Parks Elizabeth Jane, Schneider Tara Lynn, Baar Rachel Ann
Department of Food Science and Nutrition, University of Minnesota-Twin Cities, 1334 Eckles Avenue, St. Paul, Minnesota 55108, USA.
Comp Med. 2005 Feb;55(1):24-9.
To identify optimal study-design conditions to investigate lipid metabolism, male, C57BL/6J mice (age, 59 +/- 3 days) were allotted to eight groups, with six animals per group that were stratified by three factors: diet type (high fat [HF]: 60% of energy from fat versus that of a standard rodent diet, 14% fat, fed for 7 weeks), feeding regimen (ad libitum [ad lib] versus meal fed), and metabolic state (data collected in fasted or fed states). Serum free fatty acids (FFA) and triacylglycerols (TAG) concentrations, and energy expenditure (EE) were assessed. Mice gained 0.30 +/- 0.11 g of body weight/day when allowed ad lib access to HF diet, similar weight when meal-fed the HF or ad lib-fed the standard diet (0.10 +/- 0.03 g/day), and no weight when meal-fed the standard diet (0.01 +/- 0.02 g/day). Fed-state TAG concentration was 88 to 100% higher (P < 0.02) than that of the fasted state, except when animals were ad lib-fed the HF diet. When the standard diet was meal fed, FFA concentration was 30% higher in the fasted compared with the fed state (P = 0.003). Mice had 33% higher postprandial EE when either diet was meal fed (P = 0.01). Mice adapted to meal feeding developed transitions in metabolism consistent with known physiologic changes that occur from fasting to feeding. When fed the standard diet, a 6-h per day meal-feeding regimen was restrictive for normal growth. These data support use of a meal-feeding regimen when HF diets are used and research is focused on metabolic differences between fasted and fed states. This protocol allows study of the metabolic effects of an HF diet without the confounding effects of over-consumption of food and excess body weight gain.
为确定研究脂质代谢的最佳研究设计条件，将雄性C57BL/6J小鼠（年龄59±3天）分为八组，每组六只动物，按三个因素分层：饮食类型（高脂肪[HF]：60%的能量来自脂肪，而标准啮齿动物饮食为14%脂肪，喂养7周）、喂养方式（自由采食[ad lib]与定时喂食）和代谢状态（在禁食或喂食状态下收集数据）。评估血清游离脂肪酸（FFA）和三酰甘油（TAG）浓度以及能量消耗（EE）。当自由采食HF饮食时，小鼠体重每天增加0.30±0.11克；当定时喂食HF饮食或自由采食标准饮食时，体重增加相似（0.10±0.03克/天）；当定时喂食标准饮食时，体重无增加（0.01±0.02克/天）。除动物自由采食HF饮食外，喂食状态下的TAG浓度比禁食状态高88%至100%（P<0.02）。当标准饮食定时喂食时，禁食状态下的FFA浓度比喂食状态高30%（P = 0.003）。当两种饮食定时喂食时，小鼠餐后EE高33%（P = 0.01）。适应定时喂食的小鼠代谢发生转变，与从禁食到进食时已知的生理变化一致。当喂食标准饮食时，每天6小时的定时喂食方案对正常生长具有限制性。这些数据支持在使用HF饮食且研究重点为禁食和喂食状态之间的代谢差异时采用定时喂食方案。该方案允许研究HF饮食的代谢效应，而不会受到食物过度消耗和体重过度增加的混杂影响。
