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Models of Drug Addiction: Translating Molecular Targets into Molecular Medicine

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A special issue of International Journal of Molecular Sciences (ISSN 1422-0067). This special issue belongs to the section "Molecular Pharmacology".

Deadline for manuscript submissions: closed (30 April 2022) | Viewed by 30155

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Assoc. Prof. Zachary A. Rodd

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Department of Psychiatry, Institute of Psychiatric Research, Indiana University School of Medicine, Indianapolis, IN, USA
Interests: neurocircuitry of drug reward; polysubstance use/abuse; adolescent drug research; therapeutic treatment of addiction

Special Issue Information

Dear Colleagues,

Each year, novel models/experimental procedures are added to the repertoire of methods that researchers can apply to examine various aspects of addiction. A major problem in the field is that models are not discarded when overwhelming evidence indicates that they are not valid or are fatally flawed. The adherence to these ‘tried and true’ invalid models inhibits the progression of the field and reduces the impact of novel, and potentially important, models. The goal of this Special Issue of the International Journal of Molecular Science is to provide the field with theoretical discussions on the plethora of addiction models available. We encourage all authors to take positions, and we would welcome co-authored manuscripts from researchers with divergent opinions.

Assoc. Prof. Zachary A. Rodd
Guest Editor

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Keywords

addiction
model development
validity testing
preclinical
population
excessive drug use
drug-seeking
polydrug abuse.

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Published Papers (9 papers)

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16 pages, 3458 KiB

Open AccessArticle

A Novel Morphine Drinking Model of Opioid Dependence in Rats

by Pablo Berríos-Cárcamo, Mauricio Quezada, Daniela Santapau, Paola Morales, Belén Olivares, Carolina Ponce, Alba Ávila, Cristian De Gregorio, Marcelo Ezquer, María Elena Quintanilla, Mario Herrera-Marschitz, Yedy Israel and Fernando Ezquer

Int. J. Mol. Sci. 2022, 23(7), 3874; https://doi.org/10.3390/ijms23073874 - 31 Mar 2022

Cited by 11 | Viewed by 3053

Abstract

An animal model of voluntary oral morphine consumption would allow for a pre-clinical evaluation of new treatments aimed at reducing opioid intake in humans. However, the main limitation of oral morphine consumption in rodents is its bitter taste, which is strongly aversive. Taste aversion is often overcome by the use of adulterants, such as sweeteners, to conceal morphine taste or bitterants in the alternative bottle to equalize aversion. However, the adulterants’ presence is the cause for consumption choice and, upon removal, the preference for morphine is not preserved. Thus, current animal models are not suitable to study treatments aimed at reducing consumption elicited by morphine itself. Since taste preference is a learned behavior, just-weaned rats were trained to accept a bitter taste, adding the bitterant quinine to their drinking water for one week. The latter was followed by allowing the choice of quinine or morphine (0.15 mg/mL) solutions for two weeks. Then, quinine was removed, and the preference for morphine against water was evaluated. Using this paradigm, we show that rats highly preferred the consumption of morphine over water, reaching a voluntary morphine intake of 15 mg/kg/day. Morphine consumption led to significant analgesia and hyperlocomotion, and to a marked deprivation syndrome following the administration of the opioid antagonist naloxone. Voluntary morphine consumption was also shown to generate brain oxidative stress and neuroinflammation, signs associated with opioid dependence development. We present a robust two-bottle choice animal model of oral morphine self-administration for the evaluation of therapeutic interventions for the treatment of morphine dependence. Full article

(This article belongs to the Special Issue Models of Drug Addiction: Translating Molecular Targets into Molecular Medicine)

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22 pages, 23134 KiB

Open AccessArticle

Adolescent Intermittent Ethanol (AIE) Enhances the Dopaminergic Response to Ethanol within the Mesolimbic Pathway during Adulthood: Alterations in Cholinergic/Dopaminergic Genes Expression in the Nucleus Accumbens Shell

by Sheketha R. Hauser, Patrick J. Mulholland, William A. Truitt, R. Aaron Waeiss, Eric A. Engleman, Richard L. Bell and Zachary A. Rodd

Int. J. Mol. Sci. 2021, 22(21), 11733; https://doi.org/10.3390/ijms222111733 - 29 Oct 2021

Cited by 7 | Viewed by 2337

Abstract

A consistent preclinical finding is that exposure to alcohol during adolescence produces a persistent hyperdopaminergic state during adulthood. The current experiments determine that effects of Adolescent Intermittent Ethanol (AIE) on the adult neurochemical response to EtOH administered directly into the mesolimbic dopamine system, alterations in dendritic spine and gene expression within the nucleus accumbens shell (AcbSh), and if treatment with the HDACII inhibitor TSA could normalize the consequences of AIE. Rats were exposed to the AIE (4 g/kg ig; 3 days a week) or water (CON) during adolescence, and all testing occurred during adulthood. CON and AIE rats were microinjected with EtOH directly into the posterior VTA and dopamine and glutamate levels were recorded in the AcbSh. Separate groups of AIE and CON rats were sacrificed during adulthood and Taqman arrays and dendritic spine morphology assessments were performed. The data indicated that exposure to AIE resulted in a significant leftward and upward shift in the dose-response curve for an increase in dopamine in the AcbSh following EtOH microinjection into the posterior VTA. Taqman array indicated that AIE exposure affected the expression of target genes (Chrna7, Impact, Chrna5). The data indicated no alterations in dendritic spine morphology in the AcbSh or any alteration in AIE effects by TSA administration. Binge-like EtOH exposure during adolescence enhances the response to acute ethanol challenge in adulthood, demonstrating that AIE produces a hyperdopaminergic mesolimbic system in both male and female Wistar rats. The neuroadaptations induced by AIE in the AcbSh could be part of the biological basis of the observed negative consequences of adolescent binge-like alcohol exposure on adult drug self-administration behaviors. Full article

(This article belongs to the Special Issue Models of Drug Addiction: Translating Molecular Targets into Molecular Medicine)

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23 pages, 2828 KiB

Open AccessArticle

Selective Inhibition of PDE4B Reduces Binge Drinking in Two C57BL/6 Substrains

by C. Leonardo Jimenez Chavez, Camron D. Bryant, Melissa A. Munn-Chernoff and Karen K. Szumlinski

Int. J. Mol. Sci. 2021, 22(11), 5443; https://doi.org/10.3390/ijms22115443 - 21 May 2021

Cited by 12 | Viewed by 2824

Abstract

Cyclic AMP (cAMP)-dependent signaling is highly implicated in the pathophysiology of alcohol use disorder (AUD), with evidence supporting the efficacy of inhibiting the cAMP hydrolyzing enzyme phosphodiesterase 4 (PDE4) as a therapeutic strategy for drinking reduction. Off-target emetic effects associated with non-selective PDE4 inhibitors has prompted the development of selective PDE4 isozyme inhibitors for treating neuropsychiatric conditions. Herein, we examined the effect of a selective PDE4B inhibitor A33 (0–1.0 mg/kg) on alcohol drinking in both female and male mice from two genetically distinct C57BL/6 substrains. Under two different binge-drinking procedures, A33 pretreatment reduced alcohol intake in male and female mice of both substrains. In both drinking studies, there was no evidence for carry-over effects the next day; however, we did observe some sign of tolerance to A33’s effect on alcohol intake upon repeated, intermittent, treatment (5 injections of 1.0 mg/kg, every other day). Pretreatment with 1.0 mg/kg of A33 augmented sucrose intake by C57BL/6NJ, but not C57BL/6J, mice. In mice with a prior history of A33 pretreatment during alcohol-drinking, A33 (1.0 mg/kg) did not alter spontaneous locomotor activity or basal motor coordination, nor did it alter alcohol’s effects on motor activity, coordination or sedation. In a distinct cohort of alcohol-naïve mice, acute pretreatment with 1.0 mg/kg of A33 did not alter motor performance on a rotarod and reduced sensitivity to the acute intoxicating effects of alcohol. These data provide the first evidence that selective PDE4B inhibition is an effective strategy for reducing excessive alcohol intake in murine models of binge drinking, with minimal off-target effects. Despite reducing sensitivity to acute alcohol intoxication, PDE4B inhibition reduces binge alcohol drinking, without influencing behavioral sensitivity to alcohol in alcohol-experienced mice. Furthermore, A33 is equally effective in males and females and exerts a quantitatively similar reduction in alcohol intake in mice with a genetic predisposition for high versus moderate alcohol preference. Such findings further support the safety and potential clinical utility of targeting PDE4 for treating AUD. Full article

(This article belongs to the Special Issue Models of Drug Addiction: Translating Molecular Targets into Molecular Medicine)

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18 pages, 2004 KiB

Open AccessArticle

Preliminary Evidence for a Relationship between Elevated Plasma TNFα and Smaller Subcortical White Matter Volume in HCV Infection Irrespective of HIV or AUD Comorbidity

by Natalie M. Zahr, Kilian M. Pohl, Allison J. Kwong, Edith V. Sullivan and Adolf Pfefferbaum

Int. J. Mol. Sci. 2021, 22(9), 4953; https://doi.org/10.3390/ijms22094953 - 7 May 2021

Cited by 7 | Viewed by 2379

Abstract

Classical inflammation in response to bacterial, parasitic, or viral infections such as HIV includes local recruitment of neutrophils and macrophages and the production of proinflammatory cytokines and chemokines. Proposed biomarkers of organ integrity in Alcohol Use Disorders (AUD) include elevations in peripheral plasma levels of proinflammatory proteins. In testing this proposal, previous work included a group of human immunodeficiency virus (HIV)-infected individuals as positive controls and identified elevations in the soluble proteins TNFα and IP10; these cytokines were only elevated in AUD individuals seropositive for hepatitis C infection (HCV). The current observational, cross-sectional study evaluated whether higher levels of these proinflammatory cytokines would be associated with compromised brain integrity. Soluble protein levels were quantified in 86 healthy controls, 132 individuals with AUD, 54 individuals seropositive for HIV, and 49 individuals with AUD and HIV. Among the patient groups, HCV was present in 24 of the individuals with AUD, 13 individuals with HIV, and 20 of the individuals in the comorbid AUD and HIV group. Soluble protein levels were correlated to regional brain volumes as quantified with structural magnetic resonance imaging (MRI). In addition to higher levels of TNFα and IP10 in the 2 HIV groups and the HCV-seropositive AUD group, this study identified lower levels of IL1β in the 3 patient groups relative to the control group. Only TNFα, however, showed a relationship with brain integrity: in HCV or HIV infection, higher peripheral levels of TNFα correlated with smaller subcortical white matter volume. These preliminary results highlight the privileged status of TNFα on brain integrity in the context of infection. Full article

(This article belongs to the Special Issue Models of Drug Addiction: Translating Molecular Targets into Molecular Medicine)

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12 pages, 673 KiB

Open AccessArticle

Effect of Glucocorticoid Receptor Antagonism on Alcohol Self-Administration in Genetically-Selected Marchigian Sardinian Alcohol-Preferring and Non-Preferring Wistar Rats

by Federica Benvenuti, Nazzareno Cannella, Serena Stopponi, Laura Soverchia, Massimo Ubaldi, Veronica Lunerti, Valentina Vozella, Bryan Cruz, Marisa Roberto and Roberto Ciccocioppo

Int. J. Mol. Sci. 2021, 22(8), 4184; https://doi.org/10.3390/ijms22084184 - 17 Apr 2021

Cited by 15 | Viewed by 2427

Abstract

Alcoholism is a chronically relapsing disorder characterized by high alcohol intake and a negative emotional state during abstinence, which contributes to excessive drinking and susceptibility to relapse. Stress, dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis and alterations in glucocorticoid receptor (GR) function have been linked to transition from recreational consumption to alcohol use disorder (AUD). Here, we investigated the effect of pharmacological antagonisms of GR on alcohol self-administration (SA) using male and female Wistar and Marchigian Sardinian alcohol-preferring (msP) rats, a rodent line genetically selected for excessive alcohol drinking and highly sensitive to stress. Animals were trained to self-administer 10% (v/v) alcohol. Once a stable alcohol SA baseline was reached, we tested the effect of the GR antagonists mifepristone (0.0, 10, 30 and 60 mg/kg; i.p.) and CORT113176 (0.0, 10, 30 and 60 mg/kg) on alcohol SA. To evaluate whether the effects of the two compounds were specific for alcohol, the two drugs were tested on a similar saccharin SA regimen. Finally, basal blood corticosterone (CORT) levels before and after alcohol SA were determined. Systemic injection with mifepristone dose-dependently reduced alcohol SA in male and female Wistars but not in msPs. Administration of CORT113176 decreased alcohol SA in male and female Wistars as well as in female msPs but not in male msP rats. At the highest dose, mifepristone also reduced saccharin SA in male Wistars and female msPs, suggesting the occurrence of some nonspecific effects at 60 mg/kg of the drug. Similarly, the highest dose of CORT113176 (60 mg/kg) decreased saccharin intake in male Wistars. Analysis of CORT levels revealed that females of both rat lines had higher blood levels of CORT compared to males. Alcohol consumption reduced CORT in females but not in males. Overall, these findings indicate that selective blockade of GR selectively reduces alcohol SA, and genetically selected msP rats are less sensitive to this pharmacological manipulation compared to heterogeneous Wistars. Moreover, results suggest sex differences in response to GR antagonism and the ability of alcohol to regulate GR transmission. Full article

(This article belongs to the Special Issue Models of Drug Addiction: Translating Molecular Targets into Molecular Medicine)

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25 pages, 7003 KiB

Open AccessArticle

Distinct Regulation of Dopamine D3 Receptor in the Basolateral Amygdala and Dentate Gyrus during the Reinstatement of Cocaine CPP Induced by Drug Priming and Social Stress

by Rocío Guerrero-Bautista, Aurelio Franco-García, Juana M. Hidalgo, Francisco José Fernández-Gómez, Bruno Ribeiro Do Couto, M. Victoria Milanés and Cristina Núñez

Int. J. Mol. Sci. 2021, 22(6), 3100; https://doi.org/10.3390/ijms22063100 - 18 Mar 2021

Cited by 8 | Viewed by 3711

Abstract

Relapse in the seeking and intake of cocaine is one of the main challenges when treating its addiction. Among the triggering factors for the recurrence of cocaine use are the re-exposure to the drug and stressful events. Cocaine relapse engages the activity of memory-related nuclei, such as the basolateral amygdala (BLA) and the hippocampal dentate gyrus (DG), which are responsible for emotional and episodic memories. Moreover, D3 receptor (D3R) antagonists have recently arisen as a potential treatment for preventing drug relapse. Thus, we have assessed the impact of D3R blockade in the expression of some dopaminergic markers and the activity of the mTOR pathway, which is modulated by D3R, in the BLA and DG during the reinstatement of cocaine-induced conditioned place preference (CPP) evoked by drug priming and social stress. Reinstatement of cocaine CPP paralleled an increasing trend in D3R and dopamine transporter (DAT) levels in the BLA. Social stress, but not drug-induced reactivation of cocaine memories, was prevented by systemic administration of SB-277011-A (a selective D3R antagonist), which was able, however, to impede D3R and DAT up-regulation in the BLA during CPP reinstatement evoked by both stress and cocaine. Concomitant with cocaine CPP reactivation, a diminution in mTOR phosphorylation (activation) in the BLA and DG occurred, which was inhibited by D3R blockade in both nuclei before the social stress episode and only in the BLA when CPP reinstatement was provoked by a cocaine prime. Our data, while supporting a main role for D3R signalling in the BLA in the reactivation of cocaine memories evoked by social stress, indicate that different neural circuits and signalling mechanisms might mediate in the reinstatement of cocaine-seeking behaviours depending upon the triggering stimuli. Full article

(This article belongs to the Special Issue Models of Drug Addiction: Translating Molecular Targets into Molecular Medicine)

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14 pages, 1317 KiB

Open AccessArticle

Glucocorticoid Receptor Antagonist Mifepristone Does Not Alter Innate Anxiety-Like Behavior in Genetically-Selected Marchigian Sardinian (msP) Rats

by Valentina Vozella, Bryan Cruz, Luis A. Natividad, Federica Benvenuti, Nazzareno Cannella, Scott Edwards, Eric P. Zorrilla, Roberto Ciccocioppo and Marisa Roberto

Int. J. Mol. Sci. 2021, 22(6), 3095; https://doi.org/10.3390/ijms22063095 - 18 Mar 2021

Cited by 10 | Viewed by 3138

Abstract

Marchigian Sardinian alcohol-preferring (msP) rats serve as a unique model of heightened alcohol preference and anxiety disorders. Their innate enhanced stress and poor stress-coping strategies are driven by a genetic polymorphism of the corticotropin-releasing factor receptor 1 (CRF1) in brain areas involved in glucocorticoid signaling. The activation of glucocorticoid receptors (GRs) regulates the stress response, making GRs a candidate target to treat stress and anxiety. Here, we examined whether mifepristone, a GR antagonist known to reduce alcohol drinking in dependent rats, decreases innate symptoms of anxiety in msPs. Male and female msPs were compared to non-selected Wistar counterparts across three separate behavioral tests. We assessed anxiety-like behavior via the novelty-induced hypophagia (NIH) assay. Since sleep disturbances and hyperarousal are common features of stress-related disorders, we measured sleeping patterns using the comprehensive lab monitoring system (CLAMS) and stress sensitivity using acoustic startle measures. Rats received an acute administration of vehicle or mifepristone (60 mg/kg) 90 min prior to testing on NIH, acoustic startle response, and CLAMS. Our results revealed that both male and female msPs display greater anxiety-like behaviors as well as enhanced acoustic startle responses compared to Wistar counterparts. Male msPs also displayed reduced sleeping bout duration versus Wistars, and female msPs displayed greater acoustic startle responses versus male msPs. Importantly, the enhanced anxiety-like behavior and startle responses were not reduced by mifepristone. Together, these findings suggest that increased expression of stress-related behaviors in msPs are not solely mediated by acute activation of GRs. Full article

(This article belongs to the Special Issue Models of Drug Addiction: Translating Molecular Targets into Molecular Medicine)

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14 pages, 695 KiB

Open AccessReview

Extinction vs. Abstinence: A Review of the Molecular and Circuit Consequences of Different Post-Cocaine Experiences

by Marek Schwendt and Lori A. Knackstedt

Int. J. Mol. Sci. 2021, 22(11), 6113; https://doi.org/10.3390/ijms22116113 - 6 Jun 2021

Cited by 8 | Viewed by 3321

Abstract

The intravenous cocaine self-administration model is widely used to characterize the neurobiology of cocaine seeking. When studies are aimed at understanding relapse to cocaine-seeking, a post-cocaine abstinence period is imposed, followed by “relapse” tests to assess the ability of drug-related stimuli (“primes”) to evoke the resumption of the instrumental response previously made to obtain cocaine. Here, we review the literature on the impact of post-cocaine abstinence procedures on neurobiology, finding that the prelimbic and infralimbic regions of the prefrontal cortex are recruited by extinction training, and are not part of the relapse circuitry when extinction training does not occur. Pairing cocaine infusions with discrete cues recruits the involvement of the NA, which together with the dorsal striatum, is a key part of the relapse circuit regardless of abstinence procedures. Differences in molecular adaptations in the NA core include increased expression of GluN1 and glutamate receptor signaling partners after extinction training. AMPA receptors and glutamate transporters are similarly affected by abstinence and extinction. Glutamate receptor antagonists show efficacy at reducing relapse following extinction and abstinence, with a modest increase in efficacy of compounds that restore glutamate homeostasis after extinction training. Imaging studies in humans reveal cocaine-induced adaptations that are similar to those produced after extinction training. Thus, while instrumental extinction training does not have face validity, its use does not produce adaptations distinct from human cocaine users. Full article

(This article belongs to the Special Issue Models of Drug Addiction: Translating Molecular Targets into Molecular Medicine)

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20 pages, 402 KiB

Open AccessReview

Recent Perspectives on Sex Differences in Compulsion-Like and Binge Alcohol Drinking

by Anna K. Radke, Elizabeth A. Sneddon, Raizel M. Frasier and Frederic W. Hopf

Int. J. Mol. Sci. 2021, 22(7), 3788; https://doi.org/10.3390/ijms22073788 - 6 Apr 2021

Cited by 57 | Viewed by 5988

Abstract

Alcohol use disorder remains a substantial social, health, and economic problem and problem drinking levels in women have been increasing in recent years. Understanding whether and how the underlying mechanisms that drive drinking vary by sex is critical and could provide novel, more targeted therapeutic treatments. Here, we examine recent results from our laboratories and others which we believe provide useful insights into similarities and differences in alcohol drinking patterns across the sexes. Findings for binge intake and aversion-resistant, compulsion-like alcohol drinking are considered, since both are likely significant contributors to alcohol problems in humans. We also describe studies regarding mechanisms that may underlie sex differences in maladaptive alcohol drinking, with some focus on the importance of nucleus accumbens (NAcb) core and shell regions, several receptor types (dopamine, orexin, AMPA-type glutamate), and possible contributions of sex hormones. Finally, we discuss how stressors such as early life stress and anxiety-like states may interact with sex differences to contribute to alcohol drinking. Together, these findings underscore the importance and critical relevance of studying female and male mechanisms for alcohol and co-morbid conditions to gain a true and clinically useful understanding of addiction and neuropsychiatric mechanisms and treatment. Full article

(This article belongs to the Special Issue Models of Drug Addiction: Translating Molecular Targets into Molecular Medicine)

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