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Manglani K, Anika NN, Patel D, Jhaveri S, Avanthika C, Sudan S, Alimohamed Z, Tiwari K. Correlation of Leptin in Patients With Type 2 Diabetes Mellitus. Cureus 2024; 16:e57667. [PMID: 38707092 PMCID: PMC11070180 DOI: 10.7759/cureus.57667] [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] [Accepted: 04/05/2024] [Indexed: 05/07/2024] Open
Abstract
The exponential increase in diabetes mellitus (DM) poses serious public health concerns. In this review, we focus on the role of leptin in type 2 DM. The peripheral actions of leptin consist of upregulating proinflammatory cytokines which play an important role in the pathogenesis of type 2 DM and insulin resistance. Moreover, leptin is known to inhibit insulin secretion and plays a significant role in insulin resistance in obesity and type 2 DM. A literature search was conducted on Medline, Cochrane, Embase, and Google Scholar for relevant articles published until December 2023. The following search strings and Medical Subject Headings (MeSH terms) were used: "Diabetes Mellitus," "Leptin," "NPY," and "Biomarker." This article aims to discuss the physiology of leptin in type 2 DM, its glucoregulatory actions, its relationship with appetite, the impact that various lifestyle modifications can have on leptin levels, and, finally, explore leptin as a potential target for various treatment strategies.
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Affiliation(s)
- Kajol Manglani
- Internal Medicine, MedStar Washington Hospital Center, Washington, USA
| | | | - Dhriti Patel
- Medicine and Surgery, B.J. Medical College and Civil Hospital, Ahmedabad, IND
| | - Sharan Jhaveri
- Medicine and Surgery, Smt. Nathiba Hargovandas Lakhmichand Municipal Medical College, Gujarat University, Ahmedabad, IND
| | - Chaithanya Avanthika
- Pediatrics, Icahn School of Medicine at Mount Sinai, Elmhurst Hospital Center, New York, USA
- Medicine and Surgery, Karnataka Institute of Medical Sciences, Hubballi, IND
| | - Sourav Sudan
- Internal Medicine, Government Medical College, Rajouri, Rajouri, IND
| | - Zainab Alimohamed
- Division of Research & Academic Affairs, Larkin Health System, South Miami, USA
| | - Kripa Tiwari
- Internal Medicine, Maimonides Medical Center, New York, USA
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2
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Screening of Metabolism-Disrupting Chemicals on Pancreatic α-Cells Using In Vitro Methods. Int J Mol Sci 2022; 24:ijms24010231. [PMID: 36613676 PMCID: PMC9820113 DOI: 10.3390/ijms24010231] [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: 11/15/2022] [Revised: 12/07/2022] [Accepted: 12/20/2022] [Indexed: 12/25/2022] Open
Abstract
Metabolism-disrupting chemicals (MDCs) are endocrine disruptors with obesogenic and/or diabetogenic action. There is mounting evidence linking exposure to MDCs to increased susceptibility to diabetes. Despite the important role of glucagon in glucose homeostasis, there is little information on the effects of MDCs on α-cells. Furthermore, there are no methods to identify and test MDCs with the potential to alter α-cell viability and function. Here, we used the mouse α-cell line αTC1-9 to evaluate the effects of MDCs on cell viability and glucagon secretion. We tested six chemicals at concentrations within human exposure (from 0.1 pM to 1 µM): bisphenol-A (BPA), tributyltin (TBT), perfluorooctanoic acid (PFOA), triphenylphosphate (TPP), triclosan (TCS), and dichlorodiphenyldichloroethylene (DDE). Using two different approaches, MTT assay and DNA-binding dyes, we observed that BPA and TBT decreased α-cell viability via a mechanism that depends on the activation of estrogen receptors and PPARγ, respectively. These two chemicals induced ROS production, but barely altered the expression of endoplasmic reticulum (ER) stress markers. Although PFOA, TPP, TCS, and DDE did not alter cell viability nor induced ROS generation or ER stress, all four compounds negatively affected glucagon secretion. Our findings suggest that αTC1-9 cells seem to be an appropriate model to test chemicals with metabolism-disrupting activity and that the improvement of the test methods proposed herein could be incorporated into protocols for the screening of diabetogenic MDCs.
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El-Kafoury B, Mohamed F, Bahgat N, El Samad AA, Shawky M, Abdel-Hady EA. Failure of subcutaneous lipectomy to combat metabolic dysregulations in ovariectomy-induced obesity in young female rats. Hormones (Athens) 2022; 21:421-436. [PMID: 35486321 PMCID: PMC9464754 DOI: 10.1007/s42000-022-00371-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Accepted: 04/12/2022] [Indexed: 11/28/2022]
Abstract
PURPOSE The deleterious effect of visceral adipose tissue accumulation is well known. However, the recent trend in liposuction is mal-directed toward easily accessible subcutaneous fat for the purpose of body shaping. The aim of the present study is to probe the metabolic effects of subcutaneous abdominal adipose tissue lipectomy in ovariectomized obese rats as well as the role of adipokines in these changes. METHODS The study was conducted on young female rats randomized into two main groups according to the duration of the experiment, namely, 5-week and 10-week. Both groups were subdivided as follows: sham-operated, ovariectomized, and ovariectomized lipectomized rat groups. The rats underwent measurement of body weight (BW) and determination of body mass index (BMI). Fasting blood glucose, lipid profile, liver function, plasma malondialdehyde, leptin, and adiponectin were estimated, and the content of both blood and hepatic tissue of reduced glutathione was assessed. In addition, histological study of the liver, aorta, and perirenal fat of all rat groups was performed. RESULTS Ovariectomy-induced obesity is marked by a significant increase in BW and BMI. Following subcutaneous lipectomy, the rats exhibited significant weight gain accompanied by fasting hyperglycemia, dyslipidemia, deterioration of synthetic function of the liver, and disturbed oxidant/antioxidant status. Histological examination revealed fatty infiltration of aortic and hepatic tissues. CONCLUSION Despite the immediate positive effect of subcutaneous lipectomy for weight loss and/or body shaping, multiple delayed hazards follow the procedure, which should be carefully considered.
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Affiliation(s)
- Bataa El-Kafoury
- Physiology Department, Faculty of Medicine, Ain Shams University, Cairo, Egypt
| | - Fatma Mohamed
- Physiology Department, Faculty of Medicine, Ain Shams University, Cairo, Egypt
| | - Nehal Bahgat
- Physiology Department, Faculty of Medicine, Ain Shams University, Cairo, Egypt
| | - Abeer Abd El Samad
- Histology Department, Faculty of Medicine, Ain Shams University, Cairo, Egypt
| | - Mona Shawky
- Physiology Department, Faculty of Medicine, Ain Shams University, Cairo, Egypt
| | - Enas A Abdel-Hady
- Physiology Department, Faculty of Medicine, Ain Shams University, Cairo, Egypt.
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Yan Z, Fortunato M, Shyr ZA, Clark AL, Fuess M, Nichols CG, Remedi MS. Genetic Reduction of Glucose Metabolism Preserves Functional β-Cell Mass in KATP-Induced Neonatal Diabetes. Diabetes 2022; 71:1233-1245. [PMID: 35294000 PMCID: PMC9163553 DOI: 10.2337/db21-0992] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/04/2021] [Accepted: 03/09/2022] [Indexed: 11/13/2022]
Abstract
β-Cell failure and loss of β-cell mass are key events in diabetes progression. Although insulin hypersecretion in early stages has been implicated in β-cell exhaustion/failure, loss of β-cell mass still occurs in KATP gain-of-function (GOF) mouse models of human neonatal diabetes in the absence of insulin secretion. Thus, we hypothesize that hyperglycemia-induced increased β-cell metabolism is responsible for β-cell failure and that reducing glucose metabolism will prevent loss of β-cell mass. To test this, KATP-GOF mice were crossed with mice carrying β-cell-specific glucokinase haploinsufficiency (GCK+/-), to genetically reduce glucose metabolism. As expected, both KATP-GOF and KATP-GOF/GCK+/- mice showed lack of glucose-stimulated insulin secretion. However, KATP-GOF/GCK+/- mice demonstrated markedly reduced blood glucose, delayed diabetes progression, and improved glucose tolerance compared with KATP-GOF mice. In addition, decreased plasma insulin and content, increased proinsulin, and augmented plasma glucagon observed in KATP-GOF mice were normalized to control levels in KATP-GOF/GCK+/- mice. Strikingly, KATP-GOF/GCK+/- mice demonstrated preserved β-cell mass and identity compared with the marked decrease in β-cell identity and increased dedifferentiation observed in KATP-GOF mice. Moreover KATP-GOF/GCK+/- mice demonstrated restoration of body weight and liver and brown/white adipose tissue mass and function and normalization of physical activity and metabolic efficiency compared with KATP-GOF mice. These results demonstrate that decreasing β-cell glucose signaling can prevent glucotoxicity-induced loss of insulin content and β-cell failure independently of compensatory insulin hypersecretion and β-cell exhaustion.
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Affiliation(s)
- Zihan Yan
- Division of Endocrinology, Metabolism and Lipid Research, Department of Medicine, Washington University School of Medicine, St. Louis, MO
| | - Manuela Fortunato
- Division of Endocrinology, Metabolism and Lipid Research, Department of Medicine, Washington University School of Medicine, St. Louis, MO
| | - Zeenat A. Shyr
- Division of Endocrinology, Metabolism and Lipid Research, Department of Medicine, Washington University School of Medicine, St. Louis, MO
| | - Amy L. Clark
- Department of Pediatrics, Washington University School of Medicine, St. Louis, MO
| | - Matt Fuess
- Division of Endocrinology, Metabolism and Lipid Research, Department of Medicine, Washington University School of Medicine, St. Louis, MO
| | - Colin G. Nichols
- Deparment of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO
- Center for the Investigation of Membrane Excitability Diseases, Washington University School of Medicine, St. Louis, MO
| | - Maria S. Remedi
- Division of Endocrinology, Metabolism and Lipid Research, Department of Medicine, Washington University School of Medicine, St. Louis, MO
- Deparment of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO
- Center for the Investigation of Membrane Excitability Diseases, Washington University School of Medicine, St. Louis, MO
- Corresponding author: Maria S. Remedi,
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Romero-Campos HE, Dupont G, Gonzalez-Velez V. On the Electrophysiological Component of Pancreatic Alpha-Cell Models. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2021; 2021:4408-4411. [PMID: 34892197 DOI: 10.1109/embc46164.2021.9630329] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Glucagon, the main hormone responsible for increasing blood glucose levels, is secreted by pancreatic alphacells in a Ca2+ dependent process associated to membrane potential oscillations developed by the dynamic operation of K+, Na+ and Ca2+ channels. The mechanisms behind membrane potential and Ca2+ oscillations in alpha-cells are still under debate, and some new research works have used alpha-cell models to describe electrical activity. In this paper we studied the dynamics of electrical activity of three alpha-cell models using the Lead Potential Analysis method and Bifurcation Diagrams. Our aim is to highlight the differences in their dynamic behavior and therefore, in their response to glucose. Both issues are relevant to understand the stimulus-secretion coupling in alpha-cells and then, the mechanisms behind their dysregulation in Type 2 Diabetes.Clinical Relevance - A reliable description of the electrophysiological mechanisms in pancreatic alpha-cells is key to understand and treat the dysregulation of these cells in patients with Type 2 Diabetes.
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Pereira S, Cline DL, Glavas MM, Covey SD, Kieffer TJ. Tissue-Specific Effects of Leptin on Glucose and Lipid Metabolism. Endocr Rev 2021; 42:1-28. [PMID: 33150398 PMCID: PMC7846142 DOI: 10.1210/endrev/bnaa027] [Citation(s) in RCA: 62] [Impact Index Per Article: 20.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Indexed: 12/18/2022]
Abstract
The discovery of leptin was intrinsically associated with its ability to regulate body weight. However, the effects of leptin are more far-reaching and include profound glucose-lowering and anti-lipogenic effects, independent of leptin's regulation of body weight. Regulation of glucose metabolism by leptin is mediated both centrally and via peripheral tissues and is influenced by the activation status of insulin signaling pathways. Ectopic fat accumulation is diminished by both central and peripheral leptin, an effect that is beneficial in obesity-associated disorders. The magnitude of leptin action depends upon the tissue, sex, and context being examined. Peripheral tissues that are of particular relevance include the endocrine pancreas, liver, skeletal muscle, adipose tissues, immune cells, and the cardiovascular system. As a result of its potent metabolic activity, leptin is used to control hyperglycemia in patients with lipodystrophy and is being explored as an adjunct to insulin in patients with type 1 diabetes. To fully understand the role of leptin in physiology and to maximize its therapeutic potential, the mechanisms of leptin action in these tissues needs to be further explored.
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Affiliation(s)
- Sandra Pereira
- Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, Canada
| | - Daemon L Cline
- Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, Canada
| | - Maria M Glavas
- Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, Canada
| | - Scott D Covey
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, Canada
| | - Timothy J Kieffer
- Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, Canada.,Department of Surgery, University of British Columbia, Vancouver, Canada.,School of Biomedical Engineering, University of British Columbia, Vancouver, Canada
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González-Vélez V, Piron A, Dupont G. Calcium Oscillations in Pancreatic α-cells Rely on Noise and ATP-Driven Changes in Membrane Electrical Activity. Front Physiol 2020; 11:602844. [PMID: 33281631 PMCID: PMC7705205 DOI: 10.3389/fphys.2020.602844] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2020] [Accepted: 10/28/2020] [Indexed: 11/13/2022] Open
Abstract
In pancreatic α-cells, intracellular Ca2+ ([Ca2+]i) acts as a trigger for secretion of glucagon, a hormone that plays a key role in blood glucose homeostasis. Intracellular Ca2+ dynamics in these cells are governed by the electrical activity of voltage-gated ion channels, among which ATP-sensitive K+ (KATP) channels play a crucial role. In the majority of α-cells, the global Ca2+ response to lowering external glucose occurs in the form of oscillations that are much slower than electrical activity. These Ca2+ oscillations are highly variable as far as inter-spike intervals, shapes and amplitudes are concerned. Such observations suggest that Ca2+ dynamics in α-cells are much influenced by noise. Actually, each Ca2+ increase corresponds to multiple cycles of opening/closing of voltage gated Ca2+ channels that abruptly become silent, before the occurrence of another burst of activity a few tens of seconds later. The mechanism responsible for this intermittent activity is currently unknown. In this work, we used computational modeling to investigate the mechanism of cytosolic Ca2+ oscillations in α-cells. Given the limited population of KATP channels in this cell type, we hypothesized that the stochastic activity of these channels could play a key role in the sporadic character of the action potentials. To test this assumption, we extended a previously proposed model of the α-cells electrical activity (Diderichsen and Göpel, 2006) to take Ca2+ dynamics into account. Including molecular noise on the basis of a Langevin type description as well as realistic dynamics of opening and closing of KATP channels, we found that stochasticity at the level of the activity of this channel is on its own not able to produce Ca2+ oscillations with a time scale of a few tens of seconds. However, when taking into account the intimate relation between Ca2+ and ATP changes together with the intrinsic noise at the level of the KATP channels, simulations displayed Ca2+ oscillations that are compatible with experimental observations. We analyzed the detailed mechanism and used computational simulations to identify the factors that can affect Ca2+ oscillations in α-cells.
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Affiliation(s)
- Virginia González-Vélez
- Department Basic Sciences, Universidad Autónoma Metropolitana-Azcapotzalco, CDMX, Mèxico, Mexico
| | - Anthony Piron
- ULB Center for Diabetes Research, Faculté de Médecine, Université libre de Bruxelles (ULB), Brussels, Belgium.,Interuniversity Institute of Bioinformatics (IB2), Brussels, Belgium
| | - Geneviève Dupont
- Interuniversity Institute of Bioinformatics (IB2), Brussels, Belgium.,Unit of Theoretical Chronobiology, Faculté des Sciences, Université libre de Bruxelles (ULB), Brussels, Belgium
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He S, Le NA, Ramirez-Zea M, Martorell R, Narayan KMV, Stein AD. Leptin partially mediates the association between early-life nutritional supplementation and long-term glycemic status among women in a Guatemalan longitudinal cohort. Am J Clin Nutr 2020; 111:804-813. [PMID: 32069352 PMCID: PMC7138657 DOI: 10.1093/ajcn/nqaa001] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Accepted: 01/01/2020] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND Early-life exposure to improved nutrition is associated with decreased risk of diabetes but increased risk of obesity. Leptin positively correlates with adiposity and has glucose-lowering effects, thus it may mediate the association of early-life nutrition and long-term glycemic status. OBJECTIVES We aimed to investigate the role of leptin in the differential association between early-life nutrition and the risks of obesity and diabetes. METHODS We analyzed data from a Guatemalan cohort who were randomly assigned at the village level to receive nutritional supplements as children. We conducted mediation analysis to examine the role of leptin in the associations of early-life nutrition and adult cardiometabolic outcomes. RESULTS Among 1112 study participants aged (mean ± SD) 44.1 ± 4.2 y, 60.6% were women. Cardiometabolic conditions were common: 40.2% of women and 19.4% of men were obese, and 53.1% of women and 41.0% of men were hyperglycemic or diabetic. Median (IQR) leptin concentration was 15.2 ng/mL (10.2-17.3 ng/mL) in women and 2.7 ng/mL (1.3-5.3 ng/mL) in men. Leptin was positively correlated with BMI (Spearman's ρ was 0.6 in women, 0.7 in men). Women exposed to improved nutrition in early life had 2.8-ng/mL (95% CI: 0.3, 5.3 ng/mL) higher leptin and tended to have lower fasting glucose (-0.8 mmol/L; -1.8, 0.2 mmol/L, nonsignificant) than unexposed women. There were no significant differences in leptin (-0.7 ng/mL; -2.1, 0.8 ng/mL) or fasting glucose (0.2 mmol/L; -0.5, 0.9 mmol/L) in men exposed to improved nutrition in early life compared with unexposed men. Leptin mediated 34.9% of the pathway between early-life nutrition and fasting glucose in women. The mediation in women was driven by improved pancreatic β-cell function. We did not observe the mediation effect in men. CONCLUSIONS Leptin mediated the glucose-lowering effect of early-life nutrition in women but not in men.
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Affiliation(s)
- Siran He
- Nutrition and Health Sciences Program, Laney Graduate School, Emory University, Atlanta, GA, USA
| | - Ngoc-Anh Le
- Biomarker Core Laboratory, Foundation for Atlanta Veterans Education and Research, Atlanta Veterans Affairs Medical Center, Atlanta, GA, USA
| | - Manuel Ramirez-Zea
- INCAP Research Center for the Prevention of Chronic Diseases, Institute of Nutrition of Central America and Panama, Guatemala City, Guatemala
| | | | | | - Aryeh D Stein
- Rollins School of Public Health, Emory University, Atlanta, GA, USA,Address correspondence to ADS (e-mail: )
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9
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Zouhar P, Rakipovski G, Bokhari MH, Busby O, Paulsson JF, Conde-Frieboes KW, Fels JJ, Raun K, Andersen B, Cannon B, Nedergaard J. UCP1-independent glucose-lowering effect of leptin in type 1 diabetes: only in conditions of hypoleptinemia. Am J Physiol Endocrinol Metab 2020; 318:E72-E86. [PMID: 31743040 PMCID: PMC6985793 DOI: 10.1152/ajpendo.00253.2019] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The possibility to use leptin therapeutically for lowering glucose levels in patients with type 1 diabetes has attracted interest. However, earlier animal models of type 1 diabetes are severely catabolic with very low endogenous leptin levels, unlike most patients with diabetes. Here, we aim to test glucose-lowering effects of leptin in novel, more human-like murine models. We examined the glucose-lowering potential of leptin in diabetic models of two types: streptozotocin-treated mice and mice treated with the insulin receptor antagonist S961. To prevent hypoleptinemia, we used combinations of thermoneutral temperature and high-fat feeding. Leptin fully normalized hyperglycemia in standard chow-fed streptozotocin-treated diabetic mice. However, more humanized physiological conditions (high-fat diets or thermoneutral temperatures) that increased adiposity - and thus also leptin levels - in the diabetic mice abrogated the effects of leptin, i.e., the mice developed leptin resistance also in this respect. The glucose-lowering effect of leptin was not dependent on the presence of the uncoupling protein-1 and was not associated with alterations in plasma insulin, insulin-like growth factor 1, food intake or corticosterone but fully correlated with decreased plasma glucagon levels and gluconeogenesis. An important implication of these observations is that the therapeutic potential of leptin as an additional treatment in patients with type 1 diabetes is probably limited. This is because such patients are treated with insulin and do not display low leptin levels. Thus, the potential for a glucose-lowering effect of leptin would already have been attained with standard insulin therapy, and further effects on blood glucose level through additional leptin cannot be anticipated.
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Affiliation(s)
- Petr Zouhar
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden
- Department of Adipose Tissue Biology, Institute of Physiology CAS, Prague, the Czech Republic
| | | | - Muhammad Hamza Bokhari
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden
| | - Oliver Busby
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden
| | | | | | | | - Kirsten Raun
- Global Drug Discovery, Novo Nordisk A/S, Måløv, Denmark
| | | | - Barbara Cannon
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden
| | - Jan Nedergaard
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden
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Salazar J, Chávez-Castillo M, Rojas J, Ortega A, Nava M, Pérez J, Rojas M, Espinoza C, Chacin M, Herazo Y, Angarita L, Rojas DM, D'Marco L, Bermudez V. Is "Leptin Resistance" Another Key Resistance to Manage Type 2 Diabetes? Curr Diabetes Rev 2020; 16:733-749. [PMID: 31886750 DOI: 10.2174/1573399816666191230111838] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/08/2019] [Revised: 11/08/2019] [Accepted: 12/12/2019] [Indexed: 02/06/2023]
Abstract
Although novel pharmacological options for the treatment of type 2 diabetes mellitus (DM2) have been observed to modulate the functionality of several key organs in glucose homeostasis, successful regulation of insulin resistance (IR), body weight management, and pharmacological treatment of obesity remain notable problems in endocrinology. Leptin may be a pivotal player in this scenario, as an adipokine which centrally regulates appetite and energy balance. In obesity, excessive caloric intake promotes a low-grade inflammatory response, which leads to dysregulations in lipid storage and adipokine secretion. In turn, these entail alterations in leptin sensitivity, leptin transport across the blood-brain barrier and defects in post-receptor signaling. Furthermore, hypothalamic inflammation and endoplasmic reticulum stress may increase the expression of molecules which may disrupt leptin signaling. Abundant evidence has linked obesity and leptin resistance, which may precede or occur simultaneously to IR and DM2. Thus, leptin sensitivity may be a potential early therapeutic target that demands further preclinical and clinical research. Modulators of insulin sensitivity have been tested in animal models and small clinical trials with promising results, especially in combination with agents such as amylin and GLP-1 analogs, in particular, due to their central activity in the hypothalamus.
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Affiliation(s)
- Juan Salazar
- Endocrine and Metabolic Diseases Research Center, School of Medicine, The University of Zulia, Maracaibo, Venezuela
| | - Mervin Chávez-Castillo
- Endocrine and Metabolic Diseases Research Center, School of Medicine, The University of Zulia, Maracaibo, Venezuela
| | - Joselyn Rojas
- Division of Pulmonary and Critical Care Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, United States
| | - Angel Ortega
- Endocrine and Metabolic Diseases Research Center, School of Medicine, The University of Zulia, Maracaibo, Venezuela
| | - Manuel Nava
- Endocrine and Metabolic Diseases Research Center, School of Medicine, The University of Zulia, Maracaibo, Venezuela
| | - José Pérez
- Endocrine and Metabolic Diseases Research Center, School of Medicine, The University of Zulia, Maracaibo, Venezuela
| | - Milagros Rojas
- Endocrine and Metabolic Diseases Research Center, School of Medicine, The University of Zulia, Maracaibo, Venezuela
| | | | - Maricarmen Chacin
- Universidad Simon Bolivar, Facultad de Ciencias de la Salud, Barranquilla, Colombia
| | - Yaneth Herazo
- Universidad Simon Bolivar, Facultad de Ciencias de la Salud, Barranquilla, Colombia
| | - Lissé Angarita
- Escuela de Nutricion y Dietetica, Facultad de Medicina, Universidad Andres Bello, Sede Concepcion, Chile
| | - Diana Marcela Rojas
- Escuela de Nutricion y Dietética, Facultad de Medicina, Universidad Andres Bello, Santiago, Chile
| | - Luis D'Marco
- Hospital Clinico de Valencia, INCLIVA, Servicio de Nefrologia, Valencia, Spain
| | - Valmore Bermudez
- Universidad Simon Bolivar, Facultad de Ciencias de la Salud, Barranquilla, Colombia
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11
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Becerril S, Rodríguez A, Catalán V, Ramírez B, Unamuno X, Portincasa P, Gómez-Ambrosi J, Frühbeck G. Functional Relationship between Leptin and Nitric Oxide in Metabolism. Nutrients 2019; 11:nu11092129. [PMID: 31500090 PMCID: PMC6769456 DOI: 10.3390/nu11092129] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2019] [Revised: 08/23/2019] [Accepted: 09/02/2019] [Indexed: 12/28/2022] Open
Abstract
Leptin, the product of the ob gene, was originally described as a satiety factor, playing a crucial role in the control of body weight. Nevertheless, the wide distribution of leptin receptors in peripheral tissues supports that leptin exerts pleiotropic biological effects, consisting of the modulation of numerous processes including thermogenesis, reproduction, angiogenesis, hematopoiesis, osteogenesis, neuroendocrine, and immune functions as well as arterial pressure control. Nitric oxide (NO) is a free radical synthesized from L-arginine by the action of the NO synthase (NOS) enzyme. Three NOS isoforms have been identified: the neuronal NOS (nNOS) and endothelial NOS (eNOS) constitutive isoforms, and the inducible NOS (iNOS). NO mediates multiple biological effects in a variety of physiological systems such as energy balance, blood pressure, reproduction, immune response, or reproduction. Leptin and NO on their own participate in multiple common physiological processes, with a functional relationship between both factors having been identified. The present review describes the functional relationship between leptin and NO in different physiological processes.
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Affiliation(s)
- Sara Becerril
- Metabolic Research Laboratory, Clínica Universidad de Navarra, 31008 Pamplona, Spain.
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBEROBN), Instituto de Salud Carlos III, 31008 Pamplona, Spain.
- Obesity and Adipobiology Group, Instituto de Investigación Sanitaria de Navarra (IdiSNA), 31008 Pamplona, Spain.
| | - Amaia Rodríguez
- Metabolic Research Laboratory, Clínica Universidad de Navarra, 31008 Pamplona, Spain.
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBEROBN), Instituto de Salud Carlos III, 31008 Pamplona, Spain.
- Obesity and Adipobiology Group, Instituto de Investigación Sanitaria de Navarra (IdiSNA), 31008 Pamplona, Spain.
| | - Victoria Catalán
- Metabolic Research Laboratory, Clínica Universidad de Navarra, 31008 Pamplona, Spain.
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBEROBN), Instituto de Salud Carlos III, 31008 Pamplona, Spain.
- Obesity and Adipobiology Group, Instituto de Investigación Sanitaria de Navarra (IdiSNA), 31008 Pamplona, Spain.
| | - Beatriz Ramírez
- Metabolic Research Laboratory, Clínica Universidad de Navarra, 31008 Pamplona, Spain.
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBEROBN), Instituto de Salud Carlos III, 31008 Pamplona, Spain.
- Obesity and Adipobiology Group, Instituto de Investigación Sanitaria de Navarra (IdiSNA), 31008 Pamplona, Spain.
| | - Xabier Unamuno
- Metabolic Research Laboratory, Clínica Universidad de Navarra, 31008 Pamplona, Spain.
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBEROBN), Instituto de Salud Carlos III, 31008 Pamplona, Spain.
- Medical Engineering Laboratory, University of Navarra, 31008 Pamplona, Spain.
| | - Piero Portincasa
- Clinica Medica "A. Murri", Department of Biomedical Sciences and Human Oncology, University of Bari Medical School, Policlinico Hospital, 70124 Bari, Italy.
| | - Javier Gómez-Ambrosi
- Metabolic Research Laboratory, Clínica Universidad de Navarra, 31008 Pamplona, Spain.
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBEROBN), Instituto de Salud Carlos III, 31008 Pamplona, Spain.
- Obesity and Adipobiology Group, Instituto de Investigación Sanitaria de Navarra (IdiSNA), 31008 Pamplona, Spain.
| | - Gema Frühbeck
- Metabolic Research Laboratory, Clínica Universidad de Navarra, 31008 Pamplona, Spain.
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBEROBN), Instituto de Salud Carlos III, 31008 Pamplona, Spain.
- Obesity and Adipobiology Group, Instituto de Investigación Sanitaria de Navarra (IdiSNA), 31008 Pamplona, Spain.
- Department of Endocrinology & Nutrition, Clínica Universidad de Navarra, 31008 Pamplona, Spain.
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12
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D'souza AM, Neumann UH, Glavas MM, Kieffer TJ. The glucoregulatory actions of leptin. Mol Metab 2017; 6:1052-1065. [PMID: 28951828 PMCID: PMC5605734 DOI: 10.1016/j.molmet.2017.04.011] [Citation(s) in RCA: 122] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/06/2017] [Revised: 04/18/2017] [Accepted: 04/24/2017] [Indexed: 12/28/2022] Open
Abstract
Background The hormone leptin is an important regulator of metabolic homeostasis, able to inhibit food intake and increase energy expenditure. Leptin can also independently lower blood glucose levels, particularly in hyperglycemic models of leptin or insulin deficiency. Despite significant efforts and relevance to diabetes, the mechanisms by which leptin acts to regulate blood glucose levels are not fully understood. Scope of review Here we assess literature relevant to the glucose lowering effects of leptin. Leptin receptors are widely expressed in multiple cell types, and we describe both peripheral and central effects of leptin that may be involved in lowering blood glucose. In addition, we summarize the potential clinical application of leptin in regulating glucose homeostasis. Major conclusions Leptin exerts a plethora of metabolic effects on various tissues including suppressing production of glucagon and corticosterone, increasing glucose uptake, and inhibiting hepatic glucose output. A more in-depth understanding of the mechanisms of the glucose-lowering actions of leptin may reveal new strategies to treat metabolic disorders.
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Affiliation(s)
- Anna M D'souza
- Department of Cellular and Physiological Sciences, University of British Columbia, 2350 Health Sciences Mall, Vancouver, British Columbia V6T 1Z3, Canada
| | - Ursula H Neumann
- Department of Cellular and Physiological Sciences, University of British Columbia, 2350 Health Sciences Mall, Vancouver, British Columbia V6T 1Z3, Canada
| | - Maria M Glavas
- Department of Cellular and Physiological Sciences, University of British Columbia, 2350 Health Sciences Mall, Vancouver, British Columbia V6T 1Z3, Canada
| | - Timothy J Kieffer
- Department of Cellular and Physiological Sciences, University of British Columbia, 2350 Health Sciences Mall, Vancouver, British Columbia V6T 1Z3, Canada.,Department of Surgery, University of British Columbia, 2350 Health Sciences Mall, Vancouver, British Columbia V6T 1Z3, Canada
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13
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Glucagon increase after chronic AT1 blockade is more likely related to an indirect leptin-dependent than to a pancreatic α-cell-dependent mechanism. Naunyn Schmiedebergs Arch Pharmacol 2017; 390:505-518. [DOI: 10.1007/s00210-017-1346-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2016] [Accepted: 01/20/2017] [Indexed: 01/28/2023]
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14
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Segerstolpe Å, Palasantza A, Eliasson P, Andersson EM, Andréasson AC, Sun X, Picelli S, Sabirsh A, Clausen M, Bjursell MK, Smith DM, Kasper M, Ämmälä C, Sandberg R. Single-Cell Transcriptome Profiling of Human Pancreatic Islets in Health and Type 2 Diabetes. Cell Metab 2016; 24:593-607. [PMID: 27667667 PMCID: PMC5069352 DOI: 10.1016/j.cmet.2016.08.020] [Citation(s) in RCA: 961] [Impact Index Per Article: 120.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/06/2016] [Revised: 06/13/2016] [Accepted: 08/26/2016] [Indexed: 12/25/2022]
Abstract
Hormone-secreting cells within pancreatic islets of Langerhans play important roles in metabolic homeostasis and disease. However, their transcriptional characterization is still incomplete. Here, we sequenced the transcriptomes of thousands of human islet cells from healthy and type 2 diabetic donors. We could define specific genetic programs for each individual endocrine and exocrine cell type, even for rare δ, γ, ε, and stellate cells, and revealed subpopulations of α, β, and acinar cells. Intriguingly, δ cells expressed several important receptors, indicating an unrecognized importance of these cells in integrating paracrine and systemic metabolic signals. Genes previously associated with obesity or diabetes were found to correlate with BMI. Finally, comparing healthy and T2D transcriptomes in a cell-type resolved manner uncovered candidates for future functional studies. Altogether, our analyses demonstrate the utility of the generated single-cell gene expression resource.
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Affiliation(s)
- Åsa Segerstolpe
- Department of Cell and Molecular Biology (CMB), Karolinska Institutet, 171 77 Stockholm, Sweden; Integrated Cardio Metabolic Center (ICMC), Karolinska Institutet, 141 57 Huddinge, Sweden
| | - Athanasia Palasantza
- Department of Cell and Molecular Biology (CMB), Karolinska Institutet, 171 77 Stockholm, Sweden
| | - Pernilla Eliasson
- Cardiovascular and Metabolic Diseases (CVMD), Innovative Medicines and Early Development Biotech Unit (iMed), AstraZeneca, 431 83 Mölndal, Sweden
| | - Eva-Marie Andersson
- Cardiovascular and Metabolic Diseases (CVMD), Innovative Medicines and Early Development Biotech Unit (iMed), AstraZeneca, 431 83 Mölndal, Sweden
| | - Anne-Christine Andréasson
- Cardiovascular and Metabolic Diseases (CVMD), Innovative Medicines and Early Development Biotech Unit (iMed), AstraZeneca, 431 83 Mölndal, Sweden
| | - Xiaoyan Sun
- Department of Biosciences and Nutrition and Center for Innovative Medicine, Novum, Karolinska Institutet, 141 83 Huddinge, Sweden
| | - Simone Picelli
- Ludwig Institute for Cancer Research, 171 77 Stockholm, Sweden
| | - Alan Sabirsh
- Cardiovascular and Metabolic Diseases (CVMD), Innovative Medicines and Early Development Biotech Unit (iMed), AstraZeneca, 431 83 Mölndal, Sweden
| | - Maryam Clausen
- Discovery Sciences, Innovative Medicines and Early Development Biotech Unit (iMed), AstraZeneca, 431 83 Mölndal, Sweden
| | | | - David M Smith
- Discovery Sciences, Innovative Medicines and Early Development Biotech Unit (iMed), AstraZeneca, Cambridge Science Park, Milton Road, Cambridge CB4 0WG, UK
| | - Maria Kasper
- Department of Biosciences and Nutrition and Center for Innovative Medicine, Novum, Karolinska Institutet, 141 83 Huddinge, Sweden
| | - Carina Ämmälä
- Cardiovascular and Metabolic Diseases (CVMD), Innovative Medicines and Early Development Biotech Unit (iMed), AstraZeneca, 431 83 Mölndal, Sweden
| | - Rickard Sandberg
- Department of Cell and Molecular Biology (CMB), Karolinska Institutet, 171 77 Stockholm, Sweden; Integrated Cardio Metabolic Center (ICMC), Karolinska Institutet, 141 57 Huddinge, Sweden; Ludwig Institute for Cancer Research, 171 77 Stockholm, Sweden.
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15
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Denroche HC, Glavas MM, Tudurí E, Karunakaran S, Quong WL, Philippe M, Britton HM, Clee SM, Kieffer TJ. Disrupted Leptin Signaling in the Lateral Hypothalamus and Ventral Premammillary Nucleus Alters Insulin and Glucagon Secretion and Protects Against Diet-Induced Obesity. Endocrinology 2016; 157:2671-85. [PMID: 27183315 DOI: 10.1210/en.2015-1998] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Leptin signaling in the central nervous system, and particularly the arcuate hypothalamic nucleus, is important for regulating energy and glucose homeostasis. However, the roles of extra-arcuate leptin responsive neurons are less defined. In the current study, we generated mice with widespread inactivation of the long leptin receptor isoform in the central nervous system via Synapsin promoter-driven Cre (Lepr(flox/flox) Syn-cre mice). Within the hypothalamus, leptin signaling was disrupted in the lateral hypothalamic area (LHA) and ventral premammillary nucleus (PMV) but remained intact in the arcuate hypothalamic nucleus and ventromedial hypothalamic nucleus, dorsomedial hypothalamic nucleus, and nucleus of the tractus solitarius. To investigate the role of LHA/PMV neuronal leptin signaling, we examined glucose and energy homeostasis in Lepr(flox/flox) Syn-cre mice and Lepr(flox/flox) littermates under basal and diet-induced obese conditions and tested the role of LHA/PMV neurons in leptin-mediated glucose lowering in streptozotocin-induced diabetes. Lepr(flox/flox) Syn-cre mice did not have altered body weight or blood glucose levels but were hyperinsulinemic and had enhanced glucagon secretion in response to experimental hypoglycemia. Surprisingly, when placed on a high-fat diet, Lepr(flox/flox) Syn-cre mice were protected from weight gain, glucose intolerance, and diet-induced hyperinsulinemia. Peripheral leptin administration lowered blood glucose in streptozotocin-induced diabetic Lepr(flox/flox) Syn-cre mice as effectively as in Lepr(flox/flox) littermate controls. Collectively these findings suggest that leptin signaling in LHA/PMV neurons is not critical for regulating glucose levels but has an indispensable role in the regulation of insulin and glucagon levels and, may promote the development of diet-induced hyperinsulinemia and weight gain.
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Affiliation(s)
- Heather C Denroche
- Laboratory of Molecular and Cellular Medicine (H.C.D., M.M.G., E.T., W.L.Q., M.P., H.M.B., T.J.K.) and Laboratory of the Genetics of Obesity and Diabetes (S.K., S.M.C.), Department of Cellular and Physiological Sciences, Life Sciences Institute, and Department of Surgery (T.J.K.), University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z3
| | - Maria M Glavas
- Laboratory of Molecular and Cellular Medicine (H.C.D., M.M.G., E.T., W.L.Q., M.P., H.M.B., T.J.K.) and Laboratory of the Genetics of Obesity and Diabetes (S.K., S.M.C.), Department of Cellular and Physiological Sciences, Life Sciences Institute, and Department of Surgery (T.J.K.), University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z3
| | - Eva Tudurí
- Laboratory of Molecular and Cellular Medicine (H.C.D., M.M.G., E.T., W.L.Q., M.P., H.M.B., T.J.K.) and Laboratory of the Genetics of Obesity and Diabetes (S.K., S.M.C.), Department of Cellular and Physiological Sciences, Life Sciences Institute, and Department of Surgery (T.J.K.), University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z3
| | - Subashini Karunakaran
- Laboratory of Molecular and Cellular Medicine (H.C.D., M.M.G., E.T., W.L.Q., M.P., H.M.B., T.J.K.) and Laboratory of the Genetics of Obesity and Diabetes (S.K., S.M.C.), Department of Cellular and Physiological Sciences, Life Sciences Institute, and Department of Surgery (T.J.K.), University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z3
| | - Whitney L Quong
- Laboratory of Molecular and Cellular Medicine (H.C.D., M.M.G., E.T., W.L.Q., M.P., H.M.B., T.J.K.) and Laboratory of the Genetics of Obesity and Diabetes (S.K., S.M.C.), Department of Cellular and Physiological Sciences, Life Sciences Institute, and Department of Surgery (T.J.K.), University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z3
| | - Marion Philippe
- Laboratory of Molecular and Cellular Medicine (H.C.D., M.M.G., E.T., W.L.Q., M.P., H.M.B., T.J.K.) and Laboratory of the Genetics of Obesity and Diabetes (S.K., S.M.C.), Department of Cellular and Physiological Sciences, Life Sciences Institute, and Department of Surgery (T.J.K.), University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z3
| | - Heidi M Britton
- Laboratory of Molecular and Cellular Medicine (H.C.D., M.M.G., E.T., W.L.Q., M.P., H.M.B., T.J.K.) and Laboratory of the Genetics of Obesity and Diabetes (S.K., S.M.C.), Department of Cellular and Physiological Sciences, Life Sciences Institute, and Department of Surgery (T.J.K.), University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z3
| | - Susanne M Clee
- Laboratory of Molecular and Cellular Medicine (H.C.D., M.M.G., E.T., W.L.Q., M.P., H.M.B., T.J.K.) and Laboratory of the Genetics of Obesity and Diabetes (S.K., S.M.C.), Department of Cellular and Physiological Sciences, Life Sciences Institute, and Department of Surgery (T.J.K.), University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z3
| | - Timothy J Kieffer
- Laboratory of Molecular and Cellular Medicine (H.C.D., M.M.G., E.T., W.L.Q., M.P., H.M.B., T.J.K.) and Laboratory of the Genetics of Obesity and Diabetes (S.K., S.M.C.), Department of Cellular and Physiological Sciences, Life Sciences Institute, and Department of Surgery (T.J.K.), University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z3
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16
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Denroche HC, Kwon MM, Glavas MM, Tudurí E, Philippe M, Quong WL, Kieffer TJ. The role of autonomic efferents and uncoupling protein 1 in the glucose-lowering effect of leptin therapy. Mol Metab 2016; 5:716-724. [PMID: 27656409 PMCID: PMC5021671 DOI: 10.1016/j.molmet.2016.06.009] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Accepted: 06/19/2016] [Indexed: 01/06/2023] Open
Abstract
Objective Leptin reverses hyperglycemia in rodent models of type 1 diabetes (T1D). Direct application of leptin to the brain can lower blood glucose in diabetic rodents, and can activate autonomic efferents and non-shivering thermogenesis in brown adipose tissue (BAT). We investigated whether leptin reverses hyperglycemia through a mechanism that requires autonomic innervation, or uncoupling protein 1 (UCP1)-mediated thermogenesis. Methods To examine the role of parasympathetic and sympathetic efferents in the glucose-lowering action of leptin, mice with a subdiaphragmatic vagotomy or 6-hydroxydopamine induced chemical sympathectomy were injected with streptozotocin (STZ) to induce hyperglycemia, and subsequently leptin treated. To test whether the glucose-lowering action of leptin requires activation of UCP1-mediated thermogenesis in BAT, we administered leptin in STZ-diabetic Ucp1 knockout (Ucp1−/−) mice and wildtype controls. Results Leptin ameliorated STZ-induced hyperglycemia in both intact and vagotomised mice. Similarly, mice with a partial chemical sympathectomy did not have an attenuated response to leptin-mediated glucose lowering relative to sham controls, and showed intact leptin-induced Ucp1 expression in BAT. Although leptin activated BAT thermogenesis in STZ-diabetic mice, the anti-diabetic effect of leptin was not blunted in Ucp1−/− mice. Conclusions These results suggest that leptin lowers blood glucose in insulin-deficient diabetes through a manner that does not require parasympathetic or sympathetic innervation, and thus imply that leptin lowers blood glucose through an alternative CNS-mediated mechanism or redundant target tissues. Furthermore, we conclude that the glucose lowering action of leptin is independent of UCP1-dependent thermogenesis. Leptin does not require vagal innervation to reverse hyperglycemia. Leptin therapy reverses hyperglycemia in mice with a partial chemical sympathectomy. Leptin reverses hyperglycemia independent of uncoupling protein 1.
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Key Words
- 6OHDA, 6-hydroxydopamine
- ANS, autonomic nervous system
- BAT, brown adipose tissue
- Brown adipose tissue
- CCK, cholecystokinin
- CNS, central nervous system
- Glucose
- STZ, streptozotocin
- Streptozotocin
- Sympathectomy
- T1D, type 1 diabetes
- TH, tyrosine hydroxylase
- Type 1 diabetes
- UCP1, uncoupling protein 1
- Vagotomy
- iBAT, interscapular BAT
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Affiliation(s)
- Heather C Denroche
- Laboratory of Molecular and Cellular Medicine, Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Michelle M Kwon
- Laboratory of Molecular and Cellular Medicine, Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Maria M Glavas
- Laboratory of Molecular and Cellular Medicine, Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Eva Tudurí
- Laboratory of Molecular and Cellular Medicine, Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Marion Philippe
- Laboratory of Molecular and Cellular Medicine, Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Whitney L Quong
- Laboratory of Molecular and Cellular Medicine, Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Timothy J Kieffer
- Laboratory of Molecular and Cellular Medicine, Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada; Department of Surgery, University of British Columbia, Vancouver, British Columbia, Canada.
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17
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Stern JH, Rutkowski JM, Scherer PE. Adiponectin, Leptin, and Fatty Acids in the Maintenance of Metabolic Homeostasis through Adipose Tissue Crosstalk. Cell Metab 2016; 23:770-84. [PMID: 27166942 PMCID: PMC4864949 DOI: 10.1016/j.cmet.2016.04.011] [Citation(s) in RCA: 677] [Impact Index Per Article: 84.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Metabolism research has made tremendous progress over the last several decades in establishing the adipocyte as a central rheostat in the regulation of systemic nutrient and energy homeostasis. Operating at multiple levels of control, the adipocyte communicates with organ systems to adjust gene expression, glucoregulatory hormone exocytosis, enzymatic reactions, and nutrient flux to equilibrate the metabolic demands of a positive or negative energy balance. The identification of these mechanisms has great potential to identify novel targets for the treatment of diabetes and related metabolic disorders. Herein, we review the central role of the adipocyte in the maintenance of metabolic homeostasis, highlighting three critical mediators: adiponectin, leptin, and fatty acids.
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Affiliation(s)
- Jennifer H Stern
- Touchstone Diabetes Center, Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Joseph M Rutkowski
- Touchstone Diabetes Center, Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Philipp E Scherer
- Touchstone Diabetes Center, Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
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18
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Barbetti F, Colombo C, Haataja L, Cras-Méneur C, Bernardini S, Arvan P. Hyperglucagonemia in an animal model of insulin- deficient diabetes: what therapy can improve it? Clin Diabetes Endocrinol 2016; 2:11. [PMID: 28702245 PMCID: PMC5471666 DOI: 10.1186/s40842-016-0029-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Accepted: 04/11/2016] [Indexed: 02/06/2023] Open
Abstract
Background Intra-islet insulin contributes to alpha-cell suppression. Akita mice carry a toxic-gain-of- function Ins2 gene mutation encoding proinsulin-C(A7)Y, similar to that described in human Mutant Ins-gene induced Diabetes of Youth, which decreases intra-islet insulin. Herein, we examined Akita mice for examination of circulating insulin and circulating glucagon levels. The possibility that loss of intra-islet suppression of alpha-cells, with increased circulating glucagon, contributes to diabetes under conditions of intra-islet insulin deficiency, raises questions about effective treatments that may be available. Methods Blood glucose, plasma insulin, C-peptide I, C-peptide II, and glucagon were measured at various times during development of diabetes in Akita mice. We also used Akita- like hProC(A7)Y-CpepGFP transgenic mice in Ins2+/+, Ins2+/− and Ins2−/− genetic backgrounds (providing animals with greater or lesser defects in islet insulin production, respectively) in order to examine the relative abundance of immunostainable intra-islet glucagon-positive and insulin-positive cells. Similar measurements were made in Akita mice. Finally, the effects of treatment with insulin, exendin-4, and leptin on blood glucose were then compared in Akita mice. Results Interestingly, total insulin levels in the circulation were not frankly low in Akita mice, although they did not rise appropriately with the onset of hyperglycemia. By contrast, in severely diabetic Akita mice at 6 weeks of age, circulating glucagon levels were significantly elevated. Additionally, in Ins2+/− and Ins2−/− mice bearing the Akita-like hProC(A7)Y-CpepGFP transgene, development of diabetes correlated with an increase in the relative intra-islet abundance of immunostainable glucagon-positive cells, and a similar observation was made in Akita islets. In Akita mice, whereas a brief treatment with exendin-4 resulted in no apparent improvement in hyperglycemia, leptin treatment resulted in restoration of normoglycemia. Curiously, leptin treatment also suppressed circulating glucagon levels. Conclusions Loss of insulin-mediated intra-islet suppression of glucagon production may be a contributor to hyperglycemia in Akita mice, and leptin treatment appears beneficial in such a circumstance. This treatment might also be considered in some human diabetes patients with diminished insulin reserve.
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Affiliation(s)
- Fabrizio Barbetti
- Department of Experimental Medicine and Surgery, University of Tor Vergata, Rome, Italy.,Bambino Gesù Children's Hospital, IRCCS, Rome, Italy.,Department of Experimental Medicine and Surgery, University of Tor Vergata. Tor Vergata University Hospital, first floor, section D, room 118, Viale Oxford 81, 00133 Rome, Italy
| | - Carlo Colombo
- Department of Experimental Medicine and Surgery, University of Tor Vergata, Rome, Italy
| | - Leena Haataja
- Division of Metabolism, Endocrinology & Diabetes, University of Michigan Medical Center, Ann Arbor, MI USA
| | - Corentin Cras-Méneur
- Division of Metabolism, Endocrinology & Diabetes, University of Michigan Medical Center, Ann Arbor, MI USA
| | - Sergio Bernardini
- Department of Experimental Medicine and Surgery, University of Tor Vergata, Rome, Italy
| | - Peter Arvan
- Division of Metabolism, Endocrinology & Diabetes, University of Michigan Medical Center, Ann Arbor, MI USA.,University of Michigan Medical Center, Brehm Tower room 5112, 1000 Wall St., Ann Arbor, MI 48105 USA
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19
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Mirasierra M, Vallejo M. Glucose-dependent downregulation of glucagon gene expression mediated by selective interactions between ALX3 and PAX6 in mouse alpha cells. Diabetologia 2016; 59:766-75. [PMID: 26739814 DOI: 10.1007/s00125-015-3849-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/15/2015] [Accepted: 12/07/2015] [Indexed: 12/11/2022]
Abstract
AIMS/HYPOTHESIS The stimulation of glucagon secretion in response to decreased glucose levels has been studied extensively. In contrast, little is known about the regulation of glucagon gene expression in response to fluctuations in glucose concentration. Paired box 6 (PAX6) is a key transcription factor that regulates the glucagon promoter by binding to the G1 and G3 elements. Here, we investigated the role of the transcription factor aristaless-like homeobox 3 (ALX3) as a glucose-dependent modulator of PAX6 activity in alpha cells. METHODS Experiments were performed in wild-type or Alx3-deficient islets and alphaTC1 cells. We used chromatin immunoprecipitations and electrophoretic mobility shift assays for DNA binding, immunoprecipitations and pull-down assays for protein interactions, transfected cells for promoter activity, and small interfering RNA and quantitative RT-PCR for gene expression. RESULTS Elevated glucose concentration resulted in stimulated expression of Alx3 and decreased glucagon gene expression in wild-type islets. In ALX3-deficient islets, basal glucagon levels were non-responsive to changes in glucose concentration. In basal conditions ALX3 bound to the glucagon promoter at G3, but not at G1. ALX3 could form heterodimers with PAX6 that were permissive for binding to G3 but not to G1. Thus, increasing the levels of ALX3 in response to glucose resulted in the sequestration of PAX6 by ALX3 for binding to G1, thus reducing glucagon promoter activation and glucagon gene expression. CONCLUSIONS/INTERPRETATION Glucose-stimulated expression of ALX3 in alpha cells provides a regulatory mechanism for the downregulation of glucagon gene expression by interfering with PAX6-mediated transactivation on the glucagon G1 promoter element.
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Affiliation(s)
- Mercedes Mirasierra
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Madrid, Spain
- Instituto de Investigaciones Biomédicas Alberto Sols, Consejo Superior de Investigaciones Científicas/Universidad Autónoma de Madrid (CSIC/UAM), Calle Arturo Duperier 4, 28029, Madrid, Spain
| | - Mario Vallejo
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Madrid, Spain.
- Instituto de Investigaciones Biomédicas Alberto Sols, Consejo Superior de Investigaciones Científicas/Universidad Autónoma de Madrid (CSIC/UAM), Calle Arturo Duperier 4, 28029, Madrid, Spain.
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20
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Bermudez-Silva FJ, Romero-Zerbo SY, Haissaguerre M, Ruz-Maldonado I, Lhamyani S, El Bekay R, Tabarin A, Marsicano G, Cota D. The cannabinoid CB1 receptor and mTORC1 signalling pathways interact to modulate glucose homeostasis in mice. Dis Model Mech 2015; 9:51-61. [PMID: 26563389 PMCID: PMC4728331 DOI: 10.1242/dmm.020750] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2015] [Accepted: 11/02/2015] [Indexed: 12/31/2022] Open
Abstract
The endocannabinoid system (ECS) is an intercellular signalling mechanism that is present in the islets of Langerhans and plays a role in the modulation of insulin secretion and expansion of the β-cell mass. The downstream signalling pathways mediating these effects are poorly understood. Mammalian target of rapamycin complex 1 (mTORC1) signalling is a key intracellular pathway involved in energy homeostasis and is known to importantly affect the physiology of pancreatic islets. We investigated the possible relationship between cannabinoid type 1 (CB1) receptor signalling and the mTORC1 pathway in the endocrine pancreas of mice by using pharmacological analysis as well as mice genetically lacking the CB1 receptor or the downstream target of mTORC1, the kinase p70S6K1. In vitro static secretion experiments on islets, western blotting, and in vivo glucose and insulin tolerance tests were performed. The CB1 receptor antagonist rimonabant decreased glucose-stimulated insulin secretion (GSIS) at 0.1 µM while increasing phosphorylation of p70S6K1 and ribosomal protein S6 (rpS6) within the islets. Specific pharmacological blockade of mTORC1 by 3 nM rapamycin, as well as genetic deletion of p70S6K1, impaired the CB1-antagonist-mediated decrease in GSIS. In vivo experiments showed that 3 mg/kg body weight rimonabant decreased insulin levels and induced glucose intolerance in lean mice without altering peripheral insulin sensitivity; this effect was prevented by peripheral administration of low doses of rapamycin (0.1 mg/kg body weight), which increased insulin sensitivity. These findings suggest a functional interaction between the ECS and the mTORC1 pathway within the endocrine pancreas and at the whole-organism level, which could have implications for the development of new therapeutic approaches for pancreatic β-cell diseases. Summary: Evidence supporting a functional interaction between the endocannabinoid system and the mTORC1 pathway within the endocrine pancreas, which could have implications for the development of new therapeutic approaches for diabetes.
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Affiliation(s)
- Francisco J Bermudez-Silva
- Unidad de Gestion Clínica Intercentros de Endocrinología y Nutrición, Instituto de Investigación Biomédica de Málaga (IBIMA), Hospital Regional Universitario de Málaga/Universidad de Málaga, Málaga 29009, Spain Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Málaga 29009, Spain INSERM, Neurocentre Magendie, Physiopathologie de la Plasticité Neuronale, U862, Bordeaux F-33000, France Université de Bordeaux, Neurocentre Magendie, Physiopathologie de la Plasticité Neuronale, U862, Bordeaux F-33000, France
| | - Silvana Y Romero-Zerbo
- Unidad de Gestion Clínica Intercentros de Endocrinología y Nutrición, Instituto de Investigación Biomédica de Málaga (IBIMA), Hospital Regional Universitario de Málaga/Universidad de Málaga, Málaga 29009, Spain Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Málaga 29009, Spain
| | - Magalie Haissaguerre
- INSERM, Neurocentre Magendie, Physiopathologie de la Plasticité Neuronale, U862, Bordeaux F-33000, France Université de Bordeaux, Neurocentre Magendie, Physiopathologie de la Plasticité Neuronale, U862, Bordeaux F-33000, France
| | - Inmaculada Ruz-Maldonado
- Unidad de Gestion Clínica Intercentros de Endocrinología y Nutrición, Instituto de Investigación Biomédica de Málaga (IBIMA), Hospital Regional Universitario de Málaga/Universidad de Málaga, Málaga 29009, Spain Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Málaga 29009, Spain
| | - Said Lhamyani
- Unidad de Gestion Clínica Intercentros de Endocrinología y Nutrición, Instituto de Investigación Biomédica de Málaga (IBIMA), Hospital Regional Universitario de Málaga/Universidad de Málaga, Málaga 29009, Spain
| | - Rajaa El Bekay
- Unidad de Gestion Clínica Intercentros de Endocrinología y Nutrición, Instituto de Investigación Biomédica de Málaga (IBIMA), Hospital Regional Universitario de Málaga/Universidad de Málaga, Málaga 29009, Spain
| | - Antoine Tabarin
- INSERM, Neurocentre Magendie, Physiopathologie de la Plasticité Neuronale, U862, Bordeaux F-33000, France Université de Bordeaux, Neurocentre Magendie, Physiopathologie de la Plasticité Neuronale, U862, Bordeaux F-33000, France Service d'endocrinologie, diabétologie, maladies métaboliques et nutrition, Hôpital Haut-Lévêque, Pessac F-33604, France
| | - Giovanni Marsicano
- INSERM, Neurocentre Magendie, Physiopathologie de la Plasticité Neuronale, U862, Bordeaux F-33000, France Université de Bordeaux, Neurocentre Magendie, Physiopathologie de la Plasticité Neuronale, U862, Bordeaux F-33000, France
| | - Daniela Cota
- INSERM, Neurocentre Magendie, Physiopathologie de la Plasticité Neuronale, U862, Bordeaux F-33000, France Université de Bordeaux, Neurocentre Magendie, Physiopathologie de la Plasticité Neuronale, U862, Bordeaux F-33000, France
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Neri Calixto M, Ayllón Alvarez D, Vieyra Reyes P, Hernández-González M, Jiménez-Garcés C, Flores Ocampo P. Influencia de grelina y leptina sobre alteraciones psiquiátricas en sujetos con obesidad. ACTA ACUST UNITED AC 2015. [DOI: 10.1016/j.mei.2015.02.017] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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22
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Soedling H, Hodson DJ, Adrianssens AE, Gribble FM, Reimann F, Trapp S, Rutter GA. Limited impact on glucose homeostasis of leptin receptor deletion from insulin- or proglucagon-expressing cells. Mol Metab 2015; 4:619-30. [PMID: 26413468 PMCID: PMC4563029 DOI: 10.1016/j.molmet.2015.06.007] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/02/2015] [Accepted: 06/12/2015] [Indexed: 01/07/2023] Open
Abstract
AIMS/HYPOTHESIS The adipose tissue-derived hormone leptin plays an important role in the maintenance of body weight and glucose homeostasis. Leptin mediates its effects by interaction with leptin receptors (LepRb), which are highly expressed in the hypothalamus and other brain centres, and at lower levels in the periphery. Previous studies have used relatively promiscuous or inefficient Cre deleter strains, respectively, to explore the roles of LepR in pancreatic β and α cells. Here, we use two newly-developed Cre lines to explore the role of leptin signalling in insulin and proglucagon-expressing cells. METHODS Leptin receptor expression was measured in isolated mouse islets and highly-purified islet cells by RNASeq and quantitative RT-PCR. Mice lacking leptin signalling in pancreatic β, or in α and other proglucagon-expressing cells, were generated using Ins1Cre- or iGluCre-mediated recombination respectively of flox'd leptin receptor alleles. In vivo glucose homeostasis, changes in body weight, pancreatic histology and hormone secretion from isolated islets were assessed using standard techniques. RESULTS Leptin receptor mRNA levels were at or below the level of detection in wild-type adult mouse isolated islets and purified cells, and leptin signalling to Stat3 phosphorylation was undetectable. Whereas male mice further deleted for leptin receptors in β cells exhibited no abnormalities in glucose tolerance up to 16 weeks of age, females transiently displayed improved glucose tolerance at 8 weeks (11.2 ± 3.2% decrease in area under curve; p < 0.05), and improved (39.0 ± 13.0%, P < 0.05) glucose-stimulated insulin secretion in vitro. No differences were seen between genotypes in body weight, fasting glucose or β/α cell ratio. Deletion of LepR from α-cells, a minority of β cells, and a subset of proglucagon-expressing cells in the brain, exerted no effects on body weight, glucose or insulin tolerance, nor on pancreatic hormone secretion assessed in vivo and in vitro. CONCLUSIONS/INTERPRETATION The use here of a highly selective Cre recombinase indicates that leptin signalling plays a relatively minor, age- and sex-dependent role in the control of β cell function in the mouse. No in vivo role for leptin receptors on α cells, nor in other proglucagon-expressing cells, was detected in this study.
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Affiliation(s)
- Helen Soedling
- Section of Cell Biology and Functional Genomics, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Imperial College London, du Cane Road, London W12 0NN, UK
| | - David J Hodson
- Section of Cell Biology and Functional Genomics, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Imperial College London, du Cane Road, London W12 0NN, UK
| | | | - Fiona M Gribble
- University of Cambridge Metabolic Research Laboratories, Cambridge, UK
| | - Frank Reimann
- University of Cambridge Metabolic Research Laboratories, Cambridge, UK
| | - Stefan Trapp
- Centre for Cardiovascular and Metabolic Neuroscience, Department of Neuroscience, Physiology & Pharmacology, University College London, London, UK
| | - Guy A Rutter
- Section of Cell Biology and Functional Genomics, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Imperial College London, du Cane Road, London W12 0NN, UK
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23
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Nakamura T, Yoshikawa T, Naganuma F, Mohsen A, Iida T, Miura Y, Sugawara A, Yanai K. Role of histamine H3 receptor in glucagon-secreting αTC1.6 cells. FEBS Open Bio 2014; 5:36-41. [PMID: 25685663 PMCID: PMC4309840 DOI: 10.1016/j.fob.2014.12.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2014] [Revised: 12/08/2014] [Accepted: 12/09/2014] [Indexed: 12/14/2022] Open
Abstract
Histamine H3 receptor is expressed in pancreatic α-cells. Histamine H3 receptor negatively regulates glucagon secretion from αTC1.6 cells. Immepip, a selective H3 receptor agonist, decreases serum glucagon concentration in rats.
Pancreatic α-cells secrete glucagon to maintain energy homeostasis. Although histamine has an important role in energy homeostasis, the expression and function of histamine receptors in pancreatic α-cells remains unknown. We found that the histamine H3 receptor (H3R) was expressed in mouse pancreatic α-cells and αTC1.6 cells, a mouse pancreatic α-cell line. H3R inhibited glucagon secretion from αTC1.6 cells by inhibiting an increase in intracellular Ca2+ concentration. We also found that immepip, a selective H3R agonist, decreased serum glucagon concentration in rats. These results suggest that H3R modulates glucagon secretion from pancreatic α-cells.
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Affiliation(s)
- Tadaho Nakamura
- Department of Pharmacology, Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi 980-8575, Japan
| | - Takeo Yoshikawa
- Department of Pharmacology, Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi 980-8575, Japan
| | - Fumito Naganuma
- Department of Pharmacology, Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi 980-8575, Japan
| | - Attayeb Mohsen
- Department of Pharmacology, Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi 980-8575, Japan
| | - Tomomitsu Iida
- Department of Pharmacology, Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi 980-8575, Japan
| | - Yamato Miura
- Department of Pharmacology, Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi 980-8575, Japan
| | - Akira Sugawara
- Department of Molecular Endocrinology, Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi 980-8575, Japan
| | - Kazuhiko Yanai
- Department of Pharmacology, Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi 980-8575, Japan
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24
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Abstract
The fat‐derived hormone, leptin, is well known to regulate body weight. However, there is now substantial evidence that leptin also plays a primary role in the regulation of glucose homeostasis, independent of actions on food intake, energy expenditure or body weight. As such, leptin might have clinical utility in treating hyperglycemia, particularly in conditions of leptin deficiency, such as lipodystrophy and diabetes mellitus. The mechanisms through which leptin modulates glucose metabolism have not been fully elucidated. Leptin receptors are widely expressed in peripheral tissues, including the endocrine pancreas, liver, skeletal muscle and adipose, and both direct and indirect leptin action on these tissues contributes to the control of glucose homeostasis. Here we review the role of leptin in glucose homeostasis, along with our present understanding of the mechanisms involved. (J Diabetes Invest, doi: 10.1111/j.2040‐1124.2012.00203.x, 2012)
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Affiliation(s)
- Heather C Denroche
- Department of Cellular and Physiological Sciences, The Life Sciences Institute
| | - Frank K Huynh
- Department of Cellular and Physiological Sciences, The Life Sciences Institute
| | - Timothy J Kieffer
- Department of Cellular and Physiological Sciences, The Life Sciences Institute ; Department of Surgery, University of British Columbia, Vancouver, British Columbia, Canada
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25
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Abstract
Glucose homeostasis is precisely regulated by glucagon and insulin, which are released by pancreatic α- and β-cells, respectively. While β-cells have been the focus of intense research, less is known about α-cell function and the actions of glucagon. In recent years, the study of this endocrine cell type has experienced a renewed drive. The present review contains a summary of established concepts as well as new information about the regulation of α-cells by glucose, amino acids, fatty acids and other nutrients, focusing especially on glucagon release, glucagon synthesis and α-cell survival. We have also discussed the role of glucagon in glucose homeostasis and in energy and lipid metabolism as well as its potential as a modulator of food intake and body weight. In addition to the well-established action on the liver, we discuss the effects of glucagon in other organs, where the glucagon receptor is expressed. These tissues include the heart, kidneys, adipose tissue, brain, small intestine and the gustatory epithelium. Alterations in α-cell function and abnormal glucagon concentrations are present in diabetes and are thought to aggravate the hyperglycaemic state of diabetic patients. In this respect, several experimental approaches in diabetic models have shown important beneficial results in improving hyperglycaemia after the modulation of glucagon secretion or action. Moreover, glucagon receptor agonism has also been used as a therapeutic strategy to treat obesity.
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26
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Tudurí E, Denroche HC, Kara JA, Asadi A, Fox JK, Kieffer TJ. Partial ablation of leptin signaling in mouse pancreatic α-cells does not alter either glucose or lipid homeostasis. Am J Physiol Endocrinol Metab 2014; 306:E748-55. [PMID: 24473435 DOI: 10.1152/ajpendo.00681.2013] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The role of glucagon in the pathological condition of diabetes is gaining interest, and it has been recently reported that its action is essential for hyperglycemia to occur. Glucagon levels, which are elevated in some diabetic models, are reduced following leptin therapy. Likewise, hyperglycemia is corrected in type 1 diabetic mice treated with leptin, although the mechanisms have not been fully determined. A direct inhibitory effect of leptin on mouse and human α-cells has been demonstrated at the levels of electrical activity, calcium signaling, and glucagon secretion. In the present study we employed the Cre-loxP strategy to generate Lepr(flox/flox) Gcg-cre mice, which specifically lack leptin receptors in glucagon-secreting α-cells, to determine whether leptin resistance in α-cells contributes to hyperglucagonemia, and also whether leptin action in α-cells is required to improve glycemia in type 1 diabetes with leptin therapy. Immunohistochemical analysis of pancreas sections revealed Cre-mediated recombination in ∼ 43% of the α-cells. We observed that in vivo Lepr(flox/flox) Gcg-cre mice display normal glucose and lipid homeostasis. In addition, leptin administration in streptozotocin-induced diabetic Lepr(flox/flox) Gcg-cre mice restored euglycemia similarly to control mice. These findings suggest that loss of leptin receptor signaling in close to one-half of α-cells does not alter glucose metabolism in vivo, nor is it sufficient to prevent the therapeutic action of leptin in type 1 diabetes.
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MESH Headings
- Animals
- Cells, Cultured
- Diabetes Mellitus, Experimental/drug therapy
- Diabetes Mellitus, Experimental/genetics
- Diabetes Mellitus, Experimental/metabolism
- Diabetes Mellitus, Type 1/drug therapy
- Diabetes Mellitus, Type 1/genetics
- Diabetes Mellitus, Type 1/metabolism
- Female
- Gene Deletion
- Glucagon-Secreting Cells/metabolism
- Glucose/metabolism
- Homeostasis/genetics
- Leptin/metabolism
- Leptin/therapeutic use
- Lipid Metabolism/genetics
- Mice
- Mice, Inbred C57BL
- Mice, Transgenic
- Receptors, Leptin/genetics
- Receptors, Leptin/metabolism
- Signal Transduction/genetics
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Affiliation(s)
- Eva Tudurí
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada; and
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27
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Romacho T, Elsen M, Röhrborn D, Eckel J. Adipose tissue and its role in organ crosstalk. Acta Physiol (Oxf) 2014; 210:733-53. [PMID: 24495317 DOI: 10.1111/apha.12246] [Citation(s) in RCA: 191] [Impact Index Per Article: 19.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2013] [Revised: 12/18/2013] [Accepted: 01/28/2014] [Indexed: 12/13/2022]
Abstract
The discovery of adipokines has revealed adipose tissue as a central node in the interorgan crosstalk network, which mediates the regulation of multiple organs and tissues. Adipose tissue is a true endocrine organ that produces and secretes a wide range of mediators regulating adipose tissue function in an auto-/paracrine manner and important distant targets, such as the liver, skeletal muscle, the pancreas and the cardiovascular system. In metabolic disorders such as obesity, enlargement of adipocytes leads to adipose tissue dysfunction and a shift in the secretory profile with an increased release of pro-inflammatory adipokines. Adipose tissue dysfunction has a central role in the development of insulin resistance, type 2 diabetes, and cardiovascular diseases. Besides the well-acknowledged role of adipokines in metabolic diseases, and the increasing number of adipokines being discovered in the last years, the mechanisms underlying the release of many adipokines from adipose tissue remain largely unknown. To combat metabolic diseases, it is crucial to better understand how adipokines can modulate adipose tissue growth and function. Therefore, we will focus on adipokines with a prominent role in auto-/paracrine crosstalk within the adipose tissue such as RBP4, HO-1, WISP2, SFRPs and chemerin. To depict the endocrine crosstalk between adipose tissue with skeletal muscle, the cardiovascular system and the pancreas, we will report the main findings regarding the direct effects of adiponectin, leptin, DPP4 and visfatin on skeletal muscle insulin resistance, cardiovascular function and β-cell growth and function.
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Affiliation(s)
- T. Romacho
- Paul-Langerhans-Group for Integrative Physiology; German Diabetes Center; Düsseldorf Germany
| | - M. Elsen
- Paul-Langerhans-Group for Integrative Physiology; German Diabetes Center; Düsseldorf Germany
| | - D. Röhrborn
- Paul-Langerhans-Group for Integrative Physiology; German Diabetes Center; Düsseldorf Germany
| | - J. Eckel
- Paul-Langerhans-Group for Integrative Physiology; German Diabetes Center; Düsseldorf Germany
- German Center for Diabetes Research (DZD e.V.); Düsseldorf Germany
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28
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D'souza AM, Asadi A, Johnson JD, Covey SD, Kieffer TJ. Leptin deficiency in rats results in hyperinsulinemia and impaired glucose homeostasis. Endocrinology 2014; 155:1268-79. [PMID: 24467741 DOI: 10.1210/en.2013-1523] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Leptin, an adipocyte-derived hormone, has well-established anorexigenic effects but is also able to regulate glucose homeostasis independent of body weight. Until recently, the ob/ob mouse was the only animal model of global leptin deficiency. Here we report the effects of leptin deficiency on glucose homeostasis in male and female leptin knockout (KO) rats. Leptin KO rats developed obesity by 6 to 7 weeks of age, and lipid mass was increased by more than 2-fold compared with that of wild-type (WT) littermates at 18 weeks of age. Hyperinsulinemia and insulin resistance were evident in both males and females and were sustained with aging. Male KO rats experienced transient mild fasting hyperglycemia between 14 and 25 weeks of age, but thereafter fasting glucose levels were comparable to those of WT littermates up to 36 weeks of age. Fasting glucose levels of female KO rats were similar to those of WT littermates. Male KO rats exhibited a 3-fold increase in the proportion of β-cell area relative to total pancreas at 36 weeks of age. Islets from 12-week-old KO rats secreted more insulin when stimulated than islets from WT littermates. Leptin replacement via miniosmotic pump (100 μg/d) reduced food intake, attenuated weight gain, normalized glucose tolerance, and improved glucose-stimulated insulin secretion and insulin sensitivity. Together, these data demonstrate that the absence of leptin in rats recapitulates some of the phenotype previously observed in ob/ob mice including development of hyperinsulinemia, obesity, and insulin resistance.
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Affiliation(s)
- Anna M D'souza
- Department of Cellular and Physiological Sciences (A.M.D., A.A., J.D.J., T.J.K.), Department of Biochemistry and Molecular Biology (S.D.C.), and Department of Surgery (J.D.J., T.J.K.), University of British Columbia, Vancouver British Columbia, Canada V5Z 4E3
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29
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Binder E, Bermúdez-Silva FJ, Elie M, Leste-Lasserre T, Belluomo I, Clark S, Duchampt A, Mithieux G, Cota D. Leucine supplementation modulates fuel substrates utilization and glucose metabolism in previously obese mice. Obesity (Silver Spring) 2014; 22:713-20. [PMID: 23894080 DOI: 10.1002/oby.20578] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/28/2013] [Accepted: 07/04/2013] [Indexed: 12/12/2022]
Abstract
OBJECTIVE High-protein diets favor weight loss and its maintenance. Whether these effects might be recapitulated by certain amino acids is unknown. Therefore, the impact of leucine supplementation on energy balance and associated metabolic changes in diet-induced obese (DIO) mice during and after weight loss was investigated. METHODS DIO C57BL/6J mice were fed a normocaloric diet to induce weight loss while receiving or not the amino acid leucine in drinking water. Body weight, food intake, body composition, energy expenditure, glucose tolerance, insulin, and leptin sensitivity were evaluated. Q-PCR analysis was performed on muscle, brown and white adipose tissues. RESULTS DIO mice decreased body weight and fat mass in response to chow, but supplementation with leucine did not affect these parameters. During weight maintenance, mice supplemented with leucine had improved glucose tolerance, increased leptin sensitivity, and lower respiratory quotient. The latter was associated with changes in the expression of several genes modulating fatty acid metabolism and mitochondrial activity in the epididymal white and the brown adipose tissues, but not muscle. CONCLUSIONS Leucine supplementation might represent an adjuvant beneficial nutritional therapy during weight loss and maintenance, because it improves lipid and glucose metabolism and restores leptin sensitivity in previously obese animals.
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Affiliation(s)
- Elke Binder
- NeuroCentre Magendie, INSERM, Physiopathologie de la Plasticité Neuronale, U862, Bordeaux, France; NeuroCentre Magendie, Physiopathologie de la Plasticité Neuronale, Université de Bordeaux, U862, Bordeaux, France
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30
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Godoy-Matos AF. The role of glucagon on type 2 diabetes at a glance. Diabetol Metab Syndr 2014; 6:91. [PMID: 25177371 PMCID: PMC4148933 DOI: 10.1186/1758-5996-6-91] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/27/2014] [Accepted: 08/20/2014] [Indexed: 12/25/2022] Open
Abstract
The opposite effects of insulin and glucagon in fuel homeostasis, the paracrine/endocrine inhibitory effects of insulin on glucagon secretion and the hyperglucagonemia in the pathogenesis of type 2 diabetes (T2D) have long been recognized. Inappropriately increased alpha-cell function importantly contributes to hyperglycemia and reflects the loss of tonic restraint normally exerted by high local concentrations of insulin on alpha-cells, possibly as a result of beta-cell failure and alpha-cell insulin resistance, but additional mechanisms, such as the participation of incretin hormones in this response, have also been suggested. Three classes of drugs already available for clinical use address the abnormalities of glucagon secretion in T2D, namely, the GLP-1 receptor agonists (GLP-1RA), the inhibitors of dipeptidyl peptidase-4 (DPP-4i) and the amylin agonist pramlintide; it has been proposed that the glucagonostatic and insulinotropic effects of GLP-1RA equally contribute to their hypoglycemic efficacy. In this review, the control of glucagon secretion and its participation in T2D pathogenesis are summarized.
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Affiliation(s)
- Amélio F Godoy-Matos
- Metabolism Unit, Instituto Estadual de Diabetes e Endocrinologia, Rio de Janeiro and Catholic University, Rio de Janeiro, Brazil
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31
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Binder E, Bermúdez-Silva FJ, André C, Elie M, Romero-Zerbo SY, Leste-Lasserre T, Belluomo L, Duchampt A, Clark S, Aubert A, Mezzullo M, Fanelli F, Pagotto U, Layé S, Mithieux G, Cota D. Leucine supplementation protects from insulin resistance by regulating adiposity levels. PLoS One 2013; 8:e74705. [PMID: 24086364 PMCID: PMC3783457 DOI: 10.1371/journal.pone.0074705] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2013] [Accepted: 08/02/2013] [Indexed: 02/01/2023] Open
Abstract
Background Leucine supplementation might have therapeutic potential in preventing diet-induced obesity and improving insulin sensitivity. However, the underlying mechanisms are at present unclear. Additionally, it is unclear whether leucine supplementation might be equally efficacious once obesity has developed. Methodology/Principal Findings Male C57BL/6J mice were fed chow or a high-fat diet (HFD), supplemented or not with leucine for 17 weeks. Another group of HFD-fed mice (HFD-pairfat group) was food restricted in order to reach an adiposity level comparable to that of HFD-Leu mice. Finally, a third group of mice was exposed to HFD for 12 weeks before being chronically supplemented with leucine. Leucine supplementation in HFD-fed mice decreased body weight and fat mass by increasing energy expenditure, fatty acid oxidation and locomotor activity in vivo. The decreased adiposity in HFD-Leu mice was associated with increased expression of uncoupling protein 3 (UCP-3) in the brown adipose tissue, better insulin sensitivity, increased intestinal gluconeogenesis and preservation of islets of Langerhans histomorphology and function. HFD-pairfat mice had a comparable improvement in insulin sensitivity, without changes in islets physiology or intestinal gluconeogenesis. Remarkably, both HFD-Leu and HFD-pairfat mice had decreased hepatic lipid content, which likely helped improve insulin sensitivity. In contrast, when leucine was supplemented to already obese animals, no changes in body weight, body composition or glucose metabolism were observed. Conclusions/Significance These findings suggest that leucine improves insulin sensitivity in HFD-fed mice by primarily decreasing adiposity, rather than directly acting on peripheral target organs. However, beneficial effects of leucine on intestinal gluconeogenesis and islets of Langerhans's physiology might help prevent type 2 diabetes development. Differently, metabolic benefit of leucine supplementation is lacking in already obese animals, a phenomenon possibly related to the extent of the obesity before starting the supplementation.
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Affiliation(s)
- Elke Binder
- INSERM, Neurocentre Magendie, Physiopathologie de la Plasticité Neuronale, U862, Bordeaux, France
- Université de Bordeaux, Neurocentre Magendie, Physiopathologie de la Plasticité Neuronale, U862, Bordeaux, France
| | - Francisco J. Bermúdez-Silva
- INSERM, Neurocentre Magendie, Physiopathologie de la Plasticité Neuronale, U862, Bordeaux, France
- Université de Bordeaux, Neurocentre Magendie, Physiopathologie de la Plasticité Neuronale, U862, Bordeaux, France
- IBIMA-Hospital Carlos Haya, Laboratorio de Investigación, Malaga, Spain
| | - Caroline André
- INSERM, Neurocentre Magendie, Physiopathologie de la Plasticité Neuronale, U862, Bordeaux, France
- Université de Bordeaux, Neurocentre Magendie, Physiopathologie de la Plasticité Neuronale, U862, Bordeaux, France
| | - Melissa Elie
- INSERM, Neurocentre Magendie, Physiopathologie de la Plasticité Neuronale, U862, Bordeaux, France
- Université de Bordeaux, Neurocentre Magendie, Physiopathologie de la Plasticité Neuronale, U862, Bordeaux, France
| | - Silvana Y. Romero-Zerbo
- INSERM, Neurocentre Magendie, Physiopathologie de la Plasticité Neuronale, U862, Bordeaux, France
- Université de Bordeaux, Neurocentre Magendie, Physiopathologie de la Plasticité Neuronale, U862, Bordeaux, France
- IBIMA-Hospital Carlos Haya, Laboratorio de Investigación, Malaga, Spain
| | - Thierry Leste-Lasserre
- INSERM, Neurocentre Magendie, Physiopathologie de la Plasticité Neuronale, U862, Bordeaux, France
- Université de Bordeaux, Neurocentre Magendie, Physiopathologie de la Plasticité Neuronale, U862, Bordeaux, France
| | - llaria Belluomo
- INSERM, Neurocentre Magendie, Physiopathologie de la Plasticité Neuronale, U862, Bordeaux, France
- Université de Bordeaux, Neurocentre Magendie, Physiopathologie de la Plasticité Neuronale, U862, Bordeaux, France
| | - Adeline Duchampt
- INSERM, U855, Lyon, France
- Université de Lyon, Lyon, France
- Université Lyon 1, Villeurbanne, France
| | - Samantha Clark
- INSERM, Neurocentre Magendie, Physiopathologie de la Plasticité Neuronale, U862, Bordeaux, France
- Université de Bordeaux, Neurocentre Magendie, Physiopathologie de la Plasticité Neuronale, U862, Bordeaux, France
| | - Agnes Aubert
- Nutrition et Neurobiologie Intégrée, Université de Bordeaux, UMR 1286, Bordeaux, France
- INRA, Nutrition et Neurobiologie Intégrée, UMR 1286, Bordeaux, France
| | - Marco Mezzullo
- Endocrinology Unit and Centro di Ricerca Biomedica Applicata, Department of Clinical Medicine, S.Orsola-Malpighi Hospital, Alma Mater University of Bologna, Bologna, Italy
| | - Flaminia Fanelli
- Endocrinology Unit and Centro di Ricerca Biomedica Applicata, Department of Clinical Medicine, S.Orsola-Malpighi Hospital, Alma Mater University of Bologna, Bologna, Italy
| | - Uberto Pagotto
- Endocrinology Unit and Centro di Ricerca Biomedica Applicata, Department of Clinical Medicine, S.Orsola-Malpighi Hospital, Alma Mater University of Bologna, Bologna, Italy
| | - Sophie Layé
- Nutrition et Neurobiologie Intégrée, Université de Bordeaux, UMR 1286, Bordeaux, France
- INRA, Nutrition et Neurobiologie Intégrée, UMR 1286, Bordeaux, France
| | - Gilles Mithieux
- INSERM, U855, Lyon, France
- Université de Lyon, Lyon, France
- Université Lyon 1, Villeurbanne, France
| | - Daniela Cota
- INSERM, Neurocentre Magendie, Physiopathologie de la Plasticité Neuronale, U862, Bordeaux, France
- Université de Lyon, Lyon, France
- * E-mail:
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Dall'Aglio C, Mercati F, Pascucci L, Ceccarelli P. Immunolocalization of leptin and its receptor in the pancreas of the horse. Acta Histochem 2013; 115:757-60. [PMID: 23830247 DOI: 10.1016/j.acthis.2013.05.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2012] [Revised: 05/17/2013] [Accepted: 05/20/2013] [Indexed: 11/29/2022]
Abstract
The aim of the present study was to demonstrate the presence and the distribution of leptin and its receptor in the pancreas of horses of both sexes by immunohistochemical techniques. The presence and the distribution of leptin receptor were also investigated in the initial portion of the duodenum, near the duodenal ampulla. The immunohistochemical investigation demonstrates the immunolocalization of both leptin and its receptor in the endocrine cells of pancreatic islets, which led us to hypothesize that leptin may possibly exert an autocrine/paracrine action on the endocrine pancreas. Examination of the exocrine pancreas in the same treated sections showed the presence of leptin-positive cells in the wall of the interlobular ducts where, however, the receptor was not found. This observation led us to consider that some cells of the ducts may perform some minimal secretory activity, and that leptin produced by these ductal cells may reach the duodenum in the pancreatic juice. This hypothesis is enhanced by the presence of leptin-receptor in the duodenum of the same animals, where the epithelial cells of the mucosa showed intense immunolocalization in the brush border. Consequently it is possible that the ductular leptin may play a regulatory role on the functionality of the enterocytes.
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Affiliation(s)
- Cecilia Dall'Aglio
- Dipartimento di Scienze Biopatologiche Veterinarie ed Igiene delle Produzioni Animali e Alimentari, Sezione di Anatomia - Università degli Studi di Perugia, Via San Costanzo 4, 06126 Perugia, Italy.
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Lv Z, Li G, Li Y, Ying C, Chen J, Chen T, Wei J, Lin Y, Jiang Y, Wang Y, Shu B, Xu B, Xu S. Glucose and lipid homeostasis in adult rat is impaired by early-life exposure to perfluorooctane sulfonate. ENVIRONMENTAL TOXICOLOGY 2013; 28:532-42. [PMID: 23983163 DOI: 10.1002/tox.20747] [Citation(s) in RCA: 91] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2011] [Revised: 05/05/2011] [Accepted: 05/22/2011] [Indexed: 05/20/2023]
Abstract
Perfluorooctane sulfonate (PFOS), which belongs to the degradation product of many perfluorinated compounds, is on the list of persistent organic pollutants (POPs) and is currently detected in both wildlife and humans. The consequence of gestational and lactational exposure to PFOS on prediabetes effect in offspring was investigated in rats in the present study. Maternal rats were treated with vehicle, 0.5 mg/kg/day or 1.5 mg/kg/day PFOS respectively from gestation day 0 to postnatal day 21. The glucose and lipid metabolism effects were investigated on the offspring in adulthood. The gestational and lactational exposure to PFOS led to low body weight from birth to weaning, and evoked signs of a prediabetic state, with elevated fasting serum insulin and leptin level, impaired glucose tolerance, though the fasting serum glucose and glycosylated serum protein level were normal. Abnormal lipid homeostasis was also observed by the phenomenon of hepatic steatosis and increased gonadal fat pad weight. However, the circulating serum level of fasting triglyceride and cholesterol level were no different from controls. Our results suggested that developmental exposure to PFOS may contribute to glucose and lipid metabolic disorder in adulthood.
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Affiliation(s)
- Ziquan Lv
- Ministry of Education Key Laboratory of Environment and Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
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Tudurí E, Bruin JE, Denroche HC, Fox JK, Johnson JD, Kieffer TJ. Impaired Ca(2+) signaling in β-cells lacking leptin receptors by Cre-loxP recombination. PLoS One 2013; 8:e71075. [PMID: 23936486 PMCID: PMC3731269 DOI: 10.1371/journal.pone.0071075] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2013] [Accepted: 06/30/2013] [Indexed: 11/21/2022] Open
Abstract
Obesity is a major risk factor for diabetes and is typically associated with hyperleptinemia and a state of leptin resistance. The impact of chronically elevated leptin levels on the function of insulin-secreting β-cells has not been elucidated. We previously generated mice lacking leptin signaling in β-cells by using the Cre-loxP strategy and showed that these animals develop increased body weight and adiposity, hyperinsulinemia, impaired glucose-stimulated insulin secretion and insulin resistance. Here, we performed several in vitro studies and observed that β-cells lacking leptin signaling in this model are capable of properly metabolizing glucose, but show impaired intracellular Ca2+ oscillations and lack of synchrony within the islets in response to glucose, display reduced response to tolbutamide and exhibit morphological abnormalities including increased autophagy. Defects in intracellular Ca2+ signaling were observed even in neonatal islets, ruling out the possible contribution of obesity to the β-cell irregularities observed in adults. In parallel, we also detected a disrupted intracellular Ca2+ pattern in response to glucose and tolbutamide in control islets from adult transgenic mice expressing Cre recombinase under the rat insulin promoter, despite these animals being glucose tolerant and secreting normal levels of insulin in response to glucose. This unexpected observation impeded us from discerning the consequences of impaired leptin signaling as opposed to long-term Cre expression in the function of insulin-secreting cells. These findings highlight the need to generate improved Cre-driver mouse models or new tools to induce Cre recombination in β-cells.
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Affiliation(s)
- Eva Tudurí
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Jennifer E. Bruin
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Heather C. Denroche
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Jessica K. Fox
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - James D. Johnson
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
- Department of Surgery, University of British Columbia, Vancouver, British Columbia, Canada
| | - Timothy J. Kieffer
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
- Department of Surgery, University of British Columbia, Vancouver, British Columbia, Canada
- * E-mail:
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Leptin promotes K(ATP) channel trafficking by AMPK signaling in pancreatic β-cells. Proc Natl Acad Sci U S A 2013; 110:12673-8. [PMID: 23858470 DOI: 10.1073/pnas.1216351110] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Leptin is a pivotal regulator of energy and glucose homeostasis, and defects in leptin signaling result in obesity and diabetes. The ATP-sensitive potassium (K(ATP)) channels couple glucose metabolism to insulin secretion in pancreatic β-cells. In this study, we provide evidence that leptin modulates pancreatic β-cell functions by promoting K(ATP) channel translocation to the plasma membrane via AMP-activated protein kinase (AMPK) signaling. K(ATP) channels were localized mostly to intracellular compartments of pancreatic β-cells in the fed state and translocated to the plasma membrane in the fasted state. This process was defective in leptin-deficient ob/ob mice, but restored by leptin treatment. We discovered that the molecular mechanism of leptin-induced AMPK activation involves canonical transient receptor potential 4 and calcium/calmodulin-dependent protein kinase kinase β. AMPK activation was dependent on both leptin and glucose concentrations, so at optimal concentrations of leptin, AMPK was activated sufficiently to induce K(ATP) channel trafficking and hyperpolarization of pancreatic β-cells in a physiological range of fasting glucose levels. There was a close correlation between phospho-AMPK levels and β-cell membrane potentials, suggesting that AMPK-dependent K(ATP) channel trafficking is a key mechanism for regulating β-cell membrane potentials. Our results present a signaling pathway whereby leptin regulates glucose homeostasis by modulating β-cell excitability.
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Harris RBS. Direct and indirect effects of leptin on adipocyte metabolism. Biochim Biophys Acta Mol Basis Dis 2013; 1842:414-23. [PMID: 23685313 DOI: 10.1016/j.bbadis.2013.05.009] [Citation(s) in RCA: 177] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2013] [Revised: 04/18/2013] [Accepted: 05/06/2013] [Indexed: 12/22/2022]
Abstract
Leptin is hypothesized to function as a negative feedback signal in the regulation of energy balance. It is produced primarily by adipose tissue and circulating concentrations correlate with the size of body fat stores. Administration of exogenous leptin to normal weight, leptin responsive animals inhibits food intake and reduces the size of body fat stores whereas mice that are deficient in either leptin or functional leptin receptors are hyperphagic and obese, consistent with a role for leptin in the control of body weight. This review discusses the effect of leptin on adipocyte metabolism. Because adipocytes express leptin receptors there is the potential for leptin to influence adipocyte metabolism directly. Adipocytes also are insulin responsive and receive sympathetic innervation, therefore leptin can also modify adipocyte metabolism indirectly. Studies published to date suggest that direct activation of adipocyte leptin receptors has little effect on cell metabolism in vivo, but that leptin modifies adipocyte sensitivity to insulin to inhibit lipid accumulation. In vivo administration of leptin leads to a suppression of lipogenesis, an increase in triglyceride hydrolysis and an increase in fatty acid and glucose oxidation. Activation of central leptin receptors also contributes to the development of a catabolic state in adipocytes, but this may vary between different fat depots. Leptin reduces the size of white fat depots by inhibiting cell proliferation both through induction of inhibitory circulating factors and by contributing to sympathetic tone which suppresses adipocyte proliferation. This article is part of a Special Issue entitled: Modulation of Adipose Tissue in Health and Disease.
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Affiliation(s)
- Ruth B S Harris
- Department of Physiology, Medical College of Georgia, Georgia Regents University, USA.
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Nyrén R, Chang CL, Lindström P, Barmina A, Vorrsjö E, Ali Y, Juntti-Berggren L, Bensadoun A, Young SG, Olivecrona T, Olivecrona G. Localization of lipoprotein lipase and GPIHBP1 in mouse pancreas: effects of diet and leptin deficiency. BMC PHYSIOLOGY 2012. [PMID: 23186339 PMCID: PMC3537605 DOI: 10.1186/1472-6793-12-14] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
BACKGROUND Lipoprotein lipase (LPL) hydrolyzes triglycerides in plasma lipoproteins and enables uptake of lipolysis products for energy production or storage in tissues. Our aim was to study the localization of LPL and its endothelial anchoring protein glycosylphosphatidylinositol-anchored high density lipoprotein-binding protein 1 (GPIHBP1) in mouse pancreas, and effects of diet and leptin deficiency on their expression patterns. For this, immunofluorescence microscopy was used on pancreatic tissue from C57BL/6 mouse embryos (E18), adult mice on normal or high-fat diet, and adult ob/ob-mice treated or not with leptin. The distribution of LPL and GPIHBP1 was compared to insulin, glucagon and CD31. Heparin injections were used to discriminate between intracellular and extracellular LPL. RESULTS In the exocrine pancreas LPL was found in capillaries, and was mostly co-localized with GPIHBP1. LPL was releasable by heparin, indicating localization on cell surfaces. Within the islets, most of the LPL was associated with beta cells and could not be released by heparin, indicating that the enzyme remained mostly within cells. Staining for LPL was found also in the glucagon-producing alpha cells, both in embryos (E18) and in adult mice. Only small amounts of LPL were found together with GPIHBP1 within the capillaries of islets. Neither a high fat diet nor fasting/re-feeding markedly altered the distribution pattern of LPL or GPIHBP1 in mouse pancreas. Islets from ob/ob mice appeared completely deficient of LPL in the beta cells, while LPL-staining was normal in alpha cells and in the exocrine pancreas. Leptin treatment of ob/ob mice for 12 days reversed this pattern, so that most of the islets expressed LPL in beta cells. CONCLUSIONS We conclude that both LPL and GPIHBP1 are present in mouse pancreas, and that LPL expression in beta cells is dependent on leptin.
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Affiliation(s)
- Rakel Nyrén
- Department of Medical Biosciences/Physiological Chemistry, Umeå University, Umeå, Sweden
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Dall'Aglio C, Polisca A, Boiti C, Ceccarelli P. Immunolocalization of leptin and its receptor in the placenta of cats. Acta Histochem 2012; 114:719-22. [PMID: 22265029 DOI: 10.1016/j.acthis.2011.12.008] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2011] [Revised: 12/14/2011] [Accepted: 12/15/2011] [Indexed: 11/28/2022]
Abstract
The aim of the present study was to investigate the presence and the distribution of leptin (Ob) and its receptor (ObR) in the feline placenta at term by means of immunohistochemical techniques. A few Ob-positive cells were observed scattered in the lamellae of the labyrinthine placenta. These cells had the morphological characteristics typical of the very abundant cells in the placenta of cats that can be considered as being decidual and, in some cases, syncytiotrophoblastic cells. A few ObR-positive cells were observed in the same placental portion and were mainly localized in the lamellae, showing morphological features typical of decidual and syncytiotrophoblastic cells. No other structure of the placenta or the uterine wall showed positive reaction to the antibodies used. Our results confirm what has already been demonstrated in humans and laboratory animals, but not in domestic animals. Together with other emerging data on the secretory activities of the feline placenta, our study underlines its relevance in the production of molecules long known to be involved in appetite control and, probably, with potential effects on the developing fetus.
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Affiliation(s)
- Cecilia Dall'Aglio
- Dipartimento di Scienze Biopatologiche ed Igiene delle Produzioni Animali ed Alimentari, Sezione di Anatomia Veterinaria, Perugia, Italy.
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Abstract
Glucagon, a peptide hormone secreted from the α-cells of the pancreatic islets, is critical for blood glucose homeostasis. We reviewed the literature and employed a computational systems analysis of intracellular metabolic and electrical regulation of glucagon secretion to better understand these processes. The mathematical model of α-cell metabolic parameters is based on our previous model for pancreatic β-cells. We also formulated an ionic model for action potentials that incorporates Ca ( 2+) , K (+) , Na (+) and Cl (-) currents. Metabolic and ionic models are coupled to the equations describing Ca ( 2+) homeostasis and glucagon secretion that depends on activation of specific voltage-gated Ca ( 2+) channels. Paracrine and endocrine regulations were analyzed with an emphasis on their effects on a hyperpolarization of membrane potential. This general model simulates and gives insight into the mechanisms of regulation of glucagon secretion under a wide range of experimental conditions. We also reviewed and analyzed dysfunctional mechanisms in α-cells to determine key pharmacological targets for modulating glucagon secretion in type 1 and 2 diabetes.
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Affiliation(s)
- Leonid E Fridlyand
- The Kovler Diabetes Center, Departments of Medicine and Pediatrics, The University of Chicago, Chicago, IL, USA.
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Marroquí L, Batista TM, Gonzalez A, Vieira E, Rafacho A, Colleta SJ, Taboga SR, Boschero AC, Nadal A, Carneiro EM, Quesada I. Functional and structural adaptations in the pancreatic α-cell and changes in glucagon signaling during protein malnutrition. Endocrinology 2012; 153:1663-72. [PMID: 22334714 DOI: 10.1210/en.2011-1623] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Chronic malnutrition leads to multiple changes in β-cell function and peripheral insulin actions to adapt glucose homeostasis to these restricted conditions. However, despite glucose homeostasis also depends on glucagon effects, the role of α-cells in malnutrition is largely unknown. Here, we studied α-cell function and hepatic glucagon signaling in mice fed with low-protein (LP) or normal-protein diet for 8 wk after weaning. Using confocal microscopy, we found that inhibition of Ca²⁺ signaling by glucose was impaired in α-cells of LP mice. Consistent with these findings, the ability of glucose to inhibit glucagon release in isolated islets was also diminished in LP mice. This altered secretion was not related with changes in either glucagon gene expression or glucagon content. A morphometric analysis showed that α-cell mass was significantly increased in malnourished animals, aspect that was probably related with their enhanced plasma glucagon levels. When we analyzed the hepatic function, we observed that the phosphorylation of protein kinase A and cAMP response-binding element protein in response to fasting or exogenous glucagon was impaired in LP mice. Additionally, the up-regulated gene expression in response to fasting observed in the hepatic glucagon receptor as well as several key hepatic enzymes, such as peroxisome proliferator-activated receptor γ, glucose-6-phosphatase, and phosphoenolpyruvate carboxykinase, was altered in malnourished animals. Finally, liver glycogen mobilization in response to fasting and the ability of exogenous glucagon to raise plasma glucose levels were lower in LP mice. Therefore, chronic protein malnutrition leads to several alterations in both the α-cell function and hepatic glucagon signaling.
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Affiliation(s)
- Laura Marroquí
- Instituto de Bioingeniería, Universidad Miguel Hernández, 03202 Elche, Spain
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González-Vélez V, Dupont G, Gil A, González A, Quesada I. Model for glucagon secretion by pancreatic α-cells. PLoS One 2012; 7:e32282. [PMID: 22412861 PMCID: PMC3296707 DOI: 10.1371/journal.pone.0032282] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2011] [Accepted: 01/24/2012] [Indexed: 11/18/2022] Open
Abstract
Glucagon hormone is synthesized and released by pancreatic α-cells, one of the islet-cell types. This hormone, along with insulin, maintains blood glucose levels within the physiological range. Glucose stimulates glucagon release at low concentrations (hypoglycemia). However, the mechanisms involved in this secretion are still not completely clear. Here, using experimental calcium time series obtained in mouse pancreatic islets at low and high glucose conditions, we propose a glucagon secretion model for α-cells. Our model takes into account that the resupply of releasable granules is not only controlled by cytoplasmic , as in other neuroendocrine and endocrine cells, but also by the level of extracellular glucose. We found that, although calcium oscillations are highly variable, the average secretion rates predicted by the model fall into the range of values reported in the literature, for both stimulated and non-stimulated conditions. For low glucose levels, the model predicts that there would be a well-controlled number of releasable granules refilled slowly from a large reserve pool, probably to ensure a secretion rate that could last for several minutes. Studying the α-cell response to the addition of insulin at low glucose, we observe that the presence of insulin reduces glucagon release by decreasing the islet level. This observation is in line with previous work reporting that dynamics, mainly frequency, is altered by insulin [1]. Thus, the present results emphasize the main role played by and glucose in the control of glucagon secretion by α-cells. Our modeling approach also shows that calcium oscillations potentiate glucagon secretion as compared to constant levels of this cellular messenger. Altogether, the model sheds new light on the subcellular mechanisms involved in α-cell exocytosis, and provides a quantitative predictive tool for studying glucagon secretion modulators in physiological and pathological conditions.
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Affiliation(s)
- Virginia González-Vélez
- Departmento Ciencias Básicas, Universidad Autónoma Metropolitana Azcapotzalco, México City, México
| | - Geneviève Dupont
- Unité de Chronobiologie Théorique, Université Libre de Bruxelles, Brussels, Belgium
| | - Amparo Gil
- Departamento Matemática Aplicada y Ciencias de la Computación, Universidad de Cantabria, Santander, Cantabria, Spain
- * E-mail:
| | - Alejandro González
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Instituto de Bioingeniería, Universidad Miguel Hernández, Elche, Spain
| | - Iván Quesada
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Instituto de Bioingeniería, Universidad Miguel Hernández, Elche, Spain
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Lee YH, Magkos F, Mantzoros CS, Kang ES. Effects of leptin and adiponectin on pancreatic β-cell function. Metabolism 2011; 60:1664-72. [PMID: 21632069 DOI: 10.1016/j.metabol.2011.04.008] [Citation(s) in RCA: 104] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/02/2010] [Revised: 03/24/2011] [Accepted: 04/18/2011] [Indexed: 02/09/2023]
Abstract
Leptin and adiponectin are hormones secreted from adipocytes that have important roles in metabolism and energy homeostasis. This review evaluates the effects of leptin and adiponectin on β-cell function by analyzing and compiling results from human clinical trials and epidemiologic studies as well as in vitro and in vivo experiments. Leptin has been shown to inhibit ectopic fat accumulation and thereby prevent β-cell dysfunction and protect the β-cell from cytokine- and fatty acid-induced apoptosis. However, leptin suppresses insulin gene expression and secretion as well as glucose transport into the β-cell. Adiponectin stimulates insulin secretion by enhancing exocytosis of insulin granules and upregulating the expression of the insulin gene; however, this effect depends on the prevailing glucose concentration and status of insulin resistance. In addition, adiponectin has antiapoptotic properties in β-cells. Available evidence concerning the role of these adipokines on insulin secretion, insulin gene expression, and apoptosis is not always entirely consistent; and many fundamental questions remain to be answered by future studies.
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Affiliation(s)
- Yong-ho Lee
- Department of Internal Medicine, Yonsei University College of Medicine, Seoul, South Korea
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Mantzoros CS, Magkos F, Brinkoetter M, Sienkiewicz E, Dardeno TA, Kim SY, Hamnvik OPR, Koniaris A. Leptin in human physiology and pathophysiology. Am J Physiol Endocrinol Metab 2011; 301:E567-84. [PMID: 21791620 PMCID: PMC3191548 DOI: 10.1152/ajpendo.00315.2011] [Citation(s) in RCA: 379] [Impact Index Per Article: 29.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Leptin, discovered through positional cloning 15 years ago, is an adipocyte-secreted hormone with pleiotropic effects in the physiology and pathophysiology of energy homeostasis, endocrinology, and metabolism. Studies in vitro and in animal models highlight the potential for leptin to regulate a number of physiological functions. Available evidence from human studies indicates that leptin has a mainly permissive role, with leptin administration being effective in states of leptin deficiency, less effective in states of leptin adequacy, and largely ineffective in states of leptin excess. Results from interventional studies in humans demonstrate that leptin administration in subjects with congenital complete leptin deficiency or subjects with partial leptin deficiency (subjects with lipoatrophy, congenital or related to HIV infection, and women with hypothalamic amenorrhea) reverses the energy homeostasis and neuroendocrine and metabolic abnormalities associated with these conditions. More specifically, in women with hypothalamic amenorrhea, leptin helps restore abnormalities in hypothalamic-pituitary-peripheral axes including the gonadal, thyroid, growth hormone, and to a lesser extent adrenal axes. Furthermore, leptin results in resumption of menses in the majority of these subjects and, in the long term, may increase bone mineral content and density, especially at the lumbar spine. In patients with congenital or HIV-related lipoatrophy, leptin treatment is also associated with improvements in insulin sensitivity and lipid profile, concomitant with reduced visceral and ectopic fat deposition. In contrast, leptin's effects are largely absent in the obese hyperleptinemic state, probably due to leptin resistance or tolerance. Hence, another emerging area of research pertains to the discovery and/or usefulness of leptin sensitizers. Results from ongoing studies are expected to further increase our understanding of the role of leptin and the potential clinical applications of leptin or its analogs in human therapeutics.
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Affiliation(s)
- Christos S Mantzoros
- Division of Endocrinology, Diabetes and Metabolism, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA.
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Denroche HC, Levi J, Wideman RD, Sequeira RM, Huynh FK, Covey SD, Kieffer TJ. Leptin therapy reverses hyperglycemia in mice with streptozotocin-induced diabetes, independent of hepatic leptin signaling. Diabetes 2011; 60:1414-23. [PMID: 21464443 PMCID: PMC3292314 DOI: 10.2337/db10-0958] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
OBJECTIVE Leptin therapy has been found to reverse hyperglycemia and prevent mortality in several rodent models of type 1 diabetes. Yet the mechanism of leptin-mediated reversal of hyperglycemia has not been fully defined. The liver is a key organ regulating glucose metabolism and is also a target of leptin action. Thus we hypothesized that exogenous leptin administered to mice with streptozotocin (STZ)-induced diabetes reverses hyperglycemia through direct action on hepatocytes. RESEARCH DESIGN AND METHODS After the induction of diabetes in mice with a high dose of STZ, recombinant mouse leptin was delivered at a supraphysiological dose for 14 days by an osmotic pump implant. We characterized the effect of leptin administration in C57Bl/6J mice with STZ-induced diabetes and then examined whether leptin therapy could reverse STZ-induced hyperglycemia in mice in which hepatic leptin signaling was specifically disrupted. RESULTS Hyperleptinemia reversed hyperglycemia and hyperketonemia in diabetic C57Bl/6J mice and dramatically improved glucose tolerance. These effects were associated with reduced plasma glucagon and growth hormone levels and dramatically enhanced insulin sensitivity, without changes in glucose uptake by skeletal muscle. Leptin therapy also ameliorated STZ-induced hyperglycemia and hyperketonemia in mice with disrupted hepatic leptin signaling to a similar extent as observed in wild-type littermates with STZ-induced diabetes. CONCLUSIONS These observations reveal that hyperleptinemia reverses the symptoms of STZ-induced diabetes in mice and that this action does not require direct leptin signaling in the liver.
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Affiliation(s)
- Heather C. Denroche
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Jasna Levi
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Rhonda D. Wideman
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Roveena M. Sequeira
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Frank K. Huynh
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Scott D. Covey
- Department of Biochemistry and Molecular Biology, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Timothy J. Kieffer
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
- Department of Surgery, University of British Columbia, Vancouver, British Columbia, Canada
- Corresponding author: Timothy J. Kieffer,
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Marroquí L, Vieira E, Gonzalez A, Nadal A, Quesada I. Leptin downregulates expression of the gene encoding glucagon in alphaTC1-9 cells and mouse islets. Diabetologia 2011; 54:843-51. [PMID: 21234744 DOI: 10.1007/s00125-010-2024-1] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/31/2010] [Accepted: 11/19/2010] [Indexed: 12/20/2022]
Abstract
AIMS/HYPOTHESIS Leptin, released by adipocytes, can modulate glucose homeostasis through direct actions on pancreatic alpha and beta cells. Although this hormone rapidly regulates alpha cell exocytosis, its long-term effects on glucagon gene expression are currently unknown. METHODS We analysed glucagon mRNA levels and protein content in alphaTC1-9 cells and isolated mouse islets cultured with leptin, as well as in islets from mice treated in vivo with leptin. We also studied the involvement of the signal transducers and activators of transcription (STAT) pathway by western blot, immunofluorescence and interference RNA. RESULTS Leptin incubation (0.0625-18.75 nmol/l) for 24 h inhibited glucagon gene expression in alphaTC1-9 cells. This inhibitory effect was also observed in isolated mouse islets cultured with leptin, as well as in islets from mice treated with leptin for 5 days. In contrast, no changes were detected in islets from db/db mice, which lack leptin receptors. Leptin treatment also reduced the glucagon protein content in alphaTC1-9 cells and mouse islets. Moreover, leptin induced phosphorylation of STAT3 and its translocation to the nucleus, which was confirmed by western blot analysis in alphaTC1-9 cells and by immunofluorescence in isolated alpha cells. Interestingly, the effect of leptin on glucagon mRNA levels was significantly reduced by Stat3 knockdown. In contrast, pharmacological inhibition of the phosphoinositide 3-kinase pathway did not affect leptin actions. CONCLUSIONS/INTERPRETATION Our results demonstrate that leptin can regulate glucagon gene expression in alpha cells via a STAT3 pathway, and are important for understanding the role of leptin in glucose homeostasis.
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Affiliation(s)
- L Marroquí
- Instituto de Bioingeniería, Universidad Miguel Hernandez, Avenida de la Universidad, 03202 Elche, Spain
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Margoni A, Perrea DN, Vlachos I, Prokopaki G, Pantopoulou A, Fotis L, Kostaki M, Papavassiliou AG. Serum leptin, adiponectin and tumor necrosis factor-α in hyperlipidemic rats with/without concomitant diabetes mellitus. Mol Med 2010; 17:36-40. [PMID: 20838752 DOI: 10.2119/molmed.2010.00167] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2010] [Accepted: 09/05/2010] [Indexed: 12/11/2022] Open
Abstract
We compared the lipid profiles and serum levels of leptin, adiponectin and tumor necrosis factor-α (TNF-α) in rats with/without hyperlipidemia and with/without concomitant diabetes mellitus. Forty 10-wk-old male Wistar rats were divided into four groups. Groups A and C received standard food for 12 wks. Groups B and D received a high-fat diet enriched with 2% additional cholesterol. Moreover, insulin-deficient (type I) diabetes mellitus was induced in rats in groups C and D with intraperitoneal injections of streptozotocin. Fasting serum leptin levels were decreased in diabetic groups (groups C and D) compared with controls. Fasting serum adiponectin levels were decreased in groups C and D compared with group A. Serum TNF-α levels were augmented in groups B and D, those fed with an atherogenic diet. By contrast, TNF-α levels were decreased in group C. Our data suggest that serum leptin, adiponectin and TNF-α levels may serve as markers of obesity and type I diabetes mellitus.
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Affiliation(s)
- Angeliki Margoni
- Department of Biological Chemistry, University of Athens Medical School, Athens, Greece
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Alonso-Magdalena P, Vieira E, Soriano S, Menes L, Burks D, Quesada I, Nadal A. Bisphenol A exposure during pregnancy disrupts glucose homeostasis in mothers and adult male offspring. ENVIRONMENTAL HEALTH PERSPECTIVES 2010; 118:1243-50. [PMID: 20488778 PMCID: PMC2944084 DOI: 10.1289/ehp.1001993] [Citation(s) in RCA: 330] [Impact Index Per Article: 23.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2010] [Accepted: 05/07/2010] [Indexed: 05/18/2023]
Abstract
BACKGROUND Bisphenol A (BPA) is a widespread endocrine-disrupting chemical used as the base compound in the manufacture of polycarbonate plastics. In humans, epidemiological evidence has associated BPA exposure in adults with higher risk of type 2 diabetes and heart disease. OBJECTIVE We examined the action of environmentally relevant doses of BPA on glucose metabolism in mice during pregnancy and the impact of BPA exposure on these females later in life. We also investigated the consequences of in utero exposure to BPA on metabolic parameters and pancreatic function in offspring. METHODS Pregnant mice were treated with either vehicle or BPA (10 or 100 microg/kg/day) during days 9-16 of gestation. Glucose metabolism experiments were performed on pregnant mice and their offspring. RESULTS BPA exposure aggravated the insulin resistance produced during pregnancy and was associated with decreased glucose tolerance and increased plasma insulin, triglyceride, and leptin concentrations relative to controls. Insulin-stimulated Akt phosphorylation was reduced in skeletal muscle and liver of BPA-treated pregnant mice relative to controls. BPA exposure during gestation had long-term consequences for mothers: 4 months post-partum, treated females weighed more than untreated females and had higher plasma insulin, leptin, triglyceride, and glycerol levels and greater insulin resistance. At 6 months of age, male offspring exposed in utero had reduced glucose tolerance, increased insulin resistance, and altered blood parameters compared with offspring of untreated mothers. The islets of Langerhans from male offspring presented altered Ca2+ signaling and insulin secretion. BrdU (bromodeoxyuridine) incorporation into insulin-producing cells was reduced in the male progeny, yet beta-cell mass was unchanged. CONCLUSIONS Our findings suggest that BPA may contribute to metabolic disorders relevant to glucose homeostasis and that BPA may be a risk factor for diabetes.
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Affiliation(s)
- Paloma Alonso-Magdalena
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM) and
- Instituto de Bioingeniería, Universidad Miguel Hernández de Elche, Elche, Spain
| | - Elaine Vieira
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM) and
- Instituto de Bioingeniería, Universidad Miguel Hernández de Elche, Elche, Spain
| | - Sergi Soriano
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM) and
- Instituto de Bioingeniería, Universidad Miguel Hernández de Elche, Elche, Spain
| | - Lorena Menes
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM) and
- Instituto Principe Felipe, Consejo Superior de Investigaciones Científicas, Valencia, Spain
| | - Deborah Burks
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM) and
- Instituto Principe Felipe, Consejo Superior de Investigaciones Científicas, Valencia, Spain
| | - Ivan Quesada
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM) and
- Instituto de Bioingeniería, Universidad Miguel Hernández de Elche, Elche, Spain
| | - Angel Nadal
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM) and
- Instituto de Bioingeniería, Universidad Miguel Hernández de Elche, Elche, Spain
- Address correspondence to A. Nadal, Instituto de Bioingeniería and CIBERDEM, Universidad Miguel Hernandez de Elche, Avenida de la Universidad s/n, 03202 Elche, Spain. Telephone: 34-96-522-2002. Fax: 34-96-522-2033. E-mail:
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Soriano S, Gonzalez A, Marroquí L, Tudurí E, Vieira E, Amaral AG, Batista TM, Rafacho A, Boschero AC, Nadal A, Carneiro EM, Quesada I. Reduced insulin secretion in protein malnourished mice is associated with multiple changes in the beta-cell stimulus-secretion coupling. Endocrinology 2010; 151:3543-54. [PMID: 20555033 DOI: 10.1210/en.2010-0008] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The mechanism by which protein malnutrition impairs glucose-stimulated insulin secretion in the pancreatic beta-cell is not completely known but may be related to alterations in the signaling events involved in insulin release. Here, we aimed to study the stimulus-secretion coupling of beta-cells from mice fed with low-protein (LP) diet or normal-protein (NP) diet for 8 wk after weaning. Patch-clamp measurements in isolated cells showed that beta-cells from LP mice had a resting membrane potential that was more hyperpolarized than controls. Additionally, depolarization and generation of action potentials in response to stimulatory glucose concentrations were also impaired in beta-cells of LP mice. All these alterations in the LP group were most likely attributed to higher ATP-dependent K(+) (K(ATP)) channel activity in resting conditions and lower efficiency of glucose to induce the closure of these channels. Moreover, a Western blot analysis revealed higher protein levels of the sulphonylurea receptor of the K(ATP) channel in islets of LP mice. Because beta-cell Ca(2+) signals depend on electrical activity, intracellular Ca(2+) oscillations were measured by fluorescence microscopy in intact islets, indicating a lower response to glucose in the LP group. Finally, cell-to-cell synchrony of Ca(2+) signals was analyzed by confocal microscopy. Islets from LP mice exhibited a decreased level of coupling among beta-cells, which was probably due to the low expression levels of connexin 36. Therefore, low-protein diet leads to several alterations in the stimulus-secretion coupling of pancreatic beta-cells that might explain the diminished insulin secretion in response to glucose in this malnutrition state.
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Affiliation(s)
- Sergi Soriano
- Instituto de Bioingeniería and CIBER de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Universidad Miguel Hernández, 03202 Elche, Spain.
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Singer K, Pietropaolo M, Menon RK. Improving type 1 diabetes control with leptin--is this a game-changer? Pediatr Diabetes 2010; 11:216-7. [PMID: 20618743 DOI: 10.1111/j.1399-5448.2010.00687.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Affiliation(s)
- Kanakadurga Singer
- Department of Pediatrics, University of Michigan Medical School, MI, USA
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