Macho L, Ficková M, Zórad S
Institute of Experimental Endocrinology, Slovak Academy of Sciences, Bratislava, Slovak Republic.
Physiol Res. 2000;49 Suppl 1:S79-85.
Early postnatal administration of monosodium glutamate (MSG) to rats induces obesity, hyperinsulinemia and hyperglycemia in adulthood, thus suggesting the presence of insulin resistance. We therefore investigated the effects of insulin on glucose transport and lipogenesis in adipocytes as well as insulin binding to specific receptors in the liver, skeletal muscle and fat tissues. An increase of plasma insulin, glucose and leptin levels was found in 3-month-old rats treated with MSG during the postnatal period. The attenuation of insulin stimulatory effect on glucose transport was observed in MSG-treated rats. Despite the lower basal and insulin-stimulated glucose uptake, the incorporation of glucose into lipids was significantly higher in MSG-treated rats, suggesting a shift in glucose metabolism towards lipid synthesis in fat tissue. Insulin binding to plasma membranes from the liver, skeletal muscle and adipocytes was decreased in MSG-treated rats. This is in agreement with the lower insulin effect on glucose transport in these animals. Furthermore, a decreased amount of GLUT4 protein was found in adipocytes from MSG-treated obese rats. The results demonstrated an attenuation of insulin effect on glucose transport due to a lower insulin binding and lower content of GLUT4 protein in MSG-treated rats. However, the effect of insulin on lipogenesis was not changed. Our results indicated that early postnatal administration of MSG exerts an important effect on glucose metabolism and insulin action in adipocytes of adult animals.
在出生后早期给大鼠注射味精（MSG）会导致成年后肥胖、高胰岛素血症和高血糖，从而提示存在胰岛素抵抗。因此，我们研究了胰岛素对脂肪细胞中葡萄糖转运和脂肪生成的影响，以及胰岛素与肝脏、骨骼肌和脂肪组织中特定受体的结合情况。在出生后接受味精处理的3个月大的大鼠中，发现血浆胰岛素、葡萄糖和瘦素水平升高。在接受味精处理的大鼠中，观察到胰岛素对葡萄糖转运的刺激作用减弱。尽管基础葡萄糖摄取和胰岛素刺激的葡萄糖摄取较低，但在接受味精处理的大鼠中，葡萄糖掺入脂质的量显著更高，这表明脂肪组织中葡萄糖代谢向脂质合成发生了转变。在接受味精处理的大鼠中，胰岛素与肝脏、骨骼肌和脂肪细胞膜的结合减少。这与这些动物中胰岛素对葡萄糖转运的较低作用一致。此外，在接受味精处理的肥胖大鼠的脂肪细胞中发现GLUT4蛋白量减少。结果表明，在接受味精处理的大鼠中，由于胰岛素结合减少和GLUT4蛋白含量降低，胰岛素对葡萄糖转运的作用减弱。然而，胰岛素对脂肪生成的作用没有改变。我们的结果表明，出生后早期注射味精对成年动物脂肪细胞中的葡萄糖代谢和胰岛素作用有重要影响。
