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Storage and Utilization of Glycogen by Mouse Liver during Adaptation to Nutritional Changes Are GLP-1 and PASK Dependent. Nutrients 2021; 13:nu13082552. [PMID: 34444712 PMCID: PMC8399311 DOI: 10.3390/nu13082552] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Revised: 07/22/2021] [Accepted: 07/23/2021] [Indexed: 12/25/2022] Open
Abstract
Glucagon-like peptide 1 (GLP-1) and PAS kinase (PASK) control glucose and energy homeostasis according to nutritional status. Thus, both glucose availability and GLP-1 lead to hepatic glycogen synthesis or degradation. We used a murine model to discover whether PASK mediates the effect of exendin-4 (GLP-1 analogue) in the adaptation of hepatic glycogen metabolism to nutritional status. The results indicate that both exendin-4 and fasting block the Pask expression, and PASK deficiency disrupts the physiological levels of blood GLP1 and the expression of hepatic GLP1 receptors after fasting. Under a non-fasted state, exendin-4 treatment blocks AKT activation, whereby Glucokinase and Sterol Regulatory Element-Binding Protein-1c (Srebp1c) expressions were inhibited. Furthermore, the expression of certain lipogenic genes was impaired, while increasing Glucose Transporter 2 (GLUT2) and Glycogen Synthase (GYS). Moreover, exendin-4 treatment under fasted conditions avoided Glucose 6-Phosphatase (G6pase) expression, while maintaining high GYS and its activation state. These results lead to an abnormal glycogen accumulation in the liver under fasting, both in PASK-deficient mice and in exendin-4 treated wild-type mice. In short, exendin-4 and PASK both regulate glucose transport and glycogen storage, and some of the exendin-4 effects could therefore be due to the blocking of the Pask expression.
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Gilijamse PW, Demirkiran A, van Wagensveld BA, Ackermans MT, Romijn JA, Nieuwdorp M, Ter Horst KW, Serlie MJ. The relation between postprandial glucagon-like peptide-1 release and insulin sensitivity before and after bariatric surgery in humans with class II/III obesity. Surg Obes Relat Dis 2021; 17:1440-1448. [PMID: 34083134 DOI: 10.1016/j.soard.2021.04.022] [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: 11/17/2020] [Revised: 03/31/2021] [Accepted: 04/22/2021] [Indexed: 11/16/2022]
Abstract
BACKGROUND Glucagon-like peptide-1 (GLP-1) receptor agonist treatment is beneficial for the human glucose metabolism, and GLP-1 secretion is greatly enhanced following Roux-en-Y gastric bypass (RYGB). OBJECTIVES To elucidate the relationship between GLP-1 concentrations and insulin sensitivity in subjects with class II/III obesity without diabetes and to assess the relation between GLP-1 and the improvements in glucose metabolism following RYGB. SETTING Clinical research facility in a university hospital. METHODS We recruited 35 patients scheduled for RYGB and assessed their plasma GLP-1, insulin, and glucose responses to a high-fat mixed meal. Basal and insulin-mediated glucose fluxes were determined during a 2-step hyperinsulinemic-euglycemic clamp with stable isotope-labeled tracers. Out of 35 subjects, 10 were studied both before surgery and at 1 year of follow-up. RESULTS Plasma GLP-1 increased following the high-fat mixed meal. Postprandial GLP-1 excursions correlated positively with hepatic and peripheral insulin sensitivity, but not with body mass index. At 1 year after RYGB, participants had lost 24% ± 6% of their body weight. Plasma GLP-1, insulin, and glucose levels peaked earlier and higher after the mixed meal. The positive association between the postprandial GLP-1 response and peripheral insulin sensitivity persisted. CONCLUSIONS Postprandial GLP-1 concentrations correlate with insulin sensitivity in subjects with class II/III obesity without diabetes before and 1 year after RYGB. Increased GLP-1 signaling in postbariatric patients may, directly or indirectly, contribute to the observed improvements in insulin sensitivity and metabolic health.
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Affiliation(s)
- Pim W Gilijamse
- Department of Endocrinology and Metabolism, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands
| | - Ahmet Demirkiran
- Department of Surgery, Red Cross Hospital, Beverwijk, The Netherlands
| | | | - Mariette T Ackermans
- Department of Clinical Chemistry, Laboratory of Endocrinology, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands
| | - Johannes A Romijn
- Department of Medicine, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands
| | - Max Nieuwdorp
- Department of Vascular Medicine, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands
| | - Kasper W Ter Horst
- Department of Endocrinology and Metabolism, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands
| | - Mireille J Serlie
- Department of Endocrinology and Metabolism, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands.
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3
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Milani L, Galindo CM, Turin de Oliveira NM, Corso CR, Adami ER, Stipp MC, Beltrame OC, Acco A. The GLP-1 analog liraglutide attenuates acute liver injury in mice. Ann Hepatol 2020; 18:918-928. [PMID: 31151874 DOI: 10.1016/j.aohep.2019.04.011] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/20/2019] [Revised: 04/24/2019] [Accepted: 04/25/2019] [Indexed: 02/04/2023]
Abstract
INTRODUCTION AND OBJECTIVES Acute liver injury is a current health problem with few effective treatments. The present study investigated the hepatoprotective and curative potential of the glucagon-like peptide-1 analog liraglutide against carbon tetrachloride (CCl4)-induced hepatotoxicity. MATERIALS AND METHODS Male Swiss mice were subjected to two protocols. The first protocol (Pretreatment) consisted of intraperitoneal (i.p.) treatment with liraglutide (0.057 and 0.118mgkg-1) or vehicle (distilled water) once daily for 7 days. On days 6 and 7, the animals were challenged with 2% CCl4 (5mgkg-1, i.p.). The second protocol (Late treatment) began with an injection of 5% CCl4 (5mgkg-1, i.p.) and subsequent treatment with liraglutide (0.057mgkg-1) or vehicle (distilled water) for 1 day. In both protocols, 24h after the last administration, blood and bile were collected from anesthetized animals, followed by euthanasia and liver collection. Plasma and bile underwent biochemical analyses, and histological, oxidative stress, and metabolic parameters were evaluated in the liver. RESULTS Both liraglutide treatment protocols attenuated hepatotoxicity that was induced by CCl4, decreasing plasma levels of hepatic enzymes, stimulating the hepatic antioxidant system, and decreasing centrilobular necrosis, hepatic glycogen, and lipid accumulation. CCl4 tended to reduce bile lipid excretion, but liraglutide did not influence this parameter. CONCLUSIONS The present results demonstrated the hepatoprotective and therapeutic effects of liraglutide, which may be attributable to a decrease in liver oxidative stress and the preservation of metabolism. Liraglutide may have potential as a complementary therapy for acute liver injury.
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Affiliation(s)
- Letícia Milani
- Department of Pharmacology, Federal University of Paraná, Curitiba, PR, Brazil
| | - Claudia M Galindo
- Department of Pharmacology, Federal University of Paraná, Curitiba, PR, Brazil
| | | | - Claudia Rita Corso
- Department of Pharmacology, Federal University of Paraná, Curitiba, PR, Brazil
| | | | | | - Olair Carlos Beltrame
- Department of Veterinary Medicine, Federal University of Paraná, Curitiba, PR, Brazil
| | - Alexandra Acco
- Department of Pharmacology, Federal University of Paraná, Curitiba, PR, Brazil.
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4
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Grandl G, Novikoff A, DiMarchi R, Tschöp MH, Müller TD. Gut Peptide Agonism in the Treatment of Obesity and Diabetes. Compr Physiol 2019; 10:99-124. [PMID: 31853954 DOI: 10.1002/cphy.c180044] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Obesity is a global healthcare challenge that gives rise to devastating diseases such as the metabolic syndrome, type-2 diabetes (T2D), and a variety of cardiovascular diseases. The escalating prevalence of obesity has led to an increased interest in pharmacological options to counteract excess weight gain. Gastrointestinal hormones such as glucagon, amylin, and glucagon-like peptide-1 (GLP-1) are well recognized for influencing food intake and satiety, but the therapeutic potential of these native peptides is overall limited by a short half-life and an often dose-dependent appearance of unwanted effects. Recent clinical success of chemically optimized GLP-1 mimetics with improved pharmacokinetics and sustained action has propelled pharmacological interest in using bioengineered gut hormones to treat obesity and diabetes. In this article, we summarize the basic biology and signaling mechanisms of selected gut peptides and discuss how they regulate systemic energy and glucose metabolism. Subsequently, we focus on the design and evaluation of unimolecular drugs that combine the beneficial effects of selected gut hormones into a single entity to optimize the beneficial impact on systems metabolism. © 2020 American Physiological Society. Compr Physiol 10:99-124, 2020.
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Affiliation(s)
- Gerald Grandl
- Institute for Diabetes and Obesity, Helmholtz Diabetes Center, Helmholtz Zentrum München - German Research Center for Environmental Health (GmbH), Neuherberg, Germany.,German Center for Diabetes Research (DZD), Neuherberg, Germany
| | - Aaron Novikoff
- Institute for Diabetes and Obesity, Helmholtz Diabetes Center, Helmholtz Zentrum München - German Research Center for Environmental Health (GmbH), Neuherberg, Germany.,German Center for Diabetes Research (DZD), Neuherberg, Germany
| | - Richard DiMarchi
- Department of Chemistry, Indiana University, Bloomington, Indiana, USA
| | - Matthias H Tschöp
- German Center for Diabetes Research (DZD), Neuherberg, Germany.,Division of Metabolic Diseases, Technische Universität München, Munich, Germany
| | - Timo D Müller
- Institute for Diabetes and Obesity, Helmholtz Diabetes Center, Helmholtz Zentrum München - German Research Center for Environmental Health (GmbH), Neuherberg, Germany.,German Center for Diabetes Research (DZD), Neuherberg, Germany.,Department of Pharmacology and Experimental Therapy, Institute of Experimental and Clinical Pharmacology and Toxicology, Eberhard Karls University Hospitals and Clinics, Tübingen, Germany
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5
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González-García I, Milbank E, Diéguez C, López M, Contreras C. Glucagon, GLP-1 and Thermogenesis. Int J Mol Sci 2019; 20:ijms20143445. [PMID: 31337027 PMCID: PMC6678955 DOI: 10.3390/ijms20143445] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Revised: 07/09/2019] [Accepted: 07/10/2019] [Indexed: 12/15/2022] Open
Abstract
Brown adipose tissue (BAT) thermogenesis is a conserved mechanism to maintain body temperature in mammals. However, since BAT contribution to energy expenditure can represent a relevant modulator of metabolic homeostasis, many studies have focused on the nervous system and endocrine factors that control the activity of this tissue. There is long-established evidence that the counter-regulatory hormone glucagon negatively influences energy balance, enhances satiety, and increases energy expenditure. Despite compelling evidence showing that glucagon has direct action on BAT thermogenesis, recent findings are questioning this conventional attribute of glucagon action. Glucagon like peptide-1 (GLP-1) is an incretin secreted by the intestinal tract which strongly decreases feeding, and, furthermore, improves metabolic parameters associated with obesity and diabetes. Therefore, GLP-1 receptors (GLP-1-R) have emerged as a promising target in the treatment of metabolic disorders. In this short review, we will summarize the latest evidence in this regard, as well as the current therapeutic glucagon- and GLP-1-based approaches to treating obesity.
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Affiliation(s)
- Ismael González-García
- Institute for Diabetes and Obesity, Helmholtz Diabetes Center, Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), 85764 Neuherberg, Germany.
| | - Edward Milbank
- Center for Research in Molecular Medicine and Chronic Diseases (CIMUS), University of Santiago de Compostela-Instituto de Investigación Sanitaria, 15782 Santiago de Compostela, Spain
- Centro de Investigación Biomédica en Red, Fisiopatología de la Obesidad y Nutrición (CIBERobn), 15706 Santiago de Compostela, Spain
| | - Carlos Diéguez
- Center for Research in Molecular Medicine and Chronic Diseases (CIMUS), University of Santiago de Compostela-Instituto de Investigación Sanitaria, 15782 Santiago de Compostela, Spain
- Centro de Investigación Biomédica en Red, Fisiopatología de la Obesidad y Nutrición (CIBERobn), 15706 Santiago de Compostela, Spain
| | - Miguel López
- Center for Research in Molecular Medicine and Chronic Diseases (CIMUS), University of Santiago de Compostela-Instituto de Investigación Sanitaria, 15782 Santiago de Compostela, Spain
- Centro de Investigación Biomédica en Red, Fisiopatología de la Obesidad y Nutrición (CIBERobn), 15706 Santiago de Compostela, Spain
| | - Cristina Contreras
- Department of Physiology, Pharmacy School, Complutense University of Madrid, 28040 Madrid, Spain.
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Sood A, Swislocki A. Nonglycemic Effects of GLP-1 Agonists: From a Starling to Lizards to People. Metab Syndr Relat Disord 2019; 17:303-313. [PMID: 31145029 DOI: 10.1089/met.2018.0134] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
With the approval of exenatide in 2005, physicians had a new class of hypoglycemic agents available for the treatment of type 2 diabetes-the glucagon-like peptide-1 receptor agonists (or GLP-1 receptor agonists). As of this writing, there are seven drugs in this class available in the United States. In addition to demonstrating either cardiovascular risk neutrality or overt benefit, as now mandated by the United States Food and Drug Administration (FDA), many of these drugs have other, unexpected actions. It is our goal to outline these actions, some beneficial, some not. We have reviewed English-language articles in this area, not for an exhaustive study, but rather a broad search to define current understanding and perhaps generate further investigation.
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Affiliation(s)
- Ajay Sood
- 1Medical Service, VA Northern California Health Care System, Martinez, California.,2Division of Endocrinology and Metabolism, Department of Internal Medicine, UC Davis School of Medicine, Sacramento, California
| | - Arthur Swislocki
- 1Medical Service, VA Northern California Health Care System, Martinez, California.,2Division of Endocrinology and Metabolism, Department of Internal Medicine, UC Davis School of Medicine, Sacramento, California
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Müller TD, Clemmensen C, Finan B, DiMarchi RD, Tschöp MH. Anti-Obesity Therapy: from Rainbow Pills to Polyagonists. Pharmacol Rev 2019; 70:712-746. [PMID: 30087160 DOI: 10.1124/pr.117.014803] [Citation(s) in RCA: 112] [Impact Index Per Article: 22.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
With their ever-growing prevalence, obesity and diabetes represent major health threats of our society. Based on estimations by the World Health Organization, approximately 300 million people will be obese in 2035. In 2015 alone there were more than 1.6 million fatalities attributable to hyperglycemia and diabetes. In addition, treatment of these diseases places an enormous burden on our health care system. As a result, the development of pharmacotherapies to tackle this life-threatening pandemic is of utmost importance. Since the beginning of the 19th century, a variety of drugs have been evaluated for their ability to decrease body weight and/or to improve deranged glycemic control. The list of evaluated drugs includes, among many others, sheep-derived thyroid extracts, mitochondrial uncouplers, amphetamines, serotonergics, lipase inhibitors, and a variety of hormones produced and secreted by the gastrointestinal tract or adipose tissue. Unfortunately, when used as a single hormone therapy, most of these drugs are underwhelming in their efficacy or safety, and placebo-subtracted weight loss attributed to such therapy is typically not more than 10%. In 2009, the generation of a single molecule with agonism at the receptors for glucagon and the glucagon-like peptide 1 broke new ground in obesity pharmacology. This molecule combined the beneficial anorectic and glycemic effects of glucagon-like peptide 1 with the thermogenic effect of glucagon into a single molecule with enhanced potency and sustained action. Several other unimolecular dual agonists have subsequently been developed, and, based on their preclinical success, these molecules illuminate the path to a new and more fruitful era in obesity pharmacology. In this review, we focus on the historical pharmacological approaches to treat obesity and glucose intolerance and describe how the knowledge obtained by these studies led to the discovery of unimolecular polypharmacology.
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Affiliation(s)
- T D Müller
- Institute for Diabetes and Obesity, Helmholtz Diabetes Center, Helmholtz Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany (T.D.M., C.C., M.H.T.); German Center for Diabetes Research, Neuherberg, Germany (T.D.M., C.C., M.H.T.); Department of Chemistry, Indiana University, Bloomington, Indiana (B.F., R.D.D.); and Division of Metabolic Diseases, Technische Universität München, Munich, Germany (M.H.T.)
| | - C Clemmensen
- Institute for Diabetes and Obesity, Helmholtz Diabetes Center, Helmholtz Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany (T.D.M., C.C., M.H.T.); German Center for Diabetes Research, Neuherberg, Germany (T.D.M., C.C., M.H.T.); Department of Chemistry, Indiana University, Bloomington, Indiana (B.F., R.D.D.); and Division of Metabolic Diseases, Technische Universität München, Munich, Germany (M.H.T.)
| | - B Finan
- Institute for Diabetes and Obesity, Helmholtz Diabetes Center, Helmholtz Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany (T.D.M., C.C., M.H.T.); German Center for Diabetes Research, Neuherberg, Germany (T.D.M., C.C., M.H.T.); Department of Chemistry, Indiana University, Bloomington, Indiana (B.F., R.D.D.); and Division of Metabolic Diseases, Technische Universität München, Munich, Germany (M.H.T.)
| | - R D DiMarchi
- Institute for Diabetes and Obesity, Helmholtz Diabetes Center, Helmholtz Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany (T.D.M., C.C., M.H.T.); German Center for Diabetes Research, Neuherberg, Germany (T.D.M., C.C., M.H.T.); Department of Chemistry, Indiana University, Bloomington, Indiana (B.F., R.D.D.); and Division of Metabolic Diseases, Technische Universität München, Munich, Germany (M.H.T.)
| | - M H Tschöp
- Institute for Diabetes and Obesity, Helmholtz Diabetes Center, Helmholtz Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany (T.D.M., C.C., M.H.T.); German Center for Diabetes Research, Neuherberg, Germany (T.D.M., C.C., M.H.T.); Department of Chemistry, Indiana University, Bloomington, Indiana (B.F., R.D.D.); and Division of Metabolic Diseases, Technische Universität München, Munich, Germany (M.H.T.)
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8
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Brandt SJ, Müller TD, DiMarchi RD, Tschöp MH, Stemmer K. Peptide-based multi-agonists: a new paradigm in metabolic pharmacology. J Intern Med 2018; 284:581-602. [PMID: 30230640 DOI: 10.1111/joim.12837] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Obesity and its comorbidities, such as type 2 diabetes, are pressing worldwide health concerns. Available anti-obesity treatments include weight loss pharmacotherapies and bariatric surgery. Whilst surgical interventions typically result in significant and sustained weight loss, available pharmacotherapies are far less effective, typically decreasing body weight by no more than 5-10%. An emerging class of multi-agonist drugs may eventually bridge this gap. This new class of specially tailored drugs hybridizes the amino acid sequences of key metabolic hormones into one single entity with enhanced potency and sustained action. Successful examples of this strategy include multi-agonist drugs targeting the receptors for glucagon-like peptide-1 (GLP-1), glucagon and the glucose-dependent insulinotropic polypeptide (GIP). Due to the simultaneous activity at several metabolically relevant receptors, these multi-agonists offer improved body weight loss and glucose tolerance relative to their constituent monotherapies. Further advancing this concept, chimeras were generated that covalently link nuclear acting hormones such as oestrogen, thyroid hormone (T3 ) or dexamethasone to peptide hormones such as GLP-1 or glucagon. The benefit of this strategy is to restrict the nuclear hormone action exclusively to cells expressing the peptide hormone receptor, thereby maximizing combinatorial metabolic efficacy of both drug constituents in the target cells whilst preventing the nuclear hormone cargo from entering and acting on cells devoid of the peptide hormone receptor, in which the nuclear hormone might have unwanted effects. Many of these multi-agonists are in preclinical and clinical development and may represent new and effective tools in the fight against obesity and its comorbidities.
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Affiliation(s)
- S J Brandt
- Institute for Diabetes and Obesity, Helmholtz Diabetes Center, Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Neuherberg, Germany.,German Center for Diabetes Research (DZD), Neuherberg, Germany
| | - T D Müller
- Institute for Diabetes and Obesity, Helmholtz Diabetes Center, Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Neuherberg, Germany.,German Center for Diabetes Research (DZD), Neuherberg, Germany
| | - R D DiMarchi
- Department of Chemistry, Indiana University, Bloomington, IN, USA
| | - M H Tschöp
- Institute for Diabetes and Obesity, Helmholtz Diabetes Center, Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Neuherberg, Germany.,German Center for Diabetes Research (DZD), Neuherberg, Germany.,Division of Metabolic Diseases, Technische Universität München, Munich, Germany
| | - K Stemmer
- Institute for Diabetes and Obesity, Helmholtz Diabetes Center, Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Neuherberg, Germany.,German Center for Diabetes Research (DZD), Neuherberg, Germany
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Maciel MG, Beserra BTS, Oliveira FCB, Ribeiro CM, Coelho MS, Neves FDAR, Amato AA. The effect of glucagon-like peptide 1 and glucagon-like peptide 1 receptor agonists on energy expenditure: A systematic review and meta-analysis. Diabetes Res Clin Pract 2018; 142:222-235. [PMID: 29857094 DOI: 10.1016/j.diabres.2018.05.034] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Revised: 05/14/2018] [Accepted: 05/22/2018] [Indexed: 12/27/2022]
Abstract
AIM We reviewed clinical trials addressing the effect of glucacon-like peptide 1 (GLP-1) or GLP-1 receptor agonists (GLP-1RA) on energy expenditure (EE) in adults. MATERIALS AND METHODS PubMed, Science Direct and Web of Science were searched for clinical trials investigating the effect of GLP-1 or GLP-1RA on EE in adults. RESULTS Ten trials (93 participants) assessed the effect of GLP-1 administration over 1 to 48 h and found no change in resting EE (REE). Two out of three trials (62 participants) reported a significant decrease in diet-induced thermogenesis (DIT) following GLP-1 administration. Ten trials with exenatide (10 μg bid, for 10-52 weeks) or liraglutide (0.6, 1.2, 1.8 or 3 mg, for 3 days-52 weeks), with a total of 282 participants, indicated a neutral effect of these GLP-1RA on REE, DIT or physical activity-induced EE. Importantly, the longest trial with GLP-1RA reported a significant increase in REE in response to treatment with both exenatide or liraglutide and most trials reported that GLP-1RA-induced weight loss was not accompanied by decreased REE. CONCLUSIONS This review indicates that GLP-1 has no short-term effect on REE but may decrease DIT. The GLP-1RA exenatide and liraglutide have a neutral effect on REE, although it is not possible to rule out an increase in REE following prolonged treatment.
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Affiliation(s)
- Michel Garcia Maciel
- Laboratory of Molecular Pharmacology, School of Health Sciences, University of Brasilia, Brasilia, Brazil; Campus Universitario Darcy Ribeiro, Asa Norte, Brasilia, DF 70910-900, Brazil
| | - Bruna Teles Soares Beserra
- Laboratory of Molecular Pharmacology, School of Health Sciences, University of Brasilia, Brasilia, Brazil; Campus Universitario Darcy Ribeiro, Asa Norte, Brasilia, DF 70910-900, Brazil
| | - Fernanda Cerqueira Barroso Oliveira
- Laboratory of Molecular Pharmacology, School of Health Sciences, University of Brasilia, Brasilia, Brazil; Campus Universitario Darcy Ribeiro, Asa Norte, Brasilia, DF 70910-900, Brazil
| | - Carolina Martins Ribeiro
- Laboratory of Molecular Pharmacology, School of Health Sciences, University of Brasilia, Brasilia, Brazil; Campus Universitario Darcy Ribeiro, Asa Norte, Brasilia, DF 70910-900, Brazil
| | - Michella Soares Coelho
- Laboratory of Molecular Pharmacology, School of Health Sciences, University of Brasilia, Brasilia, Brazil; Campus Universitario Darcy Ribeiro, Asa Norte, Brasilia, DF 70910-900, Brazil
| | - Francisco de Assis Rocha Neves
- Laboratory of Molecular Pharmacology, School of Health Sciences, University of Brasilia, Brasilia, Brazil; Campus Universitario Darcy Ribeiro, Asa Norte, Brasilia, DF 70910-900, Brazil
| | - Angélica Amorim Amato
- Laboratory of Molecular Pharmacology, School of Health Sciences, University of Brasilia, Brasilia, Brazil; Campus Universitario Darcy Ribeiro, Asa Norte, Brasilia, DF 70910-900, Brazil.
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Brown E, Cuthbertson DJ, Wilding JP. Newer GLP-1 receptor agonists and obesity-diabetes. Peptides 2018; 100:61-67. [PMID: 29412833 DOI: 10.1016/j.peptides.2017.12.009] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/30/2017] [Revised: 12/07/2017] [Accepted: 12/08/2017] [Indexed: 02/06/2023]
Abstract
Obesity is a major risk factor for type 2 diabetes and may complicate type 1 diabetes. In parallel with the global epidemic of obesity, the incidence of type 2 diabetes is increasing exponentially. To reverse these alarming trends, weight loss becomes a major therapeutic priority in prevention and treatment of type 2 diabetes. Given that glucagon-like peptide-1 receptor agonists (GLP-1 RAs) improve glycaemic control and cause weight loss, they are receiving increasing attention for the treatment of diabetes-obesity. This review discusses current and emerging therapeutic options with GLP-1 RAs and considers the next generation of novel peptide co-agonists with the potential for improved therapeutic outcomes in obesity and type 2 diabetes.
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Affiliation(s)
- Emily Brown
- Obesity & Endocrinology Research Group, Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, United Kingdom
| | - Daniel J Cuthbertson
- Obesity & Endocrinology Research Group, Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, United Kingdom
| | - John P Wilding
- Obesity & Endocrinology Research Group, Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, United Kingdom.
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11
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Cantini G, Mannucci E, Luconi M. Perspectives in GLP-1 Research: New Targets, New Receptors. Trends Endocrinol Metab 2016; 27:427-438. [PMID: 27091492 DOI: 10.1016/j.tem.2016.03.017] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/21/2016] [Revised: 03/27/2016] [Accepted: 03/30/2016] [Indexed: 02/06/2023]
Abstract
The incretin hormone glucagon-like peptide-1 (GLP-1) binds to and activates its G-protein-coupled-receptor GLP-1R to reduce glycaemia through the stimulation of insulin and suppression of pancreatic glucagon secretion. Recently, GLP-1 effects unrelated to glucose homeostasis have been discovered in myocardium, bone, adipose tissue, and other target organs, which appear to be mainly mediated by GLP-1R-independent pathways. Here, we summarize knowledge on GLP-1R agonists (GLP-1RAs) as they relate to the improvement of glucose control, and focus on the most recently described effects, discussing the preclinical evidence of the involvement of alternative receptors and signalling mechanisms. It is now evident that the universe of GLP-1RAs is expanding further from the initial incretin effect, opening new unforeseen avenues for research and clinical applications.
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Affiliation(s)
- Giulia Cantini
- Department of Experimental and Clinical Biomedical Sciences, Endocrinology Unit, University of Florence, Florence, Italy.
| | - Edoardo Mannucci
- Department of Experimental and Clinical Biomedical Sciences, Endocrinology Unit, University of Florence, Florence, Italy; Diabetes Agency, Careggi Hospital, Florence, Italy
| | - Michaela Luconi
- Department of Experimental and Clinical Biomedical Sciences, Endocrinology Unit, University of Florence, Florence, Italy.
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Yamazaki S, Satoh H, Watanabe T. Liraglutide enhances insulin sensitivity by activating AMP-activated protein kinase in male Wistar rats. Endocrinology 2014; 155:3288-301. [PMID: 24949659 DOI: 10.1210/en.2013-2157] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
We investigated the effects of liraglutide on insulin sensitivity and glucose metabolism in male Wistar rats. The rats were fed a normal chow diet (NCD) or a 60% high-fat diet (HFD) for a total of 4 weeks. After 3 weeks of feeding, they were injected with liraglutide once a day for 7 days. Subsequently, euglycemic-hyperinsulinemic clamp studies were performed after fasting the animals for 8 hours. During the clamp studies on the NCD-fed rats, the glucose infusion rate required for euglycemia was significantly higher in the liraglutide group than in the control group. The clamp hepatic glucose output was significantly lower in the liraglutide group than in the control group, but the insulin-stimulated glucose disposal rate did not change significantly in the liraglutide groups. The clamp studies on the HFD-fed rats revealed that the glucose infusion rate required to achieve euglycemia was significantly higher in the liraglutide group than in the control HFD group, and the insulin-stimulated glucose disposal rate increased significantly in the liraglutide groups. The clamp hepatic glucose output decreased significantly in the liraglutide groups. Consistent with the clamp data, the insulin-stimulated phosphorylation of Akt and AMP-activated protein kinase was enhanced in the livers of the NCD- and HFD-fed rats and in the skeletal muscles of the HFD-fed rats. Oil red O staining indicated that liraglutide also improved hepatic steatosis. In summary, our studies suggest that in normal glucose tolerance states, liraglutide enhances insulin sensitivity in the liver but not in skeletal muscles. However, in insulin-resistant states, liraglutide improves insulin resistance in the liver and muscles and improves fatty liver.
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Affiliation(s)
- Satoru Yamazaki
- Department of Nephrology, Hypertension, Diabetology, Endocrinology, and Metabolism, Fukushima Medical University, Fukushima 960-1295, Japan
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Taing MW, Rose FJ, Whitehead JP. GLP-1(28-36)amide, the Glucagon-like peptide-1 metabolite: friend, foe, or pharmacological folly? DRUG DESIGN DEVELOPMENT AND THERAPY 2014; 8:677-88. [PMID: 24940046 PMCID: PMC4051623 DOI: 10.2147/dddt.s35723] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The glucagon-like peptide-1 (GLP-1) axis has emerged as a major therapeutic target for the treatment of type 2 diabetes. GLP-1 mediates its key insulinotropic effects via a G-protein coupled receptor expressed on β-cells and other pancreatic cell types. The insulinotropic activity of GLP-1 is terminated via enzymatic cleavage by dipeptidyl peptidase-4. Until recently, GLP-1-derived metabolites were generally considered metabolically inactive; however, accumulating evidence indicates some have biological activity that may contribute to the pleiotropic effects of GLP-1 independent of the GLP-1 receptor. Recent reports describing the putative effects of one such metabolite, the GLP-1-derived nonapeptide GLP-1(28-36) amide, are the focus of this review. Administration of the nonapeptide elevates cyclic adenosine monophosphate (cAMP) and activates protein kinase A, β-catenin, and cAMP response-element binding protein in pancreatic β-cells and hepatocytes. In stressed cells, the nonapeptide targets the mitochondria and, via poorly defined mechanisms, helps to maintain mitochondrial membrane potential and cellular adenosine triphosphate levels and to reduce cytotoxicity and apoptosis. In mouse models of diet-induced obesity, treatment with the nonapeptide reduces weight gain and ameliorates associated pathophysiology, including hyperglycemia, hyperinsulinemia, and hepatic steatosis. Nonapeptide administration in a streptozotocin-induced model of type 1 diabetes also improves glucose disposal concomitant with elevated insulin levels and increased β-cell mass and proliferation. Collectively, these results suggest some of the beneficial effects of GLP-1 receptor analogs may be mediated by the nonapeptide. However, the concentrations required to elicit some of these effects are in the micromolar range, leading to reservations about potentially related therapeutic benefits. Moreover, although controversial, concerns have been raised about the potential for incretin-based therapies to promote pancreatitis and pancreatic and thyroid cancers. The effects ascribed to the nonapeptide make it a potential contributor to such outcomes, raising additional questions about its therapeutic suitability. Notwithstanding, the nonapeptide, like other GLP-1 metabolites, appears to be biologically active. Increasing understanding of such noncanonical GLP-1 activities should help to improve future incretin-based therapeutics.
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Affiliation(s)
- Meng-Wong Taing
- Metabolic Medicine, Mater Research Institute, University of Queensland, Australia ; School of Pharmacy, University of Queensland, Brisbane, QLD, Australia
| | - Felicity J Rose
- Metabolic Medicine, Mater Research Institute, University of Queensland, Australia ; University of Queensland Diamantina Institute, Translational Research Institute, Brisbane, QLD, Australia
| | - Jonathan P Whitehead
- Metabolic Medicine, Mater Research Institute, University of Queensland, Australia
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Nguyen AT, Mandard S, Dray C, Deckert V, Valet P, Besnard P, Drucker DJ, Lagrost L, Grober J. Lipopolysaccharides-mediated increase in glucose-stimulated insulin secretion: involvement of the GLP-1 pathway. Diabetes 2014; 63:471-82. [PMID: 24186868 DOI: 10.2337/db13-0903] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Lipopolysaccharides (LPS) of the cell wall of gram-negative bacteria trigger inflammation, which is associated with marked changes in glucose metabolism. Hyperglycemia is frequently observed during bacterial infection and it is a marker of a poor clinical outcome in critically ill patients. The aim of the current study was to investigate the effect of an acute injection or continuous infusion of LPS on experimentally induced hyperglycemia in wild-type and genetically engineered mice. The acute injection of a single dose of LPS produced an increase in glucose disposal and glucose-stimulated insulin secretion (GSIS). Continuous infusion of LPS through mini-osmotic pumps was also associated with increased GSIS. Finally, manipulation of LPS detoxification by knocking out the plasma phospholipid transfer protein (PLTP) led to increased glucose disposal and GSIS. Overall, glucose tolerance and GSIS tests supported the hypothesis that mice treated with LPS develop glucose-induced hyperinsulinemia. The effects of LPS on glucose metabolism were significantly altered as a result of either the accumulation or antagonism of glucagon-like peptide 1 (GLP-1). Complementary studies in wild-type and GLP-1 receptor knockout mice further implicated the GLP-1 receptor-dependent pathway in mediating the LPS-mediated changes in glucose metabolism. Hence, enhanced GLP-1 secretion and action underlies the development of glucose-mediated hyperinsulinemia associated with endotoxemia.
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Affiliation(s)
- Anh Thoai Nguyen
- INSERM UMR866-LabEx LipSTIC, Faculté de Médecine, Université de Bourgogne, Dijon, France
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15
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Abstract
Glucagon-like peptide-1 (GLP-1), an incretin hormone secreted primarily from the intestinal L-cells in response to meals, modulates nutrient homeostasis via actions exerted in multiple tissues and cell types. GLP-1 and its analogs, as well as compounds that inhibit endogenous GLP-1 breakdown, have become an effective therapeutic strategy for many subjects with type 2 diabetes. Here we review the discovery of GLP-1; its synthesis, secretion, and elimination from the circulation; and its multiple pancreatic and extrapancreatic effects. Finally, we review current options for GLP-1-based diabetes therapy, including GLP-1 receptor agonism and inhibition of GLP-1 breakdown, as well as the benefits and drawbacks of different modes of therapy and the potential for new therapeutic avenues.
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Affiliation(s)
- Young Min Cho
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Seoul National University College of Medicine, Seoul 110-744, South Korea;
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16
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Gutiérrez-Rojas I, Lozano D, Nuche-Berenguer B, Moreno P, Acitores A, Ramos-Álvarez I, Rovira A, Novials A, Martín-Crespo E, Villanueva-Peñacarrillo ML, Esbrit P. Amylin exerts osteogenic actions with different efficacy depending on the diabetic status. Mol Cell Endocrinol 2013. [PMID: 23178165 DOI: 10.1016/j.mce.2012.11.013] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Amylin displays osteogenic features, but its role in diabetic osteopenia is unclear. We examined the possible osteogenic action of amylin infusion for 3days into fructose-induced insulin-resistant (IR) and streptozotocin-induced type 2 diabetic (T2D) and normal (N) rats. Amylin failed to affect glycaemia or parathyroid hormone levels in any group, but reduced hyperinsulinemia in IR rats. In N rats, amylin increased bone formation rate and reduced osteoclast surface and erosive surface in the femoral metaphysis, and increased osteoprotegerin (OPG)/receptor activator of NFκB ligand (RANKL) mRNA ratio in the tibia. In T2D rats, amylin normalized trabecular structure parameters and increased osteoblast number and osteocalcin (OC) expression in long bones. In contrast, in IR rats, no apparent osteogenic effect of amylin in the femur was observed, although both OC and OPG/RANKL ratio were increased in the tibia. Our findings demonstrate a different osteogenic efficacy of amylin in two diabetic settings.
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Affiliation(s)
- I Gutiérrez-Rojas
- Departamento de Metabolismo, Nutrición y Hormonas, Instituto de Investigación Sanitaria (IIS)-Fundación Jiménez Díaz, Madrid, Spain
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17
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Dhanesha N, Joharapurkar A, Shah G, Dhote V, Kshirsagar S, Bahekar R, Jain M. Exendin-4 reduces glycemia by increasing liver glucokinase activity: an insulin independent effect. Pharmacol Rep 2012; 64:140-9. [PMID: 22580530 DOI: 10.1016/s1734-1140(12)70740-5] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2011] [Revised: 11/04/2011] [Indexed: 01/13/2023]
Abstract
Exendin-4 is a stable peptide agonist of GLP-1 receptor that exhibits insulinotropic actions. Some in vivo studies indicated insulin-independent glucoregulatory actions of exendin-4. That finding prompted us to evaluate effects of exendin-4 on liver glucose metabolism. Acute and chronic treatment of exendin-4 resulted in increased hepatic glucokinase activity in db/db mice but not in lean C57 mice. The stimulatory effect of exendin-4 on glucokinase activity was abrogated by exendin 9-39, a GLP-1 antagonist. Exposure of hepatocytes isolated from db/db mice to exendin-4 elicited a rapid increase in cAMP, which was synergized by IBMX, an inhibitor of cAMP degradation. The GLP-1 antagonist, exendin 9-39, has abolished the cAMP generating effects of exendin-4 as well. Furthermore, chronic treatment of exendin-4 in streptozotocin-treated C57 mice resulted in restoration of hepatic glycogen, an indicator of improved glucose metabolism, without apparent changes in serum insulin levels. In conclusion, exendin-4 increased glucokinase enzyme protein and activity in liver via a mechanism parallel to and independent of insulin. Exendin-4-induced increase in hepatic glucokinase activity is more pronounced in the presence of hepatic insulin resistance. This beneficial effect of exendin-4 on liver glucokinase activity may be mediated by GLP-1 receptor.
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Affiliation(s)
- Nirav Dhanesha
- Department of Pharmacology and Toxicology, Zydus Research Centre, Cadila Healthcare Ltd., Sarkhej-Bavla N.H. No. 8A, Moraiya, Ahmedabad 382210, India
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18
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Abstract
In healthy humans, the incretin glucagon-like peptide 1 (GLP-1) is secreted after eating and lowers glucose concentrations by augmenting insulin secretion and suppressing glucagon release. Additional effects of GLP-1 include retardation of gastric emptying, suppression of appetite and, potentially, inhibition of β-cell apoptosis. Native GLP-1 is degraded within ~2-3 min in the circulation; various GLP-1 receptor agonists have, therefore, been developed to provide prolonged in vivo actions. These GLP-1 receptor agonists can be categorized as either short-acting compounds, which provide short-lived receptor activation (such as exenatide and lixisenatide) or as long-acting compounds (for example albiglutide, dulaglutide, exenatide long-acting release, and liraglutide), which activate the GLP-1 receptor continuously at their recommended dose. The pharmacokinetic differences between these drugs lead to important differences in their pharmacodynamic profiles. The short-acting GLP-1 receptor agonists primarily lower postprandial blood glucose levels through inhibition of gastric emptying, whereas the long-acting compounds have a stronger effect on fasting glucose levels, which is mediated predominantly through their insulinotropic and glucagonostatic actions. The adverse effect profiles of these compounds also differ. The individual properties of the various GLP-1 receptor agonists might enable incretin-based treatment of type 2 diabetes mellitus to be tailored to the needs of each patient.
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Affiliation(s)
- Juris J Meier
- Division of Diabetology, St Josef-Hospital, Ruhr-University Bochum, Gudrunstraße 56, 44791 Bochum, Germany.
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Moreno P, Nuche-Berenguer B, Gutiérrez-Rojas I, Acitores A, Sancho V, Valverde I, González N, Villanueva-Peñacarrillo ML. Normalizing action of exendin-4 and GLP-1 in the glucose metabolism of extrapancreatic tissues in insulin-resistant and type 2 diabetic states. J Mol Endocrinol 2012; 48:37-47. [PMID: 22065862 DOI: 10.1530/jme-11-0127] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Exendin-4 (Ex-4) mimics glucagon-like peptide-1 (GLP-1 or GCG as listed in the HUGO database), being anti-diabetic and anorectic, in stimulating glucose and lipid metabolism in extrapancreatic tissues. We studied the characteristics of Ex-4 and GLP-1 action, during prolonged treatment, on GLUTs expression (mRNA and protein), glycogen content (GC), glucose transport (GT), glycogen synthase a (GSa), and kinase (PI3K and MAPKs) activity, in liver, muscle, and fat of insulin-resistant (IR, by fructose) and type 2 diabetic (T2D, streptozotocin at birth) rats compared with normal rats. In both IR and T2D, the three tissues studied presented alterations in all measured parameters. In liver, GLP-1 and also Ex-4 normalized the lower than normal Glut2 (Slc2a2) expression and showed a trend to normalize the reduced GC in IR, and GLP-1, like Ex-4, also in T2D, effects mediated by PI3K and MAPKs. In skeletal muscle, neither GLP-1 nor Ex-4 modified Glut4 (Slc2a4) expression in either experimental model but showed normalization of reduced GT and GSa, in parallel with the normalization of reduced PI3K activity in T2D and MAPKs in both models. In adipose tissue, the altered GLUT4 expression in IR and T2D, along with reduced GT in IR and increased GT in T2D, and with hyperactivated PI3K in both, became normal after GLP-1 and Ex-4 treatment; yet, MAPKs, that were also higher, became normal only after Ex-4 treatment. The data shows that Ex-4, as well as GLP-1, exerts a normalizing effect on IR and T2D states through a distinct post-receptor mechanism, the liver being the main target for Ex-4 and GLP-1 to control glucose homeostasis.
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Affiliation(s)
- Paola Moreno
- Department of Metabolism, Nutrition and Hormones, IIS-Fundación Jiménez Díaz, Avda. Reyes Católicos, 2, 28040 Madrid, Spain
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20
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Park JH, Earm YE, Song DK. Cellular glucose availability and glucagon-like peptide-1. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2011; 107:286-92. [PMID: 21907232 DOI: 10.1016/j.pbiomolbio.2011.08.009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2011] [Revised: 08/22/2011] [Accepted: 08/25/2011] [Indexed: 12/25/2022]
Abstract
Glucagon-like peptide (GLP)-1 and gastric inhibitory polypeptide (GIP, glucose-dependent insulinotropic polypeptide) are produced in enteroendocrine L-cells and K-cells, respectively. They are known as incretins because they potentiate postprandial insulin secretion. Although unresponsiveness of type 2 diabetes (T2D) patients to GIP has now been reconsidered, GLP-1 mimetics and inhibitors of the GLP-1 degradation enzyme dipeptidyl peptidase (DPP)-4 have now been launched as drugs against T2D. The major roles of GLP-1 in T2D are reduction of appetite, gastric motility, glucagon secretion, enhancement of insulin secretion and β-cell survival. For insulin secretion and peripheral insulin function, GLP-1 and its mimetics sensitise β-cells to glucose; accelerate blood glucose withdrawal, in-cell glucose utilisation and glycogen synthesis in insulin-sensitive tissues; and assist in the function and survival of neurons mainly using glucose as an energy source. Taken together, GLP-1 acts to potentiate glucose availability of various cells or tissues to assist with their essential functions and/or survival. Herein, we review the signalling pathways and clinical relevance of GLP-1 in enhancing cellular glucose availability. On the basis of our recent research results, we also describe a mechanism that regulates GLP-1 for glucokinase activity. Because diabetic tissues including β-cells resist glucose, GLP-1 may be useful for treating T2D.
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Affiliation(s)
- Jae-Hyung Park
- Department of Physiology, Keimyung University School of Medicine, 2800 Dalgubeoldae-Ro, Dalseo-Gu, Daegu 704-701, Republic of Korea
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21
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Huisamen B, Genis A, Marais E, Lochner A. Pre-treatment with a DPP-4 inhibitor is infarct sparing in hearts from obese, pre-diabetic rats. Cardiovasc Drugs Ther 2011; 25:13-20. [PMID: 21088878 DOI: 10.1007/s10557-010-6271-7] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Cardiovascular risk is closely associated with insulin resistance and type 2 diabetes. Therapy based on the actions of GLP-1 is currently seen as a novel approach to treat this disease. The aims of this study was therefore to use an animal model to determine whether (i) pre-treatment of obese, insulin resistant but pre-diabetic rats with a DPP4 inhibitor, PFK275-055, could protect the heart from ischaemia/reperfusion injury and (ii) the possible mechanisms involved in such protection. Obese, pre-diabetic rats (DIO) were treated for 4 weeks with 10 mg/kg/day of the DPP4 inhibitor PFK275-055. Ex vivo perfusion was used to subject hearts to ischaemia/reperfusion to determine infarct size, functional recovery and post-ischaemic activation of proteins associated with cardiac protection. Adult ventricular cardiomyocytes were isolated to determine insulin sensitivity. Other assessments included body weight, intra-peritoneal fat weight, insulin and GLP-1 levels as well as histological evaluation of the pancreata. Results showed that DIO animals had higher body mass and intra-peritoneal fat mass than chow-fed animals. They presented with elevated plasma insulin levels and lower GLP-1 levels. Treatment with the DPP4 inhibitor resulted in smaller infarct size development in hearts from DIO rats after ischaemia/reperfusion accompanied by activation of cardioprotective kinases. GLP-1 levels were elevated and plasma insulin levels lower after treatment. In addition, the beta-cell to alpha-cell ratio of the pancreas was improved. We conclude that treatment with PFK275-055 for 4 weeks protected the heart against ischaemia/reperfusion injury, elevated GLP-1 levels and improved metabolic control in obese, pre-diabetic rats.
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22
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Villanueva-Peñacarrillo ML, Martín-Duce A, Ramos-Álvarez I, Gutiérrez-Rojas I, Moreno P, Nuche-Berenguer B, Acitores A, Sancho V, Valverde I, González N. Characteristic of GLP-1 effects on glucose metabolism in human skeletal muscle from obese patients. ACTA ACUST UNITED AC 2011; 168:39-44. [PMID: 21419173 DOI: 10.1016/j.regpep.2011.03.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2010] [Revised: 02/16/2011] [Accepted: 03/09/2011] [Indexed: 01/21/2023]
Abstract
Direct effects of GLP-1, kinase-mediated, on glucose and lipid metabolism in rat and human extrapancreatic tissues, are amply documented and also changes in type-2 diabetic (T2D) patients. Here, we explored the characteristics of the GLP-1 action and those of its analogs Ex-4 and Ex-9, on muscle glucose transport (GT) and metabolism in human morbid obesity (OB), as compared with normal and T2D subjects. In primary cultured myocytes from OB, GT and glycogen synthase a (GSa) activity values were lower than normal, and comparable to those reported in T2D patients; GT was increased by either GLP-1 or Ex-9 in a more efficient manner than in normal or T2D, up to normal levels; the Ex-4 increasing effect on GSa activity was two times that in normal cells, while Ex-9 failed to modify the enzyme activity. In OB, the control value of all kinases analyzed - PI3K, PKB, MAPKs, and p70s6K - although lower than that in normal or T2D subjects, the cells maintained their response capability to GLP-1, Ex-4, Ex-9 and insulin, with some exceptions. GLP-1 and exendins showed a direct normalizing action in the altered glucose uptake and metabolism in the muscle of obese subjects, which in the case of GLP-1 could account, at least in part, for the reported restoration of the metabolic conditions of these patients after restrictive surgery.
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Tomas E, Wood JA, Stanojevic V, Habener JF. Glucagon-like peptide-1(9-36)amide metabolite inhibits weight gain and attenuates diabetes and hepatic steatosis in diet-induced obese mice. Diabetes Obes Metab 2011; 13:26-33. [PMID: 21114600 DOI: 10.1111/j.1463-1326.2010.01316.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
AIMS The metabolic syndrome, a disease arising from the world-wide epidemic of obesity, is manifested as severe insulin resistance, hyperlipidaemia, hepatic steatosis and diabetes. Previously we reported that GLP-1(9-36)amide, derived from the gluco-incretin hormone, glucagon-like peptide-1 (GLP-1), suppresses gluconeogenesis in isolated hepatocytes. The aims of this study were to determine the effects of GLP-1(9-36)amide in diet-induced obese mice that model the development of the metabolic syndrome. METHODS Mice rendered obese by feeding a very high fat diet were administered GLP-1(9-36)amide via subcutaneous osmopumps for 8 weeks. Body weight, energy intake, plasma insulin and glucose levels (insulin-resistance), and hepatic steatosis were assessed. RESULTS Eight-week infusions of GLP-1(9-36)amide inhibited weight gain, increased energy intake, prevented the development of fasting hyperinsulinaemia and hyperglycaemia, and curtailed the accumulation of liver triglycerides. The peptide had no effects in mice fed a normal chow diet. Notably, energy intake in the obese mice receiving GLP-1(9-36)amide was 20% greater than obese mice receiving vehicle control. CONCLUSIONS GLP-1(9-36)amide exerts insulin-like actions in the presence of insulin resistance and prevents the development of metabolic syndrome. Curtailment of weight gain in the face of increased caloric intake suggests that GLP-1(9-36)amide increases energy expenditure. These findings suggest the possibility of the use of GLP-1(9-36)amide, or a peptide mimetic derived there from, for the treatment of obesity, insulin resistance and the metabolic syndrome.
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Affiliation(s)
- E Tomas
- Massachusetts General Hospital, Boston, 02114, USA
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24
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Nuche-Berenguer B, Portal-Núñez S, Moreno P, González N, Acitores A, López-Herradón A, Esbrit P, Valverde I, Villanueva-Peñacarrillo ML. Presence of a functional receptor for GLP-1 in osteoblastic cells, independent of the cAMP-linked GLP-1 receptor. J Cell Physiol 2010; 225:585-92. [PMID: 20506394 DOI: 10.1002/jcp.22243] [Citation(s) in RCA: 100] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Glucagon-like peptide 1 (GLP-1) controls glucose metabolism in extrapancreatic tissues through receptors other than the pancreatic cAMP-linked GLP-1 receptor; also, GLP-1 induces an insulin- and PTH-independent bone anabolic action in insulin-resistant and type-2 diabetic rats. Here we searched for the presence and characteristics of GLP-1 receptors in osteoblastic MC3T3-E1 cells. [(125)I]-GLP-1 specific binding to MC3T3-E1 cells was time- and temperature-dependent, reaching maximal value at 30 min at 25 degrees C; in these conditions, [(125)I]-GLP-1 binding was dissociable, and displaced by GLP-1, partially by GLP-2, but not by exendin-4 (Ex-4), exendin-9 (Ex-9), glucagon or insulin; Scatchard analysis of the unlabeled GLP-1 data showed high and low affinity binding sites; cross-linking of GLP-1 binding revealed an estimated 70 kDa band, almost undetectable in the presence of 10(-6) M GLP-1. GLP-1, Ex-9, insulin or glucagon failed to modify cellular cAMP content, while GLP-2 and Ex-4 increased it. However, GLP-1 induced an immediate hydrolysis of glycosylphosphatidylinositols (GPIs) generating short-lived inositolphosphoglycans (IPGs), and an increase in phosphatidylinositol-3 kinase (PI3K) and mitogen activated protein kinase (MAPK) activities; Ex-4 also affected GPIs, but its action was delayed with respect to that of GLP-1. This incretin was found to decrease Runx2 but increased osteocalcin gene expression, without affecting that of osteoprotegerin or the canonical Wnt pathway activity in MC3T3-E1 cells which do not express the pancreatic GLP-1 receptor. Our data demonstrate for the first time that GLP-1 can directly and functionally interact with osteoblastic cells, possibly through a GPI/IPG-coupled receptor.
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25
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McIntosh CHS, Widenmaier S, Kim SJ. Pleiotropic actions of the incretin hormones. VITAMINS AND HORMONES 2010; 84:21-79. [PMID: 21094896 DOI: 10.1016/b978-0-12-381517-0.00002-3] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The insulin secretory response to a meal results largely from glucose stimulation of the pancreatic islets and both direct and indirect (autonomic) glucose-dependent stimulation by incretin hormones released from the gastrointestinal tract. Two incretins, Glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1), have so far been identified. Localization of the cognate G protein-coupled receptors for GIP and GLP-1 revealed that they are present in numerous tissues in addition to the endocrine pancreas, including the gastrointestinal, cardiovascular, central nervous and autonomic nervous systems (ANSs), adipose tissue, and bone. At these sites, the incretin hormones exert a range of pleiotropic effects, many of which contribute to the integration of processes involved in the regulation of food intake, and nutrient and mineral processing and storage. From detailed studies at the cellular and molecular level, it is also evident that both incretin hormones act via multiple signal transduction pathways that regulate both acute and long-term cell function. Here, we provide an overview of current knowledge relating to the physiological roles of GIP and GLP-1, with specific emphasis on their modes of action on islet hormone secretion, β-cell proliferation and survival, central and autonomic neuronal function, gastrointestinal motility, and glucose and lipid metabolism. However, it is emphasized that despite intensive research on the various body systems, in many cases there is uncertainty as to the pathways by which the incretins mediate their pleiotropic effects and only a rudimentary understanding of the underlying cellular mechanisms involved, and these are challenges for the future.
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Affiliation(s)
- Christopher H S McIntosh
- Department of Cellular & Physiological Sciences and the Diabetes Research Group, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
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26
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Raab EL, Vuguin PM, Stoffers DA, Simmons RA. Neonatal exendin-4 treatment reduces oxidative stress and prevents hepatic insulin resistance in intrauterine growth-retarded rats. Am J Physiol Regul Integr Comp Physiol 2009; 297:R1785-94. [PMID: 19846744 DOI: 10.1152/ajpregu.00519.2009] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Intrauterine growth retardation (IUGR) has been linked to the development of type 2 diabetes in adulthood. We have developed an IUGR model in the rat whereby the animals develop diabetes later in life. Previous studies demonstrate that administration of the long-acting glucagon-like-peptide-1 agonist, exendin-4, during the neonatal period prevents the development of diabetes in IUGR rats. IUGR animals exhibit hepatic insulin resistance early in life (prior to the onset of hyperglycemia), characterized by blunted suppression of hepatic glucose production (HGP) in response to insulin. Basal HGP is also significantly higher in IUGR rats. We hypothesized that neonatal administration of exendin-4 would prevent the development of hepatic insulin resistance. IUGR and control rats were given exendin-4 on days 1-6 of life. Hyperinsulinemic-euglycemic clamp studies showed that Ex-4 significantly reduced basal HGP by 20% and normalized insulin suppression of HGP in IUGR rats. While Ex-4 decreased body weight and fat content in both Control and IUGR animals, these differences were only statistically significant in Controls. Exendin-4 prevented development of oxidative stress in liver and reversed insulin-signaling defects in vivo, thereby preventing the development of hepatic insulin resistance. Defects in glucose disposal and suppression of hepatic glucose production in response to insulin were reversed. Similar results were obtained in isolated Ex-4-treated neonatal hepatocytes. These results indicate that exposure to exendin-4 in the newborn period reverses the adverse consequences of fetal programming and prevents the development of hepatic insulin resistance.
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Affiliation(s)
- Elisabeth L Raab
- Department of Pediatrics, Children's Hospital Los Angeles, Los Angeles, California, USA
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Nuche-Berenguer B, Moreno P, Esbrit P, Dapía S, Caeiro JR, Cancelas J, Haro-Mora JJ, Villanueva-Peñacarrillo ML. Effect of GLP-1 treatment on bone turnover in normal, type 2 diabetic, and insulin-resistant states. Calcif Tissue Int 2009; 84:453-61. [PMID: 19219381 DOI: 10.1007/s00223-009-9220-3] [Citation(s) in RCA: 134] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/14/2008] [Accepted: 01/14/2009] [Indexed: 10/21/2022]
Abstract
It has been suggested that hormones released after nutrient absorption, such as glucose-dependent insulinotropic peptide (GIP) and glucagon-like peptide 2 (GLP-2), could be responsible for changes in bone resorption. However, information about the role of GLP-1 in this regard is scanty. Diabetes-related bone loss occurs as a consequence of poor control of glucose homeostasis, but the relationship between osteoporosis and type 2 diabetes remains unclear. Since GLP-1 is decreased in the latter condition, we evaluated some bone characteristics in streptozotocin-induced type 2 diabetic (T2D) and fructose-induced insulin-resistant (IR) rat models compared to normal (N) and the effect of GLP-1 or saline (control) treatment (3 days by osmotic pump). Blood was taken before and after treatment for plasma measurements; tibiae and femora were collected for gene expression of bone markers (RT-PCR) and structure (microCT) analysis. Compared to N, plasma glucose and insulin were, respectively, higher and lower in T2D; osteocalcin (OC) and tartrate-resistant alkaline phosphatase 5b were lower; phosphate in IR showed a tendency to be higher; PTH was not different in T2D and IR; all parameters were unchanged after GLP-1 infusion. Bone OC, osteoprotegerin (OPG) and RANKL mRNA were lower in T2D and IR; GLP-1 increased OC and OPG in all groups and RANKL in T2D. Compared to N, trabecular bone parameters showed an increased degree of anisotropy in T2D and IR, which was reduced after GLP-1. These findings show an insulin-independent anabolic effect of GLP-1 and suggest that GLP-1 could be a useful therapeutic agent for improving the deficient bone formation and bone structure associated with glucose intolerance.
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Affiliation(s)
- Bernardo Nuche-Berenguer
- Department of Metabolism, Nutrition, and Hormones, Fundación Jiménez Díaz, Avda. Reyes Católicos 2, Madrid, Spain
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Abu-Hamdah R, Rabiee A, Meneilly GS, Shannon RP, Andersen DK, Elahi D. Clinical review: The extrapancreatic effects of glucagon-like peptide-1 and related peptides. J Clin Endocrinol Metab 2009; 94:1843-52. [PMID: 19336511 PMCID: PMC2690432 DOI: 10.1210/jc.2008-1296] [Citation(s) in RCA: 150] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
CONTEXT Glucagon-like peptide-1 (GLP-1) 7-36 amide, an insulinotropic hormone released from the intestinal L cells in response to nutrient ingestion, has been extensively reviewed with respect to beta-cell function. However GLP-1 receptors are abundant in many other tissues. Thus, the function of GLP-1 is not limited to the islet cells, and it has regulatory actions on many other organs. EVIDENCE ACQUISITION A review of published, peer-reviewed medical literature (1987 to September 2008) on the extrapancreatic actions of GLP-1 was performed. EVIDENCE SYNTHESIS The extrapancreatic actions of GLP-1 include inhibition of gastric emptying and gastric acid secretion, thereby fulfilling the definition of GLP-1 as an enterogastrone. Other important extrapancreatic actions of GLP-1 include a regulatory role in hepatic glucose production, the inhibition of pancreatic exocrine secretion, cardioprotective and cardiotropic effects, the regulation of appetite and satiety, and stimulation of afferent sensory nerves. The primary metabolite of GLP-1, GLP-1 (9-36) amide, or GLP-1m, is the truncated product of degradation by dipeptidyl peptidase-4. GLP-1m has insulinomimetic effects on hepatic glucose production and cardiac function. Exendin-4 present in the salivary gland of the reptile, Gila monster (Heloderma suspectum), is a high-affinity agonist for the mammalian GLP-1 receptor. It is resistant to degradation by dipeptidyl peptidase-4, and therefore has a prolonged half-life. CONCLUSION GLP-1 and its metabolite have important extrapancreatic effects particularly with regard to the cardiovascular system and insulinomimetic effects with respect to glucose homeostasis. These effects may be particularly important in the obese state. GLP-1, GLP-1m, and exendin-4 therefore have potential therapeutic roles because of their diffuse extrapancreatic actions.
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Affiliation(s)
- Rania Abu-Hamdah
- Johns Hopkins University School of Medicine, Department of Surgery, Johns Hopkins Bayview Medical Center, Baltimore, Maryland 21224-2780, USA
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Edgerton DS, Johnson KMS, Neal DW, Scott M, Hobbs CH, Zhang X, Duttaroy A, Cherrington AD. Inhibition of dipeptidyl peptidase-4 by vildagliptin during glucagon-like Peptide 1 infusion increases liver glucose uptake in the conscious dog. Diabetes 2009; 58:243-9. [PMID: 18840785 PMCID: PMC2606880 DOI: 10.2337/db08-0515] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
OBJECTIVE This study investigated the acute effects of treatment with vildagliptin on dipeptidyl peptidase-4 (DPP-4) activity, glucagon-like peptide 1 (GLP-1) concentration, pancreatic hormone levels, and glucose metabolism. The primary aims were to determine the effects of DPP-4 inhibition on GLP-1 clearance and on hepatic glucose uptake. RESEARCH DESIGN AND METHODS Fasted conscious dogs were studied in the presence (n = 6) or absence (control, n = 6) of oral vildagliptin (1 mg/kg). In both groups, GLP-1 was infused into the portal vein (1 pmol . kg(-1) . min(-1)) for 240 min. During the same time, glucose was delivered into the portal vein at 4 mg . kg(-1) . min(-1) and into a peripheral vein at a variable rate to maintain the arterial plasma glucose level at 160 mg/dl. RESULTS Vildagliptin fully inhibited DPP-4 over the 4-h experimental period. GLP-1 concentrations were increased in the vildagliptin-treated group (50 +/- 3 vs. 85 +/- 7 pmol/l in the portal vein in control and vildagliptin-treated dogs, respectively; P < 0.05) as a result of a 40% decrease in GLP-1 clearance (38 +/- 5 and 22 +/- 2 ml . kg(-1) . min(-1), respectively; P < 0.05). Although hepatic insulin and glucagon levels were not significantly altered, there was a tendency for plasma insulin to be greater (hepatic levels were 73 +/- 10 vs. 88 +/- 15 microU/ml, respectively). During vildagliptin treatment, net hepatic glucose uptake was threefold greater than in the control group. This effect was greater than that predicted by the change in insulin. CONCLUSIONS Vildagliptin fully inhibited DPP-4 activity, reduced GLP-1 clearance by 40%, and increased hepatic glucose disposal by means beyond the effects of GLP-1 on insulin and glucagon secretion.
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Affiliation(s)
- Dale S Edgerton
- Vanderbilt University Medical Center, Nashville, Tennessee, USA.
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Sandoval DA, Bagnol D, Woods SC, D'Alessio DA, Seeley RJ. Arcuate glucagon-like peptide 1 receptors regulate glucose homeostasis but not food intake. Diabetes 2008; 57:2046-54. [PMID: 18487451 PMCID: PMC2494674 DOI: 10.2337/db07-1824] [Citation(s) in RCA: 255] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
OBJECTIVE Glucagon-like peptide-1 (GLP-1) promotes glucose homeostasis through regulation of islet hormone secretion, as well as hepatic and gastric function. Because GLP-1 is also synthesized in the brain, where it regulates food intake, we hypothesized that the central GLP-1 system regulates glucose tolerance as well. RESEARCH DESIGN AND METHODS We used glucose tolerance tests and hyperinsulinemic-euglycemic clamps to assess the role of the central GLP-1 system on glucose tolerance, insulin secretion, and hepatic and peripheral insulin sensitivity. Finally, in situ hybridization was used to examine colocalization of GLP-1 receptors with neuropeptide tyrosine and pro-opiomelanocortin neurons. RESULTS We found that central, but not peripheral, administration of low doses of a GLP-1 receptor antagonist caused relative hyperglycemia during a glucose tolerance test, suggesting that activation of central GLP-1 receptors regulates key processes involved in the maintenance of glucose homeostasis. Central administration of GLP-1 augmented glucose-stimulated insulin secretion, and direct administration of GLP-1 into the arcuate, but not the paraventricular, nucleus of the hypothalamus reduced hepatic glucose production. Consistent with a role for GLP-1 receptors in the arcuate, GLP-1 receptor mRNA was found to be expressed in 68.1% of arcuate neurons that expressed pro-opiomelanocortin mRNA but was not significantly coexpressed with neuropeptide tyrosine. CONCLUSIONS These data suggest that the arcuate GLP-1 receptors are a key component of the GLP-1 system for improving glucose homeostasis by regulating both insulin secretion and glucose production.
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Affiliation(s)
- Darleen A Sandoval
- Departments of Psychiatry and Medicine, University of Cincinnati, Cincinnati, Ohio, USA.
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31
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Sandoval D. CNS GLP-1 regulation of peripheral glucose homeostasis. Physiol Behav 2008; 94:670-4. [PMID: 18508100 DOI: 10.1016/j.physbeh.2008.04.018] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2008] [Accepted: 04/02/2008] [Indexed: 02/08/2023]
Abstract
Current models hold that peripheral and CNS GLP-1 signaling operate as distinct systems whereby CNS GLP-1 regulates food intake and circulating GLP-1 regulates glucose homeostasis. There is accumulating evidence that the arcuate nucleus, an area of the CNS that regulates energy homeostasis, responds to hormones and nutrients to regulate glucose homeostasis as well. Recent data suggest that GLP-1 may be another signal acting on the arcuate to regulate glucose homeostasis challenging the conventional model of GLP-1 physiology. This review discusses the peripheral and central GLP-1 systems and presents a model whereby these systems are integrated in regulation of glucose homeostasis.
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Affiliation(s)
- Darleen Sandoval
- Department of Psychiatry, Genome Research Institute, University of Cincinnati, Cincinnati, Ohio 45237, USA.
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Keire DA, Whitelegge JP, Bassilian S, Faull KF, Wiggins BW, Mehdizadeh OB, Reidelberger RD, Haver AC, Sayegh AI, Reeve JR. A new endogenous form of PYY isolated from canine ileum: Gly-extended PYY(1-36). ACTA ACUST UNITED AC 2008; 151:61-70. [PMID: 18501442 DOI: 10.1016/j.regpep.2008.04.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2008] [Revised: 03/21/2008] [Accepted: 04/01/2008] [Indexed: 11/30/2022]
Abstract
We purified and identified the peptide YY (PYY) forms present and determined their levels from a portion of the canine ileum directly adjacent to the cecum by a new extraction method designed to prevent and evaluate degradation of endogenous peptides. We used three reverse phase chromatography steps with radioimmunoassay of fractions for PYY-like-immunoreactivity (PYY-LI). The purified fractions underwent intact protein/peptide mass spectrometry identification and sequencing (i.e. "top-down" MS analysis). This analysis confirmed the identity of a new form of PYY, PYY(1-36)-Gly, which co-elutes with PYY(1-36)-NH(2) through all three of separation steps used. The PYY(1-36)-Gly form represents approximately 20% of the total PYY found in this region of the canine intestine. In addition, we also found that the PYY(3-36)-NH(2) form represents 6% of the total PYY in the canine ileo-cecal junction. The physiological implication of the Gly-extended form of PYY(1-36) warrants further investigation.
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Affiliation(s)
- David A Keire
- CURE: Digestive Diseases Research Center, VA GLAHS, Los Angeles, CA 90073 and Digestive Diseases Division, David Geffen School of Medicine at UCLA, Los Angeles, CA 90024, United States
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33
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Abstract
The incretin hormones glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) are physiological gut peptides with insulin-releasing and extrapancreatic glucoregulatory actions. Incretin analogues/mimetics activate GLP-1 or GIP receptors whilst avoiding physiological inactivation by dipeptidyl peptidase 4 (DPP-4), and they represent one of the newest classes of antidiabetic drug. The first clinically approved GLP-1 mimetic for the treatment of type-2 diabetes is exenatide (Byetta/exendin) which is administered subcutaneously twice daily. Clinical trials of liraglutide, a GLP-1 analogue suitable for once-daily administration, are ongoing. A number of other incretin molecules are at earlier stages of development. This review discusses the various attributes of GLP-1 and GIP for diabetes treatment and summarises current clinical data. Additionally, it explores the therapeutic possibilities offered by preclinical agents, such as non-peptide GLP-1 mimetics, GLP-1/glucagon hybrid peptides, and specific GIP receptor antagonists.
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Affiliation(s)
- Brian D Green
- School of Biological Sciences, Queens University Belfast, David Keir Building, Stranmillis Road, Belfast BT6 0NJ, Northern Ireland, UK.
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Bataille D. Pro-protein convertases in intermediary metabolism: islet hormones, brain/gut hormones and integrated physiology. J Mol Med (Berl) 2007; 85:673-84. [PMID: 17356847 DOI: 10.1007/s00109-007-0167-4] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2006] [Revised: 01/18/2007] [Accepted: 01/25/2007] [Indexed: 11/24/2022]
Abstract
Many peptide hormones implicated in the regulation of intermediary metabolism arise from larger precursors called prohormones. These precursors are cut into pieces by proprotein convertases, more precisely those called prohormone convertases (PCs) that cleave at the C terminus of basic doublets. The remaining basic amino acids are eliminated by a specialized carboxypeptidase, leading to the active hormone. This processing may provide, from a single precursor, several peptides with different biological activities depending on the site(s) of cleavage on the precursor. When the processing is tissue-specific, this mechanism allows to produce, from a single protein, different sets of hormones depending on the tissue considered, leading to novel regulatory processes. The archetype of such a pluripotent prohormone in the field of intermediary metabolism is pro-glucagon that, when cut by PC1 in intestinal L cells, produces four different peptides with different specificities [glicentin, oxyntomodulin (OXM), glucagon-like peptide-1, and glucagon-like peptide-2], whereas, when cut by PC2 in the alpha cells of the endocrine pancreas, glucagon is produced and, through the supplementary action of NRD convertase, a fragment of glucagon (miniglucagon) with original properties.
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Affiliation(s)
- Dominique Bataille
- Inserm U376, CHU Arnaud-de-Villeneuve, 34295, Montpellier Cedex 05, France.
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Green BD, Flatt PR, Bailey CJ. Dipeptidyl peptidase IV (DPP IV) inhibitors: A newly emerging drug class for the treatment of type 2 diabetes. Diab Vasc Dis Res 2006; 3:159-65. [PMID: 17160910 DOI: 10.3132/dvdr.2006.024] [Citation(s) in RCA: 135] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Inhibitors of the enzyme dipeptidyl peptidase IV (DPP IV) provide a strategy for the treatment of type 2 diabetes. DPP IV rapidly inactivates the incretin hormones glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP). Inhibition of DPP IV prolongs and enhances the activity of endogenous GLP-1 and GIP, which serve as important prandial stimulators of insulin secretion and regulators of blood glucose control. In clinical trials DPP IV inhibitors (or 'gliptins') have shown efficacy and tolerability in the management of hyperglycaemia in type 2 diabetes, without causing weight gain or hypoglycaemia.
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Affiliation(s)
- Brian D Green
- School of Biological Sciences, Queens University Belfast, Belfast, BT9 5AG, UK.
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Green BD, Flatt PR, Bailey CJ. Inhibition of dipeptidyl peptidase IV activity as a therapy of Type 2 diabetes. Expert Opin Emerg Drugs 2006; 11:525-39. [PMID: 16939389 DOI: 10.1517/14728214.11.3.525] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Dipeptidyl peptidase IV (DPP IV) is a ubiquitous, multifunctional, serine protease enzyme and receptor with roles in the control of endocrine and immune function, cell metabolism, growth and adhesion. As an enzyme, DPP IV cleaves the N-terminal dipeptide from the incretin hormones glucagon-like peptide-1 and glucose-dependent insulinotropic polypeptide. This inactivates the hormones, thereby cancelling their prandial insulinotropic effect. One approach to restore incretin activity as a therapy for Type 2 diabetes has been the development of DPP IV inhibitors. Inhibitors of DPP IV have shown efficacy and tolerability when used to control the hyperglycaemia of noninsulin-dependent animal models and human Type 2 diabetes. These DPP IV inhibitors prolong active incretin hormone concentrations and may exert additional antidiabetic effects. If long-term clinical trials confirm sustained and safe control of blood glucose, DPP IV inhibitors (known as 'gliptins') may be expected to provide a new treatment modality for Type 2 diabetes.
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Affiliation(s)
- Brian D Green
- Queens University Belfast, School of Biological Sciences, David Keir Building, Stranmillis Road, Belfast BT9 5AG, Northern Ireland.
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Jeha GS, Heptulla RA. Newer therapeutic options for children with diabetes mellitus: theoretical and practical considerations. Pediatr Diabetes 2006; 7:122-38. [PMID: 16629719 DOI: 10.1111/j.1399-543x.2006.00159.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Recent studies in adult patients with type 1 diabetes mellitus (T1DM) and T2DM have examined the potential utility, benefits, and side effects of agents that augment insulin secretion after oral ingestion of nutrients in comparison with intravenous nutrient delivery, the so-called incretins. Two families of incretin-like substances are now approved for use in adults. Glucagon-like peptide-1 (GLP-1) or agents that bind to its receptor (exenatide, Byetta) or agents that inhibit its destruction [dipeptidyl peptidase-IV (DPP-IV) inhibitors, Vildagliptin] improve insulin secretion, delay gastric emptying, and suppress glucagon secretion while decreasing food intake without increasing hypoglycemia. Pramlintide, a synthetic amylin analog, also decreases glucagon secretion and delays gastric emptying, improves hemoglobin A1c (HbA1C), and facilitates weight reduction without causing hypoglycemia. We review the historical discovery of these agents, their physiology [corrected] and their current applications. Remarkably, only one or two studies have been reported in children. Pediatricians caring for children with T1DM and T2DM should become familiar with these agents and investigate their applicability, as they seem likely to enhance our therapeutic armamentarium to treat children with diabetes mellitus.
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Affiliation(s)
- George S Jeha
- Department of Pediatrics, Division of Pediatric Endocrinology [corrected] and Metabolism, Texas Children's Hospital, Baylor College of Medicine, Houston, TX 77030, USA
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Ding X, Saxena NK, Lin S, Gupta NA, Gupta N, Anania FA. Exendin-4, a glucagon-like protein-1 (GLP-1) receptor agonist, reverses hepatic steatosis in ob/ob mice. Hepatology 2006; 43:173-81. [PMID: 16374859 PMCID: PMC2925424 DOI: 10.1002/hep.21006] [Citation(s) in RCA: 414] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Nonalcoholic fatty liver disease (NAFLD) represents a burgeoning problem in hepatology, and is associated with insulin resistance. Exendin-4 is a peptide agonist of the glucagon-like peptide (GLP) receptor that promotes insulin secretion. The aim of this study was to determine whether administration of Exendin-4 would reverse hepatic steatosis in ob/ob mice. Ob/ob mice, or their lean littermates, were treated with Exendin-4 [10 microg/kg or 20 microg/kg] for 60 days. Serum was collected for measurement of insulin, adiponectin, fasting glucose, lipids, and aminotransferase concentrations. Liver tissue was procured for histological examination, real-time RT-PCR analysis and assay for oxidative stress. Rat hepatocytes were isolated and treated with GLP-1. Ob/ob mice sustained a reduction in the net weight gained during Exendin-4 treatment. Serum glucose and hepatic steatosis was significantly reduced in Exendin-4 treated ob/ob mice. Exendin-4 improved insulin sensitivity in ob/ob mice, as calculated by the homeostasis model assessment. The measurement of thiobarbituric reactive substances as a marker of oxidative stress was significantly reduced in ob/ob-treated mice with Exendin-4. Finally, GLP-1-treated hepatocytes resulted in a significant increase in cAMP production as well as reduction in mRNA expression of stearoyl-CoA desaturase 1 and genes associated with fatty acid synthesis; the converse was true for genes associated with fatty acid oxidation. In conclusion, Exendin-4 appears to effectively reverse hepatic steatosis in ob/ob mice by improving insulin sensitivity. Our data suggest that GLP-1 proteins in liver have a novel direct effect on hepatocyte fat metabolism.
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Affiliation(s)
- Xiaokun Ding
- Division of Digestive Diseases, Emory University School of Medicine, Atlanta, GA 30322, USA
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De León DD, Crutchlow MF, Ham JYN, Stoffers DA. Role of glucagon-like peptide-1 in the pathogenesis and treatment of diabetes mellitus. Int J Biochem Cell Biol 2005; 38:845-59. [PMID: 16202636 DOI: 10.1016/j.biocel.2005.07.011] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2005] [Revised: 06/28/2005] [Accepted: 07/29/2005] [Indexed: 01/20/2023]
Abstract
Glucagon-like peptide-1 (GLP-1) is an incretin hormone secreted from enteroendocrine L cells in response to ingested nutrients. The first recognized and most important action of GLP-1 is the potentiation of glucose-stimulated insulin secretion in beta-cells, mediated by activation of its seven transmembrane domain G-protein-coupled receptor. In addition to its insulinotropic actions, GLP-1 exerts islet-trophic effects by stimulating replication and differentiation and by decreasing apoptosis of beta-cells. The GLP-1 receptor is expressed in a variety of other tissues important for carbohydrate metabolism, including pancreatic alpha-cells, hypothalamus and brainstem, and proximal intestinal tract. GLP-1 also appears to exert important actions in liver, muscle and fat. Thus, GLP-1 suppresses glucagon secretion, promotes satiety, delays gastric emptying and stimulates peripheral glucose uptake. The impaired GLP-1 secretion observed in type 2 diabetes suggests that GLP-1 plays a role in the pathogenesis of this disorder. Thus, because of its multiple actions, GLP-1 is an attractive therapeutic target for the treatment of type 2 diabetes, and major interest has resulted in the development of a variety of GLP-1 receptor agonists for this purpose. Ongoing clinical trials have shown promising results and the first analogs of GLP-1 are expected to be available in the near future.
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Affiliation(s)
- Diva D De León
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, 19104, USA
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González N, Acitores A, Sancho V, Valverde I, Villanueva-Peñacarrillo ML. Effect of GLP-1 on glucose transport and its cell signalling in human myocytes. ACTA ACUST UNITED AC 2005; 126:203-11. [PMID: 15664668 DOI: 10.1016/j.regpep.2004.10.002] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2004] [Revised: 10/01/2004] [Accepted: 10/01/2004] [Indexed: 11/24/2022]
Abstract
Glucagon-like peptide-1 (GLP-1) controls glucose metabolism in extrapancreatic tissues participating in glucose homeostasis, through receptors not associated to cAMP. In rat hepatocytes, activation of PI3K/PKB, PKC and PP-1 mediates the GLP-1-induced stimulation of glycogen synthase. We have investigated the effect of GLP-1 in normal human myocytes, and that of its structurally related peptides exendin-4 (Ex-4) and its truncated form 9-39 (Ex-9) upon glucose uptake, and the participation of cellular enzymes proposed to mediate insulin actions. GLP-1 and both exendins activated, like insulin, PI3K/PKB and p42/44 MAPK enzymes, but p70s6k was activated only by GLP-1 and insulin. GLP-1, Ex-4 and Ex-9, like insulin, stimulated glucose uptake; wortmannin blocked the action of GLP-1, insulin and Ex-9, and reduced that of Ex-4; PD98059 abolished the effect of all peptides/hormones, while rapamycin blocked that of insulin and partially prevented that of GLP-1. H-7 abolished the action of GLP-1, insulin and Ex-4, while Ro 31-8220 prevented only the Ex-4 and Ex-9 effect. In conclusion, GLP-1, like insulin, stimulates glucose uptake, and this involves activation of PI3K/PKB, p44/42 MAPKs, partially p70s6k, and possibly PKC; Ex-4 and Ex-9 both have GLP-1-like effect upon glucose transport, in which both share with GLP-1 an activation of PI3K/PKB--partially in the case of Ex-4--and p44/42 MAPKs but not p70s6k.
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Affiliation(s)
- Nieves González
- Department of Metabolism, Nutrition and Hormones, Fundación Jiménez Díaz, Avda. Reyes Católicos 2, 28040-Madrid, Spain
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Furman B, Pyne N, Flatt P, O'Harte F. Targeting beta-cell cyclic 3'5' adenosine monophosphate for the development of novel drugs for treating type 2 diabetes mellitus. A review. J Pharm Pharmacol 2005; 56:1477-92. [PMID: 15563754 DOI: 10.1211/0022357044805] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
Cyclic 3'5'AMP is an important physiological amplifier of glucose-induced insulin secretion by the pancreatic islet beta-cell, where it is formed by the activity of adenylyl cyclase, especially in response to the incretin hormones GLP-1 (glucagon-like peptide-1) and GIP (glucose-dependent insulinotropic peptide). These hormones are secreted from the small intestine during and following a meal, and are important in producing a full insulin secretory response to nutrient stimuli. Cyclic AMP influences many steps involved in glucose-induced insulin secretion and may be important in regulating pancreatic islet beta-cell differentiation, growth and survival. Cyclic AMP (cAMP) itself is rapidly degraded in the pancreatic islet beta-cell by cyclic nucleotide phosphodiesterase (PDE) enzymes. This review discusses the possibility of targeting cAMP mechanisms in the treatment of type 2 diabetes mellitus, in which insulin release in response to glucose is impaired. This could be achieved by the use of GLP-1 or GIP to elevate cAMP in the pancreatic islet beta-cell. However, these peptides are normally rapidly degraded by dipeptidyl peptidase IV (DPP IV). Thus longer-acting analogues of GLP-1 and GIP, resistant to enzymic degradation, and orally active inhibitors of DPP IV have also been developed, and these agents were found to improve metabolic control in experimentally diabetic animals and in patients with type 2 diabetes. The use of selective inhibitors of type 3 phosphodiesterase (PDE3B), which is probably the important pancreatic islet beta-cell PDE isoform, would require their targeting to the islet beta-cell, because inhibition of PDE3B in adipocytes and hepatocytes would induce insulin resistance.
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Affiliation(s)
- Brian Furman
- Department of Physiology and Pharmacology, University of Strathclyde, Strathclyde Institute for Biomedical Sciences, Taylor Street, Glasgow G4 ONR, UK.
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Green BD, Gault VA, Flatt PR, Harriott P, Greer B, O'Harte FPM. Comparative effects of GLP-1 and GIP on cAMP production, insulin secretion, and in vivo antidiabetic actions following substitution of Ala8/Ala2 with 2-aminobutyric acid. Arch Biochem Biophys 2004; 428:136-43. [PMID: 15246869 DOI: 10.1016/j.abb.2004.05.005] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2004] [Revised: 05/06/2004] [Indexed: 01/06/2023]
Abstract
The two major incretin hormones, glucagon-like peptide-1 (GLP-1), and glucose-dependent insulinotropic polypeptide (GIP), are currently being considered as prospective drug candidates for treatment of type 2 diabetes. Interest in these gut hormones was initially spurred by their potent insulinotropic activities, but a number of other antihyperglycaemic actions are now established. One of the foremost barriers in progressing GLP-1 and GIP to the clinic concerns their rapid degradation and inactivation by the ubiquitous enzyme, dipeptidyl peptidase IV (DPP IV). Here, we compare the DPP IV resistance and biological properties of Abu8/Abu2 (2-aminobutyric acid) substituted analogues of GLP-1 and GIP engineered to impart DPP IV resistance. Whereas (Abu8)GLP-1 was completely stable to human plasma (half-life >12 h), GLP-1, GIP, and (Abu2)GIP were rapidly degraded (half-lives: 6.2, 6.0, and 7.1 h, respectively). Native GIP, GLP-1, and particularly (Abu8)GLP-1 elicited significant adenylate cyclase and insulinotropic activity, while (Abu2)GIP was less effective. Similarly, in obese diabetic (ob/ob) mice, GIP, GLP-1, and (Abu8)GLP-1 displayed substantial glucose-lowering and insulin-releasing activities, whereas (Abu2)GIP was only weakly active. These studies illustrate divergent effects of penultimate amino acid Ala8/Ala2 substitution with Abu on the biological properties of GLP-1 and GIP, suggesting that (Abu8)GLP-1 represents a potential candidate for future therapeutic development.
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Affiliation(s)
- B D Green
- School of Biomedical Sciences, University of Ulster, Coleraine BT52 1SA, Northern Ireland, UK.
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43
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Green BD, Gault VA, Mooney MH, Irwin N, Harriott P, Greer B, Bailey CJ, O'Harte FPM, Flatt PR. Degradation, receptor binding, insulin secreting and antihyperglycaemic actions of palmitate-derivatised native and Ala8-substituted GLP-1 analogues. Biol Chem 2004; 385:169-77. [PMID: 15101559 DOI: 10.1515/bc.2004.035] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The hormone glucagon-like peptide-1(7-36)amide (GLP-1) is released in response to ingested nutrients and acts to promote glucose-dependent insulin secretion ensuring efficient postprandial glucose homeostasis. Unfortunately, the beneficial actions of GLP-1 which give this hormone many of the desirable properties of an antidiabetic drug are short lived due to degradation by dipeptidyl-peptidase IV (DPP IV) and rapid clearance by renal filtration. In this study we have attempted to extend GLP-1 action through the attachment of palmitoyl moieties to the epsilon-amino group in the side chain of the Lys26 residue and to combine this modification with substitutions of the Ala8 residue, namely Val or amino-butyric acid (Abu). In contrast to native GLP-1, which was rapidly degraded, [Lys(pal)26]GLP-1, [Abu8, Lys(pal)26]GLP-1 and [Val8 Lys(pal)26]GLP-1 all exhibited profound stability during 12 h incubations with DPP IV and human plasma. Receptor binding affinity and the ability to increase cyclic AMP in the clonal beta-cell line BRIN-BD11 were decreased by 86- to 167-fold and 15- to 62-fold, respectively compared with native GLP-1. However, insulin secretory potency tested using BRIN-BD11 cells was similar, or in the case of [Val8,Lys(pal)26]GLP-1 enhanced. Furthermore, when administered in vivo together with glucose to diabetic (ob/ob) mice, [Lys(pal)26]GLP-1, [Abu8,Lys(pal)26]GLP-1 and [Val8,Lys(pal)26]GLP-1 did not demonstrate acute glucose-lowering or insulinotropic activity as observed with native GLP-1. These studies support the potential usefulness of fatty acid linked analogues of GLP-1 but indicate the importance of chain length for peptide kinetics and bioavailability.
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Affiliation(s)
- Brian D Green
- School of Biomedical Sciences, University of Ulster, Coleraine BT52 1SA, Northern Ireland, UK.
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Meier JJ, Gallwitz B, Nauck MA. Glucagon-like peptide 1 and gastric inhibitory polypeptide: potential applications in type 2 diabetes mellitus. BioDrugs 2004; 17:93-102. [PMID: 12641488 DOI: 10.2165/00063030-200317020-00002] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Although the insulinotropic actions of gastric inhibitory polypeptide (GIP) and glucagon-like peptide 1 (GLP-1) have been known for almost 2 decades, the incretin hormones have not yet become available for clinical application. This can be explained by their unfavourable pharmacological properties. Both hormones are rapidly inactivated by the enzyme dipeptidyl peptidase IV (DPP IV), yielding biologically inactive fragments. There have been several attempts to make use of the antidiabetogenic potential of the incretin hormones. Various analogues of GLP-1 and GIP have been generated in order to achieve resistance to DPP IV degradation. The natural GLP-1 receptor agonist exendin-4, found in the saliva of the Gila monster, has a longer biological half-life after subcutaneous injection than GLP-1, and inhibition of DPP IV using, for example, pyrrolidine derivatives provides elevated concentrations of intact, biologically active GIP and GLP-1 endogenously released from the gut. A continuous intravenous infusion of native GLP-1 for a limited time may be suitable in certain clinical situations. Numerous clinical studies are currently underway to evaluate these approaches. Therefore, an antidiabetic treatment based on incretin hormones may become available within the next 5 years.
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Affiliation(s)
- Juris J Meier
- Medizinische Klinik I, St. Josef-Hospital, Klinikum der Ruhr-Universität Bochum, Bochum, Germany
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Nishizawa M, Moore MC, Shiota M, Gustavson SM, Snead WL, Neal DW, Cherrington AD. Effect of intraportal glucagon-like peptide-1 on glucose metabolism in conscious dogs. Am J Physiol Endocrinol Metab 2003; 284:E1027-36. [PMID: 12569088 DOI: 10.1152/ajpendo.00503.2002] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Arteriovenous difference and tracer ([3-(3)H]glucose) techniques were used in 42-h-fasted conscious dogs to identify any insulin-like effects of intraportally administered glucagon-like peptide 1-(7-36)amide (GLP-1). Each study consisted of an equilibration, a basal, and three 90-min test periods (P1, P2, and P3) during which somatostatin, intraportal insulin (3-fold basal) and glucagon (basal), and peripheral glucose were infused. Saline was infused intraportally in P1. During P2 and P3, GLP-1 was infused intraportally at 0.9 and 5.1 pmol. kg(-1). min(-1) in eight dogs, at 10 and 20 pmol. kg(-1). min(-1) in seven dogs, and at 0 pmol. kg(-1). min(-1) in eight dogs (control group). Net hepatic glucose uptake was significantly enhanced during GLP-1 infusion at 20 pmol. kg(-1). min(-1) [21.8 vs. 13.4 micromol. kg(-1). min(-1) (control), P < 0.05]. Glucose utilization was significantly increased during infusion at 10 and 20 pmol. kg(-1). min(-1) [87.3 +/- 8.3 and 105.3 +/- 12.8, respectively, vs. 62.2 +/- 5.3 and 74.7 +/- 7.4 micromol. kg(-1). min(-1) (control), P < 0.05]. The glucose infusion rate required to maintain hyperglycemia was increased (P < 0.05) during infusion of GLP-1 at 5.1, 10, and 20 pmol. kg(-1). min(-1) (22, 36, and 32%, respectively, greater than control). Nonhepatic glucose uptake increased significantly during delivery of GLP-1 at 5.1 and 10 pmol. kg(-1). min(-1) (25 and 46% greater than control) and tended (P = 0.1) to increase during GLP-1 infusion at 20 pmol. kg(-1). min(-1) (24% greater than control). Intraportal infusion of GLP-1 at high physiological and pharmacological rates increased glucose disposal primarily in nonhepatic tissues.
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Affiliation(s)
- Makoto Nishizawa
- Department of Molecular Physiology & Biophysics, Diabetes Research and Training Center, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
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Ikezawa Y, Yamatani K, Ohnuma H, Daimon M, Manaka H, Sasaki H. Glucagon-like peptide-1 inhibits glucagon-induced glycogenolysis in perivenous hepatocytes specifically. REGULATORY PEPTIDES 2003; 111:207-10. [PMID: 12609770 DOI: 10.1016/s0167-0115(02)00287-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Hepatocytes form the hepatic acinus as a unit of microcirculation. Following the bloodstream, at least two different zones can be discerned: the periportal (PPH) and the perivenous (PVH) zones. Recently, we found that insulin inhibits glucagon-induced glycogenolysis in PVH specifically. We therefore investigated the region-specific functional effects of glucagon-like peptide-1 (GLP-1), which is known to have an insulin-like activity, on glucagon-induced glycogenolysis in isolated PPH and PVH prepared by the digitonin-collagenase method. GLP-1 inhibited 0.1 nM glucagon-induced increase in glucose release from the PVH of fed rats specifically (p < 0.01) and had an additive effect with insulin. Insulin binding did not differ between PPH and PVH of fed rats. GLP-1 did not displace [125I]-glucagon binding to the purified hepatic cell membrane. Thus, it is directly confirmed that GLP-1 has an insulin-like activity in the liver.
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Affiliation(s)
- Yoshihiro Ikezawa
- The Third Department of Internal Medicine, Yamagata University School of Medicine, 2-2-2 Iidanishi, Yamagata 990-9585, Japan
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Meneilly GS, McIntosh CHS, Pederson RA, Habener JF, Ehlers MRW, Egan JM, Elahi D. Effect of glucagon-like peptide 1 (7-36 amide) on insulin-mediated glucose uptake in patients with type 1 diabetes. Diabetes Care 2003; 26:837-42. [PMID: 12610046 DOI: 10.2337/diacare.26.3.837] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
OBJECTIVE To examine the insulinomimetic insulin-independent effects of glucagon-like peptide (GLP)-1 on glucose uptake in type 1 diabetic patients. RESEARCH DESIGN AND METHODS We used the hyperinsulinemic-euglycemic clamp (480 pmol. m(-2) x min(-1)) in paired randomized studies of six women and five men with type 1 diabetes. In the course of one of the paired studies, the subjects also received GLP-1 at a dose of 1.5 pmol. kg(-1) x min(-1). The patients were 41 +/- 3 years old with a BMI of 25 +/- 1 kg/m(2). The mean duration of diabetes was 23 +/- 3 years. RESULTS Plasma glucose was allowed to fall from a fasting level of approximately 11 mmol/l to 5.3 mmol/l in each study and thereafter was held stable at that level. Plasma insulin levels during both studies were approximately 900 pmol/l. Plasma C-peptide levels did not change during the studies. In the GLP-1 study, plasma total GLP-1 levels were elevated from the fasting level of 31 +/- 3 to 150 +/- 17 pmol/l. Plasma glucagon levels fell from the fasting levels of approximately 14 pmol/l to 9 pmol/l during both paired studies. Hepatic glucose production was suppressed during the glucose clamps in all studies. Glucose uptake was not different between the two studies ( approximately 40 micromol. kg(-1) x min(-1)). CONCLUSIONS GLP-1 does not augment insulin-mediated glucose uptake in lean type 1 diabetic patients.
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Affiliation(s)
- Graydon S Meneilly
- Department of Medicine, University of British Columbia, Vancouver, British Columbia, Canada
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48
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Abstract
GLP-1 is a peptide hormone from the intestinal mucosa. It is secreted in response to meal ingestion and normally functions in the so-called ileal brake, that is, inhibition of upper gastrointestinal motility and secretion when nutrients are present in the distal small intestine. It also induces satiety and promotes tissue deposition of ingested glucose by stimulating insulin secretion. Thus, it is an essential incretin hormone. In addition, the hormone has been demonstrated to promote insulin biosynthesis and insulin gene expression and to have trophic effects on the beta cells. The trophic effects include proliferation of existing beta cells, maturation of new cells from duct progenitor cells and inhibition of apoptosis. Furthermore, glucagon secretion is inhibited. Because of these effects, the hormone effectively improves metabolism in patients with type 2 diabetes mellitus. Thus, continuous subcutaneous administration of the peptide for six weeks in patients with rather advanced disease greatly improved glucose profiles and lowered body weight, haemoglobin A(1C), and free fatty acids (FFA). In addition, insulin sensitivity doubled and insulin responses to glucose were greatly improved. There were no side effects. Continuous administration is necessary because of rapid degradation by the enzyme dipeptidyl peptidase-IV. Alternative approaches include the use of analogues that are resistant to the actions of the enzyme, as well as inhibitors of the enzyme. Both approaches have shown remarkable efficacy in both experimental and clinical studies. The GLP-1-based therapy of type 2 diabetes, therefore, represents a new and attractive alternative.
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Affiliation(s)
- Jens Juul Holst
- Department of Medical Physiology, University of Copenhagen, The Panum Institute, Copenhagen N, Denmark.
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Meier JJ, Gallwitz B, Schmidt WE, Nauck MA. Glucagon-like peptide 1 as a regulator of food intake and body weight: therapeutic perspectives. Eur J Pharmacol 2002; 440:269-79. [PMID: 12007541 DOI: 10.1016/s0014-2999(02)01434-6] [Citation(s) in RCA: 103] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
After ingestion of carbohydrate- and fat-rich meals, the incretin hormone glucagon-like peptide 1 (GLP-1) is secreted from the L-cells in the distal put into the circulation. Its major physiological effect lies in a strongly glucose-dependent stimulation of insulin secretion from pancreatic B-cells. Furthermore, GLP-1 suppresses glucagon secretion, stimulates B-cell neogenesis as well as proinsulin biosynthesis and inhibits gastric emptying and acid secretion. Recently, GLP-1 could be shown to reduce caloric intake and to enhance satiety, most likely via specific receptors within the central nervous system, resulting in reduced weight gain in experimental animals. In nondiabetic and Type 2 diabetic human subjects, exogenous GLP-1 reduces hunger, caloric intake and body weight. Therefore, in addition to its well-characterized antidiabetogenic effect, the anorectic effect may offer GLP-1 a potential in the pharmacotherapy of obesity. It is still unknown whether the GLP-1 effect on caloric intake is sustained after long-term treatment. Furthermore, the exact mechanisms by which the peptide exerts its biological effects have not yet been clarified. Due to the rapid degradation of native GLP-1, its therapeutic application is limited by the short half-life. Therefore, suitable modes of administration are needed in order to reach stable plasma concentrations. The present review aims to describe the role of GLP-1 in the central regulation of feeding and to discuss its possible application in the pharmacotherapy of obesity.
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Affiliation(s)
- Juris J Meier
- Medizinische Klinik I, St. Josef-Hospital, Klinikum der Ruhr-Universität Bochum, Gudrunstr. 56, Germany
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Deacon CF, Plamboeck A, Møller S, Holst JJ. GLP-1-(9-36) amide reduces blood glucose in anesthetized pigs by a mechanism that does not involve insulin secretion. Am J Physiol Endocrinol Metab 2002; 282:E873-9. [PMID: 11882507 DOI: 10.1152/ajpendo.00452.2001] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Glucagon-like peptide 1 (GLP-1) is a potent anti-hyperglycemic hormone currently under investigation for its therapeutic potential. However, due to rapid degradation by dipeptidyl peptidase IV (DPP IV), which limits its metabolic stability and eliminates its insulinotropic activity, it has been impossible to assess its true efficacy in vivo. In chloralose-anesthetized pigs given valine-pyrrolidide (to block endogenous DPP IV activity), the independent effects of GLP-1-(7-36) amide on glucose and insulin responses to intravenous glucose were assessed, and the metabolite generated by DPP IV, GLP-1-(9-36) amide, was investigated for any ability to influence these responses. GLP-1-(7-36) amide enhanced insulin secretion (P < 0.03 vs. vehicle), but GLP-1-(9-36) amide was without effect, either alone or when coinfused with GLP-1-(7-36) amide. In contrast, GLP-1-(9-36) amide did affect glucose responses (P < 0.03). Glucose excursions were greater after saline (121 +/- 17 mmol x l(-1) x min) than after GLP-1-(9-36) amide (73 +/- 19 mmol x l(-1) x min; P < 0.05), GLP-1-(7-36) amide (62 +/- 13 mmol x l(-1) x min; P < 0.02) or GLP-1-(7-36) amide + GLP-1-(9-36) amide (50 +/-13 mmol x l(-1) x min; P < 0.005). Glucose elimination rates were faster after GLP-1-(7-36) amide + (9-36) amide (10.3 +/- 1.2%/min) than after GLP-1-(7-36) amide (7.0 +/- 0.9%/min; P < 0.04), GLP-1-(9-36) amide (6.8 +/- 1.0%/min; P < 0.03), or saline (5.4 +/- 1.2%/min; P < 0.005). Glucagon concentrations were unaffected. These results demonstrate that GLP-1-(9-36) amide neither stimulates insulin secretion nor antagonizes the insulinotropic effect of GLP-1-(7-36) amide in vivo. Moreover, the metabolite itself possesses anti-hyperglycemic effects, supporting the hypothesis that selective DPP IV action is important in glucose homeostasis.
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Affiliation(s)
- Carolyn F Deacon
- Department of Medical Physiology, The Panum Institute, University of Copenhagen, DK-2200 Copenhagen, Denmark.
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