摘要目的 研究胃旁路手术对非肥胖2型糖尿病大鼠胰岛β细胞凋亡的影响及其机制.方法 将72只8周龄的GK大鼠随机分为手术组(O组,18只)、假手术组(S组,18只)、饮食控制组(F组,18只)和对照组(C组,18只),术前和术后1、2、4、8周检测比较空腹、餐后血糖、胰岛素和胰高血糖素样肽-1(GLP-1)水平.术后2、4、8周取血测餐后血糖后,分批随机处死大鼠,每批每组处死6只,大鼠处死后分离胰腺并取出待用.原位末端标记法检测胰岛β细胞凋亡;免疫组化方法检测凋亡相关蛋白Bcl-2、Bax的表达.结果 O组术后第4周空腹血糖由术前的(16.2 ±0.8)mmol/L下降到(9.2±0.6)mmol/L,术后第8周血糖为(9.7±0.7)mmoL/L;术后第4周餐后血糖由术前的(31.1±1.1)mmoi/L降至(13.1±0.7)mmol/L,术后第8周为(12.3 ±0.7)mmol/L;术后第4周空腹血清胰岛素水平由术前的(28.0±1.2)mU/L升至(62.8±1.9)mU/L,术后第8周为(61.7±1.4)mU/L,术后第4、8周餐后血清胰岛素水平分别为(77.4±1.1)mU/L、(77.1±1.0)mU/L;术后第2周空腹GLP-1由术前的(10.7±1.0)pmol/L升至(13.5±0.8)pmol/L,至术后第4、8周分别为(26.1±0.9)pmol/L、(25.3±1.2)pmol/L;O组各测量值术后各时相点与术前比较差异均有统计学意义(P＜0.05),与其他组比较差异亦有统计学意义(P＜0.05).O组大鼠胰岛细胞凋亡率术后4周下降至(5.9 ±0.7)%,术后8周凋亡率为(6.3±1.1)%,差异有统计学意义(P＜0.05).O组Bcl-2蛋白表达术后2、4、8周表达量分别为31.3±1.5、35.7±1.0和35.8 ±0.8,明显高于同时间点的其他3组,差异有统计学意义(P＜0.05);Bax蛋白术后2、4、8周表达量分别为13.3±0.9、10.8 ±0.9和10.9±1.1,明显低于相同时间点的其他3组,差异有统计学意义(P＜0.05).结论 胃旁路手术可显著降低糖尿病大鼠血糖,促进GLP-1分泌,从而调节Bcl-2通路,显著抑制胰岛β细胞凋亡,保护胰岛B细胞.

abstractsObjective To investigate the effects of Gastric bypass surgery on the apoptosis of islet β-cells in type 2 nonobese diabetic (NOD)rats and its mechanisms. Methods Seventy-two 8-week-old GK rats were randomly divided into four groups: operation group (group O, n = 18), sham operation group (group S, n=18), diet control group (group F, n=18) and control group (group C, n=18). The levels of fasting, postprandial blood glucose, insulin and glucagon-like peptide-1 (GLP-1) were measured and compared among the 4 groups before the operation and at 1,2, 4 and 8 weeks following the operation. The blood samples were collected at 2,4 and 8 weeks after the operation for the measurement of postprandial blood glucose, and then the rats in batches(6 rats in each group)were decapitated to retrieve the pancreas.The apoptosis of the islet β-cells was detected by using TUNEL assay, and the expression of apoptosisrelated proteins Bcl-2, Bax was measured with immunohistochemistry. Results As for group O, the fasting blood glucose level decreased from ( 16. 2 ±0. 8) mmol/L before the operation to respectively (9. 2 ±0. 6)mmol/L and (9.7 ±0. 7 ) mmol/L at 4 and 8 weeks after the operation; postprandial blood glucose decreased from ( 31.1 ± 1.1 ) mmol/L before the operation to respectively ( 13. 1 ± 0. 7 ) mmol/L and ( 12. 3 ±0. 7) mmol/L at 4 and 8 weeks after the operation. Fasting insulin level increased from (28. 0 ±1.2) mU/L before the operation to respectively (62. 8 ± 1.9) mU/L and (61.7 ± 1.4) mU/L at 4 and 8 weeks after the operation; and at 4 and 8 weeks after the operation postprandial insulin level was (77. 4 ±1.1) mU/L and (77. 1 ± 1. 0) mU/L. At 2 weeks from the operation, the fasting GLP-1 in group O increased from ( 10. 7 ± 1.0) pmol/L to ( 13. 5 ±0. 8) pmol/L, and respectively to (26. 1 ±0. 9) pmol/L and (25. 3 ± 1.2) pmol/L at 4 and 8 weeks after the operation. The differences in the above-mentioned items before and after the operation were all significant in group O ( P ＜ 0. 05 ), and the differences in the items among group O and the other three groups ( P ＜ 0. 05 ) were all significant as well. In group O, the apoptosis rate of pancreatic islet cell decreased to (5.9 ± 0. 7 ) % at 4 weeks from the operation, and (6. 3 ±1.1 ) % at 8 weeks from the operation( P ＜ 0. 05 ). The expression of Bcl-2 protein in group O was 31.3 ±1.5, 35.7 ± 1.0 and 35. 8 ± 0. 8 at 2, 4 and 8 weeks post operation, which was significantly higher in statistics than those of the same time point in the other three groups ( P ＜ 0. 05 ). The expression of Bax protein in group O was 13.3 ±0.9, 10.8 ±0.9 and 10.9 ±1.1 at 2, 4 and 8 weeks from the operation,which was significantly lower in statistics than those of the same time point in the other three groups(P ＜0. 05).Conclusions Gastric bypass surgery can significantly reduce the blood glucose level and promote the secretion of GLP-1, and therefore inhibit the apoptosis of the islet β cells in diabetic rats through the Bcl-2 pathway.