Curcumin ameliorates insulin resistance via enhancing GLUT4 translocation in skeletal muscle in streptozocin-induced diabetic rats / 中华内分泌代谢杂志

ABSTRACT

Objective:To investigate the effects and mechanisms of curcumin on insulin resistance in streptozocin-induced diabetic rats.Methods:Diabetic rats were induced by intraperitoneal injection of STZ, then all the rats were randomly divided into diabetes (DM), diabetes+ curcumin (DM+ Cur), and diabetes + buffer control (DM+ NC) groups. Normal SD rats were used as control group (NC). The DM+ Cur group was treated with curcumin, while the DM+ NC group was treated with equal-volume buffer. The test lasted 12 weeks. The blood glucose was detected, and hyperinsulinemic-euglycemic clamp test was performed to estimate peripheral insulin resistance. At the end of the experiments, rats were killed and the total protein and cell membrane protein were extracted from skeletal muscle. The levels of phosphorylated PI3K, phosphorylated AKT, total PI3K, and total AKT were measured by Western blot. The levels of total GLUT4 and GLUT4 of cell membrane were also detected by Western blot, GLUT4 levels in skeletal muscle cell membranes were detected by immunofluorescence.Results:Blood glucose levels of DM+ Cur group were lower than those of DM group [(18.67±1.99 vs 24.38±2.88) mmol/L, P<0.05], and insulin resistance was also improved[the average GIR(14.69±0.29 vs 10.25±0.30) mg·kg -1·min -1, P<0.01]. The phosphorylation levels of PI3K and AKT were increased, and GLUT4 translocation to the cell membrane was increased. Conclusion:By activating the PI3K/AKT pathway, curcumin promotes GLUT4 translocation, increases skeletal muscle glucose uptake, and finally improves insulin resistance.