| Glut4 is upregulated despite decreased insulin signaling during prolonged fasting in northern elephant seal pups. | |
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MedLine Citation:
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PMID: 20980624 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Postprandial cellular glucose uptake is dependent on an insulin-signaling cascade in muscle and adipose tissue, resulting in the translocation of the insulin-dependent glucose transporter 4 (Glut4) into the plasma membrane. Additionally, extended food deprivation is characterized by suppressed insulin signaling and decreased Glut4 expression. Northern elephant seals are adapted to prolonged fasts characterized by high levels of plasma glucose. To address the hypothesis that the fasting-induced decrease in insulin is associated with reduced insulin signaling in prolonged fasted seals, we compared the adipose protein levels of the cellular insulin-signaling pathway, Glut4 and plasma glucose, insulin, cortisol, and adiponectin concentrations between Early (n = 9; 2-3 wks postweaning) and Late (n = 8; 6-8 wks postweaning) fasted seals. Plasma adiponectin (230 ± 13 vs. 177 ± 11 ng/ml), insulin (2.7 ± 0.4 vs. 1.0 ± 0.1 μU/ml), and glucose (9.8 ± 0.5 vs. 8.0 ± 0.3 mM) decreased, while cortisol (124 ± 6 vs. 257 ± 30 nM) doubled with fasting. Glut4 increased (31%) with fasting despite the significant decreases in the cellular content of phosphatidylinositol 3-kinase as well as phosphorylated insulin receptor, insulin receptor substrate-1, and Akt2. Increased Glut4 may have contributed to the decrease in plasma glucose, but the decrease in insulin and insulin signaling suggests that Glut4 is not insulin-dependent in adipose tissue during prolonged fasting in elephant seals. The reduction of plasma glucose independent of insulin may make these animals an ideal model for the study of insulin resistance. |
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Authors:
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Jose A Viscarra; José Pablo Vázquez-Medina; Daniel E Crocker; Rudy M Ortiz |
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Publication Detail:
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Type: Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't Date: 2010-10-27 |
Journal Detail:
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Title: American journal of physiology. Regulatory, integrative and comparative physiology Volume: 300 ISSN: 1522-1490 ISO Abbreviation: Am. J. Physiol. Regul. Integr. Comp. Physiol. Publication Date: 2011 Jan |
Date Detail:
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Created Date: 2010-12-24 Completed Date: 2011-01-20 Revised Date: 2012-01-02 |
Medline Journal Info:
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Nlm Unique ID: 100901230 Medline TA: Am J Physiol Regul Integr Comp Physiol Country: United States |
Other Details:
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Languages: eng Pagination: R150-4 Citation Subset: IM |
Affiliation:
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University of California, Merced, 95343, USA. jviscarra@ucmerced.edu |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Adiponectin
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blood Adipose Tissue / metabolism Animals Animals, Newborn / metabolism Blood Glucose / metabolism Fasting / metabolism* Glucose Transporter Type 4 / metabolism* Hydrocortisone / blood Insulin / metabolism* Insulin Resistance / physiology Models, Animal Muscle, Skeletal / metabolism Seals, Earless / metabolism* Signal Transduction / physiology* Up-Regulation / physiology* |
| Grant Support | |
ID/Acronym/Agency:
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HL-091767/HL/NHLBI NIH HHS; R01 HL091767-04/HL/NHLBI NIH HHS |
| Chemical | |
Reg. No./Substance:
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0/Adiponectin; 0/Blood Glucose; 0/Glucose Transporter Type 4; 0/Insulin; 50-23-7/Hydrocortisone |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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