脂肪酸诱导的3T3-L1脂肪细胞胰岛素抵抗的研究

目的: 观察不同种类、不同浓度脂肪酸对3T3-L1脂肪细胞葡萄糖转运的影响，探讨高脂负荷在胰岛素抵抗形成中的意义，并建立最佳的脂肪酸诱导胰岛素抵抗产生的细胞模型。方法: 以3T3-L1前脂肪细胞和诱导分化成熟的3T3-L1脂肪细胞为研究对象，利用2-脱氧-［³H］-D-葡萄糖掺入法，观察最大葡萄糖摄取率时最佳胰岛素作用浓度和时间；在此基础上研究不同浓度油酸（C18:1）、棕榈酸(C16:0)对前脂肪细胞和脂肪细胞摄取葡萄糖的影响。结果:胰岛素刺激15 min（P<0.05）-1 h（P<0.01），葡萄糖转运呈升高的趋势，至6 h（P>0.05）逐渐下调；胰岛素浓度升高至50 nmol/L时，葡萄糖转运增加336%（P<0.01），100 nmol/L时达最高峰，是基础状态的492%（P<0.01）。0.125 mmol/L油酸或棕榈酸均可明显抑制胰岛素刺激状态下的3T3-L1前脂肪细胞葡萄糖转运（P<0.05），并呈浓度依赖性抑制；油酸及棕榈酸浓度分别达0.5 mmol/L和1.0 mmol/L时，分化成熟脂肪细胞葡萄糖转运显著受抑（P<0.05）。结论: 胰岛素刺激下的3T3-L1脂肪细胞葡萄糖转运有一定的时序性和浓度依赖性，100 nmol/L胰岛素刺激1h，葡萄糖转运率最高。1 mmol/L油酸或棕榈酸作用16-18 h可显著诱导3T3-L1脂肪细胞胰岛素抵抗的发生。

Fatty acid-induced insulin resistance in 3T3-L1 adipocytes

AIM: The purpose of the present study was to examine the effect of insulin and different kinds of free fatty acid (FFA) on glucose transport in cultured 3T3-L1 preadipocytes or adipocytes. METHODS: Following the exposure of preadipocytes to insulin at different concentrations and treated times, glucose transport was assessed as [3H]2-deoxy glucose uptake. Furthermore, 3T3-L1 preadipocytes and adipocytes with either the monounsaturated FFA oleate (C18:1) or the saturated FFA palmitate (C16:0)were used and glucose transport was examined as above. RESULTS: Insulin increased specific membrane glucose transport in 3T3-L1 preadipocytes at the time of 15 min to 1 h stimulation. However, after 6 h exposure to insulin, downregulation of glucose transport was observed. Dose response studies demonstrated that 2-DG transport increased by 336% at 50 nmol/L of insulin (P<0.01), reaching a maximal effect at 100 nmol/L insulin (492%, insulin vs control, P<0.01). In 3T3-L1 preadipocytes, insulin resistance was accomplished to 0.125 mmol/L oleate or palmitate (P<0.05, respectively), and the inhibition was in a dose-dependent manner. However, in adipocytes, the inhibition was noted at 0.5 mmol/L oleate or 1.0 mmol/L palmitate. CONCLUSION: Insulin increases glucose transport in 3T3-L1 preadipocytes in a time and concentration-dependent manner. After exposure to 100 nmol/L insulin for 1 h, the 2-DG uptake reaches a maximal effect. In 3T3-L1 preadipocytes or adipocytes, both 1 mmol/L oleate and palmitate induce insulin resistance.