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Russell-Guzmán J, Américo-Da Silva L, Cadagan C, Maturana M, Palomero J, Estrada M, Barrientos G, Buvinic S, Hidalgo C, Llanos P. Activation of the ROS/TXNIP/NLRP3 pathway disrupts insulin-dependent glucose uptake in skeletal muscle of insulin-resistant obese mice. Free Radic Biol Med 2024; 222:187-198. [PMID: 38897422 DOI: 10.1016/j.freeradbiomed.2024.06.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/17/2024] [Revised: 05/31/2024] [Accepted: 06/15/2024] [Indexed: 06/21/2024]
Abstract
Oxidative stress and the activation of the nucleotide-binding domain, leucine-rich-containing family, pyrin domain containing 3 (NLRP3) inflammasome have been linked to insulin resistance in skeletal muscle. In immune cells, the exacerbated generation of reactive oxygen species (ROS) activates the NLRP3 inflammasome, by facilitating the interaction between thioredoxin interacting protein (TXNIP) and NLRP3. However, the precise role of ROS/TXNIP-dependent NLRP3 inflammasome activation in skeletal muscle during obesity-induced insulin resistance remains undefined. Here, we induced insulin resistance in C57BL/6J mice by feeding them for 8 weeks with a high-fat diet (HFD) and explored whether the ROS/TXNIP/NLRP3 pathway was involved in the induction of insulin resistance in skeletal muscle. Skeletal muscle fibers from insulin-resistant mice exhibited increased oxidative stress, as evidenced by elevated malondialdehyde levels, and altered peroxiredoxin 2 dimerization. Additionally, these fibers displayed augmented activation of the NLRP3 inflammasome, accompanied by heightened ROS-dependent proximity between TXNIP and NLRP3, which was abolished by the antioxidant N-acetylcysteine (NAC). Inhibition of the NLRP3 inflammasome with MCC950 or suppressing the ROS/TXNIP/NLRP3 pathway with NAC restored insulin-dependent glucose uptake in muscle fibers from insulin-resistant mice. These findings provide insights into the mechanistic link between oxidative stress, NLRP3 inflammasome activation, and obesity-induced insulin resistance in skeletal muscle.
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Affiliation(s)
- Javier Russell-Guzmán
- Institute for Research in Dental Sciences, Faculty of Dentistry, Universidad de Chile, Santiago, 8380544, Chile; Pedagogy in Physical Education, Faculty of Education, Universidad Autónoma de Chile, Santiago, 8910123, Chile
| | - Luan Américo-Da Silva
- Institute for Research in Dental Sciences, Faculty of Dentistry, Universidad de Chile, Santiago, 8380544, Chile
| | - Cynthia Cadagan
- Institute for Research in Dental Sciences, Faculty of Dentistry, Universidad de Chile, Santiago, 8380544, Chile
| | - Martín Maturana
- Institute for Research in Dental Sciences, Faculty of Dentistry, Universidad de Chile, Santiago, 8380544, Chile
| | - Jesús Palomero
- Department of Physiology and Pharmacology, Faculty of Medicine, Campus Miguel de Unamuno, Universidad de Salamanca, Salamanca, 37007, Spain
| | - Manuel Estrada
- Institute of Biomedical Sciences, Facultad de Medicina, Universidad de Chile, Santiago, 8380000, Chile
| | - Genaro Barrientos
- Institute of Biomedical Sciences, Facultad de Medicina, Universidad de Chile, Santiago, 8380000, Chile; Center for Exercise, Metabolism and Cancer, Facultad de Medicina, Universidad de Chile, Santiago, 8380453, Chile
| | - Sonja Buvinic
- Institute for Research in Dental Sciences, Faculty of Dentistry, Universidad de Chile, Santiago, 8380544, Chile; Center for Exercise, Metabolism and Cancer, Facultad de Medicina, Universidad de Chile, Santiago, 8380453, Chile
| | - Cecilia Hidalgo
- Institute of Biomedical Sciences, Facultad de Medicina, Universidad de Chile, Santiago, 8380000, Chile; Center for Exercise, Metabolism and Cancer, Facultad de Medicina, Universidad de Chile, Santiago, 8380453, Chile; Department of Neurosciences and Biomedical Neuroscience Institute, Universidad de Chile, Santiago, 8380453, Chile
| | - Paola Llanos
- Institute for Research in Dental Sciences, Faculty of Dentistry, Universidad de Chile, Santiago, 8380544, Chile; Center for Exercise, Metabolism and Cancer, Facultad de Medicina, Universidad de Chile, Santiago, 8380453, Chile.
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Qiu L, Ren Y, Li J, Li M, Li W, Qin L, Ning C, Zhang J, Gao F. Nonlinear association of triglyceride-glucose index with hyperuricemia in US adults: a cross-sectional study. Lipids Health Dis 2024; 23:145. [PMID: 38760656 PMCID: PMC11100171 DOI: 10.1186/s12944-024-02146-5] [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: 04/01/2024] [Accepted: 05/13/2024] [Indexed: 05/19/2024] Open
Abstract
BACKGROUND Despite abundant evidence on the epidemiological risk factors of metabolic diseases related to hyperuricemia, there is still insufficient evidence regarding the nonlinear relationship between triglyceride-glucose (TyG) index and hyperuricemia. Thus, the purpose of this research is to clarify the nonlinear connection between TyG and hyperuricemia. METHODS From 2011 to 2018, a cross-sectional study was carried out using data from the National Health and Nutrition Examination Survey (NHANES). This study had 8572 participants in all. TyG was computed as Ln [triglycerides (mg/dL) × fasting glucose (mg/dL)/2]. The outcome variable was hyperuricemia. The association between TyG and hyperuricemia was examined using weighted multiple logistic regression, subgroup analysis, generalized additive models, smooth fitting curves, and two-piecewise linear regression models. RESULTS In the regression model adjusting for all confounding variables, the OR (95% CI) for the association between TyG and hyperuricemia was 2.34 (1.70, 3.21). There is a nonlinear and reverse U-shaped association between TyG and hyperuricemia, with a inflection point of 9.69. The OR (95% CI) before the inflection point was 2.64 (2.12, 3.28), and after the inflection point was 0.32 (0.11, 0.98). The interaction in gender, BMI, hypertension, and diabetes analysis was statistically significant. CONCLUSION Additional prospective studies are required to corroborate the current findings, which indicate a strong positive connection between TyG and hyperuricemia among adults in the United States.
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Affiliation(s)
- Linjie Qiu
- Xiyuan Hospital, China Academy of Chinese Medical Sciences, Beijing, China
| | - Yan Ren
- Xiyuan Hospital, China Academy of Chinese Medical Sciences, Beijing, China
| | - Jixin Li
- Xiyuan Hospital, China Academy of Chinese Medical Sciences, Beijing, China
| | - Meijie Li
- Xiyuan Hospital, China Academy of Chinese Medical Sciences, Beijing, China
| | - Wenjie Li
- Shanxi University of Chinese Medicine, Taiyuan, Shanxi, China
| | - Lingli Qin
- Xiyuan Hospital, China Academy of Chinese Medical Sciences, Beijing, China
| | - Chunhui Ning
- Xiyuan Hospital, China Academy of Chinese Medical Sciences, Beijing, China
| | - Jin Zhang
- Xiyuan Hospital, China Academy of Chinese Medical Sciences, Beijing, China.
| | - Feng Gao
- Xiyuan Hospital, China Academy of Chinese Medical Sciences, Beijing, China.
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Goutchtat R, Quenon A, Clarisse M, Delalleau N, Coddeville A, Gobert M, Gmyr V, Kerr-Conte J, Pattou F, Hubert T. Effects of subtotal pancreatectomy and long-term glucose and lipid overload on insulin secretion and glucose homeostasis in minipigs. Endocrinol Diabetes Metab 2023:e425. [PMID: 37144278 DOI: 10.1002/edm2.425] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Revised: 03/30/2023] [Accepted: 04/10/2023] [Indexed: 05/06/2023] Open
Abstract
INTRODUCTION Nowadays, there are no strong diabetic pig models, yet they are required for various types of diabetes research. Using cutting-edge techniques, we attempted to develop a type 2 diabetic minipig model in this study by combining a partial pancreatectomy (Px) with an energetic overload administered either orally or parenterally. METHODS Different groups of minipigs, including Göttingen-like (GL, n = 17) and Ossabaw (O, n = 4), were developed. Prior to and following each intervention, metabolic assessments were conducted. First, the metabolic responses of the Göttingen-like (n = 3) and Ossabaw (n = 4) strains to a 2-month High-Fat, High-Sucrose diet (HFHSD) were compared. Then, other groups of GL minipigs were established: with a single Px (n = 10), a Px combined with a 2-month HFHSD (n = 6), and long-term intraportal glucose and lipid infusions that were either preceded by a Px (n = 4) or not (n = 4). RESULTS After the 2-month HFHSD, there was no discernible change between the GL and O minipigs. The pancreatectomized group in GL minipigs showed a significantly lower Acute Insulin Response (AIR) (18.3 ± 10.0 IU/mL after Px vs. 34.9 ± 13.7 IU/mL before, p < .0005). In both long-term intraportal infusion groups, an increase in the Insulinogenic (IGI) and Hepatic Insulin Resistance Indexes (HIRI) was found with a decrease in the AIR, especially in the pancreatectomized group (IGI: 4.2 ± 1.9 after vs. 1.5 ± 0.8 before, p < .05; HIRI (×10-5 ): 12.6 ± 7.9 after vs. 3.8 ± 4.3 before, p < .05; AIR: 24.4 ± 13.7 µIU/mL after vs. 43.9 ± 14.5 µIU/mL before, p < .005). Regardless of the group, there was no fasting hyperglycemia. CONCLUSIONS In this study, we used pancreatectomy followed by long-term intraportal glucose and lipid infusions to develop an original minipig model with metabolic syndrome and early signs of glucose intolerance. We reaffirm the pig's usefulness as a preclinical model for the metabolic syndrome but without the fasting hyperglycemia that characterizes diabetes mellitus.
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Affiliation(s)
- Rébecca Goutchtat
- Univ. Lille, Inserm, CHU Lille, Institut Pasteur Lille, UFR3S, U1190 - Egid, Lille, France
| | - Audrey Quenon
- Univ. Lille, Inserm, CHU Lille, Institut Pasteur Lille, UFR3S, U1190 - Egid, Lille, France
- Univ. Lille, CHU Lille, UFR3S, Département Hospitalo-Universitaire de Recherche et d'Enseignement (Dhure), Lille, France
| | | | - Nathalie Delalleau
- Univ. Lille, Inserm, CHU Lille, Institut Pasteur Lille, UFR3S, U1190 - Egid, Lille, France
| | - Anaïs Coddeville
- Univ. Lille, Inserm, CHU Lille, Institut Pasteur Lille, UFR3S, U1190 - Egid, Lille, France
| | - Mathilde Gobert
- Univ. Lille, Inserm, CHU Lille, Institut Pasteur Lille, UFR3S, U1190 - Egid, Lille, France
| | - Valéry Gmyr
- Univ. Lille, Inserm, CHU Lille, Institut Pasteur Lille, UFR3S, U1190 - Egid, Lille, France
| | - Julie Kerr-Conte
- Univ. Lille, Inserm, CHU Lille, Institut Pasteur Lille, UFR3S, U1190 - Egid, Lille, France
| | - François Pattou
- Univ. Lille, Inserm, CHU Lille, Institut Pasteur Lille, UFR3S, U1190 - Egid, Lille, France
| | - Thomas Hubert
- Univ. Lille, Inserm, CHU Lille, Institut Pasteur Lille, UFR3S, U1190 - Egid, Lille, France
- Univ. Lille, CHU Lille, UFR3S, Département Hospitalo-Universitaire de Recherche et d'Enseignement (Dhure), Lille, France
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Parker L, Ang T, Morrison DJ, Lee NJ, Levinger I, Keske MA. Prior aerobic exercise mitigates the decrease in serum osteoglycin and lipocalin-2 following high-glucose mixed-nutrient meal ingestion in young men. Am J Physiol Endocrinol Metab 2022; 323:E319-E332. [PMID: 35767699 DOI: 10.1152/ajpendo.00025.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Osteoglycin (OGN) and lipocalin-2 (LCN2) are hormones that can be secreted by bone and have been linked to glucose homeostasis in rodents. However, the endocrine role of these hormones in humans is contradictory and unclear. We examined the effects of exercise and meal ingestion on circulating serum OGN and LCN2 levels in eight healthy males {age: 28 [25, 30] years [median ± interquartile range (IQR)] and body mass index [BMI]: 24.3 [23.6, 25.5] kg/m2}. In a randomized crossover design, participants ingested a high-glucose (1.1 g glucose/kg body wt) mixed-nutrient meal (45% carbohydrate, 20% protein, and 35% fat) on a rest-control day and 3 and 24 h after aerobic cycling exercise (1 h at 70%-75% V̇o2peak). Acute aerobic exercise increased serum LCN2 levels immediately after exercise (∼61%), which remained elevated 3-h postexercise (∼55%). In contrast, serum OGN remained similar to baseline levels throughout the 3-h postexercise recovery period. The ingestion of a high-glucose mixed-nutrient meal led to a decrease in serum OGN at 90-min (approximately -17%) and 120-min postprandial (approximately -44%), and a decrease in LCN2 at 120-min postprandial (approximately -26%). Compared with the control meal, prior exercise elevated serum OGN and LCN2 levels at 120-min postprandial when the meal was ingested 3-h (OGN: ∼74% and LCN2: ∼68%) and 24-h postexercise (OGN: ∼56% and LCN2: ∼16%). Acute exercise increases serum LCN2 and attenuates the postprandial decrease in OGN and LCN2 following high-glucose mixed-nutrient meal ingestion. The potential endocrine role of circulating OGN and LCN2 in humans warrants further investigation.NEW & NOTEWORTHY We provide novel evidence that OGN and LCN2 decrease 120 min after ingesting a high-glucose mixed-nutrient meal in healthy adults. Acute aerobic exercise increases circulating LCN2 for up to 3-h postexercise, whereas circulating OGN remains similar to baseline. Despite differing postexercise responses, postprandial LCN2 and OGN are elevated when the high-glucose meal is ingested 3-h and 24-h postexercise. Findings support that OGN and LCN2 are dynamically linked to energy homeostasis in humans.
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Affiliation(s)
- Lewan Parker
- Institute for Physical Activity and Nutrition (IPAN), School of Exercise and Nutrition Sciences, Deakin University, Geelong, Victoria, Australia
| | - Teddy Ang
- Institute for Physical Activity and Nutrition (IPAN), School of Exercise and Nutrition Sciences, Deakin University, Geelong, Victoria, Australia
| | - Dale J Morrison
- Institute for Physical Activity and Nutrition (IPAN), School of Exercise and Nutrition Sciences, Deakin University, Geelong, Victoria, Australia
- Department of Medicine, University of Melbourne, Melbourne, Victoria, Australia
| | - Nicola J Lee
- Garvan Institute of Medical Research, St. Vincent's Hospital, Darlinghurst, New South Wales, Australia
- St. Vincent's Clinical School, UNSW Sydney, Sydney, New South Wales, Australia
| | - Itamar Levinger
- Institute for Health and Sport (IHES), Victoria University, Footscray, Victoria, Australia
- Australian Institute for Musculoskeletal Science (AIMSS), University of Melbourne and Western Health, St Albans, Victoria, Australia
| | - Michelle A Keske
- Institute for Physical Activity and Nutrition (IPAN), School of Exercise and Nutrition Sciences, Deakin University, Geelong, Victoria, Australia
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Krycer JR, Lor M, Fitzsimmons RL, Hudson JE. A cell culture platform for quantifying metabolic substrate oxidation in bicarbonate-buffered medium. J Biol Chem 2021; 298:101547. [PMID: 34971704 PMCID: PMC8819040 DOI: 10.1016/j.jbc.2021.101547] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Revised: 12/21/2021] [Accepted: 12/23/2021] [Indexed: 12/21/2022] Open
Abstract
Complex diseases such as cancer and diabetes are underpinned by changes in metabolism, specifically by which and how nutrients are catabolized. Substrate utilization can be directly examined by measuring a metabolic endpoint rather than an intermediate (such as tricarboxylic cycle metabolite). For instance, oxidation of specific substrates can be measured in vitro by incubation of live cultures with substrates containing radiolabeled carbon and measuring radiolabeled carbon dioxide. To increase throughput, we previously developed a miniaturized platform to measure substrate oxidation of both adherent and suspension cells using multiwell plates rather than flasks. This enabled multiple conditions to be examined simultaneously, ideal for drug screens and mechanistic studies. However, like many metabolic assays, this was not compatible with bicarbonate-buffered media, which is susceptible to alkalinization upon exposure to gas containing little carbon dioxide such as air. While other buffers such as HEPES can overcome this problem, bicarbonate has additional biological roles as a metabolic substrate and in modulating hormone signaling. Here, we create a bicarbonate-buffered well-plate platform to measure substrate oxidation. This was achieved by introducing a sealed environment within each well that was equilibrated with carbon dioxide, enabling bicarbonate buffering. As proof of principle, we assessed metabolic flux in cultured adipocytes, demonstrating that bicarbonate-buffered medium increased lipogenesis, glucose oxidation, and sensitivity to insulin in comparison to HEPES-buffered medium. This convenient and high-throughput method facilitates the study and screening of metabolic activity under more physiological conditions to aid biomedical research.
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Affiliation(s)
- James R Krycer
- QIMR Berghofer Medical Research Institute; School of Biomedical Sciences, Faculty of Health, Queensland University of Technology
| | - Mary Lor
- QIMR Berghofer Medical Research Institute
| | | | - James E Hudson
- QIMR Berghofer Medical Research Institute; School of Biomedical Sciences, Faculty of Health, Queensland University of Technology; School of Biomedical Sciences, Faculty of Medicine, The University of Queensland.
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Parker L, Morrison DJ, Betik AC, Roberts-Thomson K, Kaur G, Wadley GD, Shaw CS, Keske MA. High-glucose mixed-nutrient meal ingestion impairs skeletal muscle microvascular blood flow in healthy young men. Am J Physiol Endocrinol Metab 2020; 318:E1014-E1021. [PMID: 32286881 DOI: 10.1152/ajpendo.00540.2019] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Oral glucose ingestion leads to impaired muscle microvascular blood flow (MBF), which may contribute to acute hyperglycemia-induced insulin resistance. We investigated whether incorporating lipids and protein into a high-glucose load would prevent postprandial MBF dysfunction. Ten healthy young men (age, 27 yr [24, 30], mean with lower and upper bounds of the 95% confidence interval; height, 180 cm [174, 185]; weight, 77 kg [70, 84]) ingested a high-glucose (1.1 g/kg glucose) mixed-nutrient meal (10 kcal/kg; 45% carbohydrate, 20% protein, and 35% fat) in the morning after an overnight fast. Femoral arterial blood flow was measured via Doppler ultrasound, and thigh MBF was measured via contrast-enhanced ultrasound, before meal ingestion and 1 h and 2 h postprandially. Blood glucose and plasma insulin were measured at baseline and every 15 min throughout the 2-h postprandial period. Compared with baseline, thigh muscle microvascular blood volume, velocity, and flow were significantly impaired at 60 min postprandial (-25%, -27%, and -46%, respectively; all P < 0.05) and to a greater extent at 120 min postprandial (-37%, -46%, and -64%; all P < 0.01). Heart rate and femoral arterial diameter, blood velocity, and blood flow were significantly increased at 60 min and 120 min postprandial (all P < 0.05). Higher blood glucose area under the curve was correlated with greater MBF dysfunction (R2 = 0.742; P < 0.001). Ingestion of a high-glucose mixed-nutrient meal impairs MBF in healthy individuals for up to 2 h postprandial.
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Affiliation(s)
- Lewan Parker
- Institute for Physical Activity and Nutrition (IPAN), School of Exercise and Nutrition Sciences, Deakin University, Geelong, Victoria, Australia
| | - Dale J Morrison
- Institute for Physical Activity and Nutrition (IPAN), School of Exercise and Nutrition Sciences, Deakin University, Geelong, Victoria, Australia
| | - Andrew C Betik
- Institute for Physical Activity and Nutrition (IPAN), School of Exercise and Nutrition Sciences, Deakin University, Geelong, Victoria, Australia
| | - Katherine Roberts-Thomson
- Institute for Physical Activity and Nutrition (IPAN), School of Exercise and Nutrition Sciences, Deakin University, Geelong, Victoria, Australia
| | - Gunveen Kaur
- Institute for Physical Activity and Nutrition (IPAN), School of Exercise and Nutrition Sciences, Deakin University, Geelong, Victoria, Australia
| | - Glenn D Wadley
- Institute for Physical Activity and Nutrition (IPAN), School of Exercise and Nutrition Sciences, Deakin University, Geelong, Victoria, Australia
| | - Christopher S Shaw
- Institute for Physical Activity and Nutrition (IPAN), School of Exercise and Nutrition Sciences, Deakin University, Geelong, Victoria, Australia
| | - Michelle A Keske
- Institute for Physical Activity and Nutrition (IPAN), School of Exercise and Nutrition Sciences, Deakin University, Geelong, Victoria, Australia
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Paiva L, Leng G. Peripheral insulin administration enhances the electrical activity of oxytocin and vasopressin neurones in vivo. J Neuroendocrinol 2020; 32:e12841. [PMID: 32180284 DOI: 10.1111/jne.12841] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Revised: 02/25/2020] [Accepted: 02/25/2020] [Indexed: 11/30/2022]
Abstract
Oxytocin neurones are involved in the regulation of energy balance through diverse central and peripheral actions and, in rats, they are potently activated by gavage of sweet substances. Here, we test the hypothesis that this activation is mediated by the central actions of insulin. We show that, in urethane-anaesthetised rats, oxytocin cells in the supraoptic nucleus show prolonged activation after i.v. injections of insulin, and that this response is greater in fasted rats than in non-fasted rats. Vasopressin cells are also activated, although less consistently. We also show that this activation of oxytocin cells is independent of changes in plasma glucose concentration, and is completely blocked by central (i.c.v.) administration of an insulin receptor antagonist. Finally, we replicate the previously published finding that oxytocin cells are activated by gavage of sweetened condensed milk, and show that this response too is completely blocked by central administration of an insulin receptor antagonist. We conclude that the response of oxytocin cells to gavage of sweetened condensed milk is mediated by the central actions of insulin.
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Affiliation(s)
- Luis Paiva
- Centre for Discovery Brain Sciences, The University of Edinburgh, Edinburgh, UK
| | - Gareth Leng
- Centre for Discovery Brain Sciences, The University of Edinburgh, Edinburgh, UK
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Shi W, Xing L, Jing L, Tian Y, Yan H, Sun Q, Dai D, Shi L, Liu S. Value of triglyceride-glucose index for the estimation of ischemic stroke risk: Insights from a general population. Nutr Metab Cardiovasc Dis 2020; 30:245-253. [PMID: 31744716 DOI: 10.1016/j.numecd.2019.09.015] [Citation(s) in RCA: 62] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/04/2019] [Revised: 08/26/2019] [Accepted: 09/16/2019] [Indexed: 01/20/2023]
Abstract
BACKGROUND AND AIMS Recent studies have recognized triglyceride-glucose index (TyG) as a practical surrogate of insulin resistance. Previous studies have demonstrated that insulin resistance contributes to ischemic stroke via multiple mechanisms. Our study aimed to investigate the association between TyG and prevalent ischemic stroke, exploring the value of TyG to optimize the risk stratification of ischemic stroke. METHODS AND RESULTS This cross-sectional study included 10,900 subjects (mean age: 59.95 years, 59.8% females) from rural areas of northeast China between September 2017 to May 2018. TyG was calculated as ln[fasting triglyceride (mg/dl) × fasting plasma glucose (mg/dl)/2]. The prevalence of ischemic stroke was 5.49%. After adjusting for all covariates, each SD increment of TyG caused 22.8% additional risk for ischemic stroke. When dividing TyG into quartiles, the top quartile had a 1.776 times risk for ischemic stroke against the bottom category. Furthermore, smoothing curve fitting demonstrated this association was linear in the whole range of TyG. Finally, AUC revealed an improvement when introducing TyG into clinical risk factors (0.746 vs 0.751, p = 0.029). Consistently, category-free net reclassification index (0.195, 95% CI: 0.112-0.277, P < 0.001) and integrated discrimination index (0.003, 95% CI: 0.001-0.004, P < 0.001) confirmed the improvement by TyG to stratify ischemic stroke risk. CONCLUSION The prevent ischemic stroke correlated proportionally with the increment of TyG, implicating the linearity of TyG as an indicator of ischemic stroke. Our findings suggest the potential value of TyG to optimize the risk stratification of ischemic stroke in a general population.
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Affiliation(s)
- Wenrui Shi
- Department of Cardiology, The First Affiliated Hospital of China Medical University, Shenyang, Liaoning, People's Republic of China
| | - Liying Xing
- Department of Cardiology, The First Affiliated Hospital of China Medical University, Shenyang, Liaoning, People's Republic of China; Liaoning Provincial Center for Disease Control and Prevention, Shenyang, Liaoning, People's Republic of China
| | - Li Jing
- Liaoning Provincial Center for Disease Control and Prevention, Shenyang, Liaoning, People's Republic of China
| | - Yuanmeng Tian
- Liaoning Provincial Center for Disease Control and Prevention, Shenyang, Liaoning, People's Republic of China
| | - Han Yan
- Liaoning Provincial Center for Disease Control and Prevention, Shenyang, Liaoning, People's Republic of China
| | - Qun Sun
- Disease Control and Prevention of Chao Yang City, Chaoyang, Liaoning, People's Republic of China
| | - Dong Dai
- Disease Control and Prevention of Dan Dong City, Dandong, Liaoning, People's Republic of China
| | - Lei Shi
- Disease Control and Prevention of Liao Yang City, Liaoyang, Liaoning, People's Republic of China
| | - Shuang Liu
- Department of Cardiovascular Ultrasound, The First Affiliated Hospital of China Medical University, Shenyang, 110005, Liaoning, People's Republic of China.
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Shi W, Xing L, Jing L, Tian Y, Liu S. Usefulness of Triglyceride-glucose Index for estimating Hyperuricemia risk: Insights from a general Population. Postgrad Med 2019; 131:348-356. [PMID: 31132018 DOI: 10.1080/00325481.2019.1624581] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Objectives: Hyperuricemia is a metabolic abnormality that has cast an enormous burden on global healthcare. Previous studies have revealed the close association between insulin resistance and hyperuricemia. Therefore, monitoring insulin sensitivity may be a possible way to prevent hyperuricemia. Recent studies have demonstrated the usefulness of triglyceride-glucose index (TyG) as a simple surrogate of insulin resistance. Hence, our study aimed to explore the impact of TyG on hyperuricemia and its value to improve the risk stratification and prevention of hyperuricemia. Methods: This cross-sectional study included 6466 subjects (mean age: 59.57 years, 60.19% females) from northeast China between September 2017 to May 2018. TyG was determined as ln[fasting TG(mg/dL)×FPG(mg/dL)/2]. Hyperuricemia was defined as serum uric acid ≥ 357 μmol/L for females and ≥ 417 μmol/L for males. Results: The prevalence of hyperuricemia was 5.24%. In the full model, each SD increment of TyG caused a 12.528 μmol/L elevation of serum urate concentration and a 54.1% additional risk for hyperuricemia. When dividing TyG into quartiles, the top quartile had a 2.730 times risk for hyperuricemia than the bottom one. Moreover, smooth curve fitting demonstrated this association was linear. Additionally, subgroup analysis revealed the association was robust to several risk factors of hyperuricemia. Finally, AUC displayed an improvement when introducing TyG into clinical risk factors (0.751 vs 0.772, p < 0.001), category-free net reclassification index (0.304, 95% CI: 0.195-0.413, P < 0.001) and integrated discrimination index (0.009, 95% CI: 0.004-0.013, P < 0.001) also showed the improvement from TyG. Conclusion: Our work revealed the linear and robust association between TyG and hyperuricemia. Furthermore, our results suggest the importance of simultaneous glycemic and lipids control in the prevention of hyperuricemia. Most importantly, our findings implicate the value of TyG to optimize the risk stratification and prevention of hyperuricemia.
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Affiliation(s)
- Wenrui Shi
- a Department of Cardiology , The First Affiliated Hospital of China Medical University , Shenyang , Liaoning , People's Republic of China
| | - Liying Xing
- b Department of Cardiovascular Diseases Prevention , Liaoning Provincial Center for Disease Control and Prevention , Shenyang , Liaoning , People's Republic of China
| | - Li Jing
- b Department of Cardiovascular Diseases Prevention , Liaoning Provincial Center for Disease Control and Prevention , Shenyang , Liaoning , People's Republic of China
| | - Yuanmeng Tian
- b Department of Cardiovascular Diseases Prevention , Liaoning Provincial Center for Disease Control and Prevention , Shenyang , Liaoning , People's Republic of China
| | - Shuang Liu
- c Department of Cardiovascular Ultrasound , The First Affiliated Hospital of China Medical University , Shenyang , Liaoning , People's Republic of China
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Cairns R, Fischer AW, Blanco-Munoz P, Alvarez-Guaita A, Meneses-Salas E, Egert A, Buechler C, Hoy AJ, Heeren J, Enrich C, Rentero C, Grewal T. Altered hepatic glucose homeostasis in AnxA6-KO mice fed a high-fat diet. PLoS One 2018; 13:e0201310. [PMID: 30110341 PMCID: PMC6093612 DOI: 10.1371/journal.pone.0201310] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2017] [Accepted: 07/12/2018] [Indexed: 12/12/2022] Open
Abstract
Annexin A6 (AnxA6) controls cholesterol and membrane transport in endo- and exocytosis, and modulates triglyceride accumulation and storage. In addition, AnxA6 acts as a scaffolding protein for negative regulators of growth factor receptors and their effector pathways in many different cell types. Here we investigated the role of AnxA6 in the regulation of whole body lipid metabolism and insulin-regulated glucose homeostasis. Therefore, wildtype (WT) and AnxA6-knockout (KO) mice were fed a high-fat diet (HFD) for 17 weeks. During the course of HFD feeding, AnxA6-KO mice gained less weight compared to controls, which correlated with reduced adiposity. Systemic triglyceride and cholesterol levels of HFD-fed control and AnxA6-KO mice were comparable, with slightly elevated high density lipoprotein (HDL) and reduced triglyceride-rich lipoprotein (TRL) levels in AnxA6-KO mice. AnxA6-KO mice displayed a trend towards improved insulin sensitivity in oral glucose and insulin tolerance tests (OGTT, ITT), which correlated with increased insulin-inducible phosphorylation of protein kinase B (Akt) and ribosomal protein S6 kinase (S6) in liver extracts. However, HFD-fed AnxA6-KO mice failed to downregulate hepatic gluconeogenesis, despite similar insulin levels and insulin signaling activity, as well as expression profiles of insulin-sensitive transcription factors to controls. In addition, increased glycogen storage in livers of HFD- and chow-fed AnxA6-KO animals was observed. Together with an inability to reduce glucose production upon insulin exposure in AnxA6-depleted HuH7 hepatocytes, this implicates AnxA6 contributing to the fine-tuning of hepatic glucose metabolism with potential consequences for the systemic control of glucose in health and disease.
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Affiliation(s)
- Rose Cairns
- School of Pharmacy, Faculty of Medicine and Health, University of Sydney, Sydney, NSW, Australia
| | - Alexander W. Fischer
- Department of Biochemistry and Molecular Biology II: Molecular Cell Biology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Patricia Blanco-Munoz
- Departament de Biomedicina, Unitat de Biologia Cel·lular, Centre de Recerca Biomèdica CELLEX, Institut d’Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Facultat de Medicina i Ciències de la Salut, Universitat de Barcelona, Barcelona, Spain
| | - Anna Alvarez-Guaita
- Departament de Biomedicina, Unitat de Biologia Cel·lular, Centre de Recerca Biomèdica CELLEX, Institut d’Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Facultat de Medicina i Ciències de la Salut, Universitat de Barcelona, Barcelona, Spain
| | - Elsa Meneses-Salas
- Departament de Biomedicina, Unitat de Biologia Cel·lular, Centre de Recerca Biomèdica CELLEX, Institut d’Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Facultat de Medicina i Ciències de la Salut, Universitat de Barcelona, Barcelona, Spain
| | - Antonia Egert
- School of Pharmacy, Faculty of Medicine and Health, University of Sydney, Sydney, NSW, Australia
| | - Christa Buechler
- Department of Internal Medicine I, Regensburg University Hospital, Regensburg, Germany
| | - Andrew J. Hoy
- Discipline of Physiology, School of Medical Science, Sydney Medical School, Charles Perkins Centre, University of Sydney, Sydney, NSW, Australia
| | - Joerg Heeren
- Department of Biochemistry and Molecular Biology II: Molecular Cell Biology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Carlos Enrich
- Departament de Biomedicina, Unitat de Biologia Cel·lular, Centre de Recerca Biomèdica CELLEX, Institut d’Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Facultat de Medicina i Ciències de la Salut, Universitat de Barcelona, Barcelona, Spain
| | - Carles Rentero
- Departament de Biomedicina, Unitat de Biologia Cel·lular, Centre de Recerca Biomèdica CELLEX, Institut d’Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Facultat de Medicina i Ciències de la Salut, Universitat de Barcelona, Barcelona, Spain
- * E-mail: (TG); (CR)
| | - Thomas Grewal
- School of Pharmacy, Faculty of Medicine and Health, University of Sydney, Sydney, NSW, Australia
- * E-mail: (TG); (CR)
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11
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Russell RD, Hu D, Greenaway T, Sharman JE, Rattigan S, Richards SM, Keske MA. Oral glucose challenge impairs skeletal muscle microvascular blood flow in healthy people. Am J Physiol Endocrinol Metab 2018; 315:E307-E315. [PMID: 29763373 DOI: 10.1152/ajpendo.00448.2017] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Skeletal muscle microvascular (capillary) blood flow increases in the postprandial state or during insulin infusion due to dilation of precapillary arterioles to augment glucose disposal. This effect occurs independently of changes in large artery function. However, acute hyperglycemia impairs vascular function, causes insulin to vasoconstrict precapillary arterioles, and causes muscle insulin resistance in vivo. We hypothesized that acute hyperglycemia impairs postprandial muscle microvascular perfusion, without disrupting normal large artery hemodynamics, in healthy humans. Fifteen healthy people (5 F/10 M) underwent an oral glucose challenge (OGC, 50 g glucose) and a mixed-meal challenge (MMC) on two separate occasions (randomized, crossover design). At 1 h, both challenges produced a comparable increase (6-fold) in plasma insulin levels. However, the OGC produced a 1.5-fold higher increase in blood glucose compared with the MMC 1 h postingestion. Forearm muscle microvascular blood volume and flow (contrast-enhanced ultrasound) were increased during the MMC (1.3- and 1.9-fold from baseline, respectively, P < 0.05 for both) but decreased during the OGC (0.7- and 0.6-fold from baseline, respectively, P < 0.05 for both) despite a similar hyperinsulinemia. Both challenges stimulated brachial artery flow (ultrasound) and heart rate to a similar extent, as well as yielding comparable decreases in diastolic blood pressure and total vascular resistance. Systolic blood pressure and aortic stiffness remained unaltered by either challenge. Independently of large artery hemodynamics, hyperglycemia impairs muscle microvascular blood flow, potentially limiting glucose disposal into skeletal muscle. The OGC reduced microvascular blood flow in muscle peripherally and therefore may underestimate the importance of skeletal muscle in postprandial glucose disposal.
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Affiliation(s)
- Ryan D Russell
- Menzies Institute for Medical Research, University of Tasmania , Hobart, Tasmania , Australia
- Department of Health and Human Performance, College of Health Affairs, University of Texas Rio Grande Valley , Brownsville, Texas
| | - Donghua Hu
- Menzies Institute for Medical Research, University of Tasmania , Hobart, Tasmania , Australia
| | - Timothy Greenaway
- Royal Hobart Hospital , Hobart, Tasmania , Australia
- School of Medicine, University of Tasmania , Hobart, Tasmania , Australia
| | - James E Sharman
- Menzies Institute for Medical Research, University of Tasmania , Hobart, Tasmania , Australia
| | - Stephen Rattigan
- Menzies Institute for Medical Research, University of Tasmania , Hobart, Tasmania , Australia
| | - Stephen M Richards
- Menzies Institute for Medical Research, University of Tasmania , Hobart, Tasmania , Australia
- School of Medicine, University of Tasmania , Hobart, Tasmania , Australia
| | - Michelle A Keske
- Menzies Institute for Medical Research, University of Tasmania , Hobart, Tasmania , Australia
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition. Deakin University , Geelong, Victoria , Australia
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12
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Holt LJ, Brandon AE, Small L, Suryana E, Preston E, Wilks D, Mokbel N, Coles CA, White JD, Turner N, Daly RJ, Cooney GJ. Ablation of Grb10 Specifically in Muscle Impacts Muscle Size and Glucose Metabolism in Mice. Endocrinology 2018; 159:1339-1351. [PMID: 29370381 DOI: 10.1210/en.2017-00851] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/19/2017] [Accepted: 01/17/2018] [Indexed: 12/14/2022]
Abstract
Grb10 is an adaptor-type signaling protein most highly expressed in tissues involved in insulin action and glucose metabolism, such as muscle, pancreas, and adipose. Germline deletion of Grb10 in mice creates a phenotype with larger muscles and improved glucose homeostasis. However, it has not been determined whether Grb10 ablation specifically in muscle is sufficient to induce hypermuscularity or affect whole body glucose metabolism. In this study we generated muscle-specific Grb10-deficient mice (Grb10-mKO) by crossing Grb10flox/flox mice with mice expressing Cre recombinase under control of the human α-skeletal actin promoter. One-year-old Grb10-mKO mice had enlarged muscles, with greater cross-sectional area of fibers compared with wild-type (WT) mice. This degree of hypermuscularity did not affect whole body glucose homeostasis under basal conditions. However, hyperinsulinemic/euglycemic clamp studies revealed that Grb10-mKO mice had greater glucose uptake into muscles compared with WT mice. Insulin signaling was increased at the level of phospho-Akt in muscle of Grb10-mKO mice compared with WT mice, consistent with a role of Grb10 as a modulator of proximal insulin receptor signaling. We conclude that ablation of Grb10 in muscle is sufficient to affect muscle size and metabolism, supporting an important role for this protein in growth and metabolic pathways.
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Affiliation(s)
- Lowenna J Holt
- Diabetes and Metabolism Division, Garvan Institute of Medical Research, Sydney, New South Wales, Australia
| | - Amanda E Brandon
- Diabetes and Metabolism Division, Garvan Institute of Medical Research, Sydney, New South Wales, Australia
- School of Medical Sciences, Charles Perkins Centre, University of Sydney, Sydney, New South Wales, Australia
| | - Lewin Small
- Diabetes and Metabolism Division, Garvan Institute of Medical Research, Sydney, New South Wales, Australia
| | - Eurwin Suryana
- Diabetes and Metabolism Division, Garvan Institute of Medical Research, Sydney, New South Wales, Australia
| | - Elaine Preston
- Diabetes and Metabolism Division, Garvan Institute of Medical Research, Sydney, New South Wales, Australia
| | - Donna Wilks
- Diabetes and Metabolism Division, Garvan Institute of Medical Research, Sydney, New South Wales, Australia
| | - Nancy Mokbel
- Diabetes and Metabolism Division, Garvan Institute of Medical Research, Sydney, New South Wales, Australia
| | - Chantal A Coles
- Murdoch Children's Research Institute, Royal Children's Hospital, Parkville, Victoria, Australia
| | - Jason D White
- Murdoch Children's Research Institute, Royal Children's Hospital, Parkville, Victoria, Australia
- Department of Veterinary Biosciences, Faculty of Veterinary and Agricultural Science, University of Melbourne, Parkville, Victoria, Australia
| | - Nigel Turner
- Diabetes and Metabolism Division, Garvan Institute of Medical Research, Sydney, New South Wales, Australia
- Department of Pharmacology, University of New South Wales, Sydney, New South Wales, Australia
| | - Roger J Daly
- Cancer Program, Biomedicine Discovery Institute, Monash University, Clayton, Victoria, Australia
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, Australia
| | - Gregory J Cooney
- Diabetes and Metabolism Division, Garvan Institute of Medical Research, Sydney, New South Wales, Australia
- School of Medical Sciences, Charles Perkins Centre, University of Sydney, Sydney, New South Wales, Australia
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13
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Small L, Brandon AE, Turner N, Cooney GJ. Modeling insulin resistance in rodents by alterations in diet: what have high-fat and high-calorie diets revealed? Am J Physiol Endocrinol Metab 2018; 314:E251-E265. [PMID: 29118016 DOI: 10.1152/ajpendo.00337.2017] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
For over half a century, researchers have been feeding different diets to rodents to examine the effects of macronutrients on whole body and tissue insulin action. During this period, the number of different diets and the source of macronutrients employed have grown dramatically. Because of the large heterogeneity in both the source and percentage of different macronutrients used for studies, it is not surprising that different high-calorie diets do not produce the same changes in insulin action. Despite this, diverse high-calorie diets continue to be employed in an attempt to generate a "generic" insulin resistance. The high-fat diet in particular varies greatly between studies with regard to the source, complexity, and ratio of dietary fat, carbohydrate, and protein. This review examines the range of rodent dietary models and methods for assessing insulin action. In almost all studies reviewed, rodents fed diets that had more than 45% of dietary energy as fat or simple carbohydrates had reduced whole body insulin action compared with chow. However, different high-calorie diets produced significantly different effects in liver, muscle, and whole body insulin action when insulin action was measured by the hyperinsulinemic-euglycemic clamp method. Rodent dietary models remain an important tool for exploring potential mechanisms of insulin resistance, but more attention needs to be given to the total macronutrient content and composition when interpreting dietary effects on insulin action.
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Affiliation(s)
- Lewin Small
- Diabetes and Metabolism Division, Garvan Institute , Sydney, New South Wales , Australia
| | - Amanda E Brandon
- Diabetes and Metabolism Division, Garvan Institute , Sydney, New South Wales , Australia
- Sydney Medical School, Charles Perkins Centre, The University of Sydney , New South Wales , Australia
| | - Nigel Turner
- Department of Pharmacology, School of Medical Science, University of New South Wales , Sydney, New South Wales , Australia
| | - Gregory J Cooney
- Diabetes and Metabolism Division, Garvan Institute , Sydney, New South Wales , Australia
- Sydney Medical School, Charles Perkins Centre, The University of Sydney , New South Wales , Australia
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14
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A gas trapping method for high-throughput metabolic experiments. Biotechniques 2018; 64:27-29. [PMID: 29384075 DOI: 10.2144/000114629] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2017] [Accepted: 12/05/2017] [Indexed: 11/23/2022] Open
Abstract
Research into cellular metabolism has become more high-throughput, with typical cell-culture experiments being performed in multiwell plates (microplates). This format presents a challenge when trying to collect gaseous products, such as carbon dioxide (CO2), which requires a sealed environment and a vessel separate from the biological sample. To address this limitation, we developed a gas trapping protocol using perforated plastic lids in sealed cell-culture multiwell plates. We used this trap design to measure CO2 production from glucose and fatty acid metabolism, as well as hydrogen sulfide production from cysteine-treated cells. Our data clearly show that this gas trap can be applied to liquid and solid gas-collection media and can be used to study gaseous product generation by both adherent cells and cells in suspension. Since our gas traps can be adapted to multiwell plates of various sizes, they present a convenient, cost-effective solution that can accommodate the trend toward high-throughput measurements in metabolic research.
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15
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Kjøbsted R, Wojtaszewski JFP, Treebak JT. Role of AMP-Activated Protein Kinase for Regulating Post-exercise Insulin Sensitivity. ACTA ACUST UNITED AC 2017; 107:81-126. [PMID: 27812978 DOI: 10.1007/978-3-319-43589-3_5] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Skeletal muscle insulin resistance precedes development of type 2 diabetes (T2D). As skeletal muscle is a major sink for glucose disposal, understanding the molecular mechanisms involved in maintaining insulin sensitivity of this tissue could potentially benefit millions of people that are diagnosed with insulin resistance. Regular physical activity in both healthy and insulin-resistant individuals is recognized as the single most effective intervention to increase whole-body insulin sensitivity and thereby positively affect glucose homeostasis. A single bout of exercise has long been known to increase glucose disposal in skeletal muscle in response to physiological insulin concentrations. While this effect is identified to be restricted to the previously exercised muscle, the molecular basis for an apparent convergence between exercise- and insulin-induced signaling pathways is incompletely known. In recent years, we and others have identified the Rab GTPase-activating protein, TBC1 domain family member 4 (TBC1D4) as a target of key protein kinases in the insulin- and exercise-activated signaling pathways. Our working hypothesis is that the AMP-activated protein kinase (AMPK) is important for the ability of exercise to insulin sensitize skeletal muscle through TBC1D4. Here, we aim to provide an overview of the current available evidence linking AMPK to post-exercise insulin sensitivity.
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Affiliation(s)
- Rasmus Kjøbsted
- Novo Nordisk Foundation Center for Basic Metabolic Research, Section of Integrative Physiology, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3b, 2200, Copenhagen, Denmark
- Section of Molecular Physiology, Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, 2100, Copenhagen, Denmark
| | - Jørgen F P Wojtaszewski
- Section of Molecular Physiology, Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, 2100, Copenhagen, Denmark
| | - Jonas T Treebak
- Novo Nordisk Foundation Center for Basic Metabolic Research, Section of Integrative Physiology, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3b, 2200, Copenhagen, Denmark.
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16
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Morita I, Tanimoto K, Akiyama N, Naya N, Fujieda K, Iwasaki T, Yukioka H. Chronic hyperinsulinemia contributes to insulin resistance under dietary restriction in association with altered lipid metabolism in Zucker diabetic fatty rats. Am J Physiol Endocrinol Metab 2017; 312:E264-E272. [PMID: 28143857 DOI: 10.1152/ajpendo.00342.2016] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/19/2016] [Revised: 01/06/2017] [Accepted: 01/23/2017] [Indexed: 12/14/2022]
Abstract
Hyperinsulinemia is widely thought to be a compensatory response to insulin resistance, whereas its potentially causal role in the progression of insulin resistance remains to be established. Here, we aimed to examine whether hyperinsulinemia could affect the progression of insulin resistance in Zucker fatty diabetic (ZDF) rats. Male ZDF rats at 8 wk of age were fed a diet ad libitum (AL) or dietary restriction (DR) of either 15 or 30% from AL feeding over 6 wk. Insulin sensitivity was determined by hyperinsulinemic euglycemic clamp. ZDF rats in the AL group progressively developed hyperglycemia and hyperinsulinemia by 10 wk of age, and then plasma insulin rapidly declined to nearly normal levels by 12 wk of age. Compared with AL group, DR groups showed delayed onset of hyperglycemia and persistent hyperinsulinemia, leading to weight gain and raised plasma triglycerides and free fatty acids by 14 wk of age. Notably, insulin sensitivity was significantly reduced in the DR group rather than the AL group and inversely correlated with plasma levels of insulin and triglyceride but not glucose. Moreover, enhanced lipid deposition and upregulation of genes involved in lipogenesis were detected in liver, skeletal muscle, and adipose tissues of the DR group rather than the AL group. Alternatively, continuous hyperinsulinemia induced by insulin pellet implantation produced a decrease in insulin sensitivity in ZDF rats. These results suggest that chronic hyperinsulinemia may lead to the progression of insulin resistance under DR conditions in association with altered lipid metabolism in peripheral tissues in ZDF rats.
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Affiliation(s)
- Ippei Morita
- Drug Discovery and Disease Research Laboratory, Shionogi and Company, Ltd., Osaka, Japan
| | - Keiichi Tanimoto
- Drug Discovery and Disease Research Laboratory, Shionogi and Company, Ltd., Osaka, Japan
| | - Nobuteru Akiyama
- Drug Discovery and Disease Research Laboratory, Shionogi and Company, Ltd., Osaka, Japan
| | - Noriyuki Naya
- Drug Discovery and Disease Research Laboratory, Shionogi and Company, Ltd., Osaka, Japan
| | - Kumiko Fujieda
- Drug Discovery and Disease Research Laboratory, Shionogi and Company, Ltd., Osaka, Japan
| | - Takanori Iwasaki
- Drug Discovery and Disease Research Laboratory, Shionogi and Company, Ltd., Osaka, Japan
| | - Hideo Yukioka
- Drug Discovery and Disease Research Laboratory, Shionogi and Company, Ltd., Osaka, Japan
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17
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Nagarajan SR, Brandon AE, McKenna JA, Shtein HC, Nguyen TQ, Suryana E, Poronnik P, Cooney GJ, Saunders DN, Hoy AJ. Insulin and diet-induced changes in the ubiquitin-modified proteome of rat liver. PLoS One 2017; 12:e0174431. [PMID: 28329008 PMCID: PMC5362237 DOI: 10.1371/journal.pone.0174431] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Accepted: 03/08/2017] [Indexed: 12/14/2022] Open
Abstract
Ubiquitin is a crucial post-translational modification regulating numerous cellular processes, but its role in metabolic disease is not well characterized. In this study, we identified the in vivo ubiquitin-modified proteome in rat liver and determined changes in this ubiquitome under acute insulin stimulation and high-fat and sucrose diet-induced insulin resistance. We identified 1267 ubiquitinated proteins in rat liver across diet and insulin-stimulated conditions, with 882 proteins common to all conditions. KEGG pathway analysis of these proteins identified enrichment of metabolic pathways, TCA cycle, glycolysis/gluconeogenesis, fatty acid metabolism, and carbon metabolism, with similar pathways altered by diet and insulin resistance. Thus, the rat liver ubiquitome is sensitive to diet and insulin stimulation and this is perturbed in insulin resistance.
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Affiliation(s)
- Shilpa R. Nagarajan
- Discipline of Physiology, School of Medical Sciences & Bosch Institute, Charles Perkins Centre, University of Sydney, Sydney, NSW, Australia
| | - Amanda E. Brandon
- Diabetes and Metabolism Division, Garvan Institute of Medical Research, Darlinghurst, NSW, Australia
- St Vincent’s Clinical School, Faculty of Medicine, University of New South Wales, Sydney, NSW, Australia
| | - Jessie A. McKenna
- Kinghorn Cancer Centre, Garvan Institute of Medical Research, Darlinghurst, NSW, Australia
- School of Medical Sciences, Faculty of Medicine, University of New South Wales, Sydney, NSW, Australia
| | - Harrison C. Shtein
- Discipline of Physiology, School of Medical Sciences & Bosch Institute, Charles Perkins Centre, University of Sydney, Sydney, NSW, Australia
| | - Thinh Q. Nguyen
- Discipline of Physiology, School of Medical Sciences & Bosch Institute, Charles Perkins Centre, University of Sydney, Sydney, NSW, Australia
| | - Eurwin Suryana
- Diabetes and Metabolism Division, Garvan Institute of Medical Research, Darlinghurst, NSW, Australia
| | - Philip Poronnik
- Discipline of Physiology, School of Medical Sciences & Bosch Institute, Charles Perkins Centre, University of Sydney, Sydney, NSW, Australia
| | - Gregory J. Cooney
- Diabetes and Metabolism Division, Garvan Institute of Medical Research, Darlinghurst, NSW, Australia
- St Vincent’s Clinical School, Faculty of Medicine, University of New South Wales, Sydney, NSW, Australia
| | - Darren N. Saunders
- Kinghorn Cancer Centre, Garvan Institute of Medical Research, Darlinghurst, NSW, Australia
- School of Medical Sciences, Faculty of Medicine, University of New South Wales, Sydney, NSW, Australia
- * E-mail: (AJH); (DNS)
| | - Andrew J. Hoy
- Discipline of Physiology, School of Medical Sciences & Bosch Institute, Charles Perkins Centre, University of Sydney, Sydney, NSW, Australia
- * E-mail: (AJH); (DNS)
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18
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Maniam J, Antoniadis CP, Le V, Morris MJ. A diet high in fat and sugar reverses anxiety-like behaviour induced by limited nesting in male rats: Impacts on hippocampal markers. Psychoneuroendocrinology 2016; 68:202-9. [PMID: 26999723 DOI: 10.1016/j.psyneuen.2016.03.007] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/02/2015] [Revised: 02/01/2016] [Accepted: 03/09/2016] [Indexed: 12/29/2022]
Abstract
Stress exposure during early development is known to produce long-term mental health deficits. Stress promotes poor lifestyle choices such as poor diet. Early life adversity and diets high in fat and sugar (HFHS) are known to affect anxiety and memory. However additive effects of HFHS and stress during early development are less explored. Here, we examined whether early life stress (ELS) simulated by limited nesting (LN) induces anxiety-like behaviour and cognitive deficits that are modulated by HFHS diet. We examined key hippocampal markers involved in anxiety and cognition, testing the hypothesis that post-weaning HFHS following ELS would ameliorate anxiety-like behaviour but worsen memory and associated hippocampal changes. Sprague-Dawley rats were exposed to LN, postnatal days 2-9, and at weaning, male siblings were given unlimited access to chow or HFHS resulting in (Con-Chow, Con-HFHS, LN-Chow, LN-HFHS, n=11-15/group). Anxiety-like behaviour was assessed by Elevated Plus Maze (EPM) at 10 weeks and spatial and object recognition tested at 11 weeks of age. Rats were culled at 13 weeks. Hippocampal mRNA expression was measured using TaqMan(®) Array Micro Fluidic cards (Life Technologies). As expected HFHS diet increased body weight; LN and control rats had similar weights at 13 weeks, energy intake was also similar across groups. LN-Chow rats showed increased anxiety-like behaviour relative to control rats, but this was reversed by HFHS diet. Spatial and object recognition memory were unaltered by LN exposure or consumption of HFHS diet. Hippocampal glucocorticoid receptor (GR) protein was not affected by LN exposure in chow rats, but was increased by 45% in HFHS rats relative to controls. Hippocampal genes involved in plasticity and mood regulation, GSKα and GSKβ were affected, with reductions in GSKβ under both diet conditions, and reduced GSKα only in LN-HFHS versus Con-HFHS. Interestingly, HFHS diet and LN exposure independently reduced expression of Akt3 mRNA, a key gene involved post-natal brain development. In summary, while an energy rich diet ameliorated anxiety-like behaviour induced by LN exposure, it significantly altered key genes that are essential for hippocampal development.
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Affiliation(s)
- Jayanthi Maniam
- Department of Pharmacology, School of Medical Sciences, UNSW Australia, Sydney 2052, New South Wales, Australia
| | - Christopher P Antoniadis
- Department of Pharmacology, School of Medical Sciences, UNSW Australia, Sydney 2052, New South Wales, Australia
| | - Vivian Le
- Department of Pharmacology, School of Medical Sciences, UNSW Australia, Sydney 2052, New South Wales, Australia
| | - Margaret J Morris
- Department of Pharmacology, School of Medical Sciences, UNSW Australia, Sydney 2052, New South Wales, Australia.
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19
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Coughlan KA, Balon TW, Valentine RJ, Petrocelli R, Schultz V, Brandon A, Cooney GJ, Kraegen EW, Ruderman NB, Saha AK. Nutrient Excess and AMPK Downregulation in Incubated Skeletal Muscle and Muscle of Glucose Infused Rats. PLoS One 2015; 10:e0127388. [PMID: 25996822 PMCID: PMC4440828 DOI: 10.1371/journal.pone.0127388] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2014] [Accepted: 04/15/2015] [Indexed: 11/18/2022] Open
Abstract
We have previously shown that incubation for 1h with excess glucose or leucine causes insulin resistance in rat extensor digitorum longus (EDL) muscle by inhibiting AMP-activated protein kinase (AMPK). To examine the events that precede and follow these changes, studies were performed in rat EDL incubated with elevated levels of glucose or leucine for 30min-2h. Incubation in high glucose (25mM) or leucine (100μM) significantly diminished AMPK activity by 50% within 30min, with further decreases occurring at 1 and 2h. The initial decrease in activity at 30min coincided with a significant increase in muscle glycogen. The subsequent decreases at 1h were accompanied by phosphorylation of αAMPK at Ser485/491, and at 2h by decreased SIRT1 expression and increased PP2A activity, all of which have previously been shown to diminish AMPK activity. Glucose infusion in vivo, which caused several fold increases in plasma glucose and insulin, produced similar changes but with different timing. Thus, the initial decrease in AMPK activity observed at 3h was associated with changes in Ser485/491 phosphorylation and SIRT1 expression and increased PP2A activity was a later event. These findings suggest that both ex vivo and in vivo, multiple factors contribute to fuel-induced decreases in AMPK activity in skeletal muscle and the insulin resistance that accompanies it.
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Affiliation(s)
- Kimberly A. Coughlan
- Department of Medicine, Section of Endocrinology and Diabetes, Boston University Medical Center, Boston, Massachusetts, United States of America
| | - Thomas W. Balon
- Department of Medicine, Section of Endocrinology and Diabetes, Boston University Medical Center, Boston, Massachusetts, United States of America
| | - Rudy J. Valentine
- Department of Medicine, Section of Endocrinology and Diabetes, Boston University Medical Center, Boston, Massachusetts, United States of America
| | - Robert Petrocelli
- Department of Medicine, Section of Endocrinology and Diabetes, Boston University Medical Center, Boston, Massachusetts, United States of America
| | - Vera Schultz
- Department of Medicine, Section of Endocrinology and Diabetes, Boston University Medical Center, Boston, Massachusetts, United States of America
| | - Amanda Brandon
- Diabetes and Obesity Program, Garvan Institute of Medical Research and School of Medical Sciences, University of NSW, Sydney, Australia
| | - Gregory J. Cooney
- Diabetes and Obesity Program, Garvan Institute of Medical Research and School of Medical Sciences, University of NSW, Sydney, Australia
| | - Edward W. Kraegen
- Diabetes and Obesity Program, Garvan Institute of Medical Research and School of Medical Sciences, University of NSW, Sydney, Australia
| | - Neil B. Ruderman
- Department of Medicine, Section of Endocrinology and Diabetes, Boston University Medical Center, Boston, Massachusetts, United States of America
| | - Asish K. Saha
- Department of Medicine, Section of Endocrinology and Diabetes, Boston University Medical Center, Boston, Massachusetts, United States of America
- * E-mail:
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Brandon AE, Tid-Ang J, Wright LE, Stuart E, Suryana E, Bentley N, Turner N, Cooney GJ, Ruderman NB, Kraegen EW. Overexpression of SIRT1 in rat skeletal muscle does not alter glucose induced insulin resistance. PLoS One 2015; 10:e0121959. [PMID: 25798922 PMCID: PMC4370576 DOI: 10.1371/journal.pone.0121959] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2014] [Accepted: 02/10/2015] [Indexed: 12/17/2022] Open
Abstract
SIRT1 is a NAD+-dependent deacetylase thought to regulate cellular metabolic pathways in response to alterations in nutrient flux. In the current study we investigated whether acute changes in SIRT1 expression affect markers of muscle mitochondrial content and also determined whether SIRT1 influenced muscle insulin resistance induced by acute glucose oversupply. In male Wistar rats either SIRT1 or a deacetylase inactive mutant form (H363Y) was electroprated into the tibialis cranialis (TC) muscle. The other leg was electroporated with an empty control vector. One week later, glucose was infused and hyperglycaemia was maintained at ~11mM. After 5 hours, 11mM glucose induced significant insulin resistance in skeletal muscle. Interestingly, overexpression of either SIRT1 or SIRT1 (H363Y) for 1 week did not change markers of mitochondrial content or function. SIRT1 or SIRT1 (H363Y) overexpression had no effect on the reduction in glucose uptake and glycogen synthesis in muscle in response to hyperglycemia. Therefore we conclude that acute increases in SIRT1 protein have little impact on mitochondrial content and that overexpressing SIRT1 does not prevent the development of insulin resistance during hyperglycaemia.
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Affiliation(s)
- Amanda E Brandon
- Diabetes and Metabolism Division, Garvan Institute of Medical Research, 384 Victoria St., Darlinghurst, NSW, 2010, Australia
| | - Jennifer Tid-Ang
- Diabetes and Metabolism Division, Garvan Institute of Medical Research, 384 Victoria St., Darlinghurst, NSW, 2010, Australia
| | - Lauren E Wright
- Diabetes and Metabolism Division, Garvan Institute of Medical Research, 384 Victoria St., Darlinghurst, NSW, 2010, Australia
| | - Ella Stuart
- Diabetes and Metabolism Division, Garvan Institute of Medical Research, 384 Victoria St., Darlinghurst, NSW, 2010, Australia
| | - Eurwin Suryana
- Diabetes and Metabolism Division, Garvan Institute of Medical Research, 384 Victoria St., Darlinghurst, NSW, 2010, Australia
| | | | - Nigel Turner
- Diabetes and Metabolism Division, Garvan Institute of Medical Research, 384 Victoria St., Darlinghurst, NSW, 2010, Australia; UNSW Medicine, University of New South Wales, Sydney, Australia
| | - Gregory J Cooney
- Diabetes and Metabolism Division, Garvan Institute of Medical Research, 384 Victoria St., Darlinghurst, NSW, 2010, Australia; UNSW Medicine, University of New South Wales, Sydney, Australia
| | - Neil B Ruderman
- Boston University School of Medicine, Boston, Massachusetts, United States of America
| | - Edward W Kraegen
- Diabetes and Metabolism Division, Garvan Institute of Medical Research, 384 Victoria St., Darlinghurst, NSW, 2010, Australia; UNSW Medicine, University of New South Wales, Sydney, Australia
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Mokbel N, Hoffman NJ, Girgis CM, Small L, Turner N, Daly RJ, Cooney GJ, Holt LJ. Grb10 deletion enhances muscle cell proliferation, differentiation and GLUT4 plasma membrane translocation. J Cell Physiol 2014; 229:1753-64. [PMID: 24664951 DOI: 10.1002/jcp.24628] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2013] [Accepted: 03/21/2014] [Indexed: 12/25/2022]
Abstract
Grb10 is an intracellular adaptor protein which binds directly to several growth factor receptors, including those for insulin and insulin-like growth factor receptor-1 (IGF-1), and negatively regulates their actions. Grb10-ablated (Grb10(-/-) ) mice exhibit improved whole body glucose homeostasis and an increase in muscle mass associated specifically with an increase in myofiber number. This suggests that Grb10 may act as a negative regulator of myogenesis. In this study, we investigated in vitro, the molecular mechanisms underlying the increase in muscle mass and the improved glucose metabolism. Primary muscle cells isolated from Grb10(-/-) mice exhibited increased rates of proliferation and differentiation compared to primary cells isolated from wild-type mice. The improved proliferation capacity was associated with an enhanced phosphorylation of Akt and ERK in the basal state and changes in the expression of key cell cycle progression markers involved in regulating transition of cells from the G1 to S phase (e.g., retinoblastoma (Rb) and p21). The absence of Grb10 also promoted a faster transition to a myogenin positive, differentiated state. Glucose uptake was higher in Grb10(-/-) primary myotubes in the basal state and was associated with enhanced insulin signaling and an increase in GLUT4 translocation to the plasma membrane. These data demonstrate an important role for Grb10 as a link between muscle growth and metabolism with therapeutic implications for diseases, such as muscle wasting and type 2 diabetes.
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Affiliation(s)
- Nancy Mokbel
- Diabetes and Obesity Research Program, The Garvan Institute of Medical Research, Sydney, New South Wales, Australia
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22
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Geillinger KE, Rathmann D, Köhrle J, Fiamoncini J, Daniel H, Kipp AP. Hepatic metabolite profiles in mice with a suboptimal selenium status. J Nutr Biochem 2014; 25:914-22. [DOI: 10.1016/j.jnutbio.2014.04.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2014] [Revised: 04/04/2014] [Accepted: 04/07/2014] [Indexed: 12/15/2022]
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Independent and combined effects of acute physiological hyperglycaemia and hyperinsulinaemia on metabolic gene expression in human skeletal muscle. Clin Sci (Lond) 2013; 124:675-84. [DOI: 10.1042/cs20120481] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Physiological hyperglycaemia and hyperinsulinaemia are strong modulators of gene expression, which underpins some of their well-known effects on insulin action and energy metabolism. The aim of the present study was to examine whether acute in vivo exposure of healthy humans to hyperinsulinaemia and hyperglycaemia have independent or additive effects on expression of key metabolic genes in skeletal muscle. On three randomized occasions, seven young subjects underwent a 4 h (i) hyperinsulinaemic (50 m-units·m−2·min−1) hyperglycaemic (10 mmol/l) clamp (HIHG), (ii) hyperglycaemic (10 mmol/l) euinsulinaemic (5 m-units·m−2·min−1) clamp (LIHG) and (iii) hyperinsulinaemic (50 m-units·m−2·min−1) euglycaemic (4.5 mmol/l) clamp (HING). Muscle biopsies were obtained before and after each clamp for the determination of expression of genes involved in energy metabolism, and phosphorylation of key insulin signalling proteins. Hyperinsulinaemia and hyperglycaemia exerted independent effects with similar direction of modulation on PI3KR1 (phosphatidylinositol 3-kinase, regulatory 1), LXRα (liver X receptor α), PDK4 (pyruvate dehydrogenase kinase 4) and FOXO1 (forkhead box O1A) and produced an additive effect on PI3KR1, the gene that encodes the p85α subunit of PI3K in human skeletal muscle. Acute hyperglycaemia itself altered the expression of genes involved in fatty acid transport and oxidation [fatty acid transporter (CD36), LCAD (long-chain acyl-CoA dehydrogenase) and FOXO1], and lipogenesis [LXRα, ChREBP (carbohydrate-responseelement-binding protein), ABCA1 (ATP-binding cassette transporter A1) and G6PD (glucose-6-phosphate dehydrogenase). Surperimposing hyperinsulinaemia on hyperglycaemia modulated a number of genes involved in insulin signalling, glucose metabolism and intracellular lipid accumulation and exerted an additive effect on PI3KR1. These may be early molecular events that precede the development of glucolipotoxicity and insulin resistance normally associated with more prolonged periods of hyperglycaemia and hyperinsulinaemia.
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Solomon TPJ, Knudsen SH, Karstoft K, Winding K, Holst JJ, Pedersen BK. Examining the effects of hyperglycemia on pancreatic endocrine function in humans: evidence for in vivo glucotoxicity. J Clin Endocrinol Metab 2012; 97:4682-91. [PMID: 23043193 DOI: 10.1210/jc.2012-2097] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
CONTEXT Investigating the impact of hyperglycemia on pancreatic endocrine function promotes our understanding of the pathophysiology of hyperglycemia-related disease. OBJECTIVE The objective of the study was to test the hypothesis that experimental hyperglycemia impairs insulin and glucagon secretion. DESIGN A randomized, crossover in healthy controls, compared with type 2 diabetic patients. SETTING The study was conducted at a university hospital. PARTICIPANTS Normal glucose-tolerant subjects (n = 10) and patients with type 2 diabetes (n = 10), individually matched by age, sex, and body mass index. INTERVENTIONS Normal glucose-tolerant subjects underwent 24 h of experimental hyperglycemia (+5.4 mm above basal). Subjects with type 2 diabetes did not undergo an intervention. MAIN OUTCOME MEASURES Insulin secretion, glucagon secretion, insulin sensitivity, disposition index, and endogenous glucose production (via [6,6-(2)H(2)]glucose infusion) were measured during hyperglycemic clamps combined with infusion of glucagon-like peptide (GLP)-1(7-36) (0.5 pmol/kg · min) and injection of arginine (5 g). RESULTS Insulin secretion was correlated with glucagon suppression in subjects with normal glucose tolerance only. Individuals with type 2 diabetes had lower insulin sensitivity (-33 ± 11%) and insulin secretory responses to glucose, GLP-1, and arginine (-40 ± 11, -58 ± 7, and -36 ± 13%, respectively) and higher plasma glucagon and endogenous glucose production compared with normal glucose-tolerant subjects (all P < 0.05). After 24 h of experimental hyperglycemia, insulin sensitivity (-29 ± 10%), disposition index (-24 ± 16%), and GLP-1- (-19 ± 7%) and arginine-stimulated (-15 ± 10%) insulin secretion were decreased in normal glucose-tolerant subjects (all P < 0.05). However, plasma glucagon responses were not affected. Furthermore, experimental hyperglycemia abolished the correlation between insulin secretion and glucagon suppression. CONCLUSIONS Experimental hyperglycemia impaired pancreatic β-cell function but did not acutely impair α-cell glucagon secretion in normal glucose-tolerant subjects.
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Affiliation(s)
- Thomas P J Solomon
- The Centre of Inflammation and Metabolism, Department of Infectious Diseases, Rigshospitalet, Copenhagen 2100, Denmark.
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Boden MJ, Brandon AE, Tid-Ang JD, Preston E, Wilks D, Stuart E, Cleasby ME, Turner N, Cooney GJ, Kraegen EW. Overexpression of manganese superoxide dismutase ameliorates high-fat diet-induced insulin resistance in rat skeletal muscle. Am J Physiol Endocrinol Metab 2012; 303:E798-805. [PMID: 22829583 PMCID: PMC3468429 DOI: 10.1152/ajpendo.00577.2011] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Elevated mitochondrial reactive oxygen species have been suggested to play a causative role in some forms of muscle insulin resistance. However, the extent of their involvement in the development of diet-induced insulin resistance remains unclear. To investigate, manganese superoxide dismutase (MnSOD), a key mitochondrial-specific enzyme with antioxidant modality, was overexpressed, and the effect on in vivo muscle insulin resistance induced by a high-fat (HF) diet in rats was evaluated. Male Wistar rats were maintained on chow or HF diet. After 3 wk, in vivo electroporation (IVE) of MnSOD expression and empty vectors was undertaken in right and left tibialis cranialis (TC) muscles, respectively. After one more week, insulin action was evaluated using hyperinsulinemic euglycemic clamp, and tissues were subsequently analyzed for antioxidant enzyme capacity and markers of oxidative stress. MnSOD mRNA was overexpressed 4.5-fold, and protein levels were increased by 70%, with protein detected primarily in the mitochondrial fraction of muscle fibers. This was associated with elevated MnSOD and glutathione peroxidase activity, indicating that the overexpressed MnSOD was functionally active. The HF diet significantly reduced whole body and TC muscle insulin action, whereas overexpression of MnSOD in HF diet animals ameliorated this reduction in TC muscle glucose uptake by 50% (P < 0.05). Decreased protein carbonylation was seen in MnSOD overexpressing TC muscle in HF-treated animals (20% vs. contralateral control leg, P < 0.05), suggesting that this effect was mediated through an altered redox state. Thus interventions causing elevation of mitochondrial antioxidant activity may offer protection against diet-induced insulin resistance in skeletal muscle.
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Affiliation(s)
- Michael J Boden
- Diabetes and Obesity Program, Garvan Institute for Medical Research, Darlinghurst, NSW, Australia 2010
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Reznick J, Preston E, Wilks DL, Beale SM, Turner N, Cooney GJ. Altered feeding differentially regulates circadian rhythms and energy metabolism in liver and muscle of rats. Biochim Biophys Acta Mol Basis Dis 2012; 1832:228-38. [PMID: 22952003 DOI: 10.1016/j.bbadis.2012.08.010] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2012] [Revised: 08/12/2012] [Accepted: 08/15/2012] [Indexed: 12/24/2022]
Abstract
Energy metabolism follows a diurnal pattern responding to the light/dark cycle and food availability. This study investigated the impact of restricting feeding to the daylight hours and feeding a high fat diet on circadian clock (bmal1, dbp, tef and e4bp4) and metabolic (pepck, fas, ucp3, pdk4) gene expression and markers of energy metabolism in muscle and liver of rats. The results show that in chow-fed rats switched to daylight feeding, the peak diurnal expression of genes in liver was shifted by 6-12h while expression of these genes in muscle remained in a similar phase to rats feeding ad libitum. High fat feeding during the daylight hours had limited effect on clock gene expression in liver or muscle but shifted the peak expression of metabolic genes (pepck, fas) in liver by 6-12h. The differential effects of daylight feeding on gene and protein expression in muscle and liver were accompanied by an 8% reduction in whole body energy expenditure, a 20-30% increased glycogen content during the light phase in muscle of day-fed rats and increased adipose tissue deposition per gram food consumed. These data demonstrate that a mismatch of feeding and light/dark cycle disrupts tissue metabolism in muscle with significant consequences for whole body energy homeostasis.
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Affiliation(s)
- Jane Reznick
- Garvan Institute of Medical Research, Darlinghurst, Sydney, Australia
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Muoio DM, Noland RC, Kovalik JP, Seiler SE, Davies MN, DeBalsi KL, Ilkayeva OR, Stevens RD, Kheterpal I, Zhang J, Covington JD, Bajpeyi S, Ravussin E, Kraus W, Koves TR, Mynatt RL. Muscle-specific deletion of carnitine acetyltransferase compromises glucose tolerance and metabolic flexibility. Cell Metab 2012; 15:764-77. [PMID: 22560225 PMCID: PMC3348515 DOI: 10.1016/j.cmet.2012.04.005] [Citation(s) in RCA: 272] [Impact Index Per Article: 22.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/31/2011] [Revised: 11/18/2011] [Accepted: 04/09/2012] [Indexed: 02/04/2023]
Abstract
The concept of "metabolic inflexibility" was first introduced to describe the failure of insulin-resistant human subjects to appropriately adjust mitochondrial fuel selection in response to nutritional cues. This phenomenon has since gained increasing recognition as a core component of the metabolic syndrome, but the underlying mechanisms have remained elusive. Here, we identify an essential role for the mitochondrial matrix enzyme, carnitine acetyltransferase (CrAT), in regulating substrate switching and glucose tolerance. By converting acetyl-CoA to its membrane permeant acetylcarnitine ester, CrAT regulates mitochondrial and intracellular carbon trafficking. Studies in muscle-specific Crat knockout mice, primary human skeletal myocytes, and human subjects undergoing L-carnitine supplementation support a model wherein CrAT combats nutrient stress, promotes metabolic flexibility, and enhances insulin action by permitting mitochondrial efflux of excess acetyl moieties that otherwise inhibit key regulatory enzymes such as pyruvate dehydrogenase. These findings offer therapeutically relevant insights into the molecular basis of metabolic inflexibility.
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Affiliation(s)
- Deborah M Muoio
- Sarah W. Stedman Nutrition and Metabolism Center, Department of Medicine, Duke University, Durham, NC 27704, USA.
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Jensen J, Rustad PI, Kolnes AJ, Lai YC. The role of skeletal muscle glycogen breakdown for regulation of insulin sensitivity by exercise. Front Physiol 2011; 2:112. [PMID: 22232606 PMCID: PMC3248697 DOI: 10.3389/fphys.2011.00112] [Citation(s) in RCA: 219] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2011] [Accepted: 12/09/2011] [Indexed: 12/12/2022] Open
Abstract
Glycogen is the storage form of carbohydrates in mammals. In humans the majority of glycogen is stored in skeletal muscles (∼500 g) and the liver (∼100 g). Food is supplied in larger meals, but the blood glucose concentration has to be kept within narrow limits to survive and stay healthy. Therefore, the body has to cope with periods of excess carbohydrates and periods without supplementation. Healthy persons remove blood glucose rapidly when glucose is in excess, but insulin-stimulated glucose disposal is reduced in insulin resistant and type 2 diabetic subjects. During a hyperinsulinemic euglycemic clamp, 70-90% of glucose disposal will be stored as muscle glycogen in healthy subjects. The glycogen stores in skeletal muscles are limited because an efficient feedback-mediated inhibition of glycogen synthase prevents accumulation. De novo lipid synthesis can contribute to glucose disposal when glycogen stores are filled. Exercise physiologists normally consider glycogen's main function as energy substrate. Glycogen is the main energy substrate during exercise intensity above 70% of maximal oxygen uptake ([Formula: see text]) and fatigue develops when the glycogen stores are depleted in the active muscles. After exercise, the rate of glycogen synthesis is increased to replete glycogen stores, and blood glucose is the substrate. Indeed insulin-stimulated glucose uptake and glycogen synthesis is elevated after exercise, which, from an evolutional point of view, will favor glycogen repletion and preparation for new "fight or flight" events. In the modern society, the reduced glycogen stores in skeletal muscles after exercise allows carbohydrates to be stored as muscle glycogen and prevents that glucose is channeled to de novo lipid synthesis, which over time will causes ectopic fat accumulation and insulin resistance. The reduction of skeletal muscle glycogen after exercise allows a healthy storage of carbohydrates after meals and prevents development of type 2 diabetes.
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Affiliation(s)
- Jørgen Jensen
- Department of Physical Performance, Norwegian School of Sport Sciences Oslo, Norway
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Kleinert M, Liao YH, Nelson JL, Bernard JR, Wang W, Ivy JL. An amino acid mixture enhances insulin-stimulated glucose uptake in isolated rat epitrochlearis muscle. J Appl Physiol (1985) 2011; 111:163-9. [PMID: 21527668 DOI: 10.1152/japplphysiol.01368.2010] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Protein and certain amino acids (AA) have been found to lower blood glucose. Although these glucose-lowering AA are important modulators of skeletal muscle metabolism, their impact on muscle glucose uptake remains unclear. We therefore examined how an AA mixture consisting of 2 mM isoleucine, 0.012 mM cysteine, 0.006 mM methionine, 0.0016 mM valine, and 0.014 mM leucine impacts skeletal muscle glucose uptake in the absence or presence of a submaximal (sINS) or maximal insulin (mINS) concentration. The AA mixture, sINS, and mINS significantly increased 2-[(3)H]deoxyglucose (2-DG) uptake by 63, 79, and 298% above basal, respectively. When the AA mixture was combined with sINS and mINS, 2-DG uptake was further increased significantly by 26% (P = 0.028) and 14% (P = 0.032), respectively. Western blotting analysis revealed that the AA mixture increased basal and sINS Akt substrate of 160 kDa (AS160) phosphorylation, while AA mixture did not change phosphorylation of Akt or mammalian target of rapamycin (mTOR) under these conditions. Interestingly, addition of the AA mixture to mINS increased phosphorylation of mTOR, Akt as well as AS160, compared with mINS alone. These data suggest that certain AA increase glucose uptake in the absence of insulin and augment insulin-stimulated glucose uptake in an additive manner. Furthermore, these effects appear to be mediated via a pathway that is independent from the canonical insulin cascade and therefore may prove effective as an alternative therapeutic treatment for insulin resistance.
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Affiliation(s)
- Maximilian Kleinert
- Department of Kinesiology and Health Education, University of Texas at Austin, Austin, Texas 78712, USA
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Brandon AE, Hoy AJ, Wright LE, Turner N, Hegarty BD, Iseli TJ, Julia Xu X, Cooney GJ, Saha AK, Ruderman NB, Kraegen EW. The evolution of insulin resistance in muscle of the glucose infused rat. Arch Biochem Biophys 2011; 509:133-41. [PMID: 21420928 DOI: 10.1016/j.abb.2011.03.008] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2011] [Revised: 03/14/2011] [Accepted: 03/15/2011] [Indexed: 11/17/2022]
Abstract
Glucose infusion into rats causes skeletal muscle insulin resistance that initially occurs without changes in insulin signaling. The aim of the current study was to prolong glucose infusion and evaluate other events associated with the transition to muscle insulin resistance. Hyperglycemia was produced in rats by glucose infusion for 3, 5 and 8 h. The rate of infusion required to maintain hyperglycemia was reduced at 5 and 8 h. Glucose uptake into red quadriceps (RQ) and its incorporation into glycogen decreased between 3 and 5 h, further decreasing at 8 h. The earliest observed change in RQ was decreased AMPKα2 activity associated with large increases in muscle glycogen content at 3 h. Activation of the mTOR pathway occurred at 5 h. Akt phosphorylation (Ser(473)) was decreased at 8 h compared to 3 and 5, although no decrease in phosphorylation of downstream GSK-3β (Ser(9)) and AS160 (Thr(642)) was observed. White quadriceps showed a similar but delayed pattern, with insulin resistance developing by 8 h and decreased AMPKα2 activity at 5 h. These results indicate that, in the presence of a nutrient overload, alterations in muscle insulin signaling occur, but after insulin resistance develops and appropriate changes in energy/nutrient sensing pathways occur.
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Affiliation(s)
- Amanda E Brandon
- Diabetes and Obesity Program, Garvan Institute of Medical Research, Darlinghurst, NSW 2010, Australia.
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Høeg LD, Sjøberg KA, Jeppesen J, Jensen TE, Frøsig C, Birk JB, Bisiani B, Hiscock N, Pilegaard H, Wojtaszewski JF, Richter EA, Kiens B. Lipid-induced insulin resistance affects women less than men and is not accompanied by inflammation or impaired proximal insulin signaling. Diabetes 2011; 60:64-73. [PMID: 20956497 PMCID: PMC3012198 DOI: 10.2337/db10-0698] [Citation(s) in RCA: 98] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
OBJECTIVE We have previously shown that overnight fasted women have higher insulin-stimulated whole body and leg glucose uptake despite a higher intramyocellular triacylglycerol concentration than men. Women also express higher muscle mRNA levels of proteins related to lipid metabolism than men. We therefore hypothesized that women would be less prone to lipid-induced insulin resistance. RESEARCH DESIGN AND METHODS Insulin sensitivity of whole-body and leg glucose disposal was studied in 16 young well-matched healthy men and women infused with intralipid or saline for 7 h. Muscle biopsies were obtained before and during a euglycemic-hyperinsulinemic clamp (1.42 mU · kg⁻¹ · min⁻¹). RESULTS Intralipid infusion reduced whole-body glucose infusion rate by 26% in women and 38% in men (P < 0.05), and insulin-stimulated leg glucose uptake was reduced significantly less in women (45%) than men (60%) after intralipid infusion. Hepatic glucose production was decreased during the clamp similarly in women and men irrespective of intralipid infusion. Intralipid did not impair insulin or AMPK signaling in muscle and subcutaneous fat, did not cause accumulation of muscle lipid intermediates, and did not impair insulin-stimulated glycogen synthase activity in muscle or increase plasma concentrations of inflammatory cytokines. In vitro glucose transport in giant sarcolemmal vesicles was not decreased by acute exposure to fatty acids. Leg lactate release was increased and respiratory exchange ratio was decreased by intralipid. CONCLUSIONS Intralipid infusion causes less insulin resistance of muscle glucose uptake in women than in men. This insulin resistance is not due to decreased canonical insulin signaling, accumulation of lipid intermediates, inflammation, or direct inhibition of GLUT activity. Rather, a higher leg lactate release and lower glucose oxidation with intralipid infusion may suggest a metabolic feedback regulation of glucose metabolism.
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Affiliation(s)
- Louise D. Høeg
- Copenhagen Muscle Research Centre, Molecular Physiology Group, Section of Human Physiology, Department of Exercise and Sport Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Kim A. Sjøberg
- Copenhagen Muscle Research Centre, Molecular Physiology Group, Section of Human Physiology, Department of Exercise and Sport Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Jacob Jeppesen
- Copenhagen Muscle Research Centre, Molecular Physiology Group, Section of Human Physiology, Department of Exercise and Sport Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Thomas E. Jensen
- Copenhagen Muscle Research Centre, Molecular Physiology Group, Section of Human Physiology, Department of Exercise and Sport Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Christian Frøsig
- Copenhagen Muscle Research Centre, Molecular Physiology Group, Section of Human Physiology, Department of Exercise and Sport Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Jesper B. Birk
- Copenhagen Muscle Research Centre, Molecular Physiology Group, Section of Human Physiology, Department of Exercise and Sport Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Bruno Bisiani
- Copenhagen Muscle Research Centre, Molecular Physiology Group, Section of Human Physiology, Department of Exercise and Sport Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Natalie Hiscock
- Unilever Discover, Colworth Science Park, Sharnbrook, Bedfordshire, U.K
| | - Henriette Pilegaard
- Copenhagen Muscle Research Centre, Department of Molecular Biology, University of Copenhagen, and the Centre of Inflammation and Metabolism, Copenhagen, Denmark
| | - Jørgen F.P. Wojtaszewski
- Copenhagen Muscle Research Centre, Molecular Physiology Group, Section of Human Physiology, Department of Exercise and Sport Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Erik A. Richter
- Copenhagen Muscle Research Centre, Molecular Physiology Group, Section of Human Physiology, Department of Exercise and Sport Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Bente Kiens
- Copenhagen Muscle Research Centre, Molecular Physiology Group, Section of Human Physiology, Department of Exercise and Sport Sciences, University of Copenhagen, Copenhagen, Denmark
- Corresponding author: Bente Kiens,
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Acute or chronic upregulation of mitochondrial fatty acid oxidation has no net effect on whole-body energy expenditure or adiposity. Cell Metab 2010; 11:70-6. [PMID: 20074529 PMCID: PMC2824926 DOI: 10.1016/j.cmet.2009.11.008] [Citation(s) in RCA: 126] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/22/2009] [Revised: 09/28/2009] [Accepted: 11/23/2009] [Indexed: 01/06/2023]
Abstract
Activation of AMP-activated protein kinase (AMPK) is thought to convey many of the beneficial effects of exercise via its inhibitory effect on acetyl-CoA carboxylase 2 (ACC2) and promotion of fatty acid oxidation. Hence, AMPK and ACC have become major drug targets for weight loss and improved insulin action. However, it remains unclear whether or how activation of the fatty acid oxidation pathway without a concomitant increase in energy expenditure could be beneficial. Here, we have used either pharmacological (administration of the AMPK agonist 5(') aminoimidazole-4-carboxamide-riboside) or genetic means (mutation of the ACC2 gene in mice) to manipulate fatty acid oxidation to determine whether this is sufficient to promote leanness. Both of these strategies increased whole-body fatty acid oxidation without altering energy expenditure or adiposity. We conclude that negative energy balance is a prerequisite for weight reduction, and increased fatty acid oxidation per se has little, if any, effect to reduce adiposity.
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Alkhateeb H, Chabowski A, Glatz JFC, Gurd B, Luiken JJFP, Bonen A. Restoring AS160 phosphorylation rescues skeletal muscle insulin resistance and fatty acid oxidation while not reducing intramuscular lipids. Am J Physiol Endocrinol Metab 2009; 297:E1056-66. [PMID: 19724017 DOI: 10.1152/ajpendo.90908.2008] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
We examined whether AICAR or leptin rapidly rescued skeletal muscle insulin resistance via increased palmitate oxidation, reductions in intramuscular lipids, and/or restoration of insulin-stimulated AS60 phosphorylation. Incubation with palmitate (2 mM, 0-18 h) induced insulin resistance in soleus muscle. From 12-18 h, palmitate was removed or AICAR or leptin was provided while 2 mM palmitate was maintained. Palmitate oxidation, intramuscular triacylglycerol, diacylglycerol, ceramide, AMPK phosphorylation, basal and insulin-stimulated glucose transport, plasmalemmal GLUT4, and Akt and AS160 phosphorylation were examined at 0, 6, 12, and 18 h. Palmitate treatment (12 h) increased intramuscular lipids (triacylglycerol +54%, diacylglycerol +11%, total ceramide +18%, C16:0 ceramide +60%) and AMPK phosphorylation (+118%), whereas it reduced fatty acid oxidation (-60%) and insulin-stimulated glucose transport (-70%), GLUT4 translocation (-50%), and AS160 phosphorylation (-40%). Palmitate removal did not rescue insulin resistance or associated parameters. The AICAR and leptin treatments did not consistently reduce intramuscular lipids, but they did rescue palmitate oxidation and insulin-stimulated glucose transport, GLUT4 translocation, and AS160 phosphorylation. Increased AMPK phosphorylation was associated with these improvements only when AICAR and leptin were present. Hence, across all experiments, AMPK phosphorylation did not correlate with any parameters. In contrast, palmitate oxidation and insulin-stimulated AS160 phosphorylation were highly correlated (r = 0.83). We speculate that AICAR and leptin activate both of these processes concomitantly, involving activation of unknown kinases in addition to AMPK. In conclusion, despite the maintenance of high concentrations of palmitate (2 mM), as well as increased concentrations of intramuscular lipids (triacylglycerol, diacylglycerol, and ceramide), the rapid AICAR- and leptin-mediated rescue of palmitate-induced insulin resistance is attributable to the restoration of insulin-stimulated AS160 phosphorylation and GLUT4 translocation.
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Affiliation(s)
- Hakam Alkhateeb
- Dept. of Human Health and Nutritional Sciences, Univ. of Guelph, Guelph, ON, N1G 2W1, Canada
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Lai YC, Lin FC, Jensen J. Glycogen content regulates insulin- but not contraction-mediated glycogen synthase activation in the rat slow-twitch soleus muscles. Acta Physiol (Oxf) 2009; 197:139-50. [PMID: 19432592 DOI: 10.1111/j.1748-1716.2009.01998.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
AIM The aim of this study was to investigate the effect of glycogen content on glycogen synthase (GS) activation and phosphorylation in the slow-twitch soleus muscles after contraction, during insulin stimulation and when these two stimuli were combined. METHODS Glycogen content was manipulated in vivo with 24 h fasting and fasting followed by 24 h refeeding. Soleus strips were electrically stimulated for 30 min in vitro, and GS activation and phosphorylation were investigated after an additional 30 min incubation with or without insulin. RESULTS Fasting reduced glycogen content in soleus muscle by 40% and refeeding enhanced by 40%, compared to rats with free access to chow. Insulin-stimulated GS fractional activity was inversely correlated with glycogen content (R = -0.95, P < 0.001, n = 24) and rate of glycogen synthesis was also inversely correlated with glycogen content (R = -0.70, P < 0.001, n = 36). After contraction, GS fractional activity was increased to similar levels in muscles with low, normal and high glycogen content; rate of glycogen synthesis after contraction was also similar. After contraction, insulin additively increased GS activation at all glycogen contents. Group means of GS fractional activity was inversely correlated with GS Ser(641) (R = -0.93, P < 0.001) and Ser(645,649,653,657) (R = -0.85, P < 0.001) phosphorylation, but not with Ser(7) phosphorylation. CONCLUSION Glycogen content regulates insulin- but not contraction-stimulated GS activation and glycogen synthesis in soleus muscles. Furthermore, phosphorylation of GS Ser(641) and Ser(645,649,653,657) seems to regulate GS activity in soleus.
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Affiliation(s)
- Y-C Lai
- Department of Physiology, National Institute of Occupational Health, Oslo, Norway
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Winnick JJ, An Z, Moore MC, Ramnanan CJ, Farmer B, Shiota M, Cherrington AD. A physiological increase in the hepatic glycogen level does not affect the response of net hepatic glucose uptake to insulin. Am J Physiol Endocrinol Metab 2009; 297:E358-66. [PMID: 19470836 PMCID: PMC2724107 DOI: 10.1152/ajpendo.00043.2009] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
To determine the effect of an acute increase in hepatic glycogen on net hepatic glucose uptake (NHGU) and disposition in response to insulin in vivo, studies were performed on two groups of dogs fasted 18 h. During the first 4 h of the study, somatostatin was infused peripherally, while insulin and glucagon were replaced intraportally in basal amounts. Hyperglycemia was brought about by glucose infusion, and either saline (n = 7) or fructose (n = 7; to stimulate NHGU and glycogen deposition) was infused intraportally. A 2-h control period then followed, during which the portal fructose and saline infusions were stopped, allowing NHGU and glycogen deposition in the fructose-infused animals to return to rates similar to those of the animals that received the saline infusion. This was followed by a 2-h experimental period, during which hyperglycemia was continued but insulin infusion was increased fourfold in both groups. During the initial 4-h glycogen loading period, NHGU averaged 1.18 +/- 0.27 and 5.55 +/- 0.53 mg x kg(-1) x min(-1) and glycogen synthesis averaged 0.72 +/- 0.24 and 3.98 +/- 0.57 mg x kg(-1) x min(-1) in the saline and fructose groups, respectively (P < 0.05). During the 2-h hyperinsulinemic period, NHGU rose from 1.5 +/- 0.4 and 0.9 +/- 0.2 to 3.1 +/- 0.6 and 2.5 +/- 0.5 mg x kg(-1) x min(-1) in the saline and fructose groups, respectively, a change of 1.6 mg x kg(-1) x min(-1) in both groups despite a significantly greater liver glycogen level in the fructose-infused group. Likewise, the metabolic fate of the extracted glucose (glycogen, lactate, or carbon dioxide) was not different between groups. These data indicate that an acute physiological increase in the hepatic glycogen content does not alter liver glucose uptake and storage under hyperglycemic/hyperinsulinemic conditions in the dog.
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Affiliation(s)
- Jason J Winnick
- Department of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, Tennessee 37232-6015, USA.
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Hoy AJ, Brandon AE, Turner N, Watt MJ, Bruce CR, Cooney GJ, Kraegen EW. Lipid and insulin infusion-induced skeletal muscle insulin resistance is likely due to metabolic feedback and not changes in IRS-1, Akt, or AS160 phosphorylation. Am J Physiol Endocrinol Metab 2009; 297:E67-75. [PMID: 19366875 PMCID: PMC2711668 DOI: 10.1152/ajpendo.90945.2008] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Type 2 diabetes is characterized by hyperlipidemia, hyperinsulinemia, and insulin resistance. The aim of this study was to investigate whether acute hyperlipidemia-induced insulin resistance in the presence of hyperinsulinemia was due to defective insulin signaling. Hyperinsulinemia (approximately 300 mU/l) with hyperlipidemia or glycerol (control) was produced in cannulated male Wistar rats for 0.5, 1 h, 3 h, or 5 h. The glucose infusion rate required to maintain euglycemia was significantly reduced by 3 h with lipid infusion and was further reduced after 5 h of infusion, with no difference in plasma insulin levels, indicating development of insulin resistance. Consistent with this finding, in vivo skeletal muscle glucose uptake (31%, P < 0.05) and glycogen synthesis rate (38%, P < 0.02) were significantly reduced after 5 h compared with 3 h of lipid infusion. Despite the development of insulin resistance, there was no difference in the phosphorylation state of multiple insulin-signaling intermediates or muscle diacylglyceride and ceramide content over the same time course. However, there was an increase in cumulative exposure to long-chain acyl-CoA (70%) with lipid infusion. Interestingly, although muscle pyruvate dehydrogenase kinase 4 protein content was decreased in hyperinsulinemic glycerol-infused rats, this decrease was blunted in muscle from hyperinsulinemic lipid-infused rats. Decreased pyruvate dehydrogenase complex activity was also observed in lipid- and insulin-infused animals (43%). Overall, these results suggest that acute reductions in muscle glucose metabolism in rats with hyperlipidemia and hyperinsulinemia are more likely a result of substrate competition than a significant early defect in insulin action or signaling.
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Affiliation(s)
- Andrew J Hoy
- Diabetes and Obesity Research Program, Garvan Institute of Medical Research, Darlinghurst, University of New South Wales, Sydney, New South Wales, Australia.
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Brunner Y, Schvartz D, Priego-Capote F, Couté Y, Sanchez JC. Glucotoxicity and pancreatic proteomics. J Proteomics 2009; 71:576-91. [DOI: 10.1016/j.jprot.2008.10.002] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2008] [Revised: 09/29/2008] [Accepted: 10/18/2008] [Indexed: 02/02/2023]
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Baus D, Heermeier K, De Hoop M, Metz-Weidmann C, Gassenhuber J, Dittrich W, Welte S, Tennagels N. Identification of a novel AS160 splice variant that regulates GLUT4 translocation and glucose-uptake in rat muscle cells. Cell Signal 2008; 20:2237-46. [DOI: 10.1016/j.cellsig.2008.08.010] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2008] [Revised: 08/05/2008] [Accepted: 08/11/2008] [Indexed: 01/11/2023]
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Can MF, Yagci G, Dag B, Ozturk E, Gorgulu S, Simsek A, Tufan T. Preoperative administration of oral carbohydrate-rich solutions: Comparison of glucometabolic responses and tolerability between patients with and without insulin resistance. Nutrition 2008; 25:72-7. [PMID: 18849145 DOI: 10.1016/j.nut.2008.07.021] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2008] [Revised: 06/24/2008] [Accepted: 07/07/2008] [Indexed: 12/01/2022]
Abstract
OBJECTIVE Preoperative carbohydrate loading with clear fluids is thought to reduce surgery-related insulin resistance (IR). However, IR per se is already present in some patients scheduled for elective surgery. Data on the safety of preoperative oral carbohydrate loading in patients with IR undergoing surgery is lacking. We aimed to evaluate the effects of preoperative carbohydrate loading on the glucometabolic state and gastric content of patients with and without IR. METHODS Thirty-four non-diabetics received 800 mL of a special carbohydrate-containing drink on the evening before the operation and then 400 mL 2 h before surgery. Blood samples for glucose, insulin, and cortisol levels were taken immediately before the second dose, at 40 and 90 min after intake of the drink, and at the onset of surgery. Patients with a homeostasis model assessment IR score >2.5 were considered to have IR. The differences between patients with and without IR were then evaluated. RESULTS Eight of the 34 patients had IR and the remaining 26 did not. Glucose levels in the IR group were higher than those in the non-IR group, but the differences did not reach significance. The initially elevated insulin concentrations then tended to decrease to the corresponding levels detected in the non-IR group. The cortisol concentrations were similar in both groups. CONCLUSION Patients with IR receiving a carbohydrate-rich drink before surgery appear not to be affected adversely by the beverage. Furthermore, they also obtain the probable beneficial effects related to these drinks and, like patients without IR, can undergo surgery safely.
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Affiliation(s)
- Mehmet Fatih Can
- Gulhane Military Medical Academy, Department of Surgery, Surgical Nutrition Audit Team, Etlik, Ankara, Turkey
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Abstract
PURPOSE OF REVIEW Acute exposure to fatty acids causes insulin resistance in muscle, and excess dietary lipid and obesity are also strongly associated with muscle insulin resistance. Relevant mechanisms, however, are still not fully elucidated. Here we examine the latest evidence as to why lipids might accumulate in muscle and the possible mechanisms for lipid-induced insulin resistance. RECENT FINDINGS Muscle lipid metabolites such as long chain fatty acid coenzyme As, diacylglycerol and ceramides may impair insulin signalling directly. Crosstalk between inflammatory signalling pathways and insulin signalling pathways, mitochondrial dysfunction and oxidative stress have also been put forward as major contributors to the development or maintenance of lipid-induced insulin resistance in muscle. Several animal models with gene deletions in pathways of fatty acid synthesis and storage also show increased metabolic rate, reduced intramuscular lipid storage and improved insulin action when challenged with a high lipid load. SUMMARY Studies in genetic and dietary obese animal models, genetically modified animals and humans with obesity or type 2 diabetes suggest plausible mechanisms for effects of fatty acids, lipid metabolites, inflammatory pathways and mitochondrial dysfunction on insulin action in muscle. Many of these mechanisms, however, have been demonstrated in situations in which lipid accumulation (obesity) already exists. Whether the initial events leading to muscle insulin resistance are direct effects of fatty acids in muscle or are secondary to lipid accumulation in adipose tissue or liver remains to be clarified.
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Affiliation(s)
- Edward W Kraegen
- Diabetes and Obesity Program, Garvan Institute of Medical Research, Sydney, Australia.
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Sun C, Zhou J. Trichostatin A improves insulin stimulated glucose utilization and insulin signaling transduction through the repression of HDAC2. Biochem Pharmacol 2008; 76:120-7. [PMID: 18495085 DOI: 10.1016/j.bcp.2008.04.004] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2008] [Revised: 04/08/2008] [Accepted: 04/10/2008] [Indexed: 01/22/2023]
Abstract
Previous study showed that Trichostatin A (TSA) could improve insulin receptor substrate 1 (IRS-1) phosphorylation at tyrosine in response to insulin evocation. However, the effects of TSA on insulin stimulated glucose utilization and insulin signaling transduction are still poorly understood. Here we showed that TSA significantly enhanced insulin stimulated glucose uptake, glycogen synthesis and glycogen synthase activities in C2C12 myotubes. In addition, the insulin stimulated phosphorylations in insulin receptor, Akt and GSK3beta were remarkably increased in the TSA-treated cells. These improving effects of TSA were probably due to HDAC2 inhibition, since the enhanced expression of HDAC2 could abolish the TSA-induced improvement in the insulin signaling transduction. Moreover, HDAC2 knockdown as well as TSA treatment also improved insulin stimulated glycogen synthesis. Most importantly, no additional effect of TSA on insulin stimulated glycogen synthesis was observed in the HDAC2 downregulated cells. These data suggest that HDAC2 should be an important potential target for regulating insulin sensitivity.
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Affiliation(s)
- Cheng Sun
- MOE Key Laboratory of Model Animal for Disease Study, Model Animal Research Center, Nanjing University, 12 Xuefu Road, Pukou District, Nanjing 210061, China.
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