Interaction of baicalin with berberine for glucose uptake in 3T3-L1 adipocytes and HepG2 hepatocytes

Baicalin and berberine are important coexisting constituents of the combination of Radix Scutellariae and Rhizoma Coptidis, known as scutellaria–coptis herb couple (SC), which has heat clearing and detoxifying effects. The aims of the present study were to investigate the effects of the combination of baicalin+berberine on glucose uptake in 3T3-L1 adipocytes or HepG2 cells.Insulin-resistant adipocytes and hepatocytes models were established. Glucose consumption was assayed to evaluate the effects of berberine, baicalin, and berberine+baicalin on glucose uptake, and the interaction of baicalin with berberine for glucose uptake was evaluated in 3T3-L1 adipocytes or HepG2 cells. Moreover, the effects of baicalin on the dose–effect relationship of berberine for glucose uptake was also evaluated in 3T3-L1 adipocytes.The results of the present study demonstrated that berberine increased glucose consumption in 3T3-L1 adipocytes and HepG2 hepatocytes in a dose-dependent manner. In contrast, statistical analyses indicated that baicalin (in doses up to 100μmol/L) produced no obvious effect. The effect of berberine+baicalin on glucose uptake was better than that of berberine or baicalin alone, which indicated that berberine and baicalin had the trend of synergetic effect on glucose uptake. Furthermore, these results showed that the synergistic effect occurred in a specific dose range, while the antagonistic effect was present in another dose range in the presence of 10μmol/L baicalin. Interestingly, the entire dose–response curves of berberine shifted down in the presence of 100μmol/L baicalin, and baicalin antagonised the effect of berberine on glucose uptake in 3T3-L1 adipocytes.The results of the present study showed that berberine dose-dependently increased glucose consumption in 3T3-L1 adipocytes and HepG2 hepatocytes. Furthermore, interaction of baicalin with berberine was additive at low doses of baicalin and antagonistic at higher baicalin doses. Thus, it is possible that baicalin is a partial agonist. These results provided a basis for the study of the TCM compatibility mechanism and a new insight into the application for Gegen Qinlian Decoction (GGQLD) or SC in the clinic.