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López-Yoldi M, Castilla-Madrigal R, Lostao MP, Barber A, Prieto J, Martínez JA, Bustos M, Moreno-Aliaga MJ. Cardiotrophin-1 decreases intestinal sugar uptake in mice and in Caco-2 cells. Acta Physiol (Oxf) 2016; 217:217-26. [PMID: 26972986 DOI: 10.1111/apha.12674] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2015] [Revised: 10/12/2015] [Accepted: 03/04/2016] [Indexed: 12/15/2022]
Abstract
AIM Cardiotrophin-1 (CT-1) is a member of the IL-6 family of cytokines with a key role in glucose and lipid metabolism. In the current investigation, we examined the in vivo and in vitro effects of CT-1 treatment on intestinal sugar absorption in different experimental models. METHODS rCT-1 effects on α-Methyl-D-glucoside uptake were assessed in everted intestinal rings from wild-type and CT-1(-/-) mice and in Caco-2 cells. rCT-1 actions on SGLT-1 expression in brush border membrane vesicles and the identification of the potential signalling pathways involved were determined by Western blot. RESULTS In vivo administration (0.2 mg kg(-1) ) of rCT-1 caused a significant decrease on α-Methyl-D-glucoside uptake in everted intestinal rings from wild-type and CT-1(-/-) mice after short-term and long-term treatments. Similarly, in vitro treatment (1-50 ng mL(-1) ) with rCT-1 reduced α-Methyl-D-glucoside uptake in everted intestinal rings. In Caco-2 cells, rCT-1 treatment (20 ng mL(-1) , 1 and 24 h) lowered apical uptake of α-Methyl-D-glucoside in parallel with a decrease on SGLT-1 protein expression. rCT-1 promoted the phosphorylation of STAT-3 after 5 and 15 min treatment, but inhibited the activation by phosphorylation of AMPK after 30 and 60 min. Interestingly, pre-treatment with the JAK/STAT inhibitor (AG490) and with the AMPK activator (AICAR) reversed the inhibitory effects of rCT-1 on α-Methyl-D-glucoside uptake. AICAR also prevented the inhibition of SGLT-1 observed in rCT-1-treated cells. CONCLUSIONS CT-1 inhibits intestinal sugar absorption by the reduction of SGLT-1 levels through the AMPK pathway, which could also contribute to explain the hypoglycaemic and anti-obesity properties of CT-1.
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Affiliation(s)
- M. López-Yoldi
- Department of Nutrition, Food Science and Physiology; University of Navarra; Pamplona Navarra Spain
- Centre for Nutrition Research; University of Navarra; Pamplona Navarra Spain
| | - R. Castilla-Madrigal
- Department of Nutrition, Food Science and Physiology; University of Navarra; Pamplona Navarra Spain
- Centre for Nutrition Research; University of Navarra; Pamplona Navarra Spain
| | - M. P. Lostao
- Department of Nutrition, Food Science and Physiology; University of Navarra; Pamplona Navarra Spain
- Centre for Nutrition Research; University of Navarra; Pamplona Navarra Spain
- IdiSNA; Navarra Institute for Health Research; Pamplona Spain
| | - A. Barber
- Department of Nutrition, Food Science and Physiology; University of Navarra; Pamplona Navarra Spain
| | - J. Prieto
- Department of Gene Therapy and Hepatology; CIMA; University of Navarra; Pamplona Navarra Spain
- CIBERehd; Institute of Health Carlos III; Madrid Spain
| | - J. A. Martínez
- Department of Nutrition, Food Science and Physiology; University of Navarra; Pamplona Navarra Spain
- Centre for Nutrition Research; University of Navarra; Pamplona Navarra Spain
- IdiSNA; Navarra Institute for Health Research; Pamplona Spain
- CIBERobn; Physiopathology of Obesity and Nutrition; Institute of Health Carlos III; Madrid Spain
| | - M. Bustos
- Department of Gene Therapy and Hepatology; CIMA; University of Navarra; Pamplona Navarra Spain
| | - M. J. Moreno-Aliaga
- Department of Nutrition, Food Science and Physiology; University of Navarra; Pamplona Navarra Spain
- Centre for Nutrition Research; University of Navarra; Pamplona Navarra Spain
- IdiSNA; Navarra Institute for Health Research; Pamplona Spain
- CIBERobn; Physiopathology of Obesity and Nutrition; Institute of Health Carlos III; Madrid Spain
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Abstract
PURPOSE OF REVIEW Sodium-glucose cotransporters (SGLTs) are important mediators of glucose uptake across apical cell membranes. SGLT1 mediates almost all sodium-dependent glucose uptake in the small intestine, while in the kidney SGLT2, and to a lesser extent SGLT1, account for more than 90% and nearly 3%, respectively, of glucose reabsorption from the glomerular ultrafiltrate. Although the recent availability of SGLT2 inhibitors for the treatment of diabetes mellitus has increased the number of clinical studies, this review has a focus on mechanisms contributing to the cellular regulation of SGLTs. RECENT FINDINGS Studies have focused on the regulation of SGLT expression under different physiological/pathophysiological conditions, for example diet, age or diabetes mellitus. Several studies provide evidence of SGLT regulation via cyclic adenosine monophosphate/protein kinase A, protein kinase C, glucagon-like peptide 2, insulin, leptin, signal transducer and activator of transcription-3 (STAT3), phosphoinositide-3 kinase (PI3K)/Akt, mitogen-activated protein kinases (MAPKs), nuclear factor-kappaB (NF-kappaB), with-no-K[Lys] kinases/STE20/SPS1-related proline/alanine-rich kinase (Wnk/SPAK) and regulatory solute carrier protein 1 (RS1) pathways. SUMMARY SGLT inhibitors are important drugs for glycemic control in diabetes mellitus. Although the contribution of SGLT1 for absorption of glucose from the intestine as well as SGLT2/SGLT1 for renal glucose reabsorption has been comprehensively defined, this review provides an up-to-date outline for the mechanistic regulation of SGLT1/SGLT2.
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Fanjul C, Barrenetxe J, De Pablo-Maiso L, Lostao MP. In vivo regulation of intestinal absorption of amino acids by leptin. J Endocrinol 2015; 224:17-23. [PMID: 25349247 DOI: 10.1530/joe-14-0453] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Leptin is secreted by the gastric mucosa and is able to reach the intestinal lumen and bind to its receptors located in the apical membranes of enterocytes. We have previously demonstrated that apical leptin inhibits uptake of amino acids in rat intestine in vitro and in Caco-2 cells. The aim of the present work was to investigate the effect of leptin on absorption of amino acids using in vivo techniques, which generate situations closer to physiological conditions. In vivo intestinal absorption of amino acids in rats was measured by isolating a jejunal loop and using the single-pass perfusion system. Disappearance of glutamine (Gln), proline (Pro), and β-alanine (β-Ala) from the perfusate, in the absence or presence of leptin, was measured using a radioactivity method. Luminal leptin (25 nM) inhibited the absorption of 2 mM Pro, 5 mM β-Ala, and 5 mM Gln by approximately 45% after 5-15 min; the effect remained constant until the end of the experiment (80 min) and was rapidly and completely reversed when leptin was removed from the perfusion medium. Moreover, leptin was able to regulate the absorption of galactose and Gln in the same animal, indicating a direct action of the hormone on the specific transporters implicated in the uptake of each nutrient. The results of the present work indicate that luminal leptin decreases absorption of amino acids in vivo in a short-term manner and in a reversible way. These results, together with our previous findings, make it evident that leptin can be considered as a hormone which provides the intestine with a control mechanism to handle absorption of nutrients.
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Affiliation(s)
- Carmen Fanjul
- Department of NutritionFood Science and Physiology, University of Navarra, 31008 Pamplona, Spain
| | - Jaione Barrenetxe
- Department of NutritionFood Science and Physiology, University of Navarra, 31008 Pamplona, Spain
| | - Lorena De Pablo-Maiso
- Department of NutritionFood Science and Physiology, University of Navarra, 31008 Pamplona, Spain
| | - María Pilar Lostao
- Department of NutritionFood Science and Physiology, University of Navarra, 31008 Pamplona, Spain
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Sáinz N, Barrenetxe J, Moreno-Aliaga MJ, Martínez JA. Leptin resistance and diet-induced obesity: central and peripheral actions of leptin. Metabolism 2015; 64:35-46. [PMID: 25497342 DOI: 10.1016/j.metabol.2014.10.015] [Citation(s) in RCA: 290] [Impact Index Per Article: 32.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/23/2014] [Revised: 10/15/2014] [Accepted: 10/20/2014] [Indexed: 12/15/2022]
Abstract
Obesity is a chronic disease that represents one of the most serious global health burdens associated to an excess of body fat resulting from an imbalance between energy intake and expenditure, which is regulated by environmental and genetic interactions. The adipose-derived hormone leptin acts via a specific receptor in the brain to regulate energy balance and body weight, although this protein can also elicit a myriad of actions in peripheral tissues. Obese individuals, rather than be leptin deficient, have in most cases, high levels of circulating leptin. The failure of these high levels to control body weight suggests the presence of a resistance process to the hormone that could be partly responsible of disturbances on body weight regulation. Furthermore, leptin resistance can impair physiological peripheral functions of leptin such as lipid and carbohydrate metabolism and nutrient intestinal utilization. The present document summarizes those findings regarding leptin resistance development and the role of this hormone in the development and maintenance of an obese state. Thus, we focused on the effect of the impaired leptin action on adipose tissue, liver, skeletal muscle and intestinal function and the accompanying relationships with diet-induced obesity. The involvement of some inflammatory mediators implicated in the development of obesity and their roles in leptin resistance development are also discussed.
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Affiliation(s)
- Neira Sáinz
- Department of Nutrition, Food Sciences and Physiology, University of Navarra, C/Irunlarrea 1, 31008 Pamplona, Spain
| | - Jaione Barrenetxe
- Department of Nutrition, Food Sciences and Physiology, University of Navarra, C/Irunlarrea 1, 31008 Pamplona, Spain
| | - María J Moreno-Aliaga
- Department of Nutrition, Food Sciences and Physiology, University of Navarra, C/Irunlarrea 1, 31008 Pamplona, Spain; CIBER Fisiopatología de la Obesidad y la Nutrición (CIBERobn), Instituto de Salud Carlos III, 28029 Madrid, Spain
| | - José Alfredo Martínez
- Department of Nutrition, Food Sciences and Physiology, University of Navarra, C/Irunlarrea 1, 31008 Pamplona, Spain; CIBER Fisiopatología de la Obesidad y la Nutrición (CIBERobn), Instituto de Salud Carlos III, 28029 Madrid, Spain.
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5
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Barrenetxe J, Sánchez O, Barber A, Gascón S, Rodríguez-Yoldi MJ, Lostao MP. TNFα regulates sugar transporters in the human intestinal epithelial cell line Caco-2. Cytokine 2013; 64:181-7. [PMID: 23910014 DOI: 10.1016/j.cyto.2013.07.004] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2012] [Revised: 06/10/2013] [Accepted: 07/02/2013] [Indexed: 01/25/2023]
Abstract
PURPOSE During intestinal inflammation TNFα levels are increased and as a consequence malabsorption of nutrients may occur. We have previously demonstrated that TNFα inhibits galactose, fructose and leucine intestinal absorption in animal models. In continuation with our work, the purpose of the present study was to investigate in the human intestinal epithelial cell line Caco-2, the effect of TNFα on sugar transport and to identify the intracellular mechanisms involved. METHODS Caco-2 cells were grown on culture plates and pre-incubated during different periods with various TNFα concentrations before measuring the apical uptake of galactose, α-methyl-glucoside (MG) or fructose for 15 min. To elucidate the signaling pathway implicated, cells were pre-incubated for 30min with the PKA inhibitor H-89 or the PKC inhibitor chelerythrine, before measuring the sugar uptake. The expression in the apical membrane of the transporters implicated in the sugars uptake process (SGLT1 and GLUT5) was determined by Western blot. RESULTS TNFα inhibited 0.1mM MG uptake after pre-incubation of the cells for 6-48h with the cytokine and in the absence of cytokine pre-incubation. In contrast, 5mM fructose uptake was stimulated by TNFα only after long pre-incubation times (24 and 48 h). These effects were mediated by the binding of the cytokine to its specific receptor TNFR1, present in the apical membrane of the Caco-2 cells. Analysis of the expression of the MG and fructose transporters at the brush border membrane of the cells, after 24h pre-incubation with the cytokine, revealed decrease on the amount of SGLT1 and increase on the amount of GLUT5 proteins. Short-term inhibition of MG transport by TNFα was not modified by H-89 but was blocked by chelerythrine. CONCLUSIONS SGLT1 and GLUT5 expression in the plasma membrane is regulated by TNFα in the human epithelial cell line Caco-2 cells, leading to alteration on sugars transport, suggesting that TNFα could be considered as a physiological local regulator of nutrients absorption in response to an intestinal inflammatory status.
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Affiliation(s)
- Jaione Barrenetxe
- Department of Nutrition, Food Science and Physiology, University of Navarra, Pamplona 31008, Spain.
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6
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Leptin levels in children and adults with classic galactosaemia. JIMD Rep 2012; 9:125-131. [PMID: 23430559 DOI: 10.1007/8904_2012_191] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/25/2012] [Revised: 09/03/2012] [Accepted: 10/04/2012] [Indexed: 12/16/2022] Open
Abstract
Among the long-term complications of Classic Galactosaemia (Gal) is premature ovarian insufficiency (POI) in female patients with subtle abnormalities of reproductive function also reported in male patients. Leptin is a circulating hormone which reflects body energy stores and which affects the neuroendocrine reproductive axis and pubertal development.We measured serum leptin in 28 children (10 girls, 18 boys; mean age 7.6 years, range 0.5-17.9 years) and in 22 adults (10 females, 12 males; mean age 23.9 years, range 18-37 years) with Gal on a strict galactose-restricted diet in comparison with control data.Leptin levels (expressed as SDS for gender and pubertal stage) were lower in Gal children than controls (mean leptin-SDS = -0.71 for girls, p < 0.05, -0.97 for boys compared with SDS = 0 for controls, p < 0.05). In an age-related analysis, leptin levels did not correlate with age in children with Gal for both sexes as it did for matched controls.As expected, females had higher leptin levels than males in either group. In adults with Gal, leptin concentrations were within normal limits for both sexes when adjusted for gender and BMI. There was a linear relationship between log-leptin and BMI in children with Gal and in controls. For Gal women, log-leptin was also associated with BMI. However, for Gal men, and hence for the entire group of adult Gal patients, this association between log-leptin and BMI was not detectable. Our findings suggest that leptin dysregulation may play a role in fertility issues in individuals with Gal from an early age.
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7
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Fanjul C, Barrenetxe J, Iñigo C, Sakar Y, Ducroc R, Barber A, Lostao MP. Leptin regulates sugar and amino acids transport in the human intestinal cell line Caco-2. Acta Physiol (Oxf) 2012; 205:82-91. [PMID: 22252010 DOI: 10.1111/j.1748-1716.2012.02412.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2011] [Revised: 10/04/2011] [Accepted: 01/09/2012] [Indexed: 01/09/2023]
Abstract
AIM Studies in rodents have shown that leptin controls sugars and glutamine entry in the enterocytes by regulating membrane transporters. Here, we have examined the effect of leptin on sugar and amino acids absorption in the human model of intestinal cells Caco-2 and investigated the transporters involved. METHODS Substrate uptake experiments were performed in Caco-2 cells, grown on plates, in the presence and the absence of leptin, and the expression of the different transporters in brush border membrane vesicles was analysed by Western blot. RESULTS Leptin inhibited 0.1 mm α-methyl-D-glucoside uptake after 5 or 30 min treatment and decreased SGLT1 protein abundance in the apical membrane. Uptake of 20 μm glutamine and 0.1 mm phenylalanine was also inhibited by leptin, indicating sensitivity to the hormone of the Na(+) -dependent neutral amino acid transporters ASCT2 and B(0) AT1. This inhibition was accompanied by a reduction in the transporters expression at the brush border membrane. Leptin also inhibited 1 mm proline and β-alanine uptake in Na(+) medium at pH 6, conditions for optimal activity of the H(+) -dependent neutral amino acid transporter PAT1. In this case, abundance of PAT1 in the brush border membrane after leptin treatment was not modified. Interestingly, leptin inhibitory effect on β-alanine uptake was reversed by the PKA inhibitor H-89 suggesting involvement of PKA pathway in leptin's regulation of PAT1 activity. CONCLUSION These data show in human intestinal cells that leptin can rapidly control the activity of physiologically relevant transporters for rich-energy molecules, that is, D-glucose (SGLT1) and amino acids (ASCT2, B(0) AT1 and PAT1).
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Affiliation(s)
- C. Fanjul
- Department of Nutrition, Food Science, Physiology and Toxicology; University of Navarra; Pamplona; Spain
| | - J. Barrenetxe
- Department of Nutrition, Food Science, Physiology and Toxicology; University of Navarra; Pamplona; Spain
| | - C. Iñigo
- Department of Biochemistry; Miguel Servet Hospital; Zaragoza; Spain
| | | | | | - A. Barber
- Department of Nutrition, Food Science, Physiology and Toxicology; University of Navarra; Pamplona; Spain
| | - M. P. Lostao
- Department of Nutrition, Food Science, Physiology and Toxicology; University of Navarra; Pamplona; Spain
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8
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Klinger S, Noci B, Müller K, Breves G. Intestinal glucose absorption in calves as affected by different carbohydrate sources. J Anim Physiol Anim Nutr (Berl) 2012; 97:342-52. [PMID: 22369577 DOI: 10.1111/j.1439-0396.2012.01277.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
From numerous recent studies, it has been demonstrated that the development of the forestomach system in ruminants and thus microbial carbohydrate fermentation do not exclude the potential of the small intestines for enzymatic carbohydrate digestion and subsequent monosaccharide absorption. However, the role of regulatory nutritional factors is still under discussion. Therefore, we investigated the kinetic parameters of intestinal Na(+) -dependent glucose absorption and SGLT1 expression using isolated brush border membrane vesicles (BBMV) from the jejunum of 10-week-old calves kept on either hay, concentrate or corn silage-based diets in addition to milk replacer. While the maximal transport capacity was significantly higher for concentrate and corn silage-fed animals, SGLT1 protein expression was highest in BBMV isolated from hay-fed animals. This observation differs from the prevalent conception that induction of Na(+) -dependent glucose uptake via SGLT1 is based on an increased number of transporters at the brush border membrane.
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Affiliation(s)
- S Klinger
- Department of Physiology, University of Veterinary Medicine Hannover, Bischofsholer Damm 15, Hannover, Germany
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9
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Huang W, Bansode RR, Bal NC, Mehta M, Mehta KD. Protein kinase Cβ deficiency attenuates obesity syndrome of ob/ob mice by promoting white adipose tissue remodeling. J Lipid Res 2011; 53:368-378. [PMID: 22210924 DOI: 10.1194/jlr.m019687] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
To explore the role of leptin in PKCβ action and to determine the protective potential of PKCβ deficiency on profound obesity, double knockout (DBKO) mice lacking PKCβ and ob genes were created, and key parameters of metabolism and body composition were studied. DBKO mice had similar caloric intake as ob/ob mice but showed significantly reduced body fat content, improved glucose metabolism, and elevated body temperature. DBKO mice were resistant to high-fat diet-induced obesity. Moreover, PKCβ deficiency increased β-adrenergic signaling by inducing expression of β1- and β3-adrenergic receptors (β-ARs) in white adipose tissue (WAT) of ob/ob mice. Accordingly, p38(MAPK) activation and expression of PGC-1α and UCP-1 were increased in WAT of DBKO mice. Consistent with results of in vivo studies, inhibition of PKCβ in WAT explants from ob/ob mice also increased expression of above β-ARs. In contrast, induction of PGC-1α and UCP-1 expression in brown adipose tissue of DBKO mice was not accompanied by changes in the expression of these β-ARs. Collectively, these findings suggest that PKCβ deficiency may prevent genetic obesity, in part, by remodeling the catabolic function of adipose tissues through β-ARs dependent and independent mechanisms.
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Affiliation(s)
- Wei Huang
- Department of Molecular & Cellular Biochemistry, Dorothy M. Davis Heart & Lung Research Institute,The Ohio State University College of Medicine, 1645 Neil Avenue, Columbus, OH 43210
| | - Rishipal R Bansode
- Department of Molecular & Cellular Biochemistry, Dorothy M. Davis Heart & Lung Research Institute,The Ohio State University College of Medicine, 1645 Neil Avenue, Columbus, OH 43210
| | - Naresh C Bal
- Department of Physiology, The Ohio State University College of Medicine, 1645 Neil Avenue, Columbus, OH 43210 and
| | - Madhu Mehta
- Department of Medicine, The Ohio State University College of Medicine, 1645 Neil Avenue, Columbus, OH 43210
| | - Kamal D Mehta
- Department of Molecular & Cellular Biochemistry, Dorothy M. Davis Heart & Lung Research Institute,The Ohio State University College of Medicine, 1645 Neil Avenue, Columbus, OH 43210.
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Ducroc R, Sakar Y, Fanjul C, Barber A, Bado A, Pilar Lostao M. Luminal leptin inhibits L-glutamine transport in rat small intestine: involvement of ASCT2 and B0AT1. Am J Physiol Gastrointest Liver Physiol 2010; 299:G179-85. [PMID: 20448142 PMCID: PMC3112213 DOI: 10.1152/ajpgi.00048.2010] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
L-glutamine is the primary metabolic fuel for enterocytes. Glutamine from the diet is transported into the absorptive cells by two sodium-dependent neutral amino acid transporters present at the apical membrane: ASCT2/SLC1A5 and B(0)AT1/SLC6A19. We have demonstrated that leptin is secreted into the stomach lumen after a meal and modulates the transport of sugars after binding to its receptors located at the brush border of the enterocytes. The present study was designed to address the effect of luminal leptin on Na(+)-dependent glutamine (Gln) transport in rat intestine and identify the transporters involved. We found that 0.2 nM leptin inhibited uptake of Gln and phenylalanine (Phe) (substrate of B(0)AT1) using everted intestinal rings. In Ussing chambers, 10 mM Gln absorption followed as Na(+)-induced short-circuit current was inhibited by leptin in a dose-dependent manner (maximum inhibition at 10 nM; I(C50) = approximately 0.1 nM). Phe absorption was also decreased by leptin. Western blot analysis after 3-min incubation of the intestinal loops with 10 mM Gln, showed marked increase of ASCT2 and B(0)AT1 protein in the brush-border membrane that was reduced by rapid preincubation of the intestinal lumen with 1 nM leptin. Similarly, the increase in ASCT2 and B(0)AT1 gene expression induced by 60-min incubation of the intestine with 10 mM Gln was strongly reduced after a short preincubation period with leptin. Altogether these data demonstrate that, in rat, leptin controls the active Gln entry through reduction of both B(0)AT1 and ASCT2 proteins traffic to the apical plasma membrane and modulation of their gene expression.
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Affiliation(s)
- Robert Ducroc
- Institut National de la Santé et de la Recherche Médicale (INSERM), U773, CRB3, Digestive Physiology and Neuroendocrinology, 16 Rue Henri Huchard, 75890 Paris, Cedex 18, France.
| | - Yassine Sakar
- CRB3, Centre de recherche biomédicale Bichat-Beaujon
INSERM : U773Université Paris-Diderot - Paris VIIFaculte de Medecine Xavier Bichat 16, Rue Henri Huchard 75870 PARIS CEDEX 18,FR
| | - Carmen Fanjul
- Dept. of Nutrition, Food Science, Physiology and Toxicology
University of NavarraPamplona, 31080,ES
| | - Ana Barber
- Dept. of Nutrition, Food Science, Physiology and Toxicology
University of NavarraPamplona, 31080,ES
| | - André Bado
- CRB3, Centre de recherche biomédicale Bichat-Beaujon
INSERM : U773Université Paris-Diderot - Paris VIIFaculte de Medecine Xavier Bichat 16, Rue Henri Huchard 75870 PARIS CEDEX 18,FR
| | - Maria Pilar Lostao
- Dept. of Nutrition, Food Science, Physiology and Toxicology
University of NavarraPamplona, 31080,ES
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11
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Krimi RB, Letteron P, Chedid P, Nazaret C, Ducroc R, Marie JC. Resistin-like molecule-beta inhibits SGLT-1 activity and enhances GLUT2-dependent jejunal glucose transport. Diabetes 2009; 58:2032-8. [PMID: 19502416 PMCID: PMC2731541 DOI: 10.2337/db08-1786] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
OBJECTIVE An increased expression of RELM-beta (resistin-like molecule-beta), a gut-derived hormone, is observed in animal models of insulin resistance/obesity and intestinal inflammation. Intestinal sugar absorption is modulated by dietary environment and hormones/cytokines. The aim of this study was to investigate the effect of RELM-beta on intestinal glucose absorption. RESEARCH DESIGN AND METHODS Oral glucose tolerance test was performed in mice and rats in the presence and the absence of RELM-beta. The RELM-beta action on glucose transport in rat jejunal sacs, everted rings, and mucosal strips was explored as well as downstream kinases modulating SGLT-1 and GLUT2 glucose transporters. RESULTS Oral glucose tolerance test carried out in rodents showed that oral administration of RELM-beta increased glycemia. Studies in rat jejunal tissue indicated that mucosal RELM-beta promoted absorption of glucose from the gut lumen. RELM-beta had no effect on paracellular mannitol transport, suggesting a transporter-mediated transcellular mechanism. In studies with jejunal mucosa mounted in Ussing chamber, luminal RELM-beta inhibited SGLT-1 activity in line with a diminished SGLT-1 abundance in brush border membranes (BBMs). Further, the potentiating effect of RELM-beta on jejunal glucose uptake was associated with an increased abundance of GLUT2 at BBMs. The effects of RELM-beta were associated with an increased amount of protein kinase C betaII in BBMs and an increased phosphorylation of AMP-activated protein kinase (AMPK). CONCLUSIONS The regulation of SGLT-1 and GLUT2 by RELM-beta expands the role of gut hormones in short-term AMPK/protein kinase C mediated control of energy balance.
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Affiliation(s)
- Rim Belharbi Krimi
- From INSERM, U773, Centre de Recherche Bichat Beaujon CRB3, and Université Paris 7 Denis Diderot, Paris, France
| | - Philippe Letteron
- From INSERM, U773, Centre de Recherche Bichat Beaujon CRB3, and Université Paris 7 Denis Diderot, Paris, France
| | - Pia Chedid
- From INSERM, U773, Centre de Recherche Bichat Beaujon CRB3, and Université Paris 7 Denis Diderot, Paris, France
| | - Corinne Nazaret
- From INSERM, U773, Centre de Recherche Bichat Beaujon CRB3, and Université Paris 7 Denis Diderot, Paris, France
| | - Robert Ducroc
- From INSERM, U773, Centre de Recherche Bichat Beaujon CRB3, and Université Paris 7 Denis Diderot, Paris, France
| | - Jean-Claude Marie
- From INSERM, U773, Centre de Recherche Bichat Beaujon CRB3, and Université Paris 7 Denis Diderot, Paris, France
- Corresponding author: Jean-Claude Marie,
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12
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Hindlet P, Bado A, Kamenicky P, Deloménie C, Bourasset F, Nazaret C, Farinotti R, Buyse M. Reduced intestinal absorption of dipeptides via PepT1 in mice with diet-induced obesity is associated with leptin receptor down-regulation. J Biol Chem 2009; 284:6801-8. [PMID: 19144638 PMCID: PMC2652284 DOI: 10.1074/jbc.m805564200] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2008] [Revised: 12/26/2008] [Indexed: 12/11/2022] Open
Abstract
Leptin is a major determinant of energy homeostasis, acting both centrally and in the gastrointestinal tract. We previously reported that acute leptin treatment enhances the absorption of di- and tripeptides via the proton-dependent PepT1 transporter. In this study, we investigated the long term effect of leptin on PepT1 levels and activity in Caco2 cell monolayers in vitro. We then assessed the significance of the regulation of PepT1 in vivo in a model of diet-induced obesity. We demonstrated that 1) leptin regulated PepT1 at the transcriptional level, via the MAPK pathway, and at the translational level, via ribosomal protein S6 activation, in Caco2 cells and 2) this activation was systematically followed by a time- and concentration-dependent loss of leptin action reflecting desensitization. Deciphering this desensitization, we demonstrated that leptin induced a down-regulation of its own receptor protein and mRNA expression. More importantly, we showed, in mice with diet-induced obesity, that a 4-week hypercaloric diet resulted in a 46% decrease in PepT1-specific transport, because of a 30% decrease in PepT1 protein and a 50% decrease in PepT1 mRNA levels. As shown in Caco2 cells, these changes in PepT1 were supported by a parallel 2-fold decrease in leptin receptor expression in mice. Taken together, these results indicate that during induction of obesity, leptin resistance may also occur peripherally in the gastrointestinal tract, disrupting the absorption of oligopeptides and peptidomimetic drugs.
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Affiliation(s)
- Patrick Hindlet
- Laboratoire de Pharmacie Clinique (UPRES EA2706) and IFR-141, Faculté de Pharmacie, Université Paris-Sud 11, 92296 Châtenay-Malabry, France.
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13
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Wong TP, Debnam ES, Leung PS. Involvement of an enterocyte renin-angiotensin system in the local control of SGLT1-dependent glucose uptake across the rat small intestinal brush border membrane. J Physiol 2007; 584:613-23. [PMID: 17702818 PMCID: PMC2277173 DOI: 10.1113/jphysiol.2007.138578] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
There is increasing evidence that locally produced angiotensin AII (AII) regulates the function of many tissues, but the involvement of enterocyte-derived AII in the control of intestinal transport is unknown. This study examined whether there is a local renin-angiotensin system (RAS) in rat villus enterocytes and assessed the effects of AII on SGLT1-dependent glucose transport across the brush border membrane (BBM). Gene and protein expression of angiotensinogen, ACE, and AT(1) and AT(2) receptors were studied in jejunal and ileal enterocytes using immunocytochemistry, Western blotting and RT-PCR. Mucosal uptake of d-[(14)C]glucose by everted intestinal sleeves before and after addition of AII (0-100 nm) to the mucosal buffer was measured in the presence or absence of the AT(1) receptor antagonist losartan (1 microm). Immunocytochemistry revealed the expression of angiotensinogen, ACE, and AT(1) and AT(2) receptors in enterocytes; immunoreactivity of AT(1) receptor and angiotensinogen proteins was especially pronounced at the BBM. Expression of angiotensinogen and AT(1) and AT(2) receptors, but not ACE, was greater in the ileum than the jejunum. Addition of AII to mucosal buffer inhibited phlorizin-sensitive (SGLT1-dependent) jejunal glucose uptake in a rapid and dose-dependent manner and reduced the expression of SGLT1 at the BBM. Losartan attenuated the inhibitory action of AII on glucose uptake. AII did not affect jejunal uptake of l-leucine. The detection of RAS components at the enterocyte BBM, and the rapid inhibition of SGLT1-dependent glucose uptake by luminal AII suggest that AII secretion exerts autocrine control of intestinal glucose transport.
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MESH Headings
- Angiotensin II/metabolism
- Angiotensin II Type 1 Receptor Blockers/pharmacology
- Angiotensinogen/genetics
- Angiotensinogen/metabolism
- Animals
- Autocrine Communication
- Blotting, Western
- Enterocytes/drug effects
- Enterocytes/metabolism
- Glucose/metabolism
- Ileum/cytology
- Ileum/drug effects
- Ileum/metabolism
- Immunohistochemistry
- In Vitro Techniques
- Jejunum/cytology
- Jejunum/drug effects
- Jejunum/metabolism
- Leucine/metabolism
- Losartan/pharmacology
- Male
- Microvilli/metabolism
- Peptidyl-Dipeptidase A/genetics
- Peptidyl-Dipeptidase A/metabolism
- Polymerase Chain Reaction
- RNA, Messenger/metabolism
- Rats
- Rats, Sprague-Dawley
- Receptor, Angiotensin, Type 1/genetics
- Receptor, Angiotensin, Type 1/metabolism
- Receptor, Angiotensin, Type 2/genetics
- Receptor, Angiotensin, Type 2/metabolism
- Renin-Angiotensin System/drug effects
- Renin-Angiotensin System/genetics
- Sodium-Glucose Transporter 1/metabolism
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Affiliation(s)
- Tung Po Wong
- Department of Physiology, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong, China
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14
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Iñigo C, Patel N, Kellett GL, Barber A, Lostao MP. Luminal leptin inhibits intestinal sugar absorption in vivo. Acta Physiol (Oxf) 2007; 190:303-10. [PMID: 17488247 DOI: 10.1111/j.1748-1716.2007.01707.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
AIM We have previously demonstrated that leptin inhibits galactose absorption in rat intestinal everted rings and that leptin receptors are present in the apical membrane of the enterocytes. This adipocyte-derived hormone is also secreted by gastric mucosal cells and is able to reach the intestinal lumen. The goal of the present study was to prove whether luminal leptin acts on intestinal sugar absorption in vivo both at low (basal state) and high sugar concentration (post-prandial state). METHODS In vivo intestinal sugar absorption in rat was measured with recirculating and single-pass perfusion systems. Sugar disappearance in the perfusate was measured by radioactivity and biochemical methods. Luminal leptin effect on intestinal absorption mediated by sodium-dependent glucose transporter 1 (SGLT1) and glucose transporter 2 (GLUT2) as well as intestinal permeability (mannitol absorption) was determined. RESULTS Luminal leptin inhibited intestinal sugar absorption at low galactose concentrations, which indicates that leptin regulates SGLT1 activity in vivo. The inhibition was reversed in the absence of hormone in the intestinal lumen, suggesting that it was produced by post-translational regulation processes. At high luminal glucose concentrations, leptin also inhibited the phloretin-insensitive component of sugar absorption mediated by SGLT1. There was no significant effect on the apical GLUT2 component of absorption. Leptin did not modify in vivo intestinal permeability determined with (14)C-mannitol. CONCLUSION These observations support the view that gastric leptin exerts a regulatory role on intestinal sugar absorption in the postprandial state by modifying the active component of absorption.
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Affiliation(s)
- C Iñigo
- Department of Physiology and Nutrition, University of Navarra, Pamplona, Spain
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15
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Kimura Y, Turner JR, Braasch DA, Buddington RK. Lumenal adenosine and AMP rapidly increase glucose transport by intact small intestine. Am J Physiol Gastrointest Liver Physiol 2005; 289:G1007-14. [PMID: 16020657 DOI: 10.1152/ajpgi.00085.2005] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Adenosine modulates the intestinal functions of secretion, motility, and immunity, yet little is known about the regulation of nutrient absorption. Therefore, we measured the carrier-mediated uptake of tracer D-[(14)C]glucose (2 microM) by everted sleeves of the mouse intestine after a lumenal exposure to adenosine and a disodium salt of AMP. Rates of glucose uptake by intact tissues increased almost twofold after a 7-min exposure to 5 mM adenosine (a physiological dose). The response was slightly more pronounced for AMP and could be induced by forskolin. The response to adenosine was blocked by theophylline and the A(2) receptor antagonist 3,7-dimethyl-1-proparglyxanthine but not by the A(1) receptor antagonist 8-phenyltheophylline. Glucose uptake by control and AMP-stimulated tissues was inhibited by phloridzin, implying that sodium-dependent glucose transporter 1 (SGLT1) is the responsive transporter, but the involvement of glucose transporter 2 (GLUT2) cannot be excluded. Of clinical relevance, AMP accelerated the systemic availability of 3-O-methylglucose after an oral administration to mice. Our results indicate that adenosine causes a rapid increase in carrier-mediated glucose uptake that is of clinical relevance and acts via receptors linked to a signaling pathway that involves intracellular cAMP production.
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Affiliation(s)
- Yasuhiro Kimura
- Dept. of Biological Sciences, Mississippi State University, MS 39762, USA
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16
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Robin MA, Sauvage I, Grandperret T, Descatoire V, Pessayre D, Fromenty B. Ethanol increases mitochondrial cytochrome P450 2E1 in mouse liver and rat hepatocytes. FEBS Lett 2005; 579:6895-902. [PMID: 16337197 DOI: 10.1016/j.febslet.2005.11.029] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2005] [Revised: 11/09/2005] [Accepted: 11/11/2005] [Indexed: 12/15/2022]
Abstract
Enhanced hepatic levels of cytochrome P450 2E1 (CYP2E1) may play a key role in the pathogenesis of some liver diseases because CYP2E1 represents a significant source of reactive oxygen species. Although a large fraction of CYP2E1 is located in the endoplasmic reticulum, CYP2E1 is also present in mitochondria. In this study, we asked whether ethanol, a known inducer of microsomal CYP2E1, could also increase CYP2E1 within mitochondria. Our findings indicated that ethanol increased microsomal and mitochondrial CYP2E1 in cultured rat hepatocytes and in the liver of lean mice. This was associated with decreased levels of glutathione, possibly reflecting increased oxidative stress. In contrast, in leptin-deficient obese mice, ethanol administration did not increase mitochondrial CYP2E1, nor it depleted mitochondrial glutathione, suggesting that leptin deficiency hampers mitochondrial targeting of CYP2E1. Thus, ethanol intoxication increases CYP2E1 not only in the endoplasmic reticulum but also in mitochondria, thus favouring oxidative stress in these compartments.
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MESH Headings
- Animals
- Blotting, Western
- Cells, Cultured
- Cytochrome P-450 CYP2E1/genetics
- Cytochrome P-450 CYP2E1/metabolism
- Diabetes Mellitus, Experimental/enzymology
- Ethanol/toxicity
- Hepatocytes/cytology
- Hepatocytes/drug effects
- Hepatocytes/enzymology
- Liver/drug effects
- Liver/enzymology
- Male
- Mice
- Mice, Inbred C57BL
- Mice, Inbred ICR
- Mice, Obese
- Microsomes, Liver/drug effects
- Microsomes, Liver/enzymology
- Mitochondria, Liver/drug effects
- Mitochondria, Liver/enzymology
- NAD/metabolism
- Rats
- Rats, Sprague-Dawley
- Subcellular Fractions/chemistry
- Subcellular Fractions/drug effects
- Time Factors
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Affiliation(s)
- Marie-Anne Robin
- INSERM Unité 481, Faculté de Médecine Xavier Bichat, 16 rue Henri Huchard, 75018 Paris, France.
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17
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Fernández de Arcaya I, Lostao MP, Martínez A, Berjón A, Barber A. Effect of adrenomedullin and proadrenomedullin N-terminal 20 peptide on sugar transport in the rat intestine. ACTA ACUST UNITED AC 2005; 129:147-54. [PMID: 15927710 DOI: 10.1016/j.regpep.2005.02.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2004] [Accepted: 02/04/2005] [Indexed: 11/28/2022]
Abstract
Previous studies have shown immunostaining of adrenomedullin (AM) and proadrenomedullin N-terminal 20 peptide (PAMP) throughout the gastrointestinal tract. Based on these data, we decided to investigate the effect of these peptides on intestinal sugar absorption using everted rings from Wistar rat intestine. PAMP increases alpha-methylglucoside (MG) uptake at concentrations ranging from 10(-12) to 10(-7) M. AM shows a dual effect inhibiting sugar absorption at low concentrations (10(-12) to 10(-11) M) and increasing MG uptake at higher concentrations (10(-8) to 10(-6) M). In all cases, the effect is phloridzin-sensitive, indicating that the peptides alter SGLT1 function without modifying the non-mediated component of absorption. The enhancing effect of 10(-8) M AM and PAMP seems to be mediated by elevation of cAMP and is accompanied by an increase on SGLT1 expression in the brush-border membrane of the enterocytes. The inhibitory effect of 10(-12) M AM could be mediated by either cAMP reduction or, more probably, by other second messenger able to inhibit sugar absorption. PKC is not involved in the action of either AM or PAMP. These results demonstrate that both peptides play a role in the regulation of the active transport of sugars in the intestine.
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Affiliation(s)
- I Fernández de Arcaya
- Departamento de Fisiología y Nutrición, Universidad de Navarra, 31080 Pamplona, Spain
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18
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Ducroc R, Guilmeau S, Akasbi K, Devaud H, Buyse M, Bado A. Luminal leptin induces rapid inhibition of active intestinal absorption of glucose mediated by sodium-glucose cotransporter 1. Diabetes 2005; 54:348-54. [PMID: 15677491 DOI: 10.2337/diabetes.54.2.348] [Citation(s) in RCA: 93] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The effect of leptin on glucose transport was studied in rat jejunal mucosa in Ussing chambers. Leptin was added in the luminal or the serosal compartment before the tissues were challenged with 1, 10, or 50 mmol/l glucose. In response to 10 mmol/l glucose, the increase in short-circuit current (DeltaIsc) reached 26.8 +/- 2.1 microA/cm(2). Luminal addition of leptin dramatically decreased glucose-induced Isc (90.5% for 10 nmol/l leptin). Inhibition was maximal after 5 min and dose dependent (IC(50) = 0.13 nM). Western blot analysis showed that rapid inhibition of glucose-induced Isc by leptin was associated with a parallel decrease in the abundance of sodium-glucose transporter-1 in brush border membranes. Inhibition by luminal leptin of DeltaIsc was prevented by inhibitor of conventional protein kinase C isoforms. Serosal addition of leptin did not decrease glucose-induced Isc within 5 min and reached maximum after 10 min. The effect of leptin from serosal side was blocked by cholecystokinin (CCK) receptor-2 receptor antagonist YM022. Altogether, these data demonstrate that luminal leptin induces rapid inhibition of glucose entry into enterocyte. The slower action of leptin on the serosal side of mucosa seems indirect and is likely mediated by endogenous CCK. They demonstrate that gut leptin is a major regulator of rapid intestinal glucose transport.
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Affiliation(s)
- Robert Ducroc
- Institut National de la Santé et de la Recherche Médicale Unité 410, IFR02 Claude Bernard, Faculté de Médecine Xavier Bichat, Paris, France.
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19
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Iñigo C, Barber A, Lostao MP. Leptin effect on intestinal galactose absorption in ob/ob and db/db mice. J Physiol Biochem 2004; 60:93-7. [PMID: 15457927 DOI: 10.1007/bf03168445] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Our previous works demonstrated that leptin inhibits galactose absorption in rat and mice intestinal rings. Here, we have studied the effect of exogenous leptin on intestinal galactose absorption in the genetically obese db/db (leptin-resistant) and ob/ob (leptin-deficient) mice. Assays were performed by incubating the intestinal rings in saline solution containing 5 mM galactose in the absence or presence of 0.2 or 0.4 nM leptin. Basal galactose uptake was similar in the wild-type and the two obese groups. Contrarily to what happens in wild-type mice, leptin increased galactose uptake in db/db animals; since these mice lack the functional long leptin receptor, the measured effect may be due to the short receptor signaling. In the ob/ob mice, 0.2 nM leptin also increased galactose absorption whereas 0.4 nM did not have any effect, suggesting that in the genetically obese animals the expression and regulation of leptin receptors may be altered.
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Affiliation(s)
- C Iñigo
- Department of Physiology and Nutrition, University of Navarra, Pamplona 31008, Spain
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