Muralidhara D V, Desautels M
Department of Physiology, College of Medicine, University of Saskatchewan, Saskatoon, Canada.
Am J Physiol. 1994 Jun;266(6 Pt 2):R1907-15. doi: 10.1152/ajpregu.1994.266.6.R1907.
The objective of this work was to evaluate how obesity would influence the changes in brown fat (BAT) thermogenic capacity during fasting-refeeding. Mice fed either chow or chow + high-fat supplement for 6 wk had body weights of 34 +/- 1 and 43 +/- 1 g, respectively. They were fasted for 48 h followed by ad libitum refeeding for up to 5 days. Loss of carcass fat was similar between food-deprived mice previously fed chow or chow + high-fat supplement. However, even after a 48-h fast, obese mice still had a carcass fat content much greater than that of chow-fed mice. Brown fat atrophy caused by food deprivation was characterized by reductions in tissue weight, fat, mitochondrial proteins and uncoupling protein (UCP), without change in tissue DNA. Obesity did not alter the rate or extent of brown fat atrophy. Upon refeeding 48-h-fasted lean and obese mice, there was recovery of BAT thermogenic capacity that was similar between the two groups. In chow-fed mice, an intact neural input was essential for recovery of BAT thermogenic capacity during refeeding. These results indicate that food deprivation triggers an immediate adaptive response in mice previously fed chow or chow + a high-fat supplement and that reduction in brown fat thermogenic capacity during fasting and its recovery during refeeding appear little affected by the size of the animal energy reserves.
这项工作的目的是评估肥胖如何影响禁食-再喂养期间棕色脂肪（BAT）产热能力的变化。喂食普通饲料或普通饲料+高脂补充剂6周的小鼠体重分别为34±1克和43±1克。它们禁食48小时，然后随意再喂养长达5天。先前喂食普通饲料或普通饲料+高脂补充剂的饥饿小鼠的体脂损失相似。然而，即使禁食48小时后，肥胖小鼠的体脂含量仍远高于喂食普通饲料的小鼠。食物剥夺引起的棕色脂肪萎缩的特征是组织重量、脂肪、线粒体蛋白和解偶联蛋白（UCP）减少，而组织DNA没有变化。肥胖并未改变棕色脂肪萎缩的速率或程度。对禁食48小时的瘦小鼠和肥胖小鼠进行再喂养后，两组的BAT产热能力均得以恢复。在喂食普通饲料的小鼠中，完整的神经输入对于再喂养期间BAT产热能力的恢复至关重要。这些结果表明，食物剥夺会触发先前喂食普通饲料或普通饲料+高脂补充剂的小鼠立即产生适应性反应，并且禁食期间棕色脂肪产热能力的降低及其再喂养期间的恢复似乎受动物能量储备大小的影响很小。
