Role of the water extract from Coccinia indica stem on the stimulation of glucose transport in L8 myotubes

Abstract Purintrapiban, J., Keawpradub, N. and Jansakul, C. Role of the water extract from Coccinia indica stem on the stimulation ofglucose transport in L8 myotubes Songklanakarin J. Sci. Technol., 2006, 28(6) : 1199-1208 Hypoglycemic effect of Coccinia indica used for treatment of diabetes in traditional remedies hasknown to relate with increased transport of glucose into peripheral tissues. However, the cellular mechanismsfor this effect remain unclear. This present study reports that the water extract (WE) of C. indica stemexhibited a dose-dependent induction of 2-deoxyglucose (2-DG) uptake in rat L8 myotubes. Maximal uptakewas observed with approximately 3-fold increase in 2-DG transport in 16 h treatment compared with thecontrol. Effect of WE was stronger than that of 1 mM metformin. The effects of insulin and WE wereadditive. WE-induced glucose uptake was significantly inhibited by cycloheximide and partially reversedby SB203580. GLUT1 protein was markedly increased in response to WE. Conversely, WE had no effect onGLUT4 protein level. Redistribution of GLUT4 to the plasma membrane was demonstrated. Triterpenoidsand carbohydrates were detected in WE. In conclusion, new GLUT1 protein synthesis is necessary for WE-stimulated glucose transport while p38-MAPK-dependent activation of transporter intrinsic activity partlycontributes to WE action. These results may explain and support the use of