Insulin Action on Lipid Metabolism

2005 ◽  
pp. 87-103
Author(s):  
Keith N. Frayn ◽  
Fredrik Karpe
Keyword(s):  
Lipid Metabolism ◽  
Insulin Action

Long-chain acyl-CoA esters as indicators of lipid metabolism and insulin sensitivity in rat and human muscle

2000 ◽  
Vol 279 (3) ◽  
pp. E554-E560 ◽  
Author(s):  
Bronwyn A. Ellis ◽  
Ann Poynten ◽  
Andrew J. Lowy ◽  
Stuart M. Furler ◽  
Donald J. Chisholm ◽  
...  
Keyword(s):  
Adipose Tissue ◽  
Lipid Metabolism ◽  
Insulin Action ◽  
Human Muscle ◽  
Whole Body ◽  
Cellular Processes ◽  
Lipid Species ◽  
Chain Acyl ◽  
Triglyceride Content ◽  
Long Chain

Long-chain acyl-CoAs (LCACoA) are an activated lipid species that are key metabolites in lipid metabolism; they also have a role in the regulation of other cellular processes. However, few studies have linked LCACoA content in rat and human muscle to changes in nutritional status and insulin action. Fasting rats for 18 h significantly elevated the three major LCACoA species in muscle ( P < 0.001), whereas high-fat feeding of rats with a safflower oil (18:2) diet produced insulin resistance and increased total LCACoA content ( P < 0.0001) by specifically increasing 18:2-CoA. The LCACoA content of red muscle from rats (4–8 nmol/g) was 4- to 10-fold higher than adipose tissue (0.4–0.9 nmol/g, P < 0.001), suggesting that any contamination of muscle samples with adipocytes would contribute little to the LCACoA content of muscle. In humans, the LCACoA content of muscle correlated significantly with a measure of whole body insulin action in 17 male subjects ( r 2 = 0.34, P = 0.01), supporting a link between muscle lipid metabolism and insulin action. These results demonstrate that the LCACoA pool reflects lipid metabolism and nutritional state in muscle. We conclude that the LCACoA content of muscle provides a direct index of intracellular lipid metabolism and its links to insulin action, which, unlike triglyceride content, is not subject to contamination by closely associated adipose tissue.

scholarly journals Intramuscular lipid metabolism, insulin action, and obesity

IUBMB Life ◽  
2009 ◽  
Vol 61 (1) ◽  
pp. 47-55 ◽  
Author(s):  
Leslie A. Consitt ◽  
Jill A. Bell ◽  
Joseph A. Houmard
Keyword(s):  
Lipid Metabolism ◽  
Insulin Action ◽  
Intramuscular Lipid

Leptin, skeletal muscle lipids, and lipid-induced insulin resistance

2007 ◽  
Vol 293 (2) ◽  
pp. R642-R650 ◽  
Author(s):  
John J. Dube ◽  
Bankim A. Bhatt ◽  
Nikolas Dedousis ◽  
Arend Bonen ◽  
Robert M. O'Doherty
Keyword(s):  
Insulin Resistance ◽  
Skeletal Muscle ◽  
Fatty Acid ◽  
Lipid Metabolism ◽  
Insulin Sensitivity ◽  
Insulin Action ◽  
Glycogen Synthase ◽  
Acid Oxidation ◽  
Fatty Acid Binding ◽  
Lipid Metabolites

Leptin-induced increases in insulin sensitivity are well established and may be related to the effects of leptin on lipid metabolism. However, the effects of leptin on the levels of lipid metabolites implicated in pathogenesis of insulin resistance and the effects of leptin on lipid-induced insulin resistance are unknown. The current study addressed in rats the effects of hyperleptinemia (HL) on insulin action and markers of skeletal muscle (SkM) lipid metabolism in the absence or presence of acute hyperlipidemia induced by an infusion of a lipid emulsion. Compared with controls (CONT), HL increased insulin sensitivity, as assessed by hyperinsulinemic-euglycemic clamp (∼15%), and increased SkM Akt (∼30%) and glycogen synthase kinase 3α (∼52%) phosphorylation. These improvements in insulin action were associated with decreased SkM triglycerides (TG; ∼61%), elevated ceramides (∼50%), and similar diacylglycerol (DAG) levels in HL compared with CONT. Acute hyperlipidemia in CONT decreased insulin sensitivity (∼25%) and increased SkM DAG (∼33%) and ceramide (∼60%) levels. However, hyperlipidemia did not induce insulin resistance or SkM DAG and ceramide accumulation in HL. SkM total fatty acid transporter CD36, plasma membrane fatty acid binding protein, acetyl Co-A carboxylase phosphorylation, and fatty acid oxidation were similar in HL compared with CONT. However, HL decreased SkM protein kinase Cθ (PKCθ), a kinase implicated in mediating the detrimental effects of lipids on insulin action. We conclude that increases in insulin sensitivity induced by HL are associated with decreased levels of SkM TG and PKCθ and increased SkM insulin signaling, but not with decreases in other lipid metabolites implicated in altering SkM insulin sensitivity (DAG and ceramide). Furthermore, insulin resistance induced by an acute lipid infusion is prevented by HL.

scholarly journals Rat amylin-(8—37) enhances insulin action and alters lipid metabolism in normal and insulin-resistant rats

1997 ◽  
Vol 273 (5) ◽  
pp. E859-E867 ◽  
Author(s):  
M. Hettiarachchi ◽  
S. Chalkley ◽  
S. M. Furler ◽  
Y.-S. Choong ◽  
M. Heller ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Lipid Metabolism ◽  
Insulin Sensitivity ◽  
Insulin Action ◽  
Glycogen Synthesis ◽  
Human Growth ◽  
Whole Body ◽  
Nonesterified Fatty Acids ◽  
Insulin Resistant

To clarify roles of amylin, we investigated metabolic responses to rat amylin-(8—37), a specific amylin antagonist, in normal and insulin-resistant, human growth hormone (hGH)-infused rats. Fasting conscious rats were infused with saline or hGH, each with and without amylin-(8—37) (0.125 μmol/h), over 5.75 h. At 3.75 h, a hyperinsulinemic (100 mU/l) clamp with bolus 2-deoxy-d-[3H]glucose and [14C]glucose was started. hGH infusion led to prompt (2- to 3-fold) basal hyperamylinemia ( P < 0.02) and hyperinsulinemia. Amylin-(8—37) reduced plasma insulin ( P < 0.001) and enhanced several measures of whole body and muscle insulin sensitivity ( P < 0.05) in both saline- and hGH-infused rats. Amylin-(8—37) corrected hGH-induced liver insulin resistance, increased basal plasma triglycerides and lowered plasma nonesterified fatty acids in both groups, and reduced muscle triglyceride and total long-chain acyl-CoA content in saline-treated rats ( P < 0.05). In isolated soleus muscle, amylin-(8—37) blocked amylin-induced inhibition of glycogen synthesis but had no effect in the absence of amylin. Thus 1) hyperamylinemia accompanies insulin resistance induced by hGH infusion; 2) amylin-(8—37) increases whole body and muscle insulin sensitivity and consistently reduces basal insulin levels in normal and hGH-induced insulin-resistant rats; and 3) amylin-(8—37) elicits a significant alteration of in vivo lipid metabolism. These findings support a role of amylin in modulating insulin action and suggest that this could be mediated by effects on lipid metabolism.

scholarly journals Altered Intramuscular Lipid Metabolism Relates to Diminished Insulin Action in Men, but Not Women, in Progression to Diabetes

Obesity ◽  
2010 ◽  
Vol 18 (11) ◽  
pp. 2093-2100 ◽  
Author(s):  
Leigh Perreault ◽  
Bryan C. Bergman ◽  
Devon M. Hunerdosse ◽  
Robert H. Eckel
Keyword(s):  
Lipid Metabolism ◽  
Insulin Action ◽  
Intramuscular Lipid

The forkhead box O family in insulin action and lipid metabolism

2020 ◽  
pp. 247-272
Author(s):  
Sojin Lee ◽  
Cuiling Zhu ◽  
Jun Yamauchi ◽  
Ping Zhu ◽  
Xiaoyun Feng ◽  
...  
Keyword(s):  
Lipid Metabolism ◽  
Insulin Action ◽  
Forkhead Box

Weight Loss and Exercise: Implications for Muscle Lipid Metabolism and Insulin Action

2004 ◽  
Vol 36 (7) ◽  
pp. 1191-1195 ◽  
Author(s):  
JASON R. BERGGREN ◽  
MATTHEW W. HULVER ◽  
G. LYNIS DOHM ◽  
JOSEPH A. HOUMARD
Keyword(s):  
Weight Loss ◽  
Lipid Metabolism ◽  
Insulin Action ◽  
Muscle Lipid

scholarly journals Ectopic fat accumulation in human astrocytes impairs insulin action

2020 ◽  
Vol 7 (9) ◽  
pp. 200701
Author(s):  
Martin Heni ◽  
Sabine S. Eckstein ◽  
Jens Schittenhelm ◽  
Anja Böhm ◽  
Norbert Hogrefe ◽  
...  
Keyword(s):  
Gene Expression ◽  
Insulin Resistance ◽  
Lipid Metabolism ◽  
Gene Expression Profile ◽  
Expression Profile ◽  
Insulin Action ◽  
Glycogen Synthesis ◽  
Lipid Storage ◽  
Human Astrocytes ◽  
Ectopic Lipid Storage

Astrocytes provide neurons with structural support and energy in form of lactate, modulate synaptic transmission, are insulin sensitive and act as gatekeeper for water, ions, glutamate and second messengers. Furthermore, astrocytes are important for glucose sensing, possess neuroendocrine functions and also play an important role in cerebral lipid metabolism. To answer the question, if there is a connection between lipid metabolism and insulin action in human astrocytes, we investigated if storage of ectopic lipids in human astrocytes has an impact on insulin signalling in those cells. Human astrocytes were cultured in the presence of a lipid emulsion, consisting of fatty acids and triglycerides, to induce ectopic lipid storage. After several days, cells were stimulated with insulin and gene expression profiling was performed. In addition, phosphorylation of Akt as well as glycogen synthesis and cell proliferation was assessed. Ectopic lipid storage was detected in human astrocytes after lipid exposure and lipid storage was persistent even when the fat emulsion was removed from the cell culture medium. Chronic exposure to lipids induced profound changes in the gene expression profile, whereby some genes showed a reversible gene expression profile upon removal of fat, and some did not. This included FOXO-dependent expression patterns. Furthermore, insulin-induced phosphorylation of Akt was diminished and also insulin-induced glycogen synthesis and proliferation was impaired in lipid-laden astrocytes. Chronic lipid exposure induces lipid storage in human astrocytes accompanied by insulin resistance. Analyses of the gene expression pattern indicated the potential of a partially reversible gene expression profile. Targeting astrocytic insulin resistance by reducing ectopic lipid load might represent a promising treatment target for insulin resistance of the brain in obesity, diabetes and neurodegeneration.

Sites of Insulin Action Using Ferritin Labeling

1971 ◽  
Vol 29 ◽  
pp. 540-541
Author(s):  
Burton B. Silver ◽  
Ronald S. Nelson
Keyword(s):  
Electron Microscopy ◽  
Binding Sites ◽  
Anterior Pituitary ◽  
Insulin Action ◽  
Diabetic Rats ◽  
Insulin Antibody ◽  
Fat Pad ◽  
Target Organs ◽  
Uranium Salts ◽  
Sugar Levels

Some investigators feel that insulin does not enter cells but exerts its influence in some manner on the cell surface. Ferritin labeling of insulin and insulin antibody was used to determine if binding sites of insulin to specific target organs could be seen with electron microscopy.Alloxanized rats were considered diabetic if blood sugar levels were in excess of 300 mg %. Test reagents included ferritin, ferritin labeled insulin, and ferritin labeled insulin antibody. Target organs examined were were diaphragm, kidney, gastrocnemius, fat pad, liver and anterior pituitary. Reagents were administered through the left common carotid. Survival time was at least one hour in test animals. Tissue incubation studies were also done in normal as well as diabetic rats. Specimens were fixed in gluteraldehyde and osmium followed by staining with lead and uranium salts. Some tissues were not stained.

A Cytochemical Study of Glucose-6-Phosphatase (G-6-PASE) in Cells Participating in Atherogenesis of Rabbit Aorta

1975 ◽  
Vol 33 ◽  
pp. 460-461
Author(s):  
Sidney D. Kobernick ◽  
Edna A. Elfont ◽  
Neddra L. Brooks
Keyword(s):  
Lipid Metabolism ◽  
New Zealand ◽  
Aortic Wall ◽  
Rabbit Aorta ◽  
Plaque Formation ◽  
Metabolic Changes ◽  
Atherosclerotic Plaques ◽  
Cytochemical Study ◽  
Cellular Alteration ◽  
New Zealand White Rabbits

This cytochemical study was designed to investigate early metabolic changes in the aortic wall that might lead to or accompany development of atherosclerotic plaques in rabbits. The hypothesis that the primary cellular alteration leading to plaque formation might be due to changes in either carbohydrate or lipid metabolism led to histochemical studies that showed elevation of G-6-Pase in atherosclerotic plaques of rabbit aorta. This observation initiated the present investigation to determine how early in plaque formation and in which cells this change could be observed.Male New Zealand white rabbits of approximately 2000 kg consumed normal diets or diets containing 0.25 or 1.0 gm of cholesterol per day for 10, 50 and 90 days. Aortas were injected jin situ with glutaraldehyde fixative and dissected out. The plaques were identified, isolated, minced and fixed for not more than 10 minutes. Incubation and postfixation proceeded as described by Leskes and co-workers.

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