Low Control over Palatable Food Intake in Rats Is Associated with Habitual Behavior and Relapse Vulnerability: Individual Differences

Abstract

The worldwide obesity epidemic poses an enormous and growing threat to public health. However, the neurobehavioral mechanisms of overeating and obesity are incompletely understood. It has been proposed that addiction-like processes may underlie certain forms of obesity, in particular those associated with binge eating disorder. To investigate the role of addiction-like processes in obesity, we adapted a model of cocaine addiction-like behavior in rats responding for highly palatable food. Here, we tested whether rats responding for highly palatable chocolate Ensure would come to show three criteria of addiction-like behavior, i.e., high motivation, continued seeking despite signaled non-availability and persistence of seeking despite aversive consequences. We also investigated whether exposure to a binge model (a diet consisting of alternating periods of limited food access and access to highly palatable food), promotes the appearance of food addiction-like behavior. Our data show substantial individual differences in control over palatable food seeking and taking, but no distinct subgroup of animals showing addiction-like behavior could be identified. Instead, we observed a wide range extending from low to very high control over palatable food intake. Exposure to the binge model did not affect control over palatable food seeking and taking, however. Animals that showed low control over palatable food intake (i.e., scored high on the three criteria for addiction-like behavior) were less sensitive to devaluation of the food reward and more prone to food-induced reinstatement of extinguished responding, indicating that control over palatable food intake is associated with habitual food intake and vulnerability to relapse. In conclusion, we present an animal model to assess control over food seeking and taking. Since diminished control over food intake is a major factor in the development of obesity, understanding its behavioral and neural underpinnings may facilitate improved management of the obesity epidemic.

Lisdexamfetamine reduces the compulsive and perseverative behaviour of binge-eating rats in a novel food reward/punished responding conflict model

“…Although this model had previously been employed to study motivation for cocaine-seeking, the authors reported that even mild foot-shocks suppressed all food-seeking by the rats. De Jong et al (2013) then switched to quinine adulteration of the palatable food as an alternative to evaluate punished responding in the rats. They observed that quinine adulteration suppressed operant responding for food to the same extent in the binge-eating and control groups of rats.…”

Pre-existing differences in motivation for food and sensitivity to cocaine-induced locomotion in obesity-prone rats

“…This sensitized response is indicative of enhanced responsivity of mesolimbic systems and is consistent with studies in humans suggesting that pre-existing differences in striatal motivational systems may contribute to obesity and hamper weight loss (Stice and Dagher, 2010, Berthoud et al, 2011, Volkow et al, 2011, Demos et al, 2012, Murdaugh et al, 2012). We speculate that pre-existing hyper-sensitivity of mesolimbic systems may facilitate neuroadaptations induced by eating sugary, fatty foods, and thereby further enhance responsivity to food cues in susceptible individuals (Robinson et al, 2015) and hamper the control of food intake (Wang et al, 2002, Johnson and Kenny, 2010, de Jong et al, 2013). Further studies using models that differentiate pre-existing from diet and/or obesity induced plasticity in motivational systems will continue to add to our understanding of how interactions between these factors contribute to the development and persistence of obesity.…”

“Eating addiction”, rather than “food addiction”, better captures addictive-like eating behavior

“…Moreover, after an extended history of cocaine self-administration, rats will continue to press a lever to obtain a cocaine infusion when a tone is presented that is previously associated with a foot shock (Deroche-Gamonet et al, 2004;Pelloux et al, 2007;Vanderschuren and Everitt, 2004). When compared to cocaine, rats are less motivated to work for a chocolate drink and in contrast to cocaine will not seek the chocolate drink when a tone is presented that was previously associated with a foot shock, even after being exposed to palatable diets for 2 months (de Jong et al, 2013; but see: Johnson and Kenny, 2010). Although some rats may display a tendency to display addictive-like behaviors, exposure to palatable foods high in fat and sugar, did not result increase these behaviors as observed after extended access to cocaine (de Jong et al, 2013).…”

“…When compared to cocaine, rats are less motivated to work for a chocolate drink and in contrast to cocaine will not seek the chocolate drink when a tone is presented that was previously associated with a foot shock, even after being exposed to palatable diets for 2 months (de Jong et al, 2013; but see: Johnson and Kenny, 2010). Although some rats may display a tendency to display addictive-like behaviors, exposure to palatable foods high in fat and sugar, did not result increase these behaviors as observed after extended access to cocaine (de Jong et al, 2013).…”