Lesser Ellen Nacha, Arroyo-Ramirez Aime, Mi Sarah Jingyi, Robinson Mike James Ferrar
Neuroscience & Behavior Program, Wesleyan University, Middletown, CT, USA.
Neuroscience & Behavior Program, Wesleyan University, Middletown, CT, USA; Department of Psychology, Wesleyan University, Middletown, CT, USA.
Behav Brain Res. 2017 Jan 15;317:163-178. doi: 10.1016/j.bbr.2016.09.041. Epub 2016 Sep 17.
The global increase in obesity rates has been tied to the rise in junk-food availability and consumption. Increasingly, children are exposed to a junk-food diet during gestation and early development. Excessive consumption of junk-food during this period may negatively impact the development of brain motivation and reward pathways. In this study we investigated the effects of a chronic junk-food diet throughout development on cue-motivated behavior ('wanting'), hedonic 'liking' for sweet tastes, as well as anxiety and weight gain in male and female Long-Evans (LE) and Sprague-Dawley (SD) rats. Here we found that chronic exposure to a junk-food diet resulted in large individual differences in weight gain (gainers and non-gainers) despite resulting in stunted growth as compared to chow-fed controls. Behaviorally, junk-food exposure attenuated conditioned approach (autoshaping) in females, particularly in non-gainers. In contrast, junk-food exposed rats that gained the most weight were willing to work harder for access to a food cue (conditioned reinforcement), and were more attracted to a junk-food context (conditioned place preference) than non-gainers. Hedonic 'liking' reactions (taste reactivity) were severely blunted in LE, but not SD rats, and 'liking' for sucrose negatively correlated with greater weight gain. Finally, junk-food exposure reduced anxiety-like behavior (elevated plus maze) in males but not females. These results suggest that junk-food exposure during development may give rise to dissociable differences in 'liking' and 'wanting' neural systems that do not depend on weight gain and may not be detected through Body Mass Index monitoring alone.
全球肥胖率的上升与垃圾食品可得性及消费量的增加有关。越来越多的儿童在孕期和早期发育阶段就接触到垃圾食品饮食。在此期间过量食用垃圾食品可能会对大脑动机和奖赏通路的发育产生负面影响。在本研究中，我们调查了整个发育过程中慢性垃圾食品饮食对雄性和雌性长 Evans（LE）大鼠及斯普拉格 - 道利（SD）大鼠线索驱动行为（“渴望”）、对甜味的享乐性“喜好”以及焦虑和体重增加的影响。我们发现，与喂食普通饲料的对照组相比，尽管慢性接触垃圾食品饮食导致生长发育迟缓，但体重增加存在很大的个体差异（增重者和非增重者）。行为方面，接触垃圾食品会减弱雌性大鼠的条件性接近行为（自动形成），尤其是非增重者。相比之下，体重增加最多的接触垃圾食品的大鼠愿意为获取食物线索而更努力工作（条件性强化），并且比非增重者更被垃圾食品环境所吸引（条件性位置偏爱）。享乐性“喜好”反应（味觉反应性）在 LE 大鼠中严重减弱，但在 SD 大鼠中未减弱，并且对蔗糖的“喜好”与更大的体重增加呈负相关。最后，接触垃圾食品会减少雄性大鼠的焦虑样行为（高架十字迷宫实验），但对雌性大鼠没有影响。这些结果表明，发育期间接触垃圾食品可能会在“喜好”和“渴望”神经系统中产生可分离的差异，这些差异不依赖于体重增加，仅通过体重指数监测可能无法检测到。
