Figure 3. Piperine stimulates glucose uptake through AMPK.

(A) C2C12 cells were treated for 3 h with various concentrations of piperine or (B) with 30 μM piperine for the duration of time indicated. Cells were then lysed, and AMPKα phosphorylation was quantified by Western blot using antibodies specific to the phosphorylated protein. The levels of total AMPKα and β-actin were also measured as controls for protein loading. (C) L6 myotubes were differentiated for 7 days and treated with 30 μM piperine for 18 h before 2-deoxy-d[H³]-glucose (2-DG) uptake was measured. (D) Differentiated L6 myotubes were treated with 30 μM piperine for 18 h in either the presence or absence of compound C (5 μM). *P < 0.05, **P < 0.01 compared with the untreated cells. Results from three independently replicated experiments. Blots were displayed in cropped format. Cropped images of full-length blots are shown.