Neutral Na-amino acid cotransport is differentially regulated by glucocorticoids in the normal and chronically inflamed rabbit small intestine

2007 ◽  
Vol 292 (2) ◽  
pp. G467-G474 ◽  
Author(s):  
Uma Sundaram ◽  
Sheik Wisel ◽  
Steven Coon
Keyword(s):  
Amino Acid ◽  
Intestinal Inflammation ◽  
Membrane Vesicles ◽  
Kinetic Studies ◽  
Protein Levels ◽  
Rabbit Small Intestine ◽  
Villus Cell ◽  
Important Means ◽  
Normal Intestine ◽  
Chronic Intestinal Inflammation

Neutral Na-amino acid cotransport by system ATB0 [e.g., Na-alanine cotransport (NAcT)] is an important means of assimilation of amino acids in the intestine. NAcT is inhibited during chronic intestinal inflammation by an alteration in the affinity for the amino acid. How glucocorticoids, a standard of treatment for diseases characterized by chronic intestinal inflammation, may affect NAcT during chronic enteritis is not known. Thus we first demonstrated that methylprednisolone (MP) stimulated NAcT in the normal intestine. The mechanism of stimulation was secondary to an increase in cotransporter numbers without an alteration in the affinity for the amino acid. Treatment with MP reversed the reduction in NAcT in villus cells from the chronically inflamed intestine. MP also alleviated the decrease in Na-K-ATPase activity in villus cells during chronic enteritis. However, MP treatment reversed the NAcT inhibition in villus cell brush border membrane vesicles from the inflamed intestine, which suggested an effect of MP at the level of the cotransporter itself. Kinetic studies demonstrated that the reversal of NAcT inhibition by MP was secondary to restoration in the affinity for the amino acid without a change in the Vmax. Unaltered steady-state mRNA and immunoreactive protein levels of NAcT also indicated that the number of cotransporters was unchanged after MP treatment in the chronically inflamed intestine. These results indicated that MP reversed NAcT inhibition in the chronically inflamed intestine by restoring the affinity of the transporter for the amino acid while it stimulated NAcT in the normal intestine by increasing the cotransporter numbers. Therefore, MP differentially regulates NAcT in the normal and chronically inflamed intestine.

scholarly journals Mechanism of leukotriene D4 inhibition of Na-alanine cotransport in intestinal epithelial cells

2008 ◽  
Vol 295 (1) ◽  
pp. G1-G6 ◽  
Author(s):  
Jamilur R. Talukder ◽  
Ramesh Kekuda ◽  
Prosenjit Saha ◽  
Uma Sundaram
Keyword(s):  
Amino Acid ◽  
Intestinal Inflammation ◽  
Rabbit Model ◽  
Intestinal Epithelial ◽  
Leukotriene D4 ◽  
Real Time Quantitative Pcr ◽  
Protein Levels ◽  
Mechanism Of Inhibition ◽  
Rabbit Small Intestine ◽  
Chronic Intestinal Inflammation

In a rabbit model of chronic intestinal inflammation, we previously demonstrated inhibition of neutral Na-amino acid cotransport. The mechanism of the inhibition was secondary to a decrease in the affinity for amino acid rather than the number of cotransporters. Since leukotriene (LT)D4 is known to be elevated in enterocytes during chronic intestinal inflammation, we used rat intestinal epithelial cell (IEC-18) monolayers to determine the mechanism of regulation of Na-alanine cotransport (alanine, serine, cysteine transporter 1: ASCT1) by LTD4. Na-alanine cotransport was inhibited by LTD4 in IEC-18 cells. The mechanism of inhibition of ASCT1 (solute carrier, SLC1A4) by LTD4 is secondary to a decrease in the affinity of the cotransporter for alanine without a significant change in cotransporter numbers and is not secondary to an alteration in the Na+ extruding capacity of the cells. Real-time quantitative PCR and Western blot analysis results indicate that ASCT1 message and protein levels are also unchanged in LTD4-treated IEC-18 cells. These results indicate that LTD4 inhibits Na-dependent neutral amino acid cotransport in IEC. The mechanism of inhibition is secondary to a decrease in the affinity for alanine, which is identical to that seen in villus cells from the chronically inflamed rabbit small intestine, where LTD4 levels are significantly increased.

Na-glucose and Na-neutral amino acid cotransport are uniquely regulated by constitutive nitric oxide in rabbit small intestinal villus cells

2005 ◽  
Vol 289 (6) ◽  
pp. G1030-G1035 ◽  
Author(s):  
Steven Coon ◽  
James Kim ◽  
Guohong Shao ◽  
Uma Sundaram
Keyword(s):  
Nitric Oxide ◽  
Small Intestine ◽  
Amino Acid ◽  
Basolateral Membrane ◽  
Kinetic Studies ◽  
Mrna Levels ◽  
Protein Levels ◽  
Mechanism Of Inhibition ◽  
Rabbit Small Intestine ◽  
Villus Cell

Na-nutrient cotransport processes are not only important for the assimilation of essential nutrients but also for the absorption of Na in the mammalian small intestine. The effect of constitutive nitric oxide (cNO) on Na-glucose (SGLT-1) and Na-amino acid cotransport (NAcT) in the mammalian small intestine is unknown. Inhibition of cNO synthase with NG-nitro-l-arginine methyl ester (l-NAME) resulted in the inhibition of Na-stimulated 3H- O-methyl-d-glucose uptake in villus cells. However, Na-stimulated alanine uptake was not affected in these cells. The l-NAME-induced reduction in SGLT-1 in villus cells was not secondary to an alteration in basolateral membrane Na-K-ATPase activity, which provides the favorable Na gradient for this cotransport process. In fact, SGLT-1 was inhibited in villus cell brush-border membrane (BBM) vesicles prepared from animals treated with l-NAME. Kinetic studies demonstrated that the mechanism of inhibition of SGLT-1 was secondary to a decrease in the affinity for glucose without a change in the maximal rate of uptake of glucose. Northern blot studies demonstrated no change in the mRNA levels of SGLT-1. Western blot studies demonstrated no significant change in the immunoreactive protein levels of SGLT-1 in ileal villus cell BBM from l-NAME-treated rabbits. These studies indicate that inhibition of cNO production inhibits SGLT-1 but not NAcT in the rabbit small intestine. Therefore, whereas cNO promotes Na-glucose cotransport, it does not affect NAcT in the mammalian small intestine.

Mechanism of inhibition of Na+-bile acid cotransport during chronic ileal inflammation in rabbits

1998 ◽  
Vol 275 (6) ◽  
pp. G1259-G1265 ◽  
Author(s):  
U. Sundaram ◽  
S. Wisel ◽  
S. Stengelin ◽  
W. Kramer ◽  
V. Rajendran
Keyword(s):  
Bile Acid ◽  
Amino Acid ◽  
Brush Border Membrane ◽  
Rabbit Model ◽  
Membrane Vesicles ◽  
Kinetic Studies ◽  
Transport Processes ◽  
Protein Levels ◽  
Mechanism Of Inhibition ◽  
Villus Cell

In the chronically inflamed ileum, unique mechanisms of alteration of similar transport processes suggest regulation by different immune-inflammatory mediator pathways. In a rabbit model of chronic ileitis, we previously demonstrated that Na+-glucose cotransport was inhibited by a decrease in the cotransporter numbers, whereas Na+-amino acid cotransport was inhibited by a decrease in the affinity for the amino acid. In this study, we demonstrated that Na+-bile acid cotransport was reduced in villus cells from the chronically inflamed ileum. In villus cell brush-border membrane vesicles from the chronically inflamed ileum, Na+-bile acid cotransport was reduced as well, suggesting a direct effect at the cotransporter itself. Kinetic studies demonstrated that Na+-bile acid cotransport was inhibited by both a decrease in the affinity as well as a decrease in the maximal rate of uptake of the bile acid. Analysis of steady-state mRNA and immunoreactive protein levels of the Na+-bile acid cotransporter also demonstrated some reduction during chronic ileitis. Thus, in the chronically inflamed ileum, the mechanisms of inhibition of Na+-glucose, Na+-amino acid, and Na+-bile acid cotransport are different. These data suggest that different cotransporters are uniquely altered either secondary to their intrinsic differences or by different immune-inflammatory mediators during chronic ileitis.

Corticosteroids reverse the inhibition of Na-glucose cotransport in the chronically inflamed rabbit ileum

1999 ◽  
Vol 276 (1) ◽  
pp. G211-G218 ◽  
Author(s):  
Uma Sundaram ◽  
Steve Coon ◽  
Sheik Wisel ◽  
A. Brian West
Keyword(s):  
Atpase Activity ◽  
Brush Border Membrane ◽  
Rabbit Model ◽  
Membrane Vesicles ◽  
Kinetic Studies ◽  
Maximal Velocity ◽  
Rabbit Ileum ◽  
Protein Levels ◽  
Mechanism Of Inhibition ◽  
Villus Cell

In a rabbit model of chronic ileal inflammation, we previously demonstrated inhibition of Na-glucose cotransport (SGLT-1). The mechanism of inhibition was secondary to a decrease in the number of cotransporters and not solely secondary to an inhibition of Na-K-ATPase or altered affinity for glucose. In this study, we determined the effect of methylprednisolone (MP) on SGLT-1 inhibition during chronic ileitis. Treatment with MP almost completely reversed the reduction in SGLT-1 in villus cells from the chronically inflamed ileum. MP also reversed the decrease in Na-K-ATPase activity in villus cells during chronic ileitis. However, MP treatment reversed the SGLT-1 inhibition in villus cell brush-border membrane vesicles from the inflamed ileum, which suggested an effect of MP at the level of the cotransporter itself. Kinetic studies demonstrated that the reversal of SGLT-1 inhibition by MP was secondary to an increase in the maximal velocity for glucose without a change in the affinity. Analysis of immunoreactive protein levels of the cotransporter demonstrated a restoration of the cotransporter numbers after MP treatment in the chronically inflamed ileum. Thus MP treatment alleviates SGLT-1 inhibition in the chronically inflamed ileum by increasing the number of cotransporters and not solely secondary to enhancing the activity of Na-K-ATPase or by altering the affinity for glucose.

scholarly journals Involvement of calcium-sensing receptor activation in the alleviation of intestinal inflammation in a piglet model by dietary aromatic amino acid supplementation

2018 ◽  
Vol 120 (12) ◽  
pp. 1321-1331 ◽  
Author(s):  
Hongnan Liu ◽  
Bie Tan ◽  
Bo Huang ◽  
Jianjun Li ◽  
Jing Wang ◽  
...  
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Inflammatory Cytokines ◽  
Intestinal Inflammation ◽  
Aromatic Amino Acids ◽  
Dietary Supplementation ◽  
Basal Diet ◽  
Signalling Pathway ◽  
Protein Levels ◽  
Pro Inflammatory Cytokines

AbstractCa2+-sensing receptor (CaSR) represents a potential therapeutic target for inflammatory bowel diseases and strongly prefers aromatic amino acid ligands. We investigated the regulatory effects of dietary supplementation with aromatic amino acids – tryptophan, phenylalanine and tyrosine (TPT) – on the CaSR signalling pathway and intestinal inflammatory response. The in vivo study was conducted with weanling piglets using a 2 × 2 factorial arrangement in a randomised complete block design. Piglets were fed a basal diet or a basal diet supplemented with TPT and with or without inflammatory challenge. The in vitro study was performed in porcine intestinal epithelial cell line to investigate the effects of TPT on inflammatory response using NPS-2143 to inhibit CaSR. Dietary supplementation of TPT alleviated histopathological injury and decreased myeloperoxidase activity in intestine challenged with lipopolysaccharide. Dietary supplementation of TPT decreased serum concentration of pro-inflammatory cytokines (IL-1β, IL-6, IL-8, IL-12, granulocyte-macrophage colony-stimulating factor, TNF-α), as well as the mRNA abundances of pro-inflammatory cytokines in intestine but enhanced anti-inflammatory cytokines IL-4 and transforming growth factor-β mRNA levels compared with pigs fed control diet and infected by lipopolysaccharide. Supplementation of TPT increased CaSR and phospholipase Cβ2 protein levels, but decreased inhibitor of NF-κB kinase α/β and inhibitor of NF-κB (IκB) protein levels in the lipopolysaccharide-challenged piglets. When the CaSR signalling pathway was blocked by NPS-2143, supplementation of TPT decreased the CaSR protein level, but enhanced phosphorylated NF-κB and IκB levels in IPEC-J2 cells. To conclude, supplementation of aromatic amino acids alleviated intestinal inflammation as mediated through the CaSR signalling pathway.

Unique regulation of anion/HCO3- exchangers by constitutive nitric oxide in rabbit small intestine

2003 ◽  
Vol 285 (6) ◽  
pp. G1084-G1090 ◽  
Author(s):  
Steven Coon ◽  
Uma Sundaram
Keyword(s):  
Nitric Oxide ◽  
Small Intestine ◽  
Kinetic Studies ◽  
Transport Processes ◽  
Crypt Cell ◽  
Maximal Rate ◽  
Mechanism Of Inhibition ◽  
Rabbit Small Intestine ◽  
Villus Cell ◽  
Inactive Analog

In the rabbit small intestine, there are three functionally different brush-border membrane (BBM) anion/HCO3- exchangers: 1) Cl/HCO3- exchange on the BBM of villus cells responsible for coupled NaCl absorption; 2) Cl/HCO3- exchange on the BBM of crypt cells possibly involved in HCO3- secretion; and 3) short-chain fatty acid (SCFA)/HCO3- exchange on the BBM of villus cells, which facilitates SCFA absorption. Although constitutive nitric oxide (cNO) has been postulated to alter many gastrointestinal tract functions, how cNO may specifically alter these three transporters is unknown. Inhibition of cNO synthase with NG-nitro-l-arginine methyl ester (l-NAME) 1) did not affect villus cell BBM Cl/HCO3 change, 2) stimulated crypt cell BBM Cl/HCO3- exchange, and 3) inhibited villus cell BBM SCFA/HCO3- exchange. d-NAME, an inactive analog of l-NAME, and l- N6-(1-iminoethyl)lysine, a more selective inhibitor of inducible NO, did not affect these transport processes. Kinetic studies demonstrated that 1) the mechanism of inhibition of crypt cell BBM Cl/HCO3- exchange is secondary to a decrease in the maximal rate of uptake of Cl, without an alteration in the affinity of the transporter for Cl, and 2) the mechanism of stimulation of villus cell BBM SCFA/HCO3- exchange is secondary to an increase in the affinity of the transporter for SCFA without an alteration in the maximal rate of uptake of SCFA. These results indicate that cNO uniquely regulates the three BBM anion/HCO3- transporters in the rabbit small intestine.

scholarly journals The Effects of Dietary Glycine on the Acetic Acid-Induced Mouse Model of Colitis

2020 ◽  
Vol 2020 ◽  
pp. 1-8 ◽  
Author(s):  
Xin Wu ◽  
Yongmin Zheng ◽  
Jie Ma ◽  
Jie Yin ◽  
Shuai Chen
Keyword(s):  
Gene Expression ◽  
Amino Acids ◽  
Acetic Acid ◽  
Amino Acid ◽  
Mouse Model ◽  
Intestinal Microbiota ◽  
Intestinal Inflammation ◽  
Serum Concentrations ◽  
Intestinal Immunity ◽  
Chronic Intestinal Inflammation

Inflammatory bowel disease, a gut disease that is prevalent worldwide, is characterized by chronic intestinal inflammation, such as colitis, and disorder of the gut microbiome. Glycine (Gly) is the simplest amino acid and functions as an anti-inflammatory immune-nutrient and intestinal microbiota regulator. This study aimed at investigating the effect of Gly on colitis induced in mice by intrarectal administration of 5% acetic acid (AA). Bodyweight and survival rates were monitored, and colonic length and weight, serum amino acid concentrations, intestinal inflammation-related gene expression, and colonic microbiota abundances were analyzed. The results showed that Gly dietary supplementation had no effect on the survival rate or the ratio of colonic length to weight. However, Gly supplementation reversed the AA-induced increase in serum concentrations of amino acids such as glutamate, leucine, isoleucine, and valine. Furthermore, Gly inhibited colonic gene expression of interleukin- (IL-) 1β and promoted IL-10 expression in colitis mice. Gly supplementation also reversed the AA-induced reduction in the abundance of bacteria such as Clostridia, Ruminococcaceae, and Clostridiales. This change in the intestinal microbiota was possibly attributable to the changes in colonic IL-10 expression and serum concentrations of valine and leucine. In sum, Gly supplementation regulated the serum concentrations of amino acids, the levels of colonic immune-associated gene expression, and the intestinal microbiota in a mouse model of colitis. These findings enhance our understanding of the role of Gly in regulating metabolism, intestinal immunity, and the gut microbiota in animals afflicted with colitis.

Mechanism of inhibition of Na+-glucose cotransport in the chronically inflamed rabbit ileum

1997 ◽  
Vol 273 (4) ◽  
pp. G913-G919 ◽  
Author(s):  
U. Sundaram ◽  
S. Wisel ◽  
V. M. Rajendren ◽  
A. B. West
Keyword(s):  
Steady State ◽  
Brush Border Membrane ◽  
Rabbit Model ◽  
Kinetic Studies ◽  
Maximal Rate ◽  
Rabbit Ileum ◽  
Intact Cells ◽  
Protein Levels ◽  
Mechanism Of Inhibition ◽  
Villus Cell

In a rabbit model of chronic ileal inflammation, we previously demonstrated that coupled NaCl absorption was reduced because of an inhibition of Cl−/[Formula: see text]but not Na+/H+exchange on the brush-border membrane (BBM) of villus cells. In this study we determined the alterations in Na+-stimulated glucose [Na+- O-methyl-d-glucose (Na+-OMG)] absorption during chronic ileitis. Na+-OMG uptake was reduced in villus cells from the chronically inflamed ileum. Na+-K+-adenosinetriphosphatase (ATPase), which provides the favorable Na+gradient for this cotransporter in intact cells, was found to be reduced also. However, in villus cell BBM vesicles from the inflamed ileum Na+-OMG uptake was reduced as well, suggesting an effect at the level of the cotransporter itself. Kinetic studies demonstrated that Na+-OMG uptake in the inflamed ileum was inhibited by a decrease in the maximal rate of uptake for OMG without a change in the affinity. Analysis of steady-state mRNA and immunoreactive protein levels of this cotransporter demonstrates reduced expression. Thus Na+-glucose cotransport was inhibited in the chronically inflamed ileum, and the inhibition was secondary to a decrease in the number of cotransporters and not solely secondary to an inhibition of Na+-K+-ATPase or altered affinity for glucose.

Effect of chronic inflammation on ileal short-chain fatty acid/bicarbonate exchange

2000 ◽  
Vol 278 (4) ◽  
pp. G585-G590 ◽  
Author(s):  
Tasos Manokas ◽  
John J. Fromkes ◽  
Uma Sundaram
Keyword(s):  
Chronic Inflammation ◽  
Intestinal Inflammation ◽  
Rabbit Model ◽  
Kinetic Studies ◽  
Short Chain Fatty Acids ◽  
Short Chain ◽  
Rabbit Ileum ◽  
Mechanism Of Inhibition ◽  
Chronic Intestinal Inflammation ◽  
Crypt Cells

Short-chain fatty acids (SCFA) have been demonstrated to at least partially ameliorate chronic intestinal inflammation. However, whether and how intestinal SCFA absorption may be altered during chronic intestinal inflammation is unknown. A rabbit model of chronic ileitis produced by coccidia was used to determine the effect of chronic inflammation on ileal SCFA/[Formula: see text] exchange. SCFA/[Formula: see text] exchange was present in the brush-border membrane (BBM) of villus but not crypt cells from normal rabbit ileum. An anion-exchange inhibitor, DIDS, significantly inhibited SCFA/[Formula: see text] exchange. Extravesicular Cl− did not alter the uptake of SCFA, suggesting that SCFA/[Formula: see text] exchange is a transport process distinct from Cl−/[Formula: see text] exchange. In chronically inflamed ileum, SCFA/[Formula: see text] exchange was also present only in BBM of villus cells. The exchanger was sensitive to DIDS and was unaffected by extravesicular Cl−. However, SCFA/[Formula: see text] exchange was significantly reduced in villus cell BBM vesicles (BBMV) from chronically inflamed ileum. Kinetic studies demonstrated that the maximal rate of uptake of SCFA, but not the affinity for SCFA, was reduced in chronically inflamed rabbit ileum. These data demonstrate that a distinct SCFA/[Formula: see text] exchange is present on BBMV of villus but not crypt cells in normal rabbit ileum. SCFA/[Formula: see text] exchange is inhibited in chronically inflamed rabbit ileum. The mechanism of inhibition is most likely secondary to a reduction in transporter numbers rather than altered affinity for SCFA.

Mechanism of regulation of rabbit intestinal villus cell brush border membrane Na/H exchange by nitric oxide

2007 ◽  
Vol 292 (2) ◽  
pp. G475-G481 ◽  
Author(s):  
Steven Coon ◽  
Guohong Shao ◽  
Sheik Wisel ◽  
Raju Vulaupalli ◽  
Uma Sundaram
Keyword(s):  
Nitric Oxide ◽  
Brush Border ◽  
Brush Border Membrane ◽  
Kinetic Studies ◽  
Protein Levels ◽  
Nacl Absorption ◽  
Exchange Kinetic ◽  
Villus Cell ◽  
Inhibitory Tone ◽  
Inactive Analog

In the mammalian small intestine, coupled NaCl absorption occurs via the dual operation of Na/H and Cl/HCO3exchange on the villus cell brush border membrane (BBM). Although constitutive nitric oxide (cNO) has been demonstrated to alter gastrointestinal tract functions, how cNO may specifically alter these two transporters to regulate coupled NaCl absorption is unknown. In villus cells, inhibition of cNO synthase (cNOS) with l- NG-nitroarginine methylester (l-NAME) stimulated Na/H exchange whereas Cl/HCO3exchange was unaffected. In villus cell BBM vesicles (BBMV) prepared from rabbits treated with l-NAME, Na/H exchange was also stimulated. d-NAME, an inactive analog of l-NAME, and N6-(1-imonoethyl)-l-lysine dihydrochloride, a more selective inhibitor of inducible NO synthase, did not affect Na/H exchange. Kinetic studies demonstrated that the mechanism of stimulation is secondary to an increase in the maximal rate of uptake of Na, without an alteration in the affinity of the transporter for Na. Northern blot studies demonstrated an increase in the message for the BBM Na/H exchanger NHE3, and Western blot studies showed that the immunoreactive protein levels of NHE3 was increased when cNOS was inhibited. Thus these results indicate that cNO under nominal physiological states most likely maintains an inhibitory tone on small intestinal coupled NaCl absorption by specifically inhibiting BBM Na/H expression.

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