1
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Burwell SC, Yan H, Lim SS, Shields BC, Tadross MR. Natural phasic inhibition of dopamine neurons signals cognitive rigidity. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.09.593320. [PMID: 38766037 PMCID: PMC11100816 DOI: 10.1101/2024.05.09.593320] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2024]
Abstract
When animals unexpectedly fail, their dopamine neurons undergo phasic inhibition that canonically drives extinction learning-a cognitive-flexibility mechanism for discarding outdated strategies. However, the existing evidence equates natural and artificial phasic inhibition, despite their spatiotemporal differences. Addressing this gap, we targeted a GABAA-receptor antagonist precisely to dopamine neurons, yielding three unexpected findings. First, this intervention blocked natural phasic inhibition selectively, leaving tonic activity unaffected. Second, blocking natural phasic inhibition accelerated extinction learning-opposite to canonical mechanisms. Third, our approach selectively benefitted perseverative mice, restoring rapid extinction without affecting new reward learning. Our findings reveal that extinction learning is rapid by default and slowed by natural phasic inhibition-challenging foundational learning theories, while delineating a synaptic mechanism and therapeutic target for cognitive rigidity.
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Affiliation(s)
- Sasha C.V. Burwell
- Department of Neurobiology, Duke University, Durham, NC
- Aligning Science Across Parkinson’s (ASAP) Collaborative Research Network, Chevy Chase, MD
| | - Haidun Yan
- Department of Biomedical Engineering, Duke University, NC
- Aligning Science Across Parkinson’s (ASAP) Collaborative Research Network, Chevy Chase, MD
| | - Shaun S.X. Lim
- Department of Biomedical Engineering, Duke University, NC
- Aligning Science Across Parkinson’s (ASAP) Collaborative Research Network, Chevy Chase, MD
| | - Brenda C. Shields
- Department of Biomedical Engineering, Duke University, NC
- Aligning Science Across Parkinson’s (ASAP) Collaborative Research Network, Chevy Chase, MD
| | - Michael R. Tadross
- Department of Neurobiology, Duke University, Durham, NC
- Department of Biomedical Engineering, Duke University, NC
- Aligning Science Across Parkinson’s (ASAP) Collaborative Research Network, Chevy Chase, MD
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2
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Aristieta A, Parker JE, Gao YE, Rubin JE, Gittis AH. Dopamine depletion weakens direct pathway modulation of SNr neurons. Neurobiol Dis 2024; 196:106512. [PMID: 38670278 DOI: 10.1016/j.nbd.2024.106512] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2024] [Revised: 04/13/2024] [Accepted: 04/23/2024] [Indexed: 04/28/2024] Open
Abstract
Neurons in the substantia nigra reticulata (SNr) transmit information about basal ganglia output to dozens of brain regions in thalamocortical and brainstem motor networks. Activity of SNr neurons is regulated by convergent input from upstream basal ganglia nuclei, including GABAergic inputs from the striatum and the external globus pallidus (GPe). GABAergic inputs from the striatum convey information from the direct pathway, while GABAergic inputs from the GPe convey information from the indirect pathway. Chronic loss of dopamine, as occurs in Parkinson's disease, disrupts the balance of direct and indirect pathway neurons at the level of the striatum, but the question of how dopamine loss affects information propagation along these pathways outside of the striatum is less well understood. Using a combination of in vivo and slice electrophysiology, we find that dopamine depletion selectively weakens the direct pathway's influence over neural activity in the SNr due to changes in the decay kinetics of GABA-mediated synaptic currents. GABAergic signaling from GPe neurons in the indirect pathway was not affected, resulting in an inversion of the normal balance of inhibitory control over basal ganglia output through the SNr. These results highlight the contribution of cellular mechanisms outside of the striatum that impact the responses of basal ganglia output neurons to the direct and indirect pathways in disease.
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Affiliation(s)
- Asier Aristieta
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA 15213, USA
| | - John E Parker
- Department of Mathematics, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Ya Emma Gao
- Neuroscience Institute, Carnegie Mellon University, Pittsburgh, PA 15213, USA
| | - Jonathan E Rubin
- Department of Mathematics, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Aryn H Gittis
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA 15213, USA; Neuroscience Institute, Carnegie Mellon University, Pittsburgh, PA 15213, USA.
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3
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Amo R, Uchida N, Watabe-Uchida M. Glutamate inputs send prediction error of reward, but not negative value of aversive stimuli, to dopamine neurons. Neuron 2024; 112:1001-1019.e6. [PMID: 38278147 PMCID: PMC10957320 DOI: 10.1016/j.neuron.2023.12.019] [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: 03/26/2023] [Revised: 11/10/2023] [Accepted: 12/21/2023] [Indexed: 01/28/2024]
Abstract
Midbrain dopamine neurons are thought to signal reward prediction errors (RPEs), but the mechanisms underlying RPE computation, particularly the contributions of different neurotransmitters, remain poorly understood. Here, we used a genetically encoded glutamate sensor to examine the pattern of glutamate inputs to dopamine neurons in mice. We found that glutamate inputs exhibit virtually all of the characteristics of RPE rather than conveying a specific component of RPE computation, such as reward or expectation. Notably, whereas glutamate inputs were transiently inhibited by reward omission, they were excited by aversive stimuli. Opioid analgesics altered dopamine negative responses to aversive stimuli into more positive responses, whereas excitatory responses of glutamate inputs remained unchanged. Our findings uncover previously unknown synaptic mechanisms underlying RPE computations; dopamine responses are shaped by both synergistic and competitive interactions between glutamatergic and GABAergic inputs to dopamine neurons depending on valences, with competitive interactions playing a role in responses to aversive stimuli.
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Affiliation(s)
- Ryunosuke Amo
- Department of Molecular and Cellular Biology, Center for Brain Science, Harvard University, Cambridge, MA 02138, USA
| | - Naoshige Uchida
- Department of Molecular and Cellular Biology, Center for Brain Science, Harvard University, Cambridge, MA 02138, USA
| | - Mitsuko Watabe-Uchida
- Department of Molecular and Cellular Biology, Center for Brain Science, Harvard University, Cambridge, MA 02138, USA.
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4
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Sotoyama H. Putative neural mechanisms underlying release-mode-specific abnormalities in dopamine neural activity in a schizophrenia-like model: The distinct roles of glutamate and serotonin in the impaired regulation of dopamine neurons. Eur J Neurosci 2024; 59:1194-1212. [PMID: 37611917 DOI: 10.1111/ejn.16123] [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: 05/18/2023] [Revised: 08/01/2023] [Accepted: 08/02/2023] [Indexed: 08/25/2023]
Abstract
Abnormalities in dopamine function might be related to psychiatric disorders such as schizophrenia. Even at the same concentration, dopamine exerts opposite effects on information processing in the prefrontal cortex depending on independent dopamine release modes known as tonic and phasic releases. This duality of dopamine prevents a blanket interpretation of the implications of dopamine abnormalities for diseases on the basis of absolute dopamine levels. Moreover, the mechanisms underlying the mode-specific dopamine abnormalities are not clearly understood. Here, I show that the two modes of dopamine release in the prefrontal cortex of a schizophrenia-like model are disrupted by different mechanisms. In the schizophrenia-like model established by perinatal exposure to inflammatory cytokine, epidermal growth factor, tonic release was enhanced and phasic release was decreased in the prefrontal cortex. I examined the activity of dopamine neurons in the ventral tegmental area (VTA), which sends dopamine projections to the prefrontal cortex, under anaesthesia. The activation of VTA dopamine neurons during excitatory stimulation (local application of glutamate or N-methyl-d-aspartic acid [NMDA]), which is associated with phasic activity, was blunt in this model. Dopaminergic neuronal activity in the resting state related to tonic release was increased by disinhibition of the dopamine neurons due to the impairment of 5HT2 (5HT2A) receptor-regulated GABAergic inputs. Moreover, chronic administration of risperidone ameliorated this disinhibition of dopaminergic neurons. These results provide an idea about the mechanism of dopamine disturbance in schizophrenia and may be informative in explaining the effects of atypical antipsychotics as distinct from those of typical drugs.
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Affiliation(s)
- Hidekazu Sotoyama
- Department of Physiology, School of Medicine, Niigata University, Niigata, Japan
- Department of Molecular Neurobiology, Brain Research Institute, Niigata University, Niigata, Japan
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5
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Amo R. Prediction error in dopamine neurons during associative learning. Neurosci Res 2024; 199:12-20. [PMID: 37451506 DOI: 10.1016/j.neures.2023.07.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Revised: 06/18/2023] [Accepted: 07/07/2023] [Indexed: 07/18/2023]
Abstract
Dopamine neurons have long been thought to facilitate learning by broadcasting reward prediction error (RPE), a teaching signal used in machine learning, but more recent work has advanced alternative models of dopamine's computational role. Here, I revisit this critical issue and review new experimental evidences that tighten the link between dopamine activity and RPE. First, I introduce the recent observation of a gradual backward shift of dopamine activity that had eluded researchers for over a decade. I also discuss several other findings, such as dopamine ramping, that were initially interpreted to conflict but later found to be consistent with RPE. These findings improve our understanding of neural computation in dopamine neurons.
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Affiliation(s)
- Ryunosuke Amo
- Department of Molecular and Cellular Biology, Center for Brain Science, Harvard University, Cambridge, MA 02138, USA.
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6
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Singh S, Hämäläinen RH. The Roles of Cystatin B in the Brain and Pathophysiological Mechanisms of Progressive Myoclonic Epilepsy Type 1. Cells 2024; 13:170. [PMID: 38247861 PMCID: PMC10814315 DOI: 10.3390/cells13020170] [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: 12/07/2023] [Revised: 01/03/2024] [Accepted: 01/15/2024] [Indexed: 01/23/2024] Open
Abstract
Progressive myoclonic epilepsy type 1 (EPM1) is an autosomal recessive disorder, also known as Unverricht-Lundborg disease (ULD). EPM1 patients suffer from photo-sensitive seizures, stimulus-sensitive myoclonus, nocturnal myoclonic seizures, ataxia and dysarthria. In addition, cerebral ataxia and impaired GABAergic inhibition are typically present. EPM1 is caused by mutations in the Cystatin B gene (CSTB). The CSTB protein functions as an intracellular thiol protease inhibitor and inhibits Cathepsin function. It also plays a crucial role in brain development and regulates various functions in neurons beyond maintaining cellular proteostasis. These include controlling cell proliferation and differentiation, synaptic functions and protection against oxidative stress, likely through regulation of mitochondrial function. Depending on the differentiation stage and status of neurons, the protein localizes either to the cytoplasm, nucleus, lysosomes or mitochondria. Further, CSTB can also be secreted to the extracellular matrix for interneuron rearrangement and migration. In this review, we will review the various functions of CSTB in the brain and discuss the putative pathophysiological mechanism underlying EPM1.
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Affiliation(s)
| | - Riikka H. Hämäläinen
- A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Neulaniementie 2, 70211 Kuopio, Finland;
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7
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Amo R, Uchida N, Watabe-Uchida M. Glutamate inputs send prediction error of reward but not negative value of aversive stimuli to dopamine neurons. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.09.566472. [PMID: 37986868 PMCID: PMC10659341 DOI: 10.1101/2023.11.09.566472] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2023]
Abstract
Midbrain dopamine neurons are thought to signal reward prediction errors (RPEs) but the mechanisms underlying RPE computation, particularly contributions of different neurotransmitters, remain poorly understood. Here we used a genetically-encoded glutamate sensor to examine the pattern of glutamate inputs to dopamine neurons. We found that glutamate inputs exhibit virtually all of the characteristics of RPE, rather than conveying a specific component of RPE computation such as reward or expectation. Notably, while glutamate inputs were transiently inhibited by reward omission, they were excited by aversive stimuli. Opioid analgesics altered dopamine negative responses to aversive stimuli toward more positive responses, while excitatory responses of glutamate inputs remained unchanged. Our findings uncover previously unknown synaptic mechanisms underlying RPE computations; dopamine responses are shaped by both synergistic and competitive interactions between glutamatergic and GABAergic inputs to dopamine neurons depending on valences, with competitive interactions playing a role in responses to aversive stimuli.
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Affiliation(s)
- Ryunosuke Amo
- Department of Molecular and Cellular Biology, Center for Brain Science, Harvard University, Cambridge, MA 02138, USA
| | - Naoshige Uchida
- Department of Molecular and Cellular Biology, Center for Brain Science, Harvard University, Cambridge, MA 02138, USA
| | - Mitsuko Watabe-Uchida
- Department of Molecular and Cellular Biology, Center for Brain Science, Harvard University, Cambridge, MA 02138, USA
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8
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Ayala-Rodríguez JD, García-Colunga J. Maternal separation modifies spontaneous synaptic activity in the infralimbic cortex of stress-resilient male rats. PLoS One 2023; 18:e0294151. [PMID: 37943747 PMCID: PMC10635473 DOI: 10.1371/journal.pone.0294151] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Accepted: 10/25/2023] [Indexed: 11/12/2023] Open
Abstract
Glutamate and GABA signaling systems are necessary to maintain proper function of the central nervous system through excitation/inhibition (E/I) balance. Alteration of this balance in the medial prefrontal cortex (mPFC), as an effect of early-life stress, may lead to the development of anxiety and depressive disorders. Few studies exist in the infralimbic division of the mPFC to understand the effect of early-life stress at different ages, which is the purpose of the present work. Newborn Sprague Dawley male rats were subjected to maternal separation (MS) for two weeks. First, tests measuring anxiety- and depression-like behaviors were performed on adolescent and adult rats subjected to MS (MS-rats). Then, to establish a relationship with behavioral results, electrophysiological recordings were performed in neurons of the infralimbic cortex in acute brain slices of infant, adolescent, and adult rats. In the behavioral tests, there were no significant differences in MS-rats compared to control rats at any age. Moreover, MS had no effect on the passive membrane properties nor neuronal excitability in the infralimbic cortex, whereas spontaneous synaptic activity in infralimbic neurons was altered. The frequency of spontaneous glutamatergic synaptic events increased in infant MS-rats, whereas in adolescent MS-rats both the frequency and the amplitude of spontaneous GABAergic events increased without any effect on glutamatergic synaptic responses. In adult MS-rats, these two parameters decreased in spontaneous GABAergic synaptic events, whereas only the frequency of glutamatergic events decreased. These data suggest that rats subjected to MS did not exhibit behavioral changes and presented an age-dependent E/I imbalance in the infralimbic cortex, possibly due to differential changes in neurotransmitter release and/or receptor expression.
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Affiliation(s)
- Jesús David Ayala-Rodríguez
- Departamento de Neurobiología Celular y Molecular, Instituto de Neurobiología, Universidad Nacional Autónoma de México, Juriquilla, Querétaro, México
| | - Jesús García-Colunga
- Departamento de Neurobiología Celular y Molecular, Instituto de Neurobiología, Universidad Nacional Autónoma de México, Juriquilla, Querétaro, México
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9
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Stetsenko A, Koos T. Neuronal implementation of the temporal difference learning algorithm in the midbrain dopaminergic system. Proc Natl Acad Sci U S A 2023; 120:e2309015120. [PMID: 37903252 PMCID: PMC10636325 DOI: 10.1073/pnas.2309015120] [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: 05/29/2023] [Accepted: 09/29/2023] [Indexed: 11/01/2023] Open
Abstract
The temporal difference learning (TDL) algorithm has been essential to conceptualizing the role of dopamine in reinforcement learning (RL). Despite its theoretical importance, it remains unknown whether a neuronal implementation of this algorithm exists in the brain. Here, we provide an interpretation of the recently described signaling properties of ventral tegmental area (VTA) GABAergic neurons and show that a circuitry of these neurons implements the TDL algorithm. Specifically, we identified the neuronal mechanism of three key components of the TDL model: a sustained state value signal encoded by an afferent input to the VTA, a temporal differentiation circuit formed by two types of VTA GABAergic neurons the combined output of which computes momentary reward prediction (RP) as the derivative of the state value, and the computation of reward prediction errors (RPEs) in dopamine neurons utilizing the output of the differentiation circuit. Using computational methods, we also show that this mechanism is optimally adapted to the biophysics of RPE signaling in dopamine neurons, mechanistically links the emergence of conditioned reinforcement to RP, and can naturally account for the temporal discounting of reinforcement. Elucidating the implementation of the TDL algorithm may further the investigation of RL in biological and artificial systems.
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Affiliation(s)
- Anya Stetsenko
- Center for Molecular and Behavioral Neuroscience, Rutgers University, Newark, NJ07102
| | - Tibor Koos
- Center for Molecular and Behavioral Neuroscience, Rutgers University, Newark, NJ07102
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10
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Devoght J, Comhair J, Morelli G, Rigo JM, D'Hooge R, Touma C, Palme R, Dewachter I, vandeVen M, Harvey RJ, Schiffmann SN, Piccart E, Brône B. Dopamine-mediated striatal activity and function is enhanced in GlyRα2 knockout animals. iScience 2023; 26:107400. [PMID: 37554441 PMCID: PMC10404725 DOI: 10.1016/j.isci.2023.107400] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Revised: 04/27/2023] [Accepted: 07/12/2023] [Indexed: 08/10/2023] Open
Abstract
The glycine receptor alpha 2 (GlyRα2) is a ligand-gated ion channel which upon activation induces a chloride conductance. Here, we investigated the role of GlyRα2 in dopamine-stimulated striatal cell activity and behavior. We show that depletion of GlyRα2 enhances dopamine-induced increases in the activity of putative dopamine D1 receptor-expressing striatal projection neurons, but does not alter midbrain dopamine neuron activity. We next show that the locomotor response to d-amphetamine is enhanced in GlyRα2 knockout animals, and that this increase correlates with c-fos expression in the dorsal striatum. 3-D modeling revealed an increase in the neuronal ensemble size in the striatum in response to D-amphetamine in GlyRα2 KO mice. Finally, we show enhanced appetitive conditioning in GlyRα2 KO animals that is likely due to increased motivation, but not changes in associative learning or hedonic response. Taken together, we show that GlyRα2 is an important regulator of dopamine-stimulated striatal activity and function.
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Affiliation(s)
- Jens Devoght
- Department of Neuroscience, UHasselt, 3500 Hasselt, Belgium
| | - Joris Comhair
- Department of Neuroscience, UHasselt, 3500 Hasselt, Belgium
| | - Giovanni Morelli
- Brain Development and Disease Laboratory, Instituto Italiano di Tecnologia, 16163 Genova, Italy
| | | | - Rudi D'Hooge
- Laboratory for Biological Psychology, University of Leuven, 3000 Leuven, Belgium
| | - Chadi Touma
- Department of Behavioural Biology, University of Osnabrück, 49076 Osnabrück, Germany
| | - Rupert Palme
- Institute of Biochemistry, University of Veterinary Medicine Vienna, Vienna A-1210, Austria
| | - Ilse Dewachter
- Department of Neuroscience, UHasselt, 3500 Hasselt, Belgium
| | | | - Robert J. Harvey
- School of Health, University of the Sunshine Coast, Sippy Downs, QLD, Australia
- Sunshine Coast Health Institute, Birtinya, QLD, Australia
| | - Serge N. Schiffmann
- Laboratory of Neurophysiology, Université libre de Bruxelles, 1070 Brussels, Belgium
| | | | - Bert Brône
- Department of Neuroscience, UHasselt, 3500 Hasselt, Belgium
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11
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Lu C, Zhu X, Feng Y, Ao W, Li J, Gao Z, Luo H, Chen M, Cai F, Zhan S, Li H, Sun W, Hu J. Atypical antipsychotics antagonize GABA A receptors in the ventral tegmental area GABA neurons to relieve psychotic behaviors. Mol Psychiatry 2023; 28:2107-2121. [PMID: 36754983 DOI: 10.1038/s41380-023-01982-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/31/2021] [Revised: 01/19/2023] [Accepted: 01/24/2023] [Indexed: 02/10/2023]
Abstract
Psychosis is an abnormal mental condition that can cause patients to lose contact with reality. It is a common symptom of schizophrenia, bipolar disorder, sleep deprivation, and other mental disorders. Clinically, antipsychotic medications, such as olanzapine and clozapine, are very effective in treatment for psychosis. To investigate the neural circuit mechanism that is affected by antipsychotics and identify more selective therapeutic targets, we employed a strategy by using these effective antipsychotics to identify antipsychotic neural substrates. We observed that local injection of antipsychotics into the ventral tegmental area (VTA) could reverse the sensorimotor gating defects induced by MK-801 injection in mice. Using in vivo fiber photometry, electrophysiological techniques, and chemogenetics, we found that antipsychotics could activate VTA gamma-aminobutyric acid (GABA) neurons by blocking GABAA receptors. Moreover, we found that the VTAGABA nucleus accumbens (NAc) projection was crucially involved in such antipsychotic effects. In summary, our study identifies a novel therapeutic target for the treatment of psychosis and underscores the utility of a 'bedside-to-bench' approach for identifying neural circuits that influence psychotic disorders.
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Affiliation(s)
- Chen Lu
- School of Life Science and Technology, ShanghaiTech University, 201210, Shanghai, China
- Institute of Neuroscience, State Key Laboratory of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 200031, Shanghai, China
- University of Chinese Academy of Sciences, 100049, Beijing, China
| | - Xiaona Zhu
- School of Life Science and Technology, ShanghaiTech University, 201210, Shanghai, China.
| | - Yifan Feng
- School of Life Science and Technology, ShanghaiTech University, 201210, Shanghai, China
| | - Weizhen Ao
- School of Life Science and Technology, ShanghaiTech University, 201210, Shanghai, China
- iHuman Institute, ShanghaiTech University, 201210, Shanghai, China
| | - Jie Li
- Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, 200030, Shanghai, China
| | - Zilong Gao
- School of Life Sciences, Westlake University, 310024, Hangzhou, China
| | - Huoqing Luo
- School of Life Science and Technology, ShanghaiTech University, 201210, Shanghai, China
| | - Ming Chen
- Institutes of Brain Science, Fudan University, 200032, Shanghai, China
| | - Fang Cai
- School of Life Science and Technology, ShanghaiTech University, 201210, Shanghai, China
| | - Shulu Zhan
- School of Life Science and Technology, ShanghaiTech University, 201210, Shanghai, China
| | - Hongxia Li
- Department of Neurology and Institute of Neurology, Ruijin Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, 200025, Shanghai, China
| | - Wenzhi Sun
- Chinese Institute for Brain Research, 102206, Beijing, China.
- School of Basic Medical Sciences, Capital Medical University, 100069, Beijing, China.
| | - Ji Hu
- School of Life Science and Technology, ShanghaiTech University, 201210, Shanghai, China.
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12
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Kibaly C, Alderete JA, Liu SH, Nasef HS, Law PY, Evans CJ, Cahill CM. Oxycodone in the Opioid Epidemic: High 'Liking', 'Wanting', and Abuse Liability. Cell Mol Neurobiol 2021; 41:899-926. [PMID: 33245509 PMCID: PMC8155122 DOI: 10.1007/s10571-020-01013-y] [Citation(s) in RCA: 46] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Accepted: 11/17/2020] [Indexed: 12/13/2022]
Abstract
It is estimated that nearly a third of people who abuse drugs started with prescription opioid medicines. Approximately, 11.5 million Americans used prescription drugs recreationally in 2016, and in 2018, 46,802 Americans died as the result of an opioid overdose, including prescription opioids, heroin, and illicitly manufactured fentanyl (National Institutes on Drug Abuse (2020) Opioid Overdose Crisis. https://www.drugabuse.gov/drugs-abuse/opioids/opioid-overdose-crisis . Accessed 06 June 2020). Yet physicians will continue to prescribe oral opioids for moderate-to-severe pain in the absence of alternative therapeutics, underscoring the importance in understanding how drug choice can influence detrimental outcomes. One of the opioid prescription medications that led to this crisis is oxycodone, where misuse of this drug has been rampant. Being one of the most highly prescribed opioid medications for treating moderate-to-severe pain as reflected in the skyrocketed increase in retail sales of 866% between 1997 and 2007, oxycodone was initially suggested to be less addictive than morphine. The false-claimed non-addictive formulation of oxycodone, OxyContin, further contributed to the opioid crisis. Abuse was often carried out by crushing the pills for immediate burst release, typically by nasal insufflation, or by liquefying the pills for intravenous injection. Here, we review oxycodone pharmacology and abuse liability as well as present the hypothesis that oxycodone may exhibit a unique pharmacology that contributes to its high likability and abuse susceptibility. We will discuss various mechanisms that likely contribute to the high abuse rate of oxycodone including clinical drug likability, pharmacokinetics, pharmacodynamics, differences in its actions within mesolimbic reward circuity compared to other opioids, and the possibility of differential molecular and cellular receptor interactions that contribute to its selective effects. We will also discuss marketing strategies and drug difference that likely contributes to the oxycodone opioid use disorders and addiction.
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Affiliation(s)
- Cherkaouia Kibaly
- Department of Psychiatry and Biobehavioral Sciences, Jane & Terry Semel Institute for Neuroscience and Human Behavior, Shirley and Stefan Hatos Center for Neuropharmacology, University of California, Los Angeles, CA, USA.
| | - Jacob A Alderete
- Department of Psychiatry and Biobehavioral Sciences, Jane & Terry Semel Institute for Neuroscience and Human Behavior, Shirley and Stefan Hatos Center for Neuropharmacology, University of California, Los Angeles, CA, USA
| | - Steven H Liu
- Department of Psychiatry and Biobehavioral Sciences, Jane & Terry Semel Institute for Neuroscience and Human Behavior, Shirley and Stefan Hatos Center for Neuropharmacology, University of California, Los Angeles, CA, USA
| | - Hazem S Nasef
- Department of Psychiatry and Biobehavioral Sciences, Jane & Terry Semel Institute for Neuroscience and Human Behavior, Shirley and Stefan Hatos Center for Neuropharmacology, University of California, Los Angeles, CA, USA
| | - Ping-Yee Law
- Department of Psychiatry and Biobehavioral Sciences, Jane & Terry Semel Institute for Neuroscience and Human Behavior, Shirley and Stefan Hatos Center for Neuropharmacology, University of California, Los Angeles, CA, USA
| | - Christopher J Evans
- Department of Psychiatry and Biobehavioral Sciences, Jane & Terry Semel Institute for Neuroscience and Human Behavior, Shirley and Stefan Hatos Center for Neuropharmacology, University of California, Los Angeles, CA, USA
| | - Catherine M Cahill
- Department of Psychiatry and Biobehavioral Sciences, Jane & Terry Semel Institute for Neuroscience and Human Behavior, Shirley and Stefan Hatos Center for Neuropharmacology, University of California, Los Angeles, CA, USA.
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13
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Neurochemical Signaling of Reward and Aversion to Ventral Tegmental Area Glutamate Neurons. J Neurosci 2021; 41:5471-5486. [PMID: 34001626 DOI: 10.1523/jneurosci.1419-20.2021] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Revised: 04/29/2021] [Accepted: 05/05/2021] [Indexed: 12/21/2022] Open
Abstract
Ventral tegmental area (VTA) glutamate neurons signal and participate in reward and aversion-based behaviors. However, the neurochemical mechanisms that underlie how these neurons contribute to motivated behaviors is unknown. We used a combination of optical sensors to identify how distinct neurochemical inputs to VTA glutamate neurons participate in motivated behavior within female and male transgenic mice. Activity of glutamate inputs to VTA glutamate neurons increased for both reward-predicting and aversion-predicting cues and aversive outcomes, but subpopulations of glutamate inputs were increased or decreased by reward. For both reward and aversion-based cues and outcomes, activity of GABA inputs to VTA glutamate neurons mostly decreased. GCaMP recordings showed overall population increases in VTA glutamate neuron intracellular calcium during reward and aversion-based cues and outcomes. Electrophysiological recordings of VTA VGluT2 neurons showed that glutamate receptor activation increases firing while loss of excitation via glutamate receptor blockade decreases firing. GABA-A receptor activation decreased VTA glutamate neuron firing but GABA-A receptor blockade did not significantly change VTA glutamate neuron firing. Electrophysiological recordings in coordination with our sensor data suggest that glutamate inputs strongly regulate VTA glutamate neuron participation in diverse motivated behaviors.SIGNIFICANCE STATEMENT Glutamate and GABA are the primary excitatory and inhibitory neurotransmitters of the nervous system. However, identifying how these neurotransmitters regulate motivated behavior has remained challenging because of a lack of tools (1) capable of measuring neurotransmission at the temporal scale of motivated behaviors and (2) capable of capturing chemical signaling onto genetically-distinct neuronal populations. We have overcome these obstacles by implementing genetically-encoded fluorescent indicators to monitor both glutamate and GABA input dynamics exclusively to ventral tegmental area (VTA) glutamate neurons during reward and aversion-based behaviors. We identify that glutamate and GABA inputs to VTA glutamate neurons differentially and dynamically signal reward and aversion-based cues and outcomes. This research provides foundational evidence that links distinct neurotransmitters to motivated behaviors regulated by VTA glutamate neurons.
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Wills L, Kenny PJ. Addiction-related neuroadaptations following chronic nicotine exposure. J Neurochem 2021; 157:1652-1673. [PMID: 33742685 DOI: 10.1111/jnc.15356] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Revised: 03/14/2021] [Accepted: 03/15/2021] [Indexed: 12/16/2022]
Abstract
The addiction-relevant molecular, cellular, and behavioral actions of nicotine are derived from its stimulatory effects on neuronal nicotinic acetylcholine receptors (nAChRs) in the central nervous system. nAChRs expressed by dopamine-containing neurons in the ventral midbrain, most notably in the ventral tegmental area (VTA), contribute to the reward-enhancing properties of nicotine that motivate the use of tobacco products. nAChRs are also expressed by neurons in brain circuits that regulate aversion. In particular, nAChRs expressed by neurons in the medial habenula (mHb) and the interpeduncular nucleus (IPn) to which the mHb almost exclusively projects regulate the "set-point" for nicotine aversion and control nicotine intake. Different nAChR subtypes are expressed in brain reward and aversion circuits and nicotine intake is titrated to maximally engage reward-enhancing nAChRs while minimizing the recruitment of aversion-promoting nAChRs. With repeated exposure to nicotine, reward- and aversion-related nAChRs and the brain circuits in which they are expressed undergo adaptations that influence whether tobacco use will transition from occasional to habitual. Genetic variation that influences the sensitivity of addiction-relevant brain circuits to the actions of nicotine also influence the propensity to develop habitual tobacco use. Here, we review some of the key advances in our understanding of the mechanisms by which nicotine acts on brain reward and aversion circuits and the adaptations that occur in these circuits that may drive addiction to nicotine-containing tobacco products.
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Affiliation(s)
- Lauren Wills
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY, USA
| | - Paul J Kenny
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY, USA
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15
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Lan Z, Zhang W, Xu J, Lu W. GABA A receptor-mediated inhibition of Dahlgren cells electrical activity in the olive flounder, Paralichthys olivaceus. Gen Comp Endocrinol 2021; 306:113753. [PMID: 33711316 DOI: 10.1016/j.ygcen.2021.113753] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/23/2020] [Revised: 02/10/2021] [Accepted: 02/28/2021] [Indexed: 11/24/2022]
Abstract
γ-Aminobutyric acid (GABA) is a major inhibitory neurotransmitter in the central nervous system. We investigated its potential role as a neurotransmitter in the neuroendocrine Dahlgren cell population of the caudal neurosecretory system (CNSS) of the flounder Paralichthys olivaceus. The application of GABA in vitro resulted in a decrease in electrical activity of Dahlgren cells, followed by an increase of the number of silent cells, together with a decreased firing frequency of all three activity patterns (tonic, phasic, bursting). GABAA receptor agonist etomidate decreased Dahlgren cell firing activity, in a similar way to GABA. The response to GABA was blocked by the GABAA receptor antagonist bicuculline. GABAA receptor gamma2 subunit (Gabrg2) and chloride channel (Clcn2) mRNA expression were significantly upregulated in the CNSS after GABA superfusion. These data suggest that GABA may modulate CNSS activity in vivo mediated by GABAA receptors.
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Affiliation(s)
- Zhaohui Lan
- National Demonstration Center for Experimental Fisheries Science Education, Shanghai Ocean University, China; Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, Ministry of Education, Shanghai Ocean University, Shanghai 201306, China; International Research Center for Marine Biosciences at Shanghai Ocean University, Ministry of Science and Technology, China
| | - Wei Zhang
- National Demonstration Center for Experimental Fisheries Science Education, Shanghai Ocean University, China; Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, Ministry of Education, Shanghai Ocean University, Shanghai 201306, China; International Research Center for Marine Biosciences at Shanghai Ocean University, Ministry of Science and Technology, China
| | - Jinling Xu
- National Demonstration Center for Experimental Fisheries Science Education, Shanghai Ocean University, China; Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, Ministry of Education, Shanghai Ocean University, Shanghai 201306, China
| | - Weiqun Lu
- National Demonstration Center for Experimental Fisheries Science Education, Shanghai Ocean University, China; Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, Ministry of Education, Shanghai Ocean University, Shanghai 201306, China; International Research Center for Marine Biosciences at Shanghai Ocean University, Ministry of Science and Technology, China.
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16
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Hikima T, Lee CR, Witkovsky P, Chesler J, Ichtchenko K, Rice ME. Activity-dependent somatodendritic dopamine release in the substantia nigra autoinhibits the releasing neuron. Cell Rep 2021; 35:108951. [PMID: 33826884 PMCID: PMC8189326 DOI: 10.1016/j.celrep.2021.108951] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Revised: 11/20/2020] [Accepted: 03/15/2021] [Indexed: 12/12/2022] Open
Abstract
Somatodendritic dopamine (DA) release from midbrain DA neurons activates D2 autoreceptors on these cells to regulate their activity. However, the source of autoregulatory DA remains controversial. Here, we test the hypothesis that D2 autoreceptors on a given DA neuron in the substantia nigra pars compacta (SNc) are activated primarily by DA released from that same cell, rather than from its neighbors. Voltage-clamp recording allows monitoring of evoked D2-receptor-mediated inhibitory currents (D2ICs) in SNc DA neurons as an index of DA release. Single-cell application of antibodies to Na+ channels via the recording pipette decreases spontaneous activity of recorded neurons and attenuates evoked D2ICs; antibodies to SNAP-25, a soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) protein, also decrease D2IC amplitude. Evoked D2ICs are nearly abolished by the light chain of botulinum neurotoxin A, which cleaves SNAP-25, whereas synaptically activated GABAB-receptor-mediated currents are unaffected. Thus, somatodendritic DA release in the SNc autoinhibits the neuron that releases it.
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Affiliation(s)
- Takuya Hikima
- Department of Neurosurgery, New York University Grossman School of Medicine, New York, NY 10016, USA
| | - Christian R Lee
- Department of Neurosurgery, New York University Grossman School of Medicine, New York, NY 10016, USA
| | - Paul Witkovsky
- Department of Neurosurgery, New York University Grossman School of Medicine, New York, NY 10016, USA
| | - Julia Chesler
- Department of Neurosurgery, New York University Grossman School of Medicine, New York, NY 10016, USA
| | - Konstantin Ichtchenko
- Department of Biochemistry & Molecular Pharmacology, New York University Grossman School of Medicine, New York, NY 10016, USA
| | - Margaret E Rice
- Department of Neurosurgery, New York University Grossman School of Medicine, New York, NY 10016, USA; Department of Neuroscience & Physiology, New York University Grossman School of Medicine, New York, NY 10016, USA.
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17
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Sallam NA, Borgland SL. Insulin and endocannabinoids in the mesolimbic system. J Neuroendocrinol 2021; 33:e12965. [PMID: 33856071 DOI: 10.1111/jne.12965] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Revised: 02/19/2021] [Accepted: 03/08/2021] [Indexed: 12/31/2022]
Abstract
Easy access to palatable food and an abundance of food-related cues exacerbate non-homeostatic feeding. The metabolic and economical sequelae of non-homeostatic feeding outweigh those of homeostatic feeding and contribute significantly to the global obesity pandemic. The mesolimbic dopamine system is the primary central circuit that governs the motivation to consume food. Insulin and endocannabinoids (eCBs) are two major, presumably opposing, players in regulating homeostatic and non-homeostatic feeding centrally and peripherally. Insulin is generally regarded as a postprandial satiety signal, whereas eCBs mainly function as pre-prandial orexinergic signals. In this review, we discuss the effects of insulin and eCB-mediated actions within the mesolimbic pathways. We propose that insulin and eCBs have regional- and time course-dependent roles. We discuss their mechanisms of actions in the ventral tegmental area and nucleus accumbens, as well as how their mechanisms converge to finely tune dopaminergic activity and food intake.
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Affiliation(s)
- Nada A Sallam
- Department of Pharmacology and Toxicology, Faculty of Pharmacy, Cairo University, Cairo, Egypt
- Department of Physiology and Pharmacology, University of Calgary, Calgary, AB, Canada
| | - Stephanie L Borgland
- Department of Physiology and Pharmacology, University of Calgary, Calgary, AB, Canada
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18
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Hurel I, Muguruza C, Redon B, Marsicano G, Chaouloff F. Cannabis and exercise: Effects of Δ 9-tetrahydrocannabinol on preference and motivation for wheel-running in mice. Prog Neuropsychopharmacol Biol Psychiatry 2021; 105:110117. [PMID: 32971218 DOI: 10.1016/j.pnpbp.2020.110117] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Revised: 09/11/2020] [Accepted: 09/20/2020] [Indexed: 11/27/2022]
Abstract
Recent surveys have revealed close links between cannabis and exercise. Specifically, cannabis usage before and/or after exercise is an increasingly common habit primarily aimed at boosting exercise pleasure, motivation, and performance whilst facilitating post-exercise recovery. However, whether these beliefs reflect the true impact of cannabis on these aspects of exercise is unknown. This study has thus examined the effects of cannabis' main psychoactive ingredient, namely Δ9-tetrahydrocannabinol (THC), on (i) mouse wheel-running preference and performance and (ii) running motivation and seeking behaviour. Wheel-running preference and performance were investigated using a T-maze with free and locked wheels located at the extremity of either arm. Running motivation and seeking were assessed by a cued-running operant task wherein wheel-running was conditioned by nose poking. Moreover, because THC targets cannabinoid type 1 (CB1) receptors, i.e. receptors previously documented to control running motivation, this study also assessed the role of these receptors in running preference, performance, and craving-like behaviour. Whilst acute blockade or genetic deletion of CB1 receptors decreased running preference and performance in the T-maze, THC proved ineffective on either variable. The failure of THC to affect running variables in the T-maze extended to running motivation, as assessed by cued-running under a progressive ratio (PR) reinforcement schedule. This ineffectiveness of THC was not related to the treatment protocol because it successfully increased motivation for palatable food. Although craving-like behaviour, as indexed by a cue-induced reinstatement of running seeking, was found to depend on CB1 receptors, THC again proved ineffective. Neither running motivation nor running seeking were affected when CB1 receptors were further stimulated by increasing the levels of the endocannabinoid 2-arachidonoylglycerol. These results, which suggest that the drive for running is insensitive to the acute stimulation of CB1 receptors, raise the hypothesis that cannabis is devoid of effect on exercise motivation. Future investigation using chronic administration of THC, with and without other cannabis ingredients (e.g. cannabidiol), is however required before conclusions can be drawn.
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Affiliation(s)
- Imane Hurel
- Endocannabinoids and NeuroAdaptation, NeuroCentre INSERM U1215, 33077 Bordeaux, France; Université de Bordeaux, 33077 Bordeaux, France
| | - Carolina Muguruza
- Endocannabinoids and NeuroAdaptation, NeuroCentre INSERM U1215, 33077 Bordeaux, France; Université de Bordeaux, 33077 Bordeaux, France; Department of Pharmacology, University of the Basque Country UPV/EHU, Leioa, Bizkaia, Spain; Centro de Investigación Biomédica en Red de Salud Mental, CIBERSAM, Spain
| | - Bastien Redon
- Endocannabinoids and NeuroAdaptation, NeuroCentre INSERM U1215, 33077 Bordeaux, France; Université de Bordeaux, 33077 Bordeaux, France
| | - Giovanni Marsicano
- Endocannabinoids and NeuroAdaptation, NeuroCentre INSERM U1215, 33077 Bordeaux, France; Université de Bordeaux, 33077 Bordeaux, France
| | - Francis Chaouloff
- Endocannabinoids and NeuroAdaptation, NeuroCentre INSERM U1215, 33077 Bordeaux, France; Université de Bordeaux, 33077 Bordeaux, France.
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19
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Tossell K, Dodhia RA, Galet B, Tkachuk O, Ungless MA. Tonic GABAergic inhibition, via GABA A receptors containing αβƐ subunits, regulates excitability of ventral tegmental area dopamine neurons. Eur J Neurosci 2021; 53:1722-1737. [PMID: 33522050 PMCID: PMC8651010 DOI: 10.1111/ejn.15133] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2019] [Revised: 12/15/2020] [Accepted: 01/18/2021] [Indexed: 12/13/2022]
Abstract
The activity of midbrain dopamine neurons is strongly regulated by fast synaptic inhibitory γ‐Aminobutyric acid (GABA)ergic inputs. There is growing evidence in other brain regions that low concentrations of ambient GABA can persistently activate certain subtypes of GABAA receptor to generate a tonic current. However, evidence for a tonic GABAergic current in midbrain dopamine neurons is limited. To address this, we conducted whole‐cell recordings from ventral tegmental area (VTA) dopamine neurons in brain slices from mice. We found that application of GABAA receptor antagonists decreased the holding current, indicating the presence of a tonic GABAergic input. Global increases in GABA release, induced by either a nitric oxide donor or inhibition of GABA uptake, further increased this tonic current. Importantly, prolonged inhibition of the firing activity of local GABAergic neurons abolished the tonic current. A combination of pharmacology and immunohistochemistry experiments suggested that, unlike common examples of tonic inhibition, this current may be mediated by a relatively unusual combination of α4βƐ subunits. Lastly, we found that the tonic current reduced excitability in dopamine neurons suggesting a subtractive effect on firing activity.
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Affiliation(s)
- Kyoko Tossell
- MRC London Institute of Medical Sciences (LMS), London, UK.,Institute of Clinical Sciences (ICS), Faculty of Medicine, Imperial College London, London, UK
| | - Rakesh A Dodhia
- MRC London Institute of Medical Sciences (LMS), London, UK.,Institute of Clinical Sciences (ICS), Faculty of Medicine, Imperial College London, London, UK
| | - Benjamin Galet
- MRC London Institute of Medical Sciences (LMS), London, UK.,Institute of Clinical Sciences (ICS), Faculty of Medicine, Imperial College London, London, UK
| | - Olga Tkachuk
- MRC London Institute of Medical Sciences (LMS), London, UK.,Institute of Clinical Sciences (ICS), Faculty of Medicine, Imperial College London, London, UK
| | - Mark A Ungless
- MRC London Institute of Medical Sciences (LMS), London, UK.,Institute of Clinical Sciences (ICS), Faculty of Medicine, Imperial College London, London, UK
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20
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Arencibia‐Albite F, Jiménez‐Rivera CA. Computational and theoretical insights into the homeostatic response to the decreased cell size of midbrain dopamine neurons. Physiol Rep 2021; 9:e14709. [PMID: 33484235 PMCID: PMC7824968 DOI: 10.14814/phy2.14709] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Revised: 11/16/2020] [Accepted: 12/14/2020] [Indexed: 11/24/2022] Open
Abstract
Midbrain dopamine neurons communicate signals of reward anticipation and attribution of salience. This capacity is distorted in heroin or cocaine abuse or in conditions such as human mania. A shared characteristic among rodent models of these behavioral disorders is that dopamine neurons in these animals acquired a small size and manifest an augmented spontaneous and burst activity. The biophysical mechanism underlying this increased excitation is currently unknown, but is believed to primarily follow from a substantial drop in K+ conductance secondary to morphology reduction. This work uses a dopamine neuron mathematical model to show, surprisingly, that under size diminution a reduction in K+ conductance is an adaptation that attempts to decrease cell excitability. The homeostatic response that preserves the intrinsic activity is the conservation of the ion channel density for each conductance; a result that is analytically demonstrated and challenges the experimentalist tendency to reduce intrinsic excitation to K+ conductance expression level. Another unexpected mechanism that buffers the raise in intrinsic activity is the presence of the ether-a-go-go-related gen K+ channel since its activation is illustrated to increase with size reduction. Computational experiments finally demonstrate that size attenuation results in the paradoxical enhancement of afferent-driven bursting as a reduced temporal summation indexed correlates with improved depolarization. This work illustrates, on the whole, that experimentation in the absence of mathematical models may lead to the erroneous interpretation of the counterintuitive aspects of empirical data.
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Affiliation(s)
- Francisco Arencibia‐Albite
- Department of PhysiologyUniversity of Puerto RicoSan JuanPuerto Rico
- Department of Natural SciencesUniversity of Sacred HeartSan JuanPuerto Rico
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21
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Otomo K, Perkins J, Kulkarni A, Stojanovic S, Roeper J, Paladini CA. In vivo patch-clamp recordings reveal distinct subthreshold signatures and threshold dynamics of midbrain dopamine neurons. Nat Commun 2020; 11:6286. [PMID: 33293613 PMCID: PMC7722714 DOI: 10.1038/s41467-020-20041-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Accepted: 11/06/2020] [Indexed: 01/19/2023] Open
Abstract
The in vivo firing patterns of ventral midbrain dopamine neurons are controlled by afferent and intrinsic activity to generate sensory cue and prediction error signals that are essential for reward-based learning. Given the absence of in vivo intracellular recordings during the last three decades, the subthreshold membrane potential events that cause changes in dopamine neuron firing patterns remain unknown. To address this, we established in vivo whole-cell recordings and obtained over 100 spontaneously active, immunocytochemically-defined midbrain dopamine neurons in isoflurane-anaesthetized adult mice. We identified a repertoire of subthreshold membrane potential signatures associated with distinct in vivo firing patterns. Dopamine neuron activity in vivo deviated from single-spike pacemaking by phasic increases in firing rate via two qualitatively distinct biophysical mechanisms: 1) a prolonged hyperpolarization preceding rebound bursts, accompanied by a hyperpolarizing shift in action potential threshold; and 2) a transient depolarization leading to high-frequency plateau bursts, associated with a depolarizing shift in action potential threshold. Our findings define a mechanistic framework for the biophysical implementation of dopamine neuron firing patterns in the intact brain.
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Affiliation(s)
- Kanako Otomo
- Institute of Neurophysiology, Neuroscience Center, Goethe University, Frankfurt, Germany
| | - Jessica Perkins
- University of Texas at San Antonio Neurosciences Institute, San Antonio, USA
| | - Anand Kulkarni
- University of Texas at San Antonio Neurosciences Institute, San Antonio, USA
| | - Strahinja Stojanovic
- Institute of Neurophysiology, Neuroscience Center, Goethe University, Frankfurt, Germany
| | - Jochen Roeper
- Institute of Neurophysiology, Neuroscience Center, Goethe University, Frankfurt, Germany.
| | - Carlos A Paladini
- University of Texas at San Antonio Neurosciences Institute, San Antonio, USA.
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22
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Perez DM. α 1-Adrenergic Receptors in Neurotransmission, Synaptic Plasticity, and Cognition. Front Pharmacol 2020; 11:581098. [PMID: 33117176 PMCID: PMC7553051 DOI: 10.3389/fphar.2020.581098] [Citation(s) in RCA: 53] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Accepted: 09/11/2020] [Indexed: 12/14/2022] Open
Abstract
α1-adrenergic receptors are G-Protein Coupled Receptors that are involved in neurotransmission and regulate the sympathetic nervous system through binding and activating the neurotransmitter, norepinephrine, and the neurohormone, epinephrine. There are three α1-adrenergic receptor subtypes (α1A, α1B, α1D) that are known to play various roles in neurotransmission and cognition. They are related to two other adrenergic receptor families that also bind norepinephrine and epinephrine, the β- and α2-, each with three subtypes (β1, β2, β3, α2A, α2B, α2C). Previous studies assessing the roles of α1-adrenergic receptors in neurotransmission and cognition have been inconsistent. This was due to the use of poorly-selective ligands and many of these studies were published before the characterization of the cloned receptor subtypes and the subsequent development of animal models. With the availability of more-selective ligands and the development of animal models, a clearer picture of their role in cognition and neurotransmission can be assessed. In this review, we highlight the significant role that the α1-adrenergic receptor plays in regulating synaptic efficacy, both short and long-term synaptic plasticity, and its regulation of different types of memory. We will also present evidence that the α1-adrenergic receptors, and particularly the α1A-adrenergic receptor subtype, are a potentially good target to treat a wide variety of neurological conditions with diminished cognition.
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Affiliation(s)
- Dianne M Perez
- The Lerner Research Institute, The Cleveland Clinic Foundation, Cleveland, OH, United States
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23
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Evans RC, Twedell EL, Zhu M, Ascencio J, Zhang R, Khaliq ZM. Functional Dissection of Basal Ganglia Inhibitory Inputs onto Substantia Nigra Dopaminergic Neurons. Cell Rep 2020; 32:108156. [PMID: 32937133 PMCID: PMC9887718 DOI: 10.1016/j.celrep.2020.108156] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2019] [Revised: 07/11/2020] [Accepted: 08/25/2020] [Indexed: 02/02/2023] Open
Abstract
Substantia nigra (SNc) dopaminergic neurons respond to aversive stimuli with inhibitory pauses in firing followed by transient rebound activation. We tested integration of inhibitory synaptic inputs onto SNc neurons from genetically defined populations in dorsal striatum (striosome and matrix) and external globus pallidus (GPe; parvalbumin- and Lhx6-positive), and examined their contribution to pause-rebound firing. Activation of striosome projections, which target "dendron bouquets" in the pars reticulata (SNr), consistently quiets firing and relief from striosome inhibition triggers rebound activity. Striosomal inhibitory postsynaptic currents (IPSCs) display a prominent GABA-B receptor-mediated component that strengthens the impact of SNr dendrite synapses on somatic excitability and enables rebounding. By contrast, GPe projections activate GABA-A receptors on the soma and proximal dendrites but do not result in rebounding. Lastly, optical mapping shows that dorsal striatum selectively inhibits the ventral population of SNc neurons, which are intrinsically capable of rebounding. Therefore, we define a distinct striatonigral circuit for generating dopamine rebound.
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Affiliation(s)
- Rebekah C. Evans
- Cellular Neurophysiology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA
| | - Emily L. Twedell
- Cellular Neurophysiology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA
| | - Manhua Zhu
- Cellular Neurophysiology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA
| | - Jefferson Ascencio
- Cellular Neurophysiology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA
| | - Renshu Zhang
- Cellular Neurophysiology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA
| | - Zayd M. Khaliq
- Cellular Neurophysiology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA,Lead Contact,Correspondence:
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Distinct Temporal Structure of Nicotinic ACh Receptor Activation Determines Responses of VTA Neurons to Endogenous ACh and Nicotine. eNeuro 2020; 7:ENEURO.0418-19.2020. [PMID: 32737187 PMCID: PMC7470928 DOI: 10.1523/eneuro.0418-19.2020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2019] [Revised: 02/10/2020] [Accepted: 04/18/2020] [Indexed: 11/29/2022] Open
Abstract
The addictive component of tobacco, nicotine, acts via nicotinic acetylcholine receptors (nAChRs). The β2 subunit-containing nAChRs (β2-nAChRs) play a crucial role in the rewarding properties of nicotine and are particularly densely expressed in the mesolimbic dopamine (DA) system. Specifically, nAChRs directly and indirectly affect DA neurons in the ventral tegmental area (VTA). The understanding of ACh and nicotinic regulation of DA neuron activity is incomplete. By computational modeling, we provide mechanisms for several apparently contradictory experimental results. First, systemic knockout of β2-containing nAChRs drastically reduces DA neurons bursting, although the major glutamatergic (Glu) afferents that have been shown to evoke this bursting stay intact. Second, the most intuitive way to rescue this bursting—by re-expressing the nAChRs on VTA DA neurons—fails. Third, nAChR re-expression on VTA GABA neurons rescues bursting in DA neurons and increases their firing rate under the influence of ACh input, whereas nicotinic application results in the opposite changes in firing. Our model shows that, first, without ACh receptors, Glu excitation of VTA DA and GABA neurons remains balanced and GABA inhibition cancels the direct excitation. Second, re-expression of ACh receptors on DA neurons provides an input that impedes membrane repolarization and is ineffective in restoring firing of DA neurons. Third, the distinct responses to ACh and nicotine occur because of distinct temporal patterns of these inputs: pulsatile versus continuous. Altogether, this study highlights how β2-nAChRs influence coactivation of the VTA DA and GABA neurons required for motivation and saliency signals carried by DA neuron activity.
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25
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Gordon-Fennell AG, Will RG, Ramachandra V, Gordon-Fennell L, Dominguez JM, Zahm DS, Marinelli M. The Lateral Preoptic Area: A Novel Regulator of Reward Seeking and Neuronal Activity in the Ventral Tegmental Area. Front Neurosci 2020; 13:1433. [PMID: 32009893 PMCID: PMC6978721 DOI: 10.3389/fnins.2019.01433] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2019] [Accepted: 12/18/2019] [Indexed: 11/22/2022] Open
Abstract
The lateral preoptic area (LPO) is a hypothalamic region whose function has been largely unexplored. Its direct and indirect projections to the ventral tegmental area (VTA) suggest that the LPO could modulate the activity of the VTA and the reward-related behaviors that the VTA underlies. We examined the role of the LPO on reward taking and seeking using operant self-administration of cocaine or sucrose. Rats were trained to self-administer cocaine or sucrose and then subjected to extinction, whereby responding was no longer reinforced. We tested if stimulating the LPO pharmacologically with bicuculline or chemogenetically with Designer Receptors Exclusively Activated by Designer Drugs (DREADDs) modifies self-administration and/or seeking. In another set of experiments, we tested if manipulating the LPO influences cocaine self-administration during and after punishment. To examine the functional connectivity between the LPO and VTA, we used in vivo electrophysiology recordings in anesthetized rats. We tested if stimulating the LPO modifies the activity of GABA and dopamine neurons of the VTA. We found that stimulating the LPO reinstated cocaine and sucrose seeking behavior but had no effect on reward intake. Furthermore, both stimulating and inhibiting the LPO prevented the sustained reduction in cocaine intake seen after punishment. Finally, stimulating the LPO inhibited the activity of VTA GABA neurons while enhancing that of VTA dopamine neurons. These findings indicate that the LPO has the capacity to drive reward seeking, modulate sustained reductions in self-administration following punishment, and regulate the activity of VTA neurons. Taken together, these findings implicate the LPO as a previously overlooked member of the reward circuit.
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Affiliation(s)
- Adam G Gordon-Fennell
- Department of Neuroscience, College of Natural Sciences, The University of Texas at Austin, Austin, TX, United States
| | - Ryan G Will
- Department of Neuroscience, College of Natural Sciences, The University of Texas at Austin, Austin, TX, United States
- Department of Psychology, College of Liberal Arts, The University of Texas at Austin, Austin, TX, United States
| | - Vorani Ramachandra
- Division of Pharmacology and Toxicology, College of Pharmacy, The University of Texas at Austin, Austin, TX, United States
| | - Lydia Gordon-Fennell
- Department of Neuroscience, College of Natural Sciences, The University of Texas at Austin, Austin, TX, United States
| | - Juan M Dominguez
- Department of Psychology, College of Liberal Arts, The University of Texas at Austin, Austin, TX, United States
| | - Daniel S Zahm
- Department of Pharmacology and Physiology, School of Medicine, Saint Louis University, St. Louis, MO, United States
| | - Michela Marinelli
- Department of Neuroscience, College of Natural Sciences, The University of Texas at Austin, Austin, TX, United States
- Division of Pharmacology and Toxicology, College of Pharmacy, The University of Texas at Austin, Austin, TX, United States
- Department of Psychiatry, Dell Medical School, The University of Texas at Austin, Austin, TX, United States
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TGF-β/Smad3 Signalling Modulates GABA Neurotransmission: Implications in Parkinson's Disease. Int J Mol Sci 2020; 21:ijms21020590. [PMID: 31963327 PMCID: PMC7013528 DOI: 10.3390/ijms21020590] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Revised: 01/13/2020] [Accepted: 01/14/2020] [Indexed: 12/12/2022] Open
Abstract
γ-Aminobutiryc acid (GABA) is found extensively in different brain nuclei, including parts involved in Parkinson’s disease (PD), such as the basal ganglia and hippocampus. In PD and in different models of the disorder, an increase in GABA neurotransmission is observed and may promote bradykinesia or L-Dopa-induced side-effects. In addition, proteins involved in GABAA receptor (GABAAR) trafficking, such as GABARAP, Trak1 or PAELR, may participate in the aetiology of the disease. TGF-β/Smad3 signalling has been associated with several pathological features of PD, such as dopaminergic neurodegeneration; reduction of dopaminergic axons and dendrites; and α-synuclein aggregation. Moreover, TGF-β/Smad3 intracellular signalling was recently shown to modulate GABA neurotransmission in the context of parkinsonism and cognitive alterations. This review provides a summary of GABA neurotransmission and TGF-β signalling; their implications in PD; and the regulation of GABA neurotransmission by TGF-β/Smad3. There appear to be new possibilities to develop therapeutic approaches for the treatment of PD using GABA modulators.
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Ventral tegmental area astrocytes orchestrate avoidance and approach behavior. Nat Commun 2019; 10:1455. [PMID: 30926783 PMCID: PMC6440962 DOI: 10.1038/s41467-019-09131-y] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2018] [Accepted: 02/22/2019] [Indexed: 12/28/2022] Open
Abstract
The ventral tegmental area (VTA) is a heterogeneous midbrain structure, containing neurons and astrocytes, that coordinates behaviors by integrating activity from numerous afferents. Within neuron-astrocyte networks, astrocytes control signals from distinct afferents in a circuit-specific manner, but whether this capacity scales up to drive motivated behavior has been undetermined. Using genetic and optical dissection strategies we report that VTA astrocytes tune glutamatergic signaling selectively on local inhibitory neurons to drive a functional circuit for learned avoidance. In this circuit, astrocytes facilitate excitation of VTA GABA neurons to increase inhibition of dopamine neurons, eliciting real-time and learned avoidance behavior that is sufficient to impede expression of preference for reward. Loss of one glutamate transporter (GLT-1) from VTA astrocytes selectively blocks these avoidance behaviors and spares preference for reward. Thus, VTA astrocytes selectively regulate excitation of local GABA neurons to drive a distinct avoidance circuit that opposes approach behavior. Astrocytes can dynamically control glutamate availability at specific active synapses through the glutamate transporter, GLT-1. Here, the authors show that astrocytes in the VTA selectively facilitate excitation of VTA GABAergic neurons to inhibit dopamine neurons and drive avoidance behavior via GLT-1.
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Mlost J, Wąsik A, Starowicz K. Role of endocannabinoid system in dopamine signalling within the reward circuits affected by chronic pain. Pharmacol Res 2019; 143:40-47. [PMID: 30831242 DOI: 10.1016/j.phrs.2019.02.029] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/03/2019] [Revised: 02/27/2019] [Accepted: 02/28/2019] [Indexed: 12/18/2022]
Abstract
The association between chronic pain, depression and anxiety has gained particular attention due to high rates of comorbidity. Recent data demonstrated that the mesolimbic reward circuitry is involved in the pathology of chronic pain. Interestingly, the mesolimbic reward circuit participates both in pain perception and in pain relief. The endocannabinoid system (ECS) has emerged as a highly relevant player involved in both pain perception and reward processing. Targeting ECS could become a novel treatment strategy for chronic pain patients. However, little is known about the underlying mechanisms of action of cannabinoids at the intersection of neurochemical changes in reward circuits and chronic pain. Because understanding the benefits and risks of cannabinoids is paramount, the aim of this review is to evaluate the state-of-art knowledge about the involvement of the ECS in dopamine signalling within the reward circuits affected by chronic pain.
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Affiliation(s)
- Jakub Mlost
- Institute of Pharmacology, Department of Neurochemistry, Polish Academy of Sciences, Kraków, Poland
| | - Agnieszka Wąsik
- Institute of Pharmacology, Department of Neurochemistry, Polish Academy of Sciences, Kraków, Poland
| | - Katarzyna Starowicz
- Institute of Pharmacology, Department of Neurochemistry, Polish Academy of Sciences, Kraków, Poland.
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Brizuela M, Swoap SJ, Ang J, Blessing WW, Ootsuka Y. Neurons in ventral tegmental area tonically inhibit sympathetic outflow to brown adipose tissue: possible mediation of thermogenic signals from lateral habenula. Am J Physiol Regul Integr Comp Physiol 2019; 316:R6-R12. [PMID: 30406672 DOI: 10.1152/ajpregu.00256.2018] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The lateral habenula (LHb), a nucleus involved in the response to salient, especially adverse, environmental events, is implicated in brown adipose tissue (BAT) thermogenesis caused by these events. LHb-elicited thermogenesis involves a neural pathway to the lower brain stem sympathetic control center in the medullary raphé. There are no direct connections from the LHb to the medullary raphé. LHb-mediated behavioral responses involve inhibitory control over the dopamine neurons in the ventral tegmental area (VTA), mediated via an excitatory drive from the LHb to GABAergic neurons in the tail of the VTA. We hypothesized that inhibition of the VTA is also involved in LHb-mediated BAT thermogenesis. To test this hypothesis, inhibition of neurons in the VTA with muscimol increased BAT sympathetic nerve discharge by 22.0 ± 9.2 dBμV ( n = 24, P < 0.0001) and BAT temperature by 1.2 ± 0.1°C ( P < 0.001). This response was abolished by inhibition of the medullary raphé neurons with muscimol. BAT thermogenesis initiated with focal injections of bicuculline in the LHb was reversed by subsequent blockade of GABAA receptors in the VTA with bicuculline. These results suggest that, at least in anesthetized rats, neurons in the VTA tonically inhibit BAT thermogenesis via a link, presently unknown, to the medullary raphé. Removal of this VTA-initiated inhibition is an important mechanism whereby LHb neurons activate BAT thermogenesis.
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Affiliation(s)
- Mariana Brizuela
- Centre for Neuroscience, Discipline of Human Physiology, College of Medicine and Public Health, Flinders University , Adelaide South Australia , Australia
| | - Steven J Swoap
- Department of Biology, Williams College , Williamstown, Massachusetts
| | - James Ang
- Centre for Neuroscience, Discipline of Human Physiology, College of Medicine and Public Health, Flinders University , Adelaide South Australia , Australia
| | - William W Blessing
- Centre for Neuroscience, Discipline of Human Physiology, College of Medicine and Public Health, Flinders University , Adelaide South Australia , Australia
| | - Youichirou Ootsuka
- Centre for Neuroscience, Discipline of Human Physiology, College of Medicine and Public Health, Flinders University , Adelaide South Australia , Australia
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Yang S, Wang J, Lin Q, Deng B, Wei X, Liu C, Li H. Cost-efficient FPGA implementation of a biologically plausible dopamine neural network and its application. Neurocomputing 2018. [DOI: 10.1016/j.neucom.2018.07.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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di Volo M, Morozova EO, Lapish CC, Kuznetsov A, Gutkin B. Dynamical ventral tegmental area circuit mechanisms of alcohol-dependent dopamine release. Eur J Neurosci 2018; 50:2282-2296. [PMID: 30215874 DOI: 10.1111/ejn.14147] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Revised: 08/15/2018] [Accepted: 08/24/2018] [Indexed: 11/28/2022]
Abstract
A large body of data has identified numerous molecular targets through which ethanol (EtOH) acts on brain circuits. Yet how these multiple mechanisms interact to result in dysregulated dopamine (DA) release under the influence of alcohol in vivo remains unclear. In this manuscript, we delineate potential circuit-level mechanisms responsible for EtOH-dependent dysregulation of DA release from the ventral tegmental area (VTA) into its projection areas. For this purpose, we constructed a circuit model of the VTA that integrates realistic Glutamatergic (Glu) inputs and reproduces DA release observed experimentally. We modelled the concentration-dependent effects of EtOH on its principal VTA targets. We calibrated the model to reproduce the inverted U-shape dose dependence of DA neuron activity on EtOH concentration. The model suggests a primary role of EtOH-induced boost in the Ih and AMPA currents in the DA firing-rate/bursting increase. This is counteracted by potentiated GABA transmission that decreases DA neuron activity at higher EtOH concentrations. Thus, the model connects well-established in vitro pharmacological EtOH targets with its in vivo influence on neuronal activity. Furthermore, we predict that increases in VTA activity produced by moderate EtOH doses require partial synchrony and relatively low rates of the Glu afferents. We propose that the increased frequency of transient (phasic) DA peaks evoked by EtOH results from synchronous population bursts in VTA DA neurons. Our model predicts that the impact of acute ETOH on dopamine release is critically shaped by the structure of the cortical inputs to the VTA.
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Affiliation(s)
- Matteo di Volo
- Unité de Neurosciences, Information et Complexité, CNRS, Gif-sur-Yvette, France.,Group for Neural Theory, LNC INSERM U960, DEC Ecole Normale Superieure PSL University, Paris, France
| | | | - Christopher C Lapish
- Addiction Neuroscience Program, Indiana University - Purdue University Indianapolis, Indianapolis, IN, USA
| | - Alexey Kuznetsov
- Department of Mathematical Sciences, Indiana University - Purdue University Indianapolis, Indianapolis, IN, USA
| | - Boris Gutkin
- Group for Neural Theory, LNC INSERM U960, DEC Ecole Normale Superieure PSL University, Paris, France.,Center for Cognition and Decision Making, NRU HSE, Moscow, Russia
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Quraishi SA, Paladini CA. Could GABA, with a side of glycine, control glutamate receptors? Eur J Neurosci 2018; 47:1206-1207. [PMID: 29729221 DOI: 10.1111/ejn.13929] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Salma A Quraishi
- Department of Biology, UTSA Neurosciences Institute, University of Texas at San Antonio, San Antonio, TX, USA
| | - Carlos A Paladini
- Department of Biology, UTSA Neurosciences Institute, University of Texas at San Antonio, San Antonio, TX, USA
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Cai H, Cao T, Zhou X, Yao JK. Neurosteroids in Schizophrenia: Pathogenic and Therapeutic Implications. Front Psychiatry 2018; 9:73. [PMID: 29568275 PMCID: PMC5852066 DOI: 10.3389/fpsyt.2018.00073] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/17/2017] [Accepted: 02/21/2018] [Indexed: 12/11/2022] Open
Abstract
Neurosteroids are a group of important endogenous molecules affecting many neural functions in the brain. Increasing evidence suggests a possible role of these neurosteroids in the pathology and symptomatology of schizophrenia (SZ) and other mental disorders. The aim of this review is to summarize the current knowledge about the neural functions of neurosteroids in the brain, and to evaluate the role of the key neurosteroids as candidate modulators in the etiology and therapeutics of SZ. The present paper provides a brief introduction of neurosteroid metabolism and distribution, followed by a discussion of the mechanisms underlying neurosteroid actions in the brain. The content regarding the modulation of the GABAA receptor is elaborated, given the considerable knowledge of its interactions with other neurotransmitter and neuroprotective systems, as well as its ameliorating effects on stress that may play a role in the SZ pathophysiology. In addition, several preclinical and clinical studies suggested a therapeutic benefit of neurosteroids in SZ patients, even though the presence of altered neurosteroid pathways in the circulating blood and/or brain remains debatable. Following treatment of antipsychotic drugs in SZ, therapeutic benefits have also been linked to the regulation of neurosteroid signaling. Specifically, the neurosteroids such as pregnenolone and dehydroepiandrosterone affect a broad spectrum of behavioral functions through their unique molecular characteristics and may represent innovative therapeutic targets for SZ. Future investigations in larger cohorts with long-term follow-ups will be required to ascertain the neuropsychopharmacological role of this yet unexploited class of neurosteroid agents.
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Affiliation(s)
- HuaLin Cai
- Department of Pharmacy, The Second Xiangya Hospital of Central South University, Changsha, China
- The Institute of Clinical Pharmacy, Central South University, Changsha, China
| | - Ting Cao
- Department of Pharmacy, The Second Xiangya Hospital of Central South University, Changsha, China
- The Institute of Clinical Pharmacy, Central South University, Changsha, China
| | - Xiang Zhou
- Medical Research Service, VA Pittsburgh Healthcare System, Pittsburgh, PA, United States
- Department of Pharmaceutical Sciences, University of Pittsburgh School of Pharmacy, Pittsburgh, PA, United States
| | - Jeffrey K. Yao
- Medical Research Service, VA Pittsburgh Healthcare System, Pittsburgh, PA, United States
- Department of Pharmaceutical Sciences, University of Pittsburgh School of Pharmacy, Pittsburgh, PA, United States
- Department of Psychiatry, University of Pittsburgh School of Medicine, Pittsburgh, PA, United States
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Gantz SC, Ford CP, Morikawa H, Williams JT. The Evolving Understanding of Dopamine Neurons in the Substantia Nigra and Ventral Tegmental Area. Annu Rev Physiol 2018; 80:219-241. [PMID: 28938084 DOI: 10.1146/annurev-physiol-021317-121615] [Citation(s) in RCA: 63] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
In recent years, the population of neurons in the ventral tegmental area (VTA) and substantia nigra (SN) has been examined at multiple levels. The results indicate that the projections, neurochemistry, and receptor and ion channel expression in this cell population vary widely. This review centers on the intrinsic properties and synaptic regulation that control the activity of dopamine neurons. Although all dopamine neurons fire action potentials in a pacemaker pattern in the absence of synaptic input, the intrinsic properties that underlie this activity differ considerably. Likewise, the transition into a burst/pause pattern results from combinations of intrinsic ion conductances, inhibitory and excitatory synaptic inputs that differ among this cell population. Finally, synaptic plasticity is a key regulator of the rate and pattern of activity in different groups of dopamine neurons. Through these fundamental properties, the activity of dopamine neurons is regulated and underlies the wide-ranging functions that have been attributed to dopamine.
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Affiliation(s)
- Stephanie C Gantz
- Intramural Research Program, National Institute on Drug Abuse, Baltimore, Maryland 21224, USA
| | - Christopher P Ford
- Department of Pharmacology, University of Colorado School of Medicine, Aurora, Colorado 80045, USA
| | - Hitoshi Morikawa
- Department of Neuroscience and Waggoner Center for Alcohol and Addiction Research, University of Texas, Austin, Texas 78712, USA
| | - John T Williams
- Vollum Institute, Oregon Health Sciences University, Portland, Oregon 97239, USA;
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Role of the Axon Initial Segment in the Control of Spontaneous Frequency of Nigral Dopaminergic Neurons In Vivo. J Neurosci 2017; 38:733-744. [PMID: 29217687 DOI: 10.1523/jneurosci.1432-17.2017] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2017] [Revised: 10/24/2017] [Accepted: 11/20/2017] [Indexed: 11/21/2022] Open
Abstract
The spontaneous tonic discharge activity of nigral dopamine neurons plays a fundamental role in dopaminergic signaling. To investigate the role of neuronal morphology and architecture with respect to spontaneous activity in this population, we visualized the 3D structure of the axon initial segment (AIS) along with the entire somatodendritic domain of adult male mouse dopaminergic neurons, previously recorded in vivo We observed a positive correlation of the firing rate with both proximity and size of the AIS. Computational modeling showed that the size of the AIS, but not its position within the somatodendritic domain, is the major causal determinant of the tonic firing rate in the intact model, by virtue of the higher intrinsic frequency of the isolated AIS. Further mechanistic analysis of the relationship between neuronal morphology and firing rate showed that dopaminergic neurons function as a coupled oscillator whose frequency of discharge results from a compromise between AIS and somatodendritic oscillators. Thus, morphology plays a critical role in setting the basal tonic firing rate, which in turn could control striatal dopaminergic signaling that mediates motivation and movement.SIGNIFICANCE STATEMENT The frequency at which nigral dopamine neurons discharge action potentials sets baseline dopamine levels in the brain, which enables activity in motor, cognitive, and motivational systems. Here, we demonstrate that the size of the axon initial segment, a subcellular compartment responsible for initiating action potentials, is a key determinant of the firing rate in these neurons. The axon initial segment and all the molecular components that underlie its critical function may provide a novel target for the regulation of dopamine levels in the brain.
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Cheng JP, Leary JB, O'Neil DA, Meyer EA, Free KE, Bondi CO, Kline AE. Spontaneous recovery of traumatic brain injury-induced functional deficits is not hindered by daily administration of lorazepam. Behav Brain Res 2017; 339:215-221. [PMID: 29203336 DOI: 10.1016/j.bbr.2017.11.039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Revised: 11/02/2017] [Accepted: 11/30/2017] [Indexed: 10/18/2022]
Abstract
Agitation and aggression are common sequelae of traumatic brain injury (TBI) and pose a challenge to physicians and other health providers during acute patient care and subsequent neurorehabilitation. Antipsychotic drugs (APDs) are routinely administered to manage TBI patients displaying such maladaptive behaviors despite several clinical and preclinical studies demonstrating that they hinder recovery. A potentially viable alternative to APDs may be the benzodiazepines, which have differing mechanisms of action. Hence, the aim of the study was to test the hypothesis that lorazepam (LOR) would not impede recovery after TBI. Anesthetized adult male rats received a cortical impact or sham injury and then were intraperitoneally administered LOR (0.1mg/kg, 1.0mg/kg, or 2.0mg/kg) or vehicle (VEH; 1mL/kg) commencing 24-h after surgery and once daily for 19days. Motor and cognitive outcomes were assessed on post-operative days 1-5 and 14-19, respectively. No differences were revealed among the four sham control groups and thus they were pooled into one inclusive SHAM group. The SHAMs performed better than all TBI groups on all assessments (p<0.05). Regarding TBI, the 2.0mg/kg LOR group performed better than the VEH and 0.1mg/kg or 1.0mg/kg LOR groups on every task (p<0.05); no differences were observed among the latter three groups on any endpoint (p>0.05). Overall, these preclinical behavioral data support the hypothesis and reveal a therapeutic benefit with the higher dose of LOR. The findings suggest that LOR may be an alternative, to APDs, for controlling agitation without compromising spontaneous recovery and perhaps could afford a dual benefit by also promoting therapeutic efficacy.
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Affiliation(s)
- Jeffrey P Cheng
- Physical Medicine & Rehabilitation, University of Pittsburgh, Pittsburgh, PA, 15213, United States; Safar Center for Resuscitation Research, University of Pittsburgh, Pittsburgh, PA, 15213, United States
| | - Jacob B Leary
- Physical Medicine & Rehabilitation, University of Pittsburgh, Pittsburgh, PA, 15213, United States; Safar Center for Resuscitation Research, University of Pittsburgh, Pittsburgh, PA, 15213, United States
| | - Darik A O'Neil
- Physical Medicine & Rehabilitation, University of Pittsburgh, Pittsburgh, PA, 15213, United States; Safar Center for Resuscitation Research, University of Pittsburgh, Pittsburgh, PA, 15213, United States
| | - Elizabeth A Meyer
- Physical Medicine & Rehabilitation, University of Pittsburgh, Pittsburgh, PA, 15213, United States; Safar Center for Resuscitation Research, University of Pittsburgh, Pittsburgh, PA, 15213, United States
| | - Kristin E Free
- Physical Medicine & Rehabilitation, University of Pittsburgh, Pittsburgh, PA, 15213, United States; Safar Center for Resuscitation Research, University of Pittsburgh, Pittsburgh, PA, 15213, United States
| | - Corina O Bondi
- Physical Medicine & Rehabilitation, University of Pittsburgh, Pittsburgh, PA, 15213, United States; Neurobiology, University of Pittsburgh, Pittsburgh, PA, 15213, United States; Center for Neuroscience, University of Pittsburgh, Pittsburgh, PA, 15213, United States
| | - Anthony E Kline
- Physical Medicine & Rehabilitation, University of Pittsburgh, Pittsburgh, PA, 15213, United States; Safar Center for Resuscitation Research, University of Pittsburgh, Pittsburgh, PA, 15213, United States; Center for Neuroscience, University of Pittsburgh, Pittsburgh, PA, 15213, United States; Center for the Neural Basis of Cognition, University of Pittsburgh, Pittsburgh, PA, 15213, United States; Critical Care Medicine, University of Pittsburgh, Pittsburgh, PA, 15213, United States; Psychology, University of Pittsburgh, PA, 15213, United States.
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Abstract
Dopamine neurons encode errors in reward prediction, yet understanding how they integrate information from different subcortical inputs to generate these signals has remained elusive. In this issue of Neuron, Tian et al. (2016) shed new light onto these underlying mechanisms.
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Affiliation(s)
- Stan B Floresco
- Department of Psychology and Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, BC V6T 1Z4, Canada.
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38
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Sanjari Moghaddam H, Zare-Shahabadi A, Rahmani F, Rezaei N. Neurotransmission systems in Parkinson’s disease. Rev Neurosci 2017; 28:509-536. [DOI: 10.1515/revneuro-2016-0068] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2016] [Accepted: 01/10/2017] [Indexed: 12/17/2022]
Abstract
AbstractParkinson’s disease (PD) is histologically characterized by the accumulation of α-synuclein particles, known as Lewy bodies. The second most common neurodegenerative disorder, PD is widely known because of the typical motor manifestations of active tremor, rigidity, and postural instability, while several prodromal non-motor symptoms including REM sleep behavior disorders, depression, autonomic disturbances, and cognitive decline are being more extensively recognized. Motor symptoms most commonly arise from synucleinopathy of nigrostriatal pathway. Glutamatergic, γ-aminobutyric acid (GABA)ergic, cholinergic, serotoninergic, and endocannabinoid neurotransmission systems are not spared from the global cerebral neurodegenerative assault. Wide intrabasal and extrabasal of the basal ganglia provide enough justification to evaluate network circuits disturbance of these neurotransmission systems in PD. In this comprehensive review, English literature in PubMed, Science direct, EMBASE, and Web of Science databases were perused. Characteristics of dopaminergic and non-dopaminergic systems, disturbance of these neurotransmitter systems in the pathophysiology of PD, and their treatment applications are discussed.
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Affiliation(s)
- Hossein Sanjari Moghaddam
- Research Center for Immunodeficiencies, Children’s Medical Center Hospital, Tehran University of Medical Sciences, Dr Qarib St, Keshavarz Blvd, Tehran 14194, Iran
- NeuroImmunology Research Association (NIRA), Universal Scientific Education and Research Network (USERN), Tehran 1419783151, Iran
- Student Scientific Research Center (SSRC), Tehran University of Medical Sciences, Tehran, Iran
| | - Ameneh Zare-Shahabadi
- Research Center for Immunodeficiencies, Children’s Medical Center Hospital, Tehran University of Medical Sciences, Dr Qarib St, Keshavarz Blvd, Tehran 14194, Iran
- NeuroImmunology Research Association (NIRA), Universal Scientific Education and Research Network (USERN), Tehran 1419783151, Iran
- Psychiatry and Psychology Research Center, Tehran University of Medical Sciences, Tehran, Iran
| | - Farzaneh Rahmani
- Research Center for Immunodeficiencies, Children’s Medical Center Hospital, Tehran University of Medical Sciences, Dr Qarib St, Keshavarz Blvd, Tehran 14194, Iran
- NeuroImaging Network (NIN), Universal Scientific Education and Research Network (USERN), Tehran, Iran
| | - Nima Rezaei
- Research Center for Immunodeficiencies, Children’s Medical Center Hospital, Tehran University of Medical Sciences, Dr Qarib St, Keshavarz Blvd, Tehran 14194, Iran
- Department of Immunology, School of Medicine, Tehran University of Medical Sciences, Tehran 1419783151, Iran
- Network of Immunity in Infection, Malignancy and Autoimmunity (NIIMA), Universal Scientific Education and Research Network (USERN), Boston, MA, USA
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Simmons DV, Petko AK, Paladini CA. Differential expression of long-term potentiation among identified inhibitory inputs to dopamine neurons. J Neurophysiol 2017; 118:1998-2008. [PMID: 28701538 DOI: 10.1152/jn.00270.2017] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2017] [Revised: 07/06/2017] [Accepted: 07/10/2017] [Indexed: 01/10/2023] Open
Abstract
The in vivo firing pattern of ventral tegmental area (VTA) dopamine neurons is controlled by GABA afferents originating primarily from the nucleus accumbens (NAc), rostromedial tegmental nucleus (RMTg), and local GABA neurons within the VTA. Although different forms of plasticity have been observed from GABA inputs to VTA dopamine neurons, one dependent on cyclic GMP synthesis and the other on adenylyl cyclase activation, it is unknown whether plasticity is differentially expressed in each. Using an optogenetic strategy, we show that identified inhibitory postsynaptic currents (IPSCs) from local VTA GABA neurons and NAc afferents exhibit a cyclic GMP-dependent long-term potentiation (LTP) that is capable of inhibiting the firing activity of dopamine neurons. However, this form of LTP was not induced from RMTg afferents. Only an adenylyl cyclase-mediated increase in IPSCs was exhibited by all three inputs. Thus discrete plasticity mechanisms recruit overlapping but different subsets of GABA inputs to VTA dopamine neurons.NEW & NOTEWORTHY We describe a mapping of plasticity expression, mediated by different mechanisms, among three distinct GABA afferents to ventral tegmental area (VTA) dopamine neurons: the rostromedial tegmental nucleus, the nucleus accumbens, and the local GABA neurons within the VTA known to synapse on VTA dopamine neurons. This work is the first demonstration that discrete plasticity mechanisms recruit overlapping but different subsets of GABA inputs to VTA dopamine neurons.
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Affiliation(s)
- DeNard V Simmons
- Neurosciences Institute, The University of Texas at San Antonio, San Antonio, Texas
| | - Alyssa K Petko
- Neurosciences Institute, The University of Texas at San Antonio, San Antonio, Texas
| | - Carlos A Paladini
- Neurosciences Institute, The University of Texas at San Antonio, San Antonio, Texas
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40
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Endocannabinoid modulation of dopamine neurotransmission. Neuropharmacology 2017; 124:52-61. [PMID: 28450060 DOI: 10.1016/j.neuropharm.2017.04.033] [Citation(s) in RCA: 115] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2017] [Revised: 04/20/2017] [Accepted: 04/23/2017] [Indexed: 12/15/2022]
Abstract
Dopamine (DA) is a major catecholamine neurotransmitter in the mammalian brain that controls neural circuits involved in the cognitive, emotional, and motor aspects of goal-directed behavior. Accordingly, perturbations in DA neurotransmission play a central role in several neuropsychiatric disorders. Somewhat surprisingly given its prominent role in numerous behaviors, DA is released by a relatively small number of densely packed neurons originating in the midbrain. The dopaminergic midbrain innervates numerous brain regions where extracellular DA release and receptor binding promote short- and long-term changes in postsynaptic neuron function. Striatal forebrain nuclei receive the greatest proportion of DA projections and are a predominant hub at which DA influences behavior. A number of excitatory, inhibitory, and modulatory inputs orchestrate DA neurotransmission by controlling DA cell body firing patterns, terminal release, and effects on postsynaptic sites in the striatum. The endocannabinoid (eCB) system serves as an important filter of afferent input that acts locally at midbrain and terminal regions to shape how incoming information is conveyed onto DA neurons and to output targets. In this review, we aim to highlight existing knowledge regarding how eCB signaling controls DA neuron function through modifications in synaptic strength at midbrain and striatal sites, and to raise outstanding questions on this topic. This article is part of the Special Issue entitled "A New Dawn in Cannabinoid Neurobiology".
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41
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Walczak M, Błasiak T. Midbrain dopaminergic neuron activity across alternating brain states of urethane anaesthetized rat. Eur J Neurosci 2017; 45:1068-1077. [PMID: 28177164 DOI: 10.1111/ejn.13533] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2016] [Revised: 01/26/2017] [Accepted: 01/31/2017] [Indexed: 12/23/2022]
Abstract
Midbrain dopaminergic neurons are implicated in the control of motor functions and reward-driven behaviours. The function of this neuronal population is strongly connected with distinct patterns of firing - irregular or bursting, which either maintains basal levels of dopamine (DA) or leads to phasic release, respectively. Heterogeneity of dopaminergic neurons, observed on both structural and functional levels, is also reflected in different responses of DA neurons to changes in global brain states. Preparation of urethane anaesthetized animal is a broadly used model to study brain state dependent activity of neurons. Unfortunately activity of midbrain DA neurons across urethane induced cyclic, spontaneous brain state alternations is poorly described. To fulfil this gap in our knowledge we have performed simultaneous, extracellular recordings of the firing of single putative DA neurons combined with continuous brain state monitoring. We found that during slow wave activity, the firing rate of recorded putative DA neurons was significantly higher compared to firing rates during activated state, both in ventral tegmental area (VTA) and substantia nigra pars compacta (SNc). In the presence of cortical slow waves, putative dopaminergic neurons also intensified bursting activity, but the magnitude of this phenomena differed in respect to the examined region (VTA or SNc). Our results show that activity of DA neurons under urethane anaesthesia is brain-state dependent and emphasize the importance of brain state monitoring during electrophysiological experiments.
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Affiliation(s)
- Magdalena Walczak
- Department of Neurophysiology and Chronobiology, Institute of Zoology, Jagiellonian University, Gronostajowa 9, 30-387, Krakow, Poland
| | - Tomasz Błasiak
- Department of Neurophysiology and Chronobiology, Institute of Zoology, Jagiellonian University, Gronostajowa 9, 30-387, Krakow, Poland
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Estep CM, Galtieri DJ, Zampese E, Goldberg JA, Brichta L, Greengard P, Surmeier DJ. Transient Activation of GABAB Receptors Suppresses SK Channel Currents in Substantia Nigra Pars Compacta Dopaminergic Neurons. PLoS One 2016; 11:e0169044. [PMID: 28036359 PMCID: PMC5201262 DOI: 10.1371/journal.pone.0169044] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2016] [Accepted: 12/09/2016] [Indexed: 12/15/2022] Open
Abstract
Dopaminergic (DA) neurons in the substantia nigra pars compacta (SNc) are richly innervated by GABAergic neurons. The postsynaptic effects of GABA on SNc DA neurons are mediated by a mixture of GABAA and GABAB receptors. Although activation of GABAA receptors inhibits spike generation, the consequences of GABAB receptor activation are less well characterized. To help fill this gap, perforated patch recordings were made from young adult mouse SNc DA neurons. Sustained stimulation of GABAB receptors hyperpolarized SNc DA neurons, as previously described. However, transient stimulation of GABAB receptors by optical uncaging of GABA did not; rather, it reduced the opening of small-conductance, calcium-activated K+ (SK) channels and increased the irregularity of spiking. This modulation was attributable to inhibition of adenylyl cyclase and protein kinase A. Thus, because suppression of SK channel activity increases the probability of burst spiking, transient co-activation of GABAA and GABAB receptors could promote a pause-burst pattern of spiking.
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Affiliation(s)
- Chad M. Estep
- Department of Physiology, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States of America
| | - Daniel J. Galtieri
- Department of Physiology, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States of America
| | - Enrico Zampese
- Department of Physiology, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States of America
| | - Joshua A. Goldberg
- Department of Medical Neurobiology, Institute of Medical Research Israel-Canada, Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Lars Brichta
- Laboratory of Molecular and Cellular Neuroscience, Rockefeller University, New York, NY, United States of America
| | - Paul Greengard
- Laboratory of Molecular and Cellular Neuroscience, Rockefeller University, New York, NY, United States of America
| | - D. James Surmeier
- Department of Physiology, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States of America
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Morozova EO, Zakharov D, Gutkin BS, Lapish CC, Kuznetsov A. Dopamine Neurons Change the Type of Excitability in Response to Stimuli. PLoS Comput Biol 2016; 12:e1005233. [PMID: 27930673 PMCID: PMC5145155 DOI: 10.1371/journal.pcbi.1005233] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Accepted: 11/02/2016] [Indexed: 11/18/2022] Open
Abstract
The dynamics of neuronal excitability determine the neuron's response to stimuli, its synchronization and resonance properties and, ultimately, the computations it performs in the brain. We investigated the dynamical mechanisms underlying the excitability type of dopamine (DA) neurons, using a conductance-based biophysical model, and its regulation by intrinsic and synaptic currents. Calibrating the model to reproduce low frequency tonic firing results in N-methyl-D-aspartate (NMDA) excitation balanced by γ-Aminobutyric acid (GABA)-mediated inhibition and leads to type I excitable behavior characterized by a continuous decrease in firing frequency in response to hyperpolarizing currents. Furthermore, we analyzed how excitability type of the DA neuron model is influenced by changes in the intrinsic current composition. A subthreshold sodium current is necessary for a continuous frequency decrease during application of a negative current, and the low-frequency "balanced" state during simultaneous activation of NMDA and GABA receptors. Blocking this current switches the neuron to type II characterized by the abrupt onset of repetitive firing. Enhancing the anomalous rectifier Ih current also switches the excitability to type II. Key characteristics of synaptic conductances that may be observed in vivo also change the type of excitability: a depolarized γ-Aminobutyric acid receptor (GABAR) reversal potential or co-activation of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (AMPARs) leads to an abrupt frequency drop to zero, which is typical for type II excitability. Coactivation of N-methyl-D-aspartate receptors (NMDARs) together with AMPARs and GABARs shifts the type I/II boundary toward more hyperpolarized GABAR reversal potentials. To better understand how altering each of the aforementioned currents leads to changes in excitability profile of DA neuron, we provide a thorough dynamical analysis. Collectively, these results imply that type I excitability in dopamine neurons might be important for low firing rates and fine-tuning basal dopamine levels, while switching excitability to type II during NMDAR and AMPAR activation may facilitate a transient increase in dopamine concentration, as type II neurons are more amenable to synchronization by mutual excitation.
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Affiliation(s)
- Ekaterina O. Morozova
- Department of Physics, Indiana University, Bloomington, Indiana, United States of America
- Department of Mathematical sciences, Indiana University - Purdue University, Indianapolis, Indiana, United States of America
- * E-mail:
| | | | - Boris S. Gutkin
- Group of Neural Theory, INSERM U960 LNC, IEC, Ecole Normale Superieure PSL University, Paris
- Center for Cognition and Decision Making, NRU HSE, Moscow, Russia
| | - Christopher C. Lapish
- Addiction Neuroscience Program, Indiana University - Purdue University, Indianapolis, Indiana, United States of America
| | - Alexey Kuznetsov
- Department of Mathematical sciences, Indiana University - Purdue University, Indianapolis, Indiana, United States of America
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Morozova EO, Myroshnychenko M, Zakharov D, di Volo M, Gutkin B, Lapish CC, Kuznetsov A. Contribution of synchronized GABAergic neurons to dopaminergic neuron firing and bursting. J Neurophysiol 2016; 116:1900-1923. [PMID: 27440240 PMCID: PMC5144690 DOI: 10.1152/jn.00232.2016] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2016] [Accepted: 07/17/2016] [Indexed: 12/29/2022] Open
Abstract
In the ventral tegmental area (VTA), interactions between dopamine (DA) and γ-aminobutyric acid (GABA) neurons are critical for regulating DA neuron activity and thus DA efflux. To provide a mechanistic explanation of how GABA neurons influence DA neuron firing, we developed a circuit model of the VTA. The model is based on feed-forward inhibition and recreates canonical features of the VTA neurons. Simulations revealed that γ-aminobutyric acid (GABA) receptor (GABAR) stimulation can differentially influence the firing pattern of the DA neuron, depending on the level of synchronization among GABA neurons. Asynchronous activity of GABA neurons provides a constant level of inhibition to the DA neuron and, when removed, produces a classical disinhibition burst. In contrast, when GABA neurons are synchronized by common synaptic input, their influence evokes additional spikes in the DA neuron, resulting in increased measures of firing and bursting. Distinct from previous mechanisms, the increases were not based on lowered firing rate of the GABA neurons or weaker hyperpolarization by the GABAR synaptic current. This phenomenon was induced by GABA-mediated hyperpolarization of the DA neuron that leads to decreases in intracellular calcium (Ca2+) concentration, thus reducing the Ca2+-dependent potassium (K+) current. In this way, the GABA-mediated hyperpolarization replaces Ca2+-dependent K+ current; however, this inhibition is pulsatile, which allows the DA neuron to fire during the rhythmic pauses in inhibition. Our results emphasize the importance of inhibition in the VTA, which has been discussed in many studies, and suggest a novel mechanism whereby computations can occur locally.
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Affiliation(s)
- Ekaterina O Morozova
- Department of Physics, Indiana University, Bloomington, Indiana; Department of Mathematical Sciences, Indiana University-Purdue University, Indianapolis, Indiana;
| | - Maxym Myroshnychenko
- Program in Neuroscience, Indiana University, Bloomington, Indiana; Addiction Neuroscience Program, Indiana University-Purdue University, Indianapolis, Indiana; and
| | - Denis Zakharov
- Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod, Russia
| | - Matteo di Volo
- Department of Mathematical Sciences, Indiana University-Purdue University, Indianapolis, Indiana; Group of Neural Theory, INSERM U960, Laboratoire de Neurosciences Cognitives, Institut d'Etude de Cognition, Ecole Normale Superieure, Paris Sciences et Lettres Research University, Paris, France
| | - Boris Gutkin
- Group of Neural Theory, INSERM U960, Laboratoire de Neurosciences Cognitives, Institut d'Etude de Cognition, Ecole Normale Superieure, Paris Sciences et Lettres Research University, Paris, France; Center for Cognition and Decision Making, National Research University Higher School of Economics, Moscow, Russia
| | - Christopher C Lapish
- Addiction Neuroscience Program, Indiana University-Purdue University, Indianapolis, Indiana; and
| | - Alexey Kuznetsov
- Department of Mathematical Sciences, Indiana University-Purdue University, Indianapolis, Indiana
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45
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Locklear MN, Michaelos M, Collins WF, Kritzer MF. Gonadectomy but not biological sex affects burst-firing in dopamine neurons of the ventral tegmental area and in prefrontal cortical neurons projecting to the ventral tegmentum in adult rats. Eur J Neurosci 2016; 45:106-120. [PMID: 27564091 DOI: 10.1111/ejn.13380] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2016] [Revised: 08/03/2016] [Accepted: 08/22/2016] [Indexed: 12/25/2022]
Abstract
The mesocortical and mesolimbic dopamine systems regulate cognitive and motivational processes and are strongly implicated in neuropsychiatric disorders in which these processes are disturbed. Sex differences and sex hormone modulation are also known for these dopamine-sensitive behaviours in health and disease. One relevant mechanism of hormone impact appears to be regulation of cortical and subcortical dopamine levels. This study asked whether this regulation of dopamine tone is a consequence of sex or sex hormone impact on the firing modes of ventral midbrain dopamine neurons. To address this, single unit extracellular recordings made in the ventral tegmental area and substantia nigra were compared among urethane-anaesthetized adult male, female, gonadectomized male rats. These comparisons showed that gonadectomy had no effect on nigral cells and no effects on pacemaker, bursty, single-spiking or random modes of dopamine activity in the ventral tegmental area. However, it did significantly and selectively increase burst firing in these cells in a testosterone-sensitive, estradiol-insensitive manner. Given the roles of prefrontal cortex (PFC) in modulating midbrain dopamine cell firing, we next asked whether gonadectomy's effects on dopamine cell bursting had correlated effects on the activity of ventral tegmentally projecting prefrontal cortical neurons. We found that gonadectomy indeed significantly and selectively increased burst firing in ventral tegmentally projecting but not neighbouring prefrontal cells. These effects were also androgen-sensitive. Together, these findings suggest a working model wherein androgen influence over the activity of PFC neurons regulates its top-down modulation of mesocortical and mesolimbic dopamine systems and related dopamine-sensitive behaviours.
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Affiliation(s)
- Mallory N Locklear
- Department of Neurobiology and Behavior, Stony Brook University, Stony Brook, NY, 11794-5230, USA
| | - Michalis Michaelos
- Department of Neurobiology and Behavior, Stony Brook University, Stony Brook, NY, 11794-5230, USA
| | - William F Collins
- Department of Neurobiology and Behavior, Stony Brook University, Stony Brook, NY, 11794-5230, USA
| | - Mary F Kritzer
- Department of Neurobiology and Behavior, Stony Brook University, Stony Brook, NY, 11794-5230, USA
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46
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Tian J, Huang R, Cohen JY, Osakada F, Kobak D, Machens CK, Callaway EM, Uchida N, Watabe-Uchida M. Distributed and Mixed Information in Monosynaptic Inputs to Dopamine Neurons. Neuron 2016; 91:1374-1389. [PMID: 27618675 DOI: 10.1016/j.neuron.2016.08.018] [Citation(s) in RCA: 143] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Revised: 06/28/2016] [Accepted: 07/25/2016] [Indexed: 01/29/2023]
Abstract
Dopamine neurons encode the difference between actual and predicted reward, or reward prediction error (RPE). Although many models have been proposed to account for this computation, it has been difficult to test these models experimentally. Here we established an awake electrophysiological recording system, combined with rabies virus and optogenetic cell-type identification, to characterize the firing patterns of monosynaptic inputs to dopamine neurons while mice performed classical conditioning tasks. We found that each variable required to compute RPE, including actual and predicted reward, was distributed in input neurons in multiple brain areas. Further, many input neurons across brain areas signaled combinations of these variables. These results demonstrate that even simple arithmetic computations such as RPE are not localized in specific brain areas but, rather, distributed across multiple nodes in a brain-wide network. Our systematic method to examine both activity and connectivity revealed unexpected redundancy for a simple computation in the brain.
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Affiliation(s)
- Ju Tian
- Department of Molecular and Cellular Biology, Center for Brain Science, Harvard University, Cambridge, MA 02138, USA
| | - Ryan Huang
- Department of Molecular and Cellular Biology, Center for Brain Science, Harvard University, Cambridge, MA 02138, USA
| | - Jeremiah Y Cohen
- Department of Molecular and Cellular Biology, Center for Brain Science, Harvard University, Cambridge, MA 02138, USA; The Solomon H. Snyder Department of Neuroscience, Brain Science Institute, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Fumitaka Osakada
- Systems Neurobiology Laboratory, Salk Institute for Biological Studies, La Jolla, CA 92037, USA; Laboratory of Cellular Pharmacology, Graduate School of Pharmaceutical Sciences, Nagoya University, Nagoya 464-8601, Japan
| | - Dmitry Kobak
- Champalimaud Neuroscience Programme, Champalimaud Centre for the Unknown, Lisbon 1400-038, Portugal
| | - Christian K Machens
- Champalimaud Neuroscience Programme, Champalimaud Centre for the Unknown, Lisbon 1400-038, Portugal
| | - Edward M Callaway
- Systems Neurobiology Laboratory, Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Naoshige Uchida
- Department of Molecular and Cellular Biology, Center for Brain Science, Harvard University, Cambridge, MA 02138, USA.
| | - Mitsuko Watabe-Uchida
- Department of Molecular and Cellular Biology, Center for Brain Science, Harvard University, Cambridge, MA 02138, USA.
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47
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Canavier CC, Evans RC, Oster AM, Pissadaki EK, Drion G, Kuznetsov AS, Gutkin BS. Implications of cellular models of dopamine neurons for disease. J Neurophysiol 2016; 116:2815-2830. [PMID: 27582295 DOI: 10.1152/jn.00530.2016] [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: 06/30/2016] [Accepted: 08/24/2016] [Indexed: 12/21/2022] Open
Abstract
This review addresses the present state of single-cell models of the firing pattern of midbrain dopamine neurons and the insights that can be gained from these models into the underlying mechanisms for diseases such as Parkinson's, addiction, and schizophrenia. We will explain the analytical technique of separation of time scales and show how it can produce insights into mechanisms using simplified single-compartment models. We also use morphologically realistic multicompartmental models to address spatially heterogeneous aspects of neural signaling and neural metabolism. Separation of time scale analyses are applied to pacemaking, bursting, and depolarization block in dopamine neurons. Differences in subpopulations with respect to metabolic load are addressed using multicompartmental models.
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Affiliation(s)
- Carmen C Canavier
- Department of Cell Biology and Anatomy, Louisiana State University Health Sciences Center, New Orleans, Louisiana;
| | - Rebekah C Evans
- Cellular Neurophysiology Unit, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland
| | - Andrew M Oster
- Department of Mathematics, Eastern Washington University, Cheney, Washington
| | - Eleftheria K Pissadaki
- IBM T.J. Watson Research Center, Yorktown Heights, New York.,Department of Computer Science, University of Sheffield, Sheffield, United Kingdom
| | - Guillaume Drion
- Department of Electrical Engineering and Computer Science, University of Liege, Liege, Belgium
| | - Alexey S Kuznetsov
- Department of Mathematical Sciences and Center for Mathematical Biosciences, Indiana University, Purdue University Indianapolis, Indianapolis, Indiana
| | - Boris S Gutkin
- Group for Neural Theory, LNC INSERM U960, Département d'Études Cognitives, École Normale Supérieure PSL Research University, Paris, France.,Center for Cognition and Decision Making, NRU Higher School of Economics, Moscow, Russia; and
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48
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The novel cannabinoid antagonist SM-11 reduces hedonic aspect of food intake through a dopamine-dependent mechanism. Pharmacol Res 2016; 113:108-115. [PMID: 27521837 DOI: 10.1016/j.phrs.2016.08.012] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/29/2016] [Revised: 06/20/2016] [Accepted: 08/08/2016] [Indexed: 01/22/2023]
Abstract
Cannabinoids, endogenous and exogenously administered, are known to positively regulate food intake and energy balance. Since CB1 receptor antagonists reduce food intake and antagonize overweight, we developed a new CB1 receptor antagonist in an attempt to identify a compound with potential application in overeating disorders. The newly developed SM-11 compound dose-dependently decreases food intake in rats by 15-20%. Moreover, SM-11 reduces self-administration of palatable food in both food restricted and ad libitum fed rats, suggesting an action on the hedonic component of food intake. Thus, we next tested the effect of SM-11 on the stimulating properties of the CB1 receptor agonist WIN55,212-2 (WIN) on the electrophysiological activity of Nucleus Accumbens-projecting dopaminergic neurons of the ventral tegmental area (VTA). SM-11 fully and readily antagonized the WIN-induced increments in single spiking and burst firing of antidromically-identified dopamine neurons. When administered to naïve (no WIN-pretreated) rats, SM-11 did not alter basal neuronal activity, thereby suggesting a pure antagonistic profile. SM-11 thus appears as a promising candidate in the search of potential anti-obesity medications.
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49
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Zakharov D, Lapish C, Gutkin B, Kuznetsov A. Synergy of AMPA and NMDA Receptor Currents in Dopaminergic Neurons: A Modeling Study. Front Comput Neurosci 2016; 10:48. [PMID: 27252643 PMCID: PMC4877376 DOI: 10.3389/fncom.2016.00048] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2016] [Accepted: 05/06/2016] [Indexed: 11/13/2022] Open
Abstract
Dopaminergic (DA) neurons display two modes of firing: low-frequency tonic and high-frequency bursts. The high frequency firing within the bursts is attributed to NMDA, but not AMPA receptor activation. In our models of the DA neuron, both biophysical and abstract, the NMDA receptor current can significantly increase their firing frequency, whereas the AMPA receptor current is not able to evoke high-frequency activity and usually suppresses firing. However, both currents are produced by glutamate receptors and, consequently, are often co-activated. Here we consider combined influence of AMPA and NMDA synaptic input in the models of the DA neuron. Different types of neuronal activity (resting state, low frequency, or high frequency firing) are observed depending on the conductance of the AMPAR and NMDAR currents. In two models, biophysical and reduced, we show that the firing frequency increases more effectively if both receptors are co-activated for certain parameter values. In particular, in the more quantitative biophysical model, the maximal frequency is 40% greater than that with NMDAR alone. The dynamical mechanism of such frequency growth is explained in the framework of phase space evolution using the reduced model. In short, both the AMPAR and NMDAR currents flatten the voltage nullcline, providing the frequency increase, whereas only NMDA prevents complete unfolding of the nullcline, providing robust firing. Thus, we confirm a major role of the NMDAR in generating high-frequency firing and conclude that AMPAR activation further significantly increases the frequency.
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Affiliation(s)
- Denis Zakharov
- Nonlinear Dynamics Department, Institute of Applied Physics, Russian Academy of Science (RAS) Nizhny Novgorod, Russia
| | - Christopher Lapish
- Department of Psychology, Indiana University-Purdue University Indianapolis (IUPUI) Indianapolis, IN, USA
| | - Boris Gutkin
- Group of Neural Theory, Ecole Normale Supérieure (ENS)Paris, France; Centre for Cognition and Decision Making, National Research University Higher School of EconomicsMoscow, Russia
| | - Alexey Kuznetsov
- Department of Mathematical Sciences and Center for Mathematical Modeling and Computational Sciences, Indiana University-Purdue University Indianapolis (IUPUI) Indianapolis, IN, USA
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50
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Enrico P, Migliore M, Spiga S, Mulas G, Caboni F, Diana M. Morphofunctional alterations in ventral tegmental area dopamine neurons in acute and prolonged opiates withdrawal. A computational perspective. Neuroscience 2016; 322:195-207. [DOI: 10.1016/j.neuroscience.2016.02.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2015] [Revised: 01/14/2016] [Accepted: 02/02/2016] [Indexed: 11/28/2022]
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