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Thangthaeng N, Rutledge M, Wong JM, Vann PH, Forster MJ, Sumien N. Metformin Impairs Spatial Memory and Visual Acuity in Old Male Mice. Aging Dis 2017; 8:17-30. [PMID: 28203479 PMCID: PMC5287385 DOI: 10.14336/ad.2016.1010] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Accepted: 10/10/2016] [Indexed: 12/11/2022] Open
Abstract
Metformin is an oral anti-diabetic used as first-line therapy for type 2 diabetes. Because benefits of metformin extend beyond diabetes to other age-related pathology, and because its effect on gene expression profiles resembles that of caloric restriction, metformin has a potential as an anti-aging intervention and may soon be assessed as an intervention to extend healthspan. However, beneficial actions of metformin in the central nervous system have not been clearly established. The current study examined the effect of chronic oral metformin treatment on motor and cognitive function when initiated in young, middle-aged, or old male mice. C57BL/6 mice aged 4, 11, or 22 months were randomly assigned to either a metformin group (2 mg/ml in drinking water) or a control group. The mice were monitored weekly for body weight, as well as food and water intake and a battery of behavioral tests for motor, cognitive and visual function was initiated after the first month of treatment. Liver, hippocampus and cortex were collected at the end of the study to assess redox homeostasis. Overall, metformin supplementation in male mice failed to affect blood glucose, body weights and redox homeostasis at any age. It also had no beneficial effect on age-related declines in psychomotor, cognitive or sensory functions. However, metformin treatment had a deleterious effect on spatial memory and visual acuity, and reduced SOD activity in brain regions. These data confirm that metformin treatment may be associated with deleterious effect resulting from the action of metformin on the central nervous system.
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Affiliation(s)
- Nopporn Thangthaeng
- Center for Neuroscience Discovery, Institute for Healthy Aging, University of North Texas Health Science Center at Fort Worth, Fort Worth, TX 76107 USA
| | - Margaret Rutledge
- Center for Neuroscience Discovery, Institute for Healthy Aging, University of North Texas Health Science Center at Fort Worth, Fort Worth, TX 76107 USA
| | - Jessica M Wong
- Center for Neuroscience Discovery, Institute for Healthy Aging, University of North Texas Health Science Center at Fort Worth, Fort Worth, TX 76107 USA
| | - Philip H Vann
- Center for Neuroscience Discovery, Institute for Healthy Aging, University of North Texas Health Science Center at Fort Worth, Fort Worth, TX 76107 USA
| | - Michael J Forster
- Center for Neuroscience Discovery, Institute for Healthy Aging, University of North Texas Health Science Center at Fort Worth, Fort Worth, TX 76107 USA
| | - Nathalie Sumien
- Center for Neuroscience Discovery, Institute for Healthy Aging, University of North Texas Health Science Center at Fort Worth, Fort Worth, TX 76107 USA
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Alternative Interventions to Prevent Oxidative Damage following Ischemia/Reperfusion. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2016; 2016:7190943. [PMID: 28116037 PMCID: PMC5225393 DOI: 10.1155/2016/7190943] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/21/2016] [Revised: 09/23/2016] [Accepted: 10/12/2016] [Indexed: 12/25/2022]
Abstract
Ischemia/reperfusion (I/R) lesions are a phenomenon that occurs in multiple pathological states and results in a series of events that end in irreparable damage that severely affects the recovery and health of patients. The principal therapeutic approaches include preconditioning, postconditioning, and remote ischemic preconditioning, which when used separately do not have a great impact on patient mortality or prognosis. Oxidative stress is known to contribute to the damage caused by I/R; however, there are no pharmacological approaches to limit or prevent this. Here, we explain the relationship between I/R and the oxidative stress process and describe some pharmacological options that may target oxidative stress-states.
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Lawler JM, Rodriguez DA, Hord JM. Mitochondria in the middle: exercise preconditioning protection of striated muscle. J Physiol 2016; 594:5161-83. [PMID: 27060608 PMCID: PMC5023703 DOI: 10.1113/jp270656] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2015] [Accepted: 04/01/2016] [Indexed: 12/24/2022] Open
Abstract
Cellular and physiological adaptations to an atmosphere which became enriched in molecular oxygen spurred the development of a layered system of stress protection, including antioxidant and stress response proteins. At physiological levels reactive oxygen and nitrogen species regulate cell signalling as well as intracellular and intercellular communication. Exercise and physical activity confer a variety of stressors on skeletal muscle and the cardiovascular system: mechanical, metabolic, oxidative. Transient increases of stressors during acute bouts of exercise or exercise training stimulate enhancement of cellular stress protection against future insults of oxidative, metabolic and mechanical stressors that could induce injury or disease. This phenomenon has been termed both hormesis and exercise preconditioning (EPC). EPC stimulates transcription factors such as Nrf-1 and heat shock factor-1 and up-regulates gene expression of a cadre of cytosolic (e.g. glutathione peroxidase and heat shock proteins) and mitochondrial adaptive or stress proteins (e.g. manganese superoxide dismutase, mitochondrial KATP channels and peroxisome proliferator activated receptor γ coactivator-1 (PGC-1)). Stress response and antioxidant enzyme inducibility with exercise lead to protection against striated muscle damage, oxidative stress and injury. EPC may indeed provide significant clinical protection against ischaemia-reperfusion injury, Type II diabetes and ageing. New molecular mechanisms of protection, such as δ-opioid receptor regulation and mitophagy, reinforce the notion that mitochondrial adaptations (e.g. heat shock proteins, antioxidant enzymes and sirtuin-1/PGC-1 signalling) are central to the protective effects of exercise preconditioning.
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Affiliation(s)
- John M Lawler
- Redox Biology & Cell Signalling Laboratory, Department of Health and Kinesiology, Graduate Faculty of Nutrition & Food Science, Texas A&M University, College Station, TX, USA.
| | - Dinah A Rodriguez
- Redox Biology & Cell Signalling Laboratory, Department of Health and Kinesiology, Graduate Faculty of Nutrition & Food Science, Texas A&M University, College Station, TX, USA
| | - Jeffrey M Hord
- Redox Biology & Cell Signalling Laboratory, Department of Health and Kinesiology, Graduate Faculty of Nutrition & Food Science, Texas A&M University, College Station, TX, USA
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Protti A, Properzi P, Magnoni S, Santini A, Langer T, Guenzani S, Ferrero S, Bassani G, Stocchetti N, Gattinoni L. Skeletal muscle lactate overproduction during metformin intoxication: An animal study with reverse microdialysis. Toxicol Lett 2016; 255:43-6. [PMID: 27178268 DOI: 10.1016/j.toxlet.2016.05.010] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2016] [Revised: 05/02/2016] [Accepted: 05/09/2016] [Indexed: 12/24/2022]
Abstract
Lactic acidosis during metformin intoxication is classically mainly attributed to diminished lactate clearance through liver gluconeogenesis. Here we studied 6 healthy, sedated and mechanically ventilated pigs to clarify whether high dose of metformin also increases skeletal muscle lactate production. Each animal had two microdialysis catheters inserted in gluteus muscles, one per side. One catheter was infused with saline (control) while the other one was infused with metformin diluted in saline (1M), both at a rate of 0.3μl/min. Dialysate lactate concentration and lactate-to-pyruvate ratio, a marker of the balance between anaerobic glycolysis and aerobic (mitochondrial) metabolism, were measured every 3h, for 12h. Continuous infusion of metformin caused a progressive rise in dialysate lactate level (p=0.007) and lactate-to-pyruvate ratio (p<0.001) compared to that of saline, as for mitochondrial "poisoning". These findings suggest that skeletal muscle lactate overproduction contributes to the development of metformin-induced lactic acidosis.
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Affiliation(s)
- Alessandro Protti
- Dipartimento di Anestesia, Rianimazione ed Emergenza-Urgenza, Fondazione IRCCS Ca' Granda - Ospedale Maggiore Policlinico, Milan, Italy.
| | - Paolo Properzi
- Dipartimento di Anestesia, Rianimazione ed Emergenza-Urgenza, Fondazione IRCCS Ca' Granda - Ospedale Maggiore Policlinico, Milan, Italy
| | - Sandra Magnoni
- Dipartimento di Anestesia, Rianimazione ed Emergenza-Urgenza, Fondazione IRCCS Ca' Granda - Ospedale Maggiore Policlinico, Milan, Italy
| | - Alessandro Santini
- Dipartimento di Anestesia, Rianimazione ed Emergenza-Urgenza, Fondazione IRCCS Ca' Granda - Ospedale Maggiore Policlinico, Milan, Italy
| | - Thomas Langer
- Dipartimento di Anestesia, Rianimazione ed Emergenza-Urgenza, Fondazione IRCCS Ca' Granda - Ospedale Maggiore Policlinico, Milan, Italy
| | - Silvia Guenzani
- Dipartimento di Fisiopatologia Medico-Chirurgica e dei Trapianti, Università degli Studi, Milan, Italy
| | - Stefano Ferrero
- U.O.C. Anatomia Patologica, Fondazione IRCCS Ca' Granda - Ospedale Maggiore Policlinico, Milan, Italy; Dipartimento di Scienze Biomediche, Chirurgiche e Odontoiatriche, Università degli Studi, Milan, Italy
| | - Giulia Bassani
- Centro di Ricerche Chirurgiche Precliniche, Fondazione IRCCS Ca' Granda - Ospedale Maggiore Policlinico, Università degli Studi, Milan, Italy
| | - Nino Stocchetti
- Dipartimento di Anestesia, Rianimazione ed Emergenza-Urgenza, Fondazione IRCCS Ca' Granda - Ospedale Maggiore Policlinico, Milan, Italy; Dipartimento di Fisiopatologia Medico-Chirurgica e dei Trapianti, Università degli Studi, Milan, Italy
| | - Luciano Gattinoni
- Dipartimento di Anestesia, Rianimazione ed Emergenza-Urgenza, Fondazione IRCCS Ca' Granda - Ospedale Maggiore Policlinico, Milan, Italy; Dipartimento di Fisiopatologia Medico-Chirurgica e dei Trapianti, Università degli Studi, Milan, Italy
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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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56
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Umegaki H. Sarcopenia and frailty in older patients with diabetes mellitus. Geriatr Gerontol Int 2016; 16:293-9. [DOI: 10.1111/ggi.12688] [Citation(s) in RCA: 85] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/16/2015] [Indexed: 12/19/2022]
Affiliation(s)
- Hiroyuki Umegaki
- Department of Community Healthcare & Geriatrics; Nagoya University Graduate School of Medicine; Nagoya Aichi Japan
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57
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Prolonged metformin treatment leads to reduced transcription of Nrf2 and neurotrophic factors without cognitive impairment in older C57BL/6J mice. Behav Brain Res 2015; 301:1-9. [PMID: 26698400 DOI: 10.1016/j.bbr.2015.12.012] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2015] [Revised: 12/08/2015] [Accepted: 12/11/2015] [Indexed: 12/12/2022]
Abstract
Long-term use of anti-diabetic agents has become commonplace as rates of obesity, metabolic syndrome and diabetes continue to escalate. Metformin, a commonly used anti-diabetic drug, has been shown to have many beneficial effects outside of its therapeutic regulation of glucose metabolism and insulin sensitivity. Studies on metformin's effects on the central nervous system are limited and predominantly consist of in vitro studies and a few in vivo studies with short-term treatment in relatively young animals; some provide support for metformin as a neuroprotective agent while others show evidence that metformin may be deleterious to neuronal survival. In this study, we examined the effect of long-term metformin treatment on brain neurotrophins and cognition in aged male C57Bl/6 mice. Mice were fed control (C), high-fat (HF) or a high-fat diet supplemented with metformin (HFM) for 6 months. Metformin decreased body fat composition and attenuated declines in motor function induced by a HF diet. Performance in the Morris water maze test of hippocampal based memory function, showed that metformin prevented impairment of spatial reference memory associated with the HF diet. Quantitative RT-PCR on brain homogenates revealed decreased transcription of BDNF, NGF and NTF3; however protein levels were not altered. Metformin treatment also decreased expression of the antioxidant pathway regulator, Nrf2. The decrease in transcription of neurotrophic factors and Nrf2 with chronic metformin intake, cautions of the possibility that extended metformin use may alter brain biochemistry in a manner that creates a vulnerable brain environment and warrants further investigation.
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58
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Victor VM, Rovira-Llopis S, Bañuls C, Diaz-Morales N, Castelló R, Falcón R, Gómez M, Rocha M, Hernández-Mijares A. Effects of metformin on mitochondrial function of leukocytes from polycystic ovary syndrome patients with insulin resistance. Eur J Endocrinol 2015; 173:683-91. [PMID: 26320144 DOI: 10.1530/eje-15-0572] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/08/2015] [Accepted: 08/27/2015] [Indexed: 12/22/2022]
Abstract
OBJECTIVE Oxidative stress and mitochondrial dysfunction are implicated in polycystic ovary syndrome (PCOS). The present study assesses the effect of metformin treatment on mitochondrial function in polymorphonuclear cells from PCOS subjects. Additionally, we evaluate endocrine parameters and levels of interleukin 6 (IL6) and tumour necrosis factor alpha (TNFα). DESIGN AND METHODS Our study population was comprised of 35 women of reproductive age diagnosed with PCOS and treated with metformin for 12 weeks, and their corresponding controls (n=41), adjusted by age and BMI. We evaluated the alteration of endocrinological and anthropometrical parameters and androgen levels. Mitochondrial O2 consumption (using a Clark-type O2 electrode), membrane potential, mitochondrial mass, and levels of reactive oxygen species (ROS) and glutathione (GSH) (by means of fluorescence microscopy) were assessed in poymorphonuclear cells. H2O2 was evaluated with the Amplex Red(R) H2O2/Peroxidase Assay kit. IL6 and TNFα were measured using the Luminex 200 flow analyser system. RESULTS Metformin had beneficial effects on patients by increasing mitochondrial O2 consumption, membrane potential, mitochondrial mass and glutathione levels, and by decreasing levels of reactive oxygen species and H2O2. In addition, metformin reduced glucose, follicle-stimulating hormone, IL6 and TNFα levels and increased dehydroepiandrosterone sulfate levels. HOMA-IR and mitochondrial function biomarkers positively correlated with ROS production (r=0.486, P=0.025), GSH content (r=0.710, P=0.049) and H2O2 (r=0.837, P=0.010), and negatively correlated with membrane potential (r=-0.829, P=0.011) at baseline. These differences disappeared after metformin treatment. CONCLUSIONS Our results demonstrate the beneficial effects of metformin treatment on mitochondrial function in leukocytes of PCOS patients.
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Affiliation(s)
- Victor M Victor
- Service of EndocrinologyUniversity Hospital Doctor Peset, Foundation for the Promotion of Health and Biomedical Research in the Valencian Region (FISABIO), Avenida Gaspar Aguilar 90, 46017 Valencia, SpainInstitute of Health Research INCLIVAUniversity of Valencia, Valencia, SpainCIBERehd - Department of Pharmacology and PhysiologyUniversity of Valencia, Valencia, SpainDepartment of MedicineUniversity of Valencia, Valencia, Spain Service of EndocrinologyUniversity Hospital Doctor Peset, Foundation for the Promotion of Health and Biomedical Research in the Valencian Region (FISABIO), Avenida Gaspar Aguilar 90, 46017 Valencia, SpainInstitute of Health Research INCLIVAUniversity of Valencia, Valencia, SpainCIBERehd - Department of Pharmacology and PhysiologyUniversity of Valencia, Valencia, SpainDepartment of MedicineUniversity of Valencia, Valencia, Spain Service of EndocrinologyUniversity Hospital Doctor Peset, Foundation for the Promotion of Health and Biomedical Research in the Valencian Region (FISABIO), Avenida Gaspar Aguilar 90, 46017 Valencia, SpainInstitute of Health Research INCLIVAUniversity of Valencia, Valencia, SpainCIBERehd - Department of Pharmacology and PhysiologyUniversity of Valencia, Valencia, SpainDepartment of MedicineUniversity of Valencia, Valencia, Spain
| | - Susana Rovira-Llopis
- Service of EndocrinologyUniversity Hospital Doctor Peset, Foundation for the Promotion of Health and Biomedical Research in the Valencian Region (FISABIO), Avenida Gaspar Aguilar 90, 46017 Valencia, SpainInstitute of Health Research INCLIVAUniversity of Valencia, Valencia, SpainCIBERehd - Department of Pharmacology and PhysiologyUniversity of Valencia, Valencia, SpainDepartment of MedicineUniversity of Valencia, Valencia, Spain Service of EndocrinologyUniversity Hospital Doctor Peset, Foundation for the Promotion of Health and Biomedical Research in the Valencian Region (FISABIO), Avenida Gaspar Aguilar 90, 46017 Valencia, SpainInstitute of Health Research INCLIVAUniversity of Valencia, Valencia, SpainCIBERehd - Department of Pharmacology and PhysiologyUniversity of Valencia, Valencia, SpainDepartment of MedicineUniversity of Valencia, Valencia, Spain
| | - Celia Bañuls
- Service of EndocrinologyUniversity Hospital Doctor Peset, Foundation for the Promotion of Health and Biomedical Research in the Valencian Region (FISABIO), Avenida Gaspar Aguilar 90, 46017 Valencia, SpainInstitute of Health Research INCLIVAUniversity of Valencia, Valencia, SpainCIBERehd - Department of Pharmacology and PhysiologyUniversity of Valencia, Valencia, SpainDepartment of MedicineUniversity of Valencia, Valencia, Spain Service of EndocrinologyUniversity Hospital Doctor Peset, Foundation for the Promotion of Health and Biomedical Research in the Valencian Region (FISABIO), Avenida Gaspar Aguilar 90, 46017 Valencia, SpainInstitute of Health Research INCLIVAUniversity of Valencia, Valencia, SpainCIBERehd - Department of Pharmacology and PhysiologyUniversity of Valencia, Valencia, SpainDepartment of MedicineUniversity of Valencia, Valencia, Spain
| | - Noelia Diaz-Morales
- Service of EndocrinologyUniversity Hospital Doctor Peset, Foundation for the Promotion of Health and Biomedical Research in the Valencian Region (FISABIO), Avenida Gaspar Aguilar 90, 46017 Valencia, SpainInstitute of Health Research INCLIVAUniversity of Valencia, Valencia, SpainCIBERehd - Department of Pharmacology and PhysiologyUniversity of Valencia, Valencia, SpainDepartment of MedicineUniversity of Valencia, Valencia, Spain
| | - Raquel Castelló
- Service of EndocrinologyUniversity Hospital Doctor Peset, Foundation for the Promotion of Health and Biomedical Research in the Valencian Region (FISABIO), Avenida Gaspar Aguilar 90, 46017 Valencia, SpainInstitute of Health Research INCLIVAUniversity of Valencia, Valencia, SpainCIBERehd - Department of Pharmacology and PhysiologyUniversity of Valencia, Valencia, SpainDepartment of MedicineUniversity of Valencia, Valencia, Spain
| | - Rosa Falcón
- Service of EndocrinologyUniversity Hospital Doctor Peset, Foundation for the Promotion of Health and Biomedical Research in the Valencian Region (FISABIO), Avenida Gaspar Aguilar 90, 46017 Valencia, SpainInstitute of Health Research INCLIVAUniversity of Valencia, Valencia, SpainCIBERehd - Department of Pharmacology and PhysiologyUniversity of Valencia, Valencia, SpainDepartment of MedicineUniversity of Valencia, Valencia, Spain
| | - Marcelino Gómez
- Service of EndocrinologyUniversity Hospital Doctor Peset, Foundation for the Promotion of Health and Biomedical Research in the Valencian Region (FISABIO), Avenida Gaspar Aguilar 90, 46017 Valencia, SpainInstitute of Health Research INCLIVAUniversity of Valencia, Valencia, SpainCIBERehd - Department of Pharmacology and PhysiologyUniversity of Valencia, Valencia, SpainDepartment of MedicineUniversity of Valencia, Valencia, Spain
| | - Milagros Rocha
- Service of EndocrinologyUniversity Hospital Doctor Peset, Foundation for the Promotion of Health and Biomedical Research in the Valencian Region (FISABIO), Avenida Gaspar Aguilar 90, 46017 Valencia, SpainInstitute of Health Research INCLIVAUniversity of Valencia, Valencia, SpainCIBERehd - Department of Pharmacology and PhysiologyUniversity of Valencia, Valencia, SpainDepartment of MedicineUniversity of Valencia, Valencia, Spain Service of EndocrinologyUniversity Hospital Doctor Peset, Foundation for the Promotion of Health and Biomedical Research in the Valencian Region (FISABIO), Avenida Gaspar Aguilar 90, 46017 Valencia, SpainInstitute of Health Research INCLIVAUniversity of Valencia, Valencia, SpainCIBERehd - Department of Pharmacology and PhysiologyUniversity of Valencia, Valencia, SpainDepartment of MedicineUniversity of Valencia, Valencia, Spain Service of EndocrinologyUniversity Hospital Doctor Peset, Foundation for the Promotion of Health and Biomedical Research in the Valencian Region (FISABIO), Avenida Gaspar Aguilar 90, 46017 Valencia, SpainInstitute of Health Research INCLIVAUniversity of Valencia, Valencia, SpainCIBERehd - Department of Pharmacology and PhysiologyUniversity of Valencia, Valencia, SpainDepartment of MedicineUniversity of Valencia, Valencia, Spain
| | - Antonio Hernández-Mijares
- Service of EndocrinologyUniversity Hospital Doctor Peset, Foundation for the Promotion of Health and Biomedical Research in the Valencian Region (FISABIO), Avenida Gaspar Aguilar 90, 46017 Valencia, SpainInstitute of Health Research INCLIVAUniversity of Valencia, Valencia, SpainCIBERehd - Department of Pharmacology and PhysiologyUniversity of Valencia, Valencia, SpainDepartment of MedicineUniversity of Valencia, Valencia, Spain Service of EndocrinologyUniversity Hospital Doctor Peset, Foundation for the Promotion of Health and Biomedical Research in the Valencian Region (FISABIO), Avenida Gaspar Aguilar 90, 46017 Valencia, SpainInstitute of Health Research INCLIVAUniversity of Valencia, Valencia, SpainCIBERehd - Department of Pharmacology and PhysiologyUniversity of Valencia, Valencia, SpainDepartment of MedicineUniversity of Valencia, Valencia, Spain Service of EndocrinologyUniversity Hospital Doctor Peset, Foundation for the Promotion of Health and Biomedical Research in the Valencian Region (FISABIO), Avenida Gaspar Aguilar 90, 46017 Valencia, SpainInstitute of Health Research INCLIVAUniversity of Valencia, Valencia, SpainCIBERehd - Department of Pharmacology and PhysiologyUniversity of Valencia, Valencia, SpainDepartment of MedicineUniversity of Valencia, Valencia, Spain
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Kajbaf F, De Broe ME, Lalau JD. Therapeutic Concentrations of Metformin: A Systematic Review. Clin Pharmacokinet 2015; 55:439-59. [DOI: 10.1007/s40262-015-0323-x] [Citation(s) in RCA: 104] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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Hafizi Abu Bakar M, Kian Kai C, Wan Hassan WN, Sarmidi MR, Yaakob H, Zaman Huri H. Mitochondrial dysfunction as a central event for mechanisms underlying insulin resistance: the roles of long chain fatty acids. Diabetes Metab Res Rev 2015; 31:453-75. [PMID: 25139820 DOI: 10.1002/dmrr.2601] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/16/2013] [Revised: 04/19/2014] [Accepted: 07/23/2014] [Indexed: 12/25/2022]
Abstract
Insulin resistance is characterized by hyperglycaemia, dyslipidaemia and oxidative stress prior to the development of type 2 diabetes mellitus. To date, a number of mechanisms have been proposed to link these syndromes together, but it remains unclear what the unifying condition that triggered these events in the progression of this metabolic disease. There have been a steady accumulation of data in numerous experimental studies showing the strong correlations between mitochondrial dysfunction, oxidative stress and insulin resistance. In addition, a growing number of studies suggest that the raised plasma free fatty acid level induced insulin resistance with the significant alteration of oxidative metabolism in various target tissues such as skeletal muscle, liver and adipose tissue. In this review, we herein propose the idea of long chain fatty acid-induced mitochondrial dysfunctions as one of the key events in the pathophysiological development of insulin resistance and type 2 diabetes. The accumulation of reactive oxygen species, lipotoxicity, inflammation-induced endoplasmic reticulum stress and alterations of mitochondrial gene subset expressions are the most detrimental that lead to the developments of aberrant intracellular insulin signalling activity in a number of peripheral tissues, thereby leading to insulin resistance and type 2 diabetes.
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Affiliation(s)
- Mohamad Hafizi Abu Bakar
- Department of Bioprocess Engineering, Faculty of Chemical Engineering, Universiti Teknologi Malaysia, Skudai, Johor, Malaysia
| | - Cheng Kian Kai
- Department of Bioprocess Engineering, Faculty of Chemical Engineering, Universiti Teknologi Malaysia, Skudai, Johor, Malaysia
| | - Wan Najihah Wan Hassan
- Department of Bioprocess Engineering, Faculty of Chemical Engineering, Universiti Teknologi Malaysia, Skudai, Johor, Malaysia
| | - Mohamad Roji Sarmidi
- Institute of Bioproduct Development, Universiti Teknologi Malaysia, Skudai, Johor, Malaysia
| | - Harisun Yaakob
- Institute of Bioproduct Development, Universiti Teknologi Malaysia, Skudai, Johor, Malaysia
| | - Hasniza Zaman Huri
- Department of Pharmacy, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
- Clinical Investigation Centre, 13th Floor Main Tower, University Malaya Medical Centre, Lembah Pantai, Kuala Lumpur, Malaysia
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61
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Zheng J, Woo SL, Hu X, Botchlett R, Chen L, Huo Y, Wu C. Metformin and metabolic diseases: a focus on hepatic aspects. Front Med 2015; 9:173-86. [PMID: 25676019 PMCID: PMC4567274 DOI: 10.1007/s11684-015-0384-0] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2014] [Accepted: 10/24/2014] [Indexed: 12/25/2022]
Abstract
Metformin has been widely used as a first-line anti-diabetic medicine for the treatment of type 2 diabetes (T2D). As a drug that primarily targets the liver, metformin suppresses hepatic glucose production (HGP), serving as the main mechanism by which metformin improves hyperglycemia of T2D. Biochemically, metformin suppresses gluconeogenesis and stimulates glycolysis. Metformin also inhibits glycogenolysis, which is a pathway that critically contributes to elevated HGP. While generating beneficial effects on hyperglycemia, metformin also improves insulin resistance and corrects dyslipidemia in patients with T2D. These beneficial effects of metformin implicate a role for metformin in managing non-alcoholic fatty liver disease. As supported by the results from both human and animal studies, metformin improves hepatic steatosis and suppresses liver inflammation. Mechanistically, the beneficial effects of metformin on hepatic aspects are mediated through both adenosine monophosphate-activated protein kinase (AMPK)-dependent and AMPK-independent pathways. In addition, metformin is generally safe and may also benefit patients with other chronic liver diseases.
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Affiliation(s)
- Juan Zheng
- Department of Nutrition and Food Science, Texas A&M University, College Station, TX 77843, USA
- Department of Endocrinology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Shih-Lung Woo
- Department of Nutrition and Food Science, Texas A&M University, College Station, TX 77843, USA
| | - Xiang Hu
- Department of Nutrition and Food Science, Texas A&M University, College Station, TX 77843, USA
- Department of Endocrinology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Rachel Botchlett
- Department of Nutrition and Food Science, Texas A&M University, College Station, TX 77843, USA
| | - Lulu Chen
- Department of Endocrinology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Yuqing Huo
- Drug Discovery Center, Key Laboratory of Chemical Genomics, Peking University Shenzhen Graduate School, Shenzhen 518055, China
| | - Chaodong Wu
- Department of Nutrition and Food Science, Texas A&M University, College Station, TX 77843, USA
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Huang Y, Yu Y, Gao J, Li R, Zhang C, Zhao H, Zhao Y, Qiao J. Impaired oocyte quality induced by dehydroepiandrosterone is partially rescued by metformin treatment. PLoS One 2015; 10:e0122370. [PMID: 25811995 PMCID: PMC4374838 DOI: 10.1371/journal.pone.0122370] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2014] [Accepted: 02/15/2015] [Indexed: 12/25/2022] Open
Abstract
The present study evaluated the influence of hyperandrogenism on oocyte quality using a murine PCOS model induced by dehydroepiandrosterone (DHEA) and further explored the effect of metformin treatment. Female BALB/c mice were treated with a vehicle control or DHEA (6 mg /100 g body weight) or DHEA plus metformin (50 mg /100 g body weight) for 20 consecutive days. DHEA-induced mice resembled some characters of human PCOS, such as irregular sexual cycles and polycystic ovaries. After the model validation was completed, metaphase II (MII) oocytes were retrieved and subsequent analyses of oocyte quality were performed. DHEA-treated mice yielded fewer MII oocytes, which displayed decreased mtDNA copy number, ATP content, inner mitochondrial membrane potential, excessive oxidative stress and impaired embryo development competence compared with those in control mice. Metformin treatment partially attenuated those damages, as evidenced by the increased fertilization and blastocyst rate, ATP content, GSH concentration and GSH/GSSG ratio, and decreased reactive oxygen species levels. No significant difference in normal spindle assembly was observed among the three groups. During in vitro maturation (IVM), the periods of germinal vesicle breakdown (GVBD) and the first polar body (PB1) extrusion were extended and the maturation rate of GVBD oocytes was decreased in DHEA mice compared with controls. Metformin treatment decreased the time elapsed of GVBD while had no effect on PB1 extrusion. These results indicated that excessive androgen is detrimental to oocyte quality while metformin treatment is, directly or indirectly, beneficial for oocyte quality improvement.
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Affiliation(s)
- Ying Huang
- Reproductive Medical Center, Department of Obstetrics and Gynecology, Peking University Third Hospital, Beijing, China
- Key Laboratory of Assisted Reproduction, Ministry of Education, Beijing, China
- Beijing Key Laboratory of Reproductive Endocrinology and Assisted Reproductive Technology, Beijing, China
| | - Yang Yu
- Reproductive Medical Center, Department of Obstetrics and Gynecology, Peking University Third Hospital, Beijing, China
- Key Laboratory of Assisted Reproduction, Ministry of Education, Beijing, China
| | - Jiangman Gao
- Reproductive Medical Center, Department of Obstetrics and Gynecology, Peking University Third Hospital, Beijing, China
- Beijing Key Laboratory of Reproductive Endocrinology and Assisted Reproductive Technology, Beijing, China
| | - Rong Li
- Reproductive Medical Center, Department of Obstetrics and Gynecology, Peking University Third Hospital, Beijing, China
- Beijing Key Laboratory of Reproductive Endocrinology and Assisted Reproductive Technology, Beijing, China
| | - Chunmei Zhang
- Reproductive Medical Center, Department of Obstetrics and Gynecology, Peking University Third Hospital, Beijing, China
- Key Laboratory of Assisted Reproduction, Ministry of Education, Beijing, China
| | - Hongcui Zhao
- Reproductive Medical Center, Department of Obstetrics and Gynecology, Peking University Third Hospital, Beijing, China
- Beijing Key Laboratory of Reproductive Endocrinology and Assisted Reproductive Technology, Beijing, China
| | - Yue Zhao
- Reproductive Medical Center, Department of Obstetrics and Gynecology, Peking University Third Hospital, Beijing, China
- Key Laboratory of Assisted Reproduction, Ministry of Education, Beijing, China
- * E-mail: (JQ); (YZ)
| | - Jie Qiao
- Reproductive Medical Center, Department of Obstetrics and Gynecology, Peking University Third Hospital, Beijing, China
- Key Laboratory of Assisted Reproduction, Ministry of Education, Beijing, China
- Beijing Key Laboratory of Reproductive Endocrinology and Assisted Reproductive Technology, Beijing, China
- * E-mail: (JQ); (YZ)
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Kinaan M, Ding H, Triggle CR. Metformin: An Old Drug for the Treatment of Diabetes but a New Drug for the Protection of the Endothelium. Med Princ Pract 2015; 24:401-15. [PMID: 26021280 PMCID: PMC5588255 DOI: 10.1159/000381643] [Citation(s) in RCA: 112] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/03/2014] [Accepted: 03/15/2015] [Indexed: 12/25/2022] Open
Abstract
The anti-diabetic and oral hypoglycaemic agent metformin, first used clinically in 1958, is today the first choice or 'gold standard' drug for the treatment of type 2 diabetes and polycystic ovary disease. Of particular importance for the treatment of diabetes, metformin affords protection against diabetes-induced vascular disease. In addition, retrospective analyses suggest that treatment with metformin provides therapeutic benefits to patients with several forms of cancer. Despite almost 60 years of clinical use, the precise cellular mode(s) of action of metformin remains controversial. A direct or indirect role of adenosine monophosphate (AMP)-activated protein kinase (AMPK), the fuel gauge of the cell, has been inferred in many studies, with evidence that activation of AMPK may result from a mild inhibitory effect of metformin on mitochondrial complex 1, which in turn would raise AMP and activate AMPK. Discrepancies, however, between the concentrations of metformin used in in vitro studies versus therapeutic levels suggest that caution should be applied before extending inferences derived from cell-based studies to therapeutic benefits seen in patients. Conceivably, the effects, or some of them, may be at least partially independent of AMPK and/or mitochondrial respiration and reflect a direct effect of either metformin or a minor and, as yet, unidentified putative metabolite of metformin on a target protein(s)/signalling cascade. In this review, we critically evaluate the data from studies that have investigated the pharmacokinetic properties and the cellular and clinical basis for the oral hypoglycaemic, insulin-sensitising and vascular protective effects of metformin.
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Affiliation(s)
| | | | - Chris R. Triggle
- *Chris R. Triggle, Weill Cornell Medical College in Qatar, PO Box 24144, Education City, Doha (Qatar), E-Mail
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Piel S, Ehinger JK, Elmér E, Hansson MJ. Metformin induces lactate production in peripheral blood mononuclear cells and platelets through specific mitochondrial complex I inhibition. Acta Physiol (Oxf) 2015; 213:171-80. [PMID: 24801139 DOI: 10.1111/apha.12311] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2013] [Revised: 11/21/2013] [Accepted: 04/26/2014] [Indexed: 12/25/2022]
Abstract
AIM Metformin is a widely used antidiabetic drug associated with the rare side effect of lactic acidosis which has been proposed to be linked to drug-induced mitochondrial dysfunction. Using respirometry, the aim of this study was to evaluate mitochondrial toxicity of metformin to human blood cells in relation to that of phenformin, a biguanide analogue withdrawn in most countries due to a high incidence of lactic acidosis. METHODS Peripheral blood mononuclear cells and platelets were isolated from healthy volunteers, and integrated mitochondrial function was studied in permeabilized and intact cells using high-resolution respirometry. A wide concentration range of metformin (0.1-100 mm) and phenformin (25-500 μm) was investigated for dose- and time-dependent effects on respiratory capacities, lactate production and pH. RESULTS Metformin induced respiratory inhibition at complex I in peripheral blood mononuclear cells and platelets (IC50 0.45 mm and 1.2 mm respectively). Phenformin was about 20-fold more potent in complex I inhibition of platelets than metformin. Metformin further demonstrated a dose- and time-dependent respiratory inhibition and augmented lactate release at a concentration of 1 mm and higher. CONCLUSION Respirometry of human peripheral blood cells readily detected respiratory inhibition by metformin and phenformin specific to complex I, providing a suitable model for probing drug toxicity. Lactate production was increased at concentrations relevant for clinical metformin intoxication, indicating mitochondrial inhibition as a direct causative pathophysiological mechanism. Relative to clinical dosing, phenformin displayed a more potent respiratory inhibition than metformin, possibly explaining the higher incidence of lactic acidosis in phenformin-treated patients.
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Affiliation(s)
- S. Piel
- Mitochondrial Medicine; Department of Clinical Sciences; Lund University; Lund Sweden
- NeuroVive Pharmaceutical AB; Lund Sweden
| | - J. K. Ehinger
- Mitochondrial Medicine; Department of Clinical Sciences; Lund University; Lund Sweden
- NeuroVive Pharmaceutical AB; Lund Sweden
- Department of Otorhinolaryngology; Head and Neck Surgery; Skåne University Hospital; Lund Sweden
| | - E. Elmér
- Mitochondrial Medicine; Department of Clinical Sciences; Lund University; Lund Sweden
- NeuroVive Pharmaceutical AB; Lund Sweden
- Department of Clinical Neurophysiology; Skåne University Hospital & Lund University; Lund Sweden
| | - M. J. Hansson
- Mitochondrial Medicine; Department of Clinical Sciences; Lund University; Lund Sweden
- NeuroVive Pharmaceutical AB; Lund Sweden
- Department of Clinical Physiology; Skåne University Hospital & Lund University; Lund Sweden
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65
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Wessels B, Ciapaite J, van den Broek NMA, Nicolay K, Prompers JJ. Metformin impairs mitochondrial function in skeletal muscle of both lean and diabetic rats in a dose-dependent manner. PLoS One 2014; 9:e100525. [PMID: 24950069 PMCID: PMC4065055 DOI: 10.1371/journal.pone.0100525] [Citation(s) in RCA: 75] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2014] [Accepted: 05/28/2014] [Indexed: 12/02/2022] Open
Abstract
Metformin is a widely prescribed drug for the treatment of type 2 diabetes. Previous studies have demonstrated in vitro that metformin specifically inhibits Complex I of the mitochondrial respiratory chain. This seems contraindicative since muscle mitochondrial dysfunction has been linked to the pathogenesis of type 2 diabetes. However, its significance for in vivo skeletal muscle mitochondrial function has yet to be elucidated. The aim of this study was to assess the effects of metformin on in vivo and ex vivo skeletal muscle mitochondrial function in a rat model of diabetes. Healthy (fa/+) and diabetic (fa/fa) Zucker diabetic fatty rats were treated by oral gavage with metformin dissolved in water (30, 100 or 300 mg/kg bodyweight/day) or water as a control for 2 weeks. After 2 weeks of treatment, muscle oxidative capacity was assessed in vivo using 31P magnetic resonance spectroscopy and ex vivo by measuring oxygen consumption in isolated mitochondria using high-resolution respirometry. Two weeks of treatment with metformin impaired in vivo muscle oxidative capacity in a dose-dependent manner, both in healthy and diabetic rats. Whereas a dosage of 30 mg/kg/day had no significant effect, in vivo oxidative capacity was 21% and 48% lower after metformin treatment at 100 and 300 mg/kg/day, respectively, independent of genotype. High-resolution respirometry measurements demonstrated a similar dose-dependent effect of metformin on ex vivo mitochondrial function. In conclusion, metformin compromises in vivo and ex vivo muscle oxidative capacity in Zucker diabetic fatty rats in a dose-dependent manner.
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Affiliation(s)
- Bart Wessels
- Biomedical NMR, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands
| | - Jolita Ciapaite
- Department of Pediatrics, Centre for Liver, Digestive and Metabolic Diseases, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Nicole M. A. van den Broek
- Biomedical NMR, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands
| | - Klaas Nicolay
- Biomedical NMR, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands
| | - Jeanine J. Prompers
- Biomedical NMR, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands
- * E-mail:
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Qin ZY, Zhang M, Dai YM, Wang YM, Zhu GZ, Zhao YP, Ji CB, Qiu J, Cao XG, Guo XR. Metformin prevents LYRM1-induced insulin resistance in 3T3-L1 adipocytes via a mitochondrial-dependent mechanism. Exp Biol Med (Maywood) 2014; 239:1567-74. [PMID: 24903160 DOI: 10.1177/1535370214537746] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
We previously proposed that LYR motif containing 1 (LYRM1)-induced mitochondrial reactive oxygen species (ROS) production contributes to obesity-related insulin resistance. Metformin inhibits ROS production and promotes mitochondrial biogenesis in specific tissues. We assessed the effects of metformin on insulin resistance in LYRM1-over-expressing 3T3-L1 adipocytes. Metformin enhanced basal and insulin-stimulated glucose uptake and GLUT4 translocation, reduced IRS-1 and Akt phosphorylation and ROS levels, and affected the expression of regulators of mitochondrial biogenesis in LYRM1-over-expressing adipocytes. Metformin may ameliorate LYRM1-induced insulin resistance and mitochondrial dysfunction in part via a direct antioxidant effect and in part by activating the adenosine monophosphate-activated protein kinase (AMPK)-PGC1/NRFs pathway.
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Affiliation(s)
- Zhen-Ying Qin
- The First Affiliated Hospital with Nanjing Medical University, Nanjing 210036, China
| | - Min Zhang
- State Key Laboratory of Reproductive Medicine, Nanjing Maternal and Child Health Hospital of Nanjing Medical University, Nanjing 210004, China
| | - Yong-mei Dai
- State Key Laboratory of Reproductive Medicine, Nanjing Maternal and Child Health Hospital of Nanjing Medical University, Nanjing 210004, China
| | - Yu-Mei Wang
- Department of Child Health, Huai'an Maternity and Child Health Hospital, Huai'an 223002, China
| | - Guan-zhong Zhu
- Institute of Pediatrics, Nanjing Medical University, Nanjing 210029, China
| | - Ya-Ping Zhao
- The 82nd Hospital of the People's Liberation Army, Huai'an 223001, China
| | - Chen-Bo Ji
- State Key Laboratory of Reproductive Medicine, Nanjing Maternal and Child Health Hospital of Nanjing Medical University, Nanjing 210004, China
| | - Jie Qiu
- State Key Laboratory of Reproductive Medicine, Nanjing Maternal and Child Health Hospital of Nanjing Medical University, Nanjing 210004, China
| | - Xin-Guo Cao
- State Key Laboratory of Reproductive Medicine, Nanjing Maternal and Child Health Hospital of Nanjing Medical University, Nanjing 210004, China
| | - Xi-Rong Guo
- Institute of Pediatrics, Nanjing Medical University, Nanjing 210029, China
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67
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Metformin ameliorates ovariectomy-induced vascular dysfunction in non-diabetic Wistar rats. Clin Sci (Lond) 2014; 127:265-75. [DOI: 10.1042/cs20130553] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The pathophysiological changes observed in the mesenteric beds of ovariectomized rats were ameliorated by metformin. If this translates to humans, metformin could have additional benefits for post-menopausal women treated with this drug for glycaemic control.
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68
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Martin SD, Morrison S, Konstantopoulos N, McGee SL. Mitochondrial dysfunction has divergent, cell type-dependent effects on insulin action. Mol Metab 2014; 3:408-18. [PMID: 24944900 PMCID: PMC4060359 DOI: 10.1016/j.molmet.2014.02.001] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/28/2014] [Revised: 02/14/2014] [Accepted: 02/18/2014] [Indexed: 12/25/2022] Open
Abstract
The contribution of mitochondrial dysfunction to insulin resistance is a contentious issue in metabolic research. Recent evidence implicates mitochondrial dysfunction as contributing to multiple forms of insulin resistance. However, some models of mitochondrial dysfunction fail to induce insulin resistance, suggesting greater complexity describes mitochondrial regulation of insulin action. We report that mitochondrial dysfunction is not necessary for cellular models of insulin resistance. However, impairment of mitochondrial function is sufficient for insulin resistance in a cell type-dependent manner, with impaired mitochondrial function inducing insulin resistance in adipocytes, but having no effect, or insulin sensitising effects in hepatocytes. The mechanism of mitochondrial impairment was important in determining the impact on insulin action, but was independent of mitochondrial ROS production. These data can account for opposing findings on this issue and highlight the complexity of mitochondrial regulation of cell type-specific insulin action, which is not described by current reductionist paradigms.
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Key Words
- AMPK, AMP-activated protein kinase
- AS160, Akt substrate of 160 kDa
- Adipocyte
- BSA, bovine serum albumin
- ECAR, extracellular acidification rate
- FoxO1, forkhead box protein O1
- G.O., glucose oxidase
- GLUT4, facilitative glucose transporter isoform 4
- GP, glucose production
- HI-FBS, heat-inactivated foetal bovine serum
- Hepatocyte
- IRS1, insulin receptor substrate 1
- Insulin action
- LDH, lactate dehydrogenase
- MMP, mitochondrial membrane potential
- Mitochondria
- MnTBAP, manganese (III) tetrakis (4-benzoic acid) porphyrin chloride
- PI3K, phosphatidylinositol 3-kinase
- ROS, reactive oxygen species
- Reactive oxygen species
- SOD, superoxide dismutase
- T2D, type 2 diabetes
- TNFα, tumour necrosis factor alpha
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Affiliation(s)
- Sheree D Martin
- Metabolic Remodelling Laboratory, Metabolic Research Unit, School of Medicine, Deakin University, Geelong, Australia
| | - Shona Morrison
- Metabolic Remodelling Laboratory, Metabolic Research Unit, School of Medicine, Deakin University, Geelong, Australia
| | - Nicky Konstantopoulos
- Metabolic Remodelling Laboratory, Metabolic Research Unit, School of Medicine, Deakin University, Geelong, Australia
| | - Sean L McGee
- Metabolic Remodelling Laboratory, Metabolic Research Unit, School of Medicine, Deakin University, Geelong, Australia ; Cell Signalling and Metabolism Division, Baker IDI Heart and Diabetes Institute, Melbourne, Australia
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69
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Martin-Montalvo A, Mercken EM, Mitchell SJ, Palacios HH, Mote PL, Scheibye-Knudsen M, Gomes AP, Ward TM, Minor RK, Blouin MJ, Schwab M, Pollak M, Zhang Y, Yu Y, Becker KG, Bohr VA, Ingram DK, Sinclair DA, Wolf NS, Spindler SR, Bernier M, de Cabo R. Metformin improves healthspan and lifespan in mice. Nat Commun 2014; 4:2192. [PMID: 23900241 PMCID: PMC3736576 DOI: 10.1038/ncomms3192] [Citation(s) in RCA: 969] [Impact Index Per Article: 96.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2012] [Accepted: 06/26/2013] [Indexed: 12/15/2022] Open
Abstract
Metformin is a drug commonly prescribed to treat patients with type 2 diabetes. Here we show that long-term treatment with metformin (0.1% w/w in diet) starting at middle age extends healthspan and lifespan in male mice, while a higher dose (1% w/w) was toxic. Treatment with metformin mimics some of the benefits of calorie restriction, such as improved physical performance, increased insulin sensitivity, and reduced low-density lipoprotein and cholesterol levels without a decrease in caloric intake. At a molecular level, metformin increases AMP-activated protein kinase activity and increases antioxidant protection, resulting in reductions in both oxidative damage accumulation and chronic inflammation. Our results indicate that these actions may contribute to the beneficial effects of metformin on healthspan and lifespan. These findings are in agreement with current epidemiological data and raise the possibility of metformin-based interventions to promote healthy aging.
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Affiliation(s)
- Alejandro Martin-Montalvo
- Translational Gerontology Branch, National Institute on Aging, National Institutes of Health, 251 Bayview Boulevard, Baltimore, Maryland 21224, USA
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Gilliam LAA, Fisher-Wellman KH, Lin CT, Maples JM, Cathey BL, Neufer PD. The anticancer agent doxorubicin disrupts mitochondrial energy metabolism and redox balance in skeletal muscle. Free Radic Biol Med 2013; 65:988-996. [PMID: 24017970 PMCID: PMC3859698 DOI: 10.1016/j.freeradbiomed.2013.08.191] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/26/2013] [Revised: 08/29/2013] [Accepted: 08/30/2013] [Indexed: 12/25/2022]
Abstract
The combined loss of muscle strength and constant fatigue are disabling symptoms for cancer patients undergoing chemotherapy. Doxorubicin, a standard chemotherapy drug used in the clinic, causes skeletal muscle dysfunction and premature fatigue along with an increase in reactive oxygen species (ROS). As mitochondria represent a primary source of oxidant generation in muscle, we hypothesized that doxorubicin could negatively affect mitochondria by inhibiting respiratory capacity, leading to an increase in H2O2-emitting potential. Here we demonstrate a biphasic response of skeletal muscle mitochondria to a single doxorubicin injection (20mg/kg). Initially at 2h doxorubicin inhibits both complex I- and II-supported respiration and increases H2O2 emission, both of which are partially restored after 24h. The relationship between oxygen consumption and membrane potential (ΔΨ) is shifted to the right at 24h, indicating elevated reducing pressure within the electron transport system (ETS). Respiratory capacity is further decreased at a later time point (72 h) along with H2O2-emitting potential and an increased sensitivity to mitochondrial permeability transition pore (mPTP) opening. These novel findings suggest a role for skeletal muscle mitochondria as a potential underlying cause of doxorubicin-induced muscle dysfunction.
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Affiliation(s)
- Laura A A Gilliam
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC 27858, USA; Department of Physiology, East Carolina University, Greenville, NC 27858, USA.
| | - Kelsey H Fisher-Wellman
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC 27858, USA; Department of Kinesiology, East Carolina University, Greenville, NC 27858, USA
| | - Chien-Te Lin
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC 27858, USA; Department of Physiology, East Carolina University, Greenville, NC 27858, USA
| | - Jill M Maples
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC 27858, USA; Department of Kinesiology, East Carolina University, Greenville, NC 27858, USA
| | - Brook L Cathey
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC 27858, USA; Department of Physiology, East Carolina University, Greenville, NC 27858, USA
| | - P Darrell Neufer
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC 27858, USA; Department of Physiology, East Carolina University, Greenville, NC 27858, USA; Department of Kinesiology, East Carolina University, Greenville, NC 27858, USA
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Abstract
A growing body of research is investigating the potential contribution of mitochondrial function to the etiology of type 2 diabetes. Numerous in vitro, in situ, and in vivo methodologies are available to examine various aspects of mitochondrial function, each requiring an understanding of their principles, advantages, and limitations. This review provides investigators with a critical overview of the strengths, limitations and critical experimental parameters to consider when selecting and conducting studies on mitochondrial function. In vitro (isolated mitochondria) and in situ (permeabilized cells/tissue) approaches provide direct access to the mitochondria, allowing for study of mitochondrial bioenergetics and redox function under defined substrate conditions. Several experimental parameters must be tightly controlled, including assay media, temperature, oxygen concentration, and in the case of permeabilized skeletal muscle, the contractile state of the fibers. Recently developed technology now offers the opportunity to measure oxygen consumption in intact cultured cells. Magnetic resonance spectroscopy provides the most direct way of assessing mitochondrial function in vivo with interpretations based on specific modeling approaches. The continuing rapid evolution of these technologies offers new and exciting opportunities for deciphering the potential role of mitochondrial function in the etiology and treatment of diabetes.
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Affiliation(s)
- Christopher G R Perry
- School of Kinesiology and Health Science, York University, Toronto, Ontario, Canada.
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72
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Kristensen JM, Larsen S, Helge JW, Dela F, Wojtaszewski JFP. Two weeks of metformin treatment enhances mitochondrial respiration in skeletal muscle of AMPK kinase dead but not wild type mice. PLoS One 2013; 8:e53533. [PMID: 23341947 PMCID: PMC3544921 DOI: 10.1371/journal.pone.0053533] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2012] [Accepted: 12/03/2012] [Indexed: 12/25/2022] Open
Abstract
Metformin is used as an anti-diabetic drug. Metformin ameliorates insulin resistance by improving insulin sensitivity in liver and skeletal muscle. Reduced mitochondrial content has been reported in type 2 diabetic muscles and it may contribute to decreased insulin sensitivity characteristic for diabetic muscles. The molecular mechanism behind the effect of metformin is not fully clarified but inhibition of complex I in the mitochondria and also activation of the 5'AMP activated protein kinase (AMPK) has been reported in muscle. Furthermore, both AMPK activation and metformin treatment have been associated with stimulation of mitochondrial function and biogenesis. However, a causal relationship in skeletal muscle has not been investigated. We hypothesized that potential effects of in vivo metformin treatment on mitochondrial function and protein expressions in skeletal muscle are dependent upon AMPK signaling. We investigated this by two weeks of oral metformin treatment of muscle specific kinase dead α(2) (KD) AMPK mice and wild type (WT) littermates. We measured mitochondrial respiration and protein activity and expressions of key enzymes involved in mitochondrial carbohydrate and fat metabolism and oxidative phosphorylation. Mitochondrial respiration, HAD and CS activity, PDH and complex I-V and cytochrome c protein expression were all reduced in AMPK KD compared to WT tibialis anterior muscles. Surprisingly, metformin treatment only enhanced respiration in AMPK KD mice and thereby rescued the respiration defect compared to the WT mice. Metformin did not influence protein activities or expressions in either WT or AMPK KD mice.We conclude that two weeks of in vivo metformin treatment enhances mitochondrial respiration in the mitochondrial deficient AMPK KD but not WT mice. The improvement seems to be unrelated to AMPK, and does not involve changes in key mitochondrial proteins.
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Affiliation(s)
- Jonas M Kristensen
- Section of Molecular Physiology Group, August Krogh Centre, Department of Nutrition, Exercise and Sport Sciences, University of Copenhagen, Denmark.
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73
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Picard M, Jung B, Liang F, Azuelos I, Hussain S, Goldberg P, Godin R, Danialou G, Chaturvedi R, Rygiel K, Matecki S, Jaber S, Des Rosiers C, Karpati G, Ferri L, Burelle Y, Turnbull DM, Taivassalo T, Petrof BJ. Mitochondrial dysfunction and lipid accumulation in the human diaphragm during mechanical ventilation. Am J Respir Crit Care Med 2012; 186:1140-9. [PMID: 23024021 DOI: 10.1164/rccm.201206-0982oc] [Citation(s) in RCA: 153] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
RATIONALE Mechanical ventilation (MV) is associated with adverse effects on the diaphragm, but the cellular basis for this phenomenon, referred to as ventilator-induced diaphragmatic dysfunction (VIDD), is poorly understood. OBJECTIVES To determine whether mitochondrial function and cellular energy status are disrupted in human diaphragms after MV, and the role of mitochondria-derived oxidative stress in the development of VIDD. METHODS Diaphragm and biceps specimens obtained from brain-dead organ donors who underwent MV (15-176 h) and age-matched control subjects were compared regarding mitochondrial enzymatic function, mitochondrial DNA integrity, lipid content, and metabolic gene and protein expression. In addition, diaphragmatic force and oxidative stress after exposure to MV for 6 hours were evaluated in mice under different conditions. MEASUREMENTS AND MAIN RESULTS In human MV diaphragms, mitochondrial biogenesis and content were down-regulated, with a more specific defect of respiratory chain cytochrome-c oxidase. Laser capture microdissection of cytochrome-c oxidase-deficient fibers revealed mitochondrial DNA deletions, consistent with damage from oxidative stress. Diaphragmatic lipid accumulation and responses of master cellular metabolic sensors (AMP-activated protein kinase and sirtuins) were consistent with energy substrate excess as a possible stimulus for these changes. In mice, induction of hyperlipidemia worsened diaphragmatic oxidative stress during MV, whereas transgenic overexpression of a mitochondria-localized antioxidant (peroxiredoxin-3) was protective against VIDD. CONCLUSIONS Our data suggest that mitochondrial dysfunction lies at the nexus between oxidative stress and the impaired diaphragmatic contractility that develops during MV. Energy substrate oversupply relative to demand, resulting from diaphragmatic inactivity during MV, could play an important role in this process.
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Affiliation(s)
- Martin Picard
- Meakins-Christie Laboratories, 3626 Saint Urbain Street, Montreal, PQ, H2X 2P2 Canada
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74
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Gruzman A, Elgart A, Viskind O, Billauer H, Dotan S, Cohen G, Mishani E, Hoffman A, Cerasi E, Sasson S. Antihyperglycaemic activity of 2,4:3,5-dibenzylidene-D-xylose-diethyl dithioacetal in diabetic mice. J Cell Mol Med 2012; 16:594-604. [PMID: 21564514 PMCID: PMC3822934 DOI: 10.1111/j.1582-4934.2011.01340.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
We have recently generated lipophilic D-xylose derivatives that increase the rate of glucose uptake in cultured skeletal muscle cells in an AMP-activated protein kinase (AMPK)-dependent manner. The derivative 2,4:3,5-dibenzylidene-D-xylose-diethyl dithioacetal (EH-36) stimulated the rate of glucose transport by increasing the abundance of glucose transporter-4 in the plasma membrane of cultured myotubes. The present study aimed at investigating potential antihyperglycaemic effects of EH-36 in animal models of diabetes. Two animal models were treated subcutaneously with EH-36: streptozotocin-induced diabetes in C57BL/6 mice (a model of insulin-deficient type 1 diabetes), and spontaneously diabetic KKAy mice (Kuo Kondo rats carrying the A(y) yellow obese gene; insulin-resistant type 2 diabetes). The in vivo biodistribution of glucose in control and treated mice was followed with the glucose analogue 2-deoxy-2-[(18) F]-D-glucose; the rate of glucose uptake in excised soleus muscles was measured with [(3) H]-2-deoxy-D-glucose. Pharmacokinetic parameters were determined by non-compartmental analysis of the in vivo data. The effective blood EH-36 concentration in treated animals was 2 μM. It reduced significantly the blood glucose levels in both types of diabetic mice and also corrected the typical compensatory hyperinsulinaemia of KKAy mice. EH-36 markedly increased glucose transport in vivo into skeletal muscle and heart, but not to adipose tissue. This stimulatory effect was mediated by Thr(172) -phosphorylation in AMPK. Biochemical tests in treated animals and acute toxicological examinations showed that EH-36 was well tolerated and not toxic to the mice. These findings indicate that EH-36 is a promising prototype molecule for the development of novel antidiabetic drugs.
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Affiliation(s)
- Arie Gruzman
- Department of Pharmacology, Institute for Drug Research, School of Pharmacy, Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem, Israel
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Gilliam LAA, Neufer PD. Transgenic mouse models resistant to diet-induced metabolic disease: is energy balance the key? J Pharmacol Exp Ther 2012; 342:631-6. [PMID: 22700428 DOI: 10.1124/jpet.112.192146] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
The prevalence and economic burden of obesity and type 2 diabetes is a driving force for the discovery of molecular targets to improve insulin sensitivity and glycemic control. Here, we review several transgenic mouse models that identify promising targets, ranging from proteins involved in the insulin signaling pathway, alterations of genes affecting energy metabolism, and transcriptional metabolic regulators. Despite the diverse endpoints in each model, a common thread that emerges is the necessity for maintenance of energy balance, suggesting pharmacotherapy must target the development of drugs that decrease energy intake, accelerate energy expenditure in a well controlled manner, or augment natural compensatory responses to positive energy balance.
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Affiliation(s)
- Laura A A Gilliam
- Department of Physiology, East Carolina University, Greenville, NC, USA
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76
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Genome protective effect of metformin as revealed by reduced level of constitutive DNA damage signaling. Aging (Albany NY) 2012; 3:1028-38. [PMID: 22067284 PMCID: PMC3229966 DOI: 10.18632/aging.100397] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
We have shown before that constitutive DNA damage signaling represented by H2AX-Ser139 phosphorylation and ATM activation in untreated normal and tumor cells is a reporter of the persistent DNA replication stress induced by endogenous oxidants, the by-products of aerobic respiration. In the present study we observed that exposure of normal mitogenically stimulated lymphocytes or tumor cell lines A549, TK6 and A431 to metformin, the specific activator of 5'AMP-activated protein kinase (AMPK) and an inhibitor of mTOR signaling, resulted in attenuation of constitutive H2AX phosphorylation and ATM activation. The effects were metformin-concentration dependent and seen even at the pharmacologically pertinent 0.1 mM drug concentration. The data also show that intracellular levels of endogenous reactive oxidants able to oxidize 2',7'-dihydro-dichlorofluorescein diacetate was reduced in metformin-treated cells. Since persistent constitutive DNA replication stress, particularly when paralleled by mTOR signaling, is considered to be the major cause of aging, the present findings are consistent with the notion that metformin, by reducing both DNA replication stress and mTOR-signaling, slows down aging and/or cell senescence processes.
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77
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Larsen S, Rabøl R, Hansen CN, Madsbad S, Helge JW, Dela F. Metformin-treated patients with type 2 diabetes have normal mitochondrial complex I respiration. Diabetologia 2012; 55:443-9. [PMID: 22009334 DOI: 10.1007/s00125-011-2340-0] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/18/2011] [Accepted: 09/22/2011] [Indexed: 12/13/2022]
Abstract
AIMS/HYPOTHESIS The glucose-lowering drug metformin has been shown to inhibit complex I of the mitochondrial electron transport chain in skeletal muscle. To investigate this effect in vivo we studied skeletal muscle mitochondrial respiratory capacity and content from patients with type 2 diabetes treated with metformin (n = 14) or sulfonylurea (n = 8) and healthy control (n = 18) participants. METHODS Mitochondrial respiratory capacity was measured ex vivo in permeabilised muscle fibres obtained from the vastus lateralis muscle of all participants. The respiratory response to in vitro titration with metformin was measured in controls. Citrate synthase (CS) activity, and fasting plasma glucose, insulin and HbA(1c) levels were measured and body composition was determined. RESULTS Participants were matched for age, BMI and percentage body fat. Fasting plasma glucose concentrations were higher (p < 0.05) in those treated with sulfonylureas and metformin than in controls. CS activity was comparable between metformin-treated and control participants, but tended to be lower in those receiving sulfonylureas. Mitochondrial respiratory capacity with substrates for complex I and complex I and II was comparable in the groups, both when estimated per mg of tissue and when normalised to CS activity. In vitro metformin titration demonstrated a dose-dependent inhibitory effect on complex I and II in human skeletal muscle at suprapharmacological concentrations. CONCLUSIONS/INTERPRETATION Metformin treatment does not inhibit mitochondrial complex I respiration in the electron transport chain in human skeletal muscle of patients with type 2 diabetes when measured ex vivo. Inhibition of complex I and II respiration in controls was demonstrated by metformin titration in vitro at doses well above those observed during metformin treatment.
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Affiliation(s)
- S Larsen
- Xlab, Center for Healthy Aging, Department of Biomedical Sciences, Faculty of Health Sciences, University of Copenhagen, Blegdamsvej 3b, 2200 Copenhagen N, Denmark.
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78
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Abstract
Considerable efforts have been made since the 1950s to better understand the cellular and molecular mechanisms of action of metformin, a potent antihyperglycaemic agent now recommended as the first-line oral therapy for T2D (Type 2 diabetes). The main effect of this drug from the biguanide family is to acutely decrease hepatic glucose production, mostly through a mild and transient inhibition of the mitochondrial respiratory chain complex I. In addition, the resulting decrease in hepatic energy status activates AMPK (AMP-activated protein kinase), a cellular metabolic sensor, providing a generally accepted mechanism for the action of metformin on hepatic gluconeogenesis. The demonstration that respiratory chain complex I, but not AMPK, is the primary target of metformin was recently strengthened by showing that the metabolic effect of the drug is preserved in liver-specific AMPK-deficient mice. Beyond its effect on glucose metabolism, metformin has been reported to restore ovarian function in PCOS (polycystic ovary syndrome), reduce fatty liver, and to lower microvascular and macrovascular complications associated with T2D. Its use has also recently been suggested as an adjuvant treatment for cancer or gestational diabetes and for the prevention in pre-diabetic populations. These emerging new therapeutic areas for metformin will be reviewed together with recent findings from pharmacogenetic studies linking genetic variations to drug response, a promising new step towards personalized medicine in the treatment of T2D.
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79
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The role of metformin and thiazolidinediones in the regulation of hepatic glucose metabolism and its clinical impact. Trends Pharmacol Sci 2011; 32:607-16. [PMID: 21824668 DOI: 10.1016/j.tips.2011.06.006] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2011] [Revised: 06/16/2011] [Accepted: 06/21/2011] [Indexed: 12/25/2022]
Abstract
Fasting hyperglycemia in type 2 diabetes mellitus (T2DM) results from elevated endogenous glucose production (EGP), which is mostly due to augmented hepatic gluconeogenesis. Insulin-resistant humans exhibit impaired insulin-dependent suppression of EGP and excessive hepatic lipid storage (steatosis), which relates to abnormal supply of free fatty acids (FFA) and energy metabolism. Only two glucose-lowering drug classes, the biguanide metformin and the thiazolidendiones (TZDs), exert insulin- and glucagon-independent hepatic effects. Preclinical studies suggest that metformin inhibits mitochondrial complex I. TZDs, as peroxisome proliferator-activated receptor (PPAR) γ-agonists, predominantly reduce the flux of FFA and cytokines from adipose tissue to the liver, but could also directly inhibit mitochondrial complex I. Although both metformin and TZDs improve fasting hyperglycemia and EGP in clinical trials, only TZDs decrease steatosis and peripheral insulin resistance. More studies are required to address their effects on hepatocellular energy metabolism with a view to identifying novel targets for the treatment of T2DM.
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Kane DA, Lin CT, Anderson EJ, Kwak HB, Cox JH, Brophy PM, Hickner RC, Neufer PD, Cortright RN. Progesterone increases skeletal muscle mitochondrial H2O2 emission in nonmenopausal women. Am J Physiol Endocrinol Metab 2011; 300:E528-35. [PMID: 21189359 PMCID: PMC3064007 DOI: 10.1152/ajpendo.00389.2010] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The luteal phase of the female menstrual cycle is associated with both 1) elevated serum progesterone (P4) and estradiol (E2), and 2) reduced insulin sensitivity. Recently, we demonstrated a link between skeletal muscle mitochondrial H(2)O(2) emission (mE(H2O2)) and insulin resistance. To determine whether serum levels of P4 and/or E(2) are related to mitochondrial function, mE(H2O2) and respiratory O(2) flux (Jo(2)) were measured in permeabilized myofibers from insulin-sensitive (IS, n = 24) and -resistant (IR, n = 8) nonmenopausal women (IR = HOMA-IR > 3.6). Succinate-supported mE(H2O2) was more than 50% greater in the IR vs. IS women (P < 0.05). Interestingly, serum P4 correlated positively with succinate-supported mE(H2O2) (r = 0. 53, P < 0.01). To determine whether P4 or E2 directly affect mitochondrial function, saponin-permeabilized vastus lateralis myofibers biopsied from five nonmenopausal women in the early follicular phase were incubated in P4 (60 nM), E2 (1.4 nM), or both. P4 alone inhibited state 3 Jo(2), supported by multisubstrate combination (P < 0.01). However, E2 alone or in combination with P4 had no effect on Jo(2). In contrast, during state 4 respiration, supported by succinate and glycerophosphate, mE(H2O2) was increased with P4 alone or in combination with E2 (P < 0.01). The results suggest that 1) P4 increases mE(H2O2) with or without E2; 2) P4 alone inhibits Jo(2) but not when E2 is present; and 3) P4 is related to the mE(H2O2) previously linked to skeletal muscle insulin resistance.
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Affiliation(s)
- Daniel A Kane
- The Human Performance Laboratory, East Carolina University, Greenville, NC 27858, USA.
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