Original Article | 2006, Vol.28, No.6, pp. 1199-1208
Role of the water extract from Coccinia indica stem on the stimulation of glucose transport in L8 myotubes
Niwat Keawpradub, Chaweewan Jansakul and Juntipa Purintrapiban
pp. 1199 - 1208
Abstract
Hypoglycemic effect of Coccinia indica used for treatment of diabetes in traditional remedies has known to relate with increased transport of glucose into peripheral tissues. However, the cellular mechanisms for this effect remain unclear. This present study reports that the water extract (WE) of C. indica stem exhibited a dose-dependent induction of 2-deoxyglucose (2-DG) uptake in rat L8 myotubes. Maximal uptake was observed with approximately 3-fold increase in 2-DG transport in 16 h treatment compared with the control. Effect of WE was stronger than that of 1 mM metformin. The effects of insulin and WE were additive. WE-induced glucose uptake was significantly inhibited by cycloheximide and partially reversed by SB203580. GLUT1 protein was markedly increased in response to WE. Conversely, WE had no effect on GLUT4 protein level. Redistribution of GLUT4 to the plasma membrane was demonstrated. Triterpenoids and carbohydrates were detected in WE. In conclusion, new GLUT1 protein synthesis is necessary for WEstimulated glucose transport while p38-MAPK-dependent activation of transporter intrinsic activity partly contributes to WE action. These results may explain and support the use of C. indica for the prevention and treatment of diabetes.
