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Carneiro L, Fenech C, Liénard F, Grall S, Abed B, Haydar J, Allard C, Desmoulins L, Paccoud R, Brindisi MC, Mouillot T, Brondel L, Fioramonti X, Pénicaud L, Jacquin-Piques A, Leloup C. Hypothalamic Glucose Hypersensitivity-Induced Insulin Secretion in the Obese Zücker Rat Is Reversed by Central Ghrelin Treatment. Antioxid Redox Signal 2024; 40:837-849. [PMID: 36656675 DOI: 10.1089/ars.2022.0031] [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] [Indexed: 01/20/2023]
Abstract
Aims: Part of hypothalamic (mediobasal hypothalamus [MBH]) neurons detect changes in blood glucose levels that in turn coordinate the vagal control of insulin secretion. This control cascade requires the production of mitochondrial reactive oxygen species (mROS), which is altered in models of obesity and insulin resistance. Obese, insulin-resistant Zücker rats are characterized by hypothalamic hypersensitivity to glucose. This initiates an abnormal vagus-induced insulin secretion, associated with an overproduction of mROS in response to a low glucose dose. Here, we hypothesized that ghrelin, known to buffer reactive oxygen species (ROS) via mitochondrial function, may be a major component of the hypothalamic glucose hypersensitivity in the hypoghrelinemic obese Zücker rat. Results: Hypothalamic glucose hypersensitivity-induced insulin secretion of Zücker obese rats was reversed by ghrelin pretreatment. The overproduction of MBH mROS in response to a low glucose load no longer occurred in obese rats that had previously received the cerebral ghrelin infusion. This decrease in mROS production was accompanied by a normalization of oxidative phosphorylation (OXPHOS). Conversely, blocking the action of ghrelin with a growth hormone secretagogue receptor antagonist in a model of hyperghrelinemia (fasted rats) completely restored hypothalamic glucose sensing-induced insulin secretion that was almost absent in this physiological situation. Accordingly, ROS signaling and mitochondrial activity were increased by the ghrelin receptor antagonist. Innovation: These results demonstrate for the first time that ghrelin addressed only to the brain could have a protective effect on the defective control of insulin secretion in the insulin-resistant, hypoghrelinemic obese subject. Conclusions: Ghrelin, through its action on OXPHOS, modulates mROS signaling in response to cerebral hyperglycemia and the consequent vagal control of insulin secretion. In insulin-resistant obese states, brain hypoghrelinemia could be responsible for the nervous defect in insulin secretion.
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Affiliation(s)
- Lionel Carneiro
- Centre des Sciences du Goût et de l'Alimentation, UMR Université de Bourgogne, CNRS 6265, INRAE 1324, Université Bourgogne Franche-Comté, Dijon, France
- INSERM U1220, Institut de Recherche en Santé Digestive (IRSD), Université Paul Sabatier, Toulouse III, CHU Purpan, Toulouse, France
| | - Claire Fenech
- Centre des Sciences du Goût et de l'Alimentation, UMR Université de Bourgogne, CNRS 6265, INRAE 1324, Université Bourgogne Franche-Comté, Dijon, France
| | - Fabienne Liénard
- Centre des Sciences du Goût et de l'Alimentation, UMR Université de Bourgogne, CNRS 6265, INRAE 1324, Université Bourgogne Franche-Comté, Dijon, France
| | - Sylvie Grall
- Centre des Sciences du Goût et de l'Alimentation, UMR Université de Bourgogne, CNRS 6265, INRAE 1324, Université Bourgogne Franche-Comté, Dijon, France
| | - Besma Abed
- Centre des Sciences du Goût et de l'Alimentation, UMR Université de Bourgogne, CNRS 6265, INRAE 1324, Université Bourgogne Franche-Comté, Dijon, France
| | - Joulia Haydar
- Centre des Sciences du Goût et de l'Alimentation, UMR Université de Bourgogne, CNRS 6265, INRAE 1324, Université Bourgogne Franche-Comté, Dijon, France
| | - Camille Allard
- Centre des Sciences du Goût et de l'Alimentation, UMR Université de Bourgogne, CNRS 6265, INRAE 1324, Université Bourgogne Franche-Comté, Dijon, France
- University of Bordeaux, INSERM U1215, Neurocentre Magendie, Bordeaux, France
| | - Lucie Desmoulins
- Centre des Sciences du Goût et de l'Alimentation, UMR Université de Bourgogne, CNRS 6265, INRAE 1324, Université Bourgogne Franche-Comté, Dijon, France
- Department of Physiology, School of Medicine, Tulane University, New Orleans, Louisiana, USA
| | - Romain Paccoud
- Centre des Sciences du Goût et de l'Alimentation, UMR Université de Bourgogne, CNRS 6265, INRAE 1324, Université Bourgogne Franche-Comté, Dijon, France
| | - Marie-Claude Brindisi
- Centre des Sciences du Goût et de l'Alimentation, UMR Université de Bourgogne, CNRS 6265, INRAE 1324, Université Bourgogne Franche-Comté, Dijon, France
| | - Thomas Mouillot
- Centre des Sciences du Goût et de l'Alimentation, UMR Université de Bourgogne, CNRS 6265, INRAE 1324, Université Bourgogne Franche-Comté, Dijon, France
| | - Laurent Brondel
- Centre des Sciences du Goût et de l'Alimentation, UMR Université de Bourgogne, CNRS 6265, INRAE 1324, Université Bourgogne Franche-Comté, Dijon, France
| | - Xavier Fioramonti
- Centre des Sciences du Goût et de l'Alimentation, UMR Université de Bourgogne, CNRS 6265, INRAE 1324, Université Bourgogne Franche-Comté, Dijon, France
- NutriNeuro, UMR 1286 INRAE, Bordeaux University, Bordeaux INP, Neurocampus, Bordeaux, France
| | - Luc Pénicaud
- Centre des Sciences du Goût et de l'Alimentation, UMR Université de Bourgogne, CNRS 6265, INRAE 1324, Université Bourgogne Franche-Comté, Dijon, France
- STROMALab, CNRS ERL 5311, Toulouse, France
| | - Agnès Jacquin-Piques
- Centre des Sciences du Goût et de l'Alimentation, UMR Université de Bourgogne, CNRS 6265, INRAE 1324, Université Bourgogne Franche-Comté, Dijon, France
| | - Corinne Leloup
- Centre des Sciences du Goût et de l'Alimentation, UMR Université de Bourgogne, CNRS 6265, INRAE 1324, Université Bourgogne Franche-Comté, Dijon, France
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Tatum SM, Holland WL. Germline and conditional ghrelin knockout increases islet size. J Clin Invest 2023; 133:e175799. [PMID: 38099493 PMCID: PMC10721140 DOI: 10.1172/jci175799] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2023] Open
Abstract
Conflicting studies in recent years report that genetic or pharmacological increases or decreases in ghrelin either increase or have no effect on islet size. In this issue of the JCI, Gupta, Burstein, and colleagues applied a rigorous approach to determine the effects of reducing ghrelin on islet size in germline and conditional ghrelin-knockout mice as well as across varying ages and weight. Both germline and conditional ghrelin-knockout mice associated with increased islet size, which was further exacerbated by older age and diet-induced obesity. These findings suggest that modulation of ghrelin may open a therapeutic window to prevent or treat diabetes.
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Gupta D, Burstein AW, Schwalbe DC, Shankar K, Varshney S, Singh O, Paul S, Ogden SB, Osborne-Lawrence S, Metzger NP, Richard CP, Campbell JN, Zigman JM. Ghrelin deletion and conditional ghrelin cell ablation increase pancreatic islet size in mice. J Clin Invest 2023; 133:e169349. [PMID: 38099492 PMCID: PMC10721155 DOI: 10.1172/jci169349] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Accepted: 10/05/2023] [Indexed: 12/18/2023] Open
Abstract
Ghrelin exerts key effects on islet hormone secretion to regulate blood glucose levels. Here, we sought to determine whether ghrelin's effects on islets extend to the alteration of islet size and β cell mass. We demonstrate that reducing ghrelin - by ghrelin gene knockout (GKO), conditional ghrelin cell ablation, or high-fat diet (HFD) feeding - was associated with increased mean islet size (up to 62%), percentage of large islets (up to 854%), and β cell cross-sectional area (up to 51%). In GKO mice, these effects were more apparent in 10- to 12-week-old mice than in 4-week-old mice. Higher β cell numbers from decreased β cell apoptosis drove the increase in β cell cross-sectional area. Conditional ghrelin cell ablation in adult mice increased the β cell number per islet by 40% within 4 weeks. A negative correlation between islet size and plasma ghrelin in HFD-fed plus chow-fed WT mice, together with even larger islet sizes in HFD-fed GKO mice than in HFD-fed WT mice, suggests that reduced ghrelin was not solely responsible for diet-induced obesity-associated islet enlargement. Single-cell transcriptomics revealed changes in gene expression in several GKO islet cell types, including upregulation of Manf, Dnajc3, and Gnas expression in β cells, which supports decreased β cell apoptosis and/or increased β cell proliferation. These effects of ghrelin reduction on islet morphology might prove useful when designing new therapies for diabetes.
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Affiliation(s)
- Deepali Gupta
- Center for Hypothalamic Research, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, Texas, USA
| | - Avi W. Burstein
- Center for Hypothalamic Research, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, Texas, USA
| | - Dana C. Schwalbe
- Department of Biology, University of Virginia, Charlottesville, Virginia, USA
| | - Kripa Shankar
- Center for Hypothalamic Research, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, Texas, USA
| | - Salil Varshney
- Center for Hypothalamic Research, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, Texas, USA
| | - Omprakash Singh
- Center for Hypothalamic Research, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, Texas, USA
| | - Subhojit Paul
- Center for Hypothalamic Research, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, Texas, USA
| | - Sean B. Ogden
- Center for Hypothalamic Research, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, Texas, USA
| | - Sherri Osborne-Lawrence
- Center for Hypothalamic Research, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, Texas, USA
| | - Nathan P. Metzger
- Center for Hypothalamic Research, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, Texas, USA
| | - Corine P. Richard
- Center for Hypothalamic Research, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, Texas, USA
| | - John N. Campbell
- Department of Biology, University of Virginia, Charlottesville, Virginia, USA
| | - Jeffrey M. Zigman
- Center for Hypothalamic Research, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, Texas, USA
- Division of Endocrinology and Metabolism, Department of Internal Medicine and
- Department of Psychiatry, UT Southwestern Medical Center, Dallas, Texas, USA
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Li N, Li N, Yang L, Gu H, Ji J, Zhou H, Zhu Q, Yu M, Sun Y, Zhou Y. GHSR1a deficiency suppresses inhibitory drive on dCA1 pyramidal neurons and contributes to memory reinforcement. Cereb Cortex 2023; 33:2612-2625. [PMID: 35797708 DOI: 10.1093/cercor/bhac230] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Revised: 05/12/2022] [Accepted: 05/13/2022] [Indexed: 11/12/2022] Open
Abstract
Growth hormone secretagogue receptor 1a (GHSR1a)-the receptor for orexigenic hormone ghrelin-is a G protein-coupled receptor that is widely distributed in the brain, including the hippocampus. Studies have demonstrated that genetic deletion of GHSR1a affects memory, suggesting the importance of ghrelin/GHSR1a signaling in cognitive control. However, current reports are controversial, and the mechanism underlying GHSR1a modulation of memory is uncertain. Here, we first report that global GHSR1a knockout enhances hippocampus-dependent memory, facilitates initial LTP in dorsal hippocampal Schaffer Collateral-CA1 synapses, and downregulates Akt activity in the hippocampus. Moreover, we show that the intrinsic excitability of GAD67+ interneurons-rather than neighboring pyramidal neurons in the dCA1-is suppressed by GHSR1a deletion, an effect that is antagonized by acute application of the Akt activator SC79. In addition, the inhibitory postsynaptic currents (IPSCs) on dCA1 pyramidal neurons are selectively reduced in mice with a GHSR1a deficiency. Finally, we demonstrate that selectively increasing the excitability of parvalbumin-expressing interneurons by hM3Dq-DREADDs increases IPSCs on dCA1 pyramidal neurons and normalizes memory in Ghsr1a KO mice. Our findings thus reveal a novel mechanism underlying memory enhancement of GHSR1a deficiency and herein support an adverse effect of GHSR1a signaling in hippocampus-dependent memory processes.
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Affiliation(s)
- Na Li
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Qingdao University, 308 Ningxia Rd, Qingdao, Shandong, 266071, China
- Department of Medicine, Qingdao Binhai University, 425 West Jialing River Rd, Qingdao, Shandong, 266555, China
| | - Nan Li
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Qingdao University, 308 Ningxia Rd, Qingdao, Shandong, 266071, China
- Department of Health and Life Sciences, University of Health and Rehabilitation Sciences, 17 Shandong Rd, Qingdao, Shandong, 266000, China
| | - Liu Yang
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Qingdao University, 308 Ningxia Rd, Qingdao, Shandong, 266071, China
| | - Huating Gu
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Qingdao University, 308 Ningxia Rd, Qingdao, Shandong, 266071, China
| | - Junjie Ji
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Qingdao University, 308 Ningxia Rd, Qingdao, Shandong, 266071, China
| | - Hao Zhou
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Qingdao University, 308 Ningxia Rd, Qingdao, Shandong, 266071, China
| | - Qianqian Zhu
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Qingdao University, 308 Ningxia Rd, Qingdao, Shandong, 266071, China
| | - Ming Yu
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Qingdao University, 308 Ningxia Rd, Qingdao, Shandong, 266071, China
- Department of Health and Life Sciences, University of Health and Rehabilitation Sciences, 17 Shandong Rd, Qingdao, Shandong, 266000, China
| | - Yuxiang Sun
- Department of Nutrition, Texas A&M University, 750 Agronomy Rd, College Station, TX, 77843, United States
| | - Yu Zhou
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Qingdao University, 308 Ningxia Rd, Qingdao, Shandong, 266071, China
- Department of Health and Life Sciences, University of Health and Rehabilitation Sciences, 17 Shandong Rd, Qingdao, Shandong, 266000, China
- Department of Physiology, Institute of Brain Sciences and Related Disorders, Qingdao University, 308 Ningxia Rd., Qingdao, Shandong, 266071, China
- Department of rehabilitation medicine, Affiliated Hospital of Qingdao University, 16 Jiangsu Rd., Qingdao, Shandong, 266000, China
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5
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Noh JY, Herrera M, Patil BS, Tan XD, Wright GA, Sun Y. The expression and function of growth hormone secretagogue receptor in immune cells: A current perspective. Exp Biol Med (Maywood) 2022; 247:2184-2191. [PMID: 36151745 PMCID: PMC9899990 DOI: 10.1177/15353702221121635] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The orexigenic hormone ghrelin and its receptor, growth hormone secretagogue receptor (GHS-R), have been extensively studied in the last two decades, revealing that ghrelin signaling has important implications in health and disease. Metabolic diseases, such as obesity and diabetes, are often accompanied by low-grade chronic inflammation, that has been coined as "meta-inflammation." Immune cells are key cellular mediators of meta-inflammation, controlling both initiation and resolution of inflammation. Immune cells exhibit dynamic changes in cellular characteristics and functional output in response to the stimuli/insults from their surrounding microenvironment. Emerging evidence shows that ghrelin has an important effect on inflammation, in addition to its well-known effects on metabolism. However, the cellular/molecular mechanism of ghrelin signaling in immunity is largely unknown because the knowledge in regard to the expression and function of GHS-R in immune cells is currently sparse. In this review, we have accumulated the recent findings related to the expression and functions of GHS-R in various immune cells under different physiological and pathological states. This review aims to inspire further investigation of the immunological roles of ghrelin signaling and advance the therapeutic applications of ghrelin signaling in meta-inflammation.
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Affiliation(s)
- Ji Yeon Noh
- Department of Nutrition, Texas A&M
University, College Station, TX 77843, USA
| | - Matthew Herrera
- Department of Nutrition, Texas A&M
University, College Station, TX 77843, USA
| | - Bhimanagouda S Patil
- Vegetable and Fruit Improvement Center,
Department of Horticultural Sciences, Texas A&M University, College Station, TX
77843, USA
| | - Xiao-Di Tan
- Department of Pediatrics, Feinberg
School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Gus A Wright
- Department of Veterinary Pathobiology,
Texas A&M University, College Station, TX 77843, USA
| | - Yuxiang Sun
- Department of Nutrition, Texas A&M
University, College Station, TX 77843, USA
- USDA/ARS Children’s Nutrition Research
Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030,
USA
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Mechanistic Investigation of GHS-R Mediated Glucose-Stimulated Insulin Secretion in Pancreatic Islets. Biomolecules 2022; 12:biom12030407. [PMID: 35327599 PMCID: PMC8945998 DOI: 10.3390/biom12030407] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2021] [Revised: 02/19/2022] [Accepted: 02/27/2022] [Indexed: 02/07/2023] Open
Abstract
Ghrelin receptor, a growth hormone secretagogue receptor (GHS-R), is expressed in the pancreas. Emerging evidence indicates that GHS-R is involved in the regulation of glucose-stimulated insulin secretion (GSIS), but the mechanism by which GHS-R regulates GSIS in the pancreas is unclear. In this study, we investigated the role of GHS-R on GSIS in detail using global Ghsr−/− mice (in vivo) and Ghsr-ablated pancreatic islets (ex vivo). GSIS was attenuated in both Ghsr−/− mice and Ghsr-ablated islets, while the islet morphology was similar between WT and Ghsr−/− mice. To elucidate the mechanism underpinning Ghsr-mediated GSIS, we investigated the key steps of the GSIS signaling cascade. The gene expression of glucose transporter 2 (Glut2) and the glucose-metabolic intermediate—glucose-6-phosphate (G6P) were reduced in Ghsr-ablated islets, supporting decreased glucose uptake. There was no difference in mitochondrial DNA content in the islets of WT and Ghsr−/− mice, but the ATP/ADP ratio in Ghsr−/− islets was significantly lower than that of WT islets. Moreover, the expression of pancreatic and duodenal homeobox 1 (Pdx1), as well as insulin signaling genes of insulin receptor (IR) and insulin receptor substrates 1 and 2 (IRS1/IRS2), was downregulated in Ghsr−/− islets. Akt is the key mediator of the insulin signaling cascade. Concurrently, Akt phosphorylation was reduced in the pancreas of Ghsr−/− mice under both insulin-stimulated and homeostatic conditions. These findings demonstrate that GHS-R ablation affects key components of the insulin signaling pathway in the pancreas, suggesting the existence of a cross-talk between GHS-R and the insulin signaling pathway in pancreatic islets, and GHS-R likely regulates GSIS via the Akt-Pdx1-GLUT2 pathway.
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Lugilde J, Casado S, Beiroa D, Cuñarro J, Garcia-Lavandeira M, Álvarez CV, Nogueiras R, Diéguez C, Tovar S. LEAP-2 Counteracts Ghrelin-Induced Food Intake in a Nutrient, Growth Hormone and Age Independent Manner. Cells 2022; 11:cells11030324. [PMID: 35159134 PMCID: PMC8834077 DOI: 10.3390/cells11030324] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2021] [Revised: 01/16/2022] [Accepted: 01/17/2022] [Indexed: 12/30/2022] Open
Abstract
Data gleaned recently shows that ghrelin, a stomach derived peptide, and liver-expressed-antimicrobial peptide 2 (LEAP-2) play opposite roles on food intake. However, the data available with LEAP-2 in relation to in vivo studies are still very scanty and some key questions regarding the interplay among ghrelin and LEAP-2 remain to be answered. In this work, using rats and mice, we study fasting-induced food intake as well as testing the effect of diet exposure, e.g., standard diet and high fat diet, in terms of ghrelin-induced food intake. The anorexigenic effect of LEAP-2 on fasting induced food intake appears to be dependent on energy stores, being more evident in ob/ob than in wild type mice and also in animals exposed to high fat diet. On the other hand, LEAP-2 administration markedly inhibited ghrelin-induced food intake in lean, obese (ob/ob and DIO) mice, aged rats and GH-deficient dwarf rats. In contrast, the inhibitory effect on glucose levels can only be observed in some specific experimental models indicating that the mechanisms involved are likely to be quite different. Taken together from these data, LEAP-2 emerged as a potential candidate to be therapeutically useful in obesity.
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Affiliation(s)
- Javier Lugilde
- Departamento de Fisioloxía and Centro de Investigación en Medicina Molecular (CIMUS), Instituto de Investigaciones Sanitarias de Santiago de Compostela (IDIS), Universidade de Santiago de Compostela, 15782 Santiago de Compostela, Spain; (J.L.); (S.C.); (D.B.); (J.C.); (R.N.)
| | - Sabela Casado
- Departamento de Fisioloxía and Centro de Investigación en Medicina Molecular (CIMUS), Instituto de Investigaciones Sanitarias de Santiago de Compostela (IDIS), Universidade de Santiago de Compostela, 15782 Santiago de Compostela, Spain; (J.L.); (S.C.); (D.B.); (J.C.); (R.N.)
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), 15706 Santiago de Compostela, Spain
| | - Daniel Beiroa
- Departamento de Fisioloxía and Centro de Investigación en Medicina Molecular (CIMUS), Instituto de Investigaciones Sanitarias de Santiago de Compostela (IDIS), Universidade de Santiago de Compostela, 15782 Santiago de Compostela, Spain; (J.L.); (S.C.); (D.B.); (J.C.); (R.N.)
| | - Juan Cuñarro
- Departamento de Fisioloxía and Centro de Investigación en Medicina Molecular (CIMUS), Instituto de Investigaciones Sanitarias de Santiago de Compostela (IDIS), Universidade de Santiago de Compostela, 15782 Santiago de Compostela, Spain; (J.L.); (S.C.); (D.B.); (J.C.); (R.N.)
| | - Montserrat Garcia-Lavandeira
- Neoplasia & Endocrine Differentiation P0L5, Centro de Investigación en Medicina Molecular y Enfermedades Crónicas (CIMUS), University of Santiago de Compostela (USC), 15782 Santiago de Compostela, Spain; (M.G.-L.); (C.V.Á.)
| | - Clara V. Álvarez
- Neoplasia & Endocrine Differentiation P0L5, Centro de Investigación en Medicina Molecular y Enfermedades Crónicas (CIMUS), University of Santiago de Compostela (USC), 15782 Santiago de Compostela, Spain; (M.G.-L.); (C.V.Á.)
| | - Rubén Nogueiras
- Departamento de Fisioloxía and Centro de Investigación en Medicina Molecular (CIMUS), Instituto de Investigaciones Sanitarias de Santiago de Compostela (IDIS), Universidade de Santiago de Compostela, 15782 Santiago de Compostela, Spain; (J.L.); (S.C.); (D.B.); (J.C.); (R.N.)
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), 15706 Santiago de Compostela, Spain
| | - Carlos Diéguez
- Departamento de Fisioloxía and Centro de Investigación en Medicina Molecular (CIMUS), Instituto de Investigaciones Sanitarias de Santiago de Compostela (IDIS), Universidade de Santiago de Compostela, 15782 Santiago de Compostela, Spain; (J.L.); (S.C.); (D.B.); (J.C.); (R.N.)
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), 15706 Santiago de Compostela, Spain
- Correspondence: (C.D.); (S.T.)
| | - Sulay Tovar
- Departamento de Fisioloxía and Centro de Investigación en Medicina Molecular (CIMUS), Instituto de Investigaciones Sanitarias de Santiago de Compostela (IDIS), Universidade de Santiago de Compostela, 15782 Santiago de Compostela, Spain; (J.L.); (S.C.); (D.B.); (J.C.); (R.N.)
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), 15706 Santiago de Compostela, Spain
- Correspondence: (C.D.); (S.T.)
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Jiménez-Vacas JM, Montero-Hidalgo AJ, Gómez-Gómez E, Fuentes-Fayos AC, Ruiz-Pino F, Guler I, Camargo A, Anglada FJ, Carrasco-Valiente J, Tena-Sempere M, Sarmento-Cabral A, Castaño JP, Gahete MD, Luque RM. In1-Ghrelin Splicing Variant as a Key Element in the Pathophysiological Association Between Obesity and Prostate Cancer. J Clin Endocrinol Metab 2021; 106:e4956-e4968. [PMID: 34255835 DOI: 10.1210/clinem/dgab516] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
CONTEXT Recent studies emphasize the importance of considering the metabolic status to develop personalized medicine approaches. This is especially relevant in prostate cancer (PCa), wherein the diagnostic capability of prostate-specific antigen (PSA) dramatically drops when considering patients with PSA levels ranging from 3 to 10 ng/mL, the so-called grey zone. Hence, additional noninvasive diagnostic and/or prognostic PCa biomarkers are urgently needed, especially in the metabolic-status context. OBJECTIVE To assess the potential relation of urine In1-ghrelin (a ghrelin-splicing variant) levels with metabolic-related/pathological conditions (eg, obesity, diabetes, body mass index, insulin and glucose levels) and to define its potential clinical value in PCa (diagnostic/prognostic capacity) and relationship with PCa risk in patients with PSA in the grey zone. METHODS Urine In1-ghrelin levels were measured by radioimmunoassay in a clinically, metabolically, pathologically well-characterized cohort of patients without (n = 397) and with (n = 213) PCa with PSA in the grey zone. RESULTS Key obesity-related factors associated with PCa risk (BMI, diabetes, glucose and insulin levels) were strongly correlated to In1-ghrelin levels. Importantly, In1-ghrelin levels were higher in PCa patients compared to control patients with suspect of PCa but negative biopsy). Moreover, high In1-ghrelin levels were associated with increased PCa risk and linked to PCa aggressiveness (eg, tumor stage, lymphovascular invasion). In1-ghrelin levels added significant diagnostic value to a clinical model consisting of age, suspicious digital rectal exam, previous biopsy, and PSA levels. Furthermore, a multivariate model consisting of clinical and metabolic variables, including In1-ghrelin levels, showed high specificity and sensitivity to diagnose PCa (area under the receiver operating characteristic curve = 0.740). CONCLUSIONS Urine In1-ghrelin levels are associated with obesity-related factors and PCa risk and aggressiveness and could represent a novel and valuable noninvasive PCa biomarker, as well as a potential link in the pathophysiological relationship between obesity and PCa.
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Affiliation(s)
- Juan M Jiménez-Vacas
- Maimonides Institute of Biomedical Research of Cordoba (IMIBIC), Cordoba, Spain
- Department of Cell Biology, Physiology and Immunology, University of Cordoba, Cordoba, Spain
- Reina Sofia University Hospital (HURS), Cordoba, Spain
- CIBER Physiopathology of Obesity and Nutrition (CIBERobn), Cordoba, Spain
| | - Antonio J Montero-Hidalgo
- Maimonides Institute of Biomedical Research of Cordoba (IMIBIC), Cordoba, Spain
- Department of Cell Biology, Physiology and Immunology, University of Cordoba, Cordoba, Spain
- Reina Sofia University Hospital (HURS), Cordoba, Spain
- CIBER Physiopathology of Obesity and Nutrition (CIBERobn), Cordoba, Spain
| | - Enrique Gómez-Gómez
- Maimonides Institute of Biomedical Research of Cordoba (IMIBIC), Cordoba, Spain
- Reina Sofia University Hospital (HURS), Cordoba, Spain
- Urology Service, HURS/IMIBIC, Cordoba, Spain
| | - Antonio C Fuentes-Fayos
- Maimonides Institute of Biomedical Research of Cordoba (IMIBIC), Cordoba, Spain
- Department of Cell Biology, Physiology and Immunology, University of Cordoba, Cordoba, Spain
- Reina Sofia University Hospital (HURS), Cordoba, Spain
- CIBER Physiopathology of Obesity and Nutrition (CIBERobn), Cordoba, Spain
| | - Francisco Ruiz-Pino
- Maimonides Institute of Biomedical Research of Cordoba (IMIBIC), Cordoba, Spain
- Department of Cell Biology, Physiology and Immunology, University of Cordoba, Cordoba, Spain
- Reina Sofia University Hospital (HURS), Cordoba, Spain
- CIBER Physiopathology of Obesity and Nutrition (CIBERobn), Cordoba, Spain
| | - Ipek Guler
- Leuven Biostatistics and Statistical Bioinformatics Centre (L-BioStat), Katholiek Universiteit (KU) Leuven, University of Leuven, Leuven, Belgium
| | - Antonio Camargo
- Maimonides Institute of Biomedical Research of Cordoba (IMIBIC), Cordoba, Spain
- Reina Sofia University Hospital (HURS), Cordoba, Spain
- CIBER Physiopathology of Obesity and Nutrition (CIBERobn), Cordoba, Spain
- Lipids and Atherosclerosis Unit, Internal Medicine Unit, Reina Sofia University Hospital, Cordoba, Spain
| | - Francisco J Anglada
- Maimonides Institute of Biomedical Research of Cordoba (IMIBIC), Cordoba, Spain
- Reina Sofia University Hospital (HURS), Cordoba, Spain
- Urology Service, HURS/IMIBIC, Cordoba, Spain
| | - Julia Carrasco-Valiente
- Maimonides Institute of Biomedical Research of Cordoba (IMIBIC), Cordoba, Spain
- Reina Sofia University Hospital (HURS), Cordoba, Spain
- Urology Service, HURS/IMIBIC, Cordoba, Spain
| | - Manuel Tena-Sempere
- Maimonides Institute of Biomedical Research of Cordoba (IMIBIC), Cordoba, Spain
- Department of Cell Biology, Physiology and Immunology, University of Cordoba, Cordoba, Spain
- Reina Sofia University Hospital (HURS), Cordoba, Spain
- CIBER Physiopathology of Obesity and Nutrition (CIBERobn), Cordoba, Spain
| | - André Sarmento-Cabral
- Maimonides Institute of Biomedical Research of Cordoba (IMIBIC), Cordoba, Spain
- Department of Cell Biology, Physiology and Immunology, University of Cordoba, Cordoba, Spain
- Reina Sofia University Hospital (HURS), Cordoba, Spain
- CIBER Physiopathology of Obesity and Nutrition (CIBERobn), Cordoba, Spain
| | - Justo P Castaño
- Maimonides Institute of Biomedical Research of Cordoba (IMIBIC), Cordoba, Spain
- Department of Cell Biology, Physiology and Immunology, University of Cordoba, Cordoba, Spain
- Reina Sofia University Hospital (HURS), Cordoba, Spain
- CIBER Physiopathology of Obesity and Nutrition (CIBERobn), Cordoba, Spain
| | - Manuel D Gahete
- Maimonides Institute of Biomedical Research of Cordoba (IMIBIC), Cordoba, Spain
- Department of Cell Biology, Physiology and Immunology, University of Cordoba, Cordoba, Spain
- Reina Sofia University Hospital (HURS), Cordoba, Spain
- CIBER Physiopathology of Obesity and Nutrition (CIBERobn), Cordoba, Spain
| | - Raúl M Luque
- Maimonides Institute of Biomedical Research of Cordoba (IMIBIC), Cordoba, Spain
- Department of Cell Biology, Physiology and Immunology, University of Cordoba, Cordoba, Spain
- Reina Sofia University Hospital (HURS), Cordoba, Spain
- CIBER Physiopathology of Obesity and Nutrition (CIBERobn), Cordoba, Spain
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9
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Peris-Sampedro F, Le May MV, Stoltenborg I, Schéle E, Dickson SL. A skeleton in the cupboard in ghrelin research: Where are the skinny dwarfs? J Neuroendocrinol 2021; 33:e13025. [PMID: 34427011 DOI: 10.1111/jne.13025] [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: 04/30/2021] [Revised: 07/09/2021] [Accepted: 08/05/2021] [Indexed: 12/15/2022]
Abstract
Based on studies delivering ghrelin or ghrelin receptor agonists, we have learned a great deal about the importance of the brain ghrelin signalling system for a wide range of physiological processes that include feeding behaviours, growth hormone secretion and glucose homeostasis. Because these processes can be considered as essential to life, the question arises as to why mouse models of depleted ghrelin signalling are not all skinny dwarfs with a host of behavioural and metabolic problems. Here, we provide a systematic detailed review of the phenotype of mice with deficient ghrelin signalling to help better understand the relevance and importance of the brain ghrelin signalling system, with a particular emphasis on those questions that remain unanswered.
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Affiliation(s)
- Fiona Peris-Sampedro
- Department of Physiology/Endocrine, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
| | - Marie V Le May
- Department of Physiology/Endocrine, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
| | - Iris Stoltenborg
- Department of Physiology/Endocrine, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
| | - Erik Schéle
- Department of Physiology/Endocrine, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
| | - Suzanne L Dickson
- Department of Physiology/Endocrine, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
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10
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Huang Z, Lu X, Huang L, Zhang C, Veldhuis JD, Cowley MA, Chen C. Stimulation of endogenous pulsatile growth hormone secretion by activation of growth hormone secretagogue receptor reduces the fat accumulation and improves the insulin sensitivity in obese mice. FASEB J 2021; 35:e21269. [PMID: 33368660 DOI: 10.1096/fj.202001924rr] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2020] [Revised: 11/23/2020] [Accepted: 11/30/2020] [Indexed: 12/18/2022]
Abstract
Obese individuals often show low growth hormone (GH) secretion, which leads to reduced lipid mobilization and further fat accumulation. Pharmacological approaches to increase GH levels in obese individuals by GH injection or GH-releasing hormone receptor agonist showed promising effects on fat reduction. However, side effects on glucose metabolism and the heavy costs on making large peptides hindered their clinical application. Here, we tested whether stimulation of endogenous GH secretion by a synthetic GH secretagogue receptor (GHSR) agonist, hexarelin, improved the metabolism in a hyperphagic obese mouse model. Male melanocortin 4 receptor knockout mice (MC4RKO) were pair-fed and received continuous hexarelin (10.56 μg/day) or vehicle infusion by an osmotic pump for 3-4 weeks. Hexarelin treatment significantly increased the pulsatile GH secretion without detectable alteration on basal GH secretion in MC4RKO mice. The treated mice showed increased lipolysis and lipid oxidation in the adipose tissue, and reduced de novo lipogenesis in the liver, leading to reduced visceral fat mass, reduced triglyceride content in liver, and unchanged circulating free fatty acid levels. Importantly, hexarelin treatment improved the whole-body insulin sensitivity but did not alter glucose tolerance, insulin levels, or insulin-like growth factor 1 (IGF-1) levels. The metabolic effects of hexarelin were likely through the direct action of GH, as indicated by the increased expression level of genes involved in GH signaling pathways in visceral adipose tissues and liver. In conclusion, hexarelin treatment stimulated the pulsatile GH secretion and reduced the fat accumulation in visceral depots and liver in obese MC4RKO mice with improved insulin sensitivity without altered levels of insulin or IGF-1. It provides evidence for managing obesity by enhancing pulsatile GH secretion through activation of GHSR in the pituitary gland.
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Affiliation(s)
- Zhengxiang Huang
- School of Biomedical Sciences, University of Queensland, St Lucia, QLD, Australia
| | - Xuehan Lu
- School of Biomedical Sciences, University of Queensland, St Lucia, QLD, Australia
| | - Lili Huang
- School of Biomedical Sciences, University of Queensland, St Lucia, QLD, Australia
| | - Chunhong Zhang
- School of Biomedical Sciences, University of Queensland, St Lucia, QLD, Australia
| | - Johannes D Veldhuis
- Department of Medicine, Endocrine Research Unit, Mayo School of Graduate Medical Education, Clinical Translational Science Center, Mayo Clinic, Rochester, MN, USA
| | - Michael A Cowley
- Department of Physiology, Monash University, Melbourne, VIC, Australia
| | - Chen Chen
- School of Biomedical Sciences, University of Queensland, St Lucia, QLD, Australia
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11
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β Cell GHS-R Regulates Insulin Secretion and Sensitivity. Int J Mol Sci 2021; 22:ijms22083950. [PMID: 33920473 PMCID: PMC8069226 DOI: 10.3390/ijms22083950] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 04/09/2021] [Accepted: 04/09/2021] [Indexed: 12/14/2022] Open
Abstract
Growth hormone secretagogue receptor (GHS-R) is widely known to regulate food intake and adiposity, but its role in glucose homeostasis is unclear. In this study, we investigated the expression of GHS-R in mouse pancreatic islets and its role in glycemic regulation. We used Ghsr-IRES-tauGFP mice, with Green Fluorescent Protein (GFP) as a surrogate for GHS-R, to demonstrate the GFP co-localization with insulin and glucagon expression in pancreatic islets, confirming GHS-R expression in β and α cells. We then generated β-cell-specific GHSR-deleted mice with MIP-Cre/ERT and validated that GHS-R suppression was restricted to the pancreatic islets. MIP-Cre/ERT;Ghsrf/f mice showed normal energy homeostasis with similar body weight, body composition, and indirect calorimetry profile. Interestingly, MIP-Cre/ERT;Ghsrf/f mice exhibited an impressive phenotype in glucose homeostasis. Compared to controls, MIP-Cre/ERT;Ghsrf/f mice showed lower fasting blood glucose and insulin; reduced first-phase insulin secretion during a glucose tolerance test (GTT) and glucose-stimulated insulin secretion (GSIS) test in vivo. The isolated pancreatic islets of MIP-Cre/ERT;Ghsrf/f mice also showed reduced insulin secretion during GSIS ex vivo. Further, MIP-Cre/ERT;Ghsrf/f mice exhibited improved insulin sensitivity during insulin tolerance tests (ITT). Overall, our results confirmed GHS-R expression in pancreatic β and α cells; GHS-R cell-autonomously regulated GSIS and modulated systemic insulin sensitivity. In conclusion, β cell GHS-R was an important regulator of glucose homeostasis, and GHS-R antagonists may have therapeutic potential for Type 2 Diabetes.
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12
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"A LEAP 2 conclusions? Targeting the ghrelin system to treat obesity and diabetes". Mol Metab 2020; 46:101128. [PMID: 33246141 PMCID: PMC8085568 DOI: 10.1016/j.molmet.2020.101128] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/30/2020] [Revised: 11/15/2020] [Accepted: 11/20/2020] [Indexed: 02/08/2023] Open
Abstract
BACKGROUND The hormone ghrelin stimulates food intake, promotes adiposity, increases body weight, and elevates blood glucose. Consequently, alterations in plasma ghrelin levels and the functioning of other components of the broader ghrelin system have been proposed as potential contributors to obesity and diabetes. Furthermore, targeting the ghrelin system has been proposed as a novel therapeutic strategy for obesity and diabetes. SCOPE OF REVIEW The current review focuses on the potential for targeting ghrelin and other proteins comprising the ghrelin system as a treatment for obesity and diabetes. The main components of the ghrelin system are introduced. Data supporting a role for the endogenous ghrelin system in the development of obesity and diabetes along with data that seemingly refute such a role are outlined. An argument for further research into the development of ghrelin system-targeted therapeutic agents is delineated. Also, an evidence-based discussion of potential factors and contexts that might influence the efficacy of this class of therapeutics is provided. MAJOR CONCLUSIONS It would not be a "leap to" conclusions to suggest that agents which target the ghrelin system - including those that lower acyl-ghrelin levels, raise LEAP2 levels, block GHSR activity, and/or raise desacyl-ghrelin signaling - could represent efficacious novel treatments for obesity and diabetes.
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13
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Hay RE, Edwards A, Klein M, Hyland L, MacDonald D, Karatsoreos I, Hill MN, Abizaid A. Ghrelin Receptor Signaling Is Not Required for Glucocorticoid-Induced Obesity in Male Mice. Endocrinology 2020; 161:5636885. [PMID: 31748785 PMCID: PMC7445420 DOI: 10.1210/endocr/bqz023] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/12/2019] [Accepted: 11/19/2019] [Indexed: 12/11/2022]
Abstract
Chronically elevated levels of glucocorticoids increase food intake, weight gain, and adiposity. Similarly, ghrelin, a gut-secreted hormone, is also associated with weight gain, adiposity, and increased feeding. Here we sought to determine if corticosterone-induced metabolic and behavioral changes require functional ghrelin receptors (GHSR). To do this, we treated male C57BL mice with chronic corticosterone (CORT) mixed in their drinking water for 28 days. Half of these mice received the GHSR antagonist JMV2959 via osmotic minipumps while treated with CORT. In a second experiment, we gave the same CORT protocol to mice with a targeted mutation to the GHSR or their wild-type littermates. As expected, CORT treatment increased food intake, weight gain, and adiposity, but contrary to expectations, mice treated with a GHSR receptor antagonist or GHSR knockout (KO) mice did not show attenuated food intake, weight gain, or adiposity in response to CORT. Similarly, the effects of CORT on the liver were the same or more pronounced in GHSR antagonist-treated and GHSR KO mice. Treatment with JMV2959 did attenuate the effects of chronic CORT on glycemic regulation as determined by the glucose tolerance test. Finally, disruption of GHSR signaling resulted in behavioral responses associated with social withdrawal, potentially due to neuroprotective effects of GHSR activation. In all, we propose that blocking GHSR signaling helps to moderate glucose concentrations when CORT levels are high, but blocking GHSR signaling does not prevent increased food intake, weight gain, or increased adiposity produced by chronic CORT.
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Affiliation(s)
- Rebecca E Hay
- Department of Neuroscience, Carleton University, Ottawa, ON, Canada
| | - Alex Edwards
- Department of Neuroscience, Carleton University, Ottawa, ON, Canada
| | - Marianne Klein
- Department of Neuroscience, Carleton University, Ottawa, ON, Canada
| | - Lindsay Hyland
- Department of Neuroscience, Carleton University, Ottawa, ON, Canada
| | - David MacDonald
- Department of Neuroscience, Carleton University, Ottawa, ON, Canada
| | - Ilia Karatsoreos
- Department of Integrative Physiology and Neuroscience, Washington State University, Pullman, WA, US
| | - Matthew N Hill
- Hotchkiss Brain Institute, Department of Cell Biology and Anatomy, University of Calgary, Calgary, AB, Canada
| | - Alfonso Abizaid
- Department of Neuroscience, Carleton University, Ottawa, ON, Canada
- Correspondence: Alfonso Abizaid, Department of Neuroscience, Carleton University, 1125 Colonel By Drive, Ottawa, ON K1S5B6, Canada. E-mail:
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14
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Gray SM, Niu J, Zhang A, Svendsen B, Campbell JE, D'Alessio DA, Tong J. Intraislet Ghrelin Signaling Does Not Regulate Insulin Secretion From Adult Mice. Diabetes 2019; 68:1795-1805. [PMID: 31201280 PMCID: PMC6702634 DOI: 10.2337/db19-0079] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Accepted: 06/06/2019] [Indexed: 01/08/2023]
Abstract
Exogenous ghrelin reduces glucose-stimulated insulin secretion and endogenous ghrelin protects against hypoglycemia during starvation. Islet ε-cells produce ghrelin and δ-cells express growth hormone secretagogue receptor (GHSR), suggesting the possibility of a paracrine mechanism for islet ghrelin to reach high local concentrations and affect insulin secretion. GHSR has high constitutive activity and may act independently of ghrelin. The objective in this study was to determine whether an intraislet ghrelin-GHSR axis modulates insulin secretion and glucose metabolism using mouse models lacking ghrelin (Ghrl-/- ) or GHSR (Ghsr-/- ). Ghsr-/- and Ghsr+/+ mice had comparable islet ghrelin concentrations. Exogenous ghrelin decreased insulin secretion in perifused isolated islets in a GHSR-dependent manner. Islets isolated from Ghrl-/- or Ghsr-/- mice did not differ from controls in glucose-, alanine-, or GLP-1-stimulated insulin secretion during perifusion. Consistent with this finding, Ghrl-/- and Ghsr-/- male mice studied after either 6 or 16 h of fasting had blood glucose concentrations comparable with those of controls following intraperitoneal glucose, or insulin tolerance tests, or after mixed nutrient meals. Collectively, our data provide strong evidence against a paracrine ghrelin-GHSR axis mediating insulin secretion or glucose tolerance in lean, chow-fed adult mice.
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Affiliation(s)
| | | | | | | | - Jonathan E Campbell
- Duke Molecular Physiology Institute, Durham, NC
- Department of Pharmacology and Cancer Biology, Duke University, Durham, NC
| | - David A D'Alessio
- Duke Molecular Physiology Institute, Durham, NC
- Division of Endocrinology, Metabolism, and Nutrition, Department of Medicine, Duke University, Durham, NC
| | - Jenny Tong
- Duke Molecular Physiology Institute, Durham, NC
- Division of Endocrinology, Metabolism, and Nutrition, Department of Medicine, Duke University, Durham, NC
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15
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Gray SM, Page LC, Tong J. Ghrelin regulation of glucose metabolism. J Neuroendocrinol 2019; 31:e12705. [PMID: 30849212 PMCID: PMC6688917 DOI: 10.1111/jne.12705] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/05/2018] [Revised: 03/04/2019] [Accepted: 03/05/2019] [Indexed: 12/14/2022]
Abstract
Ghrelin and its receptor, the growth hormone secretagogue receptor 1a (GHSR1a), are implicated in the regulation of glucose metabolism via direct actions in the pancreatic islet, as well as peripheral insulin-sensitive tissues and the brain. Although many studies have explored the role of ghrelin in glucose tolerance and insulin secretion, a complete mechanistic understanding remains to be clarified. This review highlights the local expression and function of ghrelin and GHSR1a in pancreatic islets and how this axis may modulate insulin secretion from pancreatic β-cells. Additionally, we discuss the effect of ghrelin on in vivo glucose metabolism in rodents and humans, as well as the metabolic circumstances under which the action of ghrelin may predominate.
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Affiliation(s)
- Sarah. M. Gray
- Duke Molecular Physiology Institute, Duke University, Durham, NC 27701
| | - Laura C. Page
- Division of Endocrinology, Department of Pediatrics, Duke University, Durham, NC 27701
| | - Jenny Tong
- Duke Molecular Physiology Institute, Duke University, Durham, NC 27701
- Division of Endocrinology, Department of Pediatrics, Duke University, Durham, NC 27701
- Division of Endocrinology, Metabolism, and Nutrition, Department of Medicine, Duke University, Durham, NC 27701
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16
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Mani BK, Shankar K, Zigman JM. Ghrelin's Relationship to Blood Glucose. Endocrinology 2019; 160:1247-1261. [PMID: 30874792 PMCID: PMC6482034 DOI: 10.1210/en.2019-00074] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Accepted: 03/09/2019] [Indexed: 12/16/2022]
Abstract
Much effort has been directed at studying the orexigenic actions of administered ghrelin and the potential effects of the endogenous ghrelin system on food intake, food reward, body weight, adiposity, and energy expenditure. Although endogenous ghrelin's actions on some of these processes remain ambiguous, its glucoregulatory actions have emerged as well-recognized features during extreme metabolic conditions. The blood glucose-raising actions of ghrelin are beneficial during starvation-like conditions, defending against life-threatening falls in blood glucose, but they are seemingly detrimental in obese states and in certain monogenic forms of diabetes, contributing to hyperglycemia. Also of interest, blood glucose negatively regulates ghrelin secretion. This article reviews the literature suggesting the existence of a blood glucose-ghrelin axis and highlights the factors that mediate the glucoregulatory actions of ghrelin, especially during metabolic extremes such as starvation and diabetes.
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Affiliation(s)
- Bharath K Mani
- Division of Hypothalamic Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas
- Division of Endocrinology and Metabolism, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas
- Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Kripa Shankar
- Division of Hypothalamic Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas
- Division of Endocrinology and Metabolism, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas
- Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Jeffrey M Zigman
- Division of Hypothalamic Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas
- Division of Endocrinology and Metabolism, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas
- Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, Texas
- Correspondence: Jeffrey M. Zigman, MD, PhD, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, Texas 75390. E-mail:
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17
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Sun X, Yi Y, Liang B, Yang Y, He N, Ode KL, Uc A, Wang K, Gibson-Corley KN, Engelhardt JF, Norris AW. Incretin dysfunction and hyperglycemia in cystic fibrosis: Role of acyl-ghrelin. J Cyst Fibros 2019; 18:557-565. [PMID: 30738804 DOI: 10.1016/j.jcf.2019.01.010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2018] [Revised: 01/05/2019] [Accepted: 01/21/2019] [Indexed: 12/25/2022]
Abstract
BACKGROUND Insulin secretion is insufficient in cystic fibrosis (CF), even before diabetes is present, though the mechanisms involved remain unclear. Acyl-ghrelin (AG) can diminish insulin secretion and is elevated in humans with CF. METHODS We tested the hypothesis that elevated AG contributes to reduced insulin secretion and hyperglycemia in CF ferrets. RESULTS Fasting AG was elevated in CF versus non-CF ferrets. Similar to its effects in other species, AG administration in non-CF ferrets acutely reduced insulin, increased growth hormone, and induced hyperglycemia. During oral glucose tolerance testing, non-CF ferrets had responsive insulin, glucagon like peptide-1 (GLP-1) and gastric inhibitory polypeptide (GIP) levels and maintained normal glucose levels, whereas CF ferrets had insufficient responses and became hyperglycemic. Interestingly in wild-type ferrets, the acyl-ghrelin receptor antagonist [D-Lys3]-GHRP-6 impaired glucose tolerance, and abolished insulin, GLP-1, and GIP responses during glucose tolerance testing. By contrast, in CF ferrets [D-Lys3]-GHRP-6 improved glucose tolerance, enhanced the insulin-to-glucose ratio, but did not impact the already low GLP-1 and GIP levels. CONCLUSIONS These results suggest a mechanism by which elevated AG contributes to CF hyperglycemia through inhibition of insulin secretion, an effect magnified by low GLP-1 and GIP. Interventions that lower ghrelin, ghrelin action, and/or raise GLP-1 or GIP might improve glycemia in CF.
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Affiliation(s)
- Xingshen Sun
- Department of Anatomy and Cell Biology, University of Iowa, Iowa City, IA 52242, USA
| | - Yaling Yi
- Department of Anatomy and Cell Biology, University of Iowa, Iowa City, IA 52242, USA
| | - Bo Liang
- Department of Anatomy and Cell Biology, University of Iowa, Iowa City, IA 52242, USA
| | - Yu Yang
- Department of Anatomy and Cell Biology, University of Iowa, Iowa City, IA 52242, USA
| | - Nan He
- Department of Anatomy and Cell Biology, University of Iowa, Iowa City, IA 52242, USA
| | - Katie Larson Ode
- Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, IA 52242, USA; Department of Pediatrics, University of Iowa, Iowa City, IA 52242, USA
| | - Aliye Uc
- Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, IA 52242, USA; Department of Pediatrics, University of Iowa, Iowa City, IA 52242, USA
| | - Kai Wang
- Department of Biostatistics, University of Iowa, Iowa City, IA 52242, USA
| | - Katherine N Gibson-Corley
- Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, IA 52242, USA; Department of Pathology, University of Iowa, Iowa City, IA 52242, USA
| | - John F Engelhardt
- Department of Anatomy and Cell Biology, University of Iowa, Iowa City, IA 52242, USA; Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, IA 52242, USA.
| | - Andrew W Norris
- Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, IA 52242, USA; Department of Pediatrics, University of Iowa, Iowa City, IA 52242, USA; Department of Biochemistry, University of Iowa, Iowa City, IA 52242, USA.
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18
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Mosa R, Huang L, Li H, Grist M, LeRoith D, Chen C. Long-term treatment with the ghrelin receptor antagonist [d-Lys3]-GHRP-6 does not improve glucose homeostasis in nonobese diabetic MKR mice. Am J Physiol Regul Integr Comp Physiol 2017; 314:R71-R83. [PMID: 28903914 DOI: 10.1152/ajpregu.00157.2017] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Long-term treatment with the ghrelin receptor antagonist [d-Lys3]-GHRP-6 does not improve glucose homeostasis in nonobese diabetic MKR mice. Am J Physiol Regul Integr Comp Physiol 314: R71-R83, 2018. First published September 13, 2017; doi: 10.1152/ajpregu.00157.2017 .-Ghrelin secretion has been associated with increased caloric intake and adiposity. The expressions of ghrelin and its receptor (GHS-R1a) in the pancreas has raised the interest about the role of ghrelin in glucose homeostasis. Most of the studies showed that ghrelin promoted hyperglycemia and inhibited insulin secretion. This raised the interest in using GHS-R1a antagonists as therapeutic targets for type 2 diabetes. Available data of GHS-R antagonists are on a short-term basis. Moreover, the complexity of GHS-R1a signaling makes it difficult to understand the mechanism of action of GHS-R1a antagonists. This study examined the possible effects of long-term treatment with a GHS-R1a antagonist, [d-Lys3]-growth hormone-releasing peptide (GHRP)-6, on glucose homeostasis, food intake, and indirect calorimetric parameters in nonobese diabetic MKR mice. Our results showed that [d-Lys3]-GHRP-6 (200 nmol/mouse) reduced pulsatile growth hormone secretion and body fat mass as expected but worsened glucose and insulin intolerances and increased cumulative food intake unexpectedly. In addition, a significant increase in blood glucose and decreases in plasma insulin and C-peptide levels were observed in MKR mice following long-term [d-Lys3]-GHRP-6 treatment, suggesting a direct inhibition of insulin secretion. Immunofluorescence staining of pancreatic islets showed a proportional increase in somatostatin-positive cells and a decrease in insulin-positive cells in [d-Lys3]-GHRP-6-treated mice. Furthermore, [d-Lys3]-GHRP-6 stimulated food intake on long-term treatment via reduction of proopiomelanocortin gene expression and antagonized GH secretion via reduced growth hormone-releasing hormone gene expression in hypothalamus. These results demonstrate that [d-Lys3]-GHRP-6 is not completely opposite to ghrelin and may not be a treatment option for type 2 diabetes.
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Affiliation(s)
- Rasha Mosa
- School of Biomedical Sciences, Faculty of Medicine, University of Queensland, Brisbane, Australia
| | - Lili Huang
- School of Biomedical Sciences, Faculty of Medicine, University of Queensland, Brisbane, Australia
| | - Hongzhuo Li
- School of Biomedical Sciences, Faculty of Medicine, University of Queensland, Brisbane, Australia
| | - Michael Grist
- School of Biomedical Sciences, Faculty of Medicine, University of Queensland, Brisbane, Australia
| | - Derek LeRoith
- Clinical Endocrinology Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health , Bethesda, Maryland
| | - Chen Chen
- School of Biomedical Sciences, Faculty of Medicine, University of Queensland, Brisbane, Australia
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Abstract
Background: Cancer cachexia is a catabolic syndrome associated with uncontrolled muscle breakdown. There may be associated fat loss. Occurring in high frequency in advanced cancer, it is an indicator of poor prognosis. Besides weight loss, patients experience a cluster of symptoms including anorexia, early satiety, and weakness. The 3 stages of cachexia include stages of precachexia, cachexia, and refractory cachexia. Refractory cachexia is associated with active catabolism or the presence of factors that make active management of weight loss no longer possible. Patients with refractory cachexia often receive glucocorticoids or megasterol acetate. Glucocorticoid effect is short and responses to megasterol are variable. Anamorelin is a new agent for cancer anorexia-cachexia, with trials completed in advanced lung cancer. Acting as an oral mimetic of ghrelin, it improves appetite and muscle mass. This article reviews the pharmacology, pharmacodynamics, and effect on cancer cachexia. Methods: A PubMed search was done using the Medical Subject Headings term anamorelin. Articles were selected to provide a pharmacologic characterization of anamorelin. Results: Anamorelin increases muscle mass in patients with advanced cancer in 2-phase 3 trials. Conclusions: Anamorelin improves anorexia-cachexia symptoms in patients with advanced non–small-cell lung cancer.
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Affiliation(s)
- Eric Prommer
- UCLA/ VA Hospice & Palliative Medicine UCLA School of Medicine, Los Angeles, CA, USA
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Sagheb MM, Azarpira N, Mokhtary M. The effect of ghrelin on Kiss-1 and KissR gene transcription and insulin secretion in rat islets of Langerhans and CRI-D2 cell line. IRANIAN JOURNAL OF BASIC MEDICAL SCIENCES 2017; 20:36-40. [PMID: 28133522 PMCID: PMC5243972 DOI: 10.22038/ijbms.2017.8090] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Objective(s): Ghrelin is a peptide hormone that has been shown to have numerous central and peripheral effects. The central effects including GH secretion, food intake, and energy homeostasis are partly mediated by Kiss1- KissR signaling pathway. Ghrelin and its receptor are also expressed in the pancreatic islets. Ghrelin is one of the key metabolic factors controlling insulin secretion from the islets of Langerhans. We hypothesize that the inhibitory effect of ghrelin on KiSS-1 and KissR in the islet cells may be similar to the same inhibitory effect of ghrelin in the hypothalamus. Materials and Methods: To investigate the effect of ghrelin, we isolated the islets from adult male rats by collagenase and cultured CRI-D2 cell lines. Then, we incubated them with different concentrations of ghrelin for 24 hr. After RNA extraction and cDNA synthesis from both islets and CRI-D2 cells, the relative expression of KiSS-1 and KissR was evaluated by means of real-time PCR. Furthermore, we measured the amount of insulin secreted by the islets after incubation in different concentrations of ghrelin and glucose after 1 hr. Besides, we checked the viability of the cells after 24 hr cultivation. Results: Ghrelin significantly decreased the KiSS-1 and KissR mRNA transcription in rat islets and CRI-D2 cells. Besides, Ghrelin suppressed insulin secretion from pancreatic beta cells and CRI-D2 cells. Conclusion: These findings indicate the possibility that KiSS-1 and KissR mRNA expression is mediator of ghrelin function in the islets of Langerhans.
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Affiliation(s)
| | - Negar Azarpira
- Transplant Research Center, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Mokhtar Mokhtary
- Department of Biology, Kazeroon Branch, Islamic Azad University, Kazeroon, Iran
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Zhao Y, Zhang X, Chen J, Lin C, Shao R, Yan C, Chen C. Hexarelin Protects Rodent Pancreatic Β-Cells Function from Cytotoxic Effects of Streptozotocin Involving Mitochondrial Signalling Pathways In Vivo and In Vitro. PLoS One 2016; 11:e0149730. [PMID: 26918825 PMCID: PMC4769129 DOI: 10.1371/journal.pone.0149730] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2015] [Accepted: 02/04/2016] [Indexed: 01/25/2023] Open
Abstract
Mitochondrial functions are crucial for pancreatic β-cell survival and glucose-induced insulin secretion. Hexarelin (Hex) is a synthetic small peptide ghrelin analogue, which has been shown to protect cardiomyocytes from the ischemia-reperfusion process. In this study, we used in vitro and in vivo models of streptozotocin (STZ)-induced β-cell damage to study the protective effect of Hex and the associated mechanisms. We found that STZ produced a cytotoxic effect in a dose- and time-dependent manner in MIN6 cells (a mouse β-cell line). Hex (1.0 μM) decreased the STZ-induced damage in β-cells. Rhodamine 123 assay and superoxide DHE production assay revealed that Hex ameliorated STZ-induced mitochondrial damage and excessive superoxide activity in β-cells. In addition, Hex significantly reduced STZ-induced expression of cleaved Caspases-3, Caspases-9 and the ratio of pro-apoptotic protein Bax to anti-apoptotic protein Bcl-2 in MIN6 cells. We further examined the in vivo effect of Hex in a rat model of type 1 diabetes induced by STZ injection. Hex ameliorated STZ-induced decrease in plasma insulin and protected the structure of islets from STZ-induced disruption. Hex also ameliorated STZ-induced expression of cleaved Caspase-9 and the Bax in β-cells. In conclusion, our data indicate that Hex is able to protects β-cell mass from STZ-caused cytotoxic effects involving mitochondrial pathways in vitro and in vivo. Hex may serve as a potential protective agent for the management of diabetes.
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Affiliation(s)
- Yan Zhao
- Institute of Basic Medicine Science, Xi'an Medical University, Xi'an, China
- Department of Forensic Science, School of Medicine, Xi’an Jiaotong University, Xi’an, China
- School of Biomedical Sciences, The University of Queensland, St Lucia, QLD, Australia
| | - Xinli Zhang
- School of Biomedical Sciences, The University of Queensland, St Lucia, QLD, Australia
| | - Jiezhong Chen
- School of Biomedical Sciences, The University of Queensland, St Lucia, QLD, Australia
| | - Chao Lin
- School of Biomedical Sciences, The University of Queensland, St Lucia, QLD, Australia
| | - Renfu Shao
- Gene Cology Research Centre, Faculty of Science, Health, Education and Engineering, University of the Sunshine Coast, Maroochydore, QLD, Australia
| | - Chunxia Yan
- Department of Forensic Science, School of Medicine, Xi’an Jiaotong University, Xi’an, China
| | - Chen Chen
- School of Biomedical Sciences, The University of Queensland, St Lucia, QLD, Australia
- * E-mail:
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Addition of crude glycerin to pig diets: sow and litter performance, and metabolic and feed intake regulating hormones. Animal 2015; 10:919-26. [PMID: 26696303 DOI: 10.1017/s175173111500275x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
The continued growth in biofuel production has led to a search for alternative value-added applications of its main by-product, crude glycerin. The surplus glycerin production and a higher cost of feedstuffs have increased the emphasis on evaluating its nutritive value for animal feeding. The aim of this research was to evaluate the effect of the dietary addition of crude glycerin on sow and litter performance, and to determine the serum concentrations of hormones related to energy metabolism and feed intake in sows during gestation and lactation. A total of 63 sows were assigned randomly to one of three dietary treatments, containing 0, 3 or 6% crude glycerin (G0, G3 and G6, respectively) added to a barley-soybean meal-based diet. During gestation, none of the dietary treatments had an effect on performance, while during lactation, glycerin-fed sows consumed less feed than those fed the control diet (3.8 v. 4.2kg DM/day; P=0.007). Although lactating sows fed the G3 diet had a higher BW loss than those fed the control diet (���20.6 v. ���8.7 kg; P=0.002), this difference was not reflected in litter performance. In gestation, the inclusion of glycerin did not affect blood concentrations of insulin or cortisol. However, pregnant sows fed diets supplemented with glycerin showed lower concentrations of acyl-ghrelin and higher concentrations of leptin (���55 and +68%, respectively; P<0.001). In lactating sows, there were no differences between dietary treatments for any of the hormones measured. Pre-prandial acyl-ghrelin concentrations were positively correlated with cortisol concentrations during gestation (r=0.81; P=0.001) and lactation (r=0.61; P=0.015). In conclusion, the inclusion of up to 6% crude glycerin did not affect the performance of sows during the gestation period; however it had a negative effect on the feed intake and weight loss of lactating sows. Moreover, further research is needed to elucidate the potential relationship between glycerin inclusion levels in the diet and the serum concentrations of hormones related to feed intake and energy balance control.
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Al Massadi O, López M, Fernø J, Diéguez C, Nogueiras R. What is the real relevance of endogenous ghrelin? Peptides 2015; 70:1-6. [PMID: 26003396 DOI: 10.1016/j.peptides.2015.04.027] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/21/2015] [Revised: 04/06/2015] [Accepted: 04/07/2015] [Indexed: 12/11/2022]
Abstract
Ghrelin is a pleiotropic and ubiquitous gastric hormone implicated in body physiology. Ghrelin exhibits potent orexigenic actions and increases body weight and adiposity. Ghrelin is also involved in other metabolic functions among which we can highlight the GH releasing activity and the regulation of glucose homeostasis. Ghrelin needs the enzyme GOAT to be acylated, a step essential for binding to the GHSR1a receptor to exert its functions. Genetic animal models emerge as important tools to delineate the physiological relevance of ghrelin on energy balance. Despite the numerous reports using different genetically engineered mouse models targeting the ghrelin system, its endogenous relevance in metabolism seems to be less important than its pharmaceutical options.
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Affiliation(s)
- Omar Al Massadi
- Department of Physiology, School of Medicine-CIMUS, Instituto de Investigacion Sanitaria (IDIS), University of Santiago de Compostela, Avda. Barcelona s/n, 15782 Santiago de Compostela, Spain; CIBER Fisiopatologia de la Obesidad y Nutricion (CIBERobn), Santiago de Compostela (A Coruña) 15706, Spain.
| | - Miguel López
- Department of Physiology, School of Medicine-CIMUS, Instituto de Investigacion Sanitaria (IDIS), University of Santiago de Compostela, Avda. Barcelona s/n, 15782 Santiago de Compostela, Spain; CIBER Fisiopatologia de la Obesidad y Nutricion (CIBERobn), Santiago de Compostela (A Coruña) 15706, Spain
| | - Johan Fernø
- Department of Clinical Science, K. G. Jebsen Center for Diabetes Research, University of Bergen, Bergen N-5020, Norway
| | - Carlos Diéguez
- Department of Physiology, School of Medicine-CIMUS, Instituto de Investigacion Sanitaria (IDIS), University of Santiago de Compostela, Avda. Barcelona s/n, 15782 Santiago de Compostela, Spain; CIBER Fisiopatologia de la Obesidad y Nutricion (CIBERobn), Santiago de Compostela (A Coruña) 15706, Spain
| | - Rubén Nogueiras
- Department of Physiology, School of Medicine-CIMUS, Instituto de Investigacion Sanitaria (IDIS), University of Santiago de Compostela, Avda. Barcelona s/n, 15782 Santiago de Compostela, Spain; CIBER Fisiopatologia de la Obesidad y Nutricion (CIBERobn), Santiago de Compostela (A Coruña) 15706, Spain.
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Mosa RMH, Zhang Z, Shao R, Deng C, Chen J, Chen C. Implications of ghrelin and hexarelin in diabetes and diabetes-associated heart diseases. Endocrine 2015; 49:307-23. [PMID: 25645463 DOI: 10.1007/s12020-015-0531-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/03/2014] [Accepted: 01/12/2015] [Indexed: 02/07/2023]
Abstract
Ghrelin and its synthetic analog hexarelin are specific ligands of growth hormone secretagogue (GHS) receptor. GHS have strong growth hormone-releasing effect and other neuroendocrine activities such as stimulatory effects on prolactin and adrenocorticotropic hormone secretion. Recently, several studies have reported other beneficial functions of GHS that are independent of GH. Ghrelin and hexarelin, for examples, have been shown to exert GH-independent cardiovascular activity. Hexarelin has been reported to regulate peroxisome proliferator-activated receptor gamma (PPAR-γ) in macrophages and adipocytes. PPAR-γ is an important regulator of adipogenesis, lipid metabolism, and insulin sensitization. Ghrelin also shows protective effects on beta cells against lipotoxicity through activation of phosphatidylinositol-3 kinase/protein kinase B, c-Jun N-terminal kinase (JNK) inhibition, and nuclear exclusion of forkhead box protein O1. Acylated ghrelin (AG) and unacylated ghrelin (UAG) administration reduces glucose levels and increases insulin-producing beta cell number, and insulin secretion in pancreatectomized rats and in newborn rats treated with streptozotocin, suggesting a possible role of GHS in pancreatic regeneration. Therefore, the discovery of GHS has opened many new perspectives in endocrine, metabolic, and cardiovascular research areas, suggesting the possible therapeutic application in diabetes and diabetic complications especially diabetic cardiomyopathy. Here, we review the physiological roles of ghrelin and hexarelin in the protection and regeneration of beta cells and their roles in the regulation of insulin release, glucose, and fat metabolism and present their potential therapeutic effects in the treatment of diabetes and diabetic-associated heart diseases.
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Girardet C, Mavrikaki M, Southern MR, Smith RG, Butler AA. Assessing interactions between Ghsr and Mc3r reveals a role for AgRP in the expression of food anticipatory activity in male mice. Endocrinology 2014; 155:4843-55. [PMID: 25211592 PMCID: PMC4239417 DOI: 10.1210/en.2014-1497] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The stomach hormone ghrelin and hypothalamic melanocortin neurons belong to a gut-brain circuit controlling appetite and metabolic homeostasis. Mice lacking melanocortin-3 receptor (Mc3rKO) or growth hormone secretagogue receptor (GhsrKO) genes exhibit attenuated food anticipatory activity (FAA), a rise in locomotor activity anticipating mealtime, suggesting common circuitry regulating anticipatory responses to nutrient loading. To investigate the interaction between Ghsrs and Mc3rs, we compared food anticipatory responses in GhsrKO, Mc3rKO, and double Ghsr;Mc3r knockout (DKO) mice subjected to a hypocaloric restricted feeding (RF) protocol in constant dark or 12-hour light, 12-hour dark settings. DKO are viable, exhibiting no overt behavioral or metabolic phenotypes in ad libitum or fasting conditions. FAA was initially attenuated in all mutant strains in constant darkness. However, GhsrKO eventually exhibited a robust food anticipatory response, suggesting compensation. Mc3rKO and DKO did not compensate, indicating a continued requirement for Mc3rs in maintaining the expression of FAA in situations of RF. Abnormal regulation of hypothalamic agouti-related peptide/neuropeptide Y (AgRP/Npy) neurons previously observed during fasting may contribute to attenuated FAA in Mc3rKO. AgRP and Npy expression measured 1 hour before food presentation correlated positively with FAA. Absence of Mc3rs (but not Ghsrs) was associated with lower AgRP/Npy expression, suggesting attenuated responses to signals of negative energy balance. These observations support the importance of Mc3rs as modulators of anticipatory responses to feeding, with mice able to compensate for loss of Ghsrs. The behavioral deficits of Mc3rKO displayed during RF may be partially explained by reduced hunger sensations owing to abnormal regulation of orexigenic AgRP/Npy neurons.
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Affiliation(s)
- Clemence Girardet
- Departments of Metabolism and Aging (C.G., M.M., R.G.S., A.A.B.) and Molecular Therapeutics (M.R.S.), The Scripps Research Institute, Jupiter, Florida 33458; and Department of Pharmacological and Physiological Science (C.G., M.M., A.A.B.), Saint Louis University, Saint Louis, Missouri 63104
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Plasma Ghrelin Concentrations Are Negatively Correlated With Urine Albumin-to-Creatinine Ratio in Newly Diagnosed Type 2 Diabetes. Am J Med Sci 2014; 348:382-6. [DOI: 10.1097/maj.0000000000000297] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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Chabot F, Caron A, Laplante M, St-Pierre DH. Interrelationships between ghrelin, insulin and glucose homeostasis: Physiological relevance. World J Diabetes 2014; 5:328-341. [PMID: 24936254 PMCID: PMC4058737 DOI: 10.4239/wjd.v5.i3.328] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/09/2013] [Accepted: 05/08/2014] [Indexed: 02/05/2023] Open
Abstract
Ghrelin is a 28 amino acid peptide mainly derived from the oxyntic gland of the stomach. Both acylated (AG) and unacylated (UAG) forms of ghrelin are found in the circulation. Initially, AG was considered as the only bioactive form of ghrelin. However, recent advances indicate that both AG and UAG exert distinct and common effects in organisms. Soon after its discovery, ghrelin was shown to promote appetite and adiposity in animal and human models. In response to these anabolic effects, an impressive number of elements have suggested the influence of ghrelin on the regulation of metabolic functions and the development of obesity-related disorders. However, due to the complexity of its biochemical nature and the physiological processes it governs, some of the effects of ghrelin are still debated in the literature. Evidence suggests that ghrelin influences glucose homeostasis through the modulation of insulin secretion and insulin receptor signaling. On the other hand, insulin was also shown to influence circulating levels of ghrelin. Here, we review the relationship between ghrelin and insulin and we describe the impact of this interaction on the modulation of glucose homeostasis.
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Yang J, Feng X, Zhong S, Wang Y, Liu J. Gastric Bypass Surgery May Improve Beta Cell Apoptosis with Ghrelin Overexpression in Patients with BMI ≥ 32.5 kg/m2. Obes Surg 2013; 24:561-71. [DOI: 10.1007/s11695-013-1135-4] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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Abstract
PURPOSE OF REVIEW Ghrelin is a multifaceted gut hormone that activates its receptor, growth hormone secretagogue receptor (GHS-R). Ghrelin's hallmark functions are its stimulatory effects on growth hormone release, food intake and fat deposition. Ghrelin is famously known as the 'hunger hormone'. However, ample recent literature indicates that the functions of ghrelin go well beyond its role as an orexigenic signal. Here, we have reviewed some of the most recent findings on ghrelin and its signalling in animals and humans. RECENT FINDINGS Ghrelin regulates glucose homeostasis by inhibiting insulin secretion and regulating gluconeogenesis/glycogenolysis. Ghrelin signalling decreases thermogenesis to regulate energy expenditure. Ghrelin improves the survival prognosis of myocardial infarction by reducing sympathetic nerve activity. Ghrelin prevents muscle atrophy by inducing muscle differentiation and fusion. Ghrelin regulates bone formation and metabolism by modulating proliferation and differentiation of osteoblasts. SUMMARY In addition to ghrelin's effects on appetite and adiposity, ghrelin signalling also plays crucial roles in glucose and energy homeostasis, cardioprotection, muscle atrophy and bone metabolism. These multifaceted roles of ghrelin make ghrelin and GHS-R highly attractive targets for drug development. Ghrelin mimetics may be used to treat heart diseases, muscular dystrophy/sarcopenia and osteoporosis; GHS-R antagonists may be used to treat obesity and insulin resistance.
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Affiliation(s)
- Geetali Pradhan
- USDA/ARS Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX, USA
| | - Susan L. Samson
- Division of Diabetes, Endocrinology, and Metabolism, Department of Medicine, Baylor College of Medicine, Houston, TX, USA
| | - Yuxiang Sun
- USDA/ARS Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX, USA
- Huffington Center on Aging, Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX, USA
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Uchida A, Zigman JM, Perelló M. Ghrelin and eating behavior: evidence and insights from genetically-modified mouse models. Front Neurosci 2013; 7:121. [PMID: 23882175 PMCID: PMC3712270 DOI: 10.3389/fnins.2013.00121] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2013] [Accepted: 06/25/2013] [Indexed: 01/08/2023] Open
Abstract
Ghrelin is an octanoylated peptide hormone, produced by endocrine cells of the stomach, which acts in the brain to increase food intake and body weight. Our understanding of the mechanisms underlying ghrelin's effects on eating behaviors has been greatly improved by the generation and study of several genetically manipulated mouse models. These models include mice overexpressing ghrelin and also mice with genetic deletion of ghrelin, the ghrelin receptor [the growth hormone secretagogue receptor (GHSR)] or the enzyme that post-translationally modifies ghrelin [ghrelin O-acyltransferase (GOAT)]. In addition, a GHSR-null mouse model in which GHSR transcription is globally blocked but can be cell-specifically reactivated in a Cre recombinase-mediated fashion has been generated. Here, we summarize findings obtained with these genetically manipulated mice, with the aim to highlight the significance of the ghrelin system in the regulation of both homeostatic and hedonic eating, including that occurring in the setting of chronic psychosocial stress.
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Affiliation(s)
- Aki Uchida
- Divisions of Hypothalamic Research and Endocrinology and Metabolism, Department of Medicine, The University of Texas Southwestern Medical Center Dallas, TX, USA ; Department of Psychiatry, The University of Texas Southwestern Medical Center Dallas, TX, USA
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Shang G, Gao P, Zhao Z, Chen Q, Jiang T, Zhang N, Li H. 3,5-Diiodo-l-thyronine ameliorates diabetic nephropathy in streptozotocin-induced diabetic rats. Biochim Biophys Acta Mol Basis Dis 2013; 1832:674-84. [DOI: 10.1016/j.bbadis.2013.01.023] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2012] [Revised: 01/13/2013] [Accepted: 01/29/2013] [Indexed: 12/26/2022]
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Kirchner H, Heppner KM, Holland J, Kabra D, Tschöp MH, Pfluger PT. Ablation of ghrelin O-acyltransferase does not improve glucose intolerance or body adiposity in mice on a leptin-deficient ob/ob background. PLoS One 2013; 8:e61822. [PMID: 23630616 PMCID: PMC3632576 DOI: 10.1371/journal.pone.0061822] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2012] [Accepted: 03/13/2013] [Indexed: 01/08/2023] Open
Abstract
Type 2 Diabetes is a global health burden and based on current estimates will become an even larger problem in the future. Developing new strategies to prevent and treat diabetes is a scientific challenge of high priority. The stomach hormone ghrelin has been associated with playing a role in the regulation of glucose homeostasis. However, its precise mechanism and impact on whole glucose metabolism remains to be elucidated. This study aims to clarify the role of the two ghrelin isoforms acyl- and desacyl ghrelin in regulating glucose homeostasis. Therefore ghrelin activating enzyme Ghrelin-O-acyltransferase (GOAT) was ablated in leptin-deficient ob/ob mice to study whether specific acyl ghrelin deficiency or desacyl ghrelin abundance modifies glucose tolerance on a massively obese background. As targeted deletion of acyl ghrelin does not improve glucose homeostasis in our GOAT-ob/ob mouse model we conclude that neither acyl ghrelin nor the increased ratio of desacyl/acyl ghrelin is crucial for controlling glucose homeostasis in the here presented model of massive obesity induced by leptin deficiency.
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Affiliation(s)
- Henriette Kirchner
- Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden
| | - Kristy M. Heppner
- Metabolic Diseases Institute, University of Cincinnati, Cincinnati, Ohio, United States of America
| | - Jenna Holland
- Metabolic Diseases Institute, University of Cincinnati, Cincinnati, Ohio, United States of America
| | - Dhiraj Kabra
- Institute for Diabetes and Obesity, Helmholtz Centre Munich, Neuherberg, Germany
| | - Matthias H. Tschöp
- Metabolic Diseases Institute, University of Cincinnati, Cincinnati, Ohio, United States of America
- Institute for Diabetes and Obesity, Helmholtz Centre Munich, Neuherberg, Germany
| | - Paul T. Pfluger
- Metabolic Diseases Institute, University of Cincinnati, Cincinnati, Ohio, United States of America
- Institute for Diabetes and Obesity, Helmholtz Centre Munich, Neuherberg, Germany
- * E-mail:
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