1
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Zhang Y, Ma H, Bai Y, Hou X, Yang Y, Wang G, Li Y. Chronic Neuropathic Pain and Comorbid Depression Syndrome: From Neural Circuit Mechanisms to Treatment. ACS Chem Neurosci 2024; 15:2432-2444. [PMID: 38916052 DOI: 10.1021/acschemneuro.4c00125] [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] [Indexed: 06/26/2024] Open
Abstract
Chronic neuropathic pain and comorbid depression syndrome (CDS) is a major worldwide health problem that affects the quality of life of patients and imposes a tremendous socioeconomic burden. More than half of patients with chronic neuropathic pain also suffer from moderate or severe depression. Due to the complex pathogenesis of CDS, there are no effective therapeutic drugs available. The lack of research on the neural circuit mechanisms of CDS limits the development of treatments. The purpose of this article is to provide an overview of the various circuits involved in CDS. Notably, activating some neural circuits can alleviate pain and/or depression, while activating other circuits can exacerbate these conditions. Moreover, we discuss current and emerging pharmacotherapies for CDS, such as ketamine. Understanding the circuit mechanisms of CDS may provide clues for the development of novel drug treatments for improved CDS management.
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Affiliation(s)
- Yue Zhang
- Department of Anesthesiology, Beijing Tongren Hospital, Capital Medical University, Beijing, 100730, China
| | - Hui Ma
- Beijing Institute of Basic Medical Sciences, Beijing, 100850, China
| | - Yafan Bai
- Department of Anesthesiology, Beijing Tongren Hospital, Capital Medical University, Beijing, 100730, China
| | - Xiaojuan Hou
- Hebei North University, Zhangjiakou, 075000, China
| | - Yixin Yang
- Beijing Institute of Basic Medical Sciences, Beijing, 100850, China
| | - Guyan Wang
- Department of Anesthesiology, Beijing Tongren Hospital, Capital Medical University, Beijing, 100730, China
| | - Yunfeng Li
- Beijing Institute of Basic Medical Sciences, Beijing, 100850, China
- Beijing Institute of Pharmacology and Toxicology, State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Key Laboratory of Neuropsychopharmacology, Beijing, 100850, China
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2
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Xu P, Peng J, Yuan T, Chen Z, He H, Wu Z, Li T, Li X, Wang L, Gao L, Yan J, Wei W, Li CT, Luo ZG, Chen Y. High-throughput mapping of single-neuron projection and molecular features by retrograde barcoded labeling. eLife 2024; 13:e85419. [PMID: 38390967 PMCID: PMC10914349 DOI: 10.7554/elife.85419] [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: 12/07/2022] [Accepted: 02/22/2024] [Indexed: 02/24/2024] Open
Abstract
Deciphering patterns of connectivity between neurons in the brain is a critical step toward understanding brain function. Imaging-based neuroanatomical tracing identifies area-to-area or sparse neuron-to-neuron connectivity patterns, but with limited throughput. Barcode-based connectomics maps large numbers of single-neuron projections, but remains a challenge for jointly analyzing single-cell transcriptomics. Here, we established a rAAV2-retro barcode-based multiplexed tracing method that simultaneously characterizes the projectome and transcriptome at the single neuron level. We uncovered dedicated and collateral projection patterns of ventromedial prefrontal cortex (vmPFC) neurons to five downstream targets and found that projection-defined vmPFC neurons are molecularly heterogeneous. We identified transcriptional signatures of projection-specific vmPFC neurons, and verified Pou3f1 as a marker gene enriched in neurons projecting to the lateral hypothalamus, denoting a distinct subset with collateral projections to both dorsomedial striatum and lateral hypothalamus. In summary, we have developed a new multiplexed technique whose paired connectome and gene expression data can help reveal organizational principles that form neural circuits and process information.
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Affiliation(s)
- Peibo Xu
- Institute of Neuroscience, State Key Laboratory of Neuroscience, Chinese Academy of Sciences, CAS Center for Excellence in Brain Science and Intelligence Technology, Shanghai Center for Brain Science and Brain-Inspired TechnologyShanghaiChina
- University of Chinese Academy of SciencesBeijingChina
| | - Jian Peng
- School of Life Science and Technology & State Key Laboratory of Advanced Medical Materials and Devices, ShanghaiTech UniversityShanghaiChina
| | - Tingli Yuan
- Institute of Neuroscience, State Key Laboratory of Neuroscience, Chinese Academy of Sciences, CAS Center for Excellence in Brain Science and Intelligence Technology, Shanghai Center for Brain Science and Brain-Inspired TechnologyShanghaiChina
| | - Zhaoqin Chen
- Institute of Neuroscience, State Key Laboratory of Neuroscience, Chinese Academy of Sciences, CAS Center for Excellence in Brain Science and Intelligence Technology, Shanghai Center for Brain Science and Brain-Inspired TechnologyShanghaiChina
| | - Hui He
- Institute of Neuroscience, State Key Laboratory of Neuroscience, Chinese Academy of Sciences, CAS Center for Excellence in Brain Science and Intelligence Technology, Shanghai Center for Brain Science and Brain-Inspired TechnologyShanghaiChina
- University of Chinese Academy of SciencesBeijingChina
| | - Ziyan Wu
- Institute of Neuroscience, State Key Laboratory of Neuroscience, Chinese Academy of Sciences, CAS Center for Excellence in Brain Science and Intelligence Technology, Shanghai Center for Brain Science and Brain-Inspired TechnologyShanghaiChina
| | - Ting Li
- School of Life Science and Technology & State Key Laboratory of Advanced Medical Materials and Devices, ShanghaiTech UniversityShanghaiChina
| | - Xiaodong Li
- Institute of Neuroscience, State Key Laboratory of Neuroscience, Chinese Academy of Sciences, CAS Center for Excellence in Brain Science and Intelligence Technology, Shanghai Center for Brain Science and Brain-Inspired TechnologyShanghaiChina
- University of Chinese Academy of SciencesBeijingChina
| | - Luyue Wang
- CAS Key Laboratory of Computational Biology, Shanghai Institute of Nutrition and Health, University of Chinese Academy of Sciences, Chinese Academy of ScienceShanghaiChina
| | - Le Gao
- Institute of Neuroscience, State Key Laboratory of Neuroscience, Chinese Academy of Sciences, CAS Center for Excellence in Brain Science and Intelligence Technology, Shanghai Center for Brain Science and Brain-Inspired TechnologyShanghaiChina
| | - Jun Yan
- Institute of Neuroscience, State Key Laboratory of Neuroscience, Chinese Academy of Sciences, CAS Center for Excellence in Brain Science and Intelligence Technology, Shanghai Center for Brain Science and Brain-Inspired TechnologyShanghaiChina
- Shanghai Center for Brain Science and Brain-Inspired Intelligence TechnologyShanghaiChina
- School of Future Technology, University of Chinese Academy of SciencesBeijingChina
| | - Wu Wei
- CAS Key Laboratory of Computational Biology, Shanghai Institute of Nutrition and Health, University of Chinese Academy of Sciences, Chinese Academy of ScienceShanghaiChina
- Lingang LaboratoryShanghaiChina
| | - Chengyu T Li
- Institute of Neuroscience, State Key Laboratory of Neuroscience, Chinese Academy of Sciences, CAS Center for Excellence in Brain Science and Intelligence Technology, Shanghai Center for Brain Science and Brain-Inspired TechnologyShanghaiChina
- Shanghai Center for Brain Science and Brain-Inspired Intelligence TechnologyShanghaiChina
- School of Future Technology, University of Chinese Academy of SciencesBeijingChina
- Lingang LaboratoryShanghaiChina
| | - Zhen-Ge Luo
- School of Life Science and Technology & State Key Laboratory of Advanced Medical Materials and Devices, ShanghaiTech UniversityShanghaiChina
| | - Yuejun Chen
- Institute of Neuroscience, State Key Laboratory of Neuroscience, Chinese Academy of Sciences, CAS Center for Excellence in Brain Science and Intelligence Technology, Shanghai Center for Brain Science and Brain-Inspired TechnologyShanghaiChina
- Shanghai Center for Brain Science and Brain-Inspired Intelligence TechnologyShanghaiChina
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3
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Liu S, Gao L, Chen J, Yan J. Single-neuron analysis of axon arbors reveals distinct presynaptic organizations between feedforward and feedback projections. Cell Rep 2024; 43:113590. [PMID: 38127620 DOI: 10.1016/j.celrep.2023.113590] [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: 02/23/2023] [Revised: 07/18/2023] [Accepted: 11/30/2023] [Indexed: 12/23/2023] Open
Abstract
The morphology and spatial distribution of axon arbors and boutons are crucial for neuron presynaptic functions. However, the principles governing their whole-brain organization at the single-neuron level remain unclear. We developed a machine-learning method to separate axon arbors from passing axons in single-neuron reconstruction from fluorescence micro-optical sectioning tomography imaging data and obtained 62,374 axon arbors that displayed distinct morphology, spatial patterns, and scaling laws dependent on neuron types and targeted brain areas. Focusing on the axon arbors in the thalamus and cortex, we revealed the segregated spatial distributions and distinct morphology but shared topographic gradients between feedforward and feedback projections. Furthermore, we uncovered an association between arbor complexity and microglia density. Finally, we found that the boutons on terminal arbors show branch-specific clustering with a log-normal distribution that again differed between feedforward and feedback terminal arbors. Together, our study revealed distinct presynaptic structural organizations underlying diverse functional innervation of single projection neurons.
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Affiliation(s)
- Sang Liu
- Institute of Neuroscience, State Key Laboratory of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai 200031, China; School of Future Technology, University of Chinese Academy of Sciences, Beijing 101408, China
| | - Le Gao
- Institute of Neuroscience, State Key Laboratory of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai 200031, China
| | - Jiu Chen
- Institute of Neuroscience, State Key Laboratory of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai 200031, China
| | - Jun Yan
- Institute of Neuroscience, State Key Laboratory of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai 200031, China; School of Future Technology, University of Chinese Academy of Sciences, Beijing 101408, China; Shanghai Center for Brain Science and Brain-Inspired Intelligence Technology, Shanghai 201210, China.
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4
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Gianni G, Pasqualetti M. Wiring and Volume Transmission: An Overview of the Dual Modality for Serotonin Neurotransmission. ACS Chem Neurosci 2023; 14:4093-4104. [PMID: 37966717 DOI: 10.1021/acschemneuro.3c00648] [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] [Indexed: 11/16/2023] Open
Abstract
Serotonin is a neurotransmitter involved in the modulation of a multitude of physiological and behavioral processes. In spite of the relatively reduced number of serotonin-producing neurons present in the mammalian CNS, a complex long-range projection system provides profuse innervation to the whole brain. Heterogeneity of serotonin receptors, grouped in seven families, and their spatiotemporal expression pattern account for its widespread impact. Although neuronal communication occurs primarily at tiny gaps called synapses, wiring transmission, another mechanism based on extrasynaptic diffusion of neuroactive molecules and referred to as volume transmission, has been described. While wiring transmission is a rapid and specific one-to-one modality of communication, volume transmission is a broader and slower mode in which a single element can simultaneously act on several different targets in a one-to-many mode. Some experimental evidence regarding ultrastructural features, extrasynaptic localization of receptors and transporters, and serotonin-glia interactions collected over the past four decades supports the existence of a serotonergic system of a dual modality of neurotransmission, in which wiring and volume transmission coexist. To date, in spite of the radical difference in the two modalities, limited information is available on the way they are coordinated to mediate the specific activities in which serotonin participates. Understanding how wiring and volume transmission modalities contribute to serotonergic neurotransmission is of utmost relevance for the comprehension of serotonin functions in both physiological and pathological conditions.
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Affiliation(s)
- Giulia Gianni
- Unit of Cell and Developmental Biology, Department of Biology, University of Pisa, 56127 Pisa, Italy
| | - Massimo Pasqualetti
- Unit of Cell and Developmental Biology, Department of Biology, University of Pisa, 56127 Pisa, Italy
- Center for Neuroscience and Cognitive Systems @UniTn, Istituto Italiano di Tecnologia, 38068 Rovereto, Italy
- Centro per l'Integrazione della Strumentazione Scientifica dell'Università di Pisa (CISUP), 56126 Pisa, Italy
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5
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Mays KC, Haiman JH, Janušonis S. An experimental platform for stochastic analyses of single serotonergic fibers in the mouse brain. Front Neurosci 2023; 17:1241919. [PMID: 37869509 PMCID: PMC10587471 DOI: 10.3389/fnins.2023.1241919] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2023] [Accepted: 09/21/2023] [Indexed: 10/24/2023] Open
Abstract
The self-organization of the serotonergic matrix, a massive axon meshwork in all vertebrate brains, is driven by the structural and dynamical properties of its constitutive elements. Each of these elements, a single serotonergic axon (fiber), has a unique trajectory and can be supported by a soma that executes one of the many available transcriptional programs. This "individuality" of serotonergic neurons necessitates the development of specialized methods for single-fiber analyses, both at the experimental and theoretical levels. We developed an integrated platform that facilitates experimental isolation of single serotonergic fibers in brain tissue, including regions with high fiber densities, and demonstrated the potential of their quantitative analyses based on stochastic modeling. Single fibers were visualized using two transgenic mouse models, one of which is the first implementation of the Brainbow toolbox in this system. The trajectories of serotonergic fibers were automatically traced in the three spatial dimensions with a novel algorithm, and their properties were captured with a single parameter associated with the directional von Mises-Fisher probability distribution. The system represents an end-to-end workflow that can be imported into various studies, including those investigating serotonergic dysfunction in brain disorders. It also supports new research directions inspired by single-fiber analyses in the serotonergic matrix, including supercomputing simulations and modeling in physics.
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Affiliation(s)
| | | | - Skirmantas Janušonis
- Department of Psychological and Brain Sciences, University of California, Santa Barbara, Santa Barbara, CA, United States
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6
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Maddaloni G, Chang YJ, Senft RA, Dymecki SM. A brain circuit and neuronal mechanism for decoding and adapting to change in daylength. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.11.557218. [PMID: 37745319 PMCID: PMC10515809 DOI: 10.1101/2023.09.11.557218] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/26/2023]
Abstract
Changes in daylight amount (photoperiod) drive pronounced alterations in physiology and behaviour1,2. Adaptive responses to seasonal photoperiods are vital to all organisms - dysregulation is associated with disease, from affective disorders3 to metabolic syndromes4. Circadian rhythm circuitry has been implicated5,6 yet little is known about the precise neural and cellular substrates that underlie phase synchronization to photoperiod change. Here we present a previously unknown brain circuit and novel system of axon branch-specific and reversible neurotransmitter deployment that together prove critical for behavioural and sleep adaptation to photoperiod change. We found that the recently defined neuron type called mrEn1-Pet17 located in the mouse brainstem Median Raphe Nucleus (MRN) segregates serotonin versus VGLUT3 (here proxy for the neurotransmitter glutamate) to different axonal branches innervating specific brain regions involved in circadian rhythm and sleep/wake timing8,9. We found that whether measured during the light or dark phase of the day this branch-specific neurotransmitter deployment in mrEn1-Pet1 neurons was indistinguishable; however, it strikingly reorganizes on photoperiod change. Specifically, axonal boutons but not cell soma show a shift in neurochemical phenotype upon change away from equinox light/dark conditions that reverses upon return to equinox. When we genetically disabled the deployment of VGLUT3 in mrEn1-Pet1 neurons, we found that sleep/wake periods and voluntary activity failed to synchronize to the new photoperiod or was significantly delayed. Combining intersectional rabies virus tracing and projection-specific neuronal silencing in vivo, we delineated a Preoptic Area-to-mrEn1Pet1 connection responsible for decoding the photoperiodic inputs, driving the neurochemical shift and promoting behavioural synchronization. Our results reveal a previously unrecognized brain circuit along with a novel form of periodic, branch-specific neurotransmitter deployment that together regulate organismal adaptation to photoperiod changes.
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Affiliation(s)
- G Maddaloni
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston 02115 MA, USA
| | - Y J Chang
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston 02115 MA, USA
| | - R A Senft
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston 02115 MA, USA
| | - S M Dymecki
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston 02115 MA, USA
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7
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Janušonis S, Haiman JH, Metzler R, Vojta T. Predicting the distribution of serotonergic axons: a supercomputing simulation of reflected fractional Brownian motion in a 3D-mouse brain model. Front Comput Neurosci 2023; 17:1189853. [PMID: 37265780 PMCID: PMC10231035 DOI: 10.3389/fncom.2023.1189853] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2023] [Accepted: 04/24/2023] [Indexed: 06/03/2023] Open
Abstract
The self-organization of the brain matrix of serotonergic axons (fibers) remains an unsolved problem in neuroscience. The regional densities of this matrix have major implications for neuroplasticity, tissue regeneration, and the understanding of mental disorders, but the trajectories of its fibers are strongly stochastic and require novel conceptual and analytical approaches. In a major extension to our previous studies, we used a supercomputing simulation to model around one thousand serotonergic fibers as paths of superdiffusive fractional Brownian motion (FBM), a continuous-time stochastic process. The fibers produced long walks in a complex, three-dimensional shape based on the mouse brain and reflected at the outer (pial) and inner (ventricular) boundaries. The resultant regional densities were compared to the actual fiber densities in the corresponding neuroanatomically-defined regions. The relative densities showed strong qualitative similarities in the forebrain and midbrain, demonstrating the predictive potential of stochastic modeling in this system. The current simulation does not respect tissue heterogeneities but can be further improved with novel models of multifractional FBM. The study demonstrates that serotonergic fiber densities can be strongly influenced by the geometry of the brain, with implications for brain development, plasticity, and evolution.
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Affiliation(s)
- Skirmantas Janušonis
- Department of Psychological and Brain Sciences, University of California, Santa Barbara, Santa Barbara, CA, United States
| | - Justin H. Haiman
- Department of Psychological and Brain Sciences, University of California, Santa Barbara, Santa Barbara, CA, United States
| | - Ralf Metzler
- Institute of Physics and Astronomy, University of Potsdam, Potsdam, Germany
- Asia Pacific Center for Theoretical Physics, Pohang, South Korea
| | - Thomas Vojta
- Department of Physics, Missouri University of Science and Technology, Rolla, MO, United States
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8
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Flanigan ME, Hon OJ, D'Ambrosio S, Boyt KM, Hassanein L, Castle M, Haun HL, Pina MM, Kash TL. Subcortical serotonin 5HT 2c receptor-containing neurons sex-specifically regulate binge-like alcohol consumption, social, and arousal behaviors in mice. Nat Commun 2023; 14:1800. [PMID: 37002196 PMCID: PMC10066391 DOI: 10.1038/s41467-023-36808-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Accepted: 02/17/2023] [Indexed: 04/03/2023] Open
Abstract
Binge alcohol consumption induces discrete social and arousal disturbances in human populations that promote increased drinking and accelerate the progression of Alcohol Use Disorder. Here, we show in a mouse model that binge alcohol consumption disrupts social recognition in females and potentiates sensorimotor arousal in males. These negative behavioral outcomes were associated with sex-specific adaptations in serotonergic signaling systems within the lateral habenula (LHb) and the bed nucleus of the stria terminalis (BNST), particularly those related to the receptor 5HT2c. While both BNST and LHb neurons expressing this receptor display potentiated activation following binge alcohol consumption, the primary causal mechanism underlying the effects of alcohol on social and arousal behaviors appears to be excessive activation of LHb5HT2c neurons. These findings may have valuable implications for the development of sex-specific treatments for mood and alcohol use disorders targeting the brain's serotonin system.
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Affiliation(s)
- M E Flanigan
- Bowles Center for Alcohol Studies, University of North Carolina School of Medicine, Chapel Hill, NC, USA
| | - O J Hon
- Bowles Center for Alcohol Studies, University of North Carolina School of Medicine, Chapel Hill, NC, USA
- Curriculum in Neuroscience, University of North Carolina School of Medicine, Chapel Hill, NC, USA
| | - S D'Ambrosio
- Bowles Center for Alcohol Studies, University of North Carolina School of Medicine, Chapel Hill, NC, USA
| | - K M Boyt
- Bowles Center for Alcohol Studies, University of North Carolina School of Medicine, Chapel Hill, NC, USA
| | - L Hassanein
- Bowles Center for Alcohol Studies, University of North Carolina School of Medicine, Chapel Hill, NC, USA
| | - M Castle
- Bowles Center for Alcohol Studies, University of North Carolina School of Medicine, Chapel Hill, NC, USA
| | - H L Haun
- Bowles Center for Alcohol Studies, University of North Carolina School of Medicine, Chapel Hill, NC, USA
| | - M M Pina
- Bowles Center for Alcohol Studies, University of North Carolina School of Medicine, Chapel Hill, NC, USA
| | - T L Kash
- Bowles Center for Alcohol Studies, University of North Carolina School of Medicine, Chapel Hill, NC, USA.
- Department of Pharmacology, University of North Carolina School of Medicine, Chapel Hill, NC, USA.
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9
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Hingorani M, Viviani AML, Sanfilippo JE, Janušonis S. High-resolution spatiotemporal analysis of single serotonergic axons in an in vitro system. Front Neurosci 2022; 16:994735. [PMID: 36353595 PMCID: PMC9638127 DOI: 10.3389/fnins.2022.994735] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Accepted: 09/28/2022] [Indexed: 12/04/2022] Open
Abstract
Vertebrate brains have a dual structure, composed of (i) axons that can be well-captured with graph-theoretical methods and (ii) axons that form a dense matrix in which neurons with precise connections operate. A core part of this matrix is formed by axons (fibers) that store and release 5-hydroxytryptamine (5-HT, serotonin), an ancient neurotransmitter that supports neuroplasticity and has profound implications for mental health. The self-organization of the serotonergic matrix is not well understood, despite recent advances in experimental and theoretical approaches. In particular, individual serotonergic axons produce highly stochastic trajectories, fundamental to the construction of regional fiber densities, but further advances in predictive computer simulations require more accurate experimental information. This study examined single serotonergic axons in culture systems (co-cultures and monolayers), by using a set of complementary high-resolution methods: confocal microscopy, holotomography (refractive index-based live imaging), and super-resolution (STED) microscopy. It shows that serotonergic axon walks in neural tissue may strongly reflect the stochastic geometry of this tissue and it also provides new insights into the morphology and branching properties of serotonergic axons. The proposed experimental platform can support next-generation analyses of the serotonergic matrix, including seamless integration with supercomputing approaches.
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10
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Zhou WL, Kim K, Ali F, Pittenger ST, Calarco CA, Mineur YS, Ramakrishnan C, Deisseroth K, Kwan AC, Picciotto MR. Activity of a direct VTA to ventral pallidum GABA pathway encodes unconditioned reward value and sustains motivation for reward. SCIENCE ADVANCES 2022; 8:eabm5217. [PMID: 36260661 PMCID: PMC9581470 DOI: 10.1126/sciadv.abm5217] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Accepted: 09/01/2022] [Indexed: 05/28/2023]
Abstract
Dopamine signaling from the ventral tegmental area (VTA) plays critical roles in reward-related behaviors, but less is known about the functions of neighboring VTA GABAergic neurons. We show here that a primary target of VTA GABA projection neurons is the ventral pallidum (VP). Activity of VTA-to-VP-projecting GABA neurons correlates consistently with size and palatability of the reward and does not change following cue learning, providing a direct measure of reward value. Chemogenetic stimulation of this GABA projection increased activity of a subset of VP neurons that were active while mice were seeking reward. Optogenetic stimulation of this pathway improved performance in a cue-reward task and maintained motivation to work for reward over days. This VTA GABA projection provides information about reward value directly to the VP, likely distinct from the prediction error signal carried by VTA dopamine neurons.
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Affiliation(s)
- Wen-Liang Zhou
- Department of Psychiatry, Yale University, 34 Park Street, New Haven, CT 06508, USA
| | - Kristen Kim
- Interdepartmental Neuroscience Program, Yale School of Medicine, New Haven, CT 06520, USA
| | - Farhan Ali
- Department of Psychiatry, Yale University, 34 Park Street, New Haven, CT 06508, USA
| | - Steven T. Pittenger
- Department of Psychiatry, Yale University, 34 Park Street, New Haven, CT 06508, USA
| | - Cali A. Calarco
- Interdepartmental Neuroscience Program, Yale School of Medicine, New Haven, CT 06520, USA
| | - Yann S. Mineur
- Department of Psychiatry, Yale University, 34 Park Street, New Haven, CT 06508, USA
| | - Charu Ramakrishnan
- Department of Bioengineering, Stanford University, Stanford, CA 94305, USA
| | - Karl Deisseroth
- Department of Bioengineering, Stanford University, Stanford, CA 94305, USA
| | - Alex C. Kwan
- Department of Psychiatry, Yale University, 34 Park Street, New Haven, CT 06508, USA
| | - Marina R. Picciotto
- Department of Psychiatry, Yale University, 34 Park Street, New Haven, CT 06508, USA
- Kavli Institute for Neuroscience, Yale School of Medicine, New Haven, CT 06520, USA
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11
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Lee C, Zhang Z, Janušonis S. Brain serotonergic fibers suggest anomalous diffusion-based dropout in artificial neural networks. Front Neurosci 2022; 16:949934. [PMID: 36267232 PMCID: PMC9577023 DOI: 10.3389/fnins.2022.949934] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2022] [Accepted: 09/08/2022] [Indexed: 11/13/2022] Open
Abstract
Random dropout has become a standard regularization technique in artificial neural networks (ANNs), but it is currently unknown whether an analogous mechanism exists in biological neural networks (BioNNs). If it does, its structure is likely to be optimized by hundreds of millions of years of evolution, which may suggest novel dropout strategies in large-scale ANNs. We propose that the brain serotonergic fibers (axons) meet some of the expected criteria because of their ubiquitous presence, stochastic structure, and ability to grow throughout the individual's lifespan. Since the trajectories of serotonergic fibers can be modeled as paths of anomalous diffusion processes, in this proof-of-concept study we investigated a dropout algorithm based on the superdiffusive fractional Brownian motion (FBM). The results demonstrate that serotonergic fibers can potentially implement a dropout-like mechanism in brain tissue, supporting neuroplasticity. They also suggest that mathematical theories of the structure and dynamics of serotonergic fibers can contribute to the design of dropout algorithms in ANNs.
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Affiliation(s)
- Christian Lee
- Department of Electrical and Computer Engineering, University of California, Santa Barbara, Santa Barbara, CA, United States
| | - Zheng Zhang
- Department of Electrical and Computer Engineering, University of California, Santa Barbara, Santa Barbara, CA, United States
| | - Skirmantas Janušonis
- Department of Psychological and Brain Sciences, University of California, Santa Barbara, Santa Barbara, CA, United States
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12
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Fazekas CL, Szabó A, Török B, Bánrévi K, Correia P, Chaves T, Daumas S, Zelena D. A New Player in the Hippocampus: A Review on VGLUT3+ Neurons and Their Role in the Regulation of Hippocampal Activity and Behaviour. Int J Mol Sci 2022; 23:790. [PMID: 35054976 PMCID: PMC8775679 DOI: 10.3390/ijms23020790] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2021] [Revised: 01/06/2022] [Accepted: 01/08/2022] [Indexed: 01/05/2023] Open
Abstract
Glutamate is the most abundant excitatory amino acid in the central nervous system. Neurons using glutamate as a neurotransmitter can be characterised by vesicular glutamate transporters (VGLUTs). Among the three subtypes, VGLUT3 is unique, co-localising with other "classical" neurotransmitters, such as the inhibitory GABA. Glutamate, manipulated by VGLUT3, can modulate the packaging as well as the release of other neurotransmitters and serve as a retrograde signal through its release from the somata and dendrites. Its contribution to sensory processes (including seeing, hearing, and mechanosensation) is well characterised. However, its involvement in learning and memory can only be assumed based on its prominent hippocampal presence. Although VGLUT3-expressing neurons are detectable in the hippocampus, most of the hippocampal VGLUT3 positivity can be found on nerve terminals, presumably coming from the median raphe. This hippocampal glutamatergic network plays a pivotal role in several important processes (e.g., learning and memory, emotions, epilepsy, cardiovascular regulation). Indirect information from anatomical studies and KO mice strains suggests the contribution of local VGLUT3-positive hippocampal neurons as well as afferentations in these events. However, further studies making use of more specific tools (e.g., Cre-mice, opto- and chemogenetics) are needed to confirm these assumptions.
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Affiliation(s)
- Csilla Lea Fazekas
- Institute of Experimental Medicine, 1083 Budapest, Hungary; (C.L.F.); (A.S.); (B.T.); (K.B.); (P.C.); (T.C.)
- Centre for Neuroscience, Szentágothai Research Centre, Institute of Physiology, Medical School, University of Pécs, 7624 Pécs, Hungary
- János Szentágothai Doctoral School of Neurosciences, Semmelweis University, 1085 Budapest, Hungary
- Neuroscience Paris Seine-Institut de Biologie Paris Seine (NPS-IBPS) INSERM, Sorbonne Université, CNRS, 75005 Paris, France;
| | - Adrienn Szabó
- Institute of Experimental Medicine, 1083 Budapest, Hungary; (C.L.F.); (A.S.); (B.T.); (K.B.); (P.C.); (T.C.)
- Centre for Neuroscience, Szentágothai Research Centre, Institute of Physiology, Medical School, University of Pécs, 7624 Pécs, Hungary
- János Szentágothai Doctoral School of Neurosciences, Semmelweis University, 1085 Budapest, Hungary
| | - Bibiána Török
- Institute of Experimental Medicine, 1083 Budapest, Hungary; (C.L.F.); (A.S.); (B.T.); (K.B.); (P.C.); (T.C.)
- Centre for Neuroscience, Szentágothai Research Centre, Institute of Physiology, Medical School, University of Pécs, 7624 Pécs, Hungary
- János Szentágothai Doctoral School of Neurosciences, Semmelweis University, 1085 Budapest, Hungary
| | - Krisztina Bánrévi
- Institute of Experimental Medicine, 1083 Budapest, Hungary; (C.L.F.); (A.S.); (B.T.); (K.B.); (P.C.); (T.C.)
| | - Pedro Correia
- Institute of Experimental Medicine, 1083 Budapest, Hungary; (C.L.F.); (A.S.); (B.T.); (K.B.); (P.C.); (T.C.)
- Centre for Neuroscience, Szentágothai Research Centre, Institute of Physiology, Medical School, University of Pécs, 7624 Pécs, Hungary
- János Szentágothai Doctoral School of Neurosciences, Semmelweis University, 1085 Budapest, Hungary
| | - Tiago Chaves
- Institute of Experimental Medicine, 1083 Budapest, Hungary; (C.L.F.); (A.S.); (B.T.); (K.B.); (P.C.); (T.C.)
- Centre for Neuroscience, Szentágothai Research Centre, Institute of Physiology, Medical School, University of Pécs, 7624 Pécs, Hungary
- János Szentágothai Doctoral School of Neurosciences, Semmelweis University, 1085 Budapest, Hungary
| | - Stéphanie Daumas
- Neuroscience Paris Seine-Institut de Biologie Paris Seine (NPS-IBPS) INSERM, Sorbonne Université, CNRS, 75005 Paris, France;
| | - Dóra Zelena
- Institute of Experimental Medicine, 1083 Budapest, Hungary; (C.L.F.); (A.S.); (B.T.); (K.B.); (P.C.); (T.C.)
- Centre for Neuroscience, Szentágothai Research Centre, Institute of Physiology, Medical School, University of Pécs, 7624 Pécs, Hungary
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Cerebellin-2 regulates a serotonergic dorsal raphe circuit that controls compulsive behaviors. Mol Psychiatry 2021; 26:7509-7521. [PMID: 34158618 PMCID: PMC8692491 DOI: 10.1038/s41380-021-01187-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Accepted: 06/01/2021] [Indexed: 12/11/2022]
Abstract
Cerebellin-1 (Cbln1) and cerebellin-2 (Cbln2) are secreted glycoproteins that are expressed in distinct subsets of neurons throughout the brain. Cbln1 and Cbln2 simultaneously bind to presynaptic neurexins and postsynaptic GluD1 and GluD2, thereby forming trans-synaptic adhesion complexes. Genetic associations link cerebellins, neurexins and GluD's to neuropsychiatric disorders involving compulsive behaviors, such as Tourette syndrome, attention-deficit hyperactivity disorder (ADHD), and obsessive-compulsive disorder (OCD). Extensive evidence implicates dysfunction of serotonergic signaling in these neuropsychiatric disorders. Here, we report that constitutive Cbln2 KO mice, but not Cbln1 KO mice, display robust compulsive behaviors, including stereotypic pattern running, marble burying, explosive jumping, and excessive nest building, and exhibit decreased brain serotonin levels. Strikingly, treatment of Cbln2 KO mice with the serotonin precursor 5-hydroxytryptophan or the serotonin reuptake-inhibitor fluoxetine alleviated compulsive behaviors. Conditional deletion of Cbln2 both from dorsal raphe neurons and from presynaptic neurons synapsing onto dorsal raphe neurons reproduced the compulsive behaviors of Cbln2 KO mice. Finally, injection of recombinant Cbln2 protein into the dorsal raphe of Cbln2 KO mice largely reversed their compulsive behaviors. Taken together, our results show that Cbln2 controls compulsive behaviors by regulating serotonergic circuits in the dorsal raphe.
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Alexander C, Vasefi M. Cannabidiol and the corticoraphe circuit in post-traumatic stress disorder. IBRO Neurosci Rep 2021; 11:88-102. [PMID: 34485973 PMCID: PMC8408530 DOI: 10.1016/j.ibneur.2021.08.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Revised: 08/04/2021] [Accepted: 08/18/2021] [Indexed: 01/06/2023] Open
Abstract
Post-Traumatic Stress Disorder (PTSD), characterized by re-experiencing, avoidance, negative affect, and impaired memory processing, may develop after traumatic events. PTSD is complicated by impaired plasticity and medial prefrontal cortex (mPFC) activity, hyperactivity of the amygdala, and impaired fear extinction. Cannabidiol (CBD) is a promising candidate for treatment due to its multimodal action that enhances plasticity and calms hyperexcitability. CBD’s mechanism in the mPFC of PTSD patients has been explored extensively, but literature on the mechanism in the dorsal raphe nucleus (DRN) is lacking. Following the PRISMA guidelines, we examined current literature regarding CBD in PTSD and overlapping symptomologies to propose a mechanism by which CBD treats PTSD via corticoraphe circuit. Acute CBD inhibits excess 5-HT release from DRN to amygdala and releases anandamide (AEA) onto amygdala inputs. By first reducing amygdala and DRN hyperactivity, CBD begins to ameliorate activity disparity between mPFC and amygdala. Chronic CBD recruits the mPFC, creating harmonious corticoraphe signaling. DRN releases enough 5-HT to ameliorate mPFC hypoactivity, while the mPFC continuously excites DRN 5-HT neurons via glutamate. Meanwhile, AEA regulates corticoraphe activity to stabilize signaling. AEA prevents DRN GABAergic interneurons from inhibiting 5-HT release so the DRN can assist the mPFC in overcoming its hypoactivity. DRN-mediated restoration of mPFC activity underlies CBD’s mechanism on fear extinction and learning of stress coping. CBD reduces PTSD symptoms via the DRN and corticoraphe circuit. Acute effects of CBD reduce DRN-amygdala excitatory signaling to lessen the activity disparity between amygdala and mPFC. Chronic CBD officially resolves mPFC hypoactivity by facilitating 5-HT release from DRN to mPFC. CBD-facilitated endocannabinoid signaling stabilizes DRN activity and restores mPFC inhibitory control. Chronically administered CBD acts via the corticoraphe circuit to favor fear extinction over fear memory reconsolidation.
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Key Words
- 2-AG, 2-arachidonoylglycerol
- 5-HT, Serotonin
- 5-HT1AR, 5-HT Receptor Type 1A
- 5-HT2AR, 5-HT Receptor Type 2 A
- AEA, Anandamide
- CB1R, Cannabinoid Receptor Type 1
- CB2R, Cannabinoid Receptor Type 2
- CBD, Cannabidiol
- COVID-19, SARS-CoV-2
- Cannabidiol
- DRN, Dorsal Raphe Nucleus
- ERK1/2, Extracellular Signal-Related Kinases Type 1 or Type 2
- FAAH, Fatty Acid Amide Hydrolase
- GABA, Gamma-Aminobutyric Acid
- GPCRs, G-Protein Coupled Receptors
- NMDAR, N-Methyl-D-aspartate Receptors
- PET, Positron Emission Tomography
- PFC, DRN and Raphe
- PFC, Prefrontal Cortex
- PTSD
- PTSD, Post-Traumatic Stress Disorder
- SSNRI, Selective Norepinephrine Reuptake Inhibitor
- SSRI, Selective Serotonin Reuptake Inhibitor
- Serotonin
- TRPV1, Transient Receptor Potential Vanilloid 1 Channels
- Traumatic Stress
- fMRI, Functional Magnetic Resonance Imaging
- mPFC, Medial Prefrontal Cortex
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Affiliation(s)
- Claire Alexander
- Department of Biology, Lamar University, Beaumont, TX 77710, USA
| | - Maryam Vasefi
- Department of Biology, Lamar University, Beaumont, TX 77710, USA
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15
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Serotonergic control of the glutamatergic neurons of the subthalamic nucleus. PROGRESS IN BRAIN RESEARCH 2021; 261:423-462. [PMID: 33785138 DOI: 10.1016/bs.pbr.2020.11.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The subthalamic nucleus (STN) houses a dense cluster of glutamatergic neurons that play a central role in the functional dynamics of the basal ganglia, a group of subcortical structures involved in the control of motor behaviors. Numerous anatomical, electrophysiological, neurochemical and behavioral studies have reported that serotonergic neurons from the midbrain raphe nuclei modulate the activity of STN neurons. Here, we describe this serotonergic innervation and the nature of the regulation exerted by serotonin (5-hydroxytryptamine, 5-HT) on STN neuron activity. This regulation can occur either directly within the STN or at distal sites, including other structures of the basal ganglia or cortex. The effect of 5-HT on STN neuronal activity involves several 5-HT receptor subtypes, including 5-HT1A, 5-HT1B, 5-HT2C and 5-HT4 receptors, which have garnered the highest attention on this topic. The multiple regulatory effects exerted by 5-HT are thought to be modified under pathological conditions, altering the activity of the STN, or due to the benefits and side effects of treatments used for Parkinson's disease, notably the dopamine precursor l-DOPA and high-frequency STN stimulation. Originally understood as a motor center, the STN is also associated with decision making and participates in mood regulation and cognitive performance, two domains of personality that are also regulated by 5-HT. The literature concerning the link between 5-HT and STN is already important, and the functional overlap is evident, but this link is still not entirely understood. The understanding of this link between 5-HT and STN should be increased due to the possible importance of this regulation in the control of fronto-STN loops and inherent motor and non-motor behaviors.
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16
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Vahid-Ansari F, Albert PR. Rewiring of the Serotonin System in Major Depression. Front Psychiatry 2021; 12:802581. [PMID: 34975594 PMCID: PMC8716791 DOI: 10.3389/fpsyt.2021.802581] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Accepted: 11/17/2021] [Indexed: 12/14/2022] Open
Abstract
Serotonin is a key neurotransmitter that is implicated in a wide variety of behavioral and cognitive phenotypes. Originating in the raphe nuclei, 5-HT neurons project widely to innervate many brain regions implicated in the functions. During the development of the brain, as serotonin axons project and innervate brain regions, there is evidence that 5-HT plays key roles in wiring the developing brain, both by modulating 5-HT innervation and by influencing synaptic organization within corticolimbic structures. These actions are mediated by 14 different 5-HT receptors, with region- and cell-specific patterns of expression. More recently, the role of the 5-HT system in synaptic re-organization during adulthood has been suggested. The 5-HT neurons have the unusual capacity to regrow and reinnervate brain regions following insults such as brain injury, chronic stress, or altered development that result in disconnection of the 5-HT system and often cause depression, anxiety, and cognitive impairment. Chronic treatment with antidepressants that amplify 5-HT action, such as selective serotonin reuptake inhibitors (SSRIs), appears to accelerate the rewiring of the 5-HT system by mechanisms that may be critical to the behavioral and cognitive improvements induced in these models. In this review, we survey the possible 5-HT receptor mechanisms that could mediate 5-HT rewiring and assess the evidence that 5-HT-mediated brain rewiring is impacting recovery from mental illness. By amplifying 5-HT-induced rewiring processes using SSRIs and selective 5-HT agonists, more rapid and effective treatments for injury-induced mental illness or cognitive impairment may be achieved.
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Affiliation(s)
- Faranak Vahid-Ansari
- Ottawa Hospital Research Institute (Neuroscience), University of Ottawa Brain and Mind Research Institute, Ottawa, ON, Canada
| | - Paul R Albert
- Ottawa Hospital Research Institute (Neuroscience), University of Ottawa Brain and Mind Research Institute, Ottawa, ON, Canada
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17
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Alsiö J, Lehmann O, McKenzie C, Theobald DE, Searle L, Xia J, Dalley JW, Robbins TW. Serotonergic Innervations of the Orbitofrontal and Medial-prefrontal Cortices are Differentially Involved in Visual Discrimination and Reversal Learning in Rats. Cereb Cortex 2020; 31:1090-1105. [PMID: 33043981 PMCID: PMC7906782 DOI: 10.1093/cercor/bhaa277] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Revised: 08/26/2020] [Accepted: 08/27/2020] [Indexed: 12/19/2022] Open
Abstract
Cross-species studies have identified an evolutionarily conserved role for serotonin in flexible behavior including reversal learning. The aim of the current study was to investigate the contribution of serotonin within the orbitofrontal cortex (OFC) and medial prefrontal cortex (mPFC) to visual discrimination and reversal learning. Male Lister Hooded rats were trained to discriminate between a rewarded (A+) and a nonrewarded (B−) visual stimulus to receive sucrose rewards in touchscreen operant chambers. Serotonin was depleted using surgical infusions of 5,7-dihydroxytryptamine (5,7-DHT), either globally by intracebroventricular (i.c.v.) infusions or locally by microinfusions into the OFC or mPFC. Rats that received i.c.v. infusions of 5,7-DHT before initial training were significantly impaired during both visual discrimination and subsequent reversal learning during which the stimulus–reward contingencies were changed (A− vs. B+). Local serotonin depletion from the OFC impaired reversal learning without affecting initial discrimination. After mPFC depletion, rats were unimpaired during reversal learning but slower to respond at the stimuli during all the stages; the mPFC group was also slower to learn during discrimination than the OFC group. These findings extend our understanding of serotonin in cognitive flexibility by revealing differential effects within two subregions of the prefrontal cortex in visual discrimination and reversal learning.
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Affiliation(s)
- Johan Alsiö
- Department of Psychology, Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge CB2 3EB, UK
| | - Olivia Lehmann
- Department of Psychology, Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge CB2 3EB, UK
| | - Colin McKenzie
- Department of Psychology, Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge CB2 3EB, UK
| | - David E Theobald
- Department of Psychology, Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge CB2 3EB, UK
| | - Lydia Searle
- Department of Psychology, Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge CB2 3EB, UK
| | - Jing Xia
- Department of Psychology, Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge CB2 3EB, UK
| | - Jeffrey W Dalley
- Department of Psychology, Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge CB2 3EB, UK.,Department of Psychiatry, University of Cambridge, Cambridge CB2 0SZ, UK
| | - Trevor W Robbins
- Department of Psychology, Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge CB2 3EB, UK
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18
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Zahrai A, Vahid-Ansari F, Daigle M, Albert PR. Fluoxetine-induced recovery of serotonin and norepinephrine projections in a mouse model of post-stroke depression. Transl Psychiatry 2020; 10:334. [PMID: 32999279 PMCID: PMC7527452 DOI: 10.1038/s41398-020-01008-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Revised: 08/21/2020] [Accepted: 09/03/2020] [Indexed: 12/12/2022] Open
Abstract
Chronic treatment with fluoxetine (FLX) is required for its antidepressant effects, but the role of serotonin (5-HT) axonal plasticity in FLX action is unknown. To address this, we examined mice with a stroke in the left medial prefrontal cortex (mPFC) resulting in persistent anxiety-like and depression-like behaviors and memory deficits as a model of post-stroke depression. Chronic treatment with FLX (but not exercise) completely reversed the behavioral phenotype and partially reversed changes in FosB-labeled cells in the mPFC, nucleus accumbens, septum, hippocampus, basolateral amygdala (BLA), and dorsal raphe. In these regions, 5-HT or norepinephrine (NE) innervation was quantified by staining for 5-HT or NE transporters, respectively. 5-HT synapses and synaptic triads were identified as synaptophysin-stained sites on 5-HT axons located proximal to gephyrin-stained or PSD95-stained spines. A week after stroke, 5-HT innervation was greatly reduced at the stroke site (left cingulate gyrus (CG) of the mPFC) and the left BLA. Chronically, 5-HT and NE innervation was reduced at the left CG, nucleus accumbens, and BLA, with no changes in other regions. In these areas, pre-synaptic and post-synaptic 5-HT synapses and triads to inhibitory (gephyrin+) sites were reduced, while 5-HT contacts at excitatory (PSD95+) sites were reduced in the CG and prelimbic mPFC. Chronic FLX, but not exercise, reversed these reductions in 5-HT innervation but incompletely restored NE projections. Changes in 5-HT innervation were verified using YFP staining in mice expressing YFP-tagged channelrhodopsin in 5-HT neurons. Thus, FLX-induced 5-HT axonal neuroplasticity of forebrain projections may help mediate recovery from brain injury.
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Affiliation(s)
- Amin Zahrai
- grid.412687.e0000 0000 9606 5108Ottawa Hospital Research Institute (Neuroscience), UOttawa Brain and Mind Research Institute, 451 Smyth Road, Ottawa, ON K1H-8M5 Canada
| | - Faranak Vahid-Ansari
- grid.412687.e0000 0000 9606 5108Ottawa Hospital Research Institute (Neuroscience), UOttawa Brain and Mind Research Institute, 451 Smyth Road, Ottawa, ON K1H-8M5 Canada
| | - Mireille Daigle
- grid.412687.e0000 0000 9606 5108Ottawa Hospital Research Institute (Neuroscience), UOttawa Brain and Mind Research Institute, 451 Smyth Road, Ottawa, ON K1H-8M5 Canada
| | - Paul R. Albert
- grid.412687.e0000 0000 9606 5108Ottawa Hospital Research Institute (Neuroscience), UOttawa Brain and Mind Research Institute, 451 Smyth Road, Ottawa, ON K1H-8M5 Canada
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19
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Janušonis S, Detering N, Metzler R, Vojta T. Serotonergic Axons as Fractional Brownian Motion Paths: Insights Into the Self-Organization of Regional Densities. Front Comput Neurosci 2020; 14:56. [PMID: 32670042 PMCID: PMC7328445 DOI: 10.3389/fncom.2020.00056] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2019] [Accepted: 05/19/2020] [Indexed: 01/03/2023] Open
Abstract
All vertebrate brains contain a dense matrix of thin fibers that release serotonin (5-hydroxytryptamine), a neurotransmitter that modulates a wide range of neural, glial, and vascular processes. Perturbations in the density of this matrix have been associated with a number of mental disorders, including autism and depression, but its self-organization and plasticity remain poorly understood. We introduce a model based on reflected Fractional Brownian Motion (FBM), a rigorously defined stochastic process, and show that it recapitulates some key features of regional serotonergic fiber densities. Specifically, we use supercomputing simulations to model fibers as FBM-paths in two-dimensional brain-like domains and demonstrate that the resultant steady state distributions approximate the fiber distributions in physical brain sections immunostained for the serotonin transporter (a marker for serotonergic axons in the adult brain). We suggest that this framework can support predictive descriptions and manipulations of the serotonergic matrix and that it can be further extended to incorporate the detailed physical properties of the fibers and their environment.
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Affiliation(s)
- Skirmantas Janušonis
- Department of Psychological and Brain Sciences, University of California, Santa Barbara, Santa Barbara, CA, United States
| | - Nils Detering
- Department of Statistics and Applied Probability, University of California, Santa Barbara, Santa Barbara, CA, United States
| | - Ralf Metzler
- Institute of Physics and Astronomy, University of Potsdam, Potsdam, Germany
| | - Thomas Vojta
- Department of Physics, Missouri University of Science and Technology, Rolla, MO, United States
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20
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Okaty BW, Sturrock N, Escobedo Lozoya Y, Chang Y, Senft RA, Lyon KA, Alekseyenko OV, Dymecki SM. A single-cell transcriptomic and anatomic atlas of mouse dorsal raphe Pet1 neurons. eLife 2020; 9:e55523. [PMID: 32568072 PMCID: PMC7308082 DOI: 10.7554/elife.55523] [Citation(s) in RCA: 64] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Accepted: 06/09/2020] [Indexed: 12/12/2022] Open
Abstract
Among the brainstem raphe nuclei, the dorsal raphe nucleus (DR) contains the greatest number of Pet1-lineage neurons, a predominantly serotonergic group distributed throughout DR subdomains. These neurons collectively regulate diverse physiology and behavior and are often therapeutically targeted to treat affective disorders. Characterizing Pet1 neuron molecular heterogeneity and relating it to anatomy is vital for understanding DR functional organization, with potential to inform therapeutic separability. Here we use high-throughput and DR subdomain-targeted single-cell transcriptomics and intersectional genetic tools to map molecular and anatomical diversity of DR-Pet1 neurons. We describe up to fourteen neuron subtypes, many showing biased cell body distributions across the DR. We further show that P2ry1-Pet1 DR neurons - the most molecularly distinct subtype - possess unique efferent projections and electrophysiological properties. These data complement and extend previous DR characterizations, combining intersectional genetics with multiple transcriptomic modalities to achieve fine-scale molecular and anatomic identification of Pet1 neuron subtypes.
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Affiliation(s)
- Benjamin W Okaty
- Department of Genetics, Harvard Medical SchoolBostonUnited States
| | - Nikita Sturrock
- Department of Genetics, Harvard Medical SchoolBostonUnited States
| | | | - YoonJeung Chang
- Department of Genetics, Harvard Medical SchoolBostonUnited States
| | - Rebecca A Senft
- Department of Genetics, Harvard Medical SchoolBostonUnited States
| | - Krissy A Lyon
- Department of Genetics, Harvard Medical SchoolBostonUnited States
| | | | - Susan M Dymecki
- Department of Genetics, Harvard Medical SchoolBostonUnited States
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21
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Abstract
Neurons that synthesize and release 5-hydroxytryptamine (5-HT; serotonin) express a core set of genes that establish and maintain this neurotransmitter phenotype and distinguish these neurons from other brain cells. Beyond a shared 5-HTergic phenotype, these neurons display divergent cellular properties in relation to anatomy, morphology, hodology, electrophysiology and gene expression, including differential expression of molecules supporting co-transmission of additional neurotransmitters. This diversity suggests that functionally heterogeneous subtypes of 5-HT neurons exist, but linking subsets of these neurons to particular functions has been technically challenging. We discuss recent data from molecular genetic, genomic and functional methods that, when coupled with classical findings, yield a reframing of the 5-HT neuronal system as a conglomeration of diverse subsystems with potential to inspire novel, more targeted therapies for clinically distinct 5-HT-related disorders.
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22
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Role of the Serotonin Receptor 7 in Brain Plasticity: From Development to Disease. Int J Mol Sci 2020; 21:ijms21020505. [PMID: 31941109 PMCID: PMC7013427 DOI: 10.3390/ijms21020505] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Revised: 01/08/2020] [Accepted: 01/10/2020] [Indexed: 12/18/2022] Open
Abstract
Our knowledge on the plastic functions of the serotonin (5-HT) receptor subtype 7 (5-HT7R) in the brain physiology and pathology have advanced considerably in recent years. A wealth of data show that 5-HT7R is a key player in the establishment and remodeling of neuronal cytoarchitecture during development and in the mature brain, and its dysfunction is linked to neuropsychiatric and neurodevelopmental diseases. The involvement of this receptor in synaptic plasticity is further demonstrated by data showing that its activation allows the rescue of long-term potentiation (LTP) and long-term depression (LTD) deficits in various animal models of neurodevelopmental diseases. In addition, it is becoming clear that the 5-HT7R is involved in inflammatory intestinal diseases, modulates the function of immune cells, and is likely to play a role in the gut-brain axis. In this review, we will mainly focus on recent findings on this receptor’s role in the structural and synaptic plasticity of the mammalian brain, although we will also illustrate novel aspects highlighted in gastrointestinal (GI) tract and immune system.
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23
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Ren J, Isakova A, Friedmann D, Zeng J, Grutzner SM, Pun A, Zhao GQ, Kolluru SS, Wang R, Lin R, Li P, Li A, Raymond JL, Luo Q, Luo M, Quake SR, Luo L. Single-cell transcriptomes and whole-brain projections of serotonin neurons in the mouse dorsal and median raphe nuclei. eLife 2019; 8:e49424. [PMID: 31647409 PMCID: PMC6812963 DOI: 10.7554/elife.49424] [Citation(s) in RCA: 153] [Impact Index Per Article: 30.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Accepted: 10/12/2019] [Indexed: 12/11/2022] Open
Abstract
Serotonin neurons of the dorsal and median raphe nuclei (DR, MR) collectively innervate the entire forebrain and midbrain, modulating diverse physiology and behavior. To gain a fundamental understanding of their molecular heterogeneity, we used plate-based single-cell RNA-sequencing to generate a comprehensive dataset comprising eleven transcriptomically distinct serotonin neuron clusters. Systematic in situ hybridization mapped specific clusters to the principal DR, caudal DR, or MR. These transcriptomic clusters differentially express a rich repertoire of neuropeptides, receptors, ion channels, and transcription factors. We generated novel intersectional viral-genetic tools to access specific subpopulations. Whole-brain axonal projection mapping revealed that DR serotonin neurons co-expressing vesicular glutamate transporter-3 preferentially innervate the cortex, whereas those co-expressing thyrotropin-releasing hormone innervate subcortical regions in particular the hypothalamus. Reconstruction of 50 individual DR serotonin neurons revealed diverse and segregated axonal projection patterns at the single-cell level. Together, these results provide a molecular foundation of the heterogenous serotonin neuronal phenotypes.
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Affiliation(s)
- Jing Ren
- Department of Biology and Howard Hughes Medical InstituteStanford UniversityStanfordUnited States
| | - Alina Isakova
- Department of BioengineeringStanford UniversityStanfordUnited States
- Department of Applied PhysicsStanford UniversityStanfordUnited States
| | - Drew Friedmann
- Department of Biology and Howard Hughes Medical InstituteStanford UniversityStanfordUnited States
| | - Jiawei Zeng
- National Institute of Biological ScienceBeijingChina
| | - Sophie M Grutzner
- Department of Biology and Howard Hughes Medical InstituteStanford UniversityStanfordUnited States
| | - Albert Pun
- Department of Biology and Howard Hughes Medical InstituteStanford UniversityStanfordUnited States
| | - Grace Q Zhao
- Department of NeurobiologyStanford University School of MedicineStanfordUnited States
| | - Sai Saroja Kolluru
- Department of BioengineeringStanford UniversityStanfordUnited States
- Department of Applied PhysicsStanford UniversityStanfordUnited States
| | - Ruiyu Wang
- National Institute of Biological ScienceBeijingChina
| | - Rui Lin
- National Institute of Biological ScienceBeijingChina
| | - Pengcheng Li
- Britton Chance Center for Biomedical PhotonicsWuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology (HUST)WuhanChina
- HUST-Suzhou Institute for Brainsmatics, JITRI Institute for BrainsmaticsSuzhouChina
| | - Anan Li
- Britton Chance Center for Biomedical PhotonicsWuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology (HUST)WuhanChina
- HUST-Suzhou Institute for Brainsmatics, JITRI Institute for BrainsmaticsSuzhouChina
| | - Jennifer L Raymond
- Department of NeurobiologyStanford University School of MedicineStanfordUnited States
| | - Qingming Luo
- Britton Chance Center for Biomedical PhotonicsWuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology (HUST)WuhanChina
| | - Minmin Luo
- National Institute of Biological ScienceBeijingChina
- School of Life ScienceTsinghua UniversityBeijingChina
| | - Stephen R Quake
- Department of BioengineeringStanford UniversityStanfordUnited States
- Department of Applied PhysicsStanford UniversityStanfordUnited States
- Chan Zuckerberg BiohubSan FranciscoUnited States
| | - Liqun Luo
- Department of Biology and Howard Hughes Medical InstituteStanford UniversityStanfordUnited States
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24
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Cardozo Pinto DF, Yang H, Pollak Dorocic I, de Jong JW, Han VJ, Peck JR, Zhu Y, Liu C, Beier KT, Smidt MP, Lammel S. Characterization of transgenic mouse models targeting neuromodulatory systems reveals organizational principles of the dorsal raphe. Nat Commun 2019; 10:4633. [PMID: 31604921 PMCID: PMC6789139 DOI: 10.1038/s41467-019-12392-2] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2019] [Accepted: 09/09/2019] [Indexed: 11/17/2022] Open
Abstract
The dorsal raphe (DR) is a heterogeneous nucleus containing dopamine (DA), serotonin (5HT), γ-aminobutyric acid (GABA) and glutamate neurons. Consequently, investigations of DR circuitry require Cre-driver lines that restrict transgene expression to precisely defined cell populations. Here, we present a systematic evaluation of mouse lines targeting neuromodulatory cells in the DR. We find substantial differences in specificity between lines targeting DA neurons, and in penetrance between lines targeting 5HT neurons. Using these tools to map DR circuits, we show that populations of neurochemically distinct DR neurons are arranged in a stereotyped topographical pattern, send divergent projections to amygdala subnuclei, and differ in their presynaptic inputs. Importantly, targeting DR DA neurons using different mouse lines yielded both structural and functional differences in the neural circuits accessed. These results provide a refined model of DR organization and support a comparative, case-by-case evaluation of the suitability of transgenic tools for any experimental application.
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Affiliation(s)
- Daniel F Cardozo Pinto
- Department of Molecular and Cell Biology and Helen Wills Neuroscience Institute, University of California Berkeley, Berkeley, CA, 94720, USA
- Nancy Pritzker Laboratory, Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Stanford, CA, USA
| | - Hongbin Yang
- Department of Molecular and Cell Biology and Helen Wills Neuroscience Institute, University of California Berkeley, Berkeley, CA, 94720, USA
| | - Iskra Pollak Dorocic
- Department of Molecular and Cell Biology and Helen Wills Neuroscience Institute, University of California Berkeley, Berkeley, CA, 94720, USA
| | - Johannes W de Jong
- Department of Molecular and Cell Biology and Helen Wills Neuroscience Institute, University of California Berkeley, Berkeley, CA, 94720, USA
| | - Vivian J Han
- Department of Molecular and Cell Biology and Helen Wills Neuroscience Institute, University of California Berkeley, Berkeley, CA, 94720, USA
| | - James R Peck
- Department of Molecular and Cell Biology and Helen Wills Neuroscience Institute, University of California Berkeley, Berkeley, CA, 94720, USA
| | - Yichen Zhu
- Department of Molecular and Cell Biology and Helen Wills Neuroscience Institute, University of California Berkeley, Berkeley, CA, 94720, USA
| | - Christine Liu
- Department of Molecular and Cell Biology and Helen Wills Neuroscience Institute, University of California Berkeley, Berkeley, CA, 94720, USA
| | - Kevin T Beier
- Departments of Physiology and Biophysics, Center for the Neurobiology of Learning and Memory, University of California Irvine, Irvine, CA, 92697, USA
| | - Marten P Smidt
- Swammerdam Institute for Life Sciences, FNWI University of Amsterdam, Amsterdam, The Netherlands
| | - Stephan Lammel
- Department of Molecular and Cell Biology and Helen Wills Neuroscience Institute, University of California Berkeley, Berkeley, CA, 94720, USA.
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25
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Huang KW, Ochandarena NE, Philson AC, Hyun M, Birnbaum JE, Cicconet M, Sabatini BL. Molecular and anatomical organization of the dorsal raphe nucleus. eLife 2019; 8:e46464. [PMID: 31411560 PMCID: PMC6726424 DOI: 10.7554/elife.46464] [Citation(s) in RCA: 127] [Impact Index Per Article: 25.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Accepted: 08/13/2019] [Indexed: 12/20/2022] Open
Abstract
The dorsal raphe nucleus (DRN) is an important source of neuromodulators and has been implicated in a wide variety of behavioral and neurological disorders. The DRN is subdivided into distinct anatomical subregions comprised of multiple cell types, and its complex cellular organization has impeded efforts to investigate the distinct circuit and behavioral functions of its subdomains. Here we used single-cell RNA sequencing, in situ hybridization, anatomical tracing, and spatial correlation analysis to map the transcriptional and spatial profiles of cells from the mouse DRN. Our analysis of 39,411 single-cell transcriptomes revealed at least 18 distinct neuron subtypes and 5 serotonergic neuron subtypes with distinct molecular and anatomical properties, including a serotonergic neuron subtype that preferentially innervates the basal ganglia. Our study lays out the molecular organization of distinct serotonergic and non-serotonergic subsystems, and will facilitate the design of strategies for further dissection of the DRN and its diverse functions.
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Affiliation(s)
- Kee Wui Huang
- Department of NeurobiologyHoward Hughes Medical Institute, Harvard Medical SchoolBostonUnited States
| | - Nicole E Ochandarena
- Department of NeurobiologyHoward Hughes Medical Institute, Harvard Medical SchoolBostonUnited States
| | - Adrienne C Philson
- Department of NeurobiologyHoward Hughes Medical Institute, Harvard Medical SchoolBostonUnited States
| | - Minsuk Hyun
- Department of NeurobiologyHoward Hughes Medical Institute, Harvard Medical SchoolBostonUnited States
| | - Jaclyn E Birnbaum
- Department of NeurobiologyHoward Hughes Medical Institute, Harvard Medical SchoolBostonUnited States
| | - Marcelo Cicconet
- Image and Data Analysis CoreHarvard Medical SchoolBostonUnited States
| | - Bernardo L Sabatini
- Department of NeurobiologyHoward Hughes Medical Institute, Harvard Medical SchoolBostonUnited States
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26
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Donovan LJ, Spencer WC, Kitt MM, Eastman BA, Lobur KJ, Jiao K, Silver J, Deneris ES. Lmx1b is required at multiple stages to build expansive serotonergic axon architectures. eLife 2019; 8:e48788. [PMID: 31355748 PMCID: PMC6685705 DOI: 10.7554/elife.48788] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Accepted: 07/27/2019] [Indexed: 01/18/2023] Open
Abstract
Formation of long-range axons occurs over multiple stages of morphological maturation. However, the intrinsic transcriptional mechanisms that temporally control different stages of axon projection development are unknown. Here, we addressed this question by studying the formation of mouse serotonin (5-HT) axons, the exemplar of long-range profusely arborized axon architectures. We report that LIM homeodomain factor 1b (Lmx1b)-deficient 5-HT neurons fail to generate axonal projections to the forebrain and spinal cord. Stage-specific targeting demonstrates that Lmx1b is required at successive stages to control 5-HT axon primary outgrowth, selective routing, and terminal arborization. We show a Lmx1b→Pet1 regulatory cascade is temporally required for 5-HT arborization and upregulation of the 5-HT axon arborization gene, Protocadherin-alphac2, during postnatal development of forebrain 5-HT axons. Our findings identify a temporal regulatory mechanism in which a single continuously expressed transcription factor functions at successive stages to orchestrate the progressive development of long-range axon architectures enabling expansive neuromodulation.
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Affiliation(s)
- Lauren J Donovan
- Department of NeurosciencesSchool of Medicine, Case Western Reserve UniversityClevelandUnited States
| | - William C Spencer
- Department of NeurosciencesSchool of Medicine, Case Western Reserve UniversityClevelandUnited States
| | - Meagan M Kitt
- Department of NeurosciencesSchool of Medicine, Case Western Reserve UniversityClevelandUnited States
| | - Brent A Eastman
- Department of NeurosciencesSchool of Medicine, Case Western Reserve UniversityClevelandUnited States
| | - Katherine J Lobur
- Department of NeurosciencesSchool of Medicine, Case Western Reserve UniversityClevelandUnited States
| | - Kexin Jiao
- Department of NeurosciencesSchool of Medicine, Case Western Reserve UniversityClevelandUnited States
| | - Jerry Silver
- Department of NeurosciencesSchool of Medicine, Case Western Reserve UniversityClevelandUnited States
| | - Evan S Deneris
- Department of NeurosciencesSchool of Medicine, Case Western Reserve UniversityClevelandUnited States
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27
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Zhang X, Coates K, Dacks A, Günay C, Lauritzen JS, Li F, Calle-Schuler SA, Bock D, Gaudry Q. Local synaptic inputs support opposing, network-specific odor representations in a widely projecting modulatory neuron. eLife 2019; 8:46839. [PMID: 31264962 PMCID: PMC6660217 DOI: 10.7554/elife.46839] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2019] [Accepted: 07/01/2019] [Indexed: 12/14/2022] Open
Abstract
Serotonin plays different roles across networks within the same sensory modality. Previously, we used whole-cell electrophysiology in Drosophila to show that serotonergic neurons innervating the first olfactory relay are inhibited by odorants (Zhang and Gaudry, 2016). Here we show that network-spanning serotonergic neurons segregate information about stimulus features, odor intensity and identity, by using opposing coding schemes in different olfactory neuropil. A pair of serotonergic neurons (the CSDns) innervate the antennal lobe and lateral horn, which are first and second order neuropils. CSDn processes in the antennal lobe are inhibited by odors in an identity independent manner. In the lateral horn, CSDn processes are excited in an odor identity dependent manner. Using functional imaging, modeling, and EM reconstruction, we demonstrate that antennal lobe derived inhibition arises from local GABAergic inputs and acts as a means of gain control on branch-specific inputs that the CSDns receive within the lateral horn.
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Affiliation(s)
- Xiaonan Zhang
- Department of Biology, University of Maryland, College Park, United States
| | - Kaylynn Coates
- Department of Biology, West Virginia University, Morgantown, United States
| | - Andrew Dacks
- Department of Biology, West Virginia University, Morgantown, United States
| | - Cengiz Günay
- School of Science and Technology, Georgia Gwinnett College, Lawrenceville, United States
| | - J Scott Lauritzen
- Janelia Farm Research Campus, Howard Hughes Medical Institute, Ashburn, United States
| | - Feng Li
- Janelia Farm Research Campus, Howard Hughes Medical Institute, Ashburn, United States
| | | | - Davi Bock
- Janelia Farm Research Campus, Howard Hughes Medical Institute, Ashburn, United States.,Department of Neurological Sciences, Larner College of Medicine, University of Vermont, Burlington, United States
| | - Quentin Gaudry
- Department of Biology, University of Maryland, College Park, United States
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28
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Sengupta A, Holmes A. A Discrete Dorsal Raphe to Basal Amygdala 5-HT Circuit Calibrates Aversive Memory. Neuron 2019; 103:489-505.e7. [PMID: 31204082 DOI: 10.1016/j.neuron.2019.05.029] [Citation(s) in RCA: 64] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2018] [Revised: 02/14/2019] [Accepted: 05/15/2019] [Indexed: 11/26/2022]
Abstract
Despite a wealth of clinical and preclinical data implicating the serotonin (5-HT) system in fear-related affective disorders, a precise definition of this neuromodulator's role in fear remains elusive. Using convergent anatomical and functional approaches, we interrogate the contribution to fear of basal amygdala (BA) 5-HT inputs from the dorsal raphe nucleus (DRN). We show the DRN→BA 5-HT pathway is engaged during fear memory formation and retrieval, and activity of these projections facilitates fear and impairs extinction. The DRN→BA 5-HT pathway amplifies fear-associated BA neuronal firing and theta power and phase-locking. Although fear recruits 5-HT and VGluT3 co-expressing DRN neurons, the fear-potentiating influence of the DRN→BA 5-HT pathway requires signaling at BA 5-HT1A/2A receptors. Input-output mapping illustrates how the DRN→BA 5-HT pathway is anatomically distinct and connected with other brain regions that mediate fear. These findings reveal how a discrete 5-HT circuit orchestrates a broader neural network to calibrate aversive memory.
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Affiliation(s)
- Ayesha Sengupta
- Laboratory of Behavioral and Genomic Neuroscience, National Institute on Alcohol Abuse and Alcoholism, Rockville, MD, USA.
| | - Andrew Holmes
- Laboratory of Behavioral and Genomic Neuroscience, National Institute on Alcohol Abuse and Alcoholism, Rockville, MD, USA.
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29
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Belmer A, Beecher K, Jacques A, Patkar OL, Sicherre F, Bartlett SE. Axonal Non-segregation of the Vesicular Glutamate Transporter VGLUT3 Within Serotonergic Projections in the Mouse Forebrain. Front Cell Neurosci 2019; 13:193. [PMID: 31133811 PMCID: PMC6523995 DOI: 10.3389/fncel.2019.00193] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2019] [Accepted: 04/17/2019] [Indexed: 11/13/2022] Open
Abstract
A subpopulation of raphe 5-HT neurons expresses the vesicular glutamate transporter VGLUT3 with the co-release of glutamate and serotonin proposed to play a pivotal role in encoding reward- and anxiety-related behaviors. Serotonin axons are identifiable by immunolabeling of either serotonin (5-HT) or the plasma membrane 5-HT transporter (SERT), with SERT labeling demonstrated to be only partially overlapping with 5-HT staining. Studies investigating the colocalization or segregation of VGLUT3 within SERT or 5-HT immunolabeled boutons have led to inconsistent results. Therefore, we combined immunohistochemistry, high resolution confocal imaging, and 3D-reconstruction techniques to map and quantify the distribution of VGLUT3 immunoreactive boutons within 5-HT vs. SERT-positive axons in various regions of the mouse forebrain, including the prefrontal cortex, nucleus accumbens core and shell, bed nucleus of the stria terminalis, dorsal striatum, lateral septum, basolateral and central amygdala, and hippocampus. Our results demonstrate that about 90% of 5-HT boutons are colocalized with SERT in almost all the brain regions studied, which therefore reveals that VGLUT3 and SERT do not segregate. However, in the posterior part of the NAC shell, we confirmed the presence of a subtype of 5-HT immunoreactive axons that lack the SERT. Interestingly, about 90% of the 5-HT/VGLUT3 boutons were labeled for the SERT in this region, suggesting that VGLUT3 is preferentially located in SERT immunoreactive 5-HT boutons. This work demonstrates that VGLUT3 and SERT cannot be used as specific markers to classify the different subtypes of 5-HT axons.
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Affiliation(s)
- Arnauld Belmer
- Translational Research Institute, Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, QLD, Australia
| | - Kate Beecher
- Translational Research Institute, Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, QLD, Australia
| | - Angela Jacques
- Translational Research Institute, Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, QLD, Australia
| | - Omkar L Patkar
- QIMR Berghofer Medical Research Institute, Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, QLD, Australia
| | - Florian Sicherre
- Biologie Integrative et Physiologie, Université Pierre et Marie Curie, Paris, France
| | - Selena E Bartlett
- Translational Research Institute, Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, QLD, Australia
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30
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Vahid-Ansari F, Zhang M, Zahrai A, Albert PR. Overcoming Resistance to Selective Serotonin Reuptake Inhibitors: Targeting Serotonin, Serotonin-1A Receptors and Adult Neuroplasticity. Front Neurosci 2019; 13:404. [PMID: 31114473 PMCID: PMC6502905 DOI: 10.3389/fnins.2019.00404] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2018] [Accepted: 04/09/2019] [Indexed: 12/14/2022] Open
Abstract
Major depressive disorder (MDD) is the most prevalent mental illness contributing to global disease burden. Selective serotonin (5-HT) reuptake inhibitors (SSRIs) are the first-line treatment for MDD, but are only fully effective in 30% of patients and require weeks before improvement may be seen. About 30% of SSRI-resistant patients may respond to augmentation or switching to another antidepressant, often selected by trial and error. Hence a better understanding of the causes of SSRI resistance is needed to provide models for optimizing treatment. Since SSRIs enhance 5-HT, in this review we discuss new findings on the circuitry, development and function of the 5-HT system in modulating behavior, and on how 5-HT neuronal activity is regulated. We focus on the 5-HT1A autoreceptor, which controls 5-HT activity, and the 5-HT1A heteroreceptor that mediates 5-HT actions. A series of mice models now implicate increased levels of 5-HT1A autoreceptors in SSRI resistance, and the requirement of hippocampal 5-HT1A heteroreceptor for neurogenic and behavioral response to SSRIs. We also present clinical data that show promise for identifying biomarkers of 5-HT activity, 5-HT1A regulation and regional changes in brain activity in MDD patients that may provide biomarkers for tailored interventions to overcome or bypass resistance to SSRI treatment. We identify a series of potential strategies including inhibiting 5-HT auto-inhibition, stimulating 5-HT1A heteroreceptors, other monoamine systems, or cortical stimulation to overcome SSRI resistance.
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Affiliation(s)
| | | | | | - Paul R. Albert
- Brain and Mind Research Institute, Ottawa Hospital Research Institute (Neuroscience), University of Ottawa, Ottawa, ON, Canada
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31
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Trudeau LE, El Mestikawy S. Glutamate Cotransmission in Cholinergic, GABAergic and Monoamine Systems: Contrasts and Commonalities. Front Neural Circuits 2018; 12:113. [PMID: 30618649 PMCID: PMC6305298 DOI: 10.3389/fncir.2018.00113] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2018] [Accepted: 12/03/2018] [Indexed: 11/13/2022] Open
Abstract
Multiple discoveries made since the identification of vesicular glutamate transporters (VGLUTs) two decades ago revealed that many neuronal populations in the brain use glutamate in addition to their "primary" neurotransmitter. Such a mode of cotransmission has been detected in dopamine (DA), acetylcholine (ACh), serotonin (5-HT), norepinephrine (NE) and surprisingly even in GABA neurons. Interestingly, work performed by multiple groups during the past decade suggests that the use of glutamate as a cotransmitter takes different forms in these different populations of neurons. In the present review, we will provide an overview of glutamate cotransmission in these different classes of neurons, highlighting puzzling differences in: (1) the proportion of such neurons expressing a VGLUT in different brain regions and at different stages of development; (2) the sub-cellular localization of the VGLUT; (3) the localization of the VGLUT in relation to the neurons' other vesicular transporter; and (4) the functional role of glutamate cotransmission.
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Affiliation(s)
- Louis-Eric Trudeau
- CNS Research Group, Department of Pharmacology and Physiology, Department of Neurosciences, Faculty of Medicine, Université de Montréal, Montreal, QC, Canada
| | - Salah El Mestikawy
- Department of Psychiatry, Faculty of Medicine, Douglas Mental Health University Institute, McGill University, Montreal, QC, Canada.,Sorbonne Universités, Université Pierre et Marie Curie UM 119-CNRS UMR 8246-INSERM U1130, Neurosciences Paris Seine-Institut de Biologie Paris Seine (NPS-IBPS), Paris, France
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32
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Ren J, Friedmann D, Xiong J, Liu CD, Ferguson BR, Weerakkody T, DeLoach KE, Ran C, Pun A, Sun Y, Weissbourd B, Neve RL, Huguenard J, Horowitz MA, Luo L. Anatomically Defined and Functionally Distinct Dorsal Raphe Serotonin Sub-systems. Cell 2018; 175:472-487.e20. [PMID: 30146164 PMCID: PMC6173627 DOI: 10.1016/j.cell.2018.07.043] [Citation(s) in RCA: 248] [Impact Index Per Article: 41.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2018] [Revised: 07/01/2018] [Accepted: 07/25/2018] [Indexed: 01/21/2023]
Abstract
The dorsal raphe (DR) constitutes a major serotonergic input to the forebrain and modulates diverse functions and brain states, including mood, anxiety, and sensory and motor functions. Most functional studies to date have treated DR serotonin neurons as a single population. Using viral-genetic methods, we found that subcortical- and cortical-projecting serotonin neurons have distinct cell-body distributions within the DR and differentially co-express a vesicular glutamate transporter. Further, amygdala- and frontal-cortex-projecting DR serotonin neurons have largely complementary whole-brain collateralization patterns, receive biased inputs from presynaptic partners, and exhibit opposite responses to aversive stimuli. Gain- and loss-of-function experiments suggest that amygdala-projecting DR serotonin neurons promote anxiety-like behavior, whereas frontal-cortex-projecting neurons promote active coping in the face of challenge. These results provide compelling evidence that the DR serotonin system contains parallel sub-systems that differ in input and output connectivity, physiological response properties, and behavioral functions.
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Affiliation(s)
- Jing Ren
- Department of Biology and Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
| | - Drew Friedmann
- Department of Biology and Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
| | - Jing Xiong
- Department of Electrical Engineering, Stanford University, Stanford, CA 94305, USA
| | - Cindy D Liu
- Department of Biology and Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
| | - Brielle R Ferguson
- Department of Neurology and Neurological Sciences, Stanford, CA 94305, USA
| | - Tanya Weerakkody
- Department of Neurology and Neurological Sciences, Stanford, CA 94305, USA
| | - Katherine E DeLoach
- Department of Biology and Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
| | - Chen Ran
- Department of Biology and Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
| | - Albert Pun
- Department of Biology and Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
| | - Yanwen Sun
- Department of Physics, Stanford University, Stanford, CA 94305, USA
| | - Brandon Weissbourd
- Department of Biology and Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
| | - Rachael L Neve
- Delivery Technology Core, Massachusetts General Hospital, Cambridge, MA 02139, USA
| | - John Huguenard
- Department of Neurology and Neurological Sciences, Stanford, CA 94305, USA
| | - Mark A Horowitz
- Department of Electrical Engineering, Stanford University, Stanford, CA 94305, USA
| | - Liqun Luo
- Department of Biology and Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA.
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33
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Single-axon tracing of the corticosubthalamic hyperdirect pathway in primates. Brain Struct Funct 2018; 223:3959-3973. [PMID: 30109491 DOI: 10.1007/s00429-018-1726-x] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Accepted: 08/01/2018] [Indexed: 12/20/2022]
Abstract
Individual axons that form the hyperdirect pathway in Macaca fascicularis were visualized following microiontophoretic injections of biotinylated dextran amine in layer V of the primary motor cortex (M1). Twenty-eight singly labeled axons were reconstructed in 3D from serial sections. The M1 innervation of the subthalamic nucleus (STN) arises essentially from collaterals of long-ranged corticofugal axons en route to lower brainstem regions. Typically, after leaving M1, these large caliber axons (2-3 µm) enter the internal capsule and travel between caudate nucleus and putamen without providing any collateral to the striatum. More ventrally, they emit a thin collateral (0.5-1.5 µm) that runs lateromedially within the dorsal region of the STN, providing boutons en passant in the sensorimotor territory of the nucleus. In some cases, the medial tip of the collateral enters the lenticular fasciculus dorsally and yields a few beaded axonal branches in the zona incerta. In other cases, the collateral runs caudally and innervates the ventrolateral region of the red nucleus where large axon varicosities (up to 1.7 µm in diameter) are observed, many displaying perisomatic arrangements. Our ultrastructural analysis reveals a high synaptic incidence (141%) of cortical VGluT1-immunoreactive axon varicosities on distal dendrites of STN neurons, and on various afferent axons. Our single-axon reconstructions demonstrate that the so-called hyperdirect pathway derives essentially from collaterals of long-ranged corticofugal axons that are rarely exclusively devoted to the STN, as they also innervate the red nucleus and/or the zona incerta.
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34
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Balázsfi D, Zelena D, Demeter K, Miskolczi C, Varga ZK, Nagyváradi Á, Nyíri G, Cserép C, Baranyi M, Sperlágh B, Haller J. Differential Roles of the Two Raphe Nuclei in Amiable Social Behavior and Aggression - An Optogenetic Study. Front Behav Neurosci 2018; 12:163. [PMID: 30116182 PMCID: PMC6082963 DOI: 10.3389/fnbeh.2018.00163] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2017] [Accepted: 07/11/2018] [Indexed: 01/10/2023] Open
Abstract
Serotonergic mechanisms hosted by raphe nuclei have important roles in affiliative and agonistic behaviors but the separate roles of the two nuclei are poorly understood. Here we studied the roles of the dorsal (DR) and median raphe region (MRR) in aggression by optogenetically stimulating the two nuclei. Mice received three 3 min-long stimulations, which were separated by non-stimulation periods of 3 min. The stimulation of the MRR decreased aggression in a phasic-like manner. Effects were rapidly expressed during stimulations, and vanished similarly fast when stimulations were halted. No carryover effects were observed in the subsequent three trials performed at 2-day intervals. No effects on social behaviors were observed. By contrast, DR stimulation rapidly and tonically promoted social behaviors: effects were present during both the stimulation and non-stimulation periods of intermittent stimulations. Aggressive behaviors were marginally diminished by acute DR stimulations, but repeated stimulations administered over 8 days considerably decreased aggression even in the absence of concurrent stimulations, indicating the emergence of carryover effects. No such effects were observed in the case of social behaviors. We also investigated stimulation-induced neurotransmitter release in the prefrontal cortex, a major site of aggression control. MRR stimulation rapidly but transiently increased serotonin release, and induced a lasting increase in glutamate levels. DR stimulation had no effect on glutamate, but elicited a lasting increase of serotonin release. Prefrontal serotonin levels remained elevated for at least 2 h subsequent to DR stimulations. The stimulation of both nuclei increased GABA release rapidly and transiently. Thus, differential behavioral effects of the two raphe nuclei were associated with differences in their neurotransmission profiles. These findings reveal a surprisingly strong behavioral task division between the two raphe nuclei, which was associated with a nucleus-specific neurotransmitter release in the prefrontal cortex.
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Affiliation(s)
- Diána Balázsfi
- Laboratory of Behavioural and Stress Studies, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary.,János Szentágothai School of Neurosciences, Semmelweis University, Budapest, Hungary
| | - Dóra Zelena
- Laboratory of Behavioural and Stress Studies, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary
| | - Kornél Demeter
- Laboratory of Behavioural and Stress Studies, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary
| | - Christina Miskolczi
- Laboratory of Behavioural and Stress Studies, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary.,János Szentágothai School of Neurosciences, Semmelweis University, Budapest, Hungary
| | - Zoltán K Varga
- Laboratory of Behavioural and Stress Studies, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary.,János Szentágothai School of Neurosciences, Semmelweis University, Budapest, Hungary
| | - Ádám Nagyváradi
- Laboratory of Behavioural and Stress Studies, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary
| | - Gábor Nyíri
- Laboratory of Cerebral Cortex Research, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary
| | - Csaba Cserép
- János Szentágothai School of Neurosciences, Semmelweis University, Budapest, Hungary.,Laboratory of Cerebral Cortex Research, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary
| | - Mária Baranyi
- Laboratory of Molecular Pharmacology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary
| | - Beáta Sperlágh
- Laboratory of Molecular Pharmacology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary
| | - József Haller
- Laboratory of Behavioural and Stress Studies, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary.,Institute of Behavioural Sciences and Law Enforcement, National University of Public Service, Budapest, Hungary
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35
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Abstract
Multiple mechanisms have been identified as relevant to plasticity, functional stability, and reliable processing across brain states. In the context of stability under "ever-changing conditions" (this Topic), the role of axons has been relatively under-investigated. The highly branched topologies of many axons, however, seem well designed to differentially recruit and regulate distributed postsynaptic groups, possibly in a state-dependent fashion. In this Perspective, I briefly discuss several examples of axon collateralization, and then some of the branch-specific features that might subserve differential recruitment and whole brain activation. An emerging principle is that the number of collaterals and number of target structures are not stereotyped. Rather, axons originating from one defined source typically send branches to diversified subsets of target areas. This could achieve heterogeneous inputs, with different degrees of synchronicity. Variability of neuronal responses has been suggested as inversely proportional to the degree of temporally correlated input. Increased input homogeneity, driven by sensory stimulation or behavioral conditions, is reported to reduce neuronal variability, with axon collateralization potentially having an important role.
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Affiliation(s)
- Kathleen S Rockland
- Department of Anatomy and Neurobiology, Boston University School of Medicine, Boston, MA, United States
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Giguère N, Burke Nanni S, Trudeau LE. On Cell Loss and Selective Vulnerability of Neuronal Populations in Parkinson's Disease. Front Neurol 2018; 9:455. [PMID: 29971039 PMCID: PMC6018545 DOI: 10.3389/fneur.2018.00455] [Citation(s) in RCA: 241] [Impact Index Per Article: 40.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2018] [Accepted: 05/29/2018] [Indexed: 12/21/2022] Open
Abstract
Significant advances have been made uncovering the factors that render neurons vulnerable in Parkinson's disease (PD). However, the critical pathogenic events leading to cell loss remain poorly understood, complicating the development of disease-modifying interventions. Given that the cardinal motor symptoms and pathology of PD involve the loss of dopamine (DA) neurons of the substantia nigra pars compacta (SNc), a majority of the work in the PD field has focused on this specific neuronal population. PD however, is not a disease of DA neurons exclusively: pathology, most notably in the form of Lewy bodies and neurites, has been reported in multiple regions of the central and peripheral nervous system, including for example the locus coeruleus, the dorsal raphe nucleus and the dorsal motor nucleus of the vagus. Cell and/or terminal loss of these additional nuclei is likely to contribute to some of the other symptoms of PD and, most notably to the non-motor features. However, exactly which regions show actual, well-documented, cell loss is presently unclear. In this review we will first examine the strength of the evidence describing the regions of cell loss in idiopathic PD, as well as the order in which this loss occurs. Secondly, we will discuss the neurochemical, morphological and physiological characteristics that render SNc DA neurons vulnerable, and will examine the evidence for these characteristics being shared across PD-affected neuronal populations. The insights raised by focusing on the underpinnings of the selective vulnerability of neurons in PD might be helpful to facilitate the development of new disease-modifying strategies and improve animal models of the disease.
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Affiliation(s)
- Nicolas Giguère
- CNS Research Group, Department of Pharmacology and Physiology, Department of Neurosciences, Faculty of Medicine, Université de Montréal, Montreal, QC, Canada
| | - Samuel Burke Nanni
- CNS Research Group, Department of Pharmacology and Physiology, Department of Neurosciences, Faculty of Medicine, Université de Montréal, Montreal, QC, Canada
| | - Louis-Eric Trudeau
- CNS Research Group, Department of Pharmacology and Physiology, Department of Neurosciences, Faculty of Medicine, Université de Montréal, Montreal, QC, Canada
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Gagnon D, Eid L, Coudé D, Whissel C, Di Paolo T, Parent A, Parent M. Evidence for Sprouting of Dopamine and Serotonin Axons in the Pallidum of Parkinsonian Monkeys. Front Neuroanat 2018; 12:38. [PMID: 29867377 PMCID: PMC5963193 DOI: 10.3389/fnana.2018.00038] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Accepted: 04/25/2018] [Indexed: 12/25/2022] Open
Abstract
This light and electron microscopie immunohistochemical quantitative study aimed at determining the state of the dopamine (DA) and serotonin (5-HT) innervations of the internal (GPi) and external (GPe) segments of the pallidum in cynomolgus monkeys (Macaca fascicularis) rendered parkinsonian by systemic injections of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). In contrast to the prominent DA denervation of striatum, the GPi in MPTP monkeys was found to be markedly enriched in DA (TH+) axon varicosities. The posterior sensorimotor region of this major output structure of the basal ganglia was about 8 times more intensely innervated in MPTP monkeys (0.71 ± 0.08 × 106 TH+ axon varicosities/mm3) than in controls (0.09 ± 0.01 × 106). MPTP intoxication also induced a two-fold increase in the density of 5-HT (SERT+) axon varicosities in both GPe and GPi. This augmentation was particularly pronounced anteriorly in the so-called associative and limbic pallidal territories. The total length of the labeled pallidal axons was also significantly increased in MPTP monkeys compared to controls, but the number of DA and 5-HT axon varicosities per axon length unit remained the same in the two groups, indicating that the DA and 5-HT pallidal hyperinnervations seen in MPTP monkeys result from axon sprouting rather than from the appearance of newly formed axon varicosities on non-growing axons. At the ultrastructural level, pallidal TH+ and SERT+ axons were morphologically similar in MPTP and controls, and their synaptic incidence was very low suggesting a volumic mode of transmission. Altogether, our data reveal a significant sprouting of DA and 5-HT pallidal afferents in parkinsonian monkeys, the functional significance of which remains to be determined. We suggest that the marked DA hyperinnervation of the GPi represents a neuroadaptive change designed to normalize pallidal firing patterns associated with the delayed appearance of motor symptoms, whereas the 5-HT hyperinnervation might be involved in the early expression of non-motor symptoms in Parkinson's disease.
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Affiliation(s)
- Dave Gagnon
- Department of Psychiatry and Neuroscience, Faculty of Medicine, CERVO Brain Research Centre, Université Laval, Quebec City, QC, Canada
| | - Lara Eid
- Department of Psychiatry and Neuroscience, Faculty of Medicine, CERVO Brain Research Centre, Université Laval, Quebec City, QC, Canada
| | - Dymka Coudé
- Department of Psychiatry and Neuroscience, Faculty of Medicine, CERVO Brain Research Centre, Université Laval, Quebec City, QC, Canada
| | - Carl Whissel
- Department of Psychiatry and Neuroscience, Faculty of Medicine, CERVO Brain Research Centre, Université Laval, Quebec City, QC, Canada
| | - Thérèse Di Paolo
- Faculty of Pharmacy, Centre de Recherche du CHU de Québec, Université Laval, Quebec City, QC, Canada
| | - André Parent
- Department of Psychiatry and Neuroscience, Faculty of Medicine, CERVO Brain Research Centre, Université Laval, Quebec City, QC, Canada
| | - Martin Parent
- Department of Psychiatry and Neuroscience, Faculty of Medicine, CERVO Brain Research Centre, Université Laval, Quebec City, QC, Canada
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Gaudry Q. Serotonergic Modulation of Olfaction in Rodents and Insects. THE YALE JOURNAL OF BIOLOGY AND MEDICINE 2018; 91:23-32. [PMID: 29599654 PMCID: PMC5872637] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Recent advances in genetic tools and optical imaging technology have allowed rodent and Drosophila researchers to explore the relationship between serotonergic modulation and olfactory processing at a mechanistic level previously unfeasible. Here, I review the basic organization of olfactory and serotonergic systems in both rodents and Drosophila and draw comparisons where similarities exist. I discuss circuit level models that explain many of serotonin's effects on olfactory responses in the olfactory system's inputs and outputs. Finally, I discuss models of integration within wide-field centrifugal neurons to emphasize the importance of studying serotonergic neurons directly to build more realistic models of olfactory and modulatory interactions.
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Affiliation(s)
- Quentin Gaudry
- Department of Biology, University of Maryland, College Park, MD
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39
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Camacho MB, Anastasio TJ. Computational Model of Antidepressant Response Heterogeneity as Multi-pathway Neuroadaptation. Front Pharmacol 2018; 8:925. [PMID: 29375372 PMCID: PMC5770730 DOI: 10.3389/fphar.2017.00925] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2017] [Accepted: 12/06/2017] [Indexed: 12/28/2022] Open
Abstract
Current hypotheses cannot fully explain the clinically observed heterogeneity in antidepressant response. The therapeutic latency of antidepressants suggests that therapeutic outcomes are achieved not by the acute effects of the drugs, but rather by the homeostatic changes that occur as the brain adapts to their chronic administration. We present a computational model that represents the known interactions between the monoaminergic neurotransmitter-producing brain regions and associated non-monoaminergic neurotransmitter systems, and use the model to explore the possible ways in which the brain can homeostatically adjust to chronic antidepressant administration. The model also represents the neuron-specific neurotransmitter receptors that are known to adjust their strengths (expressions or sensitivities) in response to chronic antidepressant administration, and neuroadaptation in the model occurs through sequential adjustments in these receptor strengths. The main result is that the model can reach similar levels of adaptation to chronic administration of the same antidepressant drug or combination along many different pathways, arriving correspondingly at many different receptor strength configurations, but not all of those adapted configurations are also associated with therapeutic elevations in monoamine levels. When expressed as the percentage of adapted configurations that are also associated with elevations in one or more of the monoamines, our modeling results largely agree with the percentage efficacy rates of antidepressants and antidepressant combinations observed in clinical trials. Our neuroadaptation model provides an explanation for the clinical reports of heterogeneous outcomes among patients chronically administered the same antidepressant drug regimen.
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Affiliation(s)
- Mariam B Camacho
- Computational Neurobiology Laboratory, Beckman Institute for Advanced Science and Technology, Neuroscience Program, Medical Scholars Program, University of Illinois College of Medicine at Urbana-Champaign, Urbana, IL, United States
| | - Thomas J Anastasio
- Computational Neurobiology Laboratory, Department of Molecular and Integrative Physiology, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, United States
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40
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Deneris E, Gaspar P. Serotonin neuron development: shaping molecular and structural identities. WILEY INTERDISCIPLINARY REVIEWS. DEVELOPMENTAL BIOLOGY 2018; 7:10.1002/wdev.301. [PMID: 29072810 PMCID: PMC5746461 DOI: 10.1002/wdev.301] [Citation(s) in RCA: 62] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2017] [Revised: 08/03/2017] [Accepted: 08/24/2017] [Indexed: 02/03/2023]
Abstract
The continuing fascination with serotonin (5-hydroxytryptamine, 5-HT) as a nervous system chemical messenger began with its discovery in the brains of mammals in 1953. Among the many reasons for this decades-long interest is that the small numbers of neurons that make 5-HT influence the excitability of neural circuits in nearly every region of the brain and spinal cord. A further reason is that 5-HT dysfunction has been linked to a range of psychiatric and neurological disorders many of which have a neurodevelopmental component. This has led to intense interest in understanding 5-HT neuron development with the aim of determining whether early alterations in their generation lead to brain disease susceptibility. Here, we present an overview of the neuroanatomical organization of vertebrate 5-HT neurons, their neurogenesis, and prodigious axonal architectures, which enables the expansive reach of 5-HT neuromodulation in the central nervous system. We review recent findings that have revealed the molecular basis for the tremendous diversity of 5-HT neuron subtypes, the impact of environmental factors on 5-HT neuron development, and how 5-HT axons are topographically organized through disparate signaling pathways. We summarize studies of the gene regulatory networks that control the differentiation, maturation, and maintenance of 5-HT neurons. These studies show that the regulatory factors controlling acquisition of 5-HT-type transmitter identity continue to play critical roles in the functional maturation and the maintenance of 5-HT neurons. New insights are presented into how continuously expressed 5-HT regulatory factors control 5-HT neurons at different stages of life and how the regulatory networks themselves are maintained. WIREs Dev Biol 2018, 7:e301. doi: 10.1002/wdev.301 This article is categorized under: Nervous System Development > Vertebrates: General Principles Gene Expression and Transcriptional Hierarchies > Gene Networks and Genomics Gene Expression and Transcriptional Hierarchies > Cellular Differentiation Nervous System Development > Secondary: Vertebrates: Regional Development.
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Affiliation(s)
- Evan Deneris
- Department of Neurosciences, Case Western Reserve University School of Medicine, Cleveland, OH, USA
| | - Patricia Gaspar
- Institut National de la Santé et de la Recherche Médicale (INSERM), UMR-S839, Paris, France
- Sorbonne Université, Paris, France
- Institut du Fer à Moulin, Campus Jussieu, Paris, France
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41
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Scaplen KM, Kaun KR. Reward from bugs to bipeds: a comparative approach to understanding how reward circuits function. J Neurogenet 2017; 30:133-48. [PMID: 27328845 PMCID: PMC4926782 DOI: 10.1080/01677063.2016.1180385] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
In a complex environment, animals learn from their responses to stimuli and events. Appropriate response to reward and punishment can promote survival, reproduction and increase evolutionary fitness. Interestingly, the neural processes underlying these responses are remarkably similar across phyla. In all species, dopamine is central to encoding reward and directing motivated behaviors, however, a comprehensive understanding of how circuits encode reward and direct motivated behaviors is still lacking. In part, this is a result of the sheer diversity of neurons, the heterogeneity of their responses and the complexity of neural circuits within which they are found. We argue that general features of reward circuitry are common across model organisms, and thus principles learned from invertebrate model organisms can inform research across species. In particular, we discuss circuit motifs that appear to be functionally equivalent from flies to primates. We argue that a comparative approach to studying and understanding reward circuit function provides a more comprehensive understanding of reward circuitry, and informs disorders that affect the brain’s reward circuitry.
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Affiliation(s)
- Kristin M Scaplen
- a Department of Neuroscience , Brown University , Providence , RI , USA
| | - Karla R Kaun
- a Department of Neuroscience , Brown University , Providence , RI , USA
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42
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Prouty EW, Chandler DJ, Waterhouse BD. Neurochemical differences between target-specific populations of rat dorsal raphe projection neurons. Brain Res 2017; 1675:28-40. [PMID: 28867482 PMCID: PMC5822427 DOI: 10.1016/j.brainres.2017.08.031] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2017] [Revised: 08/18/2017] [Accepted: 08/28/2017] [Indexed: 11/22/2022]
Abstract
Serotonin (5-HT)-containing neurons in the dorsal raphe (DR) nucleus project throughout the forebrain and are implicated in many physiological processes and neuropsychiatric disorders. Diversity among these neurons has been characterized in terms of their neurochemistry and anatomical organization, but a clear sense of whether these attributes align with specific brain functions or terminal fields is lacking. DR 5-HT neurons can co-express additional neuroactive substances, increasing the potential for individualized regulation of target circuits. The goal of this study was to link DR neurons to a specific functional role by characterizing cells according to both their neurotransmitter expression and efferent connectivity; specifically, cells projecting to the medial prefrontal cortex (mPFC), a region implicated in cognition, emotion, and responses to stress. Following retrograde tracer injection, brainstem sections from Sprague-Dawley rats were immunohistochemically stained for markers of serotonin, glutamate, GABA, and nitric oxide (NO). 98% of the mPFC-projecting serotonergic neurons co-expressed the marker for glutamate, while the markers for NO and GABA were observed in 60% and less than 1% of those neurons, respectively. To identify potential target-specific differences in co-transmitter expression, we also characterized DR neurons projecting to a visual sensory structure, the lateral geniculate nucleus (LGN). The proportion of serotonergic neurons co-expressing NO was greater amongst cells targeting the mPFC vs LGN (60% vs 22%). The established role of 5-HT in affective disorders and the emerging role of NO in stress signaling suggest that the impact of 5-HT/NO co-localization in DR neurons that regulate mPFC circuit function may be clinically relevant.
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Affiliation(s)
- Eric W Prouty
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA 19129, USA
| | - Daniel J Chandler
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA 19129, USA
| | - Barry D Waterhouse
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA 19129, USA.
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43
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Wong-Lin K, Wang DH, Moustafa AA, Cohen JY, Nakamura K. Toward a multiscale modeling framework for understanding serotonergic function. J Psychopharmacol 2017; 31:1121-1136. [PMID: 28417684 PMCID: PMC5606304 DOI: 10.1177/0269881117699612] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Despite its importance in regulating emotion and mental wellbeing, the complex structure and function of the serotonergic system present formidable challenges toward understanding its mechanisms. In this paper, we review studies investigating the interactions between serotonergic and related brain systems and their behavior at multiple scales, with a focus on biologically-based computational modeling. We first discuss serotonergic intracellular signaling and neuronal excitability, followed by neuronal circuit and systems levels. At each level of organization, we will discuss the experimental work accompanied by related computational modeling work. We then suggest that a multiscale modeling approach that integrates the various levels of neurobiological organization could potentially transform the way we understand the complex functions associated with serotonin.
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Affiliation(s)
- KongFatt Wong-Lin
- Intelligent Systems Research Centre, School of Computing and Intelligent Systems, University of Ulster, Magee Campus, Derry~Londonderry, UK
| | - Da-Hui Wang
- School of Systems Science, and National Key Laboratory of Cognitive Neuroscience and Learning, Beijing Normal University, Beijing, China
| | - Ahmed A Moustafa
- School of Social Sciences and Psychology, and Marcs Institute for Brain and Behaviour, University of Western Sydney, Sydney, Australia
| | - Jeremiah Y Cohen
- Solomon H. Snyder Department of Neuroscience, Brain Science Institute, Johns Hopkins University School of Medicine, Baltimore, USA
| | - Kae Nakamura
- Department of Physiology, Kansai Medical University, Hirakata, Osaka, Japan
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44
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Kljakic O, Janickova H, Prado VF, Prado MAM. Cholinergic/glutamatergic co-transmission in striatal cholinergic interneurons: new mechanisms regulating striatal computation. J Neurochem 2017; 142 Suppl 2:90-102. [PMID: 28421605 DOI: 10.1111/jnc.14003] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Revised: 02/28/2017] [Accepted: 03/01/2017] [Indexed: 01/22/2023]
Abstract
It is well established that neurons secrete neuropeptides and ATP with classical neurotransmitters; however, certain neuronal populations are also capable of releasing two classical neurotransmitters by a process named co-transmission. Although there has been progress in our understanding of the molecular mechanism underlying co-transmission, the individual regulation of neurotransmitter secretion and the functional significance of this neuronal 'bilingualism' is still unknown. Striatal cholinergic interneurons (CINs) have been shown to secrete glutamate (Glu) in addition to acetylcholine (ACh) and are recognized for their role in the regulation of striatal circuits and behavior. Our review highlights the recent research into identifying mechanisms that regulate the secretion and function of Glu and ACh released by CINs and the roles these neurons play in regulating dopamine secretion and striatal activity. In particular, we focus on how the transporters for ACh (VAChT) and Glu (VGLUT3) influence the storage of neurotransmitters in CINs. We further discuss how these individual neurotransmitters regulate striatal computation and distinct aspects of behavior that are regulated by the striatum. We suggest that understanding the distinct and complementary functional roles of these two neurotransmitters may prove beneficial in the development of therapies for Parkinson's disease and addiction. Overall, understanding how Glu and ACh secreted by CINs impacts striatal activity may provide insight into how different populations of 'bilingual' neurons are able to develop sophisticated regulation of their targets by interacting with multiple receptors but also by regulating each other's vesicular storage. This is an article for the special issue XVth International Symposium on Cholinergic Mechanisms.
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Affiliation(s)
- Ornela Kljakic
- Robarts Research Institute, Schulich School of Medicine & Dentistry, University of Western Ontario, London, Ontario, Canada.,Department of Anatomy and Cell Biology, Schulich School of Medicine & Dentistry, University of Western Ontario, London, Ontario, Canada
| | - Helena Janickova
- Robarts Research Institute, Schulich School of Medicine & Dentistry, University of Western Ontario, London, Ontario, Canada
| | - Vania F Prado
- Robarts Research Institute, Schulich School of Medicine & Dentistry, University of Western Ontario, London, Ontario, Canada.,Department of Anatomy and Cell Biology, Schulich School of Medicine & Dentistry, University of Western Ontario, London, Ontario, Canada.,Department of Physiology and Pharmacology, Schulich School of Medicine & Dentistry, University of Western Ontario, London, Ontario, Canada
| | - Marco A M Prado
- Robarts Research Institute, Schulich School of Medicine & Dentistry, University of Western Ontario, London, Ontario, Canada.,Department of Anatomy and Cell Biology, Schulich School of Medicine & Dentistry, University of Western Ontario, London, Ontario, Canada.,Department of Physiology and Pharmacology, Schulich School of Medicine & Dentistry, University of Western Ontario, London, Ontario, Canada
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45
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Perturbation of Serotonin Homeostasis during Adulthood Affects Serotonergic Neuronal Circuitry. eNeuro 2017; 4:eN-NWR-0376-16. [PMID: 28413824 PMCID: PMC5388670 DOI: 10.1523/eneuro.0376-16.2017] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Revised: 02/14/2017] [Accepted: 02/17/2017] [Indexed: 02/01/2023] Open
Abstract
Growing evidence shows that the neurotransmitter serotonin (5-HT) modulates the fine-tuning of neuron development and the establishment of wiring patterns in the brain. However, whether serotonin is involved in the maintenance of neuronal circuitry in the adult brain remains elusive. Here, we use a Tph2fl°x conditional knockout (cKO) mouse line to assess the impact of serotonin depletion during adulthood on serotonergic system organization. Data show that the density of serotonergic fibers is increased in the hippocampus and decreased in the thalamic paraventricular nucleus (PVN) as a consequence of brain serotonin depletion. Strikingly, these defects are rescued following reestablishment of brain 5-HT signaling via administration of the serotonin precursor 5-hydroxytryptophan (5-HTP). Finally, 3D reconstruction of serotonergic fibers reveals that changes in serotonin homeostasis affect axonal branching complexity. These data demonstrate that maintaining proper serotonin homeostasis in the adult brain is crucial to preserve the correct serotonergic axonal wiring.
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46
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Matias S, Lottem E, Dugué GP, Mainen ZF. Activity patterns of serotonin neurons underlying cognitive flexibility. eLife 2017; 6:e20552. [PMID: 28322190 PMCID: PMC5360447 DOI: 10.7554/elife.20552] [Citation(s) in RCA: 128] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2016] [Accepted: 02/26/2017] [Indexed: 12/18/2022] Open
Abstract
Serotonin is implicated in mood and affective disorders. However, growing evidence suggests that a core endogenous role is to promote flexible adaptation to changes in the causal structure of the environment, through behavioral inhibition and enhanced plasticity. We used long-term photometric recordings in mice to study a population of dorsal raphe serotonin neurons, whose activity we could link to normal reversal learning using pharmacogenetics. We found that these neurons are activated by both positive and negative prediction errors, and thus report signals similar to those proposed to promote learning in conditions of uncertainty. Furthermore, by comparing the cue responses of serotonin and dopamine neurons, we found differences in learning rates that could explain the importance of serotonin in inhibiting perseverative responding. Our findings show how the activity patterns of serotonin neurons support a role in cognitive flexibility, and suggest a revised model of dopamine-serotonin opponency with potential clinical implications.
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Affiliation(s)
- Sara Matias
- Champalimaud Research, Champalimaud Centre for the Unknown, Lisbon, Portugal
- MIT-Portugal Program, Porto Salvo, Portugal
| | - Eran Lottem
- Champalimaud Research, Champalimaud Centre for the Unknown, Lisbon, Portugal
| | - Guillaume P Dugué
- Institut de Biologie de l’Ecole Normale Supérieure, Centre National de la Recherche Scientifique, UMR8197, Institut National de la Santé et de la Recherche Médicale, Paris, France
| | - Zachary F Mainen
- Champalimaud Research, Champalimaud Centre for the Unknown, Lisbon, Portugal
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47
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Control of Amygdala Circuits by 5-HT Neurons via 5-HT and Glutamate Cotransmission. J Neurosci 2017; 37:1785-1796. [PMID: 28087766 PMCID: PMC5320609 DOI: 10.1523/jneurosci.2238-16.2016] [Citation(s) in RCA: 81] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2016] [Revised: 11/07/2016] [Accepted: 11/19/2016] [Indexed: 11/21/2022] Open
Abstract
The serotonin (5-HT) system and the amygdala are key regulators of emotional behavior. Several lines of evidence suggest that 5-HT transmission in the amygdala is implicated in the susceptibility and drug treatment of mood disorders. Therefore, elucidating the physiological mechanisms through which midbrain 5-HT neurons modulate amygdala circuits could be pivotal in understanding emotional regulation in health and disease. To shed light on these mechanisms, we performed patch-clamp recordings from basal amygdala (BA) neurons in brain slices from mice with channelrhodopsin genetically targeted to 5-HT neurons. Optical stimulation of 5-HT terminals at low frequencies (≤1 Hz) evoked a short-latency excitation of BA interneurons (INs) that was depressed at higher frequencies. Pharmacological analysis revealed that this effect was mediated by glutamate and not 5-HT because it was abolished by ionotropic glutamate receptor antagonists. Optical stimulation of 5-HT terminals at higher frequencies (10–20 Hz) evoked both slow excitation and slow inhibition of INs. These effects were mediated by 5-HT because they were blocked by antagonists of 5-HT2A and 5-HT1A receptors, respectively. These fast glutamate- and slow 5-HT-mediated responses often coexisted in the same neuron. Interestingly, fast-spiking and non-fast-spiking INs displayed differential modulation by glutamate and 5-HT. Furthermore, optical stimulation of 5-HT terminals did not evoke glutamate release onto BA principal neurons, but inhibited these cells directly via activation of 5-HT1A receptors and indirectly via enhanced GABA release. Collectively, these findings suggest that 5-HT neurons exert a frequency-dependent, cell-type-specific control over BA circuitry via 5-HT and glutamate co-release to inhibit the BA output. SIGNIFICANCE STATEMENT The modulation of the amygdala by serotonin (5-HT) is important for emotional regulation and is implicated in the pathogenesis and treatment of affective disorders. Therefore, it is essential to determine the physiological mechanisms through which 5-HT neurons in the dorsal raphe nuclei modulate amygdala circuits. Here, we combined optogenetic, electrophysiological, and pharmacological approaches to study the effects of activation of 5-HT axons in the basal nucleus of the amygdala (BA). We found that 5-HT neurons co-release 5-HT and glutamate onto BA neurons in a cell-type-specific and frequency-dependent manner. Therefore, we suggest that theories on the contribution of 5-HT neurons to amygdala function should be revised to incorporate the concept of 5-HT/glutamate cotransmission.
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48
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Tien NW, Kim T, Kerschensteiner D. Target-Specific Glycinergic Transmission from VGluT3-Expressing Amacrine Cells Shapes Suppressive Contrast Responses in the Retina. Cell Rep 2016; 15:1369-1375. [PMID: 27160915 DOI: 10.1016/j.celrep.2016.04.025] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2016] [Revised: 03/28/2016] [Accepted: 04/03/2016] [Indexed: 10/21/2022] Open
Abstract
Neurons that release more than one transmitter exist throughout the CNS. Yet, how these neurons deploy multiple transmitters and shape the function of specific circuits is not well understood. VGluT3-expressing amacrine cells (VG3-ACs) provide glutamatergic input to ganglion cells activated by contrast and motion. Using optogenetics, we find that VG3-ACs provide selective glycinergic input to a retinal ganglion cell type suppressed by contrast and motion (SbC-RGCs). Firing of SbC-RGCs is suppressed at light ON and OFF over a broad range of stimulus sizes. Anatomical circuit reconstructions reveal that VG3-ACs form inhibitory synapses preferentially on processes that link ON and OFF arbors of SbC-RGC dendrites. Removal of VG3-ACs from mature circuits reduces inhibition and attenuates spike suppression of SbC-RGCs in a contrast- and size-selective manner, illustrating the modularity of retinal circuits. VG3-ACs thus use dual transmitters in a target-specific manner and shape suppressive contrast responses in the retina by glycinergic transmission.
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Affiliation(s)
- Nai-Wen Tien
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, Saint Louis, MO 63110, USA; Graduate Program in Neuroscience, Washington University School of Medicine, Saint Louis, MO 63110, USA
| | - Tahnbee Kim
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, Saint Louis, MO 63110, USA; Graduate Program in Neuroscience, Washington University School of Medicine, Saint Louis, MO 63110, USA
| | - Daniel Kerschensteiner
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, Saint Louis, MO 63110, USA; Department of Neuroscience, Washington University School of Medicine, Saint Louis, MO 63110, USA; Department of Biomedical Engineering, Washington University School of Medicine, Saint Louis, MO 63110, USA; Hope Center for Neurological Disorders, Washington University School of Medicine, Saint Louis, MO 63110, USA.
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Voisin AN, Mnie-Filali O, Giguère N, Fortin GM, Vigneault E, El Mestikawy S, Descarries L, Trudeau LÉ. Axonal Segregation and Role of the Vesicular Glutamate Transporter VGLUT3 in Serotonin Neurons. Front Neuroanat 2016; 10:39. [PMID: 27147980 PMCID: PMC4828685 DOI: 10.3389/fnana.2016.00039] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2016] [Accepted: 03/21/2016] [Indexed: 11/13/2022] Open
Abstract
A subset of monoamine neurons releases glutamate as a cotransmitter due to presence of the vesicular glutamate transporters VGLUT2 or VGLUT3. In addition to mediating vesicular loading of glutamate, it has been proposed that VGLUT3 enhances serotonin (5-HT) vesicular loading by the vesicular monoamine transporter (VMAT2) in 5-HT neurons. In dopamine (DA) neurons, glutamate appears to be released from specialized subsets of terminals and it may play a developmental role, promoting neuronal growth and survival. The hypothesis of a similar developmental role and axonal localization of glutamate co-release in 5-HT neurons has not been directly examined. Using postnatal mouse raphe neurons in culture, we first observed that in contrast to 5-HT itself, other phenotypic markers of 5-HT axon terminals such as the 5-HT reuptake transporter (SERT) show a more restricted localization in the axonal arborization. Interestingly, only a subset of SERT- and 5-HT-positive axonal varicosities expressed VGLUT3, with SERT and VGLUT3 being mostly segregated. Using VGLUT3 knockout mice, we found that deletion of this transporter leads to reduced survival of 5-HT neurons in vitro and also decreased the density of 5-HT-immunoreactivity in terminals in the dorsal striatum and dorsal part of the hippocampus in the intact brain. Our results demonstrate that raphe 5-HT neurons express SERT and VGLUT3 mainly in segregated axon terminals and that VGLUT3 regulates the vulnerability of these neurons and the neurochemical identity of their axonal domain, offering new perspectives on the functional connectivity of a cell population involved in anxiety disorders and depression.
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Affiliation(s)
- Aurore N. Voisin
- Department of Pharmacology, Faculty of Medicine, GRSNC, Université de MontréalMontreal, QC, Canada
| | - Ouissame Mnie-Filali
- Department of Neurosciences, Faculty of Medicine, GRSNC, Université de MontréalMontreal, QC, Canada
| | - Nicolas Giguère
- Department of Pharmacology, Faculty of Medicine, GRSNC, Université de MontréalMontreal, QC, Canada
- Department of Neurosciences, Faculty of Medicine, GRSNC, Université de MontréalMontreal, QC, Canada
| | - Guillaume M. Fortin
- Department of Pharmacology, Faculty of Medicine, GRSNC, Université de MontréalMontreal, QC, Canada
| | - Erika Vigneault
- Department of Psychiatry, Douglas Hospital Research Center, McGill UniversityMontreal, QC, Canada
| | - Salah El Mestikawy
- Department of Psychiatry, Douglas Hospital Research Center, McGill UniversityMontreal, QC, Canada
- Institut National de la Santé et de la Recherche Médicale (INSERM), UMR-S 1130Paris, France
- Centre National de la Recherche Scientifique (CNRS), UMR 8246Paris, France
- Institut de Biologie Paris-Seine (IBPS), Sorbonne Universités, Université Pierre et Marie Curie (UPMC) Paris, UM119 Neuroscience Paris SeineParis, France
| | - Laurent Descarries
- Department of Neurosciences, Faculty of Medicine, GRSNC, Université de MontréalMontreal, QC, Canada
| | - Louis-Éric Trudeau
- Department of Pharmacology, Faculty of Medicine, GRSNC, Université de MontréalMontreal, QC, Canada
- Department of Neurosciences, Faculty of Medicine, GRSNC, Université de MontréalMontreal, QC, Canada
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Eid L, Parent M. Chemical anatomy of pallidal afferents in primates. Brain Struct Funct 2016; 221:4291-4317. [PMID: 27028222 DOI: 10.1007/s00429-016-1216-y] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Accepted: 03/15/2016] [Indexed: 12/24/2022]
Abstract
Neurons of the globus pallidus receive massive inputs from the striatum and the subthalamic nucleus, but their activity, as well as those of their striatal and subthalamic inputs, are modulated by brainstem afferents. These include serotonin (5-HT) projections from the dorsal raphe nucleus, cholinergic (ACh) inputs from the pedunculopontine tegmental nucleus, and dopamine (DA) afferents from the substantia nigra pars compacta. This review summarizes our recent findings on the distribution, quantitative and ultrastructural aspects of pallidal 5-HT, ACh and DA innervations. These results have led to the elaboration of a new model of the pallidal neuron based on a precise knowledge of the hierarchy and chemical features of the various synaptic inputs. The dense 5-HT, ACh and DA innervations disclosed in the associative and limbic pallidal territories suggest that these brainstem inputs contribute principally to the planification of motor behaviors and the regulation of attention and mood. Although 5-HT, ACh and DA inputs were found to modulate pallidal neurons and their afferents mainly through asynaptic (volume) transmission, genuine synaptic contacts occur between these chemospecific axon varicosities and pallidal dendrites, revealing that these brainstem projections have a direct access to pallidal neurons, in addition to their indirect input through the striatum and subthalamic nucleus. Altogether, these findings reveal that the brainstem 5-HT, ACh and DA pallidal afferents act in concert with the more robust GABAergic inhibitory striatopallidal and glutamatergic excitatory subthalamopallidal inputs. We hypothesize that a fragile equilibrium between forebrain and brainstem pallidal afferents plays a key role in the functional organization of the primate basal ganglia, in both health and disease.
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Affiliation(s)
- Lara Eid
- Department of Psychiatry and Neuroscience, Faculty of Medicine, Centre de recherche de l'Institut universitaire en santé mentale de Québec (CRIUSMQ), Université Laval, F-6530-1, 2601, de la Canardière, Quebec, QC, G1J 2G3, Canada
| | - Martin Parent
- Department of Psychiatry and Neuroscience, Faculty of Medicine, Centre de recherche de l'Institut universitaire en santé mentale de Québec (CRIUSMQ), Université Laval, F-6530-1, 2601, de la Canardière, Quebec, QC, G1J 2G3, Canada.
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