat anterior pituitary cells, with an ED50 of 1 nM. These results, comprising the first identification of specific VIP receptors in normal rat anterior pituitary tissue using radioligand-binding methods, provide additional support for a biological role of VIP in lactotrope function.

  7. Involvement of Concentrative Nucleoside Transporter 1 in Intestinal Absorption of Trifluridine Using Human Small Intestinal Epithelial Cells.

    PubMed

    Takahashi, Koichi; Yoshisue, Kunihiro; Chiba, Masato; Nakanishi, Takeo; Tamai, Ikumi

    2015-09-01

    TAS-102, which is effective for refractory metastatic colorectal cancer, is a combination drug of anticancer trifluridine (FTD; which is derived from pyrimidine nucleoside) and FTD-metabolizing enzyme inhibitor tipiracil hydrochloride (TPI) at a molecular ratio of 1:0.5. To evaluate the intestinal absorption mechanism of FTD, the uptake and transcellular transport of FTD by human small intestinal epithelial cell (HIEC) monolayer as a model of human intestinal epithelial cells was investigated. The uptake and membrane permeability of FTD by HIEC monolayers were saturable, Na(+) -dependent, and inhibited by nucleosides. These transport characteristics are mostly comparable with those of concentrative nucleoside transporters (CNTs). Moreover, the uptake of FTD by CNT1-expressing Xenopus oocytes was the highest among human CNT transporters. The obtained Km and Vmax values of FTD by CNT1 were 69.0 μM and 516 pmol/oocyte/30 min, respectively. The transcellular transport of FTD by Caco-2 cells, where CNT1 is heterologously expressed, from apical to basolateral side was greater than that by Mock cells. In conclusion, these results demonstrated that FTD exhibits high oral absorption by the contribution of human CNT1. © 2015 Wiley Periodicals, Inc. and the American Pharmacists Association.

  8. Bile acids induce glucagon-like peptide 2 secretion with limited effects on intestinal adaptation in early weaned pigs

    USDA-ARS?s Scientific Manuscript database

    Early weaning is a stressful event characterized by a transient period of intestinal atrophy that may be mediated by reduced secretion of glucagon-like peptide (GLP) 2. We tested whether enterally fed bile acids or plant sterols could increase nutrient-dependent GLP-2 secretion and improve intestina...

  9. Glucagon-like peptide-2 (GLP-2) increases small intestinal blood flow and mucosal growth in ruminating calves

    USDA-ARS?s Scientific Manuscript database

    Glucagon-like peptide-2 (GLP-2), increases small intestinal mass and blood flow in non-ruminants, but its effect in ruminants is unknown. Eight Holstein calves with an ultrasonic flow probe around the superior mesenteric artery (SMA), and catheters in the carotid artery and mesenteric vein, were pa...

  10. Microbiota/host crosstalk biomarkers: regulatory response of human intestinal dendritic cells exposed to Lactobacillus extracellular encrypted peptide.

    PubMed

    Bernardo, David; Sánchez, Borja; Al-Hassi, Hafid O; Mann, Elizabeth R; Urdaci, María C; Knight, Stella C; Margolles, Abelardo

    2012-01-01

    The human gastrointestinal tract is exposed to a huge variety of microorganisms, either commensal or pathogenic; at this site, a balance between immunity and immune tolerance is required. Intestinal dendritic cells (DCs) control the mechanisms of immune response/tolerance in the gut. In this paper we have identified a peptide (STp) secreted by Lactobacillus plantarum, characterized by the abundance of serine and threonine residues within its sequence. STp is encoded in one of the main extracellular proteins produced by such species, which includes some probiotic strains, and lacks cleavage sites for the major intestinal proteases. When studied in vitro, STp expanded the ongoing production of regulatory IL-10 in human intestinal DCs from healthy controls. STp-primed DC induced an immunoregulatory cytokine profile and skin-homing profile on stimulated T-cells. Our data suggest that some of the molecular dialogue between intestinal bacteria and DCs may be mediated by immunomodulatory peptides, encoded in larger extracellular proteins, secreted by commensal bacteria. These peptides may be used for the development of nutraceutical products for patients with IBD. In addition, this kind of peptides seem to be absent in the gut of inflammatory bowel disease patients, suggesting a potential role as biomarker of gut homeostasis.

  11. Microbiota/Host Crosstalk Biomarkers: Regulatory Response of Human Intestinal Dendritic Cells Exposed to Lactobacillus Extracellular Encrypted Peptide

    PubMed Central

    Al-Hassi, Hafid O.; Mann, Elizabeth R.; Urdaci, María C.; Knight, Stella C.; Margolles, Abelardo

    2012-01-01

    The human gastrointestinal tract is exposed to a huge variety of microorganisms, either commensal or pathogenic; at this site, a balance between immunity and immune tolerance is required. Intestinal dendritic cells (DCs) control the mechanisms of immune response/tolerance in the gut. In this paper we have identified a peptide (STp) secreted by Lactobacillus plantarum, characterized by the abundance of serine and threonine residues within its sequence. STp is encoded in one of the main extracellular proteins produced by such species, which includes some probiotic strains, and lacks cleavage sites for the major intestinal proteases. When studied in vitro, STp expanded the ongoing production of regulatory IL-10 in human intestinal DCs from healthy controls. STp-primed DC induced an immunoregulatory cytokine profile and skin-homing profile on stimulated T-cells. Our data suggest that some of the molecular dialogue between intestinal bacteria and DCs may be mediated by immunomodulatory peptides, encoded in larger extracellular proteins, secreted by commensal bacteria. These peptides may be used for the development of nutraceutical products for patients with IBD. In addition, this kind of peptides seem to be absent in the gut of inflammatory bowel disease patients, suggesting a potential role as biomarker of gut homeostasis. PMID:22606249

  12. Calcium uptake by intestinal brush border membrane vesicles. Comparison with in vivo calcium transport.

    PubMed Central

    Schedl, H P; Wilson, H D

    1985-01-01

    In prior studies, we examined kinetics of steady state in vivo transepithelial calcium transport in rat and hamster. The present studies related calcium uptake by the brush border to in vivo transport. We measured calcium uptake by brush border membrane vesicles from the two species. In the rat, our prior in vivo studies had shown that (a) calcium transport was mediated, (b) no nonmediated component was detectable, and (c) Vmax was 2.5 times greater in proximal than distal small intestine. In brush border membrane vesicles from the rat, Vmax for the saturable component of calcium uptake was again 2.5 times greater in proximal than distal intestine. Contrasting with in vivo studies, a major nonsaturable component was present in vesicles from proximal and distal small intestine. In the hamster, our previous in vivo studies had shown (1) both mediated and nonmediated components of calcium transport, (2) greater nonmediated transport in proximal than distal small intestines, and (3) Vmax for calcium transport twice as great in distal as in proximal small intestine. In the present study with brush border membrane vesicles from hamster, Vmax for saturable calcium transport was again twice as great in distal as in proximal small intestine. However, nonsaturable calcium transport rates relative to saturable rates were much greater with vesicles than in in vivo studies, and were greater in vesicles from distal than proximal small intestine. Since rates of saturable calcium uptake by brush border membrane vesicles parallel corresponding in vivo mediated transport rates, we conclude that the segmental rates of calcium transport in rat and hamster could be determined by brush border function. PMID:2997294

  13. Dopaminergic modulation of adenylate cyclase stimulation by vasoactive intestinal peptide in anterior pituitary.

    PubMed Central

    Onali, P; Schwartz, J P; Costa, E

    1981-01-01

    The activation of adenylate cyclase [ATP pyrophosphate-lyase (cyclizing), EC 4.6.1.1] by vasoactive intestinal peptide (VIP) was used as a model to investigate the molecular mechanisms triggered by the occupancy of dopamine recognition sites in rat anterior pituitary. Dopamine failed to change the basal enzyme activity, but it inhibited the stimulation of adenylate cyclase elicited by VIP. Apomorphine, 2-amino-6,7-dihydroxy-1,2,3,4-tetrahydronaphthalene, and 2-bromo-alpha-ergocryptine mimicked the effect of dopamine, whereas (-)-sulpiride and and classical neuroleptics antagonized it. Dopamine failed to modulate the activation of pituitary adenylate cyclase by prostaglandin E1, which does not increase prolactin secretion. From these results we infer that stimulation of D-2 (dopamine) receptors may affect pituitary secretion by inhibiting the activation of anterior pituitary adenylate cyclase by VIP or other secretagogues. PMID:6171819

  14. The effects of vasoactive intestinal peptide on adrenal steroid hormone secretion

    SciTech Connect

    Cunningham, L.A.

    1988-01-01

    Vasoactive intestinal peptide (VIP)-immunoreactive nerve fibers have been demonstrated in the rat adrenal cortex in close association with zona glomerulosa cells. We have studied the effects of VIP on steroid hormone secretion from the outer zones of the normal rat adrenal cortex. Intact capsule-glomerulosa preparations, consisting of the capsule, zona glomerulosa, and a small portion of the zona fasciculata were perifused in vitro. The secretory responsiveness was assessed by measuring aldosterone and corticosterone release following stimulation with the physiological secretagogues ACTH and angiotensin II. The distribution of adrenal VIP receptors was assessed by in vitro autoradiography of {sup 125}I-VIP binding. {sup 125}I-VIP (0.75 and 2.0 nM) binding was concentrated in the capsule and zone glomerulosa, coincident with the distribution of VIP nerve fibers which aborize extensively in this region. The specificity of this binding was demonstrated using unlabelled VIP, ACTH and angiotensin II.

  15. Clostridium difficile suppresses colonic vasoactive intestinal peptide associated with altered motility.

    PubMed

    Nassif, A; Longo, W E; Sexe, R; Stratton, M; Standeven, J; Vernava, A M; Kaminski, D L

    1995-01-01

    We investigated whether Clostridium difficile toxin alters colonic tissue levels of vasoactive intestinal peptide (VIP) at the expense of changes in colonic motility in the isolated perfused rabbit left colon. Colonic inflammation was induced by the intracolonic administration of 10(-8) M C. difflcile toxin. Strain gauge transducers were sewn onto the serosal surface of the colon to evaluate colonic motility. C. difflcile administration produced histologic changes consistent with epithelial damage. This was associated with an increased production of prostaglandin E(2) and thromboxane B(2). Tissue levels of VIP but not substance P were significantly reduced. This was associated with an increased number of contractions per minute and an average force of each colonic contraction. These results suggest that tissue levels of VIP are suppressed by C. difflcile and may participate in colonic dysmotility during active inflammation.

  16. Clostridium difficile suppresses colonic vasoactive intestinal peptide associated with altered motility

    PubMed Central

    Nassif, A.; Sexe, R.; Stratton, M.; Standeven, J.; Vernava, A. M.; Kaminski, D. L.

    1995-01-01

    We investigated whether Clostridium difficile toxin alters colonic tissue levels of vasoactive intestinal peptide (VIP) at the expense of changes in colonic motility in the isolated perfused rabbit left colon. Colonic inflammation was induced by the intracolonic administration of 10−8 M C. difflcile toxin. Strain gauge transducers were sewn onto the serosal surface of the colon to evaluate colonic motility. C. difflcile administration produced histologic changes consistent with epithelial damage. This was associated with an increased production of prostaglandin E2 and thromboxane B2. Tissue levels of VIP but not substance P were significantly reduced. This was associated with an increased number of contractions per minute and an average force of each colonic contraction. These results suggest that tissue levels of VIP are suppressed by C. difflcile and may participate in colonic dysmotility during active inflammation. PMID:18475679

  17. Increased egg production in juvenile turkey hens after active immunization with vasoactive intestinal peptide.

    PubMed

    Caldwell, S R; Johnson, A F; Yule, T D; Grimes, J L; Ficken, M; Christensen, V L

    1999-06-01

    Juvenile turkey hens were actively immunized against vasoactive intestinal peptide (VIP) prior to photostimulation to evaluate its effect on enhancing egg production. VIP antibody titers were generated in the VIP immunized hens and a greater rate of egg production per hen was observed compared to controls. In addition, the first egg laying cycle was extended for an additional 7 wk without a significant decline in egg production. Over a 27-wk period, 116 settable eggs per hen were produced from the VIP immunized hens as compared to 102 and 90 eggs for the keyhole limpet hemocyanin and saline control groups, respectively. Based on the increased egg production and the extension of the first egg laying cycle, this experiment demonstrates that VIP immunization of turkey hens is potentially economically relevant.

  18. Vasoactive intestinal peptide (VIP) induces malignant transformation of the human prostate epithelial cell line RWPE-1.

    PubMed

    Fernández-Martínez, Ana B; Bajo, Ana M; Isabel Arenas, M; Sánchez-Chapado, Manuel; Prieto, Juan C; Carmena, María J

    2010-12-18

    The carcinogenic potential of vasoactive intestinal peptide (VIP) was analyzed in non-tumor human prostate epithelial cells (RWPE-1) and in vivo xenografts. VIP induced morphological changes and a migratory phenotype consistent with stimulation of expression/activity of metalloproteinases MMP-2 and MMP-9, decreased E-cadherin-mediated cell-cell adhesion, and increased cell motility. VIP increased cyclin D1 expression and cell proliferation that was blocked after VPAC(1)-receptor siRNA transfection. Similar effects were seen in RWPE-1 tumors developed by subcutaneous injection of VIP-treated cells in athymic nude mice. VIP acts as a cytokine in RWPE-1 cell transformation conceivably through epithelial-mesenchymal transition (EMT), reinforcing VIP role in prostate tumorigenesis.

  19. The effect of atrial natriuretic peptide infusion on intestinal injury in septic shock

    PubMed Central

    Elbaradey, Ghada F.; Elshmaa, Nagat Sayed; Hodeib, Hossam

    2016-01-01

    Background and Aims: The aim of this study is to assess the effect of atrial natriuretic peptide (ANP) on intestinal ischemia-reperfusion injury in septic shock. Material and Methods: A prospective randomized controlled, observer-blinded study was carried out in surgical Intensive Care Unit (ICU), University Hospital. Forty adult patients in septic shock were randomly divided into two groups, control group (Group C) received normal saline and ANP group (Group A) patients received ANP in the form of 1.5 mg vial added to 250 ml solvent in plastic bag (1 ml = 6 micg) given at 2 mcg/kg intravenous bolus over 1 min followed by 0.01 mcg/kg/min for 24 h. The primary outcome measurements were blood marker of intestinal hypoperfusion in form of intestinal fatty acid binding protein (I-FABP), malondialdehyde (MDA), myloperoxidase enzyme activity (MPO), protein carbonyl (PC), and glutathione peroxidase activity (GPA) measured before start of ANP infusion, 6 h, 12 h, and 24 h after start of infusion. The secondary outcome measurements were the duration of noradrenaline infusion, duration of ICU stay, hospital mortality rate, and complications related to ANP. Results: In comparison with Group C, Group A showed a significant decrease (P < 0.05) in serum level of MPO, MDA, PC, and I-FABP, with a significant increase (P < 0.05) in serum level of GPA, 6 h, 12 h, and 24 h after the start of ANP infusion. There was significant decrease (P < 0.05) in mean duration of noradrenaline infusion, the length of ICU stay and mortality rate in Group A in comparison with Group C. In Group A, seven patients had mean arterial blood pressure < 65 mmHg but respond to volume resuscitation, three patients serum sodium was 125–130 mmol/L. Conclusion: In cases of septic shock, concomitant administration of ANP with noradrenaline may have a protective effect against intestinal injury through a decrease in the level of intestinal hypoperfusion owing to its anti-inflammatory and antioxidant effect. PMID

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

    PubMed Central

    Roche, Marjolaine; Kemp, Francis W; Agrawal, Amit; Attanasio, Alicia; Neti, Prasad VSV; Howell, Roger W; Ferraris, Ronaldo P

    2010-01-01

    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 of intestinal nutrient absorption. We previously showed that 5 – 14 d 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 in antioxidant enzymes are, respectively, epithelial cells responsible for nutrient absorption and the crypt region comprised mainly of 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. PMID:20970494

  1. Evaluation of the intestinal toxicity and transport of xenobiotics utilizing precision-cut slices.

    PubMed

    Niu, Xiaoyu; de Graaf, Inge A M; Groothuis, Geny M M

    2013-01-01

    1.The precision-cut intestinal slice (PCIS) technology is a relatively new addition to the battery of in vitro assays for evaluation of xenobiotic toxicity, metabolism, and transport. 2.The intestine is an important target for drug-induced toxicity due to its high exposure after oral administration. Therefore, the prediction of drug-induced intestinal side effects remains a significant safety issue in pharmaceutical development. Although animal experiments have been proven useful, species differences and the requirement for reduction of animal use warrant the development of in vitro methods which can apply human tissue. 3.The enterocytes lining the villi express high activities of enzymes and transporters involved in drug disposition. They vary highly in activities: along the length of the intestine and along the villi, gradients of expression levels of the enzymes and proteins exist, which necessitates an in vitro model that can reflect the different regions of the intestine. 4.In this chapter, the application of PCIS in studies on transport and toxicity of xenobiotics is reviewed. PCIS can be prepared from each region of the intestine and from various species in a similar manner, and the results published so far indicate that they represent a promising model to evaluate intestinal toxicity and transport.

  2. Sodium recirculation and isotonic transport in toad small intestine.

    PubMed

    Nedergaard, S; Larsen, E H; Ussing, H H

    1999-04-01

    Isolated small intestine of toad (Bufo bufo) was mounted on glass tubes for perfusion studies with oxygenated amphibian Ringer's solution containing glucose and acetate. Under open-circuit conditions (Vt = -3.9 +/- 1.8 mV, N = 14) the preparation generated a net influx of 134Cs+. The time course of unidirectional 134Cs+-fluxes was mono-exponential with similar rate constants for influx and outflux when measured in the same preparation. The flux-ratio was time invariant from the beginning of appearance of the tracers to steady state was achieved. Thus, just a single pathway, the paracellular pathway, is available for transepithelial transport of Cs+. From the ratio of unidirectional Cs+-fluxes the paracellular force was calculated to be, 18.2 +/- 1.5 mV (N = 6), which is directed against the small transepithelial potential difference. The paracellular netflux of cesium ions, therefore, is caused by solvent drag. The flux of 134Cs+ entering and trapped by the cells was of a magnitude similar to that passing the paracellular route. Therefore, independent of the convective flux of 134Cs+, every second 134Cs+ ion flowing into the lateral space was pumped into the cells rather than proceeding, via the low resistance pathway, to the serosal bath. It is thus indicated that the paracellular convective flow of 134Cs+ is driven by lateral Na+/K+-pumps. Transepithelial unidirectional 42K+ fluxes did not reach steady state within an observation period of 70 min, indicating that components of the fluxes in both directions pass the large cellular pool of potassium ions. The ratio of unidirectional 24Na+ fluxes was time-variant and declined from an initial value of 3.66 +/- 0.34 to a significantly smaller steady-state value of 2.57 +/- 0.26 (P < 0.001, N = 5 paired observations), indicating that sodium ions pass the epithelium both via the paracellular and the cellular pathway. Quantitatively, the larger ratio of paracellular Na+ fluxes, as compared to that of paracellular Cs

  3. Adaptations of intestinal nutrient transport to chronic caloric restriction in mice.

    PubMed

    Casirola, D M; Rifkin, B; Tsai, W; Ferraris, R P

    1996-07-01

    Lifelong caloric restriction increases median and maximum life span and retards the aging process in many organ systems of rodents. Because the small intestine absorbs a reduced amount of nutrients each day, does lifelong caloric restriction induce adaptations in intestinal nutrient transport? We initially compared intestinal transport of sugars and amino acids between 24-mo-old mice allowed free access to food [ad libitum (AL)] and those provided a calorically restricted [40% less than ad libitum (CR)] diet since 3 mo of age. We found that CR mice had significantly greater transport rates for D-glucose, D-fructose, and several amino acids and had significantly lower villus heights. Total intestinal absorptive capacities for D-glucose, D-fructose, and L-proline were each 40-50% greater in CR mice; absorptive capacity normalized to metabolic mass (body weight 0.75) was approximately 80% greater in CR mice. Comparison of uptakes in aged AL and CR mice with previously published results in young AL mice suggests that caloric restriction delays age-related decreases in nutrient transport. In contrast to published studies in hibernation and starvation, chronic caloric restriction enhances not only uptake per milligram but also uptake per centimeter. We then switched 24-mo-old AL mice to a calorie-restricted diet for 1 mo and found that short-term caloric restriction has no effect on intestinal nutrient transport, intestinal mass, and total absorptive capacity. Thus chronic but not short-term caloric restriction increases intestinal nutrient transport rates in aged mice, and the main mechanism underlying these increases is enhanced transport rates per unit intestinal tissue weight.

  4. Medicinal Plants Qua Glucagon-Like Peptide-1 Secretagogue via Intestinal Nutrient Sensors

    PubMed Central

    Kim, Ki-Suk; Jang, Hyeung-Jin

    2015-01-01

    Glucagon-like peptide-1 (GLP-1) participates in glucose homeostasis and feeding behavior. Because GLP-1 is rapidly inactivated by the enzymatic cleavage of dipeptidyl peptidase-4 (DPP4) long-acting GLP-1 analogues, for example, exenatide and DPP4 inhibitors, for example, liraglutide, have been developed as therapeutics for type 2 diabetes mellitus (T2DM). However, the inefficient clinical performance and the incidence of side effects reported on the existing therapeutics for T2DM have led to the development of a novel therapeutic strategy to stimulate endogenous GLP-1 secretion from enteroendocrine L cells. Since the GLP-1 secretion of enteroendocrine L cells depends on the luminal nutrient constituents, the intestinal nutrient sensors involved in GLP-1 secretion have been investigated. In particular, nutrient sensors for tastants, cannabinoids, and bile acids are able to recognize the nonnutritional chemical compounds, which are abundant in medicinal plants. These GLP-1 secretagogues derived from medicinal plants are easy to find in our surroundings, and their effectiveness has been demonstrated through traditional remedies. The finding of GLP-1 secretagogues is directly linked to understanding of the role of intestinal nutrient sensors and their recognizable nutrients. Concurrently, this study demonstrates the possibility of developing novel therapeutics for metabolic disorders such as T2DM and obesity using nutrients that are readily accessible in our surroundings. PMID:26788106

  5. Intestinal drug transporter expression and the impact of grapefruit juice in humans.

    PubMed

    Glaeser, H; Bailey, D G; Dresser, G K; Gregor, J C; Schwarz, U I; McGrath, J S; Jolicoeur, E; Lee, W; Leake, B F; Tirona, R G; Kim, R B

    2007-03-01

    The goals of this study were to assess the extent of human intestinal drug transporter expression, determine the subcellular localization of the drug uptake transporter OATP1A2, and then to assess the effect of grapefruit juice consumption on OATP1A2 expression relative to cytochrome P450 3A4 and MDR1. Expression of drug uptake and efflux transporters was assessed using human duodenal biopsy samples. Fexofenadine uptake by different transporters was measured in a transporter-transfected cell line. We investigated the influence of grapefruit juice on pharmacokinetics of orally administered fexofenadine. The effect of grapefruit juice on the expression of intestinal transporters was determined using real-time polymerase chain reaction and Western blot analysis. In the duodenum of healthy volunteers, an array of CYP enzymes as well as uptake and efflux transporters was expressed. Importantly, uptake transporters thought to be liver-specific, such as OATP1B1 and 1B3, as well as OATP2B1 and 1A2 were expressed in the intestine. However, among OATP transporters, only OATP1A2 was capable of fexofenadine uptake when assessed in vitro. OATP1A2 colocalized with MDR1 to the brush border domain of enterocytes. Consumption of grapefruit juice concomitantly or 2 h before fexofenadine administration was associated with reduced oral fexofenadine plasma exposure, whereas intestinal expression of either OATP1A2 or MDR1 remained unaffected. In conclusion, an array of drug uptake and efflux transporters are expressed in the human intestine. OATP1A2 is likely the key intestinal uptake transporter for fexofenadine absorption whose inhibition results in the grapefruit juice effect. Although short-term grapefruit juice ingestion was associated with reduced fexofenadine availability, OATP1A2 or MDR1 expression was unaffected.

  6. Inhibition of cholesterol transport in an intestine cell model by pine-derived phytosterols.

    PubMed

    Yi, Jinsoo; Knudsen, Tine A; Nielsen, Anne-Louise; Duelund, Lars; Christensen, Morten; Hervella, Pablo; Needham, David; Mouritsen, Ole G

    2016-10-01

    We have quantified the inhibition of intestinal cholesterol transport by pine-derived phytosterols using an HT29-MTX intestine cell model that forms a mucus layer similar to that in the intestine. An artificial intestinal fluid consisting of digested fat, bile salt, cholesterol, and phytosterols was formulated in order to mimic the conditions in the intestine. The apparent permeability coefficient (Papp) of the positive control, i.e., 0.1mM of cholesterol solubilized in the artificial intestine fluid, was found to be 0.33 (±0.17)×10(-6)cm/s. When 0.1mM β-sitosterol was solubilized alongside, Papp was effectively zero, corresponding to a total inhibition of cholesterol transport. A similar strong inhibition was found when commercial pine-derived phytosterols, PinVita™ FSP DuPont, were co-solubilized with cholesterol in the dietary model micelles, leading to Papp=0.06 (±0.06)×10(-6)cm/s, i.e., 5.5 times lower than the cholesterol positive control. Additionally, the effect of potential oral administration formulations generated by the pine-derived phytosterols was also characterized. The formulations were produced as a liquid formulation of the cholesterol-containing artificial intestine fluid. Six liquid formulations were tested of which four displayed a Papp in the range of 0-0.09×10(-6)cm/s. The remaining two formulations did not show any inhibition effect on cholesterol transport and even enhanced cholesterol transport. It was furthermore observed that the phytosterols were found in the collected intestine cells but not transported to the basolateral region in the intestinal cell model system. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  7. Disrupted reproduction, estrous cycle, and circadian rhythms in female mice deficient in vasoactive intestinal peptide.

    PubMed

    Loh, D H; Kuljis, D A; Azuma, L; Wu, Y; Truong, D; Wang, H B; Colwell, C S

    2014-10-01

    The female reproductive cycle is gated by the circadian timing system and may be vulnerable to disruptions in the circadian system. Prior work suggests that vasoactive intestinal peptide (VIP)-expressing neurons in the suprachiasmatic nucleus (SCN) are one pathway by which the circadian clock can influence the estrous cycle, but the impact of the loss of this peptide on reproduction has not been assessed. In the present study, we first examine the impact of the genetic loss of the neuropeptide VIP on the reproductive success of female mice. Significantly, mutant females produce about half the offspring of their wild-type sisters even when mated to the same males. We also find that VIP-deficient females exhibit a disrupted estrous cycle; that is, ovulation occurs less frequently and results in the release of fewer oocytes compared with controls. Circadian rhythms of wheel-running activity are disrupted in the female mutant mice, as is the spontaneous electrical activity of dorsal SCN neurons. On a molecular level, the VIP-deficient SCN tissue exhibits lower amplitude oscillations with altered phase relationships between the SCN and peripheral oscillators as measured by PER2-driven bioluminescence. The simplest explanation of our data is that the loss of VIP results in a weakened SCN oscillator, which reduces the synchronization of the female circadian system. These results clarify one of the mechanisms by which disruption of the circadian system reduces female reproductive success. © 2014 The Author(s).

  8. Novel Association between Vasoactive Intestinal Peptide and CRTH2 Receptor in Recruiting Eosinophils

    PubMed Central

    El-Shazly, Amr E.; Begon, Dominique Y.; Kustermans, Gaelle; Arafa, Mohammad; Dortu, Estelle; Henket, Monique; Lefebvre, Philippe P.; Louis, Renaud; Delvenne, Philippe

    2013-01-01

    We explored the relation between vasoactive intestinal peptide (VIP), CRTH2, and eosinophil recruitment. It is shown that CRTH2 expression by eosinophils from allergic rhinitis (AR) patients and eosinophil cell line (Eol-1 cells) was up-regulated by VIP treatment. This was functional and resulted in exaggerated migratory response of cells against PGD2. Nasal challenge of AR patients resulted in a significant increase of VIP contents in nasal secretion (ELISA), and the immunohistochemical studies of allergic nasal tissues showed significant expression of VIP in association with intense eosinophil recruitment. Biochemical assays showed that VIP-induced eosinophil chemotaxis from AR patients and Eol-1 cells was mediated through the CRTH2 receptor. Cell migration against VIP was sensitive to protein kinase C (PKC) and protein kinase A (PKA) inhibition but not to tyrosine kinase or p38 MAPK inhibition or calcium chelation. Western blot demonstrated a novel CRTH2-mediated cytosol-to-membrane translocation of PKC-ϵ, PKC-δ, and PKA-α, -γ, and -IIαreg in Eol-1 cells upon stimulation with VIP. Confocal images and FACS demonstrated a strong association and co-localization between VIP peptide and CRTH2 molecules. Further, VIP induced PGD2 secretion from eosinophils. Our results demonstrate the first evidence of association between VIP and CRTH2 in recruiting eosinophils. PMID:23168411

  9. Cytotoxicity of peptide-coated silver nanoparticles on the human intestinal cell line Caco-2.

    PubMed

    Böhmert, Linda; Niemann, Birgit; Thünemann, Andreas F; Lampen, Alfonso

    2012-07-01

    Silver nanoparticles are used in a wide range of consumer products such as clothing, cosmetics, household goods, articles of daily use and pesticides. Moreover, the use of a nanoscaled silver hydrosol has been requested in the European Union for even nutritional purposes. However, despite the wide applications of silver nanoparticles, there is a lack of information concerning their impact on human health. In order to investigate the effects of silver nanoparticles on human intestinal cells, we used the Caco-2 cell line and peptide-coated silver nanoparticles with defined colloidal, structural and interfacial properties. The particles display core diameter of 20 and 40 nm and were coated with the small peptide L-cysteine L-lysine L-lysine. Cell viability and proliferation were measured using Promegas CellTiter-Blue® Cell Viability assay, DAPI staining and impedance measurements. Apoptosis was determined by Annexin-V/7AAD staining and FACS analysis, membrane damage with Promegas LDH assay and reactive oxygen species by dichlorofluorescein assay. Exposure of proliferating Caco-2 cells to silver nanoparticle induced decreasing adherence capacity and cytotoxicity, whereby the formation of reactive oxygen species could be the mode of action. The effects were dependent on particle size (20, 40 nm), doses (5-100 μg/mL) and time of incubation (4-48 h). Apoptosis or membrane damage was not detected.

  10. Liver X receptor-activating ligands modulate renal and intestinal sodium–phosphate transporters

    PubMed Central

    Caldas, Yupanqui A.; Giral, Hector; Cortázar, Michael A.; Sutherland, Eileen; Okamura, Kayo; Blaine, Judith; Sorribas, Victor; Koepsell, Hermann; Levi, Moshe

    2012-01-01

    Cholesterol is pumped out of the cells in different tissues, including the vasculature, intestine, liver, and kidney, by the ATP-binding cassette transporters. Ligands that activate the liver X receptor (LXR) modulate this efflux. Here we determined the effects of LXR agonists on the regulation of phosphate transporters. Phosphate homeostasis is regulated by the coordinated action of the intestinal and renal sodium–phosphate (NaPi) transporters, and the loss of this regulation causes hyperphosphatemia. Mice treated with DMHCA or TO901317, two LXR agonists that prevent atherosclerosis in ApoE or LDLR knockout mice, significantly decreased the activity of intestinal and kidney proximal tubular brush border membrane sodium gradient-dependent phosphate uptake, decreased serum phosphate, and increased urine phosphate excretion. The effects of DMHCA were due to a significant decrease in the abundance of the intestinal and renal NaPi transport proteins. The same effect was also found in opossum kidney cells in culture after treatment with either agonist. There was increased nuclear expression of the endogenous LXR receptor, a reduction in NaPi4 protein abundance (the main type II NaPi transporter in the opossum cells), and a reduction in NaPi co-transport activity. Thus, LXR agonists modulate intestinal and renal NaPi transporters and, in turn, serum phosphate levels. PMID:21677638

  11. Liver X receptor-activating ligands modulate renal and intestinal sodium-phosphate transporters.

    PubMed

    Caldas, Yupanqui A; Giral, Hector; Cortázar, Michael A; Sutherland, Eileen; Okamura, Kayo; Blaine, Judith; Sorribas, Victor; Koepsell, Hermann; Levi, Moshe

    2011-09-01

    Cholesterol is pumped out of the cells in different tissues, including the vasculature, intestine, liver, and kidney, by the ATP-binding cassette transporters. Ligands that activate the liver X receptor (LXR) modulate this efflux. Here we determined the effects of LXR agonists on the regulation of phosphate transporters. Phosphate homeostasis is regulated by the coordinated action of the intestinal and renal sodium-phosphate (NaPi) transporters, and the loss of this regulation causes hyperphosphatemia. Mice treated with DMHCA or TO901317, two LXR agonists that prevent atherosclerosis in ApoE or LDLR knockout mice, significantly decreased the activity of intestinal and kidney proximal tubular brush border membrane sodium gradient-dependent phosphate uptake, decreased serum phosphate, and increased urine phosphate excretion. The effects of DMHCA were due to a significant decrease in the abundance of the intestinal and renal NaPi transport proteins. The same effect was also found in opossum kidney cells in culture after treatment with either agonist. There was increased nuclear expression of the endogenous LXR receptor, a reduction in NaPi4 protein abundance (the main type II NaPi transporter in the opossum cells), and a reduction in NaPi co-transport activity. Thus, LXR agonists modulate intestinal and renal NaPi transporters and, in turn, serum phosphate levels.

  12. Osmoregulation and epithelial water transport: lessons from the intestine of marine teleost fish.

    PubMed

    Whittamore, Jonathan M

    2012-01-01

    For teleost fish living in seawater, drinking the surrounding medium is necessary to avoid dehydration. This is a key component of their osmoregulatory strategy presenting the challenge of excreting excess salts while achieving a net retention of water. The intestine has an established role in osmoregulation, and its ability to effectively absorb fluid is crucial to compensating for water losses to the hyperosmotic environment. Despite this, the potential for the teleost intestine to serve as a comparative model for detailed, integrative experimental studies on epithelial water transport has so far gone largely untapped. The following review aims to present an assessment of the teleost intestine as a fluid-transporting epithelium. Beginning with a brief overview of marine teleost osmoregulation, emphasis shifts to the processing of ingested seawater by the gastrointestinal tract and the characteristics of intestinal ion and fluid transport. Particular attention is given to acid-base transfers by the intestine, specifically bicarbonate secretion, which creates the distinctly alkaline gut fluids responsible for the formation of solid calcium carbonate precipitates. The respective contributions of these unique features to intestinal fluid absorption, alongside other recognised ion transport processes, are then subsequently considered within the wider context of the classic physiological problem of epithelial water transport.

  13. Dietary phosphorus regulates intestinal transport and plasma concentrations of phosphate in rainbow trout.

    PubMed

    Avila, E M; Tu, H; Basantes, S; Ferraris, R P

    2000-05-01

    Intestinal inorganic phosphate transport and its regulation have not been studied in fish. In this study, we initially characterized the mechanisms of intestinal inorganic phosphate transport in rainbow trout (Oncorhynchus mykiss) then determined the effects of dietary phosphorus concentrations on intestinal inorganic phosphate uptake, plasma inorganic phosphate, and intestinal luminal inorganic phosphate concentrations. In 11-g trout, the saturable mechanism of brushborder inorganic phosphate uptake had a Kt= 1.2 mmol l(-1) and a Vmax = 0.22 nmol mg(-1) min(-1), while the diffusive component had a Kd = 0.012 min(-1). Similar kinetic constants were obtained from 51-g trout, suggesting that development or size had little effect on transport. Tracer inorganic phosphate (1.18 mmol l(-1)) uptake was almost completely inhibited (>95%) by 20 mmol l(-1) unlabeled inorganic phosphate. Inorganic phosphate uptake (0.2 mmol l(-1)) was strongly inhibited (approximately 75% inhibition) by phosphonoformic acid, a competitive inhibitor of mammalian inorganic phosphate transport, as well as by the absence of Na+ (approximately 90% inhibition). Northern blot and reverse transcription-polymerase chain reaction indicated that the intestinal inorganic phosphate transporter in trout is not related to the cloned Na+ inorganic phosphate-II transporter of winter flounder. Intestinal luminal and plasma inorganic phosphate concentrations each increased with dietary P concentrations. Intestinal inorganic phosphate, but not proline, absorption rates decreased with dietary phosphorus concentrations. As in mammals and birds, a Na-dependent inorganic phosphate carrier that is tightly regulated by diet is present in trout small intestine.

  14. High affinity receptors for vasoactive intestinal peptide on a human glioma cell line

    SciTech Connect

    Nielsen, F.C.; Gammeltoft, S.; Westermark, B.; Fahrenkrug, J. )

    1990-11-01

    Vasoactive intestinal peptide (VIP) bound with high affinity (Kd 0.13 nmol/l) to receptors on the human glioma cell line U-343 MG Cl 2:6. The receptors bound the related peptides helodermin, PHM and secretin with 10, 400 and 5000 times lower affinity, respectively. Deamidated VIP (VIP-COOH) and (des-His1)VIP bound with 10 and 100 times lower affinity. The fragment VIP(7-28) displaced 25% of the receptor-bound {sup 125}I-VIP whereas VIP(16-28) and VIP(1-22-NH2) were inactive. The binding of {sup 125}I-VIP could be completely inhibited by 10 mumol/l of the antagonists (N-Ac-Tyr1,D-Phe2)GRF(1-29)-NH2, (pCl-D-Phe6,Leu17)VIP and VIP(10-28); in contrast, the antagonist L-8-K was inactive. Affinity labeling showed that VIP bound to proteins with Mr's of 75 kDa, 66 kDa and 50 kDa, respectively. Following binding, the peptide was rapidly internalized, and at steady-state only 20% of cell-associated {sup 125}I-VIP was bound to receptors on the cell surface. The internalized {sup 125}I-VIP was completely degraded to {sup 125}I-tyrosine which was released from the cells. Degradation of internalized {sup 125}I-VIP was significantly reduced by chloroquine phenanthroline and pepstatin-A. Surface binding and internalization of {sup 125}I-VIP was increased 3 times by phenanthroline, and pepstatin-A caused a 5 times increase in surface binding. Chloroquine reduced surface-bound {sup 125}I-VIP, but caused retention of internalized {sup 125}I-VIP.

  15. Comparison of the protective effect of self-emulsifying peptide drug delivery systems towards intestinal proteases and glutathione.

    PubMed

    Hetényi, Gergely; Griesser, Janine; Moser, Michael; Demarne, Frédéric; Jannin, Vincent; Bernkop-Schnürch, Andreas

    2017-05-15

    The aim of this study was to evaluate the protective effect of self-emulsifying drug delivery systems (SEDDS) for therapeutic peptides towards intestinal proteases and reduced glutathione (GSH). Sodium docusate was applied as anionic surfactant for hydrophobic ion pairing with leuprorelin (LEU), insulin (INS) and desmopressin (DES). The complexes were loaded into SEDDS that were characterized regarding droplet size distribution and zeta potential. The release profile of the peptides was examined by dialysis membrane method. Enzymatic digestion studies were performed by applying α-chymotrypsin, trypsin and elastase. Furthermore, the protective effect of SEDDS towards degradation through thiol-disulfide exchange reactions was examined by addition of GSH. SEDDS showed a mean droplet size of 0.27-3.9μm and a zeta potential of -25 to -33mV. All formulations provided a sustained release of the peptides over 6h. Degradation of the model peptides by intestinal proteases and GSH could only be observed in the release medium. In the oily phase of SEDDS neither any of the proteases nor GSH was soluble (≤0.1%). Furthermore, no degradation of the model peptides by proteases and GSH took place in the oily phase of SEDDS. SEDDS can provide a 100% protective effect towards protease degradation and deactivation by GSH. According to this, SEDDS might be promising tools for oral delivery of peptide drugs. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. NisT, the transporter of the lantibiotic nisin, can transport fully modified, dehydrated, and unmodified prenisin and fusions of the leader peptide with non-lantibiotic peptides.

    PubMed

    Kuipers, Anneke; de Boef, Esther; Rink, Rick; Fekken, Susan; Kluskens, Leon D; Driessen, Arnold J M; Leenhouts, Kees; Kuipers, Oscar P; Moll, Gert N

    2004-05-21

    Lantibiotics are lanthionine-containing peptide antibiotics. Nisin, encoded by nisA, is a pentacyclic lantibiotic produced by some Lactococcus lactis strains. Its thioether rings are posttranslationally introduced by a membrane-bound enzyme complex. This complex is composed of three enzymes: NisB, which dehydrates serines and threonines; NisC, which couples these dehydrated residues to cysteines, thus forming thioether rings; and the transporter NisT. We followed the activity of various combinations of the nisin enzymes by measuring export of secreted peptides using antibodies against the leader peptide and mass spectroscopy for detection. L. lactis expressing the nisABTC genes efficiently produced fully posttranslationally modified prenisin. Strikingly, L. lactis expressing the nisBT genes could produce dehydrated prenisin without thioether rings and a dehydrated form of a non-lantibiotic peptide. In the absence of the biosynthetic NisBC enzymes, the NisT transporter was capable of excreting unmodified prenisin and fusions of the leader peptide with non-lantibiotic peptides. Our data show that NisT specifies a broad spectrum (poly)peptide transporter that can function either in conjunction with or independently from the biosynthetic genes. NisT secretes both unmodified and partially or fully posttranslationally modified forms of prenisin and non-lantibiotic peptides. These results open the way for efficient production of a wide range of peptides with increased stability or novel bioactivities.

  17. Ontogeny of Human Hepatic and Intestinal Transporter Gene Expression during Childhood: Age Matters

    PubMed Central

    Mooij, Miriam G.; Schwarz, Ute I.; de Koning, Barbara A. E.; Leeder, J. Steven; Gaedigk, Roger; Samsom, Janneke N.; Spaans, Edwin; van Goudoever, Johannes B.; Tibboel, Dick; Kim, Richard B.

    2014-01-01

    Many drugs prescribed to children are drug transporter substrates. Drug transporters are membrane-bound proteins that mediate the cellular uptake or efflux of drugs and are important to drug absorption and elimination. Very limited data are available on the effect of age on transporter expression. Our study assessed age-related gene expression of hepatic and intestinal drug transporters. Multidrug resistance protein 2 (MRP2), organic anion transporting polypeptide 1B1 (OATP1B1), and OATP1B3 expression was determined in postmortem liver samples (fetal n = 6, neonatal n = 19, infant n = 7, child n = 2, adult n = 11) and multidrug resistance 1 (MDR1) expression in 61 pediatric liver samples. Intestinal expression of MDR1, MRP2, and OATP2B1 was determined in surgical small bowel samples (neonates n = 15, infants n = 3, adults n = 14). Using real-time reverse-transcription polymerase chain reaction, we measured fetal and pediatric gene expression relative to 18S rRNA (liver) and villin (intestines), and we compared it with adults using the 2−∆∆Ct method. Hepatic expression of MRP2, OATP1B1, and OATP1B3 in all pediatric age groups was significantly lower than in adults. Hepatic MDR1 mRNA expression in fetuses, neonates, and infants was significantly lower than in adults. Neonatal intestinal expressions of MDR1 and MRP2 were comparable to those in adults. Intestinal OATP2B1 expression in neonates was significantly higher than in adults. We provide new data that show organ- and transporter-dependent differences in hepatic and intestinal drug transporter expression in an age-dependent fashion. This suggests that substrate drug absorption mediated by these transporters may be subject to age-related variation in a transporter dependent pattern. PMID:24829289

  18. Developmental regulation of nutrient transporter and enzyme mRNA abundance in the small intestine of broilers.

    PubMed

    Gilbert, E R; Li, H; Emmerson, D A; Webb, K E; Wong, E A

    2007-08-01

    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.

  19. Supramolecular functional assemblies: dynamic membrane transporters and peptide nanotubular composites.

    PubMed

    Fuertes, Alberto; Juanes, Marisa; Granja, Juan R; Montenegro, Javier

    2017-07-11

    The fabrication of functional molecular devices constitutes one of the most important current challenges for chemical sciences. The complex processes accomplished by living systems continuously demand the assistance of non-covalent interactions between molecular building blocks. Additionally, these building blocks (proteins, membranes, nucleotides) are also constituted by self-assembled structures. Therefore, supramolecular chemistry is the discipline required to understand the properties of the minimal self-assembled building blocks of living systems and to develop new functional smart materials. In the first part of this feature article, we highlight selected examples of the preparation of supramolecular membrane transporters with special emphasis on the application of dynamic covalent bonds. In the second section of the paper we review recent breakthroughs in the preparation of peptide nanotube hybrids with functional applications. The development of these devices constitutes an exciting process from where we can learn how to understand and manipulate supramolecular functional assemblies.

  20. Is apolipoprotein A-IV rate limiting in the intestinal transport and absorption of triglyceride?

    PubMed

    Kohan, Alison B; Wang, Fei; Li, Xiaoming; Vandersall, Abbey E; Huesman, Sarah; Xu, Min; Yang, Qing; Lou, Danwen; Tso, Patrick

    2013-06-15

    Apolipoprotein A-IV (apoA-IV) is synthesized by the intestine and secreted when dietary fat is absorbed and transported into lymph associated with chylomicrons. We have recently demonstrated that loss of apoA-IV increases chylomicron size and delays its clearance from the blood. There is still uncertainty, however, about the precise role of apoA-IV on the transport of dietary fat from the intestine into the lymph. ApoA-IV knockout (KO) mice do not have a gross defect in dietary lipid absorption, as measured by oral fat tolerance and fecal fat measurements. Here, using the in vivo lymph fistula mouse model, we show that the cumulative secretion of triglyceride (TG) into lymph in apoA-IV KO mice is very similar to that of wild-type (WT) mice. However, the apoA-IV KO mice do have subtle changes in TG accumulation in the intestinal mucosa during a 6-h continuous, but not bolus, infusion of lipid. There are no changes in the ratio of esterified to free fatty acids in the intestinal mucosa of the apoA-IV KO, however. When we extended these findings, by giving a higher dose of lipid (6 μmol/h) and for a longer infusion period (8 h), we found no effect of apoA-IV KO on intestinal TG absorption. This higher lipid infusion most certainly stresses the intestine, as we see a drastically lower absorption of TG (in both WT and KO mice); however, the loss of A-IV does not exacerbate this effect. This supports our hypothesis that apoA-IV is not required for TG absorption in the intestine. Our data suggest that the mechanisms by which the apoA-IV KO intestine responds to intestinal lipid may not be different from their WT counterparts. We conclude that apoA-IV is not required for normal lymphatic transport of TG.

  1. Extra-Renal Elimination of Uric Acid via Intestinal Efflux Transporter BCRP/ABCG2

    PubMed Central

    Hosomi, Atsushi; Nakanishi, Takeo; Fujita, Takuya; Tamai, Ikumi

    2012-01-01

    Urinary excretion accounts for two-thirds of total elimination of uric acid and the remainder is excreted in feces. However, the mechanism of extra-renal elimination is poorly understood. In the present study, we aimed to clarify the mechanism and the extent of elimination of uric acid through liver and intestine using oxonate-treated rats and Caco-2 cells as a model of human intestinal epithelium. In oxonate-treated rats, significant amounts of externally administered and endogenous uric acid were recovered in the intestinal lumen, while biliary excretion was minimal. Accordingly, direct intestinal secretion was thought to be a substantial contributor to extra-renal elimination of uric acid. Since human efflux transporter BCRP/ABCG2 accepts uric acid as a substrate and genetic polymorphism causing a decrease of BCRP activity is known to be associated with hyperuricemia and gout, the contribution of rBcrp to intestinal secretion was examined. rBcrp was confirmed to transport uric acid in a membrane vesicle study, and intestinal regional differences of expression of rBcrp mRNA were well correlated with uric acid secretory activity into the intestinal lumen. Bcrp1 knockout mice exhibited significantly decreased intestinal secretion and an increased plasma concentration of uric acid. Furthermore, a Bcrp inhibitor, elacridar, caused a decrease of intestinal secretion of uric acid. In Caco-2 cells, uric acid showed a polarized flux from the basolateral to apical side, and this flux was almost abolished in the presence of elacridar. These results demonstrate that BCRP contributes at least in part to the intestinal excretion of uric acid as extra-renal elimination pathway in humans and rats. PMID:22348008

  2. IGF Binding Protein-4 is Required for the Growth Effects of Glucagon-Like Peptide-2 in Murine Intestine

    PubMed Central

    Austin, Kaori; Imam, Nuvair A.; Pintar, John E.

    2015-01-01

    Glucagon-like peptide-2 (GLP-2) is an enteroendocrine hormone that stimulates the growth of the intestinal epithelium. We have previously demonstrated that GLP-2 exerts its intestinotropic effect through an indirect mechanism that requires both IGF-1 and the intestinal epithelial IGF-1 receptor. However, the biological activity of IGF-1 is modulated by IGF binding proteins (IGFBPs), including IGFBP-4, which is highly expressed in the intestine. To determine the role of IGFBP-4 in the tropic effects of GLP-2, IGFBP-4 knockout (KO) and control mice were treated with degradation-resistant GLP-2 or vehicle for 10 days. Comparable levels of IGFBP-1–3/5–7 mRNAs were observed in the intestinal mucosa of all animals. IGFBP-4 KO mice had greater small intestinal weight and length, and deeper crypts (P < .05) as compared with controls, suggesting that IGFBP-4 has an inhibitory role in basal intestinal growth. However, small intestinal weight, crypt-villus height and crypt cell proliferation increased in response to GLP-2 in control mice (P < .05), and these changes were abrogated with IGFBP-4 KO. In contrast, pregnancy-associated plasma protein-A KO mice, which have increased levels of circulating IGFBP-4, demonstrated a normal intestinotropic response to GLP-2. Finally, GLP-2 treatment of control mice significantly increased IGFBP-4 mRNA expression in the jejunal mucosa (P < .05), a finding that was recapitulated by GLP-2 treatment of fetal rat intestinal cells in culture (10−8M for 2 h; P < .05). Collectively, these results indicate that the IGF-I-modulating protein, IGFBP-4, exerts a negative effect on basal intestinal growth but plays a positive regulatory role in the intestinotropic actions of GLP-2. PMID:25514089

  3. Roles of different peptide transporters in nutrient acquisition in Candida albicans.

    PubMed

    Dunkel, Nico; Hertlein, Tobias; Franz, Renate; Reuß, Oliver; Sasse, Christoph; Schäfer, Tina; Ohlsen, Knut; Morschhäuser, Joachim

    2013-04-01

    Fungi possess two distinct proton-coupled peptide transport systems, the dipeptide/tripeptide transporters (PTR) and the oligopeptide transporters (OPT), which enable them to utilize peptides as nutrients. In the pathogenic yeast Candida albicans, peptide transporters are encoded by gene families consisting of two PTR genes and eight OPT genes. To gain insight into the functions and importance of specific peptide transporters, we generated mutants lacking the two dipeptide/tripeptide transporters Ptr2 and Ptr22, as well as the five major oligopeptide transporters Opt1 to Opt5. These mutants were unable to grow in media containing peptides as the sole nitrogen source. Forced expression of individual peptide transporters in the septuple mutants showed that Ptr2 and Ptr22 could utilize all tested dipeptides as substrates but differed in their abilities to transport specific tripeptides. Interestingly, several oligopeptide transporters, which are thought to transport peptides consisting of more than three amino acids, also mediated the uptake of tripeptides. Opt1 especially turned out to be a highly flexible transporter that enabled growth on all tripeptides tested and could even utilize a dipeptide, a function that has never been ascribed to this family of peptide transporters. Despite their inability to grow on proteins or peptides, the opt1Δ opt2Δ opt3Δ opt4Δ opt5Δ ptr2Δ ptr22Δ septuple mutants had no in vivo fitness defect in a mouse model of gastrointestinal colonization. Therefore, the nutritional versatility of C. albicans enables it to utilize alternative nitrogen sources in this host niche, which probably contributes to its success as a commensal and pathogen in mammalian hosts.

  4. Roles of Different Peptide Transporters in Nutrient Acquisition in Candida albicans

    PubMed Central

    Dunkel, Nico; Hertlein, Tobias; Franz, Renate; Reuß, Oliver; Sasse, Christoph; Schäfer, Tina; Ohlsen, Knut

    2013-01-01

    Fungi possess two distinct proton-coupled peptide transport systems, the dipeptide/tripeptide transporters (PTR) and the oligopeptide transporters (OPT), which enable them to utilize peptides as nutrients. In the pathogenic yeast Candida albicans, peptide transporters are encoded by gene families consisting of two PTR genes and eight OPT genes. To gain insight into the functions and importance of specific peptide transporters, we generated mutants lacking the two dipeptide/tripeptide transporters Ptr2 and Ptr22, as well as the five major oligopeptide transporters Opt1 to Opt5. These mutants were unable to grow in media containing peptides as the sole nitrogen source. Forced expression of individual peptide transporters in the septuple mutants showed that Ptr2 and Ptr22 could utilize all tested dipeptides as substrates but differed in their abilities to transport specific tripeptides. Interestingly, several oligopeptide transporters, which are thought to transport peptides consisting of more than three amino acids, also mediated the uptake of tripeptides. Opt1 especially turned out to be a highly flexible transporter that enabled growth on all tripeptides tested and could even utilize a dipeptide, a function that has never been ascribed to this family of peptide transporters. Despite their inability to grow on proteins or peptides, the opt1Δ opt2Δ opt3Δ opt4Δ opt5Δ ptr2Δ ptr22Δ septuple mutants had no in vivo fitness defect in a mouse model of gastrointestinal colonization. Therefore, the nutritional versatility of C. albicans enables it to utilize alternative nitrogen sources in this host niche, which probably contributes to its success as a commensal and pathogen in mammalian hosts. PMID:23376942

  5. Iodide transport in rat small intestine: dependence on calcium.

    PubMed Central

    Ilundain, A; Larralde, J; Toval, M

    1987-01-01

    1. The involvement of calcium in the regulation of iodide secretion was investigated in stripped sheets of rat small intestine. 2. In the absence of exogenous modifiers a net iodide absorption was observed in the rat proximal intestine, whereas the mid-intestine secreted iodide. 3. Removal of Ca2+ from the bathing solutions abolished net I- secretion in the mid-intestine. The calcium channel blocker verapamil produced similar effects on net I- secretion. 4. Theophylline increased net I- secretion both in the absence and in the presence of verapamil, but the effects of theophylline were less in the presence of verapamil or in Ca2+-free media. 5. Trifluoperazine inhibited basal iodide secretion and attenuated theophylline-induced I- secretion. 6. All the modifiers which prevented net I- secretion reduced iodide fluxes across the mucosal border and increased serosal iodide exit. The opposite was observed with theophylline. 7. It is suggested that I- secretion might result from changes in both mucosal and serosal I- permeabilities, and that both processes appear to be regulated by calmodulin. PMID:3446797

  6. Role of the Intestinal Bile Acid Transporters in Bile Acid and Drug Disposition

    PubMed Central

    Dawson, Paul A.

    2011-01-01

    Membrane transporters expressed by the hepatocyte and enterocyte play critical roles in maintaining the enterohepatic circulation of bile acids, an effective recycling and conservation mechanism that largely restricts these potentially cytotoxic detergents to the intestinal and hepatobiliary compartments. In doing so, the hepatic and enterocyte transport systems ensure a continuous supply of bile acids to be used repeatedly during the digestion of multiple meals throughout the day. Absorption of bile acids from the intestinal lumen and export into the portal circulation is mediated by a series of transporters expressed on the enterocyte apical and basolateral membranes. The ileal apical sodium-dependent bile acid cotransporter (abbreviated ASBT; gene symbol, SLC10A2) is responsible for the initial uptake of bile acids across the enterocyte brush border membrane. The bile acids are then efficiently shuttled across the cell and exported across the basolateral membrane by the heteromeric Organic Solute Transporter, OSTα-OSTβ. This chapter briefly reviews the tissue expression, physiology, genetics, pathophysiology, and transport properties of the ASBT and OSTα-OSTα. In addition, the chapter discusses the relationship between the intestinal bile acid transporters and drug metabolism, including development of ASBT inhibitors as novel hypocholesterolemic or hepatoprotective agents, prodrug targeting of the ASBT to increase oral bioavailability, and involvement of the intestinal bile acid transporters in drug absorption and drug-drug interactions. PMID:21103970

  7. Green tea formulations with vitamin C and xylitol on enhanced intestinal transport of green tea catechins.

    PubMed

    Chung, Jae-Hwan; Kim, Sol; Lee, Sang-Jun; Chung, Jin-Oh; Oh, Yu-Jin; Shim, Soon-Mi

    2013-05-01

    The effect of green tea formulated with vitamin C and xylitol on intestinal cell transport of gallated and nongallated catechin was studied. The transport of catechins from both apical to basolateral and basolateral to apical directions was measured. The effect of vitamin C (4, 10, 20 ppm), xylitol (11, 27.5, 55 ppm), and combinations of both on the intestinal transport rate of catechins was examined. The efflux value (Pb→a/Pa→b) of (-)-epigallocatechin (EGC), (-)-epigallocatechin gallate (EGCG), (-)-epicatechin (EC), and (-)-epicatechin gallate (ECG) was 0.26, 0.22, 1.22, and 0.17, respectively, indicating that EC appeared to be less absorbed compared with other catechins. The addition of xylitol (11, 27.5, 55 ppm) and vitamin C (4, 10, 20 ppm) and in combination enhanced transport rate of nongallated catechins such as EC and EGC. For EC, vitamin C was revealed to be the most effective on intestinal transport, implying the inhibition of the efflux transport mechanism of EC. Intestinal transport of gallated catechins significantly increased from catechins formulated with vitamin C and xylitol in a dose-dependent manner compared to the catechin-only formulation. Results provide a potential strategy to enhance the delivery and bioavailability of catechins in humans by modulating green tea formulation with vitamin C and xylitol.

  8. Transporters for the Intestinal Absorption of Cholesterol, Vitamin E, and Vitamin K.

    PubMed

    Yamanashi, Yoshihide; Takada, Tappei; Kurauchi, Ryoya; Tanaka, Yusuke; Komine, Toko; Suzuki, Hiroshi

    2017-04-03

    Humans cannot synthesize fat-soluble vitamins such as vitamin E and vitamin K. For this reason, they must be obtained from the diet via intestinal absorption. As the deficiency or excess of these vitamins has been reported to cause several types of diseases and disorders in humans, the intestinal absorption of these nutrients must be properly regulated to ensure good health. However, the mechanism of their intestinal absorption remains poorly understood. Recent studies on cholesterol using genome-edited mice, genome-wide association approaches, gene mutation analyses, and the development of cholesterol absorption inhibitors have revealed that several membrane proteins play crucial roles in the intestinal absorption of cholesterol. Surprisingly, detailed analyses of these cholesterol transporters have revealed that they can also transport vitamin E and vitamin K, providing clues to uncover the molecular mechanisms underlying the intestinal absorption of these fat-soluble vitamins. In this review, we focus on the membrane proteins (Niemann-Pick C1 like 1, scavenger receptor class B type I, cluster of differentiation 36, and ATP-binding cassette transporter A1) that are (potentially) involved in the intestinal absorption of cholesterol, vitamin E, and vitamin K and discuss their physiological and pharmacological importance. We also discuss the related uncertainties that need to be explored in future studies.

  9. Vasoactive intestinal peptide reduces the inflammatory profile in mice infected with Trypanosoma cruzi.

    PubMed

    Higyno, Pulchéria Maria Silva; Mendes, Priscila Fagundes; Miranda, Marina Barcelos de; Pereira, Dario Elias; Mota, Ana Paula Lucas; Nogueira, Katiane de Oliveira Pinto Coelho; Caldas, Ivo Santana; Moura, Sandra Aparecida de Lima; Menezes, Cristiane Alves da Silva

    2015-12-01

    Vasoactive intestinal peptide (VIP) has gained great prominence because of its therapeutic potential, which is ascribed to its ability to regulate innate immunity, inhibit antigen-specific Th1 cell responses, and generate T regulatory cells. Additionally, VIP may act as a natural antimicrobial peptide, killing bacteria, fungi, and infective forms of Trypanosoma brucei. Despite the possible relevance of VIP during the course of Chagas disease, studies regarding this in human and experimental Trypanosoma cruzi infections remain poorly characterized. In this work, we evaluated the effects of VIP on systemic and cardiac immune responses during experimental acute infection. C57BL/6 mice were infected with 5000 trypomastigotes of the VL-10 strain of T. cruzi and treated with intraperitoneal VIP injection every other day for one month. After 30 days, we observed no reduction in parasitemia levels. However, we observed a reduction in serum levels of IFN-gamma and IL-2 and an increase in that of IL-4. These data suggest that VIP treatment modified immune responses to favor the Th2 response, which had no impact on parasitemia levels although the serum level of IFN-gamma was reduced. However, this change in immune balance reduced heart damage, as noted by the smaller cardiac volume and the moderate inflammatory infiltrate observed in VIP-treated mice. Our results indicate that VIP treatment reduced the inflammatory response at the cardiac site of mice that were experimentally infected with T. cruzi. These data suggest a protective role for VIP in the heart of infected mice. Copyright © 2015 Elsevier Inc. All rights reserved.

  10. Feed Withdrawal and Transport Interactions with Intestinal and Peripheral Immunity

    USDA-ARS?s Scientific Manuscript database

    Multiple stressors associated with transporting finishing pigs to slaughter can result in increased shedding of pathogens. Previously we found feed withdrawal by itself or followed by transportation increased Salmonella concentrations in ileal contents. However, no difference was found among treatm...

  11. Glucagon-like peptide-2 modulates neurally evoked mucosal chloride secretion in guinea pig small intestine in vitro

    PubMed Central

    Baldassano, Sara; Liu, Sumei; Qu, Mei-Hu; Mulè, Flavia

    2009-01-01

    Glucagon-like peptide-2 (GLP-2) is an important neuroendocrine peptide in intestinal physiology. It influences digestion, absorption, epithelial growth, motility, and blood flow. We studied involvement of GLP-2 in intestinal mucosal secretory behavior. Submucosal-mucosal preparations from guinea pig ileum were mounted in Ussing chambers for measurement of short-circuit current (Isc) as a surrogate for chloride secretion. GLP-2 action on neuronal release of acetylcholine was determined with ELISA. Enteric neuronal expression of the GLP-2 receptor (GLP-2R) was studied with immunohistochemical methods. Application of GLP-2 (0.1–100 nM) to the serosal or mucosal side of the preparations evoked no change in baseline Isc and did not alter transepithelial ionic conductance. Transmural electrical field stimulation (EFS) evoked characteristic biphasic increases in Isc, with an initially rapid rising phase followed by a sustained phase. Application of GLP-2 reduced the EFS-evoked biphasic responses in a concentration-dependent manner. The GLP-2R antagonist GLP-2-(3-33) significantly reversed suppression of the EFS-evoked responses by GLP-2. Tetrodotoxin, scopolamine, and hexamethonium, but not vasoactive intestinal peptide type 1 receptor (VPAC1) antagonist abolished or reduced to near zero the EFS-evoked responses. GLP-2 suppressed EFS-evoked acetylcholine release as measured by ELISA. Pretreatment with GLP-2-(3-33) offset this action of GLP-2. In the submucosal plexus, GLP-2R immunoreactivity (-IR) was expressed in choline acetyltransferase-IR neurons, somatostatin-IR neurons, neuropeptide Y-IR neurons, and vasoactive intestinal peptide-IR neurons. We conclude that submucosal neurons in the guinea pig ileum express GLP-2R. Activation of GLP-2R decreases neuronally evoked epithelial chloride secretion by suppressing acetylcholine release from secretomotor neurons. PMID:19628655

  12. Physiological significance of taurine and the taurine transporter in intestinal epithelial cells.

    PubMed

    Shimizu, M; Satsu, H

    2000-01-01

    Taurine transport in human intestinal epithelial Caco-2 cells was down-regulated by culturing the cells in taurine-containing media and was up-regulated in a taurine-free medium. This adaptive regulation was associated with changes in both the Vmax and Km values of taurine transport. A change in the mRNA level of the taurine transporter (TAUT) in this regulation was also observed. The presence of such a regulatory mechanism for maintaining the intracellular taurine content at a certain level suggests that taurine plays an important role in the intestinal cell functions. The intracellular taurine content was increased when Caco-2 cells were exposed to a hypertonic stress. TAUT was up-regulated via the increased expression of TAUT mRNA in the hypertonic cells, suggesting that taurine serves as an osmolyte and protects the cells from osmotic stress. Similar up-regulation of TAUT was observed in the small intestine of water-deprived rats.

  13. Fatty acid transport protein 4 is dispensable for intestinal lipid absorption in mice.

    PubMed

    Shim, Jien; Moulson, Casey L; Newberry, Elizabeth P; Lin, Meei-Hua; Xie, Yan; Kennedy, Susan M; Miner, Jeffrey H; Davidson, Nicholas O

    2009-03-01

    FA transport protein 4 (FATP4), one member of a multigene family of FA transporters, was proposed as a major FA transporter in intestinal lipid absorption. Due to the fact that Fatp4(-/-) mice die because of a perinatal skin defect, we rescued the skin phenotype using an FATP4 transgene driven by a keratinocyte-specific promoter (Fatp4(-/-);Ivl-Fatp4(tg/+) mice) to elucidate the role of intestinal FATP4 in dietary lipid absorption. Fatp4(-/-);Ivl-Fatp4(tg/+) mice and wild-type littermates displayed indistinguishable food consumption, growth, and weight gain on either low or high fat (Western) diets, with no differences in intestinal triglyceride (TG) absorption or fecal fat losses. Cholesterol absorption and intestinal TG absorption kinetics were indistinguishable between the genotypes, although Western diet fed Fatp4(-/-);Ivl-Fatp4(tg/+) mice showed a significant increase in enterocyte TG and FA content. There was no compensatory upregulation of other FATP family members or any other FA or cholesterol transporters in Fatp4(-/-);Ivl-Fatp4(tg/+) mice. Furthermore, although serum cholesterol levels were lower in Fatp4(-/-);Ivl-Fatp4(tg/+) mice, there was no difference in hepatic VLDL secretion in-vivo or in hepatic lipid content on either a chow or Western diet. Taken together, our studies find no evidence for a physiological role of intestinal FATP4 in dietary lipid absorption in mice.

  14. Role of intestinal transporters in neonatal nutrition: carbohydrates, proteins, lipids, minerals, and vitamins.

    PubMed

    Boudry, Gaëlle; David, Elmer S; Douard, Véronique; Monteiro, Iona M; Le Huërou-Luron, Isabelle; Ferraris, Ronaldo P

    2010-10-01

    To support rapid growth and a high metabolic rate, infants require enormous amounts of nutrients. The small intestine must have the complete array of transporters that absorb the nutrients released from digested food. Failure of intestinal transporters to function properly often presents symptoms as "failure to thrive" because nutrients are not absorbed and as diarrhea because unabsorbed nutrients upset luminal osmolality or become substrates of intestinal bacteria. We enumerate the nutrients that constitute human milk and various infant milk formulas, explain their importance in neonatal nutrition, then describe for each nutrient the transporter(s) that absorbs it from the intestinal lumen into the enterocyte cytosol and from the cytosol to the portal blood. More than 100 membrane and cytosolic transporters are now thought to facilitate absorption of minerals and vitamins as well as products of digestion of the macronutrients carbohydrates, proteins, and lipids. We highlight research areas that should yield information needed to better understand the important role of these transporters during normal development.

  15. Growth factor based therapies and intestinal disease: is glucagon-like peptide-2 the new way forward?

    PubMed

    Yazbeck, Roger; Howarth, Gordon S; Abbott, Catherine A

    2009-04-01

    Inflammatory bowel disease (IBD) is a chronic, debilitating disease associated with severe damage to the intestinal mucosa. Glucagon-like peptide-2 (GLP-2) is a potent and specific gastrointestinal growth factor that is demonstrating therapeutic potential for the prevention or treatment of an expanding number of intestinal diseases, including short bowel syndrome (SBS), small bowel enteritis and IBD. The biological activity of GLP-2 is limited due to proteolytic inactivation by the protease dipeptidyl peptidase (DP)IV. Inhibitors of DPIV activity may represent a novel strategy to prolong the growth promoting actions of GLP-2. This review outlines evidence for the clinical application of GLP-2, its degradation resistant analogue, Teduglutide, and novel DPIV inhibitors in efficacy studies utilizing pre-clinical models of intestinal damage, in particular IBD.

  16. Neuropeptide Y-like immunoreactivity in rat cranial parasympathetic neurons: coexistence with vasoactive intestinal peptide and choline acetyltransferase

    SciTech Connect

    Leblanc, G.C.; Trimmer, B.A.; Landis, S.C.

    1987-05-01

    Neuropeptide Y (NPY) is widely distributed in the sympathetic nervous system, where it is colocalized with norepinephrine. The authors report here that NPY-immunoreactive neurons are also abundant in three cranial parasympathetic ganglia, the otic, sphenopalatine, and ciliary, in the rat measured by radioimmunoassay. High-performance liquid chromatographic analysis of the immunoreactive material present in the otic ganglion indicates that this material is very similar to porcine NPY and indistinguishable from the NPY-like immunoreactivity present in rat sympathetic neurons. These findings raise the possibility that NPY acts as a neuromodulator in the parasympathetic as well as the sympathetic nervous system. In contrast to what had been observed for sympathetic neurons, NPY-immunoreactive neurons in cranial parasympathetic ganglia do not contain detectable catecholamines or tyrosine hydroxylase immunoreactivity, and many do contain immunoreactivity for vasoactive intestinal peptide and/or choline acetyltransferase. These findings suggest that there is no simple rule governing coexpression of NPY with norepinephrine, acetylcholine, or vasoactive intestinal peptide in autonomic neurons. Further, while functional studies have indicated that NPY exerts actions on the peripheral vasculature which are antagonistic to those of acetylcholine and vasoactive intestinal peptide, the present results raise the possibility that these three substances may have complementary effects on other target tissues.

  17. Effect of Glucagon-Like Peptide 2 on Hepatic, Renal, and Intestinal Disposition of 1-Chloro-2,4-dinitrobenzene

    PubMed Central

    Villanueva, Silvina S. M.; Perdomo, Virginia G.; Ruiz, María L.; Rigalli, Juan P.; Arias, Agostina; Luquita, Marcelo G.; Vore, Mary; Catania, Viviana A.

    2012-01-01

    The ability of the liver, small intestine, and kidney to synthesize and subsequently eliminate dinitrophenyl-S-glutathione (DNP-SG), a substrate for multidrug resistance-associated protein 2 (Mrp2), was assessed in rats treated with glucagon-like peptide 2 (GLP-2, 12 μg/100 g b.wt. s.c. every 12 h for 5 consecutive days). An in vivo perfused jejunum model with simultaneous bile and urine collection was used. A single intravenous dose of 30 μmol/kg b.wt. 1-chloro-2,4-dinitrobenzene (CDNB) was administered, and its conjugate, DNP-SG, and dinitrophenyl cysteinyl glycine (DNP-CG), resulting from the action of γ-glutamyltransferase on DNP-SG, were determined in bile, intestinal perfusate, and urine by high-performance liquid chromatography. Tissue content of DNP-SG was also assessed in liver, intestine, and kidneys. Biliary excretion of DNP-SG+DNP-CG was decreased in GLP-2 rats with respect to controls. In contrast, their intestinal excretion was substantially increased, whereas urinary elimination was not affected. Western blot and real-time polymerase chain reaction studies revealed preserved levels of Mrp2 protein and mRNA in liver and renal cortex and a significant increase in intestine in response to GLP-2 treatment. Tissue content of DNP-SG detected 5 min after CDNB administration was decreased in liver, increased in intestine, and unchanged in kidney in GLP-2 versus control group, consistent with GLP-2-induced down-regulation of expression of glutathione transferase (GST) Mu in liver and up-regulation of GST-Alpha in intestine at both protein and mRNA levels. In conclusion, GLP-2 induced selective changes in hepatic and intestinal disposition of a common GST and Mrp2 substrate administered systemically that could be of pharmacological or toxicological relevance under therapeutic treatment conditions. PMID:22453052

  18. Malignant pheochromocytoma secreting vasoactive intestinal peptide and response to sunitinib: a case report and literature review.

    PubMed

    Leibowitz-Amit, Raya; Lebowitz-Amit, Raya; Mete, Ozgur; Asa, Sylvia L; Ezzat, Shereen; Joshua, Anthony M

    2014-08-01

    Malignant pheochromocytoma is rare and may be sporadic or have a genetic basis. Vasoactive intestinal peptide (VIP)-secreting pheochromocytoma has rarely been described in the literature, and treatment remains challenging in the absence of well-controlled randomized trials. The hypoxia-inducible factor-vascular endothelial growth factor axis has been implicated in pheochromocytoma when associated with germline Von-Hippel-Lindau (VHL) or succinate dehydrogenase (SDH) mutations, suggesting potential clinical activity of sunitinib in this setting. We present a case report of a patient with a VIP-secreting malignant pheochromocytoma manifested as severe watery diarrhea, with an exquisite clinical response to sunitinib. We review this rare clinical entity and the potential role of sunitinib in this context. A 51-year-old male initially presented with a pheochromocytoma causing symptoms related to norepinephrine excess. He underwent adrenalectomy, which resulted in complete resolution of his symptoms. Three years later, he developed multifocal metastatic disease from his primary tumor, showing immunohistochemical evidence of VIP production accompanied by severe watery diarrhea and hypokalemia. The patient had a rapid, complete, and durable clinical response to sunitinib, but with only a minor radiological response and without significant toxicity. Genetic testing was negative for germline mutations in VHL, SDHB, SDHC, SDHD, transmembrane protein 127 (TMEM127) and for neurofibromatosis type 1 (NF-1). To the best of our knowledge, this is the first report of a case of malignant VIP-producing pheochromocytoma that was responsive to sunitinib.

  19. Vasoactive intestinal peptide receptor-based imaging and treatment of tumors (Review).

    PubMed

    Tang, Bo; Yong, Xin; Xie, Rui; Li, Qian-Wei; Yang, Shi-Ming

    2014-04-01

    Vasoactive intestinal peptide receptors (VIPRs) are members of the G-protein-coupled receptor superfamily. These receptors are overexpressed in many common malignant tumors and play a major role in the progression and angiogenesis of a number of malignancies. Therefore, VIPRs may be a valuable target for the molecular imaging of tumors and therapeutic interventions. The specific natural ligand or its analogs can be labeled with a radionuclide and used for tumor receptor imaging, which could be used to visualize VIPR-related surface protein expression in vivo and to monitor the in vivo effects of molecular drugs on tumors. Moreover, the involvement of VIPRs in malignant transformation and angiogenesis renders them potential therapeutic targets for cancer treatment. A variety of VIP antagonists and cytotoxic VIP conjugates have been synthesized and evaluated for VIPR-targeted molecular therapy. The importance of VIPRs in tumor biology and the ability to predict responses to targeted therapy and monitor drug interventions suggest that VIP receptor-based imaging and treatment will be critical for the early diagnosis and management of cancer. Here, we review the current literature regarding VIPRs and their natural ligands and the involvement of VIPRs in tumor growth and angiogenesis, with an emphasis on the present use of VIPRs for the molecular imaging of tumors and therapies targeting VIPRs.

  20. Vasoactive intestinal peptide inhibits fMLP-induced respiratory burst in human lymphocytes.

    PubMed

    Bellido, L; López-González, M A; Pedrera, C; Lucas, M

    1994-01-01

    N-Formyl-Methionyl-Leucyl-Phenylalanine (fMLP) induced in lymphocytes the production of reactive oxygen intermediates in a process which was inhibited by the presence of Vasoactive Intestinal Peptide (VIP) in a dose-dependent response at VIP concentrations in the range 10(-10)-10(-7) M. The dissociation constant for the high-affinity receptors of VIP agrees with the ID50 of the activation of adenylate cyclase which are close to 0.2 nM VIP, whereas the ID50 for the inhibition by VIP of fMLP-induced chemiluminescence approaches to 5 nM VIP. Both IBMX and Forskolin produced in lymphocytes an inhibition of fMLP-induced chemiluminescence. The degree of inhibition was ascertained to be additive in the presence of the above indicated agents and suboptimal concentrations of VIP. The saturation by cAMP of its putative target, the regulatory subunit of protein kinase A, appears to be required for the onset of the inhibitory effect of VIP. This study provides evidence of the molecular signal, namely cAMP, which provokes an inhibitory effect on chemoatractant-stimulated human lymphocytes and further support a role for VIP as a mediator in the neuroimmune system.

  1. Effects of vasoactive intestinal peptide on vascular conductance are unaffected by anesthesia

    SciTech Connect

    Bouder, T.G.; Huffman, L.J.; Hedge, G.A. )

    1988-12-01

    In rats anesthetized with ketamine and pentobarbital (KET/PB), vasoactive intestinal peptide (VIP) increases vascular conductance (VC) in the salivary gland, pancreas, and thyroid gland, whereas no changes in VC are observed in a number of other organs. Because anesthesia may alter the responsiveness of physiological systems, we compared the effects of VIP on organ VC in conscious or anesthetized rats. Chronically catheterized rats were studied in the conscious state or 30 min after induction of anesthesia with KET/PB, isoflurane, or Inactin. Blood flows were measured by the reference sample version of the radioactive microsphere (MS) technique using two MS injections ({sup 141}Ce-MS/{sup 85}Sr-MS). Mean arterial blood pressure was monitored and used in the calculation of VC. Organ VCs were similar under basal conditions in conscious and anesthetized rats. VIP infusion caused systemic hypotension and increased VCs in the salivary gland, pancreas, and thyroid gland, and these responses were largely unaffected by anesthesia. These results indicate that the anesthetics used do not alter basal VC or the responsiveness of the vasculature to exogenous VIP.

  2. Distribution of hypothalamic vasoactive intestinal peptide immunoreactive neurons in the male native Thai chicken.

    PubMed

    Kamkrathok, Boonyarit; Sartsoongnoen, Natagarn; Prakobsaeng, Nattiya; Rozenboim, Israel; Porter, Tom E; Chaiseha, Yupaporn

    2016-08-01

    Avian prolactin (PRL) secretion is under stimulatory control by the PRL-releasing factor (PRF), vasoactive intestinal peptide (VIP). The neuroendocrine regulation of the avian reproductive system has been extensively studied in females. However, there are limited data in males. The aim of this study was to elucidate the VIPergic system and its relationship to PRL and testosterone (T) in the male native Thai chicken. The distributions of VIP-immunoreactive (-ir) neurons and fibers were determined by immunohistochemistry. Changes in VIP-ir neurons within the nucleus inferioris hypothalami (IH) and nucleus infundibuli hypothalami (IN) areas were compared across the reproductive stages. Plasma levels of PRL and T were determined by enzyme-linked immunosorbent assay and then compared across the reproductive stages. The results revealed that the highest accumulations of VIP-ir neurons were concentrated only within the IH-IN, and VIP-ir neurons were not detected within other hypothalamic nuclei. Within the IH-IN, VIP-ir neurons were low in premature and aging males and markedly increased in mature males. Changes in VIP-ir neurons within the IH-IN were directly mirrored with changes in PRL and T levels across the reproductive stages. These results suggested that VIP neurons in the IH-IN play a regulatory role in year-round reproductive activity in males. The present study also provides additional evidence that VIP is the PRF in non-seasonal, continuously breeding equatorial species.

  3. Vasoactive intestinal peptide can promote the development of neonatal rat primordial follicles during in vitro culture.

    PubMed

    Chen, Niannian; Li, Yu; Wang, Wenjun; Ma, Yun; Yang, Dongzi; Zhang, Qingxue

    2013-01-01

    Recruitment of primordial follicles is essential for female fertility. Some of the intraovarian growth factors involved in the initiation of primordial follicle growth have been identified, but the exact mechanisms regulating follicle activation are poorly understood. Strong evidence indicates that vasoactive intestinal peptide (VIP), a neuropeptide found in ovarian nerves, plays a role in the physiology of follicle development and function. The aim of the present study was to determine whether VIP might regulate the activation and growth of neonatal rat primordial follicles in an in vitro culture system. Ovaries from 4-day-old rats were cultured for 14 days in medium containing 10(-7) M VIP. At the end of the culture, the developmental stages and viability of the follicles were evaluated using histological sections. Immunohistochemistry studies for proliferating cell nuclear antigen (PCNA) were performed to assess the mitotic activity of granulosa cells. In addition, the expression level of kit ligand (KL) mRNA was examined after culture. Histology showed that primordial follicles could survive and start to grow in vitro. The proportion of primordial follicles was decreased and the proportion of early primary follicles increased after in vitro culture with VIP. Immunolocalization of PCNA showed that follicle growth was initiated after VIP treatment. The expression level of KL mRNA was increased in the VIP treatment group. Thus, VIP can promote primordial follicle development, possibly mediated in part through upregulating the expression of KL.

  4. Enteral peptide formulas inhibit radiation induced enteritis and apoptosis in intestinal epithelial cells and suppress the expression and function of Alzheimer's and cell division control gene products

    SciTech Connect

    Cope, F.O. ); Issinger, O.G. ); McArdle, A.H. ); Shapiro, J.; Tomei, L.D. )

    1991-03-15

    Studies have shown that patients receiving enteral peptide formulas prior to irradiation have a significantly reduced incidence of enteritis and express a profound increase in intestinal cellularity. Two conceptual approaches were taken to describe this response. First was the evaluation in changes in programmed intestinal cell death and secondly the evaluation of a gene product controlling cell division cycling. This study provided a relationship between the ratio of cell death to cell formulations. The results indicate that in the canine and murine models, irradiation induces expression of the Alzheimer's gene in intestinal crypt cells, while the incidence of apoptosis in apical cells is significantly increased. The use of peptide enteral formulations suppresses the expression of the Alzheimer's gene in crypt cells, while apoptosis is eliminated in the apical cells of the intestine. Concomitantly, enteral peptide formulations suppress the function of the CK-II gene product in the basal and baso-lateral cells of the intestine. These data indicate that although the mitotic index is significantly reduced in enterocytes, this phenomenon alone is not sufficient to account for the peptide-induced radio-resistance of the intestine. The data also indicate a significant reduction of normal apoptosis in the upper lateral and apical cells of the intestinal villi. Thus, the ratio of cell death to cell replacement is significantly decreased resulting in an increase in villus height and hypertrophy of the apical villus cells. Thus, peptide solutions should be considered as an adjunct treatment both in radio- and chemotherapy.

  5. Monocarboxylate 4 mediated butyrate transport in a rat intestinal epithelial cell line.

    PubMed

    Kekuda, Ramesh; Manoharan, Palanikumar; Baseler, Walter; Sundaram, Uma

    2013-03-01

    Short chain fatty acids (SCFA) are absorbed by carrier mediated uptake in the small intestine by pH-dependent SCFA/HCO3 (-) exchangers on the apical membrane of epithelial cells. Conventional assumption is that MCT1 mediates SCFA/HCO3 (-) exchange in the intestine. Further, due to the presence of multiple such anion exchangers, the identity of the intestinal SCFA/HCO3 (-) has been controversial. The aim of this study was to determine the identities of the butyrate transporter in the intestinal epithelial cells (IEC-18). IEC-18 cells were treated with specific siRNAs for MCT1 and MCT4, and butyrate and lactate uptake studies were performed. Alpha-cyano-4-hydroxycinnamic acid inhibited lactate uptake but not butyrate uptake in IEC-18 cells, indicating that these two substrates are transported via two different transporter systems. MCT1 siRNA treatment abolished both MCT1 mRNA by more than 95 % and protein expression by 83 % as evidenced by RTQ-PCR and western blotting experiments. However, MCT1 siRNA treatment inhibited butyrate uptake upto 24 %, whereas it inhibited lactate uptake significantly by 70 %. Treatment with MCT4 siRNA inhibited MCT4 mRNA expression by 75 % and protein expression by 85 % in these cells. MCT4 siRNA inhibited butyrate uptake by 40 %. Further, several non-steroidal anti-inflammatory drugs (NSAIDs) are transported by the butyrate transporter. Finally, MCT4 siRNA inhibited salicylate uptake by 27 % indicating direct evidence for the transport of salicylate by MCT4. These data indicate that MCT1 is the high affinity lactate transporter and MCT4 is the high affinity butyrate transporter in the intestinal epithelial cell line IEC-18.

  6. Several transport systems contribute to the intestinal uptake of Paraquat, modulating its cytotoxic effects.

    PubMed

    Silva, Renata; Carmo, Helena; Vilas-Boas, Vânia; Barbosa, Daniel José; Monteiro, Márcia; de Pinho, Paula Guedes; de Lourdes Bastos, Maria; Remião, Fernando

    2015-01-05

    Paraquat (PQ) is an extremely toxic herbicide upon oral ingestion that lacks a specific antidote. In case of intoxication, treatment primarily relies on limiting its intestinal absorption. In this study, we elucidate the intestinal transport mechanisms of PQ uptake using Caco-2 cells as a model of the human intestinal epithelium. The cells were incubated with a wide range of PQ concentrations (0-5000μM) for 24h with or without simultaneous exposure to different transporters substrates/inhibitors including, choline or hemicolinium-3 (for choline carrier-mediated transport system inhibition) and putrescine, trifluoperazine, valine, lysine, arginine or N-ethylmaleimide (for basic amino acid transport systems inhibition). PQ cytotoxicity was evaluated by the MTT reduction assay and correlated with PQ intracellular levels quantified by gas chromatography-ion trap-mass spectrometry (GC-IT/MS). Potential interactions of PQ with the substrates/inhibitors of the transport systems were investigated and discarded by infrared spectroscopy. Our results showed a significant reduction in PQ intracellular accumulation and, consequently, in PQ cytotoxicity, in the presence of both choline and hemicolinium-3, demonstrating that the choline carrier-mediated transport system is partially involved in PQ intestinal uptake. Likewise, PQ cytotoxicity and intracellular accumulation were significantly attenuated by simultaneous exposure to putrescine, trifluoperazine, valine, lysine, arginine and N-ethylmaleimide. These data suggested the involvement of more than one of the basic amino acids transport systems, including the y(+), b(0,+) or y(+)L systems. In conclusion, this study demonstrated that several transport systems mediate PQ intestinal absorption and, therefore, their modulation may provide alternative efficient pathways for limiting PQ toxicity in intoxication scenarios. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  7. In vitro study of transporters involved in intestinal absorption of inorganic arsenic.

    PubMed

    Calatayud, Marta; Barrios, Julio A; Vélez, Dinoraz; Devesa, Vicenta

    2012-02-20

    Inorganic arsenic (iAs) [As(III)+As(V)] is a drinking water contaminant, and human exposure to these arsenic species has been linked with a wide range of health effects. The main path of exposure is the oral route, and the intestinal epithelium is the first physiological barrier that iAs must cross in order to be absorbed. However, there is a lack of information about intestinal iAs absorption. The aim of this study was to evaluate the participation of certain transporters [glucose transporters (GLUT and SGLT), organic anion transporting polypeptides (OATPs), aquaporins (AQPs), and phosphate transporters (NaPi and PiT)] in intestinal absorption of As(V) and As(III), using the Caco-2 cell line as a model of the intestinal epithelium. For this purpose, the effects of chemical inhibition and gene silencing of the transporters of interest on iAs uptake were evaluated, and also the differential expression of these transporters after treatment with iAs. The results show that chemical inhibition using rifamycin SV (OATP inhibitor), phloridzin (SGLT inhibitor), phloretin (GLUT and AQP inhibitor), and copper sulfate (AQP inhibitor) leads to a significant reduction in the apparent permeability and cellular retention of As(III). RT-qPCR indicates up-regulation of GLUT2, GLUT5, OATPB, AQP3, and AQP10 after exposure to As(III), while exposure to As(V) increases the expression of sodium-dependent phosphate transporters, especially NaPiIIb. Gene silencing of OATPB, AQP10, and GLUT5 for As(III) and NaPiIIb for As(V) significantly reduces uptake of the inorganic forms. These results indicate that these transporters may be involved in intestinal absorption of iAs.

  8. Acute effects of the glucagon-like peptide 2 analogue, teduglutide, on intestinal adaptation in short bowel syndrome.

    PubMed

    Thymann, Thomas; Stoll, Barbara; Mecklenburg, Lars; Burrin, Douglas G; Vegge, Andreas; Qvist, Niels; Eriksen, Thomas; Jeppesen, Palle B; Sangild, Per T

    2014-06-01

    Neonatal short bowel syndrome following massive gut resection is associated with malabsorption of nutrients. The intestinotrophic factor glucagon-like peptide 2 (GLP-2) improves gut function in adult patients with short bowel syndrome, but its effect in pediatric patients remains unknown. Our objective was to test the efficacy of the long-acting synthetic human GLP-2 analogue, teduglutide (ALX-0600), in a neonatal piglet jejunostomy model. Two-day-old pigs were subjected to resection of 50% of the small intestine (distal part), and the remnant intestine was exteriorized on the abdominal wall as a jejunostomy. All pigs were given total parenteral nutrition for 7 days and a single daily injection of the following doses of teduglutide: 0.01 (n = 6), 0.02 (n = 6), 0.1 (n = 5), or 0.2 mg · kg · day (n = 6), and compared with placebo (n = 9). Body weight increment was similar for all 4 teduglutide groups but higher than placebo (P < 0.05). There was a dose-dependent increase in weight per length of the remnant intestine (P < 0.01) and fractional protein synthesis rate in the intestine was increased in the 0.2 mg · kg · day group versus placebo (P < 0.001); however, functional and structural endpoints including activity of digestive enzymes, absorption of enteral nutrients, and immunohistochemistry (Ki67, villin, FABP2, ChgA, and GLP-2R) were not affected by the treatment. Teduglutide induces trophicity on the remnant intestine but has limited acute effects on functional endpoints. Significant effects of teduglutide on gut function may require a longer adaptation period and/or a more frequent administration of the peptide. In perspective, GLP-2 or its analogues may be relevant to improve intestinal adaptation in pediatric patients with short bowel syndrome.

  9. Peptides actively transported across the tympanic membrane: Functional and structural properties

    PubMed Central

    Kurabi, Arwa; Beasley, Kerry A.; Chang, Lisa; McCann, James; Pak, Kwang; Ryan, Allen F.

    2017-01-01

    Otitis media (OM) is the most common infectious disease of children under six, causing more antibiotic prescriptions and surgical procedures than any other pediatric condition. By screening a bacteriophage (phage) library genetically engineered to express random peptides on their surfaces, we discovered unique peptides that actively transport phage particles across the intact tympanic membrane (TM) and into the middle ear (ME). Herein our goals were to characterize the physiochemical peptide features that may underlie trans-TM phage transport; assess morphological and functional effects of phage peptides on the ME and inner ear (IE); and determine whether peptide-bearing phage transmigrate from the ME into the IE. Incubation of five peptide-bearing phage on the TM for over 4hrs resulted in demonstrably superior transport of one peptide, in level and in exponential increase over time. This suggests a preferred peptide motif for TM active transport. Functional and structural comparisons revealed unique features of this peptide: These include a central lysine residue, isoelectric point of 0.0 at physiological pH and a hydrophobic C-terminus. When the optimal peptide was applied to the TM independent of phage, similar transport was observed, indicating that integration into phage is not required. When 109 particles of the four different trans-TM phage were applied directly into the ME, no morphological effects were detected in the ME or IE when compared to saline or wild-type (WT) phage controls. Comparable, reversible hearing loss was observed for saline controls, WT phage and trans-TM peptide phage, suggesting a mild conductive hearing loss due to ME fluid. Perilymph titers after ME incubation established that few copies of trans-TM peptide phage crossed into the IE. The results suggest that, within the parameters tested, trans-TM peptides are safe and could be used as potential agents for noninvasive delivery of drugs, particles and gene therapy vectors to the ME

  10. Intestinal Serotonin Transporter Inhibition by Toll-Like Receptor 2 Activation. A Feedback Modulation.

    PubMed

    Latorre, Eva; Layunta, Elena; Grasa, Laura; Castro, Marta; Pardo, Julián; Gomollón, Fernando; Alcalde, Ana I; Mesonero, José E

    2016-01-01

    TLR2 is a microbiota recognition receptor that has been described to contribute to intestinal homeostasis and to ameliorate inflammatory intestinal injury. In this context, serotonin (5-HT) has shown to be an essential intestinal physiological neuromodulator that is also involved in intestinal inflammatory diseases. Since the interaction between TLR2 activation and the intestinal serotoninergic system remains non-investigated, our main aim was to analyze the effect of TLR2 on intestinal serotonin transporter (SERT) activity and expression and the intracellular pathways involved. Caco-2/TC7 cells were used to analyze SERT and TLR2 molecular expression and SERT activity by measuring 5-HT uptake. The results showed that apical TLR2 activation inhibits SERT activity in Caco-2/TC7 cells mainly by reducing SERT protein level either in the plasma membrane, after short-term TLR2 activation or in both the plasma membrane and cell lysate, after long-term activation. cAMP/PKA pathway appears to mediate short-term inhibitory effect of TLR2 on SERT; however, p38 MAPK pathway has been shown to be involved in both short- and long-term TLR2 effect. Reciprocally, 5-HT long-term treatment yielded TLR2 down regulation in Caco-2/TC7 cells. Finally, results from in vivo showed an augmented intestinal SERT expression in mice Tlr2-/-, thus confirming our inhibitory effect of TLR2 on intestinal SERT in vitro. The present work infers that TLR2 may act in intestinal pathophysiology, not only by its inherent innate immune role, but also by regulating the intestinal serotoninergic system.

  11. Intestinal Serotonin Transporter Inhibition by Toll-Like Receptor 2 Activation. A Feedback Modulation

    PubMed Central

    Layunta, Elena; Grasa, Laura; Castro, Marta; Pardo, Julián; Gomollón, Fernando; Mesonero, José E.

    2016-01-01

    TLR2 is a microbiota recognition receptor that has been described to contribute to intestinal homeostasis and to ameliorate inflammatory intestinal injury. In this context, serotonin (5-HT) has shown to be an essential intestinal physiological neuromodulator that is also involved in intestinal inflammatory diseases. Since the interaction between TLR2 activation and the intestinal serotoninergic system remains non-investigated, our main aim was to analyze the effect of TLR2 on intestinal serotonin transporter (SERT) activity and expression and the intracellular pathways involved. Caco-2/TC7 cells were used to analyze SERT and TLR2 molecular expression and SERT activity by measuring 5-HT uptake. The results showed that apical TLR2 activation inhibits SERT activity in Caco-2/TC7 cells mainly by reducing SERT protein level either in the plasma membrane, after short-term TLR2 activation or in both the plasma membrane and cell lysate, after long-term activation. cAMP/PKA pathway appears to mediate short-term inhibitory effect of TLR2 on SERT; however, p38 MAPK pathway has been shown to be involved in both short- and long-term TLR2 effect. Reciprocally, 5-HT long-term treatment yielded TLR2 down regulation in Caco-2/TC7 cells. Finally, results from in vivo showed an augmented intestinal SERT expression in mice Tlr2-/-, thus confirming our inhibitory effect of TLR2 on intestinal SERT in vitro. The present work infers that TLR2 may act in intestinal pathophysiology, not only by its inherent innate immune role, but also by regulating the intestinal serotoninergic system. PMID:28033388

  12. Intra-Amniotic Administration (Gallus gallus) of Cicer arietinum and Lens culinaris Prebiotics Extracts and Duck Egg White Peptides Affects Calcium Status and Intestinal Functionality.

    PubMed

    Hou, Tao; Kolba, Nikolai; Glahn, Raymond P; Tako, Elad

    2017-07-21

    Calcium (Ca) is one of the most abundant inorganic elements in the human body and has many important physiological roles. Prebiotics and bioactive peptides are two important substances used to promote calcium uptake. However, the difference in mechanisms of the calcium uptake from these two supplements is not clear. By using the Gallus gallus model and the intra-amniotic administration procedure, the aim of this study was to investigate whether Ca status, intestinal functionality, and health-promoting bacterial populations were affected by prebiotics extracted from chickpea and lentil, and duck egg white peptides (DPs). Eleven groups (non-injected; 18 MΩ H₂O; 4 mmol/L CaCl₂; 50 mg/mL chickpea + 4 mmol/L CaCl₂; 50 mg/mL lentil + 4 mmol/L CaCl₂; 40 mg/mL DPs + 4 mmol/L CaCl₂; 5 mg/mL Val-Ser-Glu-Glu (VSEE) + 4 mmol/L CaCl₂; 50 mg/mL chickpea; 50 mg/mL lentil; 40 mg/mL DPs; 5 mg/mL VSEE) were utilized. Upon hatch, blood, cecum, small intestine, liver and bone were collected for assessment of serum bone alkaline phosphate level (BALP), the relative abundance of intestinal microflora, expression of Ca-related genes, brush border membrane (BBM) functional genes, and liver and bone mineral levels, respectively. The BALP level increased in the presence of lentil, DPs and VSEE (p < 0.05). The relative abundance of probiotics increased significantly (p < 0.05) by VSEE + Ca and chickpea. The expression of CalbindinD9k (Ca transporter) increased (p < 0.05) in Ca, chickpea + Ca and lentil + Ca groups. In addition, the brush border membrane functionality genes expressions increased (p < 0.05) by the chickpea or lentil extracts. Prebiotics and DPs beneficially affected the intestinal microflora and duodenal villus surface area. This research expands the understanding of the prebiotics' properties of chickpea and lentil extracts, and peptides' effects on calcium metabolism and gut health.

  13. Intestinal glutathione: determinant of mucosal peroxide transport, metabolism, and oxidative susceptibility

    SciTech Connect

    Aw, Tak Yee . E-mail: taw@lsuhsc.edu

    2005-05-01

    The intestine is a primary site of nutrient absorption and a critical defense barrier against dietary-derived mutagens, carcinogens, and oxidants. Accumulation of oxidants like peroxidized lipids in the gut lumen can contribute to impairment of mucosal metabolic pathways, enterocyte dysfunction independent of cell injury, and development of gut pathologies, such as inflammation and cancer. Despite this recognition, we know little of the pathways of intestinal transport, metabolism, and luminal disposition of dietary peroxides in vivo or of the underlying mechanisms of lipid peroxide-induced genesis of intestinal disease processes. This chapter summarizes our current understanding of the determinants of intestinal absorption and metabolism of peroxidized lipids. I will review experimental evidence from our laboratory and others (Table 1) supporting the pivotal role that glutathione (GSH) and reduced nicotinamide adenine dinucleotide phosphate (NADPH) play in mucosal transport and metabolism of lipid hydroperoxides and how reductant availability can be compromised under chronic stress such as hypoxia, and the influence of GSH on oxidative susceptibility, and redox contribution to genesis of gut disorders. The discussion is pertinent to understanding dietary lipid peroxides and GSH redox balance in intestinal physiology and pathophysiology and the significance of luminal GSH in preserving the integrity of the intestinal epithelium.

  14. Glutathione-enriched baker's yeast: production, bioaccessibility and intestinal transport assays.

    PubMed

    Musatti, A; Devesa, V; Calatayud, M; Vélez, D; Manzoni, M; Rollini, M

    2014-02-01

    A glutathione (GSH) yeast-based biomass (Saccharomyces cerevisiae) was used to investigate GSH stability, solubilization during gastrointestinal digestion and GSH intestinal transport. A postgrowing procedure was applied to improve intracellular GSH yeast content. The presence of adenine (ADE) in the biotransformation solution (CYS-GLY-GLU mixture) and alternatively, a glucose shot after 4-h incubation, allowed to obtain cells containing about GSH 1.6-1.7% dcw (dry cell weight) (control 0.5%). Yeast samples were subjected to in vitro gastrointestinal digestion and absorption assays employing Caco-2 and HT29-MTX cell lines in different proportions (100/0, 70/30 and 50/50). Trials were also performed to verify intestinal cell viability. At least 87% of ingested GSH is available in reduced form for intestinal absorption. In vitro GSH transport assays indicated that GSH is poorly absorbed (<20%). Nevertheless, studies in response to oxidative stress induced by H2 O2 demonstrated a protective role of the GSH-enriched biomass towards intestinal cell viability. An enriched GSH yeast-based biomass has been obtained using a postgrowing procedure. Although GSH present in enriched yeasts is poorly absorbed by intestinal cells, this biomass showed an intestinal local protective effect, improving cells viability when a simulated oxidative stress was applied. © 2013 The Society for Applied Microbiology.

  15. Effects of phorbol esters on fluid transport and blood flow in the small intestine

    SciTech Connect

    Sjoeqvist, A.; Henderson, L.S.; Fondacaro, J.D.

    1986-07-01

    Studies were designed to examine the effects of phorbol esters on intestinal fluid transport and blood flow in the anesthetized cat and enteropooling in the conscious rat. Intraluminal administration of phorbol ester into a segment of isolated small bowel produced a copious intestinal secretion and a concomitant mesenteric hyperemia in the cat. Net fluid movement in the intestine was converted from absorption in the control state to secretion following phorbol ester administration. Intravenous atropine reduced the phorbol ester-induced secretion by 56%; clonidine abolished the remaining secretory response. In the rat, intragastric administration of phorbol ester produced enteropooling comparable to that of other potent intestinal secretagogues. Since phorbol esters are known to activate protein kinase C, these suggest that activation of protein kinase C in the small intestine may lead to a full secretory response. The evidence suggests that this secretion is accompanied by a metabolic hyperemia. These results suggest that protein kinase C plays an important role in the regulation of intestinal fluid transport.

  16. Direct demonstration of guanine nucleotide sensitive receptors for vasoactive intestinal peptide in the anterior lobe of the rat pituitary gland

    SciTech Connect

    Agui, T.; Matsumoto, K. )

    1990-05-01

    The vasoactive intestinal peptide (VIP) receptors were identified on the membranes from the rat anterior pituitary gland with ({sup 125}I)VIP. The dissociation constant (Kd) and the maximal binding capacity (Bmax) values were estimated from the competitive inhibition data. The Kd and Bmax values were 1.05 +/- 0.75 nM and 103 +/- 11 fmol/mg protein, respectively. The order of molar potency of related peptides to inhibit ({sup 125}I)VIP binding was VIP greater than peptide histidine isoleucine (PHI) greater than secretin greater than glucagon. Glucagon was not effective to inhibit the binding. ({sup 125}I)VIP binding was effectively inhibited by the addition of guanine nucleotides. The order of molar potency to inhibit the binding was Gpp(NH)p greater than GTP greater than GDP greater than GMP greater than ATP. These results directly suggest the coupling of VIP receptors with guanine nucleotide binding proteins in the anterior pituitary gland.

  17. Adaptation of intestinal nutrient transport in health and disease. Part I.

    PubMed

    Thomson, A B; Wild, G

    1997-03-01

    Why is it important to understand the mechanisms controlling intestinal adaptation? There are two major answers to this question. Firstly, in establishing the cellular and molecular events associated with intestinal adaptation, we will formulate a general framework that may be applied to the understanding of adaptation of other cell membranes. For example, alterations in the synthesis of glucose carriers and their subsequent insertion into membranes may alter sugar entry across the intestinal brush border membrane (BBM) using the sodium-dependent D-glucose transporter, SGLT1, or the BBM sodium-independent facultative fructose transporter, GLUT5, and may alter facilitated sugar exit across the basolateral membrane (BLM) using GLUT2. The precise role of transcriptional and translational processes in the up- or down-regulation of sugar transport requires further definition. Alterations in enterocyte microsomal lipid metabolic enzyme expression occurring during the course of intestinal adaptation will direct the synthesis of lipids destined for trafficking to the BBM and BLM domains of the enterocyte. This will subsequently alter the passive permeability properties of these membranes and ultimately influence lipid absorption. Therefore, establishing the physiological, cellular and molecular mechanisms of adaptation in the intestine will define principles that may be applied to other epithelia. Secondly, enterocyte membrane adaptation is subject to dietary modification, and these may be exploited as a means to enhance a beneficial or to reduce a detrimental aspect of the intestinal adaptive process in disease states. Alterations in membrane function occur in association with changes in dietary lipids, and these are observed in a variety of cells and tissues including lymphocytes, testes, liver, adipocytes, nerve tissue, nuclear envelope and mitochondria. Therefore, the elucidation of the mechanisms of intestinal adaptation and the manner whereby dietary manipulation

  18. Aboral changes in D-glucose transport by human intestinal brush-border membrane vesicles.

    PubMed Central

    Bluett, M K; Abumrad, N N; Arab, N; Ghishan, F K

    1986-01-01

    D-Glucose transport was investigated in isolated brush-border membrane vesicles from human small intestine. Characteristics of D-glucose transport from the jejunum were compared with that in the mid and terminal ileum. Jejunal and mid-ileal D-glucose transport was Na+-dependent and electrogenic. The transient overshoot of jejunal D-glucose transport was significantly greater than corresponding values in mid-ileum. The terminal ileum did not exhibit Na+-dependent D-glucose transport, but did exhibit Na+-dependent taurocholate transport. Na+-glucose co-transport activity as measured by tracer-exchange experiments was greatest in the jejunum, and diminished aborally. We conclude that D-glucose transport in man is Na+-dependent and electrogenic in the proximal intestine and directly related to the activity of D-glucose-Na+ transporters present in the brush-border membranes. D-Glucose transport in the terminal ileum resembles colonic transport of D-glucose. PMID:3800877

  19. Protein abundance of clinically relevant multidrug transporters along the entire length of the human intestine.

    PubMed

    Drozdzik, Marek; Gröer, Christian; Penski, Jette; Lapczuk, Joanna; Ostrowski, Marek; Lai, Yurong; Prasad, Bhagwat; Unadkat, Jashvant D; Siegmund, Werner; Oswald, Stefan

    2014-10-06

    Intestinal transporters are crucial determinants in the oral absorption of many drugs. We therefore studied the mRNA expression (N = 33) and absolute protein content (N = 10) of clinically relevant transporters in healthy epithelium of the duodenum, the proximal and distal jejunum and ileum, and the ascending, transversal, descending, and sigmoidal colon of six organ donors (24-54 years). In the small intestine, the abundance of nearly all studied proteins ranged between 0.2 and 1.6 pmol/mg with the exception of those of OCT3 (<0.1 pmol/mg) and PEPT1 (2.6-4.9 pmol/mg) that accounted for ∼50% of all measured transporters. OATP1A2 was not detected in any intestinal segment. ABCB1, ABCG2, PEPT1, and ASBT were significantly more abundant in jejunum and ileum than in colon. In contrast to this, the level of expression of ABCC2, ABCC3, and OCT3 was found to be highest in colon. Site-dependent differences in the levels of gene and protein expression were observed for ABCB1 and ASBT. Significant correlations between mRNA and protein levels have been found for ABCG2, ASBT, OCT3, and PEPT1 in the small intestine. Our data provide further physiological pieces of the puzzle required to predict intestinal drug absorption in humans.

  20. Chemical form of selenium affects its uptake, transport and glutathione peroxidase activity in the human intestinal Caco-2 cell model

    USDA-ARS?s Scientific Manuscript database

    Determining the effect of selenium (Se) chemical form on uptake and transport in human intestinal cells is critical to assess Se bioavailability. In the present study, we measured the uptake and transport of various Se compounds in the human intestinal Caco-2 cell model. We found that two sources...

  1. A pilot study examining the relationship among Crohn disease activity, glucagon-like peptide-2 signalling and intestinal function in pediatric patients

    PubMed Central

    Sigalet, David L; Kravarusic, Dragan; Butzner, Decker; Hartmann, Bolette; Holst, Jens J; Meddings, Jon

    2013-01-01

    BACKGROUND/OBJECTIVES: The relationship between the enteroendocrine hormone glucagon-like peptide 2 (GLP-2) and intestinal inflammation is unclear. GLP-2 promotes mucosal growth, decreases permeability and reduces inflammation in the intestine; physiological stimulation of GLP-2 release is triggered by nutrient contact. The authors hypothesized that ileal Crohn disease (CD) affects GLP-2 release. METHODS: With ethics board approval, pediatric patients hospitalized with CD were studied; controls were recruited from local schools. Inclusion criteria were endoscopy-confirmed CD (primarily of the small intestine) with a disease activity index >150. Fasting and post-prandial GLP-2 levels and quantitative urinary recovery of orally administered 3-O-methyl-glucose (active transport) and lactulose/mannitol (passive) were quantified during the acute and remission phases. RESULTS: Seven patients (mean [± SD] age 15.3±1.3 years) and 10 controls (10.3±1.6 years) were studied. In patients with active disease, fasting levels of GLP-2 remained stable but postprandial levels were reduced. Patients with active disease exhibited reduced glucose absorption and increased lactulose/mannitol recovery; all normalized with disease remission. The change in the lactulose/mannitol ratio was due to both reduced lactulose and increased mannitol absorption. CONCLUSIONS: These findings suggest that pediatric patients with acute ileal CD have decreased postprandial GLP-2 release, reduced glucose absorption and increased intestinal permeability. Healing of CD resulted in normalization of postprandial GLP-2 release and mucosal functioning (nutrient absorption and permeability), the latter due to an increase in mucosal surface area. These findings have implications for the use of GLP-2 and feeding strategies as a therapy in CD patients; further studies of the effects of inflammation and the GLP-2 axis are recommended. PMID:24106731

  2. Glucagon-Like Peptide-2 Regulates Release of Chylomicrons From the Intestine

    PubMed Central

    Dash, Satya; Xiao, Changting; Morgantini, Cecilia; Connelly, Philip W.; Patterson, Bruce W.; Lewis, Gary F.

    2015-01-01

    BACKGROUND & AIMS The intestine efficiently incorporates and rapidly secretes dietary fat as chylomicrons (lipoprotein particles comprising triglycerides, phospholipids, cholesterol, and proteins) that contain the apolipoprotein isoform apoB-48. The gut can store lipids for many hours after their ingestion, and release them in chylomicrons in response to oral glucose, sham feeding, or unidentified stimuli. The gut hormone glucagon-like peptide-2 (GLP-2) facilitates intestinal absorption of lipids, but its role in chylomicron secretion in human beings is unknown. METHODS We performed a randomized, single-blind, cross-over study, with 2 study visits 4 weeks apart, to assess the effects of GLP-2 administration on triglyceride-rich lipoprotein (TRL) apoB-48 in 6 healthy men compared with placebo. Subjects underwent constant intraduodenal feeding, with a pancreatic clamp and primed constant infusion of deuterated leucine. In a separate randomized, single-blind, cross-over validation study, 6 additional healthy men ingested a high-fat meal containing retinyl palmitate and were given either GLP-2 or placebo 7 hours later with measurement of TRL triglyceride, TRL retinyl palmitate, and TRL apoB-48 levels. RESULTS GLP-2 administration resulted in a rapid (within 30 minutes) and transient increase in the concentration of TRL apoB-48, compared with placebo (P = .03). Mathematic modeling of stable isotope enrichment and the mass of the TRL apoB-48 suggested that the increase resulted from the release of stored, presynthesized apoB-48 from the gut. In the validation study, administration of GLP-2 at 7 hours after the meal, in the absence of additional food intake, robustly increased levels of TRL triglycerides (P = .007), TRL retinyl palmitate (P = .002), and TRL apoB-48 (P = .04) compared with placebo. CONCLUSIONS Administration of GLP-2 to men causes the release of chylomicrons that comprise previously synthesized and stored apoB-48 and lipids. This transiently increases TRL

  3. Gum Arabic enhances paracellular transport of water in amphibian everted small intestinal segments.

    PubMed

    Pai, M Kirtana; Chetan, S; Rao, J Prakasa; Kumar, Ritesh; Kumar, Vikas; Kumar, Rishikesh

    2013-01-01

    Gum Arabic (GA) is known for its proabsorbent activity in normal intestine as well as in animal models of diarrhea. The aim of the study was to find the effect of GA on intestinal transport of water and possible route of absorption in frog everted gut sacs. D-Mannitol was used as a marker of paracellular transport to find the route of absorption. Everted gut sacs (n = 4,5) were placed in Ringer containing GA (2.5 g/L) with or without D-Mannitol (0.5 g/L), incubated for 1 hour and analysed for change in weights of the sacs and D-Mannitol uptake. There was significant increase in uptake of water and D-Mannitol in the presence of GA compared to controls (P < 0.05). Gum Arabic improves water uptake by the intestinal mucosa, possibly by opening the paracellular pathways.

  4. Crystal Structures of the Extracellular Domain from PepT1 and PepT2 Provide Novel Insights into Mammalian Peptide Transport.

    PubMed

    Beale, John H; Parker, Joanne L; Samsudin, Firdaus; Barrett, Anne L; Senan, Anish; Bird, Louise E; Scott, David; Owens, Raymond J; Sansom, Mark S P; Tucker, Stephen J; Meredith, David; Fowler, Philip W; Newstead, Simon

    2015-10-06

    Mammals obtain nitrogen via the uptake of di- and tri-peptides in the gastrointestinal tract through the action of PepT1 and PepT2, which are members of the POT family of proton-coupled oligopeptide transporters. PepT1 and PepT2 also play an important role in drug transport in the human body. Recent crystal structures of bacterial homologs revealed a conserved peptide-binding site and mechanism of transport. However, a key structural difference exists between bacterial and mammalian homologs with only the latter containing a large extracellular domain, the function of which is currently unknown. Here, we present the crystal structure of the extracellular domain from both PepT1 and PepT2 that reveal two immunoglobulin-like folds connected in tandem, providing structural insight into mammalian peptide transport. Functional and biophysical studies demonstrate that these domains interact with the intestinal protease trypsin, suggesting a role in clustering proteolytic activity to the site of peptide transport in eukaryotic cells.

  5. Correlation between electrophysiological phenomena and transport of macromolecules in intestinal epithelium.

    PubMed

    Groot, J A

    1998-01-01

    This review discuss some recent findings in the study of the regulation of the permeability of the intestinal epithelial layer. Comparison of electrical phenomena and transport of macromolecules suggests that secretory activity and increased transepithelial transport of macromolecules are related when secretion is mediated by the Ca2+ and PKC dependent pathways. The transport of the macromolecules is via the transcellular and via the paracellular route. The barrier function of the intestinal epithelium may be diminished during nervous (acetylcholine)- and immuno-(histamine) mediated secretion. It is hypothesised that some bacterial toxins may also induce Ca2+ and PKC dependent secretion and thereby can reduce the epithelial barrier. The cAMP and cGMP mediated secretion, which can be recognised by their long-lasting transepithelial potential changes, are not coupled to increased transepithelial transport of macromolecules. Some forms of secretory diarrhea may therefore be related to the development of food-allergy or inflammation.

  6. Modulation of Chicken Intestinal Immune Gene Expression by Small Cationic Peptides as Feed Additives during the First Week Posthatch

    PubMed Central

    Genovese, Kenneth J.; He, Haiqi; Swaggerty, Christina L.; Jiang, Yiwei

    2013-01-01

    We have been investigating modulation strategies tailored around the selective stimulation of the host's immune system as an alternative to direct targeting of microbial pathogens by antibiotics. One such approach is the use of a group of small cationic peptides (BT) produced by a Gram-positive soil bacterium, Brevibacillus texasporus. These peptides have immune modulatory properties that enhance both leukocyte functional efficiency and leukocyte proinflammatory cytokine and chemokine mRNA transcription activities in vitro. In addition, when provided as a feed additive for just 4 days posthatch, BT peptides significantly induce a concentration-dependent protection against cecal and extraintestinal colonization by Salmonella enterica serovar Enteritidis. In the present studies, we assessed the effects of feeding BT peptides on transcriptional changes on proinflammatory cytokines, inflammatory chemokines, and Toll-like receptors (TLR) in the ceca of broiler chickens with and without S. Enteritidis infection. After feeding a BT peptide-supplemented diet for the first 4 days posthatch, chickens were then challenged with S. Enteritidis, and intestinal gene expression was measured at 1 or 7 days postinfection (p.i.) (5 or 11 days of age). Intestinal expression of innate immune mRNA transcripts was analyzed by quantitative real-time PCR (qRT-PCR). Analysis of relative mRNA expression showed that a BT peptide-supplemented diet did not directly induce the transcription of proinflammatory cytokine, inflammatory chemokine, type I/II interferon (IFN), or TLR mRNA in chicken cecum. However, feeding the BT peptide-supplemented diet primed cecal tissue for increased (P ≤ 0.05) transcription of TLR4, TLR15, and TLR21 upon infection with S. Enteritidis on days 1 and 7 p.i. Likewise, feeding the BT peptides primed the cecal tissue for increased transcription of proinflammatory cytokines (interleukin 1β [IL-1β], IL-6, IL-18, type I and II IFNs) and inflammatory chemokine (CxCLi2

  7. Yeast culture supplement during nursing and transport affects immunity and intestinal microbial ecology of weanling pigs

    USDA-ARS?s Scientific Manuscript database

    Weaning and transport stress can have a negative impact on the piglet's immune system and intestinal microbiota. The objective of this study was to determine the influence of a yeast product on innate immunity and microbial ecology of the gastrointestinal tract following stress of weaning and trans...

  8. Intestinal microbial affects of yeast products on weaned and transport stressed pigs

    USDA-ARS?s Scientific Manuscript database

    Study objectives were to determine effects of a commercially available yeast product (XPC, Diamond-V Mills) and stress of transportation on total Enterobacteriaceae, Escherichia coli, coliforms, and Lactobacilli populations in the intestine of weaning pigs. In a RCB design with a 2 x 2 factorial ar...

  9. Glucose Transport into Everted Sacs of the Small Intestine of Mice

    ERIC Educational Resources Information Center

    Hamilton, Kirk L.; Butt, A. Grant

    2013-01-01

    The Na[superscript +]-glucose cotransporter is a key transport protein that is responsible for absorbing Na[superscript +] and glucose from the luminal contents of the small intestine and reabsorption by the proximal straight tubule of the nephron. Robert K. Crane originally described the cellular model of absorption of Na[superscript +] and…

  10. Glucose Transport into Everted Sacs of the Small Intestine of Mice

    ERIC Educational Resources Information Center

    Hamilton, Kirk L.; Butt, A. Grant

    2013-01-01

    The Na[superscript +]-glucose cotransporter is a key transport protein that is responsible for absorbing Na[superscript +] and glucose from the luminal contents of the small intestine and reabsorption by the proximal straight tubule of the nephron. Robert K. Crane originally described the cellular model of absorption of Na[superscript +] and…

  11. Roles of sphincter of Oddi motility and serum vasoactive intestinal peptide, gastrin and cholecystokinin octapeptide

    PubMed Central

    Zhang, Zhen-Hai; Qin, Cheng-Kun; Wu, Shuo-Dong; Xu, Jian; Cui, Xian-Ping; Wang, Zhi-Yi; Xian, Guo-Zhe

    2014-01-01

    AIM: To investigate roles of sphincter of Oddi (SO) motility played in pigment gallbladder stone formation in model of guinea pigs. METHODS: Thirty-four adult male Hartley guinea pigs were divided randomly into two groups: the control group and pigment stone group. The pigment stone group was divided into 4 subgroups with 6 guinea pigs each according to time of sacrifice, and were fed a pigment lithogenic diet and sacrificed after 3, 6, 9 and 12 wk. SO manometry and recording of myoelectric activity of the guinea pigs were obtained by multifunctional physiograph at each stage. Serum vasoactive intestinal peptide (VIP), gastrin and cholecystokinin octapeptide (CCK-8) were detected at each stage in the process of pigment gallbladder stone formation by enzyme-linked immunosorbent assay. RESULTS: The incidence of pigment gallstone formation was 0%, 0%, 16.7% and 66.7% in the 3-, 6-, 9- and 12-wk group, respectively. The frequency of myoelectric activity decreased in the 3-wk group. The amplitude of myoelectric activity had a tendency to decrease but not significantly. The frequency of the SO decreased significantly in the 9-wk group. The SO basal pressure and common bile duct pressure increased in the 12-wk group (25.19 ± 7.77 mmHg vs 40.56 ± 11.81 mmHg, 22.35 ± 7.60 mmHg vs 38.51 ± 11.57 mmHg, P < 0.05). Serum VIP was significantly elevated in the 6- and 12-wk groups and serum CCK-8 was decreased significantly in the 12-wk group. CONCLUSION: Pigment gallstone-causing diet may induce SO dysfunction. The tension of the SO increased. The disturbance in SO motility may play a role in pigment gallstone formation, and changes in serum VIP and CCK-8 may be important causes of SO dysfunction. PMID:24782626

  12. Cytoprotective effect of neuropeptides on cancer stem cells: vasoactive intestinal peptide-induced antiapoptotic signaling.

    PubMed

    Sastry, Konduru S; Chouchane, Aouatef Ismail; Wang, Ena; Kulik, George; Marincola, Francesco M; Chouchane, Lotfi

    2017-06-01

    Cancer stem cells (CSCs) are increasingly considered to be responsible for tumor initiation, metastasis and drug resistance. The drug resistance mechanisms activated in CSCs have not been thoroughly investigated. Although neuropeptides such as vasoactive intestinal peptide (VIP) can promote tumor growth and activate antiapoptotic signaling in differentiated cancer cells, it is not known whether they can activate antiapoptotic mechanisms in CSCs. The objectives of this study are to unravel the cytoprotective effects of neuropeptides and identify antiapoptotic mechanisms activated by neuropeptides in response to anticancer drug treatment in CSCs. We enriched and purified CSCs (CD44(+/high)/CD24(-/low) or CD133(+) population) from breast and prostate cancer cell lines, and demonstrated their stemness phenotype. Of the several neuropeptides tested, only VIP could protect CSCs from drug-induced apoptosis. A functional correlation was found between drug-induced apoptosis and dephosphorylation of proapoptotic Bcl2 family protein BAD. Similarly, VIP-induced cytoprotection correlated with BAD phosphorylation at Ser112 in CSCs. Using pharmacological inhibitors and dominant-negative proteins, we showed that VIP-induced cytoprotection and BAD phosphorylation are mediated via both Ras/MAPK and PKA pathways in CSCs of prostate cancer LNCaP and C4-2 cells, but only PKA signaling was involved in CSCs of DUVIPR (DU145 prostate cancer cells ectopically expressing VIP receptor) and breast cancer MCF7 cells. As each of these pathways partially control BAD phosphorylation at Ser112, both have to be inhibited to block the cytoprotective effects of VIP. Furthermore, VIP is unable to protect CSCs that express phosphorylation-deficient mutant-BAD, suggesting that BAD phosphorylation is essential. Thus, antiapoptotic signaling by VIP could be one of the drug resistance mechanisms by which CSCs escape from anticancer therapies. Our findings suggest the potential usefulness of VIP receptor

  13. Corneal Endothelial Cell Integrity in Precut Human Donor Corneas Enhanced by Autocrine Vasoactive Intestinal Peptide

    PubMed Central

    Coll, Timothy; Gloria, Dante; Sprehe, Nicholas

    2017-01-01

    Purpose: To demonstrate that vasoactive intestinal peptide (VIP), a corneal endothelial (CE) cell autocrine factor, maintains the integrity of corneal endothelium in human donor corneoscleral explants precut for endothelial keratoplasty. Methods: Twelve paired human donor corneoscleral explants used as control versus VIP-treated explants (10 nM, 30 minutes, 37°C) were shipped (4°C) to the Lions Eye Institute for Transplantation and Research for precutting (Moria CBM-ALTK Keratome), shipped back to the laboratory, and cultured in ciliary neurotrophic factor (CNTF, 0.83 nM, 37°C, 24 hours). Trephined endothelial discs (8–8.5 mm) were analyzed for differentiation markers (N-cadherin, CNTF receptor α subunit [CNTFRα], and connexin 43) by Western blot after a quarter of the discs from 4 paired explants were cut away and stained with alizarin red S for microscopic damage analysis. Two additional paired explants (6 days in culture) were stained for panoramic view of central CE damage. Results: VIP treatment increased N-cadherin and CNTFRα levels (mean ± SEM) to 1.38 ± 0.11-fold (P = 0.003) and 1.46 ± 0.22-fold (P = 0.03) of paired controls, respectively, whereas CE cell CNTF responsiveness in upregulation of connexin 43 increased to 2.02 ± 0.5 (mean ± SEM)-fold of the controls (P = 0.04). CE damage decreased from (mean ± SEM) 10.0% ± 1.2% to 1.6% ± 0.3% (P < 0.0001) and 9.1% ± 1.1% to 2.4% ± 1.0% (P = 0.0006). After 6 days in culture, the damage in whole CE discs decreased from 20.0% (control) to 5.5% (VIP treated). Conclusions: VIP treatment before precut enhanced the preservation of corneal endothelium. PMID:28181929

  14. Serum Levels of Vasoactive Intestinal Peptide as a Prognostic Marker in Early Arthritis

    PubMed Central

    Martínez, Carmen; Ortiz, Ana M.; Juarranz, Yasmina; Lamana, Amalia; Seoane, Iria V.; Leceta, Javier; García-Vicuña, Rosario

    2014-01-01

    Objective Suitable biomarkers are essential for the design of therapeutic strategies in personalized medicine. Vasoactive intestinal peptide (VIP) has demonstrated immunomodulatory properties in autoimmune murine and ex vivo human models. Our aim was to study serum levels of VIP during the follow-up of an early arthritis (EA) cohort and to analyze its value as a biomarker predicting severity and therapeutic requirements. Methods Data from 91 patients on an EA register were analyzed (76% rheumatoid arthritis (RA), 24% undifferentiated arthritis, 73% women, and median age 54 years; median disease duration at entry, 5.4 months). We collected per protocol sociodemographic, clinical, and therapeutic data. VIP levels were determined by enzyme immunoassay in sera harvested from the 91 patients (353 visits; 3.9 visit/patient) and from 100 healthy controls. VIP values below the 25th percentile of those assessed in healthy population were considered low. To determine the effect of independent variables on VIP levels, we performed a longitudinal multivariate analysis nested by patient and visit. A multivariate ordered logistic regression was modeled to determine the effect of low VIP serum levels on disease activity at the end of follow-up. Results VIP concentrations varied considerably across EA patients. Those fulfilling the criteria for RA had the lowest values in the whole sample, although no significant differences were observed compared with healthy donors. Disease activity, which was assessed using DAS28, inversely correlated with VIP levels. After a two-year follow-up, those patients with low baseline levels of VIP displayed higher disease activity and received more intensive treatment. Conclusion Patients who are unable to up-regulate VIP seem to have a worse clinical course despite receiving more intense treatment. Therefore, measurement of VIP levels may be suitable as a prognostic biomarker. PMID:24409325

  15. Effect of vasoactive intestinal peptide on the wound healing of alkali-burned corneas

    PubMed Central

    Tuncel, Nese; Yildirim, Nilgun; Gurer, Firdevs; Basmak, Hikmet; Uzuner, Kubilay; Sahinturk, Varol; Gursoy, Huseyin

    2016-01-01

    AIM To study the effect of vasoactive intestinal peptide (VIP) on wound healing in experimental alkali burns of the cornea. METHODS Twenty-seven albino rabbits, weighing 3.2±0.75 kg were used. Alkali burns were induced on corneas by applying 10 mm Whatman paper No:50 soaked in 1 mol/L NaOH. They have further classified into 5 groups as follows: 1) control group given no treatment (n=5); 2) VIP given subconjunctivally (n=6); 3) VIP injected into anterior chamber (n=6); 4) NaCl 0.9% given subconjunctivally (n=5); 5) NaCl 0.9% given into the anterior chamber (n=5). All treatment protocols except control group were followed by topical eye drops composed of VIP at two hourly intervals for one week from 8 a.m. to 6 p.m. RESULTS VIP treated groups of rabbits with alkali burns were found to have better wound healing findings histo-pathologically when compared to those of control group who have received no treatment on day 30. No differences were observed between groups in respect to degree of polymorphonuclear leukocytes (PMNL) infiltration and degree of loss of amorphous substrate on day 15. However, PMNL infiltration and degree of loss of amorphous substrate were lower in Groups 2 and 3 when compared to that of control group on day 30 (P<0.05). CONCLUSION We have shown that VIP has positive effects on alkali induced corneal burns. VIP may inhibit PMNL migration to cornea through an immunomodulatory effect. Inhibition of PMNL migration might reduce the release of collagenases and this might prevent the extracellular amorphous substance loss. PMID:26949636

  16. Chronic stimulation of the hypothalamic vasoactive intestinal peptide receptor lengthens circadian period in mice and hamsters

    PubMed Central

    Pantazopoulos, Harry; Dolatshad, Hamid

    2010-01-01

    Evidence suggests that circadian rhythms are regulated through diffusible signals generated by the suprachiasmatic nucleus (SCN). Vasoactive intestinal peptide (VIP) is located in SCN neurons positioned to receive photic input from the retinohypothalamic tract and transmit information to other SCN cells and adjacent hypothalamic areas. Studies using knockout mice indicate that VIP is essential for synchrony among SCN cells and for the expression of normal circadian rhythms. To test the hypothesis that VIP is also an SCN output signal, we recorded wheel-running activity rhythms in hamsters and continuously infused the VIP receptor agonist BAY 55-9837 in the third ventricle for 28 days. Unlike other candidate output signals, infusion of BAY 55-9837 did not affect activity levels. Instead, BAY 55-9837 lengthened the circadian period by 0.69 ± 0.04 h (P < 0.0002 compared with controls). Period returned to baseline after infusions. We analyzed the effect of BAY 55-9837 on cultured SCN from PER2::LUC mice to determine if lengthening of the period by BAY 55-9837 is a direct effect on the SCN. Application of 10 μM BAY 55-9837 to SCN in culture lengthened the period of PER2 luciferase expression (24.73 ± 0.24 h) compared with control SCN (23.57 ± 0.26, P = 0.01). In addition, rhythm amplitude was significantly increased, consistent with increased synchronization of SCN neurons. The effect of BAY 55-9837 in vivo on period is similar to the effect of constant light. The present results suggest that VIP-VPAC2 signaling in the SCN may play two roles, synchronizing SCN neurons and setting the period of the SCN as a whole. PMID:20463182

  17. Modulation of Corpus Striatal Neurochemistry by Astrocytes and Vasoactive Intestinal Peptide (VIP) in Parkinsonian Rats.

    PubMed

    Yelkenli, İbrahim Halil; Ulupinar, Emel; Korkmaz, Orhan Tansel; Şener, Erol; Kuş, Gökhan; Filiz, Zeynep; Tunçel, Neşe

    2016-06-01

    The neurotoxin 6-hydroxydopamine (6-OHDA) is widely used in animal models of Parkinson's disease. In various neurodegenerative diseases, astrocytes play direct, active, and critical roles in mediating neuronal survival and functions. Vasoactive intestinal peptide (VIP) has neurotrophic actions and modulates a number of astrocytic activities. In this study, the effects of VIP on the striatal neurochemistry were investigated in parkinsonian rats. Adult Sprague-Dawley rats were divided into sham-operated, unilaterally 6-OHDA-lesioned, and lesioned + VIP-administered (25 ng/kg i.p.) groups. VIP was first injected 1 h after the intrastriatal 6-OHDA microinjection and then every 2 days throughout 15 days. Extracellular striatal concentration of glutathione (GSH), gamma-aminobutyric acid (GABA), glutamate (GLU), and lactate were measured in microdialysates by high-performance liquid chromatography (HPLC). Quantification of GABA and activity dependent neuroprotective protein (ADNP)-expressing cells were determined by glutamic acid decarboxylase (GAD)/ADNP + glial fibrillary acidic protein (GFAP) double immunohistochemistry. Our results demonstrated that a 6-OHDA lesion significantly increased the density of astrocytes in the striatum and VIP treatment slightly reduced the gliosis. Extracellular concentration of GABA, GLU, and lactate levels did not change, but GSH level significantly increased in the striatum of parkinsonian rats. VIP treatment reduced GSH level comparable to sham-operated groups, but enhanced GABA and GLU levels. Our double labeling results showed that VIP primarily acts on neurons to increase ADNP and GAD expression for protection. These results suggest that, in the 6-OHDA-induced neurodegeneration model, astrocytes were possibly activated for forefront defensiveness by modulating striatal neurochemistry.

  18. Chemical synthesis and characterization of silver-protected vasoactive intestinal peptide nanoparticles.

    PubMed

    Fernandez-Montesinos, Rafael; Castillo, Paula M; Klippstein, Rebecca; Gonzalez-Rey, Elena; Mejias, Jose A; Zaderenko, Ana P; Pozo, David

    2009-12-01

    We characterized a method to conjugate functional silver nanoparticles with vasoactive intestinal peptide (VIP), which could be used as a working model for further tailor-made applications based on VIP surface functionality. Despite sustained interest in the therapeutic applications of VIP, and the fact that its drugability could be largely improved by the attachament to functionalized metal nanoparticles, no methods have been described so far to obtain them. VIP was conjugated to tiopronin-capped silver nanoparticles of a narrow size distribution, by means of proper linkers, to obtain VIP functionalized silver nanoparticles with two different VIP orientations (Ag-tiopronin-PEG-succinic-[His]VIP and Ag-tiopronin-PEG-VIP[His]). VIP intermediate nanoparticles were characterized by transmission-electron microscopy and Fourier transform infrared spectroscopy. VIP functionalized silver nanoparticles cytotoxicity was determined by lactate dehydrogenase release from mixed glial cultures prepared from cerebral cortices of 1-3 days-old C57/Bl mice. Cells were used for lipopolysaccharide stimulation at day 18-22 of culture. Two different types of VIP-functionalized silver nanoparticles were obtained; both expose the C-terminal part of the neuropeptide, but in the first type VIP is attached to silver nanoparticle through its free amine terminus (Ag-tiopronin-PEG-succinic-[His]VIP), while in the second type, VIP N-terminus remains free (Ag-tiopronin-PEG-VIP[His]). VIP-functionalized silver nanoparticles did not compromise cellular viability and inhibited microglia-induced stimulation under inflammatory conditions. The chemical synthesis procedure developed to obtain VIP-functionalized silver nanoparticles rendered functional products, in terms of biological activity. The two alternative orientations designed, reduced the constraints for chemical synthesis that depends on the nanosurface to be functionalized. Our study provides, for the first time, a proof of principle to

  19. Evidence for an interleukin 4-inducible immunoglobulin E uptake and transport mechanism in the intestine

    PubMed Central

    1994-01-01

    Immunoglobulin (Ig) E is the principal Ig involved in immediate hypersensitivities and chronic allergic diseases such as asthma. Helminths are the most potent infectious agents known for their capacity to stimulate IgE production during the course of infection. In rats, the nematode Trichinella spiralis typically elicits a strong parasite-specific IgE response during infection, and this IgE antibody has been shown to be protective against the parasite in passive transfer experiments. The study reported here analyzed the fate of 125I- labeled myeloma IgE (1R162) in normal and T. spiralis-infected rats after intravenous injection. T. spiralis infection induced a capacity for specific binding to the gut wall of 125I-IgE rather than 125I-IgG1, as well as the transport of IgE, but not IgG1, into the gut lumen. Peak intestinal uptake and transport of 125I-IgE occurred during the first and second weeks after injection but was not elevated in the fourth week, that is, after intestinal adult worms had been expelled. Neither 125I-IgE uptake in the gut wall nor transport to the lumen could be ascribed to tissue damage or vascular leakage. Luminal transport occurred in the small intestine and not the liver, which only transports low molecular weight degraded 125I-IgE. Calculations based on the amount of intact IgE in the lumen suggest that, in a 24-h period, up to 20% of injected 125I-IgE can be transported to the gut lumen during the peak transport period, between 6 and 14 d after infection. The intestinal IgE binding and transport response can be adoptively transferred with T. spiralis immune CD4+ OX22- (CD45RC-) lymphocytes, which are protective, but not the nonprotective sister population CD4+ OX22+ (CD45RC+) of lymphocytes isolated simultaneously from thoracic duct lymph of infected rats. The intravenous infusion of recombinant rat interleukin 4 also elicited significant intestinal uptake of 125I-IgE. We also present evidence for the presence of CD23 on rat

  20. Protein Restriction with Amino Acid-Balanced Diets Shrinks Circulating Pool Size of Amino Acid by Decreasing Expression of Specific Transporters in the Small Intestine

    PubMed Central

    Luo, Min; Zhang, Xin; Sun, Wen Juan; Jiao, Ning; Li, De Fa; Yin, Jing Dong

    2016-01-01

    Dietary protein restriction is not only beneficial to health and longevity in humans, but also protects against air pollution and minimizes feeding cost in livestock production. However, its impact on amino acid (AA) absorption and metabolism is not quite understood. Therefore, the study aimed to explore the effect of protein restriction on nitrogen balance, circulating AA pool size, and AA absorption using a pig model. In Exp.1, 72 gilts weighting 29.9 ± 1.5 kg were allocated to 1 of the 3 diets containing 14, 16, or 18% CP for a 28-d trial. Growth (n = 24), nitrogen balance (n = 6), and the expression of small intestinal AA and peptide transporters (n = 6) were evaluated. In Exp.2, 12 barrows weighting 22.7 ± 1.3 kg were surgically fitted with catheters in the portal and jejunal veins as well as the carotid artery and assigned to a diet containing 14 or 18% CP. A series of blood samples were collected before and after feeding for determining the pool size of circulating AA and AA absorption in the portal vein, respectively. Protein restriction did not sacrifice body weight gain and protein retention, since nitrogen digestibility was increased as dietary protein content reduced. However, the pool size of circulating AA except for lysine and threonine, and most AA flux through the portal vein were reduced in pigs fed the low protein diet. Meanwhile, the expression of peptide transporter 1 (PepT-1) was stimulated, but the expression of the neutral and cationic AA transporter systems was depressed. These results evidenced that protein restriction with essential AA-balanced diets, decreased AA absorption and reduced circulating AA pool size. Increased expression of small intestinal peptide transporter PepT-1 could not compensate for the depressed expression of jejunal AA transporters for AA absorption. PMID:27611307

  1. Newly identified PcToll4 regulates antimicrobial peptide expression in intestine of red swamp crayfish Procambarus clarkii.

    PubMed

    Huang, Ying; Li, Tingting; Jin, Min; Yin, Shaowu; Hui, Kai-Min; Ren, Qian

    2017-02-14

    Tolls or Toll-like receptors (TLRs) have an essential role in initiating innate immune responses against pathogens. In this study, a novel Toll gene, PcToll4, was first identified from the intestinal transcriptome of the freshwater crayfish, Procambarus clarkii. The PcToll4 cDNA is 4849bp long with a 3036bp open reading frame that encodes a 1011-amino acid protein. PcToll4 contains a signal peptide, 13 LRR domains, 3 LRR TYP domains, 2 LRR CT domains, an LRR NT domain, a transmembrane region, and a TIR domain. Quantitative RT-PCR analysis revealed that PcToll4 mRNA was detected in all tested tissues, and the expression of PcToll4 in the intestine was significantly upregulated after white spot syndrome virus (WSSV) challenge. Overexpression of PcToll4 in Drosophila Schneider 2 (S2) cells activates the antimicrobial peptides (AMPs) of Drosophila, including metchnikowin, drosomycin, attacin A, and shrimp Penaeidin-4. Results of RNA interference by siRNA also showed that PcToll4 regulates the expressions of 5 anti-lipopolysaccharide factors (ALFs) in the intestine of crayfish. Our findings suggest that PcToll4 is important for the innate immune responses of P. clarkii because this gene regulates the expressions of AMPs against WSSV.

  2. Disrupted circadian rhythmicity of the intestinal glucose transporter SGLT1 in Zucker diabetic fatty rats.

    PubMed

    Bhutta, Hina Y; Deelman, Tara E; Ashley, Stanley W; Rhoads, David B; Tavakkoli, Ali

    2013-06-01

    Intestinal absorptive capacity shows a circadian rhythm synchronized with eating patterns. Disrupting these coordinated rhythms, e.g., with shift work, may contribute to metabolic disease. Circadian expression of nutrient transporters has not been studied in metabolic disease. We studied the circadian rhythm of intestinal transporter sodium glucose co-transporter type 1 (SGLT1) in an obese diabetic rat. We compared obese Zucker diabetic fatty (ZDF) rats to lean ZDF littermates. Temporal feeding patterns were assessed, then rats were harvested at Zeitgeber (ZT, ZT0 = 7:00 a.m.) 3, 9, or 15 to measure insulin resistance, SGLT1 expression and intestinal glucose absorption capacity. Regulators of SGLT1 (sweet taste receptor T1R2/3; clock genes) were measured to elucidate underlying mechanisms. Both groups exhibited altered circadian food intake. Obese ZDF rats lost circadian rhythmicity of SGLT1 mRNA expression and functional activity. Lean ZDF rats maintained rhythmicity of SGLT1 mRNA expression but that of functional glucose absorption was blunted. Circadian rhythms of intestinal clock genes were maintained in both groups. Neither group had discernible rhythms of intestinal GLUT2 (glucose transporter) or T1R2 (sweet taste receptor component) mRNA expression. In summary, lean and obese ZDF rats exhibited similar disruptions in circadian feeding. Glucose intolerance was evident in lean rats, but only obese rats further developed diabetes and exhibited disrupted circadian rhythmicity of both SGLT1 mRNA expression and function. Our findings suggest that disrupted circadian feeding rhythms contribute to glucose intolerance, but additional factors (genetics, changes in nutrient sensing/transport) are needed to lead to full diabetes.

  3. Reversible Opening of Intercellular Junctions of Intestinal Epithelial and Brain Endothelial Cells With Tight Junction Modulator Peptides.

    PubMed

    Bocsik, Alexandra; Walter, Fruzsina R; Gyebrovszki, Andrea; Fülöp, Lívia; Blasig, Ingolf; Dabrowski, Sebastian; Ötvös, Ferenc; Tóth, András; Rákhely, Gábor; Veszelka, Szilvia; Vastag, Monika; Szabó-Révész, Piroska; Deli, Mária A

    2016-02-01

    The intercellular junctions restrict the free passage of hydrophilic compounds through the paracellular clefts. Reversible opening of the tight junctions of biological barriers is investigated as one of the ways to increase drug delivery to the systemic circulation or the central nervous system. Six peptides, ADT-6, HAV-6, C-CPE, 7-mer (FDFWITP, PN-78), AT-1002, and PN-159, acting on different integral membrane and linker junctional proteins were tested on Caco-2 intestinal epithelial cell line and a coculture model of the blood-brain barrier. All peptides tested in nontoxic concentrations showed a reversible tight junctions modulating effect and were effective to open the paracellular pathway for the marker molecules fluorescein and albumin. The change in the structure of cell-cell junctions was verified by immunostaining for occludin, claudin-4,-5, ZO-1, β-catenin, and E-cadherin. Expression levels of occludin and claudins were measured in both models. We could demonstrate a selectivity of C-CPE, ADT-6, and HAV-6 peptides for epithelial cells and 7-mer and AT-1002 peptides for brain endothelial cells. PN-159 was the most effective modulator of junctional permeability in both models possibly acting via claudin-1 and -5. Our results indicate that these peptides can be effectively and selectively used as potential pharmaceutical excipients to improve drug delivery across biological barriers. Copyright © 2016 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

  4. Isolation and characterisation of a novel antibacterial peptide from a native swine intestinal tract-derived bacterium.

    PubMed

    Xin, Haiyun; Ji, Shengyue; Peng, Jiayin; Han, Peng; An, Xiaopeng; Wang, Shan; Cao, Binyun

    2017-02-27

    Antimicrobial peptides (AMPs) are highly associated with antipathogenic activity, without generating drug resistance in targeted bacteria. In this study, the existence of AMPs in the Tibetan swine, a China-native, cold-resistant and seldom-sick breed of pig, was investigated. A peptide secreted by a Tibetan swine intestinal tract-derived Bacillus strain was isolated using reversed-phase chromatography (RPC), ultrafiltration and reversed-phase high-performance liquid chromatography (RP-HPLC). The peptide was identified by mass spectrometry and was characterised for activity against Escherichia coli and Staphylococcus aureus. The 16-amino acid peptide (ASVVNKLTGGVAGLLK), named TP, had a molecular mass of 1568.919 Da and exhibited inhibitory activity against Gram-positive and Gram-negative bacteria [minimum inhibitory concentrations (MICs) of 2.5-5 µM and 10-20 µM for E. coli and S. aureus, respectively] as well as human MKN-45 and NB4 tumour cell lines [50% inhibitory concentration (IC50) = 4.686 µM and 11.479 µM, respectively]. TP also exhibited weak haemolytic activity. Furthermore, TP enhanced cell membrane permeability and K(+) outflow, bound with E. coli genomic DNA in vitro and inhibited E. coli growth. Thus, TP represents a strong candidate as an antibacterial peptide.

  5. Oral Toxicity and Intestinal Transport Mechanism of Colloidal Gold Nanoparticle-Treated Red Ginseng

    PubMed Central

    Bae, Song-Hwa; Yu, Jin; Go, Mi-Ran; Kim, Hyun-Jin; Hwang, Yun-Gu; Choi, Soo-Jin

    2016-01-01

    (1) Background: Application of nanotechnology or nanomaterials in agricultural food crops has attracted increasing attention with regard to improving crop production, quality, and nutrient utilization. Gold nanoparticles (Au-NPs) have been reported to enhance seed yield, germination rate, and anti-oxidant potential in food crops, raising concerns about their toxicity potential. In this study, we evaluated the oral toxicity of red ginseng exposed to colloidal Au-NPs during cultivation (G-red ginseng) in rats and their intestinal transport mechanism. (2) Methods: 14-day repeated oral administration of G-red ginseng extract to rats was performed, and body weight, hematological, serum biochemical, and histopathological values were analyzed. An in vitro model of human intestinal follicle-associated epithelium (FAE) and an intestinal epithelial monolayer system were used for intestinal transport mechanistic study. (3) Results: No remarkable oral toxicity of G-red ginseng extract in rats was found, and Au-NPs did not accumulate in any organ, although Au-NP transfer to G-red ginseng and some increased saponin levels were confirmed. Au-NPs were transcytozed by microfold (M) cells, but not by a paracellular pathway in the intestinal epithelium. (4) Conclusion: These findings suggest great potential of Au-NPs for agricultural food crops at safe levels. Further study is required to elucidate the functional effects of Au-NPs on ginseng and long-term toxicity. PMID:28335336

  6. Cysteine-rich intestinal protein binds zinc during transmucosal zinc transport.

    PubMed Central

    Hempe, J M; Cousins, R J

    1991-01-01

    The mechanism of zinc absorption has not been delineated, but kinetic studies show that both passive and carrier-mediated processes are involved. We have identified a low molecular mass zinc-binding protein in the soluble fraction of rat intestinal mucosa that could function as an intracellular zinc carrier. The protein was not detected in liver or pancreas, suggesting a role specific to the intestine. The protein binds zinc during transmucosal zinc transport and shows signs of saturation at higher luminal zinc concentrations, characteristics consistent with a role in carrier-mediated zinc absorption. Microsequence analysis of the protein purified by gel-filtration HPLC and SDS/PAGE showed complete identity within the first 41 N-terminal amino acids with the deduced protein sequence of cysteine-rich intestinal protein [Birkenmeier, E. H. & Gordon, J. I. (1986) Proc. Natl. Acad. Sci. USA 83, 2516-2520]. These investigators showed that the gene for this protein is developmentally regulated in neonates during the suckling period, conserved in many vertebrate species, and predominantly expressed in the small intestine. Cysteine-rich intestinal protein contains a recently identified conserved sequence of histidine and cysteine residues, the LIM motif, which our results suggest confers metal-binding properties that are important for zinc transport and/or functions of this micronutrient. Images PMID:1946385

  7. Role of intestinal lymphatics in interstitial volume regulation and transmucosal water transport

    PubMed Central

    Kvietys, Peter R.; Granger, D. Neil

    2010-01-01

    Two of the principal functions of intestinal lymphatics are to assist in 1) maintaining interstitial volume within relatively normal limits during alterations in capillary filtration (e.g., acute portal hypertension) and 2) removal of absorbed water and chylomicrons. The contribution of lymphatics to the prevention of interstitial over-hydration or dehydration during alterations in transcapillary filtration is similar in the small intestine and colon. While the lymphatics of the small intestine contribute substantially to the removal of absorbed water (particularly at low and moderate absorption rates), the contribution of colonic lymphatics to the removal of the fluid absorbate is negligible. This difference is attributed to the relative caliber and location of lymphatics in the mucosal layer of the small and large intestines. In the small intestine, large lacteals lie in close proximity to transporting epithelium, while colonic lymph vessels are rather sparse and confined to the basal portion of the mucosa. In the small intestine, the lymphatics assume a more important role in removing absorbed water during lipid absorption than during glucose absorption. PMID:20961304

  8. Strategies of Drug Transporter Quantitation by LC-MS: Importance of Peptide Selection and Digestion Efficiency.

    PubMed

    Chen, Buyun; Liu, Liling; Ho, Hoangdung; Chen, Yuan; Yang, Ze; Liang, Xiaorong; Payandeh, Jian; Dean, Brian; Hop, Cornelis E C A; Deng, Yuzhong

    2017-06-06

    Huge variation of drug transporter abundance was seen in the literature, making PBPK prediction difficult when transporters play a major role. Among multiple factors such as membrane fraction, digestion, and peptide selection that contributed to such variation, peptide selection is the least discussed. Herein, a strategy was established by using a small amount of purified protein standard to select a peptide with near 100% digestion efficiency for quantitation of a transporter protein MDR1. The impact of native membrane protein's tertiary structure on the digestion efficiency of surrogate peptides of MDR1 was investigated. Peptides in more solvent accessible regions are found to be digested much more efficiently than those in large stretches of helical structures. The concentration of peptide EALDESIPPVSFWR(EAL) in the most solvent accessible linker region of MDR1 was found closest to the true protein concentration. When using EAL for MDR1 quantitation, the abundance is over 10 times higher than previously reported, indicating the importance of peptide selection for transporter quantitation. In addition, this study also proposes a screening strategy to select peptides appropriate for relative quantitation for in vitro-in vivo extrapolation in the absence of any protein standard.

  9. Effects of copper and ceruloplasmin on iron transport in the Caco 2 cell intestinal model.

    PubMed

    Zerounian, Nora R.; Linder, Maria C.

    2002-03-01

    Previous studies have implicated copper proteins, including ceruloplasmin, in intestinal iron transport. Polarized Caco2 cells with tight junctions were used to examine the possibilities that (a) ceruloplasmin promotes iron absorption by enhancing release at the basolateral cell surface and (b) copper deficiency reduces intestinal iron transport. Iron uptake and overall transport were followed for 90 min with 1 &mgr;M 59Fe(II) applied to the apical surface of Caco2 cell monolayers. Apotransferrin (38 &mgr;M) was in the basolateral chamber. Induction of iron deficiency with desferrioxamine (100 &mgr;M; 18 h) markedly increased uptake and overall transport of iron. Uptake increased from about 20% to about 65% of dose, and overall 59Fe transport from <1% to 60% of dose. On the basis of actual iron released into the basal chamber (measured with bathophenanthroline), transport increased 8-fold. Desferrioxamine pretreatment reduced cellular Fe by 55%. The addition of freshly isolated, enzymatically active human ceruloplasmin to the basolateral chamber during absorption had no effect on uptake or transport of iron by the cells. Unexpectedly, pretreatment with three different chelators of copper (18 h), which reduced cellular levels about 40%, more than doubled iron uptake and raised overall transport to 20%. This was so, whether or not cells were also made iron deficient with desferrioxamine. Acute addition of 1 &mgr;M Cu(II) to the apical chamber had no significant effect upon iron uptake, retention, or transport in iron deficient or normal cells, in the presence of absence of ascorbate. We conclude that intestinal absorption of Fe(II) is unlikely to depend upon plasma ceruloplasmin, and that cuproproteins involved in this form of iron transport must be binding copper tightly.

  10. Sustained glucagon-like peptide-2 infusion is required for intestinal adaptation, and cessation reverses increased cellularity in rats with intestinal failure

    PubMed Central

    Koopmann, Matthew C.; Chen, Xueyan; Holst, Jens J.

    2010-01-01

    Glucagon-like peptide-2 (GLP-2) is a nutrient-dependent, proglucagon-derived hormone that is a proposed treatment for human short bowel syndrome (SBS). The objective was to determine how the timing, duration, and cessation of GLP-2 administration affect intestinal adaptation and enterocyte kinetics in a rat model of human SBS that results in intestinal failure requiring total parenteral nutrition (TPN). Rats underwent 60% jejunoileal resection plus cecectomy and jugular vein cannulation and were maintained exclusively with TPN for 18 days in these treatments: TPN control (no GLP-2); sustained GLP-2 (1–18 days); early GLP-2 (1–7 days, killed at 7 or 18 days); and delayed GLP-2 (12–18 days). Body weight gain was similar across groups, and plasma bioactive GLP-2 was significantly increased with coinfusion of GLP-2 (100 μg·kg−1·day−1) with TPN. GLP-2-treated rats showed significant increases in duodenum and jejunum mucosal dry mass, protein, DNA, and sucrase activity compared with TPN control. The increased jejunum cellularity reflected significantly decreased apoptosis and increased crypt mitosis and crypt fission due to GLP-2. When GLP-2 infusion stopped at 7 days, these effects were reversed at 18 days. Sustained GLP-2 infusion significantly increased duodenum length and decreased 18-day mortality to 0% from 37.5% deaths in TPN control (P = 0.08). Colon proglucagon expression quantified by real-time RT-qPCR was increased in TPN controls and attenuated by GLP-2 infusion; jejunal expression of the GLP-2 receptor did not differ among groups. In summary, early, sustained GLP-2 infusion reduces mortality, induces crypt fission, and is required for intestinal adaptation, whereas cessation of GLP-2 reverses gains in mucosal cellularity in a rat model of intestinal failure. PMID:20864657

  11. Intestinal cell targeting of a stable recombinant Cu-Zn SOD from Cucumis melo fused to a gliadin peptide.

    PubMed

    Intes, Laurent; Bahut, Muriel; Nicole, Pascal; Couvineau, Alain; Guette, Catherine; Calenda, Alphonse

    2012-05-31

    The mRNA encoding full length chloroplastic Cu-Zn SOD (superoxide dismutase) of Cucumis melo (Cantaloupe melon) was cloned. This sequence was then used to generate a mature recombinant SOD by deleting the first 64 codons expected to encode a chloroplastic peptide signal. A second hybrid SOD was created by inserting ten codons to encode a gliadin peptide at the N-terminal end of the mature SOD. Taking account of codon bias, both recombinant proteins were successfully expressed and produced in Escherichia coli. Both recombinant SODs display an enzymatic activity of ~5000U mg(-1) and were shown to be stable for at least 4h at 37°C in biological fluids mimicking the conditions of intestinal transit. These recombinant proteins were capable in vitro, albeit at different levels, of reducing ROS-induced-apoptosis of human epithelial cells. They also stimulated production and release in a time-dependent manner of an autologous SOD activity from cells located into jejunum biopsies. Nevertheless, the fused gliadin peptide enable the recombinant Cu-Zn SOD to maintain a sufficiently sustained interaction with the intestinal cells membrane in vivo rather than being eliminated with the flow. According to these observations, the new hybrid Cu-Zn SOD should show promise in applications for managing inflammatory bowel diseases.

  12. Temperature Modulates the Effects of Ocean Acidification on Intestinal Ion Transport in Atlantic Cod, Gadus morhua.

    PubMed

    Hu, Marian Y; Michael, Katharina; Kreiss, Cornelia M; Stumpp, Meike; Dupont, Sam; Tseng, Yung-Che; Lucassen, Magnus

    2016-01-01

    CO2-driven seawater acidification has been demonstrated to enhance intestinal bicarbonate secretion rates in teleosts, leading to an increased release of CaCO3 under simulated ocean acidification scenarios. In this study, we investigated if increasing CO2 levels stimulate the intestinal acid-base regulatory machinery of Atlantic cod (Gadus morhua) and whether temperatures at the upper limit of thermal tolerance stimulate or counteract ion regulatory capacities. Juvenile G. morhua were acclimated for 4 weeks to three CO2 levels (550, 1200, and 2200 μatm) covering present and near-future natural variability, at optimum (10°C) and summer maximum temperature (18°C), respectively. Immunohistochemical analyses revealed the subcellular localization of ion transporters, including Na(+)/K(+)-ATPase (NKA), Na(+)/H(+)-exchanger 3 (NHE3), Na(+)/[Formula: see text] cotransporter (NBC1), pendrin-like Cl(-)/[Formula: see text] exchanger (SLC26a6), V-type H(+)-ATPase subunit a (VHA), and Cl(-) channel 3 (CLC3) in epithelial cells of the anterior intestine. At 10°C, proteins and mRNA were generally up-regulated for most transporters in the intestinal epithelium after acclimation to higher CO2 levels. This supports recent findings demonstrating increased intestinal [Formula: see text] secretion rates in response to CO2 induced seawater acidification. At 18°C, mRNA expression and protein concentrations of most ion transporters remained unchanged or were even decreased, suggesting thermal compensation. This response may be energetically favorable to retain blood [Formula: see text] levels to stabilize pHe, but may negatively affect intestinal salt and water resorption of marine teleosts in future oceans.

  13. Temperature Modulates the Effects of Ocean Acidification on Intestinal Ion Transport in Atlantic Cod, Gadus morhua

    PubMed Central

    Hu, Marian Y.; Michael, Katharina; Kreiss, Cornelia M.; Stumpp, Meike; Dupont, Sam; Tseng, Yung-Che; Lucassen, Magnus

    2016-01-01

    CO2-driven seawater acidification has been demonstrated to enhance intestinal bicarbonate secretion rates in teleosts, leading to an increased release of CaCO3 under simulated ocean acidification scenarios. In this study, we investigated if increasing CO2 levels stimulate the intestinal acid–base regulatory machinery of Atlantic cod (Gadus morhua) and whether temperatures at the upper limit of thermal tolerance stimulate or counteract ion regulatory capacities. Juvenile G. morhua were acclimated for 4 weeks to three CO2 levels (550, 1200, and 2200 μatm) covering present and near-future natural variability, at optimum (10°C) and summer maximum temperature (18°C), respectively. Immunohistochemical analyses revealed the subcellular localization of ion transporters, including Na+/K+-ATPase (NKA), Na+/H+-exchanger 3 (NHE3), Na+/HCO3− cotransporter (NBC1), pendrin-like Cl−/HCO3− exchanger (SLC26a6), V-type H+-ATPase subunit a (VHA), and Cl− channel 3 (CLC3) in epithelial cells of the anterior intestine. At 10°C, proteins and mRNA were generally up-regulated for most transporters in the intestinal epithelium after acclimation to higher CO2 levels. This supports recent findings demonstrating increased intestinal HCO3− secretion rates in response to CO2 induced seawater acidification. At 18°C, mRNA expression and protein concentrations of most ion transporters remained unchanged or were even decreased, suggesting thermal compensation. This response may be energetically favorable to retain blood HCO3− levels to stabilize pHe, but may negatively affect intestinal salt and water resorption of marine teleosts in future oceans. PMID:27313538

  14. Human, rat and chicken small intestinal Na+-Cl−-creatine transporter: functional, molecular characterization and localization

    PubMed Central

    Peral, M J; García-Delgado, M; Calonge, M L; Durán, J M; De La Horra, M C; Wallimann, T; Speer, O; Ilundáin, A A

    2002-01-01

    In spite of all the fascinating properties of oral creatine supplementation, the mechanism(s) mediating its intestinal absorption has(have) not been investigated. The purpose of this study was to characterize intestinal creatine transport. [14C]Creatine uptake was measured in chicken enterocytes and rat ileum, and expression of the creatine transporter CRT was examined in human, rat and chicken small intestine by reverse transcription-polymerase chain reaction, Northern blot, in situ hybridization, immunoblotting and immunohistochemistry. Results show that enterocytes accumulate creatine against its concentration gradient. This accumulation was electrogenic, Na+- and Cl−-dependent, with a probable stoichiometry of 2 Na+: 1 Cl−: 1 creatine, and inhibited by ouabain and iodoacetic acid. The kinetic study revealed a Km for creatine of 29 μm. [14C]Creatine uptake was efficiently antagonized by non-labelled creatine, guanidinopropionic acid and cyclocreatine. More distant structural analogues of creatine, such as GABA, choline, glycine, β-alanine, taurine and betaine, had no effect on intestinal creatine uptake, indicating a high substrate specificity of the creatine transporter. Consistent with these functional data, messenger RNA for CRT was detected only in the cells lining the intestinal villus. The sequences of partial clones, and of the full-length cDNA clone, isolated from human and rat small intestine were identical to previously cloned CRT cDNAs. Immunological analysis revealed that CRT protein was mainly associated with the apical membrane of the enterocytes. This study reports for the first time that mammalian and avian enterocytes express CRT along the villus, where it mediates high-affinity, Na+- and Cl−-dependent, apical creatine uptake. PMID:12433955

  15. Region-Dependent Role of Cell-Penetrating Peptides in Insulin Absorption Across the Rat Small Intestinal Membrane.

    PubMed

    Khafagy, El-Sayed; Iwamae, Ruisha; Kamei, Noriyasu; Takeda-Morishita, Mariko

    2015-11-01

    We have reported that the cell-penetrating peptide (CPP) penetratin acts as a potential absorption enhancer in oral insulin delivery systems and that this action occurs through noncovalent intermolecular interactions. However, the region-dependent role of CPPs in intestinal insulin absorption has not been clarified. To identify the intestinal region where CPPs have the most effect in increasing insulin absorption, the region-dependent action of penetratin was investigated using in situ closed intestinal loops in rats. The order of the insulin area under the insulin concentration-time curve (AUC) increase effect by L-penetratin was ileum > jejunum > duodenum > colon. By contrast, the AUC order after coadministration of insulin with D-penetratin was colon > duodenum ≥ jejunum and ileum. We also compared the effects of the L- and D-forms of penetratin, R8, and PenetraMax on ileal insulin absorption. Along with the CPPs used in this study, L- and D-PenetraMax produced the largest insulin AUCs. An absorption study using ilea pretreated with CPPs showed that PenetraMax had no irreversible effect on the intestinal epithelial membrane. The degradation of insulin in the presence of CPPs was assessed in rat intestinal enzymatic fluid. The half-life (t 1/2) of insulin increased from 14.5 to 23.7 and 184.7 min in the presence of L- and D-PenetraMax, respectively. These enzymatic degradation-resistant effects might contribute partly to the increased ileal absorption of insulin induced by D-PenetraMax. In conclusion, this study demonstrated that the ability of the L- and D-forms of penetratin to increase intestinal insulin absorption was maximal in the ileum and the colon, respectively, and that D-PenetraMax is a powerful but transient enhancer of oral insulin absorption.

  16. CCR6 Deficiency Impairs IgA Production and Dysregulates Antimicrobial Peptide Production, Altering the Intestinal Flora

    PubMed Central

    Lin, Ya-Lin; Ip, Peng-Peng; Liao, Fang

    2017-01-01

    Intestinal immunity exists as a complex relationship among immune cells, epithelial cells, and microbiota. CCR6 and its ligand–CCL20 are highly expressed in intestinal mucosal tissues, such as Peyer’s patches (PPs) and isolated lymphoid follicles (ILFs). In this study, we investigated the role of the CCR6–CCL20 axis in intestinal immunity under homeostatic conditions. CCR6 deficiency intrinsically affects germinal center reactions in PPs, leading to impairments in IgA class switching, IgA affinity, and IgA memory B cell production and positioning in PPs, suggesting an important role for CCR6 in T-cell-dependent IgA generation. CCR6 deficiency impairs the maturation of ILFs. In these follicles, group 3 innate lymphoid cells are important components and a major source of IL-22, which stimulates intestinal epithelial cells (IECs) to produce antimicrobial peptides (AMPs). We found that CCR6 deficiency reduces IL-22 production, likely due to diminished numbers of group 3 innate lymphoid cells within small-sized ILFs. The reduced IL-22 levels subsequently decrease the production of AMPs, suggesting a critical role for CCR6 in innate intestinal immunity. Finally, we found that CCR6 deficiency impairs the production of IgA and AMPs, leading to increased levels of Alcaligenes in PPs, and segmented filamentous bacteria in IECs. Thus, the CCR6–CCL20 axis plays a crucial role in maintaining intestinal symbiosis by limiting the overgrowth of mucosa-associated commensal bacteria. PMID:28744287

  17. The effects of critical illness on intestinal glucose sensing, transporters, and absorption.

    PubMed

    Deane, Adam M; Rayner, Chris K; Keeshan, Alex; Cvijanovic, Nada; Marino, Zelia; Nguyen, Nam Q; Chia, Bridgette; Summers, Matthew J; Sim, Jennifer A; van Beek, Theresia; Chapman, Marianne J; Horowitz, Michael; Young, Richard L

    2014-01-01

    Providing effective enteral nutrition is important during critical illness. In health, glucose is absorbed from the small intestine via sodium-dependent glucose transporter-1 and glucose transporter-2, which may both be regulated by intestinal sweet taste receptors. We evaluated the effect of critical illness on glucose absorption and expression of intestinal sodium-dependent glucose transporter-1, glucose transporter-2, and sweet taste receptors in humans and mice. Prospective observational study in humans and mice. ICU and university-affiliated research laboratory. Human subjects were 12 critically ill patients and 12 healthy controls. In the laboratory 16-week-old mice were studied. Human subjects underwent endoscopy. Glucose (30 g) and 3-O-methylglucose (3 g), used to estimate glucose absorption, were infused intraduodenally over 30 minutes. Duodenal mucosa was biopsied before and after infusion. Mice were randomized to cecal ligation and puncture to model critical illness (n = 16) or sham laparotomy (control) (n = 8). At day 5, mice received glucose (100 mg) and 3-O-methylglucose (10 mg) infused intraduodenally prior to mucosal tissue collection. Quantitative polymerase chain reaction was performed to measure absolute (human) and relative levels of sodium-dependent glucose transporter-1, glucose transporter-2, and taste receptor type 1 member 2 (T1R2) transcripts. Blood samples were assayed for 3-O-methylglucose to estimate glucose absorption. Glucose absorption was three-fold lower in critically ill humans than in controls (p = 0.002) and reduced by a similar proportion in cecal ligation and puncture mice (p = 0.004). In critically ill patients, duodenal levels of sodium-dependent glucose transporter-1, glucose transporter-2, and T1R2 transcript were reduced 49% (p < 0.001), 50% (p = 0.009), and 85% (p = 0.007), whereas in the jejunum of cecal ligation and puncture mice sodium-dependent glucose transporter-1, glucose transporter-2, and T1R2

  18. Intestinal Lymphatic Transport: an Overlooked Pathway for Understanding Absorption of Plant Secondary Compounds in Vertebrate Herbivores.

    PubMed

    Kohl, Kevin D; Dearing, M Denise

    2017-03-01

    Herbivores employ numerous strategies to reduce their exposure to toxic plant secondary chemicals (PSCs). However, the physiological mechanisms of PSC absorption have not been extensively explored. In particular, the absorption of PSCs via intestinal lymphatic absorption has been largely overlooked in herbivores, even though this pathway is well recognized for pharmaceutical uptake. Here, we investigated for the first time whether PSCs might be absorbed by lymphatic transport. We fed woodrats (Neotoma albigula) diets with increasing concentrations of terpene-rich juniper (Juniperus monosperma) either with or without a compound that blocks intestinal lymphatic absorption (Pluronic L-81). Woodrats consuming diets that contained the intestinal lymphatic absorption blocker exhibited increased food intakes and maintained higher body masses on juniper diets. Our study represents the first demonstration that PSCs may be absorbed by intestinal lymphatic absorption. This absorption pathway has numerous implications for the metabolism and distribution of PSCs in the systemic circulation, given that compounds absorbed via lymphatic transport bypass first-pass hepatic metabolism. The area of lymphatic transport of PSCs represents an understudied physiological pathway in plant-herbivore interactions.

  19. Activation of CFTR trafficking and gating by vasoactive intestinal peptide in human bronchial epithelial cells.

    PubMed

    Qu, Fei; Liu, Hui-Jun; Xiang, Yang; Tan, Yu-Rong; Liu, Chi; Zhu, Xiao-Lin; Qin, Xiao-Qun

    2011-03-01

    Cystic fibrosis transmembrane conductance regulator (CFTR) is an apical membrane chloride channel critical to the regulation of fluid, chloride, and bicarbonate transport in epithelia and other cell types. The most common cause of cystic fibrosis (CF) is the abnormal trafficking of CFTR mutants. Therefore, understanding the cellular machineries that transit CFTR from the endoplasmic reticulum to the cell surface is important. Vasoactive intestinal polypeptide (VIP) plays an important role in CFTR-dependent chloride transport. The present study was designed to observe the affection of VIP on the trafficking of CFTR, and channel gating in human bronchial epithelium cells (HBEC). Confocal microscopy revealed CFTR immunofluorescence extending from the apical membrane deeply into the cell cytoplasm. After VIP treatment, apical extension of CFTR immunofluorescence into the cell was reduced and the peak intensity of CFTR fluorescence shifted towards the apical membrane. Western blot showed VIP increased cell surface and total CFTR. Compared with the augmented level of total CFTR, the surface CFTR increased more markedly. Immunoprecipitation founded that the mature form of CFTR had a marked increase in HBEC treated with VIP. VIP led to a threefold increase in Cl(-) efflux in HBEC. Glibenclamide-sensitive and DIDS-insensitive CFTR Cl(-) currents were consistently observed after stimulation with VIP (10(-8) mol/L). The augmentation of CFTR Cl(-) currents enhanced by VIP (10(-8) mol/L) was reversed, at least in part, by the protein kinase A (PKA) inhibitor, H-89 and the protein kinase C (PKC) inhibitor, H-7, suggesting PKA and PKC participate in the VIP-promoted CFTR Cl(-) currents.

  20. The transport of uric acid across mouse small intestine in vitro.

    PubMed Central

    Bronk, J R; Shaw, M I

    1986-01-01

    The in vitro recirculation technique was used to study the uptake and transport of uric acid by the jejunum of mouse small intestine. Three components of the serosal secretions appeared to be endogenously derived nucleic acid derivatives; two of these were identified as uric acid and uracil. There was no detectable metabolism of uric acid by the intestine. Uric acid transported from the lumen appeared in the serosal fluid at a concentration higher than that in the lumen. The final serosal/luminal concentration ratio of about 1.18 for exogenous uric acid was found to be constant over the concentration range studied (0.01-0.1 mM). The presence of exogenous uric acid in the lumen did not affect the production of endogenous uric acid by the intestine and its release into the serosal secretions. Mucosal concentration of exogenous uric acid was below, but the total mucosal concentration (exogenous+endogenous) was above, that in the lumen. There was no evidence for the secretion of endogenous uric acid into the lumen. Oxypurinol significantly decreased the rate of serosal appearance of exogenous uric acid. Allopurinol did not affect the transport of exogenous uric acid from the lumen and there was negligible metabolism of allopurinol to oxypurinol by the tissue. Uracil did not affect the transport of exogenous uric acid from the lumen, or the serosal appearance of endogenous uric acid. Likewise uracil transport was unaffected by luminal uric acid. PMID:3795104

  1. Intra-Amniotic Administration (Gallus gallus) of Cicer arietinum and Lens culinaris Prebiotics Extracts and Duck Egg White Peptides Affects Calcium Status and Intestinal Functionality

    PubMed Central

    Hou, Tao; Glahn, Raymond P.; Tako, Elad

    2017-01-01

    Calcium (Ca) is one of the most abundant inorganic elements in the human body and has many important physiological roles. Prebiotics and bioactive peptides are two important substances used to promote calcium uptake. However, the difference in mechanisms of the calcium uptake from these two supplements is not clear. By using the Gallus gallus model and the intra-amniotic administration procedure, the aim of this study was to investigate whether Ca status, intestinal functionality, and health-promoting bacterial populations were affected by prebiotics extracted from chickpea and lentil, and duck egg white peptides (DPs). Eleven groups (non-injected; 18 MΩ H2O; 4 mmol/L CaCl2; 50 mg/mL chickpea + 4 mmol/L CaCl2; 50 mg/mL lentil + 4 mmol/L CaCl2; 40 mg/mL DPs + 4 mmol/L CaCl2; 5 mg/mL Val-Ser-Glu-Glu (VSEE) + 4 mmol/L CaCl2; 50 mg/mL chickpea; 50 mg/mL lentil; 40 mg/mL DPs; 5 mg/mL VSEE) were utilized. Upon hatch, blood, cecum, small intestine, liver and bone were collected for assessment of serum bone alkaline phosphate level (BALP), the relative abundance of intestinal microflora, expression of Ca-related genes, brush border membrane (BBM) functional genes, and liver and bone mineral levels, respectively. The BALP level increased in the presence of lentil, DPs and VSEE (p < 0.05). The relative abundance of probiotics increased significantly (p < 0.05) by VSEE + Ca and chickpea. The expression of CalbindinD9k (Ca transporter) increased (p < 0.05) in Ca, chickpea + Ca and lentil + Ca groups. In addition, the brush border membrane functionality genes expressions increased (p < 0.05) by the chickpea or lentil extracts. Prebiotics and DPs beneficially affected the intestinal microflora and duodenal villus surface area. This research expands the understanding of the prebiotics’ properties of chickpea and lentil extracts, and peptides’ effects on calcium metabolism and gut health. PMID:28754012

  2. Glucagon-like peptide 2 prevents down-regulation of intestinal multidrug resistance-associated protein 2 and P-glycoprotein in endotoxemic rats.

    PubMed

    Arana, Maite Rocío; Tocchetti, Guillermo Nicolás; Zecchinati, Felipe; Londero, Ana Sofía; Dominguez, Camila; Perdomo, Virginia; Rigalli, Juan Pablo; Villanueva, Silvina Stella Maris; Mottino, Aldo Domingo

    2017-08-23

    Multidrug resistance-associated protein 2 (Mrp2, ABCC2) and P-glycoprotein (P-gp, ABCB1) constitute essential components of the intestinal biochemical barrier that prevent incorporation of food contaminants, drugs or toxic metabolites into the blood stream. Endotoxemia induced in rats by administration of bacterial lipopolysaccharide (LPS) results in elevated intestinal permeability and toxicity of xenobiotics in part associated with down-regulation of expression and activity of Mrp2 and P-gp. We evaluated the protective effect of glucagon-like peptide 2 (GLP-2), a peptide hormone with enterotrophic properties, on Mrp2 and P-gp alterations induced by single i.p. injection of LPS (5mg/kg b.wt.) to rats. Two different protocols of GLP-2 administration, namely prevention and reversion, were examined. The prevention protocol consisted of 7s.c. injections of GLP-2 (125μg/kg b.wt.) administered every 12h, starting 60h before LPS administration. The reversion protocol consisted of 2 doses of GLP-2, starting 3h after LPS injection. Intestinal samples were collected 24h after LPS administration and expression (protein and mRNA) and activity of Mrp2 were evaluated in proximal jejunum whereas those of P-gp were studied in ileum. GLP-2 completely neutralized down-regulation of expression of Mrp2 and P-gp and loss of their respective activities induced by LPS under prevention protocol. GLP-2 was also able to prevent internalization of both transporters from the apical membrane of the enterocyte to intracellular compartments, as detected by confocal microscopy. LPS induced an increase in IL-1β and oxidized glutathione tissue levels, which were also counterbalanced by GLP-2 administration. In contrast, the reversion protocol failed to attenuate Mrp2 and P-gp down-regulation induced by LPS. We conclude that GLP-2 can prevent down-regulation of intestinal expression and activity of Mrp2 and P-gp in endotoxemic rats and that IL-1β and oxidative stress constitute potential targets

  3. Epithelial transport and deamidation of gliadin peptides: a role for coeliac disease patient immunoglobulin A

    PubMed Central

    Rauhavirta, T; Qiao, S-W; Jiang, Z; Myrsky, E; Loponen, J; Korponay-Szabó, I R; Salovaara, H; Garcia-Horsman, J A; Venäläinen, J; Männistö, P T; Collighan, R; Mongeot, A; Griffin, M; Mäki, M; Kaukinen, K; Lindfors, K

    2011-01-01

    In coeliac disease, the intake of dietary gluten induces small-bowel mucosal damage and the production of immunoglobulin (Ig)A class autoantibodies against transglutaminase 2 (TG2). We examined the effect of coeliac patient IgA on the apical-to-basal passage of gluten-derived gliadin peptides p31–43 and p57–68 in intestinal epithelial cells. We demonstrate that coeliac IgA enhances the passage of gliadin peptides, which could be abolished by inhibition of TG2 enzymatic activity. Moreover, we also found that both the apical and the basal cell culture media containing the immunogenic gliadin peptides were able to induce the proliferation of deamidation-dependent coeliac patient-derived T cells even in the absence of exogenous TG2. Our results suggest that coeliac patient IgA could play a role in the transepithelial passage of gliadin peptides, a process during which they might be deamidated. PMID:21235541

  4. Glucagon-like peptide 1 (1–37) converts intestinal epithelial cells into insulin-producing cells

    PubMed Central

    Suzuki, Atsushi; Nakauchi, Hiromitsu; Taniguchi, Hideki

    2003-01-01

    Glucagon-like peptide (GLP) 1 is produced through posttranslational processing of proglucagon and acts as a regulator of various homeostatic events. Among its analogs, however, the function of GLP-1-(1–37), synthesized in small amounts in the pancreas, has been unclear. Here, we find that GLP-1-(1–37) induces insulin production in developing and, to a lesser extent, adult intestinal epithelial cells in vitro and in vivo, a process mediated by up-regulation of the Notch-related gene ngn3 and its downstream targets, which are involved in pancreatic endocrine differentiation. These cells became responsive to glucose challenge in vitro and reverse insulin-dependent diabetes after implantation into diabetic mice. Our findings suggest that efficient induction of insulin production in intestinal epithelial cells by GLP-1-(1–37) could represent a new therapeutic approach to diabetes mellitus. PMID:12702762

  5. Transport characteristics of isorhamnetin across intestinal Caco-2 cell monolayers and the effects of transporters on it.

    PubMed

    Duan, Jingze; Xie, Yan; Luo, Huilin; Li, Guowen; Wu, Tao; Zhang, Tong

    2014-04-01

    Flavonoid isorhamnetin occurs in various plants and herbs, and demonstrates various biological effects in humans. This work will clarify the isorhamnetin absorption mechanism using the Caco-2 monolayer cell model. The isorhamnetin transport characteristics at different concentrations, pHs, temperatures, tight junctions and potential transporters were systemically investigated. Isorhamnetin was poorly absorbed by both passive diffusion and active transport mechanisms. Both trans- and paracellular pathways were involved during isorhamnetin transport. Active transport under an ATP-dependent transport mechanism was mediated by the organic anion transporting peptide (OATP); isorhamnetin's permeability from the apical to the basolateral side significantly decreased after estrone-3-sulfate was added (p<0.01). Efflux transporters, P-glycoproteins (P-gp), breast cancer resistance proteins (BCRP) and multidrug resistance proteins (MRPs) participated in the isorhamnetin transport process. Among them, the MRPs (especially MRP2) were the main efflux transporters for isorhamnetin; transport from the apical to the basolateral side increased 10.8-fold after adding an MRP inhibitor (MK571). This study details isorhamnetin's cellular transport and elaborates isorhamnetin's absorption mechanisms to provide a foundation for further studies.

  6. Intestinal phosphate absorption is mediated by multiple transport systems in rats.

    PubMed

    Candeal, Eduardo; Caldas, Yupanqui A; Guillén, Natalia; Levi, Moshe; Sorribas, Víctor

    2017-04-01

    Apical inorganic phosphate (Pi) transport in the small intestine seems to be mainly mediated by the sodium/Pi cotransporter NaPi2b. To verify this role, we have studied the combined effects of pH, phosphonoformate, and Pi deprivation on intestinal Pi transport. Rats were fed, ad libitum, three fodders containing 1.2, 0.6, or 0.1% Pi for 1, 5, or 10 days. Pi deprivation (0.1%) increased both sodium-activated and sodium-independent Pi transport in brush-border membrane vesicles from the duodenum and jejunum for all three times. Alkaline pH inhibited Pi transport, despite the increasing concentration of [Formula: see text] (NaPi2b substrate), whereas acidity increased transport when the concentration of the PiT1/PiT2 substrate, [Formula: see text], was at its highest. The effect of Pi deprivation was maximal at acid pH, but both basal and upregulated transport were inhibited (70%) with phosphonoformate, an inhibitor of NaPi2b. PiT2 and NaPi2b protein abundance increased after 24 h of Pi deprivation in the duodenum, jejunum, and ileum, whereas PiT1 required 5-10 days in the duodenum and jejunum. Therefore, whereas transporter expressions are partially correlated with Pi transport adaptation, the pH effect precludes NaPi2b, and phosphonoformic acid precludes PiT1 and PiT2 as the main transporters. Transport and transporter expression were also inconsistent when feeding was limited to 4 h daily, because the 1.2% Pi diet paradoxically increased Pi transport in the duodenum and jejunum, but NaPi2b and PiT1 expressions only increased with the 0.1% diet. These findings suggest the presence of a major transporter that carries [Formula: see text] and is inhibited by phosphonoformate.NEW & NOTEWORTHY The combined effects of dietary inorganic phosphate (Pi) content, pH, and phosphonoformate inhibition suggest that the resulting apical Pi transport in the small intestine cannot be fully explained by the presence of NaPi2b, PiT1, or PiT2. We provide evidence of the presence of a

  7. Mass balance approaches for estimating the intestinal absorption and metabolism of peptides and analogues: theoretical development and applications

    NASA Technical Reports Server (NTRS)

    Sinko, P. J.; Leesman, G. D.; Amidon, G. L.

    1993-01-01

    A theoretical analysis for estimating the extent of intestinal peptide and peptide analogue absorption was developed on the basis of a mass balance approach that incorporates convection, permeability, and reaction. The macroscopic mass balance analysis (MMBA) was extended to include chemical and enzymatic degradation. A microscopic mass balance analysis, a numerical approach, was also developed and the results compared to the MMBA. The mass balance equations for the fraction of a drug absorbed and reacted in the tube were derived from the general steady state mass balance in a tube: [formula: see text] where M is mass, z is the length of the tube, R is the tube radius, Pw is the intestinal wall permeability, kr is the reaction rate constant, C is the concentration of drug in the volume element over which the mass balance is taken, VL is the volume of the tube, and vz is the axial velocity of drug. The theory was first applied to the oral absorption of two tripeptide analogues, cefaclor (CCL) and cefatrizine (CZN), which degrade and dimerize in the intestine. Simulations using the mass balance equations, the experimental absorption parameters, and the literature stability rate constants yielded a mean estimated extent of CCL (250-mg dose) and CZN (1000-mg dose) absorption of 89 and 51%, respectively, which was similar to the mean extent of absorption reported in humans (90 and 50%). It was proposed previously that 15% of the CCL dose spontaneously degraded systematically; however, our simulations suggest that significant CCL degradation occurs (8 to 17%) presystemically in the intestinal lumen.(ABSTRACT TRUNCATED AT 250 WORDS).

  8. Helix stabilization of amphipathic peptides by hydrocarbon stapling increases cholesterol efflux by the ABCA1 transporter.

    PubMed

    Sviridov, D O; Ikpot, I Z; Stonik, J; Drake, S K; Amar, M; Osei-Hwedieh, D O; Piszczek, G; Turner, S; Remaley, A T

    2011-07-08

    Apolipoprotein mimetic peptides are short amphipathic peptides that efflux cholesterol from cells by the ABCA1 transporter and are being investigated as therapeutic agents for cardiovascular disease. We examined the role of helix stabilization of these peptides in cholesterol efflux. A 23-amino acid long peptide (Ac-VLEDSFKVSFLSALEEYTKKLNTQ-NH2) based on the last helix of apoA-I (A10) was synthesized, as well as two variants, S1A10 and S2A10, in which the third and fourth and third and fifth turn of each peptide, respectively, were covalently joined by hydrocarbon staples. By CD spectroscopy, the stapled variants at 24 °C were more helical in aqueous buffer than A10 (A10 17%, S1A10 62%, S2A10 97%). S1A10 and S2A10 unlike A10 were resistant to proteolysis by pepsin and chymotrypsin. S1A10 and S2A10 showed more than a 10-fold increase in cholesterol efflux by the ABCA1 transporter compared to A10. In summary, hydrocarbon stapling of amphipathic peptides increases their helicity, makes them resistant to proteolysis and enhances their ability to promote cholesterol efflux by the ABCA1 transporter, indicating that this peptide modification may be useful in the development of apolipoprotein mimetic peptides.

  9. Interaction of Peptide Transporter 1 With D-Glucose and L-Glutamic Acid; Possible Involvement of Taste Receptors.

    PubMed

    Arakawa, Hiroshi; Ohmachi, Taichi; Ichiba, Kiko; Kamioka, Hiroki; Tomono, Takumi; Kanagawa, Masahiko; Idota, Yoko; Hatano, Yasuko; Yano, Kentaro; Morimoto, Kaori; Ogihara, Takuo

    2016-01-01

    We investigated the influence of sweet and umami (savory) tastants on the intestinal absorption of cephalexin (CEX), a substrate of peptide transporter 1 (PEPT1, SLC15A1) in rats. After oral administration of glucose or mannitol to rats, CEX was administered together with a second dose of glucose or mannitol. Western blot analysis indicated that expression of PEPT1 in rat jejunum membrane was decreased by glucose, compared to mannitol. Furthermore, the maximum plasma concentration (Cmax) of orally administered CEX was reduced by glucose compared to mannitol. The effect of glucose was diminished by nifedipine, a L-type Ca(2+) channel blocker. We also found that Cmax of orally administered CEX was reduced by treatment with L-glutamic acid, compared to D-glutamic acid. Thus, excessive intake of glucose and L-glutamic acid may impair oral absorption of PEPT1 substrates. Copyright © 2016. Published by Elsevier Inc.

  10. Glucose transporter 1 (GLUT1) expression is associated with intestinal type of gastric carcinoma.

    PubMed Central

    Kim, W. S.; Kim, Y. Y.; Jang, S. J.; Kimm, K.; Jung, M. H.

    2000-01-01

    Increased expression of glucose transporter1 (GLUT1) has been reported in many human cancers. We hypothesized that the degree of GLUT1 might provide a useful biological information in gastric adenocarcinoma. RT-PCR and immunostaining were used to analyze GLUT1 expression in gastric cancer. RT-PCR showed GLUT1 expression was not largely detected in normal gastric tissue but was detected in cancerous gastric tissue of counterpart. By immunohistochemistry, GLUT1 protein was absent in normal gastric epithelium and intestinal metaplasia. 11 of 65 patients with gastric adenocarcinoma had specific GLUT1 immunostaining in a plasma membrane pattern with varied intensities. GLUT1 protein did not show any significant correlation with tumor stage and nodal metastasis (p>0.05 by Mann-Whitney test). However, the positive immunostaining for GLUT1 is associated with intestinal differentiation (p=0.003). Our results suggest that GLUT1 protein is associated with intestinal type of gastric cancer. PMID:10983690

  11. New mechanisms that regulate Saccharomyces cerevisiae short peptide transporter achieve balanced intracellular amino acid concentrations.

    PubMed

    Melnykov, Artem V

    2016-01-01

    The budding yeast Saccharomyces cerevisiae is able to take up large quantities of amino acids in the form of di- and tripeptides via a short peptide transporter, Ptr2p. It is known that PTR2 can be induced by certain peptides and amino acids, and the mechanisms governing this upregulation are understood at the molecular level. We describe two new opposing mechanisms of regulation that emphasize potential toxicity of amino acids: the first is upregulation of PTR2 in a population of cells, caused by amino acid secretion that accompanies peptide uptake; the second is loss of Ptr2p activity, due to transporter internalization following peptide uptake. Our findings emphasize the importance of proper amino acid balance in the cell and extend understanding of peptide import regulation in yeast.

  12. A peptide & peptide nucleic acid synthesis technology for transporter molecules and theranostics--the SPPS.

    PubMed

    Pipkorn, Ruediger; Braun, Klaus; Wiessler, Manfred; Waldeck, Waldemar; Schrenk, Hans-Hermann; Koch, Mario; Semmler, Wolfhard; Komljenovic, Dorde

    2014-01-01

    Advances in imaging diagnostics using magnetic resonance tomography (MRT), positron emission tomography (PET) and fluorescence imaging including near infrared (NIR) imaging methods are facilitated by constant improvement of the concepts of peptide synthesis. Feasible patient-specific theranostic platforms in the personalized medicine are particularly dependent on efficient and clinically applicable peptide constructs. The role of peptides in the interrelations between the structure and function of proteins is widely investigated, especially by using computer-assisted methods. Nowadays the solid phase synthesis (SPPS) chemistry emerges as a key technology and is considered as a promising methodology to design peptides for the investigation of molecular pharmacological processes at the transcriptional level. SPPS syntheses could be carried out in core facilities producing peptides for large-scale scientific implementations as presented here.

  13. A Peptide & Peptide Nucleic Acid Synthesis Technology for Transporter Molecules and Theranostics - The SPPS

    PubMed Central

    Pipkorn, Ruediger; Braun, Klaus; Wiessler, Manfred; Waldeck, Waldemar; Schrenk, Hans-Hermann; Koch, Mario; Semmler, Wolfhard; Komljenovic, Dorde

    2014-01-01

    Advances in imaging diagnostics using magnetic resonance tomography (MRT), positron emission tomography (PET) and fluorescence imaging including near infrared (NIR) imaging methods are facilitated by constant improvement of the concepts of peptide synthesis. Feasible patient-specific theranostic platforms in the personalized medicine are particularly dependent on efficient and clinically applicable peptide constructs. The role of peptides in the interrelations between the structure and function of proteins is widely investigated, especially by using computer-assisted methods. Nowadays the solid phase synthesis (SPPS) chemistry emerges as a key technology and is considered as a promising methodology to design peptides for the investigation of molecular pharmacological processes at the transcriptional level. SPPS syntheses could be carried out in core facilities producing peptides for large-scale scientific implementations as presented here. PMID:24843319

  14. Differential responses of intestinal glucose transporter mRNA transcripts to levels of dietary sugars.

    PubMed

    Miyamoto, K; Hase, K; Takagi, T; Fujii, T; Taketani, Y; Minami, H; Oka, T; Nakabou, Y

    1993-10-01

    Dietary sugars are known to stimulate intestinal glucose transport activity, but the specific signals involved are unknown. The Na(+)-dependent glucose co-transporter (SGLT1), the liver-type facilitative glucose transporter (GLUT2) and the intestinal-type facilitative glucose transporter (GLUT5) are all expressed in rat jejunum [Miyamoto, Hase, Taketani, Minami, Oka, Nakabou and Hagihira (1991) Biochem. Biophys. Res. Commun. 181, 1110-1117]. In the present study we have investigated the effects of dietary sugars on these glucose transporter genes. A high-glucose diet stimulated glucose transport activity and increased the levels of SGLT1 and GLUT2 mRNAs in rat jejunum. 3-O-Methylglucose, D-galactose, D-fructose, D-mannose and D-xylose can mimic the regulatory effect of glucose on the SGLT1 mRNA level in rat jejunum. However, only D-galactose and D-fructose increased the levels of GLUT2 mRNA. The GLUT5 mRNA level was increased significantly only by D-fructose. Our results suggest that the increase in intestinal transport activity in rats caused by dietary glucose is due to an increase in the levels of SGLT1 and GLUT2 mRNAs, and that these increases in mRNA may be caused by an enhancement of the transcriptional rate. Furthermore, for expression of the SGLT1 gene, the signal need not be a metabolizable or transportable substrate whereas, for expression of the GLUT2 gene, metabolism of the substrate in the liver may be necessary for signalling. Only D-fructose is an effective signal for expression of the GLUT5 gene.

  15. A carrier-mediated transport for folate in basolateral membrane vesicles of rat small intestine.

    PubMed Central

    Said, H M; Redha, R

    1987-01-01

    The mechanism of exit of folate from the enterocyte, i.e. transport across the basolateral membrane, is not known. In this study we examined, using basolateral membrane vesicles, the transport of folic acid across the basolateral membrane of rat intestine. Uptake of folic acid by these vesicles represents transport of the substrate into the intravesicular compartment and not binding to the membrane surface. The rate of folic acid transport was linear for the first 1 min of incubation but decreased thereafter, reaching equilibrium after 5 min of incubation. The transport of folic acid was: (1) saturable as a function of concentration with an apparent Km of 0.6 +/- 0.17 microM and Vmax. of 1.01 +/- 0.11 pmol/30 s per mg of protein; (2) inhibited in a competitive manner by the structural analogues 5-methyltetrahydrofolate and methotrexate (Ki = 2 and 1.4 microM, respectively); (4) electroneutral; (5) Na+-independent; (6) sensitive to the effect of the anion exchange inhibitor 4,4'-di-isothiocyanatostilbene-2,2'-disulphonic acid (DIDS). These data indicate the existence of a carrier-mediated transport system for folic acid in rat intestinal basolateral membrane and demonstrate that the transport process is electroneutral, Na+-independent and sensitive to the effect of anion exchange inhibition. PMID:3689340

  16. Carrier-mediated system for transport of biotin in rat intestine in vitro

    SciTech Connect

    Said, H.M.; Redha, R.

    1987-01-01

    Transport of biotin was examined in rat intestine using the everted sac technique. Transport of 0.1 ..mu..M biotin was linear with time for at least 30 min of incubation and occurred at a rate 3.7 pmol g initial tissue wet wt/sup -1/ min/sup -1/. Transport of biotin was higher in the jejunum than the ileum and was minimum in the colon (85 +/- 6, 36 +/- 6, and 2.8 +/- 0.6 pmol x g initial tissue wet wt/sup -1/ x 25 min/sup -1/, respectively). In the jejunum, transport of biotin was saturable at low concentrations but linear at higher concentrations. The transport of low concentrations of biotin was 1) inhibited by structural analogues (desthiobiotin, biotin methyl ester, diaminobiotin, and biocytin), 2) Na/sup +/ dependent, 3) energy dependent, 4) temperature dependent, and 5) proceeded against a concentration gradient in the serosal compartment. No metabolic alteration occurs to the biotin molecule during transport. This study demonstrates that biotin transport in rat intestine occurs by a carrier-mediated process at low concentrations and by simple diffusion at high concentrations. Furthermore, the carrier-mediated process is Na/sup +/, energy, and temperature dependent.

  17. Disrupted circadian rhythmicity of the intestinal glucose transporter SGLT1 in Zucker Diabetic Fatty rats

    PubMed Central

    Bhutta, Hina Y.; Deelman, Tara E.; Ashley, Stanley W.; Rhoads, David B.; Tavakkoli, Ali

    2013-01-01

    Background Intestinal nutrient absorptive capacity shows a circadian rhythm synchronized with eating patterns. Studies have shown that disrupting these normally coordinated rhythms, e.g. with shift work, may contribute to metabolic disease. While circadian expression of many nutrient transporters has been studied in health, their rhythms in obesity and metabolic disorders is not known. We studied the circadian expression and function of intestinal glucose transporter SGLT1, a major glucose transporter, in a rodent model of obesity and diabetes. Methods We compared obese Zucker Diabetic Fatty (ZDF) rats to lean ZDF littermates. Temporal feeding patterns were assessed, then rats were harvested at Zeitgeber (ZT, ZT0=7am) 3, 9, or 15 to measure insulin resistance, SGLT1 (Sodium glucose co-transporter type 1) mRNA expression and intestinal glucose absorption capacity. Known regulators of SGLT1 expression (intestinal sweet taste receptor T1R2/3; clock genes) were also measured to elucidate underlying mechanisms. Results Both ZDF groups exhibited altered circadian food intake. Obese ZDF rats lost circadian rhythmicity of SGLT1 mRNA expression and functional activity. Lean ZDF rats had glucose levels less than half of the obese rats but were still hyperglycemic. Rhythmicity of mRNA expression was maintained but that of functional glucose uptake was blunted. Circadian rhythms of intestinal clock genes were maintained in both groups while there was no discernible rhythm of intestinal glucose transporter gene GLUT2 expression or of the T1R2 component of the sweet taste receptor in either group. In summary, lean and obese ZDF rats exhibited similar disruptions in circadian feeding pattern. Glucose intolerance was evident in lean rats, but only obese ZDF rats further developed diabetes and exhibited disrupted circadian rhythmicity of both SGLT1 mRNA expression and functional activity. Conclusions Our findings suggest that disrupted circadian feeding rhythms contribute to

  18. Intestinal absorptive transport of Genkwanin from Flos genkwa using a single-pass intestinal perfusion rat model.

    PubMed

    Jiang, Cui-Ping; He, Xin; Yang, Xiao-Lin; Zhang, Su-Li; Li, Hui; Song, Zi-Jing; Zhang, Chun-Feng; Yang, Zhong-Lin; Li, Ping

    2014-01-01

    To investigate the absorptive transport behavior of genkwanin and the beneficial effects of monoterpene enhancers with different functional groups, the single-pass intestinal perfusion (SPIP) of rats was used. The results showed that genkwanin was segmentally-dependent and the best absorptive site was the duodenum. The effective permeability coefficient (P eff ) was 1.97 × 10(-4) cm/s and the absorption rate constant (Ka) was 0.62 × 10(-2) s(-1). Transepithelial transportation descended with increasing concentrations of genkwanin. This was a 1.4-fold increase in P eff by probenecid, whereas a 1.4-fold or 1.6-fold decrease was observed by verapamil and pantoprazole, respectively. Furthermore, among the absorption enhancers, the enhancement with carbonyl (camphor and menthone) was higher than that with hydroxyl (borneol and menthol). The concentration-independent permeability and enhancement by coperfusion of probenecid indicated that genkwanin was transported by both passive diffusion and multidrug resistance protein (MDR)-mediated efflux mechanisms.

  19. Distinct Firing Properties of Vasoactive Intestinal Peptide-Expressing Neurons in the Suprachiasmatic Nucleus

    PubMed Central

    Hermanstyne, Tracey O.; Simms, Carrie L.; Carrasquillo, Yarimar; Herzog, Erik D.; Nerbonne, Jeanne M.

    2016-01-01

    The suprachiasmatic nucleus (SCN) regulates daily rhythms in physiology and behavior. Previous studies suggest a critical role for neurons expressing vasoactive intestinal peptide (VIP) in coordinating rhythmicity and synchronization in the SCN. Here we examined the firing properties of VIP-expressing SCN neurons in acute brain slices. Active and passive membrane properties were measured in VIP and in non-VIP neurons during the day and at night. Current-clamp recordings revealed that both VIP and non-VIP neurons were spontaneously active, with higher firing rates during the day than at night. Average firing frequencies, however, were higher in VIP neurons (3.1 ± 0.2 Hz, day and 2.4 ± 0.2 Hz, night) than in non-VIP neurons (1.8 ± 0.2 Hz, day and 0.9 ± 0.2 Hz, night), both day and night. The waveforms of individual action potentials in VIP and non-VIP neurons were also distinct. Action potential durations (APD50) were shorter in VIP neurons (3.6 ± 0.1 ms, day and 2.9 ± 0.1 ms, night) than in non-VIP neurons (4.4 ± 0.3 ms, day and 3.5 ± 0.2 ms, night) throughout the light-dark cycle. In addition, after hyper polarization (AHP) amplitudes were larger in VIP neurons (21 ± 0.8 mV, day and 24.9 ± 0.9 mV, night) than in non-VIP neurons (17.2 ± 1.1 mV, day and 20.5 ± 1.2 mV, night) during the day and at night. Furthermore, significant day/night differences were observed in APD50 and AHP amplitudes in both VIP and non-VIP SCN neurons, consistent with rhythmic changes in ionic conductances that contribute to shaping the firing properties of both cell types. The higher day and night firing rates of VIP neurons likely contribute to synchronizing electrical activity in the SCN. PMID:26712166

  20. Vasoactive intestinal peptide downregulates proinflammatory TLRs while upregulating anti-inflammatory TLRs in the infected cornea.

    PubMed

    Jiang, Xiaoyu; McClellan, Sharon A; Barrett, Ronald P; Zhang, Yunfan; Hazlett, Linda D

    2012-07-01

    TLRs recognize microbial pathogens and trigger an immune response, but their regulation by neuropeptides, such as vasoactive intestinal peptide (VIP), during Pseudomonas aeruginosa corneal infection remains unexplored. Therefore, C57BL/6 (B6) mice were injected i.p. with VIP, and mRNA, protein, and immunostaining assays were performed. After VIP treatment, PCR array and real-time RT-PCR demonstrated that proinflammatory TLRs (conserved helix-loop-helix ubiquitous kinase, IRAK1, TLR1, TLR4, TLR6, TLR8, TLR9, and TNFR-associated factor 6) were downregulated, whereas anti-inflammatory TLRs (single Ig IL-1-related receptor [SIGIRR] and ST2) were upregulated. ELISA showed that VIP modestly downregulated phosphorylated inhibitor of NF-κB kinase subunit α but upregulated ST2 ~2-fold. SIGIRR was also upregulated, whereas TLR4 immunostaining was reduced in cornea; all confirmed the mRNA data. To determine whether VIP effects were cAMP dependent, mice were injected with small interfering RNA for type 7 adenylate cyclase (AC7), with or without VIP treatment. After silencing AC7, changes in mRNA levels of TLR1, TNFR-associated factor 6, and ST2 were seen and unchanged with addition of VIP, indicating that their regulation was cAMP dependent. In contrast, changes were seen in mRNA levels of conserved helix-loop-helix ubiquitous kinase, IRAK1, 2, TLR4, 9 and SIGIRR following AC7 silencing alone; these were modified by VIP addition, indicating their cAMP independence. In vitro studies assessed the effects of VIP on TLR regulation in macrophages and Langerhans cells. VIP downregulated mRNA expression of proinflammatory TLRs while upregulating anti-inflammatory TLRs in both cell types. Collectively, the data provide evidence that VIP downregulates proinflammatory TLRs and upregulates anti-inflammatory TLRs and that this regulation is both cAMP dependent and independent and involves immune cell types found in the infected cornea.

  1. Transport phenomena of microbial flora in the small intestine with peristalsis.

    PubMed

    Ishikawa, T; Sato, T; Mohit, G; Imai, Y; Yamaguchi, T

    2011-06-21

    The gastrointestinal tract of humans is colonized by indigenous prokaryotic and eukaryotic microbial cells that form a complex ecological system called microbial flora. Although the microbial flora has diverse functions, its homeostasis inside the gastrointestinal tract is still largely unknown. Therefore, creating a model for investigating microbial flora in the gastrointestinal tract is important. In this study, we developed a novel numerical model to explore the transport phenomena of microbial flora in the small intestine. By simultaneously solving the flow field generated by peristalsis, the concentrations of oxygen and nutrient, and the densities of moderate anaerobes and aerobes, the effects of fluid mechanics on the transport phenomena of microbial flora are discussed. The results clearly illustrated that fluid mechanics have considerable influence not only on the bacterial population, but also on the concentration distributions of oxygen and nutrient. Especially, the flow field enhances the radial variation of the concentration fields. We also show scaling arguments for bacterial growth and oxygen consumption, which capture the main features of the results. Additionally, we investigated the transport phenomena of microbial flora in a long tube with 40 constrictions. The results showed a high growth rate of aerobes in the upstream side and a high growth rate of anaerobes in the downstream side, which qualitatively agrees with experimental observations of human intestines. These new findings provide the fundamental basis for a better understanding of the transport phenomena of microbial flora in the intestine. Copyright © 2011 Elsevier Ltd. All rights reserved.

  2. Conditional (intestinal-specific) knockout of the riboflavin transporter-3 (RFVT-3) impairs riboflavin absorption

    PubMed Central

    Subramanian, Veedamali S.; Lambrecht, Nils; Lytle, Christian

    2015-01-01

    Riboflavin (RF) is indispensable for normal cell metabolism, proliferation, and growth. The RFVT-3 protein (product of the Slc52a3 gene) is expressed in the gut with the expression being restricted to the apical membrane domain of the polarized intestinal epithelial cells. The relative contribution of RFVT-3 to total carrier-mediated RF uptake in the native intestine, however, is not clear. We addressed this issue in the current investigation using a conditional (intestinal-specific) RFVT-3 knockout (cKO) mouse model developed by the Cre/Lox approach. All RFVT-3 cKO mice were found to be RF deficient and showed a significant growth and development retardation; also, nearly two-thirds of them died prematurely between the age of 6 and 12 wk. In vivo (intestinal and colonic loops) and in vitro (native isolated intestinal epithelial cells) uptake studies showed a severe inhibition in carrier-mediated RF uptake in the cKO mice compared with control littermates. We also observed a significant increase in the level of expression of oxidative stress-responsive genes in the intestine of the cKO mice compared with control littermates. Supplementation of the RFVT-3 cKO mice with pharmacological doses of RF led to a complete correction of the growth retardation and to normalization in the level of expression of the oxidative stress-responsive genes in the gut. These results show, for the first time, that the RFVT-3 system is the main transporter involved in carrier-mediated RF uptake in the native mouse small and large intestine, and that its dysfunction impairs normal RF body homeostasis. PMID:26660539

  3. Conditional (intestinal-specific) knockout of the riboflavin transporter-3 (RFVT-3) impairs riboflavin absorption.

    PubMed

    Subramanian, Veedamali S; Lambrecht, Nils; Lytle, Christian; Said, Hamid M

    2016-02-15

    Riboflavin (RF) is indispensable for normal cell metabolism, proliferation, and growth. The RFVT-3 protein (product of the Slc52a3 gene) is expressed in the gut with the expression being restricted to the apical membrane domain of the polarized intestinal epithelial cells. The relative contribution of RFVT-3 to total carrier-mediated RF uptake in the native intestine, however, is not clear. We addressed this issue in the current investigation using a conditional (intestinal-specific) RFVT-3 knockout (cKO) mouse model developed by the Cre/Lox approach. All RFVT-3 cKO mice were found to be RF deficient and showed a significant growth and development retardation; also, nearly two-thirds of them died prematurely between the age of 6 and 12 wk. In vivo (intestinal and colonic loops) and in vitro (native isolated intestinal epithelial cells) uptake studies showed a severe inhibition in carrier-mediated RF uptake in the cKO mice compared with control littermates. We also observed a significant increase in the level of expression of oxidative stress-responsive genes in the intestine of the cKO mice compared with control littermates. Supplementation of the RFVT-3 cKO mice with pharmacological doses of RF led to a complete correction of the growth retardation and to normalization in the level of expression of the oxidative stress-responsive genes in the gut. These results show, for the first time, that the RFVT-3 system is the main transporter involved in carrier-mediated RF uptake in the native mouse small and large intestine, and that its dysfunction impairs normal RF body homeostasis.

  4. Effects of the mucoadhesive polymer polycarbophil on the intestinal absorption of a peptide drug in the rat.

    PubMed

    Lehr, C M; Bouwstra, J A; Kok, W; De Boer, A G; Tukker, J J; Verhoef, J C; Breimer, D D; Junginger, H E

    1992-05-01

    The absorption across rat intestinal tissue of the model peptide drug 9-desglycinamide, 8-arginine vasopressin from bioadhesive formulations was studied in-vitro, in a chronically isolated internal loop in-situ and after intraduodenal administration in-vivo. A controlled-release bioadhesive drug delivery system was tested, consisting of microspheres of poly(2-hydroxyethyl methacrylate) with a mucoadhesive Polycarbophil-coating, as well as fast-release formulation consisting of an aqueous solution of the peptide in a suspension of Polycarbophil particles. Using the controlled-release system, a slight improvement of peptide absorption was found in-vitro in comparison with a non-adhesive control system, but not in-situ or in-vivo. In contrast, bioavailability was significantly increased in all three models from the Polycarbophil suspension in comparison with a solution of the drug in saline. The effect appeared to be dose-dependent, indicative of intrinsic penetration-enhancing properties of the mucoadhesive polymer. A prolongation of the absorption phase in-vitro and in the chronically isolated loop in-situ suggested that the polymer was able to protect the peptide from proteolytic degradation. This could be confirmed by degradation studies in-vitro. The duration of the penetration enhancing/enzyme inhibiting effect was diminished with increasing complexity of the test model, in the same way as was previously found for the bioadhesive effect. This interrelationship suggests that the observed improvement in peptide absorption and the mucoadhesive properties of this polymer are associated. The development of a fast-release oral dosage form for peptide drugs on the basis of Polycarbophil appears to be possible.

  5. A peptide zipcode sufficient for anterograde transport within amyloid precursor protein

    PubMed Central

    Satpute-Krishnan, Prasanna; DeGiorgis, Joseph A.; Conley, Michael P.; Jang, Marcus; Bearer, Elaine L.

    2006-01-01

    Fast anterograde transport of membrane-bound organelles delivers molecules synthesized in the neuronal cell body outward to distant synapses. Identification of the molecular “zipcodes” on organelles that mediate attachment and activation of microtubule-based motors for this directed transport is a major area of inquiry. Here we identify a short peptide sequence (15 aa) from the cytoplasmic C terminus of amyloid precursor protein (APP-C) sufficient to mediate the anterograde transport of peptide-conjugated beads in the squid giant axon. APP-C beads travel at fast axonal transport rates (0.53 μm/s average velocity, 0.9 μm/s maximal velocity) whereas beads coupled to other peptides coinjected into the same axon remain stationary at the injection site. This transport appears physiologic, because it mimics behavior of endogenous squid organelles and of beads conjugated to C99, a polypeptide containing the full-length cytoplasmic domain of amyloid precursor protein (APP). Beads conjugated to APP lacking the APP-C domain are not transported. Coinjection of APP-C peptide reduces C99 bead motility by 75% and abolishes APP-C bead motility, suggesting that the soluble peptide competes with protein-conjugated beads for axoplasmic motor(s). The APP-C domain is conserved (13/15 aa) from squid to human, and peptides from either squid or human APP behave similarly. Thus, we have identified a conserved peptide zipcode sufficient to direct anterograde transport of exogenous cargo and suggest that one of APP's roles may be to recruit and activate axonal machinery for endogenous cargo transport. PMID:17062754

  6. Upregulation of intestinal glucose transporters after Roux-en-Y gastric bypass to prevent carbohydrate malabsorption.

    PubMed

    Nguyen, Nam Q; Debreceni, Tamara L; Bambrick, Jenna E; Chia, Bridgette; Deane, Adam M; Wittert, Gary; Rayner, Chris K; Horowitz, Michael; Young, Richard L

    2014-10-01

    To determine the effect of Roux-en-Y gastric bypass (RYGB) on the expression of intestinal sweet taste receptors (STRs), glucose transporters (GTs), glucose absorption, and glycemia. Intestinal biopsies were collected for mRNA expression of STR (T1R2) and GTs (SGLT-1 and GLUT2) from 11 non-diabetic RYGB, 13 non-diabetic obese, and 11 healthy subjects, at baseline and following a 30 min small intestinal (SI) glucose infusion (30 g/150 ml water with 3 g 3-O-methyl-d-glucopyranose (3-OMG)). Blood glucose, plasma 3-OMG, and insulin were measured for 270 min. In RYGB patients, expression of both GTs was ∼2-fold higher at baseline and after glucose infusion than those of morbidly obese or healthy subjects (P < 0.001). STR expressions were comparable amongst the groups. Peak plasma 3-OMG in both RYGB (r = 0.69, P = 0.01) and obese (r = 0.72, P = 0.005) correlated with baseline expression of SGLT-1, as was the case with peak blood glucose in RYGB subjects (r = 0.69, P = 0.02). The upregulated intestinal GTs in RYGB patients are associated with increased glucose absorption when glucose is delivered at a physiological rate, suggesting a molecular adaptation to prevent carbohydrate malabsorption from rapid intestinal transit after RYGB. Copyright © 2014 The Obesity Society.

  7. A permeation enhancer for increasing transport of therapeutic macromolecules across the intestine.

    PubMed

    Gupta, Vivek; Hwang, Byeong Hee; Doshi, Nishit; Mitragotri, Samir

    2013-12-10

    Delivery of therapeutic macromolecules is limited by the physiological limitations of the gastrointestinal tract including poor intestinal permeability, low pH and enzymatic activity. Several permeation enhancers have been proposed to enhance intestinal permeability of macromolecules; however their utility is often hindered by toxicity and limited potency. Here, we report on a novel permeation enhancer, Dimethyl palmitoyl ammonio propanesulfonate (PPS), with excellent enhancement potential and minimal toxicity. PPS was tested for dose- and time-dependent cytotoxicity, delivery of two model fluorescent molecules, sulforhodamine-B and FITC-insulin in vitro, and absorption enhancement of salmon calcitonin (sCT) in vivo. Caco-2 studies revealed that PPS is an effective enhancer of macromolecular transport while being minimally toxic. TEER measurements in Caco-2 monolayers confirmed the reversibility of the effect of PPS. Confocal microscopy studies revealed that molecules permeate via both paracellular and transcellular pathways in the presence of PPS. In vivo studies in rats showed that PPS enhanced relative bioavailability of sCT by 45-fold after intestinal administration. Histological studies showed that PPS does not induce damage to the intestine. PPS is an excellent permeation enhancer which provides new opportunities for developing efficacious oral/intestinal delivery systems for therapeutic macromolecules.

  8. Suppression by Trypanosoma brucei of anaphylaxis-mediated ion transport in the small intestine of rats.

    PubMed Central

    Gould, S S; Castro, G A

    1994-01-01

    The hypothesis that failure of hosts infected with Trypanosoma brucei to express type 1 hypersensitivity is related to this parasite's ability to down-regulate IgE production, and not to an innate lack of allergenicity of T. brucei antigens, was tested by studying anaphylaxis-induced changes in net epithelial ion transport in rats. Transport changes were quantified electrophysiologically in vitro, as a change in transmural short-circuit current when sensitized intestine was challenged with homologous antigen. Rats injected parenterally with trypanosome antigen elicited intestinal anaphylaxis in response to antigenic challenge, whereas the intestine of rats infected with T. brucei failed to respond. Infection with T. brucei also suppressed the anaphylactic response in rats sensitized to and challenged with ovalbumin and T. spiralis-derived antigens. In these cases suppression was related to the ability of T. brucei to block production of IgE, and not to the physiological failure of the epithelial response. However, in rats sensitized by infection with T. spiralis, neither the anaphylactic response nor IgE production were inhibited by T. brucei. Furthermore, intestinal mastocytosis normally associated with trichinosis was unaffected by the trypanosome infection. Results support the conclusion that the failure to express anaphylaxis in T. brucei-infected rats is due to the inhibition of IgE production and not to the lack of allergenicity of trypanosome antigens. PMID:8206518

  9. Characterization of loxoprofen transport in Caco-2 cells: the involvement of a proton-dependent transport system in the intestinal transport of loxoprofen.

    PubMed

    Narumi, Katsuya; Kobayashi, Masaki; Kondo, Ayuko; Furugen, Ayako; Yamada, Takehiro; Takahashi, Natsuko; Iseki, Ken

    2016-11-01

    Loxoprofen, a propionate non-steroidal anti-inflammatory drug (NSAID), is used widely in East Asian countries. However, little is known about the transport mechanisms contributing to its intestinal absorption. The objectives of this study were to characterize the intestinal transport of loxoprofen using the human intestinal Caco-2 cell model. The transport of loxoprofen was investigated in cellular uptake studies. The uptake of loxoprofen into Caco-2 cells was pH- and concentration-dependent, and was described by a Michaelis-Menten equation with passive diffusion (Km : 4.8 mm, Vmax : 142 nmol/mg protein/30 s, and Kd : 2.2 μl/mg protein/30 s). Moreover, the uptake of loxoprofen was inhibited by a typical monocarboxylate transporter (MCT) inhibitor as well as by various monocarboxylates. The uptake of [(14) C] l-lactic acid, a typical MCT substrate, in Caco-2 cells was saturable with relatively high affinity for MCT. Because loxoprofen inhibited the uptake of [(14) C] l-lactic acid in a noncompetitive manner, it was unlikely that loxoprofen uptake was mediated by high-affinity MCT(s). Our results suggest that transport of loxoprofen in Caco-2 cells is, at least in part, mediated by a proton-dependent transport system. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  10. Zinc Transporter SLC39A7/ZIP7 Promotes Intestinal Epithelial Self-Renewal by Resolving ER Stress

    PubMed Central

    Ohashi, Wakana; Kimura, Shunsuke; Iwanaga, Toshihiko; Furusawa, Yukihiro; Irié, Tarou; Izumi, Hironori; Watanabe, Takashi; Hara, Takafumi; Ohara, Osamu; Koseki, Haruhiko; Sato, Toshiro; Robine, Sylvie; Mori, Hisashi; Hattori, Yuichi; Mishima, Kenji; Ohno, Hiroshi; Hase, Koji; Fukada, Toshiyuki

    2016-01-01

    Zinc transporters play a critical role in spatiotemporal regulation of zinc homeostasis. Although disruption of zinc homeostasis has been implicated in disorders such as intestinal inflammation and aberrant epithelial morphology, it is largely unknown which zinc transporters are responsible for the intestinal epithelial homeostasis. Here, we show that Zrt-Irt-like protein (ZIP) transporter ZIP7, which is highly expressed in the intestinal crypt, is essential for intestinal epithelial proliferation. Mice lacking Zip7 in intestinal epithelium triggered endoplasmic reticulum (ER) stress in proliferative progenitor cells, leading to significant cell death of progenitor cells. Zip7 deficiency led to the loss of Olfm4+ intestinal stem cells and the degeneration of post-mitotic Paneth cells, indicating a fundamental requirement for Zip7 in homeostatic intestinal regeneration. Taken together, these findings provide evidence for the importance of ZIP7 in maintenance of intestinal epithelial homeostasis through the regulation of ER function in proliferative progenitor cells and maintenance of intestinal stem cells. Therapeutic targeting of ZIP7 could lead to effective treatment of gastrointestinal disorders. PMID:27736879

  11. Effect of chronic drug treatment on intestinal membrane transport of 14C-L-DOPA

    PubMed Central

    Rivera-Calimlim, Leonor

    1972-01-01

    1. By the use of the everted jejunal sac it was shown that chronic oral treatment of rats with various drugs can either increase or decrease the mucosal transport of 14C-L-DOPA or alter its serosal/tissue ratio. 2. 14C-L-DOPA transport was significantly increased in rats that were chronically treated with L-DOPA and diminished in those that were treated with chlorpromazine and phenobarbitone. 3. Chronic treatment with amantadine and neomycin did not affect 14C-L-DOPA intestinal transport, although direct addition of amantadine to the medium, significantly increased 14C-L-DOPA transport in everted sacs of nontreated rats. Addition of neomycin directly to the medium did not affect 14C-L-DOPA transport. 4. The possible mechanisms of these findings and their clinical significance are discussed. PMID:4655269

  12. Relationships between disaccharide hydrolysis and sugar transport in amphibian small intestine

    PubMed Central

    Parsons, D. S.; Prichard, J. S.

    1971-01-01

    1. A study is described of the relationships which exist between disaccharide hydrolysis and glucose transport in the small intestine of Rana pipiens and Bufo vulgaris. The experiments were undertaken on the intestine perfused in vitro through the vascular system and with fluid circulating through the intestinal lumen. For this system it was found that, with [U-14C]glucose in the intestinal lumen, the apparent specific activity of the glucose appearing in the vascular effluent was not significantly different from that in the lumen. 2. Changes of ionic composition of vascular and luminal fluids, and the presence of phloridzin or strophanthin, had little effect upon the maltase activity in situ in R. pipiens, although this activity was somewhat reduced when the sodium of the intestinal lumen was replaced by lithium. In contrast, in all cases a marked reduction was found in the rate of glucose translocation in the vascular effluent. 3. With Tris substituted for the luminal sodium, there was evidence of a competitive inhibition of the maltase activity in situ by the buffer cation. At the same time, the rate of glucose translocation into the vascular effluent was but little affected and there was an apparent increase in the efficiency with which the cellular systems responsible for the translocation were able to capture the glucose liberated. 4. It was found that competition for transepithelial translocation occurred between the glucose initially present in the intestinal lumen, and glucose derived from either maltose or trehalose. There was no evidence for competition for hydrolysis between maltose and trehalose, yet the glucose units derived from these two disaccharides competed with each other for translocation. 5. The significance is discussed of the finding that it is possible to dissociate the processes of disaccharide hydrolysis from those underlying the translocation of hexose units into the vascular effluent. It is suggested that monosaccharide units released

  13. Chronic alcohol feeding inhibits physiological and molecular parameters of intestinal and renal riboflavin transport

    PubMed Central

    Subramanian, Veedamali S.; Subramanya, Sandeep B.; Ghosal, Abhisek

    2013-01-01

    Vitamin B2 (riboflavin, RF) is essential for normal human health. Mammals obtain RF from exogenous sources via intestinal absorption and prevent its urinary loss by reabsorption in the kidneys. Both of these absorptive events are carrier-mediated and involve specific RF transporters (RFVTs). Chronic alcohol consumption in humans is associated with a high prevalence of RF deficiency and suboptimal levels, but little is known about the effect of chronic alcohol exposure on physiological and molecular parameters of the intestinal and renal RF transport events. We addressed these issues using rats chronically fed an alcohol liquid diet and pair-fed controls as a model. The results showed that chronic alcohol feeding significantly inhibits carrier-mediated RF transport across the intestinal brush-border and basolateral membrane domains of the polarized enterocytes. This inhibition was associated with a parallel reduction in the expression of the rat RFVT-1 and -3 at the protein, mRNA, and heterogeneous nuclear RNA (hnRNA) levels. Chronic alcohol feeding also caused a significant inhibition in RF uptake in the colon. Similarly, a significant inhibition in carrier-mediated RF transport across the renal brush-border and basolateral membrane domains was observed, which again was associated with a significant reduction in the level of expression of RFVT-1 and -3 at the protein, mRNA, and hnRNA levels. These findings demonstrate that chronic alcohol exposure impairs both intestinal absorption and renal reabsorption processes of RF and that these effects are, at least in part, mediated via transcriptional mechanism(s) involving the slc52a1 and slc52a3 genes. PMID:23804199

  14. Perinatal upregulation of intestinal transport of carnitine (C) in newborn pigs

    SciTech Connect

    Li, B.U.K.; Murray, R.D.; Heitlinger, L.A.; McClung, H.J.; Hughes, A.M.; O'Dorisio, T.M.; Sloan, H.R. Ohio State Univ., Columbus )

    1990-02-26

    Since C facilitates the perinatal transition from carbohydrate to lipid-derived energy, the authors examined the contribution of intestinal transport of dietary C to this process by determining (C)'s in sow's milk, pig jejunum and liver, and C flux across the jejunum (J{sub m-s}) as a function of postnatal age. The authors measured portal venous glucagon (G) and insulin (l) as potential regulatory signals and attempted to alter intestinal transport of C by infusing G. Pigs at days 1-7 (NB-newborn), 14-16 (SU-suckling) and 33-35 (WN-weanling) were studied. (C)'s in sow milk, piglet jejunum, and liver were determined. Fluxes were measured in an Ussing chamber and in an in situ recirculating jejunal perfusion. The effect of an IV infusion of G on ({sup 3}H)C absorption was evaluated in a single animal; an adjacent jejunal segment received saline. Sow's milk and liver (C)'s, and jejunal C transport were highest following birth and declined towards weaning. Plasma (G) and the G:I ratio demonstrated a parallel temporal pattern. The G-stimulated jejunal segment removed 53% of the C and the non-stimulated control segment, 8%. It was concluded that during the perinatal metabolic transition, enhanced intestinal nutrient assimilation promotes the transfer of dietary C to the liver where it could facilitate fatty acid oxidation. This pattern of upregulated intestinal transport immediately after birth may be mediated by pancreatic G and I secretion.

  15. Chronic alcohol feeding inhibits physiological and molecular parameters of intestinal and renal riboflavin transport.

    PubMed

    Subramanian, Veedamali S; Subramanya, Sandeep B; Ghosal, Abhisek; Said, Hamid M

    2013-09-01

    Vitamin B2 (riboflavin, RF) is essential for normal human health. Mammals obtain RF from exogenous sources via intestinal absorption and prevent its urinary loss by reabsorption in the kidneys. Both of these absorptive events are carrier-mediated and involve specific RF transporters (RFVTs). Chronic alcohol consumption in humans is associated with a high prevalence of RF deficiency and suboptimal levels, but little is known about the effect of chronic alcohol exposure on physiological and molecular parameters of the intestinal and renal RF transport events. We addressed these issues using rats chronically fed an alcohol liquid diet and pair-fed controls as a model. The results showed that chronic alcohol feeding significantly inhibits carrier-mediated RF transport across the intestinal brush-border and basolateral membrane domains of the polarized enterocytes. This inhibition was associated with a parallel reduction in the expression of the rat RFVT-1 and -3 at the protein, mRNA, and heterogeneous nuclear RNA (hnRNA) levels. Chronic alcohol feeding also caused a significant inhibition in RF uptake in the colon. Similarly, a significant inhibition in carrier-mediated RF transport across the renal brush-border and basolateral membrane domains was observed, which again was associated with a significant reduction in the level of expression of RFVT-1 and -3 at the protein, mRNA, and hnRNA levels. These findings demonstrate that chronic alcohol exposure impairs both intestinal absorption and renal reabsorption processes of RF and that these effects are, at least in part, mediated via transcriptional mechanism(s) involving the slc52a1 and slc52a3 genes.

  16. Modulation of intestinal glucose transport in response to reduced nitrogen supply in young goats.

    PubMed

    Muscher-Banse, A S; Piechotta, M; Schröder, B; Breves, G

    2012-12-01

    The reduction of dietary protein is a common approach in ruminants to decrease the excretion of N because ruminants are able to recycle N efficiently by the rumino-hepatic circulation. In nonruminant species an impact on other metabolic pathways such as glucose metabolism was observed when dietary protein intake was reduced. However, an impact of dietary N reduction in goats on glucose metabolism especially on intestinal glucose absorption is questionable because ruminants have very efficient endogenous recycling mechanisms. Therefore, the aim of the present study was to characterize the intestinal absorption of glucose in growing goats kept on different N supply under isoenergetic conditions. The different CP concentrations (20, 16, 10, 9, and 7% CP) of the experimental diets were adjusted by adding urea to the rations. Intestinal flux rates of glucose were determined by Ussing chamber experiments. For a more mechanistic approach, the Na(+)-dependent uptake of glucose into intestinal brush-border membrane vesicles (BBMV) and the expression patterns of the Na(+)-dependent glucose transporter SGLT1 and the glucose transporter 2 (GLUT2) were determined. Reduced N intake resulted in a decrease of plasma glucose (P < 0.001) and insulin (P = 0.004) concentrations whereas the intestinal flux rates of glucose were elevated (P < 0.001), which were inhibited by phlorizin. However, the uptake of glucose into intestinal BBMV was not changed whereas the expression of SGLT1 on mRNA (P < 0.05) and protein abundance (P = 0.03) was decreased in response to a reduced N intake. The mRNA expression of GLUT2 was not affected. From these data, it can be concluded that the intestinal absorption of glucose was modulated by changes in dietary N intake. It is suggested that intracellular metabolism or basolateral transport systems or both might be activated during this feeding regimen because the apical located SGLT1 might not be involved. Therefore, an impact of dietary N reduction on

  17. Molecular mechanism(s) involved in differential expression of vitamin C transporters along the intestinal tract.

    PubMed

    Subramanian, Veedamali S; Srinivasan, Padmanabhan; Wildman, Alexis J; Marchant, Jonathan S; Said, Hamid M

    2017-04-01

    Mammalian cells utilize two transporters for the uptake of ascorbic acid (AA), Na(+)-dependent vitamin C transporter SVCT-1 and SVCT-2. In the intestine, these transporters are involved in AA absorption and are expressed at the apical and basolateral membrane domains of the polarized epithelia, respectively. Little is known about the differential expression of these two transporters along the anterior-posterior axis of the intestinal tract and the molecular mechanism(s) that dictate this pattern of expression. We used mouse and human intestinal cDNAs to address these issues. The results showed a significantly lower rate of carrier-mediated AA uptake by mouse colon than jejunum. This was associated with a significantly lower level of expression of SVCT-1 and SVCT-2 at the protein, mRNA, and heterogeneous nuclear RNA (hnRNA) levels in the colon than the jejunum, implying the involvement of transcriptional mechanism(s). Similarly, expression levels of SVCT-1 and SVCT-2 mRNA and hnRNA were significantly lower in human colon. We also examined the levels of expression of hepatocyte nuclear factor 1α and specificity protein 1, which drive transcription of the Slc23a1 and Slc23a2 promoters, respectively, and found them to be markedly lower in the colon. Furthermore, significantly lower levels of the activating markers for histone (H3) modifications [H3 trimethylation of lysine 4 (H3K4me3) and H3 triacetylation of lysine 9 (H3K9ac)] were observed in the Slc23a1 and Slc23a2 promoters in the colon. These findings show, for the first time, that SVCT-1 and SVCT-2 are differentially expressed along the intestinal tract and that this pattern of expression is, at least in part, mediated via transcriptional/epigenetic mechanisms.NEW & NOTEWORTHY Our findings show, for the first time, that transporters of the water-soluble vitamin ascorbic acid (i.e., the vitamin C transporters SVCT-1 and SVCT-2) are differentially expressed along the length of the intestinal tract and that the

  18. Effect of abdominal surgery on the intestinal absorption of lipophilic drugs: possible role of the lymphatic transport.

    PubMed

    Gershkovich, Pavel; Itin, Constantin; Yacovan, Avihai; Amselem, Shimon; Hoffman, Amnon

    2009-06-01

    Although abdominal surgery is a routine procedure in clinical practice and in preclinical investigation, little is known regarding its effect on the intestinal absorption of drugs. The aim of this study was to investigate the effect of abdominal surgery on the intestinal absorption of highly lipophilic compounds with different absorption mechanisms following oral administration. The 2 compounds that were tested were biopharmaceutical classification system (BCS) class 2 model lipophilic cannabinoid derivatives, dexanabinol and PRS-211,220. Although dexanabinol is mostly absorbed via passive diffusion to the portal blood, PRS-211,220 is absorbed mostly via lymphatic transport. In this work, we compared the absorption of these compounds after abdominal surgery in rat with the absorption data obtained from naïve animals. The outcomes of this investigation showed that the abdominal surgery mostly affected the absorption process on the preenterocyte level, as indicated by the 2-fold increase in the extent of intestinal absorption of dexanabinol, which is a compound with a low degree of intestinal lymphatic transport. However, the lymphatic transport was not affected by the surgical procedure as evident by the absence of change in the extent of absorption of PRS-211,220, which is transported to the systemic circulation mainly by intestinal lymphatics. In conclusion, abdominal surgery can significantly affect the intestinal absorption of lipophilic drugs; however, intestinal lymphatic transport seems to be less affected by the abdominal surgery.

  19. Human Enteroids as a Model of Upper Small Intestinal Ion Transport Physiology and Pathophysiology.

    PubMed

    Foulke-Abel, Jennifer; In, Julie; Yin, Jianyi; Zachos, Nicholas C; Kovbasnjuk, Olga; Estes, Mary K; de Jonge, Hugo; Donowitz, Mark

    2016-03-01

    Human intestinal crypt-derived enteroids are a model of intestinal ion transport that require validation by comparison with cell culture and animal models. We used human small intestinal enteroids to study neutral Na(+) absorption and stimulated fluid and anion secretion under basal and regulated conditions in undifferentiated and differentiated cultures to show their functional relevance to ion transport physiology and pathophysiology. Human intestinal tissue specimens were obtained from an endoscopic biopsy or surgical resections performed at Johns Hopkins Hospital. Crypts were isolated, enteroids were propagated in culture, induced to undergo differentiation, and transduced with lentiviral vectors. Crypt markers, surface cell enzymes, and membrane ion transporters were characterized using quantitative reverse-transcription polymerase chain reaction, immunoblot, or immunofluorescence analyses. We used multiphoton and time-lapse confocal microscopy to monitor intracellular pH and luminal dilatation in enteroids under basal and regulated conditions. Enteroids differentiated upon withdrawal of WNT3A, yielding decreased crypt markers and increased villus-like characteristics. Na(+)/H(+) exchanger 3 activity was similar in undifferentiated and differentiated enteroids, and was affected by known inhibitors, second messengers, and bacterial enterotoxins. Forskolin-induced swelling was completely dependent on cystic fibrosis transmembrane conductance regulator and partially dependent on Na(+)/H(+) exchanger 3 and Na(+)/K(+)/2Cl(-) cotransporter 1 inhibition in undifferentiated and differentiated enteroids. Increases in cyclic adenosine monophosphate with forskolin caused enteroid intracellular acidification in HCO3(-)-free buffer. Cyclic adenosine monophosphate-induced enteroid intracellular pH acidification as part of duodenal HCO3(-) secretion appears to require cystic fibrosis transmembrane conductance regulator and electrogenic Na(+)/HCO3(-) cotransporter 1

  20. Stereospecific transport of Tyr-MIF-1 across the blood-brain barrier by peptide transport system-1

    SciTech Connect

    Banks, W.A.; Kastin, A.J.; Michals, E.A.; Barrera, C.M. )

    1990-10-01

    Previous studies have suggested that peptide transport system-1 (PTS-1), the saturable system that transports Tyr-MIF-1, the enkephalins, and related peptides out of the central nervous system (CNS), exhibits stereospecificity. In the present studies, we showed that {sup 125}I-L-Tyr-MIF-1, but not {sup 131}I-D-Tyr-MIF-1, was cleared from the CNS more rapidly than could be accounted for by nonspecific mechanisms. Such clearance was inhibited by a 1.0 nmol dose of L-Tyr-MIF-1, but not by D-Tyr-MIF-1. Neither L- nor D-Tyr-MIF-1 altered the much lower clearance of I-D-Tyr-MIF-1 from the brain. Radioactivity recovered from the vascular space after the injection of {sup 125}I-Tyr-MIF-1 into the lateral ventricle of the brain eluted by HPLC primarily as intact peptide, demonstrating that most of the Tyr-MIF-1 was not degraded during transport. By contrast, the nonsaturable unidirectional influx of Tyr-MIF-1 into the CNS did not distinguish between the isomers. These studies confirm and extend the observations that Tyr-MIF-1 is transported out of the CNS by a saturable, stereospecific transport system as an intact peptide while the influx into the CNS is by a nonsaturable mechanism that does not distinguish between the isomers.

  1. Surface expression, peptide repertoire, and thermostability of chicken class I molecules correlate with peptide transporter specificity

    PubMed Central

    Tregaskes, Clive A.; Harrison, Michael; Sowa, Anna K.; van Hateren, Andy; Hunt, Lawrence G.; Vainio, Olli; Kaufman, Jim

    2016-01-01

    The chicken major histocompatibility complex (MHC) has strong genetic associations with resistance and susceptibility to certain infectious pathogens. The cell surface expression level of MHC class I molecules varies as much as 10-fold between chicken haplotypes and is inversely correlated with diversity of peptide repertoire and with resistance to Marek’s disease caused by an oncogenic herpesvirus. Here we show that the average thermostability of class I molecules isolated from cells also varies, being higher for high-expressing MHC haplotypes. However, we find roughly the same amount of class I protein synthesized by high- and low-expressing MHC haplotypes, with movement to the cell surface responsible for the difference in expression. Previous data show that chicken TAP genes have high allelic polymorphism, with peptide translocation specific for each MHC haplotype. Here we use assembly assays with peptide libraries to show that high-expressing B15 class I molecules can bind a much wider variety of peptides than are found on the cell surface, with the B15 TAPs restricting the peptides available. In contrast, the translocation specificity of TAPs from the low-expressing B21 haplotype is even more permissive than the promiscuous binding shown by the dominantly expressed class I molecule. B15/B21 heterozygote cells show much greater expression of B15 class I molecules than B15/B15 homozygote cells, presumably as a result of receiving additional peptides from the B21 TAPs. Thus, chicken MHC haplotypes vary in several correlated attributes, with the most obvious candidate linking all these properties being molecular interactions within the peptide-loading complex (PLC). PMID:26699458

  2. Role of the sodium-dependent multivitamin transporter (SMVT) in the maintenance of intestinal mucosal integrity.

    PubMed

    Sabui, Subrata; Bohl, Jennifer Ann; Kapadia, Rubina; Cogburn, Kyle; Ghosal, Abhisek; Lambrecht, Nils W; Said, Hamid M

    2016-09-01

    Utilizing a conditional (intestinal-specific) knockout (cKO) mouse model, we have recently shown that the sodium-dependent multivitamin transporter (SMVT) (SLC5A6) is the only biotin uptake system that operates in the gut and that its deletion leads to biotin deficiency. Unexpectedly, we also observed that all SMVT-cKO mice develop chronic active inflammation, especially in the cecum. Our aim here was to examine the role of SMVT in the maintenance of intestinal mucosal integrity [permeability and expression of tight junction (TJ) proteins]. Our results showed that knocking out the mouse intestinal SMVT is associated with a significant increase in gut permeability and with changes in the level of expression of TJ proteins. To determine whether these changes are related to the state of biotin deficiency that develops in SMVT-cKO mice, we induced (by dietary means) biotin deficiency in wild-type mice and examined its effect on the above-mentioned parameters. The results showed that dietary-induced biotin deficiency leads to a similar development of chronic active inflammation in the cecum with an increase in the level of expression of proinflammatory cytokines, as well as an increase in intestinal permeability and changes in the level of expression of TJ proteins. We also examined the effect of chronic biotin deficiency on permeability and expression of TJ proteins in confluent intestinal epithelial Caco-2 monolayers but observed no changes in these parameters. These results show that the intestinal SMVT plays an important role in the maintenance of normal mucosal integrity, most likely via its role in providing biotin to different cells of the gut mucosa.

  3. Role of the sodium-dependent multivitamin transporter (SMVT) in the maintenance of intestinal mucosal integrity

    PubMed Central

    Sabui, Subrata; Bohl, Jennifer Ann; Kapadia, Rubina; Cogburn, Kyle; Ghosal, Abhisek; Lambrecht, Nils W.

    2016-01-01

    Utilizing a conditional (intestinal-specific) knockout (cKO) mouse model, we have recently shown that the sodium-dependent multivitamin transporter (SMVT) (SLC5A6) is the only biotin uptake system that operates in the gut and that its deletion leads to biotin deficiency. Unexpectedly, we also observed that all SMVT-cKO mice develop chronic active inflammation, especially in the cecum. Our aim here was to examine the role of SMVT in the maintenance of intestinal mucosal integrity [permeability and expression of tight junction (TJ) proteins]. Our results showed that knocking out the mouse intestinal SMVT is associated with a significant increase in gut permeability and with changes in the level of expression of TJ proteins. To determine whether these changes are related to the state of biotin deficiency that develops in SMVT-cKO mice, we induced (by dietary means) biotin deficiency in wild-type mice and examined its effect on the above-mentioned parameters. The results showed that dietary-induced biotin deficiency leads to a similar development of chronic active inflammation in the cecum with an increase in the level of expression of proinflammatory cytokines, as well as an increase in intestinal permeability and changes in the level of expression of TJ proteins. We also examined the effect of chronic biotin deficiency on permeability and expression of TJ proteins in confluent intestinal epithelial Caco-2 monolayers but observed no changes in these parameters. These results show that the intestinal SMVT plays an important role in the maintenance of normal mucosal integrity, most likely via its role in providing biotin to different cells of the gut mucosa. PMID:27492331

  4. Modulatory Effects of Vasoactive Intestinal Peptide on Intestinal Mucosal Immunity and Microbial Community of Weaned Piglets Challenged by an Enterotoxigenic Escherichia coli (K88)

    PubMed Central

    Xu, Chunlan; Wang, Youming; Sun, Rui; Qiao, Xiangjin; Shang, Xiaoya; Niu, Weining

    2014-01-01

    Toll-like receptors (TLRs) recognize microbial pathogens and trigger immune response, but their regulation by neuropeptide-vasoactive intestinal peptide (VIP) in weaned piglets infected by enterotoxigenic Escherichia coli (ETEC) K88 remains unexplored. Therefore, the study was conducted to investigate its role using a model of early weaned piglets infected by ETEC K88. Male Duroc×Landrace×Yorkshire piglets (n = 24) were randomly divided into control, ETEC K88, VIP, and ETEC K88+VIP groups. On the first three days, ETEC K88 and ETEC K88+VIP groups were orally administrated with ETEC K88, other two groups were given sterile medium. Then each piglet from VIP and ETEC K88+VIP group received 10 nmol VIP intraperitoneally (i.p.) once daily, on day four and six. On the seventh day, the piglets were sacrificed. The results indicated that administration of VIP improved the growth performance, reduced diarrhea incidence of ETEC K88 challenged pigs, and mitigated the histopathological changes of intestine. Serum levels of IL-2, IL-6, IL-12p40, IFN-γ and TNF-α in the ETEC K88+ VIP group were significantly reduced compared with those in the ETEC group. VIP significantly increased IL-4, IL-10, TGF-β and S-IgA production compared with the ETEC K88 group. Besides, VIP could inhibit the expression of TLR2, TLR4, MyD88, NF-κB p65 and the phosphorylation of IκB-α, p-ERK, p-JNK, and p-38 induced by ETEC K88. Moreover, VIP could upregulate the expression of occludin in the ileum mucosa compared with the ETEC K88 group. Colon and caecum content bacterial richness and diversity were lower for pigs in the ETEC group than the unchallenged groups. These results demonstrate that VIP is beneficial for the maturation of the intestinal mucosal immune system and elicited local immunomodulatory activities. The TLR2/4-MyD88 mediated NF-κB and MAPK signaling pathway may be critical to the mechanism underlying the modulatory effect of VIP on intestinal mucosal immune function and

  5. Transepithelial transport of ambroxol hydrochloride across human intestinal Caco-2 cell monolayers.

    PubMed

    Stetinová, Vera; Smetanová, Libuse; Kholová, Dagmar; Svoboda, Zbynek; Kvetina, Jaroslav

    2009-09-01

    This study aimed i) to characterize the transepithelial transport of the mucolytic agent ambroxol hydrochloride across the intestinal barrier, ii) to classify the ambroxol according to Biopharmaceutics Classification System (BCS) and iii) to predict ambroxol absorption in humans. Transport of ambroxol (100, 300 and 1000 micromol/l) was studied in a human colon carcinoma cell line Caco-2 in apical to basolateral and basolateral to apical direction, under iso-pH 7.4 and pH-gradient (6 vs. 7.4) conditions. The relative contribution of the paracellular route was estimated using Ca2+-free transport medium. Ambroxol samples from receiver compartments were analysed by HPLC with UV detection (242 nm). Results showed that ambroxol transport is linear with time, pH-dependent and direction-independent, displays non-saturable (first-order) kinetics. Thus, the transport seems to be transcellular mediated by passive diffusion. Estimated high solubility and high permeability (P(app) = 45 x 10(-6) cm/s) of ambroxol rank it among well absorbed compounds and class I of BCS. It can be expected that the oral dose fraction of ambroxol absorbed in human intestine is high.

  6. Effect of anaerobiosis, dinitrophenol and fluoride on the active intestinal transport of galactose in snail.

    PubMed

    Barber, A; Jordana, R; Ponz, F

    1975-06-01

    The active transport of galactose across the intestinal wall (everted sacs) of the snail Cryptomphalus hortensis Müller has been studied in vitro, under several metabolic conditions. Anaerobiosis does not change the serosal/mucosal galactose gradients which are developed in oxygen atmosphere. Dinitrophenol (10(-4) M) greatly increased the O2 uptake by the tissue and clearly inhibits the sugar transport. At 5 times 10(-4) M concentration, DNP totally prevents the uphill transport while the O2 uptake is normal. The inhibition produced by DNP does not increase by anaerobiosis. Fluoride inhibits the galactose transport and also the O2 uptake. It is deduced that in snail intestine the energy for the active transport of galactose can be supplied by aerobic as much as by anaerobic metabolism. The inhibition by dinitrophenol seems to be independent of its uncoupling action on the oxidative phosphorylation. The inhibitory effect of NaF may be due both to glycolisis inhibition and to alteration of the digestive epithelium.

  7. Vesicular transport and apotransferrin in intestinal iron absorption, as shown in the Caco-2 cell model.

    PubMed

    Moriya, Mizue; Linder, Maria C

    2006-02-01

    The potential roles of vesicular transport and apotransferrin (entering from the blood) in intestinal Fe absorption were investigated using Caco-2 cell monolayers with tight junctions in bicameral chambers as a model. As shown previously, addition of 39 microM apotransferrin (apoTf) to the basolateral fluid during absorption studies markedly stimulated overall transport of 1 microM (59)Fe from the apical to the basal chamber and stimulated its basolateral release from prelabeled cells, implicating endo- and exocytosis. Rates of transport more than doubled. Uptake was also stimulated, but only 20%. Specific inhibitors of aspects of vesicular trafficking were applied to determine their potential effects on uptake, retention, and basolateral (overall) transport of (59)Fe. Nocodazole and 5'-(4-fluorosulfonylbenzoyl)-adenosine each reduced uptake and basolateral transport up to 50%. Brefeldin A inhibited about 10%. Tyrphostin A8 (AG10) reduced uptake 35% but markedly stimulated basolateral efflux, particularly that dependent on apoTf. Cooling of cells to 4 degrees C (which causes depolymerization of microtubules and lowers energy availability) profoundly inhibited uptake and basolateral transfer of Fe (7- to 12-fold). Apical efflux (which was substantial) was not temperature affected. Our results support the involvement of apoTf cycling in intestinal Fe absorption and indicate that as much as half of the iron uses apoTf and non-apoTf-dependent vesicular pathways to cross the basolateral membrane and brush border of enterocytes.

  8. Analysis of the sodium recirculation theory of solute-coupled water transport in small intestine

    PubMed Central

    Larsen, Erik Hviid; Sørensen, Jakob Balslev; Sørensen, Jens Nørkær

    2002-01-01

    Our previous mathematical model of solute-coupled water transport through the intestinal epithelium is extended for dealing with electrolytes rather than electroneutral solutes. A 3Na+–2K+ pump in the lateral membranes provides the energy-requiring step for driving transjunctional and translateral flows of water across the epithelium with recirculation of the diffusible ions maintained by a 1Na+-1K+–2Cl− cotransporter in the plasma membrane facing the serosal compartment. With intracellular non-diffusible anions and compliant plasma membranes, the model describes the dependence on membrane permeabilities and pump constants of fluxes of water and electrolytes, volumes and ion concentrations of cell and lateral intercellular space (lis), and membrane potentials and conductances. Simulating physiological bioelectrical features together with cellular and paracellular fluxes of the sodium ion, computations predict that the concentration differences between lis and bathing solutions are small for all three ions. Nevertheless, the diffusion fluxes of the ions out of lis significantly exceed their mass transports. It is concluded that isotonic transport requires recirculation of all three ions. The computed sodium recirculation flux that is required for isotonic transport corresponds to that estimated in experiments on toad small intestine. This result is shown to be robust and independent of whether the apical entrance mechanism for the sodium ion is a channel, a SGLT1 transporter driving inward uphill water flux, or an electroneutral Na+–K+–2Cl− cotransporter. PMID:12096047

  9. Transporters for ammonium, amino acids and peptides are expressed in pitchers of the carnivorous plant Nepenthes.

    PubMed

    Schulze, W; Frommer, W B; Ward, J M

    1999-03-01

    Insect capture and digestion contribute substantially to the nitrogen budget of carnivorous plants. In Nepenthes, insect-derived nitrogenous compounds are imported from the pitcher fluid and transported throughout the plant via the vascular tissue to support growth. Import and distribution of nutrients may require transmembrane nitrogen transporters. Representatives of three classes of genes encoding transporters for the nitrogenous compounds ammonium, amino acids and peptides were identified in Nepenthes pitchers. The expression at the cellular level of an ammonium transporter gene, three amino acid transporter genes, and one peptide transporter gene were investigated in the insect trapping organs of Nepenthes. Expression of the ammonium transporter gene NaAMT1 was detected in the head cells of digestive glands in the lower part of the pitcher where NaAMT1 may function in ammonium uptake from the pitcher fluid. One amino acid transporter gene, NaAAP1, was expressed in bundle sheath cells surrounding the vascular tissue. To understand the locations where transmembrane transport could be required within the pitcher, symplasmic and apoplasmic continuity was probed using fluorescent dyes. Symplasmic connections were not found between cortical cells and vascular bundles. Therefore, the amino acid transporter encoded by NaAAP1 may be involved in transport of amino acids into the vascular tissue. In contrast, expression of the peptide transporter gene NaNTR1 was detected in phloem cells of the vascular tissue within pitchers. NaNTR1 may function in the export of nitrogen from the pitcher by loading peptides into the phloem.

  10. Effects of colchicine on the intestinal transport of endogenous lipid. Ultrastructural, biochemical, and radiochemical studies in fasting rats

    SciTech Connect

    Pavelka, M.; Gangl, A.

    1983-03-01

    The involvement of microtubules in the transepithelial transport of exogenous lipid in intestinal absorptive cells has been suggested. Using electronmicroscopic, biochemical, and radiochemical methods, researchers have studied the effects of the antimicrotubular agent colchicine on the intestinal mucosa and on the intestinal transport of endogenous lipid of rats in the fasting state. After colchicine treatment, the concentration of triglycerides in intestinal mucosa of rats fasted for 24 h doubled, and electron microscopic studies showed a striking accumulation of lipid particles in absorptive epithelial cells of the tips of jejunal villi. These findings suggest that colchicine interferes with the intestinal transepithelial transport of endogenous lipoproteins. Additional studies, using an intraduodenal pulse injection of (/sup 14/C)linoleic acid, showed that colchicine does not affect the uptake of fatty acids by intestinal mucosa. However, it had divergent effects on fatty acid esterification, enhancing their incorporation into triglycerides relative to phospholipids, and caused a significant accumulation of endogenous diglycerides, triglycerides, and cholesterol esters within the absorptive intestinal epithelium. Detailed ultrastructural and morphometric studies revealed a decrease of visible microtubules, and a displacement of the smooth and rough endoplasmic reticulum and Golgi apparatus. Furthermore, it is shown that after colchicine treatment, microvilli appear at the lateral plasma membrane of intestinal absorptive cells, a change not previously reported to our knowledge. Thus, our study shows that colchicine causes significant changes in enterocyte ultrastructure and colchicine perturbs the reesterification of absorbed endogenous fatty acids and their secretion in the form of triglyceride-rich lipoproteins from the enterocyte.

  11. Role of sodium ion in transport of folic acid in the small intestine

    SciTech Connect

    Zimmerman, J.; Selhub, J.; Rosenberg, I.H.

    1986-08-01

    The effect of sodium on folate transport across the intestinal luminal membrane was analyzed using two techniques: the influx chamber and isoalted brush-border membrane vesicles. Preincubation of tissue in Na -free medium did not have a consistent effect on folic acid influx provided that Na was present in the test solution. Replacement of Na in the test solution by choline resulted in a significant reduction of folic acid influx. However, when intestinal sheets that had been equilibrated in Na -free solution were exposed to test solutions containing either Na , Li , K , Rb , Cs , Tris , or guanidinium as main cations, folic acid influx was not significantly decreased. Concentration-dependence studies showed that replacement of Na by Rb did not affect the saturable mechanism of folate transport. Rather, a decrease in nonsaturable folic acid uptake accounted for the slightly reduced influx observed in the presence of Rb . Experiments with brush-border membrane vesicles revealed that methotrexate uptake was significantly higher in the presence of external Na than in the presence of K , but was not different from uptake in the presence of K plus valinomycin. These data suggest that 1) the saturable component of folate transport is not Na dependent, and 2) nonsaturable transport of folic acid across the luminal membrane occurs in part through a conductive pathway that involves a negatively charged species of folate and a cation whose membrane permeability affects the rate of folate transport. The importance of Na in this process in vivo derives from the fact that Na is the most permeant cation available at the absorptive site in the small intestine.

  12. The effect of oat β-glucan on in vitro glucose diffusion and glucose transport in rat small intestine.

    PubMed

    Zhang, Yu; Zhang, Hui; Wang, Li; Qian, Haifeng; Qi, Xiguang; Ding, Xiangli; Hu, Bo; Li, Jiajia

    2016-01-30

    Many previous studies have reported the role of oat β-glucan (OBG) in the reduction of postprandial glucose, and hypothesised that OBG may form a protective layer along the intestinal wall, acting as a viscous barrier to decrease glucose transportation. This study examined whether the molecular weight (MW) and concentration of OBG affected the diffusion of glucose in vitro. The effect of OBG on glucose transportation in vitro and sodium-potassium adenosine triphosphatase (Na(+)/K(+)-ATPase) activity in the everted small intestines of normal rats was also examined. In vitro, higher MWs and concentrations of OBG increased the inhibitory effects on glucose diffusion and glucose adsorption. The transport of glucose by glucose transporters and Na(+)/K(+)-ATPase activity in the small intestinal mucosa of rats were significantly lower following the addition of OBG than those in the absence of OBG at the same time-points throughout glucose transportation (P < 0.05). In the OBG-treated group, the Na(+)/K(+)-ATPase activity decreased with increasing OBG MW. However, as the concentration of OBG in the solution increased, the Na(+)/K(+)-ATPase activity in the small intestine increased due to stronger gastrointestinal motility. We also found that higher MWs of OBG had a greater inhibitory effect on intestinal disaccharidase activities in vitro. Oat β-glucan is able to adsorb glucose molecules, inhibit glucose transport, decrease the concentration of available glucose and suppress disaccharidase activities in the small intestine. © 2015 Society of Chemical Industry.

  13. Glugacon-like peptide-2: broad receptor expression, limited therapeutic effect on intestinal inflammation and novel role in liver regeneration.

    PubMed

    El-Jamal, Noura; Erdual, Edmone; Neunlist, Michel; Koriche, Dine; Dubuquoy, Caroline; Maggiotto, Francois; Chevalier, Julien; Berrebi, Dominique; Dubuquoy, Laurent; Boulanger, Eric; Cortot, Antoine; Desreumaux, Pierre

    2014-08-01

    The glucagon-like peptide 2 (GLP-2) is an intestinotrophic hormone with growth promoting and anti-inflammatory actions. However, the full biological functions of GLP-2 and the localization of its receptor (GLP-2R) remain controversial. Among cell lines tested, the expression of GLP-2R transcript was detected in human colonic myofibroblasts (CCD-18Co) and in primary culture of rat enteric nervous system but not in intestinal epithelial cell lines, lymphocytes, monocytes, or endothelial cells. Surprisingly, GLP-2R was expressed in murine (GLUTag), but not human (NCI-H716) enteroendocrine cells. The screening of GLP-2R mRNA in mice organs revealed an increasing gradient of GLP-2R toward the distal gut. An unexpected expression was detected in the mesenteric fat, mesenteric lymph nodes, bladder, spleen, and liver, particularly in hepatocytes. In two mice models of trinitrobenzene sulfonic acid (TNBS)- and dextran sulfate sodium (DSS)-induced colitis, the colonic expression of GLP-2R mRNA was decreased by 60% compared with control mice. Also, GLP-2R mRNA was significantly downregulated in intestinal tissues of inflammatory bowel disease patients. Therapeutically, GLP-2 showed a weak restorative effect on intestinal inflammation during TNBS-induced colitis as assessed by macroscopic score and inflammatory markers. Finally, GLP-2 treatment accelerated mouse liver regeneration following partial hepatectomy as assessed by histological and molecular analyses. In conclusion, the limited therapeutic effect of GLP-2 on colonic inflammation dampens its utility in the management of severe inflammatory intestinal disorders. However, the role of GLP-2 in liver regeneration is a novelty that might introduce GLP-2 into the management of liver diseases and emphasizes on the importance of elucidating other extraintestinal functions of GLP-2.

  14. The influence of small intestinal mucus structure on particle transport ex vivo.

    PubMed

    Bajka, Balázs H; Rigby, Neil M; Cross, Kathryn L; Macierzanka, Adam; Mackie, Alan R

    2015-11-01

    Mucus provides a barrier to bacteria and toxins while allowing nutrient absorption and waste transport. Unlike colonic mucus, small intestinal mucus structure is poorly understood. This study aimed to provide evidence for a continuous, structured mucus layer and assess the diffusion of different sized particles through it. Mucus structure was assessed by histology and immunohistochemistry. Ultra-structure was assessed by scanning electron microscopy. Tracking of 100 nm and 500 nm latex beads was conducted using ex vivo porcine mucus. The porcine jejunum and ileum were filled with mucus. Layered MUC2 staining was visible throughout the small intestine, covering villus tips. Scanning electron microscopy showed net-like mucin sheets covering villi (211 ± 7 nm pore diameter). Particle tracking of 100 nm latex beads, showed no inhibition of diffusion through mucus while 500 nm beads displayed limited diffusion. These results suggest a continuous mucus layer exists throughout the small intestine, which is highly stratified adjacent to the epithelium. The network observed is consistent with previous observations and correlates with stratified MUC2 staining. Mucin pore size is consistent with free diffusion of 100 nm and limited diffusion of 500 nm particles. Small Intestinal mucus structure has important implications for drug delivery systems and prevention and treatment of conditions like mucositis and inflammatory bowel disease. Copyright © 2015 Elsevier B.V. All rights reserved.

  15. Dietary protein quality and feed restriction influence abundance of nutrient transporter mRNA in the small intestine of broiler chicks.

    PubMed

    Gilbert, Elizabeth R; Li, Huifeng; Emmerson, Derek A; Webb, Kenneth E; Wong, Eric A

    2008-02-01

    The objective of this study was to evaluate the effect of dietary protein quality on intestinal peptide transporter (PepT1), amino acid transporter [Na+-independent cationic and zwitterionic amino acid transporter (b(o,+)AT), excitatory amino acid transporter 3 (EAAT3), Na+-independent cationic and Na+-dependent neutral amino acid transporter (y+ LAT2), and Na+-independent cationic amino acid transporter 2 (CAT2)], glucose transporter [Na+-dependent glucose and galactose transporter 1 (SGLT1) and Na+-independent glucose, galactose, and fructose transporter 2 (GLUT2)], and digestive enzyme [aminopeptidase N (APN)] mRNA abundance in 2 lines of broilers (A and B). At day of hatch (doh), chicks from both lines were randomly assigned to corn-based diets containing 24% crude protein with either soybean meal (SBM) or corn gluten meal (CGM) as the supplemental protein source. Chicks were given unlimited access to feed and water. Groups of chicks from both lines were also assigned to the SBM diet at a quantity restricted to that consumed by the CGM group (SBM-RT). Intestinal transporter and enzyme mRNA abundance was assayed by real-time PCR using the absolute quantification method. Abundance of PepT1, EAAT3, and GLUT2 mRNA was greater in Line B (P < 0.03), whereas APN and SGLT1 were greater in Line A (P < 0.04). When feed intake was equal (CGM vs. restricted SBM), a greater abundance of PepT1 and b(o,+)AT mRNA was associated with the higher quality SBM (P < 0.04), whereas a greater abundance of EAAT3 and GLUT2 mRNA was associated with the lower quality CGM (P < 0.01). When feed intake was restricted (SBM vs. SBM-RT), a greater abundance of PepT1 mRNA was associated with the restricted intake (P < 0.04). These data demonstrate that both dietary protein quality and feed restriction influence expression of nutrient transporter mRNA in the small intestine of broiler chicks.

  16. Cargo Delivery into the Brain by in vivo identified Transport Peptides

    PubMed Central

    Urich, Eduard; Schmucki, Roland; Ruderisch, Nadine; Kitas, Eric; Certa, Ulrich; Jacobsen, Helmut; Schweitzer, Christophe; Bergadano, Alessandra; Ebeling, Martin; Loetscher, Hansruedi; Freskgård, Per-Ola

    2015-01-01

    The blood-brain barrier and the blood-cerebrospinal fluid barrier prevent access of biotherapeutics to their targets in the central nervous system and therefore prohibit the effective treatment of neurological disorders. In an attempt to discover novel brain transport vectors in vivo, we injected a T7 phage peptide library and continuously collected blood and cerebrospinal fluid (CSF) using a cisterna magna cannulated conscious rat model. Specific phage clones were highly enriched in the CSF after four rounds of selection. Validation of individual peptide candidates showed CSF enrichments of greater than 1000-fold. The biological activity of peptide-mediated delivery to the brain was confirmed using a BACE1 peptide inhibitor linked to an identified novel transport peptide which led to a 40% reduction of Amyloid-β in CSF. These results indicate that the peptides identified by the in vivo phage selection approach could be useful transporters for systemically administrated large molecules into the brain with therapeutic benefits. PMID:26411801

  17. The Intestinal Transport of Bovine Milk Exosomes Is Mediated by Endocytosis in Human Colon Carcinoma Caco-2 Cells and Rat Small Intestinal IEC-6 Cells.

    PubMed

    Wolf, Tovah; Baier, Scott R; Zempleni, Janos

    2015-10-01

    MicroRNAs play essential roles in gene regulation. A substantial fraction of microRNAs in tissues and body fluids is encapsulated in exosomes, thereby conferring protection against degradation and a pathway for intestinal transport. MicroRNAs in cow milk are bioavailable in humans. This research assessed the transport mechanism of bovine milk exosomes, and therefore microRNAs, in human and rodent intestinal cells. The intestinal transport of bovine milk exosomes and microRNAs was assessed using fluorophore-labeled bovine milk exosomes in human colon carcinoma Caco-2 cells and rat small intestinal IEC-6 cells. Transport kinetics and mechanisms were characterized using dose-response studies, inhibitors of vesicle transport, carbohydrate competitors, proteolysis of surface proteins on cells and exosomes, and transepithelial transport in transwell plates. Exosome transport exhibited saturation kinetics at 37°C [Michaelis constant (Km) = 55.5 ± 48.6 μg exosomal protein/200 μL of media; maximal transport rate = 0.083 ± 0.057 ng of exosomal protein · 81,750 cells(-1) · h(-1)] and decreased by 64% when transport was measured at 4°C, consistent with carrier-mediated transport in Caco-2 cells. Exosome uptake decreased by 61-85% under the following conditions compared with controls in Caco-2 cells: removal of exosome and cell surface proteins by proteinase K, inhibition of endocytosis and vesicle trafficking by synthetic inhibitors, and inhibition of glycoprotein binding by carbohydrate competitors. When milk exosomes, at a concentration of 5 times the Km, were added to the upper chamber in transwell plates, Caco-2 cells accumulated miR-29b and miR-200c in the lower chamber, and reverse transport was minor. Transport characteristics were similar in IEC-6 cells and Caco-2 cells, except that substrate affinity and transporter capacity were lower and higher, respectively. The uptake of bovine milk exosomes is mediated by endocytosis and depends on cell and exosome

  18. Changes in vasoactive intestinal peptide, pituitary adenylate cyclase-activating polypeptide and neuropeptide Y-ergic structures of the enteric nervous system in the carcinoma of the human large intestine.

    PubMed

    Godlewski, Janusz; Łakomy, Ireneusz Mirosław

    2010-01-01

    This investigation was aimed at immunohistochemical analysis of potential changes in the enteric nervous system caused by cancer of the large intestine. In this purpose, neurons and nerve fibers of intestinal plexuses containing neuropeptides: vasoactive intestinal peptide (VIP), pituitary adenylate cyclase-activating polypeptide (PACAP) and neuropeptide Y (NPY), in pathologically changed part of the large intestine were microscpically observed and compared. Samples were taken from patients operated due to cancer of the sigmoid colon and rectum. The number of neurons and density of nerve fibres containing neuropeptides found in sections with cancer tissues were compared to those observed in sections from the uninvolved intestinal wall. Changes relating to reductions in the number of NPY-ergic neurons and density of nerve fibres in submucous and myenteric plexuses in the sections with cancer tissues (pathological sections) were statistically significant. A statistically similar presence of VIP-ergic and PACAP-ergic neurons in the submucosal and myenteric plexuses was observed in both the pathological and control sections. On the other hand, in the pathological sections, VIP-ergic nerve fibres in the myenteric plexuses and PACAP-ergic nerve fibres in the submucosal and myenteric plexuses were found to be less dense. Analysis revealed changes in pathologically affected part of the large intestine may caused disruption of proper intestinal function. Observed changes in the neural elements which are responsible for relaxation of the intestine may suggest dysfunction in the innervation of this part of the colon.

  19. Acetate transport across the intestinal epithelium of an herbivorous teleost. [Oreochromis mossambicus

    SciTech Connect

    Titus, E.; Ahearn, G.A. )

    1990-02-26

    {sup 3}H-acetate transport across the upper intestine of the tilapia, Oreochromis mossabicus, using brush border and basolateral membrane vesicles, and intestinal sheets mounted in modified Ussing chambers was investigated. Brush border and basolateral vesicles demonstrated qualitatively similar anion antiport activity where, in the presence of a full profile of organic and inorganic anions, volatile fatty acids (VFA; acetate, propionate, butyrate) and bicarbonate showed reciprocal trans-stimulation and cis-inhibition of {sup 3}H-acetate influx, suggesting both membranes had the same VFA/bicarbonate exchange mechanism. Kinetic analysis of {sup 3}H-acetate influx into brush border and basolateral vesicles revealed different half-saturation constants (Km) as a function of external acetate concentrations (6.43 mM and 11.91 mM, respectively) and as a function of internal bicarbonate (5.89 mM and 0.41 mM, respectively). Intestinal sheets supported net absorptive fluxes when serosal acetate concentrations were held steady at 1.0 mM and mucosal acetate was varied from 1.60 to 10.0 mM. Unidirectional fluxes were significantly diminished by the addition of acetazolamide. This study postulates a transcellular transport pathway for VFA whereby qualitatively similar antiporters in series lead to a downhill flow of luminal acetate to the blood, which is driven by intracellular carbonic anhydrase and a transmural VFA concentration gradient.

  20. Intestinal ammonia transport in freshwater and seawater acclimated rainbow trout (Oncorhynchus mykiss): evidence for a Na+ coupled uptake mechanism.

    PubMed

    Rubino, Julian G; Zimmer, Alex M; Wood, Chris M

    2015-05-01

    In vitro gut sac experiments were performed on freshwater and 60% seawater acclimated trout (Oncorhynchus mykiss) under treatments designed to discern possible mechanisms of intestinal ammonia transport. Seawater acclimation increased ammonia flux rate into the serosal saline (Jsamm) in the anterior intestine, however it did not alter Jsamm in the mid- or posterior intestine suggesting similar mechanisms of ammonia handling in freshwater and seawater fish. Both fluid transport rate (FTR) and Jsamm were inhibited in response to basolateral ouabain treatment, suggesting a linkage of ammonia uptake to active transport, possibly coupled to fluid transport processes via solvent drag. Furthermore, decreases in FTR and Jsamm caused by low Na(+) treatment indicated a Na(+) linked transport mechanism. Mucosal bumetanide (10(-4) M) had no impact on FTR, yet decreased Jsamm in the anterior and mid-intestine, suggesting NH4(+) substitution for K(+) on an apical NKCC, and at least a partial uncoupling of ammonia transport from fluid transport. Additional treatments (amiloride, 5-(N-ethyl-N-isopropyl)amiloride (EIPA), phenamil, bafilomycin, 4',6-diamidino-2-phenylindole (DAPI), high sodium) intended to disrupt alternative routes of Na(+) uptake yielded no change in FTR or Jsamm, suggesting the absence of direct competition between Na(+) and ammonia for transport. Finally, [(14)C]methylamine permeability (PMA) measurements indicated the likely presence of an intestinal Rh-mediated ammonia transport system, as increasing NH4Cl (0, 1, 5 mmol l(-1)) concentrations reduced PMA, suggesting competition for transport through Rh proteins. Overall, the data presented in this paper provide some of the first insights into mechanisms of teleost intestinal ammonia transport.

  1. Mixing and Transport in the Small Intestine: A Lattice-Boltzmann Model

    NASA Astrophysics Data System (ADS)

    Banco, Gino; Brasseur, James; Wang, Yanxing; Aliani, Amit; Webb, Andrew

    2007-11-01

    The two primary functions of the small intestine are absorption of nutrients into the blood stream and transport of material along the gut for eventual evacuation. The primary transport mechanism is peristalsis. The time scales for absorption, however, rely on mixing and transport of molecules between the bulk flow and epithelial surface. Two basic motions contribute to mixing: peristalsis and repetitive segmental contraction of short segments of the gut. In this study we evaluate the relative roles of peristalsis vs. segmental contraction on the degree of mixing and time scales of nutrient transport to the epithelium using a two-dimensional model of flow and mixing in the small intestine. The model uses the lattice-Boltzmann framework with second-order moving boundary conditions and passive scalar (Sc = 10). Segmental and peristaltic contractions were parameterized using magnetic resonance imaging data from rat models. The Reynolds numbers (1.9), segment lengths (33 mm), max radii (2.75 mm) and occlusion ratios (0.33) were matched for direct comparison. Mixing is quantified by the rate of dispersion of scalar from an initial concentration in the center of the segment. We find that radial mixing is more rapid with segmental than peristaltic motion, that radial dispersion is much more rapid than axial, and that axial is comparable between the motions.

  2. Evidence of lactoferrin transportation into blood circulation from intestine via lymphatic pathway in adult rats.

    PubMed

    Takeuchi, Takashi; Kitagawa, Hiroshi; Harada, Etsumori

    2004-05-01

    Using adult rats, the characteristic transporting system for lactoferrin (LF) from intestinal lumen into the blood circulation was investigated. The rats were randomly divided into two groups, a non-collected thoracic lymph (NC) group and a collected thoracic lymph (LC) group. Peripheral blood and thoracic lymph were collected from a jugular vein and a thoracic lymph duct, respectively, under anaesthesia. Bovine LF (bLF) was infused into the duodenal lumen by needle over a 1-min period at a dose of 1 g kg(-1). The transported bLF in the plasma and lymph was assayed quantitatively by double-antibody enzyme-linked immunosorbent assay (ELISA). Morphological investigation was also carried out in the intestine, lymph node, and liver. Following intraduodenal administration of bLF, the transported bLF in the NC group was detected in the plasma, and reached a peak value at 2 h. Furthermore, the bLF concentration in the thoracic duct lymph fluid in the LC group increased significantly, and peaked 2 h after the administration. In addition, bLF was not detected in the plasma of the LC group. Immunohistochemical analysis clearly showed anti-bLF positive particles in the epithelial cells of the apical villi. The striated border and baso-lateral membrane were also bLF positive. These results suggest that intraduodenally infused bLF is transported into the blood circulation via the lymphatic pathway, not via portal circulation in adult rats.

  3. Peptide Transport through the Blood-Brain Barrier

    DTIC Science & Technology

    1989-01-01

    analogues for treatment of membiry,.ACIH analogues for treatmen of post-traumatic epilepsy), should these peptides be capable of traversing the BBB...thus far. In addition, since cationization does not destroy immunoglobulin G antigenicity, the use of cationized immunoglobulins may be used for... aerosolized insulin. Mixed-meal studies and long-term use in Type I diabetes. N. Engl. J. Med. 312:1078-1084. 12. Pardridge, W.M. (1988): Recent advances in

  4. Transport, metabolism, and endosomal trafficking-dependent regulation of intestinal fructose absorption

    PubMed Central

    Patel, Chirag; Douard, Veronique; Yu, Shiyan; Gao, Nan; Ferraris, Ronaldo P.

    2015-01-01

    Dietary fructose that is linked to metabolic abnormalities can up-regulate its own absorption, but the underlying regulatory mechanisms are not known. We hypothesized that glucose transporter (GLUT) protein, member 5 (GLUT5) is the primary fructose transporter and that fructose absorption via GLUT5, metabolism via ketohexokinase (KHK), as well as GLUT5 trafficking to the apical membrane via the Ras-related protein-in-brain 11 (Rab11)a-dependent endosomes are each required for regulation. Introducing fructose but not lysine and glucose solutions into the lumen increased by 2- to 10-fold the heterogeneous nuclear RNA, mRNA, protein, and activity levels of GLUT5 in adult wild-type mice consuming chow. Levels of GLUT5 were >100-fold that of candidate apical fructose transporters GLUTs 7, 8, and 12 whose expression, and that of GLUT 2 and the sodium-dependent glucose transporter protein 1 (SGLT1), was not regulated by luminal fructose. GLUT5-knockout (KO) mice exhibited no facilitative fructose transport and no compensatory increases in activity and expression of SGLT1 and other GLUTs. Fructose could not up-regulate GLUT5 in GLUT5-KO, KHK-KO, and intestinal epithelial cell-specific Rab11a-KO mice. The fructose-specific metabolite glyceraldehyde did not increase GLUT5 expression. GLUT5 is the primary transporter responsible for facilitative absorption of fructose, and its regulation specifically requires fructose uptake and metabolism and normal GLUT5 trafficking to the apical membrane.—Patel, C., Douard, V., Yu, S., Gao, N., Ferraris, R. P. Transport, metabolism, and endosomal trafficking-dependent regulation of intestinal fructose absorption. PMID:26071406

  5. Single liposome analysis of peptide translocation by the ABC transporter TAPL.

    PubMed

    Zollmann, Tina; Moiset, Gemma; Tumulka, Franz; Tampé, Robert; Poolman, Bert; Abele, Rupert

    2015-02-17

    ATP-binding cassette (ABC) transporters use ATP to drive solute transport across biological membranes. Members of this superfamily have crucial roles in cell physiology, and some of the transporters are linked to severe diseases. However, understanding of the transport mechanism, especially of human ABC exporters, is scarce. We reconstituted the human lysosomal polypeptide ABC transporter TAPL, expressed in Pichia pastoris, into lipid vesicles (liposomes) and performed explicit transport measurements. We analyzed solute transport at the single liposome level by monitoring the coincident fluorescence of solutes and proteoliposomes in the focal volume of a confocal microscope. We determined a turnover number of eight peptides per minute, which is two orders of magnitude higher than previously estimated from macroscopic measurements. Moreover, we show that TAPL translocates peptides against a large concentration gradient. Maximal filling is not limited by an electrochemical gradient but by trans-inhibition. Countertransport and reversibility studies demonstrate that peptide translocation is a strictly unidirectional process. Altogether, these data are included in a refined model of solute transport by ABC exporters.

  6. Neural regulation of intestinal nutrient absorption.

    PubMed

    Mourad, Fadi H; Saadé, Nayef E

    2011-10-01

    The nervous system and the gastrointestinal (GI) tract share several common features including reciprocal interconnections and several neurotransmitters and peptides known as gut peptides, neuropeptides or hormones. The processes of digestion, secretion of digestive enzymes and then absorption are regulated by the neuro-endocrine system. Luminal glucose enhances its own absorption through a neuronal reflex that involves capsaicin sensitive primary afferent (CSPA) fibres. Absorbed glucose stimulates insulin release that activates hepatoenteric neural pathways leading to an increase in the expression of glucose transporters. Adrenergic innervation increases glucose absorption through α1 and β receptors and decreases absorption through activation of α2 receptors. The vagus nerve plays an important role in the regulation of diurnal variation in transporter expression and in anticipation to food intake. Vagal CSPAs exert tonic inhibitory effects on amino acid absorption. It also plays an important role in the mediation of the inhibitory effect of intestinal amino acids on their own absorption at the level of proximal or distal segment. However, chronic extrinsic denervation leads to a decrease in intestinal amino acid absorption. Conversely, adrenergic agonists as well as activation of CSPA fibres enhance peptides uptake through the peptide transporter PEPT1. Finally, intestinal innervation plays a minimal role in the absorption of fat digestion products. Intestinal absorption of nutrients is a basic vital mechanism that depends essentially on the function of intestinal mucosa. However, intrinsic and extrinsic neural mechanisms that rely on several redundant loops are involved in immediate and long-term control of the outcome of intestinal function.

  7. cap alpha. -Methylglucoside satisfies only Na/sup +/-dependent transport system of intestinal epithelium

    SciTech Connect

    Kimmich, G.A.; Randles, J.

    1981-01-01

    The unidirectional influx of ..cap alpha..-methylglucoside (..cap alpha..-MG) by isolated chicken intestinal epithelial cells is 98% inhibited by phlorizin. The remaining 2% of the total influx occurs in the absence of Na/sup +/, is not sensitive to phloretin, and is equal to the diffusional entry rate for 2-deoxyglucose. The glucoside is much more strongly accumulated (75-fold) than 3-O-methylglucose (3-OMG) (10-fold). Inhibitors of the serosal sugar carrier (phloretin, cytochalasin B, theophylline, and flavanoids) do not enhance ..cap alpha..-MG accumulation. It is concluded that the glycoside is not a substrate for the intestinal serosal transport system. Steady-state gradients of the sugar can be represented accurately by a concentrative, phlorizin-sensitive system that is opposed by a diffusional efflux process.

  8. Differential cellular expression of organic anion transporting peptides OATP1A2 and OATP2B1 in the human retina and brain: implications for carrier-mediated transport of neuropeptides and neurosteriods in the CNS.

    PubMed

    Gao, Bo; Vavricka, Stephan R; Meier, Peter J; Stieger, Bruno

    2015-07-01

    Organic anion transporting polypeptides (OATPs) are polyspecific organic anion transporters, which are expressed in the blood-brain barrier, the choroid plexus, and other organs. The physiologic function of OATPs in extrahepatic tissues remains ambiguous. In rat retina, members of the OATP family are expressed. We therefore investigated the human retina for the expression of OATP1A2 and OATP2B1 and extended the study to human brain. Furthermore, we searched for peptide neurotransmitters as novel OATP substrates. OATP1A2 displayed a broad expression pattern in human retina as assessed by immunofluorescence localization. It is expressed in photoreceptor bodies and somas of amacrine cells. OATP1B2 expression is restricted to the inner nuclear layer and to the inner plexiform layer. Using paraffin sections from human cortex, cerebellum, and hippocampus, OATP1A2 was localized to neurons and neuronal processes, while OATP2B1 is expressed in endothelial cells of brain capillaries. Substance P and vasoactive intestinal peptide were identified as substrates for OATP1A2 and OATP2B1. Double-labeling immunofluorescence of human retina demonstrated the presence of substance P and of vasoactive intestinal peptides in neurons expressing OATP1A2 and OATP2B1, respectively. The expression of OATP1A2 and OATP2B1 in retinal neurons implies a role of these transporters in the reuptake of peptide neurotransmitters released from retinal neurons. The abundant expression of OATP1A2 in brain neurons points to the possibility that OATP1A2 could be involved in the homeostasis of neurosteroids. The high expression of OATP2B1 in brain capillaries supports an important function of OATPs in substance penetration across the blood-brain barrier.

  9. The effect of parachlorophenylalanine and active immunization against vasoactive intestinal peptide on reproductive activities of broiler breeder hens photostimulated with green light.

    PubMed

    Mobarkey, Nader; Avital, Natalie; Heiblum, Rachel; Rozenboim, Israel

    2013-04-01

    Photostimulation of retinal photoreceptors appears to inhibit reproductive activity in birds. In the present study, the involvement of serotonin and vasoactive intestinal peptide was investigated in relation to reproductive failure associated with retinal photostimulation. Hens at 23 wk of age were divided into six rooms equipped with individual cages. At 24 wk of age, three rooms were photostimulated (14L:10D) with white light (control). Three rooms had two parallel lighting systems, red (660 nm) and green (560 nm), which were both on during 6 h of the 14-h light period. Upon photostimulation, the red light was turned off after 6 h, and the green light was left on for a total of 14 h (Green). Five hens from each room served as controls, five hens were immunized against vasoactive intestinal peptide, and five hens received parachlorophenylalanine, an inhibitor of serotonin biosynthesis. Parachlorophenylalanine treatment increased reproductive performance and mRNA expression of GnRH-I, LH-beta and FSH-beta (P < 0.05) in the Green group to levels which did not differ from those of the White (control) group. Immunization against vasoactive intestinal peptide reduced plasma concentration and pituitary mRNA expression of prolactin but did not affect expression of gonadal axis genes. Collectively, the results suggest that retinal photostimulation inhibits the reproductive axis through serotonin and not through vasoactive intestinal peptide.

  10. Characterization and Regulation of the Amino Acid Transporter SNAT2 in the Small Intestine of Piglets

    PubMed Central

    Tan, Bie; Wang, Jing; Kong, Xiangfeng; Guan, Guiping; Li, Fengna; Yin, Yulong

    2015-01-01

    The sodium-dependent neutral amino acid transporter 2 (SNAT2), which has dual transport/receptor functions, is well documented in eukaryotes and some mammalian systems, but has not yet been verified in piglets. The objective of this study was to investigate the characteristics and regulation of SNAT2 in the small intestine of piglets. The 1,521-bp porcine full cDNA sequence of SNAT2 (KC769999) from the small intestine of piglets was cloned. The open reading frame of cDNA encodes 506 deduced amino acid residues with a calculated molecular mass of 56.08 kDa and an isoelectric point (pI) of 7.16. Sequence alignment and phylogenetic analysis revealed that SNAT2 is highly evolutionarily conserved in mammals. SNAT2 mRNA can be detected in the duodenum, jejunum and ileum by real-time quantitative PCR. During the suckling period from days 1 to 21, the duodenum had the highest abundance of SNAT2 mRNA among the three segments of the small intestine. There was a significant decrease in the expression of SNAT2 mRNA in the duodenal and jejunal mucosa and in the expression of SNAT2 protein in the jejunal and ileal mucosa on day 1 after weaning (P < 0.05). Studies with enterocytes in vitro showed that amino acid starvation and supplementation with glutamate, arginine or leucine enhanced, while supplementation with glutamine reduced, SNAT2 mRNA expression (P < 0.05). These results regarding the characteristics and regulation of SNAT2 should help to provide some information to further clarify its roles in the absorption of amino acids and signal transduction in the porcine small intestine. PMID:26107628

  11. Effects of dietary supplementation with antimicrobial peptide-P5 on growth performance, apparent total tract digestibility, faecal and intestinal microflora and intestinal morphology of weanling pigs.

    PubMed

    Yoon, Jung Ho; Ingale, Santosh Laxman; Kim, Jin Soo; Kim, Kwang Hyun; Lohakare, Jayant; Park, Yoon Kyung; Park, Jun Cheol; Kwon, Ill Kyong; Chae, Byung Jo

    2013-02-01

    The increase in drug-resistant bacteria and the ban on antibiotic growth promoters worldwide make the search for novel means of preventing bacterial infection and promoting growth performance imperative. In this sense, antimicrobial peptides are thought to be ideal candidates owing to their antimicrobial properties, broad spectrum of activity and low propensity for development of bacterial resistance. The aim of the present study was to investigate the effect of dietary supplementation with antimicrobial peptide-P5 (AMP-P5) on weanling pig nutrition. A total of 240 weanling pigs were allotted to four treatments on the basis of initial body weight. There were four replicates in each treatment, with 15 pigs per replicate. Dietary treatments were negative control (NC, basal diet without antimicrobial), positive control (PC, basal diet + 1.5 g kg(-1) apramycin), basal diet with 40 mg kg(-1) AMP-P5 (P5-40) and basal diet with 60 mg kg(-1) AMP-P5 (P5-60). Pigs fed the PC or P5-60 diet showed improved (P < 0.05) overall growth performance, apparent total tract digestibility of dry matter, crude protein and gross energy and reduced (P < 0.05) faecal and intestinal coliforms compared with pigs fed the NC diet. The results obtained in this study indicate that dietary supplementation with 60 mg kg(-1) AMP-P5 has the potential to improve the growth performance and apparent total tract digestibility of nutrients and reduce coliforms in weanling pigs. Copyright © 2012 Society of Chemical Industry.

  12. Abundant distribution of locustatachykinin-like peptide in the nervous system and intestine of the cockroach Leucophaea maderae.

    PubMed

    Muren, J E; Lundquist, C T; Nässel, D R

    1995-06-29

    An antiserum raised to the locust neuropeptide locustatachykinin I (LomTK I) was used for analysis of the distribution of tachykinin-related peptide in the cockroach Leucophaea maderae. Extracts of dissected brains, suboesophageal ganglia, thoracic ganglia and midguts were separated by high performance liquid chromatography and the fractions analysed in enzyme-linked immunosorbent assay with use of the LomTK antiserum. Each of the tissues was found to contain LomTK-like immunoreactive (LomTK-LI) components with retention times corresponding approximately to synthetic LomTK I and II and callitachykinins I and II. The LomTK antiserum was also used for immunocytochemical mapping of peptide in the nervous system and intestine of L. maderae. A large number of LomTK-LI interneurons were detected in the proto-, deuto- and tritocerebrum of the brain and in the suboesophaegeal ganglion. The immunoreactive neurons supply processes to most parts of the brain: the central body, protocerebral bridge, mushroom body calyces, antennal lobes, optic lobe and most regions of the non-glomerular neuropil. A few protocerebral neurons send LomTK-LI processes to the glandular lobe of the corpora cardiaca. In each of the thoracic ganglia there are six LomTK-LI interneurons and in each of the unfused abdominal ones there are two interneurons. The fused terminal ganglion contains some additional cell bodies in the posterior neuromers. LomTK-LI cell bodies were detected in the frontal ganglion and fibres were seen in this ganglion as well as in the hypocerebral ganglion. The frontal ganglion supplies LomTK-LI processes to the muscle layer of the pharynx. The muscle layer of the midgut is innervated by LomTK-LI fibres from the stomatogastric system (oesophageal nerve and associated ganglia). Additionally the midgut contains numerous LomTK-LI endocrine cells. A number of the pharyngeal dilator muscles were also found to be innervated by LomTK-LI fibres, probably derived from cell bodies in the

  13. An antimicrobial peptide-A3: effects on growth performance, nutrient retention, intestinal and faecal microflora and intestinal morphology of broilers.

    PubMed

    Choi, S C; Ingale, S L; Kim, J S; Park, Y K; Kwon, I K; Chae, B J

    2013-01-01

    1. The present study investigated the effects of dietary supplementation with an antimicrobial peptide-A3 (AMP-A3) on growth performance, nutrient retention, intestinal microflora and intestinal morphology of broilers. 2. A total of 320-d-old chicks (Ross 308, average BW 44.0 ± 3.4 g) were randomly allotted to 4 dietary treatments on the basis of initial body weight (BW). The dietary treatments were negative control (NC; basal diet), positive control (PC; basal diet + 15 mg avilamycin/kg diet) and AMP-A3 (basal diet supplemented with 60 or 90 mg/kg AMP-A3). The NC diet was considered as 0 mg/kg AMP-A3 treatment. Experimental diets were given in two phases: starter phase (d 0-21) and finisher phase (d 22-35). 3. The overall BW gain and retention of dry matter (DM), gross energy (GE; d 19-21) and crude protein (CP; d 19-21 and d 33-35) were greater in birds fed on the PC and 90 mg/kg AMP-A3 diets than in birds fed on the NC diet. Also, an increase in dietary AMP-A3 linearly improved BW gain and retention of DM, GE (d 19-21) and CP (d 19-21 and d 33-35). 4. Birds fed on the PC and 90 mg/kg AMP-A3 diets had fewer excreta coliforms (d 21 and d 35), total anaerobic bacteria (TAB) and Clostridium spp. (d 35) and ileum and caecum coliforms (d 35) than birds fed on the NC diet. In addition, birds fed on the diet supplemented with increasing levels of AMP-A3 had linearly reduced excreta TAB (d 35), Clostridium spp. and coliforms (d 21 and d 35) and ileum and caecum coliforms (d 35). 5. Birds fed on the PC and 90 mg/kg AMP-A3 diets had greater villus height of the duodenum, jejunum and ileum than birds fed on the NC diet. Moreover, birds fed on increasing levels of AMP-A3 diet had increased (linear) villus height of the duodenum, jejunum and ileum. 6. These results indicate that 90 mg/kg AMP-A3 has the potential to improve growth performance, nutrient retention and intestinal morphology and to reduce harmful microorganisms in broilers and can be used as a potential

  14. PepT1 mediates transport of the proinflammatory bacterial tripeptide l-Ala-γ-d-Glu-meso-DAP in intestinal epithelial cells

    PubMed Central

    Nguyen, Hang Thi Thu; Charrier-Hisamuddin, Laetitia; Yan, Yutao; Laroui, Hamed; Demoulin, Benjamin; Sitaraman, Shanthi V.; Merlin, Didier

    2010-01-01

    PepT1 is a di/tripeptide transporter highly expressed in the small intestine, but poorly or not expressed in the colon. However, during chronic inflammation, such as inflammatory bowel disease, PepT1 expression is induced in the colon. Commensal bacteria that colonize the human colon produce a large amount of di/tripeptides. To date, two bacterial peptides (N-formylmethionyl-leucyl-phenylalanine and muramyl dipeptide) have been identified as substrates of PepT1. We hypothesized that the proinflammatory tripeptide l-Ala-γ-d-Glu-meso-DAP (Tri-DAP), a breakdown product of bacterial peptidoglycan, is transported into intestinal epithelial cells via PepT1. We found that uptake of glycine-sarcosine, a specific substrate of PepT1, in intestinal epithelial Caco2-BBE cells was inhibited by Tri-DAP in a dose-dependent manner. Tri-DAP induced activation of NF-κB and MAP kinases, consequently leading to production of the proinflammatory cytokine interleukin-8. Tri-DAP-induced inflammatory response in Caco2-BBE cells was significantly suppressed by silencing of PepT1 expression by using PepT1-shRNAs in a tetracycline-regulated expression (Tet-off) system. Colonic epithelial HT29-Cl.19A cells, which do not express PepT1 under basal condition, were mostly insensitive to Tri-DAP-induced inflammation. However, HT29-Cl.19A cells exhibited proinflammatory response to Tri-DAP upon stable transfection with a plasmid encoding PepT1. Accordingly, Tri-DAP significantly increased keratinocyte-derived chemokine production in colonic tissues from transgenic mice expressing PepT1 in intestinal epithelial cells. Finally, Tri-DAP induced a significant drop in intracellular pH in intestinal epithelial cells expressing PepT1, but not in cells that did not express PepT1. Our data collectively support the classification of Tri-DAP as a novel substrate of PepT1. Given that PepT1 is highly expressed in the colon during inflammation, PepT1-mediated Tri-DAP transport may occur more effectively during

  15. PepT1 mediates transport of the proinflammatory bacterial tripeptide L-Ala-{gamma}-D-Glu-meso-DAP in intestinal epithelial cells.

    PubMed

    Dalmasso, Guillaume; Nguyen, Hang Thi Thu; Charrier-Hisamuddin, Laetitia; Yan, Yutao; Laroui, Hamed; Demoulin, Benjamin; Sitaraman, Shanthi V; Merlin, Didier

    2010-09-01

    PepT1 is a di/tripeptide transporter highly expressed in the small intestine, but poorly or not expressed in the colon. However, during chronic inflammation, such as inflammatory bowel disease, PepT1 expression is induced in the colon. Commensal bacteria that colonize the human colon produce a large amount of di/tripeptides. To date, two bacterial peptides (N-formylmethionyl-leucyl-phenylalanine and muramyl dipeptide) have been identified as substrates of PepT1. We hypothesized that the proinflammatory tripeptide l-Ala-gamma-d-Glu-meso-DAP (Tri-DAP), a breakdown product of bacterial peptidoglycan, is transported into intestinal epithelial cells via PepT1. We found that uptake of glycine-sarcosine, a specific substrate of PepT1, in intestinal epithelial Caco2-BBE cells was inhibited by Tri-DAP in a dose-dependent manner. Tri-DAP induced activation of NF-kappaB and MAP kinases, consequently leading to production of the proinflammatory cytokine interleukin-8. Tri-DAP-induced inflammatory response in Caco2-BBE cells was significantly suppressed by silencing of PepT1 expression by using PepT1-shRNAs in a tetracycline-regulated expression (Tet-off) system. Colonic epithelial HT29-Cl.19A cells, which do not express PepT1 under basal condition, were mostly insensitive to Tri-DAP-induced inflammation. However, HT29-Cl.19A cells exhibited proinflammatory response to Tri-DAP upon stable transfection with a plasmid encoding PepT1. Accordingly, Tri-DAP significantly increased keratinocyte-derived chemokine production in colonic tissues from transgenic mice expressing PepT1 in intestinal epithelial cells. Finally, Tri-DAP induced a significant drop in intracellular pH in intestinal epithelial cells expressing PepT1, but not in cells that did not express PepT1. Our data collectively support the classification of Tri-DAP as a novel substrate of PepT1. Given that PepT1 is highly expressed in the colon during inflammation, PepT1-mediated Tri-DAP transport may occur more effectively

  16. Na+/glucose co-transporter abundance and activity in the small intestine of lambs: enhancement by abomasal infusion of casein.

    PubMed

    Mabjeesh, Sameer J; Guy, Dafna; Sklan, David

    2003-05-01

    The purpose of the present study was to determine the effect of abomasal casein infusion on glucose uptake and abundance of the Na+/glucose co-transporter (SGLT1) 1 in the ovine small intestine. Lambs (body weight 35 (sem 1.0) kg) were surgically fitted with abomasal infusion catheters and were fed diets containing equal portions of wheat hay and cracked maize. Lambs were infused with either 500 g water/d or with 500 g water containing 35 g casein/d. The infusion period lasted 10 d, after which lambs were killed, exsanguinated and eviscerated. Brush border membrane vesicles (BBMV) were prepared using mucosa from different small intestinal regions. Intake and total tract digestibility of nutrients were similar between treatments and averaged 1134, 1142 and 486 g/d and 67, 70, and 94 % for DM, organic matter and non-structural carbohydrates respectively. Crude protein (Nx6.25) digestibility was 15 % greater in the casein-infused than control lambs. Glucose uptake to BBMV ranged from 101 to 337 pmol/mg protein per s along the small intestine and was greatest in the mid-section of the small intestine. In the mid-jejunum, glucose uptake was greater (P<0.07) in lambs infused with casein and averaged 120 pmol/mg protein per s compared with 68 pmol/mg protein per s in the control group. SGLT1 affinity was similar between treatments and averaged 104 microm in the different segments of the small intestine of lambs. However, lambs infused with casein exhibited similar values along the small intestine and affinity averaged 106 microm, while in the control group a greater affinity (85 microm) was measured in the mid-jejunum. SGLT1 protein abundance was correlated with glucose uptake in the BBMV in the casein-treated lambs, but not in the control group. These results suggest that glucose uptake along the small intestine of lambs is influenced by casein or its derivatives in the small intestine via SGLT1 affinity and activity at the brush border membrane, and that SGLT1 activity

  17. Distribution of substance P and vasoactive intestinal peptide in the human liver: light and electron immunoperoxidase methods of observation.

    PubMed

    Ueno, T; Inuzuka, S; Torimura, T; Sakata, R; Sakamoto, M; Gondo, K; Aoki, T; Tanikawa, K; Tsutsumi, V

    1991-11-01

    The localization of substance P (SP) and vasoactive intestinal peptide (VIP) in 12 normal human liver tissues was examined by light and electron immunohistochemistry using immunoperoxidase methods. SP and VIP immunoreactive nerve fibers were observed around portal veins, bile ducts, and hepatic arteries in portal areas, along sinusoids and hepatocytes in hepatic lobules, and around central veins. More SP and VIP immunoreactive nerve fibers were present in the portal areas than in other regions. Moreover, SP and VIP containing nerve endings were localized close to myofibroblasts, Ito cells, fibroblasts and endothelial cells of blood vessels, and sinusoids. The results suggested that part of the innervation of the human liver may be related to the contraction and relaxation of the cells close to nerve endings, and to the regulation of hemodynamic processes by the neurotransmitters such as SP and VIP at the hepatic lobular level.

  18. Phorbol esters alter adenylate cyclase responses to vasoactive intestinal peptide and forskolin in the GH cell line

    SciTech Connect

    Summers, S.; Florio, T.; Cronin, M.

    1986-05-01

    Activation of protein kinase C with phorbol ester modifies cyclic AMP production in several anterior pituitary cell systems. In the GH cell line from a rat pituitary tumor, exposure to phorbol 12-myristate 13-acetate (PMA: 100 nM) for 30 minutes significantly reduces vasoactive intestinal peptide (VIP: 100 nM) stimulated adenylate cyclase (AC) activity in subsequent membrane preparations to 62 + 4% of control (n = 6 independent studies). In contrast, these same membrane preparations respond to forskolin (1 ..mu..M) with significantly more activity, 130 +/- 6% of controls (n = 6 independent studies). Finally, phorbol ester does not block an inhibitory hormone input into the AC system; somatostatin (100 nM) reduction of VIP-stimulated AC activity is not significantly different in membrane preparations from PMA treated and control cells (n = 3 independent studies). These other findings lead the authors to propose that protein kinase C can modify several sites in the AC complex in anterior pituitary cells.

  19. Impact of lipases on the protective effect of SEDDS for incorporated peptide drugs towards intestinal peptidases.

    PubMed

    Leonaviciute, Gintare; Zupančič, Ožbej; Prüfert, Felix; Rohrer, Julia; Bernkop-Schnürch, Andreas

    2016-07-11

    The aim of this study is the development of self-emulsifying drug delivery systems (SEDDS) differing in amounts of ester substructures and to evaluate their stability in presence of pancreatic lipase and protective effect against luminal enzymatic metabolism using leuprorelin as model peptide drug. Hydrophobic leuprolide oleate was incorporated into three different SEDDS formulations and their stability towards pancreatic lipases was investigated utilizing a dynamic in vitro digestion model. Protective effect of SEDDS in respect to peptide drug stability against proteolytic enzymes, trypsin and α-chymotrypsin, was determined via HPLC. Results of in vitro digestion demonstrated that 80% of SEDDS containing the highest amount of ester linkages was degraded within 60min. In comparison to that, SEDDS without ester bonds showed no degradation. With increasing oil droplets hydrolysis the remaining amount of peptide encapsulated into formulation decreased. Furthermore, after 180min incubation with trypsin up to 33.5% and with α-chymotrypsin up to 60.5% of leuprolide oleate was intact while leuprorelin acetate aqueous solution was completely metabolized by trypsin within 120min and by α-chymotrypsin within 5min. Protective effect in environment containing lipases was lower due to oil phase degradation, however, the amount of peptide in ester-free SEDDS was remarkably higher compared to SEDDS susceptible to lipases. The present study revealed that SEDDS stable towards hydrolysis is able to exhibit a protective effect for oral peptide delivery. Copyright © 2016 Elsevier B.V. All rights reserved.

  20. Protective effect of quercetin on pig intestinal integrity after transport stress is associated with regulation oxidative status and inflammation

    PubMed Central

    ZOU, Yi; WEI, Hong Kui; XIANG, Quan-Hang; WANG, Jun; ZHOU, Yuan-Fei; PENG, Jian

    2016-01-01

    This experiment was conducted to evaluate the effects of quercetin supplementation on intestinal integrity, intestinal reactive oxygen species (ROS) levels and intestinal inflammation in pigs under transport stress. A total of 170 finishing pigs were randomly assigned into two groups. Animals in the control group consumed a basal diet, while those in the treatment group consumed the same diet supplemented with 25 mg quercetin per kg feed. After a 4-week period, pigs were transported for 5 hr. The quercetin-supplemented pigs showed decreased serum levels of endotoxin (P<0.05), increased height of jejunum villi (P<0.05), and increased occludin and zonula occudens-1 (ZO-1) mRNA expression in the jejunum (P<0.05). These parameters are associated with intestinal health and were markedly improved by quercetin supplementation. Pigs consuming the quercetin-supplemented diet had lower intestinal levels of ROS and malondialdehyde (MDA) compared with the control group (P<0.05). This finding coincided with greater inhibition of the innate immune system (P<0.05), including mitogen-activated protein kinase (MAPK), protein kinase B (Akt) and nuclear factor κB (NF-κB) signaling pathways, as well as decreased expression of inflammatory cytokines in the jejunum. These results indicate that quercetin alleviates intestinal injury in pigs during transport, probably through modulation of intestinal oxidative status and inflammation. PMID:27301842

  1. Transcriptional regulation of the intestinal luminal Na⁺ and Cl⁻ transporters.

    PubMed

    Malakooti, Jaleh; Saksena, Seema; Gill, Ravinder K; Dudeja, Pradeep K

    2011-04-15

    The epithelial apical membrane Na+/H+ exchangers [NHE (sodium hydrogen exchanger)2 and NHE3] and Cl-/HCO3- exchangers [DRA (down-regulated in adenoma) and PAT-1 (putative anion transporter 1)] are key luminal membrane transporters involved in electroneutral NaCl absorption in the mammalian intestine. During the last decade, there has been a surge of studies focusing on the short-term regulation of these electrolyte transporters, particularly for NHE3 regulation. However, the long-term regulation of the electrolyte transporters, involving transcriptional mechanisms and transcription factors that govern their basal regulation or dysregulation in diseased states, has only now started to unfold with the cloning and characterization of their gene promoters. The present review provides a detailed analysis of the core promoters of NHE2, NHE3, DRA and PAT-1 and outlines the transcription factors involved in their basal regulation as well as in response to both physiological (butyrate, protein kinases and probiotics) and pathophysiological (cytokines and high levels of serotonin) stimuli. The information available on the transcriptional regulation of the recently identified NHE8 isoform is also highlighted. Therefore the present review bridges a gap in our knowledge of the transcriptional mechanisms underlying the alterations in the gene expression of intestinal epithelial luminal membrane Na+ and Cl- transporters involved in electroneutral NaCl absorption. An understanding of the mechanisms of the modulation of gene expression of these transporters is important for a better assessment of the pathophysiology of diarrhoea associated with inflammatory and infectious diseases and may aid in designing better management protocols.

  2. Tests of the adaptive modulation hypothesis for dietary control of intestinal nutrient transport.

    PubMed

    Karasov, W H

    1992-09-01

    According to the adaptive modulation hypothesis, an intestinal transporter should be repressed when its biosynthetic and other costs (of maintenance) exceed the benefits it provides. This leads to two contrasting predictions: transport of a sugar or amino acid worth calories should tend to be increased by its substrate, and transport of a vitamin should be modulated downwards by its substrate and upmodulated in deficiency. In a test of the first prediction, omnivorous desert iguanas eating alfalfa pellets (a high-carbohydrate diet) were compared with desert iguanas eating mealworms (a low-carbohydrate, higher-protein diet). In accord with the prediction, intact intestinal sleeves from the former group had higher rates of carrier-mediated D-glucose uptake/centimeter across the brush border than sleeves from the latter group. But in contrast to the first prediction, mealworm eaters had lower (not higher) proline uptake rates, and the ratio of glucose/proline uptake in the two groups did not differ. I review similar tests in 12 other species and show that overall the hypothesis has been quite robust with regard to the first prediction. Cases in which the hypothesis is rejected may reflect complications associated with changes in other dietary factors or phylogenetic constraints. In a test of the second prediction, uptake of the water-soluble vitamin choline was not increased in choline-deficient chicks, nor was it decreased in adults that have no dietary requirement for choline. I review similar tests for four other vitamins and five essential minerals. Dietary control of transport of the minerals and two of the vitamins seems to be in accord with the hypothesis. But transport rate for three vitamins (choline, pantothenic acid, ascorbic acid) seems not to be increased in deficiency. The best explanation seems to be that vitamin transport is modulated only if it is primarily by a carrier-mediated pathway.

  3. Transport and uptake effects of marine complex lipid liposomes in small intestinal epithelial cell models.

    PubMed

    Du, Lei; Yang, Yu-Hong; Xu, Jie; Wang, Yu-Ming; Xue, Chang-Hu; Kurihara, Hideyuki; Takahashi, Koretaro

    2016-04-01

    Nowadays, marine complex lipids, including starfish phospholipids (SFP) and cerebrosides (SFC) separated from Asterias amurensis as well as sea cucumber phospholipids (SCP) and cerebrosides (SCC) isolated from Cucumaria frondosa, have received much attention because of their potent biological activities. However, little information is known on the transport and uptake of these lipids in liposome forms in small intestinal cells. Therefore, this study was undertaken to investigate the effects of these complex lipid liposomes on transport and uptake in Caco-2 and M cell monolayer models. The results revealed that SFP and SCP contained 42% and 47.9% eicosapentaenoic acid (EPA), respectively. The average particle sizes of liposomes prepared in this study were from 169 to 189 nm. We found that the transport of the liposomes across the M cell monolayer model was much higher than the Caco-2 cell monolayer model. The liposomes consisting of SFP or SCP showed significantly higher transport and uptake than soy phospholipid (soy-PL) liposomes in both Caco-2 and M cell monolayer models. Our results also exhibited that treatment with 1 mM liposomes composed of SFP or SCP for 3 h tended to increase the EPA content in phospholipid fractions of both differentiated Caco-2 and M cells. Moreover, it was also found that the hybrid liposomes consisting of SFP/SFC/cholesterol (Chol) revealed higher transport and uptake across the M cell monolayer in comparison with other liposomes. Furthermore, treatment with SFP/SFC/Chol liposomes could notably decrease the trans-epithelial electrical resistance (TEER) values of Caco-2 and M cell monolayers. The present data also showed that the cell viability of differentiated Caco-2 and M cells was not affected after the treatment with marine complex lipids or soy-PL liposomes. Based on the data in this study, it was suggested that marine complex lipid liposomes exhibit prominent transport and uptake in small intestinal epithelial cell models.

  4. Absorption-enhancing effects of gemini surfactant on the intestinal absorption of poorly absorbed hydrophilic drugs including peptide and protein drugs in rats.

    PubMed

    Alama, Tammam; Kusamori, Kosuke; Katsumi, Hidemasa; Sakane, Toshiyasu; Yamamoto, Akira

    2016-02-29

    In general, the intestinal absorption of small hydrophilic molecules and macromolecules like peptides, after oral administration is very poor. Absorption enhancers are considered to be one of the most promising agents to enhance the intestinal absorption of drugs. In this research, we focused on a gemini surfactant, a new type of absorption enhancer. The intestinal absorption of drugs, with or without sodium dilauramidoglutamide lysine (SLG-30), a gemini surfactant, was examined by an in situ closed-loop method in rats. The intestinal absorption of 5(6)-carboxyfluorescein (CF) and fluorescein isothiocyanate-dextrans (FDs) was significantly enhanced in the presence of SLG-30, such effect being reversible. Furthermore, the calcium levels in the plasma significantly decreased when calcitonin was co-administered with SLG-30, suggestive of the increased intestinal absorption of calcitonin. In addition, no significant increase in the of lactate dehydrogenase (LDH) activity or in protein release from the intestinal epithelium was observed in the presence of SLG-30, suggestive of the safety of this compound. These findings indicate that SLG-30 is an effective absorption-enhancer for improving the intestinal absorption of poorly absorbed drugs, without causing serious damage to the intestinal epithelium.

  5. Intestinal peptides as circulating hormones: release of tachykinin-related peptide from the locust and cockroach midgut.

    PubMed

    Winther, A M; Nässel, D R

    2001-04-01

    Tachykinin-related peptides (TRPs) in the locust Locusta migratoria and the cockroach Leucophaea maderae have stimulatory effects on some muscles that are not innervated by TRP-containing neurons. Thus, these tissues may be affected by circulating TRPs. Here, we have investigated whether the midgut is the source of circulating TRPs. TRP-immunoreactive material in the locust midgut is found only in the endocrine cells of the gut epithelium. In both species of insect, the endocrine cells contain several isoforms of TRPs, as determined by immunocytochemistry and a combination of chromatography (HPLC) and enzyme immunoassay (ELISA). The release of TRPs was investigated by ELISA using isolated midguts of the locust and cockroach. Elevated levels of K(+) in the bathing saline induced the release of TRP from the midgut of both species. To examine the release of TRPs into the circulation in vivo, we measured haemolymph levels of TRPs in fed and starved locusts. The concentration of TRP-immunoreactive material in fed locusts was estimated to be 0.15 nmol l(-1), and this increased approximately fourfold in insects starved for 24 h. In accordance with this observation, the content of TRP-immunoreactive material in the midgut was lower in starved locusts than in fed locusts. Although part of the increased blood concentration of TRPs may be due to reduced blood volume, our data suggest that TRPs are released as hormones from the midgut of the locust and cockroach and that this release may be linked to nutritional status.

  6. A Mouse Model of Acrodermatitis Enteropathica: Loss of Intestine Zinc Transporter ZIP4 (Slc39a4) Disrupts the Stem Cell Niche and Intestine Integrity

    PubMed Central

    Geiser, Jim; Venken, Koen J. T.; De Lisle, Robert C.; Andrews, Glen K.

    2012-01-01

    Mutations in the human Zip4 gene cause acrodermatitis enteropathica, a rare, pseudo-dominant, lethal genetic disorder. We created a tamoxifen-inducible, enterocyte-specific knockout of this gene in mice which mimics this human disorder. We found that the enterocyte Zip4 gene in mice is essential throughout life, and loss-of-function of this gene rapidly leads to wasting and death unless mice are nursed or provided excess dietary zinc. An initial effect of the knockout was the reprogramming of Paneth cells, which contribute to the intestinal stem cell niche in the crypts. Labile zinc in Paneth cells was lost, followed by diminished Sox9 (sex determining region Y-box 9) and lysozyme expression, and accumulation of mucin, which is normally found in goblet cells. This was accompanied by dysplasia of the intestinal crypts and significantly diminished small intestine cell division, and attenuated mTOR1 activity in villus enterocytes, indicative of increased catabolic metabolism, and diminished protein synthesis. This was followed by disorganization of the absorptive epithelium. Elemental analyses of small intestine, liver, and pancreas from Zip4-intestine knockout mice revealed that total zinc was dramatically and rapidly decreased in these organs whereas iron, manganese, and copper slowly accumulated to high levels in the liver as the disease progressed. These studies strongly suggest that wasting and lethality in acrodermatitis enteropathica patients reflects the loss-of-function of the intestine zinc transporter ZIP4, which leads to abnormal Paneth cell gene expression, disruption of the intestinal stem cell niche, and diminished function of the intestinal mucosa. These changes, in turn, cause a switch from anabolic to catabolic metabolism and altered homeostasis of several essential metals, which, if untreated by excess dietary zinc, leads to dramatic weight loss and death. PMID:22737083

  7. Amphipathic polyproline peptides stimulate cholesterol efflux by the ABCA1 transporter.

    PubMed

    Sviridov, D O; Drake, S K; Freeman, L A; Remaley, A T

    2016-03-18

    ApoA-I mimetics are short synthetic peptides that contain an amphipathic α-helix and stimulate cholesterol efflux by the ABCA1 transporter in a detergent-like extraction mechanism. We investigated the use of amphipathic peptides with a polypro helix for stimulating cholesterol efflux by ABCA1. Polypro peptides were synthesized with modified prolines, containing either a hydrophobic phenyl group (Prop) or a polar N-acetylgalactosamine (Prog) attached to the pyrrolidine ring and were designated as either PP-2, 3, 4, or 5, depending on the number of 3 amino acid repeat units (Prop-Prog-Prop). Based on molecular modeling, these peptides were predicted to be relatively rigid and to bind to a phospholipid bilayer. By CD spectroscopy, PP peptides formed a Type-II polypro helix in an aqueous solution. PP-2 was inactive in promoting cholesterol efflux, but peptides with more than 2 repeat units were active. PP-4 showed a similar Vmax as a much longer amphipathic α-helical peptide, containing 37 amino acids, but had a Km that was approximately 20-fold lower. PP peptides were specific in that they did not stimulate cholesterol efflux from cells not expressing ABCA1 and were also non-cytotoxic. Addition of PP-3, 4 and 5 to serum promoted the formation of smaller size HDL species (7 nM) and increased its capacity for ABCA1-dependent cholesterol efflux by approximately 20-35% (p < 0.05). Because of their relatively small size and increased potency, amphipathic peptides with a polypro helix may represent an alternative structural motif for the development of apoA-I mimetic peptides.

  8. Calcium transport from the intestine and into bone in a rat model simulating weightlessness

    NASA Technical Reports Server (NTRS)

    Bikle, D. D.; Globus, R. K.; Morey, E. R.

    1982-01-01

    The objective of this study was to determine whether a defect in transport of calcium in the duodenum was related to decreased bone formation in the suspended rat. Rats were suspended by the tail at a 40 deg angle for up to 15 days. Ca-45 was injected into the ligated duodenum in situ 15 minutes prior to sacrific. Blood, tibia, vertebra and humerus were obtained for total calcium and Ca-45 analyses. Intestinal calcium transport did not appear to be significantly altered by suspension. However, by 5 days of suspension a significant decrease in accumulation of Ca-45 into tibia and vertebra was observed. A trend of decreasing bone mineral and mass was established in tibia and vertebra by the fifth day of suspension. The humerus failed to demonstrate a significant weight decrease or change in Ca-45 accumulation after 15 days of suspension. Results from this simulated weightlessness model suggest that transport of calcium from intestine into bone is decreased within 5 days of suspension. This deficiency appears to be associated with a progressive decrease in total mass of non-weightbearing bones.

  9. Transport and function of syntaxin 3 in human epithelial intestinal cells.

    PubMed

    Breuza, L; Fransen, J; Le Bivic, A

    2000-10-01

    To follow the transport of human syntaxin (Syn) 3 to the apical surface of intestinal cells, we produced and expressed in Caco-2 cells a chimera made of the entire Syn3 coding sequence and the extracellular domain of the human transferrin receptor (TfR). This chimera (Syn3TfR) was localized to the apical membrane and was transported along the direct apical pathway, suggesting that this is also the case for endogenous Syn3. To test the potential role of Syn3 in apical transport, we overexpressed it in Caco-2 cells and measured the efficiency of apical and basolateral delivery of several endogenous markers. We observed a strong inhibition of apical delivery of sucrase-isomaltase (SI), an apical transmembrane protein, and of alpha-glucosidase, an apically secreted protein. No effect was observed on the basolateral delivery of Ag525, a basolateral antigen, strongly suggesting that Syn3 is necessary for efficient delivery of proteins to the apical surface of intestinal cells.

  10. Active Transport of Phosphorylated Carbohydrates Promotes Intestinal Colonization and Transmission of a Bacterial Pathogen

    PubMed Central

    Sit, Brandon; Crowley, Shauna M.; Bhullar, Kirandeep; Lai, Christine Chieh-Lin; Tang, Calvin; Hooda, Yogesh; Calmettes, Charles; Khambati, Husain; Ma, Caixia; Brumell, John H.; Schryvers, Anthony B.; Vallance, Bruce A.; Moraes, Trevor F.

    2015-01-01

    Efficient acquisition of extracellular nutrients is essential for bacterial pathogenesis, however the identities and mechanisms for transport of many of these substrates remain unclear. Here, we investigate the predicted iron-binding transporter AfuABC and its role in bacterial pathogenesis in vivo. By crystallographic, biophysical and in vivo approaches, we show that AfuABC is in fact a cyclic hexose/heptose-phosphate transporter with high selectivity and specificity for a set of ubiquitous metabolites (glucose-6-phosphate, fructose-6-phosphate and sedoheptulose-7-phosphate). AfuABC is conserved across a wide range of bacterial genera, including the enteric pathogens EHEC O157:H7 and its murine-specific relative Citrobacter rodentium, where it lies adjacent to genes implicated in sugar sensing and acquisition. C. rodentium ΔafuA was significantly impaired in an in vivo murine competitive assay as well as its ability to transmit infection from an afflicted to a naïve murine host. Sugar-phosphates were present in normal and infected intestinal mucus and stool samples, indicating that these metabolites are available within the intestinal lumen for enteric bacteria to import during infection. Our study shows that AfuABC-dependent uptake of sugar-phosphates plays a critical role during enteric bacterial infection and uncovers previously unrecognized roles for these metabolites as important contributors to successful pathogenesis. PMID:26295949

  11. Glycine transport by intestinal brush border vesicles of the amphibian Discoglossus pictus.

    PubMed

    Saidane, D; Boge, G; Tritar, B; Peres, G

    1991-01-01

    1. In order to determine the different components of glycine uptake by the intestine of the frog, Discoglossus pictus, we have used brush border membrane vesicles isolated by a classical precipitation technique. 2. Enzymatic tests showed that a good purification was obtained. The concentration ratio of alkaline phosphatase was 14.8. 3. Glycine entry in vesicles as a function of time, in presence or absence of sodium, indicated an overshoot which decreased when incubation time was prolonged. The overshoot was dependent on the presence of sodium. 4. The nature of the anion associated to sodium had little effect on glycine uptake. Nevertheless, chloride and thiocyanate appeared more efficient than glutarate. 5. The effect of transmembrane potential was studied by using valinomycin associated with a potassium gradient. The addition of this substance stimulated glycine transport by 43%. 6. The transport at different glycine concentrations showed two components: one non-saturable with weak affinity and the other saturable with strong affinity (Kt = 0.338 mM). 7. In conclusion, glycine transport by the brush border of D. pictus intestine presents a saturable component depending on sodium and on transmembrane electrical potential.

  12. Phenolics from Whole Grain Oat Products as Modifiers of Starch Digestion and Intestinal Glucose Transport.

    PubMed

    Li, Min; Koecher, Katie; Hansen, Laura; Ferruzzi, Mario G

    2017-08-16

    Four oat varieties and three product forms (porridge, cereal, and snack bar) were assessed to determine the impact of oat phenolics on starch digestibility and intestinal glucose transport. α-Amylase activity was enhanced by 20 GAE μM (gallic acid equivalent) of phenolics extracted from oat (96.7-118%, p < 0.05), while it was modestly inhibited at 500 GAE μM (83.0-95.4%). Maltose hydrolysis was reduced (49.6-82.4%, p < 0.05), albeit with high IC50 values (500-940 GAE μM). Free and bound oat phenolic extracts dose-dependently attenuated transport of d-glucose-1,2,3,4,5,6,6-d7 by Caco-2 monolayers over 60 min. Oat foods were then subjected to a coupled in vitro digestion/Caco-2 intestinal cell model to determine relevance to whole food systems. Digestive release of glucose was similar among products; however, glucose transport was significantly reduced from digesta of GMI 423 porridge and puffed cereal by 34% ± 12% and 20% ± 10% (p < 0.05) at 60 min. Results suggest phenolics might be a factor modulating glycemic response of oat products.

  13. Impact of a high-cholesterol diet on expression levels of Niemann-Pick C1-like 1 and intestinal transporters in rats and mice.

    PubMed

    Kawase, Atsushi; Araki, Yasuha; Ueda, Yukiko; Nakazaki, Sayaka; Iwaki, Masahiro

    2016-08-01

    Niemann-Pick C1-like 1 (NPC1L1), ATP-binding cassette (ABC)G5, and ABCG8 are all involved in intestinal cholesterol absorption. It is unclear whether a high-cholesterol (HC) diet affects the expression of these transporters in rats and mice as well as humans. We examined the effects of an HC diet on their expression in small intestine and the differences between rats and mice in the responsive of this expression to an HC diet. In addition to these transporters, alterations in six representative drug and nutrient transporters (multidrug resistance-associated protein, breast cancer resistance protein, peptide transporter, sodium-glucose linked transporter, glucose transporter, and L-type amino acid transporter) and transcriptional factors such as hepatocyte nuclear factor (HNF)4α, sterol regulatory element-binding protein (SREBP)2, and liver X receptor (LXR)α were determined. In rats and mice fed an HC diet for 7 days, the mRNA and protein levels of NPC1L1 in the small intestine were determined by real-time reverse transcription polymerase chain reaction and western blotting, respectively. The mRNA levels of ABCG5 and ABCG8, six representative transporters, and transcriptional factors such as HNF4α, SREBP2, and LXR were examined. Significant decreases in the expression levels of NPC1L1 were observed in mice, but not rats, fed the HC diet. The mRNA levels of ABCG5 and ABCG8 were significantly increased in HC rats but not in mice. Only minor changes in the mRNA levels of the other transporters were seen in HC rats and mice. Decreased mRNA levels of HNF4α and SREBP2 in mice could be involved in the reduction in NPC1L1 expression observed upon the introduction of an HC diet. These results indicate that the effects of an HC diet on the expression levels of NPC1L1, ABCG5, and ABCG8 differ between mice and rats.

  14. Breakdown of gliadin peptides by intestinal brush borders from coeliac patients.

    PubMed Central

    Bruce, G; Woodley, J F; Swan, C H

    1984-01-01

    The 'missing peptidase' hypothesis to explain the aetiology of coeliac disease has never been satisfactorily resolved and recent reports suggest that coeliac brush borders may have depressed levels of specific peptidase enzymes. It has been inferred from these studies that the subsequent brush border digestion of gliadin peptides may therefore be defective. In this present study a sensitive fluorometric assay was used to measure the hydrolysis of a peptic-tryptic digest of gliadin by both normal and coeliac brush borders. The coeliac brush borders were as efficient as the normals in hydrolysing gliadin peptides and showed no depression of any specific peptidase activity. PMID:6381246

  15. Cytotoxicity, Intestinal Transport, and Bioavailability of Dispersible Iron and Zinc Supplements

    PubMed Central

    Kim, Hyeon-Jin; Bae, Song-Hwa; Kim, Hyoung-Jun; Kim, Kyoung-Min; Song, Jae Ho; Go, Mi-Ran; Yu, Jin; Oh, Jae-Min; Choi, Soo-Jin

    2017-01-01

    Iron or zinc deficiency is one of the most important nutritional disorders which causes health problem. However, food fortification with minerals often induces unacceptable organoleptic changes during preparation process and storage, has low bioavailability and solubility, and is expensive. Nanotechnology surface modification to obtain novel characteristics can be a useful tool to overcome these problems. In this study, the efficacy and potential toxicity of dispersible Fe or Zn supplement coated in dextrin and glycerides (SunActive FeTM and SunActive ZnTM) were evaluated in terms of cytotoxicity, intestinal transport, and bioavailability, as compared with each counterpart without coating, ferric pyrophosphate (FePP) and zinc oxide (ZnO) nanoparticles (NPs), respectively. The results demonstrate that the cytotoxicity of FePP was not significantly affected by surface modification (SunActive FeTM), while SunActive ZnTM was more cytotoxic than ZnO-NPs. Cellular uptake and intestinal transport efficiency of SunActive FeTM were significantly higher than those of its counterpart material, which was in good agreement with enhanced oral absorption efficacy after a single-dose oral administration to rats. These results seem to be related to dissolution, particle dispersibility, and coating stability of materials depending on suspending media. Both SunActiveTM products and their counterpart materials were determined to be primarily transported by microfold (M) cells through the intestinal epithelium. It was, therefore, concluded that surface modification of food fortification will be a useful strategy to enhance oral absorption efficiency at safe levels. PMID:28503169

  16. F-18 Labeled Vasoactive Intestinal Peptide Analogue in the PET Imaging of Colon Carcinoma in Nude Mice

    PubMed Central

    Liu, Yuxia; Shen, Hua; Pang, Lifang; Yin, Duanzhi; Wang, Yongxian; Li, Shanqun; Shi, Hongcheng

    2013-01-01

    As large amount of vasoactive intestinal peptide (VIP) receptors are expressed in various tumors and VIP-related diseases, radiolabeled VIP provides a potential PET imaging agent for VIP receptor. However, structural modification of VIP is required before being radiolabeled and used for VIP receptor imaging due to its poor in vivo stability. As a VIP analogue, [R8, 15, 21, L17]-VIP exhibited improved stability and receptor specificity in preliminary studies. In this study, F-18 labeled [R8,15,21, L17]-VIP was produced with the radiochemical yield being as high as 33.6% ± 3% (decay-for-corrected, n = 5) achieved within 100 min, a specific activity of 255 GBq/μmol, and a radiochemical purity as high as 99% as characterized by radioactive HPLC, TLC, and SDS-Page radioautography. A biodistribution study in normal mice also demonstrated fast elimination of F-18 labeled [R8,15,21, L17]-VIP in the blood, liver, and gastrointestinal tracts. A further micro-PET imaging study in C26 colon carcinoma bearing mice confirmed the high tumor specificity, with the tumor/muscle radioactivity uptake ratio being as high as 3.03 at 60 min following injection, and no apparent radioactivity concentration in the intestinal tracts. In addition, blocking experiment and Western Blot test further confirmed its potential in PET imaging of VIP receptor-positive tumor. PMID:24459669

  17. Amino acids induce peptide uptake via accelerated degradation of CUP9, the transcriptional repressor of the PTR2 peptide transporter.

    PubMed

    Xia, Zanxian; Turner, Glenn C; Hwang, Cheol-Sang; Byrd, Christopher; Varshavsky, Alexander

    2008-10-24

    Multiple pathways link expression of PTR2, the transporter of di- and tripeptides in the yeast Saccharomyces cerevisiae, to the availability and quality of nitrogen sources. Previous work has shown that induction of PTR2 by extracellular amino acids requires, in particular, SSY1 and PTR3. SSY1 is structurally similar to amino acid transporters but functions as a sensor of amino acids. PTR3 acts downstream of SSY1. Expression of the PTR2 peptide transporter is induced not only by amino acids but also by dipeptides with destabilizing N-terminal residues. These dipeptides bind to UBR1, the ubiquitin ligase of the N-end rule pathway, and allosterically accelerate the UBR1-dependent degradation of CUP9, a transcriptional repressor of PTR2. UBR1 targets CUP9 through its internal degron. Here we demonstrate that the repression of PTR2 by CUP9 requires TUP1 and SSN6, the corepressor proteins that form a complex with CUP9. We also show that the induction of PTR2 by amino acids is mediated by the UBR1-dependent acceleration of CUP9 degradation that requires both SSY1 and PTR3. The acceleration of CUP9 degradation is shown to be attained without increasing the activity of the N-end rule pathway toward substrates with destabilizing N-terminal residues. We also found that GAP1, a general amino acid transporter, strongly contributes to the induction of PTR2 by Trp. Although several aspects of this complex circuit remain to be understood, our findings establish new functional links between the amino acids-sensing SPS system, the CUP9-TUP1-SSN6 repressor complex, the PTR2 peptide transporter, and the UBR1-dependent N-end rule pathway.

  18. Differences between lumen targeting domains of chloroplast transit peptides determine pathway specificity for thylakoid transport.

    PubMed

    Henry, R; Kapazoglou, A; McCaffery, M; Cline, K

    1994-04-08

    Nuclear encoded thylakoid lumen proteins are imported into the chloroplast storma and further directed across thylakoid membranes by lumen targeting domains. Recently, we showed that there are two protein-specific pathways for transport into the lumen. This was unexpected in that lumen targeting domains have similar properties, all containing bacterial signal peptide motifs. Nevertheless, sequence homology analysis suggests that pathway specificity is determined by elements in the lumen targeting domain. To test this, we constructed and analyzed chimeric proteins in which transit peptides from proteins transported by one pathway were fused to the mature domains of proteins directed by the other. We also investigated the transport characteristics of a previously unexamined protein whose pathway was predicted by sequence similarity analysis. Our results confirm that lumen targeting domains contain pathway sorting elements and further indicate that distinct energy and stroma requirements for transport are pathway characteristics, unrelated to the passenger protein. These findings suggest the operation of two mechanistically different translocators.

  19. Intestinal Sodium Glucose Cotransporter 1 Inhibition Enhances Glucagon-Like Peptide-1 Secretion in Normal and Diabetic Rodents.

    PubMed

    Oguma, Takahiro; Nakayama, Keiko; Kuriyama, Chiaki; Matsushita, Yasuaki; Yoshida, Kumiko; Hikida, Kumiko; Obokata, Naoyuki; Tsuda-Tsukimoto, Minoru; Saito, Akira; Arakawa, Kenji; Ueta, Kiichiro; Shiotani, Masaharu

    2015-09-01

    The sodium glucose cotransporter (SGLT) 1 plays a major role in glucose absorption and incretin hormone release in the gastrointestinal tract; however, the impact of SGLT1 inhibition on plasma glucagon-like peptide-1 (GLP-1) levels in vivo is controversial. We analyzed the effects of SGLT1 inhibitors on GLP-1 secretion in normoglycemic and hyperglycemic rodents using phloridzin, CGMI [3-(4-cyclopropylphenylmethyl)-1-(β-d-glucopyranosyl)-4-methylindole], and canagliflozin. These compounds are SGLT2 inhibitors with moderate SGLT1 inhibitory activity, and their IC50 values against rat SGLT1 and mouse SGLT1 were 609 and 760 nM for phloridzin, 39.4 and 41.5 nM for CGMI, and 555 and 613 nM for canagliflozin, respectively. Oral administration of these inhibitors markedly enhanced and prolonged the glucose-induced plasma active GLP-1 (aGLP-1) increase in combination treatment with sitagliptin, a dipeptidyl peptidase-4 (DPP4) inhibitor, in normoglycemic mice and rats. CGMI, the most potent SGLT1 inhibitor among them, enhanced glucose-induced, but not fat-induced, plasma aGLP-1 increase at a lower dose compared with canagliflozin. Both CGMI and canagliflozin delayed intestinal glucose absorption after oral administration in normoglycemic rats. The combined treatment of canagliflozin and a DPP4 inhibitor increased plasma aGLP-1 levels and improved glucose tolerance compared with single treatment in both 8- and 13-week-old Zucker diabetic fatty rats. These results suggest that transient inhibition of intestinal SGLT1 promotes GLP-1 secretion by delaying glucose absorption and that concomitant inhibition of intestinal SGLT1 and DPP4 is a novel therapeutic option for glycemic control in type 2 diabetes mellitus. Copyright © 2015 by The American Society for Pharmacology and Experimental Therapeutics.

  20. [Important application of intestinal transporters and metabolism enzymes on gastrointestinal disposal of active ingredients of Chinese materia medica].

    PubMed

    Bi, Xiaolin; Du, Qiu; Di, Liuqing

    2010-02-01

    Oral drug bioavailability depends on gastrointestinal absorption, intestinal transporters and metabolism enzymes are the important factors in drug gastrointestinal absorption and they can also be induced or inhibited by the active ingredients of Chinese materia medica. This article presents important application of intestinal transporters and metabolism enzymes on gastrointestinal disposal of the active ingredients of Chinese materia medica, and points out the importance of research on transport and metabolism of the active ingredients of Chinese materia medica in Chinese extract and Chinese medicinal formulae.

  1. Representing intestinal drug transport in silico: an agent-oriented approach.

    PubMed

    Liu, Yu; Hunt, C Anthony

    2004-01-01

    A prototype Epithelio-Mimetic Device (EMD) was developed and tested. EMD components are designed to map logically to biological components at multiple levels of resolution. Those components are engineered to represent actual components within an in vitro cellular system used to study intestinal drug transport. Our goal is that the behaviors of the EMD closely match observed behaviors of the in vitro systems for a wide variety of drugs. Early stage system verification is achieved. The general patterns of experimental results from the EMD for a set of hypothetical drugs having a variety of physicochemical properties reasonably match observed patterns for a wide range of experimental conditions.

  2. Characteristics of (+)-catechin and (-)-epicatechin transport across pig intestinal brush border membranes.

    PubMed

    Starp, Christiane; Alteheld, Birgit; Stehle, Peter

    2006-01-01

    (+)-Catechin and (-)-epicatechin are considered as disease preventive flavan-3-ols of foods like fruits, beverages and chocolate. We investigated mechanisms and kinetics of (+)-catechin and (-)-epicatechin uptake employing a validated in vitro model with isolated pig brush border membrane vesicles. Vesicles were isolated from pig small intestine employing the divalent cation method. Characterization (marker enzymes, electron microscopy) confirmed their purity and function. Transport studies with (+)-catechin and (-)-epicatechin under predefined conditions [presence/absence of sodium, pH gradient, temperature (8-37 degrees C), various initial substrate concentrations (2-20 mmol/l)] revealed a measurable transport (HPLC analyses) across the brush border membrane for both substrates. Catechin transport was stimulated by an outwardly directed H(+) gradient (pH(i) 5.5/pH(o) 7.5). The presence of an inwardly directed Na(+) gradient did not result in a transient overshoot in (+)-catechin and (-)-epicatechin uptake. At 37 degrees C, subtraction of diffusion from the total transport rate showed saturation kinetics. Our in vitro study indicate that both (+)-catechin and (-)-epicatechin are transported across the basolateral membrane using a dual transport system consisting of free diffusion (dominant at low concentrations) and carrier-mediated facilitated diffusion.

  3. Transepithelial transports of rare sugar D-psicose in human intestine.

    PubMed

    Hishiike, Takashi; Ogawa, Masahiro; Hayakawa, Shigeru; Nakajima, Daichi; O'Charoen, Siwaporn; Ooshima, Hisaka; Sun, Yuanxia

    2013-07-31

    D-Psicose (Psi), the C3-epimer of D-fructose (Fru), is a noncalorie sugar with a lower glycemic response. The trans-cellular pathway of Psi in human enterocytes was investigated using a Caco-2 cell monolayer. The permeation rate of Psi across the monolayer was not affected by the addition of phlorizin, an inhibitor of sugar transporter SGLT1, whereas it was accelerated by treatment with forskolin, a GLUT5-gene inducer, clearly showing that GLUT5 is involved in the transport of Psi. The permeability of Psi was suppressed in the presence of D-glucose (Glc) and Fru, suggesting that the three monosaccharides are transported via the same transporter. Since GLUT2, the predominant sugar transporter on the basolateral membrane of enterocytes, mediates the transport of Glc and Fru, Psi might be mediated by GLUT2. The present study shows that Psi is incorporated from the intestinal lumen into enterocytes via GLUT5 and is released to the lamina propria via GLUT2.

  4. EAAT3 promotes amino acid transport and proliferation of porcine intestinal epithelial cells.

    PubMed

    Ye, Jin-Ling; Gao, Chun-Qi; Li, Xiang-Guang; Jin, Cheng-Long; Wang, Dan; Shu, Gang; Wang, Wen-Ce; Kong, Xiang-Feng; Yao, Kang; Yan, Hui-Chao; Wang, Xiu-Qi

    2016-06-21

    Excitatory amino acid transporter 3 (EAAT3, encoded by SLC1A1) is an epithelial type high-affinity anionic amino acid transporter, and glutamate is the major oxidative fuel for intestinal epithelial cells. This study investigated the effects of EAAT3 on amino acid transport and cell proliferation through activation of the mammalian target of the rapamycin (mTOR) pathway in porcine jejunal epithelial cells (IPEC-J2). Anionic amino acid and cystine (Cys) transport were increased (P<0.05) by EAAT3 overexpression and decreased (P<0.05) by EAAT3 knockdown rather than other amino acids. MTT and cell counting assays suggested that IPEC-J2 cell proliferation increased (P<0.05) with EAAT3 overexpression. Phosphorylation of mTOR (Ser2448), ribosomal protein S6 kinase-1 (S6K1, Thr389) and eukaryotic initiation factor 4E-binding protein-1 (4EBP1, Thr70) was increased by EAAT3 overexpression and decreased by EAAT3 knockdown (P<0.05), as were levels of activating transcription factor 4 (ATF4) and cystine/glutamate antiporter (xCT) (P<0.05). Our results demonstrate for the first time that EAAT3 facilitates anionic amino acid transport and activates the mTOR pathway, promoting Cys transport and IPEC-J2 cell proliferation.

  5. EAAT3 promotes amino acid transport and proliferation of porcine intestinal epithelial cells

    PubMed Central

    Jin, Cheng-long; Wang, Dan; Shu, Gang; Wang, Wen-ce; Kong, Xiang-feng; Yao, Kang; Yan, Hui-chao; Wang, Xiu-qi

    2016-01-01

    Excitatory amino acid transporter 3 (EAAT3, encoded by SLC1A1) is an epithelial type high-affinity anionic amino acid transporter, and glutamate is the major oxidative fuel for intestinal epithelial cells. This study investigated the effects of EAAT3 on amino acid transport and cell proliferation through activation of the mammalian target of the rapamycin (mTOR) pathway in porcine jejunal epithelial cells (IPEC-J2). Anionic amino acid and cystine (Cys) transport were increased (P<0.05) by EAAT3 overexpression and decreased (P<0.05) by EAAT3 knockdown rather than other amino acids. MTT and cell counting assays suggested that IPEC-J2 cell proliferation increased (P<0.05) with EAAT3 overexpression. Phosphorylation of mTOR (Ser2448), ribosomal protein S6 kinase-1 (S6K1, Thr389) and eukaryotic initiation factor 4E-binding protein-1 (4EBP1, Thr70) was increased by EAAT3 overexpression and decreased by EAAT3 knockdown (P<0.05), as were levels of activating transcription factor 4 (ATF4) and cystine/glutamate antiporter (xCT) (P<0.05). Our results demonstrate for the first time that EAAT3 facilitates anionic amino acid transport and activates the mTOR pathway, promoting Cys transport and IPEC-J2 cell proliferation. PMID:27231847

  6. Transport mechanism of doxorubicin loaded chitosan based nanogels across intestinal epithelium.

    PubMed

    Feng, Chao; Sun, Guohui; Wang, Zhiguo; Cheng, Xiaojie; Park, Hyunjin; Cha, Dongsu; Kong, Ming; Chen, Xiguang

    2014-05-01

    Chitosan/carboxymethyl chitosan nanogels (CS/CMCS-NGs) could enhance the oral bioavailability of doxorubicin hydrochloride (DOX). To identify the mechanisms that support this recent observation, different transport pathways of CS/CMCS-NGs through the small intestine were studied in this work. Transcellular mechanisms were investigated in the presence of different inhibitors of protein-mediated endocytosis. A reduction of 52.32±18% of drug transport was found when clathrin-mediated endocytosis was inhibited, which demonstrated that clathrin-mediated endocytosis played an important role in the transcellular transport of DOX:CS/CMCS-NGs. The paracellular transport results showed that CMCS in NGs could produce a transient and reversible enhancement of paracellular permeability by depriving Ca(2+) from adherens junctions, whose efficacy as an absorption enhancer was about 1.7-3.3 folds higher than CS in NGs in GI tract. Finally, in vivo experiment showed that the transport capacity of DOX:CS/CMCS-NGs was significantly inhibited by extra added Ca(2+), which confirmed that the higher capacity to binding Ca(2+) of CS/CMCS-NGs was beneficial for transport of DOX. Copyright © 2013 Elsevier B.V. All rights reserved.

  7. Utilization of peptide carrier system to improve intestinal absorption: targeting prolidase as a prodrug-converting enzyme

    NASA Technical Reports Server (NTRS)

    Bai, J. P.; Hu, M.; Subramanian, P.; Mosberg, H. I.; Amidon, G. L.

    1992-01-01

    The feasibility of targeting prolidase as a peptide prodrug-converting enzyme has been examined. The enzymatic hydrolysis by prolidase of substrates for the peptide transporter L-alpha-methyldopa-pro and several dipeptide analogues without an N-terminal alpha-amino group (phenylpropionylproline, phenylacetylproline, N-benzoylproline, and N-acetylproline) was investigated. The Michaelis-Menten parameters Km and Vmax for L-alpha-methyldopa-pro are 0.09 +/- 0.02 mM and 3.98 +/- 0.25 mumol/min/mg protein, respectively. However, no hydrolysis of the dipeptide analogues without an N-terminal alpha-amino group is observed, suggesting that an N-terminal alpha-amino group is required for prolidase activity. These results demonstrate that prolidase may serve as a prodrug-converting enzyme for the dipeptide-type prodrugs, utilizing the peptide carrier for transport of prodrugs into the mucosal cells and prolidase, a cytosolic enzyme, to release the drug. However, a free alpha-amino group appears to be necessary for prolidase hydrolysis.

  8. Transintestinal transport mechanisms of 5-aminosalicylic acid (in situ rat intestine perfusion, Caco-2 cells) and Biopharmaceutics Classification System.

    PubMed

    Smetanová, Libuše; Stětinová, Věra; Kholová, Dagmar; Kuneš, Martin; Nobilis, Milan; Svoboda, Zbyněk; Květina, Jaroslav

    2013-09-01

    The aim of the study was 1) to estimate permeability of 5-aminosalicylic acid (5-ASA), 2) to categorize 5-ASA according to BCS (Biopharmaceutics Classification System), and 3) to contribute to determination of 5-ASA transintestinal transport and biotransformation mechanisms. The in situ rat intestine perfusion was used as an initial method to study 5-ASA transport. The amount of 5-ASA (released from tablet) transferred into portal circulation reached 5.79 ± 0.24%. During this transport, the intestinal formation of 5-ASA main metabolite (N-ac-5-ASA) occurred. N-ac-5-ASA was found in perfusate both from intestinal lumen and from v. portae. In in vitro Caco-2 monolayers, transport of 5-ASA (10-1000 µmol/l) was studied in apical-basolateral and basolateral-apical direction (iso-pH 7.4 conditions). The transport of total 5-ASA (parent drug plus intracellularly formed N-ac-5-ASA) was linear with time, concentration- and direction-dependent. Higher basolateral-apical (secretory) transport was mainly caused by higher transport of the metabolite (suggesting metabolite efflux transport). Transport of 5-ASA (only parent drug) was saturable (transepithelial carrier-mediated) at low doses, dominated by passive, paracellular process in higher doses which was confirmed by increased 5-ASA transport using Ca2+-free transport medium. The estimated low 5-ASA permeability and its low solubility enable to classify 5-ASA as BCS class IV.

  9. Amino acid and peptide absorption after proximal small intestinal resection in the rat.

    PubMed Central

    Garrido, A B; Freeman, H J; Chung, Y C; Kim, Y S

    1979-01-01

    In experimental animals with massive proximal intestinal resection, in vivo ileal absorption of an amino acid mixture containing L-leucine and glycine as well as two different dipeptides, L-leucyl-glycine and glycyl-L-leucine, were compared. Both amino acid and dipeptide absorption were markedly enhanced in the ileal segments. However, the absorption rates from the two perfused dipeptides differed. L-leucine absorption from L-leucyl-glycine was much greater than from glycyl-L-leucine. Brush border amino-peptidase activities after resection were also increased but dissociation between absorption and hydrolytic activity occurred. This study indicates that certain dipeptides are handled differently by adapting ileal segments. Furthermore, the changes observed probably reflect mucosal cellular hyperplasia occurring in association with intestinal adaptation. PMID:428822

  10. Influence of renovascular hypertension on the distribution of vasoactive intestinal peptide in the stomach and heart of rats.

    PubMed

    Kasacka, Irena; Piotrowska, Żaneta; Janiuk, Izabela

    2015-11-01

    Arterial hypertension is associated with serious dysfunction of the cardiovascular system and digestive system. Given the relevant role of vasoactive intestinal peptide (VIP) in the regulation of digestion process, control of blood pressure and heart rate as well as cardio- and gastro-protective character of the peptide, it appeared worthwhile to undertake the research aimed at immunohistochemical identification and evaluation of VIP-positive structures in the pylorus and heart of hypertensive rats. Up to now, this issue has not been investigated. The experimental model of hypertension in rats according to Goldblatt (two-kidney one clip model of hypertension) was used in the study. The experimental material (pylorus and heart) was collected in the sixth week of the study. VIP-containing structures were evaluated using immunohistochemical and morphometric methods. The analysis of the results showed a significant increase in the number of immunoreactive VIP structures and in the intensity of immunohistochemical staining in the stomach and in the heart of hypertensive rats. Our findings indicate that VIP is an important regulator of cardiovascular and digestive system in physiological and pathological conditions. However, to better understand the exact role of VIP in hypertension further studies need to be carried out.

  11. Collagen peptides ameliorate intestinal epithelial barrier dysfunction in immunostimulatory Caco-2 cell monolayers via enhancing tight junctions.

    PubMed

    Chen, Qianru; Chen, Oliver; Martins, Isabela M; Hou, Hu; Zhao, Xue; Blumberg, Jeffrey B; Li, Bafang

    2017-03-22

    Dysfunction of the intestinal barrier plays a key role in the pathogenesis of inflammatory bowel disease (IBD) and multiple organ failure. The effect of Alaska pollock skin-derived collagen and its 3 tryptic hydrolytic fractions, HCP (6 kDa retentate), MCP (3 kDa retentate) and LCP (3 kDa permeate) on TNF-α induced barrier dysfunction was investigated in Caco-2 cell monolayers. TNF-α induced barrier dysfunction was significantly attenuated by the collagen and its peptide fractions, especially LCP, compared to TNF-α treated controls (P < 0.05). Compared to a negative control, 24 h pre-incubation with 2 mg mL(-1) LCP significantly alleviated the TNF-α induced breakdown of the tight junction protein ZO-1 and occludin and inhibited MLC phosphorylation and MLCK expression. The activation of NFκB and Elk-1 was suppressed by LCP. Thus, collagen peptides may attenuate TNF-α induced barrier dysfunction of Caco-2 cells by inhibiting the NFκB and ERK1/2-mediated MLCK pathway with associated decreases in ZO-1 and occludin protein expression.

  12. Vasoactive intestinal peptide binding sites and fibers in the brain of the pigeon Columba livia: An autoradiographic and immunohistochemical study

    SciTech Connect

    Hof, P.R.; Dietl, M.M.; Charnay, Y.; Martin, J.L.; Bouras, C.; Palacios, J.M.; Magistretti, P.J. )

    1991-03-15

    The distribution of vasoactive intestinal peptide (VIP) binding sites in the pigeon brain was examined by in vitro autoradiography on slide-mounted sections. A fully characterized monoiodinated form of VIP, which maintains the biological activity of the native peptide, was used throughout this study. The highest densities of binding sites were observed in the hyperstriatum dorsale, archistriatum, auditory field L of neostriatum, area corticoidea dorsolateralis and temporo-parieto-occipitalis, area parahippocampalis, tectum opticum, nucleus dorsomedialis anterior thalami, and in the periventricular area of the hypothalamus. Lower densities of specific binding occurred in the neostriatum, hyperstriatum ventrale and nucleus septi lateralis, dorsolateral area of the thalamus, and lateral and posteromedial hypothalamus. Very low to background levels of VIP binding were detected in the ectostriatum, paleostriatum primitivum, paleostriatum augmentatum, lobus parolfactorius, nucleus accumbens, most of the brainstem, and the cerebellum. The distribution of VIP-containing fibers and terminals was examined by indirect immunofluorescence using a polyclonal antibody against porcine VIP. Fibers and terminals were observed in the area corticoidea dorsolateralis, area parahippocampalis, hippocampus, hyperstriatum accessorium, hyperstriatum dorsale, archistriatum, tuberculum olfactorium, nuclei dorsolateralis and dorsomedialis of the thalamus, and throughout the hypothalamus and the median eminence. Long projecting fibers were visualized in the tractus septohippocampalis. In the brainstem VIP immunoreactive fibers and terminals were observed mainly in the substantia grisea centralis, fasciculus longitudinalis medialis, lemniscus lateralis, and in the area surrounding the nuclei of the 7th, 9th, and 10th cranial nerves.

  13. Bifidobacteria inhibit the inflammatory response induced by gliadins in intestinal epithelial cells via modifications of toxic peptide generation during digestion.

    PubMed

    Laparra, J M; Sanz, Y

    2010-03-01

    Celiac disease (CD) is a chronic enteropathy triggered by intake of gliadin, the toxic component of gluten. This study aims at evaluating the capacity of different Bifidobacterium strains to counteract the inflammatory effects of gliadin-derived peptides in intestinal epithelial (Caco-2) cells. A commercial extract of several gliadin (Gld) types (alpha, beta, gamma, [symbol: see text] ) was subjected to in vitro gastrointestinal digestion (pepsin at pH 3, pancreatin-bile at pH 6), inoculated or not with cell suspensions (10(8) colony forming units/ml) of either B. animalis IATA-A2, B. longum IATA-ES1, or B. bifidum IATA-ES2, in a bicameral system. The generated gliadin-derived peptides were identified by reverse phase-HPLC-ESI-MS/MS. Caco-2 cell cultures were exposed to the different gliadin peptide digestions (0.25 mg protein/ml), and the mRNA expression of nuclear factor kappa-B (NF-kappaB), tumor necrosis factor alpha (TNF-alpha), and chemokine CXCR3 receptor were analyzed by semi-quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) in stimulated cells. The production of the pro-inflammatory markers NF-kappaB p50, TNF-alpha, and IL-1beta (interleukine 1beta) by Caco-2 cells was also determined by ELISA. The peptides from gliadin digestions inoculated with bifidobacteria did not exhibit the toxic amino acid sequences identified in those noninoculated (alpha/beta-Gld [158-164] and alpha/beta-Gld [122-141]). The RT-PCR analysis evidenced a down-regulation in mRNA expression of pro-inflammatory biomarkers. Consistent with these results the production of NF-kappaB, TNF-alpha, and IL-1beta was reduced (18.2-22.4%, 28.0-64.8%, and abolished, respectively) in cell cultures exposed to gliadin digestions inoculated with bifidobacteria. Therefore, bifidobacteria change the gliadin-derived peptide pattern and, thereby, attenuate their pro-inflammatory effects on Caco-2 cells.

  14. Nitrogen affects cluster root formation and expression of putative peptide transporters

    PubMed Central

    Paungfoo-Lonhienne, Chanyarat; Schenk, Peer M.; Lonhienne, Thierry G. A.; Brackin, Richard; Meier, Stefan; Rentsch, Doris; Schmidt, Susanne

    2009-01-01

    Non-mycorrhizal Hakea actites (Proteaceae) grows in heathland where organic nitrogen (ON) dominates the soil nitrogen (N) pool. Hakea actites uses ON for growth, but the role of cluster roots in ON acquisition is unknown. The aim of the present study was to ascertain how N form and concentration affect cluster root formation and expression of peptide transporters. Hydroponically grown plants produced most biomass with low molecular weight ON>inorganic N>high molecular weight ON, while cluster roots were formed in the order no-N>ON>inorganic N. Intact dipeptide was transported into roots and metabolized, suggesting a role for the peptide transporter (PTR) for uptake and transport of peptides. HaPTR4, a member of subgroup II of the NRT1/PTR transporter family, which contains most characterized di- and tripeptide transporters in plants, facilitated transport of di- and tripeptides when expressed in yeast. No transport activity was demonstrated for HaPTR5 and HaPTR12, most similar to less well characterized transporters in subgroup III. The results provide further evidence that subgroup II of the NRT1/PTR family contains functional di- and tripeptide transporters. Green fluorescent protein fusion proteins of HaPTR4 and HaPTR12 localized to tonoplast, and plasma- and endomembranes, respectively, while HaPTR5 localized to vesicles of unknown identity. Grown in heathland or hydroponic culture with limiting N supply or starved of nutrients, HaPTR genes had the highest expression in cluster roots and non-cluster roots, and leaf expression increased upon re-supply of ON. It is concluded that formation of cluster roots and expression of PTR are regulated in response to N supply. PMID:19380419

  15. Ghrelin Facilitates GLUT2-, SGLT1- and SGLT2-mediated Intestinal Glucose Transport in Goldfish (Carassius auratus)

    PubMed Central

    Blanco, Ayelén Melisa; Bertucci, Juan Ignacio; Ramesh, Naresh; Delgado, María Jesús; Valenciano, Ana Isabel; Unniappan, Suraj

    2017-01-01

    Glucose homeostasis is an important biological process that involves a variety of regulatory mechanisms. This study aimed to determine whether ghrelin, a multifunctional gut-brain hormone, modulates intestinal glucose transport in goldfish (Carassius auratus). Three intestinal glucose transporters, the facilitative glucose transporter 2 (GLUT2), and the sodium/glucose co-transporters 1 (SGLT1) and 2 (SGLT2), were studied. Immunostaining of intestinal sections found colocalization of ghrelin and GLUT2 and SGLT2 in mucosal cells. Some cells containing GLUT2, SGLT1 and SGLT2 coexpressed the ghrelin/growth hormone secretagogue receptor 1a (GHS-R1a). Intraperitoneal glucose administration led to a significant increase in serum ghrelin levels, as well as an upregulation of intestinal preproghrelin, ghrelin O-acyltransferase and ghs-r1 expression. In vivo and in vitro ghrelin treatment caused a concentration- and time-dependent modulation (mainly stimulatory) of GLUT2, SGLT1 and SGLT2. These effects were abolished by the GHS-R1a antagonist [D-Lys3]-GHRP-6 and the phospholipase C inhibitor U73122, suggesting that ghrelin actions on glucose transporters are mediated by GHS-R1a via the PLC/PKC signaling pathway. Finally, ghrelin stimulated the translocation of GLUT2 into the plasma membrane of goldfish primary intestinal cells. Overall, data reported here indicate an important role for ghrelin in the modulation of glucoregulatory machinery and glucose homeostasis in fish. PMID:28338019

  16. Ghrelin Facilitates GLUT2-, SGLT1- and SGLT2-mediated Intestinal Glucose Transport in Goldfish (Carassius auratus).

    PubMed

    Blanco, Ayelén Melisa; Bertucci, Juan Ignacio; Ramesh, Naresh; Delgado, María Jesús; Valenciano, Ana Isabel; Unniappan, Suraj

    2017-03-24

    Glucose homeostasis is an important biological process that involves a variety of regulatory mechanisms. This study aimed to determine whether ghrelin, a multifunctional gut-brain hormone, modulates intestinal glucose transport in goldfish (Carassius auratus). Three intestinal glucose transporters, the facilitative glucose transporter 2 (GLUT2), and the sodium/glucose co-transporters 1 (SGLT1) and 2 (SGLT2), were studied. Immunostaining of intestinal sections found colocalization of ghrelin and GLUT2 and SGLT2 in mucosal cells. Some cells containing GLUT2, SGLT1 and SGLT2 coexpressed the ghrelin/growth hormone secretagogue receptor 1a (GHS-R1a). Intraperitoneal glucose administration led to a significant increase in serum ghrelin levels, as well as an upregulation of intestinal preproghrelin, ghrelin O-acyltransferase and ghs-r1 expression. In vivo and in vitro ghrelin treatment caused a concentration- and time-dependent modulation (mainly stimulatory) of GLUT2, SGLT1 and SGLT2. These effects were abolished by the GHS-R1a antagonist [D-Lys3]-GHRP-6 and the phospholipase C inhibitor U73122, suggesting that ghrelin actions on glucose transporters are mediated by GHS-R1a via the PLC/PKC signaling pathway. Finally, ghrelin stimulated the translocation of GLUT2 into the plasma membrane of goldfish primary intestinal cells. Overall, data reported here indicate an important role for ghrelin in the modulation of glucoregulatory machinery and glucose homeostasis in fish.

  17. Identification of Nramp2 as an iron transport protein: another piece of the intestinal iron absorption puzzle.

    PubMed

    Fleet, J C

    1998-03-01

    Although a number of iron-binding proteins have been identified, the roles for specific proteins in mediating iron absorption have not been definitively assigned. Two recent papers report the identification of an iron transport protein that may be responsible for movement of iron from the intestinal lumen into the enterocyte. Coupled with the recent identification of the protein mutated in hemochromatosis, researchers are now establishing a clearer picture of the mechanism of intestinal iron absorption.

  18. Exploring the impact of drug properties on the extent of intestinal lymphatic transport - in vitro and in vivo studies.

    PubMed

    Lawless, Emma; Griffin, Brendan T; O'Mahony, Aoife; O'Driscoll, Caitriona M

    2015-05-01

    Intestinal lymphatic transport of specific lipophilic drugs offers therapeutic advantages and maximises oral bioavailability. The aims of this study were; to compare intestinal lymphatic transport of a range of drugs and to investigate the influence of cyclosporine A on the mechanism/extent of lymphatic transport. Caco2 cells and an anaesthetised mesenteric lymphatic cannulated rat model were used for in vitro and in vivo studies. Lymphatic transport of three lipophilic drugs was directly compared in a long chain fatty acid formulation. In addition, the impact of cyclosporine A on triglyceride turnover was evaluated in vivo and in vitro. The extent of intestinal lymphatic transport in rats was positively correlated with drug solubility in triglyceride and negatively correlated with drug aqueous solubility. Cyclosporine A displayed non-linear lymphatic transport kinetics and reduced intestinal lymph triglyceride. In vitro experiments indicated that the cellular processes affected were intracellular lipid processing and/or lipid secretion. The linear correlations obtained using a range of lipophilic drugs confirm that the simplified approach of determining aqueous or triglyceride drug solubility is useful in predicting the extent of lymphatic transport. In vitro experiments correlated with in vivo observations, demonstrating the usefulness of the Caco-2 model for mechanistic investigations.

  19. Acquisition of dietary copper: a role for anion transporters in intestinal apical copper uptake.

    PubMed

    Zimnicka, Adriana M; Ivy, Kristin; Kaplan, Jack H

    2011-03-01

    Copper is an essential micronutrient in humans and is required for a wide range of physiological processes, including neurotransmitter biosynthesis, oxidative metabolism, protection against reactive oxygen species, and angiogenesis. The first step in the acquisition of dietary copper is absorption from the intestinal lumen. The major human high-affinity copper uptake protein, human copper transporter hCTR1, was recently shown to be at the basolateral or blood side of both intestinal and renal epithelial cell lines and thus does not play a direct role in this initial step. We sought to functionally identify the major transport pathways available for the absorption of dietary copper across the apical intestinal membrane using Caco2 cells, a well-established model for human enterocytes. The initial rate of apical copper uptake into confluent monolayers of Caco2 cells is greatly elevated if amino acids and serum proteins are removed from the growth media. Uptake from buffered saline solutions at neutral pH (but not at lower pH) is inhibited by either d- or l-histidine, unaltered by the removal of sodium ions, and inhibited by ∼90% when chloride ions are replaced by gluconate or sulfate. Chloride-dependent copper uptake occurs with Cu(II) or Cu(I), although Cu(I) uptake is not inhibited by histidine, nor by silver ions. A well-characterized inhibitor of anion exchange systems, DIDS, inhibited apical copper uptake by 60-70%, while the addition of Mn(II) or Fe(II), competitive substrates for the divalent metal transporter DMT1, had no effect on copper uptake. We propose that anion exchangers play an unexpected role in copper absorption, utilizing copper-chloride complexes as pseudo-substrates. This pathway is also observed in mouse embryonic fibroblasts, human embryonic kidney cells, and Cos-7 cells. The special environment of low pH, low concentration of protein, and protonation of amino acids in the early intestinal lumen make this pathway especially important in

  20. Acquisition of dietary copper: a role for anion transporters in intestinal apical copper uptake

    PubMed Central

    Zimnicka, Adriana M.; Ivy, Kristin

    2011-01-01

    Copper is an essential micronutrient in humans and is required for a wide range of physiological processes, including neurotransmitter biosynthesis, oxidative metabolism, protection against reactive oxygen species, and angiogenesis. The first step in the acquisition of dietary copper is absorption from the intestinal lumen. The major human high-affinity copper uptake protein, human copper transporter hCTR1, was recently shown to be at the basolateral or blood side of both intestinal and renal epithelial cell lines and thus does not play a direct role in this initial step. We sought to functionally identify the major transport pathways available for the absorption of dietary copper across the apical intestinal membrane using Caco2 cells, a well-established model for human enterocytes. The initial rate of apical