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 α_1A-adrenoceptor (α_1A-AR). An activation of α_1A-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 α_1A-AR by puerarin in C₂C₁₂ cells may increase the glucose uptake via the PLC-PKC pathway.