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Huang HH, Wang YJ, Jiang HY, Yu HW, Chen YQ, Chiou A, Kuo JC. Sarcopenia-related changes in serum GLP-1 level affect myogenic differentiation. J Cachexia Sarcopenia Muscle 2024; 15:1708-1721. [PMID: 38926763 PMCID: PMC11446708 DOI: 10.1002/jcsm.13524] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/24/2023] [Revised: 04/26/2024] [Accepted: 06/03/2024] [Indexed: 06/28/2024] Open
Abstract
BACKGROUND Sarcopenia, a group of muscle-related disorders, leads to the gradual decline and weakening of skeletal muscle over time. Recognizing the pivotal role of gastrointestinal conditions in maintaining metabolic homeostasis within skeletal muscle, we hypothesize that the effectiveness of the myogenic programme is influenced by the levels of gastrointestinal hormones in the bloodstream, and this connection is associated with the onset of sarcopenia. METHODS We first categorized 145 individuals from the Emergency Room of Taipei Veterans General Hospital into sarcopenia and non-sarcopenia groups, following the criteria established by the Asian Working Group for Sarcopenia. A thorough examination of specific gastrointestinal hormone levels in plasma was conducted to identify the one most closely associated with sarcopenia. Techniques, including immunofluorescence, western blotting, glucose uptake assays, seahorse real-time cell metabolic analysis, flow cytometry analysis, kinesin-1 activity assays and qPCR analysis, were applied to investigate its impacts and mechanisms on myogenic differentiation. RESULTS Individuals in the sarcopenia group exhibited elevated plasma levels of glucagon-like peptide 1 (GLP-1) at 1021.5 ± 313.5 pg/mL, in contrast to non-sarcopenic individuals with levels at 351.1 ± 39.0 pg/mL (P < 0.05). Although it is typical for GLP-1 levels to rise post-meal and subsequently drop naturally, detecting higher GLP-1 levels in starving individuals with sarcopenia raised the possibility of GLP-1 influencing myogenic differentiation in skeletal muscle. Further investigation using a cell model revealed that GLP-1 (1, 10 and 100 ng/mL) dose-dependently suppressed the expression of the myogenic marker, impeding myocyte fusion and the formation of polarized myotubes during differentiation. GLP-1 significantly inhibited the activity of the microtubule motor kinesin-1, interfering with the translocation of glucose transporter 4 (GLUT4) to the cell membrane and the dispersion of mitochondria. These impairments subsequently led to a reduction in glucose uptake to 0.81 ± 0.04 fold (P < 0.01) and mitochondrial adenosine triphosphate (ATP) production from 25.24 ± 1.57 pmol/min to 18.83 ± 1.11 pmol/min (P < 0.05). Continuous exposure to GLP-1, even under insulin induction, attenuated the elevated glucose uptake. CONCLUSIONS The elevated GLP-1 levels observed in individuals with sarcopenia are associated with a reduction in myogenic differentiation. The impact of GLP-1 on both the membrane translocation of GLUT4 and the dispersion of mitochondria significantly hinders glucose uptake and the production of mitochondrial ATP necessary for the myogenic programme. These findings point us towards strategies to establish the muscle-gut axis, particularly in the context of sarcopenia. Additionally, these results present the potential of identifying relevant diagnostic biomarkers.
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Affiliation(s)
- Hsien-Hao Huang
- Department of Emergency Medicine, Taipei Veterans General Hospital, Taipei, Taiwan
- Institute of Emergency and Critical Care Medicine, School of Medicine, National Yang Ming Chiao Tung University, Taipei, Taiwan
| | - Yun-Jie Wang
- Institute of Biochemistry and Molecular Biology, National Yang Ming Chiao Tung University, Taipei, Taiwan
| | - Hui-Yu Jiang
- Institute of Biochemistry and Molecular Biology, National Yang Ming Chiao Tung University, Taipei, Taiwan
| | - Helen Wenshin Yu
- Institute of Biochemistry and Molecular Biology, National Yang Ming Chiao Tung University, Taipei, Taiwan
| | - Yin-Quan Chen
- Cancer and Immunology Research Center, National Yang Ming Chiao Tung University, Taipei, Taiwan
| | - Arthur Chiou
- Institute of Biophotonics, National Yang Ming Chiao Tung University, Taipei, Taiwan
| | - Jean-Cheng Kuo
- Institute of Biochemistry and Molecular Biology, National Yang Ming Chiao Tung University, Taipei, Taiwan
- Cancer and Immunology Research Center, National Yang Ming Chiao Tung University, Taipei, Taiwan
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Peart LA, Draper M, Tarasov AI. The impact of GLP-1 signalling on the energy metabolism of pancreatic islet β-cells and extrapancreatic tissues. Peptides 2024; 178:171243. [PMID: 38788902 DOI: 10.1016/j.peptides.2024.171243] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/27/2024] [Revised: 05/19/2024] [Accepted: 05/21/2024] [Indexed: 05/26/2024]
Abstract
Glucagon-like peptide-1 signalling impacts glucose homeostasis and appetite thereby indirectly affecting substrate availability at the whole-body level. The incretin canonically produces an insulinotropic effect, thereby lowering blood glucose levels by promoting the uptake and inhibiting the production of the sugar by peripheral tissues. Likewise, GLP-1 signalling within the central nervous system reduces the appetite and food intake, whereas its gastric effect delays the absorption of nutrients, thus improving glycaemic control and reducing the risk of postprandial hyperglycaemia. We review the molecular aspects of the GLP-1 signalling, focusing on its impact on intracellular energy metabolism. Whilst the incretin exerts its effects predominantly via a Gs receptor, which decodes the incretin signal into the elevation of intracellular cAMP levels, the downstream signalling cascades within the cell, acting on fast and slow timescales, resulting in an enhancement or an attenuation of glucose catabolism, respectively.
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Affiliation(s)
- Leah A Peart
- School of Biomedical Sciences, Ulster University, Cromore Road, Coleraine, Northern Ireland BT52 1SA, UK
| | - Matthew Draper
- School of Biomedical Sciences, Ulster University, Cromore Road, Coleraine, Northern Ireland BT52 1SA, UK
| | - Andrei I Tarasov
- School of Biomedical Sciences, Ulster University, Cromore Road, Coleraine, Northern Ireland BT52 1SA, UK.
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Sztanek F, Tóth LI, Pető A, Hernyák M, Diószegi Á, Harangi M. New Developments in Pharmacological Treatment of Obesity and Type 2 Diabetes-Beyond and within GLP-1 Receptor Agonists. Biomedicines 2024; 12:1320. [PMID: 38927527 PMCID: PMC11201978 DOI: 10.3390/biomedicines12061320] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2024] [Revised: 06/05/2024] [Accepted: 06/11/2024] [Indexed: 06/28/2024] Open
Abstract
Guidelines for the management of obesity and type 2 diabetes (T2DM) emphasize the importance of lifestyle changes, including a reduced-calorie diet and increased physical activity. However, for many people, these changes can be difficult to maintain over the long term. Medication options are already available to treat obesity, which can help reduce appetite and/or reduce caloric intake. Incretin-based peptides exert their effect through G-protein-coupled receptors, the receptors for glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP), and glucagon peptide hormones are important regulators of insulin secretion and energy metabolism. Understanding the role of intercellular signaling pathways and inflammatory processes is essential for the development of effective pharmacological agents in obesity. GLP-1 receptor agonists have been successfully used, but it is assumed that their effectiveness may be limited by desensitization and downregulation of the target receptor. A growing number of new agents acting on incretin hormones are becoming available for everyday clinical practice, including oral GLP-1 receptor agonists, the dual GLP-1/GIP receptor agonist tirzepatide, and other dual and triple GLP-1/GIP/glucagon receptor agonists, which may show further significant therapeutic potential. This narrative review summarizes the therapeutic effects of different incretin hormones and presents future prospects in the treatment of T2DM and obesity.
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Affiliation(s)
- Ferenc Sztanek
- Division of Metabolism, Department of Internal Medicine, Faculty of Medicine, University of Debrecen, H-4032 Debrecen, Hungary
| | - László Imre Tóth
- Division of Metabolism, Department of Internal Medicine, Faculty of Medicine, University of Debrecen, H-4032 Debrecen, Hungary
| | - Attila Pető
- Division of Metabolism, Department of Internal Medicine, Faculty of Medicine, University of Debrecen, H-4032 Debrecen, Hungary
- Third Department of Internal Medicine, Semmelweis Hospital of Borsod-Abauj-Zemplen County Central Hospital and University Teaching Hospital, H-3529 Miskolc, Hungary
| | - Marcell Hernyák
- Division of Metabolism, Department of Internal Medicine, Faculty of Medicine, University of Debrecen, H-4032 Debrecen, Hungary
- Doctoral School of Health Sciences, University of Debrecen, H-4032 Debrecen, Hungary
| | - Ágnes Diószegi
- Division of Metabolism, Department of Internal Medicine, Faculty of Medicine, University of Debrecen, H-4032 Debrecen, Hungary
| | - Mariann Harangi
- Division of Metabolism, Department of Internal Medicine, Faculty of Medicine, University of Debrecen, H-4032 Debrecen, Hungary
- Institute of Health Studies, Faculty of Health Sciences, University of Debrecen, H-4032 Debrecen, Hungary
- ELKH-UD Vascular Pathophysiology Research Group 11003, University of Debrecen, H-4032 Debrecen, Hungary
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Reed J, Bain SC, Kanamarlapudi V. The Regulation of Metabolic Homeostasis by Incretins and the Metabolic Hormones Produced by Pancreatic Islets. Diabetes Metab Syndr Obes 2024; 17:2419-2456. [PMID: 38894706 PMCID: PMC11184168 DOI: 10.2147/dmso.s415934] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/16/2024] [Accepted: 05/07/2024] [Indexed: 06/21/2024] Open
Abstract
In healthy humans, the complex biochemical interplay between organs maintains metabolic homeostasis and pathological alterations in this process result in impaired metabolic homeostasis, causing metabolic diseases such as diabetes and obesity, which are major global healthcare burdens. The great advancements made during the last century in understanding both metabolic disease phenotypes and the regulation of metabolic homeostasis in healthy individuals have yielded new therapeutic options for diseases like type 2 diabetes (T2D). However, it is unlikely that highly desirable more efficacious treatments will be developed for metabolic disorders until the complex systemic regulation of metabolic homeostasis becomes more intricately understood. Hormones produced by pancreatic islet beta-cells (insulin) and alpha-cells (glucagon) are pivotal for maintaining metabolic homeostasis; the activity of insulin and glucagon are reciprocally correlated to achieve strict control of glucose levels (normoglycaemia). Metabolic hormones produced by other pancreatic islet cells and incretins produced by the gut are also crucial for maintaining metabolic homeostasis. Recent studies highlighted the incomplete understanding of metabolic hormonal synergism and, therefore, further elucidation of this will likely lead to more efficacious treatments for diseases such as T2D. The objective of this review is to summarise the systemic actions of the incretins and the metabolic hormones produced by the pancreatic islets and their interactions with their respective receptors.
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Affiliation(s)
- Joshua Reed
- Institute of Life Science, Medical School, Swansea University, Swansea, SA2 8PP, UK
| | - Stephen C Bain
- Institute of Life Science, Medical School, Swansea University, Swansea, SA2 8PP, UK
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Folli F, Finzi G, Manfrini R, Galli A, Casiraghi F, Centofanti L, Berra C, Fiorina P, Davalli A, La Rosa S, Perego C, Higgins PB. Mechanisms of action of incretin receptor based dual- and tri-agonists in pancreatic islets. Am J Physiol Endocrinol Metab 2023; 325:E595-E609. [PMID: 37729025 PMCID: PMC10874655 DOI: 10.1152/ajpendo.00236.2023] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/02/2023] [Revised: 09/15/2023] [Accepted: 09/16/2023] [Indexed: 09/22/2023]
Abstract
Simultaneous activation of the incretin G-protein-coupled receptors (GPCRs) via unimolecular dual-receptor agonists (UDRA) has emerged as a new therapeutic approach for type 2 diabetes. Recent studies also advocate triple agonism with molecules also capable of binding the glucagon receptor. In this scoping review, we discuss the cellular mechanisms of action (MOA) underlying the actions of these novel and therapeutically important classes of peptide receptor agonists. Clinical efficacy studies of several UDRAs have demonstrated favorable results both as monotherapies and when combined with approved hypoglycemics. Although the additive insulinotropic effects of dual glucagon-like peptide-1 receptor (GLP-1R) and glucose-dependent insulinotropic peptide receptor (GIPR) agonism were anticipated based on the known actions of either glucagon-like peptide-1 (GLP-1) or glucose-dependent insulinotropic peptide (GIP) alone, the additional benefits from GCGR were largely unexpected. Whether additional synergistic or antagonistic interactions among these G-protein receptor signaling pathways arise from simultaneous stimulation is not known. The signaling pathways affected by dual- and tri-agonism require more trenchant investigation before a comprehensive understanding of the cellular MOA. This knowledge will be essential for understanding the chronic efficacy and safety of these treatments.
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Affiliation(s)
- Franco Folli
- Dipartimento di Scienze della Salute, Università degli Studi di Milano, Milan, Italy
- Unit of Diabetes, Endocrinology and Metabolism, San Paolo Hospital, ASST Santi Paolo e Carlo, Milan, Italy
| | - Giovanna Finzi
- Unit of Pathology, Department of Oncology, ASST Sette Laghi, Varese, Italy
| | - Roberto Manfrini
- Dipartimento di Scienze della Salute, Università degli Studi di Milano, Milan, Italy
- Unit of Diabetes, Endocrinology and Metabolism, San Paolo Hospital, ASST Santi Paolo e Carlo, Milan, Italy
| | - Alessandra Galli
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Milan, Italy
| | - Francesca Casiraghi
- Dipartimento di Scienze della Salute, Università degli Studi di Milano, Milan, Italy
| | - Lucia Centofanti
- Dipartimento di Scienze della Salute, Università degli Studi di Milano, Milan, Italy
| | - Cesare Berra
- IRCCS MultiMedica, Sesto San Giovanni, Milan, Italy
| | - Paolo Fiorina
- International Center for T1D, Pediatric Clinical Research Center Romeo ed Enrica Invernizzi, DIBIC, Università di Milano, Milan, Italy
- Nephrology Division, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, United States
- Division of Endocrinology, ASST Fatebenefratelli-Sacco, Milan, Italy
| | - Alberto Davalli
- Diabetes and Endocrinology Unit, Department of Internal Medicine, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - Stefano La Rosa
- Unit of Pathology, Department of Medicine and Technological Innovation, University of Insubria, Varese, Italy
| | - Carla Perego
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Milan, Italy
| | - Paul B Higgins
- Department of Life & Physical Sciences, Atlantic Technological University, Letterkenny, Ireland
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Kamiya M, Kimura N, Umezawa N, Hasegawa H, Yasuda S. Muscle fiber necroptosis in pathophysiology of idiopathic inflammatory myopathies and its potential as target of novel treatment strategy. Front Immunol 2023; 14:1191815. [PMID: 37483632 PMCID: PMC10361824 DOI: 10.3389/fimmu.2023.1191815] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Accepted: 06/22/2023] [Indexed: 07/25/2023] Open
Abstract
Idiopathic inflammatory myopathies (IIMs), which are a group of chronic and diverse inflammatory diseases, are primarily characterized by weakness in the proximal muscles that progressively leads to persistent disability. Current treatments of IIMs depend on nonspecific immunosuppressive agents (including glucocorticoids and immunosuppressants). However, these therapies sometimes fail to regulate muscle inflammation, and some patients suffer from infectious diseases and other adverse effects related to the treatment. Furthermore, even after inflammation has subsided, muscle weakness persists in a significant proportion of the patients. Therefore, the elucidation of pathophysiology of IIMs and development of a better therapeutic strategy that not only alleviates muscle inflammation but also improves muscle weakness without increment of opportunistic infection is awaited. Muscle fiber death, which has been formerly postulated as "necrosis", is a key histological feature of all subtypes of IIMs, however, its detailed mechanisms and contribution to the pathophysiology remained to be elucidated. Recent studies have revealed that muscle fibers of IIMs undergo necroptosis, a newly recognized form of regulated cell death, and promote muscle inflammation and dysfunction through releasing inflammatory mediators such as damage-associated molecular patterns (DAMPs). The research on murine model of polymyositis, a subtype of IIM, revealed that the inhibition of necroptosis or HMGB1, one of major DAMPs released from muscle fibers undergoing necroptosis, ameliorated muscle inflammation and recovered muscle weakness. Furthermore, not only the necroptosis-associated molecules but also PGAM5, a mitochondrial protein, and reactive oxygen species have been shown to be involved in muscle fiber necroptosis, indicating the multiple target candidates for the treatment of IIMs acting through necroptosis regulation. This article overviews the research on muscle injury mechanisms in IIMs focusing on the contribution of necroptosis in their pathophysiology and discusses the potential treatment strategy targeting muscle fiber necroptosis.
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Wang M, Liu M, Zheng J, Xiong L, Wang P. Exendin-4 regulates the MAPK and WNT signaling pathways to alleviate the osteogenic inhibition of periodontal ligament stem cells in a high glucose environment. Open Med (Wars) 2023; 18:20230692. [PMID: 37034502 PMCID: PMC10080709 DOI: 10.1515/med-2023-0692] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Revised: 03/01/2023] [Accepted: 03/14/2023] [Indexed: 04/11/2023] Open
Abstract
Diabetes mellitus (DM) increases the destruction of periodontal tissue and impairs osteogenesis differentiation. Exendin-4 (Ex-4), a glucagon-like peptide-1 (GLP-1) analogue, can be used for treating DM and promotes bone regeneration. The aim of this study was to explore the effect and mechanism of Ex-4 on improving the osteogenesis of periodontal ligament stem cells (PDLSCs) in a high glucose environment. Alkaline phosphatase staining and alizarin red staining were used to detect the osteogenic differentiation of PDLSCs. The results showed that 10 nM Ex-4 could reduce the osteogenesis inhibition of PDLSCs induced by high glucose. RT-PCR and western blot results showed that Ex-4 increased the osteogenesis-related gene expression of ALP, Runx2, and Osx, and upregulated the phosphorylation of P38, JNK, and ERK1/2; the peak effect was observed in the range 0.5-1.0 h. Mitogen-activated protein kinase (MAPK) inhibitors PD98059, SB203580, and SP600125 blocked the effects of Ex-4 on MAPK activation and decreased the expression of ALP, Runx2, and Osx in PDLSCs. Moreover, after Ex-4 treatment, the total β-catenin, p-GSK3β, LEF, and Runx2 protein levels increased under normal or high glucose environments. In conclusion, our results indicated that Ex-4 regulates the MAPK and WNT signaling pathways to alleviate the osteogenic inhibition of PDLSCs in a high glucose environment.
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Affiliation(s)
- Min Wang
- Department of Stomatology, The First Affiliated Hospital of Chongqing Medical University, Chongqing, 400016, China
| | - Min Liu
- Department of Stomatology, The First Affiliated Hospital of Chongqing Medical University, Chongqing, 400016, China
| | - Jiawen Zheng
- Department of Stomatology, The First Affiliated Hospital of Chongqing Medical University, Chongqing, 400016, China
| | - Li Xiong
- Department of Pharmacy, The First Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Ping Wang
- Department of Stomatology, The First Affiliated Hospital of Chongqing Medical University, Youyi
Road 1, Chongqing, 400016, China
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Ahrén B. Glucagon-like peptide-1 and beta cell glucose sensitivity - a glucose ramp study in mice. Peptides 2021; 146:170650. [PMID: 34547355 DOI: 10.1016/j.peptides.2021.170650] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Revised: 09/09/2021] [Accepted: 09/16/2021] [Indexed: 01/03/2023]
Abstract
The incretin glucagon-like peptide-1 (GLP-1) is a gut hormone but also locally produced in pancreatic islets. We evaluated effects of GLP-1 on the insulin response to a gradual increase in glucose in mice within physiological levels. We initially developed a glucose ramp technique in mice. Glucose levels were slowly increased by 0.2 mmol/l/min for 40 min under control conditions, during intravenous infusion of GLP-1 and in GLP-1 receptor knockout mice. In control mice, glucose levels increased from 8.5 ± 0.3 to 16.1 ± 0.3 mmol/l over the 40 min, i.e., by 0.22 ± 0.01 mmol/l/min. This resulted in a slow increase in insulin levels by 96 ± 38 pmol/l from the baseline of 319 ± 53 pmol/l. GLP-1 at 0.5 nmol/kg as bolus plus 0.3 nmol/kg/min over 40 min progressively increased this insulin response by 100-fold, to 9.5 ± 0.2 nmol/l (P < 0.001). Higher doses of GLP-1 enhanced the insulin response similarly (1.0 or 3.0 nmol/kg bolus followed by 0.4 or 1.2 nmol/kg/min), whereas a lower dose (0.3 nmol/kg bolus plus 0.15 nmol/kg/min) had no significant effect compared to controls. Moreover, there was no significant difference in insulin responses between controls and GLP-1 receptor knockout mice. Since the increase in glucose levels were standardized, there was no significant difference in glucose levels between the experimental groups. We conclude that the glucose ramp technique is a tool for studies on insulin responses to slow changes in circulating glucose levels in mice. We also conclude that GLP-1 is extraordinarily potent in enhancing the insulin response to a slow increase in glucose levels.
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Affiliation(s)
- Bo Ahrén
- Department of Clinical Sciences Lund, Lund University, Lund, Sweden.
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Ruze R, Xu Q, Liu G, Li Y, Chen W, Cheng Z, Xiong Y, Liu S, Zhang G, Hu S, Yan Z. Central GLP-1 contributes to improved cognitive function and brain glucose uptake after duodenum-jejunum bypass on obese and diabetic rats. Am J Physiol Endocrinol Metab 2021; 321:E392-E409. [PMID: 34370593 DOI: 10.1152/ajpendo.00126.2021] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Accepted: 07/29/2021] [Indexed: 12/19/2022]
Abstract
The improvement of cognitive function following bariatric surgery has been highlighted, yet its underlying mechanisms remain elusive. Finding the improved brain glucose uptake of patients after Roux-en-Y gastric bypass (RYGB), duodenum-jejunum bypass (DJB), and sham surgery (Sham) were performed on obese and diabetic Wistar rats, and intracerebroventricular (ICV) injection of glucagon-like peptide-1 (GLP-1) analog liraglutide (Lira), antagonist exendin-(9-39) (Exe-9), and the viral-mediated GLP-1 receptor (Glp-1r) knockdown (KD) were applied on both groups to elucidate the role of GLP-1 in mediating cognitive function and brain glucose uptake assessed with the Morris water maze (MWM) and positron emission tomography (PET). Insulin and GLP-1 in serum and cerebral spinal fluid (CSF) were measured, and the expression of glucose uptake-related proteins including glucose transporter 1 (GLUT-1), GLUT-4, phospho-Akt substrate of 160kDa (pAS160), AS160, Rab10, Myosin-Va as well as the c-fos marker in the brain were examined. Along with augmented glucose homeostasis following DJB, central GLP-1 was correlated with the improved cognitive function and ameliorated brain glucose uptake, which was further confirmed by the enhancive role of Lira on both groups whereas the Exe-9 and Glp-1r KD were opposite. Known to activate insulin-signaling pathways, central GLP-1 contributes to improved cognitive function and brain glucose uptake after DJB.NEW & NOTEWORTHY The improvement of cognitive function following bariatric surgery has been highlighted while its mechanisms remain elusive. The brain glucose uptake of patients was improved after RYGB, and the DJB and sham surgery performed on obese and diabetic Wistar rats revealed that the elevated central GLP-1 contributes to the dramatic improvement of cognitive function, brain glucose uptake, transport, glucose sensing, and neuronal activation.
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Affiliation(s)
- Rexiati Ruze
- Department of General Surgery, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, People's Republic of China
| | - Qian Xu
- Department of General Surgery, Shandong Provincial Qianfoshan Hospital, Shandong University, Jinan, People's Republic of China
| | - Guoqin Liu
- Department of General Surgery, Jinan Central Hospital, Shandong University, Jinan, People's Republic of China
| | - Yuekai Li
- Department of Nuclear Medicine, Qilu Hospital, Cheeloo College of Medicine, Shandong University, Jinan, People's Republic of China
| | - Weijie Chen
- Department of General Surgery, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, People's Republic of China
| | - Zhiqiang Cheng
- Department of Colorectal Surgery, General Surgery, Qilu Hospital, Cheeloo College of Medicine, Shandong University, Jinan, People's Republic of China
| | - Yacheng Xiong
- Department of General Surgery, Shandong Provincial Qianfoshan Hospital, Shandong University, Jinan, People's Republic of China
| | - Shaozhuang Liu
- Department of Bariatric and Metabolic Surgery, General Surgery, Qilu Hospital, Cheeloo College of Medicine, Shandong University, Jinan, People's Republic of China
| | - Guangyong Zhang
- Department of General Surgery, The First Affiliated Hospital of Shandong First Medical University, Jinan, People's Republic of China
| | - Sanyuan Hu
- Department of General Surgery, The First Affiliated Hospital of Shandong First Medical University, Jinan, People's Republic of China
| | - Zhibo Yan
- Department of Colorectal Surgery, General Surgery, Qilu Hospital, Cheeloo College of Medicine, Shandong University, Jinan, People's Republic of China
- Key Laboratory Experimental Teratology of the Ministry of Education and Department of Physiology, School of Basic Medical Sciences, Cheeloo College of Medicine, Shandong University, Jinan, People's Republic of China
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Abdulla H, Phillips BE, Wilkinson DJ, Limb M, Jandova T, Bass JJ, Rankin D, Cegielski J, Sayda M, Crossland H, Williams JP, Smith K, Idris I, Atherton PJ. Glucagon-like peptide 1 infusions overcome anabolic resistance to feeding in older human muscle. Aging Cell 2020; 19:e13202. [PMID: 32744385 PMCID: PMC7511886 DOI: 10.1111/acel.13202] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Revised: 06/18/2020] [Accepted: 07/03/2020] [Indexed: 12/16/2022] Open
Abstract
Background Despite its known insulin‐independent effects, glucagon‐like peptide‐1 (GLP‐1) role in muscle protein turnover has not been explored under fed‐state conditions or in the context of older age, when declines in insulin sensitivity and protein anabolism, as well as losses of muscle mass and function, occur. Methods Eight older‐aged men (71 ± 1 year, mean ± SEM) were studied in a crossover trial. Baseline measures were taken over 3 hr, prior to a 3 hr postprandial insulin (~30 mIU ml−1) and glucose (7–7.5 mM) clamp, alongside I.V. infusions of octreotide and Vamin 14 (±infusions of GLP‐1). Four muscle biopsies were taken, and muscle protein turnover was quantified via incorporation of 13C6 phenylalanine and arteriovenous balance kinetics, using mass spectrometry. Leg macro‐ and microvascular flow was assessed via ultrasound and anabolic signalling by immunoblotting. GLP‐1 and insulin were measured by ELISA. Results GLP‐1 augmented muscle protein synthesis (MPS; fasted: 0.058 ± 0.004% hr−1 vs. postprandial: 0.102 ± 0.005% hr−1, p < 0.01), in comparison with non‐GLP‐1 trials. Muscle protein breakdown (MPB) was reduced throughout clamp period, while net protein balance across the leg became positive in both groups. Total femoral leg blood flow was unchanged by the clamp; however, muscle microvascular blood flow (MBF) was significantly elevated in both groups, and to a significantly greater extent in the GLP‐1 group (MBF: 5 ± 2 vs. 1.9 ± 1 fold change +GLP‐1 and −GLP‐1, respectively, p < 0.01). Activation of the Akt‐mTOR signalling was similar across both trials. Conclusion GLP‐1 infusion markedly enhanced postprandial microvascular perfusion and further stimulated muscle protein metabolism, primarily through increased MPS, during a postprandial insulin hyperaminoacidaemic clamp.
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Affiliation(s)
- Haitham Abdulla
- MRC‐Versus Arthritis Centre for Musculoskeletal Ageing Research Clinical, Metabolic and Molecular Physiology Royal Derby Hospital Centre University of Nottingham Derby UK
- Diabetes and Endocrinology Centre University Hospitals Birmingham NHS Foundation Trust Heartlands Hospital Birmingham UK
| | - Bethan E. Phillips
- MRC‐Versus Arthritis Centre for Musculoskeletal Ageing Research Clinical, Metabolic and Molecular Physiology Royal Derby Hospital Centre University of Nottingham Derby UK
- NIHR Nottingham BRC University of Nottingham Nottingham UK
| | - Daniel J. Wilkinson
- MRC‐Versus Arthritis Centre for Musculoskeletal Ageing Research Clinical, Metabolic and Molecular Physiology Royal Derby Hospital Centre University of Nottingham Derby UK
| | - Marie Limb
- MRC‐Versus Arthritis Centre for Musculoskeletal Ageing Research Clinical, Metabolic and Molecular Physiology Royal Derby Hospital Centre University of Nottingham Derby UK
| | - Tereza Jandova
- MRC‐Versus Arthritis Centre for Musculoskeletal Ageing Research Clinical, Metabolic and Molecular Physiology Royal Derby Hospital Centre University of Nottingham Derby UK
| | - Joseph J. Bass
- MRC‐Versus Arthritis Centre for Musculoskeletal Ageing Research Clinical, Metabolic and Molecular Physiology Royal Derby Hospital Centre University of Nottingham Derby UK
| | - Debbie Rankin
- MRC‐Versus Arthritis Centre for Musculoskeletal Ageing Research Clinical, Metabolic and Molecular Physiology Royal Derby Hospital Centre University of Nottingham Derby UK
| | - Jessica Cegielski
- MRC‐Versus Arthritis Centre for Musculoskeletal Ageing Research Clinical, Metabolic and Molecular Physiology Royal Derby Hospital Centre University of Nottingham Derby UK
| | - Mariwan Sayda
- MRC‐Versus Arthritis Centre for Musculoskeletal Ageing Research Clinical, Metabolic and Molecular Physiology Royal Derby Hospital Centre University of Nottingham Derby UK
| | - Hannah Crossland
- MRC‐Versus Arthritis Centre for Musculoskeletal Ageing Research Clinical, Metabolic and Molecular Physiology Royal Derby Hospital Centre University of Nottingham Derby UK
| | - John P. Williams
- MRC‐Versus Arthritis Centre for Musculoskeletal Ageing Research Clinical, Metabolic and Molecular Physiology Royal Derby Hospital Centre University of Nottingham Derby UK
- Department of Anaesthesia University Hospitals Derby and Burton NHS Foundation Trust Derby UK
| | - Kenneth Smith
- MRC‐Versus Arthritis Centre for Musculoskeletal Ageing Research Clinical, Metabolic and Molecular Physiology Royal Derby Hospital Centre University of Nottingham Derby UK
- NIHR Nottingham BRC University of Nottingham Nottingham UK
| | - Iskandar Idris
- MRC‐Versus Arthritis Centre for Musculoskeletal Ageing Research Clinical, Metabolic and Molecular Physiology Royal Derby Hospital Centre University of Nottingham Derby UK
- NIHR Nottingham BRC University of Nottingham Nottingham UK
- Department of Endocrinology and Diabetes University Hospitals Derby and Burton NHS Foundation Trust Derby UK
| | - Philip J. Atherton
- MRC‐Versus Arthritis Centre for Musculoskeletal Ageing Research Clinical, Metabolic and Molecular Physiology Royal Derby Hospital Centre University of Nottingham Derby UK
- NIHR Nottingham BRC University of Nottingham Nottingham UK
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11
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Madhu D, Khadir A, Hammad M, Kavalakatt S, Dehbi M, Al-Mulla F, Abubaker J, Tiss A. The GLP-1 analog exendin-4 modulates HSP72 expression and ERK1/2 activity in BTC6 mouse pancreatic cells. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2020; 1868:140426. [DOI: 10.1016/j.bbapap.2020.140426] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Revised: 03/09/2020] [Accepted: 04/02/2020] [Indexed: 12/25/2022]
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12
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Xiong X, Lu W, Qin X, Luo Q, Zhou W. Downregulation of the GLP-1/CREB/adiponectin pathway is partially responsible for diabetes-induced dysregulated vascular tone and VSMC dysfunction. Biomed Pharmacother 2020; 127:110218. [PMID: 32559849 DOI: 10.1016/j.biopha.2020.110218] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2019] [Revised: 04/23/2020] [Accepted: 04/28/2020] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND The dysfunction of vasculature is observed in diabetes and might be responsible for the increased incidence of vascular events. Previous studies indicated that supplementation of GLP-1 analogues is beneficial to the cardiovascular functions in diabetic patients, but the mechanisms are not clear. METHODS A type 1 diabetic model was constructed. Vascular constrictions were measured using wire myograph. Western blotting and quantitative PCR were adopted to analyze the expression profiles of key molecules. Mitochondrial functions were analyzed in both vascular tissues or vascular smooth muscle cells (VSMCs). Dual-luciferase reporter assay was used to investigate the mechanism of adiponectin regulation. RESULTS In this study, abnormal vascular hypertrophy and increased vascular tones were observed in both diabetic patients and animals. ROS productions were increased in vessels and VSMCs from diabetic patients and animals, and the ROS scavenger mitoTEMPO partially attenuated the abnormal vascular tones and hypertension. In addition, decreased GLP-1 levels were observed, while GLP-1 supplementation improved the mitochondrial functions and vascular tones. Furthermore, it was shown that GLP-1 supplementation enhanced adiponectin expressions, while adiponectin facilitated the phosphorylation of AMPK and Sirt1 expressions. Also, CREB phosphorylation was enhanced upon GLP-1 supplementation and promoted the transcriptions of adiponectin. Finally, CREB inhibition partially attenuated the effects of GLP-1 on mitochondrial functions and adiponectin expressions. CONCLUSION GLP-1 downregulation might be an important mechanism of abnormal mitochondrial function and vascular tone in diabetes. Targeting GLP-1/CREB/adiponectin axis might become a promising therapeutic strategy in alleviating diabetes-related cardiovascular dysfunctions.
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Affiliation(s)
- Xiaowei Xiong
- Department of general surgery, the Third Affiliated Hospital of Nanchang University, Nanchang, 330008, China
| | - Weihang Lu
- Department of General surgery, the Sixth Medical Center, PLA General Hospital, Beijing, 100853, China
| | - Xuan Qin
- Department of general surgery, the Third Affiliated Hospital of Nanchang University, Nanchang, 330008, China
| | - Qingyu Luo
- Department of general surgery, the Third Affiliated Hospital of Nanchang University, Nanchang, 330008, China
| | - Weimin Zhou
- Department of vascular surgery, the Second Affiliated Hospital of Nanchang University, Nanchang, 330008, China.
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13
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Abstract
The discovery that glucagon-like peptide 1 (GLP-1) mediates a significant proportion of the incretin effect during the postprandial period and the subsequent observation that GLP-1 bioactivity is retained in type 2 diabetes (T2D) led to new therapeutic strategies being developed for T2D treatment based on GLP-1 action. Although owing to its short half-life exogenous GLP-1 has no use therapeutically, GLP-1 mimetics, which have a much longer half-life than native GLP-1, have proven to be effective for T2D treatment since they prolong the incretin effect in patients. These GLP-1 mimetics are a desirable therapeutic option for T2D since they do not provoke hypoglycaemia or weight gain and have simple modes of administration and monitoring. Additionally, over more recent years, GLP-1 action has been found to mediate systemic physiological beneficial effects and this has high clinical relevance due to the post-diagnosis complications of T2D. Indeed, recent studies have found that certain GLP-1 analogue therapies improve the cardiovascular outcomes for people with diabetes. Furthermore, GLP-1-based therapies may enable new therapeutic strategies for diseases that can also arise independently of the clinical manifestation of T2D, such as dementia and Parkinson's disease. GLP-1 functions by binding to its receptor (GLP-1R), which expresses mainly in pancreatic islet beta cells. A better understanding of the mechanisms and signalling pathways by which acute and chronic GLP-1R activation alleviates disease phenotypes and induces desirable physiological responses during healthy conditions will likely lead to the development of new therapeutic GLP-1 mimetic-based therapies, which improve prognosis to a greater extent than current therapies for an array of diseases.
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Affiliation(s)
- Josh Reed
- Institute of Life Science, Medical School, Swansea University, Swansea, Wales, SA2 8PP, UK
| | - Stephen C. Bain
- Institute of Life Science, Medical School, Swansea University, Swansea, Wales, SA2 8PP, UK
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14
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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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15
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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: 28] [Impact Index Per Article: 5.6] [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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16
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Jeon J, Choi S, Ha E, Lee H, Kim T, Han S, Kim H, Kim D, Kang Y, Lee K. GLP‑1 improves palmitate‑induced insulin resistance in human skeletal muscle via SIRT1 activity. Int J Mol Med 2019; 44:1161-1171. [DOI: 10.3892/ijmm.2019.4272] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2018] [Accepted: 07/01/2019] [Indexed: 11/06/2022] Open
Affiliation(s)
- Ja Jeon
- Department of Endocrinology and Metabolism, Ajou University School of Medicine, Suwon 16499, Republic of Korea
| | - Sung‑E Choi
- Department of Physiology, Ajou University School of Medicine, Suwon 16499, Republic of Korea
| | - Eun Ha
- Department of Endocrinology and Metabolism, Ajou University School of Medicine, Suwon 16499, Republic of Korea
| | - Han Lee
- Department of Endocrinology and Metabolism, Ajou University School of Medicine, Suwon 16499, Republic of Korea
| | - Tae Kim
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Seoul Medical Center, Seoul 02076, Republic of Korea
| | - Seung Han
- Department of Endocrinology and Metabolism, Ajou University School of Medicine, Suwon 16499, Republic of Korea
| | - Hae Kim
- Department of Endocrinology and Metabolism, Ajou University School of Medicine, Suwon 16499, Republic of Korea
| | - Dae Kim
- Department of Endocrinology and Metabolism, Ajou University School of Medicine, Suwon 16499, Republic of Korea
| | - Yup Kang
- Department of Physiology, Ajou University School of Medicine, Suwon 16499, Republic of KoreaDivision of Endocrinology and Metabolism, Department of Internal Medicine, Seoul Medical Center, Seoul 02076, Republic of Korea
| | - Kwan‑Woo Lee
- Department of Endocrinology and Metabolism, Ajou University School of Medicine, Suwon 16499, Republic of Korea
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17
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Glucagon-like peptide-1 attenuates endoplasmic reticulum stress-induced apoptosis in H9c2 cardiomyocytes during hypoxia/reoxygenation through the GLP-1R/PI3K/Akt pathways. Naunyn Schmiedebergs Arch Pharmacol 2019; 392:715-722. [PMID: 30762075 DOI: 10.1007/s00210-019-01625-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Accepted: 01/28/2019] [Indexed: 02/05/2023]
Abstract
Endoplasmic reticulum (ER) stress-induced apoptosis is a major cause of myocardial ischemia/reperfusion (I/R) injury. Emerging evidence indicates that glucagon-like peptide-1 (GLP-1) has potential cardioprotective effects. However, the precise mechanisms underlying the involvement of GLP-1 in I/R injury remain largely unknown. In the present study, we aimed to determine whether GLP-1 attenuates hypoxia/reoxygenation (H/R) injury in cardiomyocytes and to further elucidate the underlying signaling pathway. The results indicate that GLP-1 reversed the increased apoptotic ratio, the increased lactate dehydrogenase (LDH) levels, the reduced cell viability, the increased Caspase-3 activity, and the increased Bax/Bcl-2 ratio caused by H/R. Importantly, GLP-1 significantly decreased the expression of H/R-induced ER stress proteins (GRP78, CHOP) and Caspase-12. In addition, we found that GLP-1 increased the expression of p-Akt in H9c2 cells with H/R injuries, and that the protective action of GLP-1 against H/R-induced injury was blocked by the GLP-1 receptor (GLP-1R) inhibitor Exendin9-39 and the PI3K inhibitor LY294002. Exendin9-39 and LY294002 also blocked the downregulation of ER stress protein expression by GLP-1, after H/R injury. Therefore, we have shown that GLP-1 exerts its cardioprotective effects by alleviating ER stress-induced apoptosis due to H/R injury and that these effects are most likely associated with the activation of GLP-1R/PI3K/Akt signaling pathway.
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18
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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: 120] [Impact Index Per Article: 24.0] [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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19
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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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20
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Rowlands J, Heng J, Newsholme P, Carlessi R. Pleiotropic Effects of GLP-1 and Analogs on Cell Signaling, Metabolism, and Function. Front Endocrinol (Lausanne) 2018; 9:672. [PMID: 30532733 PMCID: PMC6266510 DOI: 10.3389/fendo.2018.00672] [Citation(s) in RCA: 159] [Impact Index Per Article: 26.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/22/2018] [Accepted: 10/29/2018] [Indexed: 12/22/2022] Open
Abstract
The incretin hormone Glucagon-Like Peptide-1 (GLP-1) is best known for its "incretin effect" in restoring glucose homeostasis in diabetics, however, it is now apparent that it has a broader range of physiological effects in the body. Both in vitro and in vivo studies have demonstrated that GLP-1 mimetics alleviate endoplasmic reticulum stress, regulate autophagy, promote metabolic reprogramming, stimulate anti-inflammatory signaling, alter gene expression, and influence neuroprotective pathways. A substantial body of evidence has accumulated with respect to how GLP-1 and its analogs act to restore and maintain normal cellular functions. These findings have prompted several clinical trials which have reported GLP-1 analogs improve cardiac function, restore lung function and reduce mortality in patients with obstructive lung disease, influence blood pressure and lipid storage, and even prevent synaptic loss and neurodegeneration. Mechanistically, GLP-1 elicits its effects via acute elevation in cAMP levels, and subsequent protein kinase(s) activation, pathways well-defined in pancreatic β-cells which stimulate insulin secretion in conjunction with elevated Ca2+ and ATP. More recently, new studies have shed light on additional downstream pathways stimulated by chronic GLP-1 exposure, findings which have direct relevance to our understanding of the potential therapeutic effects of longer lasting analogs recently developed for clinical use. In this review, we provide a comprehensive description of the diverse roles for GLP-1 across multiple tissues, describe downstream pathways stimulated by acute and chronic exposure, and discuss novel pleiotropic applications of GLP-1 mimetics in the treatment of human disease.
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Affiliation(s)
| | | | - Philip Newsholme
- School of Pharmacy and Biomedical Sciences, Curtin Health Innovation Research Institute, Perth, WA, Australia
| | - Rodrigo Carlessi
- School of Pharmacy and Biomedical Sciences, Curtin Health Innovation Research Institute, Perth, WA, Australia
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21
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Moreno-Villegas Z, Martín-Duce A, Aparicio C, Portal-Núñez S, Sanz R, Mantey SA, Jensen RT, Lorenzo O, Egido J, González N. Activation of bombesin receptor Subtype-3 by [D-Tyr 6,β-Ala 11,Phe 13,Nle 14]bombesin 6-14 increased glucose uptake and lipogenesis in human and rat adipocytes. Mol Cell Endocrinol 2018; 474:10-19. [PMID: 29402494 DOI: 10.1016/j.mce.2018.01.028] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/05/2017] [Revised: 12/20/2017] [Accepted: 01/29/2018] [Indexed: 11/19/2022]
Abstract
BRS-3 has an important role in glucose homeostasis. Its expression was reduced in skeletal muscle from obese and/or diabetic patients, and BRS-3 KO-mice developed obesity. In this work, focused on rat/human adipose tissue, BRS-3 gene-expression was lower than normal-levels in hyperlipidemic, type-2-diabetic (T2D), and type-1-diabetic rats and also in obese (OB) and T2D patients. Moreover, BRS-3 protein levels were decreased in diabetic rat and in obese and diabetic human fat pieces; but neither mutation nor even polymorphism in the BRS-3-gene was found in OB or T2D patients. Interestingly, in rat and human adipocytes, without metabolic alterations, [D-Tyr6,β-Ala11,Phe13,Nle14]bombesin6-14 -BRS-3-agonist-, as insulin, enhanced BRS-3 gene/protein expression, increased, PKB, p70s6K, MAPKs and p90RSK1 phosphorylation-levels, and induced a concentration-related stimulation of glucose transport, GLUT-4 membrane translocation and lipogenesis, exclusively mediated by BRS-3, and abolished by wortmannin, PD98059 or rapamacyn. These results confirm that BRS-3 and/or its agonist are a potential therapeutic tool for obesity/diabetes.
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Affiliation(s)
- Zaida Moreno-Villegas
- Renal, Vascular and Diabetes Research Laboratory, Instituto de Investigación Sanitaria-Fundación Jiménez Díaz (IIS-FJD), Universidad Autónoma de Madrid, Madrid, Spain
| | - Antonio Martín-Duce
- Department of Nursery, Unit of Surgery, Universidad de Alcalá, Madrid, Spain
| | - César Aparicio
- Department of Vascular Surgery, Hospital Fundación Jiménez Díaz, Madrid, Spain
| | - Sergio Portal-Núñez
- Bone and Joint Research Unit, IIS-FJD, Madrid, Spain; Applied Molecular Medicine Institute, School of Medicine, Universidad San Pablo CEU, CEU Universities, Madrid, Spain
| | | | - Samuel A Mantey
- National Institutes of Health, Cell Biology Section, NIDDK, Digestive Disease Branch, Bethesda, MD, USA
| | - Robert T Jensen
- National Institutes of Health, Cell Biology Section, NIDDK, Digestive Disease Branch, Bethesda, MD, USA
| | - Oscar Lorenzo
- Renal, Vascular and Diabetes Research Laboratory, Instituto de Investigación Sanitaria-Fundación Jiménez Díaz (IIS-FJD), Universidad Autónoma de Madrid, Madrid, Spain; Spanish Biomedical Research Network in Diabetes and Associated Metabolic Disorders (CIBERDEM), Madrid, Spain
| | - Jesús Egido
- Renal, Vascular and Diabetes Research Laboratory, Instituto de Investigación Sanitaria-Fundación Jiménez Díaz (IIS-FJD), Universidad Autónoma de Madrid, Madrid, Spain; Spanish Biomedical Research Network in Diabetes and Associated Metabolic Disorders (CIBERDEM), Madrid, Spain
| | - Nieves González
- Renal, Vascular and Diabetes Research Laboratory, Instituto de Investigación Sanitaria-Fundación Jiménez Díaz (IIS-FJD), Universidad Autónoma de Madrid, Madrid, Spain; Spanish Biomedical Research Network in Diabetes and Associated Metabolic Disorders (CIBERDEM), Madrid, Spain.
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22
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Koshinaka K, Ando R, Sato A. Short-term replacement of starch with isomaltulose enhances both insulin-dependent and -independent glucose uptake in rat skeletal muscle. J Clin Biochem Nutr 2018; 63:113-122. [PMID: 30279622 PMCID: PMC6160723 DOI: 10.3164/jcbn.17-98] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2017] [Accepted: 11/29/2017] [Indexed: 11/29/2022] Open
Abstract
Dietary intervention for preventing postprandial increases in glucose level by replacing high-glycemic index (GI) carbohydrates with lower-GI carbohydrate has been proposed as a strategy for treating insulin-resistant metabolic disorders such as type II diabetes. In this study, we examined the effect of short-term replacement of starch with a low-GI disaccharide, isomaltulose, on insulin action in skeletal muscle. Male Wistar rats were fed isomaltulose for 12 h during their dark cycle. In isolated epitrochlearis muscle, insulin-induced glucose uptake was greater in tissue from rats treated with isomaltulose than from those treated with starch. This insulin-sensitizing effect occurred independently of changes visceral fat mass. To determine whether this sensitization was specific to insulin stimulation, we also measured glucose uptake in response to exercise. In isolated epitrochlearis muscles from rats that performed swimming exercise, exercise-induced glucose uptake was higher in isomaltulose-treated than starch-treated animals. This amplification was associated with increased phosphorylation of exercise-induced AMP-activated protein kinase. In conclusion, our results demonstrate that short-term replacement of starch with isomaltulose enhances both insulin-dependent and -independent glucose uptake in isolated skeletal muscle. This transient replacement of carbohydrate with isomaltulose, together with exercise, represents a potentially effective approach for the management of insulin resistance.
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Affiliation(s)
- Keiichi Koshinaka
- Department of Health and Sports, Niigata University of Health and Welfare, 1398 Shimami-cho, Kita-ku, Niigata 950-3198, Japan
| | - Rie Ando
- Department of Health and Sports, Niigata University of Health and Welfare, 1398 Shimami-cho, Kita-ku, Niigata 950-3198, Japan
| | - Akiko Sato
- Department of Health and Sports, Niigata University of Health and Welfare, 1398 Shimami-cho, Kita-ku, Niigata 950-3198, Japan
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23
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Perna S, Guido D, Bologna C, Solerte SB, Guerriero F, Isu A, Rondanelli M. Liraglutide and obesity in elderly: efficacy in fat loss and safety in order to prevent sarcopenia. A perspective case series study. Aging Clin Exp Res 2016; 28:1251-1257. [PMID: 26749118 DOI: 10.1007/s40520-015-0525-y] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2015] [Accepted: 12/22/2015] [Indexed: 01/04/2023]
Abstract
BACKGROUND For the growing numbers of obese elderly with diabetes, the glucagon-like peptide-1 (GLP-1) receptor analogue (liraglutide) appears a safe way to promote and maintain substantial weight loss. Given this background, the aim of this study was to assess the effect of the liraglutide treatment, at doses up to 3.0 mg per day, on the body composition, focusing on sarcopenia, in overweight and obese elderly with type 2 diabetes mellitus (T2DM). METHODS A perspective study was carried out in overweight and obese T2DM patients with HbA1c equal to 7.0 % (53 mmol/mol) ~10.0 % (86), under 3-month treatment (at least) of maximal dose of metformin at stable regime, and additional liraglutide at doses up to 3.0 mg per day. Body composition markers such as skeletal muscle index (SMI), android and gynoid fat mass, and arms and legs fat free mass, was measured by dual-energy X-ray densitometry (DXA) at baseline and after 24 weeks of liraglutide treatment. Glucose control was also carried out by glucose and HbA1c. RESULTS Nine subjects (male/female 6/3, mean age 68.22 ± 3.86 years, BMI 32.34 ± 4.89 kg/m2) were evaluated. We noted a median decrease in BMI (-0.78 kg/m2), weight (-2000 g), fat mass (-1498 g) and android fat (-0.9 %), and a increase in SMI (+0.03 kg/m2) from baseline. Glycemic control also improved, with a median change HbA1c of -0.80 %. CONCLUSIONS Twenty-four weeks of liraglutide treatment was associated with reductions in fat mass and android fat. In addition, in order to prevent sarcopenia, it preserved the muscular tropism.
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Affiliation(s)
- Simone Perna
- Department of Public Health, Experimental and Forensic Medicine, Section of Human Nutrition, Endocrinology and Dietetics, University of Pavia, Azienda di Servizi alla Persona di Pavia ''Istituto Santa Margherita'', Via Emilia 12, Pavia, Italy.
| | - Davide Guido
- Department of Public Health, Experimental and Forensic Medicine, Section of Human Nutrition, Endocrinology and Dietetics, University of Pavia, Azienda di Servizi alla Persona di Pavia ''Istituto Santa Margherita'', Via Emilia 12, Pavia, Italy
- Department of Public Health, Experimental and Forensic Medicine, Biostatistics and Clinical Epidemiology Unit, University of Pavia, Pavia, Italy
| | - Chiara Bologna
- Department of Public Health, Experimental and Forensic Medicine, Section of Human Nutrition, Endocrinology and Dietetics, University of Pavia, Azienda di Servizi alla Persona di Pavia ''Istituto Santa Margherita'', Via Emilia 12, Pavia, Italy
| | - Sebastiano Bruno Solerte
- Department of Internal Medicine, Section of Geriatrics and Gerontology, University of Pavia, Azienda di Servizi alla Persona ''Istituto Santa Margherita'', Pavia, Italy
| | - Fabio Guerriero
- Department of Internal Medicine, Section of Geriatrics and Gerontology, University of Pavia, Azienda di Servizi alla Persona ''Istituto Santa Margherita'', Pavia, Italy
| | - Antonio Isu
- Department of Public Health, Experimental and Forensic Medicine, Section of Human Nutrition, Endocrinology and Dietetics, University of Pavia, Azienda di Servizi alla Persona di Pavia ''Istituto Santa Margherita'', Via Emilia 12, Pavia, Italy
| | - Mariangela Rondanelli
- Department of Public Health, Experimental and Forensic Medicine, Section of Human Nutrition, Endocrinology and Dietetics, University of Pavia, Azienda di Servizi alla Persona di Pavia ''Istituto Santa Margherita'', Via Emilia 12, Pavia, Italy
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24
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Andreozzi F, Raciti GA, Nigro C, Mannino GC, Procopio T, Davalli AM, Beguinot F, Sesti G, Miele C, Folli F. The GLP-1 receptor agonists exenatide and liraglutide activate Glucose transport by an AMPK-dependent mechanism. J Transl Med 2016; 14:229. [PMID: 27473212 PMCID: PMC4967343 DOI: 10.1186/s12967-016-0985-7] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2016] [Accepted: 07/20/2016] [Indexed: 01/11/2023] Open
Abstract
Aims/hypothesis Potentiation of glucose-induced insulin secretion is the main mechanism of exenatide (EXE) antidiabetic action, however, increased glucose utilization by peripheral tissues has been also reported. We here studied the effect of EXE on glucose uptake by skeletal muscle cells. Methods 2-deoxy-glucose (2DG) uptake and intracellular signal pathways were measured in rat L6 skeletal muscle myotubes exposed to 100 nmol/l EXE for up to 48 h. Mechanisms of EXE action were explored by inhibiting AMPK activity with compound C (CC, 40 μmol/l) or siRNAs (2 μmol/l). Results Time course experiments show that EXE increases glucose uptake up to 48 h achieving its maximal effect, similar to that induced by insulin, after 20 min (2- vs 2.5-fold-increase, respectively). Differently from insulin, EXE does not stimulate: (i) IR β-subunit- and IRS1 tyrosine phosphorylation and binding to p85 regulatory subunit of PI-3kinase; (ii) AKT activation; and (iii) ERK1/2 and JNK1/2 phosphorylation. Conversely, EXE increases phosphorylation of α-subunit of AMPK at Thr172 by 2.5-fold (p < 0.01). Co-incubation of EXE and insulin does not induce additive effects on 2DG-uptake. Inhibition of AMPK with CC, and reduction of AMPK protein expression by siRNA, completely abolish EXE-induced 2DG-uptake. Liraglutide, another GLP-1 receptor agonist, also stimulates AMPK phosphorylation and 2DG-uptake. Moreover, EXE stimulates 2DG-uptake also by L6 myotubes rendered insulin-resistant with methylglyoxal. Finally, EXE also induces glucose transporter Glut-4 translocation to the plasma membrane. Conclusions/interpretation In L6 myotubes, EXE and liraglutide increase glucose uptake in an insulin-independent manner by activating AMPK. Electronic supplementary material The online version of this article (doi:10.1186/s12967-016-0985-7) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Francesco Andreozzi
- Department of Medical and Surgical Sciences, University of Catanzaro "Magna-Graecia", Catanzaro, Italy. .,Division of Diabetes, Department of Medicine, University of Texas Health Science Center, San Antonio, TX, USA.
| | - Gregory Alexander Raciti
- Institute of Experimental Endocrinology and Oncology "G. Salvatore", National Council of Research, Naples, Italy.,Department of Translational Medical Sciences, University of Naples "Federico II", Naples, Italy
| | - Cecilia Nigro
- Institute of Experimental Endocrinology and Oncology "G. Salvatore", National Council of Research, Naples, Italy.,Department of Translational Medical Sciences, University of Naples "Federico II", Naples, Italy
| | - Gaia Chiara Mannino
- Department of Medical and Surgical Sciences, University of Catanzaro "Magna-Graecia", Catanzaro, Italy
| | - Teresa Procopio
- Department of Medical and Surgical Sciences, University of Catanzaro "Magna-Graecia", Catanzaro, Italy
| | - Alberto M Davalli
- Department of Medicine Endocrinology Unit, Ospedale San Raffaele, Milan, Italy
| | - Francesco Beguinot
- Institute of Experimental Endocrinology and Oncology "G. Salvatore", National Council of Research, Naples, Italy.,Department of Translational Medical Sciences, University of Naples "Federico II", Naples, Italy
| | - Giorgio Sesti
- Department of Medical and Surgical Sciences, University of Catanzaro "Magna-Graecia", Catanzaro, Italy
| | - Claudia Miele
- Institute of Experimental Endocrinology and Oncology "G. Salvatore", National Council of Research, Naples, Italy.,Department of Translational Medical Sciences, University of Naples "Federico II", Naples, Italy
| | - Franco Folli
- Division of Diabetes, Department of Medicine, University of Texas Health Science Center, San Antonio, TX, USA. .,Department of Internal Medicine, University of Campinas, Campinas, SP, Brazil.
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25
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Feng Y, Su L, Zhong X, Guohong W, Xiao H, Li Y, Xiu L. Exendin-4 promotes proliferation and differentiation of MC3T3-E1 osteoblasts by MAPKs activation. J Mol Endocrinol 2016; 56:189-99. [PMID: 26647389 DOI: 10.1530/jme-15-0264] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/24/2015] [Accepted: 12/02/2015] [Indexed: 12/15/2022]
Abstract
Glucagon-like peptide-1 (GLP1) and its receptor agonist have been previously reported to play a positive role in bone metabolism in aged ovariectomized rats and insulin-resistant models. However, whether GLP1 has a direct effect on the proliferation and differentiation of osteoblasts or any cellular mechanism for this potential role is unknown. We examined the effects of the GLP1 receptor agonist exendin-4 on the proliferation, differentiation, and mineralization of mouse osteoblastic MC3T3-E1 cells. GLP1 receptor was detected in MC3T3-E1 cells by polymerase chain reaction (PCR) and Western blot assay. Cell proliferation was assessed using MTT assay, revealing that exendin-4 increased cell proliferation at effective concentrations between 10(-10) and 10(-5) M. Quantitative PCR analysis showed that exendin-4 increased the mRNA expression of the differentiation markers alkaline phosphatase (ALP), collagen-1 (COL1), osteocalcin (OC), and runt-related transcription factor 2 (RUNX2) under osteogenic conditions. Alizarin red staining confirmed that 10(-7) M exendin-4 increased osteoblast mineralization by 18.7%. Exendin-4 upregulated the phosphorylation of ERK1/2, p38, and JNK, with the peak effect at 1.5 h in the Western blot analysis. The use of selective MAPK inhibitors, namely PD98059, SB203580, and SP600125, blocked the effects of exendin-4 on kinase activation (ERK1/2, p38, and JNK), as well as cell proliferation and differentiation in MC3T3-E1 cells. These findings demonstrate that exendin-4 promotes both the proliferation and differentiation of preosteoblasts MC3T3-E1 via activation of the MAPK pathway.
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Affiliation(s)
- Yingyu Feng
- Department of EndocrinologyFirst Affiliated Hospital of Sun Yat-sen University, Guangzhou, People's Republic of China
| | - Lei Su
- Department of GeriatricsFirst Affiliated Hospital of Sun Yat-sen University, Guangzhou, People's Republic of China
| | - Xing Zhong
- Department of EndocrinologySecond Affiliated Hospital of Anhui Medical University, Hefei, Anhui, People's Republic of China
| | - Wei Guohong
- Department of EndocrinologyFirst Affiliated Hospital of Sun Yat-sen University, Guangzhou, People's Republic of China
| | - Haipeng Xiao
- Department of EndocrinologyFirst Affiliated Hospital of Sun Yat-sen University, Guangzhou, People's Republic of China
| | - Yanbing Li
- Department of EndocrinologyFirst Affiliated Hospital of Sun Yat-sen University, Guangzhou, People's Republic of China
| | - Lingling Xiu
- Department of EndocrinologyFirst Affiliated Hospital of Sun Yat-sen University, Guangzhou, People's Republic of China
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26
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Du J, Zhang L, Wang Z, Yano N, Zhao YT, Wei L, Dubielecka-Szczerba P, Liu PY, Zhuang S, Qin G, Zhao TC. Exendin-4 induces myocardial protection through MKK3 and Akt-1 in infarcted hearts. Am J Physiol Cell Physiol 2016; 310:C270-83. [PMID: 26739490 DOI: 10.1152/ajpcell.00194.2015] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2015] [Accepted: 11/18/2015] [Indexed: 11/22/2022]
Abstract
We have demonstrated that glucagon like peptide-1 (GLP-1) protects the heart against ischemic injury. However, the physiological mechanism by which GLP-1 receptor (GLP-1R) initiates cardioprotection remains to be determined. The objective of this study is to elucidate the functional roles of MAPK kinase 3 (MKK3) and Akt-1 in mediating exendin-4-elicited protection in the infarcted hearts. Adult mouse myocardial infarction (MI) was created by ligation of the left descending artery. Wild-type, MKK3(-/-), Akt-1(-/-), and Akt-1(-/-);MKK3(-/-) mice were divided into one of several groups: 1) sham: animals underwent thoracotomy without ligation; 2) MI: animals underwent MI and received a daily dose of intraperitoneal injection of vehicle (saline); 3) MI + exendin-4: infarcted mice received daily injections of exendin-4, a GLP-1R agonist (0.1 mg/kg, ip). Echocardiographic measurements indicate that exendin-4 treatment resulted in the preservation of ventricular function and increases in the survival rate, but these effects were diminished in MKK3(-/-), Akt-1(-/-), and Akt-1(-/-);MKK3(-/-) mice. Exendin-4 treatments suppressed cardiac hypotrophy and reduced scar size and cardiac interstitial fibrosis, respectively, but these beneficial effects were lost in genetic elimination of MKK3, Akt-1, or Akt-1(-/-);MKK3(-/-) mice. GLP-1R stimulation stimulated angiogenic responses, which were also mitigated by deletion of MKK3 and Akt-1. Exendin-4 treatment increased phosphorylation of MKK3, p38, and Akt-1 at Ser129 but decreased levels of active caspase-3 and cleaved poly (ADP-ribose) polymerase; these proteins were diminished in MKK3(-/-), Akt-1(-/-), and Akt-1(-/-);MKK3(-/-) mice. These results reveal that exendin-4 treatment improves cardiac function, attenuates cardiac remodeling, and promotes angiogenesis in the infarcted myocardium through MKK3 and Akt-1 pathway.
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Affiliation(s)
- Jianfeng Du
- Department of Surgery, Roger Williams Medical Center, Boston University Medical School, Boston University, Providence, Rhode Island
| | - Ling Zhang
- Department of Emergency Medicine, Alpert Medical School, Brown University, Providence, Rhode Island
| | - Zhengke Wang
- Department of Dermatology, Roger Williams Medical Center, Boston University Medical School, Boston University, Providence, Rhode Island
| | - Naohiro Yano
- Women and Infants Hospital, Alpert Medical School, Brown University, Providence, Rhode Island
| | - Yu Tina Zhao
- Department of Surgery, Roger Williams Medical Center, Boston University Medical School, Boston University, Providence, Rhode Island
| | - Lei Wei
- Department of Orthopedics, Rhode Island Hospital, Alpert Medical School, Brown University, Providence, Rhode Island
| | | | - Paul Y Liu
- Department of Plastic Surgery, Alpert Medical School, Brown University, Providence, Rhode Island
| | - Shougang Zhuang
- Department of Medicine, Alpert Medical School, Brown University, Providence, Rhode Island
| | - Gangjian Qin
- Feinberg Cardiovascular Research Institute, Northwestern University Feinberg School of Medicine, Chicago, Illinois
| | - Ting C Zhao
- Department of Surgery, Roger Williams Medical Center, Boston University Medical School, Boston University, Providence, Rhode Island;
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27
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Weiss EP, Albert SG, Reeds DN, Kress KS, Ezekiel UR, McDaniel JL, Patterson BW, Klein S, Villareal DT. Calorie Restriction and Matched Weight Loss From Exercise: Independent and Additive Effects on Glucoregulation and the Incretin System in Overweight Women and Men. Diabetes Care 2015; 38:1253-62. [PMID: 25877812 PMCID: PMC4477336 DOI: 10.2337/dc14-2913] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/08/2014] [Accepted: 03/25/2015] [Indexed: 02/03/2023]
Abstract
OBJECTIVE It is not known whether calorie restriction (CR) has additive benefits to those from exercise (EX)-induced weight loss. We hypothesized that weight loss from CR and EX (CREX) improves insulin sensitivity more than matched weight loss induced by EX or CR alone and that the incretin system may be involved in adaptations to CR. RESEARCH DESIGN AND METHODS Sedentary, overweight men and women (n = 52, 45-65 years of age) were randomized to undergo 6-8% weight loss by using CR, EX, or CREX. Glucose, insulin, C-peptide, insulin sensitivity, and incretin hormones (glucagon-like peptide 1 [GLP-1] and glucose-dependent insulinotropic polypeptide [GIP]) were measured during frequently sampled oral glucose tolerance tests (FSOGTTs). Incretin effects on insulin secretion were measured by comparing insulin secretion rates from the FSOGTTs to those from a glycemia-matched glucose infusion. RESULTS Despite similar weight losses in all groups, insulin sensitivity index values increased twofold more in the CREX group (2.09 ± 0.35 μM/kg/pM × 100) than in the CR (0.89 ± 0.39 μM/kg/pM × 100) and EX (1.04 ± 0.39 μM/kg/pM × 100) groups. Postprandial GLP-1 concentrations decreased only in the CR group (P = 0.04); GIP concentrations decreased in all groups. Incretin effects on insulin secretion were unchanged. CONCLUSIONS CR and EX have additive beneficial effects on glucoregulation. Furthermore, the adaptations to CR may involve reductions in postprandial GLP-1 concentrations. These findings underscore the importance of promoting both CR and EX for optimal health. However, because data from participants who withdrew from the study and from those who did not adhere to the intervention were excluded, the results may be limited to individuals who are capable of adhering to a healthy lifestyle intervention.
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Affiliation(s)
- Edward P Weiss
- Department of Nutrition and Dietetics, Saint Louis University, St. Louis, MO Division of Geriatrics and Nutritional Science, Washington University School of Medicine, St. Louis, MO
| | - Stewart G Albert
- Division of Endocrinology, School of Medicine, Saint Louis University, St. Louis, MO
| | - Dominic N Reeds
- Division of Geriatrics and Nutritional Science, Washington University School of Medicine, St. Louis, MO
| | - Kathleen S Kress
- Department of Nutrition and Dietetics, Saint Louis University, St. Louis, MO
| | | | - Jennifer L McDaniel
- Department of Nutrition and Dietetics, Saint Louis University, St. Louis, MO
| | - Bruce W Patterson
- Division of Geriatrics and Nutritional Science, Washington University School of Medicine, St. Louis, MO
| | - Samuel Klein
- Division of Geriatrics and Nutritional Science, Washington University School of Medicine, St. Louis, MO
| | - Dennis T Villareal
- Division of Geriatrics and Nutritional Science, Washington University School of Medicine, St. Louis, MO Division of Endocrinology, Diabetes, and Metabolism, Baylor College of Medicine, Houston, TX
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28
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Weiss EP, Albert SG, Reeds DN, Kress KS, Ezekiel UR, McDaniel JL, Patterson BW, Klein S, Villareal DT. Calorie Restriction and Matched Weight Loss From Exercise: Independent and Additive Effects on Glucoregulation and the Incretin System in Overweight Women and Men. Diabetes Care 2015. [PMID: 25877812 DOI: 10.2337/dc14‐2913] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 04/13/2023]
Abstract
OBJECTIVE It is not known whether calorie restriction (CR) has additive benefits to those from exercise (EX)-induced weight loss. We hypothesized that weight loss from CR and EX (CREX) improves insulin sensitivity more than matched weight loss induced by EX or CR alone and that the incretin system may be involved in adaptations to CR. RESEARCH DESIGN AND METHODS Sedentary, overweight men and women (n = 52, 45-65 years of age) were randomized to undergo 6-8% weight loss by using CR, EX, or CREX. Glucose, insulin, C-peptide, insulin sensitivity, and incretin hormones (glucagon-like peptide 1 [GLP-1] and glucose-dependent insulinotropic polypeptide [GIP]) were measured during frequently sampled oral glucose tolerance tests (FSOGTTs). Incretin effects on insulin secretion were measured by comparing insulin secretion rates from the FSOGTTs to those from a glycemia-matched glucose infusion. RESULTS Despite similar weight losses in all groups, insulin sensitivity index values increased twofold more in the CREX group (2.09 ± 0.35 μM/kg/pM × 100) than in the CR (0.89 ± 0.39 μM/kg/pM × 100) and EX (1.04 ± 0.39 μM/kg/pM × 100) groups. Postprandial GLP-1 concentrations decreased only in the CR group (P = 0.04); GIP concentrations decreased in all groups. Incretin effects on insulin secretion were unchanged. CONCLUSIONS CR and EX have additive beneficial effects on glucoregulation. Furthermore, the adaptations to CR may involve reductions in postprandial GLP-1 concentrations. These findings underscore the importance of promoting both CR and EX for optimal health. However, because data from participants who withdrew from the study and from those who did not adhere to the intervention were excluded, the results may be limited to individuals who are capable of adhering to a healthy lifestyle intervention.
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Affiliation(s)
- Edward P Weiss
- Department of Nutrition and Dietetics, Saint Louis University, St. Louis, MO Division of Geriatrics and Nutritional Science, Washington University School of Medicine, St. Louis, MO
| | - Stewart G Albert
- Division of Endocrinology, School of Medicine, Saint Louis University, St. Louis, MO
| | - Dominic N Reeds
- Division of Geriatrics and Nutritional Science, Washington University School of Medicine, St. Louis, MO
| | - Kathleen S Kress
- Department of Nutrition and Dietetics, Saint Louis University, St. Louis, MO
| | | | - Jennifer L McDaniel
- Department of Nutrition and Dietetics, Saint Louis University, St. Louis, MO
| | - Bruce W Patterson
- Division of Geriatrics and Nutritional Science, Washington University School of Medicine, St. Louis, MO
| | - Samuel Klein
- Division of Geriatrics and Nutritional Science, Washington University School of Medicine, St. Louis, MO
| | - Dennis T Villareal
- Division of Geriatrics and Nutritional Science, Washington University School of Medicine, St. Louis, MO Division of Endocrinology, Diabetes, and Metabolism, Baylor College of Medicine, Houston, TX
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29
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Chen MZ, Hudson CA, Vincent EE, de Berker DAR, May MT, Hers I, Dayan CM, Andrews RC, Tavaré JM. Bariatric surgery in morbidly obese insulin resistant humans normalises insulin signalling but not insulin-stimulated glucose disposal. PLoS One 2015; 10:e0120084. [PMID: 25876175 PMCID: PMC4395354 DOI: 10.1371/journal.pone.0120084] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2014] [Accepted: 01/19/2015] [Indexed: 01/14/2023] Open
Abstract
Aims Weight-loss after bariatric surgery improves insulin sensitivity, but the underlying molecular mechanism is not clear. To ascertain the effect of bariatric surgery on insulin signalling, we examined glucose disposal and Akt activation in morbidly obese volunteers before and after Roux-en-Y gastric bypass surgery (RYGB), and compared this to lean volunteers. Materials and Methods The hyperinsulinaemic euglycaemic clamp, at five infusion rates, was used to determine glucose disposal rates (GDR) in eight morbidly obese (body mass index, BMI=47.3±2.2 kg/m2) patients, before and after RYGB, and in eight lean volunteers (BMI=20.7±0.7 kg/m2). Biopsies of brachioradialis muscle, taken at fasting and insulin concentrations that induced half-maximal (GDR50) and maximal (GDR100) GDR in each subject, were used to examine the phosphorylation of Akt-Thr308, Akt-473, and pras40, in vivo biomarkers for Akt activity. Results Pre-operatively, insulin-stimulated GDR was lower in the obese compared to the lean individuals (P<0.001). Weight-loss of 29.9±4 kg after surgery significantly improved GDR50 (P=0.004) but not GDR100 (P=0.3). These subjects still remained significantly more insulin resistant than the lean individuals (p<0.001). Weight loss increased insulin-stimulated skeletal muscle Akt-Thr308 and Akt-Ser473 phosphorylation, P=0.02 and P=0.03 respectively (MANCOVA), and Akt activity towards the substrate PRAS40 (P=0.003, MANCOVA), and in contrast to GDR, were fully normalised after the surgery (obese vs lean, P=0.6, P=0.35, P=0.46, respectively). Conclusions Our data show that although Akt activity substantially improved after surgery, it did not lead to a full restoration of insulin-stimulated glucose disposal. This suggests that a major defect downstream of, or parallel to, Akt signalling remains after significant weight-loss.
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Affiliation(s)
- Mimi Z. Chen
- School of Clinical Sciences, University of Bristol, Bristol, United Kingdom
| | - Claire A. Hudson
- School of Clinical Sciences, University of Bristol, Bristol, United Kingdom
| | - Emma E. Vincent
- School of Biochemistry, University of Bristol, Bristol, United Kingdom
| | | | - Margaret T. May
- School of Social and Community Medicine, University of Bristol, Bristol, United Kingdom
| | - Ingeborg Hers
- School of Physiology and Pharmacology, University of Bristol, Bristol, United Kingdom
| | - Colin M. Dayan
- Institute of Molecular and Experimental Medicine, Cardiff University School of Medicine, Cardiff, United Kingdom
| | - Robert C. Andrews
- School of Clinical Sciences, University of Bristol, Bristol, United Kingdom
- * E-mail:
| | - Jeremy M. Tavaré
- School of Biochemistry, University of Bristol, Bristol, United Kingdom
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30
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Ravassa S, Beaumont J, Huerta A, Barba J, Coma-Canella I, González A, López B, Díez J. Association of low GLP-1 with oxidative stress is related to cardiac disease and outcome in patients with type 2 diabetes mellitus: a pilot study. Free Radic Biol Med 2015; 81:1-12. [PMID: 25595459 DOI: 10.1016/j.freeradbiomed.2015.01.002] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Revised: 12/23/2014] [Accepted: 01/04/2015] [Indexed: 12/25/2022]
Abstract
Oxidative stress (OS) contributes to cardiovascular damage in type 2 diabetes mellitus (T2DM). The peptide glucagon-like peptide-1 (GLP-1) inhibits OS and exerts cardiovascular protective actions. Our aim was to investigate whether cardiac remodeling (CR) and cardiovascular events (CVE) are associated with circulating GLP-1 and biomarkers of OS in T2DM patients. We also studied GLP-1 antioxidant effects in a model of cardiomyocyte lipotoxicity. We examined 72 T2DM patients with no coronary or valve heart disease and 14 nondiabetic subjects. A median of 6 years follow-up information was obtained in 60 patients. Circulating GLP-1, dipeptidyl peptidase-4 activity, and biomarkers of OS were quantified. In T2DM patients, circulating GLP-1 decreased and OS biomarkers increased, compared with nondiabetics. Plasma GLP-1 was inversely correlated with serum 3-nitrotyrosine in T2DM patients. Patients showing high circulating 3-nitrotyrosine and low GLP-1 levels exhibited CR and higher risk for CVE, compared to the remaining patients. In palmitate-stimulated HL-1 cardiomyocytes, GLP-1 reduced cytosolic and mitochondrial oxidative stress, increased mitochondrial ATP synthase expression, partially restored mitochondrial membrane permeability and cytochrome c oxidase activity, blunted leakage of creatine to the extracellular medium, and inhibited oxidative damage in total and mitochondrial DNA. These results suggest that T2DM patients with reduced circulating GLP-1 and exacerbated OS may exhibit CR and be at higher risk for CVE. In addition, GLP-1 exerts antioxidant effects in HL-1 palmitate-overloaded cardiomyocytes. It is proposed that therapies aimed to increase GLP-1 may counteract OS, protect from CR, and prevent CVE in patients with T2DM.
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Affiliation(s)
- Susana Ravassa
- Program of Cardiovascular Diseases, Centre for Applied Medical Research, University of Navarra, Pamplona, Spain.
| | - Javier Beaumont
- Program of Cardiovascular Diseases, Centre for Applied Medical Research, University of Navarra, Pamplona, Spain
| | - Ana Huerta
- Department of Internal Medicine, University of Navarra Clinic, University of Navarra, Pamplona, Spain
| | - Joaquín Barba
- Department of Cardiology and Cardiac Surgery, University of Navarra Clinic, University of Navarra. Pamplona, Spain
| | - Isabel Coma-Canella
- Department of Cardiology and Cardiac Surgery, University of Navarra Clinic, University of Navarra. Pamplona, Spain
| | - Arantxa González
- Program of Cardiovascular Diseases, Centre for Applied Medical Research, University of Navarra, Pamplona, Spain
| | - Begoña López
- Program of Cardiovascular Diseases, Centre for Applied Medical Research, University of Navarra, Pamplona, Spain
| | - Javier Díez
- Program of Cardiovascular Diseases, Centre for Applied Medical Research, University of Navarra, Pamplona, Spain; Department of Cardiology and Cardiac Surgery, University of Navarra Clinic, University of Navarra. Pamplona, Spain
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Sjøberg KA, Rattigan S, Jeppesen JF, Lundsgaard AM, Holst JJ, Kiens B. Differential effects of glucagon-like peptide-1 on microvascular recruitment and glucose metabolism in short- and long-term insulin resistance. J Physiol 2015; 593:2185-98. [PMID: 25688993 DOI: 10.1113/jp270129] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2015] [Accepted: 02/11/2015] [Indexed: 12/25/2022] Open
Abstract
KEY POINTS Acute glucagon-like peptide-1 (GLP-1) infusion reversed the high fat diet-induced microvascular insulin resistance that occurred after both 5 days and 8 weeks of a high fat diet intervention. When GLP-1 was co-infused with insulin it had overt effects on whole body insulin sensitivity as well as insulin-mediated skeletal muscle glucose uptake after 5 days of a high fat diet, but not after 8 weeks of high fat diet intervention. Acute GLP-1 infusion did not have an additive effect to that of insulin on microvascular recruitment or skeletal muscle glucose uptake in the control group. Here we demonstrate that GLP-1 potently increases the microvascular recruitment in rat skeletal muscle but does not increase glucose uptake in the fasting state. Thus, like insulin, GLP-1 increased the microvascular recruitment but unlike insulin, GLP-1 had no direct effect on skeletal muscle glucose uptake. ABSTRACT Acute infusion of glucagon-like peptide-1 (GLP-1) has potent effects on blood flow distribution through the microcirculation in healthy humans and rats. A high fat diet induces impairments in insulin-mediated microvascular recruitment (MVR) and muscle glucose uptake, and here we examined whether this could be reversed by GLP-1. Using contrast-enhanced ultrasound, microvascular recruitment was assessed by continuous real-time imaging of gas-filled microbubbles in the microcirculation after acute (5 days) and prolonged (8 weeks) high fat diet (HF)-induced insulin resistance in rats. A euglycaemic hyperinsulinaemic clamp (3 mU min(-1) kg(-1) ), with or without a co-infusion of GLP-1 (100 pmol l(-1) ), was performed in anaesthetized rats. Consumption of HF attenuated the insulin-mediated MVR in both 5 day and 8 week HF interventions which was associated with a 50% reduction in insulin-mediated glucose uptake compared to controls. Acute administration of GLP-1 restored the normal microvascular response by increasing the MVR after both 5 days and 8 weeks of HF intervention (P < 0.05). This effect of GLP-1 was associated with a restoration of both whole body insulin sensitivity and increased insulin-mediated glucose uptake in skeletal muscle by 90% (P < 0.05) after 5 days of HF but not after 8 weeks of HF. The present study demonstrates that GLP-1 increases MVR in rat skeletal muscle and can reverse early stages of high fat diet-induced insulin resistance in vivo.
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Affiliation(s)
- Kim A Sjøberg
- Section of Molecular Physiology, The August Krogh Centre, Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, Denmark
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Karstoft K, Mortensen SP, Knudsen SH, Solomon TPJ. Direct effect of incretin hormones on glucose and glycerol metabolism and hemodynamics. Am J Physiol Endocrinol Metab 2015; 308:E426-33. [PMID: 25564476 DOI: 10.1152/ajpendo.00520.2014] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The objective of this study was to assess the insulin-independent effects of incretin hormones on glucose and glycerol metabolism and hemodynamics under euglycemic and hyperglycemic conditions. Young, healthy men (n=10) underwent three trials in a randomized, controlled, crossover study. Each trial consisted of a two-stage (euglycemia and hyperglycemia) pancreatic clamp (using somatostatin to prevent endogenous insulin secretion). Glucose and lipid metabolism was measured via infusion of stable glucose and glycerol isotopic tracers. Hemodynamic variables (femoral, brachial, and common carotid artery blood flow and flow-mediated dilation of the brachial artery) were also measured. The three trials differed as follows: 1) saline [control (CON)], 2) glucagon-like peptide (GLP-1, 0.5 pmol·kg(-1)·min(-1)), and 3) glucose-dependent insulinotropic polypeptide (GIP, 1.5 pmol·kg(-1)·min(-1)). No between-trial differences in glucose infusion rates (GIR) or glucose or glycerol kinetics were seen during euglycemia, whereas hyperglycemia resulted in increased GIR and glucose rate of disappearance during GLP-1 compared with CON and GIP (P<0.01 for all). However, when normalized to insulin levels, no differences between trials were seen for GIR or glucose rate of disappearance. Besides a higher femoral blood flow during hyperglycemia with GIP (vs. CON and GLP-1, P<0.001), no between-trial differences were seen for the hemodynamic variables. In conclusion, GLP-1 and GIP have no direct effect on whole body glucose metabolism or hemodynamics during euglycemia. On the contrary, during hyperglycemia, GIP increases femoral artery blood flow with no effect on glucose metabolism, whereas GLP-1 increases glucose disposal, potentially due to increased insulin levels.
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Affiliation(s)
- Kristian Karstoft
- Centre of Inflammation and Metabolism and Centre for Physical Activity Research, Department of Infectious Diseases, Rigshospitalet, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Stefan P Mortensen
- Centre of Inflammation and Metabolism and Centre for Physical Activity Research, Department of Infectious Diseases, Rigshospitalet, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark; University of Southern Denmark, Odense, Denmark; and
| | - Sine H Knudsen
- Centre of Inflammation and Metabolism and Centre for Physical Activity Research, Department of Infectious Diseases, Rigshospitalet, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Thomas P J Solomon
- Centre of Inflammation and Metabolism and Centre for Physical Activity Research, Department of Infectious Diseases, Rigshospitalet, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark; Department of Biomedical Sciences, Panum Institute, University of Copenhagen, Copenhagen, Denmark
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González N, Martín-Duce A, Martínez-Arrieta F, Moreno-Villegas Z, Portal-Núñez S, Sanz R, Egido J. Effect of bombesin receptor subtype-3 and its synthetic agonist on signaling, glucose transport and metabolism in myocytes from patients with obesity and type 2 diabetes. Int J Mol Med 2015; 35:925-31. [PMID: 25653074 PMCID: PMC4356436 DOI: 10.3892/ijmm.2015.2090] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2014] [Accepted: 01/15/2015] [Indexed: 11/17/2022] Open
Abstract
Bombesin receptor subtype-3 (BRS-3) is an orphan G-protein-coupled receptor (GPCR) member of the bombesin receptor family. Several studies have suggested an association between obesity, alterations in glucose metabolism, diabetes and the BRS-3 receptor. In this study, we focused on patients simultaneously diagnosed with obesity and type 2 diabetes (OB/T2D). The analysis of BRS-3 expression in the skeletal muscle of these patients revealed a marked decrease in the expression of BRS-3 at the mRNA (23.6±1.3-fold downregulation, p<0.0001) and protein level (49±7% decrease, p<0.05) compared to the normal patients (no obesity and diabetes). Moreover, in cultured primary myocytes from patients with OB/T2D, the synthetic BRS-3 agonist, [D-Try6,β-Ala11,Phe13,Nle14]bombesin6–14, significantly increased the phosphorylation levels of mitogen-activated protein kinase (MAPK), p90RSK1, protein kinase B (PKB) and p70s6K. Specifically, the ligand at 10−11 M induced the maximal phosphorylation of MAPKs (p42, 159±15% of the control; p44, 166±11% of the control; p<0.0001) and p90RSK1 (148±2% of the control, p<0.0001). The basal phosphorylation levels of all kinases were reduced (p<0.05) in the patients with OB/T2D compared to the normal patients. Furthermore, the BRS-3 agonist stimulated glucose transport, which was already detected at 10−12 M (133±9% of the control), reached maximal levels at 10−11 M (160±9%, p<0.0001) and was maintained at up to 10−8 M (overall mean, 153±7%; p<0.007). This effect was less promiment than that attained with 10−8 M insulin (202±9%, p=0.009). The effect of the agonist on glycogen synthase a activity achieved the maximum effect at 10−11 M (165±16% of the control; p<0.0001), which did not differ from that observed with higher concentrations of the agonist. These results suggest that muscle cells isolated from patients with OB/T2D have extremely high sensitivity to the synthetic ligand, and the effects are particularly observed on MAPK and p90RSK1 phosphorylation, as well as glucose uptake. Moreover, our data indicate that BRS-3 may prove to be useful as a potential therapeutic target for the treatment of patients with OB/T2D.
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Affiliation(s)
- Nieves González
- Renal, Vascular and Diabetes Research Laboratory, IIS-Jiménez Díaz Foundation, The Autonomous University of Madrid, Spanish Biomedical Research Network in Diabetes and Associated Metabolic Disorders (CIBERDEM), Madrid, Spain
| | | | - Félix Martínez-Arrieta
- Department of General Surgery, Puerta de Hierro-Majadahonda University Hospital, The Autonomous University of Madrid, Madrid, Spain
| | - Zaida Moreno-Villegas
- Renal, Vascular and Diabetes Research Laboratory, IIS-Jiménez Díaz Foundation, The Autonomous University of Madrid, Madrid, Spain
| | - Sergio Portal-Núñez
- Department of Bone and Mineral Metabolism, IIS-Jiménez Díaz Foundation, Cooperative Research Thematic Network on Aging and Frailty (RETICEF), Madrid, Spain
| | - Raúl Sanz
- Department of Neurology, IIS-Jiménez Díaz Foundation, Madrid, Spain
| | - Jesús Egido
- Renal, Vascular and Diabetes Research Laboratory, IIS-Jiménez Díaz Foundation, The Autonomous University of Madrid, Spanish Biomedical Research Network in Diabetes and Associated Metabolic Disorders (CIBERDEM), Madrid, Spain
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Zhou H, Yang J, Xin T, Zhang T, Hu S, Zhou S, Chen G, Chen Y. Exendin-4 enhances the migration of adipose-derived stem cells to neonatal rat ventricular cardiomyocyte-derived conditioned medium via the phosphoinositide 3-kinase/Akt-stromal cell-derived factor-1α/CXC chemokine receptor 4 pathway. Mol Med Rep 2015; 11:4063-72. [PMID: 25625935 PMCID: PMC4394957 DOI: 10.3892/mmr.2015.3243] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2014] [Accepted: 12/12/2014] [Indexed: 02/07/2023] Open
Abstract
Adipose-derived stem cells (ADSCs) are considered a suitable source of cells for the repair of tissue following acute myocardial infarction (AMI); however, the transplantation efficiency of ADSCs remains low. Therefore, identification of an efficient method to enhance the migration of engrafted cells to the target site is required. The present study used exendin-4 (Ex-4), a glucagon-like peptide-1 receptor agonist, to optimize the migratory capacity of ADSCs. The aim was to determine the effect and mechanisms of Ex-4 on the migration of ADSCs to neonatal rat ventricular cardiomyocyte-derived conditioned medium (NRVC-CM). The ADSCs and cardiomyocytes were cultured in vitro. Following incubation of the ADSCs with Ex-4, cell proliferation was measured using an MTT assay and the expression levels of CXC chemokine receptor 4 (CXCR4) were investigated by reverse transctiption quantitative polymerase chain reaction (RT-qPCR), western blot analysis and flow cytometry. In addition, the expression levels of stromal cell-derived factor-1α (SDF-1α) were evaluated in the NRVC-CM treated with Ex-4 by ELISA, RT-qPCR and western blot analysis. The migration of the ADSCs to the NRVC-CM was examined using a Transwell assay. Changes in the protein expression levels of phosphorylated (p−)Akt were examined in the two types of cell by western blot analysis. The results suggested that Ex-4 promoted the proliferation and expression of CXCR4 in the ADSCs, increased the secretion of SDF-1α in the cardiomyocytes and increased the expression levels of p-Akt in both cells. However, the alterations to the SDF-1α/C XC R4 cascade in the cells were abrogated following pretreatment with LY-294002, a phosphoinositide 3-kinase(PI3K) inhibitor. Furthermore, a Transwell migration assay revealed marked translocation of the ADSCs through the membranes, towards the NRVC-CM, following treatment with Ex-4. However, these effects were reduced significantly by pretreatment of the cells with the SDF-1α/CXCR4 cascade antagonist, AMD3100, and the PI3K inhibitor, LY-294002. These results indicated that Ex-4 augmented the SDF-1α/CXCR4 cascade by activating the PI3K/Akt pathways in the ADSCs and NRVCs. Furthermore, enhancement of the PI3K/Akt-SDF-1α/CXCR4 pathway may be important in the migratory response of ADSCs to NRVC-CM in vitro.
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Affiliation(s)
- Hao Zhou
- Department of Cardiology, Chinese People's Liberty Army General Hospital, Beijing 100853, P.R. China
| | - Junjie Yang
- Department of Cardiology, Chinese People's Liberty Army General Hospital, Beijing 100853, P.R. China
| | - Ting Xin
- Department of Cardiology, Tianjin First Central Hospital, Tianjin 300192, P.R. China
| | - Tao Zhang
- Department of Cardiology, Chinese People's Liberty Army General Hospital, Beijing 100853, P.R. China
| | - Shunyin Hu
- Department of Cardiology, Chinese People's Liberty Army General Hospital, Beijing 100853, P.R. China
| | - Shanshan Zhou
- Department of Cardiology, Chinese People's Liberty Army General Hospital, Beijing 100853, P.R. China
| | - Guanghui Chen
- Department of Cardiology, Chinese People's Liberty Army General Hospital, Beijing 100853, P.R. China
| | - Yundai Chen
- Department of Cardiology, Chinese People's Liberty Army General Hospital, Beijing 100853, P.R. China
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Pabreja K, Mohd MA, Koole C, Wootten D, Furness SGB. Molecular mechanisms underlying physiological and receptor pleiotropic effects mediated by GLP-1R activation. Br J Pharmacol 2014; 171:1114-28. [PMID: 23889512 DOI: 10.1111/bph.12313] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2013] [Revised: 07/10/2013] [Accepted: 07/19/2013] [Indexed: 12/22/2022] Open
Abstract
The incidence of type 2 diabetes in developed countries is increasing yearly with a significant negative impact on patient quality of life and an enormous burden on the healthcare system. Current biguanide and thiazolidinedione treatments for type 2 diabetes have a number of clinical limitations, the most serious long-term limitation being the eventual need for insulin replacement therapy (Table 1). Since 2007, drugs targeting the glucagon-like peptide-1 (GLP-1) receptor have been marketed for the treatment of type 2 diabetes. These drugs have enjoyed a great deal of success even though our underlying understanding of the mechanisms for their pleiotropic effects remain poorly characterized even while major pharmaceutical companies actively pursue small molecule alternatives. Coupling of the GLP-1 receptor to more than one signalling pathway (pleiotropic signalling) can result in ligand-dependent signalling bias and for a peptide receptor such as the GLP-1 receptor this can be exaggerated with the use of small molecule agonists. Better consideration of receptor signalling pleiotropy will be necessary for future drug development. This is particularly important given the recent failure of taspoglutide, the report of increased risk of pancreatitis associated with GLP-1 mimetics and the observed clinical differences between liraglutide, exenatide and the newly developed long-acting exenatide long acting release, albiglutide and dulaglutide.
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Affiliation(s)
- K Pabreja
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Vic., Australia
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Sripetchwandee J, Pipatpiboon N, Pratchayasakul W, Chattipakorn N, Chattipakorn SC. DPP-4 Inhibitor and PPARγ Agonist Restore the Loss of CA1 Dendritic Spines in Obese Insulin-resistant Rats. Arch Med Res 2014; 45:547-52. [DOI: 10.1016/j.arcmed.2014.09.002] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2014] [Accepted: 09/12/2014] [Indexed: 02/07/2023]
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Li Z, Ni CL, Yao Z, Chen LM, Niu WY. Liraglutide enhances glucose transporter 4 translocation via regulation of AMP-activated protein kinase signaling pathways in mouse skeletal muscle cells. Metabolism 2014; 63:1022-30. [PMID: 24972503 DOI: 10.1016/j.metabol.2014.05.008] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/02/2014] [Revised: 04/30/2014] [Accepted: 05/13/2014] [Indexed: 12/17/2022]
Abstract
OBJECTIVE Liraglutide is an anti-diabetic drug and human glucagon-like peptide-1 (GLP-1) analog that primarily functions in the pancreas. However, its extra-pancreatic functions are not clear. Skeletal muscle tissue is an important determinant of blood glucose and cells take in approximately 80% of dietary glucose via glucose transporter 4 (GLUT4) on the plasma membrane. Insulin and muscle contraction are two physiological stimuli of GLUT4 translocation to the cell membrane from intracellular storage compartments, but the signaling mechanisms that mediate these processes are different. AMP-activated protein kinase (AMPK) and Akt are the key signal molecules mediating the effects of muscle contraction and insulin, respectively, on GLUT4 translocation. Here, we investigate the effect of liraglutide on GLUT4 translocation and the roles of AMPK and Akt in this mechanism in skeletal muscle cells by stably expressing GLUT4myc with an exofacial myc-epitope C(2)C(12)-GLUT4myc. MATERIALS/METHODS The cell surface GLUT4myc levels were determined by an antibody-coupled colorimetric assay. The phosphorylation levels of AMPK, Akt, AS160, TBC1D1, and GLUT4 were determined by western blotting. The cAMP levels were measured by an ELISA kit. siRNA was transfected with Lipofectamine 2000. Analysis of variance (ANOVA) was used for data analysis. RESULTS Liraglutide stimulated GLUT4 translocation in C(2)C(12)-GLUT4myc myotubes. Liraglutide increased the intracellular cAMP levels and the phosphorylation of AMPK, AS160, and TBC1D1. Akt phosphorylation and GLUT4 expression were not affected. Inhibition of AMPK by siRNA or Compound C reduced liraglutide-induced GLUT4 translocation. CONCLUSION Our results suggest that liraglutide may induce GLUT4 translocation by activation of AMPK in muscle cells.
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Affiliation(s)
- Zhu Li
- Department of Immunology, Key Laboratory of Immuno Microenvironment and Disease of the Educational Ministry of China, Tianjin Medical University, Tianjin, 300070 China; Key Laboratory of Hormones and Development (Ministry of Health), Metabolic Diseases Hospital & Tianjin Institute of Endocrinology, Tianjin Medical University, Tianjin 300070, China
| | - Chang-Lin Ni
- Key Laboratory of Hormones and Development (Ministry of Health), Metabolic Diseases Hospital & Tianjin Institute of Endocrinology, Tianjin Medical University, Tianjin 300070, China
| | - Zhi Yao
- Department of Immunology, Key Laboratory of Immuno Microenvironment and Disease of the Educational Ministry of China, Tianjin Medical University, Tianjin, 300070 China
| | - Li-Ming Chen
- Key Laboratory of Hormones and Development (Ministry of Health), Metabolic Diseases Hospital & Tianjin Institute of Endocrinology, Tianjin Medical University, Tianjin 300070, China.
| | - Wen-Yan Niu
- Department of Immunology, Key Laboratory of Immuno Microenvironment and Disease of the Educational Ministry of China, Tianjin Medical University, Tianjin, 300070 China; Key Laboratory of Hormones and Development (Ministry of Health), Metabolic Diseases Hospital & Tianjin Institute of Endocrinology, Tianjin Medical University, Tianjin 300070, China.
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Morales PE, Torres G, Sotomayor-Flores C, Peña-Oyarzún D, Rivera-Mejías P, Paredes F, Chiong M. GLP-1 promotes mitochondrial metabolism in vascular smooth muscle cells by enhancing endoplasmic reticulum-mitochondria coupling. Biochem Biophys Res Commun 2014; 446:410-6. [PMID: 24613839 DOI: 10.1016/j.bbrc.2014.03.004] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2014] [Accepted: 03/01/2014] [Indexed: 11/27/2022]
Abstract
Incretin GLP-1 has important metabolic effects on several tissues, mainly through the regulation of glucose uptake and usage. One mechanism for increasing cell metabolism is modulating endoplasmic reticulum (ER)-mitochondria communication, as it allows for a more efficient transfer of Ca(2+) into the mitochondria, thereby increasing activity. Control of glucose metabolism is essential for proper vascular smooth muscle cell (VSMC) function. GLP-1 has been shown to produce varied metabolic actions, but whether it regulates glucose metabolism in VSMC remains unknown. In this report, we show that GLP-1 increases mitochondrial activity in the aortic cell line A7r5 by increasing ER-mitochondria coupling. GLP-1 increases intracellular glucose and diminishes glucose uptake without altering glycogen content. ATP, mitochondrial potential and oxygen consumption increase at 3h of GLP-1 treatment, paralleled by increased Ca(2+) transfer from the ER to the mitochondria. Furthermore, GLP-1 increases levels of Mitofusin-2 (Mfn2), an ER-mitochondria tethering protein, via a PKA-dependent mechanism. Accordingly, PKA inhibition and Mfn2 down-regulation prevented mitochondrial Ca(2+) increases in GLP-1 treated cells. Inhibiting both Ca(2+) release from the ER and Ca(2+) entry into mitochondria as well as diminishing Mfn2 levels blunted the increase in mitochondrial activity in response to GLP-1. Altogether, these results strongly suggest that GLP-1 increases ER-mitochondria communication in VSMC, resulting in higher mitochondrial activity.
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Affiliation(s)
- Pablo E Morales
- Advanced Center for Chronic Diseases, Centro Estudios Moleculares de la Célula, Departamento Bioquímica y Biología Molecular, Facultad Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile
| | - Gloria Torres
- Advanced Center for Chronic Diseases, Centro Estudios Moleculares de la Célula, Departamento Bioquímica y Biología Molecular, Facultad Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile
| | - Cristian Sotomayor-Flores
- Advanced Center for Chronic Diseases, Centro Estudios Moleculares de la Célula, Departamento Bioquímica y Biología Molecular, Facultad Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile
| | - Daniel Peña-Oyarzún
- Advanced Center for Chronic Diseases, Centro Estudios Moleculares de la Célula, Departamento Bioquímica y Biología Molecular, Facultad Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile
| | - Pablo Rivera-Mejías
- Advanced Center for Chronic Diseases, Centro Estudios Moleculares de la Célula, Departamento Bioquímica y Biología Molecular, Facultad Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile
| | - Felipe Paredes
- Advanced Center for Chronic Diseases, Centro Estudios Moleculares de la Célula, Departamento Bioquímica y Biología Molecular, Facultad Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile
| | - Mario Chiong
- Advanced Center for Chronic Diseases, Centro Estudios Moleculares de la Célula, Departamento Bioquímica y Biología Molecular, Facultad Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile.
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Sjøberg KA, Holst JJ, Rattigan S, Richter EA, Kiens B. GLP-1 increases microvascular recruitment but not glucose uptake in human and rat skeletal muscle. Am J Physiol Endocrinol Metab 2014; 306:E355-62. [PMID: 24302010 PMCID: PMC3923091 DOI: 10.1152/ajpendo.00283.2013] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The insulinotropic gut hormone glucagon-like peptide-1 (GLP-1) has been proposed to have effects on vascular function and glucose disposal. However, whether GLP-1 is able to increase microvascular recruitment (MVR) in humans has not been investigated. GLP-1 was infused in the femoral artery in overnight-fasted, healthy young men. Microvascular recruitment was measured with real-time contrast-enhanced ultrasound and leg glucose uptake by the leg balance technique with and without inhibition of the insulinotropic response of GLP-1 by coinfusion of octreotide. As a positive control, MVR and leg glucose uptake were measured during a hyperinsulinemic-euglycemic clamp. Infusion of GLP-1 caused a rapid increase (P < 0.05) of 20 ± 12% (mean ± SE) in MVR in the vastus lateralis muscle of the infused leg after 5 min, and MVR further increased to 60 ± 8% above preinfusion levels by 60 min infusion. The effect was slightly slower but similar in magnitude in the noninfused contralateral leg, in which GLP-1 concentration was within the physiological range. Octreotide infusion did not prevent the GLP-1-induced increase in MVR. GLP-1 infusion did not increase leg glucose uptake with or without octreotide coinfusion. GLP-1 infusion in rats increased MVR by 28% (P < 0.05) but did not increase muscle glucose uptake. During the hyperinsulinemic clamp, MVR increased ∼40%, and leg glucose uptake increased 35-fold. It is concluded that GLP-1 in physiological concentrations causes a rapid insulin-independent increase in muscle MVR but does not affect muscle glucose uptake.
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Affiliation(s)
- Kim A Sjøberg
- Section of Molecular Physiology, the August Krogh Centre, Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
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Ramos-Álvarez I, Moreno-Villegas Z, Martín-Duce A, Sanz R, Aparicio C, Portal-Núñez S, Mantey SA, Jensen RT, González N. Human BRS-3 receptor: functions/role in cell signaling pathways and glucose metabolism in obese or diabetic myocytes. Peptides 2014; 51:91-9. [PMID: 24220502 DOI: 10.1016/j.peptides.2013.11.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/16/2013] [Revised: 11/04/2013] [Accepted: 11/04/2013] [Indexed: 10/26/2022]
Abstract
Several studies showed that the orphan Bombesin Receptor Subtype-3 (BRS-3) - member of the bombesin receptor family - has an important role in glucose homeostasis (v.g.: BRS-3-KO mice developed mild obesity, and decreased levels of BRS-3 mRNA/protein have been described in muscle from obese (OB) and type 2 diabetic (T2D) patients). In this work, to gain insight into BRS-3 receptor cell signaling pathways, and its implication on glucose metabolism, primary cultured myocytes from normal subjects, OB or T2D patients were tested using high affinity ligand - [d-Tyr(6),β-Ala(11),Phe(13),Nle(14)]bombesin6-14. In muscle cells from all metabolic conditions, the compound significantly increased not only MAPKs, p90RSK1, PKB and p70s6K phosphorylation levels, but also PI3K activity; moreover, it produced a dose-response stimulation of glycogen synthase a activity and glycogen synthesis. Myocytes from OB and T2D patients were more sensitive to the ligand than normal, and T2D cells even more than obese myocytes. These results widen the knowledge of human BRS-3 cell signaling pathways induced by a BRS-3 agonist, described its insulin-mimetic effects on glucose metabolism, showed the role of BRS-3 receptor in glucose homeostasis, and also propose the employing of BRS-3/ligand system, as participant in the obese and diabetic therapies.
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MESH Headings
- Adult
- Aged
- Bombesin/pharmacology
- Cells, Cultured
- Diabetes Mellitus, Type 2/metabolism
- Diabetes Mellitus, Type 2/pathology
- Female
- Glucose/metabolism
- Glycogen/biosynthesis
- Glycogen Synthase/metabolism
- Homeostasis
- Humans
- Male
- Middle Aged
- Mitogen-Activated Protein Kinases/metabolism
- Muscle Fibers, Skeletal/drug effects
- Muscle Fibers, Skeletal/metabolism
- Obesity/metabolism
- Obesity/pathology
- Peptide Fragments/pharmacology
- Phosphatidylinositol 3-Kinases/metabolism
- Phosphorylation
- Protein Processing, Post-Translational
- Proto-Oncogene Proteins c-akt/metabolism
- Receptors, Bombesin/agonists
- Receptors, Bombesin/physiology
- Ribosomal Protein S6 Kinases, 70-kDa/metabolism
- Ribosomal Protein S6 Kinases, 90-kDa/metabolism
- Signal Transduction
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Affiliation(s)
- I Ramos-Álvarez
- Department of Metabolism, Nutrition and Hormones, IIS-Fundación Jiménez Díaz, CIBERDEM, Madrid, Spain
| | - Z Moreno-Villegas
- Department of Metabolism, Nutrition and Hormones, IIS-Fundación Jiménez Díaz, CIBERDEM, Madrid, Spain
| | - A Martín-Duce
- Department of Nursery, Unit of Surgery, Universidad de Alcalá de Henares, Madrid, Spain
| | - R Sanz
- Department of Neurology, IIS-Fundación Jiménez Díaz, Madrid, Spain
| | - C Aparicio
- Department of Vascular Surgery, Fundación Jiménez Díaz, Madrid, Spain
| | - S Portal-Núñez
- Department of Bone Mineral Metabolism, IIS-Fundación Jiménez Díaz, Madrid, Spain
| | - S A Mantey
- Digestive Diseases Branch, NIDDK, NIH, Bethesda, USA
| | - R T Jensen
- Digestive Diseases Branch, NIDDK, NIH, Bethesda, USA
| | - N González
- Department of Metabolism, Nutrition and Hormones, IIS-Fundación Jiménez Díaz, CIBERDEM, Madrid, Spain.
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Nguyen TD, Shingu Y, Amorim PA, Schwarzer M, Doenst T. Glucagon-like peptide-1 reduces contractile function and fails to boost glucose utilization in normal hearts in the presence of fatty acids. Int J Cardiol 2013; 168:4085-92. [PMID: 23890859 DOI: 10.1016/j.ijcard.2013.07.018] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/21/2012] [Revised: 06/28/2013] [Accepted: 07/03/2013] [Indexed: 10/26/2022]
Abstract
UNLABELLED GLP-1 and exendin-4, which are used as insulin sensitizers or weight reducing drugs, were shown to improve glucose uptake in the heart. However, the direct effects of GLP-1 or exendin-4 on normal hearts in the presence of fatty acids, the main cardiac substrates, have never been investigated. We therefore assessed the effects of GLP-1 or exendin-4 on myocardial glucose uptake (GU), glucose oxidation (GO) and cardiac performance (CP) under conditions of fatty acid utilization. METHODS AND RESULTS Rat hearts were perfused with only glucose (5 mM) or glucose (5 mM) plus oleate (0.4 mM) as substrates for 60 min. After 30 min, GLP-1 or exendin-4 (0.5 nM or 5 nM) was added. In the absence of oleate, GLP-1 increased both GU and GO. Exendin-4 increased GO but showed no effect on GU. Neither GLP-1 nor exendin-4 affected CP. However, when oleate was present, GLP-1 failed to stimulate glucose utilization and exendin-4 even decreased GU. Furthermore, now GLP-1 reduced CP. In contrast to prior reports, this negative inotropic effect could not be blocked by the protein kinase A inhibitor H-89. We then measured myocardial GO and CP in rats receiving a 4-week GLP-1 infusion. Interestingly, this chronic treatment resulted in a significant reduction in both GO and CP. CONCLUSIONS Under the influence of oleate, GLP-1 reduces contractile function and fails to stimulate glucose utilization in normal hearts. Exendin-4 may acutely reduce cardiac glucose uptake but not contractility. We suggest advanced investigation of heart function and metabolism in patients treating with these peptides.
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Affiliation(s)
- T Dung Nguyen
- Department of Cardiothoracic Surgery, Jena University Hospital - Friedrich Schiller University Jena, Jena, Germany
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Ramos-Álvarez I, Martín-Duce A, Moreno-Villegas Z, Sanz R, Aparicio C, Portal-Núñez S, Mantey SA, Jensen RT, González N. Bombesin receptor subtype-3 (BRS-3), a novel candidate as therapeutic molecular target in obesity and diabetes. Mol Cell Endocrinol 2013; 367:109-15. [PMID: 23291341 DOI: 10.1016/j.mce.2012.12.025] [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] [Received: 08/21/2012] [Revised: 12/03/2012] [Accepted: 12/26/2012] [Indexed: 10/27/2022]
Abstract
BRS-3 KO-mice developed obesity and unbalanced glucose metabolism, suggesting an important role of BRS-3 receptor in glucose homeostasis. We explored BRS-3 expression in skeletal muscle from normal, obese or type-2 diabetic (T2D) patients, and the effect of [D-Phe(6), β-Ala(11),Phe(13),Nle(14)]bombesin(6-14)-BRS-3-agonist-peptide (BRS-3-AP) - on glucose-related effects, before or after BRS-3 gene silencing. In muscle tissue and primary cultured myocytes from altered metabolic states, BRS-3 gene/protein expressions were down-regulated. In normal, obese and T2D cells: A) BRS-3-AP as insulin enhanced BRS-3 and GLUT-4 mRNA/protein levels; improving glucotransporter translocation to plasma membrane, and B) BRS-3-AP caused a concentration-related-stimulation of glucose transport, being obese and T2D myocytes more sensitive to the ligand than normal. Wortmannin and PD98059, but not rapamycin, abolished the stimulatory action of BRS-3-AP on glucose transport. BRS-3 plays an important role in glucose metabolism, and could be use as a molecular target, and/or its ligand, as a therapeutic agent for obesity and diabetes treatments.
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Affiliation(s)
- Irene Ramos-Álvarez
- Department of Metabolism, Nutrition and Hormones, IIS-Fundación Jiménez Díaz, Madrid, Spain
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Pipatpiboon N, Pintana H, Pratchayasakul W, Chattipakorn N, Chattipakorn SC. DPP4-inhibitor improves neuronal insulin receptor function, brain mitochondrial function and cognitive function in rats with insulin resistance induced by high-fat diet consumption. Eur J Neurosci 2012; 37:839-49. [DOI: 10.1111/ejn.12088] [Citation(s) in RCA: 126] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2012] [Accepted: 11/09/2012] [Indexed: 01/02/2023]
Affiliation(s)
- Noppamas Pipatpiboon
- Neurophysiology Unit; Faculty of Medicine; Cardiac Electrophysiology Research and Training Center, Chiang Mai University; Chiang Mai; 50200; Thailand
| | - Hiranya Pintana
- Neurophysiology Unit; Faculty of Medicine; Cardiac Electrophysiology Research and Training Center, Chiang Mai University; Chiang Mai; 50200; Thailand
| | - Wasana Pratchayasakul
- Neurophysiology Unit; Faculty of Medicine; Cardiac Electrophysiology Research and Training Center, Chiang Mai University; Chiang Mai; 50200; Thailand
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Green CJ, Henriksen TI, Pedersen BK, Solomon TPJ. Glucagon like peptide-1-induced glucose metabolism in differentiated human muscle satellite cells is attenuated by hyperglycemia. PLoS One 2012; 7:e44284. [PMID: 22937169 PMCID: PMC3429413 DOI: 10.1371/journal.pone.0044284] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2012] [Accepted: 07/31/2012] [Indexed: 01/13/2023] Open
Abstract
BACKGROUND Glucagon like peptide-1 (GLP-1) stimulates insulin secretion from the pancreas but also has extra-pancreatic effects. GLP-1 may stimulate glucose uptake in cultured muscle cells but the mechanism is not clearly defined. Furthermore, while the pancreatic effects of GLP-1 are glucose-dependent, the glucose-dependency of its extra-pancreatic effects has not been examined. METHODS Skeletal muscle satellite cells isolated from young (22.5 ± 0.97 yr), lean (BMI 22.5 ± 0.6 kg/m(2)), healthy males were differentiated in media containing either 22.5 mM (high) or 5 mM (normal) glucose for 7 days in the absence or presence of insulin and/or various GLP-1 concentrations. Myocellular effects of GLP-1, insulin and glucose were assessed by western-blot, glucose uptake and glycogen synthesis. RESULTS We firstly show that the GLP-1 receptor protein is expressed in differentiated human muscle satellite cells (myocytes). Secondly, we show that in 5 mM glucose media, exposure of myocytes to GLP-1 results in a dose dependent increase in glucose uptake, GLUT4 amount and subsequently glycogen synthesis in a PI3K dependent manner, independent of the insulin signaling cascade. Importantly, we provide evidence that differentiation of human satellite cells in hyperglycemic (22.5 mM glucose) conditions increases GLUT1 expression, and renders the cells insulin resistant and interestingly GLP-1 resistant in terms of glucose uptake and glycogen synthesis. Hyperglycemic conditions did not affect the ability of insulin to phosphorylate downstream targets, PKB or GSK3. Interestingly we show that at 5 mM glucose, GLP-1 increases GLUT4 protein levels and that this effect is abolished by hyperglycemia. CONCLUSIONS GLP-1 increases glucose uptake and glycogen synthesis into fully-differentiated human satellite cells in a PI3-K dependent mechanism potentially through increased GLUT4 protein levels. The latter occurs independently of the insulin signaling pathway. Attenuation of both GLP-1 and insulin-induced glucose metabolism by hyperglycemia is likely to occur downstream of PI3K.
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Affiliation(s)
- Charlotte J Green
- The Centre of Inflammation and Metabolism at Department of Infectious Diseases and Copenhagen Muscle Research Centre, Rigshospitalet, The Faculty of Health Sciences, University of Copenhagen, Denmark.
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45
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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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46
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Abstract
The complex pathological mechanisms responsible for development of type 2 diabetes are not fully addressed by conventional drugs, which are also associated with inconvenient side effects such as weight gain or hypoglycemia. Two types of incretin-based therapies are now in use: incretin mimetics (glucagon-like peptide-1 [GLP-1] receptor agonists that bind specific receptors and mimic the action of natural GLP-1) and incretin enhancers (inhibitors of the enzyme that degrade the incretin hormones and thus prolong their activity). Both offer important advantages over previous agents. In addition to the proven glucose-lowering efficacy, they promote weight loss (or are weight neutral) by slowing gastric emptying and inducing satiety, inhibit glucagon secretion with maintenance of counterregulatory mechanisms, and exhibit cardiovascular benefits, while having a low risk profile. Importantly, short-term studies have shown that incretins/incretin-based therapies protect β-cells (by enhancing cell proliferation and differentiation and inhibiting apoptosis) and stimulate their function (by recruiting β-cells to the secretory process and increasing insulin biosynthesis/secretion). These therapies have the opportunity to interfere with the disease progression if used as an early intervention, when enough β-cell mass/function can still be preserved or restored.
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Affiliation(s)
- Simona Cernea
- Diabetes, Nutrition and Metabolic Diseases Outpatient Unit, Emergency County Clinical Hospital, Târgu Mureş, Romania.
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47
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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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48
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Shen CA, Fagan S, Fischman AJ, Carter EE, Chai JK, Lu XM, Yu YM, Tompkins RG. Effects of glucagon-like peptide 1 on glycemia control and its metabolic consequence after severe thermal injury--studies in an animal model. Surgery 2011; 149:635-44. [PMID: 21295809 DOI: 10.1016/j.surg.2010.11.017] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2010] [Accepted: 11/24/2010] [Indexed: 12/25/2022]
Abstract
BACKGROUND Hyperglycemia with insulin resistance is commonly seen in severely burned patients and tight glycemia control with insulin may be beneficial in this condition. The most potent insulinotropic hormone, glucagon-like peptide 1 (GLP-1), stimulates insulin secretion in a glucose-dependent manner. Because infusion of GLP-1 never reduces glucose levels to below ∼70 mg/dL, the risk of hypoglycemia by using insulin is reduced. In this study we investigated the metabolic effects of GLP-1 infusion after burn injury in an animal model. METHODS Male CD rats were divided in 3 groups: burn injury with saline, burn injury with GLP-1 treatment, and sham burn (SB). Burn injury was full thickness 40% total body surface area. The burn injury with GLP-1 treatment group received GLP-1 infusion via osmotic pump. Fasting blood glucose, plasma insulin, and plasma GLP-1 levels were measured during intraperitoneal glucose tolerance tests. Expressions of caspase 3 and bcl-2 were evaluated in pancreatic islets. In a subset of animals, protein metabolism and total energy expenditure were measured. RESULTS Fasting GLP-1 was reduced in burn injury with saline compared to SB or burn injury with GLP-1 treatment. Burn injury with GLP-1 treatment showed reduced fasting blood glucose, improved intraperitoneal glucose tolerance test results, with increased plasma insulin and GLP-1 responses to glucose. GLP-1 reduced protein breakdown and total energy expenditure in burn injury with GLP-1 treatment versus burn injury with saline, with improved protein balance. Increased expression of caspase 3 and decreased expression of bcl-2 in islet cells by burn injury were ameliorated by GLP-1. CONCLUSION Burn injury reduced plasma GLP-1 in association with insulin resistance. GLP-1 infusion improved glucose tolerance and showed anabolic effects on protein metabolism and reduced total energy expenditure after burn injury, possibly via insulinotropic and non insulinotropic mechanisms.
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Affiliation(s)
- Chuan-an Shen
- Burn Unit, Department of Surgery, Massachusetts General Hospital, Boston, MA, USA
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Affiliation(s)
- Dale S Edgerton
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee, USA.
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Ravassa S, Zudaire A, Carr RD, Díez J. Antiapoptotic effects of GLP-1 in murine HL-1 cardiomyocytes. Am J Physiol Heart Circ Physiol 2011; 300:H1361-72. [PMID: 21278133 DOI: 10.1152/ajpheart.00885.2010] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Activation of apoptosis contributes to cardiomyocyte dysfunction and death in diabetic cardiomyopathy. The peptide glucagon-like peptide-1 (GLP-1), a hormone that is the basis of emerging therapy for type 2 diabetic patients, has cytoprotective actions in different cellular models. We investigated whether GLP-1 inhibits apoptosis in HL-1 cardiomyocytes stimulated with staurosporine, palmitate, and ceramide. Studies were performed in HL-1 cardiomyocytes. Apoptosis was induced by incubating HL-1 cells with staurosporine (175 nM), palmitate (135 μM), or ceramide (15 μM) for 24 h. In staurosporine-stimulated HL-1 cardiomyocytes, phosphatidylserine exposure, Bax-to-Bcl-2 ratio, Bad phosphorylation (Ser(136)), BNIP3 expression, mitochondrial membrane depolarization, cytochrome c release, caspase-3 activation, DNA fragmentation, and mammalian target of rapamycin (mTOR)/p70S6K phosphorylation (Ser(2448) and Thr(389), respectively) were assessed. Apoptotic hallmarks were also measured in the absence or presence of low (5 mM) and high (10 mM) concentrations of glucose. In addition, phosphatidylserine exposure and DNA fragmentation were analyzed in palmitate- and ceramide-stimulated cells. Staurosporine increased apoptosis in HL-1 cardiomyocytes. GLP-1 (100 nM) partially inhibited staurosporine-induced mitochondrial membrane depolarization and completely blocked the rest of the staurosporine-induced apoptotic changes. This cytoprotective effect was mainly mediated by phosphatidylinositol 3-kinase (PI3K) and partially dependent on ERK1/2. Increasing concentrations of glucose did not influence GLP-1-induced protection against staurosporine. Furthermore, GLP-1 inhibited palmitate- and ceramide-induced phosphatidylserine exposure and DNA fragmentation. Incretin GLP-1 protects HL-1 cardiomyocytes against activation of apoptosis. This cytoprotective ability is mediated mainly by the PI3K pathway and partially by the ERK1/2 pathway and seems to be glucose independent. It is proposed that therapies based on GLP-1 may contribute to prevent cardiomyocyte apoptosis.
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Affiliation(s)
- Susana Ravassa
- Division of Cardiovascular Sciences, Center for Applied Medical Research, University Clinic, School of Medicine, University of Navarra, Pamplona, Spain.
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