The effect of naloxone on food-motivated behavior in the obese Zucker rat

Glass, Michael J.; O’Hare, Eugene; Cleary, J.; Billington, Charles J.; Levine, Allen S.

doi:10.1007/s002130050847

Cited by 41 publications

(39 citation statements)

References 29 publications

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“…Another observation that strengthens this hypothesis is that the effect of naloxone was not apparent during the first runway trials (Figure 3a). Kirkham and Blundell (1986) have found similar results, as did Glass et al (1999b), in a study of obese and lean Zucker rats. It seems that rats need to experience food under naloxone to show the observed effects.…”

Section: Discussionsupporting

confidence: 62%

Differential Regulation of the Consummatory, Motivational and Anticipatory Aspects of Feeding Behavior by Dopaminergic and Opioidergic Drugs

Barbano

Cador

2005

Neuropsychopharmacol

115

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Various aspects of feeding behavior (eg consumption, motivation and anticipation) are regulated by homeostatic and hedonic systems, and are modulated by dopaminergic and opioid brain systems. Here, we have studied the modulation of these aspects of feeding behavior by opioid and dopaminergic neurotransmission while taking into account food palatability and homeostatic state. Foods that varied in palatability were presented to either food sated or food restricted rats following injections of different doses of naloxone, an opioid receptor antagonist, or flupenthixol, a dopaminergic receptor antagonist, in behavioral paradigms that measured different aspects of feeding. Naloxone decreased food intake in a dose-dependent manner in sated rats given access to palatable food, without modifying food intake in food restricted rats. Flupenthixol did not have any effect on food intake. With regard to motivation, which was tested in a straight alley, naloxone increased the latency to reach the food only in sated rats presented with palatable food. Flupenthixol did not modify the latency of any group. Conditioned locomotor activity to repeated food presentation, a measure of anticipation, is expressed only in food restricted rats. Naloxone did not modify anticipatory activity, whereas flupenthixol decreased it only in food restricted rats presented with palatable food. These results reinforce the idea that the opioid system regulates feeding through the modulation of the perceived palatability of food. The dopaminergic system seems to be more important for the regulation of anticipatory activity related to motivationally relevant stimuli.

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Section: Discussionsupporting

confidence: 62%

Differential Regulation of the Consummatory, Motivational and Anticipatory Aspects of Feeding Behavior by Dopaminergic and Opioidergic Drugs

Barbano

Cador

2005

Neuropsychopharmacol

115

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“…This may also explain the findings by Grass et al, because under their PR3 schedule of reinforcement rats obtained over 40 pellets of sucrose. 26 With the PR schedule of reinforcement we used in these studies, we did not observe a satiety effect, and therefore our data suggest that obese rats are more motivated to work for food. Motivation for food and obesity SE la Fleur et al Interestingly, motivation to respond for sucrose before rats were subjected to the HFHS-choice diet correlated positively with the rate of obesity afterwards.…”

Section: Discussionmentioning

confidence: 53%

“…22,23 However, Glass and colleagues found a difference only between obese and lean Zucker rats when pressing for grain pellets, and not for sucrose pellets. 26 They hypothesized that obese rats are more responsive to the energy content, which is higher in sucrose than in grain pellets. It is, however, important to consider the influence of satiety signals in responding for food.…”

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…However, in nongenetic obese models, changes in food-motivated behavior were not observed. [22][23][24][25][26] It is, therefore, unclear whether there is an effect of obesity on food-motivated behavior, and to what extent such behavior affects the development of obesity.The present experiments were designed to characterize the metabolic changes and food-motivated behavior when rats were subjected to a choice diet with chow, lard and a 30% sucrose solution. First, we studied feeding, locomotor activity and body temperature, fat weights and hormonal concentrations when rats were subjected to the choice diet for 1 week to demonstrate the development of obesity.…”

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confidence: 99%

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A reciprocal interaction between food-motivated behavior and diet-induced obesity

et al. 2007

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Objectives: One of the main causes of obesity is overconsumption of diets high in fat and sugar. We studied the metabolic changes and food-motivated behavior when rats were subjected to a choice diet with chow, lard and a 30% sucrose solution (high fat high sugar (HFHS)-choice diet). Because rats showed considerable variations in the feeding response to HFHS-choice diet and in food-motivated behavior, we investigated whether the motivation to obtain a sucrose reward correlated with the development of obesity when rats were subsequently subjected to HFHS-choice diet. Method: We first studied feeding, locomotor activity and body temperature, fat weights and hormonal concentrations when male Wistar rats were subjected to HFHS-choice diet for 1 week. Second, we studied sucrose-motivated behavior, using a progressive ratio (PR) schedule of reinforcement in rats that were subjected to the HFHS-choice diet for at least 2 weeks, compared to control rats on a chow diet. Third, we measured motivation for sucrose under a PR schedule of reinforcement in rats that were subsequently subjected to HFHS-choice diet or a chow diet for 4 weeks. Fat weights were measured and correlated with the motivation to obtain sucrose pellets. Results: One week on the HFHS-choice diet increased plasma concentrations of glucose and leptin, increased fat stores, but did not alter body temperature or locomotor activity. Moreover, consuming the HFHS-choice diet for several weeks increased the motivation to work for sucrose pellets. Furthermore, the motivation to obtain sucrose pellets correlated positively with abdominal fat stores in rats subsequently subjected to the HFHS-choice diet, whereas this correlation was not found in rats fed on a chow diet. Conclusion: Our data suggest that the motivation to respond for palatable food correlates with obesity due to an obesogenic environment. Conversely, the HFHS-choice diet, which results in obesity, also increased the motivation to work for sucrose. Thus, being motivated to work for sucrose results in obesity, which, in turn, increases food-motivated behavior, resulting in a vicious circle of food motivation and obesity. IntroductionObesity is one of the fastest growing medical problems in modern society. It contributes to the development of chronic disorders such as cardiovascular disease, type 2 diabetes, hypertension and some cancers. 1 For healthy body weight regulation, it is important to balance energy intake and energy expenditure. Modern society, however, is characterized by a sedentary lifestyle and a calorie intake, which is not adjusted for that. Although regulatory mechanisms that balance intake and expenditure are known , 2,3 it still remains unclear why this fails in obese individuals. It has been postulated that the ability to overconsume high-energy dense foods (in the face of plentiful food availability) was selected during evolution. Thus, under conditions when food availability is uncertain and scarce, consuming highenergy dense foods is an adequate adaptation (for a review see Uli...

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A proposed hypothalamic–thalamic–striatal axis for the integration of energy balance, arousal, and food reward

Kelley

Baldo

Pratt

2005

J of Comparative Neurology

313

286

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We elaborate herein a novel theory of basal ganglia function that accounts for why palatable, energy-dense foods retain high incentive value even when immediate physiological energy requirements have been met. Basal ganglia function has been studied from the perspective of topographical segregation of processing within parallel circuits, with primary focus on motor control and cognition. Recent findings suggest, however, that the striatum can act as an integrated unit to modulate motivational state. We describe evidence that the striatal enkephalin system, which regulates the hedonic impact of preferred foods, undergoes coordinated gene expression changes that track current motivational state with regard to food intake. Striatal enkephalin gene expression is also downregulated by an intrastriatal infusion of a cholinergic muscarinic antagonist, a manipulation that greatly suppresses food intake. To account for these findings, we propose that signaling through a hypothalamic-midline thalamic-striatal axis impinges on the cholinergic interneurons of the striatum, which via their large, overlapping axonal fields act as a network to modulate enkephalin-containing striatal output neurons. A key relay in this circuit is the paraventricular thalamic nucleus, which receives convergent input from orexin-coded hypothalamic energy-sensing and behavioral state-regulating neurons, as well as from circadian oscillators, and projects to cholinergic interneurons throughout the striatal complex. We hypothesize that this system evolved to coordinate feeding and arousal, and to prolong the feeding central motivational state beyond the fulfillment of acute energy needs, thereby promoting "overeating" and the consequent development of an energy reserve for potential future food shortages.

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The effect of naloxone on food-motivated behavior in the obese Zucker rat

Cited by 41 publications

References 29 publications

Differential Regulation of the Consummatory, Motivational and Anticipatory Aspects of Feeding Behavior by Dopaminergic and Opioidergic Drugs

Differential Regulation of the Consummatory, Motivational and Anticipatory Aspects of Feeding Behavior by Dopaminergic and Opioidergic Drugs

A reciprocal interaction between food-motivated behavior and diet-induced obesity

A proposed hypothalamic–thalamic–striatal axis for the integration of energy balance, arousal, and food reward

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