氯化锂对Ⅱ型糖尿病患者离体红细胞胰岛素受体磷酸化的作用

EFFECTS OF LITHIUM CHLORIDE ON PHOSPHORYLATION OF RBC INSULIN RECEPTOR IN TYPE-TWO DIABETES MELLITUS

从受体水平探讨锂盐改善胰岛素敏感性的作用机制。方法 :红细胞经RPMI - 16 40孵育 30min ;用对甲苯磺酰氟 (PMSF)及超速低温离心等方法制备红细胞胰岛素受体标本 ;按Haruhiko酶联免疫吸附法(ELISA)分析红细胞磷酸化胰岛素受体数。结果 :胰岛素预处理Ⅱ型糖尿病患者红细胞后的磷酸化胰岛素受体数较对照组减少 ;用氯化锂预处理Ⅱ型糖尿病患者及对照组红细胞吸光度分别为 (1mM氯化锂 ) :0 .439±0 .12 1、0 .399± 0 .0 98;(10mM氯化锂 ) :0 .5 14± 0 .130、0 .384± 0 .10 2 ,表明 1～ 10mM氯化锂能引起二者红细胞胰岛素受体磷酸化 (P <0 .0 1) ,前者的反应显著高于后者 ;经 10 -7M胰岛素加 1mM氯化锂联合处理的Ⅱ型糖尿病患者的红细胞 ,其磷酸化胰岛素受体数高于单独用 10 -7M胰岛素者。结论 :肥胖的Ⅱ型糖尿病患者存在胰岛素受体水平 (酪氨酸激酶活性降低 )抵抗 ;氯化锂能导致Ⅱ型糖尿病患者及健康人红细胞胰岛素受体磷酸化 ,推测锂能激活酪氨酸激酶而发挥胰岛素样作用 ;

Objective:To investigate the mechanism of lithium on insulin sensitivity at receptor level.Methods:①RBC was treated in vitro with RPMI-1640 containing 11.1mM glucose、0.1%BSA and insulin or lithium;②PMSF and sodium orthovanadate were used to treat RBC and to prepare phosphorylated insulin receptor after centrfugation with 100,000g at 4℃(followed Haruhiko's method);③RBC phosphorylated insulin receptors were detected by Haruhiko's ELISA method.Results:①In type-two diabetes mellitus,the number of phosphorylated insulin receptor on RBC (0.307±0.124、0.897±0.106、1.203±0.145)reduced with 10 -9 M、10 -8 M、10 -7 M insulin respectively were less than that (0.755±0.132、1.176±0.109、1.318±0.181)of controls (P<0.05～0.01);②RBC phosphorylated insulin receptor number in both normal controls(1～10mM LiCl:0.399±0.098,0.384±0.102) and type-two diabetes mellitus (1～10mM LiCl:0.439±0.121、0.514±0.130) were increased with lithium (P<0.05～0.01),the latter was much greater than that of controls;③In type-two diabetes mellitus,the number of phosphorylated insulin receptor was increased more markedly by use of 10 -7 M insulin plus 1mM (1.349±0.149)than by 10 -7 M insulin plus 1mM LiCl(1.349±0.149)and by 10 -7 M insulin(1.203±0.145) alone.Conclusions:①Insulin resistance existed in patients with type-two diabetes mellitus as revealed by rather poor insulin receptor phosphorylation;②Insulin resistance occurred at receptor level and LiCl had an insulin-like effect through stimulating tyrosine protein kinase in both type-two diabetes mellitus patients and normal controls;③An additive effect on enhancing insulin sensitivity could be seen when LiCl and exogenous insulin were simultaneously used to treat RBC from type-two diabetes mellitus patients.