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Pereira GA, Sodré FS, Murata GM, Amaral AG, Payolla TB, Campos CV, Sato FT, Anhê GF, Bordin S. Fructose Consumption by Adult Rats Exposed to Dexamethasone In Utero Changes the Phenotype of Intestinal Epithelial Cells and Exacerbates Intestinal Gluconeogenesis. Nutrients 2020; 12:nu12103062. [PMID: 33036430 PMCID: PMC7600908 DOI: 10.3390/nu12103062] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Revised: 09/30/2020] [Accepted: 10/02/2020] [Indexed: 01/02/2023] Open
Abstract
Fructose consumption by rodents modulates both hepatic and intestinal lipid metabolism and gluconeogenesis. We have previously demonstrated that in utero exposure to dexamethasone (DEX) interacts with fructose consumption during adult life to exacerbate hepatic steatosis in rats. The aim of this study was to clarify if adult rats born to DEX-treated mothers would display differences in intestinal gluconeogenesis after excessive fructose intake. To address this issue, female Wistar rats were treated with DEX during pregnancy and control (CTL) mothers were kept untreated. Adult offspring born to CTL and DEX-treated mothers were assigned to receive either tap water (Control-Standard Chow (CTL-SC) and Dexamethasone-Standard Chow (DEX-SC)) or 10% fructose in the drinking water (CTL-fructose and DEX-fructose). Fructose consumption lasted for 80 days. All rats were subjected to a 40 h fasting before sample collection. We found that DEX-fructose rats have increased glucose and reduced lactate in the portal blood. Jejunum samples of DEX-fructose rats have enhanced phosphoenolpyruvate carboxykinase (PEPCK) expression and activity, higher facilitated glucose transporter member 2 (GLUT2) and facilitated glucose transporter member 5 (GLUT5) content, and increased villous height, crypt depth, and proliferating cell nuclear antigen (PCNA) staining. The current data reveal that rats born to DEX-treated mothers that consume fructose during adult life have increased intestinal gluconeogenesis while recapitulating metabolic and morphological features of the neonatal jejunum phenotype.
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Affiliation(s)
- Gizela A. Pereira
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, 05508-000 SP, Brazil; (G.A.P.); (F.S.S.); (G.M.M.); (A.G.A.); (T.B.P.); (F.T.S.)
| | - Frhancielly S. Sodré
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, 05508-000 SP, Brazil; (G.A.P.); (F.S.S.); (G.M.M.); (A.G.A.); (T.B.P.); (F.T.S.)
| | - Gilson M. Murata
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, 05508-000 SP, Brazil; (G.A.P.); (F.S.S.); (G.M.M.); (A.G.A.); (T.B.P.); (F.T.S.)
| | - Andressa G. Amaral
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, 05508-000 SP, Brazil; (G.A.P.); (F.S.S.); (G.M.M.); (A.G.A.); (T.B.P.); (F.T.S.)
| | - Tanyara B. Payolla
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, 05508-000 SP, Brazil; (G.A.P.); (F.S.S.); (G.M.M.); (A.G.A.); (T.B.P.); (F.T.S.)
| | - Carolina V. Campos
- Department of Pharmacology, Faculty of Medical Sciences, State University of Campinas, Campinas, 13083-887 SP, Brazil; (C.V.C.); (G.F.A.)
| | - Fabio T. Sato
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, 05508-000 SP, Brazil; (G.A.P.); (F.S.S.); (G.M.M.); (A.G.A.); (T.B.P.); (F.T.S.)
| | - Gabriel F. Anhê
- Department of Pharmacology, Faculty of Medical Sciences, State University of Campinas, Campinas, 13083-887 SP, Brazil; (C.V.C.); (G.F.A.)
| | - Silvana Bordin
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, 05508-000 SP, Brazil; (G.A.P.); (F.S.S.); (G.M.M.); (A.G.A.); (T.B.P.); (F.T.S.)
- Correspondence: ; Tel.: +55-11-3091-7245
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Radioactivity Reduction of 2-Deoxy-2-[18F] Fluoro-D-Glucose by Milk and Ursodeoxycholic Acid in Preclinical Study. Nucl Med Mol Imaging 2020; 54:105-113. [PMID: 32377262 DOI: 10.1007/s13139-020-00634-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2019] [Revised: 12/30/2019] [Accepted: 01/02/2020] [Indexed: 10/24/2022] Open
Abstract
Purpose 2-Deoxy-2-[18F] fluoro-d-glucose positron emission tomography (18F-FDG-PET) is a less-invasive and widely used diagnostic tool for detection of malignant tumors. However, prolonged retention of 18F-FDG in the body increases radiation exposure. This study evaluated the effect of oral administration of milk and ursodeoxycholic acid (UDCA) in terms of reducing radiation exposure by 18F-FDG. Methods 18F-FDG radioactivity was measured using a digital γ counter in the whole body and in various organs of rats after oral administration of milk and milk plus UDCA (milk + UDCA). Western blotting was performed to measure the expression levels of G6Pase, HK 2, CREB, FoxO1, and PGC-1α in the brain, liver, small intestine, and large intestine to assess the mechanism underlying the reduction in radiation exposure from 18F-FDG by oral administration of milk and UDCA. Results We found a significant reduction in 18F-FDG radioactivity in the whole body and in the brain, liver, and small and large intestines. Expression of G6Pase was significantly increased in the above-mentioned organs in the milk and milk + UDCA groups. Expression of HK 2 was significantly decreased in the brain and small intestine in the milk and milk + UDCA groups. CREB, FoxO1, and PGC-1α expression levels in the brain, liver, and small intestine were increased in the milk and milk + UDCA groups. However, expression of PGC-1α in the large intestine in the milk and milk + UDCA groups was significantly decreased compared with that in the control group. Conclusion The present study demonstrated that administration of milk and UDCA increased G6Pase expression levels and 18F-FDG release from the tissue. These results suggest milk and UDCA could be used to reduce radiation exposure from 18F-FDG after image acquisition. The mechanisms underpinning this phenomenon should be explored in a human study.
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Abstract
Intestinal gluconeogenesis is a recently identified function influencing energy homeostasis. Intestinal gluconeogenesis induced by specific nutrients releases glucose, which is sensed by the nervous system surrounding the portal vein. This initiates a signal positively influencing parameters involved in glucose control and energy management controlled by the brain. This knowledge has extended our vision of the gut-brain axis, classically ascribed to gastrointestinal hormones. Our work raises several questions relating to the conditions under which intestinal gluconeogenesis proceeds and may provide its metabolic benefits. It also leads to questions on the advantage conferred by its conservation through a process of natural selection.
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Affiliation(s)
- Maud Soty
- Institut National de la Santé et de la Recherche Médicale, U1213, Lyon 69372, France; Université de Lyon, Lyon 69008, France; Université Lyon I, Villeurbanne 69622, France
| | - Amandine Gautier-Stein
- Institut National de la Santé et de la Recherche Médicale, U1213, Lyon 69372, France; Université de Lyon, Lyon 69008, France; Université Lyon I, Villeurbanne 69622, France
| | - Fabienne Rajas
- Institut National de la Santé et de la Recherche Médicale, U1213, Lyon 69372, France; Université de Lyon, Lyon 69008, France; Université Lyon I, Villeurbanne 69622, France
| | - Gilles Mithieux
- Institut National de la Santé et de la Recherche Médicale, U1213, Lyon 69372, France; Université de Lyon, Lyon 69008, France; Université Lyon I, Villeurbanne 69622, France.
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Xie C, Wang Q, Wang J, Tan B, Fan Z, Deng ZY, Wu X, Yin Y. Developmental changes in hepatic glucose metabolism in a newborn piglet model: A comparative analysis for suckling period and early weaning period. Biochem Biophys Res Commun 2016; 470:824-30. [PMID: 26802463 DOI: 10.1016/j.bbrc.2016.01.114] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2016] [Accepted: 01/19/2016] [Indexed: 02/07/2023]
Abstract
The liver glucose metabolism, supplying sufficient energy for glucose-dependent tissues, is important in suckling or weaned animals, although there are few studies with piglet model. To better understand the development of glucose metabolism in the piglets during suckling period and early weaning period, we determined the hepatic glycogen content, and investigated the relative protein expression of key enzymes of glucogenesis (GNG) and mRNA levels of some glucose metabolism-related genes. During suckling period, the protein level of G6Pase in the liver of suckling piglets progressively declined with day of age compared with that of newborn piglets (at 1 day of age), whereas the PEPCK level stabilized until day 21 of age, indicating that hepatic GNG capacity gradually weakened in suckling piglets. The synthesis of hepatic glycogen, which was consistent with the fluctuation of glycolytic key genes PFKL and PKLR that gradually decreased after birth and was more or less steady during latter suckling period, although both the mRNA levels of GCK and key glucose transporter GLUT2 presented uptrend in suckling piglets. However, early weaning significantly suppressed the hepatic GNG in the weaned piglets, especially at d 3-5 of weaning period, then gradually recovered at d 7 of weaning period. Meanwhile, PFKL, PKLR and GLUT2 showed the similar trend during weaning period. On the contrast, the hepatic glycogen reached the maximum value when the G6Pase and PEPCK protein expression were at the lowest level, although the GCK level maintained increasing through 7 days of weaning period. Altogether, our study provides evidence that hepatic GNG and glycolysis in newborn piglets were more active than other days during suckling period, and early weaning could significantly suppressed glucose metabolism in liver, but this inhibition would progressively recover at day 7 after weaning.
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Affiliation(s)
- Chunyan Xie
- Hunan Provincial Engineering Research Center of Healthy Livestock, Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, Hunan, 410125, China; University of the Chinese Academy of Sciences, Beijing, 10008, China
| | - Qinhua Wang
- Hunan Provincial Engineering Research Center of Healthy Livestock, Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, Hunan, 410125, China; Hunan Co-Innovation Center of Animal Production Safety, Hunan Agricultural University, Changsha, 410128, China
| | - Jing Wang
- Hunan Provincial Engineering Research Center of Healthy Livestock, Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, Hunan, 410125, China; University of the Chinese Academy of Sciences, Beijing, 10008, China
| | - Bie Tan
- Hunan Provincial Engineering Research Center of Healthy Livestock, Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, Hunan, 410125, China; Hunan Co-Innovation Center of Animal Production Safety, Hunan Agricultural University, Changsha, 410128, China
| | - Zhiyong Fan
- Hunan Provincial Engineering Research Center of Healthy Livestock, Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, Hunan, 410125, China; Hunan Co-Innovation Center of Animal Production Safety, Hunan Agricultural University, Changsha, 410128, China
| | - Ze-yuan Deng
- State Key Laboratory of Food Science and Technology and College of Life Science and Food Engineering, Nanchang University, Nanchang, Jiangxi, 330031, China
| | - Xin Wu
- Hunan Provincial Engineering Research Center of Healthy Livestock, Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, Hunan, 410125, China; Hunan Co-Innovation Center of Animal Production Safety, Hunan Agricultural University, Changsha, 410128, China; State Key Laboratory of Food Science and Technology and College of Life Science and Food Engineering, Nanchang University, Nanchang, Jiangxi, 330031, China.
| | - Yulong Yin
- Hunan Provincial Engineering Research Center of Healthy Livestock, Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, Hunan, 410125, China; Hunan Co-Innovation Center of Animal Production Safety, Hunan Agricultural University, Changsha, 410128, China; State Key Laboratory of Food Science and Technology and College of Life Science and Food Engineering, Nanchang University, Nanchang, Jiangxi, 330031, China; School of Life Sciences, Hunan Normal University, Changsha, 41008, China; University of the Chinese Academy of Sciences, Beijing, 10008, China.
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Claud EC, Keegan KP, Brulc JM, Lu L, Bartels D, Glass E, Chang EB, Meyer F, Antonopoulos DA. Bacterial community structure and functional contributions to emergence of health or necrotizing enterocolitis in preterm infants. MICROBIOME 2013; 1:20. [PMID: 24450928 PMCID: PMC3971604 DOI: 10.1186/2049-2618-1-20] [Citation(s) in RCA: 121] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2013] [Accepted: 06/24/2013] [Indexed: 05/03/2023]
Abstract
BACKGROUND Preterm infants represent a unique patient population that is born functionally immature and must accomplish development under the influence of a hospital environment. Neonatal necrotizing enterocolitis (NEC) is an inflammatory intestinal disorder affecting preterm infants. The purpose of this study was to evaluate the progression of intestinal microbiota community development between preterm infants who remained healthy compared to preterm infants who developed NEC. RESULTS Weekly fecal samples from ten preterm infants, five with NEC and five matched healthy controls were obtained. Bacterial DNA from individual fecal samples was subjected to sequencing of 16S rRNA-based inventories using the 454 GS-FLX platform. Fecal samples from control infants demonstrated a temporal pattern in their microbiota, which converged toward that of a healthy full term breast-fed infant. Microbiota development in NEC patients diverged from controls beginning three weeks prior to diagnosis. Shotgun metagenomic sequencing was performed to identify functional differences in the respective microbiota of fecal samples from a set of twins in which one twin developed NEC and one did not. The majority of the differentially abundant genes in the NEC patient were associated with carbohydrate metabolism and mapped to members of the family Enterobacteriaceae. This may indicate an adaptation of the community to an altered profile of substrate availability for specific members as a first step towards the development of NEC. We propose that the microbial communities as a whole may metabolize milk differently, resulting in differential substrate availability for specific microbial groups. Additional differentially represented gene sets of interest were related to antibiotic resistance and vitamin biosynthesis. CONCLUSIONS Our results suggest that there is a temporal component to microbiome development in healthy preterm infants. Thus, bacteriotherapy for the treatment or prevention of NEC must consider this temporal component of the microbial community in addition to its taxonomic composition and functional content.
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Affiliation(s)
- Erika C Claud
- Section of Neonatology, Department of Pediatrics, The University of Chicago, Chicago, IL, USA
- Section of Gastroenterology, Department of Medicine, The University of Chicago, Chicago, IL, USA
| | - Kevin P Keegan
- Institute for Genomics and Systems Biology, Argonne National Laboratory, Argonne, IL, USA
| | - Jennifer M Brulc
- Institute for Genomics and Systems Biology, Argonne National Laboratory, Argonne, IL, USA
| | - Lei Lu
- Section of Neonatology, Department of Pediatrics, The University of Chicago, Chicago, IL, USA
| | - Daniela Bartels
- Mathematics and Computer Science Division, Argonne National Laboratory, Argonne, IL, USA
| | - Elizabeth Glass
- Mathematics and Computer Science Division, Argonne National Laboratory, Argonne, IL, USA
| | - Eugene B Chang
- Section of Gastroenterology, Department of Medicine, The University of Chicago, Chicago, IL, USA
| | - Folker Meyer
- Institute for Genomics and Systems Biology, Argonne National Laboratory, Argonne, IL, USA
- Mathematics and Computer Science Division, Argonne National Laboratory, Argonne, IL, USA
| | - Dionysios A Antonopoulos
- Section of Gastroenterology, Department of Medicine, The University of Chicago, Chicago, IL, USA
- Institute for Genomics and Systems Biology, Argonne National Laboratory, Argonne, IL, USA
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Delaere F, Magnan C, Mithieux G. Hypothalamic integration of portal glucose signals and control of food intake and insulin sensitivity. DIABETES & METABOLISM 2010; 36:257-62. [PMID: 20561808 DOI: 10.1016/j.diabet.2010.05.001] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2010] [Accepted: 05/05/2010] [Indexed: 11/18/2022]
Abstract
Glycolysis is an essential metabolic function that lies at the core of any cellular life. Glucose homoeostasis is, thus, a crucial physiological function of living organisms. A system of plasma glucose-sensing in the portal vein plays a key role in this homoeostasis. Connected to the hypothalamus via the peripheral nervous system, the system allows the body to adapt its response to any variation of portal glycaemia. The hypothalamus controls food intake (exogenous glucose supply) and hepatic glycogenolysis (endogenous glucose supply). Intestinal gluconeogenesis, via the release of glucose into the portal vein, plays a key role in the control of hunger and satiety, and of endogenous glucose production through the modulation of liver insulin sensitivity. The induction of intestinal gluconeogenesis provides a physiological explanation for the satiety effects induced by protein-enriched diets. In particular, the influence of protein-enriched diets on the hypothalamus is comparable to the activation observed after glucose infusion into the portal vein. The induction of intestinal gluconeogenesis also offers an explanation for the early improvement in glycaemia control observed in obese diabetic patients treated by gastric-bypass surgery. In addition to intestinal gluconeogenesis, a number of gastrointestinal hormones involved in the control of food intake exert their effects, at least in part, via the peripheral afferent nervous system. These data emphasize the importance of the gut-brain axis in the understanding and treatment of obesity and type 2 diabetes.
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Affiliation(s)
- F Delaere
- Inserm U855, Institut national de la santé et de recherche médicale, faculté de médecine Laennec, rue Guillaume-Paradin, 69372 Lyon cedex 08, France
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Previs SF, Brunengraber DZ, Brunengraber H. Is There Glucose Production Outside of the Liver and Kidney? Annu Rev Nutr 2009; 29:43-57. [DOI: 10.1146/annurev-nutr-080508-141134] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Stephen F. Previs
- Department of Nutrition, Case Western Reserve University, Cleveland, Ohio 44106;
| | | | - Henri Brunengraber
- Department of Nutrition, Case Western Reserve University, Cleveland, Ohio 44106;
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Douard V, Cui XL, Soteropoulos P, Ferraris RP. Dexamethasone sensitizes the neonatal intestine to fructose induction of intestinal fructose transporter (Slc2A5) function. Endocrinology 2008; 149:409-23. [PMID: 17947353 PMCID: PMC2194616 DOI: 10.1210/en.2007-0906] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The recent dramatic increase in fructose consumption is tightly correlated with an equally dramatic surge in the incidence of type 2 diabetes and obesity in children, but little is known about dietary fructose metabolism and absorption in neonates. The expression of the rat intestinal fructose transporter GLUT5 [Slc2A5, a member of the glucose transporter family (GLUT)] can be specifically induced by its substrate fructose, but only after weaning begins at 14 d of age. In suckling rats younger than 14 d old, dietary fructose cannot enhance GLUT5 expression. The aim of this study was to identify the mechanisms allowing fructose to stimulate GLUT5 during weaning. After intestines were perfused with fructose or glucose (control), using microarray hybridization we showed that of 5K genes analyzed in 10-d-old pups, only 13 were fructose responsive. Previous work found approximately 50 fructose-responsive genes in 20-d-old pups. To identify fructose-responsive genes whose expression also changed with age, intestines of 10- and 20-d-old littermate pups perfused with fructose were compared by microarray. Intestines of 10- and 20-d-old pups perfused with glucose were used to segregate age- but not fructose-responsive genes. About 28 genes were up- and 22 down-regulated in 20- relative to 10-d-old pups, under conditions of fructose perfusion, and many were found, by cluster analysis, to be regulated by corticosterone. When dexamethasone was injected into suckling pups before fructose perfusion, the expression of GLUT5 but not that of the sodium glucose cotransporter (SGLT) 1 and of GLUT2, as well as the uptake of fructose but not of glucose increased dramatically. Thus, dexamethasone, which allows dietary fructose to precociously stimulate intestinal fructose absorption, can mimic the effect of age and modify developmental timing mechanisms regulating GLUT5.
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Affiliation(s)
- Veronique Douard
- Department of Pharmacology and Physiology, University of Medicine and Dentistry of New Jersey, New Jersey Medical School, Newark, New Jersey 07101-1709, USA
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Chakravarty K, Hanson RW. Insulin regulation of phosphoenolpyruvate carboxykinase-c gene transcription: the role of sterol regulatory element-binding protein 1c. Nutr Rev 2007; 65:S47-56. [PMID: 17605314 DOI: 10.1111/j.1753-4887.2007.tb00328.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
The effect of insulin on the regulation of phosphoenolpyruvate carboxykinase C (PEPCK-C) gene transcription, while pivotal for control of carbohydrate metabolism, constitutes only a small part of its overall action in cellular processes. Transcription of the PEPCK-C gene is the target for a number of pathways involved in the signal transduction initiated by insulin, and these processes involve an array of transcription factors and co-regulatory proteins that either alone or in concert bind to a subset of sites in the gene promoter to regulate its expression. This review will focus on a specific transcription factor, sterol regulatory element-binding protein 1c (SREBP-1c), and its role in the control of PEPCK-C gene transcription.
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Affiliation(s)
- Kaushik Chakravarty
- Department of Cardiovascular Medicine, Discovery Biology, Pfizer La Jolla, San Diego, California 92121, USA.
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10
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Martin G, Ferrier B, Conjard A, Martin M, Nazaret R, Boghossian M, Saadé F, Mancuso C, Durozard D, Baverel G. Glutamine gluconeogenesis in the small intestine of 72 h-fasted adult rats is undetectable. Biochem J 2007; 401:465-73. [PMID: 17002601 PMCID: PMC1820798 DOI: 10.1042/bj20061148] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Recent reports have indicated that 48-72 h of fasting, Type 1 diabetes and high-protein feeding induce gluconeogenesis in the small intestine of adult rats in vivo. Since this would (i) represent a dramatic revision of the prevailing view that only the liver and the kidneys are gluconeogenic and (ii) have major consequences in the metabolism, nutrition and diabetes fields, we have thoroughly re-examined this question in the situation reported to induce the highest rate of gluconeogenesis. For this, metabolically viable small intestinal segments from 72 h-fasted adult rats were incubated with [3-13C]glutamine as substrate. After incubation, substrate utilization and product accumulation were measured by enzymatic and NMR spectroscopic methods. Although the segments utilized [13C]glutamine at high rates and accumulated 13C-labelled products linearly for 30 min in vitro, no substantial glucose synthesis could be detected. This was not due to the re-utilization of [13C]glucose initially synthesized from [13C]glutamine. Arteriovenous metabolite concentration difference measurements across the portal vein-drained viscera of 72 h-fasted Wistar and Sprague-Dawley rats clearly indicated that glutamine, the main if not the only gluconeogenic precursor taken up, could not give rise to detectable glucose production in vivo. Therefore we challenge the view that the small intestine of the adult rat is a gluconeogenic organ.
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Affiliation(s)
- Guy Martin
- Institut National de la Santé et de la Recherche Médicale, UMR 499, Animet, Faculté de Médecine RTH Laennec, Université Lyon 1, Rue G. Paradin, 69372 Lyon Cedex 08, France
| | - Bernard Ferrier
- Institut National de la Santé et de la Recherche Médicale, UMR 499, Animet, Faculté de Médecine RTH Laennec, Université Lyon 1, Rue G. Paradin, 69372 Lyon Cedex 08, France
| | - Agnès Conjard
- Institut National de la Santé et de la Recherche Médicale, UMR 499, Animet, Faculté de Médecine RTH Laennec, Université Lyon 1, Rue G. Paradin, 69372 Lyon Cedex 08, France
| | - Mireille Martin
- Institut National de la Santé et de la Recherche Médicale, UMR 499, Animet, Faculté de Médecine RTH Laennec, Université Lyon 1, Rue G. Paradin, 69372 Lyon Cedex 08, France
| | - Rémi Nazaret
- Institut National de la Santé et de la Recherche Médicale, UMR 499, Animet, Faculté de Médecine RTH Laennec, Université Lyon 1, Rue G. Paradin, 69372 Lyon Cedex 08, France
| | - Michelle Boghossian
- Institut National de la Santé et de la Recherche Médicale, UMR 499, Animet, Faculté de Médecine RTH Laennec, Université Lyon 1, Rue G. Paradin, 69372 Lyon Cedex 08, France
| | - Fadi Saadé
- Institut National de la Santé et de la Recherche Médicale, UMR 499, Animet, Faculté de Médecine RTH Laennec, Université Lyon 1, Rue G. Paradin, 69372 Lyon Cedex 08, France
| | - Claire Mancuso
- Institut National de la Santé et de la Recherche Médicale, UMR 499, Animet, Faculté de Médecine RTH Laennec, Université Lyon 1, Rue G. Paradin, 69372 Lyon Cedex 08, France
| | - Daniel Durozard
- Institut National de la Santé et de la Recherche Médicale, UMR 499, Animet, Faculté de Médecine RTH Laennec, Université Lyon 1, Rue G. Paradin, 69372 Lyon Cedex 08, France
| | - Gabriel Baverel
- Institut National de la Santé et de la Recherche Médicale, UMR 499, Animet, Faculté de Médecine RTH Laennec, Université Lyon 1, Rue G. Paradin, 69372 Lyon Cedex 08, France
- To whom correspondence should be addressed (email )
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Abstract
Gluconeogenesis is responsible for the maintenance of blood glucose levels as hepatic glycogen stores become depleted. Traditionally, only liver and kidney have been believed to be capable of gluconeogenesis, but a gluconeogenic capacity for the small intestine has recently been proposed. This possibility is supported by the expression of key gluconeogenic enzymes and radiolabeled tracer experiments, but these data are not unequivocal and alternative roles can explain the presence of gluconeogenic enzymes in this organ.
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Affiliation(s)
- Malcolm Watford
- Department of Nutritional Sciences, Rutgers University, New Brunswick, NJ 08901, USA.
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Mithieux G, Bady I, Gautier A, Croset M, Rajas F, Zitoun C. Induction of control genes in intestinal gluconeogenesis is sequential during fasting and maximal in diabetes. Am J Physiol Endocrinol Metab 2004; 286:E370-5. [PMID: 14559723 DOI: 10.1152/ajpendo.00299.2003] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We studied in rats the expression of genes involved in gluconeogenesis from glutamine and glycerol in the small intestine (SI) during fasting and diabetes. From Northern blot and enzymatic studies, we report that only phosphoenolpyruvate carboxykinase (PEPCK) activity is induced at 24 h of fasting, whereas glucose-6-phosphatase (G-6-Pase) activity is induced only from 48 h. Both genes then plateau, whereas glutaminase and glycerokinase strikingly rebound between 48 and 72 h. The two latter genes are fully expressed in streptozotocin-diabetic rats. From arteriovenous balance and isotopic techniques, we show that the SI does not release glucose at 24 h of fasting and that SI gluconeogenesis contributes to 35% of total glucose production in 72-h-fasted rats. The new findings are that 1) the SI can quantitatively account for up to one-third of glucose production in prolonged fasting; 2) the induction of PEPCK is not sufficient by itself to trigger SI gluconeogenesis; 3) G-6-Pase likely plays a crucial role in this process; and 4) glutaminase and glycerokinase may play a key potentiating role in the latest times of fasting and in diabetes.
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Affiliation(s)
- Gilles Mithieux
- Institut National de la Santé et de la Recherche Médicale 449, Faculté Laennec, 69372 Lyon, France.
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Yánez AJ, Nualart F, Droppelmann C, Bertinat R, Brito M, Concha II, Slebe JC. Broad expression of fructose-1,6-bisphosphatase and phosphoenolpyruvate carboxykinase provide evidence for gluconeogenesis in human tissues other than liver and kidney. J Cell Physiol 2003; 197:189-97. [PMID: 14502558 DOI: 10.1002/jcp.10337] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The importance of renal and hepatic gluconeogenesis in glucose homeostasis is well established, but the cellular localization of the key gluconeogenic enzymes liver fructose-1,6-bisphosphatase (FBPase) and cytosolic phosphoenolpyruvate carboxykinase (PEPCK) in these organs and the potential contribution of other tissues in this process has not been investigated in detail. Therefore, we analyzed the human tissue localization and cellular distribution of FBPase and PEPCK immunohistochemically. The localization analysis demonstrated that FBPase was expressed in many tissues that had not been previously reported to contain FBPase activity (e.g., prostate, ovary, suprarenal cortex, stomach, and heart). In some multicellular tissues, this enzyme was detected in specialized areas such as epithelial cells of the small intestine and prostate or lung pneumocytes II. Interestingly, FBPase was also present in pancreas and cortex cells of the adrenal gland, organs that are involved in the control of carbohydrate and lipid metabolism. Although similar results were obtained for PEPCK localization, different expression of this enzyme was observed in pancreas, adrenal gland, and pneumocytes type I. These results show that co-expression of FBPase and PEPCK occurs not only in kidney and liver, but also in a variety of organs such as the small intestine, stomach, adrenal gland, testis, and prostate which might also contribute to gluconeogenesis. Our results are consistent with published data on the expression of glucose-6-phosphatase in the human small intestine, providing evidence that this organ may play an important role in the human glucose homeostasis.
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Affiliation(s)
- Alejandro J Yánez
- Instituto de Bioquímica, Facultad de Ciencias, Universidad Austral de Chile, Casilla 567, Valdivia, Chile
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Wuensch SA, Ray PD. Synthesis of citrate from phosphoenolpyruvate and acetylcarnitine by mitochondria from rabbit enterocytes: implications for lipogenesis. Comp Biochem Physiol B Biochem Mol Biol 1997; 118:599-605. [PMID: 9467872 DOI: 10.1016/s0305-0491(97)00242-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Enterocytes from fasted rabbits make glucose from exogenous fructose and dihydroxyacetone at rates of 180 and 91 nmol/min/10(8) cells but do not make glucose from glycerol, aspartate, malate, lactate, alpha-ketoglutarate, glutamate or glutamine. Total activities of phosphoenolpyruvate carboxykinase, fructose 1,6-bisphosphatase and glucose 6-phosphatase in isolated enterocytes are 0.44, 0.60 and 1.90 mumol/min/10(8) cells, and > or = 95% of carboxykinase activity is intramitochondrial. Enterocytes contain marginal glycerol kinase (0.05 mumol/ min/10(8) cells) and essentially no pyruvate carboxylase activities. Enterocyte mitochondria synthesize citrate from exogenous phosphoenolpyruvate and acetylcarnitine at a rate of 2.40 nmol/min/mg protein. Citrate formation is highly dependent on exogenous HCO3 and inhibited strongly by 3-mercaptopicolinate and 1,2,3-benzenetricarboxylate. Citrate synthesis is stimulated consistently by GDP and significantly so by GTP. Citrate production is unaffected by ADP or ATP. Enterocytes from fasted-refed rabbits contain activities of 0.05, 0.12, 0.39 and 0.56 mumol/min/mg cytosolic protein of ATP:citrate lyase, NADP:malate dehydrogenase, glucose 6-phosphate dehydrogenase and NADP:isocitrate dehydrogenase. Activities of NADP:malate dehydrogenase, glucose 6-phosphate dehydrogenase and NADP:isocitrate dehydrogenase are significantly higher in enterocytes from fasted-refed rabbits than those from fasted rabbits. Mitochondrial phosphoenolpyruvate carboxykinase in enterocytes in vivo could convert glycolysis-derived phosphoenolpyruvate to oxaloacetate that, with acetyl CoA, could form citrate for export to support cytosolic lipogenesis as an activator of acetyl CoA carboxylase, a source of carbon via ATP:citrate lyase and of NADPH via NADP:malate dehydrogenase or NADP:isocitrate dehydrogenase.
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Affiliation(s)
- S A Wuensch
- Department of Biochemistry and Molecular Biology, University of North Dakota School of Medicine, Grand Forks 58202, USA
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Affiliation(s)
- P H Duée
- Institut National de la Recherche Agronomique, Jouy-en-Josas, France
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Abstract
The intestinal mucosa of infant rats was found to produce ketones when incubated in Krebs-Ringer-Bicarbonate solution. No production was found in weaned rats. Ketogenesis could be inhibited by D-carnitine or tetradecylglycidic acid (TDGA) an inhibitor of long-chain acylcarnitine transferase, suggesting that ketone production is due to a large extent to break-down of long-chain fatty acids. It is considered possible that both ketones and glucose (also produced by the infant mucosa) serve as substrates for the muscular part of the intestine.
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