Abstract
This study investigated the effects of Portulaca oleracea L. extract on glucose uptake in 3T3-L1 adipocytes. P. oleracea extract (POE) markedly enhanced glucose uptake, which was caused by increased GLUT4 expression at the plasma membrane (PM) in 3T3-L1 adipocytes. This increase in PM-GLUT4 expression was associated with insulin receptor substrate-1 (IRS-1) phosphorylation, phosphatidylinositol 3-kinase (PI3K) activation, and Akt phosphorylation, and finally, enhanced intracellular glucose uptake. POE was not associated with protein kinase C (PKC)λ/ζ phosphorylation in the insulin signaling pathway, but did promote 5'-AMP-activated kinase (AMPK) phosphorylation. Increased glucose uptake through POE was inhibited through treating with the PI3K inhibitor or AMPK inhibitor in 3T3-L1 adipocytes. This result suggested that POE may enhance glucose uptake by stimulating GLUT4 translocation to the PM through activating the PI3K and AMPK pathway in 3T3-L1 adipocytes.
Keywords:
3T3-L1 adipocytes; GLUT4 translocation; Portulaca oleracea; glucose uptake.
MeSH terms
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3T3-L1 Cells
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AMP-Activated Protein Kinases / antagonists & inhibitors
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AMP-Activated Protein Kinases / genetics
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AMP-Activated Protein Kinases / metabolism
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Adipocytes / drug effects
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Androstadienes / pharmacology
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Animals
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Carbohydrate Metabolism / drug effects*
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Cell Membrane / drug effects*
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Cell Membrane / metabolism
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Glucose / metabolism*
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Glucose Transporter Type 4 / genetics
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Glucose Transporter Type 4 / metabolism*
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Insulin Receptor Substrate Proteins / genetics
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Insulin Receptor Substrate Proteins / metabolism
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Isoenzymes / genetics
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Isoenzymes / metabolism
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Mice
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Phosphatidylinositol 3-Kinases / genetics
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Phosphatidylinositol 3-Kinases / metabolism
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Phosphoinositide-3 Kinase Inhibitors
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Phosphorylation
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Plant Extracts / pharmacology*
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Portulaca / chemistry*
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Protein Kinase C / genetics
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Protein Kinase C / metabolism
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Proto-Oncogene Proteins c-akt / genetics
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Proto-Oncogene Proteins c-akt / metabolism
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Signal Transduction
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Wortmannin
Substances
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Androstadienes
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Glucose Transporter Type 4
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Insulin Receptor Substrate Proteins
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Irs1 protein, mouse
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Isoenzymes
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Phosphoinositide-3 Kinase Inhibitors
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Plant Extracts
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Slc2a4 protein, mouse
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Proto-Oncogene Proteins c-akt
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protein kinase C zeta
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Protein Kinase C
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protein kinase C lambda
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AMP-Activated Protein Kinases
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Glucose
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Wortmannin