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Nishiyama K, Ono M, Tsuno T, Inoue R, Fukunaka A, Okuyama T, Kyohara M, Togashi Y, Fukushima S, Atsumi T, Sato A, Tsurumoto A, Sakai C, Fujitani Y, Terauchi Y, Ito S, Shirakawa J. Protective Effects of Imeglimin and Metformin Combination Therapy on β-Cells in db/db Male Mice. Endocrinology 2023; 164:bqad095. [PMID: 37314160 DOI: 10.1210/endocr/bqad095] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/08/2023] [Revised: 04/23/2023] [Accepted: 06/13/2023] [Indexed: 06/15/2023]
Abstract
Imeglimin and metformin act in metabolic organs, including β-cells, via different mechanisms. In the present study, we investigated the impacts of imeglimin, metformin, or their combination (Imeg + Met) on β-cells, the liver, and adipose tissues in db/db mice. Imeglimin, metformin, or Imeg + Met treatment had no significant effects on glucose tolerance, insulin sensitivity, respiratory exchange ratio, or locomotor activity in db/db mice. The responsiveness of insulin secretion to glucose was recovered by Imeg + Met treatment. Furthermore, Imeg + Met treatment increased β-cell mass by enhancing β-cell proliferation and ameliorating β-cell apoptosis in db/db mice. Hepatic steatosis, the morphology of adipocytes, adiposity assessed by computed tomography, and the expression of genes related to glucose or lipid metabolism and inflammation in the liver and fat tissues showed no notable differences in db/db mice. Global gene expression analysis of isolated islets indicated that the genes related to regulation of cell population proliferation and negative regulation of cell death were enriched by Imeg + Met treatment in db/db islets. In vitro culture experiments confirmed the protective effects of Imeg + Met against β-cell apoptosis. The expression of Snai1, Tnfrsf18, Pdcd1, Mmp9, Ccr7, Egr3, and Cxcl12, some of which have been linked to apoptosis, in db/db islets was attenuated by Imeg + Met. Treatment of a β-cell line with Imeg + Met prevented apoptosis induced by hydrogen peroxide or palmitate. Thus, the combination of imeglimin and metformin is beneficial for the maintenance of β-cell mass in db/db mice, probably through direct action on β-cells, suggesting a potential strategy for protecting β-cells in the treatment of type 2 diabetes.
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Affiliation(s)
- Kuniyuki Nishiyama
- Laboratory of Diabetes and Metabolic Disorders, Institute for Molecular and Cellular Regulation (IMCR), Gunma University, Maebashi 371-8512, Japan
- Department of Endocrinology and Metabolism, Graduate School of Medicine, Yokohama City University, Yokohama 236-0004, Japan
- Department of Pediatrics, Graduate School of Medicine, Yokohama City University, Yokohama 236-0004, Japan
| | - Masato Ono
- Department of Endocrinology and Metabolism, Graduate School of Medicine, Yokohama City University, Yokohama 236-0004, Japan
| | - Takahiro Tsuno
- Laboratory of Diabetes and Metabolic Disorders, Institute for Molecular and Cellular Regulation (IMCR), Gunma University, Maebashi 371-8512, Japan
- Department of Endocrinology and Metabolism, Graduate School of Medicine, Yokohama City University, Yokohama 236-0004, Japan
| | - Ryota Inoue
- Laboratory of Diabetes and Metabolic Disorders, Institute for Molecular and Cellular Regulation (IMCR), Gunma University, Maebashi 371-8512, Japan
- Department of Endocrinology and Metabolism, Graduate School of Medicine, Yokohama City University, Yokohama 236-0004, Japan
| | - Ayako Fukunaka
- Laboratory of Developmental Biology and Metabolism, Institute for Molecular and Cellular Regulation (IMCR), Gunma University, Maebashi 371-8512, Japan
| | - Tomoko Okuyama
- Department of Endocrinology and Metabolism, Graduate School of Medicine, Yokohama City University, Yokohama 236-0004, Japan
| | - Mayu Kyohara
- Department of Endocrinology and Metabolism, Graduate School of Medicine, Yokohama City University, Yokohama 236-0004, Japan
| | - Yu Togashi
- Department of Endocrinology and Metabolism, Graduate School of Medicine, Yokohama City University, Yokohama 236-0004, Japan
| | - Setsuko Fukushima
- Laboratory of Diabetes and Metabolic Disorders, Institute for Molecular and Cellular Regulation (IMCR), Gunma University, Maebashi 371-8512, Japan
| | - Takuto Atsumi
- Laboratory of Diabetes and Metabolic Disorders, Institute for Molecular and Cellular Regulation (IMCR), Gunma University, Maebashi 371-8512, Japan
| | - Aoi Sato
- Laboratory of Diabetes and Metabolic Disorders, Institute for Molecular and Cellular Regulation (IMCR), Gunma University, Maebashi 371-8512, Japan
| | - Asuka Tsurumoto
- Laboratory of Diabetes and Metabolic Disorders, Institute for Molecular and Cellular Regulation (IMCR), Gunma University, Maebashi 371-8512, Japan
| | - Chisato Sakai
- Laboratory of Diabetes and Metabolic Disorders, Institute for Molecular and Cellular Regulation (IMCR), Gunma University, Maebashi 371-8512, Japan
| | - Yoshio Fujitani
- Laboratory of Developmental Biology and Metabolism, Institute for Molecular and Cellular Regulation (IMCR), Gunma University, Maebashi 371-8512, Japan
| | - Yasuo Terauchi
- Department of Endocrinology and Metabolism, Graduate School of Medicine, Yokohama City University, Yokohama 236-0004, Japan
| | - Shuichi Ito
- Department of Pediatrics, Graduate School of Medicine, Yokohama City University, Yokohama 236-0004, Japan
| | - Jun Shirakawa
- Laboratory of Diabetes and Metabolic Disorders, Institute for Molecular and Cellular Regulation (IMCR), Gunma University, Maebashi 371-8512, Japan
- Department of Endocrinology and Metabolism, Graduate School of Medicine, Yokohama City University, Yokohama 236-0004, Japan
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Cigarette smoking blocks the benefit from reduced weight gain for insulin action by shifting lipids deposition to muscle. Clin Sci (Lond) 2021; 134:1659-1673. [PMID: 32573727 DOI: 10.1042/cs20200173] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Revised: 06/10/2020] [Accepted: 06/23/2020] [Indexed: 12/29/2022]
Abstract
Cigarette smoking (CS) is known to reduce body weight and this often masks its real effect on insulin action. The present study tested the hypothesis that CS can divert lipid deposition to muscles to offset the supposed benefit of reduced body weight gain on insulin signalling in this major site for glucose tolerance (or insulin action). The study was conducted in mice exposed to chronic CS followed by either a chow (CH) diet or a high-fat (HF) diet. CS increased triglyceride (TG) levels in both plasma and muscle despite a reduced body weight gain and adiposity. CS led to glucose intolerance in CH-fed mice and they retained the glucose intolerance that was induced by the HF diet. In adipose tissue, CS increased macrophage infiltration and the mRNA expression of TNFα but suppressed the protein expression of adipose triglyceride lipase and PPARγ. While CS increased hormone-sensitive lipase and suppressed the mRNA expression of leptin, these effects were blunted in HF-fed mice. These results imply that CS impairs insulin signalling in skeletal muscle via accumulated intramuscular lipids from lipolysis and lipodystrophy of adipose tissues. This may explain why smokers may not benefit from insulin sensitising effects of reduced body weight gain.
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Lehtonen S. Metformin Protects against Podocyte Injury in Diabetic Kidney Disease. Pharmaceuticals (Basel) 2020; 13:ph13120452. [PMID: 33321755 PMCID: PMC7764076 DOI: 10.3390/ph13120452] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2020] [Revised: 12/06/2020] [Accepted: 12/08/2020] [Indexed: 02/07/2023] Open
Abstract
Metformin is the most commonly prescribed drug for treating type 2 diabetes mellitus (T2D). Its mechanisms of action have been under extensive investigation, revealing that it has multiple cellular targets, either direct or indirect ones, via which it regulates numerous cellular pathways. Diabetic kidney disease (DKD), the serious complication of T2D, develops in up to 50% of the individuals with T2D. Various mechanisms contribute to the development of DKD, including hyperglycaemia, dyslipidemia, oxidative stress, chronic low-grade inflammation, altered autophagic activity and insulin resistance, among others. Metformin has been shown to affect these pathways, and thus, it could slow down or prevent the progression of DKD. Despite several animal studies demonstrating the renoprotective effects of metformin, there is no concrete evidence in clinical settings. This review summarizes the renoprotective effects of metformin in experimental settings. Special emphasis is on the effects of metformin on podocytes, the glomerular epithelial cells that are central in maintaining the glomerular ultrafiltration function.
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Affiliation(s)
- Sanna Lehtonen
- Research Program for Clinical and Molecular Metabolism and Department of Pathology, Faculty of Medicine, University of Helsinki, 00290 Helsinki, Finland
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Yang X. Design and optimization of crocetin loaded PLGA nanoparticles against diabetic nephropathy via suppression of inflammatory biomarkers: a formulation approach to preclinical study. Drug Deliv 2020; 26:849-859. [PMID: 31524015 PMCID: PMC6761602 DOI: 10.1080/10717544.2019.1642417] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Diabetic nephropathy (DN) is a serious complication of diabetes mellitus whose expand
process is linked with the fibrosis, renal hypertrophy and inflammation. The current study
was to formulate and optimize the nano-formulation of crocetin (CT-PLGA-NPs) against
Streptozotocin-induced renal nephropathy in rats. Double emulsion evaporation technique
was used for the preparation of CT-PLGA-NPs. CT-PLGA-NPs were scrutinized for
polydispersity index, size, gastric stability, entrapment, drug-loading capacity and
in-vitro drug release and in vivo preclinical study.
Single intraperitoneal injection of streptozotocin (STZ) (55 mg/kg) and rats were divided
into different group. Renal function and metabolic parameters of urine and serum were
estimated. Fibrotic protein, renal pro-inflammatory cytokines and degree of renal damage
expression were also determined. We also estimated the fibronectin, type IV collagen and
transforming growth factor-β1 for a possible mechanism of action. Crocetin supplement
(10 mg/kg) and CT-PLGA-NPs exhibited the accumulation of the drug in kidney and liver of
diabetic rats. Crocetin reduced the BGL and enhanced plasma insulin and body weight. Dose
dependent treatment of crocetin significantly (p < .001)
down-regulated the expression of renal tumor necrosis factor-α (TNF-α), interleukin-6
(IL-6), interleukin (IL)-1β (IL-1β) and Monocyte Chemoattractant Protein-1 (MCP-1).
Crocetin significantly (p < .001) altered the expression of
fibronectin, type IV collagen, and transforming growth factor-β1 (TGF-1β). Crocetin
significantly (p < .001) down-regulated the protein kinase C activity
and the expression of nuclear factor κB (NF-κB) p65 activity and protein production in
renal tissue. On the basis of the available result, we can conclude that nano-formulation
of crocetin could attenuate the diabetic nephropathy via antifibrotic and
anti-inflammatory effect.
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Affiliation(s)
- Xiaodong Yang
- Department of General Medicine, Zhumadian Central Hospital , Zhumadian , China
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Zhou X, Fouda S, Zeng XY, Li D, Zhang K, Xu J, Ye JM. Characterization of the Therapeutic Profile of Albiflorin for the Metabolic Syndrome. Front Pharmacol 2019; 10:1151. [PMID: 31680948 PMCID: PMC6797612 DOI: 10.3389/fphar.2019.01151] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2019] [Accepted: 09/06/2019] [Indexed: 12/12/2022] Open
Abstract
Albiflorin (AF) is a small molecule (MW 481) isolated from Paeoniae radix, a plant used as a remedy for various conditions with pathogenesis shared by metabolic diseases. Reported here is our characterization of its therapeutic profiles in three mouse models with distinctive pathological features of metabolic syndrome (MetS). Our results firstly showed that AF alleviated high fat (HF) induced obesity and associated glucose intolerance, suggesting its therapeutic efficacy for MetS. In the type 2 diabetes (T2D) model induced by a combination of HF and low doses of streptozotocin, AF lowered hyperglycaemia and improved insulin-stimulated glucose disposal. In the non-alcoholic steatohepatitis-like model resulting from a HF and high cholesterol (HF-HC) diet, AF reversed the increased liver triglyceride and cholesterol, plasma aspartate aminotransferase, and liver TNFα mRNA levels. Consistent with its effect in promoting glucose disposal in HF-fed mice, AF stimulated glucose uptake and GLUT4 translocation to the plasma membrane in L6 myotubes. However, these effects were unlikely to be associated with activation of insulin, AMPK, ER, or cellular stress signalling cascades. Further studies revealed that AF increased the whole-body energy expenditure and physical activity. Taken together, our findings indicate that AF exerts a therapeutic potential for MetS and related diseases possibly by promoting physical activity associated whole-body energy expenditure and glucose uptake in muscle. These effects are possibly mediated by a new mechanism distinct from other therapeutics derived from Chinese medicine.
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Affiliation(s)
- Xiu Zhou
- School of Biotechnology and Health Sciences, Wuyi University, Jiangmen, China.,School of Health and Biomedical Sciences, RMIT University, Melbourne, VIC, Australia.,School of Biomedical and Pharmaceutical Sciences, Guangdong University of Technology, Guangzhou, China
| | - Sherouk Fouda
- School of Health and Biomedical Sciences, RMIT University, Melbourne, VIC, Australia
| | - Xiao-Yi Zeng
- School of Health and Biomedical Sciences, RMIT University, Melbourne, VIC, Australia
| | - Dongli Li
- School of Biotechnology and Health Sciences, Wuyi University, Jiangmen, China
| | - Kun Zhang
- School of Biotechnology and Health Sciences, Wuyi University, Jiangmen, China.,School of Biomedical and Pharmaceutical Sciences, Guangdong University of Technology, Guangzhou, China
| | - Jun Xu
- School of Biotechnology and Health Sciences, Wuyi University, Jiangmen, China
| | - Ji-Ming Ye
- School of Biotechnology and Health Sciences, Wuyi University, Jiangmen, China.,School of Health and Biomedical Sciences, RMIT University, Melbourne, VIC, Australia
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Khowailed EA, Seddiek HA, Mahmoud MM, Rashed LA, Ibrahim FE. Effect of metformin on Sirtuin-1 disorders associated with diabetes in male rats. ALEXANDRIA JOURNAL OF MEDICINE 2019. [DOI: 10.1016/j.ajme.2017.09.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
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Bai XP, Dong F, Yang GH, Zhang L. Influences of sterol regulatory element binding protein-1c silencing on glucose production in HepG2 cells treated with free fatty acid. Lipids Health Dis 2019; 18:89. [PMID: 30954075 PMCID: PMC6451783 DOI: 10.1186/s12944-019-1026-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2018] [Accepted: 03/21/2019] [Indexed: 01/22/2023] Open
Abstract
BACKGROUND Elevation of exogenous free fatty acid (FFA) level leads to insulin resistance (IR) in liver, IR is manifested by elevated hepatic glucose production. We aim to study whether inhibition of endogenous fatty acid synthesis could decrease hepatic glucose production. METHODS Low-passage HepG2 cells derived from human liver tissue were cultured in medium supplemented with FFA to induce IR, the influences of sterol regulatory element binding protein-1c (SREBP-1c) silencing on glucose production of HepG2 cells were investigated, and genes responsible for fatty acid and glucose metabolism were detected by real-time PCR. RESULTS Compared with HepG2 cells cultured in normal growth medium, glucose production of HepG2 cells treated by FFA was significantly increased {[(0.28 ± 0.01) vs (0.83 ± 0.02)] umol.ug- 1 protein, n = 6 wells, P < 0.01}; the mRNA expression of phosphoenolpyruvate carboxylase kinase (PEPCK) and glucose-6-phosphatase (G6PC) in HepG2 cells increased by more than 5-fold and 3-fold, respectively; the mRNA expression of fatty acid synthase (FAS) and stearoyl-CoA desaturase-1 (SCD1) increased by approximately 4-fold and 1.1-fold, respectively; the mRNA expression of carnitine palmitoyltransferase-1 (CPT-1) changed slightly. Compared with the scrambled siRNA control, glucose production of HepG2 cells treated by FFA significantly increased after SREBP-1c silencing {[(0.018 ± 0.001) vs (0.028 ± 0.002)] umol.ug- 1 protein, n = 6 wells, P < 0.01}; the mRNA expression of PEPCK and G6PC increased by approximately 1.5-fold and 5-fold, respectively, but the mRNA expression of FAS, SCD1 and CPT-1 changed slightly. CONCLUSIONS SREBP-1c silencing further augmented glucose production of HepG2 cells treated by FFA significantly, genes responsible for fatty acid synthesis and gluconeogenesis played an important role in this process. SREBP-1c functions not only as a lipid regulator but also plays an important role in regulation of glucose metabolism.
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Affiliation(s)
- Xiu-Ping Bai
- Endocrinology Division, The Second Hospital of ShanXi Medical University, TaiYuan, 030001, ShanXi, China.
| | - Feng Dong
- Diabetes Division, University of Texas Health Science Center, San Antonio, TX, USA
| | - Guo-Hua Yang
- Central Laboratory, The Second Hospital of ShanXi Medical University, TaiYuan, 030001, ShanXi, China
| | - Lei Zhang
- Endocrinology Division, The Second Hospital of ShanXi Medical University, TaiYuan, 030001, ShanXi, China
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Zhou T, Xu X, Du M, Zhao T, Wang J. A preclinical overview of metformin for the treatment of type 2 diabetes. Biomed Pharmacother 2018; 106:1227-1235. [PMID: 30119191 DOI: 10.1016/j.biopha.2018.07.085] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2018] [Revised: 07/14/2018] [Accepted: 07/15/2018] [Indexed: 12/23/2022] Open
Abstract
Type 2 diabetes (T2D) is the most common type of diabetes mellitus and is mainly characterized by insulin resistance, β-cell dysfunction, and elevated hepatic glucose output. Metformin is a first-line antihyperglycemic agent that works mainly by regulating hepatic glucose production and peripheral insulin sensitivity. Metformin has been clinically applied for more than half a century, although the underlying pharmacological mechanisms remain elusive. This current review mainly focused on the development history of metformin and related preclinical studies on structural modification, pharmacological mechanisms for treatment of T2D, toxicology, pharmacokinetics, and pharmaceutics. The pharmacological function of metformin in lowering hyperglycemia suggests that multi-targeting could be an effective strategy for the discovery of new anti-diabetic drugs. A number of discoveries have revealed the pharmacologic mechanisms of metformin; however, precise mechanisms remain unclear. Deeper investigations on the biological features of metformin are expected to provide more rational applications and indications of this evergreen anti-T2D agent, which will in turn help to better understand the complicated pathogenesis of T2D.
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Affiliation(s)
- Tingting Zhou
- Wuxi School of Medicine, Jiangnan University, 1800 Lihu Road, Wuxi 214122, China; Shanghai Institute of Material Medica, Chinese Academy of Sciences, 555 Zuchongzhi Road, Shanghai 201203, China.
| | - Xin Xu
- Shanghai Institute of Material Medica, Chinese Academy of Sciences, 555 Zuchongzhi Road, Shanghai 201203, China
| | - Mengfan Du
- Wuxi School of Medicine, Jiangnan University, 1800 Lihu Road, Wuxi 214122, China
| | - Tong Zhao
- State Key Laboratory Cultivation Base for TCM Quality and Efficacy, School of Medicine and Life Sciences, Nanjing University of Chinese Medicine, 138 Xianlin Road, Nanjing 210023, China
| | - Jiaying Wang
- State Key Laboratory Cultivation Base for TCM Quality and Efficacy, School of Medicine and Life Sciences, Nanjing University of Chinese Medicine, 138 Xianlin Road, Nanjing 210023, China.
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Dawed AY, Ali A, Zhou K, Pearson ER, Franks PW. Evidence-based prioritisation and enrichment of genes interacting with metformin in type 2 diabetes. Diabetologia 2017; 60:2231-2239. [PMID: 28842730 PMCID: PMC6448905 DOI: 10.1007/s00125-017-4404-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/16/2017] [Accepted: 07/10/2017] [Indexed: 12/14/2022]
Abstract
AIMS/HYPOTHESIS There is an extensive body of literature suggesting the involvement of multiple loci in regulating the action of metformin; most findings lack replication, without which distinguishing true-positive from false-positive findings is difficult. To address this, we undertook evidence-based, multiple data integration to determine the validity of published evidence. METHODS We (1) built a database of published data on gene-metformin interactions using an automated text-mining approach (n = 5963 publications), (2) generated evidence scores for each reported locus, (3) from which a rank-ordered gene set was generated, and (4) determined the extent to which this gene set was enriched for glycaemic response through replication analyses in a well-powered independent genome-wide association study (GWAS) dataset from the Genetics of Diabetes and Audit Research Tayside Study (GoDARTS). RESULTS From the literature search, seven genes were identified that are related to the clinical outcomes of metformin. Fifteen genes were linked with either metformin pharmacokinetics or pharmacodynamics, and the expression profiles of a further 51 genes were found to be responsive to metformin. Gene-set enrichment analysis consisting of the three sets and two more composite sets derived from the above three showed no significant enrichment in four of the gene sets. However, we detected significant enrichment of genes in the least prioritised category (a gene set in which their expression is affected by metformin) with glycaemic response to metformin (p = 0.03). This gene set includes novel candidate genes such as SLC2A4 (p = 3.24 × 10-04) and G6PC (p = 4.77 × 10-04). CONCLUSIONS/INTERPRETATION We have described a semi-automated text-mining and evidence-scoring algorithm that facilitates the organisation and extraction of useful information about gene-drug interactions. We further validated the output of this algorithm in a drug-response GWAS dataset, providing novel candidate loci for gene-metformin interactions.
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Affiliation(s)
- Adem Y Dawed
- Division of Molecular and Clinical Medicine, Medical Research Institute, Ninewells Hospital and Medical School, Level 5, Mailbox 12, University of Dundee, Dundee, DD1 9SY, UK.
- Department of Clinical Sciences, Genetic and Molecular Epidemiology Unit, Lund University, Skåne University Hospital Malmö, Malmö, Sweden.
| | - Ashfaq Ali
- Department of Clinical Sciences, Genetic and Molecular Epidemiology Unit, Lund University, Skåne University Hospital Malmö, Malmö, Sweden
| | - Kaixin Zhou
- Division of Molecular and Clinical Medicine, Medical Research Institute, Ninewells Hospital and Medical School, Level 5, Mailbox 12, University of Dundee, Dundee, DD1 9SY, UK
| | - Ewan R Pearson
- Division of Molecular and Clinical Medicine, Medical Research Institute, Ninewells Hospital and Medical School, Level 5, Mailbox 12, University of Dundee, Dundee, DD1 9SY, UK
| | - Paul W Franks
- Department of Clinical Sciences, Genetic and Molecular Epidemiology Unit, Lund University, Skåne University Hospital Malmö, Malmö, Sweden
- Department of Public Health & Clinical Medicine, Umeå University, Umeå, Sweden
- Department of Nutrition, Harvard School of Public Health, Boston, MA, USA
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Chen Z, Ding L, Yang W, Wang J, Chen L, Chang Y, Geng B, Cui Q, Guan Y, Yang J. Hepatic Activation of the FAM3C-HSF1-CaM Pathway Attenuates Hyperglycemia of Obese Diabetic Mice. Diabetes 2017; 66:1185-1197. [PMID: 28246289 DOI: 10.2337/db16-0993] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/15/2016] [Accepted: 02/18/2017] [Indexed: 11/13/2022]
Abstract
FAM3C is a member of the family with sequence similarity 3 (FAM3) gene family, and this study determined its role and mechanism in regulation of hepatic glucose/lipid metabolism. In obese diabetic mice, FAM3C expression was reduced in the liver, and hepatic FAM3C restoration improved insulin resistance, hyperglycemia, and fatty liver. FAM3C overexpression increased the expression of heat shock factor 1 (HSF1), calmodulin (CaM), and phosphorylated protein kinase B (Akt) and reduced that of gluconeogenic and lipogenic genes in diabetic mouse livers with the suppression of gluconeogenesis and lipid deposition. In cultured hepatocytes, FAM3C overexpression upregulated HSF1 expression, which elevated CaM protein level by inducing CALM1 transcription to activate Akt in a Ca2+- and insulin-independent manner. Furthermore, FAM3C overexpression promoted nuclear exclusion of FOXO1 and repressed gluconeogenic gene expression and gluconeogenesis in a CaM-dependent manner in hepatocytes. Hepatic HSF1 overexpression activated the CaM-Akt pathway to repress gluconeogenic and lipogenic gene expression and improve hyperglycemia and fatty liver in obese diabetic mice. In conclusion, the FAM3C-HSF1-CaM-Akt pathway plays important roles in regulating glucose and lipid metabolism in hepatocytes independent of insulin and calcium. Restoring hepatic FAM3C expression is beneficial for the management of type 2 diabetes and fatty liver.
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Affiliation(s)
- Zhenzhen Chen
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Key Laboratory of Molecular Cardiovascular Science of the Ministry of Education, Center for Non-coding RNA Medicine, Peking University Health Science Center, Beijing, China
| | - Liwei Ding
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Key Laboratory of Molecular Cardiovascular Science of the Ministry of Education, Center for Non-coding RNA Medicine, Peking University Health Science Center, Beijing, China
| | - Weili Yang
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Key Laboratory of Molecular Cardiovascular Science of the Ministry of Education, Center for Non-coding RNA Medicine, Peking University Health Science Center, Beijing, China
| | - Junpei Wang
- Department of Biomedical Informatics, School of Basic Medical Sciences, Key Laboratory of Molecular Cardiovascular Science of the Ministry of Education, Center for Non-coding RNA Medicine, Peking University Health Science Center, Beijing, China
| | - Liming Chen
- Department of Biophysics and Molecular Physiology, Key Laboratory of Molecular Biophysics of Ministry of Education, Huazhong University of Science & Technology School of Life Science & Technology, Wuhan, China
| | - Yongsheng Chang
- National Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Bin Geng
- Hypertension Center, Fuwai Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Qinghua Cui
- Department of Biomedical Informatics, School of Basic Medical Sciences, Key Laboratory of Molecular Cardiovascular Science of the Ministry of Education, Center for Non-coding RNA Medicine, Peking University Health Science Center, Beijing, China
| | - Youfei Guan
- Advanced Institute for Medical Sciences, Dalian Medical University, Dalian, China
| | - Jichun Yang
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Key Laboratory of Molecular Cardiovascular Science of the Ministry of Education, Center for Non-coding RNA Medicine, Peking University Health Science Center, Beijing, China
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Karise I, Ornellas F, Barbosa-da-Silva S, Matsuura C, Del Sol M, Aguila MB, Mandarim-de-Lacerda CA. Liver and Metformin: Lessons of a fructose diet in mice. BIOCHIMIE OPEN 2017; 4:19-30. [PMID: 29450137 PMCID: PMC5801827 DOI: 10.1016/j.biopen.2017.01.002] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/26/2016] [Accepted: 01/27/2017] [Indexed: 12/11/2022]
Abstract
Studies show that the continuous consumption of fructose can lead to nonalcoholic fatty liver disease (NAFLD) and steatohepatitis. We aimed to investigate the role of Metformin in an animal model of liver injury caused by fructose intake, focusing on the molecular markers of lipogenesis, beta-oxidation, and antioxidant defenses. Male three months old C57BL/6 mice were divided into control group (C) and fructose group (F, 47% fructose), maintained for ten weeks. After, the groups received Metformin or vehicle for a further eight weeks: control (C), control + Metformin (CM), fructose (F), and fructose + Metformin (FM). Fructose resulted in hepatic steatosis, insulin resistance and lower insulin sensitivity in association with higher mRNA levels of proteins linked with de novo lipogenesis and increased lipid peroxidation. Fructose diminished mRNA expression of antioxidant enzymes, and of proteins responsible for mitochondrial biogenesis. Metformin reduced de novo lipogenesis and increased the expression of proteins related to mitochondrial biogenesis, thereby increasing beta-oxidation and decreasing lipid peroxidation. Also, Metformin upregulated the expression and activity of antioxidant enzymes, providing a defense against increased reactive oxygen species generation. Therefore, a significant reduction in triglyceride accumulation in the liver, steatosis and lipid peroxidation was observed in the FM group. In conclusion, fructose increases de novo lipogenesis, reduces the antioxidant defenses, and diminishes mitochondrial biogenesis. After an extended period of fructose intake, Metformin treatment, even in continuing the fructose intake, can reverse, at least partially, the liver injury and prevents NAFLD progression to more severe states. Fructose increases lipogenesis and lipid peroxidation, reduces the antioxidant defenses, and mitochondrial biogenesis. Metformin mechanism of action remains partially understood and controversial. Metformin can reverse the liver injury preventing the progression to more severe states.
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Affiliation(s)
- Iara Karise
- Laboratory of Morphometry, Metabolism, and Cardiovascular Diseases, Biomedical Center, Institute of Biology, State University of Rio de Janeiro, Brazil
| | - Fernanda Ornellas
- Laboratory of Morphometry, Metabolism, and Cardiovascular Diseases, Biomedical Center, Institute of Biology, State University of Rio de Janeiro, Brazil
| | - Sandra Barbosa-da-Silva
- Laboratory of Morphometry, Metabolism, and Cardiovascular Diseases, Biomedical Center, Institute of Biology, State University of Rio de Janeiro, Brazil
| | - Cristiane Matsuura
- Laboratory of Membrane Transport, Biomedical Center, Institute of Biology, State University of Rio de Janeiro, Brazil
| | - Mariano Del Sol
- Doctoral Programing on Morphological Sciences, Universidad de La Frontera, Temuco, Chile
| | - Marcia Barbosa Aguila
- Laboratory of Morphometry, Metabolism, and Cardiovascular Diseases, Biomedical Center, Institute of Biology, State University of Rio de Janeiro, Brazil.,Doctoral Programing on Morphological Sciences, Universidad de La Frontera, Temuco, Chile
| | - Carlos A Mandarim-de-Lacerda
- Laboratory of Morphometry, Metabolism, and Cardiovascular Diseases, Biomedical Center, Institute of Biology, State University of Rio de Janeiro, Brazil.,Doctoral Programing on Morphological Sciences, Universidad de La Frontera, Temuco, Chile
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12
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Remington GJ, Teo C, Wilson V, Chintoh A, Guenette M, Ahsan Z, Giacca A, Hahn MK. Metformin attenuates olanzapine-induced hepatic, but not peripheral insulin resistance. J Endocrinol 2015; 227:71-81. [PMID: 26330531 DOI: 10.1530/joe-15-0074] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 09/01/2015] [Indexed: 11/08/2022]
Abstract
Antipsychotics (APs) are linked to diabetes, even without weight gain. Whether anti-diabetic drugs are efficacious in reversing the direct effects of APs on glucose pathways is largely undetermined. We tested two metformin (Met) doses to prevent impairments seen following a dose of olanzapine (Ola) (3 mg/kg); glucokinetics were measured using the hyperinsulinemic-euglycemic clamp (HIEC). Met (150 mg/kg; n=13, or 400 mg/kg; n=11) or vehicle (Veh) (n=11) was administered through gavage preceding an overnight fast, followed by a second dose prior to the HIEC. Eleven additional animals were gavaged with Veh and received a Veh injection during the HIEC (Veh/Veh); all others received Ola. Basal glucose was similar across treatment groups. The Met 400 group had significantly greater glucose appearance (Ra) in the basal period (i.e., before Ola, or hyperinsulinemia) vs other groups. During hyperinsulinemia, glucose infusion rate (GINF) to maintain euglycemia (reflective of whole-body insulin sensitivity) was higher in Veh/Veh vs other groups. Met 150/Ola animals demonstrated increased GINF relative to Veh/Ola during early time points of the HIEC. Glucose utilization during hyperinsulinemia, relative to basal conditions, was significantly higher in Veh/Veh vs other groups. The change in hepatic glucose production (HGP) from basal to hyperinsulinemia demonstrated significantly greater decreases in Veh/Veh and Met 150/Ola groups vs Veh/Ola. Given the increase in basal Ra with Met 400, we measured serum lactate (substrate for HGP), finding increased levels in Met 400 vs Veh and Met 150. In conclusion, Met attenuates hepatic insulin resistance observed with acute Ola administration, but fails to improve peripheral insulin resistance. Use of supra-therapeutic doses of Met may mask metabolic benefits by increasing lactate.
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Affiliation(s)
- Gary J Remington
- Centre for Addiction and Mental Health250 College Street, Toronto, Ontario, Canada M5T 1R8Institute of Medical ScienceUniversity of Toronto, 1 King's College Circle, Toronto, Ontario, Canada M5S 1A8Department of PsychiatryUniversity of Toronto, 250 College Street, Toronto, Ontario, Canada M5T 1R8Department of PhysiologyUniversity of Toronto, 1 King's College Circle, Toronto, Ontario, Canada M5S 1A8 Centre for Addiction and Mental Health250 College Street, Toronto, Ontario, Canada M5T 1R8Institute of Medical ScienceUniversity of Toronto, 1 King's College Circle, Toronto, Ontario, Canada M5S 1A8Department of PsychiatryUniversity of Toronto, 250 College Street, Toronto, Ontario, Canada M5T 1R8Department of PhysiologyUniversity of Toronto, 1 King's College Circle, Toronto, Ontario, Canada M5S 1A8 Centre for Addiction and Mental Health250 College Street, Toronto, Ontario, Canada M5T 1R8Institute of Medical ScienceUniversity of Toronto, 1 King's College Circle, Toronto, Ontario, Canada M5S 1A8Department of PsychiatryUniversity of Toronto, 250 College Street, Toronto, Ontario, Canada M5T 1R8Department of PhysiologyUniversity of Toronto, 1 King's College Circle, Toronto, Ontario, Canada M5S 1A8
| | - Celine Teo
- Centre for Addiction and Mental Health250 College Street, Toronto, Ontario, Canada M5T 1R8Institute of Medical ScienceUniversity of Toronto, 1 King's College Circle, Toronto, Ontario, Canada M5S 1A8Department of PsychiatryUniversity of Toronto, 250 College Street, Toronto, Ontario, Canada M5T 1R8Department of PhysiologyUniversity of Toronto, 1 King's College Circle, Toronto, Ontario, Canada M5S 1A8
| | - Virginia Wilson
- Centre for Addiction and Mental Health250 College Street, Toronto, Ontario, Canada M5T 1R8Institute of Medical ScienceUniversity of Toronto, 1 King's College Circle, Toronto, Ontario, Canada M5S 1A8Department of PsychiatryUniversity of Toronto, 250 College Street, Toronto, Ontario, Canada M5T 1R8Department of PhysiologyUniversity of Toronto, 1 King's College Circle, Toronto, Ontario, Canada M5S 1A8
| | - Araba Chintoh
- Centre for Addiction and Mental Health250 College Street, Toronto, Ontario, Canada M5T 1R8Institute of Medical ScienceUniversity of Toronto, 1 King's College Circle, Toronto, Ontario, Canada M5S 1A8Department of PsychiatryUniversity of Toronto, 250 College Street, Toronto, Ontario, Canada M5T 1R8Department of PhysiologyUniversity of Toronto, 1 King's College Circle, Toronto, Ontario, Canada M5S 1A8 Centre for Addiction and Mental Health250 College Street, Toronto, Ontario, Canada M5T 1R8Institute of Medical ScienceUniversity of Toronto, 1 King's College Circle, Toronto, Ontario, Canada M5S 1A8Department of PsychiatryUniversity of Toronto, 250 College Street, Toronto, Ontario, Canada M5T 1R8Department of PhysiologyUniversity of Toronto, 1 King's College Circle, Toronto, Ontario, Canada M5S 1A8
| | - Melanie Guenette
- Centre for Addiction and Mental Health250 College Street, Toronto, Ontario, Canada M5T 1R8Institute of Medical ScienceUniversity of Toronto, 1 King's College Circle, Toronto, Ontario, Canada M5S 1A8Department of PsychiatryUniversity of Toronto, 250 College Street, Toronto, Ontario, Canada M5T 1R8Department of PhysiologyUniversity of Toronto, 1 King's College Circle, Toronto, Ontario, Canada M5S 1A8
| | - Zohra Ahsan
- Centre for Addiction and Mental Health250 College Street, Toronto, Ontario, Canada M5T 1R8Institute of Medical ScienceUniversity of Toronto, 1 King's College Circle, Toronto, Ontario, Canada M5S 1A8Department of PsychiatryUniversity of Toronto, 250 College Street, Toronto, Ontario, Canada M5T 1R8Department of PhysiologyUniversity of Toronto, 1 King's College Circle, Toronto, Ontario, Canada M5S 1A8
| | - Adria Giacca
- Centre for Addiction and Mental Health250 College Street, Toronto, Ontario, Canada M5T 1R8Institute of Medical ScienceUniversity of Toronto, 1 King's College Circle, Toronto, Ontario, Canada M5S 1A8Department of PsychiatryUniversity of Toronto, 250 College Street, Toronto, Ontario, Canada M5T 1R8Department of PhysiologyUniversity of Toronto, 1 King's College Circle, Toronto, Ontario, Canada M5S 1A8 Centre for Addiction and Mental Health250 College Street, Toronto, Ontario, Canada M5T 1R8Institute of Medical ScienceUniversity of Toronto, 1 King's College Circle, Toronto, Ontario, Canada M5S 1A8Department of PsychiatryUniversity of Toronto, 250 College Street, Toronto, Ontario, Canada M5T 1R8Department of PhysiologyUniversity of Toronto, 1 King's College Circle, Toronto, Ontario, Canada M5S 1A8
| | - Margaret K Hahn
- Centre for Addiction and Mental Health250 College Street, Toronto, Ontario, Canada M5T 1R8Institute of Medical ScienceUniversity of Toronto, 1 King's College Circle, Toronto, Ontario, Canada M5S 1A8Department of PsychiatryUniversity of Toronto, 250 College Street, Toronto, Ontario, Canada M5T 1R8Department of PhysiologyUniversity of Toronto, 1 King's College Circle, Toronto, Ontario, Canada M5S 1A8 Centre for Addiction and Mental Health250 College Street, Toronto, Ontario, Canada M5T 1R8Institute of Medical ScienceUniversity of Toronto, 1 King's College Circle, Toronto, Ontario, Canada M5S 1A8Department of PsychiatryUniversity of Toronto, 250 College Street, Toronto, Ontario, Canada M5T 1R8Department of PhysiologyUniversity of Toronto, 1 King's College Circle, Toronto, Ontario, Canada M5S 1A8 Centre for Addiction and Mental Health250 College Street, Toronto, Ontario, Canada M5T 1R8Institute of Medical ScienceUniversity of Toronto, 1 King's College Circle, Toronto, Ontario, Canada M5S 1A8Department of PsychiatryUniversity of Toronto, 250 College Street, Toronto, Ontario, Canada M5T 1R8Department of PhysiologyUniversity of Toronto, 1 King's College Circle, Toronto, Ontario, Canada M5S 1A8
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13
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Rosiglitazone, but not epigallocatechin-3-gallate, attenuates the decrease in PGC-1α protein levels in palmitate-induced insulin-resistant C2C12 cells. Lipids 2015; 50:521-8. [PMID: 25893813 DOI: 10.1007/s11745-015-4016-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2014] [Accepted: 03/27/2015] [Indexed: 01/29/2023]
Abstract
Alteration of lipid metabolism is an important mechanism for the treatment of insulin resistance. PGC-1α, a key regulator of mitochondrial biogenesis and function, plays an important role in the improvement of insulin sensitivity by increasing fatty acids β-oxidation. In the present study, the effects of epigallocatechin-3-gallate (EGCG), an anti-obesity agent and enhancer of lipid catabolism, on PGC-1α protein expression was examined and compared with anti-diabetic drug rosiglitazone (RGZ). After differentiation of C2C12 myoblasts to myotubes, insulin resistance was induced by palmitate treatment. Then the expression of the PGC-1a gene and glucose uptake were evaluated before and after treatment with RGZ and EGCG. Palmitate treatment significantly decreased PGC-1α protein expression in C2C12 cells (P < 0.05). RGZ could restore the expression of PGC-1α in palmitate treated cells (P > 0.05), while EGCG had no significant effect on the expression of this gene (P < 0.05). RGZ and EGCG significantly improved glucose uptake (by 2- and 1.54-fold, respectively) in myotubes treated with palmitate. These data suggest that RGZ and EGCG both exert their anti-diabetic activity by increasing insulin sensitivity, but with different molecular mechanisms. This effect of RGZ, unlike EGCG, is mediated, at least partly, by increasing PGC-1α protein expression.
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Tan S, Vollmar N, Benson S, Sowa JP, Bechmann LP, Gerken G, Fuhrer D, Canbay A. Liver Injury Indicating Fatty Liver but Not Serologic NASH Marker Improves under Metformin Treatment in Polycystic Ovary Syndrome. Int J Endocrinol 2015; 2015:254169. [PMID: 25873949 PMCID: PMC4383456 DOI: 10.1155/2015/254169] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/28/2014] [Revised: 02/18/2015] [Accepted: 02/27/2015] [Indexed: 12/12/2022] Open
Abstract
Objective. Polycystic ovary syndrome (PCOS) is associated with obesity and insulin resistance (IR), key features of nonalcoholic steatohepatitis (NASH). Cytokeratin 18 fragments (M30) have been established as a serum marker for NASH. The insulin sensitizer metformin improves hepatic IR. This study evaluates the influence of MF on serologic NASH (sNASH) in patients with PCOS. Patients and Methods. In 89 patients, metabolic parameters, liver injury indicating fatty liver (LIFL), and M30 were assessed at baseline and after metformin treatment. Patients with initial IR were subdivided into dissolved (PCOS-exIR) and persistent IR (PCOS-PIR) after treatment and compared to an initially insulin sensitive PCOS group (PCOS-C). Results. Improvement of LIFL prevalence could be seen in PCOS-C and PCOS-exIR compared to PCOS-PIR (-19.4, resp., -12.0% versus 7.2%, Chi(2) = 29.5, P < 0.001) without change in sNASH prevalence. In PCOS-PIR, ALT levels increased significantly accompanied by a nominal, nonsignificant M30 increase. Conclusions. Metformin improves LIFL in subgroups of patients with PCOS without influencing sNASH. This could either indicate a missing effect of metformin on NAFLD or slowed disease progression. Further studies are needed to elucidate NAFLD in the context of PCOS and potential therapeutic options.
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Affiliation(s)
- Susanne Tan
- Department of Endocrinology and Division of Laboratory Research, University Hospital, University of Duisburg-Essen, Hufelandstraße 55, 45147 Essen, Germany
| | - Nils Vollmar
- Department of Endocrinology and Division of Laboratory Research, University Hospital, University of Duisburg-Essen, Hufelandstraße 55, 45147 Essen, Germany
| | - Sven Benson
- Institute of Medical Psychology and Behavioral Immunobiology, University Hospital, University of Duisburg-Essen, Hufelandstraße 55, 45147 Essen, Germany
| | - Jan-Peter Sowa
- Department of Gastroenterology and Hepatology, University Hospital, University of Duisburg-Essen, Hufelandstraße 55, 45147 Essen, Germany
| | - Lars P. Bechmann
- Department of Gastroenterology and Hepatology, University Hospital, University of Duisburg-Essen, Hufelandstraße 55, 45147 Essen, Germany
| | - Guido Gerken
- Department of Gastroenterology and Hepatology, University Hospital, University of Duisburg-Essen, Hufelandstraße 55, 45147 Essen, Germany
| | - Dagmar Fuhrer
- Department of Endocrinology and Division of Laboratory Research, University Hospital, University of Duisburg-Essen, Hufelandstraße 55, 45147 Essen, Germany
| | - Ali Canbay
- Department of Gastroenterology and Hepatology, University Hospital, University of Duisburg-Essen, Hufelandstraße 55, 45147 Essen, Germany
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15
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Conde de la Rosa L, Vrenken TE, Buist-Homan M, Faber KN, Moshage H. Metformin protects primary rat hepatocytes against oxidative stress-induced apoptosis. Pharmacol Res Perspect 2015; 3:e00125. [PMID: 26038701 PMCID: PMC4448984 DOI: 10.1002/prp2.125] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2014] [Revised: 01/05/2015] [Accepted: 01/14/2015] [Indexed: 12/21/2022] Open
Abstract
The majority of chronic liver diseases are accompanied by oxidative stress, which induces apoptosis in hepatocytes and liver injury. Recent studies suggest that oxidative stress and insulin resistance are important in the pathogenesis of nonalcoholic fatty liver disease (NAFLD) and the pathophysiology of diabetes complications. Metformin has been shown to be hepatoprotective in the insulin-resistant and leptin-deficient ob/ob mouse model of NAFLD. However, the mechanism involved in the protective effects of metformin has not been elucidated yet. Therefore, we investigated the protective effect of metformin against oxidative stress-induced apoptosis. Primary rat hepatocytes were exposed to the oxidative stress-generating compound menadione in the presence and absence of metformin. Apoptosis was determined by measuring caspase activity and poly(ADP-ribose) polymerase (PARP)-cleavage, and necrosis was measured by Sytox Green nuclear staining. We demonstrate that (1) Metformin inhibits menadione-induced caspase-9,-6,-3 activation and PARP-cleavage in a concentration-dependent manner. (2) Metformin increases menadione-induced heme oxygenase-1 (HO-1) expression and inhibits c-Jun N-terminal kinase (JNK)-phosphorylation. (3) Metformin does not induce necrosis in primary hepatocytes. Metformin protects hepatocytes against oxidative stress-induced caspase activation, PARP-cleavage and apoptosis. The anti-apoptotic effect of metformin is in part dependent on HO-1 and bcl-xl induction and inhibition of JNK activation and independent of insulin signaling. Our results elucidate novel protective mechanisms of metformin and indicate that metformin could be investigated as a novel therapeutic agent for the treatment of oxidative stress-related liver diseases.
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Affiliation(s)
- Laura Conde de la Rosa
- Department of Gastroenterology and Hepatology, University Medical Center Groningen, University of Groningen Groningen, The Netherlands
| | - Titia E Vrenken
- Department of Gastroenterology and Hepatology, University Medical Center Groningen, University of Groningen Groningen, The Netherlands
| | - Manon Buist-Homan
- Department of Gastroenterology and Hepatology, University Medical Center Groningen, University of Groningen Groningen, The Netherlands
| | - Klaas Nico Faber
- Department of Gastroenterology and Hepatology, University Medical Center Groningen, University of Groningen Groningen, The Netherlands
| | - Han Moshage
- Department of Gastroenterology and Hepatology, University Medical Center Groningen, University of Groningen Groningen, The Netherlands
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Kowalski GM, Bruce CR. The regulation of glucose metabolism: implications and considerations for the assessment of glucose homeostasis in rodents. Am J Physiol Endocrinol Metab 2014; 307:E859-71. [PMID: 25205823 DOI: 10.1152/ajpendo.00165.2014] [Citation(s) in RCA: 93] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The incidence of insulin resistance and type 2 diabetes (T2D) is increasing at alarming rates. In the quest to understand the underlying causes of and to identify novel therapeutic targets to treat T2D, scientists have become increasingly reliant on the use of rodent models. Here, we provide a discussion on the regulation of rodent glucose metabolism, highlighting key differences and similarities that exist between rodents and humans. In addition, some of the issues and considerations associated with assessing glucose homeostasis and insulin action are outlined. We also discuss the role of the liver vs. skeletal muscle in regulating whole body glucose metabolism in rodents, emphasizing the importance of defective hepatic glucose metabolism in the development of impaired glucose tolerance, insulin resistance, and T2D.
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Affiliation(s)
- Greg M Kowalski
- Centre for Physical Activity and Nutrition Research, School of Exercise and Nutrition Sciences, Deakin University, Burwood, Victoria, Australia
| | - Clinton R Bruce
- Centre for Physical Activity and Nutrition Research, School of Exercise and Nutrition Sciences, Deakin University, Burwood, Victoria, Australia
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17
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Metformin raises hydrogen sulfide tissue concentrations in various mouse organs. Pharmacol Rep 2014; 65:737-42. [PMID: 23950598 DOI: 10.1016/s1734-1140(13)71053-3] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2012] [Revised: 12/11/2012] [Indexed: 11/20/2022]
Abstract
BACKGROUND The epidemic of diabetes mellitus type 2 forces to intensive work on the disease medication. Metformin, the most widely prescribed insulin sensitizer, exerts pleiotropic actions on different tissues by not fully recognized mechanisms. Hydrogen sulfide (H2S) is involved in physiology and pathophysiology of various systems in mammals and is perceived as a potential agent in the treatment of different disorders. The interaction between biguanides and H2S is unknown. The aim of the study is to assess the influence of metformin on the H2S tissue concentrations in different mouse organs. METHODS Adult SJL female mice were administered intraperitoneally 100 mg/kg b.w. per day of metformin (group D1, n = 6) or 200 mg/kg b.w. per day of metformin (group D2, n = 7). The control group (n = 6) received physiological saline. The measurements of the free and acid-labile H2S tissue concentrations were performed with Siegel spectrophotometric modified method. RESULTS There was a significant progressive increase in the H2S concentration along with the rising metformin doses as compared to the control group in the brain (D1 by 103.6%, D2 by 113.5%), in the heart (D1 by 11.7%, D2 by 27.5%) and in the kidney (D1 by 7.1%, D2 by 9.6%). In the liver, massive H2S accumulation was observed in the group D1 (increase by 420.4%), while in the D2 group only slight H2S level enhancement was noted (by 12.5%). CONCLUSION Our experiment has shown that metformin administration is followed by H2S tissue concentrations increase in mouse brain, heart, kidney and liver.
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18
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Cleasby ME, Jarmin S, Eilers W, Elashry M, Andersen DK, Dickson G, Foster K. Local overexpression of the myostatin propeptide increases glucose transporter expression and enhances skeletal muscle glucose disposal. Am J Physiol Endocrinol Metab 2014; 306:E814-23. [PMID: 24473441 PMCID: PMC3962614 DOI: 10.1152/ajpendo.00586.2013] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/21/2013] [Accepted: 01/28/2014] [Indexed: 12/20/2022]
Abstract
Insulin resistance (IR) in skeletal muscle is a prerequisite for type 2 diabetes and is often associated with obesity. IR also develops alongside muscle atrophy in older individuals in sarcopenic obesity. The molecular defects that underpin this syndrome are not well characterized, and there is no licensed treatment. Deletion of the transforming growth factor-β family member myostatin, or sequestration of the active peptide by overexpression of the myostatin propeptide/latency-associated peptide (ProMyo) results in both muscle hypertrophy and reduced obesity and IR. We aimed to establish whether local myostatin inhibition would have a paracrine/autocrine effect to enhance glucose disposal beyond that simply generated by increased muscle mass, and the mechanisms involved. We directly injected adeno-associated virus expressing ProMyo in right tibialis cranialis/extensor digitorum longus muscles of rats and saline in left muscles and compared the effects after 17 days. Both test muscles were increased in size (by 7 and 11%) and showed increased radiolabeled 2-deoxyglucose uptake (26 and 47%) and glycogen storage (28 and 41%) per unit mass during an intraperitoneal glucose tolerance test. This was likely mediated through increased membrane protein levels of GLUT1 (19% higher) and GLUT4 (63% higher). Interestingly, phosphorylation of phosphoinositol 3-kinase signaling intermediates and AMP-activated kinase was slightly decreased, possibly because of reduced expression of insulin-like growth factor-I in these muscles. Thus, myostatin inhibition has direct effects to enhance glucose disposal in muscle beyond that expected of hypertrophy alone, and this approach may offer potential for the therapy of IR syndromes.
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Affiliation(s)
- M. E. Cleasby
- Department of Comparative Biomedical Sciences, Royal Veterinary College, University of London, London, United Kingdom
| | - S. Jarmin
- School of Biological Sciences, Royal Holloway, University of London, Egham, Surrey, United Kingdom; and
| | - W. Eilers
- School of Biological Sciences, University of Reading, Reading, Berkshire, United Kingdom
| | - M. Elashry
- School of Biological Sciences, University of Reading, Reading, Berkshire, United Kingdom
| | - D. K. Andersen
- Department of Comparative Biomedical Sciences, Royal Veterinary College, University of London, London, United Kingdom
| | - G. Dickson
- School of Biological Sciences, Royal Holloway, University of London, Egham, Surrey, United Kingdom; and
| | - K. Foster
- School of Biological Sciences, University of Reading, Reading, Berkshire, United Kingdom
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19
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Kendall DL, Amin R, Clayton PE. Metformin in the treatment of obese children and adolescents at risk of type 2 diabetes. Paediatr Drugs 2014; 16:13-20. [PMID: 23949947 DOI: 10.1007/s40272-013-0045-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Metformin is the first-line treatment for type 2 diabetes (T2D) in adults, children and young people, particularly in obese or overweight patients. Many studies have demonstrated that metformin is associated with weight reduction in adults and in prevention or delay of T2D onset in those who are at increased risk. In 2012, metformin was recommended by the UK National Institute for Health and Care Excellence as a treatment option in adults aged 18 years or over, who remain at high risk of T2D, despite participation in an intensive lifestyle-change programme. Prevalence of childhood obesity is increasing and is associated with elevated long-term risk of T2D and other adverse cardio-metabolic events; however, consensus is lacking on intervention strategies aimed at reducing this risk. This article discusses the rationale and evidence for the use of metformin in obese children and young people at high risk of T2D.
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Affiliation(s)
- Deborah L Kendall
- Lancashire Teaching Hospitals NHS Foundation Trust, Royal Preston Hospital, Sharoe Green Lane, Preston, PR2 9HT, UK,
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20
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Lee HY, Wei D, Loeken MR. Lack of metformin effect on mouse embryo AMPK activity: implications for metformin treatment during pregnancy. Diabetes Metab Res Rev 2014; 30:23-30. [PMID: 23983188 PMCID: PMC3992340 DOI: 10.1002/dmrr.2451] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/20/2012] [Revised: 08/07/2013] [Accepted: 08/20/2013] [Indexed: 12/17/2022]
Abstract
BACKGROUND Adenosine monophosphate-activated protein kinase (AMPK) is stimulated in embryos during diabetic pregnancy by maternal hyperglycaemia-induced embryo oxidative stress. Stimulation of AMPK disrupts embryo gene expression and causes neural tube defects. Metformin, which may be taken during early pregnancy, has been reported to stimulate AMPK activity. Thus, the benefits of improved glycaemic control could be offset by stimulated embryo AMPK activity. Here, we investigated whether metformin can stimulate AMPK activity in mouse embryos and can adversely affect embryo gene expression and neural tube defects. METHODS Pregnant nondiabetic mice were administered metformin beginning on the first day of pregnancy. Activation of maternal and embryo AMPK [phospho-AMPK α (Thr172) relative to total AMPK], expression of Pax3, a gene required for neural tube closure, and neural tube defects were studied. Mouse embryonic stem cells were used as a cell culture model of embryonic neuroepithelium to study metformin effects on AMPK and Pax3 expression. RESULTS Metformin had no effect on AMPK in embryos or maternal skeletal muscle but increased activated AMPK in maternal liver. Metformin did not inhibit Pax3 expression or increase neural tube defects. However, metformin increased activated AMPK and inhibited Pax3 expression by mouse embryonic stem cells. Mate1/Slc47a1 and Oct3/Slc22a, which encode metformin transporters, were expressed at barely detectable levels by embryos. CONCLUSIONS Although metformin can have effects associated with diabetic embryopathy in vitro, the lack of effects on mouse embryos in vivo may be due to lack of metformin transporters and indicates that the benefits of metformin on glycaemic control are not counteracted by stimulation of embryo AMPK activity and consequent embryopathy.
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Affiliation(s)
- Hyung-yul Lee
- Section on Islet Cell and Regenerative Biology, Joslin Diabetes Center, Boston, MA, USA
- Department of Medicine, Harvard Medical School, Boston, MA, USA
| | - Dan Wei
- Section on Islet Cell and Regenerative Biology, Joslin Diabetes Center, Boston, MA, USA
- Department of Medicine, Harvard Medical School, Boston, MA, USA
| | - Mary R. Loeken
- Section on Islet Cell and Regenerative Biology, Joslin Diabetes Center, Boston, MA, USA
- Department of Medicine, Harvard Medical School, Boston, MA, USA
- Correspondence to: Mary R. Loeken, Section on Islet Cell and Regenerative Biology, Joslin Diabetes Center, One Place, Boston, MA 02215, USA.
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Wang F, Yan J, Niu Y, Li Y, Lin H, Liu X, Liu J, Li L. Mangiferin and its aglycone, norathyriol, improve glucose metabolism by activation of AMP-activated protein kinase. PHARMACEUTICAL BIOLOGY 2014; 52:68-73. [PMID: 24033319 DOI: 10.3109/13880209.2013.814691] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
CONTEXT Mangiferin has been reported to possess antidiabetic activities. Norathyriol, a xanthone aglycone, has the same structure as mangiferin, except for a C-glucosyl bond. To our best knowledge, no study has been conducted to determine and compare those two compounds on glucose consumption in vitro. OBJECTIVE In this study, the effects of norathyriol and mangiferin on glucose consumption in normal and insulin resistance (IR) L6 myotubes were evaluated. Simultaneously, the potential mechanism of this effect was also investigated. MATERIALS AND METHODS Normal or IR L6 myotubes were incubated with norathyriol (2.5 ∼ 10 μM, 0.625 ∼ 2.5 μM), mangiferin (10 ∼ 40 μM, 2.5 ∼ 10 μM) or rosiglitazone (20 μM) and/or 0.05 nM insulin for 24 h, respectively. The glucose consumption was assessed using the glucose oxidase method. Immunoblotting was performed to detect protein kinase B (PKB/Akt) and AMP-activated protein kinase (AMPK) phosphorylation in L6 myotubes cells. RESULTS Norathyriol and mangiferin treatment alone increased the glucose consumption 61.9 and 56.3%, respectively, in L6 myotubes and made additional increasing with 0.05 nM insulin. In IR L6 myotubes, norathyriol treatment made increasing with or without insulin, mangiferin treatment also made increasing but only when co-treated with insulin. Immunoblotting results showed that norathyriol and mangiferin produced an increase of 1.9 - and 1.8-fold in the phosphorylation levels of the AMPK, but not in Akt. DISCUSSION AND CONCLUSION Our findings suggest that norathyriol and mangiferin could improve the glucose utilization and insulin sensitivity by up-regulation of the phosphorylation of AMPK. Norathyriol may be considered as an active metabolite responsible for the antidiabetic activity of mangiferin.
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Affiliation(s)
- Fang Wang
- Biomedical Engineering Research Center, Kunming Medical University , Kunming , China
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Wang YL, Xiao ZQ, Liu S, Wan LS, Yue YD, Zhang YT, Liu ZX, Chen JC. Antidiabetic effects of Swertia macrosperma extracts in diabetic rats. JOURNAL OF ETHNOPHARMACOLOGY 2013; 150:536-544. [PMID: 24055468 DOI: 10.1016/j.jep.2013.08.053] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2013] [Revised: 08/03/2013] [Accepted: 08/31/2013] [Indexed: 06/02/2023]
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE Swertia macrosperma is a traditional folk medicine used for its anti-hepatitis, antipyretic and antidotal effects as "Dida" or "Zangyinchen" in Tibet, Yunnan and Guizhou province for a long time, and it has been reported for its anti-diabetic effects in a Chinese patent. Swertia macrosperma was reported rich in xanthones, iridoids, seco-iridoids and their glycosides, several of which had been documented as potential antidiabetic agents. The objective of this study was to investigate the antidiabetic effect of Swertia macrosperma in diabetic rats. MATERIALS AND METHODS This study was designed firstly to evaluate the effect of Swertia macrosperma on glucose consumption in HepG2 cells. Based on the result in HepG2 cells, the antidiabetic effect of ethanol extract (EE) and n-butanol extract (BE) were investigated in diabetic rats induced by high fat fed and streptozotocin. The effects of EE and BE on fasting blood glucose, oral glucose tolerance test, serum insulin, glycosylated hemoglobin, serum lipid level, serum antioxidant parameters, glucokinase, glucose-6-phosphatase activities and glycogen content in liver tissue were measured, histology examination of pancreatic tissue was also carried out. RESULTS After 4 weeks treatment with EE and BE, apparently decreased fasting blood glucose concentrations were observed in these treated groups, compared with the diabetic control groups. Additionally, improvement in serum antioxidant parameters and lipid profile were evidenced clearly. Moreover, EE and BE had effects of protecting the pancreatic β-cells and stimulating insulin secretion from the remaining pancreatic β-cells, evidenced by pancreatic histology examination. Increased glucokinase activity and decreased glucose-6-phosphatase activity were observed in liver. CONCLUSION The results of in vivo and in vitro experiment suggested that EE and BE of Swertia macrosperma had excellent effects on controlling the hyperglycemia and hyperlipidemia in diabetic rats.
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Affiliation(s)
- Yong-Long Wang
- Hubei Key Laboratory of Natural Medicinal Chemistry and Resource Evaluation, Tongji School of Pharmaceutical Sciences, Huazhong University of Science and Technology, Wuhan 430030, People's Republic of China
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23
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Montgomery MK, Osborne B, Brown SHJ, Small L, Mitchell TW, Cooney GJ, Turner N. Contrasting metabolic effects of medium- versus long-chain fatty acids in skeletal muscle. J Lipid Res 2013; 54:3322-33. [PMID: 24078708 DOI: 10.1194/jlr.m040451] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Dietary intake of long-chain fatty acids (LCFAs) plays a causative role in insulin resistance and risk of diabetes. Whereas LCFAs promote lipid accumulation and insulin resistance, diets rich in medium-chain fatty acids (MCFAs) have been associated with increased oxidative metabolism and reduced adiposity, with few deleterious effects on insulin action. The molecular mechanisms underlying these differences between dietary fat subtypes are poorly understood. To investigate this further, we treated C2C12 myotubes with various LCFAs (16:0, 18:1n9, and 18:2n6) and MCFAs (10:0 and 12:0), as well as fed mice diets rich in LCFAs or MCFAs, and investigated fatty acid-induced changes in mitochondrial metabolism and oxidative stress. MCFA-treated cells displayed less lipid accumulation, increased mitochondrial oxidative capacity, and less oxidative stress than LCFA-treated cells. These changes were associated with improved insulin action in MCFA-treated myotubes. MCFA-fed mice exhibited increased energy expenditure, reduced adiposity, and better glucose tolerance compared with LCFA-fed mice. Dietary MCFAs increased respiration in isolated mitochondria, with a simultaneous reduction in reactive oxygen species generation, and subsequently low oxidative damage. Collectively our findings indicate that in contrast to LCFAs, MCFAs increase the intrinsic respiratory capacity of mitochondria without increasing oxidative stress. These effects potentially contribute to the beneficial metabolic actions of dietary MCFAs.
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Affiliation(s)
- Magdalene K Montgomery
- Department of Pharmacology, School of Medical Sciences, University of New South Wales, Sydney, NSW, Australia
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24
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Imbernon M, Beiroa D, Vázquez MJ, Morgan DA, Veyrat–Durebex C, Porteiro B, Díaz–Arteaga A, Senra A, Busquets S, Velásquez DA, Al–Massadi O, Varela L, Gándara M, López–Soriano F, Gallego R, Seoane LM, Argiles JM, López M, Davis RJ, Sabio G, Rohner–Jeanrenaud F, Rahmouni K, Dieguez C, Nogueiras R. Central melanin-concentrating hormone influences liver and adipose metabolism via specific hypothalamic nuclei and efferent autonomic/JNK1 pathways. Gastroenterology 2013; 144:636-649.e6. [PMID: 23142626 PMCID: PMC3663042 DOI: 10.1053/j.gastro.2012.10.051] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/24/2012] [Revised: 10/10/2012] [Accepted: 10/31/2012] [Indexed: 01/18/2023]
Abstract
BACKGROUND & AIMS Specific neuronal circuits modulate autonomic outflow to liver and white adipose tissue. Melanin-concentrating hormone (MCH)-deficient mice are hypophagic, lean, and do not develop hepatosteatosis when fed a high-fat diet. Herein, we sought to investigate the role of MCH, an orexigenic neuropeptide specifically expressed in the lateral hypothalamic area, on hepatic and adipocyte metabolism. METHODS Chronic central administration of MCH and adenoviral vectors increasing MCH signaling were performed in rats and mice. Vagal denervation was performed to assess its effect on liver metabolism. The peripheral effects on lipid metabolism were assessed by real-time polymerase chain reaction and Western blot. RESULTS We showed that the activation of MCH receptors promotes nonalcoholic fatty liver disease through the parasympathetic nervous system, whereas it increases fat deposition in white adipose tissue via the suppression of sympathetic traffic. These metabolic actions are independent of parallel changes in food intake and energy expenditure. In the liver, MCH triggers lipid accumulation and lipid uptake, with c-Jun N-terminal kinase being an essential player, whereas in adipocytes MCH induces metabolic pathways that promote lipid storage and decreases lipid mobilization. Genetic activation of MCH receptors or infusion of MCH specifically in the lateral hypothalamic area modulated hepatic lipid metabolism, whereas the specific activation of this receptor in the arcuate nucleus affected adipocyte metabolism. CONCLUSIONS Our findings show that central MCH directly controls hepatic and adipocyte metabolism through different pathways.
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Affiliation(s)
- Monica Imbernon
- Department of Physiology, School of Medicine, University of Santiago de Compostela-Instituto de Investigación Sanitaria, S. Francisco s/n, Santiago de Compostela (A Coruña), Spain,Centro de Investigación Biomédica en Red (CIBER) Fisiopatología de la Obesidad y Nutrición, Santiago de Compostela, Spain
| | - Daniel Beiroa
- Department of Physiology, School of Medicine, University of Santiago de Compostela-Instituto de Investigación Sanitaria, S. Francisco s/n, Santiago de Compostela (A Coruña), Spain,Centro de Investigación Biomédica en Red (CIBER) Fisiopatología de la Obesidad y Nutrición, Santiago de Compostela, Spain
| | - María J. Vázquez
- Department of Physiology, School of Medicine, University of Santiago de Compostela-Instituto de Investigación Sanitaria, S. Francisco s/n, Santiago de Compostela (A Coruña), Spain,Centro de Investigación Biomédica en Red (CIBER) Fisiopatología de la Obesidad y Nutrición, Santiago de Compostela, Spain
| | - Donald A. Morgan
- Department of Pharmacology, University of Iowa Carver College of Medicine, Iowa City, Iowa
| | - Christelle Veyrat–Durebex
- Laboratory of Metabolism, Division of Endocrinology, Diabetology and Nutrition, Department of Internal Medicine, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Begoña Porteiro
- Department of Physiology, School of Medicine, University of Santiago de Compostela-Instituto de Investigación Sanitaria, S. Francisco s/n, Santiago de Compostela (A Coruña), Spain,Centro de Investigación Biomédica en Red (CIBER) Fisiopatología de la Obesidad y Nutrición, Santiago de Compostela, Spain
| | - Adenis Díaz–Arteaga
- Department of Physiology, School of Medicine, University of Santiago de Compostela-Instituto de Investigación Sanitaria, S. Francisco s/n, Santiago de Compostela (A Coruña), Spain,Centro de Investigación Biomédica en Red (CIBER) Fisiopatología de la Obesidad y Nutrición, Santiago de Compostela, Spain
| | - Ana Senra
- Department of Physiology, School of Medicine, University of Santiago de Compostela-Instituto de Investigación Sanitaria, S. Francisco s/n, Santiago de Compostela (A Coruña), Spain,Centro de Investigación Biomédica en Red (CIBER) Fisiopatología de la Obesidad y Nutrición, Santiago de Compostela, Spain
| | - Silvia Busquets
- Department of Biochemistry and Molecular Biology, University of Barcelona, Barcelona, Spain
| | - Douglas A. Velásquez
- Department of Physiology, School of Medicine, University of Santiago de Compostela-Instituto de Investigación Sanitaria, S. Francisco s/n, Santiago de Compostela (A Coruña), Spain,Centro de Investigación Biomédica en Red (CIBER) Fisiopatología de la Obesidad y Nutrición, Santiago de Compostela, Spain
| | - Omar Al–Massadi
- Centro de Investigación Biomédica en Red (CIBER) Fisiopatología de la Obesidad y Nutrición, Santiago de Compostela, Spain,Grupo Fisiopatología Endocrina, Complejo Hospitalario Universitario de Santiago-Instituto de Investigación Sanitaria (IDIS/SERGAS) Santiago de Compostela, Spain
| | - Luis Varela
- Department of Physiology, School of Medicine, University of Santiago de Compostela-Instituto de Investigación Sanitaria, S. Francisco s/n, Santiago de Compostela (A Coruña), Spain,Centro de Investigación Biomédica en Red (CIBER) Fisiopatología de la Obesidad y Nutrición, Santiago de Compostela, Spain
| | - Marina Gándara
- Department of Physiology, School of Medicine, University of Santiago de Compostela-Instituto de Investigación Sanitaria, S. Francisco s/n, Santiago de Compostela (A Coruña), Spain
| | | | - Rosalía Gallego
- Department of Physiology, School of Medicine, University of Santiago de Compostela-Instituto de Investigación Sanitaria, S. Francisco s/n, Santiago de Compostela (A Coruña), Spain
| | - Luisa M. Seoane
- Centro de Investigación Biomédica en Red (CIBER) Fisiopatología de la Obesidad y Nutrición, Santiago de Compostela, Spain,Grupo Fisiopatología Endocrina, Complejo Hospitalario Universitario de Santiago-Instituto de Investigación Sanitaria (IDIS/SERGAS) Santiago de Compostela, Spain
| | - Josep M. Argiles
- Department of Biochemistry and Molecular Biology, University of Barcelona, Barcelona, Spain
| | - Miguel López
- Department of Physiology, School of Medicine, University of Santiago de Compostela-Instituto de Investigación Sanitaria, S. Francisco s/n, Santiago de Compostela (A Coruña), Spain,Centro de Investigación Biomédica en Red (CIBER) Fisiopatología de la Obesidad y Nutrición, Santiago de Compostela, Spain
| | - Roger J. Davis
- Howard Hughes Medical Institute, Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, Massachusetts
| | - Guadalupe Sabio
- Department of Vascular Biology and Inflammation, Centro Nacional de Investigaciones Cardiovasculares Carlos III, Madrid, Spain
| | - Françoise Rohner–Jeanrenaud
- Laboratory of Metabolism, Division of Endocrinology, Diabetology and Nutrition, Department of Internal Medicine, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Kamal Rahmouni
- Department of Pharmacology, University of Iowa Carver College of Medicine, Iowa City, Iowa
| | - Carlos Dieguez
- Department of Physiology, School of Medicine, University of Santiago de Compostela-Instituto de Investigación Sanitaria, S. Francisco s/n, Santiago de Compostela (A Coruña), Spain,Centro de Investigación Biomédica en Red (CIBER) Fisiopatología de la Obesidad y Nutrición, Santiago de Compostela, Spain
| | - Ruben Nogueiras
- Department of Physiology, School of Medicine, University of Santiago de Compostela-Instituto de Investigación Sanitaria, S. Francisco s/n, Santiago de Compostela (A Coruña), Spain,Centro de Investigación Biomédica en Red (CIBER) Fisiopatología de la Obesidad y Nutrición, Santiago de Compostela, Spain
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25
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Jung UJ, Park YB, Kim SR, Choi MS. Supplementation of persimmon leaf ameliorates hyperglycemia, dyslipidemia and hepatic fat accumulation in type 2 diabetic mice. PLoS One 2012; 7:e49030. [PMID: 23145054 PMCID: PMC3493507 DOI: 10.1371/journal.pone.0049030] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2012] [Accepted: 10/03/2012] [Indexed: 01/31/2023] Open
Abstract
Persimmon Leaf (PL), commonly consumed as herbal tea and traditional medicines, contains a variety of compounds that exert antioxidant, α-amylase and α-glucosidase inhibitory activity. However, little is known about the in vivo effects and underlying mechanisms of PL on hyperglycemia, hyperlipidemia and hepatic steatosis in type 2 diabetes. Powered PL (5%, w/w) was supplemented with a normal diet to C57BL/KsJ-db/db mice for 5 weeks. PL decreased blood glucose, HOMA-IR, plasma triglyceride and total cholesterol levels, as well as liver weight, hepatic lipid droplets, triglycerides and cholesterol contents, while increasing plasma HDL-cholesterol and adiponectin levels. The anti-hyperglycemic effect was linked to decreased activity of gluconeogenic enzymes as well as increased glycogen content, glucokinase activity and its mRNA level in the liver. PL also led to a decrease in lipogenic transcriptional factor PPARγ as well as gene expression and activity of enzymes involved in lipogenesis, with a simultaneous increase in fecal lipids, which are seemingly attributable to the improved hyperlipidemia and hepatic steatosis and decreased hepatic fatty acid oxidation. Furthermore, PL ameliorated plasma and hepatic oxidative stress. Supplementation with PL may be an effective dietary strategy to improve type 2 diabetes accompanied by dyslipidemia and hepatic steatosis by partly modulating the activity or gene expression of enzymes related to antioxidant, glucose and lipid homeostasis.
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Affiliation(s)
- Un Ju Jung
- Department of Food Science and Nutrition, Kyungpook National University, Daegu, Republic of Korea
| | - Yong Bok Park
- School of Life Sciences and Biotechnology, Kyungpook National University, Daegu, Republic of Korea
| | - Sang Ryong Kim
- School of Life Sciences and Biotechnology, Kyungpook National University, Daegu, Republic of Korea
- Brain Science and Engineering Institute, Kyungpook National University, Daegu, Republic of Korea
| | - Myung-Sook Choi
- Department of Food Science and Nutrition, Kyungpook National University, Daegu, Republic of Korea
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26
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Erickson KA, Smith ME, Anthonymuthu TS, Evanson MJ, Brassfield ES, Hodson AE, Bressler MA, Tucker BJ, Thatcher MO, Prince JT, Hancock CR, Bikman BT. AICAR inhibits ceramide biosynthesis in skeletal muscle. Diabetol Metab Syndr 2012; 4:45. [PMID: 23134616 PMCID: PMC3514253 DOI: 10.1186/1758-5996-4-45] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/29/2012] [Accepted: 11/05/2012] [Indexed: 02/28/2023] Open
Abstract
BACKGROUND The worldwide prevalence of obesity has lead to increased efforts to find therapies to treat obesity-related pathologies. Ceramide is a well-established mediator of several health problems that arise from adipose tissue expansion. The purpose of this study was to determine whether AICAR, an AMPK-activating drug, selectively reduces skeletal muscle ceramide synthesis. METHODS Murine myotubes and rats were challenged with palmitate and high-fat diet, respectively, to induce ceramide accrual, in the absence or presence of AICAR. Transcript levels of the rate-limiting enzyme in ceramide biosynthesis, serine palmitoyltransferase 2 (SPT2) were measured, in addition to lipid analysis. Student's t-test and ANOVA were used to assess the association between outcomes and groups. RESULTS Palmitate alone induced an increase in serine palmitoyltransferase 2 (SPT2) expression and an elevation of ceramide levels in myotubes. Co-incubation with palmitate and AICAR prevented both effects. However, ceramide and SPT2 increased with the addition of compound C, an AMPK inhibitor. In rats fed a high-fat diet (HFD), soleus SPT2 expression increased compared with normal chow-fed littermates. Moreover, rats on HFD that received daily AICAR injections had lower SPT2 levels and reduced muscle ceramide content compared with those on HFD only. CONCLUSIONS These results suggest that AICAR reduces ceramide synthesis by targeting SPT2 transcription, likely via AMPK activation as AMPK inhibition prevented the AICAR-induced improvements. Given the role of skeletal muscle ceramide in insulin resistance, it is tempting to speculate that interventions that activate AMPK may lead to long-term ceramide reduction and improved metabolic function.
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Affiliation(s)
- Katherine A Erickson
- Physiology and Developmental Biology, Brigham Young University, 593 WIDB, Provo, UT 84602, USA
| | - Melissa E Smith
- Physiology and Developmental Biology, Brigham Young University, 593 WIDB, Provo, UT 84602, USA
| | | | - Michael J Evanson
- Physiology and Developmental Biology, Brigham Young University, 593 WIDB, Provo, UT 84602, USA
| | - Eric S Brassfield
- Physiology and Developmental Biology, Brigham Young University, 593 WIDB, Provo, UT 84602, USA
| | - Aimee E Hodson
- Physiology and Developmental Biology, Brigham Young University, 593 WIDB, Provo, UT 84602, USA
| | - M Andrew Bressler
- Physiology and Developmental Biology, Brigham Young University, 593 WIDB, Provo, UT 84602, USA
| | - Braden J Tucker
- Physiology and Developmental Biology, Brigham Young University, 593 WIDB, Provo, UT 84602, USA
| | - Mikayla O Thatcher
- Physiology and Developmental Biology, Brigham Young University, 593 WIDB, Provo, UT 84602, USA
| | - John T Prince
- Chemistry and Biochemistry, Brigham Young University, Provo, UT 84602, USA
| | - Chad R Hancock
- Nutrition, Dietetics, and Food Science, Brigham Young University, Provo, UT 84602, USA
| | - Benjamin T Bikman
- Physiology and Developmental Biology, Brigham Young University, 593 WIDB, Provo, UT 84602, USA
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27
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Patel SA, Hoehn KL, Lawrence RT, Sawbridge L, Talbot NA, Tomsig JL, Turner N, Cooney GJ, Whitehead JP, Kraegen EW, Cleasby ME. Overexpression of the adiponectin receptor AdipoR1 in rat skeletal muscle amplifies local insulin sensitivity. Endocrinology 2012; 153:5231-46. [PMID: 22989629 PMCID: PMC3498583 DOI: 10.1210/en.2012-1368] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Adiponectin is an adipokine whose plasma levels are inversely related to degrees of insulin resistance (IR) or obesity. It enhances glucose disposal and mitochondrial substrate oxidation in skeletal muscle and its actions are mediated through binding to receptors, especially adiponectin receptor 1 (AdipoR1). However, the in vivo significance of adiponectin sensitivity and the molecular mechanisms of muscle insulin sensitization by adiponectin have not been fully established. We used in vivo electrotransfer to overexpress AdipoR1 in single muscles of rats, some of which were fed for 6 wk with chow or high-fat diet (HFD) and then subjected to hyperinsulinemic-euglycemic clamp. After 1 wk, the effects on glucose disposal, signaling, and sphingolipid metabolism were investigated in test vs. contralateral control muscles. AdipoR1 overexpression (OE) increased glucose uptake and glycogen accumulation in the basal and insulin-treated rat muscle and also in the HFD-fed rats, locally ameliorating muscle IR. These effects were associated with increased phosphorylation of insulin receptor substrate-1, Akt, and glycogen synthase kinase-3β. AdipoR1 OE also caused increased phosphorylation of p70S6 kinase, AMP-activated protein kinase, and acetyl-coA carboxylase as well as increased protein levels of adaptor protein containing pleckstrin homology domain, phosphotyrosine binding domain, and leucine zipper motif-1 and adiponectin, peroxisome proliferator activated receptor-γ coactivator-1α, and uncoupling protein-3, indicative of increased mitochondrial biogenesis. Although neither HFD feeding nor AdipoR1 OE caused generalized changes in sphingolipids, AdipoR1 OE did reduce levels of sphingosine 1-phosphate, ceramide 18:1, ceramide 20:2, and dihydroceramide 20:0, plus mRNA levels of the ceramide synthetic enzymes serine palmitoyl transferase and sphingolipid Δ-4 desaturase, changes that are associated with increased insulin sensitivity. These data demonstrate that enhancement of local adiponectin sensitivity is sufficient to improve skeletal muscle IR.
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Affiliation(s)
- S A Patel
- Department of Comparative Biomedical Sciences, Royal Veterinary College, University of London, United Kingdom
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28
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Konstantopoulos N, Molero JC, McGee SL, Spolding B, Connor T, de Vries M, Wanyonyi S, Fahey R, Morrison S, Swinton C, Jones S, Cooper A, Garcia-Guerra L, Foletta VC, Krippner G, Andrikopoulos S, Walder KR. Methazolamide is a new hepatic insulin sensitizer that lowers blood glucose in vivo. Diabetes 2012; 61:2146-54. [PMID: 22586591 PMCID: PMC3402314 DOI: 10.2337/db11-0578] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
We previously used Gene Expression Signature technology to identify methazolamide (MTZ) and related compounds with insulin sensitizing activity in vitro. The effects of these compounds were investigated in diabetic db/db mice, insulin-resistant diet-induced obese (DIO) mice, and rats with streptozotocin (STZ)-induced diabetes. MTZ reduced fasting blood glucose and HbA(1c) levels in db/db mice, improved glucose tolerance in DIO mice, and enhanced the glucose-lowering effects of exogenous insulin administration in rats with STZ-induced diabetes. Hyperinsulinemic-euglycemic clamps in DIO mice revealed that MTZ increased glucose infusion rate and suppressed endogenous glucose production. Whole-body or cellular oxygen consumption rate was not altered, suggesting MTZ may inhibit glucose production by different mechanism(s) to metformin. In support of this, MTZ enhanced the glucose-lowering effects of metformin in db/db mice. MTZ is known to be a carbonic anhydrase inhibitor (CAI); however, CAIs acetazolamide, ethoxyzolamide, dichlorphenamide, chlorthalidone, and furosemide were not effective in vivo. Our results demonstrate that MTZ acts as an insulin sensitizer that suppresses hepatic glucose production in vivo. The antidiabetic effect of MTZ does not appear to be a function of its known activity as a CAI. The additive glucose-lowering effect of MTZ together with metformin highlights the potential utility for the management of type 2 diabetes.
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Affiliation(s)
- Nicky Konstantopoulos
- Metabolic Research Unit, School of Medicine, Deakin University, Geelong, Victoria, Australia.
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Oleanolic acid reduces hyperglycemia beyond treatment period with Akt/FoxO1-induced suppression of hepatic gluconeogenesis in type-2 diabetic mice. PLoS One 2012; 7:e42115. [PMID: 22860063 PMCID: PMC3408432 DOI: 10.1371/journal.pone.0042115] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2012] [Accepted: 07/02/2012] [Indexed: 12/31/2022] Open
Abstract
The present study investigated the chronic efficacy of oleanolic acid (OA), a triterpenoid selected from our recent screening, on hyperglycemia in type-2 diabetic mice. C57BL/6J mice were fed a high-fat diet followed by low doses of streptozotocin to generate a type-2 diabetic model. OA (100 mg/kg/day) was administered orally for 2 weeks with its effects monitored for 6 weeks. High-fat feeding and streptozotocin generated a steady hyperglycemia (21.2±1.1 mM) but OA administration reversed the hyperglycemia by ∼60%. Interestingly, after the cessation of OA administration, the reversed hyperglycemia was sustained for the entire post-treatment period of the study (4 weeks) despite the reoccurrence of dyslipidemia. Examination of insulin secretion and pancreas morphology did not indicate improved β-cell function as a likely mechanism. Urine glucose loss was decreased with substantial improvement of diabetic nephropathy after the OA treatment. Pair-feeding the OA-treated mice to an untreated group ruled out food intake as a main factor attributable for this sustained reduction in hyperglycemia. Studies with the use of glucose tracers revealed no increase in glucose influx into muscle, adipose tissue or liver in the OA-treated mice. Finally, we analyzed key regulators of gluconeogenesis in the liver and found significant increases in the phosphorylation of both Akt and FoxO1 after treatment with OA. Importantly, these increases were significantly correlated with a down-regulation of glucose-6-phosphatase expression. Our findings suggest triterpenoids are a potential source of new efficacious drugs for sustained control of hyperglycemia. The liver appears to be a major site of action, possibly by the suppression of hepatic glucose production via the Akt/FoxO1 axis.
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Wang M, Tong JH, Zhu G, Liang GM, Yan HF, Wang XZ. Metformin for treatment of antipsychotic-induced weight gain: a randomized, placebo-controlled study. Schizophr Res 2012; 138:54-7. [PMID: 22398127 DOI: 10.1016/j.schres.2012.02.021] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/21/2011] [Revised: 01/31/2012] [Accepted: 02/14/2012] [Indexed: 12/21/2022]
Abstract
OBJECTIVES To evaluate the efficacy of metformin for treatment of antipsychotic-induced weight gain. METHODS Seventy-two patients with first-episode schizophrenia who gained more than 7% of their predrug weight were randomly assigned to receive 1000 mg/d of metformin or placebo in addition to their ongoing treatment for 12 weeks using a double-blind study design. The primary outcome was change in body weight. The secondary outcomes included changes in body mass index, fasting glucose and insulin, and insulin resistance index. RESULTS Of the 72 patients who were randomly assigned, 66 (91.6%) completed treatments. The body weight, body mass index, fasting insulin and insulin resistance index decreased significantly in the metformin group, but increased in the placebo group during the 12-week follow-up period. Significantly more patients in the metformin group lost their baseline weight by more than 7%, which was the cutoff for clinically meaningful weight loss. Metformin was tolerated well by majority patients. CONCLUSION Metformin was effective and safe in attenuating antipsychotic-induced weight gain and insulin resistance in first-episode schizophrenia patients. Patients displayed good adherence to metformin.
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Affiliation(s)
- Man Wang
- Department of Psychiatry, the First Hospital of China Medical University, 155# Nanjing North Road, Shenyang 110001, Liaoning, PR China.
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Campello RS, Alves-Wagner ABT, Abdulkader F, Mori RCT, Machado UF. Carbohydrate- and lipid-enriched meals acutely disrupt glycemic homeostasis by inducing transient insulin resistance in rats. Can J Physiol Pharmacol 2012; 90:537-45. [PMID: 22510071 DOI: 10.1139/y2012-056] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Chronic intake of high-carbohydrate or high-lipid diets is a well-known insulin resistance inducer. This study investigates the immediate effect (1-6 h) of a carbohydrate- or lipid-enriched meal on insulin sensitivity. Fasted rats were refed with standard, carbohydrate-enriched (C), or lipid-enriched (L) meal. Plasma insulin, glucose, and non-esterified fatty acids (NEFA) were measured at 1, 2, 4, and 6 h of refeeding. The glucose-insulin index showed that either carbohydrates or lipids decreased insulin sensitivity at 2 h of refeeding. At this time point, insulin tolerance tests (ITTs) and glucose tolerance tests (GTTs) detected insulin resistance in C rats, while GTT confirmed it in L rats. Reduced glycogen and phosphorylated AKT and GSK3 content revealed hepatic insulin resistance in C rats. Reduced glucose uptake in skeletal muscle subjected to the fatty acid concentration that mimics the high NEFA level of L rats suggests insulin resistance in these animals is mainly in muscle. In conclusion, carbohydrate- or lipid-enriched meals acutely disrupt glycemic homeostasis, inducing a transient insulin resistance, which seems to involve liver and skeletal muscle, respectively. Thus, the insulin resistance observed when those types of diets are chronically consumed may be an evolution of repeated episodes of this transient insulin resistance.
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Affiliation(s)
- Raquel Saldanha Campello
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of Sao Paulo, Brazil.
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Zheng T, Shu G, Yang Z, Mo S, Zhao Y, Mei Z. Antidiabetic effect of total saponins from Entada phaseoloides (L.) Merr. in type 2 diabetic rats. JOURNAL OF ETHNOPHARMACOLOGY 2012; 139:814-21. [PMID: 22212505 DOI: 10.1016/j.jep.2011.12.025] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2011] [Revised: 12/06/2011] [Accepted: 12/13/2011] [Indexed: 05/08/2023]
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE The seed of Entada phaseoloides (L.) Merr. (Entada phaseoloides) has been long used as an effective herb for the treatment of Diabetes mellitus by Dai people, one of the Chinese ethnic minorities. Saponin is an abundant type of secondary metabolic products in the seed of this plant. The aim of this study is to evaluate the potential therapeutic effects of total saponins from Entada phaseoloides (TSEP) in experimental type 2 Diabetes mellitus (T2DM) rats. MATERIALS AND METHODS T2DM rats were induced by high-fat diet and low-dose streptozotocin (STZ). Then different oral doses of TSEP (25, 50 and 100 mg/kg) were administrated to T2DM rats for 21 days. For comparison, a standard antidiabetic drug, metformin (200 mg/kg), was used as a positive control drug. Then the relative biochemical analysis and histopathological examination were made to evaluate the antidiabetic effect of TSEP. RESULTS TSEP dramatically reduced fasted blood glucose and serum insulin levels and alleviates hyperglycemia associated oxidative stress in T2DM rats. Moreover, a significantly hypolipidemic effect and an improvement in tissue steatosis could be observed after TSEP administration. Further investigations revealed a possible anti-inflammation effect of TSEP by examining serum levels of interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-α) and C-reactive protein (CRP). The effects of TSEP exhibited a dose-dependent manner and were comparable to metformin. CONCLUSION Our present study demonstrates both hypoglycemic and hypolipidemic activities of TSEP in T2DM rats, which support its antidiabetic property. This work also implies a possibility that TSEP exerts its therapeutic effect through repressing chronic inflammation responses.
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Affiliation(s)
- Tao Zheng
- College of Pharmacy, South-Central University for Nationalities, Wuhan, PR China
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Bargiota A, Diamanti-Kandarakis E. The effects of old, new and emerging medicines on metabolic aberrations in PCOS. Ther Adv Endocrinol Metab 2012; 3:27-47. [PMID: 23148192 PMCID: PMC3474645 DOI: 10.1177/2042018812437355] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Polycystic ovary syndrome (PCOS) is a common endocrine disorder in women of reproductive age that is associated with significant adverse short- and long-term health consequences. Multiple metabolic aberrations, such as insulin resistance (IR) and hyperinsulinaemia, high incidence of impaired glucose tolerance, visceral obesity, inflammation and endothelial dysfunction, hypertension and dyslipidemia are associated with the syndrome. Assessing the metabolic aberrations and their long term health impact in women with PCOS is challenging and becomes more important as therapeutic interventions currently available for the management of PCOS are not fully able to deal with all these consequences. Current therapeutic management of PCOS has incorporated new treatments resulting from the better understanding of the pathophysiology of the syndrome. The aim of this review is to summarize the effect of old, new and emerging therapies used in the management of PCOS, on the metabolic aberrations of PCOS.
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Cleasby ME, Lau Q, Polkinghorne E, Patel SA, Leslie SJ, Turner N, Cooney GJ, Xu A, Kraegen EW. The adaptor protein APPL1 increases glycogen accumulation in rat skeletal muscle through activation of the PI3-kinase signalling pathway. J Endocrinol 2011; 210:81-92. [PMID: 21543456 PMCID: PMC3114475 DOI: 10.1530/joe-11-0039] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Revised: 05/04/2011] [Accepted: 05/04/2011] [Indexed: 12/16/2022]
Abstract
APPL1 is an adaptor protein that binds to both AKT and adiponectin receptors and is hypothesised to mediate the effects of adiponectin in activating downstream effectors such as AMP-activated protein kinase (AMPK). We aimed to establish whether APPL1 plays a physiological role in mediating glycogen accumulation and insulin sensitivity in muscle and the signalling pathways involved. In vivo electrotransfer of cDNA- and shRNA-expressing constructs was used to over-express or silence APPL1 for 1 week in single tibialis cranialis muscles of rats. Resulting changes in glucose and lipid metabolism and signalling pathway activation were investigated under basal conditions and in high-fat diet (HFD)- or chow-fed rats under hyperinsulinaemic-euglycaemic clamp conditions. APPL1 over-expression (OE) caused an increase in glycogen storage and insulin-stimulated glycogen synthesis in muscle, accompanied by a modest increase in glucose uptake. Glycogen synthesis during the clamp was reduced by HFD but normalised by APPL1 OE. These effects are likely explained by APPL1 OE-induced increase in basal and insulin-stimulated phosphorylation of IRS1, AKT, GSK3β and TBC1D4. On the contrary, APPL1 OE, such as HFD, reduced AMPK and acetyl-CoA carboxylase phosphorylation and PPARγ coactivator-1α and uncoupling protein 3 expression. Furthermore, APPL1 silencing caused complementary changes in glycogen storage and phosphorylation of AMPK and PI3-kinase pathway intermediates. Thus, APPL1 may provide a means for crosstalk between adiponectin and insulin signalling pathways, mediating the insulin-sensitising effects of adiponectin on muscle glucose disposal. These effects do not appear to require AMPK. Activation of signalling mediated via APPL1 may be beneficial in overcoming muscle insulin resistance.
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Affiliation(s)
- M E Cleasby
- Department of Veterinary Basic Sciences, Royal Veterinary College, University of London, Royal College Street, London NW1 0TU, UK.
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Takiyama Y, Harumi T, Watanabe J, Fujita Y, Honjo J, Shimizu N, Makino Y, Haneda M. Tubular injury in a rat model of type 2 diabetes is prevented by metformin: a possible role of HIF-1α expression and oxygen metabolism. Diabetes 2011; 60:981-92. [PMID: 21282369 PMCID: PMC3046859 DOI: 10.2337/db10-0655] [Citation(s) in RCA: 131] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
OBJECTIVE Chronic hypoxia has been recognized as a key regulator in renal tubulointerstitial fibrosis, as seen in diabetic nephropathy, which is associated with the activation of hypoxia-inducible factor (HIF)-1α. We assess here the effects of the biguanide, metformin, on the expression of HIF-1α in diabetic nephropathy using renal proximal tubular cells and type 2 diabetic rats. RESEARCH DESIGN AND METHODS We explored the effects of metformin on the expression of HIF-1α using human renal proximal tubular epithelial cells (HRPTECs). Male Zucker diabetic fatty (ZDF; Gmi-fa/fa) rats were treated from 9 to 39 weeks with metformin (250 mg ⋅ kg(-1) ⋅ day(-1)) or insulin. RESULTS Metformin inhibited hypoxia-induced HIF-1α accumulation and the expression of HIF-1-targeted genes in HRPTECs. Although metformin activated the downstream pathways of AMP-activated protein kinase (AMPK), neither the AMPK activator, AICAR, nor the mTOR inhibitor, rapamycin, suppressed hypoxia-induced HIF-1α expression. In addition, knockdown of AMPK-α did not abolish the inhibitory effects of metformin on HIF-1α expression. The proteasome inhibitor, MG-132, completely eradicated the suppression of hypoxia-induced HIF-1α accumulation by metformin. The inhibitors of mitochondrial respiration similarly suppressed hypoxia-induced HIF-1α expression. Metformin significantly decreased ATP production and oxygen consumption rates, which subsequently led to increased cellular oxygen tension. Finally, metformin, but not insulin, attenuated tubular HIF-1α expression and pimonidazole staining and ameliorated tubular injury in ZDF rats. CONCLUSIONS Our data suggest that hypoxia-induced HIF-1α accumulation in diabetic nephropathy could be suppressed by the antidiabetes drug, metformin, through the repression of oxygen consumption.
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Affiliation(s)
- Yumi Takiyama
- Division of Metabolism and Biosystemic Science, Department of Medicine, Asahikawa Medical University, Asahikawa, Japan.
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Kim DS, Jeong SK, Kim HR, Kim DS, Chae SW, Chae HJ. Metformin regulates palmitate-induced apoptosis and ER stress response in HepG2 liver cells. Immunopharmacol Immunotoxicol 2010; 32:251-7. [PMID: 20038265 DOI: 10.3109/08923970903252220] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The excessive supply of fatty acids to the liver contributes to hepatic insulin resistance and endoplasmic reticulum (ER) stress associated with obesity or type 2 diabetes mellitus. Furthermore, excess and/or prolonged ER stress contributes to hepatic cell death deteriorating nonalcoholic fatty liver disease to steatohepatitis. The aim of this study was to investigate the effects of metformin on palmitate-induced ER stress and hepatic insulin resistance in HepG2 cells. Metformin significantly inhibited palmitate-induced cell death and apoptosis via caspase-3 activation. Metformin also blocked the induction of ER stress proteins (GRP78, Chop, Cleaved ATF-6, p-eIF2 alpha and XBP-1) and regulated serine phosphorylation of IRS-1. Metformin may therefore protect hepatocytes from death induced by saturated fatty acids. These data may also provide a further rationale for exploring the use of metformin in the treatment of non-alcoholic fatty liver disease, revealing its blocking effect for hepatic insulin resistance evoked by saturated fatty acids.
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Affiliation(s)
- Do-Sung Kim
- Department of Pharmacology and Institute of Cardiovascular Research, School of Medicine, Chonbuk National University, Chonbuk, Republic of Korea
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Bikman BT, Zheng D, Reed MA, Hickner RC, Houmard JA, Dohm GL. Lipid-induced insulin resistance is prevented in lean and obese myotubes by AICAR treatment. Am J Physiol Regul Integr Comp Physiol 2010; 298:R1692-9. [PMID: 20393162 DOI: 10.1152/ajpregu.00190.2009] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The molecular mechanisms of obesity-associated insulin resistance are becoming increasingly clear, and the effects of various lipid molecules, such as diacylglycerol and ceramide, on the insulin signal are being actively explored. To better understand the divergent response to lipid exposure between lean and obese, we incubated primary human muscle cells from lean [body mass index (BMI) <25 kg/m(2)] and morbidly obese (BMI >40 kg/m(2)) subjects with the saturated fatty acid palmitate. Additionally, given that AMPK-activating drugs are widely prescribed for their insulin-sensitizing effects, we sought to determine whether 5-aminoimidazole-4-carboxamide 1-beta-D-ribofuranoside (AICAR)-stimulated AMPK activation could prevent or reverse the deleterious effects of lipid on insulin signaling. We found that a 1-h palmitate incubation in lean myotubes reduced (P < 0.05) insulin-stimulated phosphoprotein kinase B (Akt), Akt substrate 160 (AS160), and inhibitory factor kappaBalpha (IkappaBalpha) mass, all of which were prevented with AICAR inclusion. With a longer incubation, we observed that myotubes from morbidly obese individuals appear to be largely resistant to the detrimental effects of 16 h lipid exposure as was evident, in contrast to the lean, by the absence of a reduction in insulin-stimulated insulin receptor substrate (IRS)-1 Tyr phosphorylation, phospho-Akt, and phospho-AS160 (P < 0.05). Furthermore, 16 h lipid exposure significantly reduced IkappaBalpha levels and increased phosphorylation of c-Jun NH(2)-terminal kinase (JNK) and IRS1-Ser(312) in lean myotubes only (P < 0.05). Despite a divergent response to lipid between lean and obese myotubes, AICAR inclusion improved insulin signaling in all myotubes. These findings suggest an important role for regular exercise in addition to offering a potential mechanism of action for oral AMPK-activating agents, such as thiazolidinediones and metformin.
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Affiliation(s)
- Benjamin T Bikman
- The Metabolic Institute for the Study of Diabetes and Obesity, East Carolina University, Greenville, North Carolina 27834, USA
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Bikman BT, Zheng D, Kane DA, Anderson EJ, Woodlief TL, Price JW, Dohm GL, Neufer PD, Cortright RN. Metformin Improves Insulin Signaling in Obese Rats via Reduced IKKbeta Action in a Fiber-Type Specific Manner. J Obes 2010; 2010:970865. [PMID: 20798864 PMCID: PMC2925476 DOI: 10.1155/2010/970865] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/26/2009] [Accepted: 10/27/2009] [Indexed: 02/06/2023] Open
Abstract
Metformin is a widely used insulin-sensitizing drug, though its mechanisms are not fully understood. Metformin has been shown to activate AMPK in skeletal muscle; however, its effects on the inhibitor of kappaB kinasebeta (IKKbeta) in this same tissue are unknown. The aim of this study was to (1) determine the ability of metformin to attenuate IKKbeta action, (2) determine whether changes in AMPK activity are associated with changes in IKKbeta action in skeletal muscle, and (3) examine whether changes in AMPK and IKKbeta function are consistent with improved insulin signaling. Lean and obese male Zuckers received either vehicle or metformin by oral gavage daily for four weeks (four groups of eight). Proteins were measured in white gastrocnemius (WG), red gastrocnemius (RG), and soleus. AMPK phosphorylation increased (P < .05) in WG in both lean (57%) and obese (106%), and this was supported by an increase in phospho-ACC in WG. Further, metformin increased IkappaBalpha levels in both WG (150%) and RG (67%) of obese rats, indicative of reduced IKKbeta activity (P < .05), and was associated with reduced IRS1-pSer(307) (30%) in the WG of obese rats (P < .02). From these data we conclude that metformin treatment appears to exert an inhibitory influence on skeletal muscle IKKbeta activity, as evidenced by elevated IkappaBalpha levels and reduced IRS1-Ser(307) phosphorylation in a fiber-type specific manner.
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Affiliation(s)
- Benjamin T. Bikman
- The Metabolic Institute for the Study of Diabetes and Obesity, East Carolina University, Greenville, NC 27834, USA
- Department of Exercise and Sport Science, East Carolina University, Greenville, NC 27834, USA
- *Benjamin T. Bikman:
| | - Donghai Zheng
- The Metabolic Institute for the Study of Diabetes and Obesity, East Carolina University, Greenville, NC 27834, USA
- Department of Exercise and Sport Science, East Carolina University, Greenville, NC 27834, USA
| | - Daniel A. Kane
- The Metabolic Institute for the Study of Diabetes and Obesity, East Carolina University, Greenville, NC 27834, USA
- Department of Exercise and Sport Science, East Carolina University, Greenville, NC 27834, USA
| | - Ethan J. Anderson
- The Metabolic Institute for the Study of Diabetes and Obesity, East Carolina University, Greenville, NC 27834, USA
- Department of Exercise and Sport Science, East Carolina University, Greenville, NC 27834, USA
| | - Tracey L. Woodlief
- The Metabolic Institute for the Study of Diabetes and Obesity, East Carolina University, Greenville, NC 27834, USA
- Department of Physiology, East Carolina University, Greenville, NC 27834, USA
| | - Jesse W. Price
- Department of Biology, East Carolina University, Greenville, NC 27834, USA
| | - G. Lynis Dohm
- The Metabolic Institute for the Study of Diabetes and Obesity, East Carolina University, Greenville, NC 27834, USA
- Department of Physiology, East Carolina University, Greenville, NC 27834, USA
| | - P. Darrell Neufer
- The Metabolic Institute for the Study of Diabetes and Obesity, East Carolina University, Greenville, NC 27834, USA
- Department of Physiology, East Carolina University, Greenville, NC 27834, USA
| | - Ronald N. Cortright
- The Metabolic Institute for the Study of Diabetes and Obesity, East Carolina University, Greenville, NC 27834, USA
- Department of Physiology, East Carolina University, Greenville, NC 27834, USA
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Pasquali R, Gambineri A. Targeting insulin sensitivity in the treatment of polycystic ovary syndrome. Expert Opin Ther Targets 2009; 13:1205-26. [PMID: 19650762 DOI: 10.1517/14728220903190699] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Targeting insulin resistance may result in a list of benefits for women with PCOS, including hormonal, metabolic and ovulatory (and fertility) improvements. The therapeutic strategy to treat PCOS should however depend on the clinical situation, the phenotype, the degree of androgen excess, age, the presence of infertility and the woman's desire to conceive, the presence of obesity and, finally, the spectrum of metabolic abnormalities and the need to treat or prevent long-term associated comorbidities. According to the needs, therapeutic options include, alone or in combination, lifestyle management, particularly in the presence of obesity, the use of insulin sensitizers, metformin and thiazolidinediones, antiandrogens or estro-progestins.
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Affiliation(s)
- Renato Pasquali
- University Alma Mater Studiorum, S. Orsola-Malpighi Hospital, Division of Endocrinology, Department of Clinical Medicine, Bologna, Italy.
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Hu Z, Wang Y, Qiao J, Li M, Chi H, Chen X. The role of family history in clinical symptoms and therapeutic outcomes of women with polycystic ovary syndrome. Int J Gynaecol Obstet 2009; 108:35-9. [DOI: 10.1016/j.ijgo.2009.08.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2009] [Revised: 07/11/2009] [Accepted: 08/12/2009] [Indexed: 10/20/2022]
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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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Hegarty BD, Turner N, Cooney GJ, Kraegen EW. Insulin resistance and fuel homeostasis: the role of AMP-activated protein kinase. Acta Physiol (Oxf) 2009; 196:129-45. [PMID: 19245658 DOI: 10.1111/j.1748-1716.2009.01968.x] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The worldwide prevalence of type 2 diabetes (T2D) and related disorders of the metabolic syndrome (MS) has reached epidemic proportions. Insulin resistance (IR) is a major perturbation that characterizes these disorders. Extra-adipose accumulation of lipid, particularly within the liver and skeletal muscle, is closely linked with the development of IR. The AMP-activated protein kinase (AMPK) pathway plays an important role in the regulation of both lipid and glucose metabolism. Through its effects to increase fatty acid oxidation and inhibit lipogenesis, AMPK activity in the liver and skeletal muscle could be expected to ameliorate lipid accumulation and associated IR in these tissues. In addition, AMPK promotes glucose uptake into skeletal muscle and suppresses glucose output from the liver via insulin-independent mechanisms. These characteristics make AMPK a highly attractive target for the development of strategies to curb the prevalence and costs of T2D. Recent insights into the regulation of AMPK and mechanisms by which it modulates fuel metabolism in liver and skeletal muscle are discussed here. In addition, we consider the arguments for and against the hypothesis that dysfunctional AMPK contributes to IR. Finally we review studies which assess AMPK as an appropriate target for the prevention and treatment of T2D and MS.
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Affiliation(s)
- B D Hegarty
- Diabetes and Obesity Research Program, Garvan Institute of Medical Research, 384 Victoria Street, Darlinghurst, NSW 2010, Australia.
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Hallén S, Clapham JC. Cell based in vitro and ex vivo models in metabolic disease drug discovery: nice to have or critical path? Expert Opin Drug Discov 2009; 4:417-28. [PMID: 23485042 DOI: 10.1517/17460440902821640] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
BACKGROUND The use of cellular models as tools in drug discovery is almost universal. However, in disease areas such as metabolic diseases, are they relevant to the process and do they add value? OBJECTIVE In this article, we explore the variety of cellular models now used in drug discovery in metabolic diseases as revealed by publication. We have tried to make some connections between drug phenotypes in these models with clinical parallels. We also ask the question as to whether such models add value in the drug discovery process. This overview is not about recombinant cell systems used in target-based screening; rather, we focus on in vitro, including ex vivo, models as physiological systems in drug discovery in obesity and diabetes. CONCLUSION In terms of building target confidence, in vitro models are often the only mechanistic link to human systems early in a projects life. Many of the current targets in metabolic diseases in the early discovery phase are not yet clinically supported, let alone validated. In this respect, therefore, in vitro models warrant a place in the critical path in early discovery. In terms of any predictive role for decision-making today, this is much more difficult and is more likely pushed to a supporting role as part of a wider package. However, there is a rapid rate of advancement in this field and future developments hold much promise.
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Affiliation(s)
- Stefan Hallén
- Departments of Bioscience, AstraZeneca R&D Mölndal, Sweden +46 31 7064339 ; +46 31 7763700 ;
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Foretz M, Viollet B. Mécanisme d’action hépatique de la metformine dans le diabète de type 2. ACTA ACUST UNITED AC 2009. [DOI: 10.1016/s1957-2557(09)70104-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Purushotham A, Tian M, Belury MA. The citrus fruit flavonoid naringenin suppresses hepatic glucose production from Fao hepatoma cells. Mol Nutr Food Res 2008; 53:300-7. [DOI: 10.1002/mnfr.200700514] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Basu R, Basu A, Chandramouli V, Norby B, Dicke B, Shah P, Cohen O, Landau BR, Rizza RA. Effects of pioglitazone and metformin on NEFA-induced insulin resistance in type 2 diabetes. Diabetologia 2008; 51:2031-40. [PMID: 18769904 PMCID: PMC2701394 DOI: 10.1007/s00125-008-1138-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/21/2008] [Accepted: 07/23/2008] [Indexed: 11/26/2022]
Abstract
AIMS/HYPOTHESIS We sought to determine whether pioglitazone and metformin alter NEFA-induced insulin resistance in type 2 diabetes and, if so, the mechanism whereby this is effected. METHODS Euglycaemic-hyperinsulinaemic clamps (glucose approximately 5.3 mmol/l, insulin approximately 200 pmol/l) were performed in the presence of Intralipid-heparin (IL/H) or glycerol before and after 4 months of treatment with pioglitazone (n = 11) or metformin (n = 9) in diabetic participants. Hormone secretion was inhibited with somatostatin in all participants. RESULTS Pioglitazone increased insulin-stimulated glucose disappearance (p < 0.01) and increased insulin-induced suppression of glucose production (p < 0.01), gluconeogenesis (p < 0.05) and glycogenolysis (p < 0.05) during IL/H. However, glucose disappearance remained lower (p < 0.05) whereas glucose production (p < 0.01), gluconeogenesis (p < 0.05) and glycogenolysis (p < 0.05) were higher on the IL/H study day than on the glycerol study day, indicating persistence of NEFA-induced insulin resistance. Metformin increased (p < 0.001) glucose disappearance during IL/H to rates present during glycerol treatment, indicating protection against NEFA-induced insulin resistance in extrahepatic tissues. However, glucose production and gluconeogenesis (but not glycogenolysis) were higher (p < 0.01) during IL/H than during glycerol treatment with metformin, indicating persistence of NEFA-induced hepatic insulin resistance. CONCLUSIONS/INTERPRETATION We conclude that pioglitazone improves both the hepatic and the extrahepatic action of insulin but does not prevent NEFA-induced insulin resistance. In contrast, whereas metformin prevents NEFA-induced extrahepatic insulin resistance, it does not protect against NEFA-induced hepatic insulin resistance.
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Affiliation(s)
- R. Basu
- Division of Endocrinology, Diabetes, Metabolism and Nutrition, Mayo Clinic College of Medicine, 200 1st Street SW, Room 5-194 Joseph, Rochester, MN 55905, USA
| | - A. Basu
- Division of Endocrinology, Diabetes, Metabolism and Nutrition, Mayo Clinic College of Medicine, 200 1st Street SW, Room 5-194 Joseph, Rochester, MN 55905, USA
| | - V. Chandramouli
- Division of Clinical and Molecular Endocrinology, Case Western Reserve University School of Medicine, Cleveland, OH, USA
| | - B. Norby
- Division of Endocrinology, Diabetes, Metabolism and Nutrition, Mayo Clinic College of Medicine, 200 1st Street SW, Room 5-194 Joseph, Rochester, MN 55905, USA
| | - B. Dicke
- Division of Endocrinology, Diabetes, Metabolism and Nutrition, Mayo Clinic College of Medicine, 200 1st Street SW, Room 5-194 Joseph, Rochester, MN 55905, USA
| | - P. Shah
- Department of Endocrine Neoplasia and Hormonal Disorders, University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - O. Cohen
- Institute of Endocrinology, Chaim Sheba Medical Center, Tel Hashomer, Israel
| | - B. R. Landau
- Division of Clinical and Molecular Endocrinology, Case Western Reserve University School of Medicine, Cleveland, OH, USA
| | - R. A. Rizza
- Division of Endocrinology, Diabetes, Metabolism and Nutrition, Mayo Clinic College of Medicine, 200 1st Street SW, Room 5-194 Joseph, Rochester, MN 55905, USA
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Romualdi D, Costantini B, Selvaggi L, Giuliani M, Cristello F, Macri F, Bompiani A, Lanzone A, Guido M. Metformin improves endothelial function in normoinsulinemic PCOS patients: a new prospective. Hum Reprod 2008; 23:2127-33. [DOI: 10.1093/humrep/den230] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Abstract
Insulin resistance is characteristic of obesity, type 2 diabetes, and components of the cardiometabolic syndrome, including hypertension and dyslipidemia, that collectively contribute to a substantial risk for cardiovascular disease. Metabolic actions of insulin in classic insulin target tissues (eg, skeletal muscle, fat, and liver), as well as actions in nonclassic targets (eg, cardiovascular tissue), help to explain why insulin resistance and metabolic dysregulation are central in the pathogenesis of the cardiometabolic syndrome and cardiovascular disease. Glucose and lipid metabolism are largely dependent on mitochondria to generate energy in cells. Thereby, when nutrient oxidation is inefficient, the ratio of ATP production/oxygen consumption is low, leading to an increased production of superoxide anions. Reactive oxygen species formation may have maladaptive consequences that increase the rate of mutagenesis and stimulate proinflammatory processes. In addition to reactive oxygen species formation, genetic factors, aging, and reduced mitochondrial biogenesis all contribute to mitochondrial dysfunction. These factors also contribute to insulin resistance in classic and nonclassic insulin target tissues. Insulin resistance emanating from mitochondrial dysfunction may contribute to metabolic and cardiovascular abnormalities and subsequent increases in cardiovascular disease. Furthermore, interventions that improve mitochondrial function also improve insulin resistance. Collectively, these observations suggest that mitochondrial dysfunction may be a central cause of insulin resistance and associated complications. In this review, we discuss mechanisms of mitochondrial dysfunction related to the pathophysiology of insulin resistance in classic insulin-responsive tissue, as well as cardiovascular tissue.
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Affiliation(s)
- Jeong-A Kim
- Department of Internal Medicine, University of Missouri-Columbia School of Medicine, Columbia, Missouri, USA
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49
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Polkinghorne E, Lau Q, Cooney GJ, Kraegen EW, Cleasby ME. Local activation of the IkappaK-NF-kappaB pathway in muscle does not cause insulin resistance. Am J Physiol Endocrinol Metab 2008; 294:E316-25. [PMID: 18029440 DOI: 10.1152/ajpendo.00537.2007] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Insulin resistance of skeletal muscle is a major defect in obesity and type 2 diabetes. Insulin resistance has been associated with a chronic subclinical inflammatory state in epidemiological studies and specifically with activation of the inhibitor kappaB kinase (IkappaBK)-nuclear factor-kappaB (NF-kappaB) pathway. However, it is unclear whether this pathway plays a role in mediating insulin resistance in muscle in vivo. We separately overexpressed the p65 subunit of NF-kappaB and IkappaBKbeta in single muscles of rats using in vivo electrotransfer and compared the effects after 1 wk vs. paired contralateral control muscles. A 64% increase in p65 protein (P < 0.001) was sufficient to cause muscle fiber atrophy but had no effect on glucose disposal or glycogen storage in muscle under hyperinsulinemic-euglycemic clamp conditions. Similarly, a 650% increase in IkappaBKbeta expression (P < 0.001) caused a significant reduction in IkappaB protein but also had no effect on clamp glucose disposal after lipid infusion. In fact, IkappaBKbeta overexpression in particular caused increases in activating tyrosine phosphorylation of insulin receptor substrate-1 (24%; P = 0.02) and serine phosphorylation of Akt (23%; P < 0.001), implying a moderate increase in flux through the insulin signaling cascade. Interestingly, p65 overexpression resulted in a negative feedback reduction of 36% in Toll-like receptor (TLR)-2 (P = 0.03) but not TLR-4 mRNA. In conclusion, activation of the IkappaBKbeta-NF-kappaB pathway in muscle does not seem to be an important local mediator of insulin resistance.
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Affiliation(s)
- Emma Polkinghorne
- Department of Veterinary Basic Sciences, Royal Veterinary College, Royal College Street, London, United Kingdom
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50
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Zhang Z, Li X, Lv W, Yang Y, Gao H, Yang J, Shen Y, Ning G. Ginsenoside Re reduces insulin resistance through inhibition of c-Jun NH2-terminal kinase and nuclear factor-kappaB. Mol Endocrinol 2007; 22:186-95. [PMID: 17885204 PMCID: PMC5419627 DOI: 10.1210/me.2007-0119] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Ginsenoside Re (Re), a compound derived from Panax ginseng, shows an antidiabetic effect. However, the molecular basis of its action remains unknown. We investigated insulin signaling and the antiinflammatory effect by Re in 3T3-L1 adipocytes and in high-fat diet (HFD) rats to dissect its anti-hyperglycemic mechanism. Glucose uptake was measured in 3T3-L1 cells and glucose infusion rate determined by clamp in HFD rats. The insulin signaling cascade, including insulin receptor (IR) beta-subunit, IR substrate-1, phosphatidylinositol 3-kinase, Akt and Akt substrate of 160 kDa, and glucose transporter-4 translocation are examined. Furthermore, c-Jun NH(2)-terminal kinase (JNK), MAPK, and nuclear factor (NF)-kappaB signaling cascades were also assessed. The results show Re increases glucose uptake in 3T3-L1 cells and glucose infusion rate in HFD rats. The activation of insulin signaling by Re is initiated at IR substrate-1 and further passes on through phosphatidylinositol 3-kinase and downstream signaling cascades. Moreover, Re demonstrates an impressive suppression of JNK and NF-kappaB activation and inhibitor of NF-kappaBalpha degradation. In conclusion, Re reduces insulin resistance in 3T3-L1 adipocytes and HFD rats through inhibition of JNK and NF-kappaB activation.
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Affiliation(s)
- Zhiguo Zhang
- Laboratory of Endocrinology and Metabolism, Institute of Health Sciences, Rui-Jin Hospital, Shanghai Jiao-Tong University School of Medicine, 197 Rui-Jin 2nd Road, Shanghai 200025, China
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