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Vena AA, Zandy SL, Cofresí RU, Gonzales RA. Behavioral, neurobiological, and neurochemical mechanisms of ethanol self-administration: A translational review. Pharmacol Ther 2020; 212:107573. [PMID: 32437827 PMCID: PMC7580704 DOI: 10.1016/j.pharmthera.2020.107573] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/29/2020] [Indexed: 12/16/2022]
Abstract
Alcohol use disorder has multiple characteristics including excessive ethanol consumption, impaired control over drinking behaviors, craving and withdrawal symptoms, compulsive seeking behaviors, and is considered a chronic condition. Relapse is common. Determining the neurobiological targets of ethanol and the adaptations induced by chronic ethanol exposure is critical to understanding the clinical manifestation of alcohol use disorders, the mechanisms underlying the various features of the disorder, and for informing medication development. In the present review, we discuss ethanol's interactions with a variety of neurotransmitter systems, summarizing findings from preclinical and translational studies to highlight recent progress in the field. We then describe animal models of ethanol self-administration, emphasizing the value, limitations, and validity of commonly used models. Lastly, we summarize the behavioral changes induced by chronic ethanol self-administration, with an emphasis on cue-elicited behavior, the role of ethanol-related memories, and the emergence of habitual ethanol seeking behavior.
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Affiliation(s)
- Ashley A Vena
- Department of Psychiatry and Behavioral Neuroscience, University of Chicago, United States of America
| | | | - Roberto U Cofresí
- Psychological Sciences, University of Missouri, United States of America
| | - Rueben A Gonzales
- Division of Pharmacology and Toxicology, College of Pharmacy and Institute for Neuroscience, The University of Texas at Austin, United States of America.
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2
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Cunningham CW, Elballa WM, Vold SU. Bifunctional opioid receptor ligands as novel analgesics. Neuropharmacology 2019; 151:195-207. [PMID: 30858102 DOI: 10.1016/j.neuropharm.2019.03.006] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2018] [Revised: 01/30/2019] [Accepted: 03/02/2019] [Indexed: 12/12/2022]
Abstract
Prolonged treatment of chronic severe pain with opioid analgesics is frought with problematic adverse effects including tolerance, dependence, and life-threatening respiratory depression. Though these effects are mediated predominately through preferential activation of μ opioid peptide (μOP) receptors, there is an emerging appreciation that actions at κOP and δOP receptors contribute to the observed pharmacologic and behavioral profile of μOP receptor agonists and may be targeted simultaneously to afford improved analgesic effects. Recent developments have also identified the related nociceptin opioid peptide (NOP) receptor as a key modulator of the effects of μOP receptor signaling. We review here the available literature describing OP neurotransmitter systems and highlight recent drug and probe design strategies.
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Affiliation(s)
| | - Waleed M Elballa
- Department of Pharmaceutical Sciences, Concordia University Wisconsin, Mequon, WI, USA.
| | - Stephanie U Vold
- Department of Pharmaceutical Sciences, Concordia University Wisconsin, Mequon, WI, USA.
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3
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Korpi ER, Linden AM, Hytönen HR, Paasikoski N, Vashchinkina E, Dudek M, Herr DR, Hyytiä P. Continuous delivery of naltrexone and nalmefene leads to tolerance in reducing alcohol drinking and to supersensitivity of brain opioid receptors. Addict Biol 2017; 22:1022-1035. [PMID: 26990998 DOI: 10.1111/adb.12393] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2015] [Revised: 01/21/2016] [Accepted: 02/22/2016] [Indexed: 11/28/2022]
Abstract
Opioid antagonist treatments reduce alcohol drinking in rodent models and in alcohol-dependent patients, with variable efficacy across different studies. These treatments may suffer from the development of tolerance and opioid receptor supersensitivity, as suggested by preclinical models showing activation of these processes during and after subchronic high-dose administration of the short-acting opioid antagonist naloxone. In the present study, we compared equipotent low and moderate daily doses of naltrexone and nalmefene, two opioid antagonists in the clinical practice for treatment of alcoholism. The antagonists were given here subcutaneously for 7 days either as daily injections or continuous osmotic minipump-driven infusions to alcohol-preferring AA rats having trained to drink 10% alcohol in a limited access protocol. One day after stopping the antagonist treatment, [35 S]GTPγS autoradiography on brain cryostat sections was carried out to examine the coupling of receptors to G protein activation. The results prove the efficacy of repeated injections over infused opioid antagonists in reducing alcohol drinking. Tolerance to the reducing effect on alcohol drinking and to the enhancement of G protein coupling to μ-opioid receptors in various brain regions were consistently detected only after infused antagonists. Supersensitivity of κ-opioid receptors was seen in the ventral and dorsal striatal regions especially by infused nalmefene. Nalmefene showed no clear agonistic activity in rat brain sections or at human recombinant κ-opioid receptors. The findings support the as-needed dosing practice, rather than the standard continual dosing, in the treatment of alcoholism with opioid receptor antagonists.
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Affiliation(s)
- Esa R. Korpi
- Department of Pharmacology, Faculty of Medicine; University of Helsinki; Finland
- Department of Pharmacology, Yong Loo Lin School of Medicine; National University of Singapore; Singapore
| | - Anni-Maija Linden
- Department of Pharmacology, Faculty of Medicine; University of Helsinki; Finland
| | - Heidi R. Hytönen
- Department of Pharmacology, Faculty of Medicine; University of Helsinki; Finland
| | - Nelli Paasikoski
- Department of Pharmacology, Faculty of Medicine; University of Helsinki; Finland
| | - Elena Vashchinkina
- Department of Pharmacology, Faculty of Medicine; University of Helsinki; Finland
| | - Mateusz Dudek
- Department of Pharmacology, Faculty of Medicine; University of Helsinki; Finland
| | - Deron R. Herr
- Department of Pharmacology, Yong Loo Lin School of Medicine; National University of Singapore; Singapore
| | - Petri Hyytiä
- Department of Pharmacology, Faculty of Medicine; University of Helsinki; Finland
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4
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Granholm L, Todkar A, Bergman S, Nilsson K, Comasco E, Nylander I. The expression of opioid genes in non-classical reward areas depends on early life conditions and ethanol intake. Brain Res 2017; 1668:36-45. [PMID: 28511993 DOI: 10.1016/j.brainres.2017.05.006] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2016] [Revised: 04/21/2017] [Accepted: 05/08/2017] [Indexed: 12/28/2022]
Abstract
The young brain is highly sensitive to environmental influences that can cause long-term changes in neuronal function, possibly through altered gene expression. The endogenous opioid system continues to mature after birth and because of its involvement in reward, an inadequate maturation of this system could lead to enhanced susceptibility for alcohol use disorder. Recent studies show that the classical reward areas nucleus accumbens and ventral tegmental area are less affected by early life stress whereas endogenous opioids in non-classical areas, e.g. dorsal striatum and amygdala, are highly responsive. The aim was to investigate the interaction between early life conditions and adult voluntary ethanol intake on opioid gene expression. Male Wistar rats were exposed to conventional rearing, 15, or 360min of daily maternal separation (MS) postnatal day 1-21, and randomly assigned to ethanol or water drinking postnatal week 10-16. Rats exposed to early life stress (MS360) had increased opioid receptor gene (Oprm1, Oprd1 and Oprk1) expression in the dorsal striatum. Ethanol drinking was associated with lower striatal Oprd1 and Oprk1 expression solely in rats exposed to early life stress. Furthermore, rats exposed to early life stress had high inherent Pomc expression in the amygdala but low expression after ethanol intake. Thus, adverse events early in life induced changes in opioid gene expression and also influenced the central molecular response to ethanol intake. These long-term consequences of early life stress can contribute to the enhanced risk for excessive ethanol intake and alcohol use disorder seen after exposure to childhood adversity.
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Affiliation(s)
- Linnea Granholm
- Neuropharmacology, Addiction and Behaviour, Dept. Pharmaceutical Biosciences, Uppsala University, Uppsala, Sweden.
| | - Aniruddah Todkar
- Neuropsychopharmacology, Dept. Neuroscience, Uppsala University, Uppsala, Sweden.
| | - Sofia Bergman
- Neuropsychopharmacology, Dept. Neuroscience, Uppsala University, Uppsala, Sweden.
| | - Kent Nilsson
- Västerås Centre for Clinical Research, Uppsala University, Uppsala, Sweden.
| | - Erika Comasco
- Neuropsychopharmacology, Dept. Neuroscience, Uppsala University, Uppsala, Sweden.
| | - Ingrid Nylander
- Neuropharmacology, Addiction and Behaviour, Dept. Pharmaceutical Biosciences, Uppsala University, Uppsala, Sweden.
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Alongkronrusmee D, Chiang T, van Rijn RM. Delta Opioid Pharmacology in Relation to Alcohol Behaviors. Handb Exp Pharmacol 2016; 247:199-225. [PMID: 27316912 DOI: 10.1007/164_2016_30] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Delta opioid receptors (DORs) are heavily involved in alcohol-mediated processes in the brain. In this chapter we provide an overview of studies investigating how alcohol directly impacts DOR pharmacology and of early studies indicating DOR modulation of alcohol behavior. We will offer a brief summary of the different animal species used in alcohol studies investigating DORs followed by a broader overview of the types of alcohol behaviors modulated by DORs. We will highlight a small set of studies investigating the relationship between alcohol and DORs in analgesia. We will then provide an anatomical overview linking DOR expression in specific brain regions to different alcohol behaviors. In this section, we will provide two models that try to explain how endogenous opioids acting at DORs may influence alcohol behaviors. Next, we will provide an overview of studies investigating certain new aspects of DOR pharmacology, including the formation of heteromers and biased signaling. Finally, we provide a short overview of the genetics of the DORs in relation to alcohol use disorders (AUDs) and a short statement on the potential of using DOR-based therapeutics for treatment of AUDs.
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Affiliation(s)
- Doungkamol Alongkronrusmee
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN, USA
| | - Terrance Chiang
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN, USA
| | - Richard M van Rijn
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN, USA.
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Bell RL, Rodd ZA, Engleman EA, Toalston JE, McBride WJ. Scheduled access alcohol drinking by alcohol-preferring (P) and high-alcohol-drinking (HAD) rats: modeling adolescent and adult binge-like drinking. Alcohol 2014; 48:225-34. [PMID: 24290311 DOI: 10.1016/j.alcohol.2013.10.004] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2013] [Revised: 09/12/2013] [Accepted: 10/03/2013] [Indexed: 01/05/2023]
Abstract
Binge alcohol drinking continues to be a public health concern among today's youth and young adults. Moreover, an early onset of alcohol use, which usually takes the form of binge drinking, is associated with a greater risk for developing alcohol use disorders. Given this, it is important to examine this behavior in rat models of alcohol abuse and dependence. Toward that end, the objective of this article is to review findings on binge-like drinking by selectively bred alcohol-preferring (P) and high-alcohol-drinking (HAD) lines of rats. As reviewed elsewhere in this special issue, the P line meets all, and the HAD line meets most, of the proposed criteria for an animal model of alcoholism. One model of binge drinking is scheduled ethanol access during the dark cycle, which has been used by our laboratory for over 20 years. Our laboratory has also adopted a protocol involving the concurrent presentation of multiple ethanol concentrations. When this protocol is combined with limited access, ethanol intake is maximized yielding blood ethanol levels (BELs) in excess, sometimes greatly in excess, of 80 mg%. By extending these procedures to include multiple scheduled ethanol access sessions during the dark cycle for 5 consecutive days/week, P and HAD rats consume in 3 or 4 h as much as, if not more than, the amount usually consumed in a 24 h period. Under certain conditions, using the multiple scheduled access procedure, BELs exceeding 200 mg% can be achieved on a daily basis. An overview of findings from studies with other selectively bred, inbred, and outbred rats places these findings in the context of the existing literature. Overall, the findings support the use of P and HAD rats as animal models to study binge-like alcohol drinking and reveal that scheduled access procedures will significantly increase ethanol intake by other rat lines and strains as well.
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Affiliation(s)
- Richard L Bell
- Institute of Psychiatric Research, Department of Psychiatry, Indiana University School of Medicine, Indianapolis, IN 46202, USA.
| | - Zachary A Rodd
- Institute of Psychiatric Research, Department of Psychiatry, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Eric A Engleman
- Institute of Psychiatric Research, Department of Psychiatry, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Jamie E Toalston
- Institute of Psychiatric Research, Department of Psychiatry, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - William J McBride
- Institute of Psychiatric Research, Department of Psychiatry, Indiana University School of Medicine, Indianapolis, IN 46202, USA
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Font L, Luján MÁ, Pastor R. Involvement of the endogenous opioid system in the psychopharmacological actions of ethanol: the role of acetaldehyde. Front Behav Neurosci 2013; 7:93. [PMID: 23914161 PMCID: PMC3728478 DOI: 10.3389/fnbeh.2013.00093] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2013] [Accepted: 07/10/2013] [Indexed: 12/13/2022] Open
Abstract
Significant evidence implicates the endogenous opioid system (EOS) (opioid peptides and receptors) in the mechanisms underlying the psychopharmacological effects of ethanol. Ethanol modulates opioidergic signaling and function at different levels, including biosynthesis, release, and degradation of opioid peptides, as well as binding of endogenous ligands to opioid receptors. The role of β-endorphin and µ-opioid receptors (OR) have been suggested to be of particular importance in mediating some of the behavioral effects of ethanol, including psychomotor stimulation and sensitization, consumption and conditioned place preference (CPP). Ethanol increases the release of β-endorphin from the hypothalamic arcuate nucleus (NArc), which can modulate activity of other neurotransmitter systems such as mesolimbic dopamine (DA). The precise mechanism by which ethanol induces a release of β-endorphin, thereby inducing behavioral responses, remains to be elucidated. The present review summarizes accumulative data suggesting that the first metabolite of ethanol, the psychoactive compound acetaldehyde, could participate in such mechanism. Two lines of research involving acetaldehyde are reviewed: (1) implications of the formation of acetaldehyde in brain areas such as the NArc, with high expression of ethanol metabolizing enzymes and presence of cell bodies of endorphinic neurons and (2) the formation of condensation products between DA and acetaldehyde such as salsolinol, which exerts its actions via OR.
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Affiliation(s)
- Laura Font
- Area de Psicobiología, Universitat Jaume I Castellón, Spain
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Pharmacological traits of delta opioid receptors: pitfalls or opportunities? Psychopharmacology (Berl) 2013; 228:1-18. [PMID: 23649885 PMCID: PMC3679311 DOI: 10.1007/s00213-013-3129-2] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/15/2013] [Accepted: 04/15/2013] [Indexed: 12/11/2022]
Abstract
RATIONALE Delta opioid receptors (DORs) have been considered as a potential target to relieve pain as well as treat depression and anxiety disorders and are known to modulate other physiological responses, including ethanol and food consumption. A small number of DOR-selective drugs are in clinical trials, but no DOR-selective drugs have been approved by the Federal Drug Administration and some candidates have failed in phase II clinical trials, highlighting current difficulties producing effective delta opioid-based therapies. Recent studies have provided new insights into the pharmacology of the DOR, which is often complex and at times paradoxical. OBJECTIVE This review will discuss the existing literature focusing on four aspects: (1) Two DOR subtypes have been postulated based on differences in pharmacological effects of existing DOR-selective ligands. (2) DORs are expressed ubiquitously throughout the body and central nervous system and are, thus, positioned to play a role in a multitude of diseases. (3) DOR expression is often dynamic, with many reports of increased expression during exposure to chronic stimuli, such as stress, inflammation, neuropathy, morphine, or changes in endogenous opioid tone. (4) A large structural variety in DOR ligands implies potential different mechanisms of activating the receptor. CONCLUSION The reviewed features of DOR pharmacology illustrate the potential benefit of designing tailored or biased DOR ligands.
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Bell RL, Sable HJ, Colombo G, Hyytia P, Rodd ZA, Lumeng L. Animal models for medications development targeting alcohol abuse using selectively bred rat lines: neurobiological and pharmacological validity. Pharmacol Biochem Behav 2012; 103:119-55. [PMID: 22841890 PMCID: PMC3595005 DOI: 10.1016/j.pbb.2012.07.007] [Citation(s) in RCA: 96] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/02/2011] [Revised: 07/07/2012] [Accepted: 07/18/2012] [Indexed: 02/04/2023]
Abstract
The purpose of this review paper is to present evidence that rat animal models of alcoholism provide an ideal platform for developing and screening medications that target alcohol abuse and dependence. The focus is on the 5 oldest international rat lines that have been selectively bred for a high alcohol-consumption phenotype. The behavioral and neurochemical phenotypes of these rat lines are reviewed and placed in the context of the clinical literature. The paper presents behavioral models for assessing the efficacy of pharmaceuticals for the treatment of alcohol abuse and dependence in rodents, with particular emphasis on rats. Drugs that have been tested for their effectiveness in reducing alcohol/ethanol consumption and/or self-administration by these rat lines and their putative site of action are summarized. The paper also presents some current and future directions for developing pharmacological treatments targeting alcohol abuse and dependence.
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Affiliation(s)
- Richard L. Bell
- Department of Psychiatry, Institute of Psychiatric Research, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Helen J.K. Sable
- Department of Psychology, University of Memphis, Memphis, Tennessee, USA
| | - Giancarlo Colombo
- Neuroscience Institute, National Research Council of Italy, Section of Cagliari, Monserrato, Italy
| | - Petri Hyytia
- Institute of Biomedicine, University of Helsinki, Finland
| | - Zachary A. Rodd
- Department of Psychiatry, Institute of Psychiatric Research, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Lawrence Lumeng
- Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana, USA
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Nielsen CK, Simms JA, Li R, Mill D, Yi H, Feduccia AA, Santos N, Bartlett SE. δ-opioid receptor function in the dorsal striatum plays a role in high levels of ethanol consumption in rats. J Neurosci 2012; 32:4540-52. [PMID: 22457501 PMCID: PMC6622068 DOI: 10.1523/jneurosci.5345-11.2012] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2011] [Revised: 02/03/2012] [Accepted: 02/04/2012] [Indexed: 11/21/2022] Open
Abstract
Binge-like patterns of excessive drinking during young adulthood increase the propensity for alcohol use disorders (AUDs) later in adult life; however, the mechanisms that drive this are not completely understood. Previous studies showed that the δ-opioid peptide receptor (DOP-R) is dynamically regulated by exposure to ethanol and that the DOP-R plays a role in ethanol-mediated behaviors. The aim of this study was to determine the role of the DOP-R in high ethanol consumption from young adulthood through to late adulthood by measuring DOP-R-mediated [(35)S]GTPγS binding in brain membranes and DOP-R-mediated analgesia using a rat model of high ethanol consumption in Long Evans rats. We show that DOP-R activity in the dorsal striatum and DOP-R-mediated analgesia changes during development, being highest during early adulthood and reduced in late adulthood. Intermittent access to ethanol but not continuous ethanol or water from young adulthood leads to an increase in DOP-R activity in the dorsal striatum and DOP-R-mediated analgesia into late adulthood. Multiple microinfusions of naltrindole into the dorsal striatum or multiple systemic administration of naltrindole reduces ethanol consumption, and following termination of treatment, DOP-R activity in the dorsal striatum is attenuated. These findings suggest that DOP-R activity in the dorsal striatum plays a role in high levels of ethanol consumption and suggest that targeting the DOP-R is an alternative strategy for the treatment of AUDs.
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Affiliation(s)
- Carsten K. Nielsen
- Ernest Gallo Clinic and Research Center, University of California, San Francisco, Emeryville, California 94608, and
| | - Jeffrey A. Simms
- Ernest Gallo Clinic and Research Center, University of California, San Francisco, Emeryville, California 94608, and
| | - Rui Li
- Ernest Gallo Clinic and Research Center, University of California, San Francisco, Emeryville, California 94608, and
| | - Douglas Mill
- Ernest Gallo Clinic and Research Center, University of California, San Francisco, Emeryville, California 94608, and
| | - Henry Yi
- Ernest Gallo Clinic and Research Center, University of California, San Francisco, Emeryville, California 94608, and
| | - Allison A. Feduccia
- Ernest Gallo Clinic and Research Center, University of California, San Francisco, Emeryville, California 94608, and
| | - Nathan Santos
- Ernest Gallo Clinic and Research Center, University of California, San Francisco, Emeryville, California 94608, and
| | - Selena E. Bartlett
- Ernest Gallo Clinic and Research Center, University of California, San Francisco, Emeryville, California 94608, and
- Translational Research Institute and Institute for Health and Biomedical Innovation, Queensland University of Technology, Brisbane 4059, Australia
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Bie B, Zhu W, Pan ZZ. Ethanol-induced delta-opioid receptor modulation of glutamate synaptic transmission and conditioned place preference in central amygdala. Neuroscience 2009; 160:348-58. [PMID: 19258026 PMCID: PMC2669697 DOI: 10.1016/j.neuroscience.2009.02.049] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2008] [Revised: 02/18/2009] [Accepted: 02/22/2009] [Indexed: 12/15/2022]
Abstract
Alcoholism involves compulsive behaviors of alcohol drinking, which is thought to be related at least initially to the rewarding effect of alcohol. It has been shown that mu-opioid receptors play an essential role in drug reward and dependence for many drugs of abuse including alcohol, but the function of delta-opioid receptors (DOR) in drug reward remains largely unknown at present. Previous animal studies using systemic approaches with DOR antagonists or DOR knockout animals have yielded inconsistent results, showing a decrease, an increase or no change in alcohol consumption and behaviors of alcohol reward after DOR inhibition or deletion. In the present study, we used ethanol-conditioned rats to investigate adaptive DOR function in neurons of the central nucleus of the amygdala (CeA), a key brain site for alcohol reward and addiction. We found that functional DOR was absent in glutamate synapses of CeA neurons from control rats, but it emerged and inhibited glutamate synaptic currents in CeA neurons from rats displaying ethanol-induced behavior of conditioned place preference (CPP). Analysis of paired-pulse ratios and miniature glutamate synaptic currents revealed that the recruited DOR was present on glutamatergic presynaptic terminals. Similar induction of functional DOR was also found on GABA synapses. Furthermore, microinjection of a DOR antagonist into the CeA reversed ethanol-induced CPP behavior in rats in vivo. These results suggest that repeated alcohol exposure recruits new functional DOR on CeA glutamate and GABA synapses, which may be involved in the expression or maintenance of ethanol-induced CPP behavior.
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Affiliation(s)
- Bihua Bie
- Department of Anesthesiology and Pain Medicine, The University of Texas-MD Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, TX 77030
| | - Wei Zhu
- Department of Anesthesiology and Pain Medicine, The University of Texas-MD Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, TX 77030
| | - Zhizhong Z. Pan
- Department of Anesthesiology and Pain Medicine, The University of Texas-MD Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, TX 77030
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12
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Delta-opioid receptor expression in the ventral tegmental area protects against elevated alcohol consumption. J Neurosci 2009; 28:12672-81. [PMID: 19036960 DOI: 10.1523/jneurosci.4569-08.2008] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Alcoholism is a complex and debilitating syndrome affecting approximately 140 million people worldwide. However, not everyone who consumes ethanol develops abuse, raising the possibility that some individuals have a protective mechanism that inhibits elevated alcohol consumption. We tested the hypothesis that the delta-opioid receptor (DOR) plays such a protective role. Here we show that DOR activity in the ventral tegmental area (VTA) robustly decreases ethanol consumption in rats and that these effects depend on baseline ethanol consumption. Intra-VTA microinjection of the DOR agonist DPDPE decreases drinking, particularly in low-drinking animals. Furthermore, VTA microinjection of the DOR selective antagonist TIPP-Psi increases drinking in low, but not high, drinkers and this increase is blocked by comicroinjection of the GABA(A) antagonist bicuculline. Using electrophysiological techniques we found that in VTA brain slices from drinking rats DPDPE presynaptically inhibits GABA(A) receptor mediated IPSCs in low drinkers, but not in high drinkers or naive animals, most likely through activation of DORs on GABA terminals. This DOR-mediated inhibition of IPSCs also correlates inversely with behavioral correlates of anxiety measured in the elevated plus maze. In contrast, presynaptic inhibition of VTA GABA(A) IPSCs by the mu-opioid receptor agonist DAMGO is significantly reduced in both high- and low-drinking rats (<30%) compared with age-matched nondrinking controls (>70%). Together, our findings demonstrate the protective nature of VTA DORs and identify an important new target for therapeutic intervention for alcoholism.
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Nielsen CK, Simms JA, Pierson HB, Li R, Saini SK, Ananthan S, Bartlett SE. A novel delta opioid receptor antagonist, SoRI-9409, produces a selective and long-lasting decrease in ethanol consumption in heavy-drinking rats. Biol Psychiatry 2008; 64:974-81. [PMID: 18774553 PMCID: PMC3888668 DOI: 10.1016/j.biopsych.2008.07.018] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/05/2008] [Revised: 07/12/2008] [Accepted: 07/18/2008] [Indexed: 11/28/2022]
Abstract
BACKGROUND Naltrexone, a compound with high affinity for the mu opioid receptor (MOP-R) reduces alcohol consumption. SoRI-9409 is a derivative of naltrexone that has highest affinity at delta opioid receptors (DOP-Rs). We have investigated the effects of SoRI-9409 on ethanol consumption to determine the consequences of altering the naltrexone compound to a form with increased efficacy at DOP-Rs. METHODS Effects of the opioid receptor antagonists, SoRI-9409 (0-30 mg/kg, IP), naltrexone (0-30 mg/kg, IP), or naltrindole (0-10 mg/kg, IP) on ethanol consumption was measured in high- and low-ethanol-consuming rats with two different drinking paradigms. SoRI-9409-, naltrexone-, and naltrindole-mediated inhibition of DOP-R-stimulated [(35)S]GTP gamma S binding was measured in brain membranes prepared from high-ethanol-consuming rats. The effects of SoRI-9409 on morphine-mediated analgesia, conditioned place preference, and anxiety were also examined. RESULTS In high- but not low-ethanol-consuming animals, SoRI-9409 is threefold more effective and selective at reducing ethanol consumption when compared with naltrexone or naltrindole for up to 24 hours. SoRI-9409 administered daily for 28 days continuously reduced ethanol consumption, and when the administration of SoRI-9409 was terminated, the amount of ethanol consumed remained lower compared with vehicle-treated animals. Furthermore, SoRI-9409 inhibits DOP-R-stimulated [(35)S]GTP gamma S binding in brain membranes of high-ethanol-consuming rats. CONCLUSIONS SoRI-9409 causes selective and long-lasting reductions of ethanol consumption. This suggests that compounds that have high affinity for DOP-Rs such as SoRI-9409 might be promising candidates for development as a novel therapeutic for the treatment of alcoholism.
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Affiliation(s)
- Carsten K Nielsen
- Ernest Gallo Clinic and Research Center, University of California San Francisco, Emeryville, California 94608, USA
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14
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Kang-Park MH, Kieffer BL, Roberts AJ, Siggins GR, Moore SD. Presynaptic delta opioid receptors regulate ethanol actions in central amygdala. J Pharmacol Exp Ther 2006; 320:917-25. [PMID: 17114568 DOI: 10.1124/jpet.106.112722] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Endogenous opioid systems are implicated in the reinforcing effects of ethanol consumption. For example, delta opioid receptor (DOR) knockout (KO) mice show greater ethanol consumption than wild-type (WT) mice (Roberts et al., 2001). To explore the neurobiological correlates underlying these behaviors, we examined effects of acute ethanol application in brain slices from DOR KO mice using whole-cell patch recording techniques. We examined the central nucleus of amygdala (CeA) because the CeA is implicated in alcohol reinforcement (Koob et al., 1998). We found that the acute ethanol effects on GABA(A) receptor-mediated inhibitory postsynaptic currents (IPSCs) were greater in DOR KO mice than in WT mice. Ethanol increased the frequency of miniature IPSCs (mIPSCs) significantly more in DOR KO mice than in WT mice. In CeA of WT mice, application of ICI 174864 [[allyl]2-Tyr-alpha-amino-isobutyric acid (Aib)-Aib-Phe-Leu-OH], a DOR inverse agonist, augmented ethanol actions on mIPSC frequency comparable with ethanol effects seen in DOR KO mice. Superfusion of the selective DOR agonist D-Pen(2),D-Pen(5)-enkephalin decreased the mean frequency of mIPSCs; this effect was reversed by the DOR antagonist naltrindole. These findings suggest that endogenous opioids may reduce ethanol actions on IPSCs of CeA neurons in WT mice through DOR-mediated inhibition of GABA release and that the increased ethanol effect on IPSCs in CeA of DOR KO mice could be, at least in part, due to absence of DOR-mediated inhibition of GABA release. This result supports the hypothesis that endogenous opioid peptides modulate the ethanol-induced augmentation of GABA(A) receptor-dependent circuitry in CeA (Roberto et al., 2003).
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Kovacs KM, Szakall I, O'Brien D, Wang R, Vinod KY, Saito M, Simonin F, Kieffer BL, Vadasz C. Decreased oral self-administration of alcohol in kappa-opioid receptor knock-out mice. Alcohol Clin Exp Res 2005; 29:730-8. [PMID: 15897716 DOI: 10.1097/01.alc.0000164361.62346.d6] [Citation(s) in RCA: 98] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Although a large body of evidence suggests a role for the opioid system in alcoholism, the precise role of mu-, delta-, kappa-, and ORL1-opioid receptors and the physiological significance of their natural genetic variation have not been identified. The method of targeted gene disruption by homologous recombination has been used to knock out (KO) genes coding for opioid receptors, and study their effects on alcohol self-administration. Here we examined the effects of targeted disruption of kappa-opioid receptor (KOR) on oral alcohol self-administration and other behaviors. METHODS Oral alcohol, saccharin and quinine self-administration was assessed in a two-bottle choice paradigm using escalating concentrations of alcohol, or tastant solutions. In preference tests 12% alcohol, 0.033% and 0.066% saccharin, and 0.03 mM and 0.1 mM quinine solutions were used. Open-field activity was determined in an arena equipped with a computer-controlled activity-detection system. Subjects were tested for three consecutive days. Locomotor activity was assessed on days 1 and 2 (after saline injection, i.p.) and on day 3 (after alcohol injection, i.p.). Alcohol-induced locomotor activity was determined as the difference in activity between day 3 and day 2. RESULTS Male KOR KO mice in preference tests with 12% alcohol consumed about half as much alcohol as wild-type (WT) or heterozygous (HET) mice, showed lower preference for saccharin (0.033% and 0.066%) and higher preference to quinine (0.1 mM) than WT mice. Female KOR KO mice showed similar reduction in alcohol consumption in comparison to WT and HET mice. Partial deletion of KOR in HET mice did not change alcohol consumption in comparison to WT mice. In all genotype-groups females drank significantly more alcohol than males. MANOVA of locomotor activity among KO, WT, and HET mice indicated that strain and sex effects were not significant for alcohol-induced activation (p > 0.05), while strain x sex interaction effects on alcohol-induced activation could be detected (F(1,55) = 6.07, p < 0.05). CONCLUSION Our results indicating decreased alcohol consumption, lower saccharin preference, and higher quinine preference in KOR KO mice are in line with previous observations of opioid involvement in maintenance of food intake and raise the possibility that the deficient dynorphin/KOR system affects orosensory reward through central mechanisms which reduce alcohol intake and disrupt tastant responses, either as direct effects of absence of kappa-opioid receptors, or as effects of indirect developmental compensatory changes.
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Affiliation(s)
- Krisztina M Kovacs
- Laboratory of Neurobehavioral GeneticsNathan S. Kline Institute for Psychiatric Research, 140 Old Orangeburg Road, Orangeburg, NY 10962, USA.
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Abstract
This paper is the 26th consecutive installment of the annual review of research concerning the endogenous opioid system, now spanning over a quarter-century of research. It summarizes papers published during 2003 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 (Section 2), and the roles of these opioid peptides and receptors in pain and analgesia (Section 3); stress and social status (Section 4); tolerance and dependence (Section 5); learning and memory (Section 6); eating and drinking (Section 7); alcohol and drugs of abuse (Section 8); sexual activity and hormones, pregnancy, development and endocrinology (Section 9); mental illness and mood (Section 10); seizures and neurologic disorders (Section 11); electrical-related activity and neurophysiology (Section 12); general activity and locomotion (Section 13); gastrointestinal, renal and hepatic functions (Section 14); cardiovascular responses (Section 15); respiration and thermoregulation (Section 16); and immunological responses (Section 17).
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Affiliation(s)
- Richard J Bodnar
- Department of Psychology and Neuropsychology, Doctoral Sub-Program, Queens College, City University of New York, 65-30 Kissena Blvd., Flushing, NY 11367, USA.
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Ingman K, Sallinen J, Honkanen A, Korpi ER. Comparison of deramciclane to benzodiazepine agonists in behavioural activity of mice and in alcohol drinking of alcohol-preferring rats. Pharmacol Biochem Behav 2004; 77:847-54. [PMID: 15099931 DOI: 10.1016/j.pbb.2004.02.015] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/25/2003] [Revised: 02/19/2004] [Accepted: 02/26/2004] [Indexed: 11/18/2022]
Abstract
Interactions between alcohol and traditional benzodiazepine anxiolytics hamper the treatment of alcoholism-related anxiety disorders. Serotonin 5-HT(2) receptor antagonists, such as deramciclane, are anxiolytic, and considering their pharmacological profile, they might benefit alcoholics with comorbid anxiety. We studied the effects of acute deramciclane (1, 3 and 10 mg/kg i.p.) on alcohol drinking of alcohol-preferring AA rats drinking 10% (vol/vol) ethanol solution in a 4-h limited-access paradigm. Thereafter, a 5-day repeated-treatment experiment was carried out, under corresponding test design, with deramciclane (3 mg/kg i.p.) as a test drug and midazolam (1 mg/kg i.p.) as a benzodiazepine reference compound. Deramciclane had no effect on alcohol consumption in either acute or repeated dosing study. Midazolam increased ethanol drinking, as expected, when administered on successive days. A modified functional observational battery (FOB) procedure was applied to study neurological, behavioural and autonomic effects induced by deramciclane (1-30 mg/kg po) and diazepam (1-30 mg/kg po) in mice at 30 min, 2 h and 4 h after dosing. Deramciclane had a mild dopamine D(2) receptor antagonism-like effect at the highest dose. The effects of diazepam were predictable, myorelaxation-induced motor impairment and anxiolysis-related hyperlocomotion in a novel environment being the characteristic features at the two highest doses. Deramciclane appears to be a safe and well-tolerated drug and we suggest that it might be useful in the treatment of anxiety in alcoholics.
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Affiliation(s)
- Kimmo Ingman
- Department of Pharmacology and Clinical Pharmacology, University of Turku, Itäinen Pitkäkatu 4B, FIN-20520 Turku, Finland.
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