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Crombag HS, Duka T, Stephens DN. The Continuing Challenges of Studying Parallel Behaviours in Humans and Animal Models. Curr Top Behav Neurosci 2024. [PMID: 38976140 DOI: 10.1007/7854_2024_485] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/09/2024]
Abstract
The use of animal models continues to be essential for carrying out research into clinical phenomena, including addiction. However, the complexity of the clinical condition inevitably means that even the best animal models are inadequate, and this may go some way to account for the apparent failures of discoveries from animal models, including the identification of potential novel therapies, to translate to the clinic. We argue here that it is overambitious and misguided in the first place to attempt to model complex, multifacetted human disorders such as addiction in animals, and especially in rodents, and that all too frequently "validity" of such models is limited to superficial similarities, referred to as "face validity", that reflect quite different underlying phenomena and biological processes from the clinical situation. Instead, a more profitable approach is to identify (a) well-defined intermediate human behavioural phenotypes that reflect defined, limited aspects of, or contributors to, the human clinical disorder, and (b) to develop animal models that are homologous with those discrete human behavioural phenotypes in terms of psychological processes, and underlying neurobiological mechanisms. Examples of past and continuing weaknesses and suggestions for more limited approaches that may allow better homology between the test animal and human condition are made.
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Affiliation(s)
- Hans S Crombag
- School of Psychology and Sussex Neuroscience, The University of Sussex, Brighton, UK.
| | - Theodora Duka
- School of Psychology and Sussex Neuroscience, The University of Sussex, Brighton, UK
| | - David N Stephens
- School of Psychology and Sussex Neuroscience, The University of Sussex, Brighton, UK
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2
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Lovinger DM, Roberto M. Synaptic Effects Induced by Alcohol. Curr Top Behav Neurosci 2023:10.1007/7854_2022_412. [PMID: 36765015 PMCID: PMC11104446 DOI: 10.1007/7854_2022_412] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
Abstract
Ethanol (EtOH) has effects on numerous cellular molecular targets, and alterations in synaptic function are prominent among these effects. Acute exposure to EtOH activates or inhibits the function of proteins involved in synaptic transmission, while chronic exposure often produces opposing and/or compensatory/homeostatic effects on the expression, localization, and function of these proteins. Interactions between different neurotransmitters (e.g., neuropeptide effects on release of small molecule transmitters) can also influence both acute and chronic EtOH actions. Studies in intact animals indicate that the proteins affected by EtOH also play roles in the neural actions of the drug, including acute intoxication, tolerance, dependence, and the seeking and drinking of EtOH. The present chapter is an update of our previous Lovinger and Roberto (Curr Top Behav Neurosci 13:31-86, 2013) chapter and reviews the literature describing these acute and chronic synaptic effects of EtOH with a focus on adult animals and their relevance for synaptic transmission, plasticity, and behavior.
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Affiliation(s)
- David M Lovinger
- Laboratory for Integrative Neuroscience, National Institute on Alcohol Abuse and Alcoholism (NIAAA), Rockville, MD, USA
| | - Marisa Roberto
- Molecular Medicine Department, Scripps Research Institute, La Jolla, CA, USA.
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van den Oord EJCG, Xie LY, Zhao M, Aberg KA, Clark SL. A single-nucleus transcriptomics study of alcohol use disorder in the nucleus accumbens. Addict Biol 2023; 28:e13250. [PMID: 36577731 DOI: 10.1111/adb.13250] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2022] [Revised: 08/29/2022] [Accepted: 10/13/2022] [Indexed: 11/14/2022]
Abstract
Gene expression studies offer promising opportunities to better understand the processes underlying alcohol use disorder (AUD). As cell types differ in their function, gene expression profiles will typically vary across cell types. When studying bulk tissue, failure to account for this cellular diversity has a detrimental impact on the ability to detect disease associations. We therefore assayed the transcriptomes of 32,531 individual nuclei extracted from the nucleus accumbens (NAc) of nine donors with AUD and nine controls (72% male). Our study identified 17 clearly delineated cell types. We detected 26 transcriptome-wide significant differentially expressed genes (DEGs) that mainly involved medium spiny neurons with both D1-type and D2-type dopamine receptors, microglia (MGL) and oligodendrocytes. A higher than expected number of DEGs replicated in an existing single nucleus gene expression study of alcohol dependence in the prefrontal cortex (enrichment ratio 1.91, p value 0.019) with two genes remaining significant after a Bonferroni correction. Our most compelling result involved CD53 in MGL that replicated in the same cell type in the prefrontal cortex and was previously implicated in studies of DNA methylation, bulk gene expression and genetic variants. Several DEGs were previously reported to be associated with AUD (e.g., PER1 and MGAT5). The DEGs for MSN.3 seemed involved in neurodegeneration, disruption of circadian rhythms, alterations in glucose metabolism and changes in synaptic plasticity. For MGL, the DEGs implicated neuroinflammation and immune-related processes and for OLI, disruptions in myelination. This identification of the specific cell-types from which the association signals originate will be key for designing proper follow-up experiments and, eventually, novel clinical interventions.
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Affiliation(s)
- Edwin J C G van den Oord
- Center for Biomarker Research and Precision Medicine, Virginia Commonwealth University, Richmond, Virginia, USA
| | - Lin Y Xie
- Center for Biomarker Research and Precision Medicine, Virginia Commonwealth University, Richmond, Virginia, USA
| | - Min Zhao
- Center for Biomarker Research and Precision Medicine, Virginia Commonwealth University, Richmond, Virginia, USA
| | - Karolina A Aberg
- Center for Biomarker Research and Precision Medicine, Virginia Commonwealth University, Richmond, Virginia, USA
| | - Shaunna L Clark
- Department of Psychiatry & Behavioral Sciences, Texas A&M University, College Station, Texas, USA
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Starski P, Maulucci D, Mead H, Hopf F. Adaptation of the 5-choice serial reaction time task to measure engagement and motivation for alcohol in mice. Front Behav Neurosci 2022; 16:968359. [PMID: 36187376 PMCID: PMC9522902 DOI: 10.3389/fnbeh.2022.968359] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2022] [Accepted: 08/30/2022] [Indexed: 11/13/2022] Open
Abstract
Alcohol use disorder (AUD) is related to excessive binge alcohol consumption, and there is considerable interest in associated factors that promote intake. AUD has many behavioral facets that enhance inflexibility toward alcohol consumption, including impulsivity, motivation, and attention. Thus, it is important to understand how these factors might promote responding for alcohol and can change after protracted alcohol intake. Previous studies have explored such behavioral factors using responding for sugar in the 5-Choice Serial Reaction Time Task (5-CSRTT), which allows careful separation of impulsivity, attention, and motivation. Importantly, our studies uniquely focus on using alcohol as the reward throughout training and testing sessions, which is critical for beginning to answer central questions relating to behavioral engagement for alcohol. Alcohol preference and consumption in male C57BL/6 mice were determined from the first 9 sessions of 2-h alcohol drinking which were interspersed among 5-CSRTT training. Interestingly, alcohol preference but not consumption level significantly predicted 5-CSRTT responding for alcohol. In contrast, responding for strawberry milk was not related to alcohol preference. Moreover, high-preference (HP) mice made more correct alcohol-directed responses than low-preference (LP) during the first half of each session and had more longer reward latencies in the second half, with no differences when performing for strawberry milk, suggesting that HP motivation for alcohol may reflect “front-loading.” Mice were then exposed to an Intermittent Access to alcohol paradigm and retested in 5-CSRTT. While both HP and LP mice increased 5-CSRTT responding for alcohol, but not strawberry milk, LP performance rose to HP levels, with a greater change in correct and premature responding in LP versus HP. Overall, this study provides three significant findings: (1) alcohol was a suitable reward in the 5-CSRTT, allowing dissection of impulsivity, attention, and motivation in relation to alcohol drinking, (2) alcohol preference was a more sensitive indicator of mouse 5-CSRTT performance than consumption, and (3) intermittent alcohol drinking promoted behavioral engagement with alcohol, especially for individuals with less initial engagement.
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Affiliation(s)
- Phillip Starski
- Department of Psychiatry, Indiana University School of Medicine, Indianapolis, IN, United States
| | - Danielle Maulucci
- Department of Psychiatry, Indiana University School of Medicine, Indianapolis, IN, United States
| | - Hunter Mead
- Department of Psychology, Indiana University-Purdue University Indianapolis (IUPUI), Indianapolis, IN, United States
| | - Frederic Hopf
- Department of Psychiatry, Indiana University School of Medicine, Indianapolis, IN, United States
- *Correspondence: Frederic Hopf,
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Bahi DA, Dreyer JL. Chronic knockdown of the tetraspanin gene CD81 in the mouse nucleus accumbens modulates anxiety and ethanol-related behaviors. Physiol Behav 2022; 254:113894. [PMID: 35764142 DOI: 10.1016/j.physbeh.2022.113894] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Revised: 06/22/2022] [Accepted: 06/23/2022] [Indexed: 10/17/2022]
Abstract
CD81, a member of the tetraspanin family, plays important roles in many physiological processes, such as cell motility, attachment, and entry. Yet, CD81 functions in the brain remain unclear. In this study, we investigated the effects of CD81 knockdown, using lentiviral vectors (LV), on anxiety- and ethanol-related behaviors. For this purpose, mice were stereotaxically injected with CD81 shRNA-expressing LV into the nucleus accumbens (Nacc) and were assessed for anxiety-like behavior using the elevated plus maze (EPM) and open field (OF) tests. Alcohol's sedative effects were studied using loss-of-righting-reflex (LORR) and voluntary ethanol intake was assessed using a two-bottle choice (TBC) procedure. Results showed that mice depleted of CD81 exhibited an anxiolytic-like response in the EPM and OF tests with no effect on locomotor activity. In addition, genetic reduction of CD81 in the Nacc increased mice' sensitivity to alcohol's sedative effects in the LORR test, although plasma alcohol concentrations were unaffected. Interestingly, CD81 loss-of-function-induced anxiolysis was accompanied by a significant decrease in ethanol, but not saccharin nor quinine, intake in the TBC procedure. Finally, and following CD81 mRNA quantification, Pearson's correlations showed a significant positive relationship between accumbal CD81 mRNA with anxiety and ethanol-related behaviors. Our data indicate that CD81 is implicated in the pathogenesis of anxiety and alcoholism. Indeed the targeted disruption of CD81, with the resultant decrease in CD81 mRNA in the Nacc, converted ethanol-"preferring" mice into ethanol "non-preferring" mice. Collectively, these findings demonstrate that future CD81-targeted pharmacotherapies may be beneficial for the treatment of anxiety and alcoholism.
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Affiliation(s)
- Dr Amine Bahi
- College of Medicine, Ajman University, Ajman, UAE; Center of Medical and Bio-Allied Health Sciences Research, Ajman University, Ajman, UAE; Department of Anatomy, College of Medicine & Health Sciences, United Arab Emirates University, Al Ain, UAE.
| | - Jean-Luc Dreyer
- Division of Biochemistry, Department of Medicine, University of Fribourg, CH-1700, Fribourg, Switzerland
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Rodriguez-Romaguera J, Namboodiri VMK, Basiri ML, Stamatakis AM, Stuber GD. Developments from Bulk Optogenetics to Single-Cell Strategies to Dissect the Neural Circuits that Underlie Aberrant Motivational States. Cold Spring Harb Perspect Med 2022; 12:a039792. [PMID: 32513671 PMCID: PMC7799172 DOI: 10.1101/cshperspect.a039792] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Motivational states are regulated by complex networks across brain regions that are composed of genetically and functionally distinct neuronal populations. Disruption within these neural circuits leads to aberrant motivational states and are thought to be the root cause of psychiatric disorders related to reward processing and addiction. Critical technological advances in the field have revolutionized the study of neural systems by allowing the use of optical strategies to precisely control and visualize neural activity within genetically identified neural populations in the brain. This review will provide a brief introduction into the history of how technological advances in single-cell strategies have been applied to elucidate the neural circuits that underlie aberrant motivational states that often lead to dysfunction in reward processing and addiction.
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Affiliation(s)
- Jose Rodriguez-Romaguera
- Department of Psychiatry, University of North Carolina, Chapel Hill, North Carolina 27514, USA
- Neuroscience Center, University of North Carolina, Chapel Hill, North Carolina 27514, USA
| | - Vijay M K Namboodiri
- Center for the Neurobiology of Addiction, Pain, and Emotion, Department of Anesthesiology and Pain Medicine & Department of Pharmacology, University of Washington, Seattle, Washington 98195-6410, USA
| | - Marcus L Basiri
- Neuroscience Curriculum, University of North Carolina, Chapel Hill, North Carolina 27514, USA
| | - Alice M Stamatakis
- Neuroscience Curriculum, University of North Carolina, Chapel Hill, North Carolina 27514, USA
| | - Garret D Stuber
- Center for the Neurobiology of Addiction, Pain, and Emotion, Department of Anesthesiology and Pain Medicine & Department of Pharmacology, University of Washington, Seattle, Washington 98195-6410, USA
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Xu X, Mee T, Jia X. New era of optogenetics: from the central to peripheral nervous system. Crit Rev Biochem Mol Biol 2020; 55:1-16. [PMID: 32070147 DOI: 10.1080/10409238.2020.1726279] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Optogenetics has recently gained recognition as a biological technique to control the activity of cells using light stimulation. Many studies have applied optogenetics to cell lines in the central nervous system because it has the potential to elucidate neural circuits, treat neurological diseases and promote nerve regeneration. There have been fewer studies on the application of optogenetics in the peripheral nervous system. This review introduces the basic principles and approaches of optogenetics and summarizes the physiology and mechanism of opsins and how the technology enables bidirectional control of unique cell lines with superior spatial and temporal accuracy. Further, this review explores and discusses the therapeutic potential for the development of optogenetics and its capacity to revolutionize treatment for refractory epilepsy, depression, pain, and other nervous system disorders, with a focus on neural regeneration, especially in the peripheral nervous system. Additionally, this review synthesizes the latest preclinical research on optogenetic stimulation, including studies on non-human primates, summarizes the challenges, and highlights future perspectives. The potential of optogenetic stimulation to optimize therapy for peripheral nerve injuries (PNIs) is also highlighted. Optogenetic technology has already generated exciting, preliminary evidence, supporting its role in applications to several neurological diseases, including PNIs.
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Affiliation(s)
- Xiang Xu
- Department of Neurosurgery, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Thomas Mee
- Department of Neurosurgery, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Xiaofeng Jia
- Department of Neurosurgery, University of Maryland School of Medicine, Baltimore, MD, USA.,Department of Orthopedics, University of Maryland School of Medicine, Baltimore, MD, USA.,Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD, USA.,Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, USA.,Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
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Nonhuman animal models of substance use disorders: Translational value and utility to basic science. Drug Alcohol Depend 2020; 206:107733. [PMID: 31790978 PMCID: PMC6980671 DOI: 10.1016/j.drugalcdep.2019.107733] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/11/2019] [Revised: 11/10/2019] [Accepted: 11/11/2019] [Indexed: 12/15/2022]
Abstract
BACKGROUND The National Institute on Drug Abuse (NIDA) recently released a Request for Information (RFI) soliciting comments on nonhuman animal models of substance use disorders (SUD). METHODS A literature review was performed to address the four topics outlined in the RFI and one topic inspired by the RFI: (1) animal models that best recapitulate SUD, (2) animal models that best balance the trade-offs between resources and ecological validity, (3) animal models whose translational value are frequently misrepresented or overrepresented by the scientific community, (4) aspects of SUD that are not currently being modeled in animals, and (5) animal models that are optimal for examining the basic mechanisms by which drugs produce their abuse-related effects. RESULTS Models that employ response-contingent drug administration, use complex schedules of reinforcement, measure behaviors that mimic the distinguishing features of SUD, and use animals that are phylogenetically similar to humans have the greatest translational value. Models that produce stable and reproducible baselines of behavior, lessen the number of uncontrolled variables, and minimize the influence of extraneous factors are best at examining basic mechanisms contributing to drug reward and reinforcement. CONCLUSIONS Nonhuman animal models of SUD have undergone significant refinements to increase their utility for basic science and translational value for SUD. The existing literature describes numerous examples of how these models may best be utilized to answer mechanistic questions of drug reward and identify potential therapeutic interventions for SUD. Progress in the field could be accelerated by further collaborations between researchers using animals versus humans.
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Ron D, Weiner J. Special issue on new technologies for alcohol research and treatment. Alcohol 2019; 74:1-2. [PMID: 30409742 DOI: 10.1016/j.alcohol.2018.06.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2018] [Accepted: 06/11/2018] [Indexed: 11/17/2022]
Affiliation(s)
- Dorit Ron
- Department of Neurology, University of California San Francisco, San Francisco, CA 94143 United States.
| | - Jeff Weiner
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston-Salem, North Carolina 27157 United States.
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