Regulation of rodent energy metabolism, body weight and composition

我们让老鼠自由食用两种不同的致肥食物，然后换成食物，看看肥胖是否会逆转。其中，71只雄性C57BL/6小鼠单独饲养，6只小鼠安乐死后，其余小鼠随机分为5组：1)C组（N=18）继续饲喂鼠粮；2) HF组（N=18）饲喂60%高脂日粮；3) HFL组（N=17），高脂日粮加液体保证；4) HF-C组（N=6）在7周后由高脂组转为低脂组；5) HFL-C组（N=6）在7周后由高脂加高脂改为低脂。7周后，两种肥胖饮食组的体重都有所增加，其中补充Ensure的组体重增加最多，血清胰岛素、葡萄糖和瘦素浓度升高，血清甘油三酯浓度反而降低。肥胖的发生是由于能量摄入增加、平均能量输出相对减少以及运动活动减少引起的。改食12周后，HF-C组和HF-C组体重有所减轻，但与对照组相比，持续肥胖水平保持不变（分别为34.81.2 g、34.11.2 g和30.80.8 g, P < 0.05）。除瘦素略有升高外，所有血清激素和代谢物均恢复到控制水平。饮食转换后，HF-C组和HF-C组的平均能量输出与C组一致，尽管额外摄入的能量少于1 kcal/d，但持续肥胖仍然维持。

We provided mice with free access to two different obesigenic diets followed by a switch to chow to see if obesity was reversed. Specifically, 71 male C57BL/6 mice were individually-housed and after 6 mice were euthanized for baseline measurements the remaining mice were randomly assigned to five groups: 1) C group (N=18) continued on the chow diet; 2) HF group (N=18) on a 60% high fat diet; 3) HFL group (N=17) on the high fat diet plus liquid Ensure; 4) HF-C group (N=6) switched from high fat to chow after 7 weeks; 5) HFL-C group (N=6) switched from high fat plus Ensure to chow after 7 weeks. Body weight was increased after 7 weeks on both obesigenic diets, with the Ensure supplemented group gaining the most weight and corresponded to elevated concentrations of serum insulin, glucose, and leptin and paradoxically lower serum triglycerides. Development of obesity was caused by increased energy intake and a relative decrease of average energy output along with decreased locomotor activity. Twelve weeks after the switch to chow, the HF-C and HFL-C groups lost weight but maintained the same level of persistent obesity vs. control (34.81.2, 34.11.2 vs. 30.80.8 g respectively; P < 0.05). All serum hormones and metabolites returned to control levels with the exception for a slight increase of leptin. After the diet switch, the HF-C and HFL-C groups had an average energy output in line with the C group and the persistent obesity was maintained despite less than 1 kcal/d of additional energy intake.