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Maussion G, Rocha C, Ramoz N. iPSC-derived models for anorexia nervosa research. Trends Mol Med 2024; 30:339-349. [PMID: 38472034 DOI: 10.1016/j.molmed.2024.02.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2024] [Revised: 02/14/2024] [Accepted: 02/16/2024] [Indexed: 03/14/2024]
Abstract
Anorexia nervosa (AN) is a complex neuropsychiatric disorder with genetic and epigenetic components that results in reduced food intake combined with alterations in the reward-processing network. While studies of patient cohorts and mouse models have uncovered genes and epigenetic changes associated with the disease, neuronal networks and brain areas preferentially activated and metabolic changes associated with reduced food intake, the underlying molecular and cellular mechanisms remain unknown. The use of both 2D in vitro cultures and 3D models, namely organoids and spheroids, derived from either human embryonic stem cells (ESCs) or induced pluripotent stem cells (iPSCs), would allow identification of cell type-specific changes associated with AN and comorbid diseases, to study preferential connections between brain areas and organs, and the development of therapeutic strategies.
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Affiliation(s)
- Gilles Maussion
- The Neuro's Early Drug Discovery Unit (EDDU), McGill University, Montreal, Quebec H3A 2B4, Canada.
| | - Cecilia Rocha
- The Neuro's Early Drug Discovery Unit (EDDU), McGill University, Montreal, Quebec H3A 2B4, Canada
| | - Nicolas Ramoz
- Université Paris Cité, Institute of Psychiatry and Neuroscience of Paris (IPNP), INSERM U1266, Paris 75014, France; GHU Paris Psychiatrie et Neurosciences, CMME, Hôpital Sainte-Anne, Paris F-75014, France
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2
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Towers EB, Lynch WJ. The importance of examining sex differences in animal models validated to induce an addiction-like phenotype. Pharmacol Biochem Behav 2021; 209:173255. [PMID: 34416219 PMCID: PMC8456716 DOI: 10.1016/j.pbb.2021.173255] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Accepted: 08/11/2021] [Indexed: 11/22/2022]
Affiliation(s)
- Eleanor Blair Towers
- Psychiatry and Neurobehavioral Sciences, University of Virginia, Charlottesville, VA, United States of America.
| | - Wendy J Lynch
- Psychiatry and Neurobehavioral Sciences, University of Virginia, Charlottesville, VA, United States of America
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3
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Evaluation of tradipitant, a selective NK1 antagonist, on response to oxycodone in humans. Psychopharmacology (Berl) 2021; 238:1857-1866. [PMID: 33988725 PMCID: PMC8120018 DOI: 10.1007/s00213-021-05814-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/07/2021] [Accepted: 03/01/2021] [Indexed: 12/24/2022]
Abstract
RATIONALE Preclinical studies demonstrate that the NK1 receptor is involved in opioid reinforcement and withdrawal expression. Few studies have examined the impact of treatment with NK1 antagonists on opioid response in humans. OBJECTIVE To explore the potential for a selective NK1 antagonist, tradipitant, to attenuate the abuse liability and reinforcing and analgesic effects of oxycodone in opioid-experienced individuals. METHODS Participants with recreational opioid use, but without opioid physical dependence, were enrolled as inpatients for ~6 weeks (n = 8). A within-subject, double-blind, randomized, placebo-controlled, crossover design was employed. The pharmacodynamic response to intranasal oxycodone across a range of doses (0 to 30 mg) was examined during two counterbalanced maintenance periods (tradipitant 0 or 85 mg/bid). Oxycodone self-administration was assessed with a modified progressive ratio procedure, and analgesia was assessed with the cold pressor test. RESULTS Oxycodone produced significant and dose-related increases on a broad array of prototypic opioid measures, including subjective ratings related to abuse liability (e.g., liking) and physiological outcomes (i.e., expired CO2). Oxycodone self-administration increased with increasing dose, as did analgesia. Tradipitant largely did not alter any of these effects of oxycodone, with the exception of producing a reduction in ratings of desire for opioids. CONCLUSIONS Given that the vast majority of oxycodone effects were unchanged by tradipitant, these data do not provide support for the utility of NK1 antagonists as a potential treatment for opioid use disorder.
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4
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Gutierrez A, Nguyen JD, Creehan KM, Taffe MA. Female rats self-administer heroin by vapor inhalation. Pharmacol Biochem Behav 2020; 199:173061. [PMID: 33164848 PMCID: PMC7725943 DOI: 10.1016/j.pbb.2020.173061] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Revised: 10/14/2020] [Accepted: 10/15/2020] [Indexed: 12/23/2022]
Abstract
Over the last two decades the United States has experienced a significant increase in the medical and non-medical use of opioid drugs, resulting in record numbers of opioid-related overdoses and deaths. There was an initial increase in non-medical use of prescription opioids around 2002, followed later by increased heroin use and then most recently fentanyl. Inhalation is a common route of administration for opioids, with a documented history spanning back to Mediterranean antiquity and up through modern use with e-cigarette devices. Unfortunately, preclinical studies using inhalation as the route of administration remain relatively few. This study was conducted to determine the efficacy of e-cigarette vapor inhalation of heroin in rats. Non-contingent exposure to heroin or methadone vapor produced anti-nociceptive efficacy in male and female rats. Female rats were trained to self-administer heroin vapor; the most-preferring half of the distribution obtained more vapor reinforcers when the concentration of heroin was reduced in the vapor vehicle and when pre-treated with the opioid receptor antagonist naloxone. The anti-nociceptive effect of heroin self-administered by vapor was identical in magnitude to that produced by intravenous self-administration. Finally, anxiety-like behavior increased 24-48 h after last heroin vapor access, consistent with withdrawal signs observed after intravenous self-administration. In sum, these studies show that rewarding and anti-nociceptive effects of heroin are produced in rats by vapor inhalation using e-cigarette technology. Importantly, self-administration models by this route can be deployed to determine health effects of inhaled heroin or other opioids.
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Affiliation(s)
- Arnold Gutierrez
- Department of Neuroscience, The Scripps Research Institute, La Jolla, CA, USA; Department of Psychiatry, University of California, San Diego, La Jolla, CA, USA
| | - Jacques D Nguyen
- Department of Neuroscience, The Scripps Research Institute, La Jolla, CA, USA; Department of Psychiatry, University of California, San Diego, La Jolla, CA, USA
| | - Kevin M Creehan
- Department of Neuroscience, The Scripps Research Institute, La Jolla, CA, USA; Department of Psychiatry, University of California, San Diego, La Jolla, CA, USA
| | - Michael A Taffe
- Department of Neuroscience, The Scripps Research Institute, La Jolla, CA, USA; Department of Psychiatry, University of California, San Diego, La Jolla, CA, USA.
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5
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Stern SA, Bulik CM. Alternative Frameworks for Advancing the Study of Eating Disorders. Trends Neurosci 2020; 43:951-959. [PMID: 33139082 DOI: 10.1016/j.tins.2020.10.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Revised: 09/27/2020] [Accepted: 10/05/2020] [Indexed: 12/20/2022]
Abstract
Eating disorders are life-interrupting psychiatric conditions with high morbidity and mortality, yet the basic mechanisms underlying these conditions are understudied compared with other psychiatric disorders. In this opinion, we suggest that recent knowledge gleaned from genomic and neuroimaging investigations of eating disorders in humans presents a rich opportunity to sharpen animal models of eating disorders and to identify neural mechanisms that contribute to the risk and maintenance of these conditions. Our article reflects the state of the science, with a primary focus on anorexia nervosa (AN) and binge-eating behavior, and encourages further study of all conditions categorized under feeding and eating disorders.
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Affiliation(s)
- Sarah A Stern
- Max Planck Florida Institute for Neuroscience, Jupiter, FL, USA; Department of Molecular Genetics, Rockefeller University, New York, NY, USA
| | - Cynthia M Bulik
- Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA; Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden; Department of Nutrition, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
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6
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Fulenwider HD, Nennig SE, Hafeez H, Price ME, Baruffaldi F, Pravetoni M, Cheng K, Rice KC, Manvich DF, Schank JR. Sex differences in oral oxycodone self-administration and stress-primed reinstatement in rats. Addict Biol 2020; 25:e12822. [PMID: 31830773 DOI: 10.1111/adb.12822] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Revised: 07/08/2019] [Accepted: 07/18/2019] [Indexed: 01/15/2023]
Abstract
The opioid epidemic has become a severe public health problem, with approximately 130 opioid-induced deaths occurring each day in the United States. Prescription opioids are responsible for approximately 40% of these deaths. Oxycodone is one of the most commonly abused prescription opioids, but despite its prevalent misuse, the number of preclinical studies investigating oxycodone-seeking behaviors is relatively limited. Furthermore, preclinical oxycodone studies that include female subjects are even more scarce, and it is critical that future work includes both sexes. Additionally, the oral route of administration is one of the most common routes for recreational users, especially in the early stages of drug experimentation. However, currently, only two studies have been published investigating operant oral oxycodone self-administration in rodents. Therefore, the primary goal of the present study was to establish an oral oxycodone operant self-administration model in adult male and female rats, as well as to examine a potential mechanism of stress-primed reinstatement. We found that females consumed significantly more oral oxycodone than males in operant self-administration sessions. We also found that active oxycodone self-administration was reduced by mu opioid receptor antagonism and by substitution of water for oxycodone solution. Lastly, we induced stress-primed reinstatement and found that this behavior was significantly attenuated by antagonism of the neurokinin-1 receptor, consistent with our prior work examining stress-induced reinstatement of alcohol- and cocaine-seeking.
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Affiliation(s)
- Hannah D. Fulenwider
- Department of Physiology and Pharmacology, College of Veterinary Medicine University of Georgia Athens Georgia USA
| | - Sadie E. Nennig
- Department of Physiology and Pharmacology, College of Veterinary Medicine University of Georgia Athens Georgia USA
| | - Hiba Hafeez
- Department of Physiology and Pharmacology, College of Veterinary Medicine University of Georgia Athens Georgia USA
| | - Michaela E. Price
- Department of Physiology and Pharmacology, College of Veterinary Medicine University of Georgia Athens Georgia USA
| | | | - Marco Pravetoni
- Hennepin Healthcare Research Institute Minneapolis Minnesota USA
- Department of Pharmacology University of Minnesota Medical School Minneapolis Minnesota USA
- Center for Immunology University of Minnesota Medical School Minneapolis Minnesota USA
| | - Kejun Cheng
- Drug Design and Synthesis Section NIH/NIDA/NIAAA Rockville Maryland USA
| | - Kenner C. Rice
- Drug Design and Synthesis Section NIH/NIDA/NIAAA Rockville Maryland USA
| | - Daniel F. Manvich
- Department of Cell Biology and Neuroscience Rowan University School of Osteopathic Medicine Stratford New Jersey USA
| | - Jesse R. Schank
- Department of Physiology and Pharmacology, College of Veterinary Medicine University of Georgia Athens Georgia USA
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7
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Schank JR. Neurokinin receptors in drug and alcohol addiction. Brain Res 2020; 1734:146729. [PMID: 32067964 DOI: 10.1016/j.brainres.2020.146729] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Revised: 02/03/2020] [Accepted: 02/13/2020] [Indexed: 10/25/2022]
Abstract
The neurokinins are a class of peptide signaling molecules that mediate a range of central and peripheral functions including pain processing, gastrointestinal function, stress responses, and anxiety. Recent data have linked these neuropeptides with drug-related behaviors. Specifically, substance P (SP) and neurokinin B (NKB), have been shown to influence responses to alcohol, cocaine, and/or opiate drugs. SP and NKB preferentially bind to the neurokinin-1 receptor (NK1R) and neurokinin-3 receptor (NK3R), respectively, but do have some affinity for all classes of neurokinin receptor at high concentrations. NK1R activity has been shown to influence reward and reinforcement for opiate drugs, stimulatory and neurochemical responses to cocaine, and escalated and stress-induced alcohol seeking. In reinstatement models of relapse-like behavior, NK1R antagonism attenuates stress-induced reinstatement for all classes of drugs tested to date. The NK3R also influences alcohol intake and behavioral/neurochemical responses to cocaine, but less research has been performed in regard to this particular receptor in preclinical models of addiction. Clinically, agents targeting these receptors have shown some promise, but have produced mixed results. Here, the preclinical findings for the NK1R and NK3R are reviewed, and discussion is provided to interpret clinical findings. Additionally, important factors to consider in regards to future clinical work are suggested.
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Affiliation(s)
- Jesse R Schank
- University of Georgia, Department of Physiology and Pharmacology, 501 DW Brooks Drive, Athens, GA 30602, USA.
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8
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Pennington ZT, Trott JM, Rajbhandari AK, Li K, Walwyn WM, Evans CJ, Fanselow MS. Chronic opioid pretreatment potentiates the sensitization of fear learning by trauma. Neuropsychopharmacology 2020; 45:482-490. [PMID: 31787748 PMCID: PMC6968993 DOI: 10.1038/s41386-019-0559-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/21/2019] [Revised: 08/30/2019] [Accepted: 10/23/2019] [Indexed: 11/09/2022]
Abstract
Despite the large comorbidity between PTSD and opioid use disorders, as well as the common treatment of physical injuries resulting from trauma with opioids, the ability of opioid treatments to subsequently modify PTSD-related behavior has not been well studied. Using the stress-enhanced fear learning (SEFL) model for PTSD, we characterized the impact of chronic opioid regimens on the sensitization of fear learning seen following traumatic stress in mice. We demonstrate for the first time that chronic opioid pretreatment is able to robustly augment associative fear learning. Highlighting aversive learning as the cognitive process mediating this behavioral outcome, these changes were observed after a considerable period of drug cessation, generalized to learning about multiple aversive stimuli, were not due to changes in stimulus sensitivity or basal anxiety, and correlated with a marker of synaptic plasticity within the basolateral amygdala. Additionally, these changes were not observed when opioids were given after the traumatic event. Moreover, we found that neither reducing the frequency of opioid administration nor bidirectional manipulation of acute withdrawal impacted the subsequent enhancement in fear learning seen. Given the fundamental role of associative fear learning in the generation and progression of PTSD, these findings are of direct translational relevance to the comorbidity between opioid dependence and PTSD, and they are also pertinent to the use of opioids for treating pain resulting from traumas involving physical injuries.
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Affiliation(s)
- Zachary T. Pennington
- 0000 0000 9632 6718grid.19006.3eDepartment of Psychology, University of California, Los Angeles, CA USA ,0000 0000 9632 6718grid.19006.3eStaglin Center for Brain and Behavioral Health, University of California, Los Angeles, CA USA ,0000 0001 0670 2351grid.59734.3cDepartment of Neuroscience, Mount Sinai School of Medicine, New York, NY USA
| | - Jeremy M. Trott
- 0000 0000 9632 6718grid.19006.3eDepartment of Psychology, University of California, Los Angeles, CA USA ,0000 0000 9632 6718grid.19006.3eStaglin Center for Brain and Behavioral Health, University of California, Los Angeles, CA USA
| | - Abha K. Rajbhandari
- 0000 0000 9632 6718grid.19006.3eDepartment of Psychology, University of California, Los Angeles, CA USA ,0000 0000 9632 6718grid.19006.3eStaglin Center for Brain and Behavioral Health, University of California, Los Angeles, CA USA
| | - Kevin Li
- 0000 0000 9632 6718grid.19006.3eDepartment of Psychology, University of California, Los Angeles, CA USA
| | - Wendy M. Walwyn
- 0000 0000 9632 6718grid.19006.3eDepartment of Psychiatry and Biobehavioral Sciences, University of California, Los Angeles, CA USA ,0000 0000 9632 6718grid.19006.3eHatos Center for Neuropharmacology, University of California, Los Angeles, CA USA
| | - Christopher J. Evans
- 0000 0000 9632 6718grid.19006.3eDepartment of Psychiatry and Biobehavioral Sciences, University of California, Los Angeles, CA USA ,0000 0000 9632 6718grid.19006.3eHatos Center for Neuropharmacology, University of California, Los Angeles, CA USA
| | - Michael S. Fanselow
- 0000 0000 9632 6718grid.19006.3eDepartment of Psychology, University of California, Los Angeles, CA USA ,0000 0000 9632 6718grid.19006.3eStaglin Center for Brain and Behavioral Health, University of California, Los Angeles, CA USA ,0000 0000 9632 6718grid.19006.3eDepartment of Psychiatry and Biobehavioral Sciences, University of California, Los Angeles, CA USA
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9
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Addiction and stress: An allostatic view. Neurosci Biobehav Rev 2019; 106:245-262. [DOI: 10.1016/j.neubiorev.2018.09.008] [Citation(s) in RCA: 121] [Impact Index Per Article: 24.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2018] [Revised: 08/30/2018] [Accepted: 09/08/2018] [Indexed: 01/24/2023]
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10
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Maussion G, Demirova I, Gorwood P, Ramoz N. Induced Pluripotent Stem Cells; New Tools for Investigating Molecular Mechanisms in Anorexia Nervosa. Front Nutr 2019; 6:118. [PMID: 31457016 PMCID: PMC6700384 DOI: 10.3389/fnut.2019.00118] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2019] [Accepted: 07/17/2019] [Indexed: 12/11/2022] Open
Abstract
Anorexia nervosa (AN) is a dramatic psychiatric disorder characterized by dysregulations in food intake and reward processing, involving molecular and cellular changes in several peripheral cell types and central neuronal networks. Genomic and epigenomic analyses have allowed the identification of multiple genetic and epigenetic modifications highlighting the complex pathophysiology of AN. Behavioral and genetic rodent models have been used to recapitulate and investigate, with some limitations, the cellular and molecular changes that potentially underlie eating disorders. In the last 5 years, the use of induced pluripotent stem cells (IPSCs), combined with CRISPR-Cas9 technology, has led to the generation of specific neuronal cell subtypes engineered from human somatic samples, representing a powerful tool to complement observations made in human samples and data collected from animal models. Systems biology using IPSCs has indeed proved to be a valuable approach for the study of metabolic disorders, in addition to neurodevelopmental and psychiatric disorders. The manuscript, while reviewing the main findings related to the genetic, epigenetic, and cellular bases of AN, will present how new studies published, or to be performed, in the field of IPSC-derived cells should improve our current understanding of the pathophysiology of AN and provide potential therapeutic strategies addressing specific endophenotypes.
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Affiliation(s)
- Gilles Maussion
- Montreal Neurological Institute and Hospital, McGill University, Montreal, QC, Canada
| | - Iveta Demirova
- Montreal Neurological Institute and Hospital, McGill University, Montreal, QC, Canada
| | - Philip Gorwood
- INSERM U1266, Institute of Psychiatry and Neuroscience of Paris, Paris, France.,Hôpital Sainte-Anne (CMME), University Paris-Descartes, Paris, France
| | - Nicolas Ramoz
- INSERM U1266, Institute of Psychiatry and Neuroscience of Paris, Paris, France
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11
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Male and female mice develop escalation of heroin intake and dependence following extended access. Neuropharmacology 2019; 151:189-194. [PMID: 30880124 DOI: 10.1016/j.neuropharm.2019.03.019] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2018] [Revised: 02/22/2019] [Accepted: 03/13/2019] [Indexed: 12/22/2022]
Abstract
Opioid use disorder is a serious public health issue in the United States. Animal models of opioid dependence are fundamental for studying the etiology of addictive behaviors. We tested the hypothesis that extended access to heroin self-administration leads to increases in heroin intake and produces somatic signs of opioid dependence in both male and female mice. Adult C57BL/6J mice were trained to nosepoke (fixed-ratio 1) to obtain intravenous heroin in six daily 1-h sessions (30-60 μg/kg/infusion). The mice were divided into short access (ShA; 1 h) and long access (LgA; 6 h) groups. Immediately after the 10th escalation session, the mice received a challenge dose of naloxone (1 mg/kg), and somatic signs of withdrawal were recorded. The mice readily acquired intravenous heroin self-administration. LgA mice escalated their drug intake in the first hour across sessions and had significantly higher scores of somatic signs of naloxone-precipitated opioid withdrawal compared with ShA mice. Female mice exhibited increases in heroin intake compared with male mice. Male and female mice exhibited similar levels of somatic signs of withdrawal. Because of the wide availability of genetically modified mouse lines, the present mouse model may be particularly useful for better understanding genetic and sex differences that underlie the transition to compulsive-like opioid taking and seeking.
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12
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Vendruscolo JCM, Tunstall BJ, Carmack SA, Schmeichel BE, Lowery-Gionta EG, Cole M, George O, Vandewater SA, Taffe MA, Koob GF, Vendruscolo LF. Compulsive-Like Sufentanil Vapor Self-Administration in Rats. Neuropsychopharmacology 2018; 43:801-809. [PMID: 28812595 PMCID: PMC5809787 DOI: 10.1038/npp.2017.172] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/18/2017] [Revised: 07/18/2017] [Accepted: 07/26/2017] [Indexed: 11/09/2022]
Abstract
Opioid misuse is at historically high levels in the United States, with inhalation (ie, smoking and vaping) being one of the most common routes of consumption. We developed and validated a novel preclinical model of opioid self-administration by inhalation that does not require surgery and reliably produces somatic and motivational signs of dependence. Rats were trained to perform an operant response (nosepoke) to receive 10 s of vaporized sufentanil, a potent opioid, in 2 h daily sessions. Rats readily and concentration-dependently self-administered vaporized sufentanil. Rats exhibited a significant increase in responding for sufentanil when given the preferential μ-opioid receptor inverse agonist naloxone, suggesting the participation of μ-opioid receptors in the reinforcing properties of sufentanil vapor. Serum sufentanil concentrations significantly correlated with the number of sufentanil vapor deliveries. Rats that were given long access (LgA; 12 h/day) but not short access (ShA; 1 h/day) to vaporized sufentanil escalated their drug intake over time and exhibited both naloxone-precipitated somatic signs of opioid withdrawal and spontaneous withdrawal-induced mechanical hypersensitivity. After 6 months of forced drug abstinence, LgA rats returned to pre-escalation baseline levels of responding for sufentanil and mechanical sensitivity. Upon subsequent re-escalation (ie, after the return to extended access to sufentanil vapor), LgA rats again developed naloxone-precipitated somatic signs of withdrawal and spontaneous withdrawal-induced mechanical hypersensitivity. These findings demonstrate that the operant sufentanil vapor self-administration model has both face and construct validity and therefore will be useful for investigating the neurobiological basis of opioid addiction.
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Affiliation(s)
- Janaina C M Vendruscolo
- Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD, USA
| | - Brendan J Tunstall
- Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD, USA
| | - Stephanie A Carmack
- Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD, USA
| | - Brooke E Schmeichel
- Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD, USA
| | - Emily G Lowery-Gionta
- Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD, USA
| | - Maury Cole
- La Jolla Alcohol Research, La Jolla, CA, USA
| | - Olivier George
- Department of Neuroscience, The Scripps Research Institute, La Jolla, CA, USA
| | - Sophia A Vandewater
- Department of Neuroscience, The Scripps Research Institute, La Jolla, CA, USA
| | - Michael A Taffe
- Department of Neuroscience, The Scripps Research Institute, La Jolla, CA, USA
| | - George F Koob
- Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD, USA
| | - Leandro F Vendruscolo
- Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD, USA,Neurobiology of Addiction Section, NIH/NIDA – IRP/INRB, 251 Bayview Boulevard, BRC Room 08A727, Baltimore, MD 21224, USA, Tel: +1 443 740 2869, Fax: +1 443 740 2827, E-mail:
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13
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Nennig SE, Schank JR. The Role of NFkB in Drug Addiction: Beyond Inflammation. Alcohol Alcohol 2017; 52:172-179. [PMID: 28043969 DOI: 10.1093/alcalc/agw098] [Citation(s) in RCA: 130] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2016] [Indexed: 12/19/2022] Open
Abstract
Aims Nuclear factor kappa light chain enhancer of activated B cells (NFkB) is a ubiquitous transcription factor well known for its role in the innate immune response. As such, NFkB is a transcriptional activator of inflammatory mediators such as cytokines. It has recently been demonstrated that alcohol and other drugs of abuse can induce NFkB activity and cytokine expression in the brain. A number of reviews have been published highlighting this effect of alcohol, and have linked increased NFkB function to neuroimmune-stimulated toxicity. However, in this review we focus on the potentially non-immune functions of NFkB as possible links between NFkB and addiction. Methods An extensive review of the literature via Pubmed searches was used to assess the current state of the field. Results NFkB can induce the expression of a diverse set of gene targets besides inflammatory mediators, some of which are involved in addictive processes, such as opioid receptors and neuropeptides. NFkB mediates complex behaviors including learning and memory, stress responses, anhedonia and drug reward, processes that may lie outside the role of NFkB in the classic neuroimmune response. Conclusions Future studies should focus on these non-immune functions of NFkB signaling and their association with addiction-related processes.
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Affiliation(s)
- S E Nennig
- Department of Physiology and Pharmacology, University of Georgia, 501 D.W. Brooks Drive, Athens, GA 30602, USA
| | - J R Schank
- Department of Physiology and Pharmacology, University of Georgia, 501 D.W. Brooks Drive, Athens, GA 30602, USA
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14
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High-Frequency Stimulation of the Subthalamic Nucleus Blocks Compulsive-Like Re-Escalation of Heroin Taking in Rats. Neuropsychopharmacology 2017; 42:1850-1859. [PMID: 27917870 PMCID: PMC5520777 DOI: 10.1038/npp.2016.270] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Revised: 11/17/2016] [Accepted: 11/22/2016] [Indexed: 11/08/2022]
Abstract
Opioid addiction, including addiction to heroin, has markedly increased in the past decade. The cost and pervasiveness of heroin addiction, including resistance to recovery from addiction, provide a compelling basis for developing novel therapeutic strategies. Deep brain stimulation may represent a viable alternative strategy for the treatment of intractable heroin addiction, particularly in individuals who are resistant to traditional therapies. Here we provide preclinical evidence of the therapeutic potential of high-frequency stimulation of the subthalamic nucleus (STN HFS) for heroin addiction. STN HFS prevented the re-escalation of heroin intake after abstinence in rats with extended access to heroin, an animal model of compulsive heroin taking. STN HFS inhibited key brain regions, including the substantia nigra, entopeduncular nucleus, and nucleus accumbens shell measured using brain mapping analyses of immediate-early gene expression and produced a robust silencing of STN neurons as measured using whole-cell recording ex vivo. These results warrant further investigation to examine the therapeutic effects that STN HFS may have on relapse in humans with heroin addiction.
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Mason BJ. Emerging pharmacotherapies for alcohol use disorder. Neuropharmacology 2017; 122:244-253. [PMID: 28454983 PMCID: PMC5643030 DOI: 10.1016/j.neuropharm.2017.04.032] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2017] [Revised: 04/21/2017] [Accepted: 04/23/2017] [Indexed: 01/29/2023]
Abstract
The identification of different stages within the alcohol use disorder (AUD) cycle that are linked to neurocircuitry changes in pathophysiology associated with the negative emotional states of abstinence has provided a view of medication development for AUD that emphasizes changes in the brain reward and stress systems. Alcohol use disorder can be defined as a chronic relapsing disorder that involves compulsive alcohol seeking and taking, loss of control over alcohol intake, and emergence of a negative emotional state during abstinence. The focus of early medications development was to block the motivation to seek alcohol in the binge/intoxication stage. More recent work has focused on reversing the motivational dysregulations associated with the withdrawal/negative affect and preoccupation/anticipation stages during protracted abstinence. Advances in our understanding of the neurocircuitry and neuropharmacological mechanisms that are involved in the development and maintenance of the withdrawal/negative affect stage using validated animal models have provided viable targets for future medications. Another major advance has been proof-of-concept testing of potential therapeutics and clinical validation of relevant pharmacological targets using human laboratory models of protracted abstinence. This review focuses on future targets for medication development associated with reversal of the loss of reward function and gain in brain stress function that drive negative reinforcement in the withdrawal/negative affect stage of addiction. Basic research has identified novel neurobiological targets associated with the withdrawal/negative affect stage and preoccupation/anticipation stage, with a focus on neuroadaptive changes within the extended amygdala that account for the transition to dependence and vulnerability to relapse. This article is part of the Special Issue entitled "Alcoholism".
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Affiliation(s)
- Barbara J Mason
- The Pearson Center on Alcoholism and Addiction Research, Department of Neuroscience, The Scripps Research Institute, 10550 North Torrey Pines Road, TPC-5 La Jolla, CA 92037 USA.
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Koob GF. Antireward, compulsivity, and addiction: seminal contributions of Dr. Athina Markou to motivational dysregulation in addiction. Psychopharmacology (Berl) 2017; 234:1315-1332. [PMID: 28050629 DOI: 10.1007/s00213-016-4484-6] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/07/2016] [Accepted: 11/08/2016] [Indexed: 02/02/2023]
Abstract
RATIONALE AND OBJECTIVES Addiction is defined as a chronically relapsing disorder characterized by compulsive drug seeking that is hypothesized to derive from multiple sources of motivational dysregulation. METHODS AND RESULTS Dr. Athina Markou made seminal contributions to our understanding of the neurobiology of addiction with her studies on the dysregulation of reward function using animal models with construct validity. Repeated overstimulation of the reward systems with drugs of abuse decreases reward function, characterized by brain stimulation reward and presumbably reflecting dysphoria-like states. The construct of negative reinforcement, defined as drug taking that alleviates a negative emotional state that is created by drug abstinence, is particularly relevant as a driving force in both the withdrawal/negative affect and preoccupation/anticipation stages of the addiction cycle. CONCLUSIONS The negative emotional state that drives such negative reinforcement is hypothesized to derive from the dysregulation of key neurochemical circuits that drive incentive-salience/reward systems (dopamine, opioid peptides) in the ventral striatum and from the recruitment of brain stress systems (corticotropin-releasing factor, dynorphin) within the extended amygdala. As drug taking becomes compulsive-like, the factors that motivate behavior are hypothesized to shift to drug-seeking behavior that is driven not only by positive reinforcement but also by negative reinforcement. This shift in motivation is hypothesized to reflect the allostatic misregulation of hedonic tone such that drug taking makes the hedonic negative emotional state worse during the process of seeking temporary relief with compulsive drug taking.
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Affiliation(s)
- George F Koob
- National Institute on Alcohol Abuse and Alcoholism, 5635 Fishers Lane, Room 2001, Suite 2000, Rockville, MD, 20852, USA.
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Abstract
Addiction has been conceptualized as a three-stage cycle—binge/intoxication, withdrawal/negative affect, and preoccupation/anticipation—that worsens over time and involves allostatic changes in hedonic function via changes in the brain reward and stress systems. Using the withdrawal/negative affect stage and negative reinforcement as an important source of motivation for compulsive drug seeking, we outline the neurobiology of the stress component of the withdrawal/negative affect stage and relate it to a derivative of the Research Domain Criteria research construct for the study of psychiatric disease, known as the Addictions Neuroclinical Assessment. Using the Addictions Neuroclinical Assessment, we outline five subdomains of negative emotional states that can be operationally measured in human laboratory settings and paralleled by animal models. We hypothesize that a focus on negative emotionality and stress is closely related to the acute neurobiological alterations that are experienced in addiction and may serve as a bridge to a reformulation of the addiction nosology to better capture individual differences in patients for whom the withdrawal/negative affect stage drives compulsive drug taking.
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Affiliation(s)
- Laura E Kwako
- National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD, USA
| | - George F Koob
- National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD, USA
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Rinker JA, Mulholland PJ. Promising pharmacogenetic targets for treating alcohol use disorder: evidence from preclinical models. Pharmacogenomics 2017; 18:555-570. [PMID: 28346058 DOI: 10.2217/pgs-2016-0193] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Inherited genetic variants contribute to risk factors for developing an alcohol use disorder, and polymorphisms may inform precision medicine strategies for treating alcohol addiction. Targeting genetic mutations linked to alcohol phenotypes has provided promising initial evidence for reducing relapse rates in alcoholics. Although successful in some studies, there are conflicting findings and the reports of adverse effects may ultimately limit their clinical utility, suggesting that novel pharmacogenetic targets are necessary to advance precision medicine approaches. Here, we describe promising novel genetic variants derived from preclinical models of alcohol consumption and dependence that may uncover disease mechanisms that drive uncontrolled drinking and identify novel pharmacogenetic targets that facilitate therapeutic intervention for the treatment of alcohol use disorder.
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Affiliation(s)
- Jennifer A Rinker
- Department of Neuroscience, Medical University of South Carolina, Charleston, SC 29425, USA.,Department of Psychiatry & Behavioral Sciences, Charleston Alcohol Research Center, Addiction Sciences Division, Medical University of South Carolina, Charleston, SC 29425, USA
| | - Patrick J Mulholland
- Department of Neuroscience, Medical University of South Carolina, Charleston, SC 29425, USA.,Department of Psychiatry & Behavioral Sciences, Charleston Alcohol Research Center, Addiction Sciences Division, Medical University of South Carolina, Charleston, SC 29425, USA
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Schank JR, Heilig M. Substance P and the Neurokinin-1 Receptor: The New CRF. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2017; 136:151-175. [DOI: 10.1016/bs.irn.2017.06.008] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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20
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Dogra S, Sona C, Kumar A, Yadav PN. Epigenetic regulation of G protein coupled receptor signaling and its implications in psychiatric disorders. Int J Biochem Cell Biol 2016; 77:226-39. [PMID: 27046448 DOI: 10.1016/j.biocel.2016.03.012] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2016] [Revised: 03/21/2016] [Accepted: 03/22/2016] [Indexed: 12/21/2022]
Abstract
G protein-coupled receptors (GPCRs) act as a relay center through which extracellular signals, in the form of neurotransmitters or therapeutics, are converted into an intracellular response, which ultimately shapes the overall response at the tissue and behavioral level. Remarkably in similar ways, epigenetic mechanisms also modulate the expression pattern of a large number of genes in response to the dynamic environment inside and outside of the body, and consequently overall response. Emerging evidences from the pharmacogenomics and preclinical studies clearly suggest that these two distinct mechanisms criss-cross each other in several neurological disorders. At one hand such cross-talks between two distinct mechanisms make disease etiology more challenging to understand, while on the other hand if dealt appropriately, such situations might provide an opportunity to find novel druggable target and strategy for the treatment of complex diseases. In this review article, we have summarized and highlighted the main findings that tie epigenetic mechanisms to GPCR mediated signaling in the pathophysiology of central nervous system (CNS) disorders, including depression, addiction and pain.
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Affiliation(s)
- Shalini Dogra
- Division of Pharmacology, CSIR-Central Drug Research Institute, Lucknow, UP 226031, India
| | - Chandan Sona
- Division of Pharmacology, CSIR-Central Drug Research Institute, Lucknow, UP 226031, India
| | - Ajeet Kumar
- Division of Pharmacology, CSIR-Central Drug Research Institute, Lucknow, UP 226031, India
| | - Prem N Yadav
- Division of Pharmacology, CSIR-Central Drug Research Institute, Lucknow, UP 226031, India.
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Koob GF, Mason BJ. Existing and Future Drugs for the Treatment of the Dark Side of Addiction. Annu Rev Pharmacol Toxicol 2015; 56:299-322. [PMID: 26514207 DOI: 10.1146/annurev-pharmtox-010715-103143] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The identification of a heuristic framework for the stages of the addiction cycle that are linked to neurocircuitry changes in pathophysiology includes the binge/intoxication stage, the withdrawal/negative affect stage, and the preoccupation/anticipation (craving) stage, which represent neuroadaptations in three neurocircuits (basal ganglia, extended amygdala, and frontal cortex, respectively). The identification of excellent and validated animal models, the development of human laboratory models, and an enormous surge in our understanding of neurocircuitry and neuropharmacological mechanisms have provided a revisionist view of addiction that emphasizes the loss of brain reward function and gain of stress function that drive negative reinforcement (the dark side of addiction) as a key to compulsive drug seeking. Reversing the dark side of addiction not only explains much of the existing successful pharmacotherapies for addiction but also points to vast new opportunities for future medications to alleviate this major source of human suffering.
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Affiliation(s)
- George F Koob
- Committee on the Neurobiology of Addictive Disorders, The Scripps Research Institute, La Jolla, California 92037; ,
| | - Barbara J Mason
- Committee on the Neurobiology of Addictive Disorders, The Scripps Research Institute, La Jolla, California 92037; ,
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Rodríguez-Arias M, Aguilar MA, Miñarro J. Therapies in early development for the treatment of opiate addiction. Expert Opin Investig Drugs 2015; 24:1459-72. [PMID: 26414784 DOI: 10.1517/13543784.2015.1086746] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
INTRODUCTION Opiate drugs are psychoactive substances used to manage severe pain. However, their chronic use is associated with the development of addiction. Opiate addiction represents a significant public health concern. AREAS COVERED This review focuses on the most recent advances in the pharmacological treatment of opiate addiction, from those being tested in clinical trials (Phase I and II), to preclinical studies that point to new targets. Readers will gain knowledge of the wide variety of treatments used to treat opiate addiction, including their strengths and weaknesses, and the promising pharmacological targets identified by preclinical research. EXPERT OPINION Among the currently available agonist therapies, new dosage forms of buprenorphine can increase patient acceptability and compliance. New extended-release forms of naltrexone are building hope of retaining opiate-dependent subjects in a drug-free state. Unfortunately, the review of the literature shows that successful preclinical studies are often followed by discouraging results in human clinical trials. Nevertheless, all targets of potential interest should be tested exhaustively. Indeed, a number of new targets and research lines (genetics and neuroinflammation approaches) may lead to breakthroughs in the future.
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Affiliation(s)
- Marta Rodríguez-Arias
- a Universidad de Valencia, Unidad de Investigación Psicobiología de las Drogodependencias, Departamento de Psicobiologia , Avda. Blasco Ibáñez 21, 46010 Valencia, Spain +34 9 63 86 40 20 ; +34 9 63 86 46 68 ;
| | - María A Aguilar
- a Universidad de Valencia, Unidad de Investigación Psicobiología de las Drogodependencias, Departamento de Psicobiologia , Avda. Blasco Ibáñez 21, 46010 Valencia, Spain +34 9 63 86 40 20 ; +34 9 63 86 46 68 ;
| | - José Miñarro
- a Universidad de Valencia, Unidad de Investigación Psicobiología de las Drogodependencias, Departamento de Psicobiologia , Avda. Blasco Ibáñez 21, 46010 Valencia, Spain +34 9 63 86 40 20 ; +34 9 63 86 46 68 ;
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Paterson LM, Flechais RSA, Murphy A, Reed LJ, Abbott S, Boyapati V, Elliott R, Erritzoe D, Ersche KD, Faluyi Y, Faravelli L, Fernandez-Egea E, Kalk NJ, Kuchibatla SS, McGonigle J, Metastasio A, Mick I, Nestor L, Orban C, Passetti F, Rabiner EA, Smith DG, Suckling J, Tait R, Taylor EM, Waldman AD, Robbins TW, Deakin JFW, Nutt DJ, Lingford-Hughes AR. The Imperial College Cambridge Manchester (ICCAM) platform study: An experimental medicine platform for evaluating new drugs for relapse prevention in addiction. Part A: Study description. J Psychopharmacol 2015; 29:943-60. [PMID: 26246443 DOI: 10.1177/0269881115596155] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Drug and alcohol dependence are global problems with substantial societal costs. There are few treatments for relapse prevention and therefore a pressing need for further study of brain mechanisms underpinning relapse circuitry. The Imperial College Cambridge Manchester (ICCAM) platform study is an experimental medicine approach to this problem: using functional magnetic resonance imaging (fMRI) techniques and selective pharmacological tools, it aims to explore the neuropharmacology of putative relapse pathways in cocaine, alcohol, opiate dependent, and healthy individuals to inform future drug development. Addiction studies typically involve small samples because of recruitment difficulties and attrition. We established the platform in three centres to assess the feasibility of a multisite approach to address these issues. Pharmacological modulation of reward, impulsivity and emotional reactivity were investigated in a monetary incentive delay task, an inhibitory control task, and an evocative images task, using selective antagonists for µ-opioid, dopamine D3 receptor (DRD3) and neurokinin 1 (NK1) receptors (naltrexone, GSK598809, vofopitant/aprepitant), in a placebo-controlled, randomised, crossover design. In two years, 609 scans were performed, with 155 individuals scanned at baseline. Attrition was low and the majority of individuals were sufficiently motivated to complete all five sessions (n=87). We describe herein the study design, main aims, recruitment numbers, sample characteristics, and explain the test hypotheses and anticipated study outputs.
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Affiliation(s)
- Louise M Paterson
- Centre for Neuropsychopharmacology, Imperial College London, London, UK
| | - Remy S A Flechais
- Centre for Neuropsychopharmacology, Imperial College London, London, UK
| | - Anna Murphy
- Neuroscience and Psychiatry Unit, University of Manchester, Manchester, UK
| | - Laurence J Reed
- Centre for Neuropsychopharmacology, Imperial College London, London, UK
| | - Sanja Abbott
- Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge, UK
| | | | - Rebecca Elliott
- Neuroscience and Psychiatry Unit, University of Manchester, Manchester, UK
| | - David Erritzoe
- Centre for Neuropsychopharmacology, Imperial College London, London, UK
| | - Karen D Ersche
- Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge, UK Department of Psychiatry, University of Cambridge, Cambridge, UK
| | - Yetunde Faluyi
- Cambridgeshire and Peterborough NHS Foundation Trust, Cambridge, UK
| | - Luca Faravelli
- Centre for Neuropsychopharmacology, Imperial College London, London, UK
| | - Emilio Fernandez-Egea
- Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge, UK Cambridgeshire and Peterborough NHS Foundation Trust, Cambridge, UK
| | - Nicola J Kalk
- Centre for Neuropsychopharmacology, Imperial College London, London, UK
| | | | - John McGonigle
- Centre for Neuropsychopharmacology, Imperial College London, London, UK
| | - Antonio Metastasio
- Neuroscience and Psychiatry Unit, University of Manchester, Manchester, UK 5 Boroughs Partnership NHS Foundation Trust, Warrington, UK
| | - Inge Mick
- Centre for Neuropsychopharmacology, Imperial College London, London, UK
| | - Liam Nestor
- Centre for Neuropsychopharmacology, Imperial College London, London, UK Clinical Research Unit, GlaxoSmithKline, Cambridge, UK
| | - Csaba Orban
- Centre for Neuropsychopharmacology, Imperial College London, London, UK
| | - Filippo Passetti
- Centre for Neuropsychopharmacology, Imperial College London, London, UK Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge, UK Department of Psychiatry, University of Cambridge, Cambridge, UK
| | | | - Dana G Smith
- Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge, UK Department of Psychology, University of Cambridge, Cambridge, UK
| | - John Suckling
- Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge, UK Cambridgeshire and Peterborough NHS Foundation Trust, Cambridge, UK
| | - Roger Tait
- Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge, UK
| | - Eleanor M Taylor
- Neuroscience and Psychiatry Unit, University of Manchester, Manchester, UK
| | - Adam D Waldman
- Centre for Neuroinflammation and Neurodegeneration, Imperial College London, London, UK
| | - Trevor W Robbins
- Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge, UK Department of Psychology, University of Cambridge, Cambridge, UK
| | - J F William Deakin
- Neuroscience and Psychiatry Unit, University of Manchester, Manchester, UK
| | - David J Nutt
- Centre for Neuropsychopharmacology, Imperial College London, London, UK
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Koob GF. The dark side of emotion: the addiction perspective. Eur J Pharmacol 2015; 753:73-87. [PMID: 25583178 PMCID: PMC4380644 DOI: 10.1016/j.ejphar.2014.11.044] [Citation(s) in RCA: 232] [Impact Index Per Article: 25.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2014] [Revised: 11/06/2014] [Accepted: 11/26/2014] [Indexed: 01/04/2023]
Abstract
Emotions are "feeling" states and classic physiological emotive responses that are interpreted based on the history of the organism and the context. Motivation is a persistent state that leads to organized activity. Both are intervening variables and intimately related and have neural representations in the brain. The present thesis is that drugs of abuse elicit powerful emotions that can be interwoven conceptually into this framework. Such emotions range from pronounced euphoria to a devastating negative emotional state that in the extreme can create a break with homeostasis and thus an allostatic hedonic state that has been considered key to the etiology and maintenance of the pathophysiology of addiction. Drug addiction can be defined as a three-stage cycle-binge/intoxication, withdrawal/negative affect, and preoccupation/anticipation-that involves allostatic changes in the brain reward and stress systems. Two primary sources of reinforcement, positive and negative reinforcement, have been hypothesized to play a role in this allostatic process. The negative emotional state that drives negative reinforcement is hypothesized to derive from dysregulation of key neurochemical elements involved in the brain incentive salience and stress systems. Specific neurochemical elements in these structures include not only decreases in incentive salience system function in the ventral striatum (within-system opponent processes) but also recruitment of the brain stress systems mediated by corticotropin-releasing factor (CRF), dynorphin-κ opioid systems, and norepinephrine, vasopressin, hypocretin, and substance P in the extended amygdala (between-system opponent processes). Neuropeptide Y, a powerful anti-stress neurotransmitter, has a profile of action on compulsive-like responding for drugs similar to a CRF1 receptor antagonist. Other stress buffers include nociceptin and endocannabinoids, which may also work through interactions with the extended amygdala. The thesis argued here is that the brain has specific neurochemical neurocircuitry coded by the hedonic extremes of pleasant and unpleasant emotions that have been identified through the study of opponent processes in the domain of addiction. These neurochemical systems need to be considered in the context of the framework that emotions involve the specific brain regions now identified to differentially interpreting emotive physiological expression.
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Affiliation(s)
- George F Koob
- National Institute on Alcohol Abuse and Alcoholism, Washington, DC, USA.
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Abstract
Stress in life is unavoidable, affecting everyone on a daily basis. Psychological stress in mammals triggers a rapidly organized response for survival, but it may also cause a variety of behavioral disorders and damage cognitive function. Stress is associated with biases in cognitive processing; some of the most enduring memories are formed by traumatic events. Our understanding of how cognition is shaped by stress is still relatively primitive; however, evidence is rapidly accumulating that the 'mature' brain has a great capacity for plasticity and that there are numerous ways through which pharmacological therapeutics could rescue cognitive function and regain cognitive balance. In this review, we discuss recent advances in our understanding of the interplay between stress and cognitive processes and potential therapeutic approaches to stress-related behavioral and cognitive disorders.
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Schmeichel BE, Barbier E, Misra KK, Contet C, Schlosburg JE, Grigoriadis D, Williams JP, Karlsson C, Pitcairn C, Heilig M, Koob GF, Vendruscolo LF. Hypocretin receptor 2 antagonism dose-dependently reduces escalated heroin self-administration in rats. Neuropsychopharmacology 2015; 40:1123-9. [PMID: 25367502 PMCID: PMC4367454 DOI: 10.1038/npp.2014.293] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/16/2014] [Revised: 09/29/2014] [Accepted: 09/30/2014] [Indexed: 02/07/2023]
Abstract
The hypocretin/orexin (HCRT) system has been associated with both positive and negative drug reinforcement, implicating HCRT receptor 1 (HCRT-R1) signaling in drug-related behaviors for all major drug classes, including opioids. However, to date there are limited studies investigating the role of HCRT receptor 2 (HCRT-R2) signaling in compulsive-like drug seeking. Escalation of drug intake with extended access has been suggested to model the transition from controlled drug use to compulsive-like drug seeking/taking. The current study examined the effects of a HCRT-R2 antagonist, NBI-80713, on heroin self-administration in rats allowed short- (1 h; ShA) or long- (12 h; LgA) access to intravenous heroin self-administration. Results indicate that systemically administered NBI-80713 dose-dependently decreased heroin self-administration in LgA, but not in ShA, animals. Quantitative PCR analyses showed an increase in Hcrtr2 mRNA levels in the central amygdala, a stress-related brain region, of LgA rats. These observations suggest a functional role for HCRT-R2 signaling in compulsive-like heroin self-administration associated with extended access and indicate HCRT-R2 antagonism as a potential pharmacological target for the treatment of heroin dependence.
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Affiliation(s)
- Brooke E Schmeichel
- Committee on the Neurobiology of Addictive Disorders, The Scripps Research Institute, La Jolla, CA, USA
| | - Estelle Barbier
- Laboratories of Neurogenetics and Clinical and Translational Studies, Laboratory for Integrative Neuroscience, National Institute on Alcohol Abuse and Alcoholism, Bethesda, MD, USA
| | - Kaushik K Misra
- Committee on the Neurobiology of Addictive Disorders, The Scripps Research Institute, La Jolla, CA, USA
| | - Candice Contet
- Committee on the Neurobiology of Addictive Disorders, The Scripps Research Institute, La Jolla, CA, USA
| | - Joel E Schlosburg
- Committee on the Neurobiology of Addictive Disorders, The Scripps Research Institute, La Jolla, CA, USA
| | | | | | - Camilla Karlsson
- Laboratories of Neurogenetics and Clinical and Translational Studies, Laboratory for Integrative Neuroscience, National Institute on Alcohol Abuse and Alcoholism, Bethesda, MD, USA
| | - Caleb Pitcairn
- Laboratories of Neurogenetics and Clinical and Translational Studies, Laboratory for Integrative Neuroscience, National Institute on Alcohol Abuse and Alcoholism, Bethesda, MD, USA
| | - Markus Heilig
- Laboratories of Neurogenetics and Clinical and Translational Studies, Laboratory for Integrative Neuroscience, National Institute on Alcohol Abuse and Alcoholism, Bethesda, MD, USA
| | - George F Koob
- Committee on the Neurobiology of Addictive Disorders, The Scripps Research Institute, La Jolla, CA, USA
| | - Leandro F Vendruscolo
- Committee on the Neurobiology of Addictive Disorders, The Scripps Research Institute, La Jolla, CA, USA
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Polymorphism in the corticotropin-releasing factor receptor 1 (CRF1-R) gene plays a role in shaping the high anxious phenotype of Marchigian Sardinian alcohol-preferring (msP) rats. Psychopharmacology (Berl) 2015; 232:1083-93. [PMID: 25260340 PMCID: PMC4339612 DOI: 10.1007/s00213-014-3743-7] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/06/2014] [Accepted: 09/10/2014] [Indexed: 10/24/2022]
Abstract
INTRODUCTION Marchigian Sardinian alcohol-preferring (msP) rats exhibit innate preference for alcohol along with anxious phenotype. In these animals, two single-nucleotide polymorphisms in position -1,836 and -2,097 from the first start codon of the CRF1-R transcript have been found. MATERIALS AND METHODS Here, we examined whether these point mutations account for the heightened anxiety-like behavior and stress responsiveness of msP rats. We rederived the msP rats to obtain two distinct lines carrying the wild-type (GG) and point mutations (AA), respectively. RESULTS CRF1-R gene expression analysis revealed significant dysregulation of the system in the extended amygdala of AA rats. At the behavioral level, using the elevated plus maze, we found that both AA and GG lines had higher basal anxiety compared to Wistar rats. In the defensive burying test, AA rats showed decreased burying behavior compared to the GG and the unselected Wistar lines. Freezing/immobility did not differ among AA and GG but was higher than that of Wistars. The selective CRF1-R antagonist antalarmin (0, 10, and 20 mg/kg) reduced burying behavior in Wistar animals. However, antalarmin (10 mg/kg) tended to increase rather than reducing this behavior when tested in the msP lines, an effect that appeared more marked in the GG as compared to the AA line. CONCLUSION The present data suggest that rats with msP genetic background are more anxious and show different sensitivity to stress and CRF1-R blockade than Wistars. The point mutations occurring in the CRF1-R gene do not seem to influence basal anxiety while they appear to affect active responses to stress.
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Wade CL, Vendruscolo LF, Schlosburg JE, Hernandez DO, Koob GF. Compulsive-like responding for opioid analgesics in rats with extended access. Neuropsychopharmacology 2015; 40:421-8. [PMID: 25060491 PMCID: PMC4443956 DOI: 10.1038/npp.2014.188] [Citation(s) in RCA: 105] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/12/2014] [Revised: 07/14/2014] [Accepted: 07/15/2014] [Indexed: 11/09/2022]
Abstract
The abuse of prescription opioids that are used for the treatment of chronic pain is a major public health concern, costing ∼$53.4 billion annually in lost wages, health-care costs, and criminal costs. Although opioids remain a first-line therapy for the treatment of severe chronic pain, practitioners remain cautious because of the potential for abuse and addiction. Opioids such as heroin are considered very rewarding and reinforcing, but direct and systematic comparisons of compulsive intake between commonly prescribed opioids and heroin in animal models have not yet been performed. In the present study, we evaluated the potential for compulsive-like drug seeking and taking, using intravenous self-administration of oxycodone, fentanyl, and buprenorphine in rats allowed long access sessions (12 h). We measured compulsive-like intake using an established escalation model and responding on a progressive ratio schedule of reinforcement. We compared the potential for compulsive-like self-administration of these prescription opioids and heroin, which has been previously established to induce increasing intake that models the transition to addiction in humans. We found that animals that self-administered oxycodone, fentanyl, or heroin, but not buprenorphine had similar profiles of escalation and increases in breakpoints. The use of extended access models of prescription opioid intake will help better understand the biological factors that underlie opioid dependence.
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Affiliation(s)
- Carrie L Wade
- Committee on the Neurobiology of Addictive Disorders, The Scripps Research Institute, La Jolla, CA, USA,Committee on the Neurobiology of Addictive Disorders, The Scripps Research Institute, 10550 North Torrey Pines Road, SP30-2400, La Jolla, CA 92037, USA, Tel: +1 858 784 8030, Fax: +1 858 784 7405, E-mail:
| | - Leandro F Vendruscolo
- Committee on the Neurobiology of Addictive Disorders, The Scripps Research Institute, La Jolla, CA, USA
| | - Joel E Schlosburg
- Committee on the Neurobiology of Addictive Disorders, The Scripps Research Institute, La Jolla, CA, USA
| | - Daniel O Hernandez
- Committee on the Neurobiology of Addictive Disorders, The Scripps Research Institute, La Jolla, CA, USA
| | - George F Koob
- Committee on the Neurobiology of Addictive Disorders, The Scripps Research Institute, La Jolla, CA, USA
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29
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Abstract
This paper is the thirty-sixth consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2013 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior, and the roles of these opioid peptides and receptors in pain and analgesia; stress and social status; tolerance and dependence; learning and memory; eating and drinking; alcohol and drugs of abuse; sexual activity and hormones, pregnancy, development and endocrinology; mental illness and mood; seizures and neurologic disorders; electrical-related activity and neurophysiology; general activity and locomotion; gastrointestinal, renal and hepatic functions; cardiovascular responses; respiration and thermoregulation; and immunological responses.
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Affiliation(s)
- Richard J Bodnar
- Department of Psychology and Neuropsychology Doctoral Sub-Program, Queens College, City University of New York, Flushing, NY 11367, United States.
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30
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Hillemacher T, Leggio L, Heberlein A. Investigational therapies for the pharmacological treatment of alcoholism. Expert Opin Investig Drugs 2014; 24:17-30. [PMID: 25164385 DOI: 10.1517/13543784.2014.954037] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Introduction: Alcohol dependence is one of the most important psychiatric disorders leading to enormous harm in individuals and indeed within society. Yet, although alcohol dependence is a disease of significant importance, the availability of efficacious pharmacological treatment is still limited. Areas covered: The current review focuses on neurobiological pathways that are the rationale for recent preclinical and clinical studies testing novel compounds that could be used as treatments for alcohol dependence. These neurobiological mechanisms include the: glutamatergic, dopaminergic and GABA mediated pathways as well as neuroendocrine systems. There is also an interest in the approaches for influencing chromatin structure. Expert opinion: There are several compounds in Phase I and Phase II clinical studies that have produced potentially useful results for the treating alcoholism. Further evaluation is still necessary, and the implementation of Phase III studies will help to elucidate the usefulness of these compounds. It is important that personalized approaches (e.g., pharmacogenomics) are investigated in these later studies, as the efficacy of different compounds may vary substantially between subgroups of patients.
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Affiliation(s)
- Thomas Hillemacher
- Hannover Medical School, Center for Addiction Research (CARe), Department of Psychiatry, Social Psychiatry and Psychotherapy , Carl-Neuberg-Str. 1, 30625 Hannover , Germany +49 511 532 2427 ; +49 511 532 2415 ;
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31
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Abstract
Stress can trigger drug-seeking behavior, increase self-administration rates, and enhance drug reward. A number of stress-related neuropeptides have been shown to mediate these behavioral processes. The most studied peptide in this category is corticotropin-releasing hormone (CRH), which has been shown to mediate stress-induced reinstatement of drug seeking, escalated self-administration, and drug withdrawal, but it does not seem to be involved in baseline drug self-administration or cue-induced reinstatement. This pattern of effects holds for many classes of drugs, including alcohol, opiates, and psychostimulants. The neurokinin-1 receptor (NK1R) is the preferred receptor for the endogenous stress-related neuropeptide substance P (SP). The SP/NK1R system is a major mediator of stress and anxiety, and over the last several years, it has been demonstrated that the SP/NK1R system can have effects similar to those of CRH on drug taking and drug seeking. Specifically, NK1R inhibition attenuates escalated self-administration of alcohol as well as stress-induced reinstatement of alcohol and cocaine seeking; however, in contrast to other stress systems, the NK1R also appears to have a role in primary reward and reinforcement for opiates. This review outlines the role of NK1R in drug-seeking behaviors and highlights recent results from clinical studies that suggest that the NK1R may be a promising drug target going forward.
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Affiliation(s)
- Jesse R Schank
- Department of Physiology and Pharmacology, College of Veterinary Medicine, University of Georgia, Athens, Georgia
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32
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Schank JR, King CE, Sun H, Cheng K, Rice KC, Heilig M, Weinshenker D, Schroeder JP. The role of the neurokinin-1 receptor in stress-induced reinstatement of alcohol and cocaine seeking. Neuropsychopharmacology 2014; 39:1093-101. [PMID: 24173499 PMCID: PMC3957103 DOI: 10.1038/npp.2013.309] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/05/2013] [Revised: 09/20/2013] [Accepted: 10/03/2013] [Indexed: 12/15/2022]
Abstract
Neurokinin-1 receptors (NK1Rs) have been shown to mediate alcohol and opiate, but not cocaine reward in rodents. We recently reported that NK1R antagonism also blocks stress-induced reinstatement of alcohol seeking in rats, but it is presently unknown whether these antirelapse properties extend to other drug classes. Although some work has suggested that intracranial substance P (SP) infusion reinstates cocaine seeking following extinction, no studies have indicated a direct role for the NK1R in reinstatement of cocaine seeking. Here, we explored the effect of the NK1R antagonist L822429 on yohimbine-induced reinstatement of alcohol or cocaine seeking in Long-Evans rats. Consistent with our previous findings with footshock-induced reinstatement of alcohol seeking in Wistar rats, we found that L822429 attenuates yohimbine-induced reinstatement of alcohol seeking, but does not affect baseline alcohol self-administration. We observed a similar suppression of yohimbine-induced reinstatement of cocaine seeking by L822429, and found that Long-Evans rats exhibit greater sensitivity to NK1R antagonism than Wistar rats. Accordingly, Long-Evans rats exhibit differences in the expression of NK1Rs in some subcortical brain regions. Combined, our findings suggest that while NK1R antagonism differentially influences alcohol- and cocaine-related behavior, this receptor mediates stress-induced seeking of both drugs.
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Affiliation(s)
- Jesse R Schank
- Laboratory of Clinical and Translational Studies, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD, USA,National Institute on Alcohol Abuse and Alcoholism, Laboratory of Clinical and Translational Studies, National Institutes of Health, 10 Center Drive, Building 10-CRC, Room 1-5330, Bethesda, MD 20892-1108, USA, Tel: +1 301 402 5305, Fax: +1 301 402 0445, E-mail:
| | - Courtney E King
- Laboratory of Clinical and Translational Studies, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD, USA
| | - Hui Sun
- Laboratory of Clinical and Translational Studies, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD, USA
| | - Kejun Cheng
- Chemical Biology Branch, National Institute on Alcohol Abuse and Alcoholism and National Institute on Drug Abuse, National Institutes of Health, Bethesda, MD, USA
| | - Kenner C Rice
- Chemical Biology Branch, National Institute on Alcohol Abuse and Alcoholism and National Institute on Drug Abuse, National Institutes of Health, Bethesda, MD, USA
| | - Markus Heilig
- Laboratory of Clinical and Translational Studies, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD, USA
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33
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Steinhoff MS, von Mentzer B, Geppetti P, Pothoulakis C, Bunnett NW. Tachykinins and their receptors: contributions to physiological control and the mechanisms of disease. Physiol Rev 2014; 94:265-301. [PMID: 24382888 DOI: 10.1152/physrev.00031.2013] [Citation(s) in RCA: 413] [Impact Index Per Article: 41.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
The tachykinins, exemplified by substance P, are one of the most intensively studied neuropeptide families. They comprise a series of structurally related peptides that derive from alternate processing of three Tac genes and are expressed throughout the nervous and immune systems. Tachykinins interact with three neurokinin G protein-coupled receptors. The signaling, trafficking, and regulation of neurokinin receptors have also been topics of intense study. Tachykinins participate in important physiological processes in the nervous, immune, gastrointestinal, respiratory, urogenital, and dermal systems, including inflammation, nociception, smooth muscle contractility, epithelial secretion, and proliferation. They contribute to multiple diseases processes, including acute and chronic inflammation and pain, fibrosis, affective and addictive disorders, functional disorders of the intestine and urinary bladder, infection, and cancer. Neurokinin receptor antagonists are selective, potent, and show efficacy in models of disease. In clinical trials there is a singular success: neurokinin 1 receptor antagonists to treat nausea and vomiting. New information about the involvement of tachykinins in infection, fibrosis, and pruritus justifies further trials. A deeper understanding of disease mechanisms is required for the development of more predictive experimental models, and for the design and interpretation of clinical trials. Knowledge of neurokinin receptor structure, and the development of targeting strategies to disrupt disease-relevant subcellular signaling of neurokinin receptors, may refine the next generation of neurokinin receptor antagonists.
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34
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Long-term antagonism of κ opioid receptors prevents escalation of and increased motivation for heroin intake. J Neurosci 2014; 33:19384-92. [PMID: 24305833 DOI: 10.1523/jneurosci.1979-13.2013] [Citation(s) in RCA: 92] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
The abuse of opioid drugs, both illicit and prescription, is a persistent problem in the United States, accounting for >1.2 million users who require treatment each year. Current treatments rely on suppressing immediate withdrawal symptoms and replacing illicit drug use with long-acting opiate drugs. However, the mechanisms that lead to preventing opiate dependence are still poorly understood. We hypothesized that κ opioid receptor (KOR) activation during chronic opioid intake contributes to negative affective states associated with withdrawal and the motivation to take increasing amounts of heroin. Using a 12 h long-access model of heroin self-administration, rats showed escalation of heroin intake over several weeks. This was prevented by a single high dose (30 mg/kg) of the long-acting KOR antagonist norbinaltorphimine (nor-BNI), paralleled by reduced motivation to respond for heroin on a progressive-ratio schedule of reinforcement, a measure of compulsive-like responding. Systemic nor-BNI also significantly decreased heroin withdrawal-associated anxiety-like behavior. Immunohistochemical analysis showed prodynorphin content increased in the nucleus accumbens core in all heroin-exposed rats, but selectively increased in the nucleus accumbens shell in long-access rats. Local infusion of nor-BNI (4 μg/side) into accumbens core altered the initial intake of heroin but not the rate of escalation, while local injection into accumbens shell selectively suppressed increases in heroin intake over time without altering initial intake. These data suggest that dynorphin activity in the nucleus accumbens mediates the increasing motivation for heroin taking and compulsive-like responding for heroin, suggesting that KOR antagonists may be promising targets for the treatment of opioid addiction.
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35
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Koob GF, Buck CL, Cohen A, Edwards S, Park PE, Schlosburg JE, Schmeichel B, Vendruscolo LF, Wade CL, Whitfield TW, George O. Addiction as a stress surfeit disorder. Neuropharmacology 2014; 76 Pt B:370-82. [PMID: 23747571 PMCID: PMC3830720 DOI: 10.1016/j.neuropharm.2013.05.024] [Citation(s) in RCA: 344] [Impact Index Per Article: 34.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2013] [Revised: 05/22/2013] [Accepted: 05/28/2013] [Indexed: 12/15/2022]
Abstract
Drug addiction has been conceptualized as a chronically relapsing disorder of compulsive drug seeking and taking that progresses through three stages: binge/intoxication, withdrawal/negative affect, and preoccupation/anticipation. Drug addiction impacts multiple motivational mechanisms and can be conceptualized as a disorder that progresses from positive reinforcement (binge/intoxication stage) to negative reinforcement (withdrawal/negative affect stage). The construct of negative reinforcement is defined as drug taking that alleviates a negative emotional state. Our hypothesis is that the negative emotional state that drives such negative reinforcement is derived from dysregulation of key neurochemical elements involved in the brain stress systems within the frontal cortex, ventral striatum, and extended amygdala. Specific neurochemical elements in these structures include not only recruitment of the classic stress axis mediated by corticotropin-releasing factor (CRF) in the extended amygdala as previously hypothesized but also recruitment of dynorphin-κ opioid aversive systems in the ventral striatum and extended amygdala. Additionally, we hypothesized that these brain stress systems may be engaged in the frontal cortex early in the addiction process. Excessive drug taking engages activation of CRF not only in the extended amygdala, accompanied by anxiety-like states, but also in the medial prefrontal cortex, accompanied by deficits in executive function that may facilitate the transition to compulsive-like responding. Excessive activation of the nucleus accumbens via the release of mesocorticolimbic dopamine or activation of opioid receptors has long been hypothesized to subsequently activate the dynorphin-κ opioid system, which in turn can decrease dopaminergic activity in the mesocorticolimbic dopamine system. Blockade of the κ opioid system can also block anxiety-like and reward deficits associated with withdrawal from drugs of abuse and block the development of compulsive-like responding during extended access to drugs of abuse, suggesting another powerful brain stress/anti-reward system that contributes to compulsive drug seeking. Thus, brain stress response systems are hypothesized to be activated by acute excessive drug intake, to be sensitized during repeated withdrawal, to persist into protracted abstinence, and to contribute to the development and persistence of addiction. The recruitment of anti-reward systems provides a powerful neurochemical basis for the negative emotional states that are responsible for the dark side of addiction. This article is part of a Special Issue entitled 'NIDA 40th Anniversary Issue'.
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Affiliation(s)
- George F Koob
- Committee on the Neurobiology of Addictive Disorders, The Scripps Research Institute, 10550 North Torrey Pines Road, SP30-2400, La Jolla, CA 92037, USA.
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36
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Abstract
Drug addiction can be defined by a three-stage cycle - binge/intoxication, withdrawal/negative affect, and preoccupation/anticipation - that involves allostatic changes in the brain reward and stress systems. Two primary sources of reinforcement, positive and negative reinforcement, have been hypothesized to play a role in this allostatic process. The negative emotional state that drives negative reinforcement is hypothesized to derive from dysregulation of key neurochemical elements involved in the brain reward and stress systems. Specific neurochemical elements in these structures include not only decreases in reward system function (within-system opponent processes) but also recruitment of the brain stress systems mediated by corticotropin-releasing factor (CRF) and dynorphin-κ opioid systems in the ventral striatum, extended amygdala, and frontal cortex (both between-system opponent processes). CRF antagonists block anxiety-like responses associated with withdrawal, block increases in reward thresholds produced by withdrawal from drugs of abuse, and block compulsive-like drug taking during extended access. Excessive drug taking also engages the activation of CRF in the medial prefrontal cortex, paralleled by deficits in executive function that may facilitate the transition to compulsive-like responding. Neuropeptide Y, a powerful anti-stress neurotransmitter, has a profile of action on compulsive-like responding for ethanol similar to a CRF1 antagonist. Blockade of the κ opioid system can also block dysphoric-like effects associated with withdrawal from drugs of abuse and block the development of compulsive-like responding during extended access to drugs of abuse, suggesting another powerful brain stress system that contributes to compulsive drug seeking. The loss of reward function and recruitment of brain systems provide a powerful neurochemical basis that drives the compulsivity of addiction.
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Affiliation(s)
- George F. Koob
- Committee on the Neurobiology of Addictive Disorders, The Scripps Research Institute, La Jolla, CA, USA
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