Article

Antagonism of Sigma-1 Receptors Blocks Compulsive-Like Eating

Laboratory of Addictive Disorders, Departments of Pharmacology and Psychiatry, Boston University School of Medicine, Boston, MA, USA.
Neuropsychopharmacology: official publication of the American College of Neuropsychopharmacology (Impact Factor: 7.05). 06/2012; 37(12):2593-604. DOI: 10.1038/npp.2012.89
Source: PubMed

ABSTRACT

Binge eating disorder is an addiction-like disorder characterized by episodes of rapid and excessive food consumption within discrete periods of time which occur compulsively despite negative consequences. This study was aimed at determining whether antagonism of Sigma-1 receptors (Sig-1Rs) blocked compulsive-like binge eating. We trained male wistar rats to obtain a sugary, highly palatable diet (Palatable group) or a regular chow diet (Chow control group), for 1 h a day under fixed ratio 1 operant conditioning. Following intake stabilization, we evaluated the effects of the selective Sig-1R antagonist BD-1063 on food responding. Using a light/dark conflict test, we also tested whether BD-1063 could block the time spent and the food eaten in an aversive, open compartment, where the palatable diet was offered. Furthermore, we measured Sig-1R mRNA and protein expression in several brain areas of the two groups, 24 h after the last binge session. Palatable rats rapidly developed binge-like eating, escalating the 1 h intake by four times, and doubling the eating rate and the regularity of food responding, compared to Chow rats. BD-1063 dose-dependently reduced binge-like eating and the regularity of food responding, and blocked the increased eating rate in Palatable rats. In the light/dark conflict test, BD-1063 antagonized the increased time spent in the aversive compartment and the increased intake of the palatable diet, without affecting motor activity. Finally, Palatable rats showed reduced Sig-1R mRNA expression in prefrontal and anterior cingulate cortices, and a two-fold increase in Sig-1R protein expression in anterior cingulate cortex compared to control Chow rats. These findings suggest that the Sig-1R system may contribute to the neurobiological adaptations driving compulsive-like eating, opening new avenues of investigation towards pharmacologically treating binge eating disorder.

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    • "We also wanted to determine the compulsive-like component of sucrose intake in our model of binge-like eating. Compulsivity-like eating is defined as eating despite negative consequences [46,484950. In the modified LD box test in which a bottle of sucrose was available in the brightly lit aversive compartment, we observed that both BER and BEP rats consumed sucrose, but the intake of BEP rats was much higher compared to the BER phenotype. "
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    ABSTRACT: Binge eating episodes are frequently stimulated by stress. We developed a model of binge eating proneness based on individual sensitivity of young female Sprague Dawley rats to significantly increase sucrose consumption in response to stress. The rats were subjected to unpredictable intermittent 1-h access to 10% sucrose. After the stabilization of sucrose intake, rats were assessed for consistency of higher (for binge-like eating prone, BEP) or lower (for binge-like eating resistant, BER) sucrose intake in response to unpredictable episodes of foot-shock stress. The objectives of this study included demonstrating face validity of the BEP model and determining if some of the features of this model were pre-existing before exposure to intermittent access to sucrose and repeated stress. The BEP rats consumed a larger (20% > BER) amount of sucrose in a discrete (1-h) period of time compared to the BER phenotype in non-stressful conditions and significantly increased sucrose intake (50% > BER) under stress. Conversely, stress did not affect sucrose intake in BER rats. BEP rats showed higher sucrose intake compared to BER rats at the beginning of darkness as well as during the light period when they were sated and not physically hungry. Analyses of the sucrose licking microstructure revealed that BEP rats had a high motivational drive to consume sucrose in non-stressful condition and an increased hedonic value of sucrose when they were exposed to stressful conditions. BEP rats consumed sucrose much more rapidly under stressful conditions compared to BER rats. Finally, BEP rats demonstrated compulsive-like intake of sucrose (assessed in the light-dark box) and a blunted stress-induced increase in plasma corticosterone levels. Body weight and chow intake were not different between the phenotypes. Before exposure to intermittent access to sucrose and repeated stress, the BEP rats showed no clear evidence for compulsive sucrose intake. However, from the first 1-h access to sucrose, the BEP rats exhibited sucrose overeating; and from the first exposure to stress before intermittent access to sucrose, the BEP rats showed a blunted increase in corticosterone plasma levels. Innate sucrose hyperconsumption and altered reactivity of the hypothalamo-pituitary adrenal (HPA) axis to stress may be involved in the development of binge-like eating. Increased perceived hedonic value of palatable food and an increased motivation to consume this food despite aversive conditions as well as deregulated reactivity of the HPA axis may contribute to stress-induced bingeing on sucrose in BEP rats.
    Full-text · Article · Jan 2016 · Physiology & Behavior
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    • "The BDZ receptor partial inverse agonist Ro 15-4513 was administered immediately prior to ethanol in order to unmask its motor stimulating effect, previously reported to be hard to observe in C57Bl/6 mice [35] [36]. A locomotor activity test was performed in Plexiglas chambers (27 × 48 × 20 cm) using an Opto-M3 activity system (Columbus Instruments, Columbus, OH), as reported before [37] [38]. The Opto-M3 system consists of a series of 16 sensor beams spaced 2.54 cm apart along the longest side of the cage; motor activity was recorded by a computer over a 20 min period, which began 2 min after mice were pre-treated with Ro 15-4513 (0, 3 mg/kg; i.p.), and 1 min after ethanol (0, 1.5 g/kg; i.p.). "
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    ABSTRACT: Rationale: The Sigma-1 receptor (Sig-1R) is a chaperone protein that has been implicated in drug abuse and addiction. Multiple studies have characterized the role the Sig-1R plays in psychostimulants addiction, but fewer studies have specifically investigated its role in alcohol addiction. We have previously shown that antagonism of the Sig-1R reduces excessive drinking and motivation to drink, whereas agonism induces binge-like drinking in rodents. Objectives: The objectives of these studies were to investigate the impact of Sig-1R gene deletion in C57Bl/6J mice on ethanol drinking and other ethanol-related behaviors. Methods: We used an extensive panel of behavioral tests to examine ethanol actions in male, adult mice lacking Oprs1, the gene encoding the Sig-1R. To compare ethanol drinking behavior, Sig-1 knockout (KO) and wild type (WT) mice were subject to a two-bottle choice, continuous access paradigm with different concentrations of ethanol (3%-20% v/v) vs. water. Consumption of sweet and bitter solutions was also assessed in Sig-1R KO and WT mice. Finally, motor stimulant sensitivity, taste aversion and ataxic effects of ethanol were assessed. Results: Sig-1R KO mice displayed higher ethanol intake compared to WT mice; the two genotypes did not differ in their sweet or bitter taste perception. Sig-1R KO mice showed lower sensitivity to ethanol stimulant effects, but greater sensitivity to its taste aversive effects. Ethanol-induced sedation was unaltered in the mutants. Conclusions: Our results suggest that the deletion of the Sig-1R increases ethanol consumption, likely by decreasing its rewarding effects, and therefore indicating that the Sig-1R is involved in modulation of the reinforcing effects of alcohol.
    Full-text · Article · Oct 2015 · Behavioural brain research
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    • "Next, we determined whether high impulsivity predicted the loss of control over palatable food intake and compulsivelike eating. To test this hypothesis, we tested the rats in a light/dark conflict test, in which the food was offered in the aversive, bright compartment of the apparatus (Cottone et al, 2012; Dore et al, 2013b). Therefore, rats were required to face the aversive context in order to consume the food. "

    Full-text · Dataset · Apr 2015
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