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目的探讨骨骼肌组织中胰岛素受体底物1(IRS-1)表达及其酪氨酸磷酸化与妊娠期糖尿病发生胰岛素抵抗的关系。方法采用蛋白印迹法(western blot)及免疫沉淀法检测22例妊娠期糖尿病患者(妊娠期糖尿病组)、22例正常妊娠妇女(正常妊娠组)及13例正常非孕妇女(正常非孕组)骨骼肌组织中 IRS-1蛋白表达水平及其酪氨酸磷酸化程度;采用放射免疫法及葡萄糖氧化酶法检测各组妇女空腹胰岛素(FINS)及空腹血糖(FPG)水平,并采用稳态模型法计算胰岛素抵抗指数(HOMA-IR)。结果 (1)妊娠期糖尿病组 FPG、FINS、HOMA-IR 分别为(5.6±0.8)mmol/L、(15.4±5.1)mU/L、1.2±0.5,正常妊娠组分别为(4.4±0.5)mmol/L、(10.6±3.1)mU/L、0.8±0.3,两组间各指标分别比较,差异均有统计学意义(P<0.01);正常非孕组 FINS、HOMA-IR 分别为(7.6±2.3)mU/L、0.5±0.3,分别与正常妊娠组比较,差异均有统计学意义(P<0.01)。(2)妊娠期糖尿病组 IRS-1蛋白表达水平为0.64±0.11,明显低于正常妊娠组的0.81±0.13,两组分别比较,差异均有统计学意义(P<0.01);正常非孕组 IRS-1蛋白表达水平为0.83±0.12,与正常妊娠组比较,差异无统计学意义(P>0.05)。(3)妊娠期糖尿病组基础及胰岛素刺激后的 IRS-1酪氨酸磷酸化程度分别为0.35±0.12及0.48±0.14,均低于正常妊娠组的0.38±0.13及0.66±0.12,两组分别比较,差异均有统计学意义(P<0.01);正常妊娠组胰岛素刺激后的 IRS-1酪氨酸磷酸化程度明显低于正常非孕组的0.85±0.09(P<0.01)。(4)妊娠期糖尿病组 IRS-1蛋白表达水平和胰岛素刺激后的酪氨酸磷酸化程度与 HOMA-IR 呈明显负相关(r=-0.613,-0.632;P<0.01);正常妊娠组胰岛素刺激后酪氨酸磷酸化程度与 HOMA-IR 呈明显负相关(r=-0.526,P<0.05)。结论骨骼肌组织中IRS-1蛋白表达及其酪氨酸磷酸化程度异常,是妊娠期糖尿病患者发生胰岛素抵抗的分子机制之一。
Objective To investigate the relationship between insulin receptor substrate 1 (IRS-1) expression and tyrosine phosphorylation and insulin resistance in gestational diabetes mellitus (DM). Methods Twenty-two gestational diabetes mellitus (gestational diabetes mellitus), 22 normal pregnant women (normal pregnancy group) and 13 normal non-pregnant women (normal non-pregnant group) were detected by western blot and immunoprecipitation. The level of IRS-1 protein and tyrosine phosphorylation in skeletal muscle tissue were determined. The levels of fasting insulin (FINS) and fasting plasma glucose (FPG) in each group were detected by radioimmunoassay and glucose oxidase method. Method to calculate insulin resistance index (HOMA-IR). Results The levels of FPG, FINS and HOMA-IR in gestational diabetes mellitus group were (5.6 ± 0.8) mmol / L, (15.4 ± 5.1) mU / L and 1.2 ± 0.5 respectively, and those in normal pregnancy group were (4.4 ± 0.5) mmol /L, (10.6 ± 3.1) mU / L and 0.8 ± 0.3 respectively. There was significant difference between the two groups (P <0.01). FINS and HOMA-IR in the non-pregnant group were (7.6 ± 2.3) mU / L, 0.5 ± 0.3, respectively, compared with the normal pregnancy group, the difference was statistically significant (P <0.01). (2) The expression of IRS-1 protein in gestational diabetes mellitus group was 0.64 ± 0.11, which was significantly lower than that in normal pregnancy group (0.81 ± 0.13, P <0.01) IRS-1 protein expression level of 0.83 ± 0.12, compared with the normal pregnancy group, the difference was not statistically significant (P> 0.05). (3) The levels of IRS-1 tyrosine phosphorylation in gestational diabetes mellitus group and insulin-stimulated group were 0.35 ± 0.12 and 0.48 ± 0.14, respectively, which were lower than those in normal pregnancy group (0.38 ± 0.13 and 0.66 ± 0.12, respectively) (P <0.01). The IRS-1 tyrosine phosphorylation in normal pregnancy group was significantly lower than that in normal non-pregnant group (0.85 ± 0.09, P <0.01). (4) The level of IRS-1 protein and the tyrosine phosphorylation level of insulin-stimulated group were negatively correlated with HOMA-IR (r = -0.613, -0.632, P <0.01) in gestational diabetes mellitus group. Insulin The level of tyrosine phosphorylation was negatively correlated with HOMA-IR after stimulation (r = -0.526, P <0.05). Conclusion The expression of IRS-1 protein in skeletal muscle and the abnormality of tyrosine phosphorylation are one of the molecular mechanisms of insulin resistance in gestational diabetes mellitus.