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Adeva-Andany MM, Domínguez-Montero A, Castro-Quintela E, Funcasta-Calderón R, Fernández-Fernández C. Hypoxia-Induced Insulin Resistance Mediates the Elevated Cardiovascular Risk in Patients with Obstructive Sleep Apnea: A Comprehensive Review. Rev Cardiovasc Med 2024; 25:231. [PMID: 39076340 PMCID: PMC11270082 DOI: 10.31083/j.rcm2506231] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2024] [Revised: 04/07/2024] [Accepted: 04/12/2024] [Indexed: 07/31/2024] Open
Abstract
Patients with obstructive sleep apnea (OSA) experience insulin resistance and its clinical consequences, including hypertriglyceridemia, reduced high density lipoprotein-associated cholesterol (HDL-c), visceral adiposity, hepatic steatosis, increased epicardial fat thickness, essential hypertension, glucose intolerance, increased risk for type 2 diabetes, chronic kidney disease, subclinical vascular damage, and increased risk for cardiovascular events. Obesity is a major contributor to OSA. The prevalence of OSA is almost universal among patients with severe obesity undergoing bariatric surgery. However, insulin resistance and its clinical complications occur in OSA patients irrespective of general obesity (body mass index). In OSA patients, apnea episodes during sleep induce oxyhemoglobin desaturation and tissue hypoxia. Insulin resistance is an adaptive response to tissue hypoxia and develops in conditions with limited tissue oxygen supply, including healthy subjects exposed to hypobaric hypoxia (high altitude) and OSA patients. Indicators of oxyhemoglobin desaturation have been robustly and independently linked to insulin resistance and its clinical manifestations in patients with OSA. Insulin resistance mediates the elevated rate of type 2 diabetes, chronic kidney disease, and cardiovascular disease unexplained with traditional cardiovascular risk factors present in OSA patients. Pathophysiological processes underlying hypoxia-induced insulin resistance involve hypoxia inducible factor-1 upregulation and peroxisome proliferator-activated receptor-gamma (PPAR- γ ) downregulation. In human adipose tissue, PPAR- γ activity promotes glucose transport into adipocytes, lipid droplet biogenesis, and whole-body insulin sensitivity. Silencing of PPAR- γ in the adipose tissue reduces glucose uptake and fat accumulation into adipocytes and promotes insulin resistance. In conclusion, tissue hypoxia drives insulin resistance and its clinical consequences in patients with OSA, regardless of body mass index.
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Logesh R, Hari B, Chidambaram K, Das N. Molecular effects of Vitamin-D and PUFAs metabolism in skeletal muscle combating Type-II diabetes mellitus. Gene 2024; 904:148216. [PMID: 38307219 DOI: 10.1016/j.gene.2024.148216] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2023] [Revised: 01/10/2024] [Accepted: 01/25/2024] [Indexed: 02/04/2024]
Abstract
Multiple post-receptor intracellular alterations such as impaired glucose transfer, glucose phosphorylation, decreased glucose oxidation, and glycogen production contribute to insulin resistance (IR) in skeletal muscle, manifested by diminished insulin-stimulated glucose uptake. Type-2 diabetes mellites (T2DM) has caused by IR, which is also seen in obese patients and those with metabolic syndrome. The Vitamin-D receptor (VDR) and poly unsaturated fatty acids (PUFAs) roles in skeletal muscle growth, shapes, and function for combating type-2 diabetes have been clarified throughout this research. VDR and PUFAs appears to show a variety of effects on skeletal muscle, in addition it shows a promising role on bone and mineral homeostasis. Individuals having T2DM are reported to suffer from severe muscular weakness and alterations in shape of the muscle. Several studies have investigated the effect on VDR on muscular strength and mass, which leads to Vitamin-D deficiency (VDD) in individuals, in which most commonly seen in elderly. VDR has been shown to affect skeletal cellular proliferation, intracellular calcium handling, as well as genomic activity in a variety of different ways such as muscle metabolism, insulin sensitivity, which is the major characteristic pathogenesis for IR in combating T2DM. The identified VDR gene polymorphisms are ApaI, TaqI, FokI, and BsmI that are associated with T2DM. This review collates informations on the mechanisms by which VDR activation takes place in skeletal muscles. Despite the significant breakthroughs made in recent decades, various studies show that IR affects VDR and PUFAs metabolism in skeletal muscle. Therefore, this review collates the data to show the role of VDR and PUFAs in the skeletal muscles to combat T2DM.
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Affiliation(s)
- Rajan Logesh
- Department of Pharmacognosy, JSS College of Pharmacy, Mysuru, JSS Academy of Higher Education & Research, Karnataka, India.
| | - Balaji Hari
- TIFAC CORE in Herbal Drugs, Department of Pharmacognosy, JSS Academy of Higher Education & Research, JSS College of Pharmacy, The Nilgiris, Ooty 643001, Tamil Nadu, India
| | - Kumarappan Chidambaram
- Department of Pharmacology, College of Pharmacy, King Khalid University, Al-Qara, Asir Province, Saudi Arabia
| | - Niranjan Das
- Department of Chemistry, Iswar Chandra Vidyasagar College, Belonia 799155, Tripura, India
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Wang G, Li X, Zhou Y, Feng J, Zhang M. Effects of Dietary Chromium Picolinate on Gut Microbiota, Gastrointestinal Peptides, Glucose Homeostasis, and Performance of Heat-Stressed Broilers. Animals (Basel) 2022; 12:ani12070844. [PMID: 35405834 PMCID: PMC8997060 DOI: 10.3390/ani12070844] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2022] [Revised: 03/13/2022] [Accepted: 03/23/2022] [Indexed: 12/25/2022] Open
Abstract
The current research was devoted to evaluating the effects on gut microbiota, gastrointestinal peptides, and glucose homeostasis of chromium picolinate applied to heat-stressed broilers. In a 14 d experiment, 220 28-day-old AA broilers were randomly assigned into one thermal-neutral and three high-temperature groups dietary-supplemented with 0, 0.4, or 0.8 mg/kg of chromium as chromium picolinate. The temperature for the thermal-neutral group was set at 21 °C, while that for the other three groups (high temperature) was set at 31 °C. The results showed that the average daily gain and average daily feed intake of the 0.4 mg/kg chromium-supplemented group significantly increased compared with the high-temperature groups (p < 0.05). The content of cholecystokinin in the 0.4 mg/kg group significantly decreased, and the gastric inhibitory polypeptide level was significantly elevated in jejunum (p < 0.05). The cecal microbiota of heat-stressed broilers was substantially different from that of the thermal-neutral group. After diet-supplemented chromium, compared to the high-temperature groups, the 0.4 mg/kg chromium supplemented group was characterized by a reduction of Actinobacteriota and Proteobacteria at the phylum level. The Bacilli were elevated, while proportions of Coriobacteria and Gammaproteobacteria were reduced significantly at the class level. The proportions of Lactobacillaceae, Christensenellaceae, and Erysipelotrichaceae were elevated significantly, while that of Clostridiaceae was reduced significantly at the family level. The proportion of Turicibacter was elevated significantly and the proportions of Olsenella and Ruminococcus were reduced significantly at the genus level (p < 0.05). Compared to the high-temperature groups, in the 0.4 mg/kg chromium-supplemented group, the insulin concentration and insulin resistance index were reduced (p < 0.05), and sodium-glucose transporter 1 expression was up-regulated in jejunum (p < 0.05). Performance, microbiota, gastrointestinal peptides, or serum parameters of the 0.8 mg/kg group were almost unaffected by chromium compared with the high-temperature groups. In conclusion, diet supplemented with 0.4 mg/kg Cr improved performance, insulin resistance and sodium-glucose transporter 1 expression and altered gut microflora structure and secretion of gastrointestinal peptides, thus showing that supplementation with chromium is beneficial to maintain glucose homeostasis and alleviate heat stress.
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Htun KT, Pan J, Pasanta D, Tungjai M, Udomtanakunchai C, Chancharunee S, Kaewjaeng S, Kim HJ, Kaewkhao J, Kothan S. Identification of Metabolic Phenotypes in Young Adults with Obesity by 1H NMR Metabolomics of Blood Serum. Life (Basel) 2021; 11:life11060574. [PMID: 34207003 PMCID: PMC8246321 DOI: 10.3390/life11060574] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2021] [Revised: 06/06/2021] [Accepted: 06/15/2021] [Indexed: 02/07/2023] Open
Abstract
(1) Since the obesity prevalence rate has been consistently increasing, it is necessary to find an effective way to prevent and treat it. Although progress is being made to reduce obesity in the young adult population, a better understanding of obesity-related metabolomics and related biochemical mechanisms is urgently needed for developing appropriate screening strategies. Therefore, the aim of this study is to identify the serum metabolic profile associated with young adult obesity and its metabolic phenotypes. (2) Methods: The serum metabolic profile of 30 obese and 30 normal-weight young adults was obtained using proton nuclear magnetic resonance spectroscopy (1H NMR). 1H NMR spectra were integrated into 24 integration regions, which reflect relative metabolites, and were used as statistical variables. (3) Results: The obese group showed increased levels of lipids, glucose, glutamate, N-acetyl glycoprotein, alanine, lactate, 3 hydroxybutyrate and branch chain amino acid (BCAA), and decreased levels of choline as compared with the normal-weight group. Non-hyperlipidemia obese adults showed lower levels of lipids and lactate, glutamate, acetoacetate, N-acetyl glycoprotein, isoleucine, and higher levels of choline and glutamine, as compared with hyperlipidemic obese adults. (4) Conclusions: This study reveals valuable findings in the field of metabolomics and young adult obesity. We propose several serum biomarkers that distinguish between normal weight and obese adults, i.e., glutamine (higher in the normal group, p < 0.05), and lactate, BCAAs, acetoacetate and 3-hydroxybutyrate (higher in the obese group, p < 0.05). In addition, visceral fat and serum TG, glutamate, acetoacetate, N-acetyl glycoprotein, unsaturated lipid, isoleucine, and VLDL/LDL are higher (p < 0.05) in the obese with hyperlipidemia. Therefore, they can be used as biomarkers to identify these two types of obesity.
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Affiliation(s)
- Khin Thandar Htun
- Center of Radiation Research and Medical Imaging, Department of Radiologic Technology, Faculty of Associated Medical Sciences, Chiang Mai University, Chiang Mai 50200, Thailand; (K.T.H.); (D.P.); (M.T.); (C.U.); (S.K.)
| | - Jie Pan
- Center of Radiation Research and Medical Imaging, Department of Radiologic Technology, Faculty of Associated Medical Sciences, Chiang Mai University, Chiang Mai 50200, Thailand; (K.T.H.); (D.P.); (M.T.); (C.U.); (S.K.)
- Shandong Provincial Key Laboratory of Animal Resistant Biology, College of Life Sciences, Shandong Normal University, Jinan 250014, China
- Correspondence: (J.P.); (S.K.); Tel.: +86-13583101188 (J.P.); +66-5394-9213 (S.K.)
| | - Duanghathai Pasanta
- Center of Radiation Research and Medical Imaging, Department of Radiologic Technology, Faculty of Associated Medical Sciences, Chiang Mai University, Chiang Mai 50200, Thailand; (K.T.H.); (D.P.); (M.T.); (C.U.); (S.K.)
| | - Montree Tungjai
- Center of Radiation Research and Medical Imaging, Department of Radiologic Technology, Faculty of Associated Medical Sciences, Chiang Mai University, Chiang Mai 50200, Thailand; (K.T.H.); (D.P.); (M.T.); (C.U.); (S.K.)
| | - Chatchanok Udomtanakunchai
- Center of Radiation Research and Medical Imaging, Department of Radiologic Technology, Faculty of Associated Medical Sciences, Chiang Mai University, Chiang Mai 50200, Thailand; (K.T.H.); (D.P.); (M.T.); (C.U.); (S.K.)
| | - Sirirat Chancharunee
- Department of Chemistry, Faculty of Science, Chiang Mai University, Chiang Mai 50200, Thailand;
| | - Siriprapa Kaewjaeng
- Center of Radiation Research and Medical Imaging, Department of Radiologic Technology, Faculty of Associated Medical Sciences, Chiang Mai University, Chiang Mai 50200, Thailand; (K.T.H.); (D.P.); (M.T.); (C.U.); (S.K.)
| | - Hong Joo Kim
- Department of Physics, Kyungpook National University, Daegu 41566, Korea;
| | - Jakrapong Kaewkhao
- Center of Excellence in Glass Technology and Materials Science (CEGM), Faculty of Science and Technology, Nakhon Pathom Rajabhat University, Nakhon Pathom 73000, Thailand;
| | - Suchart Kothan
- Center of Radiation Research and Medical Imaging, Department of Radiologic Technology, Faculty of Associated Medical Sciences, Chiang Mai University, Chiang Mai 50200, Thailand; (K.T.H.); (D.P.); (M.T.); (C.U.); (S.K.)
- Correspondence: (J.P.); (S.K.); Tel.: +86-13583101188 (J.P.); +66-5394-9213 (S.K.)
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Bryant NJ, Gould GW. Insulin stimulated GLUT4 translocation - Size is not everything! Curr Opin Cell Biol 2020; 65:28-34. [PMID: 32182545 DOI: 10.1016/j.ceb.2020.02.006] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Revised: 02/03/2020] [Accepted: 02/15/2020] [Indexed: 12/21/2022]
Abstract
Insulin-regulated trafficking of the facilitative glucose transporter GLUT4 has been studied in many cell types. The translocation of GLUT4 from intracellular membranes to the cell surface is often described as a highly specialised form of membrane traffic restricted to certain cell types such as fat and muscle, which are the major storage depots for insulin-stimulated glucose uptake. Here, we discuss evidence that favours the argument that rather than being restricted to specialised cell types, the machinery through which insulin regulates GLUT4 traffic is present in all cell types. This is an important point as it provides confidence in the use of experimentally tractable model systems to interrogate the trafficking itinerary of GLUT4.
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Affiliation(s)
- Nia J Bryant
- Department of Biology and York Biomedical Research Institute, University of York, York, YO10 5DD, UK.
| | - Gwyn W Gould
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, 161 Cathedral Street, Glasgow G4 0RE, UK.
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Pereira MJ, Thombare K, Sarsenbayeva A, Kamble PG, Almby K, Lundqvist M, Eriksson JW. Direct effects of glucagon on glucose uptake and lipolysis in human adipocytes. Mol Cell Endocrinol 2020; 503:110696. [PMID: 31891768 DOI: 10.1016/j.mce.2019.110696] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/15/2019] [Revised: 11/25/2019] [Accepted: 12/27/2019] [Indexed: 12/14/2022]
Abstract
We aim to investigate the expression of the glucagon receptor (GCGR) in human adipose tissue, and the impact of glucagon in glucose uptake and lipolysis in human adipocytes. GCGR gene expression in human subcutaneous and visceral adipose tissue was demonstrated, albeit at low levels and with an inter-individual variation. Furthermore, GCGR expression was not significantly different between subjects with T2D and matched controls, and we found no significant association with BMI. Glucagon only at a supra-physiological concentration (10-100 nM) significantly increased basal and insulin-stimulated glucose uptake by up to 1.5-fold. Also, glucagon (0.01 and 1 nM) dose-dependently increased basal and isoproterenol-stimulated lipolysis up to 3.7- and 1.7-fold, respectively, compared to control. In addition, glucagon did not change insulin sensitivity to stimulate glucose uptake or inhibit lipolysis. In conclusion, we show that the GCGR gene is expressed at low levels in human adipose tissue, and glucagon at high concentrations can increase both glucose uptake and lipolysis in human adipocytes. Taken together, our data suggest that glucagon at physiological levels has minor direct effects on the regulation of adipocyte metabolism, but does not antagonize the insulin effect to stimulate glucose uptake and inhibit lipolysis in human adipocytes.
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Affiliation(s)
- Maria J Pereira
- Department of Medical Sciences, Clinical Diabetes and Metabolism, Uppsala University, Uppsala, Sweden.
| | - Ketan Thombare
- Department of Medical Sciences, Clinical Diabetes and Metabolism, Uppsala University, Uppsala, Sweden
| | - Assel Sarsenbayeva
- Department of Medical Sciences, Clinical Diabetes and Metabolism, Uppsala University, Uppsala, Sweden
| | - Prasad G Kamble
- Department of Medical Sciences, Clinical Diabetes and Metabolism, Uppsala University, Uppsala, Sweden
| | - Kristina Almby
- Department of Medical Sciences, Clinical Diabetes and Metabolism, Uppsala University, Uppsala, Sweden
| | - Martin Lundqvist
- Department of Medical Sciences, Clinical Diabetes and Metabolism, Uppsala University, Uppsala, Sweden
| | - Jan W Eriksson
- Department of Medical Sciences, Clinical Diabetes and Metabolism, Uppsala University, Uppsala, Sweden
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7
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Krycer JR, Quek LE, Francis D, Fazakerley DJ, Elkington SD, Diaz-Vegas A, Cooke KC, Weiss FC, Duan X, Kurdyukov S, Zhou PX, Tambar UK, Hirayama A, Ikeda S, Kamei Y, Soga T, Cooney GJ, James DE. Lactate production is a prioritized feature of adipocyte metabolism. J Biol Chem 2020; 295:83-98. [PMID: 31690627 PMCID: PMC6952601 DOI: 10.1074/jbc.ra119.011178] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2019] [Revised: 10/31/2019] [Indexed: 12/14/2022] Open
Abstract
Adipose tissue is essential for whole-body glucose homeostasis, with a primary role in lipid storage. It has been previously observed that lactate production is also an important metabolic feature of adipocytes, but its relationship to adipose and whole-body glucose disposal remains unclear. Therefore, using a combination of metabolic labeling techniques, here we closely examined lactate production of cultured and primary mammalian adipocytes. Insulin treatment increased glucose uptake and conversion to lactate, with the latter responding more to insulin than did other metabolic fates of glucose. However, lactate production did not just serve as a mechanism to dispose of excess glucose, because we also observed that lactate production in adipocytes did not solely depend on glucose availability and even occurred independently of glucose metabolism. This suggests that lactate production is prioritized in adipocytes. Furthermore, knocking down lactate dehydrogenase specifically in the fat body of Drosophila flies lowered circulating lactate and improved whole-body glucose disposal. These results emphasize that lactate production is an additional metabolic role of adipose tissue beyond lipid storage and release.
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Affiliation(s)
- James R Krycer
- School of Life and Environmental Sciences, The University of Sydney, Sydney, New South Wales 2006, Australia; Charles Perkins Centre, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - Lake-Ee Quek
- Charles Perkins Centre, The University of Sydney, Sydney, New South Wales 2006, Australia; School of Mathematics and Statistics, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - Deanne Francis
- School of Life and Environmental Sciences, The University of Sydney, Sydney, New South Wales 2006, Australia; Charles Perkins Centre, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - Daniel J Fazakerley
- School of Life and Environmental Sciences, The University of Sydney, Sydney, New South Wales 2006, Australia; Charles Perkins Centre, The University of Sydney, Sydney, New South Wales 2006, Australia; Metabolic Research Laboratories, Wellcome Trust-Medical Research Council Institute of Metabolic Science, University of Cambridge, Cambridge, CB2 0QQ, United Kingdom
| | - Sarah D Elkington
- School of Life and Environmental Sciences, The University of Sydney, Sydney, New South Wales 2006, Australia; Charles Perkins Centre, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - Alexis Diaz-Vegas
- School of Life and Environmental Sciences, The University of Sydney, Sydney, New South Wales 2006, Australia; Charles Perkins Centre, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - Kristen C Cooke
- School of Life and Environmental Sciences, The University of Sydney, Sydney, New South Wales 2006, Australia; Charles Perkins Centre, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - Fiona C Weiss
- School of Life and Environmental Sciences, The University of Sydney, Sydney, New South Wales 2006, Australia; Charles Perkins Centre, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - Xiaowen Duan
- School of Life and Environmental Sciences, The University of Sydney, Sydney, New South Wales 2006, Australia; Charles Perkins Centre, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - Sergey Kurdyukov
- School of Life and Environmental Sciences, The University of Sydney, Sydney, New South Wales 2006, Australia; Charles Perkins Centre, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - Ping-Xin Zhou
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9038; School of Basic Medical Sciences, Xinxiang Medical University, Xinxiang, Henan 453003, China
| | - Uttam K Tambar
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9038
| | - Akiyoshi Hirayama
- Institute for Advanced Biosciences, Keio University, Tsuruoka, Yamagata 997-0052, Japan; AMED-CREST, Japan Agency for Medical Research and Development (AMED), 1-7-1 Otemachi, Chiyoda-Ku, Tokyo 100-0004, Japan
| | - Satsuki Ikeda
- Institute for Advanced Biosciences, Keio University, Tsuruoka, Yamagata 997-0052, Japan
| | - Yushi Kamei
- Institute for Advanced Biosciences, Keio University, Tsuruoka, Yamagata 997-0052, Japan
| | - Tomoyoshi Soga
- Institute for Advanced Biosciences, Keio University, Tsuruoka, Yamagata 997-0052, Japan; AMED-CREST, Japan Agency for Medical Research and Development (AMED), 1-7-1 Otemachi, Chiyoda-Ku, Tokyo 100-0004, Japan
| | - Gregory J Cooney
- Charles Perkins Centre, The University of Sydney, Sydney, New South Wales 2006, Australia; Sydney Medical School, The University of Sydney, Sydney, New South Wales 2006, Australia.
| | - David E James
- School of Life and Environmental Sciences, The University of Sydney, Sydney, New South Wales 2006, Australia; Charles Perkins Centre, The University of Sydney, Sydney, New South Wales 2006, Australia; Sydney Medical School, The University of Sydney, Sydney, New South Wales 2006, Australia.
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8
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Pokhrel S, Shrestha S, Timilsina A, Sapkota M, Bhatt MP, Pardhe BD. Self-Care Adherence And Barriers To Good Glycaemic Control In Nepalese Type 2 Diabetes Mellitus Patients: A Hospital-Based Cross-Sectional Study. J Multidiscip Healthc 2019; 12:817-826. [PMID: 31632050 PMCID: PMC6791337 DOI: 10.2147/jmdh.s216842] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Accepted: 09/13/2019] [Indexed: 12/14/2022] Open
Abstract
PURPOSE The patient believes in adherence to medication rather than to self-care adherence and lifestyle changes for the management of diabetes. This study was carried out to establish the association of self-care adherence and their barriers in poor glycemic control in our diabetic population. PATIENTS AND METHODS This cross-sectional study was conducted among 480 already diagnosed diabetes outpatients attended in our two hospitals. Glycaemic control was defined by levels of HbA1c. Socio-demographic data, lifestyle variables and anthropometric measurements were recorded using a standard questionnaire. Fasting blood glucose, HbA1c and lipid profiles were estimated using the manufacturer's guideline. Student's t-test and one-way ANOVA were used for comparison between different groups and the correlation was established by Spearman correlation. Risk factors associated with poor glycaemic control were verified by logistic regression analysis. RESULTS The mean HbA1c of the study population was 7.4±1.3% and 65.4% had poor glycaemic control with mean 8.0±1.1%. Higher HbA1c levels were significantly associated with duration of diabetes, a number of drugs used, patient-physician relationship and knowledge about diabetes. The poor glycaemic control was significantly associated with low adherence of following the meal plan, regular medication and regular exercising (p<0.001). Among all the barriers, a too busy schedule for following the meal plan, taking medications and exercising regularly was significantly correlated with HbA1c levels. Multivariable logistic regression analysis showed irregular meal plan (OR=5.27), irregular exercise (OR=2.25), number of medication used (OR= 0.19) and lesser extent patient-physician relationship (OR=2.68) were independent risk factors for poor glycaemic control. CONCLUSION The poor glycaemic control was associated with poor adherence to self-care adherence and their barriers in our diabetic population. Integrated knowledge on diabetes management should be targeted to improve glycaemic control in our communities.
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Affiliation(s)
- Sushant Pokhrel
- Department of Laboratory Medicine, Manmohan Memorial Institute of Health Sciences, Kathmandu, Nepal
| | - Sneha Shrestha
- Department of Laboratory Medicine, Manmohan Memorial Institute of Health Sciences, Kathmandu, Nepal
| | - Alaska Timilsina
- Department of Laboratory Medicine, Manmohan Memorial Institute of Health Sciences, Kathmandu, Nepal
| | - Manisha Sapkota
- Department of Laboratory Medicine, Manmohan Memorial Institute of Health Sciences, Kathmandu, Nepal
| | - Mahendra Prasad Bhatt
- Department of Laboratory Medicine, Manmohan Memorial Institute of Health Sciences, Kathmandu, Nepal
| | - Bashu Dev Pardhe
- Department of Laboratory Medicine, Manmohan Memorial Institute of Health Sciences, Kathmandu, Nepal
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9
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Hansson B, Morén B, Fryklund C, Vliex L, Wasserstrom S, Albinsson S, Berger K, Stenkula KG. Adipose cell size changes are associated with a drastic actin remodeling. Sci Rep 2019; 9:12941. [PMID: 31506540 PMCID: PMC6736966 DOI: 10.1038/s41598-019-49418-0] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Accepted: 08/23/2019] [Indexed: 12/21/2022] Open
Abstract
Adipose tissue plays a major role in regulating whole-body insulin sensitivity and energy metabolism. To accommodate surplus energy, the tissue rapidly expands by increasing adipose cell size (hypertrophy) and cell number (hyperplasia). Previous studies have shown that enlarged, hypertrophic adipocytes are less responsive to insulin, and that adipocyte size could serve as a predictor for the development of type 2 diabetes. In the present study, we demonstrate that changes in adipocyte size correlate with a drastic remodeling of the actin cytoskeleton. Expansion of primary adipocytes following 2 weeks of high-fat diet (HFD)-feeding in C57BL6/J mice was associated with a drastic increase in filamentous (F)-actin as assessed by fluorescence microscopy, increased Rho-kinase activity, and changed expression of actin-regulating proteins, favoring actin polymerization. At the same time, increased cell size was associated with impaired insulin response, while the interaction between the cytoskeletal scaffolding protein IQGAP1 and insulin receptor substrate (IRS)-1 remained intact. Reversed feeding from HFD to chow restored cell size, insulin response, expression of actin-regulatory proteins and decreased the amount of F-actin filaments. Together, we report a drastic cytoskeletal remodeling during adipocyte expansion, a process which could contribute to deteriorating adipocyte function.
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Affiliation(s)
- Björn Hansson
- Lund University, Department of Experimental Medical Science, Lund, Sweden
| | - Björn Morén
- Lund University, Department of Experimental Medical Science, Lund, Sweden
| | - Claes Fryklund
- Lund University, Department of Experimental Medical Science, Lund, Sweden
| | - Lars Vliex
- Lund University, Department of Experimental Medical Science, Lund, Sweden.,Maastricht University, Faculty of Health, Medicine and Life Sciences, Maastricht, The Netherlands
| | | | | | - Karin Berger
- Lund University, Department of Experimental Medical Science, Lund, Sweden
| | - Karin G Stenkula
- Lund University, Department of Experimental Medical Science, Lund, Sweden.
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10
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Mohammed MA, Mahmoud MO, Awaad AS, Gamal GM, Abdelfatah D. Alpha lipoic acid protects against dexamethasone-induced metabolic abnormalities via APPL1 and PGC-1 α up regulation. Steroids 2019; 144:1-7. [PMID: 30684496 DOI: 10.1016/j.steroids.2019.01.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/23/2018] [Revised: 01/08/2019] [Accepted: 01/17/2019] [Indexed: 11/24/2022]
Abstract
BACKGROUND Glucocorticoids (GCs) have various uses in the medicine in different specialties. However, GCs administration is usually accompanying with multiple side effects such as hyperglycemia and hyperlipidemia. Alpha lipoic acid (ALA) has been documented to posse anti-diabetic properties. AIM OF THE STUDY this study highlights the role of ALA in avoiding dexamethasone induced metabolic disturbance. MATERIALS & METHODS 30 rats were randomly divided into 5 groups: Group (1): Control group; Groups 3, 4, and 5: rats received dexamethasone 1 mg/kg/day for 10 days; Groups 2, 4, and 5: Rats received ALA 100 mg/kg/day all the duration of the study, 2 weeks before dexamethasone, or concomitant with dexamethasone respectively. For each rat, we collected blood samples for measurement of glucose, lipid profiles, adiponectin, irisin, and Phosphoinositide 3-kinase (PI3K). We also isolated gastrocnemius muscles for measurement of insulin receptor substrate-1(IRS-1), peroxisome proliferator-activated receptor γ coactivator 1 α(PGC1-α), and adaptor protein, phosphotyrosine interacting with PH domain and leucine zipper 1(APPL) gene expression. RESULTS Dexamethasone administration caused hyperglycemia, hyperlipemia, decrease the level of adiponectin, irisin, and PI3K besides decreasing the gene expression of IRS-1, PGC-1 α, and APPL1. ALA administration pre or concomitant to dexamethasone avoided these results. CONCLUSION ALA can prevent metabolic abnormalities induced by dexamethasone via PGC1α and APPL1 upregulation.
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Affiliation(s)
| | - Mohamed O Mahmoud
- Department of Biochemistry, Faculty of Pharmacy, Beni-Suef University, Egypt
| | - Ashraf Sayed Awaad
- Department of Anatomy and Embryology, Faculty of Veterinary Medicine, Beni-Suef University, Egypt
| | | | - Dina Abdelfatah
- Department of Biochemistry, Faculty of Medicine, Cairo University, Egypt
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11
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Bódis K, Roden M. Energy metabolism of white adipose tissue and insulin resistance in humans. Eur J Clin Invest 2018; 48:e13017. [PMID: 30107041 DOI: 10.1111/eci.13017] [Citation(s) in RCA: 83] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/01/2018] [Revised: 07/22/2018] [Accepted: 08/12/2018] [Indexed: 12/11/2022]
Abstract
BACKGROUND Insulin resistance not only occurs in obesity, but also in lipodystrophy. Although adipose tissue mass affects metabolic fluxes and participates in interorgan crosstalk, the role of energy metabolism within white adipose tissue for insulin resistance is less clear. MATERIALS AND METHODS A Medline search identified in vivo studies in humans on energy and lipid metabolism in subcutaneous (SAT) and visceral adipose tissue (VAT). Studies in adipocyte cultures and transgenic animal models were included for the better understanding of the link between abnormal energy metabolism in adipose tissue and insulin resistance. RESULTS The current literature indicates that higher lipolysis and lower lipogenesis in VAT compared to SAT enhance portal delivery of lipid metabolites (glycerol and fatty acids) to the liver. Thus, the lower lipolysis and higher lipogenesis in SAT favour storage of excess lipids and allow for protection of insulin-sensitive tissues from lipotoxic effects. In insulin-resistant humans, enhanced lipolysis and impaired lipogenesis in adipose tissue lead to release of cytokines and lipid metabolites, ultimately promoting insulin resistance. Adipose tissue of insulin-resistant humans also displays lower expression of proteins involved in mitochondrial function. In turn, this leads to lower availability of mitochondria-derived energy sources for lipogenesis in adipose tissue. CONCLUSIONS Abnormal mitochondrial function in human white adipose tissue likely contributes to the secretion of lipid metabolites and lactate, which are linked to insulin resistance in peripheral tissues. However, the relevance of adipose tissue energy metabolism for the regulation of human insulin sensitivity remains to be further elucidated.
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Affiliation(s)
- Kálmán Bódis
- Division of Endocrinology and Diabetology, Medical Faculty, Heinrich Heine University, Düsseldorf, Germany.,Institute for Clinical Diabetology, German Diabetes Center, Leibniz Center for Diabetes Research at Heinrich Heine University, Düsseldorf, Germany.,German Center for Diabetes Research (DZD), München-Neuherberg, Germany
| | - Michael Roden
- Division of Endocrinology and Diabetology, Medical Faculty, Heinrich Heine University, Düsseldorf, Germany.,Institute for Clinical Diabetology, German Diabetes Center, Leibniz Center for Diabetes Research at Heinrich Heine University, Düsseldorf, Germany.,German Center for Diabetes Research (DZD), München-Neuherberg, Germany
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12
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Stenkula KG, Erlanson-Albertsson C. Adipose cell size: importance in health and disease. Am J Physiol Regul Integr Comp Physiol 2018; 315:R284-R295. [DOI: 10.1152/ajpregu.00257.2017] [Citation(s) in RCA: 83] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Adipose tissue is necessary to harbor energy. To handle excess energy, adipose tissue expands by increasing adipocyte size (hypertrophy) and number (hyperplasia). Here, we have summarized the different experimental techniques used to study adipocyte cell size and describe adipocyte size in relation to insulin resistance, type 2 diabetes, and diet interventions. Hypertrophic adipocytes have an impaired cellular function, and inherent mechanisms restrict their expansion to protect against cell breakage and subsequent inflammation. Reduction of large fat cells by diet restriction, physical activity, or bariatric surgery therefore is necessary to improve cellular function and health. Small fat cells may also be dysfunctional and unable to expand. The distribution and function of the entire cell size range of fat cells, from small to very large fat cells, are an important but understudied aspect of adipose tissue biology. To prevent dysmetabolism, therapeutic strategies to expand small fat cells, recruit new fat cells, and reduce large fat cells are needed.
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Affiliation(s)
- Karin G. Stenkula
- Glucose Transport and Protein Trafficking, Biomedical Center, Lund University, Lund, Sweden
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13
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Gonzalez JT, Richardson JD, Chowdhury EA, Koumanov F, Holman GD, Cooper S, Thompson D, Tsintzas K, Betts JA. Molecular adaptations of adipose tissue to 6 weeks of morning fasting vs. daily breakfast consumption in lean and obese adults. J Physiol 2018; 596:609-622. [PMID: 29193093 PMCID: PMC5813615 DOI: 10.1113/jp275113] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2017] [Accepted: 11/13/2017] [Indexed: 12/12/2022] Open
Abstract
KEY POINTS In lean individuals, 6 weeks of extended morning fasting increases the expression of genes involved in lipid turnover (ACADM) and insulin signalling (IRS2) in subcutaneous abdominal adipose tissue. In obese individuals, 6 weeks of extended morning fasting increases IRS2 expression in subcutaneous abdominal adipose tissue. The content and activation status of key proteins involved in insulin signalling and glucose transport (GLUT4, Akt1 and Akt2) were unaffected by extended morning fasting. Therefore, any observations of altered adipose tissue insulin sensitivity with extended morning fasting do not necessarily require changes in insulin signalling proximal to Akt. Insulin-stimulated adipose tissue glucose uptake rates are lower in obese versus lean individuals, but this difference is abolished when values are normalised to whole-body fat mass. This suggests a novel hypothesis which proposes that the reduced adipose glucose uptake in obesity is a physiological down-regulation to prevent excessive de novo lipogenesis. ABSTRACT This study assessed molecular responses of human subcutaneous abdominal adipose tissue (SCAT) to 6 weeks of morning fasting. Forty-nine healthy lean (n = 29) and obese (n = 20) adults provided SCAT biopsies before and after 6 weeks of morning fasting (FAST; 0 kcal until 12.00 h) or daily breakfast consumption (BFAST; ≥700 kcal before 11.00 h). Biopsies were analysed for mRNA levels of selected genes, and GLUT4 and Akt protein content. Basal and insulin-stimulated Akt activation and tissue glucose uptake rates were also determined. In lean individuals, lipid turnover and insulin signalling genes (ACADM and IRS2) were up-regulated with FAST versus BFAST (ACADM: 1.14 (95% CI: 0.97-1.30) versus 0.80 (95% CI: 0.64-0.96), P = 0.007; IRS2: 1.75 (95% CI: 1.33-2.16) versus 1.09 (95% CI: 0.67-1.51), P = 0.03, respectively). In obese individuals, no differential (FAST versus BFAST) expression was observed in genes involved in lipid turnover (all P > 0.1). GLUT4, Akt protein content and insulin-stimulated Akt phosphorylation were unaffected by FAST versus BFAST in both lean and obese cohorts (all P > 0.1). Lower insulin-stimulated glucose uptake rates in obese versus lean individuals were eradicated when normalised to whole-body fat mass (P = 0.416). We conclude that morning fasting up-regulates lipid turnover genes in SCAT of lean individuals. Secondly, altered SCAT insulin sensitivity with morning fasting is unlikely to be explained by signalling proximal to Akt. Finally, lower insulin-stimulated SCAT glucose uptake rates in obese individuals are proportional to whole-body fat mass, suggesting a compensatory down-regulation, presumably to prevent excessive de novo lipogenesis in adipose tissue. This trial was registered as ISRCTN31521726.
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Affiliation(s)
| | | | | | - Francoise Koumanov
- Department for HealthUniversity of BathBathBA2 7AYUK
- Department of Biology & BiochemistryUniversity of BathBathBA2 7AYUK
| | | | - Scott Cooper
- School of Life SciencesQueen's Medical CentreNottinghamNG7 2UHUK
| | | | - Kostas Tsintzas
- School of Life SciencesQueen's Medical CentreNottinghamNG7 2UHUK
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14
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Systemic and vascular inflammation in an in-vitro model of central obesity. PLoS One 2018; 13:e0192824. [PMID: 29438401 PMCID: PMC5811040 DOI: 10.1371/journal.pone.0192824] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2017] [Accepted: 01/31/2018] [Indexed: 12/31/2022] Open
Abstract
Metabolic disorders due to over-nutrition are a major global health problem, often associated with obesity and related morbidities. Obesity is peculiar to humans, as it is associated with lifestyle and diet, and so difficult to reproduce in animal models. Here we describe a model of human central adiposity based on a 3-tissue system consisting of a series of interconnected fluidic modules. Given the causal link between obesity and systemic inflammation, we focused primarily on pro-inflammatory markers, examining the similarities and differences between the 3-tissue model and evidence from human studies in the literature. When challenged with high levels of adiposity, the in-vitro system manifests cardiovascular stress through expression of E-selectin and von Willebrand factor as well as systemic inflammation (expressing IL-6 and MCP-1) as observed in humans. Interestingly, most of the responses are dependent on the synergic interaction between adiposity and the presence of multiple tissue types. The set-up has the potential to reduce animal experiments in obesity research and may help unravel specific cellular mechanisms which underlie tissue response to nutritional overload.
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15
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Dadson P, Ferrannini E, Landini L, Hannukainen JC, Kalliokoski KK, Vaittinen M, Honka H, Karlsson HK, Tuulari JJ, Soinio M, Salminen P, Parkkola R, Pihlajamäki J, Iozzo P, Nuutila P. Fatty acid uptake and blood flow in adipose tissue compartments of morbidly obese subjects with or without type 2 diabetes: effects of bariatric surgery. Am J Physiol Endocrinol Metab 2017; 313:E175-E182. [PMID: 28400411 DOI: 10.1152/ajpendo.00044.2017] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/06/2017] [Revised: 03/21/2017] [Accepted: 04/06/2017] [Indexed: 11/22/2022]
Abstract
Body fat accumulation, distribution, and metabolic activity are factors in the pathophysiology of obesity and type 2 diabetes (T2D). We investigated adipose blood flow, fatty acid uptake (FAU), and subcutaneous and visceral fat cellularity in obese patients with or without T2D. A total of 23 morbidly obese (mean body mass index = 42 kg/m2) patients were studied before and 6 mo after bariatric surgery; 15 nonobese subjects served as controls. Positron emission tomography was used to measure tissue FAU (with 18F-FTHA) and blood flow (with H215O); MRI was used for fat distribution and fat biopsy for adipocyte size. Obese subjects had subcutaneous hyperplasia and hypertrophy and lower blood flow; when expressed per cell, flow was similar to controls. FAU into subcutaneous and visceral depots was increased in the obese; per unit tissue mass, however, FAU was similar to controls but reduced in skeletal muscle. Fatty acid fractional extraction in subcutaneous fat and muscle was only increased in obese patients with T2D. We conclude that surgery reduces subcutaneous fat hyperplasia and hypertrophy; subcutaneous blood flow and FAU decrease in absolute terms and per cell while fractional FAU remains unchanged in T2D. In the obese, subcutaneous blood flow is a determinant of FAU and is coupled with cellularity; efficiency of FAU is enhanced in subcutaneous fat and muscle in T2D.
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Affiliation(s)
- Prince Dadson
- Turku PET Centre, University of Turku, Turku, Finland
| | - Ele Ferrannini
- National Research Council Institute of Clinical Physiology, Pisa, Italy
| | - Linda Landini
- Turku PET Centre, University of Turku, Turku, Finland
- National Research Council Institute of Clinical Physiology, Pisa, Italy
| | | | | | - Maija Vaittinen
- Turku PET Centre, University of Turku, Turku, Finland
- Institute of Public Health and Clinical Nutrition, University of Eastern Finland, Kuopio, Finland
| | - Henri Honka
- Turku PET Centre, University of Turku, Turku, Finland
| | | | | | - Minna Soinio
- Department of Endocrinology, Turku University Hospital, Turku, Finland
| | - Paulina Salminen
- Division of Digestive Surgery and Urology, Department of Acute and Digestive Surgery, Turku University Hospital, Turku, Finland
| | - Riitta Parkkola
- Medical Imaging Center, Turku University Hospital, Department of Radiology, University of Turku and Turku University Hospital, Turku, Finland; and
| | - Jussi Pihlajamäki
- Institute of Public Health and Clinical Nutrition, University of Eastern Finland, Kuopio, Finland
- Institute of Public Health and Clinical Nutrition, Department of Clinical Nutrition and Obesity Center, Kuopio University Hospital, Kuopio, Finland
| | - Patricia Iozzo
- National Research Council Institute of Clinical Physiology, Pisa, Italy
| | - Pirjo Nuutila
- Turku PET Centre, University of Turku, Turku, Finland;
- Department of Endocrinology, Turku University Hospital, Turku, Finland
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16
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Bala C, Craciun AE, Hancu N. UPDATING THE CONCEPT OF METABOLICALLY HEALTHY OBESITY. ACTA ENDOCRINOLOGICA (BUCHAREST, ROMANIA : 2005) 2016; 12:197-205. [PMID: 31149087 PMCID: PMC6535297 DOI: 10.4183/aeb.2016.197] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Obesity is a well-recognized risk factor for type 2 diabetes, cardiovascular disease, and several types of cancer. However, a proportion of the obese individuals display a significantly lower risk for metabolic complications than expected for their degree of body mass index, and this subtype of obesity was described as "metabolically healthy obesity" (MHO). No universally accepted criteria for the diagnosis of MHO exists and the prevalence of this subtype of obesity varies largely according to criteria used. Broadly, MHO is characterized by a lower amount of visceral fat, a more favorable inflammatory profile, and less insulin resistance as compared to the metabolically unhealthy obesity. Currently, controversies exist regarding the risk of cardiovascular events and all-cause mortality associated with MHO as compared to metabolically-healthy non-obese individuals. Further research is needed in order to identify the MHO phenotype and if MHO is truly healthy for a long period of time or if it is a transient state from normal metabolic/normal weight to abnormal metabolic/obese state. This review will discuss the MHO definition criteria; the differences between MHO and metabolically unhealthy obesity; the possible underlying mechanisms and clinical implications of MHO.
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Affiliation(s)
| | - A-E. Craciun
- “Iuliu Haţieganu” University of Medicine and Pharmacy, Dept. of Diabetes, Nutrition and Metabolic Diseases, Cluj-Napoca, Romania
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17
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Arble DM, Bass J, Behn CD, Butler MP, Challet E, Czeisler C, Depner CM, Elmquist J, Franken P, Grandner MA, Hanlon EC, Keene AC, Joyner MJ, Karatsoreos I, Kern PA, Klein S, Morris CJ, Pack AI, Panda S, Ptacek LJ, Punjabi NM, Sassone-Corsi P, Scheer FA, Saxena R, Seaquest ER, Thimgan MS, Van Cauter E, Wright KP. Impact of Sleep and Circadian Disruption on Energy Balance and Diabetes: A Summary of Workshop Discussions. Sleep 2015; 38:1849-60. [PMID: 26564131 DOI: 10.5665/sleep.5226] [Citation(s) in RCA: 110] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2015] [Accepted: 10/26/2015] [Indexed: 12/21/2022] Open
Abstract
A workshop was held at the National Institute for Diabetes and Digestive and Kidney Diseases with a focus on the impact of sleep and circadian disruption on energy balance and diabetes. The workshop identified a number of key principles for research in this area and a number of specific opportunities. Studies in this area would be facilitated by active collaboration between investigators in sleep/circadian research and investigators in metabolism/diabetes. There is a need to translate the elegant findings from basic research into improving the metabolic health of the American public. There is also a need for investigators studying the impact of sleep/circadian disruption in humans to move beyond measurements of insulin and glucose and conduct more in-depth phenotyping. There is also a need for the assessments of sleep and circadian rhythms as well as assessments for sleep-disordered breathing to be incorporated into all ongoing cohort studies related to diabetes risk. Studies in humans need to complement the elegant short-term laboratory-based human studies of simulated short sleep and shift work etc. with studies in subjects in the general population with these disorders. It is conceivable that chronic adaptations occur, and if so, the mechanisms by which they occur needs to be identified and understood. Particular areas of opportunity that are ready for translation are studies to address whether CPAP treatment of patients with pre-diabetes and obstructive sleep apnea (OSA) prevents or delays the onset of diabetes and whether temporal restricted feeding has the same impact on obesity rates in humans as it does in mice.
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Affiliation(s)
- Deanna M Arble
- Department of Surgery, University of Michigan, Ann Arbor, MI
| | - Joseph Bass
- Department of Medicine, Endocrinology Division, Feinberg School of Medicine, Northwestern University, Chicago, IL
| | - Cecilia Diniz Behn
- Department of Applied Mathematics & Statistics, Colorado School of Mines, Golden, CO
| | - Matthew P Butler
- Oregon Institute of Occupational Health Sciences, Oregon Health and Science University, Portland, OR
| | - Etienne Challet
- Institute for Cellular and Integrative Neuroscience, CNRS, University of Strasbourg, France
| | - Charles Czeisler
- Departments of Medicine and Neurology, Brigham and Women's Hospital, Boston, MA
| | | | - Joel Elmquist
- Departments of Internal Medicine, Pharmacology and Psychiatry, The University of Texas Southwestern Medical Center, Dallas, TX
| | - Paul Franken
- Center for Integrative Genomics, University of Lausanne, Switzerland
| | | | - Erin C Hanlon
- Department of Medicine, The University of Chicago, Chicago, IL
| | - Alex C Keene
- Department of Biology, University of Nevada, Reno, NV
| | | | - Ilia Karatsoreos
- Department of Integrative Physiology and Neuroscience, College of Veterinary Medicine, Washington State University, Pullman, WA
| | - Philip A Kern
- Department of Medicine, Division of Endocrinology and Center for Clinical and Translational Sciences, University of Kentucky, Lexington, KY
| | - Samuel Klein
- Center for Human Nutrition, Washington University School of Medicine in St. Louis, St. Louis, MO
| | | | - Allan I Pack
- Division of Sleep Medicine/Department of Medicine and Center for Sleep and Circadian Neurobiology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA
| | - Satchidananda Panda
- Regulatory Biology Laboratory, Salk Institute for Biological Studies, La Jolla, CA
| | - Louis J Ptacek
- Department of Neurology, Howard Hughes Medical Institute, University of California, San Francisco, CA
| | - Naresh M Punjabi
- Department of Medicine, The Johns Hopkins University, Baltimore, MD
| | - Paolo Sassone-Corsi
- Center for Epigenetics and Metabolism, School of Medicine, University of California, Irvine, CA
| | - Frank A Scheer
- Departments of Medicine and Neurology, Brigham and Women's Hospital, Boston, MA
| | - Richa Saxena
- Department of Anesthesia, Massachusetts General Hospital and Harvard Medical School, Boston, MA
| | - Elizabeth R Seaquest
- Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, University of Minnesota, Minneapolis, MN
| | - Matthew S Thimgan
- Department of Biological Sciences, Missouri University of Science and Technology, Rolla, MO
| | - Eve Van Cauter
- Sleep, Metabolism and Health Center, The University of Chicago, Chicago, IL
| | - Kenneth P Wright
- Department of Integrative Physiology, University of Colorado, Boulder, CO.,Division of Endocrinology, Metabolism and Diabetes, University of Colorado Anschutz Medical Campus, Aurora, CO
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18
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Jankovic A, Korac A, Buzadzic B, Otasevic V, Stancic A, Daiber A, Korac B. Redox implications in adipose tissue (dys)function--A new look at old acquaintances. Redox Biol 2015; 6:19-32. [PMID: 26177468 PMCID: PMC4511633 DOI: 10.1016/j.redox.2015.06.018] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2015] [Revised: 06/25/2015] [Accepted: 06/30/2015] [Indexed: 12/15/2022] Open
Abstract
Obesity is an energy balance disorder associated with dyslipidemia, insulin resistance and diabetes type 2, also summarized with the term metabolic syndrome or syndrome X. Increasing evidence points to “adipocyte dysfunction”, rather than fat mass accretion per se, as the key pathophysiological factor for metabolic complications in obesity. The dysfunctional fat tissue in obesity characterizes a failure to safely store metabolic substrates into existing hypertrophied adipocytes and/or into new preadipocytes recruited for differentiation. In this review we briefly summarize the potential of redox imbalance in fat tissue as an instigator of adipocyte dysfunction in obesity. We reveal the challenge of the adipose redox changes, insights in the regulation of healthy expansion of adipose tissue and its reduction, leading to glucose and lipids overflow. Adipose tissue (AT) buffers nutrient excess determining overall metabolic health. Redox insight in lipid storage and adipogenesis of AT is reviewed. Redox modulation of AT as therapeutic target in obesity/syndrome X is considered.
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Affiliation(s)
- Aleksandra Jankovic
- University of Belgrade, Department of Physiology, Institute for Biological Research "Sinisa Stankovic", Bulevar Despota Stefana 142, 11060 Belgrade, Serbia
| | - Aleksandra Korac
- University of Belgrade, Faculty of Biology, Center for Electron Microscopy, Belgrade, Serbia
| | - Biljana Buzadzic
- University of Belgrade, Department of Physiology, Institute for Biological Research "Sinisa Stankovic", Bulevar Despota Stefana 142, 11060 Belgrade, Serbia
| | - Vesna Otasevic
- University of Belgrade, Department of Physiology, Institute for Biological Research "Sinisa Stankovic", Bulevar Despota Stefana 142, 11060 Belgrade, Serbia
| | - Ana Stancic
- University of Belgrade, Department of Physiology, Institute for Biological Research "Sinisa Stankovic", Bulevar Despota Stefana 142, 11060 Belgrade, Serbia
| | - Andreas Daiber
- 2nd Medical Department, Molecular Cardiology, University Medical Center, Mainz, Germany
| | - Bato Korac
- University of Belgrade, Department of Physiology, Institute for Biological Research "Sinisa Stankovic", Bulevar Despota Stefana 142, 11060 Belgrade, Serbia.
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19
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Tan SX, Fisher-Wellman KH, Fazakerley DJ, Ng Y, Pant H, Li J, Meoli CC, Coster ACF, Stöckli J, James DE. Selective insulin resistance in adipocytes. J Biol Chem 2015; 290:11337-48. [PMID: 25720492 DOI: 10.1074/jbc.m114.623686] [Citation(s) in RCA: 77] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2014] [Indexed: 12/14/2022] Open
Abstract
Aside from glucose metabolism, insulin regulates a variety of pathways in peripheral tissues. Under insulin-resistant conditions, it is well known that insulin-stimulated glucose uptake is impaired, and many studies attribute this to a defect in Akt signaling. Here we make use of several insulin resistance models, including insulin-resistant 3T3-L1 adipocytes and fat explants prepared from high fat-fed C57BL/6J and ob/ob mice, to comprehensively distinguish defective from unaffected aspects of insulin signaling and its downstream consequences in adipocytes. Defective regulation of glucose uptake was observed in all models of insulin resistance, whereas other major actions of insulin such as protein synthesis and anti-lipolysis were normal. This defect corresponded to a reduction in the maximum response to insulin. The pattern of change observed for phosphorylation in the Akt pathway was inconsistent with a simple defect at the level of Akt. The only Akt substrate that showed consistently reduced phosphorylation was the RabGAP AS160 that regulates GLUT4 translocation. We conclude that insulin resistance in adipose tissue is highly selective for glucose metabolism and likely involves a defect in one of the components regulating GLUT4 translocation to the cell surface in response to insulin.
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Affiliation(s)
- Shi-Xiong Tan
- From the Garvan Institute of Medical Research, Darlinghurst, Sydney, New South Wales 2010, Australia
| | - Kelsey H Fisher-Wellman
- From the Garvan Institute of Medical Research, Darlinghurst, Sydney, New South Wales 2010, Australia
| | | | - Yvonne Ng
- From the Garvan Institute of Medical Research, Darlinghurst, Sydney, New South Wales 2010, Australia
| | - Himani Pant
- From the Garvan Institute of Medical Research, Darlinghurst, Sydney, New South Wales 2010, Australia
| | - Jia Li
- From the Garvan Institute of Medical Research, Darlinghurst, Sydney, New South Wales 2010, Australia
| | - Christopher C Meoli
- From the Garvan Institute of Medical Research, Darlinghurst, Sydney, New South Wales 2010, Australia, the Charles Perkins Centre, School of Molecular Biosciences and
| | - Adelle C F Coster
- the School of Mathematics and Statistics, University of New South Wales, Sydney, New South Wales 2052, Australia
| | | | - David E James
- the Charles Perkins Centre, School of Molecular Biosciences and the School of Medicine, University of Sydney, New South Wales 2006, Australia, and
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20
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Sabater D, Arriarán S, Romero MDM, Agnelli S, Remesar X, Fernández-López JA, Alemany M. Cultured 3T3L1 adipocytes dispose of excess medium glucose as lactate under abundant oxygen availability. Sci Rep 2014; 4:3663. [PMID: 24413028 PMCID: PMC5379156 DOI: 10.1038/srep03663] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2013] [Accepted: 12/16/2013] [Indexed: 12/27/2022] Open
Abstract
White adipose tissue (WAT) produces lactate in significant amount from circulating glucose, especially in obesity;Under normoxia, 3T3L1 cells secrete large quantities of lactate to the medium, again at the expense of glucose and proportionally to its levels. Most of the glucose was converted to lactate with only part of it being used to synthesize fat. Cultured adipocytes were largely anaerobic, but this was not a Warburg-like process. It is speculated that the massive production of lactate, is a process of defense of the adipocyte, used to dispose of excess glucose. This way, the adipocyte exports glucose carbon (and reduces the problem of excess substrate availability) to the liver, but the process may be also a mechanism of short-term control of hyperglycemia. The in vivo data obtained from adipose tissue of male rats agree with this interpretation.
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Affiliation(s)
- David Sabater
- 1] Department of Nutrition and Food Science, Faculty of Biology, University of Barcelona, Barcelona 08028, Spain [2] Institute of Biomedicine, University of Barcelona, Barcelona 08028, Spain [3] CIBER Obesity and Nutrition, Institute of Health Carlos III, Spain
| | - Sofía Arriarán
- 1] Department of Nutrition and Food Science, Faculty of Biology, University of Barcelona, Barcelona 08028, Spain [2] Institute of Biomedicine, University of Barcelona, Barcelona 08028, Spain [3] CIBER Obesity and Nutrition, Institute of Health Carlos III, Spain
| | - María del Mar Romero
- 1] Department of Nutrition and Food Science, Faculty of Biology, University of Barcelona, Barcelona 08028, Spain [2] Institute of Biomedicine, University of Barcelona, Barcelona 08028, Spain [3] CIBER Obesity and Nutrition, Institute of Health Carlos III, Spain
| | - Silvia Agnelli
- 1] Department of Nutrition and Food Science, Faculty of Biology, University of Barcelona, Barcelona 08028, Spain [2] Institute of Biomedicine, University of Barcelona, Barcelona 08028, Spain [3] CIBER Obesity and Nutrition, Institute of Health Carlos III, Spain
| | - Xavier Remesar
- 1] Department of Nutrition and Food Science, Faculty of Biology, University of Barcelona, Barcelona 08028, Spain [2] Institute of Biomedicine, University of Barcelona, Barcelona 08028, Spain [3] CIBER Obesity and Nutrition, Institute of Health Carlos III, Spain
| | - José Antonio Fernández-López
- 1] Department of Nutrition and Food Science, Faculty of Biology, University of Barcelona, Barcelona 08028, Spain [2] Institute of Biomedicine, University of Barcelona, Barcelona 08028, Spain [3] CIBER Obesity and Nutrition, Institute of Health Carlos III, Spain
| | - Marià Alemany
- 1] Department of Nutrition and Food Science, Faculty of Biology, University of Barcelona, Barcelona 08028, Spain [2] Institute of Biomedicine, University of Barcelona, Barcelona 08028, Spain [3] CIBER Obesity and Nutrition, Institute of Health Carlos III, Spain
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21
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Lopes P, Fuhrmann A, Sereno J, Pereira MJ, Nunes P, Pedro J, Melão A, Reis F, Carvalho E. Effects of cyclosporine and sirolimus on insulin-stimulated glucose transport and glucose tolerance in a rat model. Transplant Proc 2013; 45:1142-8. [PMID: 23622647 DOI: 10.1016/j.transproceed.2013.02.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Cyclosporine (CsA) and sirolimus (SRL) have been associated with undesirable side effects, including posttransplantation diabetes and hyperlipidemia, but the molecular mechanisms underlying these effects remain to be elucidated. Animal studies focusing on clinically relevant doses are advised. This study sought to compare the metabolic effects on isolated rat adipocytes treated with either CsA or SRL ex vivo and after long-term in vivo treatment in Wistar rats. We assessed the ex vivo effects of CsA (0.5-30 μmol/L) and SRL (1-250 μmol/L) on insulin-stimulated (14)C-glucose uptake in epididymal adipocytes (n = 6-9). In parallel, rats (n = 12) were treated with either vehicle, CsA (5 mg/kg/d) or SRL (1 mg/kg/d) for either 3 or 9 weeks. At the end of the treatment, glucose tolerance test (GTT) and insulin-stimulated (14)C-glucose uptake as well as biochemical parameters were analyzed. A significant reduction in the insulin-stimulated glucose uptake over basal was observed among isolated adipocytes, whether exposed ex vivo or in vivo to CsA or SRL treatment. Furthermore, the SRL group showed significantly lighter fat pads and smaller adipocytes at 3 weeks with a smaller gain in body weight throughout the study compared with either the vehicle or CsA cohorts. Glucose intolerance was observed after a GTT, at the end of the treatment with either drug. Additionally, at 9 weeks serum triglycerides were increased by CsA compared with vehicle or SRL treatment. Interestingly, although SRL-treated animals presented higher fed and fasted insulin levels compared with either group, suggesting insulin resistance, the CsA group presented lower fed and fasted insulin values, suggesting a defect in insulin secretion at 9 weeks. These results suggested that either ex vivo treatment of fat cells or in vivo treatment of rats with CsA or SRL impaired insulin-stimulated glucose uptake by adipocytes. Both drugs caused glucose intolerance, which altogether could be responsible for the development of posttransplantation diabetes.
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Affiliation(s)
- P Lopes
- Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal
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22
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Mohamed EAH, Yam MF, Ang LF, Mohamed AJ, Asmawi MZ. Antidiabetic properties and mechanism of action of Orthosiphon stamineus Benth bioactive sub-fraction in streptozotocin-induced diabetic rats. J Acupunct Meridian Stud 2013; 6:31-40. [PMID: 23433053 DOI: 10.1016/j.jams.2013.01.005] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2011] [Revised: 04/26/2012] [Accepted: 05/03/2012] [Indexed: 10/27/2022] Open
Abstract
Orthosiphon stamineus is a popular folk medicine widely used to treat many diseases including diabetes. Previous studies have shown that the sub-fraction of chloroform extract was able to inhibit the rise of blood glucose levels in a glucose tolerance test. This study was carried out to evaluate the chronic effect and possible mechanism of action of the bioactive chloroform sub-fraction of O. stamineus using streptozotocin-induced diabetic rats and in vitro methods. Administration of the chloroform extract sub-fraction 2 (Cƒ2-b) at a dose of 1 g/kg twice daily on diabetic rats for 14 days showed a significant lowering (p < 0.05) of the final blood glucose level compared to the pretreatment level. However, there were no significant differences in the plasma insulin levels post-treatment compared to the pretreatment levels for all doses of Cƒ2-b. Conversely, Cƒ2-b at a concentration of 2 mg/mL significantly increased (p < 0.001) the glucose uptake by the rat diaphragm muscle. The increase in glucose uptake was also shown when the muscle was incubated in a solution containing 1 IU/mL of insulin or 1 mg/mL of metformin. Furthermore, the effect of this sub-fraction on glucose absorption in the everted rat jejunum showed that Cƒ2-b at concentrations of 0.5 mg/mL, 1 mg/mL and, 2 mg/mL significantly reduced the glucose absorption of the jejunum (p < 0.05-0.001). Similarly, the absorption of glucose was also inhibited by 1 mg/mL and 2 mg/mL of metformin (p < 0.001). These results suggest that the effect of Cƒ2-b may be due to extra-pancreatic mechanisms. There was no evidence that the plant extract stimulated the release of insulin in order to lower the blood glucose level.
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Broussard JL, Ehrmann DA, Van Cauter E, Tasali E, Brady MJ. Impaired insulin signaling in human adipocytes after experimental sleep restriction: a randomized, crossover study. Ann Intern Med 2012; 157:549-57. [PMID: 23070488 PMCID: PMC4435718 DOI: 10.7326/0003-4819-157-8-201210160-00005] [Citation(s) in RCA: 248] [Impact Index Per Article: 20.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND Insufficient sleep increases the risk for insulin resistance, type 2 diabetes, and obesity, suggesting that sleep restriction may impair peripheral metabolic pathways. Yet, a direct link between sleep restriction and alterations in molecular metabolic pathways in any peripheral human tissue has not been shown. OBJECTIVE To determine whether sleep restriction results in reduced insulin sensitivity in subcutaneous fat, a peripheral tissue that plays a pivotal role in energy metabolism and balance. DESIGN Randomized, 2-period, 2-condition, crossover clinical study. SETTING University of Chicago Clinical Resource Center. PARTICIPANTS Seven healthy adults (1 woman, 6 men) with a mean age of 23.7 years (SD, 3.8) and mean body mass index of 22.8 kg/m(2) (SD, 1.6). INTERVENTION Four days of 4.5 hours in bed or 8.5 hours in bed under controlled conditions of caloric intake and physical activity. MEASUREMENTS Adipocytes collected from subcutaneous fat biopsy samples after normal and restricted sleep conditions were exposed to incremental insulin concentrations. The ability of insulin to increase levels of phosphorylated Akt (pAkt), a crucial step in the insulin-signaling pathway, was assessed. Total Akt (tAkt) served as a loading control. The insulin concentration for the half-maximal stimulation of the pAkt-tAkt ratio was used as a measure of cellular insulin sensitivity. Total body insulin sensitivity was assessed using a frequently sampled intravenous glucose tolerance test. RESULTS The insulin concentration for the half-maximal pAkt-tAkt response was nearly 3-fold higher (mean, 0.71 nM [SD, 0.27] vs. 0.24 nM [SD, 0.24]; P = 0.01; mean difference, 0.47 nM [SD, 0.33]; P = 0.01), and the total area under the receiver-operating characteristic curve of the pAkt-tAkt response was 30% lower (P = 0.01) during sleep restriction than during normal sleep. A reduction in total body insulin sensitivity (P = 0.02) paralleled this impaired cellular insulin sensitivity. LIMITATION This was a single-center study with a small sample size. CONCLUSION Sleep restriction results in an insulin-resistant state in human adipocytes. Sleep may be an important regulator of energy metabolism in peripheral tissues. PRIMARY FUNDING SOURCE National Institutes of Health.
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Pereira MJ, Palming J, Rizell M, Aureliano M, Carvalho E, Svensson MK, Eriksson JW. mTOR inhibition with rapamycin causes impaired insulin signalling and glucose uptake in human subcutaneous and omental adipocytes. Mol Cell Endocrinol 2012; 355:96-105. [PMID: 22333157 DOI: 10.1016/j.mce.2012.01.024] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/12/2011] [Revised: 01/17/2012] [Accepted: 01/27/2012] [Indexed: 02/07/2023]
Abstract
Rapamycin is an immunosuppressive agent used after organ transplantation, but its molecular effects on glucose metabolism needs further evaluation. We explored rapamycin effects on glucose uptake and insulin signalling proteins in adipocytes obtained via subcutaneous (n=62) and omental (n=10) fat biopsies in human donors. At therapeutic concentration (0.01 μM) rapamycin reduced basal and insulin-stimulated glucose uptake by 20-30%, after short-term (15 min) or long-term (20 h) culture of subcutaneous (n=23 and n=10) and omental adipocytes (n=6 and n=7). Rapamycin reduced PKB Ser473 and AS160 Thr642 phosphorylation, and IRS2 protein levels in subcutaneous adipocytes. Additionally, it reduced mTOR-raptor, mTOR-rictor and mTOR-Sin1 interactions, suggesting decreased mTORC1 and mTORC2 formation. Rapamycin also reduced IR Tyr1146 and IRS1 Ser307/Ser616/Ser636 phosphorylation, whereas no effects were observed on the insulin stimulated IRS1-Tyr and TSC2 Thr1462 phosphorylation. This is the first study to show that rapamycin reduces glucose uptake in human adipocytes through impaired insulin signalling and this may contribute to the development of insulin resistance associated with rapamycin therapy.
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Affiliation(s)
- Maria J Pereira
- The Lundberg Laboratory for Diabetes Research, Department of Molecular and Clinical Medicine, The Sahlgrenska Academy at University of Gothenburg, 413 45 Gothenburg, Sweden.
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25
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Lactate and the GPR81 receptor in metabolic regulation: implications for adipose tissue function and fatty acid utilisation by muscle during exercise. Br J Nutr 2011; 106:1310-6. [PMID: 21902860 DOI: 10.1017/s0007114511004673] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Lactate is increasingly recognised to be more than a simple end product of anaerobic glycolysis. Skeletal muscle and white adipose tissue are considered to be the main sites of lactate production and release. Recent studies have demonstrated that there is a specific G-protein coupled receptor for lactate, GPR81, which is expressed primarily in adipose tissue, and also in muscle. Lactate inhibits lipolysis in adipose tissue by mediating, through GPR81, the anti-lipolytic action of insulin. A high proportion (50 % or more) of the glucose utilised by white adipose tissue is converted to lactate and lactate production by the tissue increases markedly in obesity; this is likely to reflect a switch towards anaerobic metabolism with the development of hypoxia in the tissue. During exercise, there is a shift in fuel utilisation by muscle from lipid to carbohydrate, but this does not appear to be a result of the inhibition of lipolysis in the main adipose tissue depots by muscle-derived lactate. It is suggested instead that a putative autocrine lactate loop in myocytes may regulate fuel utilisation by muscle during exercise, operating via a muscle GPR81 receptor. In addition to being an important substrate, lactate is a key signal in metabolic regulation.
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26
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Betts JA, Thompson D, Richardson JD, Chowdhury EA, Jeans M, Holman GD, Tsintzas K. Bath Breakfast Project (BBP)--examining the role of extended daily fasting in human energy balance and associated health outcomes: study protocol for a randomised controlled trial [ISRCTN31521726]. Trials 2011; 12:172. [PMID: 21740575 PMCID: PMC3146843 DOI: 10.1186/1745-6215-12-172] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2011] [Accepted: 07/08/2011] [Indexed: 12/26/2022] Open
Abstract
BACKGROUND Current guidance regarding the role of daily breakfast in human health is largely grounded in cross-sectional observations. However, the causal nature of these relationships has not been fully explored and what limited information is emerging from controlled laboratory-based experiments appears inconsistent with much existing data. Further progress in our understanding therefore requires a direct examination of how daily breakfast impacts human health under free-living conditions. METHODS/DESIGN The Bath Breakfast Project (BBP) is a randomised controlled trial comparing the effects of daily breakfast consumption relative to extended fasting on energy balance and human health. Approximately 70 men and women will undergo extensive laboratory-based assessments of their acute metabolic responses under fasted and post-prandial conditions, to include: resting metabolic rate, substrate oxidation, dietary-induced thermogenesis and systemic concentrations of key metabolites/hormones. Physiological and psychological indices of appetite will also be monitored both over the first few hours of the day (i.e. whether fed or fasted) and also following a standardised test lunch used to assess voluntary energy intake under controlled conditions. Baseline measurements of participants' anthropometric characteristics (e.g. DEXA) will be recorded prior to intervention, along with an oral glucose tolerance test and acquisition of adipose tissue samples to determine expression of key genes and estimates of tissue-specific insulin action. Participants will then be randomly assigned either to a group prescribed an energy intake of ≥3000 kJ before 1100 each day or a group to extend their overnight fast by abstaining from ingestion of energy-providing nutrients until 1200 each day, with all laboratory-based measurements followed-up 6 weeks later. Free-living assessments of energy intake (via direct weighed food diaries) and energy expenditure (via combined heart-rate/accelerometry) will be made during the first and last week of intervention, with continuous glucose monitors worn both to document chronic glycaemic responses to the intervention and to verify compliance.
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Affiliation(s)
- James A Betts
- Human Physiology Research Group, Department for Health, University of Bath, BA2 7AY, UK
| | - Dylan Thompson
- Human Physiology Research Group, Department for Health, University of Bath, BA2 7AY, UK
| | - Judith D Richardson
- Human Physiology Research Group, Department for Health, University of Bath, BA2 7AY, UK
| | - Enhad A Chowdhury
- Human Physiology Research Group, Department for Health, University of Bath, BA2 7AY, UK
| | - Matthew Jeans
- Human Physiology Research Group, Department for Health, University of Bath, BA2 7AY, UK
| | - Geoffrey D Holman
- Department of Biology and Biochemistry, University of Bath, BA2 7AY, UK
| | - Kostas Tsintzas
- School of Biomedical Sciences, Queen's Medical Centre, Nottingham, NG7 2UH, UK
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Abstract
Over the last decades, substantial progress has been made in defining the molecular events and relevant tissues controlling insulin action and the potential defects that lead to insulin resistance and later on Type 2 diabetes mellitus (T2DM). Mitochondrial dysfunction has been postulated as a common mechanism implicated in the development of insulin resistance and T2DM aetiology. Since then there has been growing interest in this area of research and many studies have addressed whether mitochondrial function/dysfunction is implicated in the progression of T2DM or if it is just a consequence. Mitochondria are adjusted to the specific needs of the tissue and to the environmental interactions or pathophysiological state that it encounters. This review offers a current state of the subject in a tissue specific approach. We will focus our attention on skeletal muscle, liver, and white adipose tissue as the main insulin sensitive organs. Hypothalamic mitochondrial function will be also discussed.
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Affiliation(s)
- Pablo M Garcia-Roves
- Diabetes and Obesity Laboratory, Institute for Biomedical Research August Pi i Sunyer (IDIBAPS) and Spanish Biomedical Research Centre in Diabetes and Associated Metabolic Disorders (CIBERDEM), Barcelona, Spain.
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Arrieta-Blanco F, Botella-Carretero JI, Iglesias P, Balsa JA, Zamarrón I, De la Puerta C, Arrieta JJ, Ramos F, Vázquez C, Rovira A. Insulin action in adipose tissue in type 1 diabetes. Int J Gen Med 2011; 4:153-7. [PMID: 21475629 PMCID: PMC3068878 DOI: 10.2147/ijgm.s15809] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2011] [Indexed: 01/21/2023] Open
Abstract
Background: Insulin action has been reported to be normal in type 1 diabetic patients. However, some studies have reported an insulin resistance state in these patients. The aim of this study was to investigate insulin resistance in a group of type 1 diabetic patients. We studied the insulin action in adipose tissue and analyzed the effects of duration of disease, body mass index (BMI), and glycosylated hemoglobin on insulin action at the receptor and postreceptor levels in adipocytes. Methods: Nine female type 1 diabetic patients with different durations of disease and eight nondiabetic female patients of comparable age and BMI were studied. 125I-insulin binding and U-[14C]-D-glucose transport was measured in a sample of subcutaneous gluteus adipose tissue obtained by open surgical biopsy from each subject. Results: The duration of disease was negatively correlated with both 125I-insulin binding capacity (r = −0.70, P < 0.05) and basal and maximum insulin-stimulated glucose transport (r = −0.87, P < 0.01, and r = −0.88, P < 0.01, respectively). Maximum specific 125I-insulin binding to the receptors in adipocytes was higher in the group of patients with a shorter duration of disease (P < 0.01). Basal and maximum insulin-stimulated glucose transport was significantly higher in the group with less than 5 years of disease (P < 0.01). No correlation was found between BMI and insulin action. Conclusion: Female type 1 diabetic patients have normal insulin action. There is a high glucose uptake in the early phase of the disease, although a longer duration of disease appears to be a contributing factor to a decrease in insulin action in these patients, and involving both receptor and postreceptor mechanisms.
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Affiliation(s)
- Francisco Arrieta-Blanco
- Unit of Clinical Nutrition and Dietetics, Department of Endocrinology and Nutrition, Hospital Ramóny, Cajal, Madrid, Spain, Irycis, Ciberobn
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29
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Pathogenesis of insulin resistance in skeletal muscle. J Biomed Biotechnol 2010; 2010:476279. [PMID: 20445742 PMCID: PMC2860140 DOI: 10.1155/2010/476279] [Citation(s) in RCA: 378] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2009] [Accepted: 01/20/2010] [Indexed: 12/16/2022] Open
Abstract
Insulin resistance in skeletal muscle is manifested by decreased insulin-stimulated glucose uptake and results from impaired insulin signaling and multiple post-receptor intracellular defects including impaired glucose transport, glucose phosphorylation, and reduced glucose oxidation and glycogen synthesis. Insulin resistance is a core defect in type 2 diabetes, it is also associated with obesity and the metabolic syndrome. Dysregulation of fatty acid metabolism plays a pivotal role in the pathogenesis of insulin resistance in skeletal muscle. Recent studies have reported a mitochondrial defect in oxidative phosphorylation in skeletal muscle in variety of insulin resistant states. In this review, we summarize the cellular and molecular defects that contribute to the development of insulin resistance in skeletal muscle.
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Pereira MJ, Carvalho E, Eriksson JW, Crans DC, Aureliano M. Effects of decavanadate and insulin enhancing vanadium compounds on glucose uptake in isolated rat adipocytes. J Inorg Biochem 2009; 103:1687-92. [PMID: 19850351 DOI: 10.1016/j.jinorgbio.2009.09.015] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2009] [Revised: 09/17/2009] [Accepted: 09/21/2009] [Indexed: 02/07/2023]
Abstract
The effects of different vanadium compounds namely pyridine-2,6-dicarboxylatedioxovanadium(V) (V5-dipic), bis(maltolato) oxovanadium(IV) (BMOV) and amavadine, and oligovanadates namely metavanadate and decavanadate were analysed on basal and insulin stimulated glucose uptake in rat adipocytes. Decavanadate (50 microM), manifest a higher increases (6-fold) on glucose uptake compared with basal, followed by BMOV (1 mM) and metavanadate (1 mM) solutions (3-fold) whereas V5 dipic and amavadine had no effect. Decavanadate (100 microM) also shows the highest insulin like activity when compared with the others compounds studied. In the presence of insulin (10 nM), only decavanadate increases (50%) the glucose uptake when compared with insulin stimulated glucose uptake whereas BMOV and metavanadate, had no effect and V5 dipic and amavadine prevent the stimulation to about half of the basal value. Decavanadate is also able to reduce or eradicate the suppressor effect caused by dexamethasone on glucose uptake at the level of the adipocytes. Altogether, vanadium compounds and oligovanadates with several structures and coordination spheres reveal different effects on glucose uptake in rat primary adipocytes.
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Affiliation(s)
- Maria João Pereira
- CCMAR and FCT, University of Algarve, Campus das Gambelas, 8005-139 Faro, Portugal
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31
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Si Y, Shi H, Lee K. Impact of perturbed pyruvate metabolism on adipocyte triglyceride accumulation. Metab Eng 2009; 11:382-90. [PMID: 19683593 DOI: 10.1016/j.ymben.2009.08.001] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2009] [Revised: 06/15/2009] [Accepted: 08/10/2009] [Indexed: 01/08/2023]
Abstract
This study aimed to test the hypothesis that adipocyte TG accumulation could be altered by specifically perturbing pyruvate metabolism. We treated cultured 3T3-L1 adipocytes with chemical inhibitors of lactate dehydrogenase (LDH) and pyruvate carboxylase (PC), and characterized their global effects on intermediary metabolism using metabolic flux and isotopomer analysis. Inhibiting the enzymes over several days did not alter the adipocyte differentiation program as assessed by the expression levels of peroxisome proliferator-activated receptor-gamma and glycerol-3-phosphate dehydrogenase. The main metabolic effects were to up-regulate intracellular lipolysis and decrease TG accumulation. Inhibiting PC also up-regulated glycolysis. Flux estimates indicated that the reduction in TG was due to decreased de novo fatty acid synthesis. Exogenous addition of free fatty acids dose-dependently increased the cellular TG level in the inhibitor-treated adipocytes, but not in untreated control cells. The results of this study support our hypothesis regarding the critical role of pyruvate reactions in TG synthesis.
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Affiliation(s)
- Yaguang Si
- Department of Biology, Tufts University, Medford, MA 02155, USA
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Alterations of insulin signaling in type 2 diabetes: A review of the current evidence from humans. Biochim Biophys Acta Mol Basis Dis 2009; 1792:83-92. [DOI: 10.1016/j.bbadis.2008.10.019] [Citation(s) in RCA: 153] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2008] [Revised: 10/21/2008] [Accepted: 10/21/2008] [Indexed: 01/03/2023]
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Calle C, Maestro B, García-Arencibia M. Genomic actions of 1,25-dihydroxyvitamin D3 on insulin receptor gene expression, insulin receptor number and insulin activity in the kidney, liver and adipose tissue of streptozotocin-induced diabetic rats. BMC Mol Biol 2008; 9:65. [PMID: 18638371 PMCID: PMC2533347 DOI: 10.1186/1471-2199-9-65] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2007] [Accepted: 07/18/2008] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND this study set out to examine the effects of the treatment with 1,25-dihydroxyvitamin D3 (1,25D3) [150 IU/Kg (3.75 microg/Kg) one a day, for 15 days] to non-diabetic rats and in rats rendered diabetic by a single injection of streptozotocin [65 mg/kg]. RESULTS treatment with 1,25D3 to non-diabetic rats did not affect the biochemical parameters measured in the plasma and urine of these animals. Likewise, insulin receptor expression in the kidney, liver, or adipose tissue and insulin-stimulated glucose transport in adipocytes from these animals were not affected either. Treatment with 1,25D3 to streptozotocin-induced diabetic rats did not correct the hyperglycemia, hypoinsulinemia, glycosuria or ketonemia induced by the diabetes, although it partially reversed the over-expression of the insulin receptor gene in the liver and adipose tissue, without altering the normal expression of this gene in the kidney. These effects were accompanied by a normalization of the number of insulin receptors without altering receptor affinity but improving the insulin response to glucose transport in adipocytes from these diabetic animals. Moreover, a computer search in the rat insulin receptor promoter revealed the existence of two candidate vitamin D response element (VDRE) sequences located at -256/-219 bp and -653/-620 bp, the first overlapped by three and the second by four AP-2-like sites. CONCLUSION these genomic actions of 1,25D3 could represent beneficial effects associated with the amelioration of diabetes via mechanisms that possibly involve direct transcriptional activation of the rat insulin receptor gene. The candidate VDREs identified may respond to 1,25D3 via activation of the vitamin D receptor, although this remains to be investigated.
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Affiliation(s)
- Consuelo Calle
- Department of Biochemistry and Molecular Biology, School of Medicine, Complutense University, 28040-Madrid, Spain.
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Burén J, Lai YC, Lundgren M, Eriksson JW, Jensen J. Insulin action and signalling in fat and muscle from dexamethasone-treated rats. Arch Biochem Biophys 2008; 474:91-101. [PMID: 18328801 DOI: 10.1016/j.abb.2008.02.034] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2008] [Revised: 02/18/2008] [Accepted: 02/21/2008] [Indexed: 10/22/2022]
Abstract
Glucocorticoids initiate whole body insulin resistance and the aim of the present study was to investigate effects of dexamethasone on protein expression and insulin signalling in muscle and fat tissue. Rats were injected with dexamethasone (1mg/kg/day, i.p.) or placebo for 11 days before insulin sensitivity was evaluated in vitro in soleus and epitrochlearis muscles and in isolated epididymal adipocytes. Dexamethasone treatment reduced insulin-stimulated glucose uptake and glycogen synthesis by 30-70% in epitrochlearis and soleus, and insulin-stimulated glucose uptake by approximately 40% in adipocytes. 8-bromo-cAMP-stimulated lipolysis was approximately 2-fold higher in adipocytes from dexamethasone-treated rats and insulin was less effective to inhibit cAMP-stimulated lipolysis. A main finding was that dexamethasone decreased expression of PKB and insulin-stimulated Ser(473) and Thr(308) phosphorylation in both muscles and adipocytes. Expression of GSK-3 was not influenced by dexamethasone treatment in muscles or adipocytes and insulin-stimulated GSK-3beta Ser(9) phosphorylation was reduced in muscles only. A novel finding was that glycogen synthase (GS) Ser(7) phosphorylation was higher in both muscles from dexamethasone-treated rats. GS expression decreased (by 50%) in adipocytes only. Basal and insulin-stimulated GS Ser(641) and GS Ser(645,649,653,657) phosphorylation was elevated in epitrochlearis and soleus muscles and GS fractional activity was reduced correspondingly. In conclusion, dexamethasone treatment (1) decreases PKB expression and insulin-stimulated phosphorylation in both muscles and adipocytes, and (2) increases GS phosphorylation (reduces GS fractional activity) in muscles and decreases GS expression in adipocytes. We suggest PKB and GS as major targets for dexamethasone-induced insulin resistance.
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Affiliation(s)
- J Burén
- Department of Public Health and Clinical Medicine, Umeå University Hospital, Umeå, Sweden
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Hoffstedt J, Förster D, Löfgren P. Impaired subcutaneous adipocyte lipogenesis is associated with systemic insulin resistance and increased apolipoprotein B/AI ratio in men and women. J Intern Med 2007; 262:131-9. [PMID: 17598821 DOI: 10.1111/j.1365-2796.2007.01811.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
OBJECTIVES To study the association between subcutaneous fat cell lipogenesis and components of the metabolic syndrome (systemic insulin resistance, dyslipidaemia and hypertension). DESIGN AND SETTING A university hospital-based cross-sectional study of 383 subjects (303 women and 80 men) with a wide range of BMI (18-53 kg m(-2)). RESULTS Strong negative correlations between in vitro fat cell lipogenesis (basal and after maximal insulin stimulation) and HOMA-IR were present in both genders (r = -0.42 to -0.56, P < 0.0001 and r = -0.37 to -0.44, P < 0.001, for women and men respectively). Insulin sensitivity measured using the insulin tolerance test (K(ITT)) was also correlated with adipocyte lipogenesis (r = 0.47-0.57, P < 0.0001, women, r = 0.52-0.70, P < 0.001, men). Plasma apolipoprotein B/AI-ratio negatively associated with fat cell lipogenesis in women (r = -0.41 to-0.51, P < 0.0001,) and men (r = -0.49 to -0.55, P < 0.0001). The negative relationship of fat cell lipogenesis with blood pressure was significant in women (r = -0.27 to -0.28, P < 0.0002,) but not in men (P = 0.08-0.09). All correlations remained significant after adjusting for differences in fat cell volume, body mass index, waist- to hip- ratio or age (P < 0.01). CONCLUSIONS Subcutaneous adipocyte lipogenesis is negatively associated with systemic insulin resistance, plasma apolipoprotein B/AI-ratio and blood pressure supporting the view that impaired fat cell function per se may contribute to the development of the metabolic syndrome.
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Affiliation(s)
- J Hoffstedt
- Department of Medicine, Karolinska University Hospital Huddinge, Karolinska Institutet, Stockholm, Sweden
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36
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Protein restriction during early development enhances insulin responsiveness but selectively impairs sensitivity to insulin at low concentrations in white adipose tissue during a later pregnancy. Br J Nutr 2007. [DOI: 10.1017/s0007114599000847] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Poor early nutrition may elicit long-term detrimental effects on adult health, including susceptibility to non-insulin-dependent diabetes mellitus. We investigated the impact of moderate maternal protein restriction during pregnancy and lactation on the action of insulin on adipocyte glucose uptake in female offspring during their own pregnancies. Offspring of dams provided with diets containing either 200 g protein/kg or 80 g protein/kg during pregnancy and lactation (termed C and EPR groups respectively) were weaned on to 200 g protein/kg diet at 24 d of age. At 9–12 weeks of age both groups were time-mated and studied at day 19 of gestation. Rates of glucose utilization (assessed using the 2-deoxy-d-- [1-3H- ]glucose technique) measured in five distinct adipose tissue depots (parametrial (PM), mesenteric (MES), perirenal (PR), subcutaneous (SC), interscapular (IS)) in vivo in the post-absorptive state were consistently lower in early-protein-restricted (EPR) pregnant rats compared with control (C) pregnant rats. In C pregnant rats, insulin significantly increased glucose utilization only in the IS depot. In contrast, significantly increased glucose utilization rates in response to hyperinsulinaemia were evident in all five adipose-tissue depots of the EPR pregnant group. Consequently, glucose utilization rates in PM and SC depots during hyperinsulinaemia were significantly higher in EPR pregnant rats compared with C pregnant rats. Adipocytes were isolated from PM and MES depots to determine whether altered responses to insulin in vivo were retained in vitro. Rates of insulin-stimulated glucose uptake at sub-maximal (15 μU/ml) and maximal (15 mU/ml) insulin concentrations were significantly higher in both MES and PM adipocytes from EPR pregnant rats, but the sensitivity of glucose uptake to insulin at low concentrations was blunted compared with adipocytes from C pregnant rats. The results demonstrate that early protein restriction enhances the capacity for adipocyte glucose uptake at high insulin concentrations, but dampens the response to insulin at low physiological concentrations.
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37
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Lundgren M, Svensson M, Lindmark S, Renström F, Ruge T, Eriksson JW. Fat cell enlargement is an independent marker of insulin resistance and 'hyperleptinaemia'. Diabetologia 2007; 50:625-33. [PMID: 17216279 DOI: 10.1007/s00125-006-0572-1] [Citation(s) in RCA: 200] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/19/2006] [Accepted: 11/16/2006] [Indexed: 01/10/2023]
Abstract
AIMS/HYPOTHESIS The aim of this study was to explore whether fat cell size in human subcutaneous and omental adipose tissue is independently related to insulin action and adipokine levels. MATERIALS AND METHODS Fat cells were prepared from abdominal subcutaneous biopsies obtained from 49 type 2 diabetic and 83 non-diabetic subjects and from omental biopsies obtained from 37 non-diabetic subjects. Cell size and insulin action on glucose uptake capacity in vitro were assessed in isolated fat cells. Insulin sensitivity in vivo was assessed with euglycaemic-hyperinsulinaemic clamps. Fasting blood samples were collected and adipokines and NEFA were measured. RESULTS Negative correlations were found between subcutaneous fat cell size and insulin sensitivity assessed as M-value during clamp and as insulin action on glucose uptake in fat cells in vitro. This was seen in non-diabetic subjects after including age, sex and BMI in the analyses. No such relationship was found in type 2 diabetic subjects. In both groups, subcutaneous fat cell size correlated positively and independently with plasma levels of leptin but not to any of the other assessed adipokines. In non-diabetic subjects, omental fat cell size was independently and negatively correlated with insulin action in subcutaneous, but not omental, fat cells in vitro. CONCLUSIONS/INTERPRETATION Fat cell enlargement is associated with insulin resistance in non-diabetic individuals independently of BMI. This was not seen in type 2 diabetic subjects, suggesting that after development of type 2 diabetes other factors, not related to fat cell size, become more important for the modulation of insulin resistance.
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Affiliation(s)
- M Lundgren
- Department of Medicine, UKBF, Umeå University Hospital, Umeå, Sweden.
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38
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Renström F, Burén J, Svensson M, Eriksson JW. Insulin resistance induced by high glucose and high insulin precedes insulin receptor substrate 1 protein depletion in human adipocytes. Metabolism 2007; 56:190-8. [PMID: 17224332 DOI: 10.1016/j.metabol.2006.09.012] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/28/2006] [Accepted: 09/08/2006] [Indexed: 11/25/2022]
Abstract
The aim of this study was to investigate whether high glucose and/or high insulin produces cellular insulin resistance in human adipocytes and, if so, to evaluate the time course and content of key proteins in the insulin signaling pathway. Subcutaneous fat biopsies were taken from 27 nondiabetic subjects. Insulin action in vitro was studied by measurement of glucose uptake after incubation at a physiologic glucose level (6 mmol/L) for 24 hours or with the last 2, 6, or 24 hours at a high glucose level (20 mmol/L) with or without high insulin (10(4)microU/mL). High glucose alone for 24 hours produced a small but significant impairment (by approximately 20%, P < .05) of insulin's effect to stimulate glucose transport, whereas nonstimulated glucose uptake was left intact. In contrast, the combination of high glucose and high insulin for 6 hours or more reduced basal glucose uptake by approximately 40% (P < .05). In addition, insulin-stimulated glucose uptake capacity was reduced by approximately 40% already after 2 hours (P < .05) and reached a maximal decline (by approximately 50%, P < .05) after a 6-hour culture in high glucose and high insulin. Treatment with high glucose and high insulin in combination for at least 6 hours reduced cellular insulin receptor substrate (IRS)-1, but not IRS-2, protein content by approximately 45% or more (P < .05). Moreover, after 24 hours, the ability of insulin to activate protein kinase B (ie, the phosphorylated protein kinase B [pPKB]-protein kinase B ratio) was decreased by approximately 50% (P < .05). No significant effects were seen on insulin signaling proteins or glucose transporter 4 after a long-term high-glucose culture. Culture with high insulin alone (and low glucose, 6 mmol/L) decreased basal and insulin-stimulated glucose uptake in conformity with the high-glucose/high-insulin setting. However, IRS-1 protein content remained unchanged. We conclude that, in adipocytes from healthy humans, high insulin alone for 2 hours or more decrease glucose uptake capacity. Likewise, high glucose and high insulin in combination for 2 hours or more decrease glucose uptake to the same extent as when cells were cultured with high insulin alone but, in addition, with a diminishment in IRS-1 protein lagging behind. Thus, IRS-1 depletion appears to be a secondary phenomenon in this model of insulin resistance. High glucose alone induces only a minor insulin resistance in human fat cells.
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Affiliation(s)
- Frida Renström
- Department of Public Health and Clinical Medicine, Medicine, Umeå University Hospital, S-901 85 Umeå, Sweden
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39
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Shankar SS, Considine RV, Gorski JC, Steinberg HO. Insulin sensitivity is preserved despite disrupted endothelial function. Am J Physiol Endocrinol Metab 2006; 291:E691-6. [PMID: 16705064 DOI: 10.1152/ajpendo.00006.2006] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
It is well established that endothelial dysfunction and insulin resistance go hand in hand. However, it is unclear whether endothelial dysfunction per se is sufficient to impair insulin-mediated glucose uptake. We have previously reported that 4 wk of administration of the human immunodeficiency virus (HIV)-1 protease inhibitor indinavir to HIV-negative subjects induces endothelial dysfunction. Hence, we hypothesized that indinavir-induced endothelial dysfunction was associated with impaired insulin-mediated glucose disposal. We measured insulin-mediated glucose disposal at the level of the whole body, skeletal muscle, and vasculature by performing hyperinsulinemic euglycemic clamp, and vascular function studies, in a separate group of HIV-negative healthy nonobese subjects (n = 13) before and after 4 wk of daily oral indinavir. Four weeks of indinavir resulted in a 113 +/- 29% (P < 0.01) reduction of endothelium-dependent vasodilation, consistent with our earlier findings. In addition, there was a significant impairment of insulin-mediated vasodilation (101 +/- 14% before indinavir vs. 35 +/- 15% after indinavir; P < 0.05). However, there was no significant change in insulin-mediated glucose disposal at the level of the whole body (8.9 +/- 0.5 before indinavir vs. 8.5 +/- 0.6 mgxkg(-1)xmin(-1) after indinavir; P = 0.4), or skeletal muscle. Furthermore, in a separate group of four HIV-negative healthy nonobese subjects, we found that 4 wk of indinavir has no sustained effect on insulin-stimulated glucose uptake in adipose tissue. Thus our findings indicate that 1) endothelial dysfunction alone is insufficient to impair insulin-mediated glucose disposal, and 2) indinavir-induced endothelial dysfunction is likely due to a direct effect of the drug on the endothelium and is not coupled to the induction of insulin resistance.
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Affiliation(s)
- Sudha S Shankar
- Division of Endocrinology, Department of Medicine, Indiana University School of Medicine, 975 W. Walnut, IB 424 D, Indianapolis, IN 46202, USA
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40
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Yang RZ, Lee MJ, Hu H, Pray J, Wu HB, Hansen BC, Shuldiner AR, Fried SK, McLenithan JC, Gong DW. Identification of omentin as a novel depot-specific adipokine in human adipose tissue: possible role in modulating insulin action. Am J Physiol Endocrinol Metab 2006; 290:E1253-61. [PMID: 16531507 DOI: 10.1152/ajpendo.00572.2004] [Citation(s) in RCA: 594] [Impact Index Per Article: 33.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Central (visceral) obesity is more closely associated with insulin resistance, type 2 diabetes, and cardiovascular disease than is peripheral [subcutaneous (sc)] obesity, but the underlying mechanism for this pathophysiological difference is largely unknown. To understand the molecular basis of this difference, we sequenced 10,437 expressed sequence tags (ESTs) from a human omental fat cDNA library and discovered a novel visceral fat depot-specific secretory protein, which we have named omentin. Omentin ESTs were more abundant than many known adipose genes, such as perilipin, adiponectin, and leptin in the cDNA library. Protein sequence analysis indicated that omentin mRNA encodes a peptide of 313 amino acids, containing a secretory signal sequence and a fibrinogen-related domain. Northern analysis demonstrated that omentin mRNA was predominantly expressed in visceral adipose tissue and was barely detectable in sc fat depots in humans and rhesus monkeys. Quantative real-time PCR showed that omentin mRNA was expressed in stromal vascular cells, but not fat cells, isolated from omental adipose tissue, with >150-fold less in sc cell fractions. Accordingly, omentin protein was secreted into the culture medium of omental, but not sc, fat explants. Omentin was detectable in human serum by Western blot analysis. Addition of recombinant omentin in vitro did not affect basal but enhanced insulin-stimulated glucose uptake in both sc (47%, n = 9, P = 0.003) and omental (approximately 30%, n = 3, P < 0.05) human adipocytes. Omentin increased Akt phosphorylation in the absence and presence of insulin. In conclusion, omentin is a new adipokine that is expressed in omental adipose tissue in humans and may regulate insulin action.
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Affiliation(s)
- Rong-Ze Yang
- Division of Endocrinology, Diabetes, and Nutrition, University of Maryland School of Medicine, Baltimore, MD 21201, USA
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41
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Abstract
The traditional view of adipose tissue as a passive energy reservoir has changed. Adipose tissue is a complex, highly active metabolic and endocrine organ. With obesity as an increasingly important public health threat, a major development in the understanding of adipose tissue biology has come with observations in different biological spheres including whole-body physiology and application of transgenic animal models. Scientific progress has been made with the identification of several genes in spontaneous monogenic animal models of obesity, and in understanding the molecular mechanisms underlying phenotypes of altered body weight, adiposity and fat distribution by creating transgenic and knockout animal models. Mouse phenotypes resulting from inactivation or overexpression of molecules responsible for the regulation of adipose tissue metabolism have led to novel concepts in the understanding of adipocyte biology and development of obesity. This review presents an overview of transgenic animal models for the study of adipose tissue biology.
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Affiliation(s)
- Matthias Blüher
- Department of Internal Medicine II, University of Köln, Germany.
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42
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Renström F, Burén J, Eriksson JW. Insulin receptor substrates-1 and -2 are both depleted but via different mechanisms after down-regulation of glucose transport in rat adipocytes. Endocrinology 2005; 146:3044-51. [PMID: 15845625 DOI: 10.1210/en.2004-1675] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Alterations in muscle and adipose tissue insulin receptor substrate (IRS)-1 and IRS-2 are associated with, and commonly believed to contribute to, development of insulin resistance. In this study, we investigated the mechanisms behind previously observed reductions in IRS levels due to high concentrations of glucose and insulin and their significance in the impairment of glucose uptake capacity in primary rat adipocytes. Semiquantitative RT-PCR analysis showed that insulin (10(4) microU/ml) alone or in combination with glucose (15 mm) markedly suppressed IRS-2 gene expression, whereas IRS-1 mRNA was unaffected by the culture conditions. The negative effect of a high glucose/high insulin setting on IRS-1 protein level was still exerted when protein synthesis was inhibited with cycloheximide. Impairment of glucose uptake capacity after treatment with high glucose and insulin was most pronounced after 3 h, whereas IRS-1 and IRS-2 protein levels were unaffected up to 6 h but were reduced after 16 h. Moreover, impaired glucose uptake capacity could only partially be reversed by subsequent incubation at physiological conditions. These novel results suggest that: 1) in a high glucose/high insulin setting depletion of IRS-1 and IRS-2 protein, respectively, occurs via different mechanisms, and IRS-2 gene expression is suppressed, whereas IRS-1 depletion is due to posttranslational mechanisms; 2) IRS-1 and IRS-2 protein depletion is a secondary event in the development of insulin resistance in this model of hyperglycemia/hyperinsulinemia; and 3) depletion of cellular IRS in adipose tissue may be a consequence rather than a cause of insulin resistance and hyperinsulinemia in type 2 diabetes.
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Affiliation(s)
- Frida Renström
- Department of Medicine, Umeå University Hospital, SE-901 85 Umeå, Sweden
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43
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Watanabe T, Iizuka Y, Liang YQ, Inomata H, Gotoda T, Yanai K, Isobe M, Kato N. Evaluation of insulin resistance linkage to rat chromosome 4 in SHR of a Japanese colony. Biochem Biophys Res Commun 2005; 329:879-87. [PMID: 15752738 DOI: 10.1016/j.bbrc.2005.02.053] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2005] [Indexed: 10/25/2022]
Abstract
The spontaneously hypertensive rat (SHR) is a model of human insulin resistance syndrome. Quantitative trait loci for cellular defects in glucose and fatty acid metabolism have been mapped to an overlapping region of rat chromosome (RNO) RNO4 in SHR of the National Institute of Health colony, where a deletion in the Cd36 gene has been implicated as the causative mutation of insulin resistance. The present study has examined the potential presence of RNO4 linkage to a series of metabolic phenotypes in F(2) progeny derived from SHR of a Japanese colony (SHR/Izm) without the Cd36 mutation. Our data demonstrate that 'major' insulin resistance gene(s) are unlikely to exist on RNO4 in SHR/Izm and in vitro phenotypes measured in isolated adipocytes do not cosegregate in the F(2) population studied. Thus, it seems to be difficult to explain the underlying genetic mechanisms of insulin resistance by a single major gene on RNO4.
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Affiliation(s)
- Takehiro Watanabe
- Department of Gene Diagnostics and Therapeutics, Research Institute, International Medical Center of Japan, Japan
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44
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García-Arencibia M, Molero S, Dávila N, Carranza MC, Calle C. 17β-Estradiol transcriptionally represses human insulin receptor gene expression causing cellular insulin resistance. Leuk Res 2005; 29:79-87. [PMID: 15541479 DOI: 10.1016/j.leukres.2004.05.012] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2004] [Accepted: 05/10/2004] [Indexed: 01/09/2023]
Abstract
In this study, we demonstrate that 17beta-estradiol (E(2)) inhibits human insulin receptor (IR) gene expression in a dose- and time-dependent manner in U-937 human promonocytic cells. Using cells transfected with the -1819 to -271 bp fragment of the human IR promoter (wild type promoter) and treated with E(2), we show that this repression is regulated at the transcriptional level. The steroid was also found to diminish the insulin responsiveness of the cells in terms of cell survival, DNA synthesis, glucose transport, and glucose oxidation, this last effect possibly involving reduced phosphatidylinositol 3-kinase (PI3-kinase) activity. These data provide new information on the molecular mechanisms of estrogen-inducing insulin resistance in human cells.
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Affiliation(s)
- Moisés García-Arencibia
- Department of Biochemistry and Molecular Biology, School of Medicine, Complutense University, 28040 Madrid, Spain
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45
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Abstract
This article provides an overview of the pathogenesis of type 2 diabetes mellitus. Discussion begins by describing normal glucose homeostasis and ingestion of a typical meal and then discusses glucose homeostasis in diabetes. Topics covered include insulin secretion in type 2 diabetes mellitus and insulin resistance, the site of insulin resistance, the interaction between insulin sensitivity and secretion, the role of adipocytes in the pathogenesis of type 2 diabetes, cellular mechanisms of insulin resistance including glucose transport and phosphorylation, glycogen and synthesis,glucose and oxidation, glycolysis, and insulin signaling.
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Affiliation(s)
- Ralph A DeFronzo
- Diabetes Division, University of Texas Health Science Center, 7703 Floyd Curl Drive, San Antonio, TX 78229, USA
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46
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Lemhadri A, Zeggwagh NA, Maghrani M, Jouad H, Eddouks M. Anti-hyperglycaemic activity of the aqueous extract of Origanum vulgare growing wild in Tafilalet region. JOURNAL OF ETHNOPHARMACOLOGY 2004; 92:251-256. [PMID: 15138008 DOI: 10.1016/j.jep.2004.02.026] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2003] [Revised: 01/23/2004] [Accepted: 02/23/2004] [Indexed: 05/24/2023]
Abstract
The effect of an aqueous extract of Origanum vulgare (OV) leaves on blood glucose levels was investigated in normal and streptozotocin (STZ) diabetic rats. In normal rats, the blood glucose levels were slightly decreased 6 h after a single oral administration (P<0.05) as well as 15 days after once daily repeated oral administration of aqueous OV extract (P<0.05) (20 mg/kg). After a single dose or 15 daily doses, oral administration of the aqueous extract (20 mg/kg) produced a significant decrease on blood glucose levels in STZ diabetic rats (P<0.001). In STZ rats, the blood glucose levels were normalised from the fourth day after daily repeated oral administration of aqueous OV extract (20 mg/kg) (P<0.001). However, this effect was less pronounced 2 weeks after daily repeated oral administration of OV extract. In addition, no changes were observed in basal plasma insulin concentrations after treatment in either normal or STZ diabetic rats indicating that the aqueous OV extract acted without changing insulin secretion. We conclude that an aqueous extract of OV exhibits an anti-hyperglycaemic activity in STZ rats without affecting basal plasma insulin concentrations.
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Affiliation(s)
- A Lemhadri
- Laboratory of Endocrinian Physiology, F.S.T.E. Boutalamine and Pharmacology, UFR PNPE, BP 21, Errachidia 52000, Morocco
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47
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Lundgren M, Burén J, Ruge T, Myrnäs T, Eriksson JW. Glucocorticoids down-regulate glucose uptake capacity and insulin-signaling proteins in omental but not subcutaneous human adipocytes. J Clin Endocrinol Metab 2004; 89:2989-97. [PMID: 15181089 DOI: 10.1210/jc.2003-031157] [Citation(s) in RCA: 120] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Visceral adiposity is associated with insulin resistance and type 2 diabetes. This study explores the metabolic differences between s.c. and visceral fat depots with respect to effects in vitro of glucocorticoids and insulin on glucose uptake. Adipocytes from human s.c. and omental fat depots were obtained during abdominal surgery in 18 nondiabetic subjects. Cells were isolated, and metabolic studies were performed directly after the biopsies and after a culture period of 24 h with or without dexamethasone. After washing, basal and insulin-stimulated [14C]glucose uptake as well as cellular content of insulin signaling proteins and glucose transporter 4 (GLUT4) was assessed. Omental adipocytes had an approximately 2-fold higher rate of insulin-stimulated glucose uptake compared with s.c. adipocytes (P < 0.01). Dexamethasone treatment markedly inhibited (by approximately 50%; P < 0.05) both basal and insulin-stimulated glucose uptake in omental adipocytes but had no consistent effect in s.c. adipocytes. The cellular content of insulin receptor substrate 1 and phosphatidylinositol 3-kinase did not differ significantly between the depots, but the expression of protein kinase B (PKB) tended to be increased in omental compared with s.c. adipocytes (P = 0.09). Dexamethasone treatment decreased the expression of insulin receptor substrate 1 (by approximately 40%; P < 0.05) and PKB (by approximately 20%; P < 0.05) in omental but not in s.c. adipocytes. In contrast, dexamethasone pretreatment had no effect on insulin-stimulated Ser473 phosphorylation of PKB. GLUT4 expression was approximately 4-fold higher in omental than s.c. adipocytes (P < 0.05). Dexamethasone treatment did not alter the expression of GLUT4. In conclusion, human omental adipocytes display approximately 2-fold higher glucose uptake rate compared with s.c. adipocytes, and this could be explained by a higher GLUT4 expression. A marked suppression is exerted by glucocorticoids on glucose uptake and on the expression of insulin signaling proteins in omental but not in s.c. adipocytes. These findings may be of relevance for the interaction between endogenous glucocorticoids and visceral fat in the development of insulin resistance.
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Affiliation(s)
- M Lundgren
- Department of Medicine, Umeå University Hospital, Umeå SE-901 85, Sweden
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48
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Maghrani M, Zeggwagh NA, Lemhadri A, El Amraoui M, Michel JB, Eddouks M. Study of the hypoglycaemic activity of Fraxinus excelsior and Silybum marianum in an animal model of type 1 diabetes mellitus. JOURNAL OF ETHNOPHARMACOLOGY 2004; 91:309-16. [PMID: 15120454 DOI: 10.1016/j.jep.2004.01.008] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2003] [Revised: 01/04/2004] [Accepted: 01/04/2004] [Indexed: 05/24/2023]
Abstract
The hypoglycaemic effect of the aqueous extracts of Fraxinus excelsior (FE) seed and Silybum marianum (SM) aerial part was investigated in normal and streptozotocin (STZ) diabetic rats. After a single dose or 15 daily doses, oral administration of the aqueous extracts (20 mg/kg) produced a significant decrease of blood glucose levels in both normal and STZ diabetic rats (P < 0.001). From the first week, the body weight was increased in normal rats (P < 0.05) and decreased in STZ rats (P < 0.01) after FE administration. In addition, no changes were observed in basal plasma insulin concentrations after both FE and SM treatments in either normal and STZ diabetic rats indicating that these plants exert their pharmacological activity without affecting insulin secretion. We conclude that the aqueous extracts of FE and SM exhibit potent hypoglycaemic and anti-hyperglycaemic activities in normal and STZ rats, respectively, without affecting basal plasma insulin concentrations.
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Affiliation(s)
- M Maghrani
- UFR PNPE, BP 21, Errachidia 52000, Morocco
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49
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Bays H, Mandarino L, DeFronzo RA. Role of the adipocyte, free fatty acids, and ectopic fat in pathogenesis of type 2 diabetes mellitus: peroxisomal proliferator-activated receptor agonists provide a rational therapeutic approach. J Clin Endocrinol Metab 2004; 89:463-78. [PMID: 14764748 DOI: 10.1210/jc.2003-030723] [Citation(s) in RCA: 435] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Harold Bays
- Diabetes Division, University of Texas Health Science Center, San Antonio, Texas 78229, USA
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50
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Maghrani M, Lemhadri A, Zeggwagh NA, El Amraoui M, Haloui M, Jouad H, Eddouks M. Effects of an aqueous extract of Triticum repens on lipid metabolism in normal and recent-onset diabetic rats. JOURNAL OF ETHNOPHARMACOLOGY 2004; 90:331-337. [PMID: 15013198 DOI: 10.1016/j.jep.2003.10.011] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2003] [Revised: 06/19/2003] [Accepted: 10/09/2003] [Indexed: 05/24/2023]
Abstract
The aim of this study was to demonstrate the effects of single and repeated oral administration of the aqueous rhizomes extract of Triticum repens (TR) (20 mg/kg) on lipid metabolism in normal and streptozotocin-induced diabetic rats. In normal rats, the aqueous extract of TR induced a significant decrease in the plasma triglycerides concentrations 4 days (P<0.05) and 1 week after repeated oral administration (P<0.05). This reduction was abolished 2 weeks after once daily repeated oral administration. A significant decrease of plasma cholesterol levels was observed only 1 week (P<0.05) after repeated oral administration. In diabetic rats, TR treatment caused a significant decrease in plasma triglycerides levels after a single (P<0.01) and repeated (P<0.001) oral administration. A strong decrease in cholesterol level was observed 6 h after a single oral administration of the aqueous extract TR (P<0.001). Four days after repeated oral administration of TR aqueous extract, the plasma cholesterol level was significantly decreased (P<0.05) and still dropped after 2 weeks (P<0.001). On other hand, the repeated oral administration of aqueous TR extract caused a significant decrease in body weight 2 weeks after repeated oral treatment in diabetic rats (P<0.05). We conclude that the aqueous extract of TR exhibits lipid and body weight lowering activities in severe hyperglycaemic rats after repeated oral administration of aqueous TR extract at a dose of 20 mg/kg.
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