1
|
Nakamoto K, Tokuyama S. Stress-Induced Changes in the Endogenous Opioid System Cause Dysfunction of Pain and Emotion Regulation. Int J Mol Sci 2023; 24:11713. [PMID: 37511469 PMCID: PMC10380691 DOI: 10.3390/ijms241411713] [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] [Received: 06/07/2023] [Revised: 07/13/2023] [Accepted: 07/13/2023] [Indexed: 07/30/2023] Open
Abstract
Early life stress, such as child abuse and neglect, and psychosocial stress in adulthood are risk factors for psychiatric disorders, including depression and anxiety. Furthermore, exposure to these stresses affects the sensitivity to pain stimuli and is associated with the development of chronic pain. However, the mechanisms underlying the pathogenesis of stress-induced depression, anxiety, and pain control remain unclear. Endogenous opioid signaling is reportedly associated with analgesia, reward, addiction, and the regulation of stress responses and anxiety. Stress alters the expression of various opioid receptors in the central nervous system and sensitivity to opioid receptor agonists and antagonists. μ-opioid receptor-deficient mice exhibit attachment disorders and autism-like behavioral expression patterns, while those with δ-opioid receptor deficiency exhibit anxiety-like behavior. In contrast, deficiency and antagonists of the κ-opioid receptor suppress the stress response. These findings strongly suggest that the expression and dysfunction of the endogenous opioid signaling pathways are involved in the pathogenesis of stress-induced psychiatric disorders and chronic pain. In this review, we summarize the latest basic and clinical research studies on the effects of endogenous opioid signaling on early-life stress, psychosocial stress-induced psychiatric disorders, and chronic pain.
Collapse
Affiliation(s)
- Kazuo Nakamoto
- Department of Clinical Pharmacy, School of Pharmaceutical Sciences, Kobe Gakuin University, 1-1-3 Minatojima, Chuo-ku, Kobe 650-8586, Japan
| | - Shogo Tokuyama
- Department of Clinical Pharmacy, School of Pharmaceutical Sciences, Kobe Gakuin University, 1-1-3 Minatojima, Chuo-ku, Kobe 650-8586, Japan
| |
Collapse
|
2
|
Wang L, Wang X, Liu C, Xu W, Kuang W, Bu Q, Li H, Zhao Y, Jiang L, Chen Y, Qin F, Li S, Wei Q, Liu X, Liu B, Chen Y, Dai Y, Wang H, Tian J, Cao G, Zhao Y, Cen X. Morphine Re-arranges Chromatin Spatial Architecture of Primate Cortical Neurons. GENOMICS, PROTEOMICS & BIOINFORMATICS 2023; 21:551-572. [PMID: 37209997 PMCID: PMC10787020 DOI: 10.1016/j.gpb.2023.03.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2022] [Revised: 03/29/2023] [Accepted: 03/30/2023] [Indexed: 05/22/2023]
Abstract
The expression of linear DNA sequence is precisely regulated by the three-dimensional (3D) architecture of chromatin. Morphine-induced aberrant gene networks of neurons have been extensively investigated; however, how morphine impacts the 3D genomic architecture of neurons is still unknown. Here, we applied digestion-ligation-only high-throughput chromosome conformation capture (DLO Hi-C) technology to investigate the effects of morphine on the 3D chromatin architecture of primate cortical neurons. After receiving continuous morphine administration for 90 days on rhesus monkeys, we discovered that morphine re-arranged chromosome territories, with a total of 391 segmented compartments being switched. Morphine altered over half of the detected topologically associated domains (TADs), most of which exhibited a variety of shifts, followed by separating and fusing types. Analysis of the looping events at kilobase-scale resolution revealed that morphine increased not only the number but also the length of differential loops. Moreover, all identified differentially expressed genes from the RNA sequencing data were mapped to the specific TAD boundaries or differential loops, and were further validated for changed expression. Collectively, an altered 3D genomic architecture of cortical neurons may regulate the gene networks associated with morphine effects. Our finding provides critical hubs connecting chromosome spatial organization and gene networks associated with the morphine effects in humans.
Collapse
Affiliation(s)
- Liang Wang
- National Chengdu Center for Safety Evaluation of Drugs, State Key Laboratory of Biotherapy/Collaborative Innovation Center for Biotherapy, West China Hospital of Sichuan University, Chengdu 610041, China
| | - Xiaojie Wang
- National Chengdu Center for Safety Evaluation of Drugs, State Key Laboratory of Biotherapy/Collaborative Innovation Center for Biotherapy, West China Hospital of Sichuan University, Chengdu 610041, China
| | - Chunqi Liu
- National Chengdu Center for Safety Evaluation of Drugs, State Key Laboratory of Biotherapy/Collaborative Innovation Center for Biotherapy, West China Hospital of Sichuan University, Chengdu 610041, China
| | - Wei Xu
- National Chengdu Center for Safety Evaluation of Drugs, State Key Laboratory of Biotherapy/Collaborative Innovation Center for Biotherapy, West China Hospital of Sichuan University, Chengdu 610041, China; Shenzhen Key Laboratory of Drug Addiction, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China
| | - Weihong Kuang
- Department of Psychiatry, West China Hospital of Sichuan University, Chengdu 610041, China
| | - Qian Bu
- National Chengdu Center for Safety Evaluation of Drugs, State Key Laboratory of Biotherapy/Collaborative Innovation Center for Biotherapy, West China Hospital of Sichuan University, Chengdu 610041, China
| | - Hongchun Li
- National Chengdu Center for Safety Evaluation of Drugs, State Key Laboratory of Biotherapy/Collaborative Innovation Center for Biotherapy, West China Hospital of Sichuan University, Chengdu 610041, China
| | - Ying Zhao
- National Chengdu Center for Safety Evaluation of Drugs, State Key Laboratory of Biotherapy/Collaborative Innovation Center for Biotherapy, West China Hospital of Sichuan University, Chengdu 610041, China
| | - Linhong Jiang
- National Chengdu Center for Safety Evaluation of Drugs, State Key Laboratory of Biotherapy/Collaborative Innovation Center for Biotherapy, West China Hospital of Sichuan University, Chengdu 610041, China
| | - Yaxing Chen
- National Chengdu Center for Safety Evaluation of Drugs, State Key Laboratory of Biotherapy/Collaborative Innovation Center for Biotherapy, West China Hospital of Sichuan University, Chengdu 610041, China
| | - Feng Qin
- National Chengdu Center for Safety Evaluation of Drugs, State Key Laboratory of Biotherapy/Collaborative Innovation Center for Biotherapy, West China Hospital of Sichuan University, Chengdu 610041, China
| | - Shu Li
- National Chengdu Center for Safety Evaluation of Drugs, State Key Laboratory of Biotherapy/Collaborative Innovation Center for Biotherapy, West China Hospital of Sichuan University, Chengdu 610041, China
| | - Qinfan Wei
- National Chengdu Center for Safety Evaluation of Drugs, State Key Laboratory of Biotherapy/Collaborative Innovation Center for Biotherapy, West China Hospital of Sichuan University, Chengdu 610041, China
| | - Xiaocong Liu
- National Chengdu Center for Safety Evaluation of Drugs, State Key Laboratory of Biotherapy/Collaborative Innovation Center for Biotherapy, West China Hospital of Sichuan University, Chengdu 610041, China
| | - Bin Liu
- National Chengdu Center for Safety Evaluation of Drugs, State Key Laboratory of Biotherapy/Collaborative Innovation Center for Biotherapy, West China Hospital of Sichuan University, Chengdu 610041, China
| | - Yuanyuan Chen
- National Chengdu Center for Safety Evaluation of Drugs, State Key Laboratory of Biotherapy/Collaborative Innovation Center for Biotherapy, West China Hospital of Sichuan University, Chengdu 610041, China
| | - Yanping Dai
- National Chengdu Center for Safety Evaluation of Drugs, State Key Laboratory of Biotherapy/Collaborative Innovation Center for Biotherapy, West China Hospital of Sichuan University, Chengdu 610041, China
| | - Hongbo Wang
- School of Pharmacy, Key Laboratory of Molecular Pharmacology and Drug Evaluation (Yantai University), Ministry of Education, Collaborative Innovation Center of Advanced Drug Delivery System and Biotech Drugs in Universities of Shandong, Yantai University, Yantai 264005, China
| | - Jingwei Tian
- School of Pharmacy, Key Laboratory of Molecular Pharmacology and Drug Evaluation (Yantai University), Ministry of Education, Collaborative Innovation Center of Advanced Drug Delivery System and Biotech Drugs in Universities of Shandong, Yantai University, Yantai 264005, China
| | - Gang Cao
- State Key Laboratory of Agricultural Microbiology, Hubei Hongshan Laboratory, Huazhong Agricultural University, Wuhan 430070, China
| | - Yinglan Zhao
- National Chengdu Center for Safety Evaluation of Drugs, State Key Laboratory of Biotherapy/Collaborative Innovation Center for Biotherapy, West China Hospital of Sichuan University, Chengdu 610041, China
| | - Xiaobo Cen
- National Chengdu Center for Safety Evaluation of Drugs, State Key Laboratory of Biotherapy/Collaborative Innovation Center for Biotherapy, West China Hospital of Sichuan University, Chengdu 610041, China.
| |
Collapse
|
3
|
Martinez Damonte V, Pomrenze MB, Manning CE, Casper C, Wolfden AL, Malenka RC, Kauer JA. Somatodendritic Release of Cholecystokinin Potentiates GABAergic Synapses Onto Ventral Tegmental Area Dopamine Cells. Biol Psychiatry 2023; 93:197-208. [PMID: 35961792 PMCID: PMC9976994 DOI: 10.1016/j.biopsych.2022.06.011] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 06/01/2022] [Accepted: 06/10/2022] [Indexed: 11/02/2022]
Abstract
BACKGROUND Neuropeptides are contained in nearly every neuron in the central nervous system and can be released not only from nerve terminals but also from somatodendritic sites. Cholecystokinin (CCK), among the most abundant neuropeptides in the brain, is expressed in the majority of midbrain dopamine neurons. Despite this high expression, CCK function within the ventral tegmental area (VTA) is not well understood. METHODS We confirmed CCK expression in VTA dopamine neurons through immunohistochemistry and in situ hybridization and detected optogenetically induced CCK release using an enzyme-linked immunosorbent assay. To investigate whether CCK modulates VTA circuit activity, we used whole-cell patch clamp recordings in mouse brain slices. We infused CCK locally in vivo and tested food intake and locomotion in fasted mice. We also used in vivo fiber photometry to measure Ca2+ transients in dopamine neurons during feeding. RESULTS Here we report that VTA dopamine neurons release CCK from somatodendritic regions, where it triggers long-term potentiation of GABAergic (gamma-aminobutyric acidergic) synapses. The somatodendritic release occurs during trains of optogenetic stimuli or prolonged but modest depolarization and is dependent on synaptotagmin-7 and T-type Ca2+ channels. Depolarization-induced long-term potentiation is blocked by a CCK2 receptor antagonist and mimicked by exogenous CCK. Local infusion of CCK in vivo inhibits food consumption and decreases distance traveled in an open field test. Furthermore, intra-VTA-infused CCK reduced dopamine cell Ca2+ signals during food consumption after an overnight fast and was correlated with reduced food intake. CONCLUSIONS Our experiments introduce somatodendritic neuropeptide release as a previously unknown feedback regulator of VTA dopamine cell excitability and dopamine-related behaviors.
Collapse
|
4
|
Munoz B, Fritz BM, Yin F, Atwood BK. HCN1 channels mediate mu opioid receptor long-term depression at insular cortex inputs to the dorsal striatum. J Physiol 2022; 600:4917-4938. [PMID: 36181477 DOI: 10.1113/jp283513] [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: 06/28/2022] [Accepted: 09/26/2022] [Indexed: 12/24/2022] Open
Abstract
Mu opioid receptors (MORs) are expressed in the dorsal striatum, a brain region that mediates goal-directed (via the dorsomedial striatum) and habitual (via the dorsolateral striatum, DLS) behaviours. Our previous work indicates that glutamate transmission is depressed when MORs are activated in the dorsal striatum, inducing MOR-mediated long-term synaptic depression (MOR-LTD) or short-term depression (MOR-STD), depending on the input. In the DLS, MOR-LTD is produced by MORs on anterior insular cortex (AIC) inputs and MOR-STD occurs at thalamic inputs, suggesting input-specific MOR plasticity mechanisms. Here, we evaluated the mechanisms of induction of MOR-LTD and MOR-STD in the DLS using pharmacology and optogenetics combined with patch-clamp electrophysiology. We found that cAMP/PKA signalling and protein synthesis are necessary for MOR-LTD expression, similar to previous studies of cannabinoid-mediated LTD in DLS. MOR-STD does not utilize these same mechanisms. We also demonstrated that cannabinoid-LTD occurs at AIC inputs to DLS. However, while cannabinoid-LTD requires mTOR signalling in DLS, MOR-LTD does not. We characterized the role of presynaptic HCN1 channels in MOR-LTD induction as HCN1 channels expressed in AIC are necessary for MOR-LTD expression in the DLS. These results suggest a mechanism in which MOR activation requires HCN1 to induce MOR-LTD, suggesting a new target for pharmacological modulation of synaptic plasticity, providing new opportunities to develop novel drugs to treat alcohol and opioid use disorders. KEY POINTS: Mu opioid receptor-mediated long-term depression at anterior insular cortex inputs to dorsolateral striatum involves presynaptic cAMP/PKA signalling and protein translation, similar to known mechanisms of cannabinoid long-term depression. Dorsal striatal cannabinoid long-term depression also occurs at anterior insular cortex inputs to the dorsolateral striatum. Dorsal striatal cannabinoid long-term depression requires mTOR signalling, similar to hippocampal cannabinoid long-term depression, but dorsal striatal mu opioid long-term depression does not require mTOR signalling. Mu opioid long-term depression requires presynaptic HCN1 channels at anterior insular cortex inputs to dorsolateral striatum.
Collapse
Affiliation(s)
- Braulio Munoz
- Department of Pharmacology & Toxicology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Brandon M Fritz
- Department of Pharmacology & Toxicology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Fuqin Yin
- Department of Pharmacology & Toxicology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Brady K Atwood
- Department of Pharmacology & Toxicology, Indiana University School of Medicine, Indianapolis, Indiana, USA
- Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, Indiana, USA
| |
Collapse
|
5
|
Cheron J, Kerchove d'Exaerde AD. Drug addiction: from bench to bedside. Transl Psychiatry 2021; 11:424. [PMID: 34385417 PMCID: PMC8361217 DOI: 10.1038/s41398-021-01542-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/05/2021] [Revised: 07/14/2021] [Accepted: 07/23/2021] [Indexed: 02/06/2023] Open
Abstract
Drug addiction is responsible for millions of deaths per year around the world. Still, its management as a chronic disease is shadowed by misconceptions from the general public. Indeed, drug consumers are often labelled as "weak", "immoral" or "depraved". Consequently, drug addiction is often perceived as an individual problem and not societal. In technical terms, drug addiction is defined as a chronic, relapsing disease resulting from sustained effects of drugs on the brain. Through a better characterisation of the cerebral circuits involved, and the long-term modifications of the brain induced by addictive drugs administrations, first, we might be able to change the way the general public see the patient who is suffering from drug addiction, and second, we might be able to find new treatments to normalise the altered brain homeostasis. In this review, we synthetise the contribution of fundamental research to the understanding drug addiction and its contribution to potential novel therapeutics. Mostly based on drug-induced modifications of synaptic plasticity and epigenetic mechanisms (and their behavioural correlates) and after demonstration of their reversibility, we tried to highlight promising therapeutics. We also underline the specific temporal dynamics and psychosocial aspects of this complex psychiatric disease adding parameters to be considered in clinical trials and paving the way to test new therapeutic venues.
Collapse
Affiliation(s)
- Julian Cheron
- Laboratory of Neurophysiology, ULB Neuroscience Institute, Université Libre de Bruxelles (ULB), Brussels, B-1070, Belgium
| | - Alban de Kerchove d'Exaerde
- Laboratory of Neurophysiology, ULB Neuroscience Institute, Université Libre de Bruxelles (ULB), Brussels, B-1070, Belgium.
| |
Collapse
|
6
|
Tadjalli A, Seven YB, Sharma A, McCurdy CR, Bolser DC, Levitt ES, Mitchell GS. Acute morphine blocks spinal respiratory motor plasticity via long-latency mechanisms that require toll-like receptor 4 signalling. J Physiol 2021; 599:3771-3797. [PMID: 34142718 DOI: 10.1113/jp281362] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2021] [Accepted: 06/15/2021] [Indexed: 12/22/2022] Open
Abstract
KEY POINTS While respiratory complications following opioid use are mainly mediated via activation of mu opioid receptors, long-latency off-target signalling via innate immune toll-like receptor 4 (TLR4) may impair other essential elements of breathing control such as respiratory motor plasticity. In adult rats, pre-treatment with a single dose of morphine blocked long-term facilitation (LTF) of phrenic motor output via a long-latency TLR4-dependent mechanism. In the phrenic motor nucleus, morphine triggered TLR4-dependent activation of microglial p38 MAPK - a key enzyme that orchestrates inflammatory signalling and is known to undermine phrenic LTF. Morphine-induced LTF loss may destabilize breathing, potentially contributing to respiratory side effects. Therefore, we suggest minimizing TLR-4 signalling may improve breathing stability during opioid therapy. ABSTRACT Opioid-induced respiratory dysfunction is a significant public health burden. While respiratory effects are mediated via mu opioid receptors, long-latency off-target opioid signalling through innate immune toll-like receptor 4 (TLR4) may modulate essential elements of breathing control, particularly respiratory motor plasticity. Plasticity in respiratory motor circuits contributes to the preservation of breathing in the face of destabilizing influences. For example, respiratory long-term facilitation (LTF), a well-studied model of respiratory motor plasticity triggered by acute intermittent hypoxia, promotes breathing stability by increasing respiratory motor drive to breathing muscles. Some forms of respiratory LTF are exquisitely sensitive to inflammation and are abolished by even a mild inflammation triggered by TLR4 activation (e.g. via systemic lipopolysaccharides). Since opioids induce inflammation and TLR4 activation, we hypothesized that opioids would abolish LTF through a TLR4-dependent mechanism. In adult Sprague Dawley rats, pre-treatment with a single systemic injection of the prototypical opioid agonist morphine blocks LTF expression several hours later in the phrenic motor system - the motor pool driving diaphragm muscle contractions. Morphine blocked phrenic LTF via TLR4-dependent mechanisms because pre-treatment with (+)-naloxone - the opioid inactive stereoisomer and novel small molecule TLR4 inhibitor - prevented impairment of phrenic LTF in morphine-treated rats. Morphine triggered TLR4-dependent activation of microglial p38 MAPK within the phrenic motor system - a key enzyme that orchestrates inflammatory signalling and undermines phrenic LTF. Morphine-induced LTF loss may destabilize breathing, potentially contributing to respiratory side effects. We suggest minimizing TLR-4 signalling may improve breathing stability during opioid therapy by restoring endogenous mechanisms of plasticity within respiratory motor circuits.
Collapse
Affiliation(s)
- Arash Tadjalli
- Breathing Research and Therapeutics Center, University of Florida, Gainesville, FL, USA.,Department of Physical Therapy, University of Florida, Gainesville, FL, USA
| | - Yasin B Seven
- Breathing Research and Therapeutics Center, University of Florida, Gainesville, FL, USA.,Department of Physical Therapy, University of Florida, Gainesville, FL, USA
| | - Abhisheak Sharma
- Department of Pharmaceutics, University of Florida, Gainesville, FL, USA
| | | | - Donald C Bolser
- Breathing Research and Therapeutics Center, University of Florida, Gainesville, FL, USA.,Department of Physiological Sciences, University of Florida, Gainesville, FL, USA
| | - Erica S Levitt
- Breathing Research and Therapeutics Center, University of Florida, Gainesville, FL, USA.,Department of Pharmacology and Therapeutics, University of Florida, Gainesville, FL, USA
| | - Gordon S Mitchell
- Breathing Research and Therapeutics Center, University of Florida, Gainesville, FL, USA.,Department of Physical Therapy, University of Florida, Gainesville, FL, USA
| |
Collapse
|
7
|
Doyle MA, Mazei-Robison MS. Opioid-Induced Molecular and Cellular Plasticity of Ventral Tegmental Area Dopamine Neurons. Cold Spring Harb Perspect Med 2021; 11:cshperspect.a039362. [PMID: 31964652 PMCID: PMC7371531 DOI: 10.1101/cshperspect.a039362] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Opioid drugs are highly valued as potent analgesics; however, there are significant risks associated with long-term use because of their abuse liability. Opioids cause changes in ventral tegmental area (VTA) gene expression and cell activity that have been linked to addiction-related behaviors in rodent models. Here, we focus on VTA dopamine (DA) neurons and review the cellular, structural, and synaptic plasticity changes induced by acute and chronic opioid exposure. We also discuss many avenues for future research including determination of whether opioid neuroadaptations are specific for subpopulations of VTA DA neurons. A better understanding of the molecular adaptations within the cells and circuits that drive opioid abuse is crucial for the development of better treatments for substance use disorders and to create novel, safer pain-relieving therapeutics.
Collapse
|
8
|
Capogna M, Castillo PE, Maffei A. The ins and outs of inhibitory synaptic plasticity: Neuron types, molecular mechanisms and functional roles. Eur J Neurosci 2020; 54:6882-6901. [PMID: 32663353 DOI: 10.1111/ejn.14907] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Revised: 06/30/2020] [Accepted: 07/08/2020] [Indexed: 01/05/2023]
Abstract
GABAergic interneurons are highly diverse, and their synaptic outputs express various forms of plasticity. Compelling evidence indicates that activity-dependent changes of inhibitory synaptic transmission play a significant role in regulating neural circuits critically involved in learning and memory and circuit refinement. Here, we provide an updated overview of inhibitory synaptic plasticity with a focus on the hippocampus and neocortex. To illustrate the diversity of inhibitory interneurons, we discuss the case of two highly divergent interneuron types, parvalbumin-expressing basket cells and neurogliaform cells, which support unique roles on circuit dynamics. We also present recent progress on the molecular mechanisms underlying long-term, activity-dependent plasticity of fast inhibitory transmission. Lastly, we discuss the role of inhibitory synaptic plasticity in neuronal circuits' function. The emerging picture is that inhibitory synaptic transmission in the CNS is extremely diverse, undergoes various mechanistically distinct forms of plasticity and contributes to a much more refined computational role than initially thought. Both the remarkable diversity of inhibitory interneurons and the various forms of plasticity expressed by GABAergic synapses provide an amazingly rich inhibitory repertoire that is central to a variety of complex neural circuit functions, including memory.
Collapse
Affiliation(s)
- Marco Capogna
- Department of Biomedicine, Danish National Research Foundation Center of Excellence PROMEMO, Aarhus University, Aarhus, Denmark
| | - Pablo E Castillo
- Dominck P Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY, USA.,Department of Psychiatry and Behavioral Sciences, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Arianna Maffei
- Center for Neural Circuit Dynamics and Department of Neurobiology and Behavior, Stony Brook University, Stony Brook, NY, USA
| |
Collapse
|
9
|
Crummy EA, O'Neal TJ, Baskin BM, Ferguson SM. One Is Not Enough: Understanding and Modeling Polysubstance Use. Front Neurosci 2020; 14:569. [PMID: 32612502 PMCID: PMC7309369 DOI: 10.3389/fnins.2020.00569] [Citation(s) in RCA: 136] [Impact Index Per Article: 34.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Accepted: 05/08/2020] [Indexed: 12/19/2022] Open
Abstract
Substance use disorder (SUD) is a chronic, relapsing disease with a highly multifaceted pathology that includes (but is not limited to) sensitivity to drug-associated cues, negative affect, and motivation to maintain drug consumption. SUDs are highly prevalent, with 35 million people meeting criteria for SUD. While drug use and addiction are highly studied, most investigations of SUDs examine drug use in isolation, rather than in the more prevalent context of comorbid substance histories. Indeed, 11.3% of individuals diagnosed with a SUD have concurrent alcohol and illicit drug use disorders. Furthermore, having a SUD with one substance increases susceptibility to developing dependence on additional substances. For example, the increased risk of developing heroin dependence is twofold for alcohol misusers, threefold for cannabis users, 15-fold for cocaine users, and 40-fold for prescription misusers. Given the prevalence and risk associated with polysubstance use and current public health crises, examining these disorders through the lens of co-use is essential for translatability and improved treatment efficacy. The escalating economic and social costs and continued rise in drug use has spurred interest in developing preclinical models that effectively model this phenomenon. Here, we review the current state of the field in understanding the behavioral and neural circuitry in the context of co-use with common pairings of alcohol, nicotine, cannabis, and other addictive substances. Moreover, we outline key considerations when developing polysubstance models, including challenges to developing preclinical models to provide insights and improve treatment outcomes.
Collapse
Affiliation(s)
- Elizabeth A Crummy
- Graduate Program in Neuroscience, University of Washington, Seattle, WA, United States.,Center for Neurobiology of Addiction, Pain, and Emotion, University of Washington, Seattle, WA, United States.,Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle, WA, United States.,Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, United States
| | - Timothy J O'Neal
- Graduate Program in Neuroscience, University of Washington, Seattle, WA, United States.,Center for Neurobiology of Addiction, Pain, and Emotion, University of Washington, Seattle, WA, United States.,Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle, WA, United States.,Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, United States
| | - Britahny M Baskin
- Graduate Program in Neuroscience, University of Washington, Seattle, WA, United States.,Center for Neurobiology of Addiction, Pain, and Emotion, University of Washington, Seattle, WA, United States.,Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle, WA, United States.,Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, United States
| | - Susan M Ferguson
- Center for Neurobiology of Addiction, Pain, and Emotion, University of Washington, Seattle, WA, United States.,Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle, WA, United States.,Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, United States.,Alcohol and Drug Abuse Institute, University of Washington, Seattle, WA, United States
| |
Collapse
|
10
|
Hood LE, Leyrer-Jackson JM, Olive MF. Pharmacotherapeutic management of co-morbid alcohol and opioid use. Expert Opin Pharmacother 2020; 21:823-839. [PMID: 32103695 PMCID: PMC7239727 DOI: 10.1080/14656566.2020.1732349] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Accepted: 02/17/2020] [Indexed: 12/12/2022]
Abstract
Opioid use disorder (OUD) and alcohol use disorder (AUD) are two highly prevalent substance-related disorders worldwide. Co-use of the substances is also quite prevalent, yet there are no pharmacological treatment approaches specifically designed to treat co-morbid OUD and AUD. Here, the authors critically summarize OUD, AUD and opioid/alcohol co-use and their current pharmacotherapies for treatment. They also review the mechanisms of action of opioids and alcohol within the brain reward circuitry and discuss potential combined mechanisms of action and resulting neuroadaptations. Pharmacotherapies that aim to treat AUD or OUD that may be beneficial in the treatment of co-use are also highlighted. Preclinical models assessing alcohol and opioid co-use remain sparse. Lasting neuroadaptations in brain reward circuits caused by co-use of alcohol and opioids remains largely understudied. In order to fully understand the neurobiological underpinnings of alcohol and opioid co-use and develop efficacious pharmacotherapies, the preclinical field must expand its current experimental paradigms of 'single drug' use to encompass polysubstance use. Such studies will provide insights on the neural alterations induced by opioid and alcohol co-use, and may help develop novel pharmacotherapies for individuals with co-occurring alcohol and opioid use disorders.
Collapse
Affiliation(s)
- Lauren E. Hood
- Department of Psychology, Arizona State University, Tempe, Arizona, USA
| | | | - M. Foster Olive
- Department of Psychology, Arizona State University, Tempe, Arizona, USA
| |
Collapse
|
11
|
St Laurent R, Martinez Damonte V, Tsuda AC, Kauer JA. Periaqueductal Gray and Rostromedial Tegmental Inhibitory Afferents to VTA Have Distinct Synaptic Plasticity and Opiate Sensitivity. Neuron 2020; 106:624-636.e4. [PMID: 32191871 DOI: 10.1016/j.neuron.2020.02.029] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2018] [Revised: 10/01/2019] [Accepted: 02/25/2020] [Indexed: 12/16/2022]
Abstract
The ventral tegmental area (VTA) is a major target of addictive drugs and receives multiple GABAergic projections originating outside the VTA. We describe differences in synaptic plasticity and behavior when optogenetically driving two opiate-sensitive GABAergic inputs to the VTA, the rostromedial tegmental nucleus (RMTg), and the periaqueductal gray (PAG). Activation of GABAergic RMTg terminals in the VTA in vivo is aversive, and low-frequency stimulation induces long-term depression in vitro. Low-frequency stimulation of PAG afferents in vitro unexpectedly causes long-term potentiation. Opioid receptor activation profoundly depresses PAG and RMTg inhibitory synapses but prevents synaptic plasticity only at PAG synapses. Activation of the GABAergic PAG terminals in the VTA promotes immobility, and optogenetically-driven immobility is blocked by morphine. Our data reveal the PAG as a source of highly opioid-sensitive GABAergic afferents and support the idea that different GABAergic pathways to the VTA control distinct behaviors.
Collapse
Affiliation(s)
- Robyn St Laurent
- Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Stanford, CA 94035, USA
| | - Valentina Martinez Damonte
- Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Stanford, CA 94035, USA
| | - Ayumi C Tsuda
- Department of Molecular Pharmacology, Physiology, and Biotechnology, Brown University, Providence, RI 02912, USA
| | - Julie A Kauer
- Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Stanford, CA 94035, USA.
| |
Collapse
|
12
|
Synaptic Plasticity at Inhibitory Synapses in the Ventral Tegmental Area Depends upon Stimulation Site. eNeuro 2019; 6:ENEURO.0137-19.2019. [PMID: 31619451 PMCID: PMC6860988 DOI: 10.1523/eneuro.0137-19.2019] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2019] [Revised: 09/16/2019] [Accepted: 10/04/2019] [Indexed: 01/04/2023] Open
Abstract
Drug exposure induces cell and synaptic plasticity within the brain reward pathway that could be a catalyst for progression to addiction. Several cellular adaptations have been described in the ventral tegmental area (VTA), a central component of the reward pathway that is the major source of dopamine release. For example, administration of morphine induces long-term potentiation (LTP) of excitatory synapses on VTA dopamine cells and blocks LTP at inhibitory synapses. Drug-induced synaptic changes have a common endpoint of increasing dopamine cell firing and dopamine release. However, gaining a complete picture of synaptic plasticity in the VTA is hindered by its complex circuitry of efferents and afferents. Most studies of synaptic plasticity in the VTA activated a mixed population of afferents, potentially yielding an incomplete and perhaps misleading view of how drugs of abuse modify VTA synapses. Here, we use midbrain slices from mice and find that electrical stimulation in two different regions induces different forms of plasticity, including two new forms of LTP at inhibitory synapses. High-frequency stimulation (HFS) induces LTP independently of NMDA receptor (NMDAR) activation, and surprisingly, some inhibitory inputs to the VTA also undergo NMDAR-independent LTP after a low-frequency stimulation (LFS) pairing protocol.
Collapse
|
13
|
Langlois LD, Dacher M, Nugent FS. Dopamine Receptor Activation Is Required for GABAergic Spike Timing-Dependent Plasticity in Response to Complex Spike Pairing in the Ventral Tegmental Area. Front Synaptic Neurosci 2018; 10:32. [PMID: 30297996 PMCID: PMC6160785 DOI: 10.3389/fnsyn.2018.00032] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Accepted: 08/30/2018] [Indexed: 01/06/2023] Open
Abstract
One of the most influential synaptic learning rules explored in the past decades is activity dependent spike-timing-dependent plasticity (STDP). In STDP, synapses are either potentiated or depressed based on the order of pre- and postsynaptic neuronal activation within narrow, milliseconds-long, time intervals. STDP is subject to neuromodulation by dopamine (DA), a potent neurotransmitter that significantly impacts synaptic plasticity and reward-related behavioral learning. Previously, we demonstrated that GABAergic synapses onto ventral tegmental area (VTA) DA neurons are able to express STDP (Kodangattil et al., 2013), however it is still unclear whether DA modulates inhibitory STDP in the VTA. Here, we used whole-cell recordings in rat midbrain slices to investigate whether DA D1-like and/or D2-like receptor (D1R/D2R) activation is required for induction of STDP in response to a complex pattern of spiking. We found that VTA but not Substantia nigra pars compact (SNc) DA neurons exhibit long-term depression (LTDGABA) in response to a combination of positive (pre-post) and negative (post-pre) timing of spiking (a complex STDP protocol). Blockade of either D1Rs or D2Rs prevented the induction of LTDGABA while activation of D1Rs did not affect the plasticity in response to this complex STDP protocol in VTA DA neurons.Our data suggest that this DA-dependent GABAergic STDP is selectively expressed at GABAergic synapses onto VTA DA neurons which could be targeted by drugs of abuse to mediate drug-induced modulation of DA signaling within the VTA, as well as in VTA-projection areas, thereby affecting reward-related learning and drug-associated memories.
Collapse
Affiliation(s)
- Ludovic D Langlois
- Department of Pharmacology, F. Edward Hebert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, MD, United States
| | - Matthieu Dacher
- Department of Pharmacology, F. Edward Hebert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, MD, United States
| | - Fereshteh S Nugent
- Department of Pharmacology, F. Edward Hebert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, MD, United States
| |
Collapse
|
14
|
Muñoz B, Fritz BM, Yin F, Atwood BK. Alcohol exposure disrupts mu opioid receptor-mediated long-term depression at insular cortex inputs to dorsolateral striatum. Nat Commun 2018; 9:1318. [PMID: 29615610 PMCID: PMC5882774 DOI: 10.1038/s41467-018-03683-1] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2017] [Accepted: 03/02/2018] [Indexed: 01/07/2023] Open
Abstract
Drugs of abuse, including alcohol, ablate the expression of specific forms of long-term synaptic depression (LTD) at glutamatergic synapses in dorsal striatum (DS), a brain region involved in goal-directed and habitual behaviors. This loss of LTD is associated with altered DS-dependent behavior. Given the role of the µ-opioid receptor (MOR) in behavioral responding for alcohol, we explored the impact of alcohol on various forms of MOR-mediated synaptic depression that we find are differentially expressed at specific DS synapses. Corticostriatal MOR-mediated LTD (mOP-LTD) in the dorsolateral striatum occurs exclusively at inputs from anterior insular cortex and is selectively disrupted by in vivo alcohol exposure. Alcohol has no effect on corticostriatal mOP-LTD in dorsomedial striatum, thalamostriatal MOR-mediated short-term depression, or mOP-LTD of cholinergic interneuron-driven glutamate release. Disrupted mOP-LTD at anterior insular cortex-dorsolateral striatum synapses may therefore be a key mechanism of alcohol-induced neuroadaptations involved in the development of alcohol use disorders.
Collapse
Affiliation(s)
- Braulio Muñoz
- Department of Psychiatry, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
| | - Brandon M Fritz
- Department of Psychiatry, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
| | - Fuqin Yin
- Department of Psychiatry, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
| | - Brady K Atwood
- Department of Psychiatry, Indiana University School of Medicine, Indianapolis, IN, 46202, USA. .,Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, IN, 46202, USA. .,Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN, 46202, USA.
| |
Collapse
|
15
|
Kim J, Im HI, Moon C. Intravenous morphine self-administration alters accumbal microRNA profiles in the mouse brain. Neural Regen Res 2018; 13:77-85. [PMID: 29451210 PMCID: PMC5840996 DOI: 10.4103/1673-5374.224374] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
A significant amount of evidence indicates that microRNAs (miRNAs) play an important role in drug addiction. The nucleus accumbens (NAc) is a critical part of the brain's reward circuit and is involved in a variety of psychiatric disorders, including depression, anxiety, and drug addiction. However, few studies have examined the expression of miRNAs and their functional roles in the NAc under conditions of morphine addiction. In this study, mice were intravenously infused with morphine (0.01, 0.03, 0.3, 1 and 3 mg/kg/infusion) and showed inverted U-shaped response. After morphine self-administration, NAc was used to analyze the functional networks of altered miRNAs and their putative target mRNAs in the NAc following intravenous self-administration of morphine. We utilized several bioinformatics tools, including Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway mapping and CyTargetLinker. We found that 62 miRNAs were altered and exhibited differential expression patterns. The putative targets were related to diverse regulatory functions, such as neurogenesis, neurodegeneration, and synaptic plasticity, as well as the pharmacological effects of morphine (receptor internalization/endocytosis). The present findings provide novel insights into the regulatory mechanisms of accumbal molecules under conditions of morphine addiction and identify several novel biomarkers associated with morphine addiction.
Collapse
Affiliation(s)
- Juhwan Kim
- Department of Veterinary Anatomy and Animal Behavior, College of Veterinary Medicine and BK21 Plus Project Team, Chonnam National University, Gwangju; Center for Neuroscience, Korea Institute of Science and Technology (KIST), Seoul, South Korea
| | - Heh-In Im
- Center for Neuroscience, Korea Institute of Science and Technology (KIST); Convergence Research Center for Diagnosis, Treatment and Care System of Dementia; Division of Biomedical Science & Technology, KIST School, Korea University of Science and Technology, Seoul, South Korea
| | - Changjong Moon
- Department of Veterinary Anatomy and Animal Behavior, College of Veterinary Medicine and BK21 Plus Project Team, Chonnam National University, Gwangju, South Korea
| |
Collapse
|
16
|
Abstract
Opioids are among the most effective pain relievers; however, their abuse has been on the rise worldwide evident from an alarming increase in accidental opioid overdoses. This demands for an urgent increase in scientific endeavors for better understanding of main cellular mechanisms and circuits involved in opiate addiction. Preclinical studies strongly suggest that memories associated with positive and negative opioid experiences are critical in promoting compulsive opiate-seeking and opiate-taking behaviors, and relapse. Particular focus on synaptic plasticity as the cellular correlate of learning and memory has rapidly evolved in drug addiction field over the past two decades. Several critical addiction-related brain areas are identified, one of which is the ventral tegmental area (VTA), an area intensively studied as the initial locus for drug reward. Here, we provide an update to our previous review on "Opiates and Plasticity" highlighting the most recent discoveries of synaptic plasticity associated with opiates in the VTA. Electrophysiological studies of plasticity of addiction to date have been invaluable in addressing learning processes and mechanisms that underlie motivated and addictive behaviors, and now with the availability of powerful technologies of transgenic approaches and optogenetics, circuit-based studies hold high promise in fostering synaptic studies of opiate addiction.
Collapse
Affiliation(s)
- Ludovic D. Langlois
- Department of Pharmacology, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20814, United States
| | - Fereshteh S. Nugent
- Department of Pharmacology, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20814, United States
| |
Collapse
|
17
|
Naloxone blocks the aversive effects of electrical stimulation of the parabrachial complex in a place discrimination task. Neurobiol Learn Mem 2016; 136:21-27. [DOI: 10.1016/j.nlm.2016.09.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2016] [Revised: 09/12/2016] [Accepted: 09/18/2016] [Indexed: 01/02/2023]
|
18
|
Xin W, Edwards N, Bonci A. VTA dopamine neuron plasticity - the unusual suspects. Eur J Neurosci 2016; 44:2975-2983. [PMID: 27711998 DOI: 10.1111/ejn.13425] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2016] [Revised: 09/26/2016] [Accepted: 10/03/2016] [Indexed: 12/25/2022]
Abstract
Dopamine neurons in the ventral tegmental area (VTA) are involved in a variety of physiological and pathological conditions, ranging from motivated behaviours to substance use disorders. While many studies have shown that these neurons can express plasticity at excitatory and inhibitory synapses, little is known about how inhibitory inputs and glial activity shape the output of DA neurons and therefore, merit greater discussion. In this review, we will attempt to fill in a bit more of the puzzle, with a focus on inhibitory transmission and astrocyte function. We summarize the findings within the VTA as well as observations made in other brain regions that have important implications for plasticity in general and should be considered in the context of DA neuron plasticity.
Collapse
Affiliation(s)
- Wendy Xin
- Synaptic Plasticity Section, National Institute on Drug Abuse Intramural Research Program, Baltimore, MD, 21224, USA.,Solomon H. Snyder Department of Neuroscience, Johns Hopkins University, Baltimore, MD, USA
| | - Nicholas Edwards
- Synaptic Plasticity Section, National Institute on Drug Abuse Intramural Research Program, Baltimore, MD, 21224, USA
| | - Antonello Bonci
- Synaptic Plasticity Section, National Institute on Drug Abuse Intramural Research Program, Baltimore, MD, 21224, USA.,Solomon H. Snyder Department of Neuroscience, Johns Hopkins University, Baltimore, MD, USA
| |
Collapse
|
19
|
Diversity of Dopaminergic Neural Circuits in Response to Drug Exposure. Neuropsychopharmacology 2016; 41:2424-46. [PMID: 26934955 PMCID: PMC4987841 DOI: 10.1038/npp.2016.32] [Citation(s) in RCA: 107] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/22/2015] [Revised: 02/05/2016] [Accepted: 02/22/2016] [Indexed: 01/09/2023]
Abstract
Addictive substances are known to increase dopaminergic signaling in the mesocorticolimbic system. The origin of this dopamine (DA) signaling originates in the ventral tegmental area (VTA), which sends afferents to various targets, including the nucleus accumbens, the medial prefrontal cortex, and the basolateral amygdala. VTA DA neurons mediate stimuli saliency and goal-directed behaviors. These neurons undergo robust drug-induced intrinsic and extrinsic synaptic mechanisms following acute and chronic drug exposure, which are part of brain-wide adaptations that ultimately lead to the transition into a drug-dependent state. Interestingly, recent investigations of the differential subpopulations of VTA DA neurons have revealed projection-specific functional roles in mediating reward, aversion, and stress. It is now critical to view drug-induced neuroadaptations from a circuit-level perspective to gain insight into how differential dopaminergic adaptations and signaling to targets of the mesocorticolimbic system mediates drug reward. This review hopes to describe the projection-specific intrinsic characteristics of these subpopulations, the differential afferent inputs onto these VTA DA neuron subpopulations, and consolidate findings of drug-induced plasticity of VTA DA neurons and highlight the importance of future projection-based studies of this system.
Collapse
|
20
|
Kim J, Ham S, Hong H, Moon C, Im HI. Brain Reward Circuits in Morphine Addiction. Mol Cells 2016; 39:645-53. [PMID: 27506251 PMCID: PMC5050528 DOI: 10.14348/molcells.2016.0137] [Citation(s) in RCA: 72] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Revised: 07/18/2016] [Accepted: 07/20/2016] [Indexed: 12/30/2022] Open
Abstract
Morphine is the most potent analgesic for chronic pain, but its clinical use has been limited by the opiate's innate tendency to produce tolerance, severe withdrawal symptoms and rewarding properties with a high risk of relapse. To understand the addictive properties of morphine, past studies have focused on relevant molecular and cellular changes in the brain, highlighting the functional roles of reward-related brain regions. Given the accumulated findings, a recent, emerging trend in morphine research is that of examining the dynamics of neuronal interactions in brain reward circuits under the influence of morphine action. In this review, we highlight recent findings on the roles of several reward circuits involved in morphine addiction based on pharmacological, molecular and physiological evidences.
Collapse
Affiliation(s)
- Juhwan Kim
- Center for Neuroscience, Brain Science Institute, Seoul 02792,
Korea
- Convergence Research Center for Diagnosis, Treatment and Care System of Dementia, Korea Institute of Science and Technology (KIST), Seoul 02792,
Korea
- Department of Veterinary Anatomy, College of Veterinary Medicine and Animal Medical Institute, Chonnam National University, Gwangju 61186,
Korea
| | - Suji Ham
- Center for Neuroscience, Brain Science Institute, Seoul 02792,
Korea
- Convergence Research Center for Diagnosis, Treatment and Care System of Dementia, Korea Institute of Science and Technology (KIST), Seoul 02792,
Korea
- Department of Neuroscience, Korea University of Science and Technology (UST), Daejeon 34113,
Korea
| | - Heeok Hong
- Department of Medical Science, Konkuk University School of Medicine, Seoul 05029,
Korea
| | - Changjong Moon
- Department of Veterinary Anatomy, College of Veterinary Medicine and Animal Medical Institute, Chonnam National University, Gwangju 61186,
Korea
| | - Heh-In Im
- Center for Neuroscience, Brain Science Institute, Seoul 02792,
Korea
- Convergence Research Center for Diagnosis, Treatment and Care System of Dementia, Korea Institute of Science and Technology (KIST), Seoul 02792,
Korea
- Department of Neuroscience, Korea University of Science and Technology (UST), Daejeon 34113,
Korea
| |
Collapse
|
21
|
Authement ME, Langlois LD, Kassis H, Gouty S, Dacher M, Shepard RD, Cox BM, Nugent FS. Morphine-induced synaptic plasticity in the VTA is reversed by HDAC inhibition. J Neurophysiol 2016; 116:1093-103. [PMID: 27306674 DOI: 10.1152/jn.00238.2016] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2016] [Accepted: 06/13/2016] [Indexed: 12/14/2022] Open
Abstract
Dopamine (DA) dysfunction originating from the ventral tegmental area (VTA) occurs as a result of synaptic abnormalities following consumption of drugs of abuse and underlies behavioral plasticity associated with drug abuse. Drugs of abuse can cause changes in gene expression through epigenetic mechanisms in the brain that underlie some of the lasting neuroplasticity and behavior associated with addiction. Here we investigated the function of histone acetylation and histone deacetylase (HDAC)2 in the VTA in recovery of morphine-induced synaptic modifications following a single in vivo exposure to morphine. Using a combination of immunohistochemistry, Western blot, and whole cell patch-clamp recording in rat midbrain slices, we show that morphine increased HDAC2 activity in VTA DA neurons and reduced histone H3 acetylation at lysine 9 (Ac-H3K9) in the VTA 24 h after the injection. Morphine-induced synaptic changes at glutamatergic synapses involved endocannabinoid signaling to reduce GABAergic synaptic strength onto VTA DA neurons. Both plasticities were recovered by in vitro incubation of midbrain slices with a class I-specific HDAC inhibitor (HDACi), CI-994, through an increase in acetylation of histone H3K9. Interestingly, HDACi incubation also increased levels of Ac-H3K9 and triggered GABAergic and glutamatergic plasticities in DA neurons of saline-treated rats. Our results suggest that acute morphine-induced changes in VTA DA activity and synaptic transmission engage HDAC2 activity locally in the VTA to maintain synaptic modifications through histone hypoacetylation.
Collapse
Affiliation(s)
- Michael E Authement
- Department of Pharmacology, Uniformed Services University of the Health Sciences, Bethesda, Maryland
| | - Ludovic D Langlois
- Department of Pharmacology, Uniformed Services University of the Health Sciences, Bethesda, Maryland
| | - Haifa Kassis
- Department of Pharmacology, Uniformed Services University of the Health Sciences, Bethesda, Maryland
| | - Shawn Gouty
- Department of Pharmacology, Uniformed Services University of the Health Sciences, Bethesda, Maryland
| | - Matthieu Dacher
- Department of Pharmacology, Uniformed Services University of the Health Sciences, Bethesda, Maryland
| | - Ryan D Shepard
- Department of Pharmacology, Uniformed Services University of the Health Sciences, Bethesda, Maryland
| | - Brian M Cox
- Department of Pharmacology, Uniformed Services University of the Health Sciences, Bethesda, Maryland
| | - Fereshteh S Nugent
- Department of Pharmacology, Uniformed Services University of the Health Sciences, Bethesda, Maryland
| |
Collapse
|
22
|
Merrill CB, Friend LN, Newton ST, Hopkins ZH, Edwards JG. Ventral tegmental area dopamine and GABA neurons: Physiological properties and expression of mRNA for endocannabinoid biosynthetic elements. Sci Rep 2015; 5:16176. [PMID: 26553597 PMCID: PMC4639757 DOI: 10.1038/srep16176] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2015] [Accepted: 10/08/2015] [Indexed: 11/12/2022] Open
Abstract
The ventral tegmental area (VTA) is involved in adaptive reward and motivation processing and is composed of dopamine (DA) and GABA neurons. Defining the elements regulating activity and synaptic plasticity of these cells is critical to understanding mechanisms of reward and addiction. While endocannabinoids (eCBs) that potentially contribute to addiction are known to be involved in synaptic plasticity mechanisms in the VTA, where they are produced is poorly understood. In this study, DA and GABAergic cells were identified using electrophysiology, cellular markers, and a transgenic mouse model that specifically labels GABA cells. Using single-cell RT-qPCR and immunohistochemistry, we investigated mRNA and proteins involved in eCB signaling such as diacylglycerol lipase α, N-acyl-phosphatidylethanolamine-specific phospholipase D, and 12-lipoxygenase, as well as type I metabotropic glutamate receptors (mGluRs). Our results demonstrate the first molecular evidence of colocalization of eCB biosynthetic enzyme and type I mGluR mRNA in VTA neurons. Further, these data reveal higher expression of mGluR1 in DA neurons, suggesting potential differences in eCB synthesis between DA and GABA neurons. These data collectively suggest that VTA GABAergic and DAergic cells have the potential to produce various eCBs implicated in altering neuronal activity or plasticity in adaptive motivational reward or addiction.
Collapse
Affiliation(s)
- Collin B Merrill
- Brigham Young University Department of Physiology and Developmental Biology Provo, UT 84602 USA
| | - Lindsey N Friend
- Brigham Young University Neuroscience Center Provo, UT 84602 USA
| | - Scott T Newton
- Brigham Young University Neuroscience Center Provo, UT 84602 USA
| | | | - Jeffrey G Edwards
- Brigham Young University Department of Physiology and Developmental Biology Provo, UT 84602 USA.,Brigham Young University Neuroscience Center Provo, UT 84602 USA
| |
Collapse
|
23
|
Tian H, Xu Y, Liu F, Wang G, Hu S. Effect of acute fentanyl treatment on synaptic plasticity in the hippocampal CA1 region in rats. Front Pharmacol 2015; 6:251. [PMID: 26578961 PMCID: PMC4626754 DOI: 10.3389/fphar.2015.00251] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2015] [Accepted: 10/14/2015] [Indexed: 12/22/2022] Open
Abstract
Postoperative cognitive dysfunction (POCD), mainly characterized by short-term decline of learning and memory, occurs after operations under anesthesia. However, the underlying mechanisms are poorly understood. The μ-opioid receptors (MOR) are highly expressed in interneurons of hippocampus, and is believed to be critical for the dysfunction of synaptic plasticity between hippocampal neurons. Therefore, we investigated the effect of fentanyl, a strong agonist of MOR and often used for anesthesia and analgesia in clinical settings, on hippocampal synaptic plasticity in the Schaffer-collateral CA1 pathway during acute exposure and washout in vitro. Our results revealed that acute fentanyl exposure (0.01, 0.1, 1 μM) dose-dependently increased the field excitatory postsynaptic potentials (fEPSPs), which was prevented by pre-administration of picrotoxin (50 μM) or MOR antagonist D-Phe-Cys-Tyr-D-Trp-Orn-Thr-Phe-Thr-NH2 (CTOP, 10 μM). While fentanyl exposure-increased fEPSPs amplitude was prevented by picrotoxin [an inhibitor of γ-aminobutyric acid receptor (GABAR)] treatment or fentanyl washout, pretreatment of picrotoxin failed to prevent the fentanyl-impaired long-term potentiation (LTP) of synaptic strength as well as the fentanyl-enhanced long-term depression (LTD). These results demonstrated that fentanyl acute exposure and washout increases hippocampal excitability in the Schaffer-collateral CA1 pathway, depending on disinhibiting interneurons after MOR activation. In addition, fentanyl acute exposure and washout modulated synaptic plasticity, but the inhibitory activation was not critical. Elucidating the detailed mechanisms for synaptic dysfunction after fentanyl exposure and washout may provide insights into POCD generation after fentanyl anesthesia.
Collapse
Affiliation(s)
- Hai Tian
- Clinic of Anesthesiology, No. 324 Hospital of the People's Liberation Army Chongqing, China
| | - Yueming Xu
- Clinic of Anesthesiology, No. 324 Hospital of the People's Liberation Army Chongqing, China
| | - Fucun Liu
- Clinic of Pharmacology, No. 324 Hospital of the People's Liberation Army Chongqing, China
| | - Guowei Wang
- Department of Medical Affairs, No. 324 Hospital of the People's Liberation Army Chongqing, China
| | - Sanjue Hu
- Institute of Neurosciences, The Fourth Military Medical University Xi'an, China
| |
Collapse
|
24
|
Korpi ER, den Hollander B, Farooq U, Vashchinkina E, Rajkumar R, Nutt DJ, Hyytiä P, Dawe GS. Mechanisms of Action and Persistent Neuroplasticity by Drugs of Abuse. Pharmacol Rev 2015; 67:872-1004. [DOI: 10.1124/pr.115.010967] [Citation(s) in RCA: 101] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
|
25
|
Abstract
Dopamine neurons in the ventral tegmental area (VTA) are a key target of addictive drugs, and neuroplasticity in this region may underlie some of the core features of addiction. From the very first exposure, all drugs of abuse induce synaptic plasticity in the VTA. However, it is not well understood how this diverse group of drugs brings about common synaptic change. Orexin (also known as hypocretin) is a lateral hypothalamic neuropeptide released into the VTA that promotes drug-seeking behaviors and potentiates excitatory synaptic transmission onto VTA dopamine neurons. Here we show that signaling at orexin receptor type 1 (OxR1) in the VTA is required for morphine-induced plasticity of dopamine neurons. Systemic or intra-VTA administration of the OxR1 antagonist SB 334867 in rats blocked a morphine-induced increase in the AMPAR/NMDAR ratio, an increase in presynaptic glutamate release, and a postsynaptic change in AMPAR number or function, including a switch in subunit composition. Furthermore, SB 334867 blocked a morphine-induced decrease in presynaptic GABA release, and a morphine-induced shift in the balance of excitatory and inhibitory synaptic inputs to dopamine neurons. These findings identify a novel role for orexin in morphine-induced plasticity in the VTA and provide a mechanism by which orexin can gate the output of dopamine neurons.
Collapse
|
26
|
Authement M, Kodangattil J, Gouty S, Rusnak M, Symes A, Cox B, Nugent F. Histone Deacetylase Inhibition Rescues Maternal Deprivation-Induced GABAergic Metaplasticity through Restoration of AKAP Signaling. Neuron 2015; 86:1240-52. [DOI: 10.1016/j.neuron.2015.05.024] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2014] [Revised: 04/23/2015] [Accepted: 05/07/2015] [Indexed: 12/27/2022]
|
27
|
Is a 'general' theory of addiction possible? A commentary on: a multistep general theory of transition to addiction. Psychopharmacology (Berl) 2014; 231:3923-7. [PMID: 24888430 DOI: 10.1007/s00213-014-3627-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/20/2014] [Accepted: 02/23/2014] [Indexed: 12/28/2022]
|
28
|
Atwood BK, Kupferschmidt DA, Lovinger DM. Opioids induce dissociable forms of long-term depression of excitatory inputs to the dorsal striatum. Nat Neurosci 2014; 17:540-8. [PMID: 24561996 DOI: 10.1038/nn.3652] [Citation(s) in RCA: 91] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2013] [Accepted: 01/20/2014] [Indexed: 11/09/2022]
Abstract
As prescription opioid analgesic abuse rates rise, so does the need to understand the long-term effects of opioid exposure on brain function. The dorsal striatum is an important site for drug-induced neuronal plasticity. We found that exogenously applied and endogenously released opioids induced long-term depression (OP-LTD) of excitatory inputs to the dorsal striatum in mice and rats. Mu and delta OP-LTD, although both being presynaptically expressed, were dissociable in that they summated, differentially occluded endocannabinoid-LTD and inhibited different striatal inputs. Kappa OP-LTD showed a unique subregional expression in striatum. A single in vivo exposure to the opioid analgesic oxycodone disrupted mu OP-LTD and endocannabinoid-LTD, but not delta or kappa OP-LTD. These data reveal previously unknown opioid-mediated forms of long-term striatal plasticity that are differentially affected by opioid analgesic exposure and are likely important mediators of striatum-dependent learning and behavior.
Collapse
Affiliation(s)
- Brady K Atwood
- Section on Synaptic Pharmacology, Laboratory for Integrative Neuroscience, National Institute on Alcohol Abuse and Alcoholism, US National Institutes of Health, Bethesda, Maryland, USA
| | - David A Kupferschmidt
- Section on Synaptic Pharmacology, Laboratory for Integrative Neuroscience, National Institute on Alcohol Abuse and Alcoholism, US National Institutes of Health, Bethesda, Maryland, USA
| | - David M Lovinger
- Section on Synaptic Pharmacology, Laboratory for Integrative Neuroscience, National Institute on Alcohol Abuse and Alcoholism, US National Institutes of Health, Bethesda, Maryland, USA
| |
Collapse
|
29
|
Kupchik YM, Scofield MD, Rice KC, Cheng K, Roques BP, Kalivas PW. Cocaine dysregulates opioid gating of GABA neurotransmission in the ventral pallidum. J Neurosci 2014; 34:1057-66. [PMID: 24431463 PMCID: PMC3891949 DOI: 10.1523/jneurosci.4336-13.2014] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2013] [Revised: 11/12/2013] [Accepted: 12/04/2013] [Indexed: 11/21/2022] Open
Abstract
The ventral pallidum (VP) is a target of dense nucleus accumbens projections. Many of these projections coexpress GABA and the neuropeptide enkephalin, a δ and μ opioid receptor (MOR) ligand. Of these two, the MOR in the VP is known to be involved in reward-related behaviors, such as hedonic responses to palatable food, alcohol intake, and reinstatement of cocaine seeking. Stimulating MORs in the VP decreases extracellular GABA, indicating that the effects of MORs in the VP on cocaine seeking are via modulating GABA neurotransmission. Here, we use whole-cell patch-clamp on a rat model of withdrawal from cocaine self-administration to test the hypothesis that MORs presynaptically regulate GABA transmission in the VP and that cocaine withdrawal changes the interaction between MORs and GABA. We found that in cocaine-extinguished rats pharmacological activation of MORs no longer presynaptically inhibited GABA release, whereas blocking the MORs disinhibited GABA release. Moreover, MOR-dependent long-term depression of GABA neurotransmission in the VP was lost in cocaine-extinguished rats. Last, GABA neurotransmission was found to be tonically suppressed in cocaine-extinguished rats. These substantial synaptic changes indicated that cocaine was increasing tone on MOR receptors. Accordingly, increasing endogenous tone by blocking the enzymatic degradation of enkephalin inhibited GABA neurotransmission in yoked saline rats but not in cocaine-extinguished rats. In conclusion, our results indicate that following withdrawal from cocaine self-administration enkephalin levels in the VP are elevated and the opioid modulation of GABA neurotransmission is impaired. This may contribute to the difficulties withdrawn addicts experience when trying to resist relapse.
Collapse
Affiliation(s)
- Yonatan M Kupchik
- Department of Neurosciences, Medical University of South Carolina, Charleston, South Carolina 29425, Chemical Biology Research Branch, National Institute on Drug Abuse and National Institute on Alcohol and Alcoholism, Rockville, Maryland 20892, Pharmaleads SAS, 75013 Paris, France, and Université Paris-Descartes, 75006 Paris, France
| | | | | | | | | | | |
Collapse
|
30
|
Opiate-induced molecular and cellular plasticity of ventral tegmental area and locus coeruleus catecholamine neurons. Cold Spring Harb Perspect Med 2013; 2:a012070. [PMID: 22762025 DOI: 10.1101/cshperspect.a012070] [Citation(s) in RCA: 83] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The study of neuronal adaptations induced by opiate drugs is particularly relevant today given their widespread prescription and nonprescription use. Although much is known about the acute actions of such drugs on the nervous system, a great deal of work remains to fully understand their chronic effects. Here, we focus on longer-lasting adaptations that occur in two catecholaminergic brain regions that mediate distinct behavioral actions of opiates: ventral tegmental area (VTA) dopaminergic neurons, important for drug reward, and locus coeruleus (LC) noradrenergic neurons, important for physical dependence and withdrawal. We focus on changes in cellular, synaptic, and structural plasticity in these brain regions that contribute to opiate dependence and addiction. Understanding the molecular determinants of this opiate-induced plasticity will be critical for the development of better treatments for opiate addiction and perhaps safer opiate drugs for medicinal use.
Collapse
|
31
|
Kodangattil JN, Dacher M, Authement ME, Nugent FS. Spike timing-dependent plasticity at GABAergic synapses in the ventral tegmental area. J Physiol 2013; 591:4699-710. [PMID: 23897235 DOI: 10.1113/jphysiol.2013.257873] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Persistent changes in excitatory and inhibitory synaptic strengths to the ventral tegmental area (VTA) dopamine (DA) neurons in response to addictive drugs may underlie the transition from casual to compulsive drug use. While an enormous amount of work has been done in the area of glutamatergic plasticity of the VTA, little is known regarding the learning rules governing GABAergic plasticity in the VTA. Spike timing-dependent plasticity, STDP, has attracted considerable attention primarily due to its potential roles in processing and storage of information in the brain and there is emerging evidence for the existence of STDP at inhibitory synapses. We therefore used whole-cell recordings in rat midbrain slices to investigate whether near-coincident pre- and postsynaptic firing induces a lasting change in synaptic efficacy of VTA GABAergic synapses. We found that a Hebbian form of STDP including long-term potentiation (LTP) and long-term depression (LTD) can be induced at GABAergic synapses onto VTA DA neurons and relies on the precise temporal order of pre- and postsynaptic spiking. Importantly, GABAergic STDP is heterosynaptic (NMDA receptor dependent): triggered by correlated activities of the presynaptic glutamatergic input and postsynaptic DA cells. GABAergic STDP is postsynaptic and has an associative component since pre- or postsynaptic spiking per se did not induce STDP. STDP of GABAergic synapses in the VTA provides physiologically relevant forms of inhibitory plasticity that may underlie natural reinforcement of reward-related behaviours. Moreover, this form of inhibitory plasticity may mediate some of the reinforcing, aversive and addictive properties of drugs of abuse.
Collapse
Affiliation(s)
- Jayaraj N Kodangattil
- F. S. Nugent: Edward Hebert School of Medicine, Department of Pharmacology, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, USA.
| | | | | | | |
Collapse
|
32
|
A-kinase anchoring protein-calcineurin signaling in long-term depression of GABAergic synapses. J Neurosci 2013; 33:2650-60. [PMID: 23392692 DOI: 10.1523/jneurosci.2037-12.2013] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The postsynaptic scaffolding A-kinase anchoring protein 79/150 (AKAP79/150) signaling complex regulates excitatory synaptic transmission and strength through tethering protein kinase A (PKA), PKC, and calcineurin (CaN) to the postsynaptic densities of neurons (Sanderson and Dell'Acqua, 2011), but its role in inhibitory synaptic transmission and plasticity is unknown. Using immunofluorescence and whole-cell patch-clamp recording in rat midbrain slices, we show that activation of postsynaptic D(2)-like family of dopamine (DA) receptor in the ventral tegmental area (VTA) induces long-term depression (LTD) of GABAergic synapses on DA neurons through an inositol triphosphate receptor-mediated local rise in postsynaptic Ca(2+) and CaN activation accompanied by PKA inhibition, which requires AKAP150 as a bridging signaling molecule. Our data also illuminate a requirement for a clathrin-mediated internalization of GABA(A) receptors in expression of LTD(GABA). Moreover, disruption of AKAP-PKA anchoring does not affect glutamatergic synapses onto DA neurons, suggesting that the PKA-AKAP-CaN complex is uniquely situated at GABA(A) receptor synapses in VTA DA neurons to regulate plasticity associated with GABA(A) receptors. Drug-induced modulation of GABAergic plasticity in the VTA through such novel signaling mechanisms has the potential to persistently alter the output of individual DA neurons and of the VTA, which may contribute to the reinforcing or addictive properties of drugs of abuse.
Collapse
|
33
|
Abstract
This paper is the thirty-fourth consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2011 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior (Section 2), and the roles of these opioid peptides and receptors in pain and analgesia (Section 3); stress and social status (Section 4); tolerance and dependence (Section 5); learning and memory (Section 6); eating and drinking (Section 7); alcohol and drugs of abuse (Section 8); sexual activity and hormones, pregnancy, development and endocrinology (Section 9); mental illness and mood (Section 10); seizures and neurologic disorders (Section 11); electrical-related activity and neurophysiology (Section 12); general activity and locomotion (Section 13); gastrointestinal, renal and hepatic functions (Section 14); cardiovascular responses (Section 15); respiration (Section 16); and immunological responses (Section 17).
Collapse
Affiliation(s)
- Richard J Bodnar
- Department of Psychology and Neuropsychology Doctoral Sub-Program, Queens College, City University of New York, Flushing, NY 11367, United States.
| |
Collapse
|
34
|
Badiani A, Belin D, Epstein D, Calu D, Shaham Y. Opiate versus psychostimulant addiction: the differences do matter. Nat Rev Neurosci 2011; 12:685-700. [PMID: 21971065 DOI: 10.1038/nrn3104] [Citation(s) in RCA: 355] [Impact Index Per Article: 27.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The publication of the psychomotor stimulant theory of addiction in 1987 and the finding that addictive drugs increase dopamine concentrations in the rat mesolimbic system in 1988 have led to a predominance of psychobiological theories that consider addiction to opiates and addiction to psychostimulants as essentially identical phenomena. Indeed, current theories of addiction - hedonic allostasis, incentive sensitization, aberrant learning and frontostriatal dysfunction - all argue for a unitary account of drug addiction. This view is challenged by behavioural, cognitive and neurobiological findings in laboratory animals and humans. Here, we argue that opiate addiction and psychostimulant addiction are behaviourally and neurobiologically distinct and that the differences have important implications for addiction treatment, addiction theories and future research.
Collapse
Affiliation(s)
- Aldo Badiani
- Department of Physiology and Pharmacology Vittorio Erspamer, Sapienza University of Rome, Rome, Italy.
| | | | | | | | | |
Collapse
|
35
|
Margolis EB, Mitchell JM, Hjelmstad GO, Fields HL. A novel opioid receptor-mediated enhancement of GABAA receptor function induced by stress in ventral tegmental area neurons. J Physiol 2011; 589:4229-42. [PMID: 21690191 DOI: 10.1113/jphysiol.2011.209023] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Opioid receptors are G-protein-coupled receptors (GPCRs) that modulate synaptic function. Depending upon their nervous system site of action, opioid receptor agonists alter food consumption, pain perception, responses to stress, and drug reward. Opioid receptors signal primarily via G(i/o)-proteins that modulate ion channels to directly inhibit neurons or decrease neurotransmitter release from nerve terminals. Here we report that following stress, activating δ opioid receptors (DORs) on midbrain ventral tegmental area (VTA) neurons causes a novel synaptic effect: the augmentation of GABA(A) receptor (GABA(A)R)-mediated inhibitory postsynaptic currents. Most neurons showing this augmentation were identified as dopaminergic. In addition, in both stressed and unstressed animals, DOR activation decreases GABA(A)R currents in some VTA neurons. Surprisingly, both augmentation and inhibition were also observed when we bypassed the presynaptic terminal by iontophoretically applying GABA, indicating that postsynaptic mechanisms are responsible for both effects. Using a variety of blockers we determined that the augmentation is probably due to insertion of GABA(A)Rs into the synapse by a mechanism that is G-protein independent and mediated by activation of Akt via PI3K. GABA(A)Rs are inserted into the extra-synaptic plasma membrane before trafficking to the synapse, a mechanism consistent with our observation that the DOR-mediated increase in GABA(A)R signalling occurs significantly earlier in iontophoretically applied than in electrically evoked synaptic GABA. This G-protein-independent signalling pathway is not only a novel mechanism of opioid receptor-mediated inhibition, but it also represents the first reported link between activation of a GPCR and insertion of GABA(A)Rs into the plasma membrane.
Collapse
Affiliation(s)
- Elyssa B Margolis
- Ernest Gallo Clinic and Research Centre, 5858 Horton Street, Suite no. 200, Emeryville, CA, USA.
| | | | | | | |
Collapse
|