In vivo effects of dexamethasone and sucrose on glucose transport (GLUT-4) protein tissue distribution.
Tissue-specific changes in GLUT-4 were compared in the following three different rat models by inducing varying degrees of hyperinsulinemia with or without hyperglycemia and hypertriglyceridemia: 1) sucrose feeding (Suc), 2) subcutaneous dexamethasone administration (Dex), and 3) a combination of both treatments (Dex/Suc). Suc raised circulatory insulin and triglyceride levels without affecting plasma glucose, whereas both Dex and Dex/Suc induced significant hyperinsulinemia, hyperglycemia, and hypertriglyceridemia. In adipocytes and skeletal muscle, Suc feeding was not associated with any change in total cellular GLUT-4 levels. However, Suc induced a sevenfold increase in fat cell plasma membrane GLUT-4 levels in the basal state and inhibited GLUT-4 translocation in response to insulin. Administration of Dex or Dex/Suc diminished GLUT-4 expression in fat cells, increased it in skeletal muscle, but did not induce any change in heart. Similar to Suc feeding, Dex and Dex/Suc also increased the amount of GLUT-4 detected at the plasma membrane of adipocytes in the basal state and inhibited GLUT-4 translocation in response to insulin. These results emphasize the specific regulation of GLUT-4 in insulin-sensitive tissues.
Department of Biochemistry, Boston University School of Medicine, Massachusetts 02118, USA.
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Coderre
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Vallega
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Pilch
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Chipkin
D000273:Adipose Tissue / Q000378:metabolism; D000818:Animals; D015153:Blotting, Western; D001835:Body Weight / Q000187:drug effects; D003907:Dexamethasone / Q000494:pharmacology*; D005947:Glucose / Q000378:metabolism*; D051275:Glucose Transporter Type 4; D006943:Hyperglycemia / Q000378:metabolism; D006946:Hyperinsulinism / Q000378:metabolism; D007333:Insulin Resistance; D008297:Male; D009004:Monosaccharide Transport Proteins / Q000378:metabolism*; D009124:Muscle Proteins; D018482:Muscle, Skeletal / Q000378:metabolism; D009206:Myocardium / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D013395:Sucrose / Q000494:pharmacology*; D014018:Tissue Distribution
D051275:Glucose Transporter Type 4; D009004:Monosaccharide Transport Proteins; D009124:Muscle Proteins; C495694:Slc2a4 protein, rat; D013395:Sucrose; D003907:Dexamethasone; D005947:Glucose