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Rauchová H, Neprašová B, Maletínská L, Kuneš J. Glutathione Levels and Lipid Oxidative Damage in Selected Organs of Obese Koletsky and Lean Spontaneously Hypertensive Rats. Physiol Res 2024; 73:481-484. [PMID: 39027962 PMCID: PMC11299778 DOI: 10.33549/physiolres.935319] [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: 01/10/2024] [Accepted: 01/31/2024] [Indexed: 07/27/2024] Open
Abstract
Koletsky rats, the genetically obese strain of spontaneously hypertensive rats (SHROB), are the well-accepted animal model of human metabolic syndrome. They are characterized by early onset obesity, spontaneous hypertension, hyperinsulinemia, hyperlipidemia, proteinuria and shortened life-span. One of the factors in the pathogenesis of metabolic syndrome is oxidative stress. The aim of the present study was to compare two parameters related to oxidative stress: the levels of the main intracellular antioxidant, reduced glutathione as well as the indirect indicator of lipid peroxidation damage, thiobarbituric acid-reactive substances (TBARS) in heart, renal cortex and medulla and liver in male lean spontaneously hypertensive rats (SHR) and obese Koletsky rats. We did not find any significant differences in these markers in heart and kidneys. However, we found significantly lower glutathione level in Koletsky rat liver compared with SHR (5.03+/-0.23 vs. 5.83+/-0.14 µmol/g tissue, respectively). On the contrary, we observed significantly higher TBARS levels in Koletsky rat liver compared with SHR (28.56+/-2.15 vs. 21.83+/-1.60 nmol/mg protein, respectively). We conclude that the liver is the most sensitive tissue to oxidative damage with the significantly decreased concentration of glutathione and the significantly increased concentration of TBARS in obese Koletsky rats in comparison with lean control SHR.
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Affiliation(s)
- H Rauchová
- Laboratory of Experimental Hypertension, Institute of Physiology of the Czech Academy of Sciences, Prague 4, Czech Republic.
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AÇIKEL ELMAS M, BİNGÖL ÖZAKPINAR Ö, KOLGAZİ M, ŞENER G, ERCAN F. Morphological and Biochemical Investigation of the Healing Effects of Exercise on High Fat Diet Induced Kidney and Bladder Damage. CLINICAL AND EXPERIMENTAL HEALTH SCIENCES 2022. [DOI: 10.33808/clinexphealthsci.1027516] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Objective: The aim of this study was to assess the preventive effects of swimming exercise on kidney and bladder damage caused by a high-fat diet (HFD) using morphological and biochemical measures.
Methods: Sprague Dawley rats were fed either standard chow (CONT, 6% fat) or HFD (45% fat) for 18 weeks, these rats were divided into two subgroups at the last 6 weeks of the experiment. The exercise groups (CONT+EXC, HFD+EXC) were trained daily swimming sessions (1 h per day for 5 days/week) during the last 6 weeks. Kidney and bladder samples were prepared for light and electron microscopic examination at the end of experiment. Malondialdehyde, glutathione, interleukin-6, and tumor necrosis factor-α were measured by biochemically.Results: Regular morphology of renal cortex and urinary bladder mucosa were observed in the CONT and CONT+EXC groups. Degenerated renal corpuscles and proximal tubules in kidney and degenerated urothelium with leaky tight junctions and increase of mast cells in bladder mucosa were observed in the HFD group. Ameliorated renal cortex and bladder mucosa were observed in the HFD+EXC group. Moreover, malondialdehyde, glutathione, interleukin-6 and tumor necrosis factor- α levels were compatible with histological findings.
Conclusion: HFD induced kidney and bladder damage may have linked to increased oxidative damage. It was observed that histological damage and altered oxidative stress parameters were reversed with swimming exercise, and it is thought that moderate swimming exercise may have a role in the regulation of oxidative stress.
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Affiliation(s)
| | | | | | - Göksel ŞENER
- FENERBAHÇE ÜNİVERSİTESİ, SAĞLIK HİZMETLERİ MESLEK YÜKSEKOKULU
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Mráziková L, Neprašová B, Mengr A, Popelová A, Strnadová V, Holá L, Železná B, Kuneš J, Maletínská L. Lipidized Prolactin-Releasing Peptide as a New Potential Tool to Treat Obesity and Type 2 Diabetes Mellitus: Preclinical Studies in Rodent Models. Front Pharmacol 2021; 12:779962. [PMID: 34867411 PMCID: PMC8637538 DOI: 10.3389/fphar.2021.779962] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Accepted: 11/01/2021] [Indexed: 11/13/2022] Open
Abstract
Obesity and type 2 diabetes mellitus (T2DM) are preconditions for the development of metabolic syndrome, which is reaching pandemic levels worldwide, but there are still only a few anti-obesity drugs available. One of the promising tools for the treatment of obesity and related metabolic complications is anorexigenic peptides, such as prolactin-releasing peptide (PrRP). PrRP is a centrally acting neuropeptide involved in food intake and body weight (BW) regulation. In its natural form, it has limitations for peripheral administration; thus, we designed analogs of PrRP lipidized at the N-terminal region that showed high binding affinities, increased stability and central anorexigenic effects after peripheral administration. In this review, we summarize the preclinical results of our chronic studies on the pharmacological role of the two most potent palmitoylated PrRP31 analogs in various mouse and rat models of obesity, glucose intolerance, and insulin resistance. We used mice and rats with diet-induced obesity fed a high-fat diet, which is considered to simulate the most common form of human obesity, or rodent models with leptin deficiency or disrupted leptin signaling in which long-term food intake regulation by leptin is distorted. The rodent models described in this review are models of metabolic syndrome with different severities, such as obesity or morbid obesity, prediabetes or diabetes and hypertension. We found that the effects of palmitoylated PrRP31 on food intake and BW but not on glucose intolerance require intact leptin signaling. Thus, palmitoylated PrRP31 analogs have potential as therapeutics for obesity and related metabolic complications.
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Affiliation(s)
- Lucia Mráziková
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Prague, Czech
| | - Barbora Neprašová
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Prague, Czech.,Institute of Physiology, Czech Academy of Sciences, Prague, Czech
| | - Anna Mengr
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Prague, Czech
| | - Andrea Popelová
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Prague, Czech
| | - Veronika Strnadová
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Prague, Czech
| | - Lucie Holá
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Prague, Czech
| | - Blanka Železná
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Prague, Czech
| | - Jaroslav Kuneš
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Prague, Czech.,Institute of Physiology, Czech Academy of Sciences, Prague, Czech
| | - Lenka Maletínská
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Prague, Czech
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Saande CJ, Steffes MA, Webb JL, Valentine RJ, Rowling MJ, Schalinske KL. Whole Egg Consumption Impairs Insulin Sensitivity in a Rat Model of Obesity and Type 2 Diabetes. Curr Dev Nutr 2019; 3:nzz015. [PMID: 31008440 PMCID: PMC6462456 DOI: 10.1093/cdn/nzz015] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Revised: 02/20/2019] [Accepted: 03/06/2019] [Indexed: 01/21/2023] Open
Abstract
BACKGROUND The literature regarding the relation between egg consumption and type 2 diabetes (T2D) is inconsistent and there is limited evidence pertaining to the impact of egg consumption on measures of insulin sensitivity. OBJECTIVES The aim of this study was to investigate the effect of dietary whole egg on metabolic biomarkers of insulin resistance in T2D rats. METHODS Male Zucker diabetic fatty (ZDF) rats (n = 12; 6 wk of age) and age-matched lean controls (n = 12) were randomly assigned to be fed a casein- or whole egg-based diet. At week 5 of dietary treatment, an insulin tolerance test (ITT) was performed on all rats and blood glucose was measured by glucometer. After 7 wk of dietary treatment, rats were anesthetized and whole blood was collected via a tail vein bleed. Following sedation, the extensor digitorum longus muscle was removed before and after an intraperitoneal insulin injection, and insulin signaling in skeletal muscle was analyzed by Western blot. Serum glucose and insulin were analyzed by ELISA for calculation of the homeostatic model assessment of insulin resistance (HOMA-IR). RESULTS Mean ITT blood glucose over the course of 60 min was 32% higher in ZDF rats fed the whole egg-based diet than in ZDF rats fed the casein-based diet. Furthermore, whole egg consumption increased fasting blood glucose by 35% in ZDF rats. Insulin-stimulated phosphorylation of key proteins in the insulin signaling pathway did not differ in skeletal muscle of ZDF rats fed casein- and whole egg-based diets. In lean rats, no differences were observed in insulin tolerance, HOMA-IR and skeletal muscle insulin signaling, regardless of experimental dietary treatment. CONCLUSIONS These data suggest that whole body insulin sensitivity may be impaired by whole egg consumption in T2D rats, although no changes were observed in skeletal muscle insulin signaling that could explain this finding.
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Affiliation(s)
- Cassondra J Saande
- Department of Food Science and Human Nutrition, Iowa State University, Ames, IA 50011
- Interdepartmental Graduate Program in Nutritional Sciences, Iowa State University, Ames, IA 50011
| | - Megan A Steffes
- Department of Food Science and Human Nutrition, Iowa State University, Ames, IA 50011
| | - Joseph L Webb
- Department of Food Science and Human Nutrition, Iowa State University, Ames, IA 50011
- Interdepartmental Graduate Program in Nutritional Sciences, Iowa State University, Ames, IA 50011
| | - Rudy J Valentine
- Interdepartmental Graduate Program in Nutritional Sciences, Iowa State University, Ames, IA 50011
- Department of Kinesiology, Iowa State University, Ames, IA, 50011
| | - Matthew J Rowling
- Department of Food Science and Human Nutrition, Iowa State University, Ames, IA 50011
- Interdepartmental Graduate Program in Nutritional Sciences, Iowa State University, Ames, IA 50011
| | - Kevin L Schalinske
- Department of Food Science and Human Nutrition, Iowa State University, Ames, IA 50011
- Interdepartmental Graduate Program in Nutritional Sciences, Iowa State University, Ames, IA 50011
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Yang P, Liang Y, Luo Y, Li Z, Wen Y, Shen J, Li R, Zheng H, Gu HF, Xia N. Liraglutide ameliorates nonalcoholic fatty liver disease in diabetic mice via the IRS2/PI3K/Akt signaling pathway. Diabetes Metab Syndr Obes 2019; 12:1013-1021. [PMID: 31308717 PMCID: PMC6614831 DOI: 10.2147/dmso.s206867] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/26/2019] [Accepted: 04/16/2019] [Indexed: 12/15/2022] Open
Abstract
Purpose: High prevalence of nonalcoholic fatty liver disease (NAFLD) among patients with type 2 diabetes has implicated the role of hepatic insulin resistance (IR) in the diseases. To better understand the underlying mechanism, we have evaluated the pathophysiological effects of Liraglutide on NAFLD via the insulin signaling pathway. Patients and methods: A 2×2 factorial experiment was designed. High-fat diet (HFD)-induced NAFLD mice with diabetes were treated with Liraglutide for 10 weeks, while the control mice were saline-treated. Hepatic expressions of InsR, IGF-1R, IRS2, PI3K and Akt at mRNA and protein levels were analyzed with RT-PCR and Western blotting. Hematoxylin and eosin staining, Oil Red O staining and electron microscopy were used to visualize triglyceride accumulation in liver. Results: Liraglutide significantly decreased body weight, fasting blood glucose levels and HOMA-IR scores in HFD mice. Compared with the control mice fed with chow diet, hepatic expressions of InsR, IRS2, PI3K and Akt at both mRNA and protein levels in HFD mice were significantly reduced, but upregulated after Liraglutide treatment. Furthermore, Liraglutide treatment was found to improve hepatic steatosis. Conclusion: The current study thereby provides evidence that Liraglutide ameliorates NAFLD and improves hepatic steatosis mainly by upregulation of the IRS2/PI3K/Akt signaling mediators.
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Affiliation(s)
- Pijian Yang
- Department of Endocrinology and Metabolism, The First Affiliated Hospital of Guangxi Medical University, Nanning530021, People’s Republic of China
| | - Yuzhen Liang
- Department of Endocrinology and Metabolism, The Second Affiliated Hospital of Guangxi Medical University, Nanning530021, People’s Republic of China
| | - Yunchen Luo
- Department of Endocrinology and Metabolism, The Second Affiliated Hospital of Guangxi Medical University, Nanning530021, People’s Republic of China
| | - Zhengming Li
- Department of Endocrinology and Metabolism, The Second Affiliated Hospital of Guangxi Medical University, Nanning530021, People’s Republic of China
| | - Yumei Wen
- Department of Endocrinology and Metabolism, The First Affiliated Hospital of Guangxi Medical University, Nanning530021, People’s Republic of China
| | - Jing Shen
- Department of Endocrinology and Metabolism, The First Affiliated Hospital of Guangxi Medical University, Nanning530021, People’s Republic of China
| | - Ruwen Li
- Department of Endocrinology and Metabolism, The First Affiliated Hospital of Guangxi Medical University, Nanning530021, People’s Republic of China
| | - Hua Zheng
- Life Sciences Institute, Guangxi Medical University, Nanning530021, People’s Republic of China
| | - Harvest F Gu
- Center for Pathophysiology, School of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing210009People’s Republic of China
| | - Ning Xia
- Department of Endocrinology and Metabolism, The First Affiliated Hospital of Guangxi Medical University, Nanning530021, People’s Republic of China
- Correspondence: Ning XiaDepartment of Endocrinology and Metabolism, The First Affiliated Hospital of Guangxi Medical University, Nanning530021, People’s Republic of ChinaTel +86 771 280 2380Email
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McPherson KC, Shields CA, Poudel B, Fizer B, Pennington A, Szabo-Johnson A, Thompson WL, Cornelius DC, Williams JM. Impact of obesity as an independent risk factor for the development of renal injury: implications from rat models of obesity. Am J Physiol Renal Physiol 2018; 316:F316-F327. [PMID: 30539649 DOI: 10.1152/ajprenal.00162.2018] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Diabetes and hypertension are the major causes of chronic kidney disease (CKD). Epidemiological studies within the last few decades have revealed that obesity-associated renal disease is an emerging epidemic and that the increasing prevalence of obesity parallels the increased rate of CKD. This has led to the inclusion of obesity as an independent risk factor for CKD. A major complication when studying the relationship between obesity and renal injury is that cardiovascular and metabolic disorders that may result from obesity including hyperglycemia, hypertension, and dyslipidemia, or the cluster of these disorders [defined as the metabolic syndrome, (MetS)] also contribute to the development and progression of renal disease. The associations between hyperglycemia and hypertension with renal disease have been reported extensively in patients suffering from obesity. Currently, there are several obese rodent models (high-fat diet-induced obesity and leptin signaling dysfunction) that exhibit characteristics of MetS. However, the available obese rodent models currently have not been used to investigate the impact of obesity alone on the development of renal injury before hypertension and/or hyperglycemia. Therefore, the aim of this review is to describe the incidence and severity of renal disease in these rodent models of obesity and determine which models are suitable to study the independent effects obesity on the development and progression of renal disease.
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Affiliation(s)
- Kasi C McPherson
- Department of Pharmacology and Toxicology, University of Mississippi Medical Center, Jackson, Mississippi
| | - Corbin A Shields
- Department of Pharmacology and Toxicology, University of Mississippi Medical Center, Jackson, Mississippi
| | - Bibek Poudel
- Department of Pharmacology and Toxicology, University of Mississippi Medical Center, Jackson, Mississippi
| | - Brianca Fizer
- Department of Pharmacology and Toxicology, University of Mississippi Medical Center, Jackson, Mississippi
| | - Alyssa Pennington
- Department of Pharmacology and Toxicology, University of Mississippi Medical Center, Jackson, Mississippi
| | - Ashley Szabo-Johnson
- Department of Pharmacology and Toxicology, University of Mississippi Medical Center, Jackson, Mississippi
| | - Willie L Thompson
- Department of Pharmacology and Toxicology, University of Mississippi Medical Center, Jackson, Mississippi
| | - Denise C Cornelius
- Department of Pharmacology and Toxicology, University of Mississippi Medical Center, Jackson, Mississippi.,Department of Emergency Medicine, University of Mississippi Medical Center , Jackson, Mississippi
| | - Jan M Williams
- Department of Pharmacology and Toxicology, University of Mississippi Medical Center, Jackson, Mississippi
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Luo YH, Zhu M, Wang DG, Yang YS, Tan T, Zhu H, He JF. Yangxin Tongmai Formula ameliorates impaired glucose tolerance in children with Graves' disease through upregulation of the insulin receptor levels. Acta Pharmacol Sin 2018; 39:923-929. [PMID: 29168473 DOI: 10.1038/aps.2017.94] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2017] [Accepted: 06/17/2017] [Indexed: 12/15/2022] Open
Abstract
Graves' disease (GD) is the leading cause of hyperthyroidism, and the majority of GD patients eventually develop disorders of glucose handling, which further affects their quality of life. Yangxin Tongmai formula (YTF) is modified from a famous formula of traditional Chinese medicine for the treatment of cardiovascular diseases. In this study we investigated the potential effects of YTF in the treatment of pediatric GD patients with impaired glucose tolerance. Forty pediatric GD patients and 20 healthy children were recruited for this clinical study. Based on the glucose tolerance, the GD patients were divided into two groups: 20 patients displayed impaired glucose tolerance, while the other 20 patients displayed normal glucose tolerance. YTF was orally administered for 60 days. YTF administration significantly ameliorated the abnormal glucose tolerance and insulin sensitivity in the GD patients with impaired glucose tolerance. To determine the molecular mechanisms of this observation, the number of plasma insulin receptors was determined by ELISA. Before treatment, the fasting and postprandial levels of the insulin receptor were significantly lower in patients with impaired glucose tolerance compared with those in patients with normal glucose tolerance and healthy children. After YTF treatment, both the fasting and the postprandial circulating insulin receptor levels were upregulated, and close to those in healthy children. Therefore, YTF is a potential effective treatment to enhance glucose handling in GD children with impaired glucose tolerance.
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Kleinert M, Clemmensen C, Hofmann SM, Moore MC, Renner S, Woods SC, Huypens P, Beckers J, de Angelis MH, Schürmann A, Bakhti M, Klingenspor M, Heiman M, Cherrington AD, Ristow M, Lickert H, Wolf E, Havel PJ, Müller TD, Tschöp MH. Animal models of obesity and diabetes mellitus. Nat Rev Endocrinol 2018; 14:140-162. [PMID: 29348476 DOI: 10.1038/nrendo.2017.161] [Citation(s) in RCA: 521] [Impact Index Per Article: 86.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
More than one-third of the worldwide population is overweight or obese and therefore at risk of developing type 2 diabetes mellitus. In order to mitigate this pandemic, safer and more potent therapeutics are urgently required. This necessitates the continued use of animal models to discover, validate and optimize novel therapeutics for their safe use in humans. In order to improve the transition from bench to bedside, researchers must not only carefully select the appropriate model but also draw the right conclusions. In this Review, we consolidate the key information on the currently available animal models of obesity and diabetes and highlight the advantages, limitations and important caveats of each of these models.
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Affiliation(s)
- Maximilian Kleinert
- Institute for Diabetes and Obesity, Helmholtz Diabetes Center at Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Ingolstädter Landstr. 1, D-85764 Neuherberg, Germany
- Division of Metabolic Diseases, Department of Medicine, Technische Universität München, D-80333 Munich, Germany
- German Center for Diabetes Research (DZD), Ingolstädter Landstr. 1, D-85764 Neuherberg, Germany
- Section of Molecular Physiology, Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, DK-2200 Copenhagen, Denmark
| | - Christoffer Clemmensen
- Institute for Diabetes and Obesity, Helmholtz Diabetes Center at Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Ingolstädter Landstr. 1, D-85764 Neuherberg, Germany
- Division of Metabolic Diseases, Department of Medicine, Technische Universität München, D-80333 Munich, Germany
- German Center for Diabetes Research (DZD), Ingolstädter Landstr. 1, D-85764 Neuherberg, Germany
| | - Susanna M Hofmann
- German Center for Diabetes Research (DZD), Ingolstädter Landstr. 1, D-85764 Neuherberg, Germany
- Institute for Diabetes and Regeneration Research, Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Ingolstädter Landstr. 1, D-85764 Neuherberg, Germany
- Medizinische Klinik und Poliklinik IV, Klinikum der Ludwig-Maximilians-Universität München, Ziemssenstr. 1, D-80336 Munich, Germany
| | - Mary C Moore
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee 37212, USA
| | - Simone Renner
- German Center for Diabetes Research (DZD), Ingolstädter Landstr. 1, D-85764 Neuherberg, Germany
- Chair for Molecular Animal Breeding and Biotechnology, Gene Center, Ludwig-Maximilan University München, Feodor-Lynen-Str. 25, D-81377 Munich, Germany
| | - Stephen C Woods
- University of Cincinnati College of Medicine, Department of Psychiatry and Behavioral Neuroscience, Metabolic Diseases Institute, 2170 East Galbraith Road, Cincinnati, Ohio 45237, USA
| | - Peter Huypens
- German Center for Diabetes Research (DZD), Ingolstädter Landstr. 1, D-85764 Neuherberg, Germany
- Institute of Experimental Genetics, Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Ingolstädter Landstr. 1, D-85764 Neuherberg, Germany
| | - Johannes Beckers
- German Center for Diabetes Research (DZD), Ingolstädter Landstr. 1, D-85764 Neuherberg, Germany
- Institute of Experimental Genetics, Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Ingolstädter Landstr. 1, D-85764 Neuherberg, Germany
- Technische Universität München, Chair of Experimental Genetics, D-85354 Freising, Germany
| | - Martin Hrabe de Angelis
- German Center for Diabetes Research (DZD), Ingolstädter Landstr. 1, D-85764 Neuherberg, Germany
- Institute of Experimental Genetics, Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Ingolstädter Landstr. 1, D-85764 Neuherberg, Germany
- Technische Universität München, Chair of Experimental Genetics, D-85354 Freising, Germany
| | - Annette Schürmann
- German Center for Diabetes Research (DZD), Ingolstädter Landstr. 1, D-85764 Neuherberg, Germany
- Department of Experimental Diabetology, German Institute of Human Nutrition (DIfE), Arthur-Scheunert-Allee 114-116, D-14558 Nuthetal, Germany
| | - Mostafa Bakhti
- German Center for Diabetes Research (DZD), Ingolstädter Landstr. 1, D-85764 Neuherberg, Germany
- Institute for Diabetes and Regeneration Research, Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Ingolstädter Landstr. 1, D-85764 Neuherberg, Germany
- Institute of Stem Cell Research, Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Ingolstädter Landstr. 1, D-85764 Neuherberg, Germany
| | - Martin Klingenspor
- Chair of Molecular Nutritional Medicine, Technische Universität München, TUM School of Life Sciences Weihenstephan, Gregor-Mendel-Str. 2, D-85354 Freising, Germany
- Else Kröner-Fresenius Center for Nutritional Medicine, Technische Universität München, D-85354 Freising, Germany
- Institute for Food & Health, Technische Universität München, D-85354 Freising, Germany
| | - Mark Heiman
- MicroBiome Therapeutics, 1316 Jefferson Ave, New Orleans, Louisiana 70115, USA
| | - Alan D Cherrington
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee 37212, USA
| | - Michael Ristow
- Energy Metabolism Laboratory, Institute of Translational Medicine, Swiss Federal Institute of Technology (ETH) Zurich, CH-8603 Zurich-Schwerzenbach, Switzerland
| | - Heiko Lickert
- German Center for Diabetes Research (DZD), Ingolstädter Landstr. 1, D-85764 Neuherberg, Germany
- Institute for Diabetes and Regeneration Research, Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Ingolstädter Landstr. 1, D-85764 Neuherberg, Germany
- Institute of Stem Cell Research, Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Ingolstädter Landstr. 1, D-85764 Neuherberg, Germany
| | - Eckhard Wolf
- German Center for Diabetes Research (DZD), Ingolstädter Landstr. 1, D-85764 Neuherberg, Germany
- Chair for Molecular Animal Breeding and Biotechnology, Gene Center, Ludwig-Maximilan University München, Feodor-Lynen-Str. 25, D-81377 Munich, Germany
| | - Peter J Havel
- Department of Molecular Biosciences, School of Veterinary Medicine and Department of Nutrition, 3135 Meyer Hall, University of California, Davis, California 95616-5270, USA
| | - Timo D Müller
- Institute for Diabetes and Obesity, Helmholtz Diabetes Center at Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Ingolstädter Landstr. 1, D-85764 Neuherberg, Germany
- Division of Metabolic Diseases, Department of Medicine, Technische Universität München, D-80333 Munich, Germany
- German Center for Diabetes Research (DZD), Ingolstädter Landstr. 1, D-85764 Neuherberg, Germany
| | - Matthias H Tschöp
- Institute for Diabetes and Obesity, Helmholtz Diabetes Center at Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Ingolstädter Landstr. 1, D-85764 Neuherberg, Germany
- Division of Metabolic Diseases, Department of Medicine, Technische Universität München, D-80333 Munich, Germany
- German Center for Diabetes Research (DZD), Ingolstädter Landstr. 1, D-85764 Neuherberg, Germany
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Lipidized prolactin-releasing peptide improved glucose tolerance in metabolic syndrome: Koletsky and spontaneously hypertensive rat study. Nutr Diabetes 2018; 8:5. [PMID: 29339795 PMCID: PMC5851428 DOI: 10.1038/s41387-017-0015-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/23/2017] [Accepted: 11/01/2017] [Indexed: 12/21/2022] Open
Abstract
Background/Objectives Prolactin-releasing peptide (PrRP) has a potential to decrease food intake and ameliorate obesity, but is ineffective after peripheral administration. We have previously shown that our novel lipidized analogs PrRP enhances its stability in the circulation and enables its central effect after peripheral application. The purpose of this study was to explore if sub-chronic administration of novel PrRP analog palmitoylated in position 11 (palm11-PrRP31) to Koletsky-spontaneously hypertensive obese rats (SHROB) could lower body weight and glucose intolerance as well as other metabolic parameters. Subjects/Methods The SHROB rats (n = 16) were used for this study and age-matched hypertensive lean SHR littermates (n = 16) served as controls. Palm11-PrRP31 was administered intraperitoneally to SHR and SHROB (n = 8) at a dose of 5 mg/kg once-daily for 3 weeks. During the dosing period food intake and body weight were monitored. At the end of the experiment the oral glucose tolerance test was performed; plasma and tissue samples were collected. Thereafter, arterial blood pressure was measured. Results At the end of the experiment, vehicle-treated SHROB rats showed typical metabolic syndrome parameters, including obesity, glucose intolerance, dyslipidemia, and hypertension. Peripheral treatment with palm11-PrRP31 progressively decreased the body weight of SHR rats but not SHROB rats, though glucose tolerance was markedly improved in both strains. Moreover, in SHROB palm11-PrRP31 ameliorated the HOMA index, insulin/glucagon ratio, and increased insulin receptor substrate 1 and 2 expression in fat and insulin signaling in the hypothalamus, while it had no effect on blood pressure. Conclusions We demonstrated that our new lipidized PrRP analog is capable of improving glucose tolerance in obese SHROB rats after peripheral application, suggesting that its effect on glucose metabolism is independent of leptin signaling and body weight lowering. These data suggest that this analog has the potential to be a compound with both anti-obesity and glucose-lowering properties.
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McPherson KC, Taylor L, Johnson AC, Didion SP, Geurts AM, Garrett MR, Williams JM. Early development of podocyte injury independently of hyperglycemia and elevations in arterial pressure in nondiabetic obese Dahl SS leptin receptor mutant rats. Am J Physiol Renal Physiol 2016; 311:F793-F804. [PMID: 27465994 DOI: 10.1152/ajprenal.00590.2015] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2015] [Accepted: 07/25/2016] [Indexed: 01/05/2023] Open
Abstract
The current study examined the effect of obesity on the development of renal injury within the genetic background of the Dahl salt-sensitive rat with a dysfunctional leptin receptor derived from zinc-finger nucleases (SSLepRmutant strain). At 6 wk of age, body weight was 35% higher in the SSLepRmutant strain compared with SSWT rats and remained elevated throughout the entire study. The SSLepRmutant strain exhibited impaired glucose tolerance and increased plasma insulin levels at 6 wk of age, suggesting insulin resistance while SSWT rats did not. However, blood glucose levels were normal throughout the course of the study. Systolic arterial pressure (SAP) was similar between the two strains from 6 to 10 wk of age. However, by 18 wk of age, the development of hypertension was more severe in the SSLepRmutant strain compared with SSWT rats (201 ± 10 vs. 155 ± 3 mmHg, respectively). Interestingly, proteinuria was substantially higher at 6 wk of age in the SSLepRmutant strain vs. SSWT rats (241 ± 27 vs. 24 ± 2 mg/day, respectively) and remained elevated until the end of the study. The kidneys from the SSLepRmutant strain displayed significant glomerular injury, including podocyte foot process effacement and lipid droplets compared with SSWT rats as early as 6 wk of age. By 18 wk of age, plasma creatinine levels were twofold higher in the SSLepRmutant strain vs. SSWT rats, suggesting the presence of chronic kidney disease (CKD). Overall, these results indicate that the SSLepRmutant strain develops podocyte injury and proteinuria independently of hyperglycemia and elevated arterial pressure that later progresses to CKD.
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Affiliation(s)
- Kasi C McPherson
- Department of Pharmacology and Toxicology, University of Mississippi Medical Center, Jackson, Mississippi; and
| | - Lateia Taylor
- Department of Pharmacology and Toxicology, University of Mississippi Medical Center, Jackson, Mississippi; and
| | - Ashley C Johnson
- Department of Pharmacology and Toxicology, University of Mississippi Medical Center, Jackson, Mississippi; and
| | - Sean P Didion
- Department of Pharmacology and Toxicology, University of Mississippi Medical Center, Jackson, Mississippi; and
| | - Aron M Geurts
- Human Molecular Genetics Center, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Michael R Garrett
- Department of Pharmacology and Toxicology, University of Mississippi Medical Center, Jackson, Mississippi; and
| | - Jan M Williams
- Department of Pharmacology and Toxicology, University of Mississippi Medical Center, Jackson, Mississippi; and
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11
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Takemura A, Ishihara A. Mild Hyperbaric Oxygen Inhibits Growth-related Decrease in Muscle Oxidative Capacity of Rats with Metabolic Syndrome. J Atheroscler Thromb 2016; 24:26-38. [PMID: 27237220 PMCID: PMC5225130 DOI: 10.5551/jat.34686] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Aim: We examined the effects of mild hyperbaric oxygen on the properties of the soleus muscle in rats with metabolic syndrome. Methods: Five-week-old metabolic syndrome (SHR/NDmcr-cp, cp/cp) rats were divided into normobaric (CP) and mild hyperbaric oxygen (CP-H) groups (n = 5/group). In addition, 5-week-old Wistar rats were assigned as the normobaric control (WR) group (n = 5). The CP-H group was exposed to 1.25 atmospheres absolute with 36% oxygen for 3 h daily for 16 weeks. Succinate dehydrogenase (SDH) activity and mRNA levels of peroxisome proliferator-activated receptor γ coactivator-1α (Pgc-1α) in the soleus muscle were examined. The fiber type composition, cross-sectional areas, and SDH staining intensity in the soleus muscle were also examined. Results: The CP-H group showed lower fasting and nonfasting blood glucose, glycated hemoglobin, total cholesterol, triglyceride, insulin, and systolic blood pressure levels; higher adiponectin levels; and higher SDH activity and mRNA levels of Pgc-1α in the muscle than the CP group. Compared with the CP group, the CP-H group had a lower percentage of type I fibers and observed type IIA fibers in the muscle. The CP-H group also had higher SDH staining intensity of type I and type IIC fibers in the muscle than the CP group. No differences in these values were observed in the muscles of the WR and CP-H groups. Conclusion: Mild hyperbaric oxygen inhibited growth-related increase in blood glucose levels and decrease in muscle oxidative capacity of rats with metabolic syndrome because of improved oxidative metabolism.
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Affiliation(s)
- Ai Takemura
- Laboratory of Cell Biology and Life Science, Graduate School of Human and Environmental Studies, Kyoto University
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12
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Quasi-Steady-State Analysis based on Structural Modules and Timed Petri Net Predict System's Dynamics: The Life Cycle of the Insulin Receptor. Metabolites 2015; 5:766-93. [PMID: 26694479 PMCID: PMC4693194 DOI: 10.3390/metabo5040766] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2015] [Revised: 11/23/2015] [Accepted: 12/09/2015] [Indexed: 02/01/2023] Open
Abstract
The insulin-dependent activation and recycling of the insulin receptor play an essential role in the regulation of the energy metabolism, leading to a special interest for pharmaceutical applications. Thus, the recycling of the insulin receptor has been intensively investigated, experimentally as well as theoretically. We developed a time-resolved, discrete model to describe stochastic dynamics and study the approximation of non-linear dynamics in the context of timed Petri nets. Additionally, using a graph-theoretical approach, we analyzed the structure of the regulatory system and demonstrated the close interrelation of structural network properties with the kinetic behavior. The transition invariants decomposed the model into overlapping subnetworks of various sizes, which represent basic functional modules. Moreover, we computed the quasi-steady states of these subnetworks and demonstrated that they are fundamental to understand the dynamic behavior of the system. The Petri net approach confirms the experimental results of insulin-stimulated degradation of the insulin receptor, which represents a common feature of insulin-resistant, hyperinsulinaemic states.
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13
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Zhang Q, Davis KJ, Hoffmann D, Vaidya VS, Brown RP, Goering PL. Urinary biomarkers track the progression of nephropathy in hypertensive and obese rats. Biomark Med 2014; 8:85-94. [PMID: 24325231 DOI: 10.2217/bmm.13.106] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
AIMS To determine whether urinary biomarkers of acute kidney injury can be used to monitor the progression of chronic kidney injury in a rat model of hypertension and obesity. MATERIALS & METHODS A suite of novel urinary biomarkers were used to track the progression of kidney damage in SHROB and SHR-lean rats. RESULTS Urinary albumin, NAG, clusterin, osteopontin, RPA-1 and fibrinogen levels were significantly elevated over time and were closely associated with the severity of histopathologically determined nephropathy in both SHROB and SHR-lean rats. CONCLUSION Urinary biomarkers, such as albumin, fibrinogen, NAG, clusterin, RPA-1 and osteopontin, may serve as useful tools to track the progression of chronic kidney disease associated with hypertension and obesity.
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Affiliation(s)
- Qin Zhang
- Center for Devices & Radiological Health, US FDA, 10903 New Hampshire Avenue, Silver Spring, MD 20993, USA
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14
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Borengasser SJ, Zhong Y, Kang P, Lindsey F, Ronis MJJ, Badger TM, Gomez-Acevedo H, Shankar K. Maternal obesity enhances white adipose tissue differentiation and alters genome-scale DNA methylation in male rat offspring. Endocrinology 2013; 154:4113-25. [PMID: 23959936 PMCID: PMC3800750 DOI: 10.1210/en.2012-2255] [Citation(s) in RCA: 128] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The risk of obesity (OB) in adulthood is strongly influenced by maternal body composition. Here we examined the hypothesis that maternal OB influences white adipose tissue (WAT) transcriptome and increases propensity for adipogenesis in the offspring, prior to the development of OB, using an established model of long-term metabolic programming. Employing an overfeeding-based rat model, in which exposure to OB is limited to preconception and gestation alone, we conducted global transcriptomic profiling in WAT, and gene/protein expression analysis of lipogenic and adipogenic pathways and examined adipogenic differentiation of WAT stromal-vascular cells ex vivo. Using reduced representation bisulfite sequencing we also evaluated genome-scale changes in DNA methylation in offspring WAT. Maternal OB led to extensive changes in expression of genes (± 1.8-fold, P ≤ .05), revealing a distinct up-regulation of lipogenic pathways in WAT. mRNA expression of a battery of sterol regulatory element-binding protein-1-regulated genes was increased in OB-dam offspring, which were confirmed by immunoblotting. In conjunction with lipogenic gene expression, OB-dam offspring showed increased glucose transporter-4 mRNA/protein expression and greater AKT phosphorylation following acute insulin challenge, suggesting sensitization of insulin signaling in WAT. Offspring of OB dams also exhibited increased in vivo expression of adipogenic regulators (peroxisome proliferator-activated receptor-γ, CCAAT enhancer binding protein α [C/EBP-α] and C/EBP-β), associated with greater ex vivo differentiation of WAT stromal-vascular cells. These transcriptomic changes were associated with alterations in DNA methylation of CpG sites and CGI shores, proximal to developmentally important genes, including key pro-adipogenic factors (Zfp423 and C/EBP-β). Our findings strongly suggest that the maternal OB in utero alters adipocyte commitment and differentiation via epigenetic mechanisms.
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Affiliation(s)
- Sarah J Borengasser
- Arkansas Children's Nutrition Center, 15 Children's Way, Slot 512-20B, Little Rock, Arkansas 72202.
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15
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Das >UN. Lipoxins, resolvins, protectins, maresins and nitrolipids, and their clinical implications with specific reference to diabetes mellitus and other diseases: part II. ACTA ACUST UNITED AC 2013. [DOI: 10.2217/clp.13.32] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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16
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Nagatomo F, Fujino H, Kondo H, Takeda I, Tsuda K, Ishihara A. High-fat diet-induced reduction of peroxisome proliferator-activated receptor-γ coactivator-1α messenger RNA levels and oxidative capacity in the soleus muscle of rats with metabolic syndrome. Nutr Res 2012; 32:144-51. [PMID: 22348463 DOI: 10.1016/j.nutres.2011.12.015] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2011] [Revised: 12/24/2011] [Accepted: 12/30/2011] [Indexed: 01/21/2023]
Abstract
Animal models of type 2 diabetes exhibit reduced peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α) messenger RNA (mRNA) levels, which are associated with decreased oxidative capacity, in skeletal muscles. In contrast, animal models with metabolic syndrome show normal PGC-1α mRNA levels. We hypothesized that a high-fat diet decreases PGC-1α mRNA levels in skeletal muscles of rats with metabolic syndrome, reducing muscle oxidative capacity and accelerating metabolic syndrome or inducing type 2 diabetes. We examined mRNA levels and fiber profiles in the soleus muscles of rats with metabolic syndrome (SHR/NDmcr-cp [cp/cp]; CP) fed a high-fat diet. Five-week-old CP rats were assigned to a sedentary group (CP-N) that was fed a standard diet (15.1 kJ/g, 23.6% protein, 5.3% fat, and 54.4% carbohydrates) or a sedentary group (CP-H) that was fed a high-fat diet (21.6 kJ/g, 23.6% protein, 34.9% fat, and 25.9% carbohydrates) and were housed for 10 weeks. Body weight, energy intake, and systolic blood pressure were higher in the CP-H group than in the CP-N group. Nonfasting glucose, triglyceride, total cholesterol, and leptin levels were higher in the CP-H group than in the CP-N group. There was no difference in insulin levels between the CP-N and CP-H groups. Muscle PGC-1α mRNA levels and succinate dehydrogenase activity were lower in the CP-H group than in the CP-N group. We concluded that a high-fat diet reduces PGC-1α mRNA levels and oxidative capacity in skeletal muscles and accelerates metabolic syndrome.
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Affiliation(s)
- Fumiko Nagatomo
- Laboratory of Cell Biology and Life Science, Graduate School of Human and Environmental Studies, Kyoto University, Kyoto 606-8501, Japan
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17
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Nagatomo F, Fujino H, Kondo H, Kouzaki M, Gu N, Takeda I, Tsuda K, Ishihara A. The effects of running exercise on oxidative capacity and PGC-1α mRNA levels in the soleus muscle of rats with metabolic syndrome. J Physiol Sci 2012; 62:105-14. [PMID: 22234788 PMCID: PMC10717813 DOI: 10.1007/s12576-011-0188-1] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2011] [Accepted: 12/09/2011] [Indexed: 12/16/2022]
Abstract
Skeletal muscles in animals with metabolic syndrome exhibit reduced oxidative capacity. We investigated the effects of running exercise on fiber characteristics, oxidative capacity, and mRNA levels in the soleus muscles of rats with metabolic syndrome [SHR/NDmcr-cp (cp/cp); CP]. We divided 5-week-old CP rats into non-exercise (CP) and exercise (CP-Ex) groups. Wistar-Kyoto rats (WKY) were used as the control group. CP-Ex rats were permitted voluntary exercise on running wheels for 10 weeks. Triglyceride levels were higher and adiponectin levels lower in the CP and CP-Ex groups than in the WKY group. However, triglyceride levels were lower and adiponectin levels higher in the CP-Ex group than in the CP group. The soleus muscles in CP-Ex rats contained only high-oxidative type I fibers, whereas those in WKY and CP rats contained type I, IIA, and IIC fibers. Muscle succinate dehydrogenase (SDH) activity was higher in the CP-Ex group than in the CP group; there was no difference in SDH activity between the WKY and CP-Ex groups. Muscle proliferator-activated receptor γ coactivator-1α (PGC-1α) mRNA levels were higher in the CP-Ex group than in the CP group; there was no difference in PGC-1α mRNA levels between the WKY and CP-Ex groups. In CP-Ex rats, longer running distance was associated with increased muscle SDH activity and PGC-1α mRNA levels. We concluded that running exercise restored decreased muscle oxidative capacity and PGC-1α mRNA levels and improved hypertriglyceridemia in rats with metabolic syndrome.
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Affiliation(s)
- Fumiko Nagatomo
- Laboratory of Cell Biology and Life Science, Graduate School of Human and Environmental Studies, Kyoto University, Sakyo-ku, Kyoto, 606-8501 Japan
| | - Hidemi Fujino
- Department of Rehabilitation Science, Kobe University Graduate School of Health Sciences, Kobe, 654-0142 Japan
| | - Hiroyo Kondo
- Department of Food Sciences and Nutrition, Nagoya Women’s University, Nagoya, 467-8610 Japan
| | - Motoki Kouzaki
- Laboratory of Neurophysiology, Graduate School of Human and Environmental Studies, Kyoto University, Kyoto, 606-8501 Japan
| | - Ning Gu
- Department of Life Science and Engineering, Harbin Institute of Technology, Harbin, 15001 China
| | - Isao Takeda
- Department of Physical Therapy, Takarazuka University of Medical and Health Care, Takarazuka, 666-0162 Japan
| | - Kinsuke Tsuda
- Laboratory of Metabolism, Graduate School of Human and Environmental Studies, Kyoto University, Kyoto, 606-8501 Japan
| | - Akihiko Ishihara
- Laboratory of Cell Biology and Life Science, Graduate School of Human and Environmental Studies, Kyoto University, Sakyo-ku, Kyoto, 606-8501 Japan
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Kumar S, Singh R, Vasudeva N, Sharma S. Acute and chronic animal models for the evaluation of anti-diabetic agents. Cardiovasc Diabetol 2012; 11:9. [PMID: 22257465 PMCID: PMC3286385 DOI: 10.1186/1475-2840-11-9] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/21/2011] [Accepted: 01/19/2012] [Indexed: 11/10/2022] Open
Abstract
Diabetes mellitus is a potentially morbid condition with high prevalence worldwide thus being a major medical concern. Experimental induction of diabetes mellitus in animal models is essential for the advancement of our knowledge and understanding of the various aspects of its pathogenesis and ultimately finding new therapies and cure. Experimental diabetes mellitus is generally induced in laboratory animals by several methods that include: chemical, surgical and genetic (immunological) manipulations. Most of the experiments in diabetes are carried out in rodents, although some studies are still performed in larger animals. The present review highlights the various methods of inducing diabetes in experimental animals in order to test the newer drugs for their anti-diabetic potential.
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Affiliation(s)
- Suresh Kumar
- Pharmacology Division, Department of Pharmaceutical Sciences, Guru Jambheshwar University of Science and Technology, Post Box: 38, Hisar-125001, India
| | - Rajeshwar Singh
- Pharmacology Division, Department of Pharmaceutical Sciences, Guru Jambheshwar University of Science and Technology, Post Box: 38, Hisar-125001, India
| | - Neeru Vasudeva
- Pharmacology Division, Department of Pharmaceutical Sciences, Guru Jambheshwar University of Science and Technology, Post Box: 38, Hisar-125001, India
| | - Sunil Sharma
- Pharmacology Division, Department of Pharmaceutical Sciences, Guru Jambheshwar University of Science and Technology, Post Box: 38, Hisar-125001, India
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19
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Fatani S, Itua I, Clark P, Wong C, Naderali EK. The effects of diet-induced obesity on hepatocyte insulin signaling pathways and induction of non-alcoholic liver damage. Int J Gen Med 2011; 4:211-9. [PMID: 21475632 PMCID: PMC3068881 DOI: 10.2147/ijgm.s17376] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2011] [Indexed: 12/12/2022] Open
Abstract
The prevalence of diet-induced obesity is increasing amongst adults and children worldwide, predisposing millions of people to an array of health problems that include metabolic syndrome, non-alcoholic fatty liver disease and non-alcoholic steatohepatitis. In this study we used experimental animals to investigate the effects of dietary obesity on markers of hepatic insulin signaling as well as structural changes in hepatocytes. Adult male Wistar rats were randomized and assigned to either a control group or a test group. Controls were fed standard laboratory pelleted diet (chow-fed), while the test group had free access to a highly-palatable diet (HPD). After eight weeks, the HPD-fed animals were subdivided into three subgroups and their diets altered as follows: HPD-to-chow, HPD with the addition of fenofibrate given by oral gavage for a further seven weeks, or HPD with vehicle (1% carboxymethylcellulose at 1 mL/kg body weight) given by oral gavage for a further seven weeks, respectively. Untreated diet-fed animals had significantly higher body weight, liver weight, and all measured metabolic profiles compared with chow-fed and treated diet-fed groups. Expression of kinases IRβ, IRS-1, AKt, eNOS, Shc and ERK1/2 were unaffected by obesity, while IRS-2 and P I3 kinase levels were significantly reduced in untreated HPD animals. Compared with chow-fed animals, steatosis and steatohepatitis were almost doubled in animals from untreated HPD, while removal of HPD and fenofibrate-treatment reduced steatosis by 40% and 80% respectively. These data suggest that diet-induced obesity affects intracellular insulin signaling mechanisms, namely IRS-2 and PI 3-kinase, leading to hepatic insulin resistance. Moreover, diet-induced obesity induces fatty liver, an effect which can be reversed by either removal of the source of obesity or treatment with fenofibrate, a peroxisome proliferator-activated receptor alpha agonist.
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Affiliation(s)
- Sameer Fatani
- Obesity Biology Unit, School of Clinical Sciences, University of Liverpool, Liverpool, UK
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20
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Wheatley KE, Nogueira LM, Perkins SN, Hursting SD. Differential effects of calorie restriction and exercise on the adipose transcriptome in diet-induced obese mice. J Obes 2011; 2011:265417. [PMID: 21603264 PMCID: PMC3092555 DOI: 10.1155/2011/265417] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/09/2010] [Accepted: 03/01/2011] [Indexed: 11/18/2022] Open
Abstract
We tested the hypothesis that obesity reversal by calorie restriction (CR) versus treadmill exercise (EX) differentially modulates adipose gene expression using 48 female C57BL/6 mice administered a diet-induced obesity (DIO) regimen for 8 weeks, then randomized to receive for 8 weeks either: (1) a control (AIN-76A) diet, fed ad libitum (DIO control); (2) a 30% CR regimen; (3) a treadmill EX regimen (with AIN-76A diet fed ad libitum); or (4) continuation of the DIO diet. Relative to the DIO controls, both CR and EX reduced adiposity by 35-40% and serum leptin levels by 80%, but only CR increased adiponectin and insulin sensitivity. Gene expression microarray analysis of visceral white adipose tissue revealed 209 genes responsive to both CR and EX, relative to the DIO group. However, CR uniquely altered expression of an additional 496 genes, whereas only 20 were uniquely affected by EX. Of the genes distinctly responsive to CR, 17 related to carbohydrate metabolism and glucose transport, including glucose transporter (GLUT) 4. Chromatin immunoprecipitation assays of the Glut4 promoter revealed that, relative to the DIO controls, CR significantly increased histone 4 acetylation, suggesting epigenetic regulation may underlie some of the differential effects of CR versus EX on the adipose transcriptome.
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Affiliation(s)
- Karrie E. Wheatley
- Department of Nutritional Sciences, University of Texas, Austin, TX 78712, USA
- Department of Molecular Carcinogenesis, UT-MD Anderson Cancer Center, Smithville, TX 78957, USA
| | - Leticia M. Nogueira
- Department of Molecular Carcinogenesis, UT-MD Anderson Cancer Center, Smithville, TX 78957, USA
- Institute for Cellular and Molecular Biology, University of Texas, Austin, TX 78712, USA
- Cancer Prevention Fellowship Program, National Cancer Institute, Bethesda, MD 20852, USA
| | - Susan N. Perkins
- Department of Nutritional Sciences, University of Texas, Austin, TX 78712, USA
| | - Stephen D. Hursting
- Department of Nutritional Sciences, University of Texas, Austin, TX 78712, USA
- Department of Molecular Carcinogenesis, UT-MD Anderson Cancer Center, Smithville, TX 78957, USA
- Institute for Cellular and Molecular Biology, University of Texas, Austin, TX 78712, USA
- *Stephen D. Hursting:
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Rong X, Li Y, Ebihara K, Zhao M, Kusakabe T, Tomita T, Murray M, Nakao K. Irbesartan treatment up-regulates hepatic expression of PPARalpha and its target genes in obese Koletsky (fa(k)/fa(k)) rats: a link to amelioration of hypertriglyceridaemia. Br J Pharmacol 2010; 160:1796-807. [PMID: 20649581 DOI: 10.1111/j.1476-5381.2010.00835.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
BACKGROUND AND PURPOSE Hypertriglyceridaemia is associated with an increased risk of cardiovascular disease. Irbesartan, a well-established angiotensin II type 1 receptor (AT(1)) blocker, improves hypertriglyceridaemia in rodents and humans but the underlying mechanism of action is unclear. EXPERIMENTAL APPROACH Male obese Koletsky (fa(k)/fa(k)) rats, which exhibit spontaneous hypertension and metabolic abnormalities, received irbesartan (40 mg x kg(-1) x day(-1)) or vehicle by oral gavage over 7 weeks. Adipocyte-derived hormones in plasma were measured by ELISA. Gene expression in liver and other tissues was assessed by real-time PCR and Western immunoblotting. KEY RESULTS In Koletsky (fa(k)/fa(k)) rats irbesartan lowered plasma concentrations of triglycerides and non-esterified fatty acids, and decreased plasma insulin concentrations and the homeostasis model assessment of insulin resistance index. However, this treatment did not affect food intake, body weight, epididymal white adipose tissue weight, adipocyte size and plasma leptin concentrations, although plasma adiponectin was decreased. Irbesartan up-regulated hepatic expression of mRNAs corresponding to peroxisome proliferator-activated receptor (PPAR)alpha and its target genes (carnitine palmitoyltransferase-1a, acyl-CoA oxidase and fatty acid translocase/CD36) that mediate hepatic fatty acid uptake and oxidation; the increase in hepatic PPARalpha expression was confirmed at the protein level. In contrast, irbesartan did not affect expression of adipose PPARgamma and its downstream genes or hepatic genes that mediate fatty acid synthesis. CONCLUSIONS AND IMPLICATIONS These findings demonstrate that irbesartan treatment up-regulates PPARalpha and several target genes in liver of obese spontaneously hypertensive Koletsky (fa(k)/fa(k)) rats and offers a novel insight into the lipid-lowering mechanism of irbesartan.
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Affiliation(s)
- X Rong
- Department of Medicine and Clinical Science, Kyoto University Graduate School of Medicine, Sakyo-ku, Kyoto, Japan
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Lee J, Xu Y, Lu L, Bergman B, Leitner JW, Greyson C, Draznin B, Schwartz GG. Multiple abnormalities of myocardial insulin signaling in a porcine model of diet-induced obesity. Am J Physiol Heart Circ Physiol 2009; 298:H310-9. [PMID: 19897715 DOI: 10.1152/ajpheart.00359.2009] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Heightened cardiovascular risk among patients with systemic insulin resistance is not fully explained by the extent of atherosclerosis. It is unknown whether myocardial insulin resistance accompanies systemic insulin resistance and contributes to increased cardiovascular risk. This study utilized a porcine model of diet-induced obesity to determine if myocardial insulin resistance develops in parallel with systemic insulin resistance and investigated potential mechanisms for such changes. Micropigs (n = 16) were assigned to control (low fat, no added sugars) or intervention (25% wt/wt coconut oil and 20% high-fructose corn syrup) diet for 7 mo. Intervention diet resulted in obesity, hypertension, and dyslipidemia. Systemic insulin resistance was manifest by elevated fasting glucose and insulin, abnormal response to intravenous glucose tolerance testing, and blunted skeletal muscle phosphatidylinositol-3-kinase (PI 3-kinase) activation and protein kinase B (Akt) phosphorylation in response to insulin. In myocardium, insulin-stimulated glucose uptake, PI 3-kinase activation, and Akt phosphorylation were also blunted in the intervention diet group. These findings were explained by increased myocardial content of p85alpha (regulatory subunit of PI 3-kinase), diminished association of PI 3-kinase with insulin receptor substrate (IRS)-1 in response to insulin, and increased serine-307 phosphorylation of IRS-1. Thus, in a porcine model of diet-induced obesity that recapitulates many characteristics of insulin-resistant patients, myocardial insulin resistance develops along with systemic insulin resistance and is associated with multiple abnormalities of insulin signaling.
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Affiliation(s)
- Jenny Lee
- Veterans Affairs Medical Center, University of Colorado, Denver, Colorado, USA
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Shafrir E, Ziv E. A useful list of spontaneously arising animal models of obesity and diabetes. Am J Physiol Endocrinol Metab 2009; 296:E1450-2. [PMID: 19468077 DOI: 10.1152/ajpendo.00113.2009] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Abstract
Animal obesity models differ widely in type and extent of obesity. They are either based on environmental factors (e.g., high-fat diet-induced obesity), spontaneous mutants (i.e., ob/ob mice), genetically engineered animals (e.g., mice with melanocortin receptor subtype-4 gene disruption (knock-out), or mechanical intervention (e.g., chemical lesion of the ventromedial hypothalamus). This unit reviews available rodent models to study obesity and attempts to highlight the greatest utility for each model.
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Ernsberger P, Johnson JL, Rosenthal T, Mirelman D, Koletsky RJ. Therapeutic actions of allylmercaptocaptopril and captopril in a rat model of metabolic syndrome. Am J Hypertens 2007; 20:866-74. [PMID: 17679035 PMCID: PMC2930912 DOI: 10.1016/j.amjhyper.2007.02.015] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2006] [Revised: 12/02/2006] [Accepted: 02/26/2007] [Indexed: 01/13/2023] Open
Abstract
BACKGROUND Hypertension often coexists with hyperlipidemia, insulin resistance, and glucose intolerance in metabolic syndrome. Allylmercaptocaptopril is a conjugate of the angiotensin-converting enzyme inhibitor captopril with allicin, an active principle in garlic with multiple beneficial actions on metabolic-syndrome abnormalities. We sought to test the hypothesis that the conjugation of allicin to captopril may confer additional therapeutic actions in metabolic disease. METHODS We compared allylmercaptocaptopril (53.5 mg/kg/day orally for 60 days) to an equimolar dose of captopril (40 mg/kg/day) in the spontaneously hypertensive, obese rat (SHROB) model. RESULTS Allylmercaptocaptopril prevented progressive weight gain, without a detectable effect on food intake. Both captopril and allylmercaptocaptopril lowered blood pressure, but allylmercaptocaptopril was more effective. Allylmercaptocaptopril, but not captopril, improved cardiac hypertrophy, as indicated by heart weight and ventricular-wall thickness. Allylmercaptocaptopril improved, whereas captopril impaired, oral glucose tolerance after a fast. Triglycerides were decreased by both captopril and allylmercaptocaptopril. Total cholesterol and non-HDL cholesterol were reduced by captopril but not by allylmercaptocaptopril. The SHROB rats developed severe glomerulosclerosis and renal failure. Allylmercaptocaptopril showed significant nephro-protection, as indicated by reductions in urinary protein loss, urinary protein-to-creatinine ratio, and plasma creatinine. Captopril showed the same trends and also prevented the decline of creatinine clearance. Finally, both allylmercaptocaptopril and captopril reduced the basal level of lipolysis in isolated abdominal adipocytes, and restored the response to catecholamine stimulation. CONCLUSIONS Both captopril and allylmercaptocaptopril are effective in attenuating multiple abnormalities of metabolic syndrome. Allylmercaptocaptopril may have additional effectiveness on improving glucose tolerance, further lowering blood pressure, reducing cardiac hypertrophy, preventing weight gain, and protecting against renal disease.
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Affiliation(s)
- Paul Ernsberger
- Department of Nutrition, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106-4906, USA.
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26
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Shadoan MK, Zhang L, Wagner JD. Effects of hormone therapy on insulin signaling proteins in skeletal muscle of cynomolgus monkeys. Steroids 2004; 69:313-8. [PMID: 15219409 DOI: 10.1016/j.steroids.2004.02.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/09/2003] [Revised: 02/09/2004] [Accepted: 02/16/2004] [Indexed: 11/26/2022]
Abstract
We have previously shown that hormone therapy (HT) with medroxyprogesterone acetate (MPA) alone or in combination with conjugated equine estrogens (CEE) impairs insulin sensitivity. In the current study, we sought to determine if the effect of MPA on whole body insulin sensitivity is associated with alterations in insulin signaling proteins in skeletal muscle. Ovariectomized cynomolgus monkeys were treated for 2 years with either no hormones (n = 10), CEE (0.625 mg/day human equivalent, n = 11) or CEE + MPA (2.5 mg/day human equivalent, n = 12). At the end of the study, biopsies of rectus femoris muscle were flash frozen in the basal and insulin-stimulated (10 min post-intravenous insulin injection) state. Immunoblotting revealed that CEE + MPA monkeys had significantly less glucose transporter 4 (GLUT4) expression (ANOVA P = 0.001), but there was no significant treatment effect on expression of insulin receptor, insulin receptor substrate (IRS)-1, IRS-2, or the p85 subunit of phosphatidylinositol 3-kinase (PI 3-K). There was a tendency for decreased insulin receptor tyrosine phosphorylation with CEE + MPA treatment (ANOVA P = 0.14). These deficiencies in skeletal muscle insulin signaling likely contribute to the unfavorable changes in whole body insulin sensitivity associated with CEE + MPA treatment.
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Affiliation(s)
- Melanie K Shadoan
- Department of Pathology, Comparative Medicine Clinical Research Center, Medical Center Boulevard, Wake Forest University School of Medicine, Winston-Salem, NC 27157, USA.
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27
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Kovacs P, Hanson RL, Lee YH, Yang X, Kobes S, Permana PA, Bogardus C, Baier LJ. The role of insulin receptor substrate-1 gene (IRS1) in type 2 diabetes in Pima Indians. Diabetes 2003; 52:3005-9. [PMID: 14633864 DOI: 10.2337/diabetes.52.12.3005] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The insulin receptor substrate-1 (IRS1) is a critical element in insulin-signaling pathways, and mutations in the IRS1 gene have been reported to have a role in determining susceptibility to traits related to type 2 diabetes. In gene expression studies of tissue biopsies from nondiabetic Pima Indians, IRS1 mRNA levels were reduced in adipocytes from obese subjects compared with lean subjects, and IRS1 mRNA levels were also reduced in skeletal muscle from insulin-resistant subjects compared with insulin-sensitive subjects (all P < 0.05). Based on these expression differences and the known physiologic role of IRS1, this gene was investigated as a candidate gene for susceptibility to type 2 diabetes in Pima Indians, a population with an extremely high incidence and prevalence of type 2 diabetes. Thirteen variants were identified, and among these variants, several were in complete linkage disequilibrium. Four genotypically unique variants were further genotyped in 937 DNA samples from full-heritage Pima Indians. Three of the variants were modestly associated with type 2 diabetes (P < 0.05), one of which was additionally associated with 2-h plasma insulin and glucose as well as insulin action at physiologic and maximally stimulating insulin concentrations (all P < 0.05). The association of variants in IRS1 with type 2 diabetes and type 2 diabetes-related phenotypes and the differential expression of IRS1 in adipocytes and skeletal muscle suggest a role of this gene in the pathogenesis of type 2 diabetes in Pima Indians.
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Affiliation(s)
- Peter Kovacs
- Phoenix Epidemiology and Clinical Research Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Phoenix, Arizona 85016, USA
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28
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Shadoan MK, Anthony MS, Rankin SE, Clarkson TB, Wagner JD. Effects of tibolone and conjugated equine estrogens with or without medroxyprogesterone acetate on body composition and fasting carbohydrate measures in surgically postmenopausal monkeys. Metabolism 2003; 52:1085-91. [PMID: 14506611 DOI: 10.1016/s0026-0495(03)00181-1] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The effects of tibolone on body weight, body composition, and fasting carbohydrate measures in surgically postmenopausal cynomolgus monkeys were compared to those of conjugated equine estrogens (CEE) with and without medroxyprogesterone acetate (MPA). Monkeys were fed a moderately atherogenic diet with either no hormones (control n = 29), CEE (0.042 mg/kg, n = 27), CEE + MPA (0.167 mg/kg, n = 29), low-dose tibolone (LoTib, 0.05 mg/kg, n = 30), or high-dose tibolone (HiTib, 0.20 mg/kg, n = 31) daily for 2 years. Body weight (BW) was measured throughout the study, and dual-energy x-ray absorptiometry (DEXA) scans of the abdominal region (lumbar vertebrae 1 through 5) were performed at the end of the trial to assess abdominal body composition. Fasting carbohydrate measures (glucose, insulin, C-peptide, and fructosamine) were determined at baseline and after 2 years of treatment. Compared to controls, BW significantly increased and abdominal soft tissue mass was greater (analysis of variance [ANOVA], P <.001, P = 0.003, respectively) in all but the CEE-treated group (P =.78, P =.94, respectively). HiTib-treated monkeys had greater abdominal lean mass compared to controls (P =.008), while there was no significant treatment effect on abdominal fat mass (analysis of covariance [ANCOVA], P =.29). Fasting insulin concentrations and fasting insulin/glucose ratios were greater in CEE + MPA- (P =.002, P =.03, respectively) and HiTib-treated monkeys (P =.03, P =.02, respectively) compared to controls. There was a strong trend for a treatment effect on fasting blood glucose concentration (ANCOVA, P =.06) with CEE + MPA-treated animals having the greatest values, despite no difference in fructosamine concentration (ANCOVA, P =.57). Using these fasting measures, the homeostasis model assessment (HOMA-IR) revealed significant insulin resistance with CEE + MPA treatment compared to controls (P =.008), while the quantitative insulin sensitivity check index (QUICKI) showed significantly impaired insulin sensitivity in all hormone replacement therapy (HRT) groups (all P values <.03), except CEE (P =.12). In conclusion, HRT with CEE + MPA or tibolone results in greater BW, abdominal soft tissue, and insulin resistance (CEE + MPA and HiTib) compared to control-treated monkeys.
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Affiliation(s)
- Melanie K Shadoan
- Wake Forest University School of Medicine, Winston-Salem, NC 27157-1032, USA
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Zorad S, Golda V, Fickova M, Macho L, Pinterova L, Jurcovicova J. Terguride treatment attenuated prolactin release and enhanced insulin receptor affinity and GLUT 4 content in obese spontaneously hypertensive female, but not male rats. Ann N Y Acad Sci 2002; 967:490-9. [PMID: 12079879 DOI: 10.1111/j.1749-6632.2002.tb04307.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Glucose tolerance, serum insulin, insulin receptors in epididymal fat tissue, and GLUT 4 content in muscle, as well as serum prolactin, were studied in obese and lean spontaneously hypertensive rats (SHRs) of both sexes. Obese animals displayed insulin resistance and decreased capacity of high-affinity binding sites of insulin receptors in fat tissue plasma membranes. GLUT 4 content in musculus quadriceps was diminished only in obese females. Terguride treatment lowered prolactin serum levels, which was concomitant with ameliorated insulin sensitivity in obese animals of both sexes. Similarly, only in obese females, terguride significantly increased the affinity of high-affinity insulin-binding sites and normalized GLUT 4 content. Our results document downregulation of insulin receptors and GLUT 4 in obesity and suggest a role for prolactin in obesity-induced insulin resistance, particularly in female rats.
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Affiliation(s)
- S Zorad
- Institute of Experimental Endocrinology, Slovak Academy of Sciences, Bratislava, Slovak Republic.
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Youngren JF, Paik J, Barnard RJ. Impaired insulin-receptor autophosphorylation is an early defect in fat-fed, insulin-resistant rats. J Appl Physiol (1985) 2001; 91:2240-7. [PMID: 11641367 DOI: 10.1152/jappl.2001.91.5.2240] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
High-fat feeding results in impaired insulin signaling in skeletal muscle, but the role of the insulin receptor (IR) remains controversial. In the present study, female Fischer 344 rats were fed diets either low in fat [low fat, complex carbohydrate (LFCC)] or high in fat and sucrose (HFS). Insulin-stimulated skeletal muscle glucose transport, measured in purified sarcolemmal vesicles, was lower in rats consuming the HFS diet for 2 and 8 wk compared with LFCC controls (72.9 +/- 3.5, 67.6 +/- 3.5, and 86.1 +/- 3.5 pmol x mg(-1) x 15 s(-1), respectively; P < 0.05). Muscle IR content was unchanged in 2-wk HFS animals but was 50% lower in the 8-wk HFS group (P < 0.001). However, compared with LFCC, insulin-stimulated IR autophosphorylation was 26% lower in 2-wk HFS and 40% lower in 8-wk HFS animals (P < 0.005). Total muscle content of the proposed IR inhibitors cytokine tumor necrosis factor-alpha and membrane glycoprotein PC-1 was not significantly changed in HFS animals at either 2 or 8 wk. These results demonstrate that high-fat feeding induces insulin resistance in muscle concomitant with a diminished IR signaling capacity, although the mechanism remains unknown.
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Affiliation(s)
- J F Youngren
- Division of Diabetes and Endocrine Research, Department of Medicine, Mount Zion Medical Center, University of California, San Francisco 94143-1616, USA.
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31
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Wang L, Shao J, Muhlenkamp P, Liu S, Klepcyk P, Ren J, Friedman JE. Increased insulin receptor substrate-1 and enhanced skeletal muscle insulin sensitivity in mice lacking CCAAT/enhancer-binding protein beta. J Biol Chem 2000; 275:14173-81. [PMID: 10747954 DOI: 10.1074/jbc.m000764200] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
CCAAT/enhancer-binding protein beta (C/EBPbeta) controls gene transcription and metabolic processes in a variety of insulin-sensitive tissues; however, its role in regulating insulin responsiveness in vivo has not been investigated. We performed hyperinsulinemic-euglycemic clamps in awake, non-stressed, chronically catheterized adult mice homozygous for a deletion in the gene for C/EBPbeta (C/EBPbeta(-/-)). Fasting plasma insulin, glucose, and free fatty acid (FFA) levels were significantly lower in C/EBPbeta(-/-) mice compared with wild-type (WT) controls. Acute hyperinsulinemia (4 h) suppressed hepatic glucose production, phosphoenolpyruvate carboxykinase mRNA, and plasma FFA to a similar extent in WT and C/EBPbeta(-/-) mice, suggesting that C/EBPbeta deletion does not alter the metabolic and gene regulatory response to insulin in liver and adipose tissue. In contrast, using submaximal (5 milliunits/kg/min) and maximal (20 milliunits/kg/min) insulin infusions, whole-body glucose disposal was 77% (p < 0.01) and 33% (p < 0.05) higher in C/EBPbeta(-/-) mice, respectively, compared with WT mice. Maximal insulin-stimulated 3-O-methylglucose uptake in isolated soleus muscle was 54% greater in C/EBPbeta(-/-) mice (p < 0.05). Furthermore, insulin-stimulated insulin receptor and Akt Ser(473) phosphorylation and phosphatidylinositol 3-kinase activity were 1.6-2.5-fold greater in skeletal muscle from C/EBPbeta(-/-) mice compared with WT mice. The level of insulin receptor substrate-1 protein was increased 2-fold in skeletal muscle from C/EBPbeta(-/-) mice. These results demonstrate that C/EBPbeta deletion decreases plasma FFA levels and increases insulin signal transduction specifically in skeletal muscle, and both contribute to increased whole-body insulin sensitivity.
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Affiliation(s)
- L Wang
- Department of Nutrition, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106-4935, USA
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Virkamäki A, Ueki K, Kahn CR. Protein-protein interaction in insulin signaling and the molecular mechanisms of insulin resistance. J Clin Invest 1999; 103:931-43. [PMID: 10194465 PMCID: PMC408269 DOI: 10.1172/jci6609] [Citation(s) in RCA: 562] [Impact Index Per Article: 22.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Affiliation(s)
- A Virkamäki
- Research Division, Joslin Diabetes Center, Harvard Medical School, Boston, Massachusetts 02215, USA
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