THE EFFECTS OF FASTING AND REFEEDING ON LIVER-GLYCOGEN SYNTHASE AND PHOSPHORYLASE IN OBESE AND LEAN MICE
THE EFFECTS OF FASTING AND REFEEDING ON LIVER-GLYCOGEN SYNTHASE AND PHOSPHORYLASE IN OBESE AND LEAN MICE
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DOI：
10.1055/s-2007-1003285
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发表时间：
1992-04-01
影响因子：
2.2
通讯作者：
TURTLE, JR
中科院分区：
文献类型：
--
作者：
CHEN, C;WILLIAMS, PF;TURTLE, JR
作为研究金硫葡萄糖（GTG）肥胖小鼠胰岛素抵抗可能部位的一部分，我们评估了肝糖原合成酶和磷酸化酶对禁食和再喂养的反应。在剥夺食物48小时和葡萄糖灌胃120分钟（1 g/kg wt）后，对瘦肉小鼠和GTG小鼠的糖原合成酶和磷酸化酶（合成酶I和磷酸化酶a）的活性形式和这些酶的总活性进行了估计。瘦小鼠在饥饿12 h后肝糖原含量下降幅度最大，磷酸化酶活性从23.8 +/- 1.9 μ mol/g蛋白/min降至6.8 +/- 0.7 μ mol/g蛋白/min。这些变化伴随着合酶I活性的增加（从0.14 +/- 0.01增加到0.46 +/- 0.04 mu-mol/g protein/min）。在肥胖小鼠中，饥饿48小时后，酶活性也发生了类似的变化。这些变化伴随着GTG小鼠高胰岛素血症和高血糖的显著减少。瘦小鼠和肥胖小鼠灌胃葡萄糖后，合酶I的活性在前30分钟进一步升高，随后下降。复饲后磷酸化酶活性逐渐升高。本研究结果表明，尽管肝糖原沉积增加，但即使存在胰岛素抵抗，肥胖小鼠肝脏中糖原合成酶和磷酸化酶对禁食和再喂养的反应与对照小鼠相似。
The responses of hepatic glycogen synthase and phosphorylase to fasting and refeeding were assessed as part of an investigation into possible sites of insulin resistance in gold thioglucose (GTG) obese mice. The active forms glycogen synthase and phosphorylase (synthase I and phosphorylase a) and the total activity of these enzymes were estimated in lean and GTG mice over 48 h of food deprivation, and for 120 min after glucose gavage (1 g/kg wt). In lean mice there was a maximal reduction in hepatic glycogen content after 12 h of starvation and the activity of phosphorylase a decreased from 23.8 +/- 1.9 to 6.8 +/- 0.7 mu-mol/g protein/min. These changes were accompanied by an increase in the activity of synthase I (from 0.14 +/- 0.01 to 0.46 +/- 0.04-mu-mol/g protein/min). In obese mice, similar changes in enzyme activity occurred after 48 h of starvation. These changes were accompanied by a significant reduction in the hyperinsulinemia and hyperglycemia of the GTG mice. After glucose gavage in both lean and obese mice, the activity of synthase I further increased over the first 30 min and declined thereafter. The activity of phosphorylase a increased progressively after refeeding. Results from this study suggest that despite increased hepatic glycogen deposition, the responses of glycogen synthase and phosphorylase, in livers of obese mice, to fasting and refeeding are similar to those of control mice even in the presence of insulin resistance.