scholarly journals Mice lacking PKC-θ in skeletal muscle have reduced intramyocellular lipid accumulation and increased insulin responsiveness in skeletal muscle

2018 ◽  
Vol 314 (3) ◽  
pp. R468-R477 ◽  
Author(s):  
Bailey Peck ◽  
Josh Huot ◽  
Tim Renzi ◽  
Susan Arthur ◽  
Michael J. Turner ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Skeletal Muscle ◽  
Lipid Accumulation ◽  
Specific Effect ◽  
Whole Body ◽  
Mrna Levels ◽  
Intramyocellular Lipid ◽  
Fatty Acid Binding ◽  
Tissue Specific ◽  
Insulin Responsiveness

Protein kinase C-θ (PKC-θ) is a lipid-sensitive molecule associated with lipid-induced insulin resistance in skeletal muscle. Rodent models have not cohesively supported that PKC-θ impairs insulin responsiveness in skeletal muscle. The purpose of this study was to generate mice that lack PKC-θ in skeletal muscle and determine how lipid accumulation and insulin responsiveness are affected in that tissue. Mice lacking PKC-θ in skeletal muscle (SkMPKCθKO) and controls (SkMPKCθWT) were placed on a regular diet (RD) or high-fat diet (HFD) for 15 wk, followed by determination of food intake, fasting glucose levels, lipid accumulation, and insulin responsiveness. There were no differences between SkMPKCθWTand SkMPKCθKOmice on a RD. SkMPKCθKOmice on a HFD gained less weight from 10 through 15 wk of dietary intervention ( P < 0.05). This was likely due to less caloric consumption ( P = 0.0183) and fewer calories from fat ( P < 0.001) compared with SkMPKCθWTmice on a HFD. Intramyocellular lipid accumulation ( P < 0.0001), fatty acid binding protein 4, and TNF-α mRNA levels ( P < 0.05) were markedly reduced in SkMPKCθKOcompared with SkMPKCθWTmice on a HFD. As a result, fasting hyperglycemia was mitigated and insulin responsiveness, as indicated by Akt phosphorylation, was maintained in SkMPKCθKOon a HFD. Liver lipid accumulation was not affected by genotype, suggesting the deletion of PKC-θ from skeletal muscle has a tissue-specific effect. PKC-θ is a regulator of lipid-induced insulin resistance in skeletal muscle. However, the effects of this mutation may be tissue specific. Further work is warranted to comprehensively evaluated whole body metabolic responses in this model.

scholarly journals Rapid development of systemic insulin resistance with overeating is not accompanied by robust changes in skeletal muscle glucose and lipid metabolism

2013 ◽  
Vol 38 (5) ◽  
pp. 512-519 ◽  
Author(s):  
Andrea S. Cornford ◽  
Alexander Hinko ◽  
Rachael K. Nelson ◽  
Ariel L. Barkan ◽  
Jeffrey F. Horowitz
Keyword(s):  
Insulin Resistance ◽  
Skeletal Muscle ◽  
Lipid Metabolism ◽  
Insulin Sensitivity ◽  
Lipid Accumulation ◽  
Rapid Development ◽  
Insulin Response ◽  
Whole Body ◽  
Muscle Lipid ◽  
Wet Weight

Prolonged overeating and the resultant weight gain are clearly linked with the development of insulin resistance and other cardiometabolic abnormalities, but adaptations that occur after relatively short periods of overeating are not completely understood. The purpose of this study was to characterize metabolic adaptations that may accompany the development of insulin resistance after 2 weeks of overeating. Healthy, nonobese subjects (n = 9) were admitted to the hospital for 2 weeks, during which time they ate ∼4000 kcals·day−1 (70 kcal·kg−1 fat free mass·day−1). Insulin sensitivity was estimated during a meal tolerance test, and a muscle biopsy was obtained to assess muscle lipid accumulation and protein markers associated with insulin resistance, inflammation, and the regulation of lipid metabolism. Whole-body insulin sensitivity declined markedly after 2 weeks of overeating (Matsuda composite index: 8.3 ± 1.3 vs. 4.6 ± 0.7, p < 0.05). However, muscle markers of insulin resistance and inflammation (i.e., phosphorylation of IRS-1-Ser312, Akt-Ser473, and c-Jun N-terminal kinase) were not altered by overeating. Intramyocellular lipids tended to increase after 2 weeks of overeating (triacylglyceride: 7.6 ± 1.6 vs. 10.0 ± 1.8 nmol·mg−1 wet weight; diacylglyceride: 104 ± 10 vs. 142 ± 23 pmol·mg−1 wet weight) but these changes did not reach statistical significance. Overeating induced a 2-fold increase in 24-h insulin response (area under the curve (AUC); p < 0.05), with a resultant ∼35% reduction in 24-h plasma fatty acid AUC (p < 0.05). This chronic reduction in circulating fatty acids may help explain the lack of a robust increase in muscle lipid accumulation. In summary, our findings suggest alterations in skeletal muscle metabolism may not contribute meaningfully to the marked whole-body insulin resistance observed after 2 weeks of overeating.

scholarly journals Polycystic Ovary Syndrome Is Associated with Tissue-Specific Differences in Insulin Resistance

2009 ◽  
Vol 94 (1) ◽  
pp. 157-163 ◽  
Author(s):  
Theodore P. Ciaraldi ◽  
Vanita Aroda ◽  
Sunder Mudaliar ◽  
R. Jeffrey Chang ◽  
Robert R. Henry
Keyword(s):  
Insulin Resistance ◽  
Skeletal Muscle ◽  
Glucose Tolerance ◽  
Polycystic Ovary ◽  
Whole Body ◽  
Glucose Disposal ◽  
Signaling Proteins ◽  
Impaired Insulin ◽  
Isolated Adipocytes ◽  
Insulin Responsiveness

Abstract Objective: The potential differential contributions of skeletal muscle and adipose tissue to whole body insulin resistance were evaluated in subjects with polycystic ovary syndrome (PCOS). Research Design and Methods: Forty-two PCOS subjects and 15 body mass index-matched control subjects were studied. Insulin action was evaluated by the hyperinsulinemic/euglycemic clamp procedure. Isolated adipocytes and cultured muscle cells were analyzed for glucose transport activity; adipocytes, muscle tissue, and myotubes were analyzed for the expression and phosphorylation of insulin-signaling proteins. Results: Fifty-seven per cent of the PCOS subjects had impaired glucose tolerance and the lowest rate of maximal insulin-stimulated whole body glucose disposal compared to controls (P &lt; 0.01). PCOS subjects with normal glucose tolerance had intermediate reduction in glucose disposal rate (P &lt; 0.05 vs. both control and impaired glucose tolerance subjects). However, rates of maximal insulin-stimulated glucose transport (insulin responsiveness) into isolated adipocytes were comparable between all three groups, whereas PCOS subjects displayed impaired insulin sensitivity. In contrast, myotubes from PCOS subjects displayed reduced insulin responsiveness for glucose uptake and normal sensitivity. There were no differences between groups in the expression of glucose transporter 4 or insulin-signaling proteins or maximal insulin stimulation of phosphorylation of Akt in skeletal muscle, myotubes, or adipocytes. Conclusions: Individuals with PCOS display impaired insulin responsiveness in skeletal muscle and myotubes, whereas isolated adipocytes display impaired insulin sensitivity but normal responsiveness. Skeletal muscle and adipose tissue contribute differently to insulin resistance in PCOS. Insulin resistance in PCOS cannot be accounted for by differences in the expression of selected signaling molecules or maximal phosphorylation of Akt.

scholarly journals The PERSonalized Glucose Optimization Through Nutritional Intervention (PERSON) Study: Rationale, Design and Preliminary Screening Results

2021 ◽  
Vol 8 ◽  
Author(s):  
Anouk Gijbels ◽  
Inez Trouwborst ◽  
Kelly M. Jardon ◽  
Gabby B. Hul ◽  
Els Siebelink ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Skeletal Muscle ◽  
Insulin Sensitivity ◽  
Glucose Metabolism ◽  
Dietary Intervention ◽  
Hepatic Insulin Resistance ◽  
Whole Body ◽  
Primary Study ◽  
Sensitivity Index ◽  
Tissue Specific

Background: It is well-established that the etiology of type 2 diabetes differs between individuals. Insulin resistance (IR) may develop in different tissues, but the severity of IR may differ in key metabolic organs such as the liver and skeletal muscle. Recent evidence suggests that these distinct tissue-specific IR phenotypes may also respond differentially to dietary macronutrient composition with respect to improvements in glucose metabolism.Objective: The main objective of the PERSON study is to investigate the effects of an optimal vs. suboptimal dietary macronutrient intervention according to tissue-specific IR phenotype on glucose metabolism and other health outcomes.Methods: In total, 240 overweight/obese (BMI 25 – 40 kg/m2) men and women (age 40 – 75 years) with either skeletal muscle insulin resistance (MIR) or liver insulin resistance (LIR) will participate in a two-center, randomized, double-blind, parallel, 12-week dietary intervention study. At screening, participants undergo a 7-point oral glucose tolerance test (OGTT) to determine the hepatic insulin resistance index (HIRI) and muscle insulin sensitivity index (MISI), classifying each participant as either “No MIR/LIR,” “MIR,” “LIR,” or “combined MIR/LIR.” Individuals with MIR or LIR are randomized to follow one of two isocaloric diets varying in macronutrient content and quality, that is hypothesized to be either an optimal or suboptimal diet, depending on their tissue-specific IR phenotype (MIR/LIR). Extensive measurements in a controlled laboratory setting as well as phenotyping in daily life are performed before and after the intervention. The primary study outcome is the difference in change in disposition index, which is the product of insulin sensitivity and first-phase insulin secretion, between participants who received their hypothesized optimal or suboptimal diet.Discussion: The PERSON study is one of the first randomized clinical trials in the field of precision nutrition to test effects of a more personalized dietary intervention based on IR phenotype. The results of the PERSON study will contribute knowledge on the effectiveness of targeted nutritional strategies to the emerging field of precision nutrition, and improve our understanding of the complex pathophysiology of whole body and tissue-specific IR.Clinical Trial Registration:https://clinicaltrials.gov/ct2/show/NCT03708419, clinicaltrials.gov as NCT03708419.

scholarly journals Circulating Docosahexaenoic Acid Associates with Insulin-Dependent Skeletal Muscle and Whole Body Glucose Uptake in Older Women Born from Normal Weight Mothers

2017 ◽  
Author(s):  
Robert M. Badeau ◽  
Miikka-Juhani Honka ◽  
Marco Bucci ◽  
Patricia Iozzo ◽  
Johan G. Eriksson ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Skeletal Muscle ◽  
Docosahexaenoic Acid ◽  
Glucose Uptake ◽  
Elderly Women ◽  
Normal Weight ◽  
Whole Body ◽  
Plasma Metabolites ◽  
Tissue Specific ◽  
Insulin Dependent

Background: Obesity among pregnant women is common, and their offspring are predisposed to obesity, insulin resistance, and diabetes. Circulating metabolites that are related to insulin resistance and are associated with this decreased tissue-specific uptake are unknown. Here, we assessed metabolite profiles in elderly women and who were either female offspring from obese mothers (OOM) or offspring of lean mothers (OLM). Metabolic changes were tested for associations with metrics for insulin resistance. Methods: 37 elderly women were separated into an elderly offspring from obese mothers (OOM; n = 17) and elderly offspring from lean/normal weight mothers (OLM; n = 20) groups. We measured plasma metabolites using 1H-NMR and also insulin-dependent tissue specific glucose uptake in skeletal muscle were assessed. Associations were made between metabolites and glucose uptake. Results: Compared to the OLM group, we found that the 22:6 docosahexaenoic acid percentage of the total long chain n-3 fatty acids (DHA/FA) was significantly lower in OOM (P = 0.015). DHA/FA associated significantly to skeletal muscle GU (P = 0.031) and M-value in the OLM group only (P = 0.050). Conclusions: DHA/FA is associated with insulin-dependent skeletal muscle glucose uptake and that this association is significantly weakened in the offspring of obese mothers.

Increased lipid accumulation and insulin resistance in transgenic mice expressing DGAT2 in glycolytic (type II) muscle

2007 ◽  
Vol 293 (6) ◽  
pp. E1772-E1781 ◽  
Author(s):  
Malin C. Levin ◽  
Mara Monetti ◽  
Matthew J. Watt ◽  
Mini P. Sajan ◽  
Robert D. Stevens ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Skeletal Muscle ◽  
Transgenic Mice ◽  
Lipid Accumulation ◽  
Fatty Acyl ◽  
Whole Body ◽  
Lipid Deposition ◽  
Adult Mice ◽  
Insulin Tolerance

Insulin resistance and type 2 diabetes are frequently accompanied by lipid accumulation in skeletal muscle. However, it is unknown whether primary lipid deposition in skeletal muscle is sufficient to cause insulin resistance or whether the type of muscle fiber, oxidative or glycolytic fiber, is an important determinant of lipid-mediated insulin resistance. Here we utilized transgenic mice to test the hypothesis that lipid accumulation specifically in glycolytic muscle promotes insulin resistance. Overexpression of DGAT2, which encodes an acyl-CoA:diacylglycerol acyltransferase that catalyzes triacylglycerol (TG) synthesis, in glycolytic muscle of mice increased the content of TG, ceramides, and unsaturated long-chain fatty acyl-CoAs in young adult mice. This lipid accumulation was accompanied by impaired insulin signaling and insulin-mediated glucose uptake in glycolytic muscle and impaired whole body glucose and insulin tolerance. We conclude that DGAT2-mediated lipid deposition specifically in glycolytic muscle promotes insulin resistance in this tissue and may contribute to the development of diabetes.

scholarly journals One Week of Bed Rest Leads to Substantial Muscle Atrophy and Induces Whole-Body Insulin Resistance in the Absence of Skeletal Muscle Lipid Accumulation

Diabetes ◽  
2016 ◽  
Vol 65 (10) ◽  
pp. 2862-2875 ◽  
Author(s):  
Marlou L. Dirks ◽  
Benjamin T. Wall ◽  
Bas van de Valk ◽  
Tanya M. Holloway ◽  
Graham P. Holloway ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Skeletal Muscle ◽  
Muscle Atrophy ◽  
Lipid Accumulation ◽  
Bed Rest ◽  
Whole Body ◽  
Muscle Lipid ◽  
Skeletal Muscle Lipid

scholarly journals Tissue-specific dysregulation of 11β-hydroxysteroid dehydrogenase type 1 in overweight/obese women with polycystic ovary syndrome compared with weight-matched controls

2014 ◽  
Vol 171 (1) ◽  
pp. 47-57 ◽  
Author(s):  
Alessandra Gambineri ◽  
Flaminia Fanelli ◽  
Federica Tomassoni ◽  
Alessandra Munarini ◽  
Uberto Pagotto ◽  
...  
Keyword(s):  
Polycystic Ovary Syndrome ◽  
Polycystic Ovary ◽  
Hydroxysteroid Dehydrogenase ◽  
Whole Body ◽  
Mrna Levels ◽  
Ovary Syndrome ◽  
Tissue Specific ◽  
Cortisol Metabolism ◽  
Cortisol Metabolites

ContextAbnormal cortisol metabolism in polycystic ovary syndrome (PCOS) has been invoked as a cause of secondary activation of the hypothalamic–pituitary–adrenal axis and hence androgen excess. However, this is based on urinary excretion of cortisol metabolites, which cannot detect tissue-specific changes in metabolism and may be confounded by obesity.ObjectiveTo assess cortisol clearance and whole-body and tissue-specific activities of 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1 (HSD11B1)) in PCOS.DesignCase–control study.SettingMedical center.PatientsA total of 20 overweight–obese unmedicated Caucasian women with PCOS, aged 18–45 years, and 20 Caucasian controls matched for age, BMI, body fat distribution, andHSD11B1genotypes (rs846910 and rs12086634).Main outcome measuresCortisol metabolites were measured in 24 h urine. During steady-state 9,11,12,12-[2H]4-cortisol infusion, cortisol clearance was calculated and whole-body HSD11B1 activity was assessed as the rate of appearance of 9,12,12-2H3-cortisol (d3-cortisol). Hepatic HSD11B1 activity was quantified as the generation of plasma cortisol following an oral dose of cortisone. Subcutaneous adipose HSD11B1 activity andHSD11B1mRNA were measured,ex vivo, in biopsies.ResultsUrinary cortisol metabolite excretion, deuterated cortisol clearance, and the rate of appearance of d3-cortisol did not differ between patients with PCOS and controls. However, hepatic HSD11B1 conversion of oral cortisone to cortisol was impaired (P<0.05), whereas subcutaneous abdominal adipose tissueHSD11B1mRNA levels and activity were increased (P<0.05) in women with PCOS when compared with controls.ConclusionsTissue-specific dysregulation of HSD11B1 is a feature of PCOS, over and above obesity, whereas increased clearance of cortisol may result from obesity rather than PCOS.

scholarly journals Intramyocellular Lipid Accumulation After High-Fat Diet Is Associated with the Gene Expression Involved in Lipid Metabolism in Skeletal Muscle of Non-Obese Men

2016 ◽  
Vol 62 (Suppl.1) ◽  
pp. 144-145
Author(s):  
SAORI KAKEHI ◽  
YOSHIFUMI TAMURA ◽  
KAGEUMI TAKENO ◽  
YUKO SAKURAI ◽  
MINAKO KAWAGUCHI ◽  
...  
Keyword(s):  
Gene Expression ◽  
Skeletal Muscle ◽  
Lipid Metabolism ◽  
Lipid Accumulation ◽  
High Fat Diet ◽  
Intramyocellular Lipid ◽  
High Fat

scholarly journals Hepatokine ERAP1 impairs skeletal muscle insulin sensitivity via ADRB2/PKA pathway

2020 ◽  
Author(s):  
Feifan Guo ◽  
Yuguo Niu ◽  
Haizhou Jiang ◽  
Hanrui Yin ◽  
Fenfen Wang ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Skeletal Muscle ◽  
Insulin Sensitivity ◽  
Neutralizing Antibodies ◽  
Leptin Receptor ◽  
Whole Body ◽  
C2c12 Myotubes ◽  
Insulin Resistant ◽  
Skeletal Muscle Insulin Sensitivity ◽  
Pka Pathway

Abstract The current study aimed to investigate the role of endoplasmic reticulum aminopeptidase 1 (ERAP1), a novel hepatokine, in whole-body glucose metabolism. Here, we found that hepatic ERAP1 levels were increased in insulin-resistant leptin-receptor-mutated (db/db) and high-fat diet (HFD)-fed mice. Consistently, hepatic ERAP1 overexpression attenuated skeletal muscle (SM) insulin sensitivity, whereas knockdown ameliorated SM insulin resistance. Furthermore, serum and hepatic ERAP1 levels were positively correlated, and recombinant mouse ERAP1 or conditioned medium with high ERAP1 content (CM-ERAP1) attenuated insulin signaling in C2C12 myotubes, and CM-ERAP1 or HFD-induced insulin resistance was blocked by ERAP1 neutralizing antibodies. Mechanistically, ERAP1 reduced ADRB2 expression and interrupted ADRB2-dependent signaling in C2C12 myotubes. Finally, ERAP1 inhibition via global knockout or the inhibitor thimerosal improved insulin sensitivity. Together, ERAP1 is a hepatokine that impairs SM and whole-body insulin sensitivity, and its inhibition might provide a therapeutic strategy for diabetes, particularly for those with SM insulin resistance.

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