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McElroy SL, Coloma PM, Berger B, Guerdjikova AI, Joyce JM, Liebowitz MR, Pain S, Rabasa C. Efficacy, safety, and tolerability of nivasorexant in adults with binge-eating disorder: A randomized, Phase II proof of concept trial. Int J Eat Disord 2023; 56:2120-2130. [PMID: 37584285 DOI: 10.1002/eat.24039] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/14/2023] [Revised: 07/25/2023] [Accepted: 07/25/2023] [Indexed: 08/17/2023]
Abstract
OBJECTIVE This Phase II, placebo-controlled, double-blind study investigated the efficacy, safety, and tolerability of nivasorexant in the treatment of adults with moderate to severe binge-eating disorder (BED). METHODS Adults meeting the DSM-5 BED criteria were randomized 1:1 to placebo or nivasorexant (100 mg b.i.d.). The primary endpoint was the change from baseline to Week 12 in the number of binge eating (BE) days per week. Exploratory efficacy endpoints included cessation of BE in the last 4 weeks of treatment; and change from baseline to Week 12 in the number of BE episodes/week, the clinician global impression (CGI) of change, the Yale-Brown Obsessive-Compulsive Scale modified for BE, and the Hamilton rating scale for depression (HAMD-17). Key safety outcomes included treatment-emergent adverse events (TEAEs) and adverse events of special interest (i.e., somnolence and fatigue). RESULTS Sixty-eight participants were randomized to each treatment arm. The change from baseline to Week 12 in the number of BE days/week was the same for placebo (least squares mean [LSM]: -2.93) and nivasorexant (LSM: -2.93), with no difference between the treatment groups (LSM difference = .000 [95% confidence interval (CI): -.69, .69], p = .9992). Furthermore, no differences between treatment groups were observed in the exploratory efficacy endpoints. Nivasorexant was well tolerated; the overall incidence of TEAEs was balanced between treatment groups, and the frequency of somnolence and fatigue in the nivasorexant group were similar to placebo. DISCUSSION In this proof-of-concept study, 100 mg b.i.d. nivasorexant did not improve BE in adults with moderate to severe BED. PUBLIC SIGNIFICANCE The results of this Phase II study indicate that nivasorexant was well tolerated in adults with BED, but did not improve binge eating behavior over placebo. Further research is needed to improve our understanding of the role of the orexin-1 receptor in BED.
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Affiliation(s)
- Susan L McElroy
- Lindner Center of HOPE, Department of Psychiatry & Behavioral Neuroscience, University of Cincinnati College of Medicine, Cincinnati, Ohio, USA
| | | | | | - Anna I Guerdjikova
- Lindner Center of HOPE, Department of Psychiatry & Behavioral Neuroscience, University of Cincinnati College of Medicine, Cincinnati, Ohio, USA
| | - J Mark Joyce
- Clinical Neuroscience Solutions, Inc., Jacksonville, Florida, USA
| | - Michael R Liebowitz
- Medical Research Network, New York, New York, USA
- Department of Psychiatry, Columbia University, New York, New York, USA
| | - Scott Pain
- Idorsia Pharmaceuticals Ltd, Allschwil, Switzerland
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2
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Berger B, Kaufmann P, Berse M, Treiber A, Grignaschi N, Dingemanse J. Effect of nivasorexant (ACT-539313), a selective orexin-1-receptor antagonist, on multiple cytochrome P450 probe substrates in vitro and in vivo using a cocktail approach in healthy subjects. Pharmacol Res Perspect 2023; 11:e01143. [PMID: 37800597 PMCID: PMC10557102 DOI: 10.1002/prp2.1143] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Revised: 08/07/2023] [Accepted: 08/21/2023] [Indexed: 10/07/2023] Open
Abstract
Nivasorexant, a selective orexin-1-receptor antagonist, has recently been assessed in the treatment of humans with binge-eating disorder. Herein, the inhibitory potential of nivasorexant on cytochromes P450 (CYPs) 2C9, 2C19, and 3A4 was evaluated. Human liver microsomes/recombinant CYP enzymes were evaluated in vitro. In vivo, a single-center, open-label, fixed-sequence study was performed in healthy adults to explore the effect of 100 mg nivasorexant administered twice daily (b.i.d.) on the pharmacokinetics (PK) of flurbiprofen (50 mg, CYP2C9), omeprazole (20 mg, CYP2C19), midazolam (2 mg, CYP3A4) making use of a cocktail approach. Plasma PK sampling was performed over 24 h on Day 1 (Cocktail alone), 8 (Cocktail + nivasorexant), and 15 (Cocktail + nivasorexant at steady state). Genotyping of subjects' CYPs was performed while safety and tolerability were also assessed. In vitro, nivasorexant inhibited CYP2C9, 2C19, and 3A4 in competitive inhibition assays with IC50 values of 8.6, 1.6, and 19-44 μM, respectively, while showing a significant time-dependent CYP2C19 inhibition. In 22 subjects, exposure to flurbiprofen, omeprazole, and midazolam was generally higher during concomitant single- (i.e., area under the plasma concentration-time curve [AUC] ratio increased by 1.04-, 2.05-, and 1.56-fold, respectively) and repeated-dose (i.e., AUC ratio increased by 1.47-, 6.84-, and 3.71-fold, respectively) nivasorexant administration compared with the cocktail substrates administered alone. The most frequently reported adverse event was somnolence. According to regulatory guidance, nivasorexant is classified as a moderate CYP2C19 and weak CYP3A4 inhibitor after 1 day and as a weak CYP2C9, strong CYP2C19, and moderate CYP3A4 inhibitor after 8 days of 100 mg b.i.d. administration. Clinicaltrials.gov ID: NCT05254548.
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Affiliation(s)
- Benjamin Berger
- Department of Clinical PharmacologyIdorsia Pharmaceuticals LtdAllschwilSwitzerland
| | - Priska Kaufmann
- Department of Clinical PharmacologyIdorsia Pharmaceuticals LtdAllschwilSwitzerland
| | | | - Alexander Treiber
- Department of Preclinical Drug Metabolism and PharmacokineticsIdorsia Pharmaceuticals LtdAllschwilSwitzerland
| | - Nathalie Grignaschi
- Department of Preclinical Drug Metabolism and PharmacokineticsIdorsia Pharmaceuticals LtdAllschwilSwitzerland
| | - Jasper Dingemanse
- Department of Clinical PharmacologyIdorsia Pharmaceuticals LtdAllschwilSwitzerland
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3
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Sena KD, Beierle JA, Richardson KT, Kantak KM, Bryant CD. Assessment of Binge-Like Eating of Unsweetened vs. Sweetened Chow Pellets in BALB/c Substrains. Front Behav Neurosci 2022; 16:944890. [PMID: 35910681 PMCID: PMC9337213 DOI: 10.3389/fnbeh.2022.944890] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2022] [Accepted: 06/22/2022] [Indexed: 11/13/2022] Open
Abstract
Binge eating disorder (BED) is defined as chronic episodes of consuming large amounts of food in less than 2 h. Binge eating disorder poses a serious public health problem, as it increases the risk of obesity, type II diabetes, and heart disease. Binge eating is a highly heritable trait; however, its genetic basis remains largely unexplored. We employed a mouse model for binge eating that focused on identifying heritable differences between inbred substrains in acute and escalated intake of sucrose-sweetened palatable food vs. unsweetened chow pellets in a limited, intermittent access paradigm. In the present study, we examined two genetically similar substrains of BALB/c mice for escalation in food consumption, incubation of craving after a no-food training period, and compulsive-like food consumption in an aversive context. BALB/cJ and BALB/cByJ mice showed comparable levels of acute and escalated consumption of palatable food across training trials. Surprisingly, BALB/cByJ mice also showed binge-like eating of the unsweetened chow pellets similar to the escalation in palatable food intake of both substrains. Finally, we replicated the well-documented decrease in anxiety-like behavior in BALB/cByJ mice in the light-dark conflict test that likely contributed to greater palatable food intake than BALB/cJ in the light arena. To summarize, BALB/cByJ mice show binge-like eating in the presence and absence of sucrose. Possible explanations for the lack of selectivity in binge-like eating across diets (e.g., novelty preference, taste) are discussed.
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Affiliation(s)
- Katherine D. Sena
- Laboratory of Addiction Genetics, Department of Pharmacology and Experimental Therapeutics, Boston University School of Medicine, Boston, MA, United States
| | - Jacob A. Beierle
- Laboratory of Addiction Genetics, Department of Pharmacology and Experimental Therapeutics, Boston University School of Medicine, Boston, MA, United States
| | - Kayla T. Richardson
- Laboratory of Addiction Genetics, Department of Pharmacology and Experimental Therapeutics, Boston University School of Medicine, Boston, MA, United States
| | - Kathleen M. Kantak
- Department of Psychological and Brain Sciences, Boston University, Boston, MA, United States
| | - Camron D. Bryant
- Laboratory of Addiction Genetics, Department of Pharmacology and Experimental Therapeutics, Boston University School of Medicine, Boston, MA, United States
- *Correspondence: Camron D. Bryant
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4
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Jones JA, Zuhlsdorff K, Dalley JW. Neurochemical substrates linked to impulsive and compulsive phenotypes in addiction: A preclinical perspective. J Neurochem 2021; 157:1525-1546. [PMID: 33931861 DOI: 10.1111/jnc.15380] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Revised: 04/24/2021] [Accepted: 04/25/2021] [Indexed: 01/18/2023]
Abstract
Drug compulsion manifests in some but not all individuals and implicates multifaceted processes including failures in top-down cognitive control as drivers for the hazardous pursuit of drug use in some individuals. As a closely related construct, impulsivity encompasses rash or risky behaviour without foresight and underlies most forms of drug taking behaviour, including drug use during adverse emotional states (i.e., negative urgency). While impulsive behavioural dimensions emerge from drug-induced brain plasticity, burgeoning evidence suggests that impulsivity also predates the emergence of compulsive drug use. Although the neural substrates underlying the apparently causal relationship between trait impulsivity and drug compulsion are poorly understood, significant advances have come from the interrogation of defined limbic cortico-striatal circuits involved in motivated behaviour and response inhibition, together with chemical neuromodulatory influences from the ascending neurotransmitter systems. We review what is presently known about the neurochemical mediation of impulsivity, in its various forms, and ask whether commonalities exist in the neurochemistry of compulsive drug-motivated behaviours that might explain individual risk for addiction.
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Affiliation(s)
- Jolyon A Jones
- Department of Psychology, University of Cambridge, Cambridge, UK
| | | | - Jeffrey W Dalley
- Department of Psychology, University of Cambridge, Cambridge, UK.,Department of Psychiatry, Hershel Smith Building for Brain and Mind Sciences, Cambridge, UK
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Recent perspectives on orexin/hypocretin promotion of addiction-related behaviors. Neuropharmacology 2020; 168:108013. [PMID: 32092435 DOI: 10.1016/j.neuropharm.2020.108013] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2019] [Revised: 01/23/2020] [Accepted: 02/14/2020] [Indexed: 12/18/2022]
Abstract
The neuropeptide hypocretin/orexin plays a broad and important role in physiological functions ranging from addiction, stress, and anxiety to sleep, energy metabolism, and homeostatic regulation. A number of recent reviews addressing the importance of orexin for different addictive behaviors, especially the contribution of orexin-1-receptors (Ox1Rs) in responding for intoxicants in higher-motivation individuals and situations, and orexin-2-receptor (Ox2Rs) in stress-related aspects of addictive responding. This may parallel the importance of more lateral orexin neurons in the hypothalamus for reward and more medial for stress and arousal. However, there is clearly also some crossover, which may reflect, in part, where positive and negative conditioning (reward- and relief-seeking) are both present concurrently in established addiction, and also where orexin signaling can differ in subregions of a particular brain region. Here, we attempt to examine and synthesize some of the most recent work addressing orexin functions in addiction, including a particular role for Ox1Rs for driving responding in higher-motivation individuals and under higher levels of effort. While there are some commonalities across addictive substances addressed here (alcohol, cocaine, opiates), there are also some differences, which may relate to several factors including the speed of intoxication with a given substance. Together, recent findings have shed important insight and clues into what a more unified role of Ox1Rs might entail, and critical areas for future work. In addition, these many studies support the development of Ox1R blockers for use in humans to counteract addiction and other disorders of motivation. This article is part of the special issue on Neuropeptides.
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6
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Rodríguez-Ortega E, Cubero I. Environmental Enrichment Modulates Drug Addiction and Binge-Like Consumption of Highly Rewarding Substances: A Role for Anxiety and Compulsivity Brain Systems? Front Behav Neurosci 2018; 12:295. [PMID: 30555310 PMCID: PMC6281824 DOI: 10.3389/fnbeh.2018.00295] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2018] [Accepted: 11/15/2018] [Indexed: 01/09/2023] Open
Abstract
Drug addiction is a chronic disorder comprising components of both impulsivity and compulsivity in the so called “addiction cycle” which develops over time from early non-dependent, repetitive, binge-consumption to later post-dependent compulsive consumption. Thus, frequent binge-like intake is a typical pattern of excessive drug intake characteristic of the pre-dependent phase of the addiction cycle, which represent an important risk factor to develop addiction in vulnerable individuals. In this framework, it is of paramount interest to further understand the earliest stage of the addiction cycle so novel approaches would emerge aimed to control repetitive episodes of binge-consumption in non-dependent subjects, protecting vulnerable individuals from transition to dependence. Environmental enrichment (EE) is a preclinical animal model in which animals are housed under novel, social enriched conditions, which allows exercising and provides sensory and cognitive stimulation. EE promotes important improvements for a variety of cognitive processes and clear therapeutic and protective effects preventing ethanol (EtOH) and drug addiction as well. Interestingly, recent observations suggest that EE might additionally modulate binge-like intake of highly palatable caloric substances, including EtOH, which suggests the ability of EE to regulate consumption during the initial stage of the addiction cycle. We have proposed that EE protective and therapeutic effects on binge-consumption of palatable substances might primarily be mediated by the modulatory control that EE exerts on anxiety and impulsivity/compulsivity traits, which are all risk factors favoring transition to drug addiction.
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Affiliation(s)
| | - Inmaculada Cubero
- Departamento de Psicología, Universidad de Almería, Almería, Spain.,Centro de Evaluación y Rehabilitación Neuropsicológica (CERNEP), Universidad de Almería, Almería, Spain
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7
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Kreisler AD, Mattock M, Zorrilla EP. The duration of intermittent access to preferred sucrose-rich food affects binge-like intake, fat accumulation, and fasting glucose in male rats. Appetite 2018; 130:59-69. [PMID: 30063959 PMCID: PMC6168430 DOI: 10.1016/j.appet.2018.07.025] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2018] [Revised: 07/23/2018] [Accepted: 07/25/2018] [Indexed: 12/21/2022]
Abstract
Many people restrict their palatable food intake. In animal models, time-limiting access to palatable foods increases their intake while decreasing intake of less preferred alternatives; negative emotional withdrawal-like behavior is sometimes reported. In drug addiction models, intermittent extended access drives greater changes in use than brief access. When it comes to palatable food, the impact of briefer vs. longer access durations within intermittent access conditions remains unclear. Here, we provided male rats with chow or with weekday access to a preferred, sucrose-rich diet (PREF) (2, 4, or 8 h daily) with chow otherwise available. Despite normal energy intake, all restricted access conditions increased weight gain by 6 weeks and shifted diet acceptance within 1 week. They increased daily and 2-h intake of PREF with individual vulnerability and decreased chow intake. Rats with the briefest access had the greatest binge-like (2-h) intake, did not lose weight on weekends despite undereating chow, and were fattier by 12 weeks. Extended access rats (8 h) showed the greatest daily intake of preferred food and corresponding undereating of chow, slower weight gain when PREF was unavailable, and more variable daily energy intake from week to week. Increased fasting glucose was seen in 2-h and 8-h access rats. During acute withdrawal from PREF to chow diet, restricted access rats showed increased locomotor activity. Thus, intermittent access broadly promoted weight gain, fasting hyperglycemia and psychomotor arousal during early withdrawal. More restricted access promoted greater binge-like intake and fat accumulation, whereas longer access promoted evidence of greater food reward tolerance.
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Affiliation(s)
- A D Kreisler
- Department of Neuroscience, The Scripps Research Institute, La Jolla, CA, USA.
| | - M Mattock
- Department of Neuroscience, The Scripps Research Institute, La Jolla, CA, USA
| | - E P Zorrilla
- Department of Neuroscience, The Scripps Research Institute, La Jolla, CA, USA
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8
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Gentile TA, Simmons SJ, Watson MN, Connelly KL, Brailoiu E, Zhang Y, Muschamp JW. Effects of Suvorexant, a Dual Orexin/Hypocretin Receptor Antagonist, on Impulsive Behavior Associated with Cocaine. Neuropsychopharmacology 2018; 43:1001-1009. [PMID: 28741623 PMCID: PMC5854790 DOI: 10.1038/npp.2017.158] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/28/2017] [Revised: 07/10/2017] [Accepted: 07/16/2017] [Indexed: 11/09/2022]
Abstract
Hypothalamic hypocretin (orexin) peptides mediate arousal, attention, and reward processing. Fibers containing orexins project to brain structures that govern motivated behavior, including the ventral tegmental area (VTA). A number of psychiatric conditions, including attention deficit hyperactivity disorder (ADHD) and substance use disorders, are characterized by deficits in impulse control, however the relationship between orexin and impulsive behavior is incompletely characterized. The effects of systemic or centrally administered orexin receptor (OXR) antagonists on measures of impulsive-like behavior in rats were evaluated using the five-choice serial reaction time task (5-CSRTT) and delay discounting procedures. These paradigms were also used to test the capacity of OXR antagonists to attenuate acute cocaine-evoked impulsivity. Finally, immunohistochemistry and calcium imaging were used to assess potential cellular mechanisms by which OXR blockade may influence motor impulsivity. Suvorexant, a dual (OX1/2R) orexin receptor antagonist, reduced cocaine-evoked premature responses in 5-CSRTT when administered systemically or directly into VTA. Neither suvorexant nor OX1R- or OX2R-selective compounds (SB334867 or TCS-OX2-29, respectively) altered delay discounting. Finally, suvorexant did not alter Fos-immunoreactivity within tyrosine hydroxylase-immunolabeled neurons of VTA, but did attenuate cocaine- and orexin-induced increases in calcium transient amplitude within neurons of VTA. Results from the present studies suggest potential therapeutic utility of OXR antagonists in reducing psychostimulant-induced motor impulsivity. These findings also support the view that orexin transmission is closely involved in executive function in normal and pathological conditions.
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Affiliation(s)
- Taylor A Gentile
- Center for Substance Abuse Research, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, USA
| | - Steven J Simmons
- Center for Substance Abuse Research, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, USA
| | - Mia N Watson
- Center for Substance Abuse Research, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, USA
| | - Krista L Connelly
- Center for Substance Abuse Research, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, USA
| | - Eugen Brailoiu
- Center for Substance Abuse Research, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, USA
| | - Yanan Zhang
- Research Triangle Institute, Research Triangle Park, NC, USA
| | - John W Muschamp
- Center for Substance Abuse Research, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, USA,Center for Substance Abuse Research, Department of Pharmacology, Lewis Katz School of Medicine, Temple University, 3500 North Broad Street – MERB 849, Philadelphia, PA, 19140, USA, Tel: +1 215 707 8089, Fax: +1 215 707 6661, E-mail:
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Alcaraz-Iborra M, Navarrete F, Rodríguez-Ortega E, de la Fuente L, Manzanares J, Cubero I. Different Molecular/Behavioral Endophenotypes in C57BL/6J Mice Predict the Impact of OX 1 Receptor Blockade on Binge-Like Ethanol Intake. Front Behav Neurosci 2017; 11:186. [PMID: 29066961 PMCID: PMC5641301 DOI: 10.3389/fnbeh.2017.00186] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2017] [Accepted: 09/25/2017] [Indexed: 12/16/2022] Open
Abstract
Ethanol (EtOH) research has focused on stages of dependence. It is of paramount importance to more deeply understand the neurobehavioral factors promoting increased risk for EtOH binge drinking during the early stages of the addiction cycle. The first objective of this study was to evaluate whether C57BL/6J mice showing high drinking in the dark (DID) exhibit neurobehavioral traits known to contribute to EtOH binge-drinking disorders. Comparing high vs. low drinkers (HD/LD), we evaluated different types of basal anxiety-like responses, EtOH preference and sensitivity to the reinforcing properties of EtOH, and basal mRNA expression of the OX1/OX2 receptors (OX1r/OX2r) within the prefrontal cortex (PFC) and the nucleus accumbens (NAcc). Additionally, we tested binge drinking by LD/HD in response to a selective OX1r antagonist following intermittent episodes of DID (iDID). We report that DID consistently segregates two neurobehavioral endophenotypes, HD vs. LD, showing differences in neophobia and/or impulsivity/compulsivity traits. Additionally, HD mice show decreased basal OX1r and OX2r mRNA expression within the NAcc and elevated OX1r within the PFC. Exposure to several intermittent episodes of EtOH DID triggered a rapid increase in EtOH intake over time in LD mice matching that observed in HD mice. Despite HD/LD endophenotypes did not show differences in EtOH intake, they still predicted the response to a pharmacological challenge with a selective OX1r antagonist. The present data underscore the relevance of HD/LD endophenotypes stemming from DID procedures for exploring neurobehavioral processes underlying the early stages of the addiction cycle and EtOH binge-drinking disorders.
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Affiliation(s)
- Manuel Alcaraz-Iborra
- Laboratorio de Psicobiología, Departamento de Psicologia, Universidad de Almería, Almería, Spain
| | - Francisco Navarrete
- Instituto de Neurociencias, Consejo Superior de Investigaciones Científicas (CSIC), Universidad Miguel Hernández de Elche, Elche, Spain
| | - Elisa Rodríguez-Ortega
- Laboratorio de Psicobiología, Departamento de Psicologia, Universidad de Almería, Almería, Spain
| | - Leticia de la Fuente
- Laboratorio de Psicobiología, Departamento de Psicologia, Universidad de Almería, Almería, Spain
| | - Jorge Manzanares
- Instituto de Neurociencias, Consejo Superior de Investigaciones Científicas (CSIC), Universidad Miguel Hernández de Elche, Elche, Spain
| | - Inmaculada Cubero
- Laboratorio de Psicobiología, Departamento de Psicologia, Universidad de Almería, Almería, Spain.,Institute of Biomedical Sciences, Universidad Autonoma de Chile, Santiago de Chile, Chile
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Orexin/hypocretin-1 receptor antagonism reduces ethanol self-administration and reinstatement selectively in highly-motivated rats. Brain Res 2016; 1654:34-42. [PMID: 27771284 DOI: 10.1016/j.brainres.2016.10.018] [Citation(s) in RCA: 65] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2016] [Revised: 10/17/2016] [Accepted: 10/18/2016] [Indexed: 12/18/2022]
Abstract
The orexin/hypocretin (ORX) system regulates motivation for natural rewards and drugs of abuse such as alcohol. ORX receptor antagonists, most commonly OX1R antagonists including SB-334867 (SB), decrease alcohol drinking, self-administration and reinstatement in both genetically-bred alcohol-preferring and outbred strains of rats. Importantly, levels of alcohol seeking and drinking in outbred rats are variable, as they are in humans. We have shown that OX1R antagonism selectively decreases homecage alcohol drinking in high-, but not low-alcohol-preferring rats. It is unknown, however, whether this effect is selective to homecage drinking or whether it also applies to alcohol seeking paradigms such as self-administration and reinstatement following extinction, in which motivation is high in the absence of alcohol. Here we trained Sprague Dawley rats to self-administer 20% ethanol paired with a light-tone cue on an FR3 regimen. Rats were then extinguished and subjected to cue-induced reinstatement. Rats were segregated into high- and low-ethanol-responding groups (HR and LR) based on self-administration levels. During self-administration and cue-induced reinstatement, rats were given SB or vehicle prior to ethanol seeking. In both conditions, OX1R antagonism decreased responding selectively in HR, but not LR rats. There were no non-specific effects of SB treatment on arousal or general behavior. These data indicate that ORX signaling at the OX1R receptor specifically regulates high levels of motivation for alcohol, even in the absence of direct alcohol reinforcement. This implicates the ORX system in the pathological motivation underlying alcohol abuse and alcoholism and demonstrates that the OX1R may be an important target for treating alcohol abuse.
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11
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Reichelt AC, Westbrook RF, Morris MJ. Integration of reward signalling and appetite regulating peptide systems in the control of food-cue responses. Br J Pharmacol 2015; 172:5225-38. [PMID: 26403657 DOI: 10.1111/bph.13321] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2015] [Revised: 07/28/2015] [Accepted: 08/27/2015] [Indexed: 12/24/2022] Open
Abstract
Understanding the neurobiological substrates that encode learning about food-associated cues and how those signals are modulated is of great clinical importance especially in light of the worldwide obesity problem. Inappropriate or maladaptive responses to food-associated cues can promote over-consumption, leading to excessive energy intake and weight gain. Chronic exposure to foods rich in fat and sugar alters the reinforcing value of foods and weakens inhibitory neural control, triggering learned, but maladaptive, associations between environmental cues and food rewards. Thus, responses to food-associated cues can promote cravings and food-seeking by activating mesocorticolimbic dopamine neurocircuitry, and exert physiological effects including salivation. These responses may be analogous to the cravings experienced by abstaining drug addicts that can trigger relapse into drug self-administration. Preventing cue-triggered eating may therefore reduce the over-consumption seen in obesity and binge-eating disorder. In this review we discuss recent research examining how cues associated with palatable foods can promote reward-based feeding behaviours and the potential involvement of appetite-regulating peptides including leptin, ghrelin, orexin and melanin concentrating hormone. These peptide signals interface with mesolimbic dopaminergic regions including the ventral tegmental area to modulate reactivity to cues associated with palatable foods. Thus, a novel target for anti-obesity therapeutics is to reduce non-homeostatic, reward driven eating behaviour, which can be triggered by environmental cues associated with highly palatable, fat and sugar rich foods.
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Affiliation(s)
- A C Reichelt
- School of Psychology, UNSW Sydney, Sydney, UNSW, Australia.,School of Medical Sciences, UNSW Sydney, Sydney, UNSW, Australia
| | - R F Westbrook
- School of Psychology, UNSW Sydney, Sydney, UNSW, Australia
| | - M J Morris
- School of Medical Sciences, UNSW Sydney, Sydney, UNSW, Australia
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