非肥胖2型糖尿病胰岛素抵抗的病机研究

Investigation of Mechanism of Insulin Resistance in Non-obese Type 2 Diabetes

目的 探讨胰岛素受体数目及其 β亚基自身磷酸化程度改变在 2型糖尿病患者胰岛素抵抗发生中的作用。 方法 14例非肥胖型 2型糖尿病患者和 12例正常对照者 ,用放射配基结合法测定完整红细胞膜上胰岛素受体数目及其亲和常数 ,按Comi等人所述方法制备红细胞膜蛋白 ,用胰岛素及γ -3 2PATP促发磷酸化反应 ,反应结束后进行不连续垂直板凝胶电泳 ( 0 1%SDS～ 7%5 %PAGE)分离蛋白质 ,并进行放射自显影 ,测定 95KD蛋白质的吸光度。结果 非肥胖型 2型糖尿病患者 ,每个红细胞上胰岛素高亲和力位点数目为 2 1± 13 ,亲和常数为 ( 1 70± 0 93 )× 10 -9LM-1 ,低亲和力位点数目为 95 5± 42 7,亲和常数为 ( 1 44± 0 86)× 10 -7LM-1 ,与正常对照组相比 ,差异无显著性 ;非肥胖型 2型糖尿病患者红细胞膜上 95KD蛋白的磷酸化程度为 8 0 2± 5 60△A/mg蛋白 ,明显低于对照组 2 8 3 8± 15 2 4△A/mg蛋白。结论 胰岛素受体 β亚基自身磷酸化程度的降低可能是非肥胖型 2型糖尿病患者胰岛素抵抗产生的主要因素 ;胰岛素受体数目及其与胰岛素亲和力的改变可能与非肥胖型

Objective To elucidate the role of insulin receptor and its β-subunit autophosphorylation in evoking insulin resistance in non-obese type 2 diabetes. Methods 14 patients with non-obese type 2 diabetes and 12 healthy subjects were enrolled in this study. Insulin receptor numbers and its insulin affinity in erythrocytes were measured using radio-labelled ligand binding assay described by Comi et al. Insulin receptor autophosphorylation in erythrocytes membrane was initiated by adding insulin and γ- 32 P ATP. Then the membrane proteins were resolved on 7 5% SDS-PAGE and subjected to autoradiography. Results The numbers of high and low affinity receptors in erythrocytes of type 2 diabetes were 21±13 and 955±427 per cell respectively, and they showed no significant difference as compared with control. The high affinity constant(K 1) and low affinity constant(K 2) of insulin receptors in erythrocytes of type 2 diabetes were (1 70±0 93)×10 -9 LM -1 and (1 44±0 86)×10 -7 LM -1 respectively, also displaying no significant difference in comparison with the control. Insulin-induced receptor β subunit autophosphorylation was 8 02±5 6△A/mg protein in type 2 diabetes, which was lower than that (28 38±15 24)△A/mg protein) in control(P<0 05). Conclusions The decrease in autophosphorylation of insulin receptor β subunit may be the major factor evoking insulin resistance in non-obese type 2 diabetes. The changes in number and affinity of insulin receptors may not be related to induction of insulin resistance in non-obese type 2 diabetes.