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Myat A, Arri S, Bhatt DL, Gersh BJ, Redwood SR, Marber MS. Design and rationale for the randomised, double-blinded, placebo-controlled Liraglutide to Improve corONary haemodynamics during Exercise streSS (LIONESS) crossover study. Cardiovasc Diabetol 2015; 14:27. [PMID: 25848859 PMCID: PMC4358711 DOI: 10.1186/s12933-015-0193-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/26/2015] [Accepted: 02/07/2015] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND Glucagon-like peptide-1 is an incretin hormone essential for normal human glucose homeostasis. Expression of the glucagon-like peptide-1 receptor in the myocardium has fuelled growing interest in the direct and indirect cardiovascular effects of native glucagon-like peptide-1, its degradation product glucagon-like peptide-1(9-36), and the synthetic glucagon-like peptide-1 receptor agonists. Preclinical studies have demonstrated cardioprotective actions of all three compounds in the setting of experimental myocardial infarction and left ventricular systolic dysfunction. This has led to Phase 2 trials of native glucagon-like peptide-1 and incretin-based therapies in humans with and without Type 2 diabetes mellitus. These studies have demonstrated the ability of glucagon-like peptide-1, independent of glycaemic control, to positively modulate the metabolic and haemodynamic parameters of individuals with coronary artery disease and left ventricular systolic dysfunction. We aim to add to this growing body of evidence by studying the effect of chronic glucagon-like peptide-1 receptor activation on exercise-induced ischaemia in patients with chronic stable angina managed conservatively or awaiting revascularisation. The hypothesis being liraglutide, a subcutaneously injectable glucagon-like peptide-1 receptor agonist, is able to improve exercise haemodynamics in patients with obstructive coronary artery disease when compared with saline placebo. METHODS AND DESIGN The Liraglutide to Improve corONary haemodynamics during Exercise streSS (LIONESS) trial is an investigator-initiated single-centre randomised double-blinded placebo-controlled crossover proof-of-principle physiological study. Primary endpoints are change in rate pressure product at 0.1 mV ST-segment depression and change in degree of ST-segment depression at peak exercise during sequential exercise tolerance testing performed over a 6-week study period in which 26 patients will be randomised to either liraglutide or saline with crossover to the opposing regimen at week 3. DISCUSSION The study will be conducted in accordance with the principles of Good Clinical Practice and the Declaration of Helsinki. The local Research Ethics Committee and Medicines and Healthcare Products Regulatory Agency have approved the study. TRIAL REGISTRATION National Institute of Health Research Clinical Research Network (NIHR CRN) Portfolio ID 11112 and ClinicalTrials.gov Identifier NCT02315001.
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Affiliation(s)
- Aung Myat
- />King’s College London British Heart Foundation Centre of Research Excellence, The Rayne Institute, Cardiovascular Division, St Thomas’ Hospital, Westminster Bridge Road, London, SE1 7EH UK
| | - Satpal Arri
- />King’s College London British Heart Foundation Centre of Research Excellence, The Rayne Institute, Cardiovascular Division, St Thomas’ Hospital, Westminster Bridge Road, London, SE1 7EH UK
| | - Deepak L Bhatt
- />Brigham and Women’s Hospital Heart & Vascular Centre and Harvard Medical School, Boston, MA 02115 USA
| | - Bernard J Gersh
- />Division of Cardiovascular Diseases, Mayo Clinic College of Medicine, 200 First Street SW, Rochester, MN 55905 USA
| | - Simon R Redwood
- />King’s College London British Heart Foundation Centre of Research Excellence, The Rayne Institute, Cardiovascular Division, St Thomas’ Hospital, Westminster Bridge Road, London, SE1 7EH UK
| | - Michael S Marber
- />King’s College London British Heart Foundation Centre of Research Excellence, The Rayne Institute, Cardiovascular Division, St Thomas’ Hospital, Westminster Bridge Road, London, SE1 7EH UK
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Abstract
The enteroendocrine system is the primary sensor of ingested nutrients and is responsible for secreting an array of gut hormones, which modulate multiple physiological responses including gastrointestinal motility and secretion, glucose homeostasis, and appetite. This Review provides an up-to-date synopsis of the molecular mechanisms underlying enteroendocrine nutrient sensing and highlights our current understanding of the neuro-hormonal regulation of gut hormone secretion, including the interaction between the enteroendocrine system and the enteric nervous system. It is hoped that a deeper understanding of how these systems collectively regulate postprandial physiology will further facilitate the development of novel therapeutic strategies.
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Ripken D, van der Wielen N, van der Meulen J, Schuurman T, Witkamp R, Hendriks H, Koopmans S. Cholecystokinin regulates satiation independently of the abdominal vagal nerve in a pig model of total subdiaphragmatic vagotomy. Physiol Behav 2015; 139:167-76. [DOI: 10.1016/j.physbeh.2014.11.031] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2014] [Revised: 09/16/2014] [Accepted: 11/10/2014] [Indexed: 11/25/2022]
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Vinet L, Lamprianou S, Babič A, Lange N, Thorel F, Herrera PL, Montet X, Meda P. Targeting GLP-1 receptors for repeated magnetic resonance imaging differentiates graded losses of pancreatic beta cells in mice. Diabetologia 2015; 58:304-12. [PMID: 25413047 PMCID: PMC4287680 DOI: 10.1007/s00125-014-3442-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/19/2014] [Accepted: 10/17/2014] [Indexed: 12/22/2022]
Abstract
AIMS/HYPOTHESIS Non-invasive imaging of beta cells is a much-needed development but is one that faces significant biological and technological hurdles. A relevant imaging method should at least allow for an evaluation over time of the mass of beta cells under physiological and pathological conditions, and for an assessment of novel therapies. We, therefore, investigated the ability of a new MRI probe to repeatedly measure the loss of beta cells in a rodent model. METHODS We developed an innovative nanoparticle probe that targets the glucagon-like peptide 1 receptor, and can be used for both fluorescence imaging and MRI. Using fluorescence, we characterised the specificity and biodistribution of the probe. Using 1.5 T MRI, we longitudinally imaged the changes in insulin content in male and female mice of the RIP-DTr strain, which mimic the changes expected in type 1 and type 2 diabetes, respectively. RESULTS We showed that this probe selectively labelled beta cells in situ, imaged in vivo native pancreatic islets and evaluated their loss after diphtheria toxin administration, in a model of graded beta cell deletion. Thus, using clinical MRI, the probe quantitatively differentiates, in the same mouse strain, between female animals featuring a 50% loss of beta cells and the males featuring an almost complete loss of beta cells. CONCLUSIONS/INTERPRETATION The approach addresses several of the hurdles that have so far limited the non-invasive imaging of beta cells, including the potential to repeatedly monitor the very same animals using clinically available equipment, and to differentiate graded losses of beta cells.
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Affiliation(s)
- Laurent Vinet
- Department of Genetic Medicine and Development, University of Geneva, Geneva, CMU, 1 rue Michel-Servet, CH-1211, Geneva 4, Switzerland,
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305
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Scarlett JM, Schwartz MW. Gut-brain mechanisms controlling glucose homeostasis. F1000PRIME REPORTS 2015; 7:12. [PMID: 25705395 PMCID: PMC4311273 DOI: 10.12703/p7-12] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Grants] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Our current understanding of glucose homeostasis is centered on glucose-induced secretion of insulin from pancreatic islets and insulin action on glucose metabolism in peripheral tissues. In addition, however, recent evidence suggests that neurocircuits located within a brain-centered glucoregulatory system work cooperatively with pancreatic islets to promote glucose homeostasis. Among key observations is evidence that, in addition to insulin-dependent mechanisms, the brain has the capacity to potently lower blood glucose levels via mechanisms that are insulin-independent, some of which are activated by signals emanating from the gastrointestinal tract. This review highlights evidence supporting a key role for a “gut-brain-liver axis” in control of glucose homeostasis by the brain-centered glucoregulatory system and the implications of this regulatory system for diabetes pathogenesis and treatment.
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Affiliation(s)
- Jarrad M. Scarlett
- Diabetes and Obesity Center of Excellence, Department of Medicine, University of Washington at South Lake Union850 Republican Street, N335, Box 358055, Seattle, WA 98195USA
- Department of Pediatric Gastroenterology and Hepatology, Seattle Children's HospitalOB.9.620.1, P.O. Box 5371, Seattle, WA 98105USA
| | - Michael W. Schwartz
- Diabetes and Obesity Center of Excellence, Department of Medicine, University of Washington at South Lake Union850 Republican Street, N335, Box 358055, Seattle, WA 98195USA
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306
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Korol SV, Jin Z, Babateen O, Birnir B. GLP-1 and exendin-4 transiently enhance GABAA receptor-mediated synaptic and tonic currents in rat hippocampal CA3 pyramidal neurons. Diabetes 2015; 64:79-89. [PMID: 25114295 DOI: 10.2337/db14-0668] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Glucagon-like peptide-1 (GLP-1) is a hormone that stimulates insulin secretion. Receptors for GLP-1 are also found in the brain, including the hippocampus, the center for memory and learning. Diabetes is a risk factor for decreased memory functions. We studied effects of GLP-1 and exendin-4, a GLP-1 receptor agonist, on γ-aminobutyric acid (GABA) signaling in hippocampal CA3 pyramidal neurons. GABA is the main inhibitory neurotransmitter and decreases neuronal excitability. GLP-1 (0.01-1 nmol/L) transiently enhanced synaptic and tonic currents, and the effects were blocked by exendin (9-39). Ten pmol/L GLP-1 increased both the spontaneous inhibitory postsynaptic current (sIPSC) amplitudes and frequency by a factor of 1.8. In 0.1, 1 nmol/L GLP-1 or 10, 50, or 100 nmol/L exendin-4, only the sIPSC frequency increased. The tonic current was enhanced by 0.01-1 nmol/L GLP-1 and by 0.5-100 nmol/L exendin-4. When action potentials were inhibited by tetrodotoxin (TTX), inhibitory postsynaptic currents decreased and currents were no longer potentiated by GLP-1 or exendin-4. In contrast, although the tonic current decreased in TTX, it was still enhanced by GLP-1 or exendin-4. The results demonstrate GLP-1 receptor regulation of hippocampal function and are consistent with GLP-1 receptor agonists enhancing GABAA signaling by pre- and postsynaptic mechanisms.
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Affiliation(s)
- Sergiy V Korol
- Department of Neuroscience, Uppsala University, Uppsala, Sweden
| | - Zhe Jin
- Department of Neuroscience, Uppsala University, Uppsala, Sweden
| | - Omar Babateen
- Department of Neuroscience, Uppsala University, Uppsala, Sweden
| | - Bryndis Birnir
- Department of Neuroscience, Uppsala University, Uppsala, Sweden
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307
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Bisschop PH, Fliers E, Kalsbeek A. Autonomic Regulation of Hepatic Glucose Production. Compr Physiol 2014; 5:147-65. [DOI: 10.1002/cphy.c140009] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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308
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Consoli A, Formoso G. Potential side effects to GLP-1 agonists: understanding their safety and tolerability. Expert Opin Drug Saf 2014; 14:207-18. [PMID: 25496749 DOI: 10.1517/14740338.2015.987122] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
INTRODUCTION Glucagon-like peptide 1 receptor (GLP-1Rx) agonists might elicit unwelcome side effects and concerns have recently been raised about their safety. AREAS COVERED Available evidence about safety, tolerability and potential adverse events relative to GLP-1Rx agonists presently used. We searched the MEDLINE database using the terms: 'GLP-1 receptor agonists', 'Incretin therapy side effects', 'exenatide', ' liraglutide', 'exenatide long-acting release', 'lixisenatide'. Articles were selected on the basis of the study design and importance, in the light of authors' clinical experience and personal judgment. The main safety concern about GLP-1Rx agonists use is the possible association with increased risk of pancreatitis and/or tumors. This concern stems mainly from limited observations in animal models not confirmed in similar studies. Furthermore, clinical studies reporting association between GLP-1Rx agonist use and pancreatitis/cancer are marred by several biases and both clinical trials and post-marketing analyses failed to demonstrate a significant association. EXPERT OPINION As stated by both FDA and EMA, the safety concerns emerged so far about GLP-1RX agonists should not affect present prescribing habits. Thus, although a strict data monitoring must be encouraged, they should not prevent access to the benefits of an innovative treatment, such as GLP-1Rx agonists use, to a large diabetic population still confronted with unmet needs.
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Affiliation(s)
- Agostino Consoli
- G. d'Annunzio University, Department of Medicine and Aging Sciences , Edificio CeSi, Room 271, Via Colle dell'Ara 1, 66100 Chieti , Italy +39 0871 541339 ; +39 0871 541307 ;
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309
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Tate M, Chong A, Robinson E, Green BD, Grieve DJ. Selective targeting of glucagon-like peptide-1 signalling as a novel therapeutic approach for cardiovascular disease in diabetes. Br J Pharmacol 2014; 172:721-36. [PMID: 25231355 DOI: 10.1111/bph.12943] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2014] [Revised: 08/21/2014] [Accepted: 09/14/2014] [Indexed: 12/21/2022] Open
Abstract
Glucagon-like peptide-1 (GLP-1) is an incretin hormone whose glucose-dependent insulinotropic actions have been harnessed as a novel therapy for glycaemic control in type 2 diabetes. Although it has been known for some time that the GLP-1 receptor is expressed in the CVS where it mediates important physiological actions, it is only recently that specific cardiovascular effects of GLP-1 in the setting of diabetes have been described. GLP-1 confers indirect benefits in cardiovascular disease (CVD) under both normal and hyperglycaemic conditions via reducing established risk factors, such as hypertension, dyslipidaemia and obesity, which are markedly increased in diabetes. Emerging evidence indicates that GLP-1 also exerts direct effects on specific aspects of diabetic CVD, such as endothelial dysfunction, inflammation, angiogenesis and adverse cardiac remodelling. However, the majority of studies have employed experimental models of diabetic CVD and information on the effects of GLP-1 in the clinical setting is limited, although several large-scale trials are ongoing. It is clearly important to gain a detailed knowledge of the cardiovascular actions of GLP-1 in diabetes given the large number of patients currently receiving GLP-1-based therapies. This review will therefore discuss current understanding of the effects of GLP-1 on both cardiovascular risk factors in diabetes and direct actions on the heart and vasculature in this setting and the evidence implicating specific targeting of GLP-1 as a novel therapy for CVD in diabetes.
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Affiliation(s)
- Mitchel Tate
- Centre for Experimental Medicine, Queen's University Belfast, Belfast, UK
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310
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Wada R, Yagihashi S. The expression of glucagon-like peptide-1 receptor and dipeptidyl peptidase-IV in neuroendocrine neoplasms of the pancreas and gastrointestinal tract. Endocr Pathol 2014; 25:390-6. [PMID: 25119061 DOI: 10.1007/s12022-014-9326-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Neuroendocrine neoplasm (NEN) of the pancreas and gastrointestinal tract is infrequent but often produces hormones to cause distinct clinical features. Glucagon-like peptide-1 receptor (GLP1R) is a G-protein coupled receptor for GLP1, which is cleaved by dipeptidyl peptidase (DPP)-IV, a peptidase that regulates the activity of peptide hormones. Since these molecules are involved in the neuroendocrine function of NEN, they could serve molecular targets for diagnosis and therapy of NEN. However, the expressions of these molecules in NEN are not well studied. We therefore examined the expression of GLP1R and DPP-IV in 22 cases of pancreatic NEN (P-NEN) and 20 cases of gastrointestinal NEN (GI-NEN) by immunostaining. GLP1R was expressed in all eight insulinomas (100 %) but so in only four out of 14 cases (29 %) of non-insulinomas. In contrast to GLP1R, DPP-IV was detected in one out of eight insulinomas (13 %) and in 12 out of 14 cases (86 %) of non-insulinomas. In GI-NEN, GLP1R was negative in all 10 cases of the foregut NEN, whereas it was expressed in all three cases (100 %) of midgut NEN and four out of seven cases (57 %) of hindgut NEN. DPP-IV was expressed in five out of 10 cases (50 %) of the foregut NEN. The expression was detected in two out of three cases (67 %) of midgut NEN and in all seven cases (100 %) of hindgut NEN. In conclusion, we found distinct expression patterns of GLP1R and DPP-IV depending on the neuroendocrine cell types in P-NEN and the anatomical sites in GI-NEN.
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Affiliation(s)
- Ryuichi Wada
- Department of Pathology and Molecular Medicine, Graduate School of Medicine, Hirosaki University, 5 Zaifu-cho, Hirosaki, 036-8562, Japan,
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311
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Affiliation(s)
- John R. Ussher
- Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, Canada
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312
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Li AQ, Zhao L, Zhou TF, Zhang MQ, Qin XM. Exendin-4 promotes endothelial barrier enhancement via PKA- and Epac1-dependent Rac1 activation. Am J Physiol Cell Physiol 2014; 308:C164-75. [PMID: 25377089 DOI: 10.1152/ajpcell.00249.2014] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Among emerging antidiabetic agents, glucagon-like peptide-1 (GLP-1)-based therapies carry special cardiovascular implications, exerting both direct and indirect effects. The control of vascular permeability is of pivotal importance in vascular pathologies. The objective of the present study was to determine the effect of GLP-1 on endothelial barrier function and assess the underlying mechanism(s). Here we show for the first time that the stable GLP-1 analog exendin-4 attenuated the leakage of subcutaneous blood vessels in mice indexed by dye extravasation caused by injections of thrombin. Moreover, in cultured endothelial cells, exendin-4 significantly prevented the thrombin-induced FITC-dextran permeability of endothelial monolayers via GLP-1 receptor. Immunofluorescence microscopy reveals that exendin-4 abrogates detrimental effects of thrombin on VE-cadherin and the F-actin cytoskeleton, with decreased stress fiber and gap formation. Importantly, exendin-4 reduced thrombin-induced tyrosine phosphorylation of VE-cadherin at Y731 and Y658. Moreover, small GTPase Rac1 was significantly activated as a result of exendin-4 treatment. The efficacy of exendin-4 to counteract the barrier-compromising effect of thrombin was blunted when Rac1 was inactivated by Rac1 inhibitor NSC-23766. Inhibition of PKA activity or small-interfering RNA for exchange protein directly activated by cAMP 1 (Epac1) decreased exendin-4-induced Rac1 activation and barrier enhancement, indicating the participation of both PKA and Epac1 in the barrier-stabilizing effect of exendin-4 elicited on thrombin-impaired barrier function. Thus, our findings have uncovered an unpredicted role for exendin-4 in the coordination of vascular permeability and clarified the molecular underpinnings that contribute to barrier restoration initiated by exendin-4.
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Affiliation(s)
- Ai Q Li
- Institute of Cardiovascular Science, and Key Laboratory of Molecular Cardiovascular Science of Ministry of Education, Peking University Health Science Center, Beijing, China
| | - Liang Zhao
- Institute of Cardiovascular Science, and Key Laboratory of Molecular Cardiovascular Science of Ministry of Education, Peking University Health Science Center, Beijing, China
| | - Teng F Zhou
- Institute of Cardiovascular Science, and Key Laboratory of Molecular Cardiovascular Science of Ministry of Education, Peking University Health Science Center, Beijing, China
| | - Meng Q Zhang
- Institute of Cardiovascular Science, and Key Laboratory of Molecular Cardiovascular Science of Ministry of Education, Peking University Health Science Center, Beijing, China
| | - Xiao M Qin
- Institute of Cardiovascular Science, and Key Laboratory of Molecular Cardiovascular Science of Ministry of Education, Peking University Health Science Center, Beijing, China
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313
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Scholz GH, Fleischmann H. Basal insulin combined incretin mimetic therapy with glucagon-like protein 1 receptor agonists as an upcoming option in the treatment of type 2 diabetes: a practical guide to decision making. Ther Adv Endocrinol Metab 2014; 5:95-123. [PMID: 25419451 PMCID: PMC4236299 DOI: 10.1177/2042018814556099] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The combination of basal insulin and glucagon-like protein 1 receptor agonists (GLP-1 RAs) is a new intriguing therapeutic option for patients with type 2 diabetes. In our daily practice we abbreviate this therapeutic concept with the term BIT (basal insulin combined incretin mimetic therapy) in a certain analogy to BOT (basal insulin supported oral therapy). In most cases BIT is indeed an extension of BOT, if fasting, prandial or postprandial blood glucose values have not reached the target range. In our paper we discuss special features of combinations of short- or prandial-acting and long- or continuous-acting GLP-1 RAs like exenatide, lixisenatide and liraglutide with basal insulin in relation to different glycemic targets. Overall it seems appropriate to use a short-acting GLP-1 RA if, after the near normalization of fasting blood glucose with BOT, the prandial or postprandial values are elevated. A long-acting GLP-1 RA might well be given, if fasting blood glucose values are the problem. Based on pathophysiological findings, recent clinical studies and our experience with BIT and BOT as well as BOTplus we developed chart-supported algorithms for decision making, including features and conditions of patients. The development of these practical tools was guided by the need for a more individualized antidiabetic therapy and the availability of the new BIT principle.
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Affiliation(s)
- Gerhard H Scholz
- St. Elisabeth-Krankenhaus Leipzig, Biedermannstrasse 84, Leipzig, D-04277, Germany
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314
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Taher J, Baker CL, Cuizon C, Masoudpour H, Zhang R, Farr S, Naples M, Bourdon C, Pausova Z, Adeli K. GLP-1 receptor agonism ameliorates hepatic VLDL overproduction and de novo lipogenesis in insulin resistance. Mol Metab 2014; 3:823-33. [PMID: 25506548 PMCID: PMC4264039 DOI: 10.1016/j.molmet.2014.09.005] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/25/2014] [Revised: 09/07/2014] [Accepted: 09/11/2014] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND/OBJECTIVES Fasting dyslipidemia is commonly observed in insulin resistant states and mechanistically linked to hepatic overproduction of very low density lipoprotein (VLDL). Recently, the incretin hormone glucagon-like peptide-1 (GLP-1) has been implicated in ameliorating dyslipidemia associated with insulin resistance and reducing hepatic lipid stores. Given that hepatic VLDL production is a key determinant of circulating lipid levels, we investigated the role of both peripheral and central GLP-1 receptor (GLP-1R) agonism in regulation of VLDL production. METHODS The fructose-fed Syrian golden hamster was employed as a model of diet-induced insulin resistance and VLDL overproduction. Hamsters were treated with the GLP-1R agonist exendin-4 by intraperitoneal (ip) injection for peripheral studies or by intracerebroventricular (ICV) administration into the 3rd ventricle for central studies. Peripheral studies were repeated in vagotomised hamsters. RESULTS Short term (7-10 day) peripheral exendin-4 enhanced satiety and also prevented fructose-induced fasting dyslipidemia and hyperinsulinemia. These changes were accompanied by decreased fasting plasma glucose levels, reduced hepatic lipid content and decreased levels of VLDL-TG and -apoB100 in plasma. The observed changes in fasting dyslipidemia could be partially explained by reduced respiratory exchange ratio (RER) thereby indicating a switch in energy utilization from carbohydrate to lipid. Additionally, exendin-4 reduced mRNA markers associated with hepatic de novo lipogenesis and inflammation. Despite these observations, GLP-1R activity could not be detected in primary hamster hepatocytes, thus leading to the investigation of a potential brain-liver axis functioning to regulate lipid metabolism. Short term (4 day) central administration of exendin-4 decreased body weight and food consumption and further prevented fructose-induced hypertriglyceridemia. Additionally, the peripheral lipid-lowering effects of exendin-4 were negated in vagotomised hamsters implicating the involvement of parasympathetic signaling. CONCLUSION Exendin-4 prevents fructose-induced dyslipidemia and hepatic VLDL overproduction in insulin resistance through an indirect mechanism involving altered energy utilization, decreased hepatic lipid synthesis and also requires an intact parasympathetic signaling pathway.
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Affiliation(s)
- Jennifer Taher
- Molecular Structure and Function, Research Institute, The Hospital for Sick Children, Toronto, ON, Canada
- Department of Laboratory Medicine and Pathobiology, University of Toronto, ON, Canada
| | - Christopher L. Baker
- Molecular Structure and Function, Research Institute, The Hospital for Sick Children, Toronto, ON, Canada
| | - Carmelle Cuizon
- Molecular Structure and Function, Research Institute, The Hospital for Sick Children, Toronto, ON, Canada
| | - Hassan Masoudpour
- Molecular Structure and Function, Research Institute, The Hospital for Sick Children, Toronto, ON, Canada
| | - Rianna Zhang
- Molecular Structure and Function, Research Institute, The Hospital for Sick Children, Toronto, ON, Canada
| | - Sarah Farr
- Molecular Structure and Function, Research Institute, The Hospital for Sick Children, Toronto, ON, Canada
- Department of Laboratory Medicine and Pathobiology, University of Toronto, ON, Canada
| | - Mark Naples
- Molecular Structure and Function, Research Institute, The Hospital for Sick Children, Toronto, ON, Canada
| | - Celine Bourdon
- Physiology and Experimental Medicine, Research Institute, The Hospital for Sick Children, Toronto, ON, Canada
| | - Zdenka Pausova
- Physiology and Experimental Medicine, Research Institute, The Hospital for Sick Children, Toronto, ON, Canada
| | - Khosrow Adeli
- Molecular Structure and Function, Research Institute, The Hospital for Sick Children, Toronto, ON, Canada
- Department of Laboratory Medicine and Pathobiology, University of Toronto, ON, Canada
- Corresponding author. Molecular Structure and Function, The Hospital for Sick Children, 555 University Ave, Atrium Room 3652, Toronto, ON M5G 1X8, Canada. Tel.: +1 416 813 8682; fax: +1 416 813 6257.
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315
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van der Wielen N, van Avesaat M, de Wit NJW, Vogels JTWE, Troost F, Masclee A, Koopmans SJ, van der Meulen J, Boekschoten MV, Müller M, Hendriks HFJ, Witkamp RF, Meijerink J. Cross-species comparison of genes related to nutrient sensing mechanisms expressed along the intestine. PLoS One 2014; 9:e107531. [PMID: 25216051 PMCID: PMC4162619 DOI: 10.1371/journal.pone.0107531] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2014] [Accepted: 08/12/2014] [Indexed: 01/29/2023] Open
Abstract
INTRODUCTION Intestinal chemosensory receptors and transporters are able to detect food-derived molecules and are involved in the modulation of gut hormone release. Gut hormones play an important role in the regulation of food intake and the control of gastrointestinal functioning. This mechanism is often referred to as "nutrient sensing". Knowledge of the distribution of chemosensors along the intestinal tract is important to gain insight in nutrient detection and sensing, both pivotal processes for the regulation of food intake. However, most knowledge is derived from rodents, whereas studies in man and pig are limited, and cross-species comparisons are lacking. AIM To characterize and compare intestinal expression patterns of genes related to nutrient sensing in mice, pigs and humans. METHODS Mucosal biopsy samples taken at six locations in human intestine (n = 40) were analyzed by qPCR. Intestinal scrapings from 14 locations in pigs (n = 6) and from 10 locations in mice (n = 4) were analyzed by qPCR and microarray, respectively. The gene expression of glucagon, cholecystokinin, peptide YY, glucagon-like peptide-1 receptor, taste receptor T1R3, sodium/glucose cotransporter, peptide transporter-1, GPR120, taste receptor T1R1, GPR119 and GPR93 was investigated. Partial least squares (PLS) modeling was used to compare the intestinal expression pattern between the three species. RESULTS AND CONCLUSION The studied genes were found to display specific expression patterns along the intestinal tract. PLS analysis showed a high similarity between human, pig and mouse in the expression of genes related to nutrient sensing in the distal ileum, and between human and pig in the colon. The gene expression pattern was most deviating between the species in the proximal intestine. Our results give new insights in interspecies similarities and provide new leads for translational research and models aiming to modulate food intake processes in man.
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Affiliation(s)
- Nikkie van der Wielen
- Top Institute Food and Nutrition, 9A, Wageningen, The Netherlands
- Division of Human Nutrition, Wageningen University, Wageningen, The Netherlands
| | - Mark van Avesaat
- Top Institute Food and Nutrition, 9A, Wageningen, The Netherlands
- Division of Gastroenterology and Hepatology, Department of Internal Medicine, NUTRIM, Maastricht University Medical Center, Maastricht, The Netherlands
| | - Nicole J. W. de Wit
- Division of Human Nutrition, Wageningen University, Wageningen, The Netherlands
| | - Jack T. W. E. Vogels
- Netherlands Organisation for Applied Scientific Research, TNO, Zeist, The Netherlands
| | - Freddy Troost
- Top Institute Food and Nutrition, 9A, Wageningen, The Netherlands
- Division of Gastroenterology and Hepatology, Department of Internal Medicine, NUTRIM, Maastricht University Medical Center, Maastricht, The Netherlands
| | - Ad Masclee
- Top Institute Food and Nutrition, 9A, Wageningen, The Netherlands
- Division of Gastroenterology and Hepatology, Department of Internal Medicine, NUTRIM, Maastricht University Medical Center, Maastricht, The Netherlands
| | - Sietse-Jan Koopmans
- Department of Animal Sciences, Wageningen University, Wageningen, The Netherlands
- Animal Sciences Group, Wageningen University and Research centre, Lelystad, The Netherlands
| | - Jan van der Meulen
- Animal Sciences Group, Wageningen University and Research centre, Lelystad, The Netherlands
| | - Mark V. Boekschoten
- Top Institute Food and Nutrition, 9A, Wageningen, The Netherlands
- Division of Human Nutrition, Wageningen University, Wageningen, The Netherlands
| | - Michael Müller
- Division of Human Nutrition, Wageningen University, Wageningen, The Netherlands
| | - Henk F. J. Hendriks
- Top Institute Food and Nutrition, 9A, Wageningen, The Netherlands
- Netherlands Organisation for Applied Scientific Research, TNO, Zeist, The Netherlands
| | - Renger F. Witkamp
- Division of Human Nutrition, Wageningen University, Wageningen, The Netherlands
| | - Jocelijn Meijerink
- Division of Human Nutrition, Wageningen University, Wageningen, The Netherlands
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316
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Younce CW, Niu J, Ayala J, Burmeister MA, Smith LH, Kolattukudy P, Ayala JE. Exendin-4 improves cardiac function in mice overexpressing monocyte chemoattractant protein-1 in cardiomyocytes. J Mol Cell Cardiol 2014; 76:172-6. [PMID: 25200599 DOI: 10.1016/j.yjmcc.2014.08.022] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/13/2014] [Revised: 08/11/2014] [Accepted: 08/21/2014] [Indexed: 01/10/2023]
Abstract
The incretin hormone glucagon-like peptide-1 (Glp1) is cardioprotective in models of ischemia-reperfusion injury, myocardial infarction and gluco/lipotoxicity. Inflammation is a factor in these models, yet it is unknown whether Glp1 receptor (Glp1r) agonists are protective against cardiac inflammation. We tested the hypothesis that the Glp1r agonist Exendin-4 (Ex4) is cardioprotective in mice with cardiac-specific monocyte chemoattractant protein-1 overexpression. These MHC-MCP1 mice exhibit increased cardiac monocyte infiltration, endoplasmic reticulum (ER) stress, apoptosis, fibrosis and left ventricular dysfunction. Ex4 treatment for 8 weeks improved cardiac function and reduced monocyte infiltration, fibrosis and apoptosis in MHC-MCP1 mice. Ex4 enhanced expression of the ER chaperone glucose-regulated protein-78 (GRP78), decreased expression of the pro-apoptotic ER stress marker CCAAT/-enhancer-binding protein homologous protein (CHOP) and increased expression of the ER calcium regulator Sarco/Endoplasmic Reticulum Calcium ATPase-2a (SERCA2a). These findings suggest that the Glp1r is a viable target for treating cardiomyopathies associated with stimulation of pro-inflammatory factors.
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Affiliation(s)
- Craig W Younce
- Diabetes and Obesity Research Center, Sanford-Burnham Medical Research Institute at Lake Nona, Orlando, FL 32827, USA
| | - Jianli Niu
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL, USA
| | - Jennifer Ayala
- Diabetes and Obesity Research Center, Sanford-Burnham Medical Research Institute at Lake Nona, Orlando, FL 32827, USA
| | - Melissa A Burmeister
- Diabetes and Obesity Research Center, Sanford-Burnham Medical Research Institute at Lake Nona, Orlando, FL 32827, USA
| | - Layton H Smith
- Diabetes and Obesity Research Center, Sanford-Burnham Medical Research Institute at Lake Nona, Orlando, FL 32827, USA
| | - Pappachan Kolattukudy
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL, USA
| | - Julio E Ayala
- Diabetes and Obesity Research Center, Sanford-Burnham Medical Research Institute at Lake Nona, Orlando, FL 32827, USA.
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317
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Goodwill AG, Mather KJ, Conteh AM, Sassoon D, Noblet JN, Tune JD. Cardiovascular and hemodynamic effects of glucagon-like peptide-1. Rev Endocr Metab Disord 2014; 15:209-17. [PMID: 24881624 PMCID: PMC4119853 DOI: 10.1007/s11154-014-9290-z] [Citation(s) in RCA: 11] [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: 12/24/2022]
Abstract
Glucagon-like peptide-1 (GLP-1) is an incretin hormone that has been shown to have hemodynamic and cardioprotective capacity in addition to its better characterized glucoregulatory actions. Because of this, emerging research has focused on the ability of GLP-1 based therapies to drive myocardial substrate selection, enhance cardiac performance and regulate heart rate, blood pressure and vascular tone. These studies have produced consistent and reproducible results amongst numerous laboratories. However, there are obvious disparities in findings obtained in small animal models versus those of higher mammals. This species dependent discrepancy calls to question, the translational value of individual findings. Moreover, few studies of GLP-1 mediated cardiovascular action have been performed in the presence of a pre-existing comorbidities (e.g. obesity/diabetes) which limits interpretation of the effectiveness of incretin-based therapies in the setting of disease. This review addresses cardiovascular and hemodynamic potential of GLP-1 based therapies with attention to species specific effects as well as the interaction between therapies and disease.
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Affiliation(s)
- Adam G. Goodwill
- Department of Cellular and Integrative Physiology, Indiana University School of Medicine, Indianapolis IN USA
| | - Kieren J. Mather
- Department of Medicine, Indiana University of School of Medicine, Indianapolis IN USA
| | - Abass M. Conteh
- Department of Cellular and Integrative Physiology, Indiana University School of Medicine, Indianapolis IN USA
| | - Daniel Sassoon
- Department of Cellular and Integrative Physiology, Indiana University School of Medicine, Indianapolis IN USA
| | - Jillian N. Noblet
- Department of Cellular and Integrative Physiology, Indiana University School of Medicine, Indianapolis IN USA
| | - Johnathan D. Tune
- Department of Cellular and Integrative Physiology, Indiana University School of Medicine, Indianapolis IN USA
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318
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Zhang M, Robitaille M, Showalter AD, Huang X, Liu Y, Bhattacharjee A, Willard FS, Han J, Froese S, Wei L, Gaisano HY, Angers S, Sloop KW, Dai FF, Wheeler MB. Progesterone receptor membrane component 1 is a functional part of the glucagon-like peptide-1 (GLP-1) receptor complex in pancreatic β cells. Mol Cell Proteomics 2014; 13:3049-62. [PMID: 25044020 DOI: 10.1074/mcp.m114.040196] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Glucagon-like peptide-1 (GLP-1) is an incretin hormone that regulates glucose homeostasis. Because of their direct stimulation of insulin secretion from pancreatic β cells, GLP-1 receptor (GLP-1R) agonists are now important therapeutic options for the treatment of type 2 diabetes. To better understand the mechanisms that control the insulinotropic actions of GLP-1, affinity purification and mass spectrometry (AP-MS) were employed to uncover potential proteins that functionally interact with the GLP-1R. AP-MS performed on Chinese hamster ovary cells or MIN6 β cells, both expressing the human GLP-1R, revealed 99 proteins potentially associated with the GLP-1R. Three novel GLP-1R interactors (PGRMC1, Rab5b, and Rab5c) were further validated through co-immunoprecipitation/immunoblotting, fluorescence resonance energy transfer, and immunofluorescence. Functional studies revealed that overexpression of PGRMC1, a novel cell surface receptor that associated with liganded GLP-1R, enhanced GLP-1-induced insulin secretion (GIIS) with the most robust effect. Knockdown of PGRMC1 in β cells decreased GIIS, indicative of positive interaction with GLP-1R. To gain insight mechanistically, we demonstrated that the cell surface PGRMC1 ligand P4-BSA increased GIIS, whereas its antagonist AG-205 decreased GIIS. It was then found that PGRMC1 increased GLP-1-induced cAMP accumulation. PGRMC1 activation and GIIS induced by P4-BSA could be blocked by inhibition of adenylyl cyclase/EPAC signaling or the EGF receptor-PI3K signal transduction pathway. These data reveal a dual mechanism for PGRMC1-increased GIIS mediated through cAMP and EGF receptor signaling. In conclusion, we identified several novel GLP-1R interacting proteins. PGRMC1 expressed on the cell surface of β cells was shown to interact with the activated GLP-1R to enhance the insulinotropic actions of GLP-1.
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Affiliation(s)
- Ming Zhang
- From the ‡Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, Canada, M5S 1A8; §Division of Advanced Diagnosis, Toronto General Research Institute, Toronto, Canada, M5G 1C7
| | - Mélanie Robitaille
- ¶Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, and Department of Biochemistry, Faculty of Medicine, University of Toronto, Toronto, Canada, M5S 3M2
| | - Aaron D Showalter
- ‖Endocrine Discovery, Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, Indiana, 46285
| | - Xinyi Huang
- From the ‡Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, Canada, M5S 1A8; §Division of Advanced Diagnosis, Toronto General Research Institute, Toronto, Canada, M5G 1C7
| | - Ying Liu
- From the ‡Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, Canada, M5S 1A8
| | - Alpana Bhattacharjee
- From the ‡Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, Canada, M5S 1A8
| | - Francis S Willard
- ‖‖Quantitative Biology, Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, Indiana, 46285
| | - Junfeng Han
- **Department of Endocrinology and Metabolism, Shanghai Jiaotong University Affiliated Sixth People's Hospital, Shanghai, China 200233
| | - Sean Froese
- From the ‡Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, Canada, M5S 1A8; §Division of Advanced Diagnosis, Toronto General Research Institute, Toronto, Canada, M5G 1C7
| | - Li Wei
- **Department of Endocrinology and Metabolism, Shanghai Jiaotong University Affiliated Sixth People's Hospital, Shanghai, China 200233
| | - Herbert Y Gaisano
- ‡‡Department of Medicine, Faculty of Medicine, University of Toronto, Toronto, Canada, M5S 1A8
| | - Stéphane Angers
- ¶Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, and Department of Biochemistry, Faculty of Medicine, University of Toronto, Toronto, Canada, M5S 3M2
| | - Kyle W Sloop
- ‖Endocrine Discovery, Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, Indiana, 46285
| | - Feihan F Dai
- From the ‡Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, Canada, M5S 1A8;
| | - Michael B Wheeler
- From the ‡Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, Canada, M5S 1A8; §Division of Advanced Diagnosis, Toronto General Research Institute, Toronto, Canada, M5G 1C7;
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319
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Abstract
Glucagon-like peptide-1 receptor (GLP-1R) agonists and dipeptidyl peptidase-4 (DPP-4) inhibitors represent 2 distinct classes of incretin-based therapies used for the treatment of type 2 diabetes mellitus. Activation of GLP-1R signaling or inhibition of DPP-4 activity produces a broad range of overlapping and unique cardiovascular actions. Native GLP-1 regulates cardiovascular biology via activation of the classical GLP-1R, or through GLP-1(9-36), a cardioactive metabolite generated by DPP-4-mediated cleavage. In contrast, clinically approved GLP-1R agonists are not cleaved to GLP-1(9-36) and produce the majority of their actions through the classical GLP-1R. The cardiovascular mechanisms engaged by DPP-4 inhibition are more complex, encompassing increased levels of intact GLP-1, reduced levels of GLP-1(9-36), and changes in levels of numerous cardioactive peptides. Herein we review recent experimental and clinical advances that reveal how GLP-1R agonists and DPP-4 inhibitors affect the normal and diabetic heart and coronary vasculature, often independent of changes in blood glucose. Improved understanding of the complex science of incretin-based therapies is required to optimize the selection of these therapeutic agents for the treatment of diabetic patients with cardiovascular disease.
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Affiliation(s)
- John R Ussher
- From the Department of Medicine, Lunenfeld-Tanenbaum Research Institute, Mt. Sinai Hospital, University of Toronto, Ontario, Canada
| | - Daniel J Drucker
- From the Department of Medicine, Lunenfeld-Tanenbaum Research Institute, Mt. Sinai Hospital, University of Toronto, Ontario, Canada.
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320
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Ussher JR, Baggio LL, Campbell JE, Mulvihill EE, Kim M, Kabir MG, Cao X, Baranek BM, Stoffers DA, Seeley RJ, Drucker DJ. Inactivation of the cardiomyocyte glucagon-like peptide-1 receptor (GLP-1R) unmasks cardiomyocyte-independent GLP-1R-mediated cardioprotection. Mol Metab 2014; 3:507-17. [PMID: 25061556 PMCID: PMC4099509 DOI: 10.1016/j.molmet.2014.04.009] [Citation(s) in RCA: 92] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/21/2014] [Revised: 04/27/2014] [Accepted: 04/28/2014] [Indexed: 01/07/2023] Open
Abstract
GLP-1R agonists improve outcomes in ischemic heart disease. Here we studied GLP-1R-dependent adaptive and cardioprotective responses to ventricular injury. Glp1r−/− hearts exhibited chamber-specific differences in gene expression, but normal mortality and left ventricular (LV) remodeling after myocardial infarction (MI) or experimental doxorubicin-induced cardiomyopathy. Selective disruption of the cardiomyocyte GLP-1R in Glp1rCM−/− mice produced no differences in survival or LV remodeling following LAD coronary artery occlusion. Unexpectedly, the GLP-1R agonist liraglutide still produced robust cardioprotection and increased survival in Glp1rCM−/− mice following LAD coronary artery occlusion. Although liraglutide increased heart rate (HR) in Glp1rCM−/− mice, basal HR was significantly lower in Glp1rCM−/− mice. Hence, endogenous cardiomyocyte GLP-1R activity is not required for adaptive responses to ischemic or cardiomyopathic injury, and is dispensable for GLP-1R agonist-induced cardioprotection or enhanced chronotropic activity. However the cardiomyocyte GLP-1R is essential for the control of HR in mice.
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Affiliation(s)
- John R Ussher
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Canada
| | - Laurie L Baggio
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Canada
| | - Jonathan E Campbell
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Canada
| | - Erin E Mulvihill
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Canada
| | - Minsuk Kim
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Canada
| | - M Golam Kabir
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Canada
| | - Xiemin Cao
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Canada
| | - Benjamin M Baranek
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Canada
| | - Doris A Stoffers
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, USA
| | - Randy J Seeley
- UC College of Medicine, University of Cincinnati, Cincinnati, USA
| | - Daniel J Drucker
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Canada
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321
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Wang P, Yoo B, Yang J, Zhang X, Ross A, Pantazopoulos P, Dai G, Moore A. GLP-1R-targeting magnetic nanoparticles for pancreatic islet imaging. Diabetes 2014; 63:1465-74. [PMID: 24458362 PMCID: PMC4178324 DOI: 10.2337/db13-1543] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/07/2013] [Accepted: 01/19/2014] [Indexed: 12/19/2022]
Abstract
Noninvasive assessment of pancreatic β-cell mass would tremendously aid in managing type 1 diabetes (T1D). Toward this goal, we synthesized an exendin-4 conjugated magnetic iron oxide-based nanoparticle probe targeting glucagon-like peptide 1 receptor (GLP-1R), which is highly expressed on the surface of pancreatic β-cells. In vitro studies in βTC-6, the β-cell line, showed specific accumulation of the targeted probe (termed MN-Ex10-Cy5.5) compared with nontargeted (termed MN-Cy5.5). In vivo magnetic resonance imaging showed a significant transverse relaxation time (T2) shortening in the pancreata of mice injected with the MN-Ex10-Cy5.5 probe compared with control animals injected with the nontargeted probe at 7.5 and 24 h after injection. Furthermore, ΔT2 of the pancreata of prediabetic NOD mice was significantly higher than that of diabetic NOD mice after the injection of MN-Ex10-Cy5.5, indicating the decrease of probe accumulation in these animals due to β-cell loss. Of note, ΔT2 of prediabetic and diabetic NOD mice injected with MN-Cy5.5 was not significantly changed, reflecting the nonspecific mode of accumulation of nontargeted probe. We believe our results point to the potential for using this agent for monitoring the disease development and response of T1D to therapy.
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Affiliation(s)
- Ping Wang
- Molecular Imaging Laboratory, Massachusetts General Hospital/Massachusetts Institute of Technology/Harvard Medical School Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA
| | - Byunghee Yoo
- Molecular Imaging Laboratory, Massachusetts General Hospital/Massachusetts Institute of Technology/Harvard Medical School Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA
| | - Jingsheng Yang
- Massachusetts General Hospital/Massachusetts Institute of Technology/Harvard Medical School Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA
| | - Xueli Zhang
- Molecular Imaging Laboratory, Massachusetts General Hospital/Massachusetts Institute of Technology/Harvard Medical School Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA
- Center for Drug Discovery, School of Pharmacy, China Pharmaceutical University, Nanjing, China
| | - Alana Ross
- Molecular Imaging Laboratory, Massachusetts General Hospital/Massachusetts Institute of Technology/Harvard Medical School Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA
| | - Pamela Pantazopoulos
- Molecular Imaging Laboratory, Massachusetts General Hospital/Massachusetts Institute of Technology/Harvard Medical School Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA
| | - Guangping Dai
- Massachusetts General Hospital/Massachusetts Institute of Technology/Harvard Medical School Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA
| | - Anna Moore
- Molecular Imaging Laboratory, Massachusetts General Hospital/Massachusetts Institute of Technology/Harvard Medical School Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA
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322
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Aroor A, Nistala R. Tissue-specific expression of GLP1R in mice: is the problem of antibody nonspecificity solved? Diabetes 2014; 63:1182-4. [PMID: 24651800 DOI: 10.2337/db13-1937] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Affiliation(s)
- Annayya Aroor
- Division of Endocrinology and Metabolism, Department of Internal Medicine, University of Missouri-Columbia School of Medicine, Columbia, MO
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