间歇低氧大鼠肝细胞GLUT-2、GCK表达与胰岛素抵抗的相关性研究

Association between the expression of GLUT-2, GCK in hepatocytes and insulin resistance in rats treated by intermittent hypoxia

目的检测葡萄糖转运蛋白-2（GLUT-2）、葡萄糖激酶（GCK）在间歇低氧大鼠模型肝细胞中表达的变化，探讨间歇低氧引起胰岛素抵抗的相关机制。方法24只6周龄健康雄性Sprague．Dawley（SD）大鼠按照随机数字表法分为对照组、间歇低氧4周组（IH4组）和间歇低氧8周组（IH8组），每组8只。间歇低氧组按预设通气模式每天给予间歇低氧暴露8h，对照组给予间歇压缩空气，暴露时间同IH4组。实验结束后测定各组大鼠空腹血糖、空腹胰岛素，计算稳态模型评估．胰岛素抵抗指数（HOMA．IR）及胰岛素敏感性指数（ISI）。免疫组织化学染色观察肝细胞GLUT-2、GCK蛋白表达变化，并利用平均灰度值对蛋白进行定量分析。结果与对照组相比，IH4组及IH8组空腹血糖、空腹胰岛素、HOMA—IR均升高，ISI均降低，且IH8组更明显（F=161．92、51．46、126．99、83．87，P均〈0．05）。与对照组相比，IH4组及IH8组肝细胞GLUT-2、GCK蛋白表达均降低，且IH8组更显著（F=184．91、240．85，P均〈0．05）。Pearson相关分析显示，GLUT-2、GCK平均灰度值与ISI呈负相关（r=-0．886、-0．906，P均〈0．05），与HOMA-IR呈正相关（r=0．894、0．869，P均〈0．05）。结论间歇低氧暴露使大鼠肝细胞GLUT-2、GCK蛋白表达下调，可能参与间歇低氧条件下胰岛素抵抗的发生。

Objective To determine the expression of glucose transporter-2 （GLUT-2） and glucokinase （GCK） in hepatocytes of intermittent hypoxic rat model, and explore the possible mechanisms of insulin resistance caused by intermittent hypoxia. Methods Twenty-four healthy male Sprague-Dawley （SD） rats at 6-week age were divided into control group （NC group） ,4 weeks of intermittent hypoxia group （ IH4 group） and 8 weeks of intermittent hypoxia group （ IH8 group） according to the random number table, with 8 rats in each group. According to the preset ventilation mode, rats in intermittent groups were exposed in intermittent hypoxia for 8 hours every day, whereas rats in NC group were exposed in intermittent com- pressed air for the same time with IH4 group. Fasting blood glucose and fasting insulin were tested after ex- periment; homeostasis model assessment-insulin resistance index （HOMA-IR） and insulin sensitivity index （ISI） were calculated. The expression of hepatic GLUT-2 and GCK protein were measured by immunohisto- chemical method, and were quantitatively analyzed by the average gray value. Results Compared with NC group, fasting blood glucose, fasting insulin and HOMA-IR were increased, whereas ISI were decreased in IH4 group and IH8 group, especially in IH8 group （F = 161.92, 51.46, 126.99, 83.87, all P 〈 0.05 ）. Compared with NC group, the expression of GLUT-2 and GCK in hepatic cells were decreased in IH4 group and IH8 group, especially in IH8 group （F = 184.91, 240.85, all P 〈0.05）. Pearson correlation analysis showed that the level of GLUT-2 and GCK were negatively correlated with ISI （ r = - 0.886, - 0. 906, all P 〈 0.05）, and positively correlated with HOMA-IR （ r = 0. 894, 0. 869, all P 〈 0.05 ）. Conclusion Intermittent hypoxia decreases the expression of GLUT-2 and GCK, which may participate in the occurrence of insulin resistance under the condition of intermittent hypoxia.