高游离脂肪酸血症通过氧化应激导致胰岛β细胞功能受损

目的 研究高游离脂肪酸(FFA)血症对胰岛β细胞功能的影响.方法 正常雄性SD大鼠随机分为3组:对照组输注生理盐水,FFA组输注脂肪乳,氮乙酰半胱氨酸(NAC)干预组在输注脂肪乳的同时加用NAC.持续输液2～4天,行静脉葡萄糖耐最试验(IVGTY)和胰腺组织表面灌注试验评价在体及离体情况下胰岛β细胞胰岛素分泌功能.结果 胰腺组织表面灌注结果显示,FFA组脂肪乳输注2天,基础状态下的胰岛素分泌较对照组增加(55.5±19.4 vs 27.4±6.7)mIU/L,P<0.01],而葡萄糖刺激的胰岛素分泌(GSIS)与对照组并无差别;延长脂肪乳输注到4天,高FFA刺激基础胰岛素分泌的作用消失,且GSIS明显抑制(46.8±33.0 vs 214.7±27.4)mIU/L,P<0.05].IVG3T结果亦显示脂肪乳输注4天后胰岛素分泌功能受到抑制.但在脂肪乳输注的同时加用抗氧化剂NAC可使β细胞GSIS峰值部分恢复(165.4±14.8)mIU/L,P<0.01].结论 循环中FFA水平增高可能通过激活氧化应激导致胰岛β细胞功能受损.

Elevated circulating free fatty acids level causes pancreatic islet β-cell dysfunction via oxidative stress

Objective To evaluate the effects of elevated circulating free fatty acids (FFA) level on basal and glucose stimulated insulin secretion (GSIS) of islet β-cell and to explore the pathophysiological link between FFA and impaired β-cell dysfunction. Methods Male SD rats underwent infusions with normal saline (C group), intralipid+heparin (FFA group) and N-acetylcysteine+FFA (NAC group) for 2-4 days. Insulin secretion from pancreatic tissues was evaluated during intravenous glucose tolerance test and isolated pancreas perfasion test at the end of 2 and 4 days infusion. Results After 2 days infusion, the basal insulin secretion from isolated perfused pancreas was increased in FFA group (55.5±19.4 vs 27.4±6.7) mU/L, P<0.01], but the response to 16.7 mmol/L glucose in isolated perfased pancreas was similar in FFA and C groups. The peak value during GSIS was inhibited by 4 days FFA infusion (46.8±33.0 vs 214.7±27.4)mIU/L,P<0.05]. GSIS was also decreased in FFA group compared with C group in IVGTr. After interfered with NAC, GSIS was partly recovered (165.4± 14.8)mIU/L, P<0.01]. Conclusion Elevated circulating FFA levels may contribute to the abnormality of pancreatic islet β-cell through oxidative stress.