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Townsend LK, Steinberg GR. AMPK and the Endocrine Control of Metabolism. Endocr Rev 2023; 44:910-933. [PMID: 37115289 DOI: 10.1210/endrev/bnad012] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2023] [Revised: 03/10/2023] [Accepted: 04/24/2023] [Indexed: 04/29/2023]
Abstract
Complex multicellular organisms require a coordinated response from multiple tissues to maintain whole-body homeostasis in the face of energetic stressors such as fasting, cold, and exercise. It is also essential that energy is stored efficiently with feeding and the chronic nutrient surplus that occurs with obesity. Mammals have adapted several endocrine signals that regulate metabolism in response to changes in nutrient availability and energy demand. These include hormones altered by fasting and refeeding including insulin, glucagon, glucagon-like peptide-1, catecholamines, ghrelin, and fibroblast growth factor 21; adipokines such as leptin and adiponectin; cell stress-induced cytokines like tumor necrosis factor alpha and growth differentiating factor 15, and lastly exerkines such as interleukin-6 and irisin. Over the last 2 decades, it has become apparent that many of these endocrine factors control metabolism by regulating the activity of the AMPK (adenosine monophosphate-activated protein kinase). AMPK is a master regulator of nutrient homeostasis, phosphorylating over 100 distinct substrates that are critical for controlling autophagy, carbohydrate, fatty acid, cholesterol, and protein metabolism. In this review, we discuss how AMPK integrates endocrine signals to maintain energy balance in response to diverse homeostatic challenges. We also present some considerations with respect to experimental design which should enhance reproducibility and the fidelity of the conclusions.
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Affiliation(s)
- Logan K Townsend
- Centre for Metabolism Obesity and Diabetes Research, Hamilton, ON L8S 4L8, Canada
- Division of Endocrinology and Metabolism, Department of Medicine, McMaster University, Hamilton, ON L8S 4L8, Canada
| | - Gregory R Steinberg
- Centre for Metabolism Obesity and Diabetes Research, Hamilton, ON L8S 4L8, Canada
- Division of Endocrinology and Metabolism, Department of Medicine, McMaster University, Hamilton, ON L8S 4L8, Canada
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON L8S 4L8, Canada
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2
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Wu D, Zhang Z, Sun W, Yan Y, Jing M, Ma S. The effect of G0S2 on insulin sensitivity: A proteomic analysis in a G0S2-overexpressed high-fat diet mouse model. Front Endocrinol (Lausanne) 2023; 14:1130350. [PMID: 37033250 PMCID: PMC10076770 DOI: 10.3389/fendo.2023.1130350] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Accepted: 03/07/2023] [Indexed: 04/11/2023] Open
Abstract
BACKGROUND Previous research has shown a tight relationship between the G0/G1 switch gene 2 (G0S2) and metabolic diseases such as non-alcoholic fatty liver disease (NAFLD) and obesity and diabetes, and insulin resistance has been shown as the major risk factor for both NAFLD and T2DM. However, the mechanisms underlying the relationship between G0S2 and insulin resistance remain incompletely understood. Our study aimed to confirm the effect of G0S2 on insulin resistance, and determine whether the insulin resistance in mice fed a high-fat diet (HFD) results from G0S2 elevation. METHODS In this study, we extracted livers from mice that consumed HFD and received tail vein injections of AD-G0S2/Ad-LacZ, and performed a proteomics analysis. RESULTS Proteomic analysis revealed that there was a total of 125 differentially expressed proteins (DEPs) (56 increased and 69 decreased proteins) among the identified 3583 proteins. Functional enrichment analysis revealed that four insulin signaling pathway-associated proteins were significantly upregulated and five insulin signaling pathway -associated proteins were significantly downregulated. CONCLUSION These findings show that the DEPs, which were associated with insulin resistance, are generally consistent with enhanced insulin resistance in G0S2 overexpression mice. Collectively, this study demonstrates that G0S2 may be a potential target gene for the treatment of obesity, NAFLD, and diabetes.
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Affiliation(s)
- Dongming Wu
- College of First Clinical Medicine, Shandong University of Traditional Chinese Medicine, Jinan, China
| | - Zhenyuan Zhang
- Department of Endocrinology, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, China
- Shandong Clinical Research Center of Diabetes and Metabolic Diseases, Jinan, China
- Shandong Key Laboratory of Endocrinology and Lipid Metabolism, Jinan, China
- Shandong Prevention and Control Engineering Laboratory of Endocrine and Metabolic Diseases, Jinan, China
| | - Wenxiu Sun
- Department of Nursing, Taishan Vocational College of Nursing, Taian, China
| | - Yong Yan
- Department of Transfusion Medicine, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, China
| | - Mengzhe Jing
- Department of Endocrinology, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, China
- Shandong Clinical Research Center of Diabetes and Metabolic Diseases, Jinan, China
- Shandong Key Laboratory of Endocrinology and Lipid Metabolism, Jinan, China
- Shandong Prevention and Control Engineering Laboratory of Endocrine and Metabolic Diseases, Jinan, China
| | - Shizhan Ma
- Department of Endocrinology, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, China
- Shandong Clinical Research Center of Diabetes and Metabolic Diseases, Jinan, China
- Shandong Key Laboratory of Endocrinology and Lipid Metabolism, Jinan, China
- Shandong Prevention and Control Engineering Laboratory of Endocrine and Metabolic Diseases, Jinan, China
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3
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Liu J, Lai F, Hou Y, Zheng R. Leptin signaling and leptin resistance. MEDICAL REVIEW (BERLIN, GERMANY) 2022; 2:363-384. [PMID: 37724323 PMCID: PMC10388810 DOI: 10.1515/mr-2022-0017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Accepted: 07/12/2022] [Indexed: 09/20/2023]
Abstract
With the prevalence of obesity and associated comorbidities, studies aimed at revealing mechanisms that regulate energy homeostasis have gained increasing interest. In 1994, the cloning of leptin was a milestone in metabolic research. As an adipocytokine, leptin governs food intake and energy homeostasis through leptin receptors (LepR) in the brain. The failure of increased leptin levels to suppress feeding and elevate energy expenditure is referred to as leptin resistance, which encompasses complex pathophysiological processes. Within the brain, LepR-expressing neurons are distributed in hypothalamus and other brain areas, and each population of the LepR-expressing neurons may mediate particular aspects of leptin effects. In LepR-expressing neurons, the binding of leptin to LepR initiates multiple signaling cascades including janus kinase (JAK)-signal transducers and activators of transcription (STAT) phosphatidylinositol 3-kinase (PI3K)-protein kinase B (AKT), extracellular regulated protein kinase (ERK), and AMP-activated protein kinase (AMPK) signaling, etc., mediating leptin actions. These findings place leptin at the intersection of metabolic and neuroendocrine regulations, and render leptin a key target for treating obesity and associated comorbidities. This review highlights the main discoveries that shaped the field of leptin for better understanding of the mechanism governing metabolic homeostasis, and guides the development of safe and effective interventions to treat obesity and associated diseases.
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Affiliation(s)
- Jiarui Liu
- Department of Anatomy, Histology and Embryology, School of Basic Medical Sciences, Health Science Center, Peking University, Beijing, China
| | - Futing Lai
- Department of Anatomy, Histology and Embryology, School of Basic Medical Sciences, Health Science Center, Peking University, Beijing, China
| | - Yujia Hou
- Department of Anatomy, Histology and Embryology, School of Basic Medical Sciences, Health Science Center, Peking University, Beijing, China
| | - Ruimao Zheng
- Department of Anatomy, Histology and Embryology, School of Basic Medical Sciences, Health Science Center, Peking University, Beijing, China
- Neuroscience Research Institute, Peking University, Beijing, China
- Key Laboratory for Neuroscience of Ministry of Education, Peking University, Beijing, China
- Key Laboratory for Neuroscience of National Health Commission, Peking University, Beijing 100191, China
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4
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Townsend LK, MacPherson REK, Wright DC. New Horizon: Exercise and a Focus on Tissue-Brain Crosstalk. J Clin Endocrinol Metab 2021; 106:2147-2163. [PMID: 33982072 DOI: 10.1210/clinem/dgab333] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/24/2020] [Indexed: 01/03/2023]
Abstract
The world population is aging, leading to increased rates of neurodegenerative disorders. Exercise has countless health benefits and has consistently been shown to improve brain health and cognitive function. The purpose of this review is to provide an overview of exercise-induced adaptations in the brain with a focus on crosstalk between peripheral tissues and the brain. We highlight recent investigations into exercise-induced circulating factors, or exerkines, including irisin, cathepsin B, GPLD1, and ketones and the mechanisms mediating their effects in the brain.
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Affiliation(s)
- Logan K Townsend
- Department of Medicine, McMaster University, Hamilton, L8S 4L8, Canada
- Department of Human Health and Nutritional Science, University of Guelph, Guelph, N1G 2W1, Canada
| | - Rebecca E K MacPherson
- Department of Health Sciences and Centre for Neuroscience, Brock University, St. Catharines, L2S 3A1, Canada
| | - David C Wright
- Department of Human Health and Nutritional Science, University of Guelph, Guelph, N1G 2W1, Canada
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5
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Peng J, Yin L, Wang X. Central and peripheral leptin resistance in obesity and improvements of exercise. Horm Behav 2021; 133:105006. [PMID: 34087669 DOI: 10.1016/j.yhbeh.2021.105006] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/24/2021] [Revised: 04/25/2021] [Accepted: 05/22/2021] [Indexed: 01/16/2023]
Abstract
Obesity is strongly related to leptin resistance that refers to the state in which leptin fails to inhibit appetite, enhance energy expenditure and regulate glycolipid metabolism, whereas decreasing leptin resistance is important for obesity treatment. Leptin resistance that develops in brain and also directly in peripheral tissues is considered as central and peripheral leptin resistance, respectively. The mechanism of central leptin resistance is the focus of intensive studies but still not totally clarified. A challenged notion about the effect of impaired leptin BBB transport emerges and a concept of "selective leptin resistance" is discussed. Peripheral leptin resistance, especially leptin resistance in muscle, has drawn more attention recently, while its mechanism remains unclear. Exercise is an effective way to reduce obesity, which is at least in part due to the alleviation of leptin resistance. Here, we summarized newly discovered data about the associated factors of central leptin resistance and peripheral leptin resistance, and the actions of exercise on leptin resistance, which is important to understand the mechanisms of leptin resistance and exercise-induced alleviation of leptin resistance, and to facilitate clinical application of leptin in obesity treatment.
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Affiliation(s)
- Jin Peng
- School of Kinesiology, Shanghai University of Sport, Shanghai 200438, China
| | - Lijun Yin
- School of Kinesiology, Shanghai University of Sport, Shanghai 200438, China
| | - Xiaohui Wang
- School of Kinesiology, Shanghai University of Sport, Shanghai 200438, China.
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6
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Beaulieu K, Oustric P, Finlayson G. The Impact of Physical Activity on Food Reward: Review and Conceptual Synthesis of Evidence from Observational, Acute, and Chronic Exercise Training Studies. Curr Obes Rep 2020; 9:63-80. [PMID: 32297126 PMCID: PMC7261263 DOI: 10.1007/s13679-020-00372-3] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
PURPOSE OF REVIEW This review brings together current evidence from observational, acute, and chronic exercise training studies to inform public debate on the impact of physical activity and exercise on food reward. RECENT FINDINGS Low levels of physical activity are associated with higher liking and wanting for high-energy food. Acute bouts of exercise tend to reduce behavioral indices of reward for high-energy food in inactive individuals. A dissociation in liking (increase) and wanting (decrease) may occur during chronic exercise training associated with loss of body fat. Habitual moderate-to-vigorous physical activity is associated with lower liking and wanting for high-fat food, and higher liking for low-fat food. Food reward does not counteract the benefit of increasing physical activity levels for obesity management. Exercise training appears to be accompanied by positive changes in food preferences in line with an overall improvement in appetite control.
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Affiliation(s)
- Kristine Beaulieu
- Appetite Control & Energy Balance Research Group, School of Psychology, Faculty of Medicine & Health, University of Leeds, Leeds, West Yorkshire, UK
| | - Pauline Oustric
- Appetite Control & Energy Balance Research Group, School of Psychology, Faculty of Medicine & Health, University of Leeds, Leeds, West Yorkshire, UK
| | - Graham Finlayson
- Appetite Control & Energy Balance Research Group, School of Psychology, Faculty of Medicine & Health, University of Leeds, Leeds, West Yorkshire, UK.
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7
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Homeostatic and non-homeostatic appetite control along the spectrum of physical activity levels: An updated perspective. Physiol Behav 2018; 192:23-29. [DOI: 10.1016/j.physbeh.2017.12.032] [Citation(s) in RCA: 54] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2017] [Revised: 12/19/2017] [Accepted: 12/24/2017] [Indexed: 12/26/2022]
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8
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Beaulieu K, Hopkins M, Blundell J, Finlayson G. Does Habitual Physical Activity Increase the Sensitivity of the Appetite Control System? A Systematic Review. Sports Med 2018; 46:1897-1919. [PMID: 27002623 PMCID: PMC5097075 DOI: 10.1007/s40279-016-0518-9] [Citation(s) in RCA: 84] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Background It has been proposed that habitual physical activity improves appetite control; however, the evidence has never been systematically reviewed. Objective To examine whether appetite control (e.g. subjective appetite, appetite-related peptides, food intake) differs according to levels of physical activity. Data Sources Medline, Embase and SPORTDiscus were searched for articles published between 1996 and 2015, using keywords pertaining to physical activity, appetite, food intake and appetite-related peptides. Study Selection Articles were included if they involved healthy non-smoking adults (aged 18–64 years) participating in cross-sectional studies examining appetite control in active and inactive individuals; or before and after exercise training in previously inactive individuals. Study Appraisal and Synthesis Of 77 full-text articles assessed, 28 studies (14 cross-sectional; 14 exercise training) met the inclusion criteria. Results Appetite sensations and absolute energy intake did not differ consistently across studies. Active individuals had a greater ability to compensate for high-energy preloads through reductions in energy intake, in comparison with inactive controls. When physical activity level was graded across cross-sectional studies (low, medium, high, very high), a significant curvilinear effect on energy intake (z-scores) was observed. Limitations Methodological issues existed concerning the small number of studies, lack of objective quantification of food intake, and various definitions used to define active and inactive individuals. Conclusion Habitually active individuals showed improved compensation for the energy density of foods, but no consistent differences in appetite or absolute energy intake, in comparison with inactive individuals. This review supports a J-shaped relationship between physical activity level and energy intake. Further studies are required to confirm these findings. PROSPERO Registration Number CRD42015019696 Electronic supplementary material The online version of this article (doi:10.1007/s40279-016-0518-9) contains supplementary material, which is available to authorized users.
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Affiliation(s)
| | - Mark Hopkins
- School of Psychology, University of Leeds, Leeds, LS2 9JT, UK.,Academy of Sport and Physical Activity, Sheffield Hallam University, Sheffield, UK
| | - John Blundell
- School of Psychology, University of Leeds, Leeds, LS2 9JT, UK
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9
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Pedroso JAB, de Mendonca POR, Fortes MAS, Tomaz I, Pecorali VL, Auricino TB, Costa IC, Lima LB, Furigo IC, Bueno DN, Ramos-Lobo AM, Lotfi CFP, Donato J. SOCS3 expression in SF1 cells regulates adrenal differentiation and exercise performance. J Endocrinol 2017; 235:207-222. [PMID: 28899903 DOI: 10.1530/joe-17-0255] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/15/2017] [Accepted: 09/12/2017] [Indexed: 12/25/2022]
Abstract
Many hormones/cytokines are secreted in response to exercise and cytokine signaling may play a pivotal role in the training adaptations. To investigate the importance of cytokine signaling during vertical ladder climbing, a resistance exercise model, we produced mice lacking SOCS3 protein exclusively in steroidogenic factor-1 (SF1) cells (SF1 Socs3 KO mice). SF1 expression is found in steroidogenic cells of the adrenal cortex and gonads, as well as in neurons of the ventromedial nucleus of the hypothalamus. Histological markers of the fetal adrenal zone (or X-zone in rodents) were still present in adult males and postpartum SF1 Socs3 KO females, suggesting a previously unrecognized effect of SOCS3 on the terminal differentiation of the adrenal gland. This change led to a distinct distribution of lipid droplets along the adrenal cortex. Under basal conditions, adult SF1 Socs3 KO mice exhibited similar adrenal weight, and plasma ACTH and corticosterone concentrations. Nonetheless, SF1 Socs3 KO mice exhibited a blunted ACTH-induced corticosterone secretion. The overall metabolic responses induced by resistance training remained unaffected in SF1 Socs3 KO mice, including changes in body adiposity, glucose tolerance and energy expenditure. However, training performance and glucose control during intense resistance exercise were impaired in SF1 Socs3 KO mice. Furthermore, a reduced counter-regulatory response to 2-deoxy-d-glucose was observed in mutant mice. These findings revealed a novel participation of SOCS3 regulating several endocrine and metabolic aspects. Therefore, cytokine signaling in SF1 cells exerts an important role to sustain training performance possibly by promoting the necessary metabolic adjustments during exercise.
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Affiliation(s)
- João A B Pedroso
- Department of Physiology and BiophysicsInstitute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Pedro O R de Mendonca
- Department of AnatomyInstitute of Biomedical Science, University of São Paulo, São Paulo, Brazil
| | - Marco A S Fortes
- Department of Physiology and BiophysicsInstitute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Igor Tomaz
- Department of Physiology and BiophysicsInstitute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Vitor L Pecorali
- Department of Physiology and BiophysicsInstitute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Thais B Auricino
- Department of AnatomyInstitute of Biomedical Science, University of São Paulo, São Paulo, Brazil
| | - Ismael C Costa
- Department of AnatomyInstitute of Biomedical Science, University of São Paulo, São Paulo, Brazil
| | - Leandro B Lima
- Department of Physiology and BiophysicsInstitute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Isadora C Furigo
- Department of Physiology and BiophysicsInstitute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Debora N Bueno
- Department of Physiology and BiophysicsInstitute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Angela M Ramos-Lobo
- Department of Physiology and BiophysicsInstitute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Claudimara F P Lotfi
- Department of AnatomyInstitute of Biomedical Science, University of São Paulo, São Paulo, Brazil
| | - Jose Donato
- Department of Physiology and BiophysicsInstitute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
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10
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Ramos-Lobo AM, Donato J. The role of leptin in health and disease. Temperature (Austin) 2017; 4:258-291. [PMID: 28944270 DOI: 10.1080/23328940.2017.1327003] [Citation(s) in RCA: 88] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Revised: 04/27/2017] [Accepted: 05/02/2017] [Indexed: 02/07/2023] Open
Abstract
Leptin is a master regulator of energy balance and body adiposity. Additionally, leptin exerts important control on glucose homeostasis, thermogenesis, autonomic nervous system and neuroendocrine axes. In metabolic diseases, such as obesity and diabetes mellitus, leptin signaling may be compromised, indicating the important role of this hormone in the etiology and pathophysiological manifestations of these conditions. In the present manuscript, we reviewed important concepts of leptin signaling, as well as about the effects of leptin on several biologic functions. We also discussed the possible therapeutic use of leptin administration and how our current obesogenic environment contributes to the development of leptin resistance. Our objective was to provide a comprehensive and state-of-the-art review about the importance of leptin to maintain the homeostasis and during pathological conditions.
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Affiliation(s)
- Angela M Ramos-Lobo
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP, Brazil
| | - Jose Donato
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP, Brazil
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11
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Beaulieu K, Hopkins M, Blundell J, Finlayson G. Impact of physical activity level and dietary fat content on passive overconsumption of energy in non-obese adults. Int J Behav Nutr Phys Act 2017; 14:14. [PMID: 28166797 PMCID: PMC5294904 DOI: 10.1186/s12966-017-0473-3] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2016] [Accepted: 01/31/2017] [Indexed: 01/20/2023] Open
Abstract
Background Passive overconsumption is the increase in energy intake driven by the high-fat energy-dense food environment. This can be explained in part because dietary fat has a weaker effect on satiation (i.e. process that terminates feeding). Habitually active individuals show improved satiety (i.e. process involved in post-meal suppression of hunger) but any improvement in satiation is unknown. Here we examined whether habitual physical activity mitigates passive overconsumption through enhanced satiation in response to a high-fat meal. Methods Twenty-one non-obese individuals with high levels of physical activity (HiPA) and 19 individuals with low levels of physical activity (LoPA) matched for body mass index (mean = 22.8 kg/m2) were recruited. Passive overconsumption was assessed by comparing ad libitum energy intake from covertly manipulated high-fat (HFAT; 50% fat) or high-carbohydrate (HCHO; 70% carbohydrate) meals in a randomized crossover design. Habitual physical activity was assessed using SenseWear accelerometers (SWA). Body composition, resting metabolic rate, eating behaviour traits, fasting appetite-related peptides and hedonic food reward were also measured. Results In the whole sample, passive overconsumption was observed with greater energy intake at HFAT compared to HCHO (p < 0.01), without any differences between activity groups (p > 0.05). SWA confirmed that HiPA were more active than LoPA (p < 0.01). HiPA had lower body fat and greater fat-free mass than LoPA (p < 0.05 for both) but did not differ in resting metabolic rate, eating behaviour traits, appetite-related peptides or food reward (p > 0.05 for all). Conclusions Non-obese individuals with high or low physical activity levels but matched for BMI showed similar susceptibility to passive overconsumption when consuming an ad libitum high-fat compared to a high-carbohydrate meal. This occurred despite increased total daily energy expenditure and improved body composition in HiPA. Greater differences in body composition and/or physical activity levels may be required to impact on satiation. Electronic supplementary material The online version of this article (doi:10.1186/s12966-017-0473-3) contains supplementary material, which is available to authorized users.
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Affiliation(s)
| | - Mark Hopkins
- School of Psychology, University of Leeds, Leeds, LS2 9JT, UK.,School of Food Science & Nutrition, University of Leeds, Leeds, LS2 9JT, UK
| | - John Blundell
- School of Psychology, University of Leeds, Leeds, LS2 9JT, UK
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12
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Sturgeon K, Digiovanni L, Good J, Salvatore D, Fenderson D, Domchek S, Stopfer J, Galantino ML, Bryan C, Hwang WT, Schmitz K. Exercise-Induced Dose-Response Alterations in Adiponectin and Leptin Levels Are Dependent on Body Fat Changes in Women at Risk for Breast Cancer. Cancer Epidemiol Biomarkers Prev 2016; 25:1195-200. [DOI: 10.1158/1055-9965.epi-15-1087] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2015] [Accepted: 04/03/2016] [Indexed: 11/16/2022] Open
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13
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Wada T, Sunaga H, Miyata K, Shirasaki H, Uchiyama Y, Shimba S. Aryl Hydrocarbon Receptor Plays Protective Roles against High Fat Diet (HFD)-induced Hepatic Steatosis and the Subsequent Lipotoxicity via Direct Transcriptional Regulation of Socs3 Gene Expression. J Biol Chem 2016; 291:7004-16. [PMID: 26865635 DOI: 10.1074/jbc.m115.693655] [Citation(s) in RCA: 94] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2015] [Indexed: 11/06/2022] Open
Abstract
Aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor regulating the expression of genes involved in xenobiotic response. Recent studies have suggested that AhR plays essential roles not only in xenobiotic detoxification but also energy metabolism. Thus, in this study, we studied the roles of AhR in lipid metabolism. Under high fat diet (HFD) challenge, liver-specific AhR knock-out (AhR LKO) mice exhibited severe steatosis, inflammation, and injury in the liver. Gene expression analysis and biochemical study revealed thatde novolipogenesis activity was significantly increased in AhR LKO mice. In contrast, induction of suppressor of cytokine signal 3 (Socs3) expression by HFD was attenuated in the livers of AhR LKO mice. Rescue of theSocs3gene in the liver of AhR LKO mice cancelled the HFD-induced hepatic lipotoxicities. Promoter analysis established Socs3 as novel transcriptional target of AhR. These results indicated that AhR plays a protective role against HFD-induced hepatic steatosis and the subsequent lipotoxicity effects, such as inflammation, and that the mechanism of protection involves the direct transcriptional regulation ofSocs3expression by AhR.
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Affiliation(s)
- Taira Wada
- From the Department of Health Science, School of Pharmacy, Nihon University, Funabashi, Chiba 274-8555, Japan
| | - Hiroshi Sunaga
- From the Department of Health Science, School of Pharmacy, Nihon University, Funabashi, Chiba 274-8555, Japan
| | - Kazuki Miyata
- From the Department of Health Science, School of Pharmacy, Nihon University, Funabashi, Chiba 274-8555, Japan
| | - Haruno Shirasaki
- From the Department of Health Science, School of Pharmacy, Nihon University, Funabashi, Chiba 274-8555, Japan
| | - Yuki Uchiyama
- From the Department of Health Science, School of Pharmacy, Nihon University, Funabashi, Chiba 274-8555, Japan
| | - Shigeki Shimba
- From the Department of Health Science, School of Pharmacy, Nihon University, Funabashi, Chiba 274-8555, Japan
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14
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Coles CA. Adipokines in Healthy Skeletal Muscle and Metabolic Disease. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 900:133-60. [DOI: 10.1007/978-3-319-27511-6_6] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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15
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Santoro A, Mattace Raso G, Meli R. Drug targeting of leptin resistance. Life Sci 2015; 140:64-74. [DOI: 10.1016/j.lfs.2015.05.012] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Revised: 05/06/2015] [Accepted: 05/13/2015] [Indexed: 12/21/2022]
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16
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Influence of habitual physical activity on gastric emptying in healthy males and relationships with body composition and energy expenditure. Br J Nutr 2015; 114:489-96. [PMID: 26168984 DOI: 10.1017/s0007114515002044] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Although a number of studies have examined the role of gastric emptying (GE) in obesity, the influences of habitual physical activity level, body composition and energy expenditure (EE) on GE have received very little consideration. In the present study, we compared GE in active and inactive males, and characterised relationships with body composition (fat mass and fat-free mass) and EE. A total of forty-four males (active n 22, inactive n 22; BMI 21-36 kg/m2; percentage of fat mass 9-42%) were studied, with GE of a standardised (1676 kJ) pancake meal being assessed by the [13C]octanoic acid breath test, body composition by air displacement plethysmography, RMR by indirect calorimetry, and activity EE (AEE) by accelerometry. The results showed that GE was faster in active compared with inactive males (mean half-time (t 1/2): active 157 (sd 18) and inactive 179 (sd 21) min, P< 0.001). When data from both groups were pooled, GE t 1/2 was associated with percentage of fat mass (r 0.39, P< 0.01) and AEE (r - 0.46, P< 0.01). After controlling for habitual physical activity status, the association between AEE and GE remained, but not that for percentage of fat mass and GE. BMI and RMR were not associated with GE. In summary, faster GE is considered to be a marker of a habitually active lifestyle in males, and is associated with a higher AEE level and a lower percentage of fat mass. The possibility that GE contributes to a gross physiological regulation (or dysregulation) of food intake with physical activity level deserves further investigation.
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Suppressor of cytokine signalling (SOCS) proteins as guardians of inflammatory responses critical for regulating insulin sensitivity. Biochem J 2014; 461:177-88. [PMID: 24966052 DOI: 10.1042/bj20140143] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Overactivation of immune pathways in obesity is an important cause of insulin resistance and thus new approaches aimed to limit inflammation or its consequences may be effective for treating Type 2 diabetes. The SOCS (suppressors of cytokine signalling) are a family of proteins that play an essential role in mediating inflammatory responses in both immune cells and metabolic organs such as the liver, adipose tissue and skeletal muscle. In the present review we discuss the role of SOCS1 and SOCS3 in controlling immune cells such as macrophages and T-cells and the impact this can have on systemic inflammation and insulin resistance. We also dissect the mechanisms by which SOCS (1-7) regulate insulin signalling in different tissues including their impact on the insulin receptor and insulin receptor substrates. Lastly, we discuss the important findings from SOCS whole-body and tissue-specific null mice, which implicate an important role for these proteins in controlling insulin action and glucose homoeostasis in obesity.
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Ferrante MC, Amero P, Santoro A, Monnolo A, Simeoli R, Di Guida F, Mattace Raso G, Meli R. Polychlorinated biphenyls (PCB 101, PCB 153 and PCB 180) alter leptin signaling and lipid metabolism in differentiated 3T3-L1 adipocytes. Toxicol Appl Pharmacol 2014; 279:401-408. [PMID: 24978599 DOI: 10.1016/j.taap.2014.06.016] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2014] [Revised: 06/11/2014] [Accepted: 06/18/2014] [Indexed: 11/28/2022]
Abstract
Non-dioxin-like polychlorinated biphenyls (NDL-PCBs) are highly lipophilic environmental contaminants that accumulate in lipid-rich tissues, such as adipose tissue. Here, we reported the effects induced by PCBs 101, 153 and 180, three of the six NDL-PCBs defined as indicators, on mature 3T3-L1 adipocytes. We observed an increase in lipid content, in leptin gene expression and a reduction of leptin receptor expression and signaling, when cells were exposed to PCBs, alone or in combination. These modifications were consistent with the occurrence of "leptin-resistance" in adipose tissue, a typical metabolic alteration related to obesity. Therefore, we investigated how PCBs affect the expression of pivotal proteins involved in the signaling of leptin receptor. We evaluated the PCB effect on the intracellular pathway JAK/STAT, determining the phosphorylation of STAT3, a downstream activator of the transcription of leptin gene targets, and the expression of SOCS3 and PTP1B, two important regulators of leptin resistance. In particular, PCBs 153 and 180 or all PCB combinations induced a significant reduction in pSTAT3/STAT3 ratio and an increase in PTP1B and SOCS3, evidencing an additive effect. The impairment of leptin signaling was associated with the reduction of AMPK/ACC pathway activation, leading to the increase in lipid content. These pollutants were also able to increase the transcription of inflammatory cytokines (IL-6 and TNFα). It is worthy to note that the PCB concentrations used are comparable to levels detectable in human adipose tissue. Our data strongly support the hypothesis that NDL-PCBs may interfere with the lipid metabolism contributing to the development of obesity and related diseases.
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Affiliation(s)
- Maria C Ferrante
- Department of Veterinary Medicine and Animal Productions, Federico II University of Naples, Via Delpino 1, 80137 Naples, Italy
| | - Paola Amero
- Department of Pharmacy, Federico II University of Naples, Via Montesano 49, 80131 Naples, Italy
| | - Anna Santoro
- Department of Pharmacy, Federico II University of Naples, Via Montesano 49, 80131 Naples, Italy
| | - Anna Monnolo
- Department of Veterinary Medicine and Animal Productions, Federico II University of Naples, Via Delpino 1, 80137 Naples, Italy
| | - Raffaele Simeoli
- Department of Pharmacy, Federico II University of Naples, Via Montesano 49, 80131 Naples, Italy
| | - Francesca Di Guida
- Department of Pharmacy, Federico II University of Naples, Via Montesano 49, 80131 Naples, Italy
| | - Giuseppina Mattace Raso
- Department of Pharmacy, Federico II University of Naples, Via Montesano 49, 80131 Naples, Italy.
| | - Rosaria Meli
- Department of Pharmacy, Federico II University of Naples, Via Montesano 49, 80131 Naples, Italy.
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Kaya MS, Bayıroglu F, Mis L, Kilinc D, Comba B. In case of obesity, longevity-related mechanisms lead to anti-inflammation. AGE (DORDRECHT, NETHERLANDS) 2014; 36:677-687. [PMID: 24306820 PMCID: PMC4039259 DOI: 10.1007/s11357-013-9598-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2013] [Accepted: 11/04/2013] [Indexed: 06/02/2023]
Abstract
The exact mechanisms which contribute to longevity have not been figured out yet. Our aim was to find out a common way for prompting longevity by bringing together the well-known applications such as food restriction, exercise, and probiotic supplementing in an experimental obesity model. Experimental obesity was promoted in a total of 32 young (2 months old) and 32 aged (16 months old) male Wistar albino rats through 8-week cafeteria diet (salami, chocolate, chips, and biscuits). Old and young animals were divided into groups each consisting of eight animals and also divided into four subgroups as obese control, obese food restriction, obese probiotic-fed and obese exercise groups. Probiotic group diet contained 0.05 %w/total diet inactive and lyophilized Lactobacillus casei str. Shirota. The exercise group was subjected to treadmill running 1 h/day, at 21 m/min and at an uphill incline of 15 % for 5 days a week. Food restriction group was formed by giving 40 % less food than the others. The control group was fed regular pellet feed ad libitum. This program was continued for 16 weeks. Blood samples from all the groups were analyzed for fasting glucose, insulin, IGF-1, insulin-like growth factor binding protein 3 (IGFBP-3), interleukin (IL)-6, IL-12, malondialdehyde (MDA), fT3, TT3, fT4, TT4, and liver tissue MDA levels were measured. All applications showed anti-inflammatory effects through the observed changes in the levels of IGFBP-3, IL-6, and IL-12 in the young and old obese rats. While the interventions normally contribute to longevity by recruiting different action mechanisms, anti-inflammatory effect is the only mode of action for all the applications in the obesity model.
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Affiliation(s)
- Mehmet Salih Kaya
- />Department of Physiology, University of Dicle, Campus, Diyarbakir, 21280 Turkey
| | - Fahri Bayıroglu
- />Department of Physiology, University of Yuzuncu Yil, Campus, Van, 65080 Turkey
- />University of Ağrı İbrahim Çeçen, Agri, Turkey
| | - Leyla Mis
- />Department of Physiology, University of Yuzuncu Yil, Campus, Van, 65080 Turkey
| | - Dide Kilinc
- />Department of Physiology, University of Yuzuncu Yil, Campus, Van, 65080 Turkey
| | - Bahat Comba
- />Department of Physiology, University of Yuzuncu Yil, Campus, Van, 65080 Turkey
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Guerra B, Ponce-González JG, Morales-Alamo D, Guadalupe-Grau A, Kiilerich K, Fuentes T, Ringholm S, Biensø RS, Santana A, Lundby C, Pilegaard H, Calbet JAL. Leptin signaling in skeletal muscle after bed rest in healthy humans. Eur J Appl Physiol 2013; 114:345-57. [PMID: 24292882 DOI: 10.1007/s00421-013-2779-4] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2013] [Accepted: 11/18/2013] [Indexed: 12/22/2022]
Abstract
PURPOSE This study aimed at determining the effects of bed rest on the skeletal muscle leptin signaling system. METHODS Deltoid and vastus lateralis muscle biopsies and blood samples were obtained from 12 healthy young men (mean ± SD, BMI 22.8 ± 2.7 kg/m(2)) before and after 7 days of bed rest. Leptin receptor isoforms (OB-Rs), suppressor of cytokine signaling 3 (SOCS3) and protein tyrosine phosphatase 1B (PTP1B) protein expression and signal transducer and activator of transcription 3 (STAT3) phosphorylation were analyzed by Western blot. RESULTS After bed rest basal insulin concentration was increased by 53% (P < 0.05), the homeostasis model assessment (HOMA) by 40% (P < 0.05), and serum leptin concentration by 35% (P < 0.05) with no changes in body fat mass. Although the soluble isoform of the leptin receptor (s-OBR) remained unchanged, the molar excess of leptin over sOB-R was increased by 1.4-fold after bed rest (P < 0.05). OB-Rs and SOCS3 protein expression, and STAT3 phosphorylation level remained unaffected in deltoid and vastus lateralis by bed rest, as PTP1B in the deltoid. PTP1B was increased by 90% with bed rest in the vastus lateralis (P < 0.05). There was a linear relationship between the increase in vastus lateralis PTP1B and the increase in both basal insulin concentrations (r = 0.66, P < 0.05) and HOMA (r = 0.68, P < 0.05) with bed rest. CONCLUSIONS One week of bed rest is associated with increased leptin levels without augmenting STAT3 phosphorylation indicating some degree of leptin resistance in skeletal muscle, which can be explained, at least in part, by an elevation of PTP1B protein content in the vastus lateralis muscle.
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Affiliation(s)
- Borja Guerra
- Departamento de Educación Física, University of Las Palmas de Gran Canaria, Campus Universitario de Tafira, 35017, Las Palmas de Gran Canaria, Canary Island, Spain,
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Roberts CK, Hevener AL, Barnard RJ. Metabolic syndrome and insulin resistance: underlying causes and modification by exercise training. Compr Physiol 2013; 3:1-58. [PMID: 23720280 DOI: 10.1002/cphy.c110062] [Citation(s) in RCA: 264] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Metabolic syndrome (MS) is a collection of cardiometabolic risk factors that includes obesity, insulin resistance, hypertension, and dyslipidemia. Although there has been significant debate regarding the criteria and concept of the syndrome, this clustering of risk factors is unequivocally linked to an increased risk of developing type 2 diabetes and cardiovascular disease. Regardless of the true definition, based on current population estimates, nearly 100 million have MS. It is often characterized by insulin resistance, which some have suggested is a major underpinning link between physical inactivity and MS. The purpose of this review is to: (i) provide an overview of the history, causes and clinical aspects of MS, (ii) review the molecular mechanisms of insulin action and the causes of insulin resistance, and (iii) discuss the epidemiological and intervention data on the effects of exercise on MS and insulin sensitivity.
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Affiliation(s)
- Christian K Roberts
- Exercise and Metabolic Disease Research Laboratory, Translational Sciences Section, School of Nursing, University of California at Los Angeles, Los Angeles, California, USA.
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22
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Timing of maternal exposure to a high fat diet and development of obesity and hyperinsulinemia in male rat offspring: same metabolic phenotype, different developmental pathways? J Nutr Metab 2013; 2013:517384. [PMID: 23762542 PMCID: PMC3666195 DOI: 10.1155/2013/517384] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2013] [Revised: 04/08/2013] [Accepted: 04/20/2013] [Indexed: 12/22/2022] Open
Abstract
Objective. Offspring born to mothers either fed an obesogenic diet throughout their life or restricted to pregnancy and lactation demonstrate obesity, hyperinsulinemia, and hyperleptinemia, irrespective of their postweaning diet. We examined whether timing of a maternal obesogenic diet results in differential regulation of pancreatic adipoinsular and inflammatory signaling pathways in offspring. Methods. Female Wistar rats were randomized into 3 groups: (1) control (CONT): fed a control diet preconceptionally and during pregnancy and lactation; (2) maternal high fat (MHF): fed an HF diet throughout their life and during pregnancy and lactation; (3) pregnancy and lactation HF (PLHF): fed a control diet throughout life until mating, then HF diet during pregnancy and lactation. Male offspring were fed the control diet postweaning. Plasma and pancreatic tissue were collected, and mRNA concentrations of key factors regulating adipoinsular axis signaling were determined. Results. MHF and PLHF offspring exhibited increased adiposity and were hyperinsulinemic and hyperleptinemic compared to CONT. Despite a similar anthropometric phenotype, MHF and PLHF offspring exhibited distinctly different expression for key pancreatic genes, dependent upon maternal preconceptional nutritional background. Conclusions. These data suggest that despite using differential signaling pathways, obesity in offspring may be an adaptive outcome of early life exposure to HF during critical developmental windows.
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O'Neill HM, Holloway GP, Steinberg GR. AMPK regulation of fatty acid metabolism and mitochondrial biogenesis: implications for obesity. Mol Cell Endocrinol 2013; 366:135-51. [PMID: 22750049 DOI: 10.1016/j.mce.2012.06.019] [Citation(s) in RCA: 241] [Impact Index Per Article: 21.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/10/2011] [Revised: 03/13/2012] [Accepted: 06/21/2012] [Indexed: 12/25/2022]
Abstract
Skeletal muscle plays an important role in regulating whole-body energy expenditure given it is a major site for glucose and lipid oxidation. Obesity and type 2 diabetes are causally linked through their association with skeletal muscle insulin resistance, while conversely exercise is known to improve whole body glucose homeostasis simultaneously with muscle insulin sensitivity. Exercise activates skeletal muscle AMP-activated protein kinase (AMPK). AMPK plays a role in regulating exercise capacity, skeletal muscle mitochondrial content and contraction-stimulated glucose uptake. Skeletal muscle AMPK is also thought to be important for regulating fatty acid metabolism; however, direct genetic evidence in this area is currently lacking. This review will discuss the current paradigms regarding the influence of AMPK in regulating skeletal muscle fatty acid metabolism and mitochondrial biogenesis at rest and during exercise, and highlight the potential implications in the development of insulin resistance.
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Affiliation(s)
- Hayley M O'Neill
- University of Melbourne, Department of Medicine, St. Vincent's Institute of Medical Research, Melbourne, Victoria, Australia.
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Yi X, Cao S, Chang B, Zhao D, Gao H, Wan Y, Shi J, Wei W, Guan Y. Effects of acute exercise and chronic exercise on the liver leptin-AMPK-ACC signaling pathway in rats with type 2 diabetes. J Diabetes Res 2013; 2013:946432. [PMID: 24455748 PMCID: PMC3877642 DOI: 10.1155/2013/946432] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/13/2013] [Revised: 11/01/2013] [Accepted: 11/01/2013] [Indexed: 01/06/2023] Open
Abstract
AIM To investigate the effects of acute and chronic exercise on glucose and lipid metabolism in liver of rats with type 2 diabetes caused by a high fat diet and low dose streptozotocin (STZ). METHODS Animals were classified into control (CON), diabetes (DC), diabetic chronic exercise (DCE), and diabetic acute exercise (DAE) groups. RESULTS Compared to CON, the leptin levels in serum and liver and ACC phosphorylation were significantly higher in DC, but the levels of liver leptin receptor, AMPK α 1/2, AMPK α 1, and ACC proteins expression and phosphorylation were significantly lower in DC. In addition, the levels of liver glycogen reduced significantly, and the levels of TG and FFA increased significantly in DC compared to CON. Compared to DC, the levels of liver AMPK α 1/2, AMPK α 2, AMPK α 1, and ACC phosphorylation significantly increased in DCE and DAE. However, significant increase of the level of liver leptin receptor and glycogen as well as significant decrease of the level of TG and FFA were observed only in DEC. CONCLUSION Our study demonstrated that both acute and chronic exercise indirectly activated the leptin-AMPK-ACC signaling pathway and increased insulin sensitivity in the liver of type 2 diabetic rats. However, only chronic and long-term exercise improved glucose and lipid metabolism of the liver.
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Affiliation(s)
- Xuejie Yi
- Department of Biochemistry and Molecular Biology, College of Basic Medical Sciences, China Medical University, Shenyang 110001, China
- Department of Exercise Science, Shenyang Sport University, Shenyang, China
| | - Shicheng Cao
- Department of Sport Medicine, College of Basic Medical Sciences, China Medical University, Shenyang, China
| | - Bo Chang
- Department of Exercise Science, Shenyang Sport University, Shenyang, China
| | - Dalin Zhao
- Department of Exercise Science, Shenyang Sport University, Shenyang, China
| | - Haining Gao
- Department of Exercise Science, Shenyang Sport University, Shenyang, China
| | - Yihan Wan
- Department of Exercise Science, Shenyang Sport University, Shenyang, China
| | - Jiaojiao Shi
- Department of Exercise Science, Shenyang Sport University, Shenyang, China
| | - Wei Wei
- Department of Exercise Science, Shenyang Sport University, Shenyang, China
| | - Yifu Guan
- Department of Biochemistry and Molecular Biology, College of Basic Medical Sciences, China Medical University, Shenyang 110001, China
- *Yifu Guan:
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Jorgensen SB, O'Neill HM, Sylow L, Honeyman J, Hewitt KA, Palanivel R, Fullerton MD, Öberg L, Balendran A, Galic S, van der Poel C, Trounce IA, Lynch GS, Schertzer JD, Steinberg GR. Deletion of skeletal muscle SOCS3 prevents insulin resistance in obesity. Diabetes 2013; 62:56-64. [PMID: 22961088 PMCID: PMC3526029 DOI: 10.2337/db12-0443] [Citation(s) in RCA: 113] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Obesity is associated with chronic low-grade inflammation that contributes to defects in energy metabolism and insulin resistance. Suppressor of cytokine signaling (SOCS)-3 expression is increased in skeletal muscle of obese humans. SOCS3 inhibits leptin signaling in the hypothalamus and insulin signal transduction in adipose tissue and the liver. Skeletal muscle is an important tissue for controlling energy expenditure and whole-body insulin sensitivity; however, the physiological importance of SOCS3 in this tissue has not been examined. Therefore, we generated mice that had SOCS3 specifically deleted in skeletal muscle (SOCS MKO). The SOCS3 MKO mice had normal muscle development, body mass, adiposity, appetite, and energy expenditure compared with wild-type (WT) littermates. Despite similar degrees of obesity when fed a high-fat diet, SOCS3 MKO mice were protected against the development of hyperinsulinemia and insulin resistance because of enhanced skeletal muscle insulin receptor substrate 1 (IRS1) and Akt phosphorylation that resulted in increased skeletal muscle glucose uptake. These data indicate that skeletal muscle SOCS3 does not play a critical role in regulating muscle development or energy expenditure, but it is an important contributing factor for inhibiting insulin sensitivity in obesity. Therapies aimed at inhibiting SOCS3 in skeletal muscle may be effective in reversing obesity-related glucose intolerance and insulin resistance.
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Affiliation(s)
- Sebastian Beck Jorgensen
- St. Vincent’s Institute of Medical Research and Department of Medicine, University of Melbourne, Fitzroy, Victoria, Australia.
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Palanivel R, Fullerton MD, Galic S, Honeyman J, Hewitt KA, Jorgensen SB, Steinberg GR. Reduced Socs3 expression in adipose tissue protects female mice against obesity-induced insulin resistance. Diabetologia 2012; 55:3083-93. [PMID: 22872213 PMCID: PMC5233443 DOI: 10.1007/s00125-012-2665-3] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/09/2012] [Accepted: 06/18/2012] [Indexed: 01/08/2023]
Abstract
AIMS/HYPOTHESIS Inflammation in obesity increases the levels of the suppressor of cytokine signalling-3 (SOCS3) protein in adipose tissue, but the physiological importance of this protein in regulating whole-body insulin sensitivity in obesity is not known. METHODS We generated Socs3 floxed (wild-type, WT) and Socs3 aP2 (also known as Fabp4)-Cre null (Socs3 AKO) mice. Mice were maintained on either a regular chow or a high-fat diet (HFD) for 16 weeks during which time body mass, adiposity, glucose homeostasis and insulin sensitivity were assessed. RESULTS The HFD increased SOCS3 levels in adipose tissue of WT but not Socs3 AKO mice. WT and Socs3 AKO mice had similar body mass and adiposity, assessed using computed tomography (CT) imaging, irrespective of diet or sex. On a control chow diet there were no differences in insulin sensitivity or glucose tolerance. When fed a HFD, female but not male Socs3 AKO mice had improved glucose tolerance as well as lower fasting glucose and insulin levels compared with WT littermates. Hyperinsulinaemic-euglycaemic clamps and positron emission tomography (PET) imaging demonstrated that improved insulin sensitivity was due to elevated adipose tissue glucose uptake. Increased insulin-stimulated glucose uptake in adipose tissue was associated with enhanced levels and activating phosphorylation of insulin receptor substrate-1 (IRS1). CONCLUSIONS/INTERPRETATION These data demonstrate that inhibiting SOCS3 production in adipose tissue of female mice is effective for improving whole-body insulin sensitivity in obesity.
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Affiliation(s)
- R Palanivel
- Division of Endocrinology and Metabolism, Department of Medicine, McMaster University, 1280 Main St West, Hamilton, ON, Canada L8N 3Z5
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Zolotnik IA, Figueroa TY, Yaspelkis BB. Insulin receptor and IRS-1 co-immunoprecipitation with SOCS-3, and IKKα/β phosphorylation are increased in obese Zucker rat skeletal muscle. Life Sci 2012; 91:816-22. [PMID: 22982470 DOI: 10.1016/j.lfs.2012.08.038] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2012] [Revised: 07/27/2012] [Accepted: 08/27/2012] [Indexed: 01/21/2023]
Abstract
AIMS We evaluated if selected pro-inflammatory cytokines and/or the protein suppressor of cytokine signaling 3 (SOCS-3) could account for decreased insulin-stimulated phosphatidylinositol 3-kinase (PI3-K) activity in the skeletal muscle of the obese Zucker rat. MAIN METHODS Eight lean and eight obese Zucker rats ~4weeks of age were obtained and allowed to feed ad libitum for 4weeks before undergoing hind limb perfusion in the presence of 500μU/ml insulin. KEY FINDINGS Insulin-stimulated skeletal muscle PI3-K activity and 3-O-methylglucose transport rates were reduced (P<0.05) in obese compared to lean animals. IRS-1 concentration remained unchanged although IRS-1 tyrosine phosphorylation was decreased (P<0.05), and IRS-1 serine phosphorylation (pS) was increased (P<0.05) in obese animals compared to lean animals. IKKα/β pS and JNK theronine/tyrosine phosphorylation was increased (P<0.05) in the obese animals. IκBα concentration was decreased (P<0.05) and IκBα pS was increased (P<0.05) in the obese compared to lean Zucker animals. SOCS-3 concentration and SOCS-3 co-immunoprecipitation with both insulin receptor β-subunit (IR-β) and IRS-1 were elevated (P<0.05) in obese compared to lean animals. IRS-1 co-immunoprecipitation with IR-β was reduced 56% in the obese animals. SIGNIFICANCE Increased IKKα/β and JNK serine phosphorylation may contribute to increasing IRS-1 serine phosphorylation, while concurrent co-localization of SOCS-3 with both IR-β and IRS-1 may prevent IRS-1 from interacting with IR-β. These two mechanisms thusly may independently contribute to impairing insulin-stimulated PI3-K activation in the skeletal muscle of the obese Zucker rat.
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Affiliation(s)
- Ilya A Zolotnik
- Exercise Biochemistry Laboratory, Department of Kinesiology, California State University Northridge, CA 91330, USA
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Harwood HJ. The adipocyte as an endocrine organ in the regulation of metabolic homeostasis. Neuropharmacology 2012; 63:57-75. [DOI: 10.1016/j.neuropharm.2011.12.010] [Citation(s) in RCA: 157] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2011] [Revised: 11/28/2011] [Accepted: 12/09/2011] [Indexed: 02/06/2023]
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Harris RBS, Apolzan JW. Changes in glucose tolerance and leptin responsiveness of rats offered a choice of lard, sucrose, and chow. Am J Physiol Regul Integr Comp Physiol 2012; 302:R1327-39. [PMID: 22496363 DOI: 10.1152/ajpregu.00477.2011] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Rats offered chow, lard, and 30% sucrose solution (choice) rapidly become obese. We tested metabolic disturbances in rats offered choice, chow+lard, or chow+30% sucrose solution [chow+liquid sucrose (LS)] and compared them with rats fed a composite 60% kcal fat, 7% sucrose diet [high-fat diet (HFD)], or a 10% kcal fat, 35% sucrose diet [low-fat diet (LFD)]. Choice rats had the highest energy intake, but HFD rats gained the most weight. After 23 days carcass fat was the same for choice, HFD, chow+lard, and chow+LS groups. Glucose clearance was the same for all groups during an intraperitoneal glucose tolerance test (GTT) on day 12, but fasting insulin was increased in choice, LFD fed, and chow+LS rats. By contrast, only choice and chow+LS rats were resistant to an intraperitoneal injection of 2 mg leptin/kg on day 17. In experiment 2 choice rats were insulin insensitive during an intraperitoneal GTT, but this was corrected in an oral GTT due to GLP-1 release. UCP-1 protein was increased in brown fat and inguinal white fat in choice rats, and this was associated with a significant increase in energy expenditure of choice rats during the dark period whether expenditure was expressed on a per animal or a metabolic body size basis. The increase in expenditure obviously was not great enough to prevent development of obesity. Further studies are required to determine the mechanistic basis of the rapid onset of leptin resistance in choice rats and how consumption of sucrose solution drives this process.
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Affiliation(s)
- Ruth B S Harris
- Dept. of Physiology, Georgia Health Sciences Univ., 1120 15th St., Augusta, GA 30912, USA.
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Cruz IS, Rosa G, Valle V, Mello DBD, Fortes M, Dantas EH. Efeitos agudos do treinamento concorrente sobre os níveis séricos de leptina e cortisol em adultos jovens sobrepesados. REV BRAS MED ESPORTE 2012. [DOI: 10.1590/s1517-86922012000200003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
OBJETIVO: Este estudo teve como objetivo analisar os efeitos imediatos do treinamento concorrente sobre a leptina e os níveis de cortisol em adultos jovens com sobrepeso. MÉTODOS: Este estudo utilizou uma metodologia quase-experimental. Foram 20 indivíduos voluntários de ambos os sexos, divididos em um grupo sobrepesado treinamento (GST n = 10) e um grupo sobrepesado controle (n = 10). A coleta de sangue foi realizada com os indivíduos em repouso após jejum de 12 horas. Os níveis de leptina e cortisol foram analisados por radioimunoensaio e ensaio por quimioluminescência chimiluminescence antes e imediatamente após o treinamento. ANOVA two way foi utilizada para análise estatística com nível de significância de p < 0,05. RESULTADOS: Na análise da leptina sérica, observou-se diferença significativa intergrupos (GST x GSC) nos momentos pré-intervenção (p = 0,02) e pós-intervenção (p = 0,01). Na análise intragrupos, não foram observadas alterações significativas. E na análise do cortisol sérico intergrupos (GST x GSC), foi observada uma diferença significativa nos momentos pré-intervenção (p = 0,01) e pós-intervenção (p = 0,01), porém, na análise intragrupos, não houve alterações significativas. CONCLUSÃO: Uma única sessão de treinamento concorrente não é suficiente para promover alterações agudas nos níveis de leptina e cortisol dos jovens adultos sobrepesados voluntários deste estudo.
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Affiliation(s)
- Iara S. Cruz
- Universidade Federal do Estado do Rio de Janeiro, Brasil; Universidade Católica Nuestra Señora de Assunção
| | - Guilherme Rosa
- Universidade Federal do Estado do Rio de Janeiro, Brasil; Universidade Católica Nuestra Señora de Assunção
| | - Valeria Valle
- Universidade Federal do Estado do Rio de Janeiro, Brasil
| | - Danielli B. de Mello
- Universidade Federal do Estado do Rio de Janeiro, Brasil; Escola de Educação Física do Exército, Brasil
| | - Marcos Fortes
- Universidade Federal do Estado do Rio de Janeiro, Brasil; Escola de Educação Física do Exército, Brasil
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Zhao J, Tian Y, Xu J, Liu D, Wang X, Zhao B. Endurance exercise is a leptin signaling mimetic in hypothalamus of Wistar rats. Lipids Health Dis 2011; 10:225. [PMID: 22136466 PMCID: PMC3248031 DOI: 10.1186/1476-511x-10-225] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2011] [Accepted: 12/02/2011] [Indexed: 01/22/2023] Open
Abstract
BACKGROUND Endurance exercise is known to promote a substantial effect on the energy balance in rats and humans. However, little is known about the exact mechanisms for the appetite-suppressive effects of endurance exercise. We hypothesized that endurance training might activate signaling cascades in the hypothalamus known to be involved in leptin signaling. METHODS 16 male Wistar rats were randomly assigned to two groups: sedentary (n = 8) and exercise groups (n = 8). Animals in the exercise group started treadmill running at 30 m/min, 0% grade, for 1 min/bout. Running time was gradually increased by 2 min/bout every day. The training plan was one bout per day during initial two weeks, and two bouts per day during 3rd-9th week. At the end of nine-week experiment, blood was analyzed for low-density lipoprotein cholesterol (LDL-C), triglyceride (TG), total cholesterol (TC), free fatty acid (FFA), interleukin (IL)-6, and leptin in both groups. Activations of janus kinase 2-signaling transducer and activator of transcription 3 (JAK2-STAT3), protein kinase B (Akt), extracellular regulated kninase (ERKs), and suppressor of cytokine signaling 3 (SOCS3) in hypothalamus were measured in the end of nine weeks of exercise protocol. RESULTS Nine-week endurance exercise induced lower concentrations of LDL-C, TG, TC, FFA, and leptin in rats (P < 0.05 or P < 0.01). Nine-week endurance exercise significantly increased the circulating IL-6 concentration compared with sedentary group (239.6 ± 37.2 pg/ml vs. 151.8 ± 31.5 pg/ml, P < 0.01). Exercise rats showed significant increases in JAK2, STAT3, Akt, ERKs, and SOCS3 phosphorylations compared with sedentary rats (P < 0.01). CONCLUSION The data suggest that endurance exercise is a leptin signaling mimetic in hypothalamus of Wistar rats.
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Affiliation(s)
- Jiexiu Zhao
- Sport Biological Center, China Institute of Sport Science, Beijing 100061, PR China
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Guerra B, Olmedillas H, Guadalupe-Grau A, Ponce-González JG, Morales-Alamo D, Fuentes T, Chapinal E, Fernández-Pérez L, De Pablos-Velasco P, Santana A, Calbet JAL. Is sprint exercise a leptin signaling mimetic in human skeletal muscle? J Appl Physiol (1985) 2011; 111:715-25. [PMID: 21659488 DOI: 10.1152/japplphysiol.00805.2010] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
This study was designed to determine whether sprint exercise activates signaling cascades linked to leptin actions in human skeletal muscle and how this pattern of activation may be interfered by glucose ingestion. Muscle biopsies were obtained in 15 young healthy men in response to a 30-s sprint exercise (Wingate test) randomly distributed into two groups: the fasting (n = 7, C) and the glucose group (n = 8, G), who ingested 75 g of glucose 1 h before the Wingate test. Exercise elicited different patterns of JAK2, STAT3, STAT5, ERK1/2, p38 MAPK phosphorylation, and SOCS3 protein expression during the recovery period after glucose ingestion. Thirty minutes after the control sprint, STAT3 and ERK1/2 phosphorylation levels were augmented (both, P < 0.05). SOCS3 protein expression was increased 120 min after the control sprint but PTP1B protein expression was unaffected. Thirty and 120 min after the control sprint, STAT5 phosphorylation was augmented (P < 0.05). Glucose abolished the 30 min STAT3 and ERK1/2 phosphorylation and the 120 min SOCS3 protein expression increase while retarding the STAT5 phosphorylation response to sprint. Activation of these signaling cascades occurred despite a reduction of circulating leptin concentration after the sprint. Basal JAK2 and p38 MAPK phosphorylation levels were reduced and increased (both P < 0.05), respectively, by glucose ingestion prior to exercise. During recovery, JAK2 phosphorylation was unchanged and p38 MAPK phosphorylation was transiently reduced when the exercise was preceded by glucose ingestion. In conclusion, sprint exercise performed under fasting conditions is a leptin signaling mimetic in human skeletal muscle.
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Affiliation(s)
- Borja Guerra
- Department of Physical Education, University of Las Palmas de Gran Canaria, Spain
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Qi Z, He J, Zhang Y, Shao Y, Ding S. Exercise training attenuates oxidative stress and decreases p53 protein content in skeletal muscle of type 2 diabetic Goto-Kakizaki rats. Free Radic Biol Med 2011; 50:794-800. [PMID: 21185935 DOI: 10.1016/j.freeradbiomed.2010.12.022] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/20/2010] [Revised: 12/07/2010] [Accepted: 12/15/2010] [Indexed: 11/28/2022]
Abstract
Oxidative stress can impair mitochondrial function and fuel utilization and is closely linked with the development of insulin resistance in skeletal muscle in diabetes mellitus as well as fatty liver disease. In vitro data indicate that cellular levels of reactive oxygen species depend on the expression and activity of p53, which plays a key role in energy metabolism and as a crucial transcription factor for SCO cytochrome oxidase deficient homolog 2 (SCO2) and tumor p53-induced glycolysis and apoptosis regulator (TIGAR), which regulate mitochondrial respiration and glycolysis in cells. The aims of this study were: (1) to investigate whether exercise training could attenuate the development of oxidative stress in skeletal muscle in rats with diabetes mellitus (DM) and (2) to evaluate the potential role of p53 and its transcriptional targets in exercise-induced mitochondrial adaptation in skeletal muscle in rats with DM. Goto-Kakizaki (GK) rats, which develop type 2 DM (T2DM) early in life, were randomly divided into two groups: (1) subjected to regular exercise on a treadmill at 20m/min for 30-60min, 6 days per week for 8 weeks (GK exercising, n=7), and (2) rested controls (GK control, n=7). Exercise training increased serum adiponectin and decreased serum insulin and levels of glycosylated hemoglobin (P<0.05). Skeletal muscle GSH content and GSH:GSSG ratio increased in GK exercising rats vs GK controls (P<0.05). Skeletal muscle COX activity (P<0.05), mtDNA markers (P<0.01), and COXII protein levels (P<0.05) increased in response to exercise training. Exercise training decreased p53 protein levels and TIGAR expression in skeletal muscle (P<0.05), but SCO2 expression was unchanged. These data indicate that exercise training can attenuate oxidative stress and increase mitochondrial DNA content in skeletal muscle in rats with T2DM and that exercise-induced suppression of p53 and TIGAR expression may play a role in preventing oxidative stress in insulin resistance.
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Affiliation(s)
- Zhengtang Qi
- College of Physical Education and Health, East China Normal University, Shanghai 200241, China
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Guri AJ, Bassaganya-Riera J. Systemic effects of white adipose tissue dysregulation and obesity-related inflammation. Obesity (Silver Spring) 2011; 19:689-700. [PMID: 20930712 DOI: 10.1038/oby.2010.230] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Amir J Guri
- Nutritional Immunology and Molecular Medicine Laboratory, CyberInfrastructure Division, Virginia Bioinformatics Institute, Virginia Polytechnic Institute and State University, Blacksburg, Virginia, USA
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35
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Ritchie IRW, Gulli RA, Stefanyk LE, Harasim E, Chabowski A, Dyck DJ. Restoration of skeletal muscle leptin response does not precede the exercise-induced recovery of insulin-stimulated glucose uptake in high-fat-fed rats. Am J Physiol Regul Integr Comp Physiol 2010; 300:R492-500. [PMID: 21084675 DOI: 10.1152/ajpregu.00602.2010] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Leptin administration increases fatty acid (FA) oxidation rates and decreases lipid storage in oxidative skeletal muscle, thereby improving insulin response. We have previously shown high-fat (HF) diets to rapidly induce skeletal muscle leptin resistance, prior to the disruption of normal muscle FA metabolism (increase in FA transport; accumulation of triacylglycerol, diacylglycerol, ceramide) that occurs in advance of impaired insulin signaling and glucose transport. All of this occurs within a 4-wk period. Conversely, exercise can rapidly improve insulin response, in as little as one exercise bout. Thus, if the early development of leptin resistance is a contributor to HF diet-induced insulin resistance (IR) in skeletal muscle, then it is logical to predict that the rapid restoration of insulin response by exercise training would be preceded by the recovery of leptin response. In the current study, we sought to determine 1) whether 1, 2, or 4 wk of exercise training was sufficient to restore leptin response in isolated soleus muscle of rats already consuming a HF diet (60% kcal), and 2) whether this preceded the training-induced corrections in FA metabolism and improved insulin-stimulated glucose transport. In the low-fat (LF)-fed control group, insulin increased glucose transport by 153% and leptin increased AMPK and ACC phosphorylation and the rate of palmitate oxidation (+73%). These responses to insulin and leptin were either severely blunted or absent following 4 wk of HF feeding. Exercise intervention decreased muscle ceramide content (-28%) and restored insulin-stimulated glucose transport to control levels within 1 wk; muscle leptin response (AMPK and ACC phosphorylation, FA oxidation) was also restored, but not until the 2-wk time point. In conclusion, endurance exercise training is able to restore leptin response, but this does not appear to be a necessary precursor for the restoration of insulin response.
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Affiliation(s)
- Ian R W Ritchie
- Dept. of Human Health and Nutritional Sciences, Animal Science and Nutrition Bldg., Rm 205, University of Guelph, Guelph, ON, Canada
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36
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Lessard SJ, Rivas DA, Stephenson EJ, Yaspelkis BB, Koch LG, Britton SL, Hawley JA. Exercise training reverses impaired skeletal muscle metabolism induced by artificial selection for low aerobic capacity. Am J Physiol Regul Integr Comp Physiol 2010; 300:R175-82. [PMID: 21048074 DOI: 10.1152/ajpregu.00338.2010] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
We have used a novel model of genetically imparted endurance exercise capacity and metabolic health to study the genetic and environmental contributions to skeletal muscle glucose and lipid metabolism. We hypothesized that metabolic abnormalities associated with low intrinsic running capacity would be ameliorated by exercise training. Selective breeding for 22 generations resulted in rat models with a fivefold difference in intrinsic aerobic capacity. Low (LCR)- and high (HCR)-capacity runners remained sedentary (SED) or underwent 6 wk of exercise training (EXT). Insulin-stimulated glucose transport, insulin signal transduction, and rates of palmitate oxidation were lower in LCR SED vs. HCR SED (P < 0.05). Decreases in glucose and lipid metabolism were associated with decreased β₂-adrenergic receptor (β₂-AR), and reduced expression of Nur77 target proteins that are critical regulators of muscle glucose and lipid metabolism [uncoupling protein-3 (UCP3), fatty acid transporter (FAT)/CD36; P < 0.01 and P < 0.05, respectively]. EXT reversed the impairments to glucose and lipid metabolism observed in the skeletal muscle of LCR, while increasing the expression of β₂-AR, Nur77, GLUT4, UCP3, and FAT/CD36 (P < 0.05) in this tissue. However, no metabolic improvements were observed following exercise training in HCR. Our results demonstrate that metabolic impairments resulting from genetic factors (low intrinsic aerobic capacity) can be overcome by an environmental intervention (exercise training). Furthermore, we identify Nur77 as a potential mechanism for improved skeletal muscle metabolism in response to EXT.
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Affiliation(s)
- Sarah J Lessard
- Royal Melbourne Institute of Technology, Bundoora, Victoria, Australia
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Russo F, De Girolamo P, Neglia S, Gargiulo A, Arcamone N, Gargiulo G, Varricchio E. Immunohistochemical and immunochemical characterization of the distribution of leptin-like proteins in the gastroenteric tract of two teleosts (Dicentrarchus labrax and Carassius auratus L.) with different feeding habits. Microsc Res Tech 2010; 74:714-9. [DOI: 10.1002/jemt.20948] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2010] [Accepted: 08/31/2010] [Indexed: 11/08/2022]
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Yaspelkis BB, Kvasha IA, Lessard SJ, Rivas DA, Hawley JA. Aerobic training reverses high-fat diet-induced pro-inflammatory signalling in rat skeletal muscle. Eur J Appl Physiol 2010; 110:779-88. [PMID: 20596724 DOI: 10.1007/s00421-010-1559-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/23/2010] [Indexed: 12/16/2022]
Abstract
High-fat feeding activates components of the pro-inflammatory pathway and increases co-immunoprecipitation of suppressor of cytokine signalling (SOCS)-3 with both the insulin receptor (IR)-β subunit and IRS-1, which together contribute to keeping PI-3 kinase from being fully activated. However, whether aerobic training reverses these impairments is unknown. Sprague-Dawley rats were fed a chow (CON, n = 8) or saturated high-fat (n = 16) diets for 4 weeks. High-fat-fed rats were then allocated (n = 8/group) to either sedentary (HF) or aerobic exercise training (HFX) for an additional 4 weeks after which all animals underwent hind limb perfusions. Insulin-stimulated red quadriceps 3-O-methylglucose transport rates and PI-3 kinase activity were greater (p < 0.05) in CON and HFX compared to HF. IRS-1 tyrosine phosphorylation was increased (p < 0.05) and IRS-1 serine 307 phosphorylation was decreased (p < 0.05) in HFX compared to HF. IR-β subunit co-immunoprecipitation with IRS-1 was increased in HFX compared to HF. SOCS-3 co-immunoprecipitation with both the IR-β subunit and IRS-1 was decreased (p < 0.05) in HFX compared to HF. IKKα/β serine phosphorylation, and IκBα serine phosphorylation were decreased (p < 0.05) while IκBα protein concentration was increased in HFX compared to HF. By decreasing the association of SOCS-3 with both the IR-β subunit and IRS-1 the interaction between IRS-1 and the IR-β subunit was normalized in the HFX, and may have contributed to skeletal muscle PI-3 kinase being fully activated by insulin. Additionally, the reduction in IKKα/β serine phosphorylation in HFX may have contributed to decreasing IRS-1 serine phosphorylation, and in turn, promoted the normalization of insulin-stimulated activation of PI-3 kinase.
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Affiliation(s)
- Ben B Yaspelkis
- Exercise Biochemistry Laboratory, Department of Kinesiology, California State University Northridge, 18111 Nordhoff Street, Northridge, CA 91330-8287, USA.
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Galic S, Oakhill JS, Steinberg GR. Adipose tissue as an endocrine organ. Mol Cell Endocrinol 2010; 316:129-39. [PMID: 19723556 DOI: 10.1016/j.mce.2009.08.018] [Citation(s) in RCA: 1096] [Impact Index Per Article: 78.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/12/2008] [Revised: 08/05/2009] [Accepted: 08/25/2009] [Indexed: 02/06/2023]
Abstract
Obesity is characterized by increased storage of fatty acids in an expanded adipose tissue mass and is closely associated with the development of insulin resistance in peripheral tissues such as skeletal muscle and the liver. In addition to being the largest source of fuel in the body, adipose tissue and resident macrophages are also the source of a number of secreted proteins. Cloning of the obese gene and the identification of its product, leptin, was one of the first discoveries of an adipocyte-derived signaling molecule and established an important role for adipose tissue as an endocrine organ. Since then, leptin has been found to have a profound role in the regulation of whole-body metabolism by stimulating energy expenditure, inhibiting food intake and restoring euglycemia, however, in most cases of obesity leptin resistance limits its biological efficacy. In contrast to leptin, adiponectin secretion is often diminished in obesity. Adiponectin acts to increase insulin sensitivity, fatty acid oxidation, as well as energy expenditure and reduces the production of glucose by the liver. Resistin and retinol binding protein-4 are less well described. Their expression levels are positively correlated with adiposity and they are both implicated in the development of insulin resistance. More recently it has been acknowledged that macrophages are an important part of the secretory function of adipose tissue and the main source of inflammatory cyokines, such as TNFalpha and IL-6. An increase in circulating levels of these macrophage-derived factors in obesity leads to a chronic low-grade inflammatory state that has been linked to the development of insulin resistance and diabetes. These proteins commonly known as adipokines are central to the dynamic control of energy metabolism, communicating the nutrient status of the organism with the tissues responsible for controlling both energy intake and expenditure as well as insulin sensitivity.
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Affiliation(s)
- Sandra Galic
- St. Vincent's Institute of Medical Research and Department of Medicine, University of Melbourne, Melbourne, Victoria, Australia
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Alkhateeb H, Chabowski A, Glatz JFC, Gurd B, Luiken JJFP, Bonen A. Restoring AS160 phosphorylation rescues skeletal muscle insulin resistance and fatty acid oxidation while not reducing intramuscular lipids. Am J Physiol Endocrinol Metab 2009; 297:E1056-66. [PMID: 19724017 DOI: 10.1152/ajpendo.90908.2008] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
We examined whether AICAR or leptin rapidly rescued skeletal muscle insulin resistance via increased palmitate oxidation, reductions in intramuscular lipids, and/or restoration of insulin-stimulated AS60 phosphorylation. Incubation with palmitate (2 mM, 0-18 h) induced insulin resistance in soleus muscle. From 12-18 h, palmitate was removed or AICAR or leptin was provided while 2 mM palmitate was maintained. Palmitate oxidation, intramuscular triacylglycerol, diacylglycerol, ceramide, AMPK phosphorylation, basal and insulin-stimulated glucose transport, plasmalemmal GLUT4, and Akt and AS160 phosphorylation were examined at 0, 6, 12, and 18 h. Palmitate treatment (12 h) increased intramuscular lipids (triacylglycerol +54%, diacylglycerol +11%, total ceramide +18%, C16:0 ceramide +60%) and AMPK phosphorylation (+118%), whereas it reduced fatty acid oxidation (-60%) and insulin-stimulated glucose transport (-70%), GLUT4 translocation (-50%), and AS160 phosphorylation (-40%). Palmitate removal did not rescue insulin resistance or associated parameters. The AICAR and leptin treatments did not consistently reduce intramuscular lipids, but they did rescue palmitate oxidation and insulin-stimulated glucose transport, GLUT4 translocation, and AS160 phosphorylation. Increased AMPK phosphorylation was associated with these improvements only when AICAR and leptin were present. Hence, across all experiments, AMPK phosphorylation did not correlate with any parameters. In contrast, palmitate oxidation and insulin-stimulated AS160 phosphorylation were highly correlated (r = 0.83). We speculate that AICAR and leptin activate both of these processes concomitantly, involving activation of unknown kinases in addition to AMPK. In conclusion, despite the maintenance of high concentrations of palmitate (2 mM), as well as increased concentrations of intramuscular lipids (triacylglycerol, diacylglycerol, and ceramide), the rapid AICAR- and leptin-mediated rescue of palmitate-induced insulin resistance is attributable to the restoration of insulin-stimulated AS160 phosphorylation and GLUT4 translocation.
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Affiliation(s)
- Hakam Alkhateeb
- Dept. of Human Health and Nutritional Sciences, Univ. of Guelph, Guelph, ON, N1G 2W1, Canada
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Fuentes T, Ara I, Guadalupe-Grau A, Larsen S, Stallknecht B, Olmedillas H, Santana A, Helge JW, Calbet JAL, Guerra B. Leptin receptor 170 kDa (OB-R170) protein expression is reduced in obese human skeletal muscle: a potential mechanism of leptin resistance. Exp Physiol 2009; 95:160-71. [PMID: 19717488 DOI: 10.1113/expphysiol.2009.049270] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
To examine whether obesity-associated leptin resistance could be due to down-regulation of leptin receptors (OB-Rs) and/or up-regulation of suppressor of cytokine signalling 3 (SOCS3) and protein tyrosine phosphatase 1B (PTP1B) in skeletal muscle, which blunt janus kinase 2-dependent leptin signalling and signal transducer and activator of transcription 3 (STAT3) phosphorylation and reduce AMP-activated protein kinase (AMPK) and acetyl-coenzyme A carboxylase (ACC) phosphorylation. Deltoid and vastus lateralis muscle biopsies were obtained from 20 men: 10 non-obese control subjects (mean +/- s.d. age, 31 +/- 5 years; height, 184 +/- 9 cm; weight, 91 +/- 13 kg; and percentage body fat, 24.8 +/- 5.8%) and 10 obese (age, 30 +/- 7 years; height, 184 +/- 8 cm; weight, 115 +/- 8 kg; and percentage body fat, 34.9 +/- 5.1%). Skeletal muscle OB-R170 (OB-R long isoform) protein expression was 28 and 25% lower (both P < 0.05) in arm and leg muscles, respectively, of obese men compared with control subjects. In normal-weight subjects, SOCS3 protein expression, and STAT3, AMPKalpha and ACCbeta phosphorylation, were similar in the deltoid and vastus lateralis muscles. In obese subjects, the deltoid muscle had a greater amount of leptin receptors than the vastus lateralis, whilst SOCS3 protein expression was increased and basal STAT3, AMPKalpha and ACCbeta phosphorylation levels were reduced in the vastus lateralis compared with the deltoid muscle (all P < 0.05). In summary, skeletal muscle leptin receptors and leptin signalling are reduced in obesity, particularly in the leg muscles.
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Affiliation(s)
- T Fuentes
- Department of Physical Education, University of Las Palmas de Gran Canaria, Campus Universitario de Tafira, 35017 Las Palmas de Gran Canaria, Canary Island, Spain
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Dyck DJ. Adipokines as regulators of muscle metabolism and insulin sensitivity. Appl Physiol Nutr Metab 2009; 34:396-402. [PMID: 19448705 DOI: 10.1139/h09-037] [Citation(s) in RCA: 105] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Skeletal muscle is the largest tissue responsible for the insulin-stimulated disposal of glucose. However, identifying the link between excess body fat and impaired insulin sensitivity in skeletal muscle has been difficult. Several adipose-derived cytokines (adipokines) have been implicated in the impairment of insulin sensitivity, while adipokines such as leptin and adiponectin exert an insulin-sensitizing effect. Leptin and adiponectin have each been shown to increase fatty acid (FA) oxidation and decrease triglyceride storage in muscle, which may explain, in part, the insulin-sensitizing effect of these cytokines. Recent evidence strongly implicates an increased localization of the FA transporters to the plasma membrane (PM) as an important factor in the accumulation of intramuscular lipids with high-fat diets and obesity. Perhaps surprisingly, relatively little attention has been paid to the ability of insulin-sensitizing compounds, such as leptin and adiponectin, to decrease the abundance of FA transporters in the PM, thereby decreasing lipid accumulation. In the case of both adipokines, there is also evidence that a resistance to their ability to stimulate FA oxidation in skeletal muscle develops during obesity. One of our recent studies indicates that this development can be very rapid (i.e., within days), and precedes the increase in lipid uptake and accumulation that leads to insulin resistance. It is noteworthy that leptin resistance can be modulated by both diet and training in rodents. Further studies examining the underlying mechanisms of the development of leptin and adiponectin resistance are warranted.
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Affiliation(s)
- David J Dyck
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON N1G 2W1, Canada.
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Yaspelkis BB, Kvasha IA, Figueroa TY. High-fat feeding increases insulin receptor and IRS-1 coimmunoprecipitation with SOCS-3, IKKalpha/beta phosphorylation and decreases PI-3 kinase activity in muscle. Am J Physiol Regul Integr Comp Physiol 2009; 296:R1709-15. [PMID: 19386987 DOI: 10.1152/ajpregu.00117.2009] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Suppressor of cytokine signaling (SOCS) proteins and/or activation of the proinflammatory pathway have been postulated as possible mechanisms that may contribute to skeletal muscle insulin resistance. Thus, the aims of the present investigation were to determine in high-fat-fed skeletal muscle: 1) whether SOCS-3 protein concentration is increased, 2) whether coimmunoprecipitation of SOCS-3 with the insulin receptor-beta subunit and/or IRS-1 is increased, and 3) whether select components of the proinflammatory pathway are altered. Thirty-two male Sprague-Dawley rats were assigned to either control (CON, n = 16) or high-fat-fed (HF, n = 16) dietary groups for 12 wk and then subjected to hind limb perfusions in the presence (n = 8/group) or absence (n = 8/group) of insulin. Insulin-stimulated skeletal muscle 3-MG transport rates and PI-3 kinase activity were greater (P < 0.05) in CON. IRS-1 tyrosine phosphorylation was decreased (P < 0.05), and IRS-1 serine 307 phosphorylation was increased (P < 0.05) in HF. Insulin receptor-beta (IR-beta) subunit coimmunoprecipitation with IRS-1 was reduced in HF. SOCS-3 protein concentration and SOCS-3 coimmunoprecipitation with both the IR-beta subunit and IRS-1 was increased (P < 0.05) in HF. IKKalpha/beta serine phosphorylation was increased (P < 0.05), IkappaBalpha protein concentration was decreased (P < 0.05) and IkappaBalpha serine phosphorylation was increased (P < 0.05) in HF. Increased colocalization of SOCS-3 with both the IR-beta subunit and IRS-1 may provide steric hindrance that prevents IRS-1 from interacting with IR-beta, while increased IKKbeta serine phosphorylation may contribute to increasing IRS-1 serine phosphorylation, both of which independently can have deleterious effects on insulin-stimulated PI-3 kinase activation in high-fat-fed rodent skeletal muscle.
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Affiliation(s)
- Ben B Yaspelkis
- Exercise Biochemistry Laboratory, Department of Kinesiology, California State University Northridge, Northridge, 18111 Nordhoff St., Northridge, CA 91330-8287 USA.
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Eguchi R, Cheik NC, Oyama LM, Nascimento CMOD, Mello MTD, Tufik S, Dâmaso A. Efeitos do exercício crônico sobre a concentração circulante da leptina e grelina em ratos com obesidade induzida por dieta. REV BRAS MED ESPORTE 2008. [DOI: 10.1590/s1517-86922008000300004] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
A obesidade vem se tornando uma das maiores epidemias mundiais, dessa forma, conhecer sua etiologia e mecanismos que regulam seu desenvolvimento é de grande relevância para o seu Tratamento. Portanto, o objetivo do presente estudo foi avaliar os efeitos da obesidade exógena induzida pela dieta de cafeteria e da atividade física crônica em ratos, sobre a adiposidade e a concentração sérica dos hormônios reguladores do balanço energético (leptina e grelina). Foram utilizados 32 ratos Wistar machos, divididos em quatro grupos: Sedentário alimentado com dieta padrão (SN), sedentário alimentado com dieta de cafeteria (SC), treinado alimentado com dieta padrão (TN) e treinado alimentado com dieta de cafeteria (TC). A dieta de cafeteria aumentou significativamente a adiposidade central (RET) e visceral (EPI) (p<0,05), induzindo a obesidade. Por outro lado, o treinamento físico minimizou o efeito da dieta de cafeteria, diminuindo tanto a adiposidade central como a visceral. A atividade física crônica não impediu o desenvolvimento da hiperleptinemia nos ratos normocalóricos e alimentados com dieta de cafeteria. Observou-se ainda que decorrente do treinamento físico e consequente redução de massa, nos animais normocalóricos, houve diminuição na concentração plasmática de grelina. Concluímos com este estudo que a qualidade da dieta e a quantidade de tecido adiposo, apresentaram-se como importantes reguladores da concentração plasmática de hormônios reguladores do balanço energético, reforçando a importância de uma dieta adequada e da atividade física contínua na manutenção do peso corporal no combate aos efeitos deletérios da obesidade.
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da Mota GR, Zanesco A. [Leptin, ghrelin, and physical exercise]. ACTA ACUST UNITED AC 2008; 51:25-33. [PMID: 17435852 DOI: 10.1590/s0004-27302007000100006] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2005] [Accepted: 07/10/2006] [Indexed: 01/22/2023]
Abstract
Obesity is a major public health problem in the Western world resulting in serious social, physical and psychological damages. The genesis of obesity is complex involving a variety of factors such as genetic, psychological, metabolic and environmental factors. Progress in endocrinology and metabolism show that adipocyte is considered now as an endocrine tissue producing several substance including adiponectin, tumor necrosis factor-alpha, interleukin-6 and leptin. Specifically, leptin is the main peptide produced by the adipocyte and its serum concentration represents an important peripheral signal in the regulation of food intake and energy expenditure in mammals. In addition to leptin, a new peptide was discovered recently named ghrelin. Ghrelin, a peptide hormone identified in the stomach, is directly involved with the regulation of energy balance and obesity. Physical exercise has been used as a non-pharmacological tool in management of body weight and the effect of physical activity on weight control is an important issue for clinical studies in endocrinology field. Thus, this review will attempt to update the knowledge of leptin and ghrelin on the body weight regulation and the effect of exercise training on these peptide concentrations. It can be concluded that the relationship between physical exercise and the plasma concentration of these peptides is not clear. The reasons for that could be related to the differences in duration, intensity and frequency of the training program employed in each study. Indeed, most of the studies have not analyzed the intensity of training program by either plasma lactate concentration or maximum oxygen consumption. On the other hand, genetic basis could also explain the discrepancies found in some studies, since it has been shown that polymorphism for a variety of genes might be an important factor to determine the differences of cellular response to physical training.
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Affiliation(s)
- Gustavo R da Mota
- Departamento de Educação Física, Instituto de Biociências, Universidade Estadual Paulista (UNESP), Rio Claro, SP
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Trevenzoli IH, Valle MMR, Machado FB, Garcia RMG, Passos MCF, Lisboa PC, Moura EG. Neonatal hyperleptinaemia programmes adrenal medullary function in adult rats: effects on cardiovascular parameters. J Physiol 2007; 580:629-37. [PMID: 17218354 PMCID: PMC2075542 DOI: 10.1113/jphysiol.2006.126151] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Epidemiological studies have shown a strong correlation between stressful events (nutritional, hormonal or environmental) in early life and development of adult diseases such as obesity, diabetes and cardiovascular failure. It is known that gestation and lactation are crucial periods for healthy growth in mammals and that the sympathoadrenal system is markedly influenced by environmental conditions during these periods. We previously demonstrated that neonatal hyperleptinaemia in rats programmes higher body weight, higher food intake and hypothalamic leptin resistance in adulthood. Using this model of programming, we investigated adrenal medullary function and effects on cardiovascular parameters in male rats in adulthood. Leptin treatment during the first 10 days of lactation (8 microg 100 g(-1) day(-1), s.c.) resulted in lower body weight (6.5%, P < 0.05), hyperleptinaemia (10-fold, P < 0.05) and higher catecholamine content in adrenal glands (18.5%, P < 0.05) on the last day of treatment. In adulthood (150 days), the rats presented higher body weight (5%, P < 0.05), adrenal catecholamine content (3-fold, P < 0.05), tyrosine hydroxylase expression (35%, P < 0.05) and basal and caffeine-stimulated catecholamine release (53% and 100%, respectively, P < 0.05). Systolic blood pressure and heart rate were also higher in adult rats (7% and 6%, respectively, P < 0.05). Our results show that hyperleptinaemia in early life increases adrenal medullary function in adulthood and that this may alter cardiovascular parameters. Thus, we suggest that imprinting factors which increase leptin and catecholamine levels during the neonatal period could be involved in development of adult chronic diseases.
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Affiliation(s)
- I H Trevenzoli
- Physiology Department, Alcântara Gomes Biology Institute, State University of Rio de Janeiro, RJ, 20551-030, Brazil
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McAinch A, Steinberg G, Mollica J, O’Brien P, Dixon J, Kemp B, Cameron-Smith D. Leptin stimulation of COXIV is impaired in obese skeletal muscle myotubes. Obes Res Clin Pract 2007; 1:1-78. [DOI: 10.1016/j.orcp.2006.10.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/16/2006] [Revised: 10/04/2006] [Accepted: 10/12/2006] [Indexed: 10/23/2022]
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Watt MJ, Dzamko N, Thomas WG, Rose-John S, Ernst M, Carling D, Kemp BE, Febbraio MA, Steinberg GR. CNTF reverses obesity-induced insulin resistance by activating skeletal muscle AMPK. Nat Med 2006; 12:541-8. [PMID: 16604088 DOI: 10.1038/nm1383] [Citation(s) in RCA: 215] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2005] [Accepted: 02/23/2006] [Indexed: 12/19/2022]
Abstract
Ciliary neurotrophic factor (CNTF) induces weight loss and improves glucose tolerance in humans and rodents. CNTF is thought to act centrally by inducing hypothalamic neurogenesis to modulate food intake and peripherally by altering hepatic gene expression, in a manner similar to that of leptin. Here, we show that CNTF signals through the CNTFRalpha-IL-6R-gp130beta receptor complex to increase fatty-acid oxidation and reduce insulin resistance in skeletal muscle by activating AMP-activated protein kinase (AMPK), independent of signaling through the brain. Thus, our findings further show that the antiobesogenic effects of CNTF in the periphery result from direct effects on skeletal muscle, and that these peripheral effects are not suppressed by diet-induced or genetic models of obesity, an essential requirement for the therapeutic treatment of obesity-related diseases.
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Affiliation(s)
- Matthew J Watt
- Cellular and Molecular Metabolism Laboratory, School of Medical Sciences, Royal Melbourne Institute of Technology, PO Box 71, Bundoora, 3083, Australia
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Dyck DJ, Heigenhauser GJF, Bruce CR. The role of adipokines as regulators of skeletal muscle fatty acid metabolism and insulin sensitivity. Acta Physiol (Oxf) 2006; 186:5-16. [PMID: 16497175 DOI: 10.1111/j.1748-1716.2005.01502.x] [Citation(s) in RCA: 162] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Several adipose-derived cytokines (adipokines) have been suggested to act as a link between accumulated fat mass and altered insulin sensitivity. Resistin and tumour necrosis factor-alpha (TNF-alpha) have been implicated in impairing insulin sensitivity in rodents; conversely, two other adipokines, leptin and adiponectin, increase insulin sensitivity in lean and obese rodents. Currently, there is considerable focus on the concept that lipid accumulation in skeletal muscle leads to the development of insulin resistance. Adiponectin and leptin have each been demonstrated to increase rates of fatty acid (FA) oxidation and decrease muscle lipid content, which may in part be the underlying mechanism to their insulin sensitizing effect. These effects on FA metabolism appear to be mediated in part through the activation of AMP-activated protein kinase. Evidence derived from animal and human studies suggests that the ability of leptin and adiponectin to stimulate FA oxidation in muscle is impaired in the obese condition. Thus, leptin and adiponectin resistance may be an initiating factor in the accumulation of intramuscular lipids, such as diacylglycerol and ceramide, and the ensuing development of insulin resistance. Lifestyle factors such as diet and exercise are able to restore the sensitivity of muscle to leptin. The actual physiological roles of resistin and TNF-alpha in altering muscle lipid metabolism are more controversial, but each has been shown to directly impair insulin signalling and consequently, insulin stimulated glucose uptake in muscle. However, the possibility that resistin and TNF-alpha reduces insulin sensitivity in muscle by directly impairing FA metabolism in this tissue leading to lipid accumulation, has been virtually unexamined. Thus, the contribution of various adipokines to the development of insulin resistance is complex and not fully understood. Finally, the effects of these adipokines on metabolism and insulin sensitivity are generally studied in isolation, making it difficult to predict the interactive effects and the net impact on insulin sensitivity.
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Affiliation(s)
- D J Dyck
- Department of Human Health and Nutritional Sciences, University of Guelph, Ontario, Canada.
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Abstract
Leptin reduces intracellular lipid stores and improves insulin sensitivity. Thus, the development of leptin resistance in obesity may be an early event leading to elevated intramuscular lipids and insulin resistance. Recent data indicate that obesity-causing high-fat diets lead to leptin resistance in muscle, whereas supplementation with dietary fish oil and aerobic training can partially reverse this resistance.
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Affiliation(s)
- David J Dyck
- Department of Human Biology and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
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