高糖对大鼠脂肪细胞胰岛素信号蛋白磷酸化的影响

目的 探讨高浓度葡萄糖（高糖）对原代培养大鼠脂肪细胞的葡萄糖转运活动、胰岛素信号蛋白磷酸化及表达的影响。方法 分离的大鼠脂肪细胞在5，10，15和25mmol/L葡萄糖中孵育24h，然后测定：糖转运活动；胰岛素受体（IR）、胰岛素受体底物（IRS）1、2及蛋白激酶B（PKB）的磷酸化；IRS1，IRS2，肌醇磷脂－3－激酶85亚单位（p85)和PKB的蛋白表达。结果 高糖抑制了这些细胞的葡萄糖转运活动，削弱了IR、IRS1的酪氨酸磷酸化及PKB的丝氨酸磷酸化；下调IRS1而上调IRS2蛋白表达。结论 高糖能抑制脂肪细胞的糖转运活动，诱导胰岛素抵抗。其作用机制与影响胰岛素信号蛋白多部位的磷酸化及蛋白表达有关。

Effects of high glucose on phosphorylations of insulin signaling proteins in rat adipocytes

Objective To explore the effects of high glucose on glucose transport activity, and phosphorylationandexpressionofinsulinsignalingproteins in primary cultured rat adipocytes. Methods Isolated rat adipocytes were cultured at different glucose concentrations (5, 10, 15, 25 mmol/L) for 24 h. Then the glucose uptake, the phosphorylations of insulin receptor (IR), insulin receptor substrate (IRS) 1 and 2 and protein kinase B (PKB) as well as the protein expressions of IRS1, IRS2, p85 subunit of phosphatitylinositol 3 kinase (p85) and PKB were measured. Results These adipocytes treated with different high glucose showed the impairment of the basal and insulin induced increase in glucose uptake and significant decrease of IR, IRS1 and PKB phosphorylations as well as IRS1 protein expression, but up regulation of IRS2 protein expression. p85 and PKB contents and IRS2 phosphorylation were unaffected. Conclusion The exposure to high glucose inhibits glucose uptake and induces insulin resistance in adipocyte. The mechanism may be involved in affecting the multiple step phosphorylations and the expressions of insulin signaling proteins.