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Özçete ÖD, Banerjee A, Kaeser PS. Mechanisms of neuromodulatory volume transmission. Mol Psychiatry 2024; 29:3680-3693. [PMID: 38789677 PMCID: PMC11540752 DOI: 10.1038/s41380-024-02608-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/19/2023] [Revised: 05/07/2024] [Accepted: 05/10/2024] [Indexed: 05/26/2024]
Abstract
A wealth of neuromodulatory transmitters regulate synaptic circuits in the brain. Their mode of signaling, often called volume transmission, differs from classical synaptic transmission in important ways. In synaptic transmission, vesicles rapidly fuse in response to action potentials and release their transmitter content. The transmitters are then sensed by nearby receptors on select target cells with minimal delay. Signal transmission is restricted to synaptic contacts and typically occurs within ~1 ms. Volume transmission doesn't rely on synaptic contact sites and is the main mode of monoamines and neuropeptides, important neuromodulators in the brain. It is less precise than synaptic transmission, and the underlying molecular mechanisms and spatiotemporal scales are often not well understood. Here, we review literature on mechanisms of volume transmission and raise scientific questions that should be addressed in the years ahead. We define five domains by which volume transmission systems can differ from synaptic transmission and from one another. These domains are (1) innervation patterns and firing properties, (2) transmitter synthesis and loading into different types of vesicles, (3) architecture and distribution of release sites, (4) transmitter diffusion, degradation, and reuptake, and (5) receptor types and their positioning on target cells. We discuss these five domains for dopamine, a well-studied monoamine, and then compare the literature on dopamine with that on norepinephrine and serotonin. We include assessments of neuropeptide signaling and of central acetylcholine transmission. Through this review, we provide a molecular and cellular framework for volume transmission. This mechanistic knowledge is essential to define how neuromodulatory systems control behavior in health and disease and to understand how they are modulated by medical treatments and by drugs of abuse.
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Affiliation(s)
- Özge D Özçete
- Department of Neurobiology, Harvard Medical School, Boston, MA, 02115, USA
| | - Aditi Banerjee
- Department of Neurobiology, Harvard Medical School, Boston, MA, 02115, USA
| | - Pascal S Kaeser
- Department of Neurobiology, Harvard Medical School, Boston, MA, 02115, USA.
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Borroto-Escuela DO, Gonzalez-Cristo E, Ochoa-Torres V, Serra-Rojas EM, Ambrogini P, Arroyo-García LE, Fuxe K. Understanding electrical and chemical transmission in the brain. Front Cell Neurosci 2024; 18:1398862. [PMID: 38988663 PMCID: PMC11233782 DOI: 10.3389/fncel.2024.1398862] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2024] [Accepted: 06/14/2024] [Indexed: 07/12/2024] Open
Abstract
The histochemical Falck-Hillarp method for the localization of dopamine (DA), noradrenaline (NA) and serotonin in the central nervous system (CNS) of rodents was introduced in the 1960s. It supported the existence of chemical neurotransmission in the CNS. The monoamine neurons in the lower brain stem formed monosynaptic ascending systems to the telencephalon and diencephalon and monoamine descending systems to the entire spinal cord. The monoamines were early on suggested to operate via synaptic chemical transmission in the CNS. This chemical transmission reduced the impact of electrical transmission. In 1969 and the 1970s indications were obtained that important modes of chemical monoamine communication in the CNS also took place through the extra-synaptic fluid, the extracellular fluid, and long-distance communication in the cerebrospinal fluid involving diffusion and flow of transmitters like DA, NA and serotonin. In 1986, this type of transmission was named volume transmission (VT) by Agnati and Fuxe and their colleagues, also characterized by transmitter varicosity and receptor mismatches. The short and long-distance VT pathways were characterized by volume fraction, tortuosity and clearance. Electrical transmission also exists in the mammalian CNS, but chemical transmission is in dominance. One electrical mode is represented by electrical synapses formed by gap junctions which represent low resistant passages between nerve cells. It allows for a more rapid passage of action potentials between nerve cells compared to chemical transmission. The second mode is based on the ability of synaptic currents to generate electrical fields to modulate chemical transmission. One aim is to understand how chemical transmission can be integrated with electrical transmission and how putative (aquaporin water channel, dopamine D2R and adenosine A2AR) complexes in astrocytes can significancy participate in the clearance of waste products from the glymphatic system. VT may also help accomplish the operation of the acupuncture meridians essential for Chinese medicine in view of the indicated existence of extracellular VT pathways.
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Affiliation(s)
- Dasiel O. Borroto-Escuela
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
- Receptomics and Brain Disorders Lab, Department of Human Physiology Physical Education and Sport, Faculty of Medicine, University of Malaga, Málaga, Spain
| | - Emmanuell Gonzalez-Cristo
- Receptomics and Brain Disorders Lab, Department of Human Physiology Physical Education and Sport, Faculty of Medicine, University of Malaga, Málaga, Spain
| | - Verty Ochoa-Torres
- Receptomics and Brain Disorders Lab, Department of Human Physiology Physical Education and Sport, Faculty of Medicine, University of Malaga, Málaga, Spain
- Faculty of Engineering and Biotechnology, University OTR and the Regional Cooperative for Comprehensive Medical Assistance (CRAMI), Montevideo, Uruguay
| | - Emilio M. Serra-Rojas
- Receptomics and Brain Disorders Lab, Department of Human Physiology Physical Education and Sport, Faculty of Medicine, University of Malaga, Málaga, Spain
- Cardiology Service, Lozano Blesa University Clinical Hospital, Zaragoza, Spain
| | - Patrizia Ambrogini
- Department of Biomolecular Sciences, Università di Urbino Carlo Bo, Urbino, Italy
| | - Luis E. Arroyo-García
- Division of Neurogeriatrics, Department of Neurobiology, Care Sciences, and Society, Karolinska Institutet, Stockholm, Sweden
| | - Kjell Fuxe
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
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Sárkány B, Dávid C, Hortobágyi T, Gombás P, Somogyi P, Acsády L, Viney TJ. Early and selective localization of tau filaments to glutamatergic subcellular domains within the human anterodorsal thalamus. Acta Neuropathol 2024; 147:98. [PMID: 38861157 PMCID: PMC11166832 DOI: 10.1007/s00401-024-02749-3] [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: 01/12/2024] [Revised: 05/21/2024] [Accepted: 06/01/2024] [Indexed: 06/12/2024]
Abstract
Widespread cortical accumulation of misfolded pathological tau proteins (ptau) in the form of paired helical filaments is a major hallmark of Alzheimer's disease. Subcellular localization of ptau at various stages of disease progression is likely to be informative of the cellular mechanisms involving its spread. Here, we found that the density of ptau within several distinct rostral thalamic nuclei in post-mortem human tissue (n = 25 cases) increased with the disease stage, with the anterodorsal nucleus (ADn) consistently being the most affected. In the ADn, ptau-positive elements were present already in the pre-cortical (Braak 0) stage. Tau pathology preferentially affected the calretinin-expressing subpopulation of glutamatergic neurons in the ADn. At the subcellular level, we detected ptau immunoreactivity in ADn cell bodies, dendrites, and in a specialized type of presynaptic terminal that expresses vesicular glutamate transporter 2 (vGLUT2) and likely originates from the mammillary body. The ptau-containing terminals displayed signs of degeneration, including endosomal/lysosomal organelles. In contrast, corticothalamic axon terminals lacked ptau. The data demonstrate the involvement of a specific cell population in ADn at the onset of the disease. The presence of ptau in subcortical glutamatergic presynaptic terminals supports hypotheses about the transsynaptic spread of tau selectively affecting specialized axonal pathways.
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Affiliation(s)
- Barbara Sárkány
- Department of Pharmacology, University of Oxford, Oxford, OX1 3QT, UK.
| | - Csaba Dávid
- Lendület Laboratory of Thalamus Research, Institute of Experimental Medicine, Budapest, 1083, Hungary
- Department of Anatomy, Histology and Embryology, Semmelweis University, Budapest, 1094, Hungary
| | - Tibor Hortobágyi
- Department of Neurology, Faculty of Medicine, University of Debrecen, Debrecen, 4032, Hungary
| | - Péter Gombás
- Department of Pathology, Szt. Borbála Hospital, Tatabánya, 2800, Hungary
| | - Peter Somogyi
- Department of Pharmacology, University of Oxford, Oxford, OX1 3QT, UK
| | - László Acsády
- Lendület Laboratory of Thalamus Research, Institute of Experimental Medicine, Budapest, 1083, Hungary.
| | - Tim J Viney
- Department of Pharmacology, University of Oxford, Oxford, OX1 3QT, UK.
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Cahill MK, Perez YR, Larpthaveesarp A, Etchenique R, Poskanzer KE. A Photoactivatable Norepinephrine for Probing Adrenergic Neural Circuits. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.13.566764. [PMID: 38014204 PMCID: PMC10680792 DOI: 10.1101/2023.11.13.566764] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2023]
Abstract
Norepinephrine (NE) is a critical neuromodulator that mediates a wide range of behavior and neurophysiology, including attention, arousal, plasticity, and memory consolidation. A major source of NE is the brainstem nucleus the locus coeruleus (LC), which sends widespread projections throughout the central nervous system (CNS). Efforts to dissect this complex noradrenergic circuitry have driven the development of many tools that detect endogenous NE or modulate widespread NE release via LC activation and inhibition. While these tools have enabled research that elucidates physiological roles of NE, additional tools to probe these circuits with a higher degree of spatial precision could enable a finer delineation of function. Here, we describe the synthesis and chemical properties of a photo-activatable NE, [Ru(bpy) 2 (PMe 3 )(NE)]PF 6 (RuBi-NE). We validate the one-photon (1P) release of NE using whole-cell patch clamp electrophysiology in acute mouse brain slices containing the LC. We show that a 10 ms pulse of blue light, in the presence of RuBi-NE, briefly modulates the firing rate of LC neurons via α-2 adrenergic receptors. The development of a photo-activatable NE that can be released with light in the visible spectrum provides a new tool for fine-grained mapping of complex noradrenergic circuits, as well as the ability to probe how NE acts on non-neuronal cells in the CNS.
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Gargano A, Olabiyi BF, Palmisano M, Zimmer A, Bilkei-Gorzo A. Possible role of locus coeruleus neuronal loss in age-related memory and attention deficits. Front Neurosci 2023; 17:1264253. [PMID: 37694113 PMCID: PMC10492095 DOI: 10.3389/fnins.2023.1264253] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2023] [Accepted: 08/07/2023] [Indexed: 09/12/2023] Open
Abstract
Introduction Aging is associated with a decline in cognitive abilities, including memory and attention. It is generally accepted that age-related histological changes such as increased neuroinflammatory glial activity and a reduction in the number of specific neuronal populations contribute to cognitive aging. Noradrenergic neurons in the locus coeruleus (LC) undergo an approximately 20 % loss during ageing both in humans and mice, but whether this change contributes to cognitive deficits is not known. To address this issue, we asked whether a similar loss of LC neurons in young animals as observed in aged animals impairs memory and attention, cognitive domains that are both influenced by the noradrenergic system and impaired in aging. Methods For that, we treated young healthy mice with DSP-4, a toxin that specifically kills LC noradrenergic neurons. We compared the performance of DSP-4 treated young mice with the performance of aged mice in models of attention and memory. To do this, we first determined the dose of DSP-4, which causes a similar 20 % neuronal loss as is typical in aged animals. Results Young mice treated with DSP-4 showed impaired attention in the presence of distractor and memory deficits in the 5-choice serial reaction time test (5-CSRTT). Old, untreated mice showed severe deficits in both the 5-CSRTT and in fear extinction tests. Discussion Our data now suggest that a reduction in the number of LC neurons contributes to impaired working memory and greater distractibility in attentional tasks but not to deficits in fear extinction. We hypothesize that the moderate loss of LC noradrenergic neurons during aging contributes to attention deficits and working memory impairments.
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Affiliation(s)
| | | | | | | | - Andras Bilkei-Gorzo
- Medical Faculty, Institute of Molecular Psychiatry, University of Bonn, Venusberg-Campus, Bonn, Germany
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Viglione A, Mazziotti R, Pizzorusso T. From pupil to the brain: New insights for studying cortical plasticity through pupillometry. Front Neural Circuits 2023; 17:1151847. [PMID: 37063384 PMCID: PMC10102476 DOI: 10.3389/fncir.2023.1151847] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2023] [Accepted: 03/08/2023] [Indexed: 04/03/2023] Open
Abstract
Pupil size variations have been associated with changes in brain activity patterns related with specific cognitive factors, such as arousal, attention, and mental effort. The locus coeruleus (LC), a key hub in the noradrenergic system of the brain, is considered to be a key regulator of cognitive control on pupil size, with changes in pupil diameter corresponding to the release of norepinephrine (NE). Advances in eye-tracking technology and open-source software have facilitated accurate pupil size measurement in various experimental settings, leading to increased interest in using pupillometry to track the nervous system activation state and as a potential biomarker for brain disorders. This review explores pupillometry as a non-invasive and fully translational tool for studying cortical plasticity starting from recent literature suggesting that pupillometry could be a promising technique for estimating the degree of residual plasticity in human subjects. Given that NE is known to be a critical mediator of cortical plasticity and arousal, the review includes data revealing the importance of the LC-NE system in modulating brain plasticity and pupil size. Finally, we will review data suggesting that pupillometry could provide a quantitative and complementary measure of cortical plasticity also in pre-clinical studies.
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Affiliation(s)
| | | | - Tommaso Pizzorusso
- BIO@SNS Lab, Scuola Normale Superiore, Pisa, Italy
- Institute of Neuroscience, National Research Council, Pisa, Italy
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Cooke P, Janowitz H, Dougherty SE. Neuronal Redevelopment and the Regeneration of Neuromodulatory Axons in the Adult Mammalian Central Nervous System. Front Cell Neurosci 2022; 16:872501. [PMID: 35530177 PMCID: PMC9074815 DOI: 10.3389/fncel.2022.872501] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Accepted: 03/24/2022] [Indexed: 01/09/2023] Open
Abstract
One reason that many central nervous system injuries, including those arising from traumatic brain injury, spinal cord injury, and stroke, have limited recovery of function is that neurons within the adult mammalian CNS lack the ability to regenerate their axons following trauma. This stands in contrast to neurons of the adult mammalian peripheral nervous system (PNS). New evidence, provided by single-cell expression profiling, suggests that, following injury, both mammalian central and peripheral neurons can revert to an embryonic-like growth state which is permissive for axon regeneration. This “redevelopment” strategy could both facilitate a damage response necessary to isolate and repair the acute damage from injury and provide the intracellular machinery necessary for axon regrowth. Interestingly, serotonin neurons of the rostral group of raphe nuclei, which project their axons into the forebrain, display a robust ability to regenerate their axons unaided, counter to the widely held view that CNS axons cannot regenerate without experimental intervention after injury. Furthermore, initial evidence suggests that norepinephrine neurons within the locus coeruleus possess similar regenerative abilities. Several morphological characteristics of serotonin axon regeneration in adult mammals, observable using longitudinal in vivo imaging, are distinct from the known characteristics of unaided peripheral nerve regeneration, or of the regeneration seen in the spinal cord and optic nerve that occurs with experimental intervention. These results suggest that there is an alternative CNS program for axon regeneration that likely differs from that displayed by the PNS.
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Affiliation(s)
- Patrick Cooke
- Linden Lab, Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Haley Janowitz
- Linden Lab, Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Sarah E Dougherty
- Linden Lab, Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, United States
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Huang D, Grady FS, Peltekian L, Laing JJ, Geerling JC. Efferent projections of CGRP/Calca-expressing parabrachial neurons in mice. J Comp Neurol 2021; 529:2911-2957. [PMID: 33715169 DOI: 10.1002/cne.25136] [Citation(s) in RCA: 42] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Revised: 03/07/2021] [Accepted: 03/08/2021] [Indexed: 12/19/2022]
Abstract
The parabrachial nucleus (PB) is composed of glutamatergic neurons at the midbrain-hindbrain junction. These neurons form many subpopulations, one of which expresses Calca, which encodes the neuropeptide calcitonin gene-related peptide (CGRP). This Calca-expressing subpopulation has been implicated in a variety of homeostatic functions, but the overall distribution of Calca-expressing neurons in this region remains unclear. Also, while previous studies in rats and mice have identified output projections from CGRP-immunoreactive or Calca-expressing neurons, we lack a comprehensive understanding of their efferent projections. We began by identifying neurons with Calca mRNA and CGRP immunoreactivity in and around the PB, including populations in the locus coeruleus and motor trigeminal nucleus. Calca-expressing neurons in the PB prominently express the mu opioid receptor (Oprm1) and are distinct from neighboring neurons that express Foxp2 and Pdyn. Next, we used Cre-dependent anterograde tracing with synaptophysin-mCherry to map the efferent projections of these neurons. Calca-expressing PB neurons heavily target subregions of the amygdala, bed nucleus of the stria terminalis, basal forebrain, thalamic intralaminar and ventral posterior parvicellular nuclei, and hindbrain, in different patterns depending on the injection site location within the PB region. Retrograde axonal tracing revealed that the previously unreported hindbrain projections arise from a rostral-ventral subset of CGRP/Calca neurons. Finally, we show that these efferent projections of Calca-expressing neurons are distinct from those of neighboring PB neurons that express Pdyn. This information provides a detailed neuroanatomical framework for interpreting experimental work involving CGRP/Calca-expressing neurons and opioid action in the PB region.
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Affiliation(s)
- Dake Huang
- Department of Neurology, University of Iowa, Iowa, USA
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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: 26] [Impact Index Per Article: 8.7] [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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Kasamatsu T, Imamura K. Ocular dominance plasticity: Molecular mechanisms revisited. J Comp Neurol 2020; 528:3039-3074. [PMID: 32737874 DOI: 10.1002/cne.25001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Accepted: 07/10/2020] [Indexed: 12/14/2022]
Abstract
Ocular dominance plasticity (ODP) is a type of cortical plasticity operating in visual cortex of mammals that are endowed with binocular vision based on the competition-driven disparity. Earlier, a molecular mechanism was proposed that catecholamines play an important role in the maintenance of ODP in kittens. Having survived the initial test, the hypothesis was further advanced to identify noradrenaline (NA) as a key factor that regulates ODP in the immature cortex. Later, the ODP-promoting effect of NA is extended to the adult with age-related limitations. Following the enhanced NA availability, the chain events downstream lead to the β-adrenoreceptor-induced cAMP accumulation, which in turn activates the protein kinase A. Eventually, the protein kinase translocates to the cell nucleus to activate cAMP responsive element binding protein (CREB). CREB is a cellular transcription factor that controls the transcription of various genes, underpinning neuronal plasticity and long-term memory. In the advent of molecular genetics in that various types of new tools have become available with relative ease, ODP research has lightly adopted in the rodent model the original concepts and methodologies. Here, after briefly tracing the strategic maturation of our quest, the review moves to the later development of the field, with the emphasis placed around the following issues: (a) Are we testing ODP per se? (b) What does monocular deprivation deprive of the immature cortex? (c) The critical importance of binocular competition, (d) What is the adult plasticity? (e) Excitation-Inhibition balance in local circuits, and (f) Species differences in the animal models.
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Affiliation(s)
- Takuji Kasamatsu
- Smith-Kettlewell Eye Research Institute, San Francisco, California, USA
| | - Kazuyuki Imamura
- Department of Systems Life Engineering, Maebashi Institute of Technology, Maebashi-shi, Gunma, Japan
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Locus Coeruleus Modulates Neuroinflammation in Parkinsonism and Dementia. Int J Mol Sci 2020; 21:ijms21228630. [PMID: 33207731 PMCID: PMC7697920 DOI: 10.3390/ijms21228630] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Revised: 11/10/2020] [Accepted: 11/11/2020] [Indexed: 12/11/2022] Open
Abstract
Locus Coeruleus (LC) is the main noradrenergic nucleus of the central nervous system, and its neurons widely innervate the whole brain. LC is severely degenerated both in Alzheimer’s disease (AD) and in Parkinson’s disease (PD), years before the onset of clinical symptoms, through mechanisms that differ among the two disorders. Several experimental studies have shown that noradrenaline modulates neuroinflammation, mainly by acting on microglia/astrocytes function. In the present review, after a brief introduction on the anatomy and physiology of LC, we provide an overview of experimental data supporting a pathogenetic role of LC degeneration in AD and PD. Then, we describe in detail experimental data, obtained in vitro and in vivo in animal models, which support a potential role of neuroinflammation in such a link, and the specific molecules (i.e., released cytokines, glial receptors, including pattern recognition receptors and others) whose expression is altered by LC degeneration and might play a key role in AD/PD pathogenesis. New imaging and biochemical tools have recently been developed in humans to estimate in vivo the integrity of LC, the degree of neuroinflammation, and pathology AD/PD biomarkers; it is auspicable that these will allow in the near future to test the existence of a link between LC-neuroinflammation and neurodegeneration directly in patients.
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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: 25] [Impact Index Per Article: 6.3] [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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Janitzky K. Impaired Phasic Discharge of Locus Coeruleus Neurons Based on Persistent High Tonic Discharge-A New Hypothesis With Potential Implications for Neurodegenerative Diseases. Front Neurol 2020; 11:371. [PMID: 32477246 PMCID: PMC7235306 DOI: 10.3389/fneur.2020.00371] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Accepted: 04/14/2020] [Indexed: 12/21/2022] Open
Abstract
The locus coeruleus (LC) is a small brainstem nucleus with widely distributed noradrenergic projections to the whole brain, and loss of LC neurons is a prominent feature of age-related neurodegenerative diseases, such as Alzheimer's disease (AD) and Parkinson's disease (PD). This article discusses the hypothesis that in early stages of neurodegenerative diseases, the discharge mode of LC neurons could be changed to a persistent high tonic discharge, which in turn might impair phasic discharge. Since phasic discharge of LC neurons is required for the release of high amounts of norepinephrine (NE) in the brain to promote anti-inflammatory and neuroprotective effects, persistent high tonic discharge of LC neurons could be a key factor in the progression of neurodegenerative diseases. Transcutaneous vagal stimulation (t-VNS), a non-invasive technique that potentially increases phasic discharge of LC neurons, could therefore provide a non-pharmacological treatment approach in specific disease stages. This article focuses on LC vulnerability in neurodegenerative diseases, discusses the hypothesis that a persistent high tonic discharge of LC neurons might affect neurodegenerative processes, and finally reflects on t-VNS as a potentially useful clinical tool in specific stages of AD and PD.
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Affiliation(s)
- Kathrin Janitzky
- Department of Neurology, Carl von Ossietzky University Oldenburg, Oldenburg, Germany
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14
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Abstract
Why did I choose this particular topic for my lecture rather than the history of neuroscience or the history of the neuron? Simply because I believe that every disciple has the obligation to pay homage to their mentors once in their lifetime. My formation as a neuroscientist involved three such mentors spanned across three countries. The first was Spain, where I was born, completed my medical studies, and had my first glimpse of neuroscience at the Cajal Institute with Fernando de Castro. It was him who, in 1961, advised me to spend some time abroad, and to that purpose he obtained me a scholarship from the French government, that allowed me to settle in Paris. Once in France I had the good fortune to meet Prof. René Couteaux, another generous mentor, who took care of my stay in the country. Two years later, he made me a proposition to which I could only answer in the affirmative by offering me a research position in France. I got married (the best thing that happened in my life), and spent the next 57 years working on the cerebellum. The third person I want to honor and remember in this presentation is Sanford Louis Palay who was my postdoc professor during the 2 years I worked at Harvard Medical School in Boston. And as it turns out, all three of my mentors have made positive contributions to the history of the synapse. So, without further delay, let us dive in. Anat Rec, 303:1252-1279, 2020. © 2020 American Association for Anatomy.
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Affiliation(s)
- Constantino Sotelo
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, Paris, France
- Instituto de Neurociencias, Consejo Superior de Investigaciones Científicas (CSIC)-Universidad Miguel Hernández (UMH), San Juan de Alicante, Spain
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15
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Sherer LM, Catudio Garrett E, Morgan HR, Brewer ED, Sirrs LA, Shearin HK, Williams JL, McCabe BD, Stowers RS, Certel SJ. Octopamine neuron dependent aggression requires dVGLUT from dual-transmitting neurons. PLoS Genet 2020; 16:e1008609. [PMID: 32097408 PMCID: PMC7059954 DOI: 10.1371/journal.pgen.1008609] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2019] [Revised: 03/06/2020] [Accepted: 01/14/2020] [Indexed: 12/02/2022] Open
Abstract
Neuromodulators such as monoamines are often expressed in neurons that also release at least one fast-acting neurotransmitter. The release of a combination of transmitters provides both "classical" and "modulatory" signals that could produce diverse and/or complementary effects in associated circuits. Here, we establish that the majority of Drosophila octopamine (OA) neurons are also glutamatergic and identify the individual contributions of each neurotransmitter on sex-specific behaviors. Males without OA display low levels of aggression and high levels of inter-male courtship. Males deficient for dVGLUT solely in OA-glutamate neurons (OGNs) also exhibit a reduction in aggression, but without a concurrent increase in inter-male courtship. Within OGNs, a portion of VMAT and dVGLUT puncta differ in localization suggesting spatial differences in OA signaling. Our findings establish a previously undetermined role for dVGLUT in OA neurons and suggests that glutamate uncouples aggression from OA-dependent courtship-related behavior. These results indicate that dual neurotransmission can increase the efficacy of individual neurotransmitters while maintaining unique functions within a multi-functional social behavior neuronal network.
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Affiliation(s)
- Lewis M. Sherer
- Cellular, Molecular and Microbial Biology Graduate Program, University of Montana, Missoula, Montana, United States of America
| | - Elizabeth Catudio Garrett
- Cellular, Molecular and Microbial Biology Graduate Program, University of Montana, Missoula, Montana, United States of America
| | - Hannah R. Morgan
- Division of Biological Sciences, Center for Structural and Functional Neuroscience, University of Montana, Missoula, Montana, United States of America
| | - Edmond D. Brewer
- Division of Biological Sciences, Center for Structural and Functional Neuroscience, University of Montana, Missoula, Montana, United States of America
| | - Lucy A. Sirrs
- Division of Biological Sciences, Center for Structural and Functional Neuroscience, University of Montana, Missoula, Montana, United States of America
| | - Harold K. Shearin
- Cell Biology and Neuroscience Department, Montana State University, Bozeman, Montana, United States of America
| | - Jessica L. Williams
- Cell Biology and Neuroscience Department, Montana State University, Bozeman, Montana, United States of America
| | - Brian D. McCabe
- Brain Mind Institute, Swiss Federal Institute of Technology (EPFL), Lausanne, Switzerland
| | - R. Steven Stowers
- Cell Biology and Neuroscience Department, Montana State University, Bozeman, Montana, United States of America
| | - Sarah J. Certel
- Cellular, Molecular and Microbial Biology Graduate Program, University of Montana, Missoula, Montana, United States of America
- Division of Biological Sciences, Center for Structural and Functional Neuroscience, University of Montana, Missoula, Montana, United States of America
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16
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Jones BE. Arousal and sleep circuits. Neuropsychopharmacology 2020; 45:6-20. [PMID: 31216564 PMCID: PMC6879642 DOI: 10.1038/s41386-019-0444-2] [Citation(s) in RCA: 117] [Impact Index Per Article: 29.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Revised: 05/16/2019] [Accepted: 06/11/2019] [Indexed: 12/20/2022]
Abstract
The principal neurons of the arousal and sleep circuits are comprised by glutamate and GABA neurons, which are distributed within the reticular core of the brain and, through local and distant projections and interactions, regulate cortical activity and behavior across wake-sleep states. These are in turn modulated by the neuromodulatory systems that are comprised by acetylcholine, noradrenaline, dopamine, serotonin, histamine, orexin (hypocretin), and melanin-concentrating hormone (MCH) neurons. Glutamate and GABA neurons are heterogeneous in their profiles of discharge, forming distinct functional cell types by selective or maximal discharge during (1) waking and paradoxical (REM) sleep, (2) during slow wave sleep, (3) during waking, or (4) during paradoxical (REM) sleep. The neuromodulatory systems are each homogeneous in their profile of discharge, the majority discharging maximally during waking and paradoxical sleep or during waking. Only MCH neurons discharge maximally during sleep. They each exert their modulatory influence upon other neurons through excitatory and inhibitory receptors thus effecting a concerted differential change in the functionally different cell groups. Both arousal and sleep circuit neurons are homeostatically regulated as a function of their activity in part through changes in receptors. The major pharmacological agents used for the treatment of wake and sleep disorders act upon GABA and neuromodulatory transmission.
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Affiliation(s)
- Barbara E. Jones
- 0000 0004 1936 8649grid.14709.3bDepartment of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, QC H3A 2B4 Canada
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Dougherty SE, Kajstura TJ, Jin Y, Chan-Cortés MH, Kota A, Linden DJ. Catecholaminergic axons in the neocortex of adult mice regrow following brain injury. Exp Neurol 2019; 323:113089. [PMID: 31697941 DOI: 10.1016/j.expneurol.2019.113089] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2019] [Revised: 10/10/2019] [Accepted: 10/23/2019] [Indexed: 12/21/2022]
Abstract
Serotonin axons in the adult rodent brain can regrow and recover their function following several forms of injury including controlled cortical impact (CCI), a neocortical stab wound, or systemic amphetamine toxicity. To assess whether this capacity for regrowth is unique to serotonergic fibers, we used CCI and stab injury models to assess whether fibers from other neuromodulatory systems can also regrow following injury. Using tyrosine-hydoxylase (TH) immunohistochemistry we measured the density of catecholaminergic axons before and at various time points after injury. One week after CCI injury we observed a pronounced loss, across cortical layers, of TH+ axons posterior to the site of injury. One month after CCI injury the same was true of TH+ axons both anterior and posterior to the site of injury. This loss was followed by significant recovery of TH+ fiber density across cortical layers, both anterior and posterior to the site of injury, measured three months after injury. TH+ axon loss and recovery over weeks to months was also observed throughout cortical layers using the stab injury model. Double label immunohistochemistry revealed that nearly all TH+ axons in neocortical layer 1/2 are also dopamine-beta-hyroxylase+ (DBH+; presumed norepinephrine), while TH+ axons in layer 5 are a mixture of DBH+ and dopamine transporter+ types. This suggests that noradrenergic axons can regrow following CCI or stab injury in the adult mouse neocortex and leaves open the question of whether dopaminergic axons can do the same.
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Affiliation(s)
- Sarah E Dougherty
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, 725 N. Wolfe Street, 916 Hunterian Building, Baltimore, MD, USA
| | - Tymoteusz J Kajstura
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, 725 N. Wolfe Street, 916 Hunterian Building, Baltimore, MD, USA
| | - Yunju Jin
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, 725 N. Wolfe Street, 916 Hunterian Building, Baltimore, MD, USA; Department of Neurobiology and Anatomy, University of Utah, School of Medicine, 20 South 2030 East, Room 320 BPRB, Salt Lake City, UT, USA
| | - Michelle H Chan-Cortés
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, 725 N. Wolfe Street, 916 Hunterian Building, Baltimore, MD, USA
| | - Akhil Kota
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, 725 N. Wolfe Street, 916 Hunterian Building, Baltimore, MD, USA
| | - David J Linden
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, 725 N. Wolfe Street, 916 Hunterian Building, Baltimore, MD, USA.
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Papesh MH, Guevara Pinto JD. Spotting rare items makes the brain "blink" harder: Evidence from pupillometry. Atten Percept Psychophys 2019; 81:2635-2647. [PMID: 31222658 PMCID: PMC6858538 DOI: 10.3758/s13414-019-01777-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
In many visual search tasks (e.g., cancer screening, airport baggage inspections), the most serious search targets occur infrequently. As an ironic side effect, when observers finally encounter important objects (e.g., a weapon in baggage), they often fail to notice them, a phenomenon known as the low-prevalence effect (LPE). Although many studies have investigated LPE search errors, we investigated the attentional consequences of successful rare target detection. Using an attentional blink paradigm, we manipulated how often observers encountered the first serial target (T1), then measured its effects on their ability to detect a following target (T2). Across two experiments, we show that the LPE is more than just an inflated miss rate: When observers successfully detected rare targets, they were less likely to spot subsequent targets. Using pupillometry to index locus-coeruleus (LC) mediated attentional engagement, Experiment 2 confirmed that an LC refractory period mediates the attentional blink (`Nieuwenhuis, Gilzenrat, Holmes, & Cohen, 2005, Journal of Experimental Psychology: General, 134[3], 291-307), and that these effects emerge relatively quickly following T1 onset. Moreover, in both behavioral and pupil analyses, we found that detecting low-prevalence targets exacerbates the LC refractory period. Consequences for theories of the LPE are discussed.
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Affiliation(s)
- Megan H Papesh
- Department of Psychology, Louisiana State University, Baton Rouge, LA, USA.
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Sargin D, Jeoung HS, Goodfellow NM, Lambe EK. Serotonin Regulation of the Prefrontal Cortex: Cognitive Relevance and the Impact of Developmental Perturbation. ACS Chem Neurosci 2019; 10:3078-3093. [PMID: 31259523 DOI: 10.1021/acschemneuro.9b00073] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The prefrontal cortex is essential for both executive function and emotional regulation. The interrelationships among these behavioral domains are increasingly recognized, as well as their sensitivity to serotonin (5-hydroxytryptamine, 5-HT). Prefrontal cortex receives serotonergic inputs from the dorsal and median raphe nuclei and is modulated by multiple subtypes of 5-HT receptor across its layers and cell types. Extremes of serotonergic modulation alter mood regulation in vulnerable individuals, yet the impact of serotonin under more typical physiological parameters remains unclear. In this regard, new tools are permitting a closer examination of the behavioral impact of the serotonin system. Optogenetic and chemogenetic manipulations of dorsal raphe 5-HT neurons reveal that serotonin has a greater impact on executive function than previously appreciated. Domains that appear sensitive to fluctuations in 5-HT neuronal excitability include patience and cognitive flexibility. This work is broadly consistent with ex vivo research investigating how 5-HT regulates prefrontal cortex and its output projections. A growing literature suggests 5-HT modulation of these prefrontal circuits is unexpectedly flexible to alteration during development by genetic, behavioral, environmental or pharmacological manipulations, with lasting repercussions for cognition and emotional regulation. Here, we review the cellular and circuit mechanisms of prefrontal serotonergic modulation, investigate recent research into the cognitive consequences of the serotonergic system, and probe the lasting consequences of developmental perturbations. Understanding both the complexity of the prefrontal serotonin system and its sensitivity during development are essential to learn more about the vulnerabilities of this system in mood and anxiety disorders and the underappreciated cognitive consequences of these disorders and their treatment.
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Affiliation(s)
- Derya Sargin
- Department of Physiology, University of Toronto, Toronto, ON M5S 1A8, Canada
- Department of Physiology and Pharmacology, University of Calgary, Calgary AB T2N 1N4, Canada
| | - Ha-Seul Jeoung
- Department of Physiology, University of Toronto, Toronto, ON M5S 1A8, Canada
| | | | - Evelyn K. Lambe
- Department of Physiology, University of Toronto, Toronto, ON M5S 1A8, Canada
- Department of OBGYN, University of Toronto, Toronto, ON M5G 1E2, Canada
- Department of Psychiatry, University of Toronto, Toronto, ON M5T 1R8, Canada
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BDNF val66met association with serotonin transporter binding in healthy humans. Transl Psychiatry 2017; 7:e1029. [PMID: 28195567 PMCID: PMC5438027 DOI: 10.1038/tp.2016.295] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/15/2016] [Revised: 11/22/2016] [Accepted: 12/15/2016] [Indexed: 12/31/2022] Open
Abstract
The serotonin transporter (5-HTT) is a key feature of the serotonin system, which is involved in behavior, cognition and personality and implicated in neuropsychiatric illnesses including depression. The brain-derived neurotrophic factor (BDNF) val66met and 5-HTTLPR polymorphisms have predicted differences in 5-HTT levels in humans but with equivocal results, possibly due to limited sample sizes. Within the current study we evaluated these genetic predictors of 5-HTT binding with [11C]DASB positron emission tomography (PET) in a comparatively large cohort of 144 healthy individuals. We used a latent variable model to determine genetic effects on a latent variable (5-HTTLV), reflecting shared correlation across regional 5-HTT binding (amygdala, caudate, hippocampus, midbrain, neocortex, putamen and thalamus). Our data supported a significant BDNF val66met effect on 5-HTTLV such that met-carriers showed 2-7% higher subcortical 5-HTT binding compared with val/val individuals (P=0.042). Our data did not support a BDNF val66met effect in neocortex and 5-HTTLPR did not significantly predict 5-HTTLV. We did not observe evidence for an interaction between genotypes. Our findings indicate that met-carriers have increased subcortical 5-HTT binding. The small difference suggests limited statistical power may explain previously reported null effects. Our finding adds to emerging evidence that BDNF val66met contributes to differences in the human brain serotonin system, informing how variability in the 5-HTT level emerges and may represent an important molecular mediator of BDNF val66met effects on behavior and related risk for neuropsychiatric illness.
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Badin AS, Fermani F, Greenfield SA. The Features and Functions of Neuronal Assemblies: Possible Dependency on Mechanisms beyond Synaptic Transmission. Front Neural Circuits 2017; 10:114. [PMID: 28119576 PMCID: PMC5223595 DOI: 10.3389/fncir.2016.00114] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2016] [Accepted: 12/22/2016] [Indexed: 11/13/2022] Open
Abstract
"Neuronal assemblies" are defined here as coalitions within the brain of millions of neurons extending in space up to 1-2 mm, and lasting for hundreds of milliseconds: as such they could potentially link bottom-up, micro-scale with top-down, macro-scale events. The perspective first compares the features in vitro versus in vivo of this underappreciated "meso-scale" level of brain processing, secondly considers the various diverse functions in which assemblies may play a pivotal part, and thirdly analyses whether the surprisingly spatially extensive and prolonged temporal properties of assemblies can be described exclusively in terms of classic synaptic transmission or whether additional, different types of signaling systems are likely to operate. Based on our own voltage-sensitive dye imaging (VSDI) data acquired in vitro we show how restriction to only one signaling process, i.e., synaptic transmission, is unlikely to be adequate for modeling the full profile of assemblies. Based on observations from VSDI with its protracted spatio-temporal scales, we suggest that two other, distinct processes are likely to play a significant role in assembly dynamics: "volume" transmission (the passive diffusion of diverse bioactive transmitters, hormones, and modulators), as well as electrotonic spread via gap junctions. We hypothesize that a combination of all three processes has the greatest potential for deriving a realistic model of assemblies and hence elucidating the various complex brain functions that they may mediate.
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Affiliation(s)
- Antoine-Scott Badin
- Neuro-Bio Ltd., Culham Science CentreAbingdon, UK; Department of Physiology, Anatomy and Genetics, Mann Group, University of OxfordOxford, UK
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Zhang HQ, Zhang Y, Liu L, Li JL, Lu YC, Yu YY, Li H, Zhang T, Chan YS, Zhang FX, Li YQ. Neural connection supporting endogenous 5-hydroxytryptamine influence on autonomic activity in medial prefrontal cortex. Auton Neurosci 2016; 203:25-32. [PMID: 27932203 DOI: 10.1016/j.autneu.2016.11.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Revised: 11/17/2016] [Accepted: 11/29/2016] [Indexed: 12/26/2022]
Abstract
5-hydroxytryptamine (5-HT) transmission in the medial prefrontal cortex (mPFC) enhances or suppresses signal outflow to influence emotion-/cognition-based function performances and, putatively, the autonomic responses. The top-down cortical modulation of autonomic activities may be mediated in part through projections from mPFC to brain stem dorsal vagal complex (DVC). The abundant and heterogeneous densities of 5-HT fibers across laminae in mPFC suggest serotonergic innervation of mPFC-DVC projection neurons whereby endogenous 5-HT acts to regulate autonomic activities. The present study investigated the physical relationship between 5-HT fibers and the autonomic-related mPFC neurons by examining and quantitatively characterizing the 5-HT contacts upon retrogradely labeled mPFC-DVC projection neurons in pre- and infra-limbic cortices (PrL/IL) with light and electron microscopies combined with immunocytochemistry for 5-HT and presynaptic vesicle marker synaptophysin (Syn). 5-HT varicosities were observed, under confocal microscope, to form close appositions to or, at ultrastructural level, to form asymmetric axodendritic synapses and direct contacts upon the target neurons. About 16% of the entire 5-HTergic varicosities in lamina V of PrL/IL coexpressed Syn and about 24% of the peri-somatic 5-HTergic swellings demonstrated Syn-immunoreactivity (ir), suggesting a low frequency of putative synapses estimated at optical level. Ultrastructurally, examination of thirty-seven serially cut thin 5-HT boutons closely apposed to the labeled dendritic profiles demonstrated that only three contacts presented with identifiable asymmetric, synaptic membrane specializations. These data provide the first and direct morphological evidence supporting that endogenous 5-HT may be released mainly via direct contacts bearing no identifiable synaptic specializations as well as synapses, targeting autonomic-related mPFC neurons for autonomic regulation.
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Affiliation(s)
- Hao-Qiang Zhang
- Department of Anatomy and K.K. Leung Brain Research Centre, The Fourth Military Medical University, Xi'an, People's Republic of China; Department of Orthopedics, Xi-Jing Hospital, The Fourth Military Medical University, Xi'an, People's Republic of China
| | - Yong Zhang
- Department of Anatomy and K.K. Leung Brain Research Centre, The Fourth Military Medical University, Xi'an, People's Republic of China
| | - Lin Liu
- Department of Anatomy and K.K. Leung Brain Research Centre, The Fourth Military Medical University, Xi'an, People's Republic of China; Department of Dermatology, Xi-Jing Hospital, The Fourth Military Medical University, Xi'an, People's Republic of China
| | - Jin-Lian Li
- Department of Anatomy and K.K. Leung Brain Research Centre, The Fourth Military Medical University, Xi'an, People's Republic of China
| | - Ya-Cheng Lu
- Department of Anatomy and K.K. Leung Brain Research Centre, The Fourth Military Medical University, Xi'an, People's Republic of China
| | - Ying-Ying Yu
- Department of Anatomy and K.K. Leung Brain Research Centre, The Fourth Military Medical University, Xi'an, People's Republic of China; Department of Anatomy, Histology and Embryology, Basic Medical College, Fujian Medical University, Fuzhou, China
| | - Hui Li
- Department of Anatomy and K.K. Leung Brain Research Centre, The Fourth Military Medical University, Xi'an, People's Republic of China
| | - Ting Zhang
- Department of Anatomy and K.K. Leung Brain Research Centre, The Fourth Military Medical University, Xi'an, People's Republic of China
| | - Ying-Shing Chan
- Department of Physiology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, People's Republic of China
| | - Fu-Xing Zhang
- Department of Anatomy and K.K. Leung Brain Research Centre, The Fourth Military Medical University, Xi'an, People's Republic of China.
| | - Yun-Qing Li
- Department of Anatomy and K.K. Leung Brain Research Centre, The Fourth Military Medical University, Xi'an, People's Republic of China.
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Jin Y, Dougherty SE, Wood K, Sun L, Cudmore RH, Abdalla A, Kannan G, Pletnikov M, Hashemi P, Linden DJ. Regrowth of Serotonin Axons in the Adult Mouse Brain Following Injury. Neuron 2016; 91:748-762. [PMID: 27499084 PMCID: PMC4990493 DOI: 10.1016/j.neuron.2016.07.024] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2014] [Revised: 02/16/2016] [Accepted: 07/05/2016] [Indexed: 12/27/2022]
Abstract
It is widely believed that damaged axons in the adult mammalian brain have little capacity to regrow, thereby impeding functional recovery after injury. Studies using fixed tissue have suggested that serotonin neurons might be a notable exception, but remain inconclusive. We have employed in vivo two-photon microscopy to produce time-lapse images of serotonin axons in the neocortex of the adult mouse. Serotonin axons undergo massive retrograde degeneration following amphetamine treatment and subsequent slow recovery of axonal density, which is dominated by new growth with little contribution from local sprouting. A stab injury that transects serotonin axons running in the neocortex is followed by local regression of cut serotonin axons and followed by regrowth from cut ends into and across the stab rift zone. Regrowing serotonin axons do not follow the pathways left by degenerated axons. The regrown axons release serotonin and their regrowth is correlated with recovery in behavioral tests.
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Affiliation(s)
- Yunju Jin
- Solomon H. Snyder Department of Neuroscience, School of Medicine, Johns Hopkins University, 725 North Wolfe Street, Baltimore, MD 21205, USA
| | - Sarah E Dougherty
- Solomon H. Snyder Department of Neuroscience, School of Medicine, Johns Hopkins University, 725 North Wolfe Street, Baltimore, MD 21205, USA
| | - Kevin Wood
- Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, MI 48202, USA
| | - Landy Sun
- Solomon H. Snyder Department of Neuroscience, School of Medicine, Johns Hopkins University, 725 North Wolfe Street, Baltimore, MD 21205, USA
| | - Robert H Cudmore
- Solomon H. Snyder Department of Neuroscience, School of Medicine, Johns Hopkins University, 725 North Wolfe Street, Baltimore, MD 21205, USA
| | - Aya Abdalla
- Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, MI 48202, USA
| | - Geetha Kannan
- Solomon H. Snyder Department of Neuroscience, School of Medicine, Johns Hopkins University, 725 North Wolfe Street, Baltimore, MD 21205, USA; Department of Psychiatry and Department of Molecular and Comparative Pathobiology, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA; Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Mikhail Pletnikov
- Solomon H. Snyder Department of Neuroscience, School of Medicine, Johns Hopkins University, 725 North Wolfe Street, Baltimore, MD 21205, USA; Department of Psychiatry and Department of Molecular and Comparative Pathobiology, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA; Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Parastoo Hashemi
- Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, MI 48202, USA
| | - David J Linden
- Solomon H. Snyder Department of Neuroscience, School of Medicine, Johns Hopkins University, 725 North Wolfe Street, Baltimore, MD 21205, USA.
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Norepinephrine ignites local hotspots of neuronal excitation: How arousal amplifies selectivity in perception and memory. Behav Brain Sci 2015; 39:e200. [PMID: 26126507 DOI: 10.1017/s0140525x15000667] [Citation(s) in RCA: 337] [Impact Index Per Article: 37.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Emotional arousal enhances perception and memory of high-priority information but impairs processing of other information. Here, we propose that, under arousal, local glutamate levels signal the current strength of a representation and interact with norepinephrine (NE) to enhance high priority representations and out-compete or suppress lower priority representations. In our "glutamate amplifies noradrenergic effects" (GANE) model, high glutamate at the site of prioritized representations increases local NE release from the locus coeruleus (LC) to generate "NE hotspots." At these NE hotspots, local glutamate and NE release are mutually enhancing and amplify activation of prioritized representations. In contrast, arousal-induced LC activity inhibits less active representations via two mechanisms: 1) Where there are hotspots, lateral inhibition is amplified; 2) Where no hotspots emerge, NE levels are only high enough to activate low-threshold inhibitory adrenoreceptors. Thus, LC activation promotes a few hotspots of excitation in the context of widespread suppression, enhancing high priority representations while suppressing the rest. Hotspots also help synchronize oscillations across neural ensembles transmitting high-priority information. Furthermore, brain structures that detect stimulus priority interact with phasic NE release to preferentially route such information through large-scale functional brain networks. A surge of NE before, during, or after encoding enhances synaptic plasticity at NE hotspots, triggering local protein synthesis processes that enhance selective memory consolidation. Together, these noradrenergic mechanisms promote selective attention and memory under arousal. GANE not only reconciles apparently contradictory findings in the emotion-cognition literature but also extends previous influential theories of LC neuromodulation by proposing specific mechanisms for how LC-NE activity increases neural gain.
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25
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Bach-y-Rita P. Theoretical and Practical Considerations in the Restoration of Function After Stroke. Top Stroke Rehabil 2015; 8:1-15. [PMID: 14523734 DOI: 10.1310/8t1t-etxu-8pdf-9x7f] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Recovery of function after stroke appears to include elements of both restoration and compensation. The brain is highly plastic, which allows reorganization after damage. Stroke produces permanent damage to the brain, so recovery must be based on activity in surviving cells that are either adjacent, contralateral, or in a different region. Furthermore, representation of a particular function in the brain is usually not limited to a single brain region. Multiple representation provides the opportunity for brain reorganization; functions are assumed by surviving brain structures. Compensation can be the initial response in the recovery phase and may persist through later phases because of the new habits formed (as the restraint therapy studies of Taub and others would suggest), because the damage to the brain is extensive and hinders restoration, because of secondary pathology, such as tendon shortening and muscle wasting, that does not allow brain reorganization to be translated into functional recovery, or because of inadequate (especially late) rehabilitation.
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Affiliation(s)
- P Bach-y-Rita
- Department of Rehabilitation Medicine, University of Wisconsin-Madison, USA
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Marzo A, Totah NK, Neves RM, Logothetis NK, Eschenko O. Unilateral electrical stimulation of rat locus coeruleus elicits bilateral response of norepinephrine neurons and sustained activation of medial prefrontal cortex. J Neurophysiol 2014; 111:2570-88. [DOI: 10.1152/jn.00920.2013] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The brain stem nucleus locus coeruleus (LC) is thought to modulate cortical excitability by norepinephrine (NE) release in LC forebrain targets. The effects of LC burst discharge, typically evoked by a strong excitatory input, on cortical ongoing activity are poorly understood. To address this question, we combined direct electrical stimulation of LC (LC-DES) with extracellular recording in LC and medial prefrontal cortex (mPFC), an important cortical target of LC. LC-DES consisting of single pulses (0.1–0.5 ms, 0.01–0.05 mA) or pulse trains (20–50 Hz, 50–200 ms) evoked short-latency excitatory and inhibitory LC responses bilaterally as well as a delayed rebound excitation occurring ∼100 ms after stimulation offset. The pulse trains, but not single pulses, reliably elicited mPFC activity change, which was proportional to the stimulation strength. The firing rate of ∼50% of mPFC units was significantly modulated by the strongest LC-DES. Responses of mPFC putative pyramidal neurons included fast (∼100 ms), transient (∼100–200 ms) inhibition (10% of units) or excitation (13%) and delayed (∼500 ms), sustained (∼1 s) excitation (26%). The sustained spiking resembled NE-dependent mPFC activity during the delay period of working memory tasks. Concurrently, the low-frequency (0.1–8 Hz) power of the local field potential (LFP) decreased and high-frequency (>20 Hz) power increased. Overall, the DES-induced LC firing pattern resembled the naturalistic biphasic response of LC-NE neurons to alerting stimuli and was associated with a shift in cortical state that may optimize processing of behaviorally relevant events.
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Affiliation(s)
- Aude Marzo
- Max Planck Institute for Biological Cybernetics, Tübingen, Germany; and
| | - Nelson K. Totah
- Max Planck Institute for Biological Cybernetics, Tübingen, Germany; and
| | - Ricardo M. Neves
- Max Planck Institute for Biological Cybernetics, Tübingen, Germany; and
| | - Nikos K. Logothetis
- Max Planck Institute for Biological Cybernetics, Tübingen, Germany; and
- Centre for Imaging Sciences, Biomedical Imaging Institute, University of Manchester, Manchester, United Kingdom
| | - Oxana Eschenko
- Max Planck Institute for Biological Cybernetics, Tübingen, Germany; and
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Göthert M. Serotonin discovery and stepwise disclosure of 5-HT receptor complexity over four decades. Part I. General background and discovery of serotonin as a basis for 5-HT receptor identification. Pharmacol Rep 2014; 65:771-86. [PMID: 24145072 DOI: 10.1016/s1734-1140(13)71059-4] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2013] [Revised: 03/28/2013] [Indexed: 11/16/2022]
Abstract
This review contains background information on the serotonin system, furthermore the suggestion to introduce the term Contemporary Witness Report (CWR) for a novel type of review and, as the main part, an overview over the history of serotonin discovery as a basis for the identification of its receptor heterogeneity and the increase in complexity by genetic and allosteric variation. The present article conforms to CWRs in historical and autobiographical elements, in more emphasis on the author's work than in conventional reviews and in aspects neglected in previous reviews, but not in the main feature namely the work of a scientist with comprehensive expertise in a field in which, over long time, he/she continuously performed research and published. A scientist complying with these requirements is a contemporary witness in that field. His report on the scientific achievements in that period, a CWR, comprises confirmation and putative re-interpretation of data from a superior viewpoint. Identification of serotonin's vascular properties (publication year: 1912) as an "adrenaline mimicking substance" (without attempt to isolate it) by O'Connor preceded the discovery of serotonin in the gastrointestinal tract by Erspamer [1937] and in blood by Rapport [1948, 1949], who identified its structure as 5-hydroxytryptamine [1949]. Detection as a neurotransmitter in invertebrates suggested its occurrence in vertebrate CNS as well. This was verified by finding it in dog, rat and rabbit brain [1953]. The Falck-Hillarp technique [1962] visualized serotonin neurones as fluorescent structures. The neurotoxin 5,7-dihydroxytryptamine [1972] indirectly proved the involvement of 5-HT in multiple CNS functions.
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Affiliation(s)
- Manfred Göthert
- University Clinics of Bonn, BMZ, Institute of Pharmacology and Toxicology, Sigmund-Freud-Str. 25, D-53127 Bonn, Germany. or
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Gagnon D, Parent M. Distribution of VGLUT3 in highly collateralized axons from the rat dorsal raphe nucleus as revealed by single-neuron reconstructions. PLoS One 2014; 9:e87709. [PMID: 24504335 PMCID: PMC3913638 DOI: 10.1371/journal.pone.0087709] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2013] [Accepted: 01/03/2014] [Indexed: 12/11/2022] Open
Abstract
This study aimed at providing the first detailed morphological description, at the single-cell level, of the rat dorsal raphe nucleus neurons, including the distribution of the VGLUT3 protein within their axons. Electrophysiological guidance procedures were used to label dorsal raphe nucleus neurons with biotinylated dextran amine. The somatodendritic and axonal arborization domains of labeled neurons were reconstructed entirely from serial sagittal sections using a computerized image analysis system. Under anaesthesia, dorsal raphe nucleus neurons display highly regular (1.72±0.50 Hz) spontaneous firing patterns. They have a medium size cell body (9.8±1.7 µm) with 2–4 primary dendrites mainly oriented anteroposteriorly. The ascending axons of dorsal raphe nucleus are all highly collateralized and widely distributed (total axonal length up to 18.7 cm), so that they can contact, in various combinations, forebrain structures as diverse as the striatum, the prefrontal cortex and the amygdala. Their morphological features and VGLUT3 content vary significantly according to their target sites. For example, high-resolution confocal analysis of the distribution of VGLUT3 within individually labeled-axons reveals that serotonin axon varicosities displaying VGLUT3 are larger (0.74±0.03 µm) than those devoid of this protein (0.55±0.03 µm). Furthermore, the percentage of axon varicosities that contain VGLUT3 is higher in the striatum (93%) than in the motor cortex (75%), suggesting that a complex trafficking mechanism of the VGLUT3 protein is at play within highly collateralized axons of the dorsal raphe nucleus neurons. Our results provide the first direct evidence that the dorsal raphe nucleus ascending projections are composed of widely distributed neuronal systems, whose capacity to co-release serotonin and glutamate varies from one forebrain locus to the other.
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Affiliation(s)
- Dave Gagnon
- Centre de recherche de l’Institut universitaire en santé mentale de Québec, Department of Psychiatry and Neuroscience, Faculty of medicine, Université Laval, Quebec City, QC, Canada
| | - Martin Parent
- Centre de recherche de l’Institut universitaire en santé mentale de Québec, Department of Psychiatry and Neuroscience, Faculty of medicine, Université Laval, Quebec City, QC, Canada
- * E-mail:
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Trudeau LE, Hnasko TS, Wallén-Mackenzie A, Morales M, Rayport S, Sulzer D. The multilingual nature of dopamine neurons. PROGRESS IN BRAIN RESEARCH 2014; 211:141-64. [PMID: 24968779 DOI: 10.1016/b978-0-444-63425-2.00006-4] [Citation(s) in RCA: 96] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
The ability of dopamine (DA) neurons to release other transmitters in addition to DA itself has been increasingly recognized, hence the concept of their multilingual nature. A subset of DA neurons, mainly found in the ventral tegmental area, express VGLUT2, allowing them to package and release glutamate onto striatal spiny projection neurons and cholinergic interneurons. Some dopaminergic axon terminals release GABA. Glutamate release by DA neurons has a developmental role, facilitating axonal growth and survival, and may determine in part the critical contribution of the ventral striatum to psychostimulant-induced behavior. Vesicular glutamate coentry may have synergistic effects on vesicular DA filling. The multilingual transmission of DA neurons across multiple striatal domains and the increasing insight into the role of glutamate cotransmission in the ventral striatum highlight the importance of analyzing DA neuron transmission at the synaptic level.
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Affiliation(s)
- Louis-Eric Trudeau
- Department of Pharmacology, Neuroscience Research Group, Faculty of Medicine, Université de Montréal, Montréal, QC, Canada; Department of Neurosciences, Neuroscience Research Group, Faculty of Medicine, Université de Montréal, Montréal, QC, Canada.
| | - Thomas S Hnasko
- Department of Neurosciences, University of California San Diego, La Jolla, CA, USA
| | - Asa Wallén-Mackenzie
- Unit of Functional Neurobiology, Department of Neuroscience, Uppsala University, Uppsala, Sweden
| | - Marisela Morales
- National Institute on Drug Abuse, Intramural Research Program, Neuronal Networks Section, Baltimore, MD, USA
| | - Steven Rayport
- Department of Psychiatry, Columbia University, New York, NY, USA; Department of Molecular Therapeutics, NYS Psychiatric Institute, New York, NY, USA
| | - David Sulzer
- Department of Psychiatry, Columbia University, New York, NY, USA; Department of Neurology, Columbia University, New York, NY, USA; Department of Pharmacology, Columbia University, New York, NY, USA; Department of Molecular Therapeutics, NYS Psychiatric Institute, New York, NY, USA
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Serotonin 5-HT1A receptors as targets for agents to treat psychiatric disorders: rationale and current status of research. CNS Drugs 2013; 27:703-16. [PMID: 23757185 DOI: 10.1007/s40263-013-0071-0] [Citation(s) in RCA: 225] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Psychiatric disorders represent a large economic burden in modern societies. However, pharmacological treatments are still far from optimal. Drugs used in the treatment of major depressive disorder (MDD) and anxiety disorders (selective serotonin [5-HT] reuptake inhibitors [SSRIs] and serotonin-noradrenaline reuptake inhibitors [SNRIs]) are pharmacological refinements of first-generation tricyclic drugs, discovered by serendipity, and show low efficacy and slowness of onset. Moreover, antipsychotic drugs are partly effective in positive symptoms of schizophrenia, yet they poorly treat negative symptoms and cognitive deficits. The present article reviews the neurobiological basis of 5-HT1A receptor (5-HT1A-R) function and the role of pre- and postsynaptic 5-HT1A-Rs in the treatment of MDD, anxiety and psychotic disorders. The activation of postsynaptic 5-HT1A-Rs in corticolimbic areas appears beneficial for the therapeutic action of antidepressant drugs. However, presynaptic 5-HT1A-Rs play a detrimental role in MDD, since individuals with high density or function of presynaptic 5-HT1A-Rs are more susceptible to mood disorders and suicide, and respond poorly to antidepressant drugs. Moreover, the indirect activation of presynaptic 5-HT1A-Rs by SSRIs/SNRIs reduces 5-HT neuron activity and terminal 5-HT release, thus opposing the elevation of extracellular 5-HT produced by blockade of the serotonin transporter (SERT) in the forebrain. Chronic antidepressant treatment desensitizes presynaptic 5-HT1A-Rs, thus reducing the effectiveness of the 5-HT1A autoreceptor-mediated negative feedback. The prevention of this process by the non-selective partial agonist pindolol accelerates clinical antidepressant effects. Two new antidepressant drugs, vilazodone (marketed in the USA) and vortioxetine (in development) incorporate partial 5-HT1A-R agonist properties with SERT blockade. Several studies with transgenic mice have also established the respective role of pre- and postsynaptic 5-HT1A-Rs in MDD and anxiety. In agreement with pharmacological studies, presynaptic and postsynaptic 5-HT1A-R activation appears necessary for anxiolytic and antidepressant effects, respectively, yet, neurodevelopmental roles for 5-HT1A-Rs are also involved. Likewise, the use of small interference RNA has enabled the showing of robust antidepressant-like effects in mice after selective knock-down of 5-HT1A autoreceptors. Postsynaptic 5-HT1A-Rs in the prefrontal cortex (PFC) also appear important for the superior clinical effects of clozapine and other second-generation (atypical) antipsychotic drugs in the treatment of schizophrenia and related psychotic disorders. Despite showing a moderate in vitro affinity for 5-HT1A-Rs in binding assays, clozapine displays functional agonist properties at this receptor type in vivo. The stimulation of 5-HT1A-Rs in the PFC leads to the distal activation of the mesocortical pathway and to an increased dopamine release in PFC, an effect likely involved in the clinical actions of clozapine in negative symptoms and cognitive deficits in schizophrenia. The anxiolytic/antidepressant properties of 5-HT1A-R agonists in preclinical tests raised expectations enormously. However, these agents have achieved little clinical success, possibly due to their partial agonist character at postsynaptic 5-HT1A-Rs, together with full agonist properties at presynaptic 5-HT1A autoreceptors, as well as their gastrointestinal side effects. The partial 5-HT1A-R agonists buspirone, gepirone, and tandospirone are marketed as anxiolytic drugs, and buspirone is also used as an augmentation strategy in MDD. The development of new 5-HT1A-R agonists with selectivity for postsynaptic 5-HT1A-Rs may open new perspectives in the field.
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Abstract
The central noradrenergic neurone, like the peripheral sympathetic neurone, is characterized by a diffusely arborizing terminal axonal network. The central neurones aggregate in distinct brainstem nuclei, of which the locus coeruleus (LC) is the most prominent. LC neurones project widely to most areas of the neuraxis, where they mediate dual effects: neuronal excitation by α₁-adrenoceptors and inhibition by α₂-adrenoceptors. The LC plays an important role in physiological regulatory networks. In the sleep/arousal network the LC promotes wakefulness, via excitatory projections to the cerebral cortex and other wakefulness-promoting nuclei, and inhibitory projections to sleep-promoting nuclei. The LC, together with other pontine noradrenergic nuclei, modulates autonomic functions by excitatory projections to preganglionic sympathetic, and inhibitory projections to preganglionic parasympathetic neurones. The LC also modulates the acute effects of light on physiological functions ('photomodulation'): stimulation of arousal and sympathetic activity by light via the LC opposes the inhibitory effects of light mediated by the ventrolateral preoptic nucleus on arousal and by the paraventricular nucleus on sympathetic activity. Photostimulation of arousal by light via the LC may enable diurnal animals to function during daytime. LC neurones degenerate early and progressively in Parkinson's disease and Alzheimer's disease, leading to cognitive impairment, depression and sleep disturbance.
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Affiliation(s)
- Elemer Szabadi
- Division of Psychiatry, University of Nottingham, Nottingham, UK.
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Agster KL, Mejias-Aponte CA, Clark BD, Waterhouse BD. Evidence for a regional specificity in the density and distribution of noradrenergic varicosities in rat cortex. J Comp Neurol 2013; 521:2195-207. [PMID: 23184811 PMCID: PMC4529674 DOI: 10.1002/cne.23270] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2011] [Revised: 11/09/2012] [Accepted: 11/13/2012] [Indexed: 11/10/2022]
Abstract
The brainstem nucleus locus coeruleus (LC) is the sole source of norepinephrine (NE)-containing fibers in the mammalian cortex. Previous studies suggest that the density of noradrenergic fibers in rat is relatively uniform across cortical regions and that cells in the nucleus discharge en masse. This implies that activation of the LC results in equivalent release of NE throughout the cortex. However, it is possible that there could be differences in the density of axonal varicosities across regions, and that these differences, rather than a difference in fiber density, may contribute to the regulation of NE efflux. Quantification of dopamine β-hydroxylase (DβH)-immunostained varicosities was performed on several cortical regions and in the ventral posterior medial (VPM) thalamus by using unbiased sampling methods. The density of DβH varicosities is greater in the prefrontal cortex than in motor, somatosensory, or piriform cortices, greater in superficial than in deep layers of cortex, and greater in the VPM than in the somatosensory cortex. Our results provide anatomical evidence for non-uniform release of NE across functionally discrete cortical regions. This morphology may account for a differential, region-specific, impact of LC output on different cortical areas.
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Affiliation(s)
- Kara L. Agster
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA 19129
| | | | - Brian D. Clark
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA 19129
| | - Barry D. Waterhouse
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA 19129
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Hertz L, Xu J, Song D, Du T, Yan E, Peng L. Brain glycogenolysis, adrenoceptors, pyruvate carboxylase, Na(+),K(+)-ATPase and Marie E. Gibbs' pioneering learning studies. Front Integr Neurosci 2013; 7:20. [PMID: 23565080 PMCID: PMC3615183 DOI: 10.3389/fnint.2013.00020] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2013] [Accepted: 03/15/2013] [Indexed: 01/02/2023] Open
Abstract
The involvement of glycogenolysis, occurring in astrocytes but not in neurons, in learning is undisputed (Duran et al., 2013). According to one school of thought the role of astrocytes for learning is restricted to supply of substrate for neuronal oxidative metabolism. The present "perspective" suggests a more comprehensive and complex role, made possible by lack of glycogen degradation, unless specifically induced by either (1) activation of astrocytic receptors, perhaps especially β-adrenergic or (2) even small increases in extracellular K(+) concentration above its normal resting level. It discusses (1) the known importance of glycogenolysis for glutamate formation, requiring pyruvate carboxylation; (2) the established role of K(+)-stimulated glycogenolysis for K(+) uptake in cultured astrocytes, which probably indicates that astrocytes are an integral part of cellular K(+) homeostasis in the brain in vivo; and (3) the plausible role of transmitter-induced glycogenolysis, stimulating Na(+),K(+)-ATPase/NKCC1 activity and thereby contributing both to the post-excitatory undershoot in extracellular K(+) concentration and the memory-enhancing effect of transmitter-mediated reduction of slow neuronal afterhyperpolarization (sAHP).
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Affiliation(s)
| | | | | | | | | | - Liang Peng
- Department of Clinical Pharmacology, China Medical UniversityShenyang, People's Republic of China
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35
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Krahl SE, Clark KB. Vagus nerve stimulation for epilepsy: A review of central mechanisms. Surg Neurol Int 2012; 3:S255-9. [PMID: 23230530 PMCID: PMC3514919 DOI: 10.4103/2152-7806.103015] [Citation(s) in RCA: 101] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2012] [Accepted: 09/04/2012] [Indexed: 11/21/2022] Open
Abstract
In a previous paper, the anatomy and physiology of the vagus nerve was discussed in an attempt to explain which vagus nerve fibers and branches are affected by clinically relevant electrical stimulation. This companion paper presents some of vagus nerve stimulation's putative central nervous system mechanisms of action by summarizing known anatomical projections of vagal afferents and their effects on brain biogenic amine pathways and seizure expression.
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Affiliation(s)
- Scott E Krahl
- Research and Development Service, VA Greater Los Angeles Healthcare System, Los Angeles, California ; Department of Neurosurgery, University of California, Los Angeles, California
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36
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COMMUNICATION. Br J Pharmacol 2012. [DOI: 10.1111/j.1476-5381.1987.tb16603.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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Rapid effects of hearing song on catecholaminergic activity in the songbird auditory pathway. PLoS One 2012; 7:e39388. [PMID: 22724011 PMCID: PMC3378548 DOI: 10.1371/journal.pone.0039388] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2012] [Accepted: 05/23/2012] [Indexed: 11/19/2022] Open
Abstract
Catecholaminergic (CA) neurons innervate sensory areas and affect the processing of sensory signals. For example, in birds, CA fibers innervate the auditory pathway at each level, including the midbrain, thalamus, and forebrain. We have shown previously that in female European starlings, CA activity in the auditory forebrain can be enhanced by exposure to attractive male song for one week. It is not known, however, whether hearing song can initiate that activity more rapidly. Here, we exposed estrogen-primed, female white-throated sparrows to conspecific male song and looked for evidence of rapid synthesis of catecholamines in auditory areas. In one hemisphere of the brain, we used immunohistochemistry to detect the phosphorylation of tyrosine hydroxylase (TH), a rate-limiting enzyme in the CA synthetic pathway. We found that immunoreactivity for TH phosphorylated at serine 40 increased dramatically in the auditory forebrain, but not the auditory thalamus and midbrain, after 15 min of song exposure. In the other hemisphere, we used high pressure liquid chromatography to measure catecholamines and their metabolites. We found that two dopamine metabolites, dihydroxyphenylacetic acid and homovanillic acid, increased in the auditory forebrain but not the auditory midbrain after 30 min of exposure to conspecific song. Our results are consistent with the hypothesis that exposure to a behaviorally relevant auditory stimulus rapidly induces CA activity, which may play a role in auditory responses.
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Neurotransmitter segregation: functional and plastic implications. Prog Neurobiol 2012; 97:277-87. [PMID: 22531669 DOI: 10.1016/j.pneurobio.2012.04.004] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2011] [Revised: 03/21/2012] [Accepted: 04/10/2012] [Indexed: 12/25/2022]
Abstract
Synaptic cotransmission is the ability of neurons to use more than one transmitter to convey synaptic signals. Cotransmission was originally described as the presence of a classic transmitter, which conveys main signal, along one or more cotransmitters that modulate transmission, later on, it was found cotransmission of classic transmitters. It has been generally accepted that neurons store and release the same set of transmitters in all their synaptic processes. However, some findings that show axon endings of individual neurons storing and releasing different sets of transmitters, are not in accordance with this assumption, and give support to the hypothesis that neurons can segregate transmitters to different synapses. Here, we review the studies showing segregation of transmitters in invertebrate and mammalian central nervous system neurons, and correlate them with our results obtained in sympathetic neurons. Our data show that these neurons segregate even classic transmitters to separated axons. Based on our data we suggest that segregation is a plastic phenomenon and responds to functional synaptic requirements, and to 'environmental' cues such as neurotrophins. We propose that neurons have the machinery to guide the different molecules required in synaptic transmission through axons and sort them to different axon endings. We believe that transmitter segregation improves neuron interactions during cotransmission and gives them selective and better control of synaptic plasticity.
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Matragrano LL, Sanford SE, Salvante KG, Beaulieu M, Sockman KW, Maney DL. Estradiol-dependent modulation of serotonergic markers in auditory areas of a seasonally breeding songbird. Behav Neurosci 2011; 126:110-22. [PMID: 21942431 DOI: 10.1037/a0025586] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Because no organism lives in an unchanging environment, sensory processes must remain plastic so that in any context, they emphasize the most relevant signals. As the behavioral relevance of sociosexual signals changes along with reproductive state, the perception of those signals is altered by reproductive hormones such as estradiol (E2). We showed previously that in white-throated sparrows, immediate early gene responses in the auditory pathway of females are selective for conspecific male song only when plasma E2 is elevated to breeding-typical levels. In this study, we looked for evidence that E2-dependent modulation of auditory responses is mediated by serotonergic systems. In female nonbreeding white-throated sparrows treated with E2, the density of fibers immunoreactive for serotonin transporter innervating the auditory midbrain and rostral auditory forebrain increased compared with controls. E2 treatment also increased the concentration of the serotonin metabolite 5-HIAA in the caudomedial mesopallium of the auditory forebrain. In a second experiment, females exposed to 30 min of conspecific male song had higher levels of 5-HIAA in the caudomedial nidopallium of the auditory forebrain than birds not exposed to song. Overall, we show that in this seasonal breeder, (a) serotonergic fibers innervate auditory areas; (b) the density of those fibers is higher in females with breeding-typical levels of E2 than in nonbreeding, untreated females; and (c) serotonin is released in the auditory forebrain within minutes in response to conspecific vocalizations. Our results are consistent with the hypothesis that E2 acts via serotonin systems to alter auditory processing.
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Maney DL, Pinaud R, Pinaud R. Estradiol-dependent modulation of auditory processing and selectivity in songbirds. Front Neuroendocrinol 2011; 32:287-302. [PMID: 21146556 PMCID: PMC3119742 DOI: 10.1016/j.yfrne.2010.12.002] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/30/2010] [Revised: 11/26/2010] [Accepted: 12/02/2010] [Indexed: 10/18/2022]
Abstract
The steroid hormone estradiol plays an important role in reproductive development and behavior and modulates a wide array of physiological and cognitive processes. Recently, reports from several research groups have converged to show that estradiol also powerfully modulates sensory processing, specifically, the physiology of central auditory circuits in songbirds. These investigators have discovered that (1) behaviorally-relevant auditory experience rapidly increases estradiol levels in the auditory forebrain; (2) estradiol instantaneously enhances the responsiveness and coding efficiency of auditory neurons; (3) these changes are mediated by a non-genomic effect of brain-generated estradiol on the strength of inhibitory neurotransmission; and (4) estradiol regulates biochemical cascades that induce the expression of genes involved in synaptic plasticity. Together, these findings have established estradiol as a central regulator of auditory function and intensified the need to consider brain-based mechanisms, in addition to peripheral organ dysfunction, in hearing pathologies associated with estrogen deficiency.
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Affiliation(s)
- Donna L Maney
- Department of Psychology, Emory University, Atlanta, GA, USA
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Matragrano LL, Sanford SE, Salvante KG, Sockman KW, Maney DL. Estradiol-dependent catecholaminergic innervation of auditory areas in a seasonally breeding songbird. Eur J Neurosci 2011; 34:416-25. [PMID: 21714815 DOI: 10.1111/j.1460-9568.2011.07751.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A growing body of evidence suggests that gonadal steroids such as estradiol (E2) alter neural responses not only in brain regions associated with reproductive behavior but also in sensory areas. Because catecholamine systems are involved in sensory processing and selective attention, and because they are sensitive to E2 in many species, they may mediate the neural effects of E2 in sensory areas. Here, we tested the effects of E2 on catecholaminergic innervation, synthesis and activity in the auditory system of white-throated sparrows, a seasonally breeding songbird in which E2 promotes selective auditory responses to song. Non-breeding females with regressed ovaries were held on a winter-like photoperiod and implanted with silastic capsules containing either no hormone or E2. In one hemisphere of the brain, we used immunohistochemistry to quantify fibers immunoreactive for tyrosine hydroxylase or dopamine beta-hydroxylase in the auditory forebrain, thalamus and midbrain. E2 treatment increased catecholaminergic innervation in the same areas of the auditory system in which E2 promotes selectivity for song. In the contralateral hemisphere we quantified dopamine, norepinephrine and their metabolites in tissue punches using HPLC. Norepinephrine increased in the auditory forebrain, but not the midbrain, after E2 treatment. We found that evidence of interhemispheric differences, both in immunoreactivity and catecholamine content that did not depend on E2 treatment. Overall, our results show that increases in plasma E2 typical of the breeding season enhanced catecholaminergic innervation and synthesis in some parts of the auditory system, raising the possibility that catecholamines play a role in E2-dependent auditory plasticity in songbirds.
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Affiliation(s)
- Lisa L Matragrano
- Department of Psychology, Emory University, 26 Eagle Row, Atlanta, GA, USA.
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Sotelo C. Camillo Golgi and Santiago Ramon y Cajal: The anatomical organization of the cortex of the cerebellum. Can the neuron doctrine still support our actual knowledge on the cerebellar structural arrangement? ACTA ACUST UNITED AC 2011; 66:16-34. [DOI: 10.1016/j.brainresrev.2010.05.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2010] [Accepted: 05/19/2010] [Indexed: 10/19/2022]
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Sakai K, Takahashi K, Anaclet C, Lin JS. Sleep-waking discharge of ventral tuberomammillary neurons in wild-type and histidine decarboxylase knock-out mice. Front Behav Neurosci 2010; 4:53. [PMID: 21060718 PMCID: PMC2972729 DOI: 10.3389/fnbeh.2010.00053] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2010] [Accepted: 07/21/2010] [Indexed: 01/30/2023] Open
Abstract
Using extracellular single-unit recordings, we have determined the characteristics of neurons in the ventral tuberomammillary nucleus (VTM) of wild-type (WT) and histidine decarboxylase knock-out (HDC-KO) mice during the sleep-waking cycle. The VTM neurons of HDC-KO mice showed no histamine immunoreactivity, but were immunoreactive for the histaminergic (HA) neuron markers adenosine deaminase and glutamic acid decarboxylase 67. In the VTM of WT mice, we found waking (W)-specific, non-W-specific W-active, sleep-active, W and paradoxical sleep (PS)-active, and state-indifferent neuron groups. We previously demonstrated in WT mice that only W-specific neurons are histaminergic and that they are characterized by a triphasic broad action potential. In the VTM of HDC-KO mice, we found all these groups of state-dependent and state-indifferent neurons, including W-specific neurons that were characterized by a triphasic broad action potential and a W-specific slow tonic discharge, as in WT mice. The W-specific neurons ceased firing before the onset of electroencephalogram (EEG) synchronization, the first EEG sign of sleep, and remained silent during both slow-wave sleep (SWS) and PS. At the transition from SWS to W, they discharged after the onset of EEG activation, the first EEG sign of W. They either responded to an arousing stimulus with a long delay or did not respond. They therefore presented exactly the same characteristics as those seen in the VTM of WT mice. Thus VTM neurons deprived of their natural transmitter histamine still exhibit the firing properties of W-specific HA neurons.
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Affiliation(s)
- Kazuya Sakai
- INSERM U628, Claude Bernard University Lyon 1 Lyon, France
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Certel SJ, Leung A, Lin CY, Perez P, Chiang AS, Kravitz EA. Octopamine neuromodulatory effects on a social behavior decision-making network in Drosophila males. PLoS One 2010; 5:e13248. [PMID: 20967276 PMCID: PMC2953509 DOI: 10.1371/journal.pone.0013248] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2010] [Accepted: 09/05/2010] [Indexed: 11/18/2022] Open
Abstract
Situations requiring rapid decision-making in response to dynamic environmental demands occur repeatedly in natural environments. Neuromodulation can offer important flexibility to the output of neural networks in coping with changing conditions, but the contribution of individual neuromodulatory neurons in social behavior networks remains relatively unknown. Here we manipulate the Drosophila octopaminergic system and assay changes in adult male decision-making in courtship and aggression paradigms. When the functional state of OA neural circuits is enhanced, males exhibit elevated courtship behavior towards other males in both behavioral contexts. Eliminating the expression of the male form of the neural sex determination factor, Fruitless (Fru(M)), in three OA suboesophageal ganglia (SOG) neurons also leads to increased male-male courtship behavior in these same contexts. We analyzed the fine anatomical structure through confocal examination of labeled single neurons to determine the arborization patterns of each of the three Fru(M)-positive OA SOG neurons. These neurons send processes that display mirror symmetric, widely distributed arbors of endings within brain regions including the ventrolateral protocerebra, the SOG and the peri-esophageal complex. The results suggest that a small subset of OA neurons have the potential to provide male selective modulation of behavior at a single neuron level.
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Affiliation(s)
- Sarah J Certel
- Department of Neurobiology, Harvard Medical School, Boston, Massachusetts, United States of America.
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Corrections and clarifications. Science 2010; 264:644. [PMID: 17737931 DOI: 10.1126/science.264.5159.644-c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The Random Sample item "The brain behind that happy face" (15 Oct., p. 336) refers to a paper by Paul Ekman and Richard Davidson. That paper appeared in the September 1993 issue of Psychological Science, a journal of the American Psychological Society.
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Logothetis NK. Neurovascular Uncoupling: Much Ado about Nothing. FRONTIERS IN NEUROENERGETICS 2010; 2. [PMID: 20725519 PMCID: PMC2912029 DOI: 10.3389/fnene.2010.00002] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/26/2010] [Accepted: 04/04/2010] [Indexed: 11/13/2022]
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Descarries L, Riad M, Parent M. Ultrastructure of the Serotonin Innervation in the Mammalian Central Nervous System. HANDBOOK OF BEHAVIORAL NEUROSCIENCE 2010. [DOI: 10.1016/s1569-7339(10)70072-2] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
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