高脂膳食和跑台运动构建模型大鼠腓肠肌葡萄糖转运体4和 cAMP反应元件结合蛋白的变化

摘要

BACKGROUND:Some studies indicate that PI3K/Akt signaling pathway is associated with the expression of glucose transporter 4 (GLUT4) and the function of cAMP response element binding protein (CREB) in skeletal muscle. However, it is stil unclear whether PI3K/Akt signaling pathway has the effects on CREB and GLUT4 in skeletal muscle of the rats with high-fat diet and treadmil exercise. OBJECTIVE:To investigate whether PI3K/Akt signaling pathway has the effects on CREB and GLUT4 in gastrocnemius muscle of the rats with high-fat diet and treadmil exercise. METHODS:A total of 70 rats were fed with normal diet for 2 weeks, and randomly divided into common feed group (n=20) and high-fat feed group (n=50). Rats in both groups were respectively fed with common feed and high-fat feed for 8 weeks. The rats in the common feed group were equaly assigned to common feed quiet group and common feed exercise group. 20 rats from the high-fat feed group whose body weight was 1.4 times of common rats were randomly and equaly assigned to obese quiet group and obese exercise group. Rats in the quiet groups did not do exercises. Rats in the exercise groups received adaptive sports for 1 week and medium-intensity treadmil exercise for 8 weeks. RESULTS AND CONCLUSION:(1) Impairments of PI3K/Akt signaling pathway appeared in obese rats, however, the quantity of GLUT4 expression did not change obviously in gastrocnemius muscles of obese rats. The reasons for the decrease of the nuclear protein CREB level of gastrocnemius muscles of obese rats might be related to the decrease of pAkt-Ser473 level. (2) The increase of the quantity of GLUT4 expression was accompanied by significantly up-regulated pAkt-Ser473 level by exercise intervention in gastrocnemius muscles of obese rats. Exercise intervention significantly increased the expression of nuclear protein CREB in gastrocnemius muscles of chow-fed rats and obese rats, which was consistent with the changes of pAkt-Ser473. These findings suggest that pAkt-Ser473 can play an important role in the effects of high-fat diet and exercise intervention on GLUT4 and CREB protein expression in gastrocnemius muscles of obese rats.%背景：研究表明 PI3K/Akt 信号通路与骨骼肌葡萄糖转运体4的表达以及 cAMP 反应元件结合蛋白(cAMP response element binding protein，CREB)的功能发挥均相关，但PI3K/Akt信号通路在高脂膳食和运动对骨骼肌葡萄糖转运体4和CREB的影响中是否发挥作用尚无定论。目的：探讨PI3K/Akt信号通路在高脂膳食和跑台运动对大鼠腓肠肌葡萄糖转运体4和CREB的影响中是否发挥作用。方法：70只大鼠普通饲料适应性喂养2周后，随机分为普通饲料组(n=20)和高脂饲料组(n=50)，分别以普通饲料和高脂饲料饲养8周。普饲料组大鼠随机等分为普饲安静组和普饲运动组。选取高脂饲料组中体质量超过普通饲料组大鼠平均体质量加1.4倍标准差的大鼠20只，随机等分为肥胖安静组和肥胖运动组。普饲安静组和肥胖安静组大鼠不运动。普通饲料运动组和肥胖运动组大鼠经1周适应性运动后进行8周中等强度的跑台运动。结果与结论：①肥胖大鼠腓肠肌出现PI3K/Akt信号通路障碍，但葡萄糖转运体4表达没有显著变化；肥胖大鼠腓肠肌核蛋白CREB水平降低的原因可能与pAkt-Ser473水平下降有关。②运动干预在引起大鼠腓肠肌葡萄糖转运体4表达增加的同时明显上调了pAkt-Ser473的水平；运动干预明显升高普通膳食大鼠和肥胖大鼠腓肠肌核蛋白CREB表达，并与pAkt-Ser473的变化相一致。证实pAkt-Ser473水平的变化在高脂膳食和运动干预影响腓肠肌葡萄糖转运体4和CREB蛋白表达中可能发挥着重要作用。