Department of Psychology, Michigan State University, 316 Physics Road, East Lansing, MI 48824, USA.
Neuroscience Program, Michigan State University, 293 Farm Lane, East Lansing, MI 48824, USA.
Physiol Behav. 2019 Jul 1;206:13-21. doi: 10.1016/j.physbeh.2019.03.005. Epub 2019 Mar 8.
Binge eating is characterized by the consumption of a large amount of palatable food in a short period of time and is a core feature of many eating disorders. Patients with eating disorders are also known to display impairments in inhibitory control, cognition and decision-making, which may promote and maintain binge eating symptomology. In the current study, we examined whether rats that were subsequently characterized as displaying a higher propensity to binge eat would show pre-existing deficits in reinforcer devaluation-a paradigm used to examine decision-making following reductions in the value of a food reinforcer. Female rats were first trained to respond on two levers for the delivery of two food reinforcers (sucrose and maltodextrin solutions). At the test stage, rats were provided 1 h access to one of the two reinforcers to allow for devaluation via sensory specific satiety, immediately followed by an extinction test with both levers. Normal rats typically show reductions in responding on the lever associated with the devalued reinforcer (i.e., intact goal-directed responding). Subsequently, we used intermittent access to palatable food to identify high (BE prone [BEP]; n = 14), intermediate (BE neutral [BEN]; n = 48), and low (BE resistant [BER]; n = 13) phenotypes of binge eating. Prior reinforcer devaluation performance showed BEN and BER rats suppressed responding on the lever associated with the devalued reinforcer while BEP rats did not. This insensitivity to instrumental reinforcer devaluation in BEP rats did not reflect impaired sensory-specific satiety as during a food choice test, BEP rats showed a more robust alteration in food preferences following devaluation. Additionally, across all rats sensory specific satiety was correlated with subsequent intake of palatable food. Collectively, these findings suggest dissociable effects of devaluation procedures on instrumental actions and consummatory behaviors in BEP rats, and may indicate that pre-existing differences in goal-directed behavior and sensory-specific satiety contribute to the propensity to overeat palatable food.
暴食症的特征是在短时间内大量食用美味食物，这是许多饮食失调症的核心特征。患有饮食失调症的患者也表现出抑制控制、认知和决策方面的障碍，这可能会促进和维持暴食症状。在目前的研究中，我们研究了那些随后表现出更高暴食倾向的大鼠是否会在强化物贬损之前表现出缺陷，强化物贬损是一种用于检查食物强化物价值降低后决策的范式。雌性大鼠首先接受训练，通过两个杠杆来获得两种食物强化物（蔗糖和麦芽糊精溶液）。在测试阶段，大鼠有 1 小时的时间来接触其中一种强化物，通过感官特异性饱腹感来进行价值贬低，然后立即用两个杠杆进行消退测试。正常大鼠通常会减少与贬低强化物相关的杠杆反应（即，完整的目标导向反应）。随后，我们使用间歇性的美味食物来识别高（暴食倾向 [BEP]；n=14）、中（暴食中性 [BEN]；n=48）和低（暴食抵抗 [BER]；n=13）暴食表型。先前的强化物贬损表现表明，BEN 和 BER 大鼠抑制了与贬损强化物相关的杠杆反应，而 BEP 大鼠则没有。BEP 大鼠对工具性强化物贬损的这种不敏感并不反映感觉特异性饱腹感受损，因为在食物选择测试中，BEP 大鼠在价值贬低后表现出更强的食物偏好改变。此外，所有大鼠的感觉特异性饱腹感与随后对美味食物的摄入量呈正相关。综上所述，这些发现表明，在 BEP 大鼠中，贬损程序对工具性行为和消费行为有不同的影响，这可能表明目标导向行为和感觉特异性饱腹感的先前差异有助于暴食美味食物的倾向。
