脂联素影响骨骼肌胰岛素抵抗模型中葡萄糖转运蛋白4表达的研究

目的：通过建立骨骼肌L6细胞胰岛素抵抗模型，探讨骨骼肌L6细胞中脂联素（ APN）的分泌，以及脂联素对骨骼肌胰岛素抵抗模型中葡萄糖转运蛋白4（GLUT4）表达的影响。方法（1）体外培养大鼠L6成肌细胞，诱导分化后，给予不同浓度的棕榈酸（PA），测定不同时间细胞培养上清液葡萄糖浓度，观察PA对L6细胞摄取葡萄糖的影响，建立胰岛素抵抗模型；（2）根据实验条件的不同分为三组：NC组（正常对照组，即骨骼肌L6细胞组）；IR组（胰岛素抵抗模型组）；IR＋PIO组（胰岛素抵抗模型＋吡格列酮组）。应用Western blot方法分别测定上述三组APN和GLUT4表达水平。结果（1）0．4 mmol· L^-1的棕榈酸在作用12、24、36 h以及0．6～0．8 mmol· L^-1棕榈酸作用8～36 h后，细胞培养上清液中葡萄糖含量，明显高于对照组。胰岛素抵抗模型建立；（2）Western blot结果显示：①与NC组比较，IR组APN和GLUT4表达均减少，差异有统计学意义；②与IR组比较，IR＋PIO组其APN和GLUT4表达均增加，差异有统计学意义。结论（1）大鼠L6成肌细胞培养并诱导分化后，经过一定条件下PA刺激，可以建立胰岛素抵抗模型；（2）大鼠L6细胞可分泌和表达脂联素，骨骼肌源性脂联素上调L6细胞GLUT4的表达；（3）吡格列酮作为PPAR-γ激动剂，可增加大鼠L6细胞脂联素的分泌，进而改善胰岛素敏感性。

Adiponectin affects the expression of GLUT4 in skeletal muscle insulin resistance model

Objective To explore the effect of adiponectin on the expression of GLUT 4 in skeletal muscle by establishing the model of insulin resistance in skeletal muscle L6 cells.Methods （1） Rat L6 muscle cells were cultured after induction of differentiation ,different concentrations of palmitic acid （PA）.Glucose concentrations in cell culture supernatant were measured at different time and the effect of PA on glucose uptake in L 6 cells was observed .Insulin resistance model was established;（ 2 ） According to different experimental conditions rats were assigned into three groups：NC group （control group,namely skeletal muscle L6 cell group）,IR group （insulin resistance model group ） ,and IR ＋PIO group （ insulin resistance model ＋pioglitazone group ） .APN and GLUT4 protein expres-sion levels were determined by Western blot in the three groups .Results （1） After use of 0.4 mmol· L^-1 of palmitic acid after 12, 24,36 h and 0.6-0.8 mmol· L^-1 of palmitic acid during 8~36 h,cell culture supernatant glucose levels were significantly higher than that in the insulin resistance model （P〈0.05）;（2） The results of Western blot showed that compared with NC group ,the expression of APN and GLUT4 were reduced in the IR group with a significant difference （P 〈0.05）.Compared with the IR group,the ex-pression of APN and GLUT4 were increased in the IR ＋PIO group with a significant difference（P 〈0.05）.Conclusions （1）L6 muscle cells from rats cultured and induced to differentiate can create insulin resistance model by palmitic acid stimulation in certain conditions;（2）L6 cells from rats can secrete and express adiponectin ,which increases the expression of skeletal Muscle＇s GLUT4;（3） As the PPAR-γagonist,Pioglitazone can increase the secretion of the rat L 6 muscle cells APN,thereby improving insulin sensitivity .