Desautels M, Dulos R A
Department of Physiology, College of Medicine, University of Saskatchewan, Saskatoon, Canada.
Am J Physiol. 1988 Aug;255(2 Pt 1):E120-8. doi: 10.1152/ajpendo.1988.255.2.E120.
Mice fasted for 24 h showed reductions in carcass fat and gonadal fat depots and atrophy of brown adipose tissue (BAT) that was characterized by loss of protein and succinate dehydrogenase. These changes were reversed on 24 h of refeeding. Cycling mice experienced 14 cycles of 1 day of fast followed by 2 days of refeeding, whereas control mice were fed ad libitum. Weight loss during each fast remained constant, and the animals lost and regained in excess of twice their initial weights within 6 wk. However, final weight and carcass and gonadal fat weights were similar to those of animals fed ad libitum. Total food intake was similar between cycling mice and those fed ad libitum suggesting an increase in feeding efficiency. There was no development of resistance to food deprivation since the preceding fasting experience of the animal had no effect on weight and carcass fat loss during a 24- or 48-h fast. Norepinephrine-stimulated oxygen consumption that was reduced in cycling mice was probably the result of a reduction of BAT thermogenic capacity. BAT succinate dehydrogenase content and the concentration of uncoupling protein in isolated mitochondria were significantly reduced. These changes in BAT composition were not observed when the refeeding period of each cycle was increased to 6 days. These results suggest that reduced energy expenditure in BAT may play a role in the conservation of energy during intermittent and frequent bouts of food deprivation.
禁食24小时的小鼠，其胴体脂肪和性腺脂肪储备减少，褐色脂肪组织（BAT）萎缩，其特征是蛋白质和琥珀酸脱氢酶流失。这些变化在重新喂食24小时后逆转。周期性禁食的小鼠经历了14个周期，即1天禁食后接着2天重新喂食，而对照小鼠则随意进食。每次禁食期间的体重减轻保持恒定，并且这些动物在6周内体重减轻和恢复的幅度超过其初始体重的两倍。然而，最终体重以及胴体和性腺脂肪重量与随意进食的动物相似。周期性禁食的小鼠和随意进食的小鼠的总食物摄入量相似，这表明进食效率有所提高。由于动物之前的禁食经历对24小时或48小时禁食期间的体重和胴体脂肪损失没有影响，因此没有产生对食物剥夺的抗性。周期性禁食的小鼠中去甲肾上腺素刺激的耗氧量降低，这可能是BAT产热能力降低的结果。BAT琥珀酸脱氢酶含量和分离线粒体中解偶联蛋白的浓度显著降低。当每个周期的重新喂食期增加到6天时，未观察到BAT组成的这些变化。这些结果表明，BAT能量消耗的减少可能在间歇性和频繁的食物剥夺期间的能量保存中起作用。
