Assessment of the redox status in patients with metabolic syndrome and type 2 diabetes reveals great variations

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Abstract

The aim of the present study was to examine the effectiveness of a new redox status marker, the static oxidation reduction potential (sORP), for assessing oxidative stress in 75 patients with metabolic syndrome (MetS) and type 2 diabetes (T2D). A total of 35 normal subjects were used as the controls. Moreover, conventional markers of oxidative stress were assessed, such as thiobarbituric acid reactive substances (TBARS), protein carbonyls, the total antioxidant capacity in plasma, glutathione (GSH) levels and catalase (CAT) activity in erythrocytes. The results revealed that sORP was significantly higher (by 13.4%) in the patients with MetS and T2D compared to the controls, indicating an increase in oxidative stress. This finding was also supported by the significantly lower levels (by 27.7%) of GSH and the higher levels (by 23.3%) of CAT activity in the patients with MetS and T2D compared to the controls. Moreover, our results indicated a great variation in oxidative stress markers between the different patients with MetS and T2D, particarly as regards the GSH levels. Thus, the patients with MetS and T2D were divided into 2 subgroups, one with low GSH levels (n=31; GSH <3 µmol/g Hb) and another with high GSH levels (n=35; GSH >4 µmol/g Hb). The comparison of the markers between the 2 subgroups indicated that in the low GSH group, the GSH levels were significantly lower (by 51.7 and 52.9%) than those in the high GSH group and the controls, respectively. Furthermore, sORP in the low GSH group was significantly higher (by 8.1%) compared to the high GSH group, suggesting its sensitivity for assessing oxidative stress in patients wtih MetS and T2D. Moreover, this variation in oxidative stress levels between the different patients with T2D suggests that the assessment of the redox status may be important in prediabetic conditions, since there is evidence indicating that differences in the redox status in pre-diabetes may result in different outcomes.

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Antioxidants prevent health-promoting effects of physical exercise in humans.

Michael Ristow, Kim Zarse, Andreas Oberbach … (2009)

Exercise promotes longevity and ameliorates type 2 diabetes mellitus and insulin resistance. However, exercise also increases mitochondrial formation of presumably harmful reactive oxygen species (ROS). Antioxidants are widely used as supplements but whether they affect the health-promoting effects of exercise is unknown. We evaluated the effects of a combination of vitamin C (1000 mg/day) and vitamin E (400 IU/day) on insulin sensitivity as measured by glucose infusion rates (GIR) during a hyperinsulinemic, euglycemic clamp in previously untrained (n = 19) and pretrained (n = 20) healthy young men. Before and after a 4 week intervention of physical exercise, GIR was determined, and muscle biopsies for gene expression analyses as well as plasma samples were obtained to compare changes over baseline and potential influences of vitamins on exercise effects. Exercise increased parameters of insulin sensitivity (GIR and plasma adiponectin) only in the absence of antioxidants in both previously untrained (P < 0.001) and pretrained (P < 0.001) individuals. This was paralleled by increased expression of ROS-sensitive transcriptional regulators of insulin sensitivity and ROS defense capacity, peroxisome-proliferator-activated receptor gamma (PPARgamma), and PPARgamma coactivators PGC1alpha and PGC1beta only in the absence of antioxidants (P < 0.001 for all). Molecular mediators of endogenous ROS defense (superoxide dismutases 1 and 2; glutathione peroxidase) were also induced by exercise, and this effect too was blocked by antioxidant supplementation. Consistent with the concept of mitohormesis, exercise-induced oxidative stress ameliorates insulin resistance and causes an adaptive response promoting endogenous antioxidant defense capacity. Supplementation with antioxidants may preclude these health-promoting effects of exercise in humans.

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Relation between antioxidant enzyme gene expression and antioxidative defense status of insulin-producing cells.

M Tiedge, S Lortz, J Drinkgern … (1997)

Antioxidant enzyme expression was determined in rat pancreatic islets and RINm5F insulin-producing cells on the level of mRNA, protein, and enzyme activity in comparison with 11 other rat tissues. Although superoxide dismutase expression was in the range of 30% of the liver values, the expression of the hydrogen peroxide-inactivating enzymes catalase and glutathione peroxidase was extremely low, in the range of 5% of the liver. Pancreatic islets but not RINm5F cells expressed an additional phospholipid hydroperoxide glutathione peroxidase that exerted protective effects against lipid peroxidation of the plasma membrane. Regression analysis for mRNA and protein expression and enzyme activities from 12 rat tissues revealed that the mRNA levels determine the enzyme activities of the tissues. The induction of cellular stress by high glucose, high oxygen, and heat shock treatment did not affect antioxidant enzyme expression in rat pancreatic islets or in RINm5F cells. Thus insulin-producing cells cannot adapt the low antioxidant enzyme activity levels to typical situations of cellular stress by an upregulation of gene expression. Through stable transfection, however, we were able to increase catalase and glutathione peroxidase gene expression in RINm5F cells, resulting in enzyme activities more than 100-fold higher than in nontransfected controls. Catalase-transfected RINm5F cells showed a 10-fold greater resistance toward hydrogen peroxide toxicity, whereas glutathione peroxidase overexpression was much less effective. Thus inactivation of hydrogen peroxide through catalase seems to be a step of critical importance for the removal of reactive oxygen species in insulin-producing cells. Overexpression of catalase may therefore be an effective means of preventing the toxic action of reactive oxygen species.

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Oxidative stress and metabolic syndrome.

Christian K Roberts, Kunal Sindhu (2009)

Metabolic syndrome is a collection of cardiometabolic risk factors that includes obesity, insulin resistance, hypertension and dyslipidemia. Although there has been significant debate regarding the criteria and concept of the syndrome, this clustering of risk factors is unequivocally linked to an increased risk of developing type 2 diabetes and cardiovascular disease. Metabolic syndrome is often characterized by oxidative stress, a condition in which an imbalance results between the production and inactivation of reactive oxygen species. Reactive oxygen species can best be described as double-edged swords; while they play an essential role in multiple physiological systems, under conditions of oxidative stress, they contribute to cellular dysfunction. Oxidative stress is thought to play a major role in the pathogenesis of a variety of human diseases, including atherosclerosis, diabetes, hypertension, aging, Alzheimer's disease, kidney disease and cancer. The purpose of this review is to discuss the role of oxidative stress in metabolic syndrome and its major clinical manifestations (namely coronary artery disease, hypertension and diabetes). It will also highlight the effects of lifestyle modification in ameliorating oxidative stress in metabolic syndrome. Discussion will be limited to human data.

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Author and article information

Journal

Journal ID (nlm-ta): Exp Ther Med

Journal ID (iso-abbrev): Exp Ther Med

Journal ID (publisher-id): ETM

Title: Experimental and Therapeutic Medicine

Publisher: D.A. Spandidos

ISSN (Print): 1792-0981

ISSN (Electronic): 1792-1015

Publication date (Print): March 2016

Publication date (Electronic): 05 January 2016

Publication date PMC-release: 05 January 2016

Volume: 11

Issue: 3

Pages: 895-903

Affiliations

[1 ]Department of Biochemistry and Biotechnology, University of Thessaly, Larissa 41221, Greece

[2 ]Department of Trauma Research, St. Anthony Hospital, Lakewood, CO 80228, USA

[3 ]Department of Trauma Research, Swedish Medical Center, Englewood, CO 80113, USA

[4 ]Department of Trauma Research, Medical Center of Plano, Plano, TX 75075, USA

[5 ]Luoxis Diagnostics, Inc., Englewood, CO 80112, USA

[6 ]Department of Intensive Care, University Hospital of Thessaly Biopolis, Larissa 41110, Greece

[7 ]Laboratory of Clinical Virology, University of Crete, Medical School, Heraklion 71409, Greece

[8 ]Department of Forensic Sciences and Toxicology, Medical School, University of Crete, Heraklion 71003, Greece

[9 ]Standard Centre of Bioassays, ‘Hartografoi Hygeias’, Athens 15124, Greece

Author notes

Correspondence to: Professor Demetrios Kouretas, Department of Biochemistry and Biotechnology, University of Thessaly, Ploutonos 26 and Aiolou Street, Larissa 41221, Greece, E-mail: dkouret@ 123456uth.gr

Article

Publisher ID: ETM-0-0-2968

DOI: 10.3892/etm.2016.2968

PMC ID: 4774368

PubMed ID: 26998009

SO-VID: f6de5928-b247-4bc9-87a7-06663cb6865a

License:

This is an open access article distributed under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.

Assessment of the redox status in patients with metabolic syndrome and type 2 diabetes reveals great variations

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Most cited references 50

Antioxidants prevent health-promoting effects of physical exercise in humans.

Relation between antioxidant enzyme gene expression and antioxidative defense status of insulin-producing cells.

Oxidative stress and metabolic syndrome.

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