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Lin L, Burke J, Venkatesh S, Sadana P. AMPK-SIRT1-independent inhibition of ANGPTL3 gene expression is a potential lipid-lowering mechanism of metformin. J Pharm Pharmacol 2019; 71:1421-1428. [DOI: 10.1111/jphp.13138] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2019] [Accepted: 06/02/2019] [Indexed: 02/06/2023]
Abstract
Abstract
Objectives
Hypertriglyceridaemia enhances cardiovascular disease risk in patients with diabetes. Lipoprotein lipase (LPL) regulates plasma triglyceride levels by hydrolysing chylomicrons and very-low-density lipoprotein (VLDL). Metformin, an antidiabetic drug, improves plasma lipids including triglycerides. We examined metformin's regulation of angiopoietin-like 3 (ANGPTL3), a liver-derived secretory protein with LPL inhibitory property.
Methods
Using HepG2 cells, a human hepatocyte cell line, the effects of metformin on ANGPTL3 gene and protein expression were determined. The role of AMPK-SIRT1 pathway in metformin regulation of ANGPTL3 was determined using pharmacological, RNAi and reporter assays. Metformin regulation of ANGPTL3 expression was also examined in sodium palmitate-induced insulin resistance.
Key findings
Metformin and pharmacological activators of AMPK and SIRT1 inhibited the expression of ANGPTL3 in HepG2 cells. Pharmacological or RNAi-based antagonism of AMPK or SIRT1 failed to affect metformin inhibition of ANGPTL3. AMPK-SIRT1 activators and metformin exhibited distinct effects on the expression of ANGPTL3 gene luciferase reporter. Sodium palmitate-induced insulin resistance in cells resulted in increased ANGPTL3 gene expression which was suppressed by pretreatment with metformin.
Conclusions
Metformin inhibits ANGPTL3 expression in the liver in an AMPK-SIRT1-independent manner as a potential mechanism to regulate LPL and lower plasma lipids.
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Affiliation(s)
- Li Lin
- Department of Pharmaceutical Sciences, College of Pharmacy, Northeast Ohio Medical University, Rootstown, OH, USA
| | - Jamie Burke
- Department of Pharmaceutical Sciences, College of Pharmacy, Northeast Ohio Medical University, Rootstown, OH, USA
| | - Sahana Venkatesh
- Department of Pharmaceutical Sciences, College of Pharmacy, Northeast Ohio Medical University, Rootstown, OH, USA
| | - Prabodh Sadana
- Department of Pharmaceutical Sciences, College of Pharmacy, Northeast Ohio Medical University, Rootstown, OH, USA
- Department of Pharmacy Practice, College of Pharmacy, Northeast Ohio Medical University, Rootstown, OH, USA
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2
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Tokubuchi I, Tajiri Y, Iwata S, Hara K, Wada N, Hashinaga T, Nakayama H, Mifune H, Yamada K. Beneficial effects of metformin on energy metabolism and visceral fat volume through a possible mechanism of fatty acid oxidation in human subjects and rats. PLoS One 2017; 12:e0171293. [PMID: 28158227 PMCID: PMC5291441 DOI: 10.1371/journal.pone.0171293] [Citation(s) in RCA: 80] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2015] [Accepted: 01/19/2017] [Indexed: 12/20/2022] Open
Abstract
OBJECTIVE Metformin is known to have a beneficial effect on body weight and body composition, although the precise mechanism has not been elucidated yet. The aim of this study is to investigate the effects of metformin on energy metabolism and anthropometric factors in both human subjects and rats. METHODS In human studies, metformin (1500mg/day) was administered to 23 healthy subjects and 18 patients with type 2 diabetes for 2 weeks. Metabolic parameters and energy metabolism were measured during a meal tolerance test in the morning before and after the treatment of metformin. In animal studies, 13 weeks old SD rats were fed 25-26 g of standard chow only during 12-hours dark phase with either treated by metformin (2.5mg/ml in drinking water) or not for 2 weeks, and metabolic parameters, anthropometric factors and energy metabolism together with expressions related to fat oxidation and adaptive thermogenesis were measured either in fasting or post-prandial state at 15 weeks old. RESULTS Post-prandial plasma lactate concentration was significantly increased after the metformin treatment in both healthy subjects and diabetic patients. Although energy expenditure (EE) did not change, baseline respiratory quotient (RQ) was significantly decreased and post-prandial RQ was significantly increased vice versa following the metformin treatment in both groups. By the administration of metformin to SD rats for 2 weeks, plasma levels of lactate and pyruvate were significantly increased in both fasting and post-prandial states. RQ during a fasting state was significantly decreased in metformin-treated rats compared to controls with no effect on EE. Metformin treatment brought about a significant reduction of visceral fat mass compared to controls accompanied by an up-regulation of fat oxidation-related enzyme in the liver, UCP-1 in the brown adipose tissue and UCP-3 in the skeletal muscle. CONCLUSION From the results obtained, beneficial effects of metformin on visceral fat reduction has been demonstrated probably through a mechanism for a potential shift of fuel resource into fat oxidation and an upregulation of adaptive thermogenesis independent of an anorexigenic effect of this drug.
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Affiliation(s)
- Ichiro Tokubuchi
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Kurume University School of Medicine, Kurume, Japan
| | - Yuji Tajiri
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Kurume University School of Medicine, Kurume, Japan
| | - Shimpei Iwata
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Kurume University School of Medicine, Kurume, Japan
| | - Kento Hara
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Kurume University School of Medicine, Kurume, Japan
| | - Nobuhiko Wada
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Kurume University School of Medicine, Kurume, Japan
| | - Toshihiko Hashinaga
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Kurume University School of Medicine, Kurume, Japan
| | - Hitomi Nakayama
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Kurume University School of Medicine, Kurume, Japan
| | - Hiroharu Mifune
- Institute of Animal Experimentation, Kurume University School of Medicine, Kurume, Japan
| | - Kentaro Yamada
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Kurume University School of Medicine, Kurume, Japan
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3
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Evans RD, Hauton D. The role of triacylglycerol in cardiac energy provision. Biochim Biophys Acta Mol Cell Biol Lipids 2016; 1861:1481-91. [DOI: 10.1016/j.bbalip.2016.03.010] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2016] [Revised: 03/08/2016] [Accepted: 03/09/2016] [Indexed: 02/07/2023]
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Bairwa SC, Parajuli N, Dyck JRB. The role of AMPK in cardiomyocyte health and survival. Biochim Biophys Acta Mol Basis Dis 2016; 1862:2199-2210. [PMID: 27412473 DOI: 10.1016/j.bbadis.2016.07.001] [Citation(s) in RCA: 99] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2016] [Revised: 07/05/2016] [Accepted: 07/05/2016] [Indexed: 01/09/2023]
Abstract
Cellular energy homeostasis is a fundamental process that governs the overall health of the cell and is paramount to cell survival. Central to this is the control of ATP generation and utilization, which is regulated by a complex myriad of enzymatic reactions controlling cellular metabolism. In the cardiomyocyte, ATP generated from substrate catabolism is used for numerous cellular processes including maintaining ionic homeostasis, cell repair, protein synthesis and turnover, organelle turnover, and contractile function. In many instances, cardiovascular disease is associated with impaired cardiac energetics and thus the signalling that regulates pathways involved in cardiomyocyte metabolism may be potential targets for pharmacotherapy designed to help treat cardiovascular disease. An important regulator of cardiomyocyte energy homeostasis is adenosine monophosphate-activated protein kinase (AMPK). AMPK is a serine-threonine kinase that functions primarily as a metabolic sensor to coordinate anabolic and catabolic activities in the cell via the phosphorylation of multiple proteins involved in metabolic pathways. In addition to the direct role that AMPK plays in the regulation of cardiomyocyte metabolism, AMPK can also either directly or indirectly influence other cellular processes such as regulating mitochondrial function, post-translation acetylation, autophagy, mitophagy, endoplasmic reticulum stress, and apoptosis. Thus, AMPK is implicated in the control of a wide variety of cellular processes that can influence cardiomyocyte health and survival. In this review, we will discuss the important role that AMPK plays in regulating cardiac metabolism, as well as the additional cellular processes that may contribute to cardiomyocyte function and survival in the healthy and the diseased heart. This article is part of a Special Issue entitled: The role of post-translational protein modifications on heart and vascular metabolism edited by Jason R.B. Dyck & Jan. F.C. Glatz.
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Affiliation(s)
- Suresh C Bairwa
- Department of Medicine, Faculty of Medicine and Dentistry, Cardiovascular Research Centre, University of Alberta, Edmonton, Alberta, Canada
| | - Nirmal Parajuli
- Department of Medicine, Faculty of Medicine and Dentistry, Cardiovascular Research Centre, University of Alberta, Edmonton, Alberta, Canada
| | - Jason R B Dyck
- Department of Medicine, Faculty of Medicine and Dentistry, Cardiovascular Research Centre, University of Alberta, Edmonton, Alberta, Canada; Department of Pediatrics, Faculty of Medicine and Dentistry, Cardiovascular Research Centre, University of Alberta, Edmonton, Alberta, Canada.
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Singh J, Olle B, Suhail H, Felicella MM, Giri S. Metformin-induced mitochondrial function and ABCD2 up-regulation in X-linked adrenoleukodystrophy involves AMP-activated protein kinase. J Neurochem 2016; 138:86-100. [DOI: 10.1111/jnc.13562] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2015] [Revised: 12/29/2015] [Accepted: 01/25/2016] [Indexed: 12/25/2022]
Affiliation(s)
- Jaspreet Singh
- Department of Neurology; Henry Ford Health System; Detroit Michigan USA
| | - Brittany Olle
- Department of Neurology; Henry Ford Health System; Detroit Michigan USA
| | - Hamid Suhail
- Department of Neurology; Henry Ford Health System; Detroit Michigan USA
| | | | - Shailendra Giri
- Department of Neurology; Henry Ford Health System; Detroit Michigan USA
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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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Yao XM, Ye SD, Xiao CC, Gu JF, Yang D, Wang S. Metformin alleviates high glucose-mediated oxidative stress in rat glomerular mesangial cells by modulation of p38 mitogen-activated protein kinase expression in vitro. Mol Med Rep 2015; 12:520-6. [PMID: 25760137 DOI: 10.3892/mmr.2015.3446] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2014] [Accepted: 02/13/2015] [Indexed: 11/05/2022] Open
Abstract
The aim of the current study was to investigate the effects and mechanism of metformin in oxidative stress and p38 mitogen-activated protein kinase (p38MAPK) expression in rat glomerular mesangial cells (MCs) cultured in a high glucose medium. Rat glomerular MCs (HBZY-1) were cultured in complete medium and divided into the following five groups: Normal control (NC), high glucose (HG), metformin-treated, SB203580-treated (SB) and N-acetylcysteine-treated (NAC). The production of intracellular reactive oxygen species (ROS) in rat glomerular MCs was measured using flow cytometry. Superoxide dismutase (SOD) activity and malondialdehyde (MDA) content in the supernatant was detected using colorimetric analysis and an ELISA, respectively. p22phox mRNA levels in rat glomerular MCs were determined using reverse transcription-quantitative polymerase chain reaction. The levels of p22phox protein and phosphorylated p38 mitogen-activated protein kinase (p-p38MAPK) protein in rat glomerular MCs were determined by western blot analysis. Compared with the NC group, the activity of SOD in the supernatant was significantly reduced, whereas the levels of MDA in the supernatant, intracellular p22phox mRNA and protein, p-p38MAPK protein in addition to ROS production in rat glomerular MCs were significantly increased in the HG group (P<0.05). When metformin was added to the high glucose medium, the activity of SOD in supernatant fluid was increased significantly, whereas a significant reduction (P<0.05) was observed in the levels of MDA in the supernatant, intracellular p22phox mRNA and protein, p-p38MAPK protein in addition to ROS production in rat glomerular MCs. These results were similar to those obtained when SB203580 or N-acetylcysteine was added to the high glucose medium (P<0.05). In conclusion, metformin was suggested to alleviate high glucose-induced oxidative stress and p-p38MAPK protein expression in rat glomerular MCs, which may contribute to its reno‑protective abilities in diabetes.
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Affiliation(s)
- Xin-Ming Yao
- Department of Endocrinology, Anhui Provincial Hospital Affiliated to Anhui Medical University, Hefei, Anhui 230001, P.R. China
| | - Shan-Dong Ye
- Department of Endocrinology, Anhui Provincial Hospital Affiliated to Anhui Medical University, Hefei, Anhui 230001, P.R. China
| | - Chun-Chun Xiao
- Department of Endocrinology, Anhui Provincial Hospital Affiliated to Anhui Medical University, Hefei, Anhui 230001, P.R. China
| | - Jun-Fei Gu
- Department of Endocrinology, Anhui Provincial Hospital Affiliated to Anhui Medical University, Hefei, Anhui 230001, P.R. China
| | - Di Yang
- Department of Endocrinology, Anhui Provincial Hospital Affiliated to Anhui Medical University, Hefei, Anhui 230001, P.R. China
| | - Shan Wang
- Department of Endocrinology, Anhui Provincial Hospital Affiliated to Anhui Medical University, Hefei, Anhui 230001, P.R. China
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Hauton D, Winter J, Al-Shammari AA, Gaffney EA, Evans RD, Egginton S. Changes to both cardiac metabolism and performance accompany acute reductions in functional capillary supply. Biochim Biophys Acta Gen Subj 2014; 1850:681-90. [PMID: 25529297 DOI: 10.1016/j.bbagen.2014.12.014] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2014] [Revised: 11/14/2014] [Accepted: 12/12/2014] [Indexed: 10/24/2022]
Abstract
BACKGROUND The relative importance of arteriole supply or ability to switch between substrates to preserve cardiac performance is currently unclear, but may be critically important in conditions such as diabetes. METHODS Metabolism of substrates was measured before and after infusion of polystyrene microspheres in the perfused working heart to mimic random capillary loss due to microvascular disease. The effect of acute loss of functional capillary supply on palmitate and glucose metabolism together with function was quantified, and theoretical tissue oxygen distribution calculated from histological samples and ventricular VO(2) estimated. RESULTS Microsphere infusion led to a dose-dependent decrease in rate-pressure product (RPP) and oxygen consumption (P<0.001). Microsphere infusion also increased work/unit oxygen consumption of hearts ('efficiency') by 25% (P<0.01). When corrected for cardiac work palmitate oxidation remained tightly coupled to very low workloads (RPP<2500 mmHg/min), illustrating a high degree of metabolic control. Arteriole occlusion by microspheres decreased the density of patent capillaries (P<0.001) and correspondingly increased the average capillary supply area by 40% (P<0.01). Calculated rates of oxygen consumption declined from 16.6±7.2 ml/100 ml/min to 12.4±9 ml/100 ml/min following arteriole occlusion, coupled with increases in size of regions of myocardial hypoxia (Control=22.0% vs. Microspheres=42.2%). CONCLUSIONS Cardiac mechanical performance is very sensitive to arteriolar blockade, but metabolite switching from fatty acid to glucose utilisation may also support cardiac function in regions of declining PO(2). GENERAL SIGNIFICANCE Preserving functional capillary supply may be critical for maintenance of cardiac function when metabolic flexibility is lost, as in diabetes.
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Affiliation(s)
- David Hauton
- School of Food Science and Nutrition, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, United Kingdom.
| | - James Winter
- Cardiovascular Physiology, The Rayne Institute, King's College London, London SE1 7EH, United Kingdom
| | - Abdullah A Al-Shammari
- Mathematical Institute, University of Oxford, Woodstock Road, Oxford OX2 6GG, United Kingdom; Department of Mathematics, Faculty of Sciences, Kuwait University, P.O. Box 5969, Khaldiya 13060, Kuwait
| | - Eamonn A Gaffney
- Mathematical Institute, University of Oxford, Woodstock Road, Oxford OX2 6GG, United Kingdom
| | - Rhys D Evans
- Department of Physiology, Anatomy and Genetics, Sherrington Building, University of Oxford, South Parks Road, Oxford OX1 3PT, United Kingdom
| | - Stuart Egginton
- School of Biomedical Sciences, University of Leeds, Clarendon Way, Leeds LS2 9JT, United Kingdom
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Kersten S. Physiological regulation of lipoprotein lipase. Biochim Biophys Acta Mol Cell Biol Lipids 2014; 1841:919-33. [PMID: 24721265 DOI: 10.1016/j.bbalip.2014.03.013] [Citation(s) in RCA: 341] [Impact Index Per Article: 34.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2014] [Revised: 03/27/2014] [Accepted: 03/30/2014] [Indexed: 01/01/2023]
Abstract
The enzyme lipoprotein lipase (LPL), originally identified as the clearing factor lipase, hydrolyzes triglycerides present in the triglyceride-rich lipoproteins VLDL and chylomicrons. LPL is primarily expressed in tissues that oxidize or store fatty acids in large quantities such as the heart, skeletal muscle, brown adipose tissue and white adipose tissue. Upon production by the underlying parenchymal cells, LPL is transported and attached to the capillary endothelium by the protein GPIHBP1. Because LPL is rate limiting for plasma triglyceride clearance and tissue uptake of fatty acids, the activity of LPL is carefully controlled to adjust fatty acid uptake to the requirements of the underlying tissue via multiple mechanisms at the transcriptional and post-translational level. Although various stimuli influence LPL gene transcription, it is now evident that most of the physiological variation in LPL activity, such as during fasting and exercise, appears to be driven via post-translational mechanisms by extracellular proteins. These proteins can be divided into two main groups: the liver-derived apolipoproteins APOC1, APOC2, APOC3, APOA5, and APOE, and the angiopoietin-like proteins ANGPTL3, ANGPTL4 and ANGPTL8, which have a broader expression profile. This review will summarize the available literature on the regulation of LPL activity in various tissues, with an emphasis on the response to diverse physiological stimuli.
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Affiliation(s)
- Sander Kersten
- Nutrition, Metabolism and Genomics Group, Division of Human Nutrition, Wageningen University, Bomenweg 2, 6703HD Wageningen, The Netherlands
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Fatty acid-inducible ANGPTL4 governs lipid metabolic response to exercise. Proc Natl Acad Sci U S A 2014; 111:E1043-52. [PMID: 24591600 DOI: 10.1073/pnas.1400889111] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Physical activity increases energy metabolism in exercising muscle. Whether acute exercise elicits metabolic changes in nonexercising muscles remains unclear. We show that one of the few genes that is more highly induced in nonexercising muscle than in exercising human muscle during acute exercise encodes angiopoietin-like 4 (ANGPTL4), an inhibitor of lipoprotein lipase-mediated plasma triglyceride clearance. Using a combination of human, animal, and in vitro data, we show that induction of ANGPTL4 in nonexercising muscle is mediated by elevated plasma free fatty acids via peroxisome proliferator-activated receptor-δ, presumably leading to reduced local uptake of plasma triglyceride-derived fatty acids and their sparing for use by exercising muscle. In contrast, the induction of ANGPTL4 in exercising muscle likely is counteracted via AMP-activated protein kinase (AMPK)-mediated down-regulation, promoting the use of plasma triglycerides as fuel for active muscles. Our data suggest that nonexercising muscle and the local regulation of ANGPTL4 via AMPK and free fatty acids have key roles in governing lipid homeostasis during exercise.
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Boyda HN, Procyshyn RM, Asiri Y, Wu C, Wang CK, Lo R, Pang CCY, Honer WG, Barr AM. Antidiabetic-drug combination treatment for glucose intolerance in adult female rats treated acutely with olanzapine. Prog Neuropsychopharmacol Biol Psychiatry 2014; 48:170-6. [PMID: 24140931 DOI: 10.1016/j.pnpbp.2013.10.006] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/14/2013] [Revised: 09/23/2013] [Accepted: 10/07/2013] [Indexed: 01/06/2023]
Abstract
Second generation antipsychotic drugs are routinely used as treatment for psychotic disorders. Many of these compounds, including olanzapine, cause metabolic side-effects such as impaired glucose tolerance and insulin resistance. Individual antidiabetic drugs can help control elevated glucose levels in patients treated with antipsychotics, but the effects of combining antidiabetics, which routinely occurs with Type 2 diabetes mellitus patients, have never been studied. Presently, we compared the effects of the three different antidiabetics metformin (500mg/kg, p.o.), rosiglitazone (30mg/kg, p.o.) and glyburide (10mg/kg, p.o.) on metabolic dysregulation in adult female rats treated acutely with olanzapine. In addition, dual combinations of each of these antidiabetics were compared head-to-head against each other and the individual drugs. The animals received two daily treatments with antidiabetics and were then treated acutely with olanzapine (10mg/kg, i.p.). Fasting glucose and insulin levels were measured, followed by a 2h glucose tolerance test. Olanzapine caused a large and highly significant glucose intolerance compared to vehicle treated rats. Rosiglitazone decreased glucose levels non-significantly, while both metformin and glyburide significantly decreased glucose levels compared to olanzapine-only treated animals. For antidiabetic dual-drug combinations, the rosiglitazone-metformin group showed an unexpected increase in glucose levels compared to all of the single antidiabetic drugs. However, both the metformin-glyburide and rosiglitazone-glyburide groups showed significantly greater reductions in glucose levels following olanzapine than with single drug treatment alone for metformin or rosiglitazone, bringing glucose levels down to values equivalent to vehicle-only treated animals. These findings indicate that further study of antidiabetic dual-drug combinations in patients treated with antipsychotic drugs is warranted.
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Affiliation(s)
- Heidi N Boyda
- Department of Anesthesiology, Pharmacology & Therapeutics, University of British Columbia, 2176 Health Sciences Mall, Vancouver, BC V6T 1Z3, Canada
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Pojoga LH, Yao TM, Opsasnick LA, Garza AE, Reslan OM, Adler GK, Williams GH, Khalil RA. Dissociation of hyperglycemia from altered vascular contraction and relaxation mechanisms in caveolin-1 null mice. J Pharmacol Exp Ther 2013; 348:260-70. [PMID: 24281385 DOI: 10.1124/jpet.113.209189] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Hyperglycemia and endothelial dysfunction are associated with hypertension, but the specific causality and genetic underpinning are unclear. Caveolin-1 (cav-1) is a plasmalemmal anchoring protein and modulator of vascular function and glucose homeostasis. Cav-1 gene variants are associated with reduced insulin sensitivity in hypertensive individuals, and cav-1(-/-) mice show endothelial dysfunction, hyperglycemia, and increased blood pressure (BP). On the other hand, insulin-sensitizing therapy with metformin may inadequately control hyperglycemia while affecting the vascular outcome in certain patients with diabetes. To test whether the pressor and vascular changes in cav-1 deficiency states are related to hyperglycemia and to assess the vascular mechanisms of metformin under these conditions, wild-type (WT) and cav-1(-/-) mice were treated with either placebo or metformin (400 mg/kg daily for 21 days). BP and fasting blood glucose were in cav-1(-/-) > WT and did not change with metformin. Phenylephrine (Phe)- and KCl-induced aortic contraction was in cav-1(-/-) < WT; endothelium removal, the nitric-oxide synthase (NOS) blocker L-NAME (N(ω)-nitro-L-arginine methyl ester), or soluble guanylate cyclase (sGC) inhibitor 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ) enhanced Phe contraction, and metformin blunted this effect. Acetylcholine-induced relaxation was in cav-1(-/-) > WT, abolished by endothelium removal, L-NAME or ODQ, and reduced with metformin. Nitric oxide donor sodium nitroprusside was more potent in inducing relaxation in cav-1(-/-) than in WT, and metformin reversed this effect. Aortic eNOS, AMPK, and sGC were in cav-1(-/-) > WT, and metformin decreased total and phosphorylated eNOS and AMPK in cav-1(-/-). Thus, metformin inhibits both vascular contraction and NO-cGMP-dependent relaxation but does not affect BP or blood glucose in cav-1(-/-) mice, suggesting dissociation of hyperglycemia from altered vascular function in cav-1-deficiency states.
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Affiliation(s)
- Luminita H Pojoga
- Cardiovascular Endocrine Section, Endocrinology, Diabetes and Hypertension Division (L.H.P., T.M.Y., A.E.G., G.K.A., G.H.W.), and Division of Vascular and Endovascular Surgery (L.A.O., O.M.R., R.A.K.), Brigham and Women's Hospital, and Harvard Medical School, Boston, Massachusetts
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Nagendran J, Waller TJ, Dyck JRB. AMPK signalling and the control of substrate use in the heart. Mol Cell Endocrinol 2013; 366:180-93. [PMID: 22750050 DOI: 10.1016/j.mce.2012.06.015] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/12/2011] [Revised: 03/29/2012] [Accepted: 06/21/2012] [Indexed: 12/21/2022]
Abstract
All mammalian cells rely on adenosine triphosphate (ATP) to maintain function and for survival. The heart has the highest basal ATP demand of any organ due to the necessity for continuous contraction. As such, the ability of the cardiomyocyte to monitor cellular energy status and adapt the supply of substrates to match the energy demand is crucial. One important serine/threonine protein kinase that monitors cellular energy status in the heart is adenosine monophosphate activated protein kinase (AMPK). AMPK is also a key enzyme that controls multiple catabolic and anabolic biochemical pathways in the heart and indirectly plays a crucial role in regulating cardiac function in both physiological and pathophysiological conditions. Herein, we review the involvement of AMPK in myocardial fatty acid and glucose transport and utilization, as it relates to basal cardiac function. We also assess the literature amassed on cardiac AMPK and discuss the controversies surrounding the role of AMPK in physiological and pathophysiological processes in the heart. The work reviewed herein also emphasizes areas that require further investigation for the purpose of eventually translating this information into improved patient care.
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Affiliation(s)
- Jeevan Nagendran
- Cardiovascular Research Centre, Department of Pediatrics, University of Alberta, Edmonton, Alberta, Canada
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Whittington HJ, Hall AR, McLaughlin CP, Hausenloy DJ, Yellon DM, Mocanu MM. Chronic Metformin Associated Cardioprotection Against Infarction: Not Just a Glucose Lowering Phenomenon. Cardiovasc Drugs Ther 2012. [DOI: 10.1007/s10557-012-6425-x] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Boyda HN, Procyshyn RM, Tse L, Hawkes E, Jin CH, Pang CC, Honer WG, Barr AM. Differential effects of 3 classes of antidiabetic drugs on olanzapine-induced glucose dysregulation and insulin resistance in female rats. J Psychiatry Neurosci 2012; 37:407-15. [PMID: 22640703 PMCID: PMC3493097 DOI: 10.1503/jpn.110140] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND The second-generation antipsychotic drug olanzapine is an effective pharmacological treatment for psychosis. However, use of the drug is commonly associated with a range of metabolic side effects, including glucose intolerance and insulin resistance. These symptoms have been accurately modelled in rodents. METHODS We compared the effects of 3 distinct classes of antidiabetic drugs, metformin (100 and 500 mg/kg, oral), rosiglitazone (6 and 30 mg/kg, oral) and glyburide (2 and 10 mg/kg, oral), on olanzapineinduced metabolic dysregulation. After acutely treating female rats with lower (7.5 mg/kg) or higher (15 mg/kg) doses of olanzapine, we assessed glucose intolerance using the glucose tolerance test and measured insulin resistance using the homeostatic model assessment of insulin resistance equation. RESULTS Both doses of olanzapine caused pronounced glucose dysregulation and insulin resistance, which were significantly reduced by treatment with metformin and rosiglitazone; however, glucose tolerance did not fully return to control levels. In contrast, glyburide failed to reverse the glucose intolerance caused by olanzapine despite increasing insulin levels. LIMITATIONS We evaluated a single antipsychotic drug, and it is unknown whether other antipsychotic drugs are similarly affected by antidiabetic treatments. CONCLUSION The present study indicates that oral hypoglycemic drugs that influence hepatic glucose metabolism, such as metformin and rosiglitazone, are more effective in regulating olanzapine-induced glucose dysregulation than drugs primarily affecting insulin release, such as glyburide. The current model may be used to better understand the biological basis of glucose dysregulation caused by olanzapine and how it can be reversed.
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Affiliation(s)
| | | | | | | | | | | | | | - Alasdair M. Barr
- Correspondence to: A.M. Barr, Department of Anesthesiology and Pharmacology, University of British Columbia, 2176 Health Sciences Mall, Vancouver BC V6T 1Z3;
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Malvoisin E. Detection of AMP-activated protein kinase α1 by isoelectric focusing in sera of patients with metabolic diseases. Electrophoresis 2012; 33:2828-32. [DOI: 10.1002/elps.201200092] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2012] [Revised: 04/28/2012] [Accepted: 05/16/2012] [Indexed: 11/06/2022]
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Hauton D, Caldwell GM. Cardiac lipoprotein lipase activity in the hypertrophied heart may be regulated by fatty acid flux. Biochim Biophys Acta Mol Cell Biol Lipids 2011; 1821:627-36. [PMID: 22226882 PMCID: PMC3793859 DOI: 10.1016/j.bbalip.2011.12.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2011] [Revised: 10/14/2011] [Accepted: 12/14/2011] [Indexed: 12/23/2022]
Abstract
Cardiac hypertrophy is characterised by an imbalance between lipid uptake and fatty acid β-oxidation leading to an accumulation of lipids, particularly triacylglycerol (TAG). It is unclear whether uptake mechanisms such as lipoprotein lipase (LPL) can be attenuated to diminish this uptake. Rats were cold acclimated to induce cardiac hypertrophy and increase cardiac LPL. Lipid uptake and metabolism were altered by feeding a ‘Western-style’ high fat diet (WSD) or feeding oxfenicine (2 g/L) in the drinking water. Diastolic stiffness (increased volume change/unit pressure change) was induced in hypertrophied hearts for rats fed WSD (P < 0.05) or WSD + oxfenicine (P < 0.01), although absolute performance of cardiac muscle, estimated from stress–strain calculations was unchanged. Cold acclimation increased cardiac endothelial LPL (P < 0.05) but this was diminished following oxfenicine. Following WSD LPL was further decreased below WSD-fed control hearts (P < 0.05) with no further decrease by oxfenicine supplementation. A negative correlation was noted between plasma TAG and endothelial LPL (correlation coefficient = − 0.654; P < 0.001) but not cardiac TAG concentration. Transcript levels of angiopoietin-like protein-4 (ANGPTL4) were increased 6-fold by WSD (P < 0.05) and increased 15-fold following WSD + oxfenicine (P < 0.001). For CA-hearts fed WSD or WSD + oxfenicine ANGPTL4 mRNA levels were preserved at chow-fed levels. VLDLR protein levels were increased 10-fold (P < 0.01) by CA. ANGPTL4 protein levels were increased 2-fold (P < 0.05) by WSD, but restored following oxfenicine. For CA-hearts WSD increased ANGPTL4 protein levels 3-fold (P < 0.01) with WSD + oxfenicine increasing ANGPTL4 protein 4-fold (P < 0.01). These data suggest that endothelial LPL levels in the heart are altered to maintain FA flux and may exploit ANGPTL4.
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Affiliation(s)
- David Hauton
- School of Clinical and Experimental Medicine, College of Medicinal and Dental Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, United Kingdom.
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