Stimulatory effect of puerarin on α_1A-adrenoceptor to increase glucose uptake into cultured C₂C₁₂ cells of mice

Effects of puerarin, an active principle contained in the roots of Pueraria lobata (Leguminosae), on the regulation of glucose metabolism in an insulin deficient state were investigated in cultured myoblast C2C12 cells using glucose uptake as indicator. Puerarin enhanced the uptake of radioactive glucose into C2C12 cells in a concentration-dependent manner, which was abolished by prazosin pretreatment. Activation of α1-adrenoceptors by puerarin was further indicated by the displacement of [3H]prazosin binding in C2C12 cells. The stimulatory action of puerarin on glucose uptake was also reduced in C2C12 cells pre-incubated with the antagonists, both WB 4101 and RS 17056, at concentrations sufficient to block α1A-adrenoceptor (α1A-AR). An activation of α1A-AR seems responsible for the action of puerarin in C2C12 cells. Pharmacological inhibition of phospholipase C (PLC) by U73312 resulted a concentration-dependent decrease of puerarin-stimulated glucose uptake in C2C12 cells. This inhibition of glucose uptake by U73122 was specific because the inactive congener, U73343, failed to block puerarin-stimulated glucose uptake. Moreover, both chelerythrine and GF 109203X diminished the action of puerarin at concentration sufficient to inhibit protein kinase C (PKC). The obtained data suggest that an activation of α1A-AR by puerarin in C2C12 cells may increase the glucose uptake via the PLC-PKC pathway.