Iwabe Maiko, Kawamoto Emi, Koshinaka Keiichi, Kawanaka Kentaro
Department of Health and Nutrition, Niigata University of Health and Welfare, Niigata, Japan.
Physiol Rep. 2014 Dec 11;2(12). doi: 10.14814/phy2.12162. Print 2014 Dec 1.
A single bout of exercise can enhance insulin-stimulated glucose uptake in both fast-twitch (type II) and slow-twitch (type I) skeletal muscle for several hours postexercise. Akt substrate of 160 kDa (AS160) is most distal insulin signaling proteins that have been proposed to contribute to the postexercise enhancement of insulin action in fast-twitch muscle. In this study, we examined whether the postexercise increase in insulin action of glucose uptake in slow-twitch muscle is accompanied by increased phosphorylation of AS160 and its paralog TBC1D1. Male Wistar rats (~1-month-old) were exercised on a treadmill for 180 min (9 m/min). Insulin (50 μU/mL)-stimulated glucose uptake was increased at 2 h after cessation of exercise in soleus muscle composed of predominantly slow-twitch fibers. This postexercise increase in insulin action of glucose uptake was accompanied by increased phosphorylation of AS160 (detected by phospho-Thr642 and phospho-Ser588 antibody). On the other hand, prior exercise did not increase phosphorylation of TBC1D1 (detected by phospho-Thr590) at 2 h postexercise. These results suggest the possibility that an enhancement in AS160 phosphorylation but not TBC1D1 phosphorylation is involved with increased postexercise insulin action of glucose uptake in slow-twitch muscle.
单次运动可在运动后数小时内增强快肌（II型）和慢肌（I型）骨骼肌中胰岛素刺激的葡萄糖摄取。160 kDa的Akt底物（AS160）是最远端的胰岛素信号蛋白，有人提出它有助于运动后快肌中胰岛素作用的增强。在本研究中，我们研究了运动后慢肌中葡萄糖摄取的胰岛素作用增加是否伴随着AS160及其旁系同源物TBC1D1磷酸化的增加。雄性Wistar大鼠（约1月龄）在跑步机上运动180分钟（9米/分钟）。在主要由慢肌纤维组成的比目鱼肌中，运动停止后2小时，胰岛素（50 μU/mL）刺激的葡萄糖摄取增加。运动后葡萄糖摄取的胰岛素作用增加伴随着AS160磷酸化的增加（通过磷酸化苏氨酸642和磷酸化丝氨酸588抗体检测）。另一方面，运动前并未增加运动后2小时TBC1D1的磷酸化（通过磷酸化苏氨酸590检测）。这些结果表明，AS160磷酸化增强而非TBC1D1磷酸化增强可能与运动后慢肌中葡萄糖摄取的胰岛素作用增加有关。
