la Fleur S E, Luijendijk M C M, van der Zwaal E M, Brans M A D, Adan R A H
Department of Endocrinology and Metabolism, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.
Department of Neuroscience and Pharmacology, University Medical Centre Utrecht, Utrecht, The Netherlands.
Int J Obes (Lond). 2014 May;38(5):643-9. doi: 10.1038/ijo.2013.159. Epub 2013 Aug 27.
Rats subjected to a free-choice high-fat high-sugar (fcHFHS) diet persistently overeat, exhibit increased food-motivated behavior and become overtly obese. Conversely, several studies using a non-choice (nc) high-energy diet showed only an initial increase in food intake with unaltered or reduced food-motivated behavior. This raises the question of the importance of choice in the persistence of hyperphagia in rats on a fcHFHS diet.
Meal patterns, food intake and body weight gain were studied in male Wistar rats on free-choice diets with fat and/or sugar and in rats on nc diets with fat and sugar (custom made with ingredients similar to the fcHFHS diet).
Rats on a ncHFHS diet initially overconsumed, but reduced intake thereafter, whereas rats on a fcHFHS diet remained hyperphagic. Because half of the sugar intake in the fcHFHS group occurred during the inactive period, we next determined whether sugar intake during the light phase was a necessary requirement for hyperphagia, by restricting access to liquid sugar to either the light or dark period with unlimited access to fat and chow. Results showed that hyperphagia occurred irrespective of the timing of sugar intake. Meal pattern analysis revealed consumption of larger but fewer meals in the ncHFHS group, as well as the fcHF group. Interestingly, meal number was increased in all rats drinking liquid sugar (whether on a fcHFHS or a fcHS diet), whereas a compensatory decrease in meal size was only observed in the fcHS group, but not the fcHFHS group.
We hereby show the importance of choice in the observation of fcHFHS diet-induced hyperphagia, which results in increases in meal number due to sugar drinking without any compensatory decrease in meal size. We thus provide a novel dietary model in rats that mimics important features of human overconsumption that have been ignored in rodent models of obesity.
食用自由选择的高脂肪高糖（fcHFHS）饮食的大鼠持续暴饮暴食，表现出更强的食物驱动行为，并变得明显肥胖。相反，几项使用非选择（nc）高能饮食的研究表明，仅在最初食物摄入量会增加，而食物驱动行为未改变或减少。这就提出了一个问题，即在fcHFHS饮食的大鼠中，选择在暴饮暴食持续存在中的重要性。
研究了雄性Wistar大鼠在含有脂肪和/或糖的自由选择饮食以及含有脂肪和糖的nc饮食（使用与fcHFHS饮食相似的成分定制）中的进食模式、食物摄入量和体重增加情况。
ncHFHS饮食的大鼠最初过度进食，但此后摄入量减少，而fcHFHS饮食的大鼠则持续暴饮暴食。由于fcHFHS组一半的糖摄入量发生在不活动期间，接下来我们通过将液体糖的摄入限制在明期或暗期，同时让大鼠无限制地获取脂肪和食物，来确定明期的糖摄入是否是暴饮暴食的必要条件。结果表明，无论糖摄入的时间如何，都会出现暴饮暴食现象。进食模式分析显示，ncHFHS组以及fcHF组的大鼠进食量更大但餐数更少。有趣的是，所有饮用液体糖的大鼠（无论是fcHFHS饮食还是fcHS饮食）餐数都增加了，而仅在fcHS组中观察到餐量有代偿性减少，fcHFHS组则没有。
我们在此表明了选择在观察fcHFHS饮食诱导的暴饮暴食中的重要性，这种暴饮暴食会因饮用糖导致餐数增加，且餐量没有任何代偿性减少。因此，我们在大鼠中提供了一种新的饮食模型，该模型模拟了人类过度消费的重要特征，而这些特征在肥胖啮齿动物模型中被忽视了。
