Objective To observe the effect of phytochemicals-epigallocatechin gallate (EGCG) on the expression of glucose transporter, insulin sensitivity and inflammatory factors in SW872 adipocytes with insulin resistance (IR).
Methods The insulin resistance model of SW872 adipocytes was constructed with oleic acid then the adipocytes were treated with EGCG at different doses (25, 50, and 100 μmol/L) for 24 hours. The uptake of 2-deoxy glucose labeled glucose of the adipocytes was detected with confocal laser scanning microscopy. The expression of glucose transporter type 4 (GLUT4) protein was determined with Westernblot. The mRNA expressions of tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and C-reactive protein (CRP) were detected with real-time fluorescence quantitative reverse transcription polymerase chain reaction (RT-qPCR) and the expressions of TNF-α, IL-6, and CRP protein were measured with enzyme-linked immunosorbent assay (ELISA).
Results Compared with those of the control cells, the glucose uptake and the expression of GLUT4 protein of the model cells were significantly decreased (both P < 0.05), and the levels of TNF-α, IL-6, CRP mRNA expression were significantly increased (all P < 0.01). The protein secretion of TNF-α (161.3 ± 14.2 pg/mL), IL-6 (121.6 ± 13.6 pg/mL), and CRP (1.82 ± 0.17 pg/mL) in the model cells were also significantly higher than those in the control cells (P < 0.01 for all). In EGCG treated adipocytes, the glucose uptake and GLUT4 protein increased significantly (both P < 0.05), while the mRNA expressions of TNF-α, IL-6, and CRP decreased significantly (P < 0.01 for all) compared with those in the model cells. In the SW872 adipocytes treated with high, moderate, and low dose EGCG, the protein expressions of TNF-α (148.8 ± 13.3, 131.4 ± 11.3, and 119.5 ± 12.1 pg/mL), IL-6 (93.3 ± 10.4, 85.5 ± 14.1, and 73.9 ± 11.3 pg/mL), and CRP (1.74 ± 0.12, 1.53 ± 0.15, and 1.36 ± 0.12 pg/mL) were significantly reduced in a dose dependent manner compared with those in the model cells (P < 0.01 for all).
Conclusion EGCG can promote glucose uptake and enhance insulin sensitivity, thereby improving insulin resistance; the mechanism of the effects may be related to the reduction in inflammatory factor expression.
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