中文摘要：

目的探讨在炎症情况下,瘦素（leptin）对胰岛β细胞胰岛素合成与葡萄糖刺激的胰岛素分泌（glucose-stimulated insulin secretion,GSIS）功能的影响。方法在含5.5 mmol/L葡萄糖培养基中培养传代的大鼠胰腺癌细胞系（INS-1E）和大鼠原代分离的胰岛,经生理浓度leptin（0.5 nmol/L）或TNF-α（2 ng/ml）及高浓度leptin（10 nmol/L）与TNF-α（20 ng/ml）单独及联合处理48 h后,在基础葡萄糖（3.3 mmol/L）或高糖（16.7 mmol/L）中分别刺激1 h,放免法检测葡萄糖刺激的GSIS功能;用RT-PCR方法检测胰岛素原（proinsulin）mRNA表达水平,同时细胞经超声破胞后检测胞内胰岛素含量。结果高浓度leptin（10 nmol/L）或TNF-α（20 ng/ml）单独刺激组与对照组以及低浓度leptin或TNF-α组相比,均可显著性抑制INS-1E细胞和原代胰岛的GSIS功能（P〈0.05）,与之相应的是细胞内proinsulin mRNA水平以及胞内胰岛素含量亦显著降低（P〈0.01）;但TNF-α＋leptin联合刺激组中,胰岛素原mRNA水平及胰岛素蛋白含量均较leptin单独刺激并未进一步降低,反而有显著升高（P〈0.05）,提示TNF-α具有拮抗leptin抑制胰岛素基因表达和分泌的作用。结论 TNF-α可以干扰leptin对胰岛β细胞胰岛素合成和分泌的抑制作用。提示肥胖者体内升高的TNF-α可能通过拮抗leptin对胰岛素分泌的抑制作用,在肥胖伴随的高胰岛素血症的发生及葡萄糖代谢紊乱中具有重要作用。

英文摘要：

Objective To study the influence of leptin on pancreatic β cell insulin synthesis and glucose-stimulated insulin secretion（GSIS） in inflammation.Methods INS-1E rat insulinoma cells and freshly isolated rat pancreatic islets cultured in glucose（5.5 mmol/L）-containing media were treated with leptin（0.5 nmol/L or 10 nmol/L）,TNF-α（2 ng/ml or 20 ng/ml）,or their combination（leptin 10 nmol/L and TNF-α 20 ng/ml） for 48 h.Then,the cells and islets were balanced with low-concentration glucose（3.3 mmol/L） for 1 h to test the base level of insulin secretion,and subsequently stimulated with high-concentration glucose（16.7 mmol/L） for 1 h to test GSIS by radioimmunoassay.The expression of proinsulin mRNA was determined by RT-PCR.Intracellular insulin contents were detected after ultrasonic cell disruption.Results High-concentration leptin（10 nmol/L） or TNF-α（20 ng/ml） significantly suppressed GSIS（P0.05） and reduced the intracellular proinsulin mRNA level and insulin content（P0.01） in INS-1E cells and pancreatic β cells.However,low-concentration leptin（0.5 nmol/L） or TNF-α（2 ng/ml） did not show such activities.Additionally,when the cultured INS-1E cells or islets were treated with high-concentration leptin（10 nmol/L） plus TNF-α（20 ng/ml）,the intracellular proinsulin mRNA level and insulin content were not further decreased but significantly increased as compared with the results after high-concentration leptin（10 nmol/L） treatment（P0.05）,indicating that TNF-α may antagonize the inhibition effect of leptin on insulin synthesis and secretion.Conclusion TNF-α can interfere with leptin-mediated inhibition of insulin synthesis and secretion in pancreatic β cells,and TNF-α level increase may contribute to the genesis of hyperinsulinemia and glucose metabolism disorder in people with obesity.