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Luján MÁ, Covey DP, Young-Morrison R, Zhang L, Kim A, Morgado F, Patel S, Bass CE, Paladini C, Cheer JF. Mobilization of endocannabinoids by midbrain dopamine neurons is required for the encoding of reward prediction. Nat Commun 2023; 14:7545. [PMID: 37985770 PMCID: PMC10662422 DOI: 10.1038/s41467-023-43131-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Accepted: 11/01/2023] [Indexed: 11/22/2023] Open
Abstract
Brain levels of the endocannabinoid 2-arachidonoylglycerol (2-AG) shape motivated behavior and nucleus accumbens (NAc) dopamine release. However, it is not clear whether mobilization of 2-AG specifically from midbrain dopamine neurons is necessary for dopaminergic responses to external stimuli predicting forthcoming reward. Here, we use a viral-genetic strategy to prevent the expression of the 2-AG-synthesizing enzyme diacylglycerol lipase α (DGLα) from ventral tegmental area (VTA) dopamine cells in adult mice. We find that DGLα deletion from VTA dopamine neurons prevents depolarization-induced suppression of excitation (DSE), a form of 2-AG-mediated synaptic plasticity, in dopamine neurons. DGLα deletion also decreases effortful, cue-driven reward-seeking but has no effect on non-cued or low-effort operant tasks and other behaviors. Moreover, dopamine recording in the NAc reveals that deletion of DGLα impairs the transfer of accumbal dopamine signaling from a reward to its earliest predictors. These results demonstrate that 2-AG mobilization from VTA dopamine neurons is a necessary step for the generation of dopamine-based predictive associations that are required to direct and energize reward-oriented behavior.
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Affiliation(s)
- Miguel Á Luján
- Department of Neurobiology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Dan P Covey
- Department of Neurobiology, University of Maryland School of Medicine, Baltimore, MD, USA
- Department of Neuroscience, Lovelace Biomedical Research Institute, Albuquerque, NM, USA
| | - Reana Young-Morrison
- Department of Neurobiology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - LanYuan Zhang
- Department of Neurobiology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Andrew Kim
- Department of Neurobiology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Fiorella Morgado
- Department of Neurobiology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Sachin Patel
- Northwestern Center for Psychiatric Neuroscience, Department of Psychiatry and Behavioral Sciences, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - Caroline E Bass
- Department of Pharmacology and Toxicology, University at Buffalo, State University of New York, Buffalo, NY, USA
| | - Carlos Paladini
- UTSA Neuroscience Institute, University of Texas at San Antonio, San Antonio, TX, USA
| | - Joseph F Cheer
- Department of Neurobiology, University of Maryland School of Medicine, Baltimore, MD, USA.
- Department of Psychiatry, University of Maryland School of Medicine, Baltimore, MD, USA.
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2
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Edwards JG, Cristino L, Covey DP. Editorial: The Emerging Role of Endocannabinoids in Synaptic Plasticity, Reward, and Addiction. Front Synaptic Neurosci 2022; 14:898090. [PMID: 35615441 PMCID: PMC9125233 DOI: 10.3389/fnsyn.2022.898090] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2022] [Accepted: 03/25/2022] [Indexed: 11/13/2022] Open
Affiliation(s)
- Jeffrey G. Edwards
- Department of Cell Biology and Physiology, Neuroscience Center Director, Brigham Young University, Provo, UT, United States
- *Correspondence: Jeffrey G. Edwards
| | - Luigia Cristino
- Institute of Biomolecular Chemistry, Italian National Research Council, Pozzuoli, Italy
| | - Dan P. Covey
- Department of Neuroscience, Lovelace Biomedical Research Institute, Albuquerque, NM, United States
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3
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Covey DP, Yocky AG. Endocannabinoid Modulation of Nucleus Accumbens Microcircuitry and Terminal Dopamine Release. Front Synaptic Neurosci 2021; 13:734975. [PMID: 34497503 PMCID: PMC8419321 DOI: 10.3389/fnsyn.2021.734975] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Accepted: 08/05/2021] [Indexed: 12/20/2022] Open
Abstract
The nucleus accumbens (NAc) is located in the ventromedial portion of the striatum and is vital to valence-based predictions and motivated action. The neural architecture of the NAc allows for complex interactions between various cell types that filter incoming and outgoing information. Dopamine (DA) input serves a crucial role in modulating NAc function, but the mechanisms that control terminal DA release and its effect on NAc neurons continues to be elucidated. The endocannabinoid (eCB) system has emerged as an important filter of neural circuitry within the NAc that locally shapes terminal DA release through various cell type- and site-specific actions. Here, we will discuss how eCB signaling modulates terminal DA release by shaping the activity patterns of NAc neurons and their afferent inputs. We then discuss recent technological advancements that are capable of dissecting how distinct cell types, their afferent projections, and local neuromodulators influence valence-based actions.
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Affiliation(s)
- Dan P Covey
- Department of Neuroscience, Lovelace Biomedical Research Institute, Albuquerque, NM, United States
| | - Alyssa G Yocky
- Department of Neuroscience, Lovelace Biomedical Research Institute, Albuquerque, NM, United States
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4
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Covey DP, Hernandez E, Luján MÁ, Cheer JF. Chronic Augmentation of Endocannabinoid Levels Persistently Increases Dopaminergic Encoding of Reward Cost and Motivation. J Neurosci 2021; 41:6946-6953. [PMID: 34230105 PMCID: PMC8360683 DOI: 10.1523/jneurosci.0285-21.2021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Revised: 06/16/2021] [Accepted: 06/21/2021] [Indexed: 11/21/2022] Open
Abstract
Motivational deficits characterized by an unwillingness to overcome effortful costs are a common feature of neuropsychiatric and neurologic disorders that are insufficiently understood and treated. Dopamine (DA) signaling in the nucleus accumbens (NAc) facilitates goal-seeking, but how NAc DA release encodes motivationally salient stimuli to influence effortful investment is not clear. Using fast-scan cyclic voltammetry in male and female mice, we find that NAc DA release diametrically responds to cues signaling increasing cost of reward, while DA release to the reward itself is unaffected by its cost. Because endocannabinoid (eCB) signaling facilitates goal seeking and NAc DA release, we further investigated whether repeated augmentation of the eCB 2-arachidonoylglycerol with a low dose of a monoacylglycerol lipase (MAGL) inhibitor facilitates motivation and DA signaling without the development of tolerance. We find that chronic MAGL treatment stably facilitates goal seeking and DA encoding of prior reward cost, providing critical insight into the neurobiological mechanisms of a viable treatment for motivational deficits.SIGNIFICANCE STATEMENT Decades of work has established a fundamental role for dopamine neurotransmission in motivated behavior and cue-reward learning, but how dopaminergic encoding of cues associates with motivated action has remained unclear. Specifically, how dopamine neurons signal future and prior reward cost, and whether this can be modified to influence motivational set points is not known. The current study provides important insight into how dopamine neurons encode motivationally relevant stimuli to influence goal-directed action and supports cannabinoid-based therapies for treatment of motivational disorders.
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Affiliation(s)
- Dan P Covey
- Department of Neuroscience, Lovelace Biomedical Research Institute, Albuquerque, New Mexico 87108
| | - Edith Hernandez
- Medical Scientist Training Program (MD/PhD), University of Minnesota Medical School, Minneapolis, Minnesota 55455
| | - Miguel Á Luján
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, Maryland 21201
| | - Joseph F Cheer
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, Maryland 21201
- Department of Psychiatry, University of Maryland School of Medicine, Baltimore, Maryland 21201
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5
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Hergert DC, Robertson-Benta C, Sicard V, Schwotzer D, Hutchison K, Covey DP, Quinn DK, Sadek JR, McDonald J, Mayer AR. Use of Medical Cannabis to Treat Traumatic Brain Injury. J Neurotrauma 2021; 38:1904-1917. [PMID: 33256496 DOI: 10.1089/neu.2020.7148] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
There is not a single pharmacological agent with demonstrated therapeutic efficacy for traumatic brain injury (TBI). With recent legalization efforts and the growing popularity of medical cannabis, patients with TBI will inevitably consider medical cannabis as a treatment option. Pre-clinical TBI research suggests that cannabinoids have neuroprotective and psychotherapeutic properties. In contrast, recreational cannabis use has consistently shown to have detrimental effects. Our review identified a paucity of high-quality studies examining the beneficial and adverse effects of medical cannabis on TBI, with only a single phase III randomized control trial. However, observational studies demonstrate that TBI patients are using medical and recreational cannabis to treat their symptoms, highlighting inconsistencies between public policy, perception of potential efficacy, and the dearth of empirical evidence. We conclude that randomized controlled trials and prospective studies with appropriate control groups are necessary to fully understand the efficacy and potential adverse effects of medical cannabis for TBI.
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Affiliation(s)
- Danielle C Hergert
- The Mind Research Network/Lovelace Biomedical and Environmental Research Institute, Pete & Nancy Domenici Hall, Albuquerque, New Mexico, USA
| | - Cidney Robertson-Benta
- The Mind Research Network/Lovelace Biomedical and Environmental Research Institute, Pete & Nancy Domenici Hall, Albuquerque, New Mexico, USA
| | - Veronik Sicard
- The Mind Research Network/Lovelace Biomedical and Environmental Research Institute, Pete & Nancy Domenici Hall, Albuquerque, New Mexico, USA
| | - Daniela Schwotzer
- Lovelace Biomedical and Environmental Research Institute, Albuquerque, New Mexico, USA
| | - Kent Hutchison
- Department of Psychology and Neuroscience, University of Colorado, Boulder, Colorado, USA
| | - Dan P Covey
- Lovelace Biomedical and Environmental Research Institute, Albuquerque, New Mexico, USA
| | - Davin K Quinn
- Department of Neurology, University of New Mexico Health Sciences Center, Albuquerque, New Mexico, USA
| | - Joseph R Sadek
- Department of Neurology, University of New Mexico Health Sciences Center, Albuquerque, New Mexico, USA.,Department of Psychiatry and Behavioral Sciences, University of New Mexico Health Sciences Center, Albuquerque, New Mexico, USA.,New Mexico VA Health Care System, Albuquerque, New Mexico, USA
| | - Jacob McDonald
- Lovelace Biomedical and Environmental Research Institute, Albuquerque, New Mexico, USA
| | - Andrew R Mayer
- The Mind Research Network/Lovelace Biomedical and Environmental Research Institute, Pete & Nancy Domenici Hall, Albuquerque, New Mexico, USA.,Department of Neurology, University of New Mexico Health Sciences Center, Albuquerque, New Mexico, USA.,Department of Psychiatry and Behavioral Sciences, University of New Mexico Health Sciences Center, Albuquerque, New Mexico, USA.,Psychology Department, University of New Mexico, Albuquerque, New Mexico, USA
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6
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Radke AK, Kocharian A, Covey DP, Lovinger DM, Cheer JF, Mateo Y, Holmes A. Contributions of nucleus accumbens dopamine to cognitive flexibility. Eur J Neurosci 2018; 50:2023-2035. [PMID: 30218623 DOI: 10.1111/ejn.14152] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2018] [Revised: 08/22/2018] [Accepted: 09/10/2018] [Indexed: 02/06/2023]
Abstract
There is a compelling evidence that midbrain dopamine (DA) neurons and their projections to the ventral striatum provide a mechanism for motivating reward-seeking behavior, and for utilizing information about unexpected reward prediction errors (RPEs) to guide behavior based on current, rather than historical, outcomes. When this mechanism is compromised in addictions, it may produce patterns of maladaptive behavior that remain obdurate in the face of contrary information and even adverse consequences. Nonetheless, DAergic contributions to performance on behavioral tasks that rely on the ability to flexibly update stimulus-reward relationships remains incompletly understood. In the current study, we used a discrimination and reversal paradigm to monitor subsecond DA release in mouse NAc core (NAc) using in vivo fast-scan cyclic voltammetry (FSCV). We observed post-choice elevations in phasic NAc DA release; however, increased DA transients were only evident during early reversal when mice made responses at the newly rewarded stimulus. Based on this finding, we used in vivo optogenetic (eNpHR) photosilencing and (Channelrhodopsin2 [ChR2]) photostimulation to assess the effects of manipulating VTA-DAergic fibers in the NAc on reversal performance. Photosilencing the VTA → NAc DAergic pathway during early reversal increased errors, while photostimulation did not demonstrably affect behavior. Taken together, these data provide additional evidence of the importance of NAc DA release as a neural substrate supporting adjustments in learned behavior after a switch in expected stimulus-reward contingencies. These findings have possible implications for furthering understanding the role of DA in persistent, maladaptive decision-making characterizing addictions.
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Affiliation(s)
- Anna K Radke
- Laboratory of Behavioral and Genomic Neuroscience, National Institute on Alcohol Abuse and Alcoholism, Bethesda, MD, USA.,Psychology Department, Miami University, 90 N Patterson Ave, Oxford, OH, 45056, USA.,Center for Neuroscience and Behavior, Miami University, Oxford, OH, USA
| | - Adrina Kocharian
- Laboratory of Behavioral and Genomic Neuroscience, National Institute on Alcohol Abuse and Alcoholism, Bethesda, MD, USA
| | - Dan P Covey
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD, USA.,Department of Psychiatry, University of Maryland School of Medicine, Baltimore, MD, USA
| | - David M Lovinger
- Department of Psychiatry, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Joseph F Cheer
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD, USA.,Department of Psychiatry, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Yolanda Mateo
- Laboratory for Integrative Neuroscience, National Institute on Alcohol Abuse and Alcoholism, Bethesda, MD, USA
| | - Andrew Holmes
- Laboratory of Behavioral and Genomic Neuroscience, National Institute on Alcohol Abuse and Alcoholism, Bethesda, MD, USA
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7
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Covey DP, Dantrassy HM, Yohn SE, Castro A, Conn PJ, Mateo Y, Cheer JF. Inhibition of endocannabinoid degradation rectifies motivational and dopaminergic deficits in the Q175 mouse model of Huntington's disease. Neuropsychopharmacology 2018; 43:2056-2063. [PMID: 29925886 PMCID: PMC6098121 DOI: 10.1038/s41386-018-0107-8] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/13/2018] [Revised: 05/18/2018] [Accepted: 05/24/2018] [Indexed: 12/13/2022]
Abstract
Prominent motor deficits (e.g., chorea) that typify Huntington's disease (HD) arise following a prolonged prodromal stage characterized by psychiatric disturbances. Apathy, a disorder of motivation characterized by diminished goal-directed behavior, is one of the earliest and most common psychiatric symptoms in HD, but the underlying neurobiology is unclear and treatment options are limited. Alterations in the endocannabinoid (eCB) and dopamine systems represent prominent pathophysiological markers in HD that-similar to motivational deficits-present early and decline across disease progression. Whether changes in dopamine and eCB systems are associated with specific behavioral impairments in HD and whether these deficits are amenable to viable treatments is unknown. Here, we show that dopaminergic encoding of effortful drive progressively declines with age in an HD mouse model, and is restored by elevating tissue levels of the eCB 2-arachidonoylglycerol (2-AG) through targeted inhibition of its enzymatic degradation. This work supports aberrant dopaminergic encoding of reward as a neurobiological correlate of apathy in HD, and indicates that cannabinoid receptor-based therapies may benefit neuropsychiatric care for HD.
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Affiliation(s)
- Dan P. Covey
- 0000 0001 2175 4264grid.411024.2Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD USA
| | - Hannah M. Dantrassy
- 0000 0001 2175 4264grid.411024.2Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD USA
| | - Samantha E. Yohn
- 0000 0001 2264 7217grid.152326.1Department of Pharmacology, Vanderbilt Kennedy Center, Vanderbilt University School of Medicine, Nashville, TN USA ,0000 0001 2264 7217grid.152326.1Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, TN 37232 USA
| | - Alberto Castro
- 0000 0001 2175 4264grid.411024.2Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD USA
| | - P. Jeffrey Conn
- 0000 0001 2264 7217grid.152326.1Department of Pharmacology, Vanderbilt Kennedy Center, Vanderbilt University School of Medicine, Nashville, TN USA ,0000 0001 2264 7217grid.152326.1Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, TN 37232 USA ,0000 0001 2264 7217grid.152326.1Vanderbilt Kennedy Center, Vanderbilt University School of Medicine, Nashville, TN USA
| | - Yolanda Mateo
- 0000 0001 2297 5165grid.94365.3dSection on Synaptic Pharmacology, Laboratory for Integrative Neuroscience, National Institute on Alcohol Abuse and Alcoholism, US National Institute of Health, Rockville, MD USA
| | - Joseph F. Cheer
- 0000 0001 2175 4264grid.411024.2Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD USA ,0000 0001 2175 4264grid.411024.2Department of Psychiatry, University of Maryland School of Medicine, Baltimore, MD USA
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8
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Mateo Y, Johnson KA, Covey DP, Atwood BK, Wang HL, Zhang S, Gildish I, Cachope R, Bellocchio L, Guzmán M, Morales M, Cheer JF, Lovinger DM. Endocannabinoid Actions on Cortical Terminals Orchestrate Local Modulation of Dopamine Release in the Nucleus Accumbens. Neuron 2017; 96:1112-1126.e5. [PMID: 29216450 DOI: 10.1016/j.neuron.2017.11.012] [Citation(s) in RCA: 81] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2016] [Revised: 04/08/2017] [Accepted: 11/09/2017] [Indexed: 12/14/2022]
Abstract
Dopamine (DA) transmission mediates numerous aspects of behavior. Although DA release is strongly linked to firing of DA neurons, recent developments indicate the importance of presynaptic modulation at striatal dopaminergic terminals. The endocannabinoid (eCB) system regulates DA release and is a canonical gatekeeper of goal-directed behavior. Here we report that extracellular DA increases induced by selective optogenetic activation of cholinergic neurons in the nucleus accumbens (NAc) are inhibited by CB1 agonists and eCBs. This modulation requires CB1 receptors on cortical glutamatergic afferents. Dopamine increases driven by optogenetic activation of prefrontal cortex (PFC) terminals in the NAc are similarly modulated by activation of these CB1 receptors. We further demonstrate that this same population of CB1 receptors modulates optical self-stimulation sustained by activation of PFC afferents in the NAc. These results establish local eCB actions on PFC terminals within the NAc that inhibit mesolimbic DA release and constrain reward-driven behavior.
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Affiliation(s)
- Yolanda Mateo
- Section on Synaptic Pharmacology, Laboratory for Integrative Neuroscience, National Institute on Alcohol Abuse and Alcoholism, US National Institutes of Health, Rockville, MD, USA
| | - Kari A Johnson
- Section on Synaptic Pharmacology, Laboratory for Integrative Neuroscience, National Institute on Alcohol Abuse and Alcoholism, US National Institutes of Health, Rockville, MD, USA
| | - Dan P Covey
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Brady K Atwood
- Section on Synaptic Pharmacology, Laboratory for Integrative Neuroscience, National Institute on Alcohol Abuse and Alcoholism, US National Institutes of Health, Rockville, MD, USA
| | - Hui-Ling Wang
- Neuronal Networks Section, National Institute on Drug Abuse, US National Institutes of Health, Baltimore, MD, USA
| | - Shiliang Zhang
- Neuronal Networks Section, National Institute on Drug Abuse, US National Institutes of Health, Baltimore, MD, USA
| | - Iness Gildish
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Roger Cachope
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Luigi Bellocchio
- Department of Biochemistry and Molecular Biology I, Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Instituto Ramón y Cajal de Investigación Sanitaria (IRYCIS) and Instituto Universitario de Investigación Neuroquímica (IUIN), Complutense University, Madrid, Spain
| | - Manuel Guzmán
- Department of Biochemistry and Molecular Biology I, Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Instituto Ramón y Cajal de Investigación Sanitaria (IRYCIS) and Instituto Universitario de Investigación Neuroquímica (IUIN), Complutense University, Madrid, Spain
| | - Marisela Morales
- Neuronal Networks Section, National Institute on Drug Abuse, US National Institutes of Health, Baltimore, MD, USA
| | - Joseph F Cheer
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD, USA; Department of Psychiatry, University of Maryland School of Medicine, Baltimore, MD, USA.
| | - David M Lovinger
- Section on Synaptic Pharmacology, Laboratory for Integrative Neuroscience, National Institute on Alcohol Abuse and Alcoholism, US National Institutes of Health, Rockville, MD, USA.
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9
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Covey DP, Bunner KD, Schuweiler DR, Cheer JF, Garris PA. Amphetamine elevates nucleus accumbens dopamine via an action potential-dependent mechanism that is modulated by endocannabinoids. Eur J Neurosci 2016; 43:1661-73. [PMID: 27038339 PMCID: PMC5819353 DOI: 10.1111/ejn.13248] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Accepted: 03/29/2016] [Indexed: 02/04/2023]
Abstract
The reinforcing effects of abused drugs are mediated by their ability to elevate nucleus accumbens dopamine. Amphetamine (AMPH) was historically thought to increase dopamine by an action potential-independent, non-exocytotic type of release called efflux, involving reversal of dopamine transporter function and driven by vesicular dopamine depletion. Growing evidence suggests that AMPH also acts by an action potential-dependent mechanism. Indeed, fast-scan cyclic voltammetry demonstrates that AMPH activates dopamine transients, reward-related phasic signals generated by burst firing of dopamine neurons and dependent on intact vesicular dopamine. Not established for AMPH but indicating a shared mechanism, endocannabinoids facilitate this activation of dopamine transients by broad classes of abused drugs. Here, using fast-scan cyclic voltammetry coupled to pharmacological manipulations in awake rats, we investigated the action potential and endocannabinoid dependence of AMPH-induced elevations in nucleus accumbens dopamine. AMPH increased the frequency, amplitude and duration of transients, which were observed riding on top of slower dopamine increases. Surprisingly, silencing dopamine neuron firing abolished all AMPH-induced dopamine elevations, identifying an action potential-dependent origin. Blocking cannabinoid type 1 receptors prevented AMPH from increasing transient frequency, similar to reported effects on other abused drugs, but not from increasing transient duration and inhibiting dopamine uptake. Thus, AMPH elevates nucleus accumbens dopamine by eliciting transients via cannabinoid type 1 receptors and promoting the summation of temporally coincident transients, made more numerous, larger and wider by AMPH. Collectively, these findings are inconsistent with AMPH eliciting action potential-independent dopamine efflux and vesicular dopamine depletion, and support endocannabinoids facilitating phasic dopamine signalling as a common action in drug reinforcement.
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Affiliation(s)
- Dan P. Covey
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Kendra D. Bunner
- Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN, USA
| | - Douglas R. Schuweiler
- School of Biological Sciences, Illinois State University, 210 Julian Hall, Normal, IL 61790-4120, USA
| | - Joseph F. Cheer
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD, USA
- Department of Psychiatry, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Paul A. Garris
- School of Biological Sciences, Illinois State University, 210 Julian Hall, Normal, IL 61790-4120, USA
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10
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Covey DP, Wenzel JM, Cheer JF. Cannabinoid modulation of drug reward and the implications of marijuana legalization. Brain Res 2014; 1628:233-43. [PMID: 25463025 DOI: 10.1016/j.brainres.2014.11.034] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2014] [Revised: 11/11/2014] [Accepted: 11/15/2014] [Indexed: 10/24/2022]
Abstract
Marijuana is the most popular illegal drug worldwide. Recent trends indicate that this may soon change; not due to decreased marijuana use, but to an amendment in marijuana's illegal status. The cannabinoid type 1 (CB1) receptor mediates marijuana's psychoactive and reinforcing properties. CB1 receptors are also part of the brain endocannabinoid (eCB) system and support numerous forms of learning and memory, including the conditioned reinforcing properties of cues predicting reward or punishment. This is accomplished via eCB-dependent alterations in mesolimbic dopamine function, which plays an obligatory role in reward learning and motivation. Presynaptic CB1 receptors control midbrain dopamine neuron activity and thereby shape phasic dopamine release in target regions, particularly the nucleus accumbens (NAc). By also regulating synaptic input to the NAc, CB1 receptors modulate NAc output onto downstream neurons of the basal ganglia motor circuit, and thereby support goal-directed behaviors. Abused drugs promote short- and long-term adaptations in eCB-regulation of mesolimbic dopamine function, and thereby hijack neural systems related to the pursuit of rewards to promote drug abuse. By pharmacologically targeting the CB1 receptors, marijuana has preferential access to this neuronal system and can potently alter eCB-dependent processing of reward-related stimuli. As marijuana legalization progresses, greater access to this drug should increase the utility of marijuana as a research tool to better understand the eCB system, which has the potential to advance cannabinoid-based treatments for drug addiction.
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Affiliation(s)
- Dan P Covey
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD, USA; Department of Psychiatry, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Jennifer M Wenzel
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD, USA; Department of Psychiatry, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Joseph F Cheer
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD, USA; Department of Psychiatry, University of Maryland School of Medicine, Baltimore, MD, USA.
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11
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Covey DP, Cheer JF. Pick your poison: not all opioids are created equal in the eyes of dopamine (commentary on Vander Weele et al.). Eur J Neurosci 2014; 40:3040. [PMID: 25288049 DOI: 10.1111/ejn.12726] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Dan P Covey
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, 20 Penn Street, Baltimore, MD 21201, USA
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12
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Covey DP, Roitman MF, Garris PA. Illicit dopamine transients: reconciling actions of abused drugs. Trends Neurosci 2014; 37:200-10. [PMID: 24656971 DOI: 10.1016/j.tins.2014.02.002] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2013] [Revised: 01/27/2014] [Accepted: 02/05/2014] [Indexed: 01/03/2023]
Abstract
Phasic increases in brain dopamine are required for cue-directed reward seeking. Although compelling within the framework of appetitive behavior, the view that illicit drugs hijack reward circuits by hyperactivating these dopamine transients is inconsistent with established psychostimulant pharmacology. However, recent work reclassifying amphetamine (AMPH), cocaine, and other addictive dopamine-transporter inhibitors (DAT-Is) supports transient hyperactivation as a unifying hypothesis of abused drugs. We argue here that reclassification also identifies generating burst firing by dopamine neurons as a keystone action. Unlike natural rewards, which are processed by sensory systems, drugs act directly on the brain. Consequently, to mimic natural rewards and exploit reward circuits, dopamine transients must be elicited de novo. Of available drug targets, only burst firing achieves this essential outcome.
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Affiliation(s)
- Dan P Covey
- School of Biological Sciences, Illinois State University, Normal, IL 61790-4120, USA
| | - Mitchell F Roitman
- Department of Psychology, University of Illinois at Chicago, Chicago, IL 60607-7137, USA
| | - Paul A Garris
- School of Biological Sciences, Illinois State University, Normal, IL 61790-4120, USA.
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13
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Arumugam PU, Zeng H, Siddiqui S, Covey DP, Carlisle JA, Garris PA. Characterization of ultrananocrystalline diamond microsensors for in vivo dopamine detection. Appl Phys Lett 2013; 102:253107. [PMID: 23918991 PMCID: PMC3710216 DOI: 10.1063/1.4811785] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/03/2013] [Accepted: 06/01/2013] [Indexed: 05/18/2023]
Abstract
We show the technical feasibility of coating and micro patterning boron-doped ultrananocrystalline diamond (UNCD®) on metal microwires and of applying them as microsensors for the detection of dopamine in vivo using fast-scan cyclic voltammetry. UNCD electrode surface consistently generated electrochemical signals with high signal-to-noise ratio of >800 using potassium ferrocyanide-ferricyanide redox couple. Parylene patterned UNCD microelectrodes were effectively applied to detect dopamine reliably in vitro using flow injection analysis with a detection limit of 27 nM and in the striatum of the anesthetized rat during electrical stimulation of dopamine neurons.
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Affiliation(s)
- Prabhu U Arumugam
- Advanced Diamond Technologies, Inc., 48 E Belmont Drive, Romeoville, Illinois 60446, USA
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14
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Abstract
Amphetamine, a highly addictive drug with therapeutic efficacy, exerts paradoxical effects on the fundamental communication modes employed by dopamine neurons in modulating behavior. While amphetamine elevates tonic dopamine signaling by depleting vesicular stores and driving non-exocytotic release through reverse transport, this psychostimulant also activates phasic dopamine signaling by up-regulating vesicular dopamine release. We hypothesized that these seemingly incongruent effects arise from amphetamine depleting the reserve pool and enhancing the readily releasable pool. This novel hypothesis was tested using in vivo voltammetry and stimulus trains of varying duration to access different vesicular stores. We show that amphetamine actions are stimulus dependent in the dorsal striatum. Specifically, amphetamine up-regulated vesicular dopamine release elicited by a short-duration train, which interrogates the readily releasable pool, but depleted release elicited by a long-duration train, which interrogates the reserve pool. These opposing actions of vesicular dopamine release were associated with concurrent increases in tonic and phasic dopamine responses. A link between vesicular depletion and tonic signaling was supported by results obtained for amphetamine in the ventral striatum and cocaine in both striatal sub-regions, which demonstrated augmented vesicular release and phasic signals only. We submit that amphetamine differentially targeting dopamine stores reconciles the paradoxical activation of tonic and phasic dopamine signaling. Overall, these results further highlight the unique and region-distinct cellular mechanisms of amphetamine and may have important implications for its addictive and therapeutic properties.
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Affiliation(s)
- Dan P. Covey
- School of Biological Sciences, Illinois State University, Normal, Illinois, United States of America
| | - Steven A. Juliano
- School of Biological Sciences, Illinois State University, Normal, Illinois, United States of America
| | - Paul A. Garris
- School of Biological Sciences, Illinois State University, Normal, Illinois, United States of America
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15
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Ramsson ES, Howard CD, Covey DP, Garris PA. High doses of amphetamine augment, rather than disrupt, exocytotic dopamine release in the dorsal and ventral striatum of the anesthetized rat. J Neurochem 2011; 119:1162-72. [PMID: 21806614 DOI: 10.1111/j.1471-4159.2011.07407.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
High doses of amphetamine (AMPH) are thought to disrupt normal patterns of action potential-dependent dopaminergic neurotransmission by depleting vesicular stores of dopamine (DA) and inducing robust non-exocytotic DA release or efflux via dopamine transporter (DAT) reversal. However, these cardinal AMPH actions have been difficult to establish definitively in vivo. Here, we use fast-scan cyclic voltammetry (FSCV) in the urethane-anesthetized rat to evaluate the effects of 10 and 20 mg/kg AMPH on vesicular DA release and DAT function in dorsal and ventral striata. An equivalent high dose of cocaine (40 mg/kg) was also examined for comparison to psychostimulants acting preferentially by DAT inhibition. Parameters describing exocytotic DA release and neuronal DA uptake were determined from dynamic DA signals evoked by mild electrical stimulation previously established to be reinforcing. High-sensitivity FSCV with nanomolar detection was used to monitor changes in the background voltammetric signal as an index of DA efflux. Both doses of AMPH and cocaine markedly elevated evoked DA levels over the entire 2-h time course in the dorsal and ventral striatum. These increases were mediated by augmented vesicular DA release and diminished DA uptake typically acting concurrently. AMPH, but not cocaine, induced a slow, DA-like rise in some baseline recordings. However, this effect was highly variable in amplitude and duration, modest, and generally not present at all. These data thus describe a mechanistically similar activation of action potential-dependent dopaminergic neurotransmission by AMPH and cocaine in vivo. Moreover, DA efflux appears to be a unique, but secondary, AMPH action.
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Affiliation(s)
- Eric S Ramsson
- School of Biological Sciences, Illinois State University, Normal, IL, USA
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Covey DP, Garris PA. Using fast-scan cyclic voltammetry to evaluate striatal dopamine release elicited by subthalamic nucleus stimulation. Annu Int Conf IEEE Eng Med Biol Soc 2010; 2009:3306-9. [PMID: 19964299 DOI: 10.1109/iembs.2009.5333768] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Deep brain stimulation (DBS), an effective neurosurgical therapy for Parkinson's disease (PD), may act via eliciting neurotransmitter release. However, the precise relationships between DBS and neurotransmitter release are not established. One issue in these studies may be analytical limitations of microdialysis and positron emission tomography, the primary measurement technologies employed. Limitations may be overcome by microsensors, which exhibit improved temporal and spatial resolution. Here we assess fast-scan cyclic voltammetry (FSCV) at a carbon-fiber microelectrode (CFM) for monitoring a putative DBS neurotransmitter, dopamine, during stimulation of the subthalamic nucleus (STN), a DBS target for PD. These results, obtained in the anesthetized rat, suggest that real-time microsensors are a suitable approach for testing the neurotransmitter release hypothesis of DBS action.
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Affiliation(s)
- Dan P Covey
- School of Biological Sciences and Department of Chemistry, Illinois State University, Normal, IL, USA
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Roham M, Daberkow DP, Ramsson ES, Covey DP, Pakdeeronachit S, Garris PA, Mohseni P. A Wireless IC for Wide-Range Neurochemical Monitoring Using Amperometry and Fast-Scan Cyclic Voltammetry. IEEE Trans Biomed Circuits Syst 2008; 2:3-9. [PMID: 23852628 DOI: 10.1109/tbcas.2008.918282] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
An integrated circuit for real-time wireless monitoring of neurochemical activity in the nervous system is described. The chip is capable of conducting measurements in both fast-scan cyclic voltammetry (FSCV) and amperometry modes for a wide input current range. The chip architecture employs a second-order DeltaSigma modulator (DeltaSigmaM) and a frequency-shift-keyed transmitter operating near 433 MHz. It is fabricated using the AMI 0.5-mum double-poly triple-metal n-well CMOS process, and requires only one off-chip component for operation. A measured current resolution of 12 pA at a sampling rate of 100 Hz and 132 pA at a sampling rate of 10 kHz is achieved in amperometry and 300-V/s FSCV modes, respectively, for any input current in the range of plusmn430 nA. The modulator core and the transmitter draw 22 and 400 muA from a 2.6-V power supply, respectively. The chip has been externally interfaced with a carbon-fiber microelectrode implanted acutely in the caudate-putamen of an anesthetized rat, and, for the first time, extracellular levels of dopamine elicited by electrical stimulation of the medial forebrain bundle have been successfully recorded wirelessly using 300-V/s FSCV.
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