Impaired Glycogen Synthase Activity and Mitochondrial Dysfunction in Skeletal Muscle: Markers or Mediators of Insulin Resistance in Type 2 Diabetes?

2006 ◽  
Vol 2 (4) ◽  
pp. 375-395 ◽  
Author(s):  
Bentham Science Publisher Bentham Science Publisher
Keyword(s):  
Insulin Resistance ◽  
Type 2 Diabetes ◽  
Skeletal Muscle ◽  
Mitochondrial Dysfunction ◽  
Glycogen Synthase ◽  
Glycogen Synthase Activity

scholarly journals Mitochondrial Function in Skeletal Muscle Is Normal and Unrelated to Insulin Action in Young Men Born with Low Birth Weight

2008 ◽  
Vol 93 (10) ◽  
pp. 3885-3892 ◽  
Author(s):  
Charlotte Brøns ◽  
Christine B. Jensen ◽  
Heidi Storgaard ◽  
Amra Alibegovic ◽  
Stine Jacobsen ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Type 2 Diabetes ◽  
Skeletal Muscle ◽  
Birth Weight ◽  
Low Birth Weight ◽  
Mitochondrial Dysfunction ◽  
Mitochondrial Function ◽  
Young Men ◽  
Hepatic Insulin Resistance

Objective: Low birth weight (LBW) is an independent risk factor of insulin resistance and type 2 diabetes. Recent studies suggest that mitochondrial dysfunction and impaired expression of genes involved in oxidative phosphorylation (OXPHOS) may play a key role in the pathogenesis of insulin resistance in aging and type 2 diabetes. The aim of this study was to determine whether LBW in humans is associated with mitochondrial dysfunction in skeletal muscle. Methods: Mitochondrial capacity for ATP synthesis was assessed by 31phosphorus magnetic resonance spectroscopy in forearm and leg muscles in 20 young, lean men with LBW and 26 matched controls. On a separate day, a hyperinsulinemic euglycemic clamp with excision of muscle biopsies and dual-energy x-ray absorptiometry scanning was performed. Muscle gene expression of selected OXPHOS genes was determined by quantitative real-time PCR. Results: The LBW subjects displayed a variety of metabolic and prediabetic abnormalities, including elevated fasting blood glucose and plasma insulin levels, reduced insulin-stimulated glycolytic flux, and hepatic insulin resistance. Nevertheless, in vivo mitochondrial function was normal in LBW subjects, as was the expression of OXPHOS genes. Conclusions: These data support and expand previous findings of abnormal glucose metabolism in young men with LBW. In addition, we found that the young, healthy men with LBW exhibited hepatic insulin resistance. However, the study does not support the hypothesis that muscle mitochondrial dysfunction per se is the underlying key metabolic defect that explains or precedes whole body insulin resistance in LBW subjects at risk for developing type 2 diabetes.

scholarly journals Potential role of glycogen synthase kinase-3 in skeletal muscle insulin resistance of type 2 diabetes

Diabetes ◽  
2000 ◽  
Vol 49 (2) ◽  
pp. 263-271 ◽  
Author(s):  
S. E. Nikoulina ◽  
T. P. Ciaraldi ◽  
S. Mudaliar ◽  
P. Mohideen ◽  
L. Carter ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Type 2 Diabetes ◽  
Skeletal Muscle ◽  
Potential Role ◽  
Glycogen Synthase ◽  
Glycogen Synthase Kinase 3 ◽  
Muscle Insulin Resistance ◽  
Skeletal Muscle Insulin Resistance

Oxidative stress in skeletal muscle impairs mitochondrial respiration and limits exercise capacity in type 2 diabetic mice

2009 ◽  
Vol 297 (3) ◽  
pp. H1069-H1077 ◽  
Author(s):  
Takashi Yokota ◽  
Shintaro Kinugawa ◽  
Kagami Hirabayashi ◽  
Shouji Matsushima ◽  
Naoki Inoue ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Insulin Resistance ◽  
Type 2 Diabetes ◽  
Skeletal Muscle ◽  
Mitochondrial Dysfunction ◽  
Exercise Capacity ◽  
Mitochondrial Function ◽  
Exercise Intolerance ◽  
Whole Body

Insulin resistance or diabetes is associated with limited exercise capacity, which can be caused by the abnormal energy metabolism in skeletal muscle. Oxidative stress is involved in mitochondrial dysfunction in diabetes. We hypothesized that increased oxidative stress could cause mitochondrial dysfunction in skeletal muscle and make contribution to exercise intolerance in diabetes. C57/BL6J mice were fed on normal diet or high fat diet (HFD) for 8 wk to induce obesity with insulin resistance and diabetes. Treadmill tests with expired gas analysis were performed to determine the exercise capacity and whole body oxygen uptake (V̇o2). The work (vertical distance × body weight) to exhaustion was reduced in the HFD mice by 36%, accompanied by a 16% decrease of peak V̇o2. Mitochondrial ADP-stimulated respiration, electron transport chain complex I and III activities, and mitochondrial content in skeletal muscle were decreased in the HFD mice. Furthermore, superoxide production and NAD(P)H oxidase activity in skeletal muscle were significantly increased in the HFD mice. Intriguingly, the treatment of HFD-fed mice with apocynin [10 mmol/l; an inhibitor of NAD(P)H oxidase activation] improved exercise intolerance and mitochondrial dysfunction in skeletal muscle without affecting glucose metabolism itself. The exercise capacity and mitochondrial function in skeletal muscle were impaired in type 2 diabetes, which might be due to enhanced oxidative stress. Therapies designed to regulate oxidative stress and maintain mitochondrial function could be beneficial to improve the exercise capacity in type 2 diabetes.

scholarly journals Early or advanced stage type 2 diabetes is not accompanied by in vivo skeletal muscle mitochondrial dysfunction

2008 ◽  
Vol 158 (5) ◽  
pp. 643-653 ◽  
Author(s):  
H M De Feyter ◽  
N M A van den Broek ◽  
S F E Praet ◽  
K Nicolay ◽  
L J C van Loon ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Type 2 Diabetes ◽  
Skeletal Muscle ◽  
Mitochondrial Dysfunction ◽  
Mitochondrial Function ◽  
Resonance Spectroscopy ◽  
Diabetes Patients

ObjectiveSeveral lines of evidence support a potential role of skeletal muscle mitochondrial dysfunction in the pathogenesis of insulin resistance and/or type 2 diabetes. However, it remains to be established whether mitochondrial dysfunction represents either cause or consequence of the disease. We examined in vivo skeletal muscle mitochondrial function in early and advanced stages of type 2 diabetes, with the aim to gain insight in the proposed role of mitochondrial dysfunction in the aetiology of insulin resistance and/or type 2 diabetes.MethodsTen long-standing, insulin-treated type 2 diabetes patients, 11 subjects with impaired fasting glucose, impaired glucose tolerance and/or recently diagnosed type 2 diabetes, and 12 healthy, normoglycaemic controls, matched for age and body composition and with low habitual physical activity levels were studied. In vivo mitochondrial function of the vastus lateralis muscle was evaluated from post-exercise phosphocreatine (PCr) recovery kinetics using 31P magnetic resonance spectroscopy (MRS). Intramyocellular lipid (IMCL) content was assessed in the same muscle using single-voxel 1H MRS.ResultsIMCL content tended to be higher in the type 2 diabetes patients when compared with normoglycaemic controls (P=0.06). The31P MRS parameters for mitochondrial function, i.e. PCr and ADP recovery time constants and maximum aerobic capacity, did not differ between groups.ConclusionsThe finding that in vivo skeletal muscle oxidative capacity does not differ between long-standing, insulin-treated type 2 diabetes patients, subjects with early stage type 2 diabetes and sedentary, normoglycaemic controls suggests that mitochondrial dysfunction does not necessarily represent either cause or consequence of insulin resistance and/or type 2 diabetes.

scholarly journals Analysis of gene expression profiles in insulin-sensitive tissues from pre-diabetic and diabetic Zucker diabetic fatty rats

2005 ◽  
Vol 34 (2) ◽  
pp. 299-315 ◽  
Author(s):  
Young Ho Suh ◽  
Younyoung Kim ◽  
Jeong Hyun Bang ◽  
Kyoung Suk Choi ◽  
June Woo Lee ◽  
...  
Keyword(s):  
Gene Expression ◽  
Insulin Resistance ◽  
Type 2 Diabetes ◽  
Skeletal Muscle ◽  
Adipose Tissue ◽  
Expression Profiles ◽  
Gene Expression Profiles ◽  
Zucker Diabetic Fatty Rats ◽  
Zdf Rats

Insulin resistance occurs early in the disease process, preceding the development of type 2 diabetes. Therefore, the identification of molecules that contribute to insulin resistance and leading up to type 2 diabetes is important to elucidate the molecular pathogenesis of the disease. To this end, we characterized gene expression profiles from insulin-sensitive tissues, including adipose tissue, skeletal muscle, and liver tissue of Zucker diabetic fatty (ZDF) rats, a well characterized type 2 diabetes animal model. Gene expression profiles from ZDF rats at 6 weeks (pre-diabetes), 12 weeks (diabetes), and 20 weeks (late-stage diabetes) were compared with age- and sex-matched Zucker lean control (ZLC) rats using 5000 cDNA chips. Differentially regulated genes demonstrating > 1.3-fold change at age were identified and categorized through hierarchical clustering analysis. Our results showed that while expression of lipolytic genes was elevated in adipose tissue of diabetic ZDF rats at 12 weeks of age, expression of lipogenic genes was decreased in liver but increased in skeletal muscle of 12 week old diabetic ZDF rats. These results suggest that impairment of hepatic lipogenesis accompanied with the reduced lipogenesis of adipose tissue may contribute to development of diabetes in ZDF rats by increasing lipogenesis in skeletal muscle. Moreover, expression of antioxidant defense genes was decreased in the liver of 12-week old diabetic ZDF rats as well as in the adipose tissue of ZDF rats both at 6 and 12 weeks of age. Cytochrome P450 (CYP) genes were also significantly reduced in 12 week old diabetic liver of ZDF rats. Genes involved in glucose utilization were downregulated in skeletal muscle of diabetic ZDF rats, and the hepatic gluconeogenic gene was upregulated in diabetic ZDF rats. Genes commonly expressed in all three tissue types were also observed. These profilings might provide better fundamental understanding of insulin resistance and development of type 2 diabetes.

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