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Vassoler FM, Budge KE, Isgate SB, Gildawie KR, Byrnes EM. Neuroplasticity-related genes correlate with individual differences in distinct phases of oxycodone self-administration in male rats. Neuropharmacology 2024; 254:109972. [PMID: 38710443 PMCID: PMC11164234 DOI: 10.1016/j.neuropharm.2024.109972] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Revised: 04/11/2024] [Accepted: 04/25/2024] [Indexed: 05/08/2024]
Abstract
Opioid use disorder (OUD) is a chronic condition associated with long-lasting molecular and behavioral changes. Animals with prolonged access to opioids develop behaviors similar to human OUD. Identifying associated molecular changes can provide insight to underpinnings that lead to or maintain OUD. In pilot studies, we identified several miRNA targets that are altered by the administration of oxycodone. We selected mir182 for follow up as it was recently shown to be dysregulated in plasma of men administered oxycodone. In addition, mir182 is increased in reward-related brain regions of male rats following exposure to various addictive substances. The present study utilizes a long-access oxycodone self-administration paradigm to examine changes in mir182 and its mRNA targets associated with neuroplasticity, which may be involved in the maintenance of OUD-like phenotype in rats. Male rats were trained to self-administer oxycodone (0.1 mg/kg/infusion, i. v.) for 6 h daily sessions for 12 days. Each animal had a yoked saline control that received matched saline infusions. Animals were then tested on a progressive ratio schedule to measure motivation to obtain a single infusion of oxycodone. Drug seeking was measured following 28 days of forced abstinence using a 90-min cued/test. RTqPCR was utilized to measure mir182 and mRNA targets related to neuroplasticity (wnt3, plppr4, pou3f3, tle4, cacna2d, and bdnf) from the nucleus accumbens. Data revealed that animals responded on a continuum for oxycodone. When divided into two groups termed high- and low responders, animals diverged during self-administration acquisition and maintained differences in behavior and gene expression throughout the study. mir182 was upregulated in the nucleus accumbens of both high and low responders and negatively correlated with tle4, which showed a strong negative correlation with reinstatement behavior. mRNA target levels were correlated with behaviors associated with increased severity of OUD behavior in male rats.
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Affiliation(s)
- Fair M Vassoler
- Cummings School of Veterinary Medicine at Tufts University, 200 Westboro Road, North Grafton, MA, 01536, USA.
| | - Kerri E Budge
- Cummings School of Veterinary Medicine at Tufts University, 200 Westboro Road, North Grafton, MA, 01536, USA
| | - Sara B Isgate
- Cummings School of Veterinary Medicine at Tufts University, 200 Westboro Road, North Grafton, MA, 01536, USA
| | - Kelsea R Gildawie
- Cummings School of Veterinary Medicine at Tufts University, 200 Westboro Road, North Grafton, MA, 01536, USA
| | - Elizabeth M Byrnes
- Cummings School of Veterinary Medicine at Tufts University, 200 Westboro Road, North Grafton, MA, 01536, USA
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Gutierrez A, Nguyen JD, Creehan KM, Grant Y, Taffe MA. Adult Consequences of Repeated Nicotine Vapor Inhalation in Adolescent Rats. Nicotine Tob Res 2024; 26:715-723. [PMID: 37946372 PMCID: PMC11109496 DOI: 10.1093/ntr/ntad211] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2023] [Revised: 10/03/2023] [Accepted: 10/20/2023] [Indexed: 11/12/2023]
Abstract
INTRODUCTION There has been a resurgence in nicotine inhalation in adolescents due to the popularity and availability of Electronic Nicotine Delivery Systems (ENDS). Almost five times as many US high-school seniors inhale nicotine vapor daily compared with those who smoke tobacco. This study was conducted to determine the impact of repeated adolescent vapor inhalation of nicotine on behavior in adulthood. METHODS Male and female Sprague-Dawley rats were exposed to 30-minute sessions of ENDS vapor inhalation, twice daily, from post-natal day (PND) 31-40. Conditions included vapor from the propylene glycol (PG) vehicle or nicotine (30 mg/mL in the PG). Animals were assessed for effects of nicotine on open field (PND 74-105) and wheel activity (PND 126-180) and for volitional exposure to nicotine vapor (PND 285-395). Plasma nicotine and cotinine were assessed in separate groups of male and female Wistar and Sprague-Dawley rats after a single nicotine inhalation session. RESULTS Group mean plasma nicotine ranged from 39 to 59 ng/mL post-session with minimal strain differences detected. Adolescent nicotine exposure enhanced sensitivity to the locomotor stimulating effects of nicotine (0.1-0.8 mg/kg, s.c.) in an open field in female rats, but didn't change the effects of nicotine on wheel activity. Female rats exposed to nicotine (30 mg/mL) vapor as adolescents responded more vigorously than PG-exposed females to nicotine vapor in a fixed ratio 5 challenge. CONCLUSIONS Repeated adolescent nicotine vapor inhalation leads to enhanced liability for volitional exposure to nicotine vapor in adulthood in female rats, but minimal change in spontaneous locomotor behavior. IMPLICATIONS These results show that adolescent vaping of nicotine can lead to lasting sensitization to the effects of nicotine in adulthood, including volitional responding for nicotine vapor. Demonstration of this in a controlled animal model establishes causality in a manner not possible from longitudinal evidence in human populations. These findings further highlight the importance of decreasing adolescent nicotine exposure to e-cigarettes to reduce consumption in adulthood.
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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
- Department of Psychology and Neuroscience, Baylor University;Waco, TX, 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
| | - Yanabel Grant
- 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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Slivicki RA, Wang JG, Nhat VTT, Kravitz AV, Creed MC, Gereau RW. Impact of Δ 9-Tetrahydrocannabinol and oxycodone co-administration on measures of antinociception, dependence, circadian activity, and reward in mice. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.04.569809. [PMID: 38105953 PMCID: PMC10723318 DOI: 10.1101/2023.12.04.569809] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2023]
Abstract
Oxycodone is commonly prescribed for moderate to severe pain disorders. While efficacious, long-term use can result in tolerance, physical dependence, and the development of opioid use disorder. Cannabis and its derivatives such as Δ9-Tetrahydrocannabinol (Δ9-THC) have been reported to enhance oxycodone analgesia in animal models and in humans. However, it remains unclear if Δ9-THC may facilitate unwanted aspects of oxycodone intake, such as tolerance, dependence, and reward at analgesic doses. This study sought to evaluate the impact of co-administration of Δ9-THC and oxycodone across behavioral measures related to antinociception, dependence, circadian activity, and reward in both male and female mice. Oxycodone and Δ9-THC produced dose-dependent antinociceptive effects in the hotplate assay that were similar between sexes. Repeated treatment (twice daily for 5 days) resulted in antinociceptive tolerance. Combination treatment of oxycodone and Δ9-THC produced a greater antinociceptive effect than either administered alone, and delayed the development of antinociceptive tolerance. Repeated treatment with oxycodone produced physical dependence and alterations in circadian activity, neither of which were exacerbated by co-treatment with Δ9-THC. Combination treatment of oxycodone and Δ9-THC produced CPP when co-administered at doses that did not produce preference when administered alone. These data indicate that Δ9-THC may facilitate oxycodone-induced antinociception without augmenting certain unwanted features of opioid intake (e.g. dependence, circadian rhythm alterations). However, our findings also indicate that Δ9-THC may facilitate rewarding properties of oxycodone at therapeutically relevant doses which warrant consideration when evaluating this combination for its potential therapeutic utility.
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Affiliation(s)
- Richard A. Slivicki
- Washington University Pain Center and Department of Anesthesiology, Washington University, St. Louis, MO
| | - Justin G. Wang
- Washington University Pain Center and Department of Anesthesiology, Washington University, St. Louis, MO
- Neuroscience Graduate Program, Division of Biology & Biomedical Sciences, Washington University, St. Louis, MO
| | - Vy Trinh Tran Nhat
- Washington University Pain Center and Department of Anesthesiology, Washington University, St. Louis, MO
| | - Alexxai V. Kravitz
- Washington University Pain Center and Department of Anesthesiology, Washington University, St. Louis, MO
- Department of Psychiatry, Washington University, St. Louis, MO
- Department of Neuroscience, Washington University, St. Louis, MO
| | - Meaghan C. Creed
- Washington University Pain Center and Department of Anesthesiology, Washington University, St. Louis, MO
- Department of Neuroscience, Washington University, St. Louis, MO
| | - Robert W. Gereau
- Washington University Pain Center and Department of Anesthesiology, Washington University, St. Louis, MO
- Department of Neuroscience, Washington University, St. Louis, MO
- Department of Biomedical Engineering, Washington University, St. Louis, MO
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Illenberger JM, Flores-Ramirez FJ, Pascasio G, Matzeu A, Martin-Fardon R. Daily treatment with the dual orexin receptor antagonist DORA-12 during oxycodone abstinence decreases oxycodone conditioned reinstatement. Neuropharmacology 2023; 239:109685. [PMID: 37579870 PMCID: PMC10529002 DOI: 10.1016/j.neuropharm.2023.109685] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2023] [Revised: 08/02/2023] [Accepted: 08/07/2023] [Indexed: 08/16/2023]
Abstract
Chronic opioid use disturbs circadian rhythm and sleep, encouraging opioid use and relapse. The orexin (OX) system is recruited by opioids and regulates physiological processes including sleep. Dual OX receptor antagonists (DORAs), developed for insomnia treatment, may relieve withdrawal-associated sleep disturbances. This study investigated whether DORA-12, a recently developed DORA, reduces physiological activity disturbances during oxycodone abstinence and consequently prevents oxycodone-seeking behavior. Male and female Wistar rats were trained to intravenously self-administer oxycodone (0.15 mg/kg, 21 sessions; 8 h/session) in the presence of a contextual/discriminative stimulus (SD). The rats were subsequently housed individually (22 h/day) to monitor activity, food and water intake. They received DORA-12 (0-30 mg/kg, p.o.) after undergoing daily 1-h extinction training (14 days). After extinction, the rats were tested for oxycodone-seeking behavior elicited by the SD. Hypothalamus sections were processed to assess oxycodone- or DORA-12-associated changes to the OX cell number. In males, oxycodone-associated increases in activity during the light-phase, reinstatement, and decreases in the number of OX cells observed in the vehicle-treated group were not observed with DORA-12-treatment. Oxycodone-associated increases in light-phase food and water intake were not observed by day 14 of 3 mg/kg DORA-12-treatment and dark-phase water intake was increased across treatment days. In females, OX cell number was unaffected by oxycodone or DORA-12. Three and 30 mg/kg DORA-12 increased females' day 7 dark-phase activity and decreased reinstatement. Thirty mg/kg DORA-12 reduced oxycodone-associated increases in light-phase food and water intake. The results suggest that DORA-12 improves oxycodone-induced disruptions to physiological activities and reduces relapse.
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Affiliation(s)
- Jessica M Illenberger
- The Scripps Research Institute, 10550 North Torrey Pines Road, SR-107, La Jolla, CA, 92037, USA.
| | | | - Glenn Pascasio
- The Scripps Research Institute, 10550 North Torrey Pines Road, SR-107, La Jolla, CA, 92037, USA
| | - Alessandra Matzeu
- The Scripps Research Institute, 10550 North Torrey Pines Road, SR-107, La Jolla, CA, 92037, USA
| | - Rémi Martin-Fardon
- The Scripps Research Institute, 10550 North Torrey Pines Road, SR-107, La Jolla, CA, 92037, USA
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Barrett JE, Shekarabi A, Inan S. Oxycodone: A Current Perspective on Its Pharmacology, Abuse, and Pharmacotherapeutic Developments. Pharmacol Rev 2023; 75:1062-1118. [PMID: 37321860 PMCID: PMC10595024 DOI: 10.1124/pharmrev.121.000506] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Revised: 04/30/2023] [Accepted: 06/05/2023] [Indexed: 06/17/2023] Open
Abstract
Oxycodone, a semisynthetic derivative of naturally occurring thebaine, an opioid alkaloid, has been available for more than 100 years. Although thebaine cannot be used therapeutically due to the occurrence of convulsions at higher doses, it has been converted to a number of other widely used compounds that include naloxone, naltrexone, buprenorphine, and oxycodone. Despite the early identification of oxycodone, it was not until the 1990s that clinical studies began to explore its analgesic efficacy. These studies were followed by the pursuit of several preclinical studies to examine the analgesic effects and abuse liability of oxycodone in laboratory animals and the subjective effects in human volunteers. For a number of years oxycodone was at the forefront of the opioid crisis, playing a significant role in contributing to opioid misuse and abuse, with suggestions that it led to transitioning to other opioids. Several concerns were expressed as early as the 1940s that oxycodone had significant abuse potential similar to heroin and morphine. Both animal and human abuse liability studies have confirmed, and in some cases amplified, these early warnings. Despite sharing a similar structure with morphine and pharmacological actions also mediated by the μ-opioid receptor, there are several differences in the pharmacology and neurobiology of oxycodone. The data that have emerged from the many efforts to analyze the pharmacological and molecular mechanism of oxycodone have generated considerable insight into its many actions, reviewed here, which, in turn, have provided new information on opioid receptor pharmacology. SIGNIFICANCE STATEMENT: Oxycodone, a μ-opioid receptor agonist, was synthesized in 1916 and introduced into clinical use in Germany in 1917. It has been studied extensively as a therapeutic analgesic for acute and chronic neuropathic pain as an alternative to morphine. Oxycodone emerged as a drug with widespread abuse. This article brings together an integrated, detailed review of the pharmacology of oxycodone, preclinical and clinical studies of pain and abuse, and recent advances to identify potential opioid analgesics without abuse liability.
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Affiliation(s)
- James E Barrett
- Center for Substance Abuse Research, Lewis Katz School of Medicine, Temple University. Philadelphia, Pennsylvania
| | - Aryan Shekarabi
- Center for Substance Abuse Research, Lewis Katz School of Medicine, Temple University. Philadelphia, Pennsylvania
| | - Saadet Inan
- Center for Substance Abuse Research, Lewis Katz School of Medicine, Temple University. Philadelphia, Pennsylvania
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6
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Nguyen JD, Grant Y, Yang C, Gutierrez A, Taffe MA. Oxycodone Self-Administration in Female Rats is Enhanced by ∆ 9-tetrahydrocannabinol, but not by Cannabidiol, in a Progressive Ratio Procedure. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.26.564282. [PMID: 37961225 PMCID: PMC10634900 DOI: 10.1101/2023.10.26.564282] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
Epidemiological evidence suggests that the legalization of cannabis may reduce opioid-related harms. Preclinical evidence of neuropharmacological interactions of endogenous cannabinoid and opioid systems prompts further investigation of cannabinoids as potential therapeutics for the non-medical use of opioids. In these studies female rats, previously trained to self-administer oxycodone (0.15 mg/kg/infusion) intravenously in 6 h sessions, were allowed to self-administer oxycodone after exposure to cannabidiol (CBD) and Δ9-tetrahydrocannabinol (THC) by vapor inhalation and THC by injection (5.0-20 mg/kg, i.p.). Self-administration was characterized under Progressive Ratio (PR) and Fixed Ratio (FR) 1 schedules of reinforcement in 3 h sessions. THC decreased IVSA of oxycodone in a FR procedure but increased reward seeking in a PR procedure. CBD decreased the IVSA of oxycodone in the FR but not the PR procedure. The results are consistent with an anti-reward effect of CBD but suggest THC acts to increase the reinforcing efficacy of oxycodone in this procedure.
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Affiliation(s)
- Jacques D. Nguyen
- Department of Psychiatry, University of California, San Diego; La Jolla, CA, USA
- Department of Psychology and Neuroscience, Baylor University, Waco, TX, USA
| | - Yanabel Grant
- Department of Psychiatry, University of California, San Diego; La Jolla, CA, USA
| | - Celine Yang
- Department of Psychiatry, University of California, San Diego; La Jolla, CA, USA
| | - Arnold Gutierrez
- Department of Psychiatry, University of California, San Diego; La Jolla, CA, USA
| | - Michael A. Taffe
- Department of Psychiatry, University of California, San Diego; La Jolla, CA, USA
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7
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Farahbakhsh ZZ, Song K, Branthwaite HE, Erickson KR, Mukerjee S, Nolan SO, Siciliano CA. Systemic kappa opioid receptor antagonism accelerates reinforcement learning via augmentation of novelty processing in male mice. Neuropsychopharmacology 2023; 48:857-868. [PMID: 36804487 PMCID: PMC10156709 DOI: 10.1038/s41386-023-01547-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/13/2022] [Revised: 01/20/2023] [Accepted: 02/02/2023] [Indexed: 02/19/2023]
Abstract
Selective inhibition of kappa opioid receptors (KORs) is highly anticipated as a pharmacotherapeutic intervention for substance use disorders and depression. The accepted explanation for KOR antagonist-induced amelioration of aberrant behaviors posits that KORs globally function as a negative valence system; antagonism thereby blunts the behavioral influence of negative internal states such as anhedonia and negative affect. While effects of systemic KOR manipulations have been widely reproduced, explicit evaluation of negative valence as an explanatory construct is lacking. Here, we tested a series of falsifiable hypotheses generated a priori based on the negative valence model by pairing reinforcement learning tasks with systemic pharmacological KOR blockade in male C57BL/6J mice. The negative valence model failed to predict multiple experimental outcomes: KOR blockade accelerated contingency learning during both positive and negative reinforcement without altering innate responses to appetitive or aversive stimuli. We next proposed novelty processing, which influences learning independent of valence, as an alternative explanatory construct. Hypotheses based on novelty processing predicted subsequent observations: KOR blockade increased exploration of a novel, but not habituated, environment and augmented the reinforcing efficacy of novel visual stimuli in a sensory reinforcement task. Together, these results revise and extend long-standing theories of KOR system function.
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Affiliation(s)
- Zahra Z Farahbakhsh
- Department of Pharmacology, Vanderbilt Brain Institute, Vanderbilt Center for Addiction Research, Vanderbilt University, Nashville, TN, 37232, USA
| | - Keaton Song
- Department of Pharmacology, Vanderbilt Brain Institute, Vanderbilt Center for Addiction Research, Vanderbilt University, Nashville, TN, 37232, USA
| | - Hannah E Branthwaite
- Department of Pharmacology, Vanderbilt Brain Institute, Vanderbilt Center for Addiction Research, Vanderbilt University, Nashville, TN, 37232, USA
| | - Kirsty R Erickson
- Department of Pharmacology, Vanderbilt Brain Institute, Vanderbilt Center for Addiction Research, Vanderbilt University, Nashville, TN, 37232, USA
| | - Snigdha Mukerjee
- Department of Pharmacology, Vanderbilt Brain Institute, Vanderbilt Center for Addiction Research, Vanderbilt University, Nashville, TN, 37232, USA
| | - Suzanne O Nolan
- Department of Pharmacology, Vanderbilt Brain Institute, Vanderbilt Center for Addiction Research, Vanderbilt University, Nashville, TN, 37232, USA
| | - Cody A Siciliano
- Department of Pharmacology, Vanderbilt Brain Institute, Vanderbilt Center for Addiction Research, Vanderbilt University, Nashville, TN, 37232, USA.
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8
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Bodnar RJ. Endogenous opiates and behavior: 2021. Peptides 2023; 164:171004. [PMID: 36990387 DOI: 10.1016/j.peptides.2023.171004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/26/2023] [Revised: 03/23/2023] [Accepted: 03/23/2023] [Indexed: 03/29/2023]
Abstract
This paper is the forty-fourth consecutive installment of the annual anthological review of research concerning the endogenous opioid system, summarizing articles published during 2021 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides and receptors as well as effects of opioid/opiate agonizts and antagonists. The review is subdivided into the following specific topics: molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors (1), the roles of these opioid peptides and receptors in pain and analgesia in animals (2) and humans (3), opioid-sensitive and opioid-insensitive effects of nonopioid analgesics (4), opioid peptide and receptor involvement in tolerance and dependence (5), stress and social status (6), learning and memory (7), eating and drinking (8), drug abuse and alcohol (9), sexual activity and hormones, pregnancy, development and endocrinology (10), mental illness and mood (11), seizures and neurologic disorders (12), electrical-related activity and neurophysiology (13), general activity and locomotion (14), gastrointestinal, renal and hepatic functions (15), cardiovascular responses (16), respiration and thermoregulation (17), and immunological responses (18).
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Affiliation(s)
- Richard J Bodnar
- Department of Psychology and Neuropsychology Doctoral Sub-Program, Queens College, City University of New York, CUNY, 65-30 Kissena Blvd., Flushing, NY 11367, USA.
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9
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Khom S, Nguyen JD, Vandewater SA, Grant Y, Roberto M, Taffe MA. Self-Administration of Entactogen Psychostimulants Dysregulates Gamma-Aminobutyric Acid (GABA) and Kappa Opioid Receptor Signaling in the Central Nucleus of the Amygdala of Female Wistar Rats. Front Behav Neurosci 2021; 15:780500. [PMID: 34975428 PMCID: PMC8716434 DOI: 10.3389/fnbeh.2021.780500] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2021] [Accepted: 11/08/2021] [Indexed: 11/13/2022] Open
Abstract
Male rats escalate intravenous self-administration of entactogen psychostimulants, 3,4-methylenedioxymethcathinone (methylone) and 3,4-methylenedioxymethamphetamine (MDMA) under extended access conditions, as with typical psychostimulants. Here, we investigated whether female rats escalate self-administration of methylone, 3,4-methylenedioxypentedrone (pentylone), and MDMA and then studied consequences of MDMA and pentylone self-administration on GABAA receptor and kappa opioid receptor (KOR) signaling in the central nucleus of the amygdala (CeA), a brain area critically dysregulated by extended access self-administration of alcohol or cocaine. Adult female Wistar rats were trained to self-administer methylone, pentylone, MDMA (0.5 mg/kg/infusion), or saline-vehicle using a fixed-ratio 1 response contingency in 6-h sessions (long-access: LgA) followed by progressive ratio (PR) dose-response testing. The effects of pentylone-LgA, MDMA-LgA and saline on basal GABAergic transmission (miniature post-synaptic inhibitory currents, mIPSCs) and the modulatory role of KOR at CeA GABAergic synapses were determined in acute brain slices using whole-cell patch-clamp. Methylone-LgA and pentylone-LgA rats similarly escalated their drug intake (both obtained more infusions compared to MDMA-LgA rats), however, pentylone-LgA rats reached higher breakpoints in PR tests. At the cellular level, baseline CeA GABA transmission was markedly elevated in pentylone-LgA and MDMA-LgA rats compared to saline-vehicle. Specifically, pentylone-LgA was associated with increased CeA mIPSC frequency (GABA release) and amplitude (post-synaptic GABAA receptor function), while mIPSC amplitudes (but not frequency) was larger in MDMA-LgA rats compared to saline rats. In addition, pentylone-LgA and MDMA-LgA profoundly disrupted CeA KOR signaling such as both KOR agonism (1 mM U50488) and KOR antagonism (200 nM nor-binaltorphimine) decreased mIPSC frequency suggesting recruitment of non-canonical KOR signaling pathways. This study confirms escalated self-administration of entactogen psychostimulants under LgA conditions in female rats which is accompanied by increased CeA GABAergic inhibition and altered KOR signaling. Collectively, our study suggests that CeA GABA and KOR mechanisms play a critical role in entactogen self-administration like those observed with escalation of alcohol or cocaine self-administration.
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Affiliation(s)
- Sophia Khom
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA, United States
- Department of Pharmaceutical Sciences, University of Vienna, Vienna, Austria
| | - Jacques D. Nguyen
- Department of Neuroscience, The Scripps Research Institute, La Jolla, CA, United States
- Department of Psychiatry, University of California San Diego, La Jolla, CA, United States
| | - Sophia A. Vandewater
- Department of Neuroscience, The Scripps Research Institute, La Jolla, CA, United States
| | - Yanabel Grant
- Department of Neuroscience, The Scripps Research Institute, La Jolla, CA, United States
- Department of Psychiatry, University of California San Diego, La Jolla, CA, United States
| | - Marisa Roberto
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA, United States
| | - Michael A. Taffe
- Department of Neuroscience, The Scripps Research Institute, La Jolla, CA, United States
- Department of Psychiatry, University of California San Diego, La Jolla, CA, United States
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10
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Nguyen JD, Grant Y, Taffe MA. Paradoxical changes in brain reward status during oxycodone self-administration in a novel test of the negative reinforcement hypothesis. Br J Pharmacol 2021; 178:3797-3812. [PMID: 33948939 PMCID: PMC8387405 DOI: 10.1111/bph.15520] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Revised: 04/18/2021] [Accepted: 04/20/2021] [Indexed: 12/27/2022] Open
Abstract
BACKGROUND AND PURPOSE The extra medical use of, and addiction to, prescription opioid analgesics is a growing health problem. To characterize how prescription opioid abuse develops, this study investigated the affective consequences of escalating prescription opioid use using intracranial self-stimulation (ICSS) reward and oxycodone intravenous self-administration (IVSA) models. EXPERIMENTAL APPROACH Male Wistar rats were given access to oxycodone IVSA (0.15 mg·kg-1 per infusion, i.v.) in short-access (ShA; 1 h) or long-access (LgA; 12 h) sessions for five sessions per week followed by intermittent 60-h discontinuations from drug access, a novel explicit test of the negative reinforcement hypothesis. Separate groups were first trained in the ICSS procedure and then in oxycodone IVSA in 11-h LgA sessions. KEY RESULTS Rats given LgA to oxycodone escalated their responding more than ShA rats, with further significant increases observed following each 60-h discontinuation. Presession brain reward thresholds increased with sequential daily LgA IVSA sessions, consistent with a growing negative affective state consequent to successive daily intoxication/abstinence cycles. A 1-h oxycodone IVSA interval was sufficient to normalize these elevated reward thresholds, as was, paradoxically, a 60-h weekend abstinence. The increase in ICSS thresholds was attenuated in a group treated with the long-acting κ-opioid antagonist norbinaltorphimine prior to IVSA training. CONCLUSION AND IMPLICATIONS Changes in brain reward function during escalation of oxycodone self-administration are driven by an interplay between κ-opioid receptor-mediated negative affective state associated with escalated oxycodone intake and dynamic restoration of brain reward status during longer periods of abstinence.
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Affiliation(s)
- 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
| | - Yanabel Grant
- 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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Pantazis CB, Gonzalez LA, Tunstall BJ, Carmack SA, Koob GF, Vendruscolo LF. Cues conditioned to withdrawal and negative reinforcement: Neglected but key motivational elements driving opioid addiction. SCIENCE ADVANCES 2021; 7:7/15/eabf0364. [PMID: 33827822 PMCID: PMC8026136 DOI: 10.1126/sciadv.abf0364] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Accepted: 02/19/2021] [Indexed: 05/07/2023]
Abstract
Opioid use disorder (OUD) is a debilitating disorder that affects millions of people. Neutral cues can acquire motivational properties when paired with the positive emotional effects of drug intoxication to stimulate relapse. However, much less research has been devoted to cues that become conditioned to the aversive effects of opioid withdrawal. We argue that environmental stimuli promote motivation for opioids when cues are paired with withdrawal (conditioned withdrawal) and generate opioid consumption to terminate conditioned withdrawal (conditioned negative reinforcement). We review evidence that cues associated with pain drive opioid consumption, as patients with chronic pain may misuse opioids to escape physical and emotional pain. We highlight sex differences in withdrawal-induced stress reactivity and withdrawal cue processing and discuss neurocircuitry that may underlie withdrawal cue processing in dependent individuals. These studies highlight the importance of studying cues associated with withdrawal in dependent individuals and point to areas for exploration in OUD research.
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Affiliation(s)
- Caroline B Pantazis
- Integrative Neuroscience Research Branch, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Baltimore, MD, USA.
| | - Luis A Gonzalez
- Integrative Neuroscience Research Branch, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Baltimore, MD, USA
- Department of Psychological and Brain Sciences, Krieger School of Arts and Sciences, Johns Hopkins University, Baltimore, MD, USA
| | - Brendan J Tunstall
- Department of Pharmacology, Addiction Science, and Toxicology, University of Tennessee Health Science Center, Memphis, TN, USA
| | - Stephanie A Carmack
- Center for Adaptive Systems of Brain-Body Interactions, George Mason University, Fairfax, VA, USA
| | - George F Koob
- Integrative Neuroscience Research Branch, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Baltimore, MD, USA
| | - Leandro F Vendruscolo
- Integrative Neuroscience Research Branch, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Baltimore, MD, USA.
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