脂肪酸诱导的3T3-L1脂肪细胞胰岛素抵抗的研究

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

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15min(P<0.05)-1h(P<0.01),葡萄糖转运呈升高的趋势,至6h(P>0.05)逐渐下调;胰岛素浓度升高至50nmol/L时,葡萄糖转运增加336%(P<0.01),100nmol/L时达最高峰,是基础状态的492%(P<0.01)。0.125mmol/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0.5mmol/L和1.0mmol/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,100nmol/L胰岛素刺激1h,葡萄糖转运率最高。1mmol/L油酸或棕榈酸作用16-18h可显著诱导3T3-L1脂肪细胞胰岛素抵抗的发生。

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 [ ^3 H ] 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 - LI 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 - LI preadipocytes or adipocytes, both 1 mmol/L oleate and palmitate induce insulin resistance.