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Kim Y, Kim S, Ho WK, Lee SH. Burst firing is required for induction of Hebbian LTP at lateral perforant path to hippocampal granule cell synapses. Mol Brain 2023; 16:45. [PMID: 37217996 DOI: 10.1186/s13041-023-01034-w] [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: 02/27/2023] [Accepted: 05/04/2023] [Indexed: 05/24/2023] Open
Abstract
High frequency burst firing is critical in summation of back-propagating action potentials (APs) in dendrites, which may greatly depolarize dendritic membrane potential. The physiological significance of burst firings of hippocampal dentate GCs in synaptic plasticity remains unknown. We found that GCs with low input resistance could be categorized into regular-spiking (RS) and burst-spiking (BS) cells based on their initial firing frequency (Finit) upon somatic rheobase current injection, and investigated how two types of GCs differ in long-term potentiation (LTP) induced by high-frequency lateral perforant pathway (LPP) inputs. Induction of Hebbian LTP at LPP synapses required at least three postsynaptic APs at Finit higher than 100 Hz, which was met in BS but not in RS cells. The synaptically evoked burst firing was critically dependent on persistent Na+ current, which was larger in BS than RS cells. The Ca2+ source for Hebbian LTP at LPP synapses was primarily provided by L-type calcium channels. In contrast, Hebbian LTP at medial PP synapses was mediated by T-type calcium channels, and could be induced regardless of cell types or Finit of postsynaptic APs. These results suggest that intrinsic firing properties affect synaptically driven firing patterns, and that bursting behavior differentially affects Hebbian LTP mechanisms depending on the synaptic input pathway.
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Affiliation(s)
- Yoonsub Kim
- Cell Physiology Lab. Department of Physiology, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Sooyun Kim
- Clinical Research Institute, Seoul National University Hospital, Seoul, Republic of Korea
| | - Won-Kyung Ho
- Cell Physiology Lab. Department of Physiology, Seoul National University College of Medicine, Seoul, Republic of Korea.
| | - Suk-Ho Lee
- Cell Physiology Lab. Department of Physiology, Seoul National University College of Medicine, Seoul, Republic of Korea.
- Department of Brain and Cognitive Science, Seoul National University College of Natural Science, 103 Daehak-Ro, Jongno-Gu, 03080, Seoul, Republic of Korea.
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OKUBO YOHEI. Investigation of Brain Functions with Fluorescence Imaging Techniques. JUNTENDO IJI ZASSHI = JUNTENDO MEDICAL JOURNAL 2022; 68:157-162. [PMID: 38912284 PMCID: PMC11189797 DOI: 10.14789/jmj.jmj21-0051-ot] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/09/2021] [Accepted: 01/05/2022] [Indexed: 06/25/2024]
Abstract
An intricate interplay of complex spatio-temporal events underlies brain functions. Therefore, clarifying these dynamic processes is indispensable for revealing the mechanisms of brain functions. Fluorescence imaging is a powerful technique for visualizing cellular and molecular dynamics in the brain. Recent developments in fluorescent indicators and specialized optics have advanced research in the field of neuroscience. In this review, I will exemplify the power and beauty of fluorescence imaging by discussing my work focusing on the molecular dynamics of metabotropic glutamate receptor (mGluR) signaling at the synapse. By developing novel fluorescent indicators for glutamate, inositol 1,4,5-trisphosphate and Ca2+ within the endoplasmic reticulum, I succeeded in imaging the spatio-temporal dynamics of synaptic mGluR signaling, which led to the identification of novel mechanisms of mGluR-mediated glutamatergic neurotransmission. These discoveries highlight the importance of the development and application of novel fluorescence imaging techniques for the investigation of brain functions.
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Affiliation(s)
- YOHEI OKUBO
- Corresponding author: Yohei Okubo (ORCiD: 0000-0001-7611-3237), Department of Cellular and Molecular Pharmacology, Juntendo University Graduate School of Medicine, Hongo 2-1-1, Bunkyo-ku, Tokyo 113-8421, Japan, TEL: +81-3-5802-1035 E-mail:
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3
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Jonas R, Schmelz M. Sensitization of supra-threshold pain responses-Translational aspects and mechanisms. FRONTIERS IN NETWORK PHYSIOLOGY 2022; 2:1078890. [PMID: 36926107 PMCID: PMC10013001 DOI: 10.3389/fnetp.2022.1078890] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2022] [Accepted: 12/05/2022] [Indexed: 12/23/2022]
Abstract
A substantial translational gap in pain research has been reflected by a mismatch of relevant primary pain assessment endpoints in preclinical vs. clinical trials. Since activity-dependent mechanisms may be neglected during reflexive tests, this may add as a confounding factor during preclinical pain assessment. In this perspective, we consider the evidence for a need for supra-threshold pain assessment in the pain research literature. In addition to that, we focus on previous results that may demonstrate an example mechanism, where the detection of neuron-glial interactions on pain seems to be substantially depending on the assessment of pain intensity beyond threshold levels.
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Affiliation(s)
- Robin Jonas
- Department of Translational Pharmacology, Medical School EWL, Bielefeld University, Bielefeld, Germany.,UMCG Pain Center, Department of Anaesthesiology, University Medical Center Groningen, University of Groningen, Groningen, Netherlands
| | - Martin Schmelz
- Department of Experimental Pain Research, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
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Chen X, Beltran DJ, Tsygankova VD, Woolwine BJ, Patel T, Baer W, Felger JC, Miller AH, Haroon E. Kynurenines increase MRS metabolites in basal ganglia and decrease resting-state connectivity in frontostriatal reward circuitry in depression. Transl Psychiatry 2021; 11:456. [PMID: 34482366 PMCID: PMC8418602 DOI: 10.1038/s41398-021-01587-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/16/2021] [Revised: 08/04/2021] [Accepted: 08/19/2021] [Indexed: 12/25/2022] Open
Abstract
Inflammation is associated with the development of anhedonia in major depression (MD), but the pathway by which inflammatory molecules gain access to the brain and lead to anhedonia is not clear. Molecules of the kynurenine pathway (KP), which is activated by inflammation, readily influx into the brain and generate end products that alter brain chemistry, disrupt circuit functioning, and result in the expression of inflammatory behaviors such as anhedonia. We examined the impact of plasma and CSF KP metabolites on brain chemistry and neural function using multimodal neuroimaging in 49 depressed subjects. We measured markers of glial dysfunction and distress including glutamate (Glu) and myo-inositol in the left basal ganglia using magnetic resonance spectroscopy (MRS); metrics of local activity coherence (regional homogeneity, ReHo) and functional connectivity from resting-state functional MRI measures; and anhedonia from the Inventory for Depressive Symptoms-Self Report Version (IDS-SR). Plasma kynurenine/tryptophan (KYN/TRP) ratio and cerebrospinal fluid (CSF) 3-hydroxykynurenine (3HK) were associated with increases in left basal ganglia myo-inositol. Plasma kynurenic acid (KYNA) and KYNA/QA were associated with decreases and quinolinic acid (QA) with increases in left basal ganglia Glu. Plasma and CSF KP were associated with decreases in ReHo in the basal ganglia and dorsomedial prefrontal regions (DMPFC) and impaired functional connectivity between these two regions. DMPFC-basal ganglia mediated the effect of plasma and CSF KP on anhedonia. These findings highlight the pathological impact of KP system dysregulation in mediating inflammatory behaviors such as anhedonia.
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Affiliation(s)
- Xiangchuan Chen
- Emory Behavioral Immunology Program, Atlanta, GA, USA
- Department of Psychiatry and Behavioral Sciences, Atlanta, GA, USA
| | - Diana J Beltran
- Emory Behavioral Immunology Program, Atlanta, GA, USA
- Department of Psychiatry and Behavioral Sciences, Atlanta, GA, USA
| | - Valeriya D Tsygankova
- Emory Behavioral Immunology Program, Atlanta, GA, USA
- Department of Psychiatry and Behavioral Sciences, Atlanta, GA, USA
| | - Bobbi J Woolwine
- Emory Behavioral Immunology Program, Atlanta, GA, USA
- Department of Psychiatry and Behavioral Sciences, Atlanta, GA, USA
| | - Trusharth Patel
- Department of Anesthesiology, Emory University School of Medicine, Atlanta, GA, USA
| | - Wendy Baer
- Emory Behavioral Immunology Program, Atlanta, GA, USA
- Department of Psychiatry and Behavioral Sciences, Atlanta, GA, USA
| | - Jennifer C Felger
- Emory Behavioral Immunology Program, Atlanta, GA, USA
- Department of Psychiatry and Behavioral Sciences, Atlanta, GA, USA
| | - Andrew H Miller
- Emory Behavioral Immunology Program, Atlanta, GA, USA
- Department of Psychiatry and Behavioral Sciences, Atlanta, GA, USA
| | - Ebrahim Haroon
- Emory Behavioral Immunology Program, Atlanta, GA, USA.
- Department of Psychiatry and Behavioral Sciences, Atlanta, GA, USA.
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Mather M. Noradrenaline in the aging brain: Promoting cognitive reserve or accelerating Alzheimer's disease? Semin Cell Dev Biol 2021; 116:108-124. [PMID: 34099360 PMCID: PMC8292227 DOI: 10.1016/j.semcdb.2021.05.013] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Revised: 05/04/2021] [Accepted: 05/05/2021] [Indexed: 12/19/2022]
Abstract
Many believe that engaging in novel and mentally challenging activities promotes brain health and prevents Alzheimer's disease in later life. However, mental stimulation may also have risks as well as benefits. As neurons release neurotransmitters, they often also release amyloid peptides and tau proteins into the extracellular space. These by-products of neural activity can aggregate into the tau tangle and amyloid plaque signatures of Alzheimer's disease. Over time, more active brain regions accumulate more pathology. Thus, increasing brain activity can have a cost. But the neuromodulator noradrenaline, released during novel and mentally stimulating events, may have some protective effects-as well as some negative effects. Via its inhibitory and excitatory effects on neurons and microglia, noradrenaline sometimes prevents and sometimes accelerates the production and accumulation of amyloid-β and tau in various brain regions. Both α2A- and β-adrenergic receptors influence amyloid-β production and tau hyperphosphorylation. Adrenergic activity also influences clearance of amyloid-β and tau. Furthermore, some findings suggest that Alzheimer's disease increases noradrenergic activity, at least in its early phases. Because older brains clear the by-products of synaptic activity less effectively, increased synaptic activity in the older brain risks accelerating the accumulation of Alzheimer's pathology more than it does in the younger brain.
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Affiliation(s)
- Mara Mather
- Leonard Davis School of Gerontology, Department of Psychology, & Department of Biomedical Engineering, University of Southern California, 3715 McClintock Ave, Los Angeles, CA 90089, United States.
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Structural changes in brains of patients with disorders of consciousness treated with deep brain stimulation. Sci Rep 2021; 11:4401. [PMID: 33623134 PMCID: PMC7902623 DOI: 10.1038/s41598-021-83873-y] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Accepted: 02/09/2021] [Indexed: 11/09/2022] Open
Abstract
Disorders of consciousness (DOC) are one of the major consequences after anoxic or traumatic brain injury. So far, several studies have described the regaining of consciousness in DOC patients using deep brain stimulation (DBS). However, these studies often lack detailed data on the structural and functional cerebral changes after such treatment. The aim of this study was to conduct a volumetric analysis of specific cortical and subcortical structures to determine the impact of DBS after functional recovery of DOC patients. Five DOC patients underwent unilateral DBS electrode implantation into the centromedian parafascicular complex of the thalamic intralaminar nuclei. Consciousness recovery was confirmed using the Rappaport Disability Rating and the Coma/Near Coma scale. Brain MRI volumetric measurements were done prior to the procedure, then approximately a year after, and finally 7 years after the implementation of the electrode. The volumetric analysis included changes in regional cortical volumes and thickness, as well as in subcortical structures. Limbic cortices (parahippocampal and cingulate gyrus) and paralimbic cortices (insula) regions showed a significant volume increase and presented a trend of regional cortical thickness increase 1 and 7 years after DBS. The volumes of related subcortical structures, namely the caudate, the hippocampus as well as the amygdala, were significantly increased 1 and 7 years after DBS, while the putamen and nucleus accumbens presented with volume increase. Volume increase after DBS could be a result of direct DBS effects, or a result of functional recovery. Our findings are in accordance with the results of very few human studies connecting DBS and brain volume increase. Which mechanisms are behind the observed brain changes and whether structural changes are caused by consciousness recovery or DBS in patients with DOC is still a matter of debate.
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7
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Ding X, Peng D. Transient Global Amnesia: An Electrophysiological Disorder Based on Cortical Spreading Depression-Transient Global Amnesia Model. Front Hum Neurosci 2020; 14:602496. [PMID: 33363460 PMCID: PMC7753037 DOI: 10.3389/fnhum.2020.602496] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Accepted: 11/17/2020] [Indexed: 01/09/2023] Open
Abstract
Transient global amnesia (TGA) is a benign memory disorder with etiologies that have been debated for a long time. The prevalence of stressful events before a TGA attack makes it hard to overlook these precipitating factors, given that stress has the potential to organically effect the brain. Cortical spreading depression (CSD) was proposed as a possible cause decades ago. Being a regional phenomenon, CSD seems to affect every aspect of the micro-mechanism in maintaining the homeostasis of the central nervous system (CNS). Corresponding evidence regarding hemodynamic and morphological changes from TGA and CSD have been accumulated separately, but the resemblance between the two has not been systematically explored so far, which is surprising especially considering that CSD had been confirmed to cause secondary damage in the human brain. Thus, by deeply delving into the anatomic and electrophysiological properties of the CNS, the CSD-TGA model may render insights into the basic pathophysiology behind the façade of the enigmatic clinical presentation.
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Affiliation(s)
- Xuejiao Ding
- Department of Neurology, China-Japan Friendship Hospital, Beijing, China
- Graduate School of Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, China
| | - Dantao Peng
- Department of Neurology, China-Japan Friendship Hospital, Beijing, China
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8
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Siemsen BM, Reichel CM, Leong KC, Garcia-Keller C, Gipson CD, Spencer S, McFaddin JA, Hooker KN, Kalivas PW, Scofield MD. Effects of Methamphetamine Self-Administration and Extinction on Astrocyte Structure and Function in the Nucleus Accumbens Core. Neuroscience 2019; 406:528-541. [PMID: 30926546 PMCID: PMC6545487 DOI: 10.1016/j.neuroscience.2019.03.040] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2018] [Revised: 03/15/2019] [Accepted: 03/19/2019] [Indexed: 01/01/2023]
Abstract
Astrocytes provide support for neurons, regulate metabolic processes, and influence neuronal communication in a variety of ways, including through the homeostatic regulation of glutamate. Following 2-h cocaine or methamphetamine self-administration (SA) and extinction, rodents display decreased levels of basal glutamate in the nucleus accumbens core (NAcore), which transitions to elevated glutamate levels during drug seeking. We hypothesized that, like cocaine, this glutamate 'overflow' during methamphetamine seeking arises via decreased expression of the astroglial glutamate transporter GLT-1, and withdrawal of perisynaptic astroglial processes (PAPs) from synapses. As expected, methamphetamine self-administration and extinction decreased the level of contact made by PAPs in the NAcore, yet did not impact glutamate uptake, GLT-1 expression, or the general structural characteristics of astrocytes. Interestingly, systemic administration of N-acetylcysteine (NAC), a drug that both upregulates GLT-1 and promotes glial-glutamate release, reduced cued methamphetamine seeking. In order to test the impact of astrocyte activation and the induction of glial glutamate release within the NAcore, we employed astrocyte-specific expression of designer receptors exclusively activated by designer drugs (DREADDs). We show here that acute activation of Gq-coupled DREADDs in this region inhibited cued methamphetamine seeking. Taken together, these data indicate that cued methamphetamine seeking following two-hour SA is not mediated by deficient glutamate clearance in the NAcore, yet can be inhibited by engaging NAcore astrocytes.
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Affiliation(s)
- B M Siemsen
- Department of Anesthesiology and Perioperative Medicine, Medical University of South Carolina, Charleston, SC, USA; Department of Neuroscience, Medical University of South Carolina, Charleston, SC, USA
| | - C M Reichel
- Department of Neuroscience, Medical University of South Carolina, Charleston, SC, USA
| | - K C Leong
- Department of Psychology, Trinity University, San Antonio, TX, USA
| | - C Garcia-Keller
- Department of Neuroscience, Medical University of South Carolina, Charleston, SC, USA
| | - C D Gipson
- Department of Psychology, Arizona State University, Tempe, AZ, USA
| | - S Spencer
- Department of Pharmacology, University of Minnesota, Minneapolis, MN, USA
| | - J A McFaddin
- Department of Anesthesiology and Perioperative Medicine, Medical University of South Carolina, Charleston, SC, USA
| | - K N Hooker
- Department of Anesthesiology and Perioperative Medicine, Medical University of South Carolina, Charleston, SC, USA
| | - P W Kalivas
- Department of Neuroscience, Medical University of South Carolina, Charleston, SC, USA
| | - M D Scofield
- Department of Anesthesiology and Perioperative Medicine, Medical University of South Carolina, Charleston, SC, USA; Department of Neuroscience, Medical University of South Carolina, Charleston, SC, USA.
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Increased inflammation and brain glutamate define a subtype of depression with decreased regional homogeneity, impaired network integrity, and anhedonia. Transl Psychiatry 2018; 8:189. [PMID: 30202011 PMCID: PMC6131242 DOI: 10.1038/s41398-018-0241-4] [Citation(s) in RCA: 68] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Revised: 07/31/2018] [Accepted: 08/03/2018] [Indexed: 12/11/2022] Open
Abstract
Combined increases in peripheral inflammation and brain glutamate may identify a subtype of depression with distinct neuroimaging signatures. Two contrasting subgroups of depressed subjects-with and without combined elevations in plasma C-reactive protein (CRP) and basal ganglia glutamate (high and low CRP-Glu, respectively) were identified by hierarchical clustering using plasma CRP (indexing peripheral inflammation) and magnetic resonance spectroscopy (MRS)-based measurement of left basal ganglia glutamate. High CRP-Glu group status was associated with greater severity of anhedonia and cognitive and motor slowing. Local- and network-level measures of functional integrity were determined using brain oxygen level-dependent (BOLD)-oscillatory activity and graph theory. Greater decreases in concordance of oscillatory activity between neighboring voxels (Regional Homogeneity 'ReHo', p < 0.01) within the MRS volume-of-interest was associated with the High CRP-Glu subgroup. Using brain-wide, CRP-Glu ReHo contrast maps, a covariance network of 41 regions-of-interest (ROIs) with similar ReHo decreases was identified in the High CRP-Glu group and was located to brain structures previously implicated in depression. The 41-ROI network was further decomposed into four subnetworks. ReHo decreases within Subnetwork4-comprised of reward processing regions -was associated with anhedonia. Subnetwork4 ReHo also predicted decreased network integrity, which mediated the link between local ReHo and anhedonia in the Low but not High CRP-Glu group. These findings suggest that decreased ReHo and related disruptions in network integrity may reflect toxic effects of inflammation-induced increases in extrasynaptic glutamate signaling. Moreover, local BOLD oscillatory activity as reflected in ReHo might be a useful measure of target-engagement in the brain for treatment of inflammation-induced behaviors.
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Wu J, Abdelfattah AS, Zhou H, Ruangkittisakul A, Qian Y, Ballanyi K, Campbell RE. Genetically Encoded Glutamate Indicators with Altered Color and Topology. ACS Chem Biol 2018; 13:1832-1837. [PMID: 29308878 DOI: 10.1021/acschembio.7b01085] [Citation(s) in RCA: 61] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Glutamate is one of the 20 common amino acids and of utmost importance for chemically mediated synaptic transmission in nervous systems. To expand the color palette of genetically encoded indicators for glutamate, we used protein engineering to develop a red intensity-based glutamate-sensing fluorescent reporter (R-iGluSnFR1). Manipulating the topology of R-iGluSnFR1, and a previously reported green fluorescent indicator, led to the development of noncircularly permutated (ncp) variants. R- and Rncp-iGluSnFR1 display glutamate affinities of 11 μM and 0.9 μM, respectively. We demonstrate that these glutamate indicators are functional when targeted to the surface of HEK-293 cells. Furthermore, we show that Gncp-iGluSnFR enabled reliable visualization of extrasynaptic glutamate in organotypic hippocampal slice cultures, while R-iGluSnFR can reliably resolve action potential-evoked glutamate transients by electrical field stimuli in cultures of dissociated hippocampal neurons.
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Affiliation(s)
- Jiahui Wu
- Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada T6G 2G2
| | - Ahmed S. Abdelfattah
- Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada T6G 2G2
| | - Hang Zhou
- Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada T6G 2G2
| | | | - Yong Qian
- Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada T6G 2G2
| | - Klaus Ballanyi
- Department of Physiology, University of Alberta, Edmonton, Alberta, Canada T6G 2H7
| | - Robert E. Campbell
- Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada T6G 2G2
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11
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Wang A, Feng J, Li Y, Zou P. Beyond Fluorescent Proteins: Hybrid and Bioluminescent Indicators for Imaging Neural Activities. ACS Chem Neurosci 2018; 9:639-650. [PMID: 29482322 DOI: 10.1021/acschemneuro.7b00455] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Optical biosensors have been invaluable tools in neuroscience research, as they provide the ability to directly visualize neural activity in real time, with high specificity, and with exceptional spatial and temporal resolution. Notably, a majority of these sensors are based on fluorescent protein scaffolds, which offer the ability to target specific cell types or even subcellular compartments. However, fluorescent proteins are intrinsically bulky tags, often insensitive to the environment, and always require excitation light illumination. To address these limitations, there has been a proliferation of alternative sensor scaffolds developed in recent years, including hybrid sensors that combine the advantages of synthetic fluorophores and genetically encoded protein tags, as well as bioluminescent probes. While still in their early stage of development as compared with fluorescent protein-based sensors, these novel probes have offered complementary solutions to interrogate various aspects of neuronal communication, including transmitter release, changes in membrane potential, and the production of second messengers. In this Review, we discuss these important new developments with a particular focus on design strategies.
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Affiliation(s)
- Anqi Wang
- College of Chemistry and Molecular Engineering, Synthetic and Functional Biomolecules Center, Beijing National Laboratory for Molecular Sciences, Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, Peking University, Beijing 100871, China
- Peking-Tsinghua Center for Life Sciences, PKU-IDG/McGovern Institute for Brain Research, Peking University, Beijing 100871, China
| | - Jiesi Feng
- State Key Laboratory of Membrane Biology, School of Life Sciences, Peking University, Beijing 100871, China
- Peking-Tsinghua Center for Life Sciences, PKU-IDG/McGovern Institute for Brain Research, Peking University, Beijing 100871, China
| | - Yulong Li
- State Key Laboratory of Membrane Biology, School of Life Sciences, Peking University, Beijing 100871, China
- Peking-Tsinghua Center for Life Sciences, PKU-IDG/McGovern Institute for Brain Research, Peking University, Beijing 100871, China
| | - Peng Zou
- College of Chemistry and Molecular Engineering, Synthetic and Functional Biomolecules Center, Beijing National Laboratory for Molecular Sciences, Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, Peking University, Beijing 100871, China
- Peking-Tsinghua Center for Life Sciences, PKU-IDG/McGovern Institute for Brain Research, Peking University, Beijing 100871, China
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12
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Ferguson BS, Rogatzki MJ, Goodwin ML, Kane DA, Rightmire Z, Gladden LB. Lactate metabolism: historical context, prior misinterpretations, and current understanding. Eur J Appl Physiol 2018; 118:691-728. [PMID: 29322250 DOI: 10.1007/s00421-017-3795-6] [Citation(s) in RCA: 209] [Impact Index Per Article: 34.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2017] [Accepted: 12/22/2017] [Indexed: 02/07/2023]
Abstract
Lactate (La-) has long been at the center of controversy in research, clinical, and athletic settings. Since its discovery in 1780, La- has often been erroneously viewed as simply a hypoxic waste product with multiple deleterious effects. Not until the 1980s, with the introduction of the cell-to-cell lactate shuttle did a paradigm shift in our understanding of the role of La- in metabolism begin. The evidence for La- as a major player in the coordination of whole-body metabolism has since grown rapidly. La- is a readily combusted fuel that is shuttled throughout the body, and it is a potent signal for angiogenesis irrespective of oxygen tension. Despite this, many fundamental discoveries about La- are still working their way into mainstream research, clinical care, and practice. The purpose of this review is to synthesize current understanding of La- metabolism via an appraisal of its robust experimental history, particularly in exercise physiology. That La- production increases during dysoxia is beyond debate, but this condition is the exception rather than the rule. Fluctuations in blood [La-] in health and disease are not typically due to low oxygen tension, a principle first demonstrated with exercise and now understood to varying degrees across disciplines. From its role in coordinating whole-body metabolism as a fuel to its role as a signaling molecule in tumors, the study of La- metabolism continues to expand and holds potential for multiple clinical applications. This review highlights La-'s central role in metabolism and amplifies our understanding of past research.
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Affiliation(s)
- Brian S Ferguson
- College of Applied Health Sciences, University of Illinois at Chicago, Chicago, IL, USA
| | - Matthew J Rogatzki
- Department of Health and Exercise Science, Appalachian State University, Boone, NC, USA
| | - Matthew L Goodwin
- Department of Orthopaedics, University of Utah, Salt Lake City, UT, USA.,Huntsman Cancer Institute, Salt Lake City, UT, USA
| | - Daniel A Kane
- Department of Human Kinetics, St. Francis Xavier University, Antigonish, Canada
| | - Zachary Rightmire
- School of Kinesiology, Auburn University, 301 Wire Road, Auburn, AL, 36849, USA
| | - L Bruce Gladden
- School of Kinesiology, Auburn University, 301 Wire Road, Auburn, AL, 36849, USA.
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13
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Thalamic interactions of cerebellum and basal ganglia. Brain Struct Funct 2017; 223:569-587. [PMID: 29224175 DOI: 10.1007/s00429-017-1584-y] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2017] [Accepted: 11/29/2017] [Indexed: 01/04/2023]
Abstract
Cerebellum and basal ganglia are reciprocally interconnected with the neocortex via oligosynaptic loops. The signal pathways of these loops predominantly converge in motor areas of the frontal cortex and are mainly segregated on subcortical level. Recent evidence, however, indicates subcortical interaction of these systems. We have reviewed literature that addresses the question whether, and to what extent, projections of main output nuclei of basal ganglia (reticular part of the substantia nigra, internal segment of the globus pallidus) and cerebellum (deep cerebellar nuclei) interact with each other in the thalamus. To this end, we compiled data from electrophysiological and anatomical studies in rats, cats, dogs, and non-human primates. Evidence suggests the existence of convergence of thalamic projections originating in basal ganglia and cerebellum, albeit sparse and restricted to certain regions. Four regions come into question to contain converging inputs: (1) lateral parts of medial dorsal nucleus (MD); (2) parts of anterior intralaminar nuclei and centromedian and parafascicular nuclei (CM/Pf); (3) ventromedial nucleus (VM); and (4) border regions of cerebellar and ganglia terminal territories in ventral anterior and ventral lateral nuclei (VA-VL). The amount of convergences was found to exhibit marked interspecies differences. To explain the rather sparse convergences of projection territories and to estimate their physiological relevance, we present two conceivable principles of anatomical organization: (1) a "core-and-shell" organization, in which a central core is exclusive to one projection system, while peripheral shell regions intermingle and occasionally converge with other projection systems and (2) convergences that are characteristic to distinct functional networks. The physiological relevance of these convergences is not yet clear. An oculomotor network proposed in this work is an interesting candidate to examine potential ganglia and cerebellar subcortical interactions.
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14
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Gupta R, Reneaux M. Role of Heterogeneous Macromolecular Crowding and Geometrical Irregularity at Central Excitatory Synapses in Shaping Synaptic Transmission. PLoS One 2016; 11:e0167505. [PMID: 27907112 PMCID: PMC5131996 DOI: 10.1371/journal.pone.0167505] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2016] [Accepted: 11/15/2016] [Indexed: 01/24/2023] Open
Abstract
Besides the geometrical tortousity due to the extrasynaptic structures, macromolecular crowding and geometrical irregularities constituting the cleft composition at central excitatory synapses has a major and direct role in retarding the glutamate diffusion within the cleft space. However, the cleft composition may not only coarsely reduce the overall diffusivity of the glutamate but may also lead to substantial spatial variation in the diffusivity across the cleft space. Decrease in the overall diffusivity of the glutamate may have straightforward consequences to the glutamate transients in the cleft. However, how spatial variation in the diffusivity may further affect glutamate transients is an intriguing aspect. Therefore, to understand the role of cleft heterogeneity, the present study adopts a novel approach of glutamate diffusion which considers a gamma statistical distribution of the diffusion coefficient of glutamate (Dglut) across the cleft space, such that its moments discernibly capture the dual impacts of the cleft composition, and further applies the framework of superstatistics. The findings reveal a power law behavior in the glutamate transients, akin to the long-range anomalous subdiffusion, which leads to slower decay profile of cleft glutamate at higher intensity of cleft heterogeneity. Moreover, increase in the cleft heterogeneity is seen to eventually cause slower-rising excitatory postsynaptic currents with higher amplitudes, lesser noise, and prolonged duration of charge transfer across the postsynaptic membrane. Further, with regard to the conventional standard diffusion approach, the study suggests that the effective Dglut essentially derives from the median of the Dglut distribution and does not necessarily need to be the mean Dglut. Together, the findings indicate a strong implication of cleft heterogeneity to the metabolically cost-effective tuning of synaptic response during the phenomenon of plasticity at individual synapses and also provide an additional factor of variability in transmission across identical synapses.
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Affiliation(s)
- Rahul Gupta
- School of Computational and Integrative Sciences, Jawaharlal Nehru University, New Delhi, India 110067
| | - Melissa Reneaux
- School of Computational and Integrative Sciences, Jawaharlal Nehru University, New Delhi, India 110067
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15
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Schwarcz R. Kynurenines and Glutamate: Multiple Links and Therapeutic Implications. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2016; 76:13-37. [PMID: 27288072 PMCID: PMC5803753 DOI: 10.1016/bs.apha.2016.01.005] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Glutamate is firmly established as the major excitatory neurotransmitter in the mammalian brain and is actively involved in most aspects of neurophysiology. Moreover, glutamatergic impairments are associated with a wide variety of dysfunctional states, and both hypo- and hyperfunction of glutamate have been plausibly linked to the pathophysiology of neurological and psychiatric diseases. Metabolites of the kynurenine pathway (KP), the major catabolic route of the essential amino acid tryptophan, influence glutamatergic activity in several distinct ways. This includes direct effects of these "kynurenines" on ionotropic and metabotropic glutamate receptors or vesicular glutamate transport, and indirect effects, which are initiated by actions at various other recognition sites. In addition, some KP metabolites affect glutamatergic functions by generating or scavenging highly reactive free radicals. This review summarizes these phenomena and discusses implications for brain physiology and pathology.
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Affiliation(s)
- R Schwarcz
- Maryland Psychiatric Research Center, University of Maryland School of Medicine, Baltimore, MD, United States.
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16
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Pál B. Astrocytic Actions on Extrasynaptic Neuronal Currents. Front Cell Neurosci 2015; 9:474. [PMID: 26696832 PMCID: PMC4673305 DOI: 10.3389/fncel.2015.00474] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2015] [Accepted: 11/20/2015] [Indexed: 01/23/2023] Open
Abstract
In the last few decades, knowledge about astrocytic functions has significantly increased. It was demonstrated that astrocytes are not passive elements of the central nervous system (CNS), but active partners of neurons. There is a growing body of knowledge about the calcium excitability of astrocytes, the actions of different gliotransmitters and their release mechanisms, as well as the participation of astrocytes in the regulation of synaptic functions and their contribution to synaptic plasticity. However, astrocytic functions are even more complex than being a partner of the “tripartite synapse,” as they can influence extrasynaptic neuronal currents either by releasing substances or regulating ambient neurotransmitter levels. Several types of currents or changes of membrane potential with different kinetics and via different mechanisms can be elicited by astrocytic activity. Astrocyte-dependent phasic or tonic, inward or outward currents were described in several brain areas. Such currents, together with the synaptic actions of astrocytes, can contribute to neuromodulatory mechanisms, neurosensory and -secretory processes, cortical oscillatory activity, memory, and learning or overall neuronal excitability. This mini-review is an attempt to give a brief summary of astrocyte-dependent extrasynaptic neuronal currents and their possible functional significance.
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Affiliation(s)
- Balázs Pál
- Department of Physiology, Faculty of Medicine, University of Debrecen Debrecen, Hungary
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17
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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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18
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Tanaka K, Shoji A, Sugawara M. An enzyme-entrapped agarose gel for visualization of ischemia-induced L-glutamate fluxes in hippocampal slices in a flow system. ANAL SCI 2015; 31:321-5. [PMID: 25864676 DOI: 10.2116/analsci.31.321] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
An agarose gel slip containing L-glutamate oxidase (GluOx), horseradish peroxidase (HRP) and a dye DA-64 is proposed as a tool for visualizing ischemia-induced L-glutamate release in hippocampal slices in a flow system. The agarose slip with a detection limit of 6.0 ± 0.8 μmol L(-1) for L-glutamate enabled us to visualize L-glutamate fluxes in a flow system. The leak of a dye from the agarose gel was negligible and a diffusion blur due to spreading of Bindshedler's Green (BG) within the gel was suppressed. Monitoring the time-dependent change of ischemia-induced L-glutamate fluxes at neuronal regions CA1, DG and CA3 of hippocampal slices is demonstrated.
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Affiliation(s)
- Kazuhisa Tanaka
- Department of Chemistry, College of Humanities and Sciences, Nihon University
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19
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Ueno T, Kume K. [Sleep research with fruit fly]. Nihon Yakurigaku Zasshi 2015; 145:134-9. [PMID: 25765495 DOI: 10.1254/fpj.145.134] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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20
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Liang R, Broussard GJ, Tian L. Imaging chemical neurotransmission with genetically encoded fluorescent sensors. ACS Chem Neurosci 2015; 6:84-93. [PMID: 25565280 DOI: 10.1021/cn500280k] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
A major challenge in neuroscience is to decipher the logic of neural circuitry and to link it to learning, memory, and behavior. Synaptic transmission is a critical event underlying information processing within neural circuitry. In the extracellular space, the concentrations and distributions of excitatory, inhibitory, and modulatory neurotransmitters impact signal integration, which in turn shapes and refines the function of neural networks. Thus, the determination of the spatiotemporal relationships between these chemical signals with synaptic resolution in the intact brain is essential to decipher the codes for transferring information across circuitry and systems. Here, we review approaches and probes that have been employed to determine the spatial and temporal extent of neurotransmitter dynamics in the brain. We specifically focus on the design, screening, characterization, and application of genetically encoded indicators directly probing glutamate, the most abundant excitatory neurotransmitter. These indicators provide synaptic resolution of glutamate dynamics with cell-type specificity. We also discuss strategies for developing a suite of genetically encoded probes for a variety of neurotransmitters and neuromodulators.
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Affiliation(s)
- Ruqiang Liang
- Department
of Biochemistry and Molecular Medicine and ‡Center
for Neuroscience, University of California Davis, Davis, California 95817, United States
| | - Gerard Joseph Broussard
- Department
of Biochemistry and Molecular Medicine and ‡Center
for Neuroscience, University of California Davis, Davis, California 95817, United States
| | - Lin Tian
- Department
of Biochemistry and Molecular Medicine and ‡Center
for Neuroscience, University of California Davis, Davis, California 95817, United States
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21
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Ikegami Y, Hozumi S, Shoji A, Hirano-Iwata A, Bliss T, Sugawara M. Real-time monitoring of extracellular l-glutamate levels released by high-frequency stimulation at region CA1 of hippocampal slices with a glass capillary-based l-glutamate sensor. SENSING AND BIO-SENSING RESEARCH 2014. [DOI: 10.1016/j.sbsr.2014.10.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
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22
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Huang Y, Lu M, Guo W, Zeng R, Wang B, Wang H. Thrombospondin 1 promotes synaptic formation in bone marrow-derived neuron-like cells. Neural Regen Res 2014; 8:869-81. [PMID: 25206378 PMCID: PMC4145928 DOI: 10.3969/j.issn.1673-5374.2013.10.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2012] [Accepted: 03/07/2013] [Indexed: 01/13/2023] Open
Abstract
In this study, a combination of growth factors was used to induce bone marrow mesenchymal stem cells differentiation into neuron-like cells, in a broader attempt to observe the role of thrombospondin 1 in synapse formation. Results showed that there was no significant difference in the differentiation rate of neuron-like cells between bone marrow mesenchymal stem cells with thrombospondin induction and those without. However, the cell shape was more complex and the neurites were dendritic, with unipolar, bipolar or multipolar morphologies, after induction with thrombospondin 1. The induced cells were similar in morphology to normal neurites. Immunohistochemical staining showed that the number of positive cells for postsynaptic density protein 95 and synaptophysin 1 protein was significantly increased after induction with thrombospondin 1. These findings indicate that thrombospondin 1 promotes synapse formation in neuron-like cells that are differentiated from bone marrow mesenchymal stem cells.
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Affiliation(s)
- Yun Huang
- Department of Orthopedics, Affiliated Hospital of Guangdong Medical College, Zhanjiang 524001, Guangdong Province, China
| | - Mingnan Lu
- Department of Orthopedics, Affiliated Hospital of Guangdong Medical College, Zhanjiang 524001, Guangdong Province, China
| | - Weitao Guo
- Department of Orthopedics, Affiliated Hospital of Guangdong Medical College, Zhanjiang 524001, Guangdong Province, China
| | - Rong Zeng
- Department of Orthopedics, Affiliated Hospital of Guangdong Medical College, Zhanjiang 524001, Guangdong Province, China
| | - Bin Wang
- Department of Orthopedics, Affiliated Hospital of Guangdong Medical College, Zhanjiang 524001, Guangdong Province, China
| | - Huaibo Wang
- Department of Orthopedics, Affiliated Hospital of Guangdong Medical College, Zhanjiang 524001, Guangdong Province, China
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23
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Okubo Y. [Visualization of metabotropic glutamate-receptor signaling]. Nihon Yakurigaku Zasshi 2014; 144:76-80. [PMID: 25109520 DOI: 10.1254/fpj.144.76] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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24
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Pietrobon D, Moskowitz MA. Chaos and commotion in the wake of cortical spreading depression and spreading depolarizations. Nat Rev Neurosci 2014; 15:379-93. [PMID: 24857965 DOI: 10.1038/nrn3770] [Citation(s) in RCA: 277] [Impact Index Per Article: 27.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Punctuated episodes of spreading depolarizations erupt in the brain, encumbering tissue structure and function, and raising fascinating unanswered questions concerning their initiation and propagation. Linked to migraine aura and headache, cortical spreading depression contributes to the morbidity in the world's migraine with aura population. Even more ominously, erupting spreading depolarizations accelerate tissue damage during brain injury. The once-held view that spreading depolarizations may not exist in the human brain has changed, largely because of the discovery of migraine genes that confer cortical spreading depression susceptibility, the application of sophisticated imaging tools and efforts to interrogate their impact in the acutely injured human brain.
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Affiliation(s)
- Daniela Pietrobon
- Department of Biomedical Sciences and CNR Institute of Neuroscience, University of Padova 35121 Padova, Italy
| | - Michael A Moskowitz
- 1] Stroke and Neurovascular Regulation Laboratory, Departments of Radiology and Neurology, 149 13th Street, Room 6403, Massachusetts General Hospital, Charlestown, Massachusetts 02129, USA. [2] Department of Neurology, Harvard Medical School, Boston, Massachusetts, USA
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25
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Stensrud M, Chaudhry F, Leergaard T, Bjaalie J, Gundersen V. Vesicular glutamate transporter-3 in the rodent brain: Vesicular colocalization with vesicular γ-aminobutyric acid transporter. J Comp Neurol 2013; 521:3042-56. [DOI: 10.1002/cne.23331] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2012] [Revised: 03/08/2013] [Accepted: 03/13/2013] [Indexed: 01/12/2023]
Affiliation(s)
- M.J. Stensrud
- Department of Anatomy; Institute of Basic Medical Sciences, and Centre for Molecular Biology and Neuroscience (CMBN), University of Oslo; 0317 Oslo; Norway
| | - F.A. Chaudhry
- The Biotechnology Centre of Oslo and The Centre for Molecular Biology and Neuroscience (CMBN); University of Oslo; 0317 Oslo; Norway
| | - T.B. Leergaard
- Department of Anatomy; Institute of Basic Medical Sciences, and Centre for Molecular Biology and Neuroscience (CMBN), University of Oslo; 0317 Oslo; Norway
| | - J.G. Bjaalie
- Department of Anatomy; Institute of Basic Medical Sciences, and Centre for Molecular Biology and Neuroscience (CMBN), University of Oslo; 0317 Oslo; Norway
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26
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Poorthuis RB, Mansvelder HD. Nicotinic acetylcholine receptors controlling attention: behavior, circuits and sensitivity to disruption by nicotine. Biochem Pharmacol 2013; 86:1089-98. [PMID: 23856288 DOI: 10.1016/j.bcp.2013.07.003] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2013] [Revised: 07/01/2013] [Accepted: 07/02/2013] [Indexed: 11/26/2022]
Abstract
Attention is a central cognitive function that enables long-term engagement in a task and suppression of irrelevant information to obtain future goals. The prefrontal cortex (PFC) is the main link in integrating emotional and motivational state of an animal to regulate top-down attentional processes. Acetylcholine modulates PFC neuronal networks by activating nicotinic acetylcholine receptors (nAChRs) to support attention. However, how neuronal activity changes in the PFC during attention and which nAChR subtypes mediate this is only rudimentarily understood, but progress is being made. Recently, exciting new insights were obtained in the dynamics of cholinergic signaling in the PFC and modes of acetylcholine transmission via nAChRs in the cortex. In addition, mechanisms are uncovered on how the PFC circuitry is regulated by nAChRs. Novel studies show that endogenous activation of nAChRs in the PFC plays a central role in controlling attention. Here, we review current insights into how different subtypes of nAChRs expressed by distinct types of neurons in the PFC circuitry shape attention. In addition we discuss the impact of nicotine on the cholinergic system and prefrontal cortical circuits. Low concentrations of nicotine, as experienced by smokers, interfere with cholinergic signaling. In the long-term exposure to nicotine during adolescence leads to maladaptive adaptations of the PFC circuitry, which ultimately leads to a decrement in attention performance, again emphasizing the importance of nAChRs in attention.
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Affiliation(s)
- Rogier B Poorthuis
- Department of Integrative Neurophysiology, CNCR, Neuroscience Campus Amsterdam, VU University, Amsterdam, The Netherlands
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27
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Li WH, Li D. Fluorescent probes for monitoring regulated secretion. Curr Opin Chem Biol 2013; 17:672-81. [PMID: 23711436 DOI: 10.1016/j.cbpa.2013.04.026] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2013] [Revised: 04/22/2013] [Accepted: 04/24/2013] [Indexed: 01/14/2023]
Abstract
Numerous secretory cells use the regulated secretory pathway to release signaling molecules. Regulated secretion is an essential component of the intercellular communication network of a multicellular organism and serves diverse functions in neurobiology, endocrinology, and many other aspects of animal physiology. Probes that can monitor a specific exocytotic event with high temporal and spatial resolution would be invaluable tools for studying the molecular and cellular mechanisms underlying stimulus-secretion coupling, and for characterizing secretion defects that are found in different human diseases. This review summarizes different strategies and recent progress in developing fluorescent sensors for imaging regulated cell secretion.
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Affiliation(s)
- Wen-hong Li
- Department of Cell Biology and of Biochemistry, University of Texas Southwestern Medical Center, 6000 Harry Hines Boulevard, Dallas, TX 75390-9039, United States.
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28
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Fung P, Robinson P. Neural field theory of calcium dependent plasticity with applications to transcranial magnetic stimulation. J Theor Biol 2013; 324:72-83. [DOI: 10.1016/j.jtbi.2013.01.013] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2012] [Revised: 01/17/2013] [Accepted: 01/20/2013] [Indexed: 10/27/2022]
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29
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Digital morphometry of rat cerebellar climbing fibers reveals distinct branch and bouton types. J Neurosci 2013; 32:14670-84. [PMID: 23077053 DOI: 10.1523/jneurosci.2018-12.2012] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Cerebellar climbing fibers (CFs) provide powerful excitatory input to Purkinje cells (PCs), which represent the sole output of the cerebellar cortex. Recent discoveries suggest that CFs have information-rich signaling properties important for cerebellar function, beyond eliciting the well known all-or-none PC complex spike. CF morphology has not been quantitatively analyzed at the same level of detail as its biophysical properties. Because morphology can greatly influence function, including the capacity for information processing, it is important to understand CF branching structure in detail, as well as its variability across and within arbors. We have digitally reconstructed 68 rat CFs labeled using biotinylated dextran amine injected into the inferior olive and comprehensively quantified their morphology. CF structure was considerably diverse even within the same anatomical regions. Distinctly identifiable primary, tendril, and distal branches could be operationally differentiated by the relative size of the subtrees at their initial bifurcations. Additionally, primary branches were more directed toward the cortical surface and had fewer and less pronounced synaptic boutons, suggesting they prioritize efficient and reliable signal propagation. Tendril and distal branches were spatially segregated and bouton dense, indicating specialization in signal transmission. Furthermore, CFs systematically targeted molecular layer interneuron cell bodies, especially at terminal boutons, potentially instantiating feedforward inhibition on PCs. This study offers the most detailed and comprehensive characterization of CF morphology to date. The reconstruction files and metadata are publicly distributed at NeuroMorpho.org.
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30
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Stone E, Hoffman K, Kavanaugh M. Identifying neurotransmitter spill-over in hippocampal field recordings. Math Biosci 2012; 240:169-86. [PMID: 22889695 DOI: 10.1016/j.mbs.2012.07.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2011] [Revised: 07/19/2012] [Accepted: 07/20/2012] [Indexed: 10/28/2022]
Abstract
A model of synaptic and extra-synaptic excitatory signaling in the hippocampus is presented. The model is used to analytically evaluate the potential contributions of homosynaptic and heterosynaptic glutamate spill-over to receptor signaling during an electrophysiological experiment in which glutamate transporters are pharmacologically blocked. Inhibition of glutamate uptake selectively prolongs the decay kinetics of the second field excitatory postsynaptic potential evoked by paired pulse stimulation of Schaffer collateral axons in area CA1. The model includes AMPA and NMDA glutamate receptors, and the removal of glutamate by transporters and diffusion. We establish analytically that the prolongation cannot be caused by local effects, i.e., the transporters acting within or near the synapse. In contrast, a time profile of glutamate consistent with spill-over from adjacent synapses can explain the effect. The different reaction kinetics of AMPA and NMDA receptors have a significant role in reproducing the experimental results, as explained by analysis of the ODEs governing the reactions.
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Affiliation(s)
- Emily Stone
- Department of Mathematical Sciences, The University of Montana, Missoula, MT 59812, USA.
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31
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Nuritova F, Frenguelli BG. Putative depolarisation-induced retrograde signalling accelerates the repeated hypoxic depression of excitatory synaptic transmission in area CA1 of rat hippocampus via group I metabotropic glutamate receptors. Neuroscience 2012; 222:159-72. [PMID: 22842516 DOI: 10.1016/j.neuroscience.2012.07.034] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2012] [Revised: 07/16/2012] [Accepted: 07/17/2012] [Indexed: 02/08/2023]
Abstract
Excitatory synaptic transmission in area CA1 of the mammalian hippocampus is rapidly depressed during hypoxia. The depression is largely attributable to an increase in extracellular adenosine and activation of inhibitory adenosine A(1) receptors on presynaptic glutamatergic terminals. However, sequential exposure to hypoxia results in a slower subsequent hypoxic depression of excitatory synaptic transmission, a phenomenon we have previously ascribed to a reduction in the release of extracellular adenosine. In the present study we show that this delayed depression of excitatory postsynaptic currents (EPSCs) to repeated hypoxia can be reversed by a period of postsynaptic depolarisation delivered to an individual CA1 neuron, under whole-cell voltage clamp, between two periods of hypoxia. The depolarisation-induced acceleration of the hypoxic depression of the EPSC is dependent upon postsynaptic Ca(2+) influx, the activation of PKC and is blocked by intracellular application of GDP-β-S and N-ethylmaleimide (NEM), inhibitors of membrane fusion events. In addition, the acceleration of the hypoxic depression of the EPSC was prevented by the GI mGluR antagonist AIDA, but not by the CB1 cannabinoid receptor antagonist AM251. Our results suggest a process initiated in the postsynaptic cell that can influence glutamate release during subsequent metabolic stress. This may reflect a novel neuroprotective strategy potentially involving retrograde release of adenosine and/or glutamate.
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Affiliation(s)
- F Nuritova
- Neurosciences Institute, Division of Pathology & Neuroscience, University of Dundee, Ninewells Hospital & Medical School, Dundee DD1 9SY, UK
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32
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Fuxe K, Borroto-Escuela DO, Romero-Fernandez W, Diaz-Cabiale Z, Rivera A, Ferraro L, Tanganelli S, Tarakanov AO, Garriga P, Narváez JA, Ciruela F, Guescini M, Agnati LF. Extrasynaptic neurotransmission in the modulation of brain function. Focus on the striatal neuronal-glial networks. Front Physiol 2012; 3:136. [PMID: 22675301 PMCID: PMC3366473 DOI: 10.3389/fphys.2012.00136] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2012] [Accepted: 04/23/2012] [Indexed: 12/20/2022] Open
Abstract
Extrasynaptic neurotransmission is an important short distance form of volume transmission (VT) and describes the extracellular diffusion of transmitters and modulators after synaptic spillover or extrasynaptic release in the local circuit regions binding to and activating mainly extrasynaptic neuronal and glial receptors in the neuroglial networks of the brain. Receptor-receptor interactions in G protein-coupled receptor (GPCR) heteromers play a major role, on dendritic spines and nerve terminals including glutamate synapses, in the integrative processes of the extrasynaptic signaling. Heteromeric complexes between GPCR and ion-channel receptors play a special role in the integration of the synaptic and extrasynaptic signals. Changes in extracellular concentrations of the classical synaptic neurotransmitters glutamate and GABA found with microdialysis is likely an expression of the activity of the neuron-astrocyte unit of the brain and can be used as an index of VT-mediated actions of these two neurotransmitters in the brain. Thus, the activity of neurons may be functionally linked to the activity of astrocytes, which may release glutamate and GABA to the extracellular space where extrasynaptic glutamate and GABA receptors do exist. Wiring transmission (WT) and VT are fundamental properties of all neurons of the CNS but the balance between WT and VT varies from one nerve cell population to the other. The focus is on the striatal cellular networks, and the WT and VT and their integration via receptor heteromers are described in the GABA projection neurons, the glutamate, dopamine, 5-hydroxytryptamine (5-HT) and histamine striatal afferents, the cholinergic interneurons, and different types of GABA interneurons. In addition, the role in these networks of VT signaling of the energy-dependent modulator adenosine and of endocannabinoids mainly formed in the striatal projection neurons will be underlined to understand the communication in the striatal cellular networks.
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Affiliation(s)
- Kjell Fuxe
- Department of Neuroscience, Karolinska InstitutetStockholm, Sweden
| | | | | | - Zaida Diaz-Cabiale
- Department of Physiology, School of Medicine, University of MálagaMálaga, Spain
| | - Alicia Rivera
- Department of Cell Biology, Faculty of Sciences, University of MálagaMálaga, Spain
| | - Luca Ferraro
- Pharmacology Section, Department of Clinical and Experimental Medicine, University of FerraraFerrara, Italy
| | - Sergio Tanganelli
- Pharmacology Section, Department of Clinical and Experimental Medicine, University of FerraraFerrara, Italy
| | - Alexander O. Tarakanov
- Russian Academy of Sciences, St. Petersburg Institute for Informatics and AutomationSaint Petersburg, Russia
| | - Pere Garriga
- Departament d’Enginyeria Química, Centre de Biotecnologia Molecular, Universitat Politècnica de CatalunyaBarcelona, Spain
| | - José Angel Narváez
- Department of Physiology, School of Medicine, University of MálagaMálaga, Spain
| | - Francisco Ciruela
- Unitat de Farmacologia, Departament Patologia i Terapèutica Experimental, Universitat de BarcelonaBarcelona, Spain
| | - Michele Guescini
- Department of Biomolecular Sciences, University of Urbino “CarloBo”Urbino, Italy
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33
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Leak RK, Moore RY. Innervation of ventricular and periventricular brain compartments. Brain Res 2012; 1463:51-62. [PMID: 22575559 DOI: 10.1016/j.brainres.2012.04.055] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2012] [Revised: 04/22/2012] [Accepted: 04/29/2012] [Indexed: 01/29/2023]
Abstract
Synaptic transmission is divided into two broad categories on the basis of the distance over which neurotransmitters travel. Wiring transmission is the release of transmitter into synaptic clefts in close apposition to receptors. Volume transmission is the release of transmitters or modulators over varying distances before interacting with receptors. One case of volume transmission over potentially long distances involves release into cerebrospinal fluid (CSF). The CSF contains neuroactive substances that affect brain function and range in size from small molecule transmitters to peptides and large proteins. CSF-contacting neurons are a well-known and universal feature of non-mammalian vertebrates, but only supra- and subependymal serotonergic plexuses are a commonly studied feature in mammals. The origin of most other neuroactive substances in CSF is unknown. In order to determine which brain regions communicate with CSF, we describe the distribution of retrograde neuronal labeling in the rat brain following ventricular injection of Cholera toxin, ß subunit (CTß), a tracer frequently used in brain circuit analysis. Within 15 to 30 min following intraventricular injection, there is only diffuse, non-specific staining adjacent to the ventricular surface. Within 2 to 10 days, however, there is extensive labeling of neuronal perikarya in specific nuclear groups in the telencephalon, thalamus, hypothalamus and brainstem, many at a considerable distance from the ventricles. These observations support the view that ventricular CSF is a significant channel for volume transmission and identifies those brain regions most likely to be involved in this process.
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Affiliation(s)
- Rehana K Leak
- Division of Pharmaceutical Sciences, Mylan School of Pharmacy, Duquesne University, Pittsburgh, PA 15282, USA.
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Tang ZQ, Lu Y. Development of GPCR modulation of GABAergic transmission in chicken nucleus laminaris neurons. PLoS One 2012; 7:e35831. [PMID: 22545142 PMCID: PMC3335798 DOI: 10.1371/journal.pone.0035831] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2012] [Accepted: 03/22/2012] [Indexed: 02/02/2023] Open
Abstract
Neurons in the nucleus laminaris (NL) of birds act as coincidence detectors and encode interaural time difference to localize the sound source in the azimuth plane. GABAergic transmission in a number of CNS nuclei including the NL is subject to a dual modulation by presynaptic GABAB receptors (GABABRs) and metabotropic glutamate receptors (mGluRs). Here, using in vitro whole-cell patch clamp recordings from acute brain slices of the chick, we characterized the following important but unknown properties pertaining to such a dual modulation: (1) emergence of functional GABA synapses in NL neurons; (2) the temporal onset of neuromodulation mediated by GABABRs and mGluRs; and (3) the physiological conditions under which GABABRs and mGluRs are activated by endogenous transmitters. We found that (1) GABAAR-mediated synaptic responses were observed in about half of the neurons at embryonic day 11 (E11); (2) GABABR-mediated modulation of the GABAergic transmission was detectable at E11, whereas the modulation by mGluRs did not emerge until E15; and (3) endogenous activity of GABABRs was induced by both low- (5 or 10 Hz) and high-frequency (200 Hz) stimulation of the GABAergic pathway, whereas endogenous activity of mGluRs was induced by high- (200 Hz) but not low-frequency (5 or 10 Hz) stimulation of the glutamatergic pathway. Furthermore, the endogenous activity of mGluRs was mediated by group II but not group III members. Therefore, autoreceptor-mediated modulation of GABAergic transmission emerges at the same time when the GABA synapses become functional. Heteroreceptor-mediated modulation appears at a later time and is receptor type dependent in vitro.
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Affiliation(s)
- Zheng-Quan Tang
- Department of Anatomy and Neurobiology, Northeast Ohio Medical University, College of Medicine, Rootstown, Ohio, United States of America
| | - Yong Lu
- Department of Anatomy and Neurobiology, Northeast Ohio Medical University, College of Medicine, Rootstown, Ohio, United States of America
- * E-mail:
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Bochorishvili G, Stornetta RL, Coates MB, Guyenet PG. Pre-Bötzinger complex receives glutamatergic innervation from galaninergic and other retrotrapezoid nucleus neurons. J Comp Neurol 2012; 520:1047-61. [PMID: 21935944 PMCID: PMC3925347 DOI: 10.1002/cne.22769] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
The retrotrapezoid nucleus (RTN) contains CO(2) -responsive neurons that regulate breathing frequency and amplitude. These neurons (RTN-Phox2b neurons) contain the transcription factor Phox2b, vesicular glutamate transporter 2 (VGLUT2) mRNA, and a subset contains preprogalanin mRNA. We wished to determine whether the terminals of RTN-Phox2b neurons contain galanin and VGLUT2 proteins, to identify the specific projections of the galaninergic subset, to test whether RTN-Phox2b neurons contact neurons in the pre-Bötzinger complex, and to identify the ultrastructure of these synapses. The axonal projections of RTN-Phox2b neurons were traced by using biotinylated dextran amine (BDA), and many BDA-ir boutons were found to contain galanin immunoreactivity. RTN galaninergic neurons had ipsilateral projections that were identical with those of this nucleus at large: the ventral respiratory column, the caudolateral nucleus of the solitary tract, and the pontine Kölliker-Fuse, intertrigeminal region, and lateral parabrachial nucleus. For ultrastructural studies, RTN-Phox2b neurons (galaninergic and others) were transfected with a lentiviral vector that expresses mCherry almost exclusively in Phox2b-ir neurons. After spinal cord injections of a catecholamine neuron-selective toxin, there was a depletion of C1 neurons in the RTN area; thus it was determined that the mCherry-positive terminals located in the pre-Bötzinger complex originated almost exclusively from the RTN-Phox2b (non-C1) neurons. These terminals were generally VGLUT2-immunoreactive and formed numerous close appositions with neurokinin-1 receptor-ir pre-Bötzinger complex neurons. Their boutons (n = 48) formed asymmetric synapses filled with small clear vesicles. In summary, RTN-Phox2b neurons, including the galaninergic subset, selectively innervate the respiratory pattern generator plus a portion of the dorsolateral pons. RTN-Phox2b neurons establish classic excitatory glutamatergic synapses with pre-Bötzinger complex neurons presumed to generate the respiratory rhythm.
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Affiliation(s)
| | - Ruth L. Stornetta
- Department of Pharmacology, University of Virginia, Charlottesville, Virginia 22908
| | - Melissa B. Coates
- Department of Pharmacology, University of Virginia, Charlottesville, Virginia 22908
| | - Patrice G. Guyenet
- Department of Pharmacology, University of Virginia, Charlottesville, Virginia 22908
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Bergersen LH, Gjedde A. Is lactate a volume transmitter of metabolic states of the brain? FRONTIERS IN NEUROENERGETICS 2012; 4:5. [PMID: 22457647 PMCID: PMC3307048 DOI: 10.3389/fnene.2012.00005] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/14/2012] [Accepted: 03/01/2012] [Indexed: 11/13/2022]
Abstract
We present the perspective that lactate is a volume transmitter of cellular signals in brain that acutely and chronically regulate the energy metabolism of large neuronal ensembles. From this perspective, we interpret recent evidence to mean that lactate transmission serves the maintenance of network metabolism by two different mechanisms, one by regulating the formation of cAMP via the lactate receptor GPR81, the other by adjusting the NADH/NAD(+) redox ratios, both linked to the maintenance of brain energy turnover and possibly cerebral blood flow. The role of lactate as mediator of metabolic information rather than metabolic substrate answers a number of questions raised by the controversial oxidativeness of astrocytic metabolism and its contribution to neuronal function.
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Affiliation(s)
- Linda H Bergersen
- The Brain and Muscle Energy Group, Centre for Molecular Biology and Neuroscience, Institute for Basic Medical Sciences, University of Oslo, Oslo, Norway
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Synaptic and extrasynaptic NMDA receptors differentially modulate neuronal cyclooxygenase-2 function, lipid peroxidation, and neuroprotection. J Neurosci 2011; 31:13710-21. [PMID: 21957234 DOI: 10.1523/jneurosci.3544-11.2011] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Stimulation of synaptic NMDA receptors (NMDARs) induces neuroprotection, while extrasynaptic NMDARs promote excitotoxic cell death. Neuronal expression of cyclooxygenase-2 (COX-2) is enhanced by synaptic NMDARs, and although this enzyme mediates neuronal functions, COX-2 is also regarded as a key modulator of neuroinflammation and is thought to exacerbate excitotoxicity via overproduction of prostaglandins. This raises an apparent paradox: synaptic NMDARs are pro-survival yet are essential for robust neuronal COX-2 expression. We hypothesized that stimulation of extrasynaptic NMDARs converts COX-2 signaling from a physiological to a potentially pathological process. We combined HPLC-electrospray ionization-tandem MS-based mediator lipidomics and unbiased image analysis in mouse dissociated and organotypic cortical cultures to uncover that synaptic and extrasynaptic NMDARs differentially modulate neuronal COX-2 expression and activity. We show that synaptic NMDARs enhance neuronal COX-2 expression, while sustained synaptic stimulation limits COX-2 activity by suppressing cellular levels of the primary COX-2 substrate, arachidonic acid (AA). In contrast, extrasynaptic NMDARs suppress COX-2 expression while activating phospholipase A₂, which enhances AA levels by hydrolysis of membrane phospholipids. Thus, sequential activation of synaptic then extrasynaptic NMDARs maximizes COX-2-dependent prostaglandin synthesis. We also show that excitotoxic events only drive induction of COX-2 expression through abnormal synaptic network excitability. Finally, we show that nonenzymatic lipid peroxidation of arachidonic and other polyunsaturated fatty acids is a function of network activity history. A new paradigm emerges from our results suggesting that pathological COX-2 signaling associated with models of stroke, epilepsy, and neurodegeneration requires specific spatiotemporal NMDAR stimulation.
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