Takahashi A, Shimazu T, Maruyama Y
Department of Neuropsychopharmacology (Tsumura), Gunma University School of Medicine, Maebashi, Japan.
Jpn J Physiol. 1992;42(4):653-64. doi: 10.2170/jjphysiol.42.653.
The effects of cold exposure on glucose transport system in brown adipose tissue (BAT) and the role of sympathetic nerves in this response were studied in rats. The rate constant of glucose uptake in BAT increased 10-, 13-, and 14-fold after 6 h, 1 d, and 2 d of cold exposure, respectively, as compared with controls. After 2 d of cold exposure, the number of glucose transporters in the plasma membranes increased from 10.2 +/- 1.1 to 16.7 +/- 1.4 pmol/mg protein and the transporter number in the microsomal membranes decreased from 15.1 +/- 1.0 to 9.0 +/- 1.1 pmol/mg protein, as measured by cytochalasin B binding. However, the increase in glucose utilization in BAT preceded the recruitment of glucose transporters to the plasma membranes. Thus, the glucose utilization markedly increased 6 h after cold exposure without significant increase in the glucose transporter number. The apparent dissociation constant (Kd) for cytochalasin B was unchanged. The stimulatory effect of cold exposure on glucose utilization in BAT was prevented by sympathetic denervation. In denervated BAT, cold exposure conversely decreased the number of glucose transporters in the plasma membranes. These results indicate that: (1) cold exposure increases glucose utilization in BAT and promotes translocation of glucose transporters from the microsomes to plasma membranes; (2) the effects of cold exposure depend entirely upon sympathetic innervation of BAT; (3) the recruitment or redistribution of glucose transporters accounts only partly for the large increase in glucose utilization in BAT after acute cold exposure.
在大鼠中研究了冷暴露对棕色脂肪组织（BAT）中葡萄糖转运系统的影响以及交感神经在此反应中的作用。与对照组相比，冷暴露6小时、1天和2天后，BAT中葡萄糖摄取的速率常数分别增加了10倍、13倍和14倍。冷暴露2天后，通过细胞松弛素B结合测定，质膜中葡萄糖转运体的数量从10.2±1.1增加到16.7±1.4 pmol/mg蛋白质，微粒体膜中的转运体数量从15.1±1.0减少到9.0±1.1 pmol/mg蛋白质。然而，BAT中葡萄糖利用的增加先于葡萄糖转运体向质膜的募集。因此，冷暴露6小时后葡萄糖利用显著增加，而葡萄糖转运体数量没有显著增加。细胞松弛素B的表观解离常数（Kd）没有变化。交感神经去支配可阻止冷暴露对BAT中葡萄糖利用的刺激作用。在去神经支配的BAT中，冷暴露反而减少了质膜中葡萄糖转运体的数量。这些结果表明：（1）冷暴露增加了BAT中的葡萄糖利用，并促进了葡萄糖转运体从微粒体向质膜的转运；（2）冷暴露的作用完全依赖于BAT的交感神经支配；（3）急性冷暴露后BAT中葡萄糖利用的大幅增加，葡萄糖转运体的募集或重新分布仅起部分作用。
