Portulaca oleracea L. Extract Enhances Glucose Uptake by Stimulating GLUT4 Translocation to the Plasma Membrane in 3T3-L1 Adipocytes.

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.