Curcumin increases insulin sensitivity in C2C12 muscle cells via AKT and AMPK signaling pathways

Background: Diabetes is an enduring condition that causes impaired, peripheral insulin resistance. Curcumin was shown to exert notable anti-diabetic effects, which might be possible by overexpression of certain glucose transporter genes and glycoprotein content within the cells. Objectives: To investigate the effect of curcumin alone and in concomitant with insulin on glucose translocation from intracellular compartments of nuclear or endoplasmic reticulum membranes into the cytoplasmic membrane (CM) and key kinases involved in insulin signaling pathways. Materials and Methods: C2C12 myoblast cells were cultured and differentiated to the myotubes. Later, the cells were treated with curcumin alone or a combination of curcumin and insulin, so their viability was measured by MTT assay. The expression level of GLUT 4 gene was examined by Real Time-reverse Transcription Polymerase Chain Reaction (qRT-PCR). To evaluate the activity of curcumin and curcumin/insulin synergistic effect on stimulated GLUT4 translocation, kinases AKT, P-AKT, AMP-activated protein kinase (AMPK) and P-AMPK were assessed and detected via Western Blotting (WB). Results: Curcumin significantly induced GLUT 4 expression and its translocation from intra-cell space into the cell surface and showed a synergic effect on GLUT 4 translocation in presence of insulin. This synergistic effect was inhibited by the insulin receptor inhibitor AG1024 and the inhibitor of AMPK signaling, compound C. Conclusion: Curcumin demonstrated a synergistic effect with insulin and could be a choice of type 2 diabetes mellitus (T2DM) treatment, which may be affected by both AKT and AMPK signaling pathways, hereby facilitates glucose uptake into the cells.