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Nakamura C, Ishizuka N, Yokoyama K, Yazaki Y, Tatsumi F, Ikumi N, Hempstock W, Ikari A, Yoshino Y, Hayashi H. Regulatory mechanisms of glucose absorption in the mouse proximal small intestine during fasting and feeding. Sci Rep 2023; 13:10838. [PMID: 37407613 DOI: 10.1038/s41598-023-38024-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Accepted: 06/30/2023] [Indexed: 07/07/2023] Open
Abstract
Fasting is known to alter the function of various organs and the mechanisms of glucose metabolism, which affect health outcomes and slow aging. However, it remains unclear how fasting and feeding affects glucose absorption function in the small intestine. We studied the effects of the fasting and feeding on glucose-induced short-circuit current (Isc) in vitro using an Ussing chamber technique. Glucose-induced Isc by SGLT1 was observed in the ileum, but little or no Isc was observed in the jejunum in ad libitum-fed mice. However, in mice fasted for 24-48 h, in addition to the ileum, robust glucose-induced Isc was observed over time in the jejunum. The expression of SGLT1 in the brush border membranes was significantly decreased in the jejunum under fed conditions compared to 48 h fasting, as analyzed by western blotting. Additionally, when mice were fed a 60% high glucose diet for 3 days, the increase in glucose-induced Isc was observed only in the ileum, and totally suppressed in the jejunum. An increase in Na+ permeability between epithelial cells was concomitantly observed in the jejunum of fasted mice. Transepithelial glucose flux was assessed using a non-metabolizable glucose analog, 14C-methyl α-D-glucopyranoside glucose (MGP). Regardless of whether fed or fasted, no glucose diffusion mechanism was observed. Fasting increased the SGLT1-mediated MGP flux in the jejunum. In conclusion, segment-dependent up- and down-regulation mechanisms during fasting and feeding are important for efficient glucose absorption once the fast is broken. Additionally, these mechanisms may play a crucial role in the small intestine's ability to autoregulate glucose absorption, preventing acute hyperglycemia when large amounts of glucose are ingested.
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Affiliation(s)
- Chisato Nakamura
- Laboratory of Physiology, Graduate School of Nutritional and Environmental Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka, 422-8526, Japan
| | - Noriko Ishizuka
- Laboratory of Physiology, Graduate School of Nutritional and Environmental Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka, 422-8526, Japan
| | - Kanako Yokoyama
- Laboratory of Physiology, Graduate School of Nutritional and Environmental Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka, 422-8526, Japan
| | - Yuyu Yazaki
- Laboratory of Physiology, Graduate School of Nutritional and Environmental Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka, 422-8526, Japan
| | - Fumiya Tatsumi
- Laboratory of Physiology, Graduate School of Nutritional and Environmental Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka, 422-8526, Japan
| | - Naotaka Ikumi
- Laboratory of Physiology, Graduate School of Nutritional and Environmental Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka, 422-8526, Japan
| | - Wendy Hempstock
- Laboratory of Physiology, Graduate School of Nutritional and Environmental Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka, 422-8526, Japan
- Department of Nursing, School of Nursing, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka, 422-8526, Japan
| | - Akira Ikari
- Laboratory of Biochemistry, Gifu Pharmaceutical University, Gifu, 501-1196, Japan
| | - Yuta Yoshino
- Laboratory of Biochemistry, Gifu Pharmaceutical University, Gifu, 501-1196, Japan
| | - Hisayoshi Hayashi
- Laboratory of Physiology, Graduate School of Nutritional and Environmental Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka, 422-8526, Japan.
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Mechanisms of Glucose Absorption in the Small Intestine in Health and Metabolic Diseases and Their Role in Appetite Regulation. Nutrients 2021; 13:nu13072474. [PMID: 34371983 PMCID: PMC8308647 DOI: 10.3390/nu13072474] [Citation(s) in RCA: 39] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Revised: 07/13/2021] [Accepted: 07/16/2021] [Indexed: 12/11/2022] Open
Abstract
The worldwide prevalence of metabolic diseases such as obesity, metabolic syndrome and type 2 diabetes shows an upward trend in recent decades. A characteristic feature of these diseases is hyperglycemia which can be associated with hyperphagia. Absorption of glucose in the small intestine physiologically contributes to the regulation of blood glucose levels, and hence, appears as a putative target for treatment of hyperglycemia. In fact, recent progress in understanding the molecular and cellular mechanisms of glucose absorption in the gut and its reabsorption in the kidney helped to develop a new strategy of diabetes treatment. Changes in blood glucose levels are also involved in regulation of appetite, suggesting that glucose absorption may be relevant to hyperphagia in metabolic diseases. In this review we discuss the mechanisms of glucose absorption in the small intestine in physiological conditions and their alterations in metabolic diseases as well as their relevance to the regulation of appetite. The key role of SGLT1 transporter in intestinal glucose absorption in both physiological conditions and in diabetes was clearly established. We conclude that although inhibition of small intestinal glucose absorption represents a valuable target for the treatment of hyperglycemia, it is not always suitable for the treatment of hyperphagia. In fact, independent regulation of glucose absorption and appetite requires a more complex approach for the treatment of metabolic diseases.
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Soták M, Casselbrant A, Rath E, Zietek T, Strömstedt M, Adingupu DD, Karlsson D, Fritsch Fredin M, Ergang P, Pácha J, Batorsky A, Alpers CE, Börgeson E, Hansen PBL, Ericsson A, Björnson Granqvist A, Wallenius V, Fändriks L, Unwin RJ. Intestinal sodium/glucose cotransporter 3 expression is epithelial and downregulated in obesity. Life Sci 2020; 267:118974. [PMID: 33385407 DOI: 10.1016/j.lfs.2020.118974] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Revised: 12/11/2020] [Accepted: 12/20/2020] [Indexed: 12/12/2022]
Abstract
AIM We aimed to determine whether the sodium/glucose cotransporter family member SGLT3, a proposed glucose sensor, is expressed in the intestine and/or kidney, and if its expression is altered in mouse models of obesity and in humans before and after weight-loss surgery. MAIN METHODS We used in-situ hybridization and quantitative PCR to determine whether the Sglt3 isoforms 3a and 3b were expressed in the intestine and kidney of C57, leptin-deficient ob/ob, and diabetic BTBR ob/ob mice. Western blotting and immunohistochemistry were also used to assess SGLT3 protein levels in jejunal biopsies from obese patients before and after weight-loss Roux-en-Y gastric bypass surgery (RYGB), and in lean healthy controls. KEY FINDINGS Sglt3a/3b mRNA was detected in the small intestine (duodenum, jejunum and ileum), but not in the large intestine or kidneys of mice. Both isoforms were detected in epithelial cells (confirmed using intestinal organoids). Expression of Sglt3a/3b mRNA in duodenum and jejunum was significantly lower in ob/ob and BTBR ob/ob mice than in normal-weight littermates. Jejunal SGLT3 protein levels in aged obese patients before RYGB were lower than in lean individuals, but substantially upregulated 6 months post-RYGB. SIGNIFICANCE Our study shows that Sglt3a/3b is expressed primarily in epithelial cells of the small intestine in mice. Furthermore, we observed an association between intestinal mRNA Sglt3a/3b expression and obesity in mice, and between jejunal SGLT3 protein levels and obesity in humans. Further studies are required to determine the possible role of SGLT3 in obesity.
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Affiliation(s)
- Matúš Soták
- Bioscience, Research and Early Development, Cardiovascular, Renal and Metabolism, BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden; Department of Molecular and Clinical Medicine, Wallenberg Laboratory, Institute of Medicine, University of Gothenburg, Sweden; Wallenberg Centre for Molecular and Translational Medicine, University of Gothenburg, Sweden.
| | - Anna Casselbrant
- Department of Surgery, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Eva Rath
- Chair of Nutrition and Immunology, Technische Universität München, Freising, Germany
| | - Tamara Zietek
- Department of Nutritional Physiology, Technische Universität München, Freising, Germany
| | - Maria Strömstedt
- Bioscience, Research and Early Development, Cardiovascular, Renal and Metabolism, BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden
| | - Damilola D Adingupu
- Bioscience, Research and Early Development, Cardiovascular, Renal and Metabolism, BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden
| | - Daniel Karlsson
- Bioscience, Research and Early Development, Cardiovascular, Renal and Metabolism, BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden
| | - Maria Fritsch Fredin
- Bioscience, Research and Early Development, Cardiovascular, Renal and Metabolism, BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden
| | - Peter Ergang
- Institute of Physiology, Czech Academy of Sciences, Prague, Czech Republic
| | - Jiří Pácha
- Institute of Physiology, Czech Academy of Sciences, Prague, Czech Republic
| | - Anna Batorsky
- Department of Pathology, University of Washington School of Medicine, Seattle, USA
| | - Charles E Alpers
- Department of Pathology, University of Washington School of Medicine, Seattle, USA
| | - Emma Börgeson
- Department of Molecular and Clinical Medicine, Wallenberg Laboratory, Institute of Medicine, University of Gothenburg, Sweden; Wallenberg Centre for Molecular and Translational Medicine, University of Gothenburg, Sweden; Department of Clinical Physiology, Sahlgrenska University Hospital, Sweden
| | - Pernille B L Hansen
- Bioscience, Research and Early Development, Cardiovascular, Renal and Metabolism, BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden; Wallenberg Centre for Molecular and Translational Medicine, University of Gothenburg, Sweden
| | - Anette Ericsson
- Bioscience, Research and Early Development, Cardiovascular, Renal and Metabolism, BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden
| | - Anna Björnson Granqvist
- Bioscience, Research and Early Development, Cardiovascular, Renal and Metabolism, BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden
| | - Ville Wallenius
- Department of Surgery, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Lars Fändriks
- Department of Surgery, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Robert J Unwin
- Bioscience, Research and Early Development, Cardiovascular, Renal and Metabolism, BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden; Department of Renal Medicine, Division of Medicine, University College London, UK
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Oparija-Rogenmozere L, Rajendran A, Poncet N, Camargo SMR, Verrey F. Phosphorylation of mouse intestinal basolateral amino acid uniporter LAT4 is controlled by food-entrained diurnal rhythm and dietary proteins. PLoS One 2020; 15:e0233863. [PMID: 32470053 PMCID: PMC7259769 DOI: 10.1371/journal.pone.0233863] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Accepted: 05/13/2020] [Indexed: 12/29/2022] Open
Abstract
Adaptive regulation of epithelial transporters to nutrient intake is essential to decrease energy costs of their synthesis and maintenance, however such regulation is understudied. Previously we demonstrated that the transport function of the basolateral amino acid uniporter LAT4 (Slc43a2) is increased by dephosphorylation of serine 274 (S274) and nearly abolished by dephosphorylation of serine 297 (S297) when expressed in Xenopus oocytes. Phosphorylation changes in the jejunum of food-entrained mice suggested an increase in LAT4 transport function during food expectation. Thus, we investigated further how phosphorylation, expression and localization of mouse intestinal LAT4 respond to food-entrained diurnal rhythm and dietary protein content. In mice entrained with 18% protein diet, LAT4 mRNA was not submitted to diurnal regulation, unlike mRNAs of luminal symporters and antiporters. Only in duodenum, LAT4 protein expression increased during food intake. Concurrently, S274 phosphorylation was decreased in all three small intestinal segments, whereas S297 phosphorylation was increased only in jejunum. Interestingly, during food intake, S274 phosphorylation was nearly absent in ileum and accompanied by strong phosphorylation of mTORC1 target S6. Entraining mice with 8% protein diet provoked a shift in jejunal LAT4 localization from the cell surface to intracellular stores and increased S274 phosphorylation in both jejunum and ileum during food anticipation, suggesting decreased transport function. In contrast, 40% dietary protein content led to increased LAT4 expression in jejunum and its internalization in ileum. Ex vivo treatments of isolated intestinal villi fraction demonstrated that S274 phosphorylation was stimulated by protein kinase A. Rapamycin-sensitive insulin treatment and amino acids increased S297 phosphorylation, suggesting that the response to food intake might be regulated via the insulin-mTORC1 pathway. Ghrelin, an oscillating orexigenic hormone, did not affect phosphorylation of intestinal LAT4. Overall, we show that phosphorylation, expression and localization of intestinal mouse LAT4 responds to diurnal and dietary stimuli in location-specific manner.
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Affiliation(s)
- Lalita Oparija-Rogenmozere
- Institute of Physiology and Zurich Center for Integrative Human Physiology (ZIHP), University of Zurich, Zurich, Switzerland
| | - Anuradha Rajendran
- Institute of Physiology and Zurich Center for Integrative Human Physiology (ZIHP), University of Zurich, Zurich, Switzerland
| | - Nadège Poncet
- Institute of Physiology and Zurich Center for Integrative Human Physiology (ZIHP), University of Zurich, Zurich, Switzerland
| | - Simone M R Camargo
- Institute of Physiology and Zurich Center for Integrative Human Physiology (ZIHP), University of Zurich, Zurich, Switzerland
| | - François Verrey
- Institute of Physiology and Zurich Center for Integrative Human Physiology (ZIHP), University of Zurich, Zurich, Switzerland.,NCCR Kidney.CH, Zurich, Switzerland
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Daily expression of sodium-dependent glucose cotransporter-1 protein in jejunum during rat ontogeny. ACTA ACUST UNITED AC 2019; 5:290-296. [PMID: 31528732 PMCID: PMC6737494 DOI: 10.1016/j.aninu.2019.04.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2018] [Revised: 01/17/2019] [Accepted: 04/02/2019] [Indexed: 11/21/2022]
Abstract
It is widely known that intestinal capacities such as the enzymatic hydrolysis of carbohydrates, lipids and proteins, and the subsequent absorption of the hydrolyzed products, are evolutionary matched to dietary loads and feeding behaviors. In this study, we demonstrate that the protein expression of apically located sodium-dependent glucose cotransporter-1 (SGLT-1) throughout rat ontogeny is daily adjusted to afford glucose uptake when the load of this metabolically essential monosaccharide in the intestinal lumen is maximum. The jejunal expression of SGLT-1 protein in 14 one-day-old suckling pups was found to increase at dark and early light phase (P < 0.05), when they have a better access to mother milk. In weaning 21-d-old and juvenile 28-d-old rats, the cotransporter expression was high throughout the entire day (P < 0.05). Finally, adult 90-d-old rats showed a well-developed circadian rhythm for SGLT-1 protein (P < 0.05), whose expression increased at late light and dark phase when the highest intestinal glucose load was achieved. To our knowledge, these results are the first reporting the daily profile of SGLT-1 expression during rat early developmental stage and may contribute to understand the biological significance of a well-established molecular capacity to deal with the crucial increase of glucose load in the diet during the weaning process.
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Khachab M, Kanaan A, Awad D, Deeba E, Osman S, Nassar CF. Colectomy induces an aldosterone-mediated increase in jejunal glucose uptake in rats. Life Sci 2017; 174:43-49. [PMID: 28254387 DOI: 10.1016/j.lfs.2017.02.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2016] [Revised: 02/15/2017] [Accepted: 02/24/2017] [Indexed: 11/25/2022]
Abstract
AIMS The main function of the colon is water and electrolyte absorption. Total colectomy eliminates this colonic function and may alter the absorptive capacity of the small intestine for nutrients. This study examines the effect of total colectomy on jejunal glucose absorption and investigates the potential role of aldosterone in mediating the alterations in glucose uptake post-colectomy using the aldosterone antagonist spironolactone. MAIN METHODS Total colectomy with ileo-rectal anastomosis was performed on anesthetized rats. Sham rats were identically handled without colon resection. Two days post-surgery, groups of colectomized rats were injected with either a daily subcutaneous dose of spironolactone or sesame oil for 12days. Body weight changes and food and water intake were measured in all experimental groups. Glucose absorption was measured by in-vivo single pass perfusion in the rat jejunum of control, sham, colectomized, colectomized with spironolactone, and colectomized with sesame oil treatment. Na/K ATPase, SGK1, SGLT1 and GLUT2 expressions were determined in jejunal mucosa in control, colectomized and colectomized/spironolactone injected rats by Western blot analysis. Histological assessment was performed on jejunal sections in control and colectomized groups. KEY FINDINGS Glucose absorption significantly increased in colectomized rats with an observed increase in Na/K ATPase and SGK1 expression. No significant expression change in SGLT1 and GLUT2 was detected in the jejunum in colectomized rats. Spironolactone, however, significantly decreased the glucose uptake post-colectomy and normalized Na/K ATPase and SGK1 expression. SIGNIFICANCE Our results suggest that jejunal glucose uptake increases post-colectomy as a possible consequence of an aldosterone-mediated function.
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Affiliation(s)
- Maha Khachab
- Department of Biomedical Sciences, Faculty of Medicine and Medical Sciences, University of Balamand, El-Kurah, Lebanon.
| | - Amjad Kanaan
- Department of Biomedical Sciences, Faculty of Medicine and Medical Sciences, University of Balamand, El-Kurah, Lebanon
| | - Dania Awad
- Faculty of Health Sciences, Lebanese University, Tripoli, Lebanon
| | - Elie Deeba
- Department of Biomedical Sciences, Faculty of Medicine and Medical Sciences, University of Balamand, El-Kurah, Lebanon
| | - Samira Osman
- Department of Biomedical Sciences, Faculty of Medicine and Medical Sciences, University of Balamand, El-Kurah, Lebanon
| | - Camille F Nassar
- Department of Biomedical Sciences, Faculty of Medicine and Medical Sciences, University of Balamand, El-Kurah, Lebanon
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Lehmann A, Hornby PJ. Intestinal SGLT1 in metabolic health and disease. Am J Physiol Gastrointest Liver Physiol 2016; 310:G887-98. [PMID: 27012770 DOI: 10.1152/ajpgi.00068.2016] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/15/2016] [Accepted: 03/21/2016] [Indexed: 01/31/2023]
Abstract
The Na(+)-glucose cotransporter 1 (SGLT1/SLC5A1) is predominantly expressed in the small intestine. It transports glucose and galactose across the apical membrane in a process driven by a Na(+) gradient created by Na(+)-K(+)-ATPase. SGLT2 is the major form found in the kidney, and SGLT2-selective inhibitors are a new class of treatment for type 2 diabetes mellitus (T2DM). Recent data from patients treated with dual SGLT1/2 inhibitors or SGLT2-selective drugs such as canagliflozin (SGLT1 IC50 = 663 nM) warrant evaluation of SGLT1 inhibition for T2DM. SGLT1 activity is highly dynamic, with modulation by multiple mechanisms to ensure maximal uptake of carbohydrates (CHOs). Intestinal SGLT1 inhibition lowers and delays the glucose excursion following CHO ingestion and augments glucagon-like peptide-1 (GLP-1) and peptide YY (PYY) secretion. The latter is likely due to increased glucose exposure of the colonic microbiota and formation of metabolites such as L cell secretagogues. GLP-1 and PYY secretion suppresses food intake, enhances the ileal brake, and has an incretin effect. An increase in colonic microbial production of propionate could contribute to intestinal gluconeogenesis and mediate positive metabolic effects. On the other hand, a threshold of SGLT1 inhibition that could lead to gastrointestinal intolerability is unclear. Altered Na(+) homeostasis and increased colonic CHO may result in diarrhea and adverse gastrointestinal effects. This review considers the potential mechanisms contributing to positive metabolic and negative intestinal effects. Compounds that inhibit SGLT1 must balance the modulation of these mechanisms to achieve therapeutic efficacy for metabolic diseases.
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Affiliation(s)
- Anders Lehmann
- Division of Endocrinology, Department of Physiology, Institute of Neuroscience and Physiology, Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden; and
| | - Pamela J Hornby
- Cardiovascular and Metabolic Disease, Janssen Research and Development, LLC, Spring House, Pennsylvania
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Nguyen NQ, Debreceni TL, Bambrick JE, Chia B, Deane AM, Wittert G, Rayner CK, Horowitz M, Young RL. Upregulation of intestinal glucose transporters after Roux-en-Y gastric bypass to prevent carbohydrate malabsorption. Obesity (Silver Spring) 2014; 22:2164-71. [PMID: 24990218 DOI: 10.1002/oby.20829] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/06/2014] [Revised: 05/23/2014] [Accepted: 06/13/2014] [Indexed: 02/05/2023]
Abstract
OBJECTIVE 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. METHODS 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. RESULTS 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). CONCLUSIONS 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.
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Affiliation(s)
- Nam Q Nguyen
- Department of Gastroenterology and Hepatology, Royal Adelaide Hospital, Adelaide, South Australia, 5000, Australia; Discipline of Medicine, University of Adelaide, Royal Adelaide Hospital, Adelaide, South Australia, 5000, Australia
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Trung VN, Yamamoto H, Murata S, Kuwahara A, Tani T. Ileal glucose infusion leads to increased insulin sensitivity and decreased blood glucose levels in Wistar rats. J INVEST SURG 2014; 27:332-7. [PMID: 24960307 DOI: 10.3109/08941939.2014.929764] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
PURPOSE OF THE STUDY Rerouting of nutrients and/or increasing nutrient delivery to the small intestine after Roux-en-Y gastric bypass may have important potential as a diabetes treatment modality. However, it is still important question which part of the gastrointestinal tract is the most important for control of glycemia. The aim of this study was to investigate the role of different segments of the gastrointestinal tract on glucose metabolism in the physiological state. MATERIALS AND METHODS Forty 12-week-old male Wistar rats were divided into the following four groups of 10 animals each: the gastrostomy group, the duodenostomy group, the jejunostomy group, and the ileostomy group. All rats were subjected to a glucose tolerance test by infusion of glucose via the surgically inserted tubes in the stomach (gastrostomy), in the duodenum (duodenostomy), in the jejunum (jejunostomy), or in the ileum (ileostomy). Plasma glucagon-like peptide-17-36 (GLP-17-36) and insulin levels during the glucose tolerance test were assayed and Matsuda index was calculated. RESULTS Ileostomy rats exhibited significantly lower glycemic excursions compared with gastrostomy, duodenostomy, and jejunostomy rats. Insulin and GLP-1 levels during the glucose tolerance test were significantly higher in duodenostomy and jejunostomy rats than in gastrostomy and ileostomy rats. Matsuda index was significantly higher in ileostomy rats than in duodenostomy and jejunostomy rats. CONCLUSION Ileal glucose infusion leads to increased insulin sensitivity, further decreasing blood glucose levels.
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Affiliation(s)
- Vo Nguyen Trung
- 1Department of Surgery, Shiga University of Medical Science, Seta-Tsukinowa-cho, Otsu, Shiga, Japan
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10
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Duodenal-Jejunal Bypass Improves Glycemia and Decreases SGLT1-Mediated Glucose Absorption in Rats With Streptozotocin-Induced Type 2 Diabetes. Ann Surg 2013; 258:89-97. [DOI: 10.1097/sla.0b013e3182890311] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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11
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Bhutta HY, Deelman TE, Ashley SW, Rhoads DB, Tavakkoli A. Disrupted circadian rhythmicity of the intestinal glucose transporter SGLT1 in Zucker diabetic fatty rats. Dig Dis Sci 2013; 58:1537-45. [PMID: 23633155 PMCID: PMC3691300 DOI: 10.1007/s10620-013-2669-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/25/2012] [Accepted: 03/27/2013] [Indexed: 12/09/2022]
Abstract
BACKGROUND 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. 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 = 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. RESULTS 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. CONCLUSIONS 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.
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Affiliation(s)
- Hina Y. Bhutta
- Department of Surgery, Brigham and Women’s Hospital, 75 Francis Street, Boston, MA 02115
- Department of Investigative Medicine, Imperial College, Exhibition Road, London, UK SW7 2AZ
- Harvard Medical School, 25 Shattuck Street, Boston, MA 02115
| | - Tara E. Deelman
- Department of Surgery, Brigham and Women’s Hospital, 75 Francis Street, Boston, MA 02115
- Harvard Medical School, 25 Shattuck Street, Boston, MA 02115
| | - Stanley W. Ashley
- Department of Surgery, Brigham and Women’s Hospital, 75 Francis Street, Boston, MA 02115
- Harvard Medical School, 25 Shattuck Street, Boston, MA 02115
| | - David B. Rhoads
- Pediatric Endocrine Unit, Mass General Hospital for Children, 55 Fruit Street, Boston, MA 02114
- Harvard Medical School, 25 Shattuck Street, Boston, MA 02115
| | - Ali Tavakkoli
- Department of Surgery, Brigham and Women’s Hospital, 75 Francis Street, Boston, MA 02115
- Harvard Medical School, 25 Shattuck Street, Boston, MA 02115
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Pácha J, Sumová A. Circadian regulation of epithelial functions in the intestine. Acta Physiol (Oxf) 2013; 208:11-24. [PMID: 23461998 DOI: 10.1111/apha.12090] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2012] [Revised: 02/21/2013] [Accepted: 02/21/2013] [Indexed: 12/24/2022]
Abstract
Many physiological functions exhibit a diurnal rhythmicity that is influenced by biological clocks and feeding rhythms. In this review, we discuss the growing evidence showing the important role of circadian rhythms in regulating intestinal mucosa. First, we introduce the molecular timing system and the interrelationship between the master biological clock in the suprachiasmatic nuclei of the brain and the peripheral intestinal clock and provide evidence that the intestinal clock is entrained with the external environment. Second, we review the circadian rhythmicity of enterocyte proliferation and the largely unknown regulatory mechanisms behind these rhythms. Finally, we focus on the circadian clock control of food processing that functions by regulating the expression of digestive enzymes and intestinal nutrient and salt transporters. The concepts to be discussed highlight the ability of the intestinal epithelium to utilize self-sustained clock signals together with signals associated with changes in the cellular environment and to use endogenous temporal control of the gastrointestinal functions to meet varying physiological and pathophysiological demands. The fact that internal de-synchronizations within the body, such as those that occur in shift workers or with changes in food intake behaviour, are often associated with malfunctions of the gastrointestinal tract indicates that more information about the connections between the circadian clock and intestinal mucosa/transporting enterocytes could provide clues for future therapies.
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Affiliation(s)
- J. Pácha
- Institute of Physiology; Academy of Sciences of the Czech Republic; Prague; Czech Republic
| | - A. Sumová
- Institute of Physiology; Academy of Sciences of the Czech Republic; Prague; Czech Republic
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Stearns AT, Balakrishnan A, Radmanesh A, Ashley SW, Rhoads DB, Tavakkolizadeh A. Relative contributions of afferent vagal fibers to resistance to diet-induced obesity. Dig Dis Sci 2012; 57:1281-90. [PMID: 22138962 PMCID: PMC4111149 DOI: 10.1007/s10620-011-1968-4] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/12/2010] [Accepted: 11/02/2011] [Indexed: 12/09/2022]
Abstract
BACKGROUND We previously demonstrated vagal neural pathways, specifically subdiaphragmatic afferent fibers, regulate expression of the intestinal sodium-glucose cotransporter SGLT1, the intestinal transporter responsible for absorption of dietary glucose. We hypothesized targeting this pathway could be a novel therapy for obesity. We therefore tested the impact of disrupting vagal signaling by total vagotomy or selective vagal de-afferentation on weight gain and fat content in diet-induced obese rats. METHODS Male Sprague-Dawley rats (n = 5-8) underwent truncal vagotomy, selective vagal de-afferentation with capsaicin, or sham procedure. Animals were maintained for 11 months on a high-caloric Western diet. Abdominal visceral fat content was assessed by magnetic resonance imaging together with weight of fat pads at harvest. Glucose homeostasis was assessed by fasting blood glucose and HbA1C. Jejunal SGLT1 gene expression was assessed by qPCR and immunoblotting and function by glucose uptake in everted jejunal sleeves. RESULTS At 11-months, vagotomized rats weighed 19% less (P = 0.003) and de-afferented rats 7% less (P = 0.19) than shams. Vagotomized and de-afferented animals had 52% (P < 0.0001) and 18% reduction (P = 0.039) in visceral abdominal fat, respectively. There were no changes in blood glucose or glycemic indexes. SGLT1 mRNA, protein and function were unchanged across all cohorts at 11-months postoperatively. CONCLUSIONS Truncal vagotomy led to significant reductions in both diet-induced weight gain and visceral abdominal fat deposition. Vagal de-afferentation led to a more modest, but clinically and statistically significant, reduction in visceral abdominal fat. As increased visceral abdominal fat is associated with excess morbidity and mortality, vagal de-afferentation may be a useful adjunct in bariatric surgery.
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Affiliation(s)
- A. T. Stearns
- Department of Surgery, Brigham and Women’s Hospital, Harvard Medical School, 75 Francis Street, Boston, MA 02115, USA. Department of Physiology, Anatomy and Genetics, University of Oxford, South Parks Road, Oxford, UK
| | - A. Balakrishnan
- Department of Surgery, Brigham and Women’s Hospital, Harvard Medical School, 75 Francis Street, Boston, MA 02115, USA. Division of Gastroenterology, School of Clinical Sciences, University of Liverpool, Crown Street, Liverpool L69 3GE, UK
| | - A. Radmanesh
- Department of Radiology, Brigham and Women’s Hospital, Harvard Medical School, 75 Francis Street, Boston, MA 02115, USA
| | - S. W. Ashley
- Department of Surgery, Brigham and Women’s Hospital, Harvard Medical School, 75 Francis Street, Boston, MA 02115, USA
| | - D. B. Rhoads
- Pediatric Endocrine Unit, MassGeneral Hospital for Children, Harvard Medical School, Fruit Street, Boston, MA 02114, USA
| | - A. Tavakkolizadeh
- Department of Surgery, Brigham and Women’s Hospital, Harvard Medical School, 75 Francis Street, Boston, MA 02115, USA
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14
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A. Gruzdkov A, V. Gromova L, M. Grefner N, Yu. Komissarchik Y. Kinetics and mechanisms of glucose absorption in the rat small intestine under physiological conditions. ACTA ACUST UNITED AC 2012. [DOI: 10.4236/jbpc.2012.32021] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Hayashi H, Yamashita Y. Role of N-glycosylation in cell surface expression and protection against proteolysis of the intestinal anion exchanger SLC26A3. Am J Physiol Cell Physiol 2011; 302:C781-95. [PMID: 22159084 DOI: 10.1152/ajpcell.00165.2011] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
SLC26A3 is a Cl(-)/HCO(3)(-) exchanger that plays a major role in Cl(-) absorption from the intestine. Its mutation causes congenital chloride-losing diarrhea. It has been shown that SLC26A3 are glycosylated, with the attached carbohydrate being extracellular and perhaps modulating function. However, the role of glycosylation has yet to be clearly determined. We used the approaches of biochemical modification and site-directed mutagenesis to prevent glycosylation. Deglycosylation experiments with glycosidases indicated that the mature glycosylated form of SLC26A3 exists at the plasma membrane, and a putative large second extracellular loop contains all of the N-linked carbohydrates. Deglycosylation of SLC26A3 causes depression of transport activity compared with wild-type, although robust intracellular pH changes were still observed, suggesting that N-glycosylation is not absolutely necessary for transport activity. To localize glycosylation sites, we mutated the five consensus sites by replacing asparagine (N) with glutamine. Immnoblotting suggests that SLC26A3 is glycosylated at N153, N161, and N165. Deglycosylation of SLC26A3 causes a defect in cell surface processing with decreased cell surface expression. We also assessed whether SLC26A3 is protected from tryptic digestion. While the mature glycosylated SLC26A3 showed little breakdown after treatment with trypsin, deglycosylated SLC26A3 exhibited increased susceptibility to trypsin, suggesting that the oligosaccharides protect SLC26A3 from tryptic digestion. In conclusion, our data indicate that N-glycosylation of SLC26A3 is important for cell surface expression and for protection from proteolytic degradation that may contribute to the understanding of pathogenesis of congenital disorders of glycosylation.
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Affiliation(s)
- Hisayoshi Hayashi
- Laboratory of Physiology, School of Food and Nutritional Sciences, Univ. of Shizuoka, Suruga-ku, Shizuoka, Japan.
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Soták M, Polidarová L, Musílková J, Hock M, Sumová A, Pácha J. Circadian regulation of electrolyte absorption in the rat colon. Am J Physiol Gastrointest Liver Physiol 2011; 301:G1066-74. [PMID: 21903759 DOI: 10.1152/ajpgi.00256.2011] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The intestinal transport of nutrients exhibits distinct diurnal rhythmicity, and the enterocytes harbor a circadian clock. However, temporal regulation of the genes involved in colonic ion transport, i.e., ion transporters and channels operating in absorption and secretion, remains poorly understood. To address this issue, we assessed the 24-h profiles of expression of genes encoding the sodium pump (subunits Atp1a1 and Atp1b1), channels (α-, β-, and γ-subunits of Enac and Cftr), transporters (Dra, Ae1, Nkcc1, Kcc1, and Nhe3), and the Na(+)/H(+) exchanger (NHE) regulatory factor (Nherf1) in rat colonic mucosa. Furthermore, we investigated temporal changes in the spatial localization of the clock genes Per1, Per2, and Bmal1 and the genes encoding ion transporters and channels along the crypt axis. In rats fed ad libitum, the expression of Atp1a1, γEnac, Dra, Ae1, Nhe3, and Nherf1 showed circadian variation with maximal expression at circadian time 12, i.e., at the beginning of the subjective night. The peak γEnac expression coincided with the rise in plasma aldosterone. Restricted feeding phase advanced the expression of Dra, Ae1, Nherf, and γEnac and decreased expression of Atp1a1. The genes Atp1b1, Cftr, αEnac, βEnac, Nkcc1, and Kcc1 did not show any diurnal variations in mRNA levels. A low-salt diet upregulated the expression of βEnac and γEnac during the subjective night but did not affect expression of αEnac. Similarly, colonic electrogenic Na(+) transport was much higher during the subjective night than the subjective day. These findings indicate that the transporters and channels operating in NaCl absorption undergo diurnal regulation and suggest a role of an intestinal clock in the coordination of colonic NaCl absorption.
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Affiliation(s)
- M Soták
- Institute of Physiology, Academy of Sciences of the Czech Republic, Prague, Czech Republic
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Up-regulation of intestinal type 1 taste receptor 3 and sodium glucose luminal transporter-1 expression and increased sucrose intake in mice lacking gut microbiota. Br J Nutr 2011; 107:621-30. [PMID: 21781379 DOI: 10.1017/s0007114511003412] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The chemosensory components shared by both lingual and intestinal epithelium play a critical role in food consumption and the regulation of intestinal functions. In addition to nutrient signals, other luminal contents, including micro-organisms, are important in signalling across the gastrointestinal mucosa and initiating changes in digestive functions. A potential role of gut microbiota in influencing food intake, energy homeostasis and weight gain has been suggested. However, whether gut microbiota modulates the expression of nutrient-responsive receptors and transporters, leading to altered food consumption, is unknown. Thus, we examined the preference for nutritive (sucrose) and non-nutritive (saccharin) sweet solutions in germ-free (GF, C57BL/6J) mice compared with conventional (CV, C57BL/6J) control mice using a two-bottle preference test. Then, we quantified mRNA and protein expression of the sweet signalling protein type 1 taste receptor 3 (T1R3) and α-gustducin and Na glucose luminal transporter-1 (SGLT-1) of the intestinal epithelium of both CV and GF mice. Additionally, we measured gene expression of T1R2, T1R3 and α-gustducin in the lingual epithelium. We found that, while the preference for sucrose was similar between the groups, GF mice consumed more of the high concentration (8 %) of sucrose solution than CV mice. There was no difference in either the intake of or the preference for saccharin. GF mice expressed significantly more T1R3 and SGLT-1 mRNA and protein in the intestinal epithelium compared with CV mice; however, lingual taste receptor mRNA expression was similar between the groups. We conclude that the absence of intestinal microbiota alters the expression of sweet taste receptors and GLUT in the proximal small intestine, which is associated with increased consumption of nutritive sweet solutions.
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Abstract
Numerous studies using gastric bypass rat models have been recently conducted to uncover underlying physiological mechanisms of Roux-en-Y gastric bypass. Reflecting on lessons learned from gastric bypass rat models may thus aid the development of gastric bypass models in mice and other species. This review aims to discuss technical and experimental details of published gastric bypass rat models to understand advantages and limitations of this experimental tool. The review is based on PubMed literature using the search terms 'animal model', 'rodent model', 'bariatric surgery', 'gastric bypass', and 'Roux-en-Y gastric bypass'. All studies published up until February 2011 were included. 32 studies describing 15 different rat gastric bypass models were included. Description of surgical technique differs in terms of pouch size, limb lengths, preservation of the vagal nerve, and mortality rate. Surgery was carried out exclusively in male rats of different strains and ages. Pre- and postoperative diets also varied significantly. Technical and experimental variations in published gastric bypass rat models complicate comparison and identification of potential physiological mechanisms involved in gastric bypass. In summary, there is no clear evidence that any of these models is superior, but there is an emerging need for standardization of the procedure to achieve consistent and comparable data.
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Affiliation(s)
- Florian Seyfried
- Imperial Weight Centre, Department of Investigative Medicine, Imperial College London, London, UK
- Department of Surgery, University of Würzburg, Würzburg, Germany
| | - Carel W. le Roux
- Imperial Weight Centre, Department of Investigative Medicine, Imperial College London, London, UK
| | - Marco Bueter
- Imperial Weight Centre, Department of Investigative Medicine, Imperial College London, London, UK
- Department of Surgery, University Hospital Zürich, Zürich, Switzerland
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Banerjee SK, Wang DW, Alzamora R, Huang XN, Pastor-Soler NM, Hallows KR, McGaffin KR, Ahmad F. SGLT1, a novel cardiac glucose transporter, mediates increased glucose uptake in PRKAG2 cardiomyopathy. J Mol Cell Cardiol 2010; 49:683-92. [PMID: 20600102 DOI: 10.1016/j.yjmcc.2010.06.003] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/23/2010] [Revised: 06/06/2010] [Accepted: 06/09/2010] [Indexed: 01/04/2023]
Abstract
Human mutations in the gene PRKAG2 encoding the gamma2 subunit of AMP-activated protein kinase (AMPK) cause a glycogen storage cardiomyopathy. Transgenic mice (TG(T400N)) with the human T400N mutation exhibit inappropriate activation of AMPK and consequent glycogen storage in the heart. Although increased glucose uptake and activation of glycogen synthesis have been documented in PRKAG2 cardiomyopathy, the mechanism of increased glucose uptake has been uncertain. Wildtype (WT), TG(T400N), and TG(alpha2DN) (carrying a dominant negative, kinase dead alpha2 catalytic subunit of AMPK) mice were studied at ages 2-8 weeks. Cardiac mRNA expression of sodium-dependent glucose transporter 1 (SGLT1), but not facilitated-diffusion glucose transporter 1 (GLUT1) or GLUT4, was increased approximately 5- to 7-fold in TG(T400N) mice relative to WT. SGLT1 protein was similarly increased at the cardiac myocyte sarcolemma in TG(T400N) mice. Phlorizin, a specific SGLT1 inhibitor, attenuated cardiac glucose uptake in TG(T400N) mice by approximately 40%, but not in WT mice. Chronic phlorizin treatment reduced cardiac glycogen content by approximately 25% in TG(T400N) mice. AICAR, an AMPK activator, increased cardiac SGLT1 mRNA expression approximately 3-fold in WT mice. Relative to TG(T400N) mice, double transgenic (TG(T400N)/TG(alpha2DN)) mice had decreased ( approximately 50%) cardiac glucose uptake and decreased (approximately 70%) cardiac SGLT1 expression. TG(T400N) hearts had increased binding activity of the transcription factors HNF-1 and Sp1 to the promoter of the gene encoding SGLT1. Our data suggest that upregulation of cardiac SGLT1 is responsible for increased cardiac glucose uptake in the TG(T400N) mouse. Increased AMPK activity leads to upregulation of SGLT1, which in turn mediates increased cardiac glucose uptake.
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Affiliation(s)
- Sanjay K Banerjee
- Cardiovascular Institute, University of Pittsburgh, Pittsburgh, PA 15213-2582, USA
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20
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Rapid upregulation of sodium-glucose transporter SGLT1 in response to intestinal sweet taste stimulation. Ann Surg 2010; 251:865-71. [PMID: 20395849 DOI: 10.1097/sla.0b013e3181d96e1f] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
OBJECTIVE We set out to examine the short-term regulation of the intestinal sodium/glucose cotransporter SGLT1 by its substrate glucose and sweet taste analogs. SUMMARY BACKGROUND DATA Intestinal SGLT1 is a putative target for antidiabetic therapy; however, its physiological regulation is incompletely understood, limiting its application as a pharmacological target. While it is clearly regulated by dietary composition over a period of days, its short-term regulation by nutrients is unknown. METHODS Sprague-Dawley rats were anesthetized, and the duodenum cannulated. D-glucose, D-fructose, saccharin, D-mannitol, and water were infused for 3 hours, before harvest of proximal jejunum for SGLT1 analysis with Western blotting and quantitative polymerase chain reaction. In further experiments, the receptor region was identified by D-glucose infusion of isolated regions. Lastly, the vagus was de-afferented with capsaicin, and 5HT3-receptor activation of vagal afferents inhibited using ondansetron, before repeating experiments using water or D-glucose infusion. RESULTS Infusion of D-glucose led to 2.9-fold up-regulation in SGLT1 compared with water or iso-osmotic D-mannitol; this effect was replicated by D-fructose or saccharin. This response was strongest following isolated infusions of duodenum and proximal jejunum, with a blunted effect distally; topography matched the expression profile of sweet taste receptor T1R2/T1R3. The reflex was abolished by capsaicin pretreatment, and blunted by ondansetron. CONCLUSIONS The agonist response implicates the luminal-based sweet-taste receptor T1R2/T1R3, with the reflex apparently involving vagal afferents. The proximal nature of the sensor coincides with the excluded biliopancreatic limb in Roux-en-Y gastric bypass, and this may provide a novel explanation for the antidiabetic effect of this procedure.
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Balakrishnan A, Stearns AT, Ashley SW, Tavakkolizadeh A, Rhoads DB. Restricted feeding phase shifts clock gene and sodium glucose cotransporter 1 (SGLT1) expression in rats. J Nutr 2010; 140:908-14. [PMID: 20200113 PMCID: PMC2855260 DOI: 10.3945/jn.109.116749] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
The intestine exhibits striking diurnal rhythmicity in glucose uptake, mediated by the sodium glucose cotransporter (SGLT1); however, regulatory pathways for these rhythms remain incompletely characterized. We hypothesized that SGLT1 rhythmicity is linked to the circadian clock. To investigate this, we examined rhythmicity of Sglt1 and individual clock genes in rats that consumed food ad libitum (AL). We further compared phase shifts of Sglt1 and clock genes in a second group of rats following restricted feeding to either the dark (DF) or light (LF) phase. Rats fed during the DF were pair-fed to rats fed during the LF. Jejunal mucosa was harvested across the diurnal period to generate expression profiles of Sglt1 and clock genes Clock, Bmal1 (brain-muscle Arnt-like 1), ReverbA/B, Per(Period) 1/2, and Cry (Cryptochrome) 1/2. All clock genes were rhythmic in AL rats (P < 0.05). Sglt1 also exhibited diurnal rhythmicity, with peak expression preceding nutrient arrival (P < 0.05). Light-restricted feeding shifted the expression rhythms of Sglt1 and most clock genes (Bmal1, ReverbA and B, Per1, Per2, and Cry1) compared with dark-restricted feeding (P < 0.05). The Sglt1 rhythm shifted in parallel with rhythms of Per1 and ReverbB. These effects of restricted feeding highlight luminal nutrients as a key Zeitgeber in the intestine, capable of simultaneously shifting the phases of transporter and clock gene expression, and suggest a role for clock genes in regulating Sglt1 and therefore glucose uptake. Understanding the regulatory cues governing rhythms in intestinal function may allow new therapeutic options for conditions of dysregulated absorption such as diabetes and obesity.
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Affiliation(s)
- Anita Balakrishnan
- Department of Surgery, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115, USA.
| | - Adam T. Stearns
- Department of Surgery, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115; School of Clinical Sciences, Division of Gastroenterology, University of Liverpool, Liverpool L69 3GE, United Kingdom; Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford OX1 2JD, United Kingdom; Pediatric Endocrine Unit, MassGeneral Hospital for Children and Harvard Medical School, Boston, MA 02114
| | - Stanley W. Ashley
- Department of Surgery, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115; School of Clinical Sciences, Division of Gastroenterology, University of Liverpool, Liverpool L69 3GE, United Kingdom; Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford OX1 2JD, United Kingdom; Pediatric Endocrine Unit, MassGeneral Hospital for Children and Harvard Medical School, Boston, MA 02114
| | - Ali Tavakkolizadeh
- Department of Surgery, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115; School of Clinical Sciences, Division of Gastroenterology, University of Liverpool, Liverpool L69 3GE, United Kingdom; Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford OX1 2JD, United Kingdom; Pediatric Endocrine Unit, MassGeneral Hospital for Children and Harvard Medical School, Boston, MA 02114
| | - David B. Rhoads
- Department of Surgery, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115; School of Clinical Sciences, Division of Gastroenterology, University of Liverpool, Liverpool L69 3GE, United Kingdom; Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford OX1 2JD, United Kingdom; Pediatric Endocrine Unit, MassGeneral Hospital for Children and Harvard Medical School, Boston, MA 02114,To whom correspondence should be addressed. E-mail: and
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Abstract
The molecular basis for biological rhythms is formed by clock genes. Clock genes are functional in the liver, within gastrointestinal epithelial cells and neurons of the enteric nervous system. These observations suggest a possible role for clock genes in various circadian functions of the liver and the gastrointestinal tract through the modulation of organ specific clock-controlled genes. Consequently, disruptions in circadian rhythmicity may lead to adverse health consequences. This review will focus on the current understanding of the role of circadian rhythms in the pathogenesis of gastrointestinal- and hepatic disease such as obesity, non-alcoholic fatty liver disease, alcoholic fatty liver disease and alterations in colonic motility.
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Affiliation(s)
- Willemijntje A Hoogerwerf
- Department of Internal Medicine, Division of Gastroenterology, VA Ann Arbor Healthcare System, University of Michigan, 2215 Fuller Road, Ann Arbor, MI 48105, USA.
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Stearns AT, Balakrishnan A, Tavakkolizadeh A. Impact of Roux-en-Y gastric bypass surgery on rat intestinal glucose transport. Am J Physiol Gastrointest Liver Physiol 2009; 297:G950-7. [PMID: 20501442 PMCID: PMC2777457 DOI: 10.1152/ajpgi.00253.2009] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Roux-en-Y gastric bypass (RYGB) has become the gold-standard bariatric procedure, partly because of the rapid resolution of accompanying diabetes. There is increasing evidence this is mediated by duodenal exclusion. We hypothesize that duodenal exclusion suppresses intestinal Na(+)/glucose cotransporter SGLT1-mediated glucose transport, improving glucose handling, and aimed to test this in a rodent RYGB model. Sprague-Dawley rats underwent sham procedure or duodenal exclusion by RYGB (10 cm Roux, 16 cm biliopancreatic limbs). Animals were maintained for 3 wk on a Western diet, before harvest at 10 AM, 4 PM, and 10 PM. Sections were taken from each limb for hematoxylin and eosin staining, and morphological assessment was performed. Functional glucose uptake studies, along with Western blotting and quantitative PCR, were performed on Roux limb. Histology showed morphometric changes in Roux and common limbs, with increase in villus height and crypt depth compared with BP and sham jejunum. Despite this, glucose transport was reduced by up to 68% (P < 0.001) in the Roux limb compared with sham jejunum. Normal diurnal rhythms in glucose uptake were ablated. This occurred at a posttranscriptional level, with little change in message but appearance of different weight species of Sglt1 on Western blotting. We have shown duodenal exclusion significantly influences both intestinal structure and glucose transport function, with glucose absorptive capacity reduced after RYGB. This provides a novel mechanistic explanation for some of the antidiabetic effects of RYGB.
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Affiliation(s)
- Adam T. Stearns
- 1Department of Surgery, Brigham and Women's Hospital/Harvard Medical School, Boston, Massachusetts; ,2Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom; and
| | - Anita Balakrishnan
- 1Department of Surgery, Brigham and Women's Hospital/Harvard Medical School, Boston, Massachusetts; ,3School of Clinical Sciences, Division of Gastroenterology, University of Liverpool, Liverpool, United Kingdom
| | - Ali Tavakkolizadeh
- 1Department of Surgery, Brigham and Women's Hospital/Harvard Medical School, Boston, Massachusetts;
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