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Hammad AM, Alasmari F, Sari Y. Effect of Modulation of the Astrocytic Glutamate Transporters' Expression on Cocaine-Induced Reinstatement in Male P Rats Exposed to Ethanol. Alcohol Alcohol 2021; 56:210-219. [PMID: 33063090 PMCID: PMC11004936 DOI: 10.1093/alcalc/agaa104] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Revised: 09/18/2020] [Accepted: 09/19/2020] [Indexed: 11/14/2022] Open
Abstract
AIM Reinforcing properties of ethanol and cocaine are mediated in part through the glutamatergic system. Extracellular glutamate concentration is strictly maintained through several glutamate transporters, such as glutamate transporter 1 (GLT-1), cystine/glutamate transporter (xCT) and glutamate aspartate transporter (GLAST). Previous findings revealed that cocaine and ethanol exposure downregulated GLT-1 and xCT, and that β-lactam antibiotics restored their expression. METHODS In this study, we investigated the effect of ampicillin/sulbactam (AMP/SUL) (200 mg/kg, i.p.), a β-lactam antibiotic, on cocaine-induced reinstatement and locomotor activity in male alcohol preferring (P) rats using free choice ethanol (15 and 30%, v/v) and water. We also investigated the effect of co-exposure to ethanol and cocaine (20 mg/kg, i.p.) on GLT-1, xCT and GLAST expression in the nucleus accumbens (NAc) core, NAc shell and dorsomedial prefrontal cortex (dmPFC). RESULTS Cocaine exposure decreased ethanol intake and preference. Cocaine and ethanol co-exposure acquired place preference and increased locomotor activity compared to ethanol-exposed rats. GLT-1 and xCT expression were downregulated after cocaine and ethanol co-exposure in the NAc core and shell, but not in dmPFC. AMP/SUL attenuated reinstatement to cocaine as well attenuated the decrease in locomotor activity and ethanol intake and preference. These effects were associated with upregulation of GLT-1 and xCT expression in the NAc core/shell and dmPFC. GLAST expression was not affected after ethanol and cocaine co-exposure or AMP/SUL treatment. CONCLUSION Our findings demonstrate that astrocytic glutamate transporters within the mesocorticolimbic area are critical targets in modulating cocaine-seeking behavior while being consuming ethanol.
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Affiliation(s)
- Alaa M Hammad
- Department of Pharmacology and Experimental Therapeutics, College of Pharmacy and Pharmaceutical Sciences, University of Toledo, Toledo, OH, USA
- Department of Pharmacy, College of Pharmacy, Al-Zaytoonah University of Jordan, Amman, Jordan
| | - Fawaz Alasmari
- Department of Pharmacology and Experimental Therapeutics, College of Pharmacy and Pharmaceutical Sciences, University of Toledo, Toledo, OH, USA
- Department of Pharmacology and Toxicology, College of Pharmacy, King Saud University, Riyadh, Saudi Arabia
| | - Youssef Sari
- Department of Pharmacology and Experimental Therapeutics, College of Pharmacy and Pharmaceutical Sciences, University of Toledo, Toledo, OH, USA
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Marcos A, Moreno M, Orihuel J, Ucha M, Mª de Paz A, Higuera-Matas A, Capellán R, Crego AL, Martínez-Larrañaga MR, Ambrosio E, Anadón A. The effects of combined intravenous cocaine and ethanol self-administration on the behavioral and amino acid profile of young adult rats. PLoS One 2020; 15:e0227044. [PMID: 32203565 PMCID: PMC7089423 DOI: 10.1371/journal.pone.0227044] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Accepted: 12/11/2019] [Indexed: 12/22/2022] Open
Abstract
Under paradigms of combined intravenous cocaine and ethanol self-administration, the effects on behavior have been poorly explored. Numerous studies have found sex differences in amino acids profile and behavioral responses to each drug, yet few have focused on the interactions between cocaine and ethanol. The main objective of this work was to explore the acquisition and maintenance of intravenous self-administration behavior with a combination of cocaine and ethanol in male and female young adult rats. Likewise, the amino acids profile in blood plasma was quantified 48 hours after the last self-administration session. Male and female 52 days old Wistar rats were randomly assigned to one of 3 groups: i) saline control, ii) cocaine (1 mg/kg bodyweight/injection) and iii) cocaine and ethanol (1 mg + 133 mg/kg bodyweight/ injection). After 24 self-administration sessions carried out on a fixed-ratio-1 schedule, with a limit of 15 doses per session, 14 plasma amino acids were quantified by mean Capillary Electrophoresis technique. The curve of cocaine and ethanol combined self-administration was similar to that associated with cocaine administration alone, with females acquiring self-administration criterion before males. The self-administration of cocaine and ethanol altered the plasma concentration and relative ratios of the amino acid L-Tyrosine. In our intravenous self-administration model, females appeared more vulnerable to acquire abusive consumption of the cocaine and ethanol combination, which altered plasma L-Tyrosine levels.
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Affiliation(s)
- Alberto Marcos
- Psychobiology Department, School of Psychology, Universidad Nacional de Educación a Distancia, Madrid, Spain
| | - Mario Moreno
- Psychobiology Department, School of Psychology, Universidad Nacional de Educación a Distancia, Madrid, Spain
| | - Javier Orihuel
- Psychobiology Department, School of Psychology, Universidad Nacional de Educación a Distancia, Madrid, Spain
| | - Marcos Ucha
- Psychobiology Department, School of Psychology, Universidad Nacional de Educación a Distancia, Madrid, Spain
| | - Ana Mª de Paz
- Departamento de Psicología Básica I, Facultad de Psicología, Universidad Nacional de Educación a Distancia (UNED), Madrid, Spain
| | - Alejandro Higuera-Matas
- Psychobiology Department, School of Psychology, Universidad Nacional de Educación a Distancia, Madrid, Spain
| | - Roberto Capellán
- Psychobiology Department, School of Psychology, Universidad Nacional de Educación a Distancia, Madrid, Spain
| | - Antonio L. Crego
- Departamento de Química Analítica, Química Física e Ingeniería Química, Facultad de Ciencias, Universidad de Alcalá, Ctra. Madrid-Barcelona, Alcalá de Henares, Madrid, Spain
| | - María-Rosa Martínez-Larrañaga
- Department of Pharmacology and Toxicology, Faculty of Veterinary Medicine, Universidad Complutense de Madrid, Madrid, Spain
| | - Emilio Ambrosio
- Psychobiology Department, School of Psychology, Universidad Nacional de Educación a Distancia, Madrid, Spain
- * E-mail:
| | - Arturo Anadón
- Department of Pharmacology and Toxicology, Faculty of Veterinary Medicine, Universidad Complutense de Madrid, Madrid, Spain
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de Carvalho TG, Garcia VB, de Araújo AA, da Silva Gasparotto LH, Silva H, Guerra GCB, de Castro Miguel E, de Carvalho Leitão RF, da Silva Costa DV, Cruz LJ, Chan AB, de Araújo Júnior RF. Spherical neutral gold nanoparticles improve anti-inflammatory response, oxidative stress and fibrosis in alcohol-methamphetamine-induced liver injury in rats. Int J Pharm 2018; 548:1-14. [DOI: 10.1016/j.ijpharm.2018.06.008] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Revised: 05/24/2018] [Accepted: 06/04/2018] [Indexed: 02/07/2023]
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Winkler MC, Greager EM, Stafford J, Bachtell RK. Methamphetamine self-administration reduces alcohol consumption and preference in alcohol-preferring P rats. Addict Biol 2018; 23:90-101. [PMID: 27860181 PMCID: PMC5811924 DOI: 10.1111/adb.12476] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Subclinical levels of polysubstance use are a prevalent and understudied phenomenon. Alcohol is a substance commonly co‐used with other substances of other drug classes. These studies sought to determine the consumption effects of combining alcohol drinking and methamphetamine (MA) self‐administration. Male alcohol‐preferring P rats had continuous access to a two‐bottle alcohol drinking procedure in the home cage. Control rats remained alcohol naïve. Rats were also surgically implanted with intra‐jugular catheters and trained to self‐administer saline (control) or MA in daily 2‐hour sessions. We first measured the acquisition and maintenance of MA intake in alcohol‐consuming or control rats. MA intake was initially enhanced by alcohol consumption on a fixed ratio 1 schedule of reinforcement, but this effect did not prevail as the difficulty of the schedule (FR5 and progressive ratio) was increased. We next measured both alcohol consumption and preference before, during and after MA (or saline) self‐administration. MA self‐administration significantly reduced alcohol intake and preference ratios, a robust effect that persisted across several experimental variations. Interestingly, alcohol consumption rebounded following the cessation of MA self‐administration. The effects of MA self‐administration were specific to alcohol intake because it did not alter total fluid consumption or consumption of sucrose. MA self‐administration did not impact blood‐alcohol concentrations or alcohol‐induced loss of righting reflex suggesting no effect of MA intake on the alcohol metabolism or sensitivity. Together, the results suggest that MA intake disrupts alcohol consumption and preferences but not the reverse in alcohol‐preferring P rats.
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Affiliation(s)
- Madeline C. Winkler
- Department of Psychology and Neuroscience and Center for Neuroscience; University of Colorado Boulder; Boulder CO USA
| | - Emilee M. Greager
- Department of Psychology and Neuroscience and Center for Neuroscience; University of Colorado Boulder; Boulder CO USA
| | - Jacob Stafford
- Department of Psychology and Neuroscience and Center for Neuroscience; University of Colorado Boulder; Boulder CO USA
| | - Ryan K. Bachtell
- Department of Psychology and Neuroscience and Center for Neuroscience; University of Colorado Boulder; Boulder CO USA
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5
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Lê A, Kalant H. Intravenous self-administration of alcohol in rats-problems with translation to humans. Addict Biol 2017; 22:1665-1681. [PMID: 27480572 PMCID: PMC5290288 DOI: 10.1111/adb.12429] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Revised: 05/24/2016] [Accepted: 06/17/2016] [Indexed: 12/16/2022]
Abstract
Alcohol is consumed orally by humans, and oral self-administration has been successfully modeled in laboratory animals. Over the last several years, attempts have been made to develop a procedure for the reliable intravenous (IV) self-administration of alcohol in rodents. IV self-administration would provide a better tool for investigating neurobiological mechanisms of alcohol reinforcement and dependence because confounding factors associated with oral self-administration, such as variations in orosensory sensitivity to alcohol and/or its absorption, are avoided. A review of the literature shows that rats, mice and non-human primates can initiate and maintain IV self-administration of alcohol. However, there are 50- to 100-fold interspecies differences in the reported alcohol infusion doses required. Most surprising is that the infusion dose (1-2 mg/kg) that reliably maintains IV alcohol self-administration in rats results in total alcohol intakes of only 20-25 mg/kg/hour, which are unlikely to have significant pharmacological effects. The evidence to support IV self-administration of such low doses of alcohol in rats as well as the potential biological mechanisms underlying such self-administration are discussed. The minute amounts of alcohol shown to reliably maintain IV self-administration behavior in rats challenge the relationship between their blood alcohol levels and the rewarding and reinforcing effects of alcohol.
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Affiliation(s)
- A.D. Lê
- Neurobiology of Alcohol Laboratory, Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, Canada
- Department of Pharmacology and Toxicology, University of Toronto
- Department of Psychiatry, University of Toronto
| | - H. Kalant
- Department of Pharmacology and Toxicology, University of Toronto
- Centre for Addiction and Mental Health, Research Division
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6
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Hammad AM, Althobaiti YS, Das SC, Sari Y. Effects of repeated cocaine exposure and withdrawal on voluntary ethanol drinking, and the expression of glial glutamate transporters in mesocorticolimbic system of P rats. Mol Cell Neurosci 2017; 82:58-65. [PMID: 28442364 DOI: 10.1016/j.mcn.2017.04.008] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Revised: 03/18/2017] [Accepted: 04/20/2017] [Indexed: 11/26/2022] Open
Abstract
Glutamatergic neurotransmission within the brain's reward circuits plays a major role in the reinforcing properties of both ethanol and cocaine. Glutamate homeostasis is regulated by several glutamate transporters, including glutamate transporter type 1 (GLT-1), cystine/glutamate transporter (xCT), and glutamate aspartate transporter (GLAST). Cocaine exposure has been shown to induce a dysregulation in glutamate homeostasis and a decrease in the expression of GLT-1 and xCT in the nucleus accumbens (NAc). In this study, alcohol preferring (P) rats were exposed to free-choice of ethanol (15% and 30%) and/or water for five weeks. On Week 6, rats were administered (i.p.) cocaine (10 and 20mg/kg) or saline for 12 consecutive days. This study tested two groups of rats: the first group was euthanized after seven days of repeated cocaine i.p. injection, and the second group was deprived from cocaine for five days and euthanized at Day 5 after cocaine withdrawal. Only repeated cocaine (20mg/kg, i.p.) exposure decreased ethanol intake from Day 3 through Day 8. Co-exposure of cocaine and ethanol decreased the relative mRNA expression and the expression of GLT-1 in the NAc but not in the medial prefrontal cortex (mPFC). Importantly, co-exposure of cocaine and ethanol decreased relative expression of xCT in the NAc but not in the mPFC. Our findings demonstrated that chronic cocaine exposure affects ethanol intake; and ethanol and cocaine co-abuse alters the expression of glial glutamate transporters.
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Affiliation(s)
- Alaa M Hammad
- Department of Pharmacology and Experimental Therapeutics, College of Pharmacy and Pharmaceutical Sciences, University of Toledo, Toledo, OH, USA
| | - Yusuf S Althobaiti
- Department of Pharmacology and Experimental Therapeutics, College of Pharmacy and Pharmaceutical Sciences, University of Toledo, Toledo, OH, USA
| | - Sujan C Das
- Department of Pharmacology and Experimental Therapeutics, College of Pharmacy and Pharmaceutical Sciences, University of Toledo, Toledo, OH, USA
| | - Youssef Sari
- Department of Pharmacology and Experimental Therapeutics, College of Pharmacy and Pharmaceutical Sciences, University of Toledo, Toledo, OH, USA.
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Karatayev O, Lukatskaya O, Moon SH, Guo WR, Chen D, Algava D, Abedi S, Leibowitz SF. Nicotine and ethanol co-use in Long-Evans rats: Stimulatory effects of perinatal exposure to a fat-rich diet. Alcohol 2015; 49:479-89. [PMID: 25979531 DOI: 10.1016/j.alcohol.2015.03.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2014] [Revised: 03/09/2015] [Accepted: 03/11/2015] [Indexed: 12/14/2022]
Abstract
Clinical studies demonstrate frequent co-existence of nicotine and alcohol abuse and suggest that this may result, in part, from the ready access to and intake of fat-rich diets. Whereas animal studies show that high-fat diet intake in adults can enhance the consumption of either nicotine or ethanol and that maternal consumption of a fat-rich diet during pregnancy increases operant responding for nicotine in offspring, little is known about the impact of dietary fat on the co-abuse of these two drugs. The goal of this study was to test in Long-Evans rats the effects of perinatal exposure to fat on the co-use of nicotine and ethanol, using a novel paradigm that involves simultaneous intravenous (IV) self-administration of these two drugs. Fat- vs. chow-exposed offspring were characterized and compared, first in terms of their nicotine self-administration behavior, then in terms of their nicotine/ethanol self-administration behavior, and lastly in terms of their self-administration of ethanol in the absence of nicotine. The results demonstrate that maternal consumption of fat compared to low-fat chow during gestation and lactation significantly stimulates nicotine self-administration during fixed-ratio testing. It also increases nicotine/ethanol self-administration during fixed-ratio and dose-response testing, with BEC elevated to 120 mg/dL, and causes an increase in breakpoint during progressive ratio testing. Of particular note is the finding that rats perinatally exposed to fat self-administer significantly more of the nicotine/ethanol mixture as compared to nicotine alone, an effect not evident in the chow-control rats. After removal of nicotine from the nicotine/ethanol mixture, this difference between the fat- and chow-exposed rats was lost, with both groups failing to acquire the self-administration of ethanol alone. Together, these findings suggest that perinatal exposure to a fat-rich diet, in addition to stimulating self-administration of nicotine, causes an even greater vulnerability to the excessive co-use of nicotine and ethanol.
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8
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Hauser SR, Wilden JA, Deehan GA, McBride WJ, Rodd ZA. Cocaine influences alcohol-seeking behavior and relapse drinking in alcohol-preferring (P) rats. Alcohol Clin Exp Res 2015; 38:2678-86. [PMID: 25346508 DOI: 10.1111/acer.12540] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2014] [Accepted: 08/01/2014] [Indexed: 11/30/2022]
Abstract
BACKGROUND The results of several studies suggest that there may be common neurocircuits regulating drug-seeking behaviors. Common biological pathways regulating drug-seeking would explain the phenomenon that seeking for 1 drug can be enhanced by exposure to another drug of abuse. The objective of this study was to assess the time course effects of acute cocaine administration on ethanol (EtOH) seeking and relapse. METHODS Alcohol-preferring (P) rats were allowed to self-administer 15% EtOH and water. EtOH-seeking was assessed through the use of the Pavlovian spontaneous recovery (PSR) model, while EtOH-relapse drinking was assessed through the use of the alcohol-deprivation effect. RESULTS Cocaine (0, 1, or 10 mg/kg), injected immediately, 30 minutes, or 4 hours prior to the first PSR testing session, dose-dependently increased responding on the EtOH lever compared to extinction responses and responding by saline controls. Under relapse conditions, cocaine given immediately prior to the relapse session had no effect (1 mg/kg) or reduced responding (10 mg/kg). In contrast, cocaine given 4 hours prior to the relapse session markedly enhanced EtOH responding compared to saline. CONCLUSIONS The enhanced expression of EtOH-seeking and EtOH-relapse behaviors may be a result of a priming effect of cocaine on neuronal circuits mediating these behaviors. The effect of cocaine on EtOH-relapse drinking is indicative of the complex interactions that can occur between drugs of abuse; production of conflicting behaviors (immediate), and priming of relapse/seeking (4-hour delay).
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Affiliation(s)
- Sheketha R Hauser
- Department of Psychiatry, Institute of Psychiatric Research, Indiana University School of Medicine, Indianapolis, Indiana
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Windisch KA, Kosobud AEK, Czachowski CL. Intravenous alcohol self-administration in the P rat. Alcohol 2014; 48:419-25. [PMID: 24835637 DOI: 10.1016/j.alcohol.2013.12.007] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2013] [Revised: 12/18/2013] [Accepted: 12/27/2013] [Indexed: 11/29/2022]
Abstract
Alcohol consumption produces a complex array of effects that can be divided into two types: the explicit pharmacological effects of ethanol (which can be temporally separate from time of intake) and the more temporally "relevant" effects (primarily olfactory and taste) that bridge the time from intake to onset of the pharmacological effects. Intravenous (IV) self-administration of ethanol limits the confounding "non-pharmacological" effects associated with oral consumption, allows for controlled and precise dosing, and bypasses first order absorption kinetics, allowing for more direct and better-controlled assessment of alcohol's effect on the brain. IV ethanol self-administration has been reliably demonstrated in mouse and human experimental models; however, models of IV self-administration have been historically problematic in the rat. An operant multiple-schedule study design was used to elucidate the role of each component of a compound IV-ethanol plus oral-sucrose reinforcer. Male alcohol-preferring P rats had free access to both food and water during all IV self-administration sessions. Animals were trained to press a lever for orally delivered 1% sucrose (1S) on a fixed ratio 4 schedule, and then surgically implanted with an indwelling jugular catheter. Animals were then trained to respond on a multiple FR4-FR4 schedule composed of alternating 2.5-min components across 30-min sessions. For the multiple schedule, two components were used: an oral 1S only and an oral 1S plus IV 20% ethanol (25 mg/kg/injection). Average total ethanol intake was 0.47 ± 0.04 g/kg. We found significantly higher earning of sucrose-only reinforcers and greater sucrose-lever error responding relative to the compound oral-sucrose plus IV-ethanol reinforcer. These response patterns suggest that sucrose, not ethanol, was responsible for driving overall responding. The work with a compound IV ethanol-oral sucrose reinforcer presented here suggests that the existing intravenous ethanol self-administration methodology cannot overcome the aversive properties of ethanol via this route in the rat.
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Affiliation(s)
- Kyle A Windisch
- Department of Psychology, Indiana University-Purdue University, 402 N. Blackford St. LD124, Indianapolis, IN 46202, USA
| | - Ann E K Kosobud
- Department of Psychology, Indiana University-Purdue University, 402 N. Blackford St. LD124, Indianapolis, IN 46202, USA
| | - Cristine L Czachowski
- Department of Psychology, Indiana University-Purdue University, 402 N. Blackford St. LD124, Indianapolis, IN 46202, USA.
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Davis CM, Riley AL. Conditioned taste aversion learning: implications for animal models of drug abuse. Ann N Y Acad Sci 2010; 1187:247-75. [PMID: 20201857 DOI: 10.1111/j.1749-6632.2009.05147.x] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Drugs of abuse are typically discussed in terms of their rewarding effects and how these effects mediate drug taking. However, these drugs produce aversive effects that could have an important role in the overall acceptability of a drug and its likelihood of being self-administered. Rewarding and aversive effects, then, could be interpreted as separate behavioral effects, with the balance of the two determining overall drug acceptability. Interestingly, the role of aversive effects on drug acceptability in the self-administration preparation has received limited attention in this context. This chapter examines the aversive effects of drugs and discusses their role in drug taking. If these aversive effects serve a protective function, manipulations that alter or decrease these effects could have implications for drug taking. Several factors have been reported to alter conditioned taste aversion (CTA) learning, a preparation used in the assessment of the aversive effects of drugs in general. Two of these factors, drug history and strain, are reviewed here. By reviewing these, we intend to demonstrate the protective nature of aversive effects in the initiation and escalation of drug taking and to provide evidence that reductions in aversive effects could produce changes in patterns of drug self-administration that could lead to an increased vulnerability to abuse drugs by altering the reward-aversion balance. The aim of this chapter is not to question the importance of rewarding effects in self-administration but rather to provide evidence that aversive effects are an important factor that needs to be considered in discussions of drug-taking behavior.
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Affiliation(s)
- Catherine M Davis
- Psychopharmacology Laboratory, Department of Psychology, American University, Washington, DC, USA.
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Self-administration of drug mixtures by monkeys: combining drugs with comparable mechanisms of action. Psychopharmacology (Berl) 2008; 196:575-82. [PMID: 18026937 PMCID: PMC3109501 DOI: 10.1007/s00213-007-0991-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/09/2007] [Accepted: 10/16/2007] [Indexed: 10/22/2022]
Abstract
RATIONALE Abuse of drug mixtures is common. Drug interactions that are super-additive in terms of reinforcing effects may contribute to this phenomenon. Although quantitative methods for assessing drug interactions have been developed, they have not been widely applied to the analysis of reinforcing effects. OBJECTIVES The present experiment was designed to study self-administration of mixtures of drugs with comparable pharmacological mechanisms of action. Our hypothesis was that the drugs would be dose-additive. MATERIALS AND METHODS Rhesus monkeys prepared with i.v. catheters were allowed to self-administer cocaine or saline under a progressive-ratio schedule in baseline sessions. When responding was stable, two mu opioid agonists, alfentanil and remifentanil, were tested alone in one group (n = 5). Two dopamine (DA) uptake blockers, cocaine and RTI-117 were tested in the other group (n = 6). Next, mixtures of doses of the two opioids or the two DA uptake blockers were tested in approximate 1:1, 1:2, and 2:1 ratios of their ED50s. Results were analyzed using isobolographic techniques. RESULTS All drugs alone and drug mixtures functioned as positive reinforcers in a dose-related manner. There was no difference between experimentally determined ED50 values and predicted additive ED50 values for any mixture. Maximum responding maintained by mixtures, a measure of reinforcing strength, did not differ from that for single drugs. CONCLUSIONS Mixtures of various proportions of two drugs with comparable mechanisms of action were additive, i.e., they did not interact. This result will serve as the basis for comparison to studies of mixtures of drugs with various mechanisms of action.
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Gass JT, Olive MF. Reinstatement of ethanol-seeking behavior following intravenous self-administration in Wistar rats. Alcohol Clin Exp Res 2007; 31:1441-5. [PMID: 17666107 DOI: 10.1111/j.1530-0277.2007.00480.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
BACKGROUND In animal models of alcoholism, subjects are traditionally trained to self-administer ethanol via the oral route. However, ethanol is also self-administered intravenously (IV), a paradigm which offers several advantages over oral self-administration methods, including immediate delivery to the bloodstream, more rapid onset of pharmacological effects, and elimination of the need to utilize tastants or sweeteners to mask the aversive orosensory properties of ethanol. However, no studies to date have examined reinstatement of ethanol-seeking behavior in animals with a history of IV ethanol self-administration. METHODS Male Wistar rats were implanted with indwelling jugular vein catheters and trained to self-administer ethanol IV (1% v/v solution, equivalent to 1 mg/kg) in an operant lever-pressing paradigm in twice daily 1 hour sessions. Each IV delivery of ethanol was paired with presentation of a light-tone complex stimulus. After stabilization of response patterns, IV self-administration behavior was subjected to extinction procedures. Next, animals were exposed to the three types of stimuli known to reinstate ethanol-seeking behavior: presentation of ethanol-associated cues, a priming dose of ethanol (0.5 g/kg i.p.), or exposure to stress via administration of the anxiogenic compound yohimbine (2.5 mg/kg i.p.) or its corresponding vehicle. RESULTS During the maintenance phase of self-administration, animals exhibited significantly more presses on the lever that delivered the ethanol solution than the inactive lever, indicating that IV ethanol functioned as a positive reinforcer. Following extinction, it was found that ethanol-seeking behavior could be reinstated by all three types of stimuli (cues, ethanol priming, and yohimbine). Vehicle injection did not affect responding on either lever. CONCLUSIONS Ethanol serves as a reinforcer when self-administered IV, and following extinction, ethanol-seeking behavior can be reinstated by ethanol-associated cues, ethanol priming, or a pharmacological stressor. Thus, reinstatement of ethanol-seeking behavior in animals with a history of IV ethanol self-administration may be a novel animal model of relapse.
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Affiliation(s)
- Justin T Gass
- Center for Drug and Alcohol Programs, Department of Psychiatry and Behavioral Sciences, Medical University of South Carolina, Charleston, South Carolina 29425, USA
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Gonzales RA, Job MO, Doyon WM. The role of mesolimbic dopamine in the development and maintenance of ethanol reinforcement. Pharmacol Ther 2005; 103:121-46. [PMID: 15369680 DOI: 10.1016/j.pharmthera.2004.06.002] [Citation(s) in RCA: 240] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The neurobiological processes by which ethanol seeking and consumption are established and maintained are thought to involve areas of the brain that mediate motivated behavior, such as the mesolimbic dopamine system. The mesolimbic dopamine system is comprised of cells that originate in the ventral tegmental area (VTA) and project to several forebrain regions, including a prominent terminal area, the nucleus accumbens (NAcc). The NAcc has been subdivided into core and shell subregions. Both areas receive converging excitatory input from the cortex and amygdala and dopamine input from the VTA, with the accumbal medium spiny neuron situated to integrate the signals. Although forced ethanol administration enhances dopamine activity in the NAcc, conclusions regarding the role of mesolimbic dopamine in ethanol reinforcement cannot be made from these experiments. Behavioral experiments consistently show that pharmacological manipulations of the dopamine transmission in the NAcc alter responding for ethanol, although ethanol reinforcement is maintained after lesions of the accumbal dopamine system. Additionally, extracellular dopamine increases in the NAcc during operant self-administration of ethanol, which is consistent with a role of dopamine in ethanol reinforcement. Behavioral studies that distinguish appetitive responding from ethanol consumption show that dopamine is important in ethanol-seeking behavior, whereas neurochemical studies suggest that accumbal dopamine is also important during ethanol consumption before pharmacological effects occur. Cellular studies suggest that ethanol alters synaptic plasticity in the mesolimbic system, possibly through dopaminergic mechanisms, and this may underlie the development of ethanol reinforcement. Thus, anatomical, pharmacological, neurochemical, cellular, and behavioral studies are more clearly defining the role of mesolimbic dopamine in ethanol reinforcement.
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Affiliation(s)
- Rueben A Gonzales
- Department of Pharmacology, College of Pharmacy, The University of Texas at Austin, 1 University Station A1915, Austin, TX 78712-0125, USA.
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Berlanga ML, Olsen CM, Chen V, Ikegami A, Herring BE, Duvauchelle CL, Alcantara AA. Cholinergic interneurons of the nucleus accumbens and dorsal striatum are activated by the self-administration of cocaine. Neuroscience 2003; 120:1149-56. [PMID: 12927219 DOI: 10.1016/s0306-4522(03)00378-6] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The nucleus accumbens, a major component of the ventral striatum, and the dorsal striatum are primary targets of the mesolimbic dopamine pathway, which is a pathway that plays a critical role in reward and addiction. The shell compartment of the nucleus accumbens and the ventromedial striatum, in particular, receive extensive afferent projections from the ventral tegmental area, which is the major afferent source of the mesolimbic pathway [Prog Brain Res 99 (1993) 209; J Neurosci 7 (1987) 3915]. The present study focused on striatal cholinergic interneurons as potential key neurons involved in the neural basis of drug reinforcement. The main finding of this study is that cholinergic interneurons located in the shell compartment of the nucleus accumbens and the ventromedial striatum were activated, as measured by Fos labeling, following a 1 h session of the self-administration of cocaine in rats. A direct correlation existed between the percent of cholinergic interneurons that were activated and the amount of cocaine that was self-administered. The greatest amount of administered cocaine (approximately 10 mg/kg) resulted in the activation of approximately 80% of the cholinergic neurons. No such correlation existed in the group of animals that self-administered saline. In addition, activation was not found in the core compartment of the nucleus accumbens or the dorsolateral striatum, which receive extensive innervation from the substantia nigra and thus are more closely tied to the motor effects of the drug. In conclusion, cocaine-driven neuronal activation was specific to the shell compartment of the nucleus accumbens (R(2)=0.9365) and the ventromedial striatum (R(2)=0.9059). These findings demonstrate that cholinergic interneurons are involved in the initial stage of cocaine intake and that these neurons are located in areas of the nucleus accumbens and dorsal striatum that are more closely tied to the rewarding and hedonic effects rather than the motor effects of cocaine intake.
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Affiliation(s)
- M L Berlanga
- Institute for Neuroscience, The University of Texas at Austin, Austin, TX 78712, USA
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