游离脂肪酸对大鼠骨骼肌细胞葡萄糖转运蛋白4和胰岛素信号传导蛋白的影响

目的：观察游离脂肪酸对大鼠骨骼肌细胞葡萄糖转运蛋白4（GLUT4）和胰岛素信号传导蛋白Grb2及ERK2的影响。方法：分离、培养新生Sprague-Dawley大鼠骨骼肌细胞，分别与软脂酸（0．25mmol/L)或油酸（0．125mmol/L)孵育12、24、36h，提取蛋白后用Western印迹法检测GLUT4、Grb2和ERK2的蛋白水平；用斑点印迹杂交法检测骨骼肌细胞内GLUT4 RNA含量的变化。结果：经软脂酸和油酸孵育12、24、36h后，大鼠骨骼肌细胞GLUT4的蛋白和RNA水平均显著降低（P＜0．05）；同时，Grb2和ERK2的蛋白水平也明显下降（P＜0．05）。结论：游离脂肪酸可抑制GLUT4的基因及蛋白表达和降低胰岛素信号传导蛋白Grb2和ERK2的蛋白表达水平，这可能会影响胰岛素的信号传导作用和骨骼肌的葡萄糖摄取，引起骨骼肌的胰岛素抑抗。

Effect of free fatty acids on glucose transporter 4 and insulin signaling proteins in rat skeletal muscle cells

Objective To investigate the effect of free fatty acids on glucose transpoter4 (GLUT4) and insulin signaling proteins Grb2 and ERK2 in rat skeletal cells. Methods After the skeletal muscle cells of Sprague Dawley rats were incubated with palmitate (0 25 mmol/L) or oleate (0 125 mmol/L) for 12, 24 and 36 hours, Western blotting was used to assess the levels of GLUT4 and insulin signaling proteins Grb2 and ERK2. The level of GLUT4 RNA was determined by dot blotting. Results The protein and RNA contents of GLUT4 were significantly decreased( P <0.05) and the protein levels of Grb2 and ERK2 were decreased also compared with control in rat skeletal muscle cells after incubated with free fatty acids for 12 , 24 and 36 hours( P <0.05). Conclusion Free fatty acids inhibit glucose metabolism and insulin activity in rat skeletal muscle cells by downregulating the expression of GLUT4 gene and protein and downregulating the protein expression of Grb2 and ERK2.