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Hall LG, Thyfault JP, Johnson JD. Exercise and inactivity as modifiers of β cell function and type 2 diabetes risk. J Appl Physiol (1985) 2023; 134:823-839. [PMID: 36759159 PMCID: PMC10042613 DOI: 10.1152/japplphysiol.00472.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2022] [Revised: 01/31/2023] [Accepted: 01/31/2023] [Indexed: 02/11/2023] Open
Abstract
Exercise and regular physical activity are beneficial for the prevention and management of metabolic diseases such as obesity and type 2 diabetes, whereas exercise cessation, defined as deconditioning from regular exercise or physical activity that has lasted for a period of months to years, can lead to metabolic derangements that drive disease. Adaptations to the insulin-secreting pancreatic β-cells are an important benefit of exercise, whereas less is known about how exercise cessation affects these cells. Our aim is to review the impact that exercise and exercise cessation have on β-cell function, with a focus on the evidence from studies examining glucose-stimulated insulin secretion (GSIS) using gold-standard techniques. Potential mechanisms by which the β-cell adapts to exercise, including exerkine and incretin signaling, autonomic nervous system signaling, and changes in insulin clearance, will also be explored. We will highlight areas for future research.
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Affiliation(s)
- Liam G Hall
- Department of Cellular and Physiological Sciences, Life Sciences Institute, The University of British Columbia, Vancouver, British Columbia, Canada
| | - John P Thyfault
- Department of Cell Biology and Physiology, University of Kansas Medical Center, Kansas City, Kansas, United States
- Division of Endocrinology and Metabolism, Department of Internal Medicine, University of Kansas Medical Center, Kansas City, Kansas, United States
- KU Diabetes Institute, University of Kansas Medical Center, Kansas City, Kansas, United States
| | - James D Johnson
- Department of Cellular and Physiological Sciences, Life Sciences Institute, The University of British Columbia, Vancouver, British Columbia, Canada
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2
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Mirzadeh Z, Faber CL, Schwartz MW. Central Nervous System Control of Glucose Homeostasis: A Therapeutic Target for Type 2 Diabetes? Annu Rev Pharmacol Toxicol 2022; 62:55-84. [PMID: 34990204 PMCID: PMC8900291 DOI: 10.1146/annurev-pharmtox-052220-010446] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Historically, pancreatic islet beta cells have been viewed as principal regulators of glycemia, with type 2 diabetes (T2D) resulting when insulin secretion fails to compensate for peripheral tissue insulin resistance. However, glycemia is also regulated by insulin-independent mechanisms that are dysregulated in T2D. Based on evidence supporting its role both in adaptive coupling of insulin secretion to changes in insulin sensitivity and in the regulation of insulin-independent glucose disposal, the central nervous system (CNS) has emerged as a fundamental player in glucose homeostasis. Here, we review and expand upon an integrative model wherein the CNS, together with the islet, establishes and maintains the defended level of glycemia. We discuss the implications of this model for understanding both normal glucose homeostasis and T2D pathogenesis and highlight centrally targeted therapeutic approaches with the potential to restore normoglycemia to patients with T2D.
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Affiliation(s)
- Zaman Mirzadeh
- Ivy Brain Tumor Center, Department of Neurosurgery, Barrow Neurological Institute, Phoenix, Arizona 85013, USA;
| | - Chelsea L Faber
- Ivy Brain Tumor Center, Department of Neurosurgery, Barrow Neurological Institute, Phoenix, Arizona 85013, USA;
- UW Medicine Diabetes Institute, Department of Medicine, University of Washington, Seattle, Washington 98109, USA;
| | - Michael W Schwartz
- UW Medicine Diabetes Institute, Department of Medicine, University of Washington, Seattle, Washington 98109, USA;
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3
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Janssen JAMJL. Hyperinsulinemia and Its Pivotal Role in Aging, Obesity, Type 2 Diabetes, Cardiovascular Disease and Cancer. Int J Mol Sci 2021; 22:ijms22157797. [PMID: 34360563 PMCID: PMC8345990 DOI: 10.3390/ijms22157797] [Citation(s) in RCA: 73] [Impact Index Per Article: 24.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Revised: 07/11/2021] [Accepted: 07/13/2021] [Indexed: 01/10/2023] Open
Abstract
For many years, the dogma has been that insulin resistance precedes the development of hyperinsulinemia. However, recent data suggest a reverse order and place hyperinsulinemia mechanistically upstream of insulin resistance. Genetic background, consumption of the “modern” Western diet and over-nutrition may increase insulin secretion, decrease insulin pulses and/or reduce hepatic insulin clearance, thereby causing hyperinsulinemia. Hyperinsulinemia disturbs the balance of the insulin–GH–IGF axis and shifts the insulin : GH ratio towards insulin and away from GH. This insulin–GH shift promotes energy storage and lipid synthesis and hinders lipid breakdown, resulting in obesity due to higher fat accumulation and lower energy expenditure. Hyperinsulinemia is an important etiological factor in the development of metabolic syndrome, type 2 diabetes, cardiovascular disease, cancer and premature mortality. It has been further hypothesized that nutritionally driven insulin exposure controls the rate of mammalian aging. Interventions that normalize/reduce plasma insulin concentrations might play a key role in the prevention and treatment of age-related decline, obesity, type 2 diabetes, cardiovascular disease and cancer. Caloric restriction, increasing hepatic insulin clearance and maximizing insulin sensitivity are at present the three main strategies available for managing hyperinsulinemia. This may slow down age-related physiological decline and prevent age-related diseases. Drugs that reduce insulin (hyper) secretion, normalize pulsatile insulin secretion and/or increase hepatic insulin clearance may also have the potential to prevent or delay the progression of hyperinsulinemia-mediated diseases. Future research should focus on new strategies to minimize hyperinsulinemia at an early stage, aiming at successfully preventing and treating hyperinsulinemia-mediated diseases.
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Affiliation(s)
- Joseph A M J L Janssen
- Department of internal Medicine, Division of Endocrinology, Erasmus Medical Center, 40, 3015 GD Rotterdam, The Netherlands
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4
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Zhang AM, Wellberg EA, Kopp JL, Johnson JD. Hyperinsulinemia in Obesity, Inflammation, and Cancer. Diabetes Metab J 2021; 45:285-311. [PMID: 33775061 PMCID: PMC8164941 DOI: 10.4093/dmj.2020.0250] [Citation(s) in RCA: 79] [Impact Index Per Article: 26.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Accepted: 12/23/2020] [Indexed: 12/13/2022] Open
Abstract
The relative insufficiency of insulin secretion and/or insulin action causes diabetes. However, obesity and type 2 diabetes mellitus can be associated with an absolute increase in circulating insulin, a state known as hyperinsulinemia. Studies are beginning to elucidate the cause-effect relationships between hyperinsulinemia and numerous consequences of metabolic dysfunctions. Here, we review recent evidence demonstrating that hyperinsulinemia may play a role in inflammation, aging and development of cancers. In this review, we will focus on the consequences and mechanisms of excess insulin production and action, placing recent findings that have challenged dogma in the context of the existing body of literature. Where relevant, we elaborate on the role of specific signal transduction components in the actions of insulin and consequences of chronic hyperinsulinemia. By discussing the involvement of hyperinsulinemia in various metabolic and other chronic diseases, we may identify more effective therapeutics or lifestyle interventions for preventing or treating obesity, diabetes and cancer. We also seek to identify pertinent questions that are ripe for future investigation.
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Affiliation(s)
- Anni M.Y. Zhang
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, BC, Canada
| | - Elizabeth A. Wellberg
- Department of Pathology, University of Oklahoma Health Sciences Center, Stephenson Cancer Center, Harold Hamm Diabetes Center, Oklahoma City, OK, USA
| | - Janel L. Kopp
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, BC, Canada
| | - James D. Johnson
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, BC, Canada
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5
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Wu D, Wong CK, Han JM, Orban PC, Huang Q, Gillies J, Mojibian M, Gibson WT, Levings MK. T reg-specific insulin receptor deletion prevents diet-induced and age-associated metabolic syndrome. J Exp Med 2021; 217:151826. [PMID: 32478834 PMCID: PMC7398165 DOI: 10.1084/jem.20191542] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2019] [Revised: 12/02/2019] [Accepted: 04/24/2020] [Indexed: 12/12/2022] Open
Abstract
Adipose tissue (AT) regulatory T cells (T regs) control inflammation and metabolism. Diet-induced obesity causes hyperinsulinemia and diminishes visceral AT (VAT) T reg number and function, but whether these two phenomena were mechanistically linked was unknown. Using a T reg–specific insulin receptor (Insr) deletion model, we found that diet-induced T reg dysfunction is driven by T reg–intrinsic insulin signaling. Compared with Foxp3cre mice, after 13 wk of high-fat diet, Foxp3creInsrfl/fl mice exhibited improved glucose tolerance and insulin sensitivity, effects associated with lower AT inflammation and increased numbers of ST2+ T regs in brown AT, but not VAT. Similarly, Foxp3creInsrfl/fl mice were protected from the metabolic effects of aging, but surprisingly had reduced VAT T regs and increased VAT inflammation compared with Foxp3cre mice. Thus, in both diet- and aging-associated hyperinsulinemia, excessive Insr signaling in T regs leads to undesirable metabolic outcomes. Ablation of Insr signaling in T regs represents a novel approach to mitigate the detrimental effects of hyperinsulinemia on immunoregulation of metabolic syndrome.
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Affiliation(s)
- Dan Wu
- Department of Surgery, University of British Columbia, Vancouver, Canada.,BC Children's Hospital Research Institute, Vancouver, Canada
| | - Chi Kin Wong
- BC Children's Hospital Research Institute, Vancouver, Canada.,Department of Medical Genetics, University of British Columbia, Vancouver, Canada
| | - Jonathan M Han
- Department of Surgery, University of British Columbia, Vancouver, Canada.,BC Children's Hospital Research Institute, Vancouver, Canada
| | - Paul C Orban
- Department of Surgery, University of British Columbia, Vancouver, Canada.,BC Children's Hospital Research Institute, Vancouver, Canada
| | - Qing Huang
- Department of Surgery, University of British Columbia, Vancouver, Canada.,BC Children's Hospital Research Institute, Vancouver, Canada
| | - Jana Gillies
- Department of Surgery, University of British Columbia, Vancouver, Canada.,BC Children's Hospital Research Institute, Vancouver, Canada
| | - Majid Mojibian
- Department of Surgery, University of British Columbia, Vancouver, Canada.,BC Children's Hospital Research Institute, Vancouver, Canada
| | - William T Gibson
- BC Children's Hospital Research Institute, Vancouver, Canada.,Department of Medical Genetics, University of British Columbia, Vancouver, Canada
| | - Megan K Levings
- Department of Surgery, University of British Columbia, Vancouver, Canada.,BC Children's Hospital Research Institute, Vancouver, Canada.,School of Biomedical Engineering, University of British Columbia, Vancouver, Canada
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6
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Xu C, Zhou G, Zhao M, Zhang X, Fang L, Guan Q, Zhang H, Gao L, Zhang T, Zhao J. Bidirectional temporal relationship between obesity and hyperinsulinemia: longitudinal observation from a Chinese cohort. BMJ Open Diabetes Res Care 2021; 9:9/1/e002059. [PMID: 33632707 PMCID: PMC7908912 DOI: 10.1136/bmjdrc-2020-002059] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/05/2020] [Revised: 01/28/2021] [Accepted: 02/07/2021] [Indexed: 11/21/2022] Open
Abstract
INTRODUCTION Although obesity and hyperinsulinemia are closely intercorrelated, their temporal sequence is still uncertain. This study aims to investigate the temporal relationship patterns between obesity measures and hyperinsulinemia in Chinese adults. RESEARCH DESIGN AND METHODS The longitudinal cohort consisted of 2493 participants (860 males and 1633 female, mean age 56.71 years at follow-up) for whom measurements of obesity and hyperinsulinemia measures were collected twice between 2011 and 2014, with an average follow-up time of 3 years. Cross-lagged panel analysis was used to examine the temporal relationship between obesity measures (body mass index (BMI); waist circumference (WC); hip circumference (HC); waist-to-hip ratio (WHR)) and hyperinsulinemia (insulin, homeostasis model assessment of insulin resistance (HOMA-IR), or homeostasis model assessment of beta cell function (HOMA-%β)). RESULTS After the adjustment of age, sex, smoking, drinking and follow-up years, in the BMI-insulin model, the path coefficient (β2=0.229; p<0.001) of baseline BMI to follow-up insulin was significantly greater than the path coefficient (β1=0.073; p<0.001) of baseline insulin to follow-up BMI (p<0.001 for β2>β1). In the WHR-insulin model, the path coefficient (β1=0.152; p<0.001) of baseline insulin to follow-up WHR was significantly greater than the path coefficient (β2=0.077; p<0.001) of baseline WHR to follow-up insulin (p=0.007 for β1>β2). In the WC/HC-insulin model, the path coefficients of baseline insulin to follow-up WC or HC (β1s) were also greater than the path coefficients of baseline WC or HC to follow-up insulin (β2s), but the difference between β1s and β2s were not significant. The similar temporal patterns were founded between obesity measures with HOMA-IR or HOMA-%β. CONCLUSIONS These findings indicate that there is a bidirectional relationship between obesity and hyperinsulinemia, and abdominal obesity measures are more sensitive to hyperinsulinemia measures than BMI.
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Affiliation(s)
- Chao Xu
- Department of Endocrinology and Metabolism, Shandong Provincial Hospital, Cheeloo College of Medicine, Shandong University, Jinan, China
- Institute of Endocrinology, Shandong Academy of Clinical Medicine, Jinan, China
- Shandong Clinical Medical Center of Endocrinology and Metabolism, Jinan, China
| | - Guangshuai Zhou
- Department of Biostatistics, School of Public Health, Cheeloo College of Medicine, Shandong University, Jinan, China
- Department of Quality Management Office, Zibo Central Hospital, Zibo, China
| | - Meng Zhao
- Department of Endocrinology and Metabolism, Shandong Provincial Hospital, Cheeloo College of Medicine, Shandong University, Jinan, China
- Institute of Endocrinology, Shandong Academy of Clinical Medicine, Jinan, China
- Shandong Clinical Medical Center of Endocrinology and Metabolism, Jinan, China
| | - Xu Zhang
- Department of Endocrinology and Metabolism, Shandong Provincial Hospital, Cheeloo College of Medicine, Shandong University, Jinan, China
- Institute of Endocrinology, Shandong Academy of Clinical Medicine, Jinan, China
- Shandong Clinical Medical Center of Endocrinology and Metabolism, Jinan, China
| | - Li Fang
- Department of Endocrinology and Metabolism, Shandong Provincial Hospital, Cheeloo College of Medicine, Shandong University, Jinan, China
- Institute of Endocrinology, Shandong Academy of Clinical Medicine, Jinan, China
- Shandong Clinical Medical Center of Endocrinology and Metabolism, Jinan, China
| | - Qingbo Guan
- Department of Endocrinology and Metabolism, Shandong Provincial Hospital, Cheeloo College of Medicine, Shandong University, Jinan, China
- Institute of Endocrinology, Shandong Academy of Clinical Medicine, Jinan, China
- Shandong Clinical Medical Center of Endocrinology and Metabolism, Jinan, China
| | - Haiqing Zhang
- Department of Endocrinology and Metabolism, Shandong Provincial Hospital, Cheeloo College of Medicine, Shandong University, Jinan, China
- Institute of Endocrinology, Shandong Academy of Clinical Medicine, Jinan, China
- Shandong Clinical Medical Center of Endocrinology and Metabolism, Jinan, China
| | - Ling Gao
- Institute of Endocrinology, Shandong Academy of Clinical Medicine, Jinan, China
- Shandong Clinical Medical Center of Endocrinology and Metabolism, Jinan, China
- Scientific Center, Shandong Provincial Hospital, Cheeloo College of Medicine, Shandong University, Jinan, China
| | - Tao Zhang
- Department of Biostatistics, School of Public Health, Cheeloo College of Medicine, Shandong University, Jinan, China
| | - Jiajun Zhao
- Department of Endocrinology and Metabolism, Shandong Provincial Hospital, Cheeloo College of Medicine, Shandong University, Jinan, China
- Institute of Endocrinology, Shandong Academy of Clinical Medicine, Jinan, China
- Shandong Clinical Medical Center of Endocrinology and Metabolism, Jinan, China
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7
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Abstract
The current paradigm of type 2 diabetes (T2D) is gluco-centric, being exclusively categorized by glycemic characteristics. The gluco-centric paradigm views hyperglycemia as the primary target, being driven by resistance to insulin combined with progressive beta cells failure, and considers glycemic control its ultimate treatment goal. Most importantly, the gluco-centric paradigm considers the non-glycemic diseases associated with T2D, e.g., obesity, dyslipidemia, hypertension, macrovascular disease, microvascular disease and fatty liver as 'risk factors' and/or 'outcomes' and/or 'comorbidities', rather than primary inherent disease aspects of T2D. That is in spite of their high prevalence (60-90%) and major role in profiling T2D morbidity and mortality. Moreover, the gluco-centric paradigm fails to realize that the non-glycemic diseases of T2D are driven by insulin and, except for glycemic control, response to insulin in T2D is essentially the rule rather than the exception. Failure of the gluco-centric paradigm to offer an exhaustive unifying view of the glycemic and non-glycemic diseases of T2D may have contributed to T2D being still an unmet need. An mTORC1-centric paradigm maintains that hyperactive mTORC1 drives the glycemic and non-glycemic disease aspects of T2D. Hyperactive mTORC1 is proposed to act as double-edged agent, namely, to interfere with glycemic control by disrupting the insulin receptor-Akt transduction pathway, while concomitantly driving the non-glycemic diseases of T2D. The mTORC1-centric paradigm may offer a novel perspective for T2D in terms of pathogenesis, clinical focus and treatment strategy.
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Affiliation(s)
- Jacob Bar-Tana
- Hebrew University Medical School, 91120, Jerusalem, Israel.
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8
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da Silva Rosa SC, Nayak N, Caymo AM, Gordon JW. Mechanisms of muscle insulin resistance and the cross-talk with liver and adipose tissue. Physiol Rep 2020; 8:e14607. [PMID: 33038072 PMCID: PMC7547588 DOI: 10.14814/phy2.14607] [Citation(s) in RCA: 58] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2020] [Revised: 09/18/2020] [Accepted: 09/19/2020] [Indexed: 12/18/2022] Open
Abstract
Insulin resistance is a metabolic disorder affecting multiple tissues and is a precursor event to type 2 diabetes (T2D). As T2D affects over 425 million people globally, there is an imperative need for research into insulin resistance to better understand the underlying mechanisms. The proposed mechanisms involved in insulin resistance include both whole body aspects, such as inflammation and metabolic inflexibility; as well as cellular phenomena, such as lipotoxicity, ER stress, and mitochondrial dysfunction. Despite numerous studies emphasizing the role of lipotoxicity in the pathogenesis of insulin resistance, an understanding of the interplay between tissues and these proposed mechanisms is still emerging. Furthermore, the tissue-specific and unique responses each of the three major insulin target tissues and how each interconnect to regulate the whole body insulin response has become a new priority in metabolic research. With an emphasis on skeletal muscle, this mini-review highlights key similarities and differences in insulin signaling and resistance between different target-tissues, and presents the latest findings related to how these tissues communicate to control whole body metabolism.
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Affiliation(s)
- Simone C. da Silva Rosa
- Department of Human Anatomy and Cell ScienceUniversity of ManitobaWinnipegCanada
- The Diabetes Research Envisioned and Accomplished in Manitoba (DREAM) ThemeUniversity of ManitobaWinnipegCanada
- Children’s Hospital Research Institute of Manitoba (CHRIM)University of ManitobaWinnipegCanada
| | - Nichole Nayak
- The Diabetes Research Envisioned and Accomplished in Manitoba (DREAM) ThemeUniversity of ManitobaWinnipegCanada
- Children’s Hospital Research Institute of Manitoba (CHRIM)University of ManitobaWinnipegCanada
- College of NursingUniversity of ManitobaWinnipegCanada
| | - Andrei Miguel Caymo
- The Diabetes Research Envisioned and Accomplished in Manitoba (DREAM) ThemeUniversity of ManitobaWinnipegCanada
- Children’s Hospital Research Institute of Manitoba (CHRIM)University of ManitobaWinnipegCanada
| | - Joseph W. Gordon
- Department of Human Anatomy and Cell ScienceUniversity of ManitobaWinnipegCanada
- The Diabetes Research Envisioned and Accomplished in Manitoba (DREAM) ThemeUniversity of ManitobaWinnipegCanada
- Children’s Hospital Research Institute of Manitoba (CHRIM)University of ManitobaWinnipegCanada
- College of NursingUniversity of ManitobaWinnipegCanada
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9
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Esser N, Utzschneider KM, Kahn SE. Early beta cell dysfunction vs insulin hypersecretion as the primary event in the pathogenesis of dysglycaemia. Diabetologia 2020; 63:2007-2021. [PMID: 32894311 DOI: 10.1007/s00125-020-05245-x] [Citation(s) in RCA: 87] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Accepted: 07/07/2020] [Indexed: 12/12/2022]
Abstract
Obesity and insulin resistance are associated with the development of type 2 diabetes. It is well accepted that beta cell dysfunction is required for hyperglycaemia to occur. The prevailing view is that, in the presence of insulin resistance, beta cell dysfunction that occurs early in the course of the disease process is the critical abnormality. An alternative model has been proposed in which primary beta cell overstimulation results in insulin hypersecretion that then leads to the development of obesity and insulin resistance, and ultimately to beta cell exhaustion. In this review, data from preclinical and clinical studies, including intervention studies, are discussed in the context of these models. The preponderance of the data supports the view that an early beta cell functional defect is the more likely mechanism underlying the pathogenesis of hyperglycaemia in the majority of individuals who develop type 2 diabetes. Graphical abstract.
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Affiliation(s)
- Nathalie Esser
- Veterans Affairs Puget Sound Health Care System, 1660 South Columbian Way (151), Seattle, WA, 98108, USA
- Division of Metabolism, Endocrinology and Nutrition, Department of Medicine, University of Washington, Seattle, WA, USA
| | - Kristina M Utzschneider
- Veterans Affairs Puget Sound Health Care System, 1660 South Columbian Way (151), Seattle, WA, 98108, USA
- Division of Metabolism, Endocrinology and Nutrition, Department of Medicine, University of Washington, Seattle, WA, USA
| | - Steven E Kahn
- Veterans Affairs Puget Sound Health Care System, 1660 South Columbian Way (151), Seattle, WA, 98108, USA.
- Division of Metabolism, Endocrinology and Nutrition, Department of Medicine, University of Washington, Seattle, WA, USA.
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10
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Abstract
BACKGROUND Insulin shares a limited physiological concentration range with other endocrine hormones. Not only too low, but also too high systemic insulin levels are detrimental for body functions. MAIN BODY The physiological function and clinical relevance of insulin are usually seen in association with its role in maintaining glucose homeostasis. However, insulin is an anabolic hormone which stimulates a large number of cellular responses. Not only too low, but also excess insulin concentrations are detrimental to the physiological balance. Although the glucoregulatory activity of insulin is mitigated during hyperinsulinemia by dampening the efficiency of insulin signaling ("insulin resistance"), this is not the case for most other hormonal actions of insulin, including the promotion of protein synthesis, de novo lipogenesis, and cell proliferation; the inhibition of lipolysis, of autophagy-dependent cellular turnover, and of nuclear factor E2-related factor-2 (Nrf2)-dependent antioxidative; and other defense mechanisms. Hence, there is no general insulin resistance but selective impairment of insulin signaling which causes less glucose uptake from the blood and reduced activation of endothelial NO synthase (eNOS). Because of the largely unrestricted insulin signaling, hyperinsulinemia increases the risk of obesity, type 2 diabetes, and cardiovascular disease and decreases health span and life expectancy. In epidemiological studies, high-dose insulin therapy is associated with an increased risk of cardiovascular disease. Randomized controlled trials of insulin treatment did not observe any effect on disease risk, but these trials only studied low insulin doses up to 40 IU/day. Proof for a causal link between elevated insulin levels and cardiovascular disease risk comes from Mendelian randomization studies comparing individuals with genetically controlled low or high insulin production. CONCLUSIONS The detrimental actions of prolonged high insulin concentrations, seen also in cell culture, argue in favor of a lifestyle that limits circadian insulin levels. The health risks associated with hyperinsulinemia may have implications for treatment regimens used in type 2 diabetes.
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11
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Exploring Therapeutic Targets to Reverse or Prevent the Transition from Metabolically Healthy to Unhealthy Obesity. Cells 2020; 9:cells9071596. [PMID: 32630256 PMCID: PMC7407965 DOI: 10.3390/cells9071596] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Revised: 06/24/2020] [Accepted: 06/30/2020] [Indexed: 12/14/2022] Open
Abstract
The prevalence of obesity and obesity-related metabolic comorbidities are rapidly increasing worldwide, placing a huge economic burden on health systems. Excessive nutrient supply combined with reduced physical exercise results in positive energy balance that promotes adipose tissue expansion. However, the metabolic response and pattern of fat accumulation is variable, depending on the individual’s genetic and acquired susceptibility factors. Some develop metabolically healthy obesity (MHO) and are resistant to obesity-associated metabolic diseases for some time, whereas others readily develop metabolically unhealthy obesity (MUO). An unhealthy response to excess fat accumulation could be due to susceptibility intrinsic factors (e.g., increased likelihood of dedifferentiation and/or inflammation), or by pathogenic drivers extrinsic to the adipose tissue (e.g., hyperinsulinemia), or a combination of both. This review outlines the major transcriptional factors and genes associated with adipogenesis and regulation of adipose tissue homeostasis and describes which of these are disrupted in MUO compared to MHO individuals. It also examines the potential role of pathogenic insulin hypersecretion as an extrinsic factor capable of driving the changes in adipose tissue which cause transition from MHO to MUO. On this basis, therapeutic approaches currently available and emerging to prevent and reverse the transition from MHO to MUO transition are reviewed.
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12
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Whitticar NB, Nunemaker CS. Reducing Glucokinase Activity to Enhance Insulin Secretion: A Counterintuitive Theory to Preserve Cellular Function and Glucose Homeostasis. Front Endocrinol (Lausanne) 2020; 11:378. [PMID: 32582035 PMCID: PMC7296051 DOI: 10.3389/fendo.2020.00378] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Accepted: 05/12/2020] [Indexed: 12/21/2022] Open
Abstract
Pancreatic beta-cells are the only cells in the body that can synthesize and secrete insulin. Through the process of glucose-stimulated insulin secretion, beta-cells release insulin into circulation, stimulating GLUT4-dependent glucose uptake into peripheral tissue. Insulin is normally secreted in pulses that promote signaling at the liver. Long before type 2 diabetes is diagnosed, beta-cells become oversensitive to glucose, causing impaired pulsatility and overstimulation in fasting levels of glucose. The resulting hypersecretion of insulin can cause poor insulin signaling and clearance at the liver, leading to hyperinsulinemia and insulin resistance. Continued overactivity can eventually lead to beta-cell exhaustion and failure at which point type 2 diabetes begins. To prevent or reverse the negative effects of overstimulation, beta-cell activity can be reduced. Clinical studies have revealed the potential of beta-cell rest to reverse new cases of diabetes, but treatments lack durable benefits. In this perspective, we propose an intervention that reduces overactive glucokinase activity in the beta-cell. Glucokinase is known as the glucose sensor of the beta-cell due to its high control over insulin secretion. Therefore, glycolytic overactivity may be responsible for hyperinsulinemia early in the disease and can be reduced to restore normal stimulus-secretion coupling. We have previously reported that reducing glucokinase activity in prediabetic mouse islets can restore pulsatility and enhance insulin secretion. Building on this counterintuitive finding, we review the importance of pulsatile insulin secretion and highlight how normalizing glucose sensing in the beta cell during prediabetic hyperinsulinemia may restore pulsatility and improve glucose homeostasis.
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Affiliation(s)
- Nicholas B. Whitticar
- Translational Biomedical Sciences Program, Graduate College, Ohio University, Athens, OH, United States
- Diabetes Institute, Heritage College of Osteopathic Medicine, Ohio University, Athens OH, United States
- Department of Biomedical Sciences, Heritage College of Osteopathic Medicine, Ohio University, Athens, OH, United States
| | - Craig S. Nunemaker
- Diabetes Institute, Heritage College of Osteopathic Medicine, Ohio University, Athens OH, United States
- Department of Biomedical Sciences, Heritage College of Osteopathic Medicine, Ohio University, Athens, OH, United States
- *Correspondence: Craig S. Nunemaker
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13
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Tricò D, Natali A, Arslanian S, Mari A, Ferrannini E. Identification, pathophysiology, and clinical implications of primary insulin hypersecretion in nondiabetic adults and adolescents. JCI Insight 2018; 3:124912. [PMID: 30568042 DOI: 10.1172/jci.insight.124912] [Citation(s) in RCA: 84] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2018] [Accepted: 11/06/2018] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND Excessive insulin secretion may lead to glucose dysregulation. Our aim was to identify primary (independent of insulin resistance) insulin hypersecretion in subjects with normal glucose tolerance and its role in the progression of dysglycemia. METHODS In 1,168 adults, insulin secretion rate (ISR) and β cell function were estimated by C-peptide modeling during an oral glucose tolerance test (OGTT) and an i.v. glucose tolerance test. Whole-body insulin sensitivity was measured by a hyperinsulinemic-euglycemic clamp. After regressing ISR on insulin sensitivity, subjects in the upper tertile of the distribution of residuals were defined as primary hypersecretors. This approach was applied to a biethnic cohort of 182 obese adolescents, who received an OGTT, a hyperglycemic, and a euglycemic clamp. RESULTS Adult hypersecretors showed older age, more familial diabetes, sedentary lifestyle, increased fat mass, and worse lipid profile compared with the rest of the cohort, despite virtually identical BMI and insulin sensitivity. Insulin secretion was increased by 53% due to enhanced (+23%) β cell glucose sensitivity. Despite the resulting hyperinsulinemia, glucose tolerance was worse in hypersecretors among both adults and adolescents, coupled with higher indices of liver insulin resistance and increased availability of gluconeogenic substrates. At the 3-year follow-up, adult hypersecretors had increased incidence of impaired glucose tolerance/type 2 diabetes. CONCLUSION Primary insulin hypersecretion, independent of insulin resistance, is associated with a worse clinical and metabolic phenotype in adults and adolescents and predicts deterioration of glucose control over time. FUNDING The relationship between insulin sensitivity and cardiovascular disease (RISC) Study was partly supported by EU grant QLG1-CT-2001-01252.
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Affiliation(s)
- Domenico Tricò
- Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy.,Institute of Life Sciences, Sant'Anna School of Advanced Studies, Pisa, Italy
| | - Andrea Natali
- Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy
| | - Silva Arslanian
- Center for Pediatric Research in Obesity and Metabolism, UPMC Children's Hospital of Pittsburgh, Pittsburgh, Pennsylvania, USA.,Division of Pediatric Endocrinology, Diabetes and Metabolism, Children's Hospital of Pittsburgh, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, USA
| | - Andrea Mari
- Institute of Neuroscience, National Research Council, Padua, Italy
| | - Ele Ferrannini
- Institute of Clinical Physiology, National Research Council, Pisa, Italy
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14
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Kolb H, Stumvoll M, Kramer W, Kempf K, Martin S. Insulin translates unfavourable lifestyle into obesity. BMC Med 2018; 16:232. [PMID: 30541568 PMCID: PMC6292073 DOI: 10.1186/s12916-018-1225-1] [Citation(s) in RCA: 55] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/23/2018] [Accepted: 11/26/2018] [Indexed: 12/18/2022] Open
Abstract
Lifestyle factors conferring increased diabetes risk are associated with elevated basal insulin levels (hyperinsulinaemia). The latter predicts later obesity in children and adolescents.A causal role of hyperinsulinaemia for adipose tissue growth is probable because pharmacological reduction of insulin secretion lowers body weight in people who are obese. Genetic inactivation of insulin gene alleles in mice also lowers their systemic insulin levels and prevents or ameliorates high-fat diet-induced obesity. Hyperinsulinaemia causes weight gain because of a physiological property of insulin. Insulin levels that are on the high side of normal, or which are slightly elevated, are sufficient to suppress lipolysis and promote lipogenesis in adipocytes. The effect of insulin on glucose transport or hepatic glucose production requires six or two times higher hormone levels, respectively.It seems justified to suggest a lifestyle that avoids high insulin levels in order to limit anabolic fat tissue activity.
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Affiliation(s)
- Hubert Kolb
- Faculty of Medicine, University of Duesseldorf, Moorenstr. 5, 40225, Duesseldorf, Germany.,West German Centre of Diabetes and Health, Duesseldorf Catholic Hospital Group, Hohensandweg 37, 40591, Duesseldorf, Germany
| | - Michael Stumvoll
- Department of Endocrinology and Nephrology, University of Leipzig, Liebigstraße 18, 04103, Leipzig, Germany
| | - Werner Kramer
- Biomedical and Scientific Consulting, 55130, Mainz, Germany
| | - Kerstin Kempf
- West German Centre of Diabetes and Health, Duesseldorf Catholic Hospital Group, Hohensandweg 37, 40591, Duesseldorf, Germany.
| | - Stephan Martin
- Faculty of Medicine, University of Duesseldorf, Moorenstr. 5, 40225, Duesseldorf, Germany.,West German Centre of Diabetes and Health, Duesseldorf Catholic Hospital Group, Hohensandweg 37, 40591, Duesseldorf, Germany
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15
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Page MM, Skovsø S, Cen H, Chiu AP, Dionne DA, Hutchinson DF, Lim GE, Szabat M, Flibotte S, Sinha S, Nislow C, Rodrigues B, Johnson JD. Reducing insulin via conditional partial gene ablation in adults reverses diet-induced weight gain. FASEB J 2018; 32:1196-1206. [PMID: 29122848 PMCID: PMC5892722 DOI: 10.1096/fj.201700518r] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Excess circulating insulin is associated with obesity in humans and in animal models. However, the physiologic causality of hyperinsulinemia in adult obesity has rightfully been questioned because of the absence of clear evidence that weight loss can be induced by acutely reversing diet-induced hyperinsulinemia. Herein, we describe the consequences of inducible, partial insulin gene deletion in a mouse model in which animals have already been made obese by consuming a high-fat diet. A modest reduction in insulin production/secretion was sufficient to cause significant weight loss within 5 wk, with a specific effect on visceral adipose tissue. This result was associated with a reduction in the protein abundance of the lipodystrophy gene polymerase I and transcript release factor ( Ptrf; Cavin) in gonadal adipose tissue. RNAseq analysis showed that reduced insulin and weight loss also associated with a signature of reduced innate immunity. This study demonstrates that changes in circulating insulin that are too fine to adversely affect glucose homeostasis nonetheless exert control over adiposity.-Page, M. M., Skovsø, S., Cen, H., Chiu, A. P., Dionne, D. A., Hutchinson, D. F., Lim, G. E., Szabat, M., Flibotte, S., Sinha, S., Nislow, C., Rodrigues, B., Johnson, J. D. Reducing insulin via conditional partial gene ablation in adults reverses diet-induced weight gain.
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Affiliation(s)
- Melissa M Page
- Department of Cellular and Physiological Sciences, Diabetes Research Group, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Søs Skovsø
- Department of Cellular and Physiological Sciences, Diabetes Research Group, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Haoning Cen
- Department of Cellular and Physiological Sciences, Diabetes Research Group, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Amy P Chiu
- Pharmaceutical Sciences, University of British Columbia, Vancouver, British Columbia, Canada
| | - Derek A Dionne
- Department of Cellular and Physiological Sciences, Diabetes Research Group, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Daria F Hutchinson
- Department of Cellular and Physiological Sciences, Diabetes Research Group, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Gareth E Lim
- Department of Cellular and Physiological Sciences, Diabetes Research Group, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Marta Szabat
- Department of Cellular and Physiological Sciences, Diabetes Research Group, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Stephane Flibotte
- Pharmaceutical Sciences, University of British Columbia, Vancouver, British Columbia, Canada
| | - Sunita Sinha
- Pharmaceutical Sciences, University of British Columbia, Vancouver, British Columbia, Canada
| | - Corey Nislow
- Pharmaceutical Sciences, University of British Columbia, Vancouver, British Columbia, Canada
| | - Brian Rodrigues
- Pharmaceutical Sciences, University of British Columbia, Vancouver, British Columbia, Canada
| | - James D Johnson
- Department of Cellular and Physiological Sciences, Diabetes Research Group, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
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16
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Abstract
This review is motivated by the need to question dogma that has not yielded significant improvements in outcomes of Type 2 Diabetes treatment: that insulin resistance is the driver of ß-Cell failure and resulting hyperglycemia. We highlight the fact that hyperlipidemia, insulin resistance, and hyperinsulinemia all precede overt diabetes diagnosis and can each induce the other when tested experimentally. New research highlights the importance of high levels of circulating insulin as both a driver of weight gain and insulin resistance. Data from our lab and others document that several nutrients and environmental toxins can stimulate insulin secretion at non-stimulatory glucose in the absence of insulin resistance. This occurs either by direct action on the ß-Cell or by shifting its sensitivity to known secretagogues. We raise the next logical question of whether ß-Cell dysfunction in Type 2 Diabetes is due to impaired function, defined as failure, or if chronic overstimulation of the ß-Cell that exceeds its capacity to synthesize and secrete insulin, defined as abuse, is the main abnormality in Type 2 Diabetes. These questions are important as they have direct implications for how to best prevent and treat Type 2 Diabetes.
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Affiliation(s)
- Karel Erion
- Division of Endocrinology, Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, United States
| | - Barbara E Corkey
- Evans Department of Medicine, Obesity Research Center, Boston University School of Medicine, Boston, MA, United States
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17
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Kristinsson H, Sargsyan E, Manell H, Smith DM, Göpel SO, Bergsten P. Basal hypersecretion of glucagon and insulin from palmitate-exposed human islets depends on FFAR1 but not decreased somatostatin secretion. Sci Rep 2017; 7:4657. [PMID: 28680093 PMCID: PMC5498543 DOI: 10.1038/s41598-017-04730-5] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2016] [Accepted: 06/01/2017] [Indexed: 12/19/2022] Open
Abstract
In obesity fasting levels of both glucagon and insulin are elevated. In these subjects fasting levels of the free fatty acid palmitate are raised. We have demonstrated that palmitate enhances glucose-stimulated insulin secretion from isolated human islets via free fatty acid receptor 1 (FFAR1/GPR40). Since FFAR1 is also present on glucagon-secreting alpha-cells, we hypothesized that palmitate simultaneously stimulates secretion of glucagon and insulin at fasting glucose concentrations. In addition, we hypothesized that concomitant hypersecretion of glucagon and insulin was also contributed by reduced somatostatin secretion. We found basal glucagon, insulin and somatostatin secretion and respiration from human islets, to be enhanced during palmitate treatment at normoglycemia. Secretion of all hormones and mitochondrial respiration were lowered when FFAR1 or fatty acid β-oxidation was inhibited. The findings were confirmed in the human beta-cell line EndoC-βH1. We conclude that fatty acids enhance both glucagon and insulin secretion at fasting glucose concentrations and that FFAR1 and enhanced mitochondrial metabolism but not lowered somatostatin secretion are crucial in this effect. The ability of chronically elevated palmitate levels to simultaneously increase basal secretion of glucagon and insulin positions elevated levels of fatty acids as potential triggering factors for the development of obesity and impaired glucose control.
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Affiliation(s)
- H Kristinsson
- Department of Medical Cell Biology, Uppsala University, BMC, Husargatan 3, Uppsala, Sweden.
| | - E Sargsyan
- Department of Medical Cell Biology, Uppsala University, BMC, Husargatan 3, Uppsala, Sweden
| | - H Manell
- Department of Medical Cell Biology, Uppsala University, BMC, Husargatan 3, Uppsala, Sweden
| | - D M Smith
- Discovery Sciences, Innovative Medicines and Early Development Biotech Unit, AstraZeneca, Cambridge, UK
| | - S O Göpel
- AstraZeneca R&D Gothenburg, CVMD Bioscience, Gothenburg, Sweden
| | - P Bergsten
- Department of Medical Cell Biology, Uppsala University, BMC, Husargatan 3, Uppsala, Sweden
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18
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Abstract
PURPOSE OF REVIEW This perspective is motivated by the need to question dogma that does not work: that the problem is insulin resistance (IR). We highlight the need to investigate potential environmental obesogens and toxins. RECENT FINDINGS The prequel to severe metabolic disease includes three interacting components that are abnormal: (a) IR, (b) elevated lipids and (c) elevated basal insulin (HI). HI is more common than IR and is a significant independent predictor of diabetes. We hypothesize that (1) the initiating defect is HI that increases nutrient consumption and hyperlipidemia (HL); (2) the cause of HI may include food additives, environmental obesogens or toxins that have entered our food supply since 1980; and (3) HI is sustained by HL derived from increased adipose mass and leads to IR. We suggest that HI and HL are early indicators of metabolic dysfunction and treating and reversing these abnormalities may prevent the development of more serious metabolic disease.
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Affiliation(s)
- Karel A. Erion
- 0000 0004 0367 5222grid.475010.7Obesity Research Center, Department of Medicine, Boston University School of Medicine, 650 Albany St, Boston, MA 02118 USA
- 0000 0000 9632 6718grid.19006.3eDivision of Endocrinology, Department of Medicine, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA USA
| | - Barbara E. Corkey
- 0000 0004 0367 5222grid.475010.7Obesity Research Center, Department of Medicine, Boston University School of Medicine, 650 Albany St, Boston, MA 02118 USA
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19
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Kundu P, Mondal A, Chowdhury C. A Palladium-Catalyzed Method for the Synthesis of 2-(α-Styryl)-2,3-dihydroquinazolin-4-ones and 3-(α-Styryl)-3,4-dihydro-1,2,4-benzothiadiazine-1,1-dioxide: Access to 2-(α-Styryl)quinazolin-4(3H)-ones and 3-(α-Styryl)-1,2,4-benzothiadiazine-1,1-dioxides. J Org Chem 2016; 81:6596-608. [DOI: 10.1021/acs.joc.6b01242] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- Priyanka Kundu
- Organic & Medicinal Chemisty Division, CSIR-Indian Institute of Chemical Biology, 4, Raja S.C. Mullick Road, Kolkata-700032, India
| | - Amrita Mondal
- Organic & Medicinal Chemisty Division, CSIR-Indian Institute of Chemical Biology, 4, Raja S.C. Mullick Road, Kolkata-700032, India
| | - Chinmay Chowdhury
- Organic & Medicinal Chemisty Division, CSIR-Indian Institute of Chemical Biology, 4, Raja S.C. Mullick Road, Kolkata-700032, India
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20
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Vetterli L, Carobbio S, Frigerio F, Karaca M, Maechler P. The Amplifying Pathway of the β-Cell Contributes to Diet-induced Obesity. J Biol Chem 2016; 291:13063-75. [PMID: 27137930 DOI: 10.1074/jbc.m115.707448] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2015] [Indexed: 12/24/2022] Open
Abstract
Efficient energy storage in adipose tissues requires optimal function of the insulin-producing β-cell, whereas its dysfunction promotes diabetes. The associated paradox related to β-cell efficiency is that excessive accumulation of fat in adipose tissue predisposes for type 2 diabetes. Insulin exocytosis is regulated by intracellular metabolic signal transduction, with glutamate dehydrogenase playing a key role in the amplification of the secretory response. Here, we used mice with β-cell-selective glutamate dehydrogenase deletion (βGlud1(-/-)), lacking an amplifying pathway of insulin secretion. As opposed to control mice, βGlud1(-/-) animals fed a high calorie diet maintained glucose tolerance and did not develop diet-induced obesity. Islets of βGlud1(-/-) mice did not increase their secretory response upon high calorie feeding, as did islets of control mice. Inhibited adipose tissue expansion observed in knock-out mice correlated with lower expression of genes responsible for adipogenesis. Rather than being efficiently stored, lipids were consumed at a higher rate in βGlud1(-/-) mice compared with controls, in particular during food intake periods. These results show that reduced β-cell function prior to high calorie feeding prevented diet-induced obesity.
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Affiliation(s)
- Laurène Vetterli
- From the Department of Cell Physiology and Metabolism and Faculty Diabetes Center, Geneva University Medical Centre, 1211 Geneva 4, Switzerland
| | - Stefania Carobbio
- From the Department of Cell Physiology and Metabolism and Faculty Diabetes Center, Geneva University Medical Centre, 1211 Geneva 4, Switzerland
| | - Francesca Frigerio
- From the Department of Cell Physiology and Metabolism and Faculty Diabetes Center, Geneva University Medical Centre, 1211 Geneva 4, Switzerland
| | - Melis Karaca
- From the Department of Cell Physiology and Metabolism and Faculty Diabetes Center, Geneva University Medical Centre, 1211 Geneva 4, Switzerland
| | - Pierre Maechler
- From the Department of Cell Physiology and Metabolism and Faculty Diabetes Center, Geneva University Medical Centre, 1211 Geneva 4, Switzerland
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21
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Templeman NM, Clee SM, Johnson JD. Suppression of hyperinsulinaemia in growing female mice provides long-term protection against obesity. Diabetologia 2015; 58:2392-402. [PMID: 26155745 PMCID: PMC4572061 DOI: 10.1007/s00125-015-3676-7] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/30/2015] [Accepted: 06/05/2015] [Indexed: 01/13/2023]
Abstract
AIMS/HYPOTHESIS Hyperinsulinaemia is associated with obesity but its causal role in the onset of obesity remains controversial. In this study, we tested the hypothesis that transient attenuation of diet-induced insulin hypersecretion in young mice can provide sustained protection against obesity throughout adult life. METHODS Using 'genetically humanised' mice lacking both alleles of rodent-specific Ins1, we compared mice heterozygous for the ancestral insulin gene Ins2 with Ins2(+/+) controls. Female Ins1(-/-):Ins2(+/-) and Ins1(-/-):Ins2(+/+) littermates were fed chow or high-fat diet (HFD). Insulin secretion, metabolic health variables and body mass/composition were tracked for over 1 year. We examined islet function and adipose transcript levels of adipogenic, lipogenic and lipolytic genes at two time points. RESULTS In control Ins1(-/-):Ins2(+/+) mice, HFD resulted in elevated fasting and glucose-stimulated insulin secretion between 8 weeks and 27 weeks of age. Hyperinsulinaemia was reduced by nearly 50% in Ins1(-/-):Ins2(+/-) mice during this period, without lasting adverse effects on glucose homeostasis. This corresponded with attenuated weight gain and adiposity. White adipose tissue from Ins1(-/-):Ins2(+/-) mice had fewer large lipid droplets, although transcriptional changes were not detected. Importantly, Ins1(-/-):Ins2(+/-) mice remained lighter than Ins1(-/-):Ins2(+/+) littermates despite reaching an equivalent degree of hyperinsulinaemia on HFD by 52 weeks. CONCLUSIONS/INTERPRETATION These data demonstrate that attenuation of hyperinsulinaemia in young, growing female mice provides a long-lasting protection against obesity. This protection persists despite a late-onset emergence of hyperinsulinaemia in HFD-fed Ins1(-/-):Ins2(+/-) mice. Given the evolutionary conserved roles of insulin, it is possible that suppressing hyperinsulinaemia early in life may have far-reaching consequences on obesity in full-grown adult humans.
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Affiliation(s)
- Nicole M Templeman
- Diabetes Research Group, Life Sciences Institute, Department of Cellular and Physiological Sciences, University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC, Canada, V6T 1Z3
| | - Susanne M Clee
- Diabetes Research Group, Life Sciences Institute, Department of Cellular and Physiological Sciences, University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC, Canada, V6T 1Z3
| | - James D Johnson
- Diabetes Research Group, Life Sciences Institute, Department of Cellular and Physiological Sciences, University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC, Canada, V6T 1Z3.
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22
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Buffenstein R, Nelson OL, Corbit KC. Questioning the preclinical paradigm: natural, extreme biology as an alternative discovery platform. Aging (Albany NY) 2015; 6:913-20. [PMID: 25553771 PMCID: PMC4276785 DOI: 10.18632/aging.100704] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The pace at which science continues to advance is astonishing. From cosmology, microprocessors, structural engineering, and DNA sequencing our lives are continually affected by science-based technology. However, progress in treating human ailments, especially age-related conditions such as cancer and Alzheimer's disease, moves at a relative snail's pace. Given that the amount of investment is not disproportionately low, one has to question why our hopes for the development of efficacious drugs for such grievous illnesses have been frustratingly unrealized. Here we discuss one aspect of drug development –rodent models – and propose an alternative approach to discovery research rooted in evolutionary experimentation. Our goal is to accelerate the conversation around how we can move towards more translative preclinical work.
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Affiliation(s)
- Rochelle Buffenstein
- Barshop Institute for Aging and Longevity Studies, University of Texas Health Science Center at San Antonio, TX University of Texas Health Science Center at San Antonio, TX USA
| | - O Lynne Nelson
- Department of Veterinary Clinical Sciences, Washington State University, Pullman, WA 9916, USA
| | - Kevin C Corbit
- Department of Metabolic Disorders, Amgen, Inc., Thousand Oaks, CA 91360, USA
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23
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Hasson BR, Apovian C, Istfan N. Racial/Ethnic Differences in Insulin Resistance and Beta Cell Function: Relationship to Racial Disparities in Type 2 Diabetes among African Americans versus Caucasians. Curr Obes Rep 2015; 4:241-9. [PMID: 26627219 DOI: 10.1007/s13679-015-0150-2] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Both biological and sociocultural factors have been implicated in the well-documented racial disparity in incidence and prevalence of type 2 diabetes (T2D) between African Americans (AA) and non-Hispanic whites (NHW). This review examines the extent to which biological differences in glucose metabolism, specifically insulin resistance and beta cell function (BCF), contribute to this disparity. The majority of available data suggests that AA are more insulin resistant and have upregulated BCF compared to NHW. Increasing evidence implicates high insulin secretion as a cause rather than consequence of T2D; therefore, upregulated BCF in AA may specifically confer increased risk of T2D in this cohort. Racial disparities in the metabolic characteristics of T2D have direct implications for the treatment and health consequences of this disease; therefore, future research is needed to determine whether strategies to reduce insulin secretion in AA may prevent or delay T2D and lessen racial health disparities.
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Affiliation(s)
- Brooke R Hasson
- Division of Endocrinology, Diabetes, and Nutrition, Boston University School of Medicine, 88 East Newton Street, Boston, MA, 02118, USA.
| | - Caroline Apovian
- Division of Endocrinology, Diabetes, and Nutrition, Boston University School of Medicine, 88 East Newton Street, Boston, MA, 02118, USA.
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24
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Pedersen DJ, Guilherme A, Danai LV, Heyda L, Matevossian A, Cohen J, Nicoloro SM, Straubhaar J, Noh HL, Jung D, Kim JK, Czech MP. A major role of insulin in promoting obesity-associated adipose tissue inflammation. Mol Metab 2015; 4:507-18. [PMID: 26137438 PMCID: PMC4481426 DOI: 10.1016/j.molmet.2015.04.003] [Citation(s) in RCA: 109] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/11/2015] [Revised: 04/18/2015] [Accepted: 04/22/2015] [Indexed: 12/23/2022] Open
Abstract
Objective Adipose tissue (AT) inflammation is associated with systemic insulin resistance and hyperinsulinemia in obese rodents and humans. A longstanding concept is that hyperinsulinemia may promote systemic insulin resistance through downregulation of its receptor on target tissues. Here we tested the novel hypothesis that insulin also impairs systemic insulin sensitivity by specifically enhancing adipose inflammation. Methods Circulating insulin levels were reduced by about 50% in diet-induced and genetically obese mice by treatments with diazoxide or streptozotocin, respectively. We then examined AT crown-like structures, macrophage markers and pro-inflammatory cytokine expression in AT. AT lipogenesis and systemic insulin sensitivity was also monitored. Conversely, insulin was infused into lean mice to determine its affects on the above parameters. Results Lowering circulating insulin levels in obese mice by streptozotocin treatment decreased macrophage content in AT, enhancing insulin stimulated Akt phosphorylation and de novo lipogenesis (DNL). Moreover, responsiveness of blood glucose levels to injected insulin was improved by streptozotocin and diazoxide treatments of obese mice without changes in body weight. Remarkably, even in lean mice, infusion of insulin under constant euglycemic conditions stimulated expression of cytokines in AT. Consistent with these findings, insulin treatment of 3T3-L1 adipocytes caused a 10-fold increase in CCL2 mRNA levels within 6 h, which was blocked by the ERK inhibitor PD98059. Conclusion Taken together, these results indicate that obesity-associated hyperinsulinemia unexpectedly drives AT inflammation in obese mice, which in turn contributes to factors that suppress insulin-stimulated adipocyte DNL and systemic insulin sensitivity. Adipose tissue inflammation correlates with hyperinsulinemia in obese mice and humans independent of BMI. Reduction of hyperinsulinemia ameliorates adipose tissue inflammation and enhances systemic insulin sensitivity. Insulin increases adipose inflammation in vivo and enhances adipocyte MCP-1 expression in vitro through ERK activation.
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Affiliation(s)
- David J Pedersen
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Adilson Guilherme
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Laura V Danai
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Lauren Heyda
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Anouch Matevossian
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Jessica Cohen
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Sarah M Nicoloro
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Juerg Straubhaar
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Hye Lim Noh
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA 01605, USA ; Division of Endocrinology, Metabolism, and Diabetes, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - DaeYoung Jung
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA 01605, USA ; Division of Endocrinology, Metabolism, and Diabetes, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Jason K Kim
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA 01605, USA ; Division of Endocrinology, Metabolism, and Diabetes, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Michael P Czech
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA 01605, USA
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25
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Pulsatile insulin secretion, impaired glucose tolerance and type 2 diabetes. Mol Aspects Med 2015; 42:61-77. [PMID: 25637831 DOI: 10.1016/j.mam.2015.01.003] [Citation(s) in RCA: 151] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2014] [Revised: 01/09/2015] [Accepted: 01/10/2015] [Indexed: 12/28/2022]
Abstract
Type 2 diabetes (T2DM) results when increases in beta cell function and/or mass cannot compensate for rising insulin resistance. Numerous studies have documented the longitudinal changes in metabolism that occur during the development of glucose intolerance and lead to T2DM. However, the role of changes in insulin secretion, both amount and temporal pattern, has been understudied. Most of the insulin secreted from pancreatic beta cells of the pancreas is released in a pulsatile pattern, which is disrupted in T2DM. Here we review the evidence that changes in beta cell pulsatility occur during the progression from glucose intolerance to T2DM in humans, and contribute significantly to the etiology of the disease. We review the evidence that insulin pulsatility improves the efficacy of secreted insulin on its targets, particularly hepatic glucose production, but also examine evidence that pulsatility alters or is altered by changes in peripheral glucose uptake. Finally, we summarize our current understanding of the biophysical mechanisms responsible for oscillatory insulin secretion. Understanding how insulin pulsatility contributes to normal glucose homeostasis and is altered in metabolic disease states may help improve the treatment of T2DM.
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Mogul HR, Freeman R, Nguyen K, Frey M, Klein LA, Jozak S, Tanenbaum K. Carbohydrate modified diet & insulin sensitizers reduce body weight & modulate metabolic syndrome measures in EMPOWIR (enhance the metabolic profile of women with insulin resistance): a randomized trial of normoglycemic women with midlife weight gain. PLoS One 2014; 9:e108264. [PMID: 25259787 PMCID: PMC4178125 DOI: 10.1371/journal.pone.0108264] [Citation(s) in RCA: 7] [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: 04/29/2014] [Accepted: 08/18/2014] [Indexed: 01/06/2023] Open
Abstract
RATIONALE Progressive midlife weight gain is associated with multiple adverse health outcomes and may represent an early manifestation of insulin resistance in a distinct subset of women. Emerging data implicate hyperinsulinema as a proximate cause of weight gain and support strategies that attenuate insulin secretion. OBJECTIVE To assess a previously reported novel hypocaloric carbohydrate modified diet alone (D), and in combination with metformin (M) and metformin plus low-dose rosiglitazone (MR), in diverse women with midlife weight gain (defined as >20lbs since the twenties), normal glucose tolerance, and hyperinsulinemia. PARTICIPANTS 46 women, mean age 46.6±1.0, BMI 30.5±0.04 kg/m2, 54.5% white, 22.7% black, 15.9% Hispanic, at 2 university medical centers. METHODS A dietary intervention designed to reduce insulin excursions was implemented in 4 weekly nutritional group workshops prior to randomization. MAIN OUTCOME MEASURE Change in 6-month fasting insulin. Pre-specified secondary outcomes were changes in body weight, HOMA-IR, metabolic syndrome (MS) measures, leptin, and adiponectin. RESULTS Six-month fasting insulin declined significantly in the M group: 12.5 to 8.0 µU/ml, p = .026. Mean 6-month weight decreased significantly and comparably in D, M, and MR groups: 4.7, 5.4, and 5.5% (p's.049, .002, and.032). HOMA-IR decreased in M and MR groups (2.5 to 1.6 and 1.9 to 1.3, p's = .054, .013). Additional improvement in MS measures included reduced waist circumference in D and MR groups and increased HDL in the D and M groups. Notably, mean fasting leptin did not decline in a subset of subjects with weight loss (26.15±2.01 ng/ml to 25.99±2.61 ng/ml, p = .907. Adiponectin increased significantly in the MR group (11.1±1.0 to 18.5±7.4, p<.001) Study medications were well tolerated. CONCLUSIONS These findings suggest that EMPOWIR's easily implemented dietary interventions, alone and in combination with pharmacotherapies that target hyperinsulinemia, merit additional investigation in larger, long-term studies. TRIAL REGISTRATION ClinicalTrials.gov NCT00618072.
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Affiliation(s)
- Harriette R. Mogul
- Department of Medicine, Division of Endocrinology, New York Medical College, Valhalla, New York, United States of America
| | - Ruth Freeman
- Departments of Medicine and Obstetrics and Gynecology, Albert Einstein College of Medicine, Bronx, New York, United States of America
| | - Khoa Nguyen
- Department of Medicine, Division of Endocrinology, New York Medical College, Valhalla, New York, United States of America
| | - Michael Frey
- Department of Medicine, Division of Endocrinology, New York Medical College, Valhalla, New York, United States of America
| | - Lee-Ann Klein
- Department of Medicine, Division of Endocrinology, New York Medical College, Valhalla, New York, United States of America
| | - Sheila Jozak
- Departments of Medicine and Obstetrics and Gynecology, Albert Einstein College of Medicine, Bronx, New York, United States of America
| | - Karen Tanenbaum
- Department of Medicine, Division of Endocrinology, New York Medical College, Valhalla, New York, United States of America
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Electroacupuncture and rosiglitazone combined therapy as a means of treating insulin resistance and type 2 diabetes mellitus: a randomized controlled trial. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE 2013; 2013:969824. [PMID: 23983807 PMCID: PMC3745852 DOI: 10.1155/2013/969824] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/21/2013] [Revised: 04/19/2013] [Accepted: 04/28/2013] [Indexed: 01/08/2023]
Abstract
Aims. To evaluate the efficacy of rosiglitazone (TZD) and electroacupuncture (EA) combined therapy as a treatment for type 2 diabetes mellitus (T2DM) patients by randomized single-blind placebo controlled clinical trial.
Methods. A total of 31 newly diagnostic T2DM patients, who fulfilled the study's eligibility criteria, were recruited. The individuals were randomly assigned into two groups, the control group (TZD, N = 15) and the experimental group (TZD + EA, N = 16). Changes in their plasma free fatty acid (FFA), glucose, and insulin levels, together with their homeostasis model assessment (HOMA) indices, were statistically compared before and after treatment. Hypoglycemic activity (%) was also compared between these two groups.
Results. There was no significant difference in hypoglycemic activity between the TZD and TZD + EA group. The effectiveness of the combined therapy seems to derive from an improvement in insulin resistance and a significant lowering of the secreted insulin rather than the effect of TZD alone on T2DM. The combined treatment had no significant adverse effects. A lower plasma FFA concentration is likely to be the mechanism that causes this effect. Conclusion. This combined therapy seems to suppress endogenous insulin secretion by improving insulin resistance via a mechanism involving a reduction in plasma FFA. This trial is registered with ClinicalTrials.gov NCT01577095.
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Corkey BE. Diabetes: have we got it all wrong? Insulin hypersecretion and food additives: cause of obesity and diabetes? Diabetes Care 2012; 35:2432-7. [PMID: 23173132 PMCID: PMC3507569 DOI: 10.2337/dc12-0825] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Affiliation(s)
- Barbara E Corkey
- Evans Department of Medicine, Obesity Research Center, Boston University School of Medicine, Boston, Massachusetts, USA.
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Hardy AB, Wijesekara N, Genkin I, Prentice KJ, Bhattacharjee A, Kong D, Chimienti F, Wheeler MB. Effects of high-fat diet feeding on Znt8-null mice: differences between β-cell and global knockout of Znt8. Am J Physiol Endocrinol Metab 2012; 302:E1084-96. [PMID: 22338079 PMCID: PMC3774340 DOI: 10.1152/ajpendo.00448.2011] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Genomewide association studies have linked a polymorphism in the zinc transporter 8 (Znt8) gene to higher risk of developing type 2 diabetes. Znt8 is highly expressed in pancreatic β-cells where it is involved in the regulation of zinc transport into granules. However, Znt8 is also expressed in other tissues including α-cells, where its function is as yet unknown. Previous work demonstrated that mice lacking Znt8 globally were more susceptible to diet-induced obesity (Lemaire et al., Proc Natl Acad Sci USA 106: 14872-14877, 2009; Nicolson et al., Diabetes 58: 2070-2083, 2009). Therefore, the main goal of this study was to examine the physiological impact of β-cell-specific Znt8 deficiency in mice during high-fat high-calorie (HFHC) diet feeding. For these studies, we used β-cell-specific Znt8 knockout (Ins2Cre:Znt8loxP/loxP) and whole body Znt8 knockout (Cre-:Znt8(-/-)) mice placed on a HFHC diet for 16 wk. Ins2Cre:Znt8loxP/loxP mice on HFHC diet had similar body weights throughout the study but displayed impaired insulin biosynthesis and secretion and were glucose intolerant compared with littermate control Ins2Cre mice. In contrast, Cre-:Znt8(-/-) mice became remarkably obese, hyperglycemic, hyperinsulinemic, insulin resistant, and glucose intolerant compared with littermate control Cre- mice. These data show that β-cell Znt8 alone does not considerably aggravate weight gain and glucose intolerance during metabolic stress imposed by an HFHC diet. However, global loss of Znt8 is involved in exacerbating diet-induced obesity and resulting insulin resistance, and this may be due to the loss of Znt8 activity in a tissue other than the β-cell. Thus, our data suggest that Znt8 contributes to the risk of developing type 2 diabetes through β-cell- and non-β-cell-specific effects.
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Affiliation(s)
| | | | | | | | | | - D. Kong
- 3Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts; and
| | | | - M. B. Wheeler
- 1Department of Physiology and
- 2Department of Medicine, University of Toronto, Toronto, Ontario, Canada;
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Abstract
The Banting Medal for Scientific Achievement Award is the American Diabetes Association's highest scientific award and honors an individual who has made significant, long-term contributions to the understanding of diabetes, its treatment, and/or prevention. The award is named after Nobel Prize winner Sir Frederick Banting, who codiscovered insulin treatment for diabetes. Dr. Barbara E. Corkey received the American Diabetes Association's Banting Medal for Scientific Achievement at the Association's 71st Scientific Sessions, 24-28 June 2011, San Diego, California. She presented the Banting Lecture, "Hyperinsulinemia: Cause or Consequence?" on Sunday, 26 June 2011.
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Affiliation(s)
- Barbara E Corkey
- Obesity Research Center, Evans Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, USA.
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Hypothalamic Obesity following Craniopharyngioma Surgery: Results of a Pilot Trial of Combined Diazoxide and Metformin Therapy. INTERNATIONAL JOURNAL OF PEDIATRIC ENDOCRINOLOGY 2011; 2011:417949. [PMID: 21603206 DOI: 10.1155/2011/417949] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2010] [Accepted: 02/07/2011] [Indexed: 01/08/2023]
Abstract
Objective. To assess the effect of combined diazoxide-metformin therapy in obese adolescents treated for craniopharyngioma. Design. A prospective open-label 6-month pilot treatment trial in 9 obese subjects with craniopharyngioma. Diazoxide (2 mg/kg divided b.i.d., maximum 200 mg/day) and metformin (1000 mg b.i.d.). Whole body insulin sensitivity index (WBISI) and area-under-the-curve insulin (AUC(ins)) were calculated. Results. Seven subjects completed: 4M/3F, mean ± SD age 15.4 ± 2.9 years, weight 99.7 ± 26.3 kg, BMI 35.5 ± 5.6 kg/m(2), and BMI SDS 2.3 ± 0.3. Two were withdrawn due to vomiting and peripheral edema. Of participants completing the study, the mean ± SD weight gain, BMI, and BMI SDS during the 6 months were reduced compared to the 6 months prestudy (+1.2 ± 5.9 versus +9.5 ± 2.7 kg, P = .004; -0.3 ± 2.3 versus +2.2 ± 1.5 kg/m(2), P = .04; -0.04 ± 0.15 versus +0.11 ± 0.08, P = .021, resp.). AUC(ins) correlated with weight loss (r = 0.82, P = .02) and BMI decrease (r = 0.96, P = .009). Conclusion. Combined diazoxide-metformin therapy was associated with reduced weight gain in patients with hypothalamic obesity. AUC(ins) at study commencement predicted effectiveness of the treatment.
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Affiliation(s)
- Michael A Valentino
- Department of Pharmacology, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
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Abstract
OBJECTIVES : The mechanisms by which correcting hyperglycemia with exogenous insulin improves mortality and morbidity in critically ill patients remain unclear. We designed this study to test the hypothesis that relative endogenous insulin deficiency is associated with adverse outcomes in critical illness related to hyperglycemia. DESIGN : Prospective controlled animal study. SETTING : University research laboratory. SUBJECTS : Male C57BL/6J mice, 8-12 wks old. INTERVENTIONS : Spontaneously breathing mice were instrumented with chronic indwelling arterial and venous catheters. After a postoperative recovery period, endotoxemia was initiated with intra-arterial lipopolysaccharide (1 mg/kg) in the presence of dextrose infusion (100 microL/hr). Insulin secretion was blocked with diazoxide (2.5-30 mg/kg/day). Mice were monitored continuously for 48 hrs with blood sampled serially for blood glucose and plasma insulin determinations. MEASUREMENTS AND MAIN RESULTS : In both saline- and glucose-infused mice, lipopolysaccharide administration induced transient hemodynamic instability without significant impact on mortality. In the saline-infused group, lipopolysaccharide administration caused a transient reduction in blood glucose and in circulating insulin. However, in glucose-infused mice, lipopolysaccharide induced a large and unexpected increase in circulating insulin without significant alteration in blood glucose. Blockade of insulin secretion in response to lipopolysaccharide in the presence of exogenous glucose precipitated marked hyperglycemia and resulted in >90% mortality. In a subanalysis of animals matched for the degree of hyperglycemia, nonsurvivors had markedly lower insulin levels compared with survivors (3.5 +/- 0.8 ng/dL vs. 9.3 +/- 1.4 ng/dL; p < .004). CONCLUSIONS : Endogenous insulin deficiency in the face of hyperglycemia is associated with mortality in a mouse model of lipopolysaccharide-induced critical illness.
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Trivin C, Busiah K, Mahlaoui N, Recasens C, Souberbielle JC, Zerah M, Sainte-Rose C, Brauner R. Childhood craniopharyngioma: greater hypothalamic involvement before surgery is associated with higher homeostasis model insulin resistance index. BMC Pediatr 2009; 9:24. [PMID: 19341477 PMCID: PMC2675525 DOI: 10.1186/1471-2431-9-24] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/20/2008] [Accepted: 04/02/2009] [Indexed: 11/21/2022] Open
Abstract
Background Obesity seems to be linked to the hypothalamic involvement in craniopharyngioma. We evaluated the pre-surgery relationship between the degree of this involvement on magnetic resonance imaging and insulin resistance, as evaluated by the homeostasis model insulin resistance index (HOMA). As insulin-like growth factor 1, leptin, soluble leptin receptor (sOB-R) and ghrelin may also be involved, we compared their plasma concentrations and their link to weight change. Methods 27 children with craniopharyngioma were classified as either grade 0 (n = 7, no hypothalamic involvement), grade 1 (n = 8, compression without involvement), or grade 2 (n = 12, severe involvement). Results Despite having similar body mass indexes (BMI), the grade 2 patients had higher glucose, insulin and HOMA before surgery than the grade 0 (P = 0.02, <0.05 and 0.02 respectively) and 1 patients (P < 0.02 and <0.03 for both insulin and HOMA). The grade 0 (5.8 ± 4.9) and 1 (7.2 ± 5.3) patients gained significantly less weight (kg) during the year after surgery than did the grade 2 (16.3 ± 7.4) patients. The pre-surgery HOMA was positively correlated with these weight changes (P < 0.03). The data for the whole population before and 6–18 months after surgery showed increases in BMI (P < 0.0001), insulin (P < 0.005), and leptin (P = 0.0005), and decreases in sOB-R (P < 0.04) and ghrelin (P < 0.03). Conclusion The hypothalamic involvement by the craniopharyngioma before surgery seems to determine the degree of insulin resistance, regardless of the BMI. The pre-surgery HOMA values were correlated with the post-surgery weight gain. This suggests that obesity should be prevented by reducing inn secretion in those cases with hypothalamic involvement.
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Affiliation(s)
- Christine Trivin
- 1AP-HP, Hôpital Necker-Enfants Malades, Service d'Explorations Fonctionnelles, Paris, 75743, France.
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Yaney GC, Corkey BE. Fatty acid metabolism and insulin secretion in pancreatic beta cells. Diabetologia 2003; 46:1297-312. [PMID: 13680127 DOI: 10.1007/s00125-003-1207-4] [Citation(s) in RCA: 185] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/14/2003] [Revised: 07/14/2003] [Indexed: 01/16/2023]
Abstract
Increases in glucose or fatty acids affect metabolism via changes in long-chain acyl-CoA formation and chronically elevated fatty acids increase total cellular CoA. Understanding the response of pancreatic beta cells to increased amounts of fuel and the role that altered insulin secretion plays in the development and maintenance of obesity and Type 2 diabetes is important. Data indicate that the activated form of fatty acids acts as an effector molecule in stimulus-secretion coupling. Glucose increases cytosolic long-chain acyl-CoA because it increases the "switch" compound malonyl-CoA that blocks mitochondrial beta-oxidation, thus implementing a shift from fatty acid to glucose oxidation. We present arguments in support of the following: (i) A source of fatty acid either exogenous or endogenous (derived by lipolysis of triglyceride) is necessary to support normal insulin secretion; (ii) a rapid increase of fatty acids potentiates glucose-stimulated secretion by increasing fatty acyl-CoA or complex lipid concentrations that act distally by modulating key enzymes such as protein kinase C or the exocytotic machinery; (iii) a chronic increase of fatty acids enhances basal secretion by the same mechanism, but promotes obesity and a diminished response to stimulatory glucose; (iv) agents which raise cAMP act as incretins, at least in part, by stimulating lipolysis via beta-cell hormone-sensitive lipase activation. Furthermore, increased triglyceride stores can give higher rates of lipolysis and thus influence both basal and stimulated insulin secretion. These points highlight the important roles of NEFA, LC-CoA, and their esterified derivatives in affecting insulin secretion in both normal and pathological states.
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Affiliation(s)
- G C Yaney
- Boston University School of Medicine, Obesity Research Center, 650 Albany Street, Boston, MA 02118, USA
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Velasquez-Mieyer PA, Cowan PA, Arheart KL, Buffington CK, Spencer KA, Connelly BE, Cowan GW, Lustig RH. Suppression of insulin secretion is associated with weight loss and altered macronutrient intake and preference in a subset of obese adults. Int J Obes (Lond) 2003; 27:219-26. [PMID: 12587002 PMCID: PMC1490021 DOI: 10.1038/sj.ijo.802227] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.0] [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
PURPOSE Hyperinsulinemia is a common feature of many obesity syndromes. We investigated whether suppression of insulin secretion, without dietary or exercise intervention, could promote weight loss and alter food intake and preference in obese adults. METHODS Suppression of insulin secretion was achieved using octreotide-LAR 40 mg IM q28d for 24 weeks in 44 severely obese adults (89% female, 39% minority). Oral glucose tolerance testing was performed before and after treatment, indices of beta-cell activity (CIRgp), insulin sensitivity (CISI), and clearance (CP/I AUC) were computed, and leptin levels, 3-day food records and carbohydrate-craving measurements were obtained. DEXA evaluations were performed pre- and post-therapy in an evaluable subgroup. RESULTS For the entire cohort, significant insulin suppression was achieved with simultaneous improvements in insulin sensitivity, weight loss, and body mass index (BMI). Leptin, fat mass, total caloric intake, and carbohydrate craving significantly decreased. When grouped by BMI response, high responders (HR; DeltaBMI<-3 kg/m(2)) and low responders (LR; DeltaBMI between -3 and -0.5) exhibited higher suppression of CIRgp and IAUC than nonresponders (NR; DeltaBMI-0.5). CISI improved and significant declines in leptin and fat mass occurred only in HR and LR. Conversely, both leptin and fat mass increased in NR. Carbohydrate intake was markedly suppressed in HR only, while carbohydrate-craving scores decreased in HR and LR. For the entire cohort, DeltaBMI correlated with DeltaCISI, Deltafat mass, and Deltaleptin. DeltaFat mass also correlated with DeltaIAUC and DeltaCISI. CONCLUSIONS In a subcohort of obese adults, suppression of insulin secretion was associated with loss of body weight and fat mass and with concomitant modulation of caloric intake and macronutrient preference.
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Affiliation(s)
- P A Velasquez-Mieyer
- Department of Pediatrics, University of Tennessee Health Science Center, Memphis, USA.
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