Stimulatory effect of puerarin on alpha1A-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 C 2 C 12 cells using glucose uptake as indicator. Puerarin enhanced the uptake of radioactive glucose into C 2 C 12 cells in a concentration-dependent manner, which was abolished by prazosin pretreatment. Activation of alpha 1 -adrenoceptors by puerarin was further indicated by the displacement of [ 3H]prazosin binding in C 2 C 12 cells. The stimulatory action of puerarin on glucose uptake was also reduced in C 2 C 12 cells pre-incubated with the antagonists, both WB 4101 and RS 17 056, at concentrations sufficient to block alpha 1A -adrenoceptor (alpha 1A -AR). An activation of alpha 1A -AR seems responsible for the action of puerarin in C 2 C 12 cells. Pharmacological inhibition of phospholipase C (PLC) by U73312 resulted a concentration-dependent decrease of puerarin-stimulated glucose uptake in C 2 C 12 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 alpha 1A -AR by puerarin in C 2 C 12 cells may increase the glucose uptake via the PLC-PKC pathway.