51
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Steinert JR. Activated inhibition in regulating excitability. J Physiol 2017; 595:3243-3244. [PMID: 28295346 PMCID: PMC5451725 DOI: 10.1113/jp274196] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Affiliation(s)
- Joern R Steinert
- MRC Toxicology Unit, Hodgkin Building, University of Leicester, Lancaster Road, Leicester, LE1 9HN, UK
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52
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Rodriguez-Grande B, Konsman JP. Gas Diffusion in the CNS. J Neurosci Res 2017; 96:207-218. [PMID: 28504343 DOI: 10.1002/jnr.24077] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Revised: 03/23/2017] [Accepted: 04/10/2017] [Indexed: 12/21/2022]
Abstract
Gases have been long known to have essential physiological functions in the CNS such as respiration or regulation of vascular tone. Since gases have been classically considered to freely diffuse, research in gas biology has so far focused on mechanisms of gas synthesis and gas reactivity, rather than gas diffusion and transport. However, the discovery of gas pores during the last two decades and the characterization of diverse diffusion patterns through different membranes has raised the possibility that modulation of gas diffusion is also a physiologically relevant parameter. Here we review the means of gas movement into and within the brain through "free" diffusion and gas pores, notably aquaporins, discussing the role that gas diffusion may play in the modulation of gas function. We highlight how diffusion is relevant to neuronal signaling, volume transmission, and cerebrovascular control in the case of NO, one of the most extensively studied gases. We point out how facilitated transport can be especially relevant for gases with low permeability in lipid membranes like NH3 and discuss the possible implications of NH3 -permeable channels in physiology and hyperammonemic encephalopathy. We identify novel research questions about how modulation of gas diffusion could intervene in CNS pathologies. This emerging area of research can provide novel and interesting insights in the field of gas biology.
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53
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Shi W, Lu Y. Metabotropic glutamate and GABA receptors modulate cellular excitability and glutamatergic transmission in chicken cochlear nucleus angularis neurons. Hear Res 2017; 346:14-24. [PMID: 28104407 DOI: 10.1016/j.heares.2017.01.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/05/2016] [Revised: 12/20/2016] [Accepted: 01/12/2017] [Indexed: 12/25/2022]
Abstract
Neurons in the avian cochlear nucleus angularis (NA) receive glutamatergic input from the auditory nerve, and GABAergic input from the superior olivary nucleus. Physiologically heterogeneous, NA neurons perform multiple functions including encoding sound intensity information. Using in vitro whole-cell patch recordings from acute brain slices and immunohistochemistry staining, we investigated neuromodulation mediated by metabotropic glutamate and GABA receptors (mGluRs and GABABRs) in NA neurons. Based on their intrinsic firing patterns in response to somatic current injections, NA neurons were classified into onset, damped, and tonic cells. Pharmacological activation of group II mGluRs, group III mGluRs, and GABABRs, by their respective agonists, suppressed the cellular excitability of non-onset firing NA neurons. Each of these agonists inhibited the glutamatergic transmission in NA neurons, in a cell type-independent manner. The frequency but not the amplitude of spontaneous release of glutamate was reduced by each of these agonists, suggesting that the modulation of the glutamatergic transmission was via presynaptic actions. Interestingly, activation of group I mGluRs increased cellular excitability and suppressed glutamatergic transmission in non-onset neurons. These results elaborate that auditory processing in NA neurons is subject to neuromodulation mediated by metabotropic receptors activated by native neurotransmitters released at NA.
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Affiliation(s)
- Wei Shi
- Department of Anatomy and Neurobiology, College of Medicine, Northeast Ohio Medical University, Rootstown, OH 44272, USA; School of Biomedical Sciences, Kent State University, Kent, OH 44240, USA; School of Life Science, Tsinghua University, Beijing, 100084, PR China.
| | - Yong Lu
- Department of Anatomy and Neurobiology, College of Medicine, Northeast Ohio Medical University, Rootstown, OH 44272, USA; School of Biomedical Sciences, Kent State University, Kent, OH 44240, USA.
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54
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Sweeney Y, Clopath C. Emergent spatial synaptic structure from diffusive plasticity. Eur J Neurosci 2016; 45:1057-1067. [DOI: 10.1111/ejn.13279] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2016] [Revised: 05/04/2016] [Accepted: 05/13/2016] [Indexed: 11/29/2022]
Affiliation(s)
- Yann Sweeney
- Department of Bioengineering; Imperial College London, South Kensington Campus; London SW7 2AZ UK
| | - Claudia Clopath
- Department of Bioengineering; Imperial College London, South Kensington Campus; London SW7 2AZ UK
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55
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Nitric Oxide: A Regulator of Cellular Function in Health and Disease. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2015; 2016:9782346. [PMID: 26798429 PMCID: PMC4699049 DOI: 10.1155/2016/9782346] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 10/04/2015] [Accepted: 10/04/2015] [Indexed: 01/09/2023]
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56
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Yu H, Liao Y, Li T, Cui Y, Wang G, Zhao F, Jin Y. Alterations of Synaptic Proteins in the Hippocampus of Mouse Offspring Induced by Developmental Lead Exposure. Mol Neurobiol 2015; 53:6786-6798. [DOI: 10.1007/s12035-015-9597-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2015] [Accepted: 12/01/2015] [Indexed: 12/22/2022]
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57
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Garthwaite J. From synaptically localized to volume transmission by nitric oxide. J Physiol 2015; 594:9-18. [PMID: 26486504 DOI: 10.1113/jp270297] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Accepted: 10/13/2015] [Indexed: 12/22/2022] Open
Abstract
Nitric oxide (NO) functions widely as a transmitter/diffusible second messenger in the central nervous system, exerting physiological effects in target cells by binding to specialized guanylyl cyclase-coupled receptors, resulting in cGMP generation. Despite having many context-dependent physiological roles and being implicated in numerous disease states, there has been a lack of clarity about the ways that NO operates at the cellular and subcellular levels. Recently, several approaches have been used to try to gain a more concrete, quantitative understanding of this unique signalling pathway. These approaches have included analysing the kinetics of NO receptor function, real-time imaging of cellular NO signal transduction in target cells, and the use of ultrasensitive detector cells to record NO as it is being generated from native sources in brain tissue. The current picture is that, when formed in a synapse, NO is likely to act only very locally, probably mostly within the confines of that synapse, and to exist only in picomolar concentrations. Nevertheless, closely neighbouring synapses may also be within reach, raising the possibility of synaptic crosstalk. By engaging its enzyme-coupled receptors, the low NO concentrations are able to stimulate physiological (submicromolar) increases in cGMP concentration in an activity-dependent manner. When many NO-emitting neurones or synapses are active simultaneously in a tissue region, NO can act more like a volume transmitter to influence, and perhaps coordinate, the behaviour of cells within that region, irrespective of their identity and anatomical connectivity.
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Affiliation(s)
- John Garthwaite
- Wolfson Institute for Biomedical Research, University College London, Gower Street, London, WC1E 6BT, UK
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58
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Nitric Oxide-Mediated Posttranslational Modifications: Impacts at the Synapse. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2015; 2016:5681036. [PMID: 26635909 PMCID: PMC4655263 DOI: 10.1155/2016/5681036] [Citation(s) in RCA: 74] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/15/2015] [Accepted: 06/28/2015] [Indexed: 11/18/2022]
Abstract
Nitric oxide (NO) is an important gasotransmitter molecule that is involved in numerous physiological processes throughout the nervous system. In addition to its involvement in physiological plasticity processes (long-term potentiation, LTP; long-term depression, LTD) which can include NMDAR-mediated calcium-dependent activation of neuronal nitric oxide synthase (nNOS), new insights into physiological and pathological consequences of nitrergic signalling have recently emerged. In addition to the canonical cGMP-mediated signalling, NO is also implicated in numerous pathways involving posttranslational modifications. In this review we discuss the multiple effects of S-nitrosylation and 3-nitrotyrosination on proteins with potential modulation of function but limit the analyses to signalling involved in synaptic transmission and vesicular release. Here, crucial proteins which mediate synaptic transmission can undergo posttranslational modifications with either pre- or postsynaptic origin. During normal brain function, both pathways serve as important cellular signalling cascades that modulate a diverse array of physiological processes, including synaptic plasticity, transcriptional activity, and neuronal survival. In contrast, evidence suggests that aging and disease can induce nitrosative stress via excessive NO production. Consequently, uncontrolled S-nitrosylation/3-nitrotyrosination can occur and represent pathological features that contribute to the onset and progression of various neurodegenerative diseases, including Parkinson's, Alzheimer's, and Huntington's.
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59
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Perineuronal nets in the auditory system. Hear Res 2015; 329:21-32. [DOI: 10.1016/j.heares.2014.12.012] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/16/2014] [Revised: 12/03/2014] [Accepted: 12/29/2014] [Indexed: 12/19/2022]
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60
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Parodi J, Montecinos-Oliva C, Varas R, Alfaro IE, Serrano FG, Varas-Godoy M, Muñoz FJ, Cerpa W, Godoy JA, Inestrosa NC. Wnt5a inhibits K(+) currents in hippocampal synapses through nitric oxide production. Mol Cell Neurosci 2015; 68:314-22. [PMID: 26311509 DOI: 10.1016/j.mcn.2015.08.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2014] [Revised: 06/05/2015] [Accepted: 08/19/2015] [Indexed: 02/06/2023] Open
Abstract
Hippocampal synapses play a key role in memory and learning processes by inducing long-term potentiation and depression. Wnt signaling is essential in the development and maintenance of synapses via several mechanisms. We have previously found that Wnt5a induces the production of nitric oxide (NO), which modulates NMDA receptor expression in the postsynaptic regions of hippocampal neurons. Here, we report that Wnt5a selectively inhibits a voltage-gated K(+) current (Kv current) and increases synaptic activity in hippocampal slices. Further supporting a specific role for Wnt5a, the soluble Frizzled receptor protein (sFRP-2; a functional Wnt antagonist) fully inhibits the effects of Wnt5a. We additionally show that these responses to Wnt5a are mediated by activation of a ROR2 receptor and increased NO production because they are suppressed by the shRNA-mediated knockdown of ROR2 and by 7-nitroindazole, a specific inhibitor of neuronal NOS. Together, our results show that Wnt5a increases NO production by acting on ROR2 receptors, which in turn inhibit Kv currents. These results reveal a novel mechanism by which Wnt5a may regulate the excitability of hippocampal neurons.
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Affiliation(s)
- Jorge Parodi
- Centro de Envejecimiento y Regeneración (CARE), Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Carla Montecinos-Oliva
- Centro de Envejecimiento y Regeneración (CARE), Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Rodrigo Varas
- Facultad de Ciencias de la Salud, Universidad Autónoma de Chile, Talca, Chile
| | - Iván E Alfaro
- Fundación Ciencia y Vida, Santiago, Chile; Facultad de Ciencias Naturales y Exactas, Universidad de Playa Ancha, Valparaiso, Chile
| | - Felipe G Serrano
- Centro de Envejecimiento y Regeneración (CARE), Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | | | - Francisco J Muñoz
- Laboratory of Molecular Physiology and Channelopathies, Department of Experimental and Health Sciences, Universitat Pompeu Fabra, Parc de Recerca Biomédica de Barcelonab, Spain
| | - Waldo Cerpa
- Laboratorio de Función y Patología Neuronal, Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, P. Universidad Católica de Chile, Santiago, Chile
| | - Juan A Godoy
- Centro de Envejecimiento y Regeneración (CARE), Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile; Laboratory of Molecular Physiology and Channelopathies, Department of Experimental and Health Sciences, Universitat Pompeu Fabra, Parc de Recerca Biomédica de Barcelonab, Spain
| | - Nibaldo C Inestrosa
- Centro de Envejecimiento y Regeneración (CARE), Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile; Centre for Healthy Brain Ageing, School of Psychiatry, Faculty of Medicine, University of New South Wales, Sydney, Australia; Centro UC Síndrome de Down, Pontificia Universidad Católica de Chile, Santiago, Chile; Centro de Excelencia en Biomedicina de Magallanes (CEBIMA), Universidad de Magallanes, Punta Arenas, Chile.
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61
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Nacsa K, Elekes K, Serfőző Z. Ultrastructural localization of NADPH diaphorase and nitric oxide synthase in the neuropils of the snail CNS. Micron 2015; 75:58-66. [DOI: 10.1016/j.micron.2015.04.015] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2015] [Revised: 04/28/2015] [Accepted: 04/30/2015] [Indexed: 12/15/2022]
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62
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Sweeney Y, Hellgren Kotaleski J, Hennig MH. A Diffusive Homeostatic Signal Maintains Neural Heterogeneity and Responsiveness in Cortical Networks. PLoS Comput Biol 2015; 11:e1004389. [PMID: 26158556 PMCID: PMC4497656 DOI: 10.1371/journal.pcbi.1004389] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2014] [Accepted: 06/09/2015] [Indexed: 11/18/2022] Open
Abstract
Gaseous neurotransmitters such as nitric oxide (NO) provide a unique and often overlooked mechanism for neurons to communicate through diffusion within a network, independent of synaptic connectivity. NO provides homeostatic control of intrinsic excitability. Here we conduct a theoretical investigation of the distinguishing roles of NO-mediated diffusive homeostasis in comparison with canonical non-diffusive homeostasis in cortical networks. We find that both forms of homeostasis provide a robust mechanism for maintaining stable activity following perturbations. However, the resulting networks differ, with diffusive homeostasis maintaining substantial heterogeneity in activity levels of individual neurons, a feature disrupted in networks with non-diffusive homeostasis. This results in networks capable of representing input heterogeneity, and linearly responding over a broader range of inputs than those undergoing non-diffusive homeostasis. We further show that these properties are preserved when homeostatic and Hebbian plasticity are combined. These results suggest a mechanism for dynamically maintaining neural heterogeneity, and expose computational advantages of non-local homeostatic processes.
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Affiliation(s)
- Yann Sweeney
- Institute for Adaptive and Neural Computation, School of Informatics, University of Edinburgh, Edinburgh, United Kingdom
- Department of Computational Biology, School of Computer Science and Communication, Royal Institute of Technology, Stockholm, Sweden
- * E-mail:
| | - Jeanette Hellgren Kotaleski
- Department of Computational Biology, School of Computer Science and Communication, Royal Institute of Technology, Stockholm, Sweden
| | - Matthias H. Hennig
- Institute for Adaptive and Neural Computation, School of Informatics, University of Edinburgh, Edinburgh, United Kingdom
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63
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Raju K, Doulias PT, Evans P, Krizman EN, Jackson JG, Horyn O, Daikhin Y, Nissim I, Yudkoff M, Nissim I, Sharp KA, Robinson MB, Ischiropoulos H. Regulation of brain glutamate metabolism by nitric oxide and S-nitrosylation. Sci Signal 2015; 8:ra68. [PMID: 26152695 DOI: 10.1126/scisignal.aaa4312] [Citation(s) in RCA: 97] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Nitric oxide (NO) is a signaling intermediate during glutamatergic neurotransmission in the central nervous system (CNS). NO signaling is in part accomplished through cysteine S-nitrosylation, a posttranslational modification by which NO regulates protein function and signaling. In our investigation of the protein targets and functional impact of S-nitrosylation in the CNS under physiological conditions, we identified 269 S-nitrosocysteine residues in 136 proteins in the wild-type mouse brain. The number of sites was significantly reduced in the brains of mice lacking endothelial nitric oxide synthase (eNOS(-/-)) or neuronal nitric oxide synthase (nNOS(-/-)). In particular, nNOS(-/-) animals showed decreased S-nitrosylation of proteins that participate in the glutamate/glutamine cycle, a metabolic process by which synaptic glutamate is recycled or oxidized to provide energy. (15)N-glutamine-based metabolomic profiling and enzymatic activity assays indicated that brain extracts from nNOS(-/-) mice converted less glutamate to glutamine and oxidized more glutamate than those from mice of the other genotypes. GLT1 [also known as EAAT2 (excitatory amino acid transporter 2)], a glutamate transporter in astrocytes, was S-nitrosylated at Cys(373) and Cys(561) in wild-type and eNOS(-/-) mice, but not in nNOS(-/-) mice. A form of rat GLT1 that could not be S-nitrosylated at the equivalent sites had increased glutamate uptake compared to wild-type GLT1 in cells exposed to an S-nitrosylating agent. Thus, NO modulates glutamatergic neurotransmission through the selective, nNOS-dependent S-nitrosylation of proteins that govern glutamate transport and metabolism.
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Affiliation(s)
- Karthik Raju
- Neuroscience Graduate Group, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Paschalis-Thomas Doulias
- Division of Neonatology, Department of Pediatrics, Children's Hospital of Philadelphia Research Institute, Philadelphia, PA 19104, USA
| | - Perry Evans
- Department of Biomedical and Health Informatics, Children's Hospital of Philadelphia Research Institute, Philadelphia, PA 19104, USA
| | - Elizabeth N Krizman
- Division of Neurology, Department of Pediatrics, Children's Hospital of Philadelphia Research Institute, Philadelphia, PA 19104, USA
| | - Joshua G Jackson
- Division of Neurology, Department of Pediatrics, Children's Hospital of Philadelphia Research Institute, Philadelphia, PA 19104, USA
| | - Oksana Horyn
- Division of Genetic and Metabolic Disease, Department of Pediatrics, Children's Hospital of Philadelphia Research Institute, Philadelphia, PA 19104, USA
| | - Yevgeny Daikhin
- Division of Genetic and Metabolic Disease, Department of Pediatrics, Children's Hospital of Philadelphia Research Institute, Philadelphia, PA 19104, USA
| | - Ilana Nissim
- Division of Genetic and Metabolic Disease, Department of Pediatrics, Children's Hospital of Philadelphia Research Institute, Philadelphia, PA 19104, USA
| | - Marc Yudkoff
- Division of Genetic and Metabolic Disease, Department of Pediatrics, Children's Hospital of Philadelphia Research Institute, Philadelphia, PA 19104, USA
| | - Itzhak Nissim
- Division of Genetic and Metabolic Disease, Department of Pediatrics, Children's Hospital of Philadelphia Research Institute, Philadelphia, PA 19104, USA. Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Kim A Sharp
- Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Michael B Robinson
- Neuroscience Graduate Group, University of Pennsylvania, Philadelphia, PA 19104, USA. Division of Neurology, Department of Pediatrics, Children's Hospital of Philadelphia Research Institute, Philadelphia, PA 19104, USA. Department of Systems Pharmacology and Translational Therapeutics, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Harry Ischiropoulos
- Neuroscience Graduate Group, University of Pennsylvania, Philadelphia, PA 19104, USA. Division of Neonatology, Department of Pediatrics, Children's Hospital of Philadelphia Research Institute, Philadelphia, PA 19104, USA. Department of Systems Pharmacology and Translational Therapeutics, University of Pennsylvania, Philadelphia, PA 19104, USA.
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64
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Gao F, Berrebi AS. Forward masking in the medial nucleus of the trapezoid body of the rat. Brain Struct Funct 2015; 221:2303-17. [PMID: 25921974 DOI: 10.1007/s00429-015-1044-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2014] [Accepted: 04/10/2015] [Indexed: 10/23/2022]
Abstract
Perception of acoustic stimuli is modulated by the temporal and spectral relationship between sound components. Forward masking experiments show that the perception threshold for a probe tone is significantly impaired by a preceding masker stimulus. Forward masking has been systematically studied at the level of the auditory nerve, cochlear nucleus, inferior colliculus and auditory cortex, but not yet in the superior olivary complex. The medial nucleus of the trapezoid body (MNTB), a principal cell group of the superior olive, plays an essential role in sound localization. The MNTB receives excitatory input from the contralateral cochlear nucleus via the calyces of Held and innervates the ipsilateral lateral and medial superior olives, as well as the superior paraolivary nucleus. Here, we performed single-unit extracellular recordings in the MNTB of rats. Using a forward masking paradigm previously employed in studies of the inferior colliculus and auditory nerve, we determined response thresholds for a 20-ms characteristic frequency pure tone (the probe), and then presented it in conjunction with another tone (the masker) that was varied in intensity, duration, and frequency; we also systematically varied the masker-to-probe delay. Probe response thresholds increased and response magnitudes decreased when a masker was presented. The forward suppression effects were greater when masker level and masker duration were increased, when the masker frequency approached the MNTB unit's characteristic frequency, and as the masker-to-probe delay was shortened. Probe threshold shifts showed an exponential decay as the masker-to-probe delay increased.
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Affiliation(s)
- Fei Gao
- Departments of Otolaryngology, Head and Neck Surgery, Neurobiology and Anatomy, Sensory Neuroscience Research Center, Health Sciences Center, West Virginia University School of Medicine, PO Box 9303, Morgantown, WV, 26506, USA
| | - Albert S Berrebi
- Departments of Otolaryngology, Head and Neck Surgery, Neurobiology and Anatomy, Sensory Neuroscience Research Center, Health Sciences Center, West Virginia University School of Medicine, PO Box 9303, Morgantown, WV, 26506, USA.
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65
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Synaptic plasticity in the auditory system: a review. Cell Tissue Res 2015; 361:177-213. [PMID: 25896885 DOI: 10.1007/s00441-015-2176-x] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2015] [Accepted: 03/18/2015] [Indexed: 01/19/2023]
Abstract
Synaptic transmission via chemical synapses is dynamic, i.e., the strength of postsynaptic responses may change considerably in response to repeated synaptic activation. Synaptic strength is increased during facilitation, augmentation and potentiation, whereas a decrease in synaptic strength is characteristic for depression and attenuation. This review attempts to discuss the literature on short-term and long-term synaptic plasticity in the auditory brainstem of mammals and birds. One hallmark of the auditory system, particularly the inner ear and lower brainstem stations, is information transfer through neurons that fire action potentials at very high frequency, thereby activating synapses >500 times per second. Some auditory synapses display morphological specializations of the presynaptic terminals, e.g., calyceal extensions, whereas other auditory synapses do not. The review focuses on short-term depression and short-term facilitation, i.e., plastic changes with durations in the millisecond range. Other types of short-term synaptic plasticity, e.g., posttetanic potentiation and depolarization-induced suppression of excitation, will be discussed much more briefly. The same holds true for subtypes of long-term plasticity, like prolonged depolarizations and spike-time-dependent plasticity. We also address forms of plasticity in the auditory brainstem that do not comprise synaptic plasticity in a strict sense, namely short-term suppression, paired tone facilitation, short-term adaptation, synaptic adaptation and neural adaptation. Finally, we perform a meta-analysis of 61 studies in which short-term depression (STD) in the auditory system is opposed to short-term depression at non-auditory synapses in order to compare high-frequency neurons with those that fire action potentials at a lower rate. This meta-analysis reveals considerably less STD in most auditory synapses than in non-auditory ones, enabling reliable, failure-free synaptic transmission even at frequencies >100 Hz. Surprisingly, the calyx of Held, arguably the best-investigated synapse in the central nervous system, depresses most robustly. It will be exciting to reveal the molecular mechanisms that set high-fidelity synapses apart from other synapses that function much less reliably.
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66
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Kopp-Scheinpflug C, Pigott BM, Forsythe ID. Nitric oxide selectively suppresses IH currents mediated by HCN1-containing channels. J Physiol 2015; 593:1685-700. [PMID: 25605440 PMCID: PMC4386966 DOI: 10.1113/jphysiol.2014.282194] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2014] [Accepted: 01/16/2015] [Indexed: 12/12/2022] Open
Abstract
Hyperpolarization-activated non-specific cation-permeable channels (HCN) mediate I(H) currents, which are modulated by cGMP and cAMP and by nitric oxide (NO) signalling. Channel properties depend upon subunit composition (HCN1-4 and accessory subunits) as demonstrated in expression systems, but physiological relevance requires investigation in native neurons with intact intracellular signalling. Here we use the superior olivary complex (SOC), which exhibits a distinctive pattern of HCN1 and HCN2 expression, to investigate NO modulation of the respective I(H) currents, and compare properties in wild-type and HCN1 knockout mice. The medial nucleus of the trapezoid body (MNTB) expresses HCN2 subunits exclusively, and sends inhibitory projections to the medial and lateral superior olives (MSO, LSO) and the superior paraolivary nucleus (SPN). In contrast to the MNTB, these target nuclei possess an I(H) with fast kinetics, and they express HCN1 subunits. NO is generated in the SOC following synaptic activity and here we show that NO selectively suppresses HCN1, while enhancing IH mediated by HCN2 subunits. NO hyperpolarizes the half-activation of HCN1-mediated currents and slows the kinetics of native IH currents in the MSO, LSO and SPN. This modulation was independent of cGMP and absent in transgenic mice lacking HCN1. Independently, NO signalling depolarizes the half-activation of HCN2-mediated I(H) currents in a cGMP-dependent manner. Thus, NO selectively suppresses fast HCN1-mediated I(H) and facilitates a slow HCN2-mediated I(H) , so generating a spectrum of modulation, dependent on the local expression of HCN1 and/or HCN2.
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Affiliation(s)
- Cornelia Kopp-Scheinpflug
- Division of Neurobiology, Department Biology II, Ludwig-Maximilians-University Munich, Großhadernerstr. 282152, Planegg-Martinsried, Germany
| | - Beatrice M Pigott
- Department of Cell Physiology and Pharmacology, University of LeicesterLeicester, LE1 9HN, UK
| | - Ian D Forsythe
- Department of Cell Physiology and Pharmacology, University of LeicesterLeicester, LE1 9HN, UK
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67
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Zhong LR, Estes S, Artinian L, Rehder V. Cell-specific regulation of neuronal activity by endogenous production of nitric oxide. Eur J Neurosci 2015; 41:1013-24. [DOI: 10.1111/ejn.12875] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2014] [Revised: 12/09/2014] [Accepted: 02/11/2015] [Indexed: 11/30/2022]
Affiliation(s)
- Lei Ray Zhong
- Biology Department; Georgia State University; Atlanta GA 30302 USA
| | - Stephen Estes
- Biology Department; Georgia State University; Atlanta GA 30302 USA
| | - Liana Artinian
- Biology Department; Georgia State University; Atlanta GA 30302 USA
| | - Vincent Rehder
- Biology Department; Georgia State University; Atlanta GA 30302 USA
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Coomber B, Kowalkowski VL, Berger JI, Palmer AR, Wallace MN. Modulating central gain in tinnitus: changes in nitric oxide synthase in the ventral cochlear nucleus. Front Neurol 2015; 6:53. [PMID: 25806021 PMCID: PMC4354362 DOI: 10.3389/fneur.2015.00053] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2014] [Accepted: 02/25/2015] [Indexed: 01/30/2023] Open
Abstract
A significant challenge in tinnitus research lies in explaining how acoustic insult leads to tinnitus in some individuals, but not others. One possibility is genetic variability in the expression and function of neuromodulators – components of neural signaling that alter the balance of excitation and inhibition in neural circuits. An example is nitric oxide (NO) – a free radical and potent neuromodulator in the mammalian brain – that regulates plasticity via both pre-synaptic and postsynaptic mechanisms. Changes in NO have previously been implicated in tinnitus generation, specifically in the ventral cochlear nucleus (VCN). Here, we examined nitric oxide synthase (NOS) – the enzyme responsible for NO production – in the guinea pig VCN following acoustic trauma. NOS was present in most cell types – including spherical and globular bushy cells, small, medium, and large multipolar cells, and octopus cells – spanning the entire extent of the VCN. The staining pattern was symmetrical in control animals. Unilateral acoustic over-exposure (AOE) resulted in marked asymmetries between ipsilateral and contralateral sides of the VCN in terms of the distribution of NOS across the cochlear nuclei in animals with behavioral evidence of tinnitus: fewer NOS-positive cells and a reduced level of NOS staining was present across the whole extent of the contralateral VCN, relative to the ipsilateral VCN. The asymmetric pattern of NOS-containing cells was observed as early as 1 day after AOE and was also present in some animals at 3, 7, and 21 days after AOE. However, it was not until 8 weeks after AOE, when tinnitus had developed, that asymmetries were significant overall, compared with control animals. Asymmetrical NOS expression was not correlated with shifts in the threshold hearing levels. Variability in NOS expression between animals may represent one underlying difference that can be linked to whether or not tinnitus develops after noise exposure.
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Affiliation(s)
- Ben Coomber
- MRC Institute of Hearing Research , Nottingham , UK
| | - Victoria L Kowalkowski
- MRC Institute of Hearing Research , Nottingham , UK ; Otology and Hearing, Division of Clinical Neuroscience, University of Nottingham , Nottingham , UK
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Bradley SA, Steinert JR. Characterisation and comparison of temporal release profiles of nitric oxide generating donors. J Neurosci Methods 2015; 245:116-24. [PMID: 25749567 PMCID: PMC4401449 DOI: 10.1016/j.jneumeth.2015.02.024] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Revised: 02/19/2015] [Accepted: 02/20/2015] [Indexed: 01/11/2023]
Abstract
Nitric oxide release profiles were characterised for commonly used donors. Released NO differs greatly between donors and depends on storage conditions. High release donors (NOC-5, PAPA NONOate) decay quickly. SNP and GSNO show greater stability releasing consistent lower NO levels. This comprehensive characterisation provides knowledge to define NO concentrations released in vitro.
Background Nitric oxide (NO) is a vital signalling molecule in a variety of tissues including the neuronal, vascular and reproductive system. However, its high diffusibility and inactivation make characterisation of nitrergic signalling difficult. The use of NO donors is essential to characterise downstream signalling pathways but knowledge of donor release capacities is lacking, thus making comparisons of donor responses difficult. New method This study characterises NO profiles of commonly used NO donors. Donors were stored under defined conditions and temporal release profiles detected to allow determination of released NO concentrations. Results Using NO-sensitive microsensors we assessed release profiles of NO donors following different storage times and conditions. We found that donors such as NOC-5 and PAPA-NONOate decayed substantially within days, whereas SNP and GSNO showed greater stability releasing consistent levels of NO over days. In all donors tested, the amount of released NO differs between frozen and unfrozen stocks. Comparison with existing method(s) Fluorescent and amperometric approaches to measure NO concentrations yield a wide range of levels. However, due to a lack of characterisation of the release profiles, inconsistent effects on NO signalling have been widely documented. Our systematic assessment of release profiles of a range of NO donors therefore provides new essential data allowing for improved and defined investigations of nitrergic signalling. Conclusions This is the first systematic comparison of temporal release profiles of different NO donors allowing researchers to compare conditions across different studies and the use of defined NO levels by choosing specific donors and concentrations.
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Affiliation(s)
- Sophie A Bradley
- MRC Toxicology Unit, Hodgkin Building, University of Leicester, Leicester LE1 9HN, UK
| | - Joern R Steinert
- MRC Toxicology Unit, Hodgkin Building, University of Leicester, Leicester LE1 9HN, UK.
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70
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Donato F, Borges Filho C, Giacomeli R, Alvater EET, Del Fabbro L, Antunes MDS, de Gomes MG, Goes ATR, Souza LC, Boeira SP, Jesse CR. Evidence for the Involvement of Potassium Channel Inhibition in the Antidepressant-Like Effects of Hesperidin in the Tail Suspension Test in Mice. J Med Food 2015; 18:818-23. [PMID: 25647144 DOI: 10.1089/jmf.2014.0074] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The administration of hesperidin elicits an antidepressant-like effect in mice by a mechanism dependent on an interaction with the L-arginine-nitric oxide (NO)-cyclic guanosine monophosphate (cGMP) pathway, whose stimulation is associated with the activation of potassium (K(+)) channels. Thus, this study investigated the involvement of different types of K(+) channels in the antidepressant-like effect of hesperidin in the mice tail suspension test (TST). The intracerebroventricular administration of tetraethylammonium (TEA, a nonspecific blocker of K(+) channels), glibenclamide (an ATP-sensitive K(+) channel blocker), charybdotoxin (a large- and intermediate-conductance calcium-activated K(+) channel blocker) or apamin (a small-conductance calcium-activated K(+) channel blocker) combined with a subeffective dose of hesperidin (0.01 mg/kg, intraperitoneally [i.p.]) was able to produce a synergistic antidepressant-like effect in the mice TST. Moreover, the antidepressant-like effect elicited by an effective dose of hesperidin (0.3 mg/kg, i.p.) in TST was abolished by the treatment of mice with pharmacological compounds K(+) channel openers (cromakalim and minoxidil). Results showed that the antidepressant-like effect of hesperidin in TST may involve, at least in part, the modulation of neuronal excitability through inhibition of K(+) channels and may act through a mechanism dependent on the inhibition of L-arginine-NO pathway.
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Affiliation(s)
- Franciele Donato
- Laboratory of Pharmacological and Toxicological Assessments Applied to Bioactive Molecules, LaftamBio Pampa, Federal University of Pampa , Itaqui, Rio Grande do Sul, Brazil
| | - Carlos Borges Filho
- Laboratory of Pharmacological and Toxicological Assessments Applied to Bioactive Molecules, LaftamBio Pampa, Federal University of Pampa , Itaqui, Rio Grande do Sul, Brazil
| | - Renata Giacomeli
- Laboratory of Pharmacological and Toxicological Assessments Applied to Bioactive Molecules, LaftamBio Pampa, Federal University of Pampa , Itaqui, Rio Grande do Sul, Brazil
| | - Elza Eliza Tenório Alvater
- Laboratory of Pharmacological and Toxicological Assessments Applied to Bioactive Molecules, LaftamBio Pampa, Federal University of Pampa , Itaqui, Rio Grande do Sul, Brazil
| | - Lucian Del Fabbro
- Laboratory of Pharmacological and Toxicological Assessments Applied to Bioactive Molecules, LaftamBio Pampa, Federal University of Pampa , Itaqui, Rio Grande do Sul, Brazil
| | - Michele da Silva Antunes
- Laboratory of Pharmacological and Toxicological Assessments Applied to Bioactive Molecules, LaftamBio Pampa, Federal University of Pampa , Itaqui, Rio Grande do Sul, Brazil
| | - Marcelo Gomes de Gomes
- Laboratory of Pharmacological and Toxicological Assessments Applied to Bioactive Molecules, LaftamBio Pampa, Federal University of Pampa , Itaqui, Rio Grande do Sul, Brazil
| | - André Tiago Rossito Goes
- Laboratory of Pharmacological and Toxicological Assessments Applied to Bioactive Molecules, LaftamBio Pampa, Federal University of Pampa , Itaqui, Rio Grande do Sul, Brazil
| | - Leandro Cattelan Souza
- Laboratory of Pharmacological and Toxicological Assessments Applied to Bioactive Molecules, LaftamBio Pampa, Federal University of Pampa , Itaqui, Rio Grande do Sul, Brazil
| | - Silvana Peterini Boeira
- Laboratory of Pharmacological and Toxicological Assessments Applied to Bioactive Molecules, LaftamBio Pampa, Federal University of Pampa , Itaqui, Rio Grande do Sul, Brazil
| | - Cristiano Ricardo Jesse
- Laboratory of Pharmacological and Toxicological Assessments Applied to Bioactive Molecules, LaftamBio Pampa, Federal University of Pampa , Itaqui, Rio Grande do Sul, Brazil
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Sanchez J, Ghelani S, Otto-Meyer S. From development to disease: Diverse functions of NMDA-type glutamate receptors in the lower auditory pathway. Neuroscience 2015; 285:248-59. [DOI: 10.1016/j.neuroscience.2014.11.027] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2014] [Revised: 11/07/2014] [Accepted: 11/16/2014] [Indexed: 01/19/2023]
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TAKAHASHI T. Strength and precision of neurotransmission at mammalian presynaptic terminals. PROCEEDINGS OF THE JAPAN ACADEMY. SERIES B, PHYSICAL AND BIOLOGICAL SCIENCES 2015; 91:305-320. [PMID: 26194855 PMCID: PMC4631896 DOI: 10.2183/pjab.91.305] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2015] [Accepted: 05/06/2015] [Indexed: 05/30/2023]
Abstract
Classically, the basic concept of chemical synaptic transmission was established at the frog neuromuscular junction, and direct intracellular recordings from presynaptic terminals at the squid giant presynaptic terminal have further clarified principles of neurotransmitter release. More recently, whole-cell patch-camp recordings from the calyx of Held in rodent brainstem slices have extended the classical concept to mammalian synapses providing new insights into the mechanisms underlying strength and precision of neurotransmission and developmental changes therein. This review summarizes findings from our laboratory and others on these subjects, mainly at the calyx of Held, with a particular focus on precise, high-fidelity, fast neurotransmission. The mechanisms by which presynaptic terminals acquire strong, precise neurotransmission during postnatal development are also discussed.
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Affiliation(s)
- Tomoyuki TAKAHASHI
- Cellular and Molecular Synaptic Function Unit, Okinawa Institute of Science and Technology Graduate University, Okinawa, Japan
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73
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González-Forero D, Moreno-López B. Retrograde response in axotomized motoneurons: nitric oxide as a key player in triggering reversion toward a dedifferentiated phenotype. Neuroscience 2014; 283:138-65. [PMID: 25168733 DOI: 10.1016/j.neuroscience.2014.08.021] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2014] [Revised: 08/03/2014] [Accepted: 08/14/2014] [Indexed: 12/11/2022]
Abstract
The adult brain retains a considerable capacity to functionally reorganize its circuits, which mainly relies on the prevalence of three basic processes that confer plastic potential: synaptic plasticity, plastic changes in intrinsic excitability and, in certain central nervous system (CNS) regions, also neurogenesis. Experimental models of peripheral nerve injury have provided a useful paradigm for studying injury-induced mechanisms of central plasticity. In particular, axotomy of somatic motoneurons triggers a robust retrograde reaction in the CNS, characterized by the expression of plastic changes affecting motoneurons, their synaptic inputs and surrounding glia. Axotomized motoneurons undergo a reprograming of their gene expression and biosynthetic machineries which produce cell components required for axonal regrowth and lead them to resume a functionally dedifferentiated phenotype characterized by the removal of afferent synaptic contacts, atrophy of dendritic arbors and an enhanced somato-dendritic excitability. Although experimental research has provided valuable clues to unravel many basic aspects of this central response, we are still lacking detailed information on the cellular/molecular mechanisms underlying its expression. It becomes clear, however, that the state-switch must be orchestrated by motoneuron-derived signals produced under the direction of the re-activated growth program. Our group has identified the highly reactive gas nitric oxide (NO) as one of these signals, by providing robust evidence for its key role to induce synapse elimination and increases in intrinsic excitability following motor axon damage. We have elucidated operational principles of the NO-triggered downstream transduction pathways mediating each of these changes. Our findings further demonstrate that de novo NO synthesis is not only "necessary" but also "sufficient" to promote the expression of at least some of the features that reflect reversion toward a dedifferentiated state in axotomized adult motoneurons.
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Affiliation(s)
- D González-Forero
- Grupo de Neurodegeneración y Neuroreparación (GRUNEDERE), Área de Fisiología, Instituto de Biomoléculas (INBIO), Facultad de Medicina, Universidad de Cádiz, Cádiz, Spain.
| | - B Moreno-López
- Grupo de Neurodegeneración y Neuroreparación (GRUNEDERE), Área de Fisiología, Instituto de Biomoléculas (INBIO), Facultad de Medicina, Universidad de Cádiz, Cádiz, Spain.
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74
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Role of nitric oxide in the regulation of motor function. An overview of behavioral, biochemical and histological studies in animal models. Pharmacol Rep 2014; 65:1043-55. [PMID: 24399702 DOI: 10.1016/s1734-1140(13)71464-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2013] [Revised: 07/27/2013] [Indexed: 12/17/2022]
Abstract
A compelling body of evidence suggests that nitric oxide (NO), a unique gaseous neurotransmitter and neuromodulator plays a key role in the regulation of motor function. Recently, the interest of researchers concentrates on the NO - soluble guanylyl cyclase (sGC) - cyclic GMP (cGMP) signaling pathway in the striatum as a new target for the treatment of Parkinson's disease (PD). The aim of the study is to review the available literature referring to the role of NO in the integration of basal ganglia functions. First, attention has been focused on behavioral effects of NO donors and neuronal nitric oxide synthase (nNOS) inhibitors in the modulation of motor behavior. Then, disturbances in the nitrergic neurotransmission in PD and its 6-OHDA animal model have been presented. Moreover, the most current data demonstrating the contribution of both dopamine and glutamate to the regulation of NO biosynthesis in the striatum have been analyzed. Finally, the role of NO in the tonic and phasic dopamine release as well as in the regulation of striatal output pathways also has been discussed.
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75
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Lourenço CF, Santos RM, Barbosa RM, Cadenas E, Radi R, Laranjinha J. Neurovascular coupling in hippocampus is mediated via diffusion by neuronal-derived nitric oxide. Free Radic Biol Med 2014; 73:421-9. [PMID: 24887095 DOI: 10.1016/j.freeradbiomed.2014.05.021] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/12/2014] [Revised: 05/19/2014] [Accepted: 05/23/2014] [Indexed: 02/08/2023]
Abstract
The coupling between neuronal activity and cerebral blood flow (CBF) is essential for normal brain function. The mechanisms behind this neurovascular coupling process remain elusive, mainly because of difficulties in probing dynamically the functional and coordinated interaction between neurons and the vasculature in vivo. Direct and simultaneous measurements of nitric oxide (NO) dynamics and CBF changes in hippocampus in vivo support the notion that during glutamatergic activation nNOS-derived NO induces a time-, space-, and amplitude-coupled increase in the local CBF, later followed by a transient increase in local O2 tension. These events are dependent on the activation of the NMDA-glutamate receptor and nNOS, without a significant contribution of endothelial-derived NO or astrocyte-neuron signaling pathways. Upon diffusion of NO from active neurons, the vascular response encompasses the activation of soluble guanylate cyclase. Hence, in the hippocampus, neurovascular coupling is mediated by nNOS-derived NO via a diffusional connection between active glutamatergic neurons and blood vessels.
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Affiliation(s)
- Cátia F Lourenço
- Faculty of Pharmacy and Center for Neurosciences and Cell Biology, University of Coimbra, Health Sciences Campus, 3000-548 Coimbra, Portugal
| | - Ricardo M Santos
- Faculty of Pharmacy and Center for Neurosciences and Cell Biology, University of Coimbra, Health Sciences Campus, 3000-548 Coimbra, Portugal
| | - Rui M Barbosa
- Faculty of Pharmacy and Center for Neurosciences and Cell Biology, University of Coimbra, Health Sciences Campus, 3000-548 Coimbra, Portugal
| | - Enrique Cadenas
- Department of Pharmacology and Pharmaceutical Sciences, School of Pharmacy, University of Southern California, Los Angeles, CA 90089, USA
| | - Rafael Radi
- Department of Biochemistry and Center for Free Radical and Biomedical Research, Facultad de Medicina, Universidad de la Republica, Montevideo, Uruguay
| | - João Laranjinha
- Faculty of Pharmacy and Center for Neurosciences and Cell Biology, University of Coimbra, Health Sciences Campus, 3000-548 Coimbra, Portugal.
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76
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Michel CB, Hennig MH, Graham BP. Nitric oxide activity-dependent regulator compensates synaptic depression and enhances metabolic efficiency in the auditory brainstem. BMC Neurosci 2014. [PMCID: PMC4125072 DOI: 10.1186/1471-2202-15-s1-p154] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
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77
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Yassin L, Radtke-Schuller S, Asraf H, Grothe B, Hershfinkel M, Forsythe ID, Kopp-Scheinpflug C. Nitric oxide signaling modulates synaptic inhibition in the superior paraolivary nucleus (SPN) via cGMP-dependent suppression of KCC2. Front Neural Circuits 2014; 8:65. [PMID: 24987336 PMCID: PMC4060731 DOI: 10.3389/fncir.2014.00065] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2014] [Accepted: 05/28/2014] [Indexed: 11/13/2022] Open
Abstract
Glycinergic inhibition plays a central role in the auditory brainstem circuitries involved in sound localization and in the encoding of temporal action potential firing patterns. Modulation of this inhibition has the potential to fine-tune information processing in these networks. Here we show that nitric oxide (NO) signaling in the auditory brainstem (where activity-dependent generation of NO is documented) modulates the strength of inhibition by changing the chloride equilibrium potential. Recent evidence demonstrates that large inhibitory postsynaptic currents (IPSCs) in neurons of the superior paraolivary nucleus (SPN) are enhanced by a very low intracellular chloride concentration, generated by the neuronal potassium chloride co-transporter (KCC2) expressed in the postsynaptic neurons. Our data show that modulation by NO caused a 15 mV depolarizing shift of the IPSC reversal potential, reducing the strength of inhibition in SPN neurons, without changing the threshold for action potential firing. Regulating inhibitory strength, through cGMP-dependent changes in the efficacy of KCC2 in the target neuron provides a postsynaptic mechanism for rapidly controlling the inhibitory drive, without altering the timing or pattern of the afferent spike train. Therefore, this NO-mediated suppression of KCC2 can modulate inhibition in one target nucleus (SPN), without influencing inhibitory strength of other target nuclei (MSO, LSO) even though they are each receiving collaterals from the same afferent nucleus (a projection from the medial nucleus of the trapezoid body, MNTB).
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Affiliation(s)
- Lina Yassin
- Division of Neurobiology, Department Biology II, Ludwig-Maximilians-University MunichPlanegg-Martinsried, Germany
| | - Susanne Radtke-Schuller
- Division of Neurobiology, Department Biology II, Ludwig-Maximilians-University MunichPlanegg-Martinsried, Germany
| | - Hila Asraf
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the NegevBeer-Sheva, Israel
| | - Benedikt Grothe
- Division of Neurobiology, Department Biology II, Ludwig-Maximilians-University MunichPlanegg-Martinsried, Germany
| | - Michal Hershfinkel
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the NegevBeer-Sheva, Israel
| | - Ian D. Forsythe
- Department of Cell Physiology and Pharmacology, University of LeicesterLeicester, UK
| | - Cornelia Kopp-Scheinpflug
- Division of Neurobiology, Department Biology II, Ludwig-Maximilians-University MunichPlanegg-Martinsried, Germany
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78
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Foster JD, Dunford C, Sillar KT, Miles GB. Nitric oxide-mediated modulation of the murine locomotor network. J Neurophysiol 2013; 111:659-74. [PMID: 24259545 PMCID: PMC3921400 DOI: 10.1152/jn.00378.2013] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Spinal motor control networks are regulated by neuromodulatory systems to allow adaptability of movements. The present study aimed to elucidate the role of nitric oxide (NO) in the modulation of mammalian spinal locomotor networks. This was investigated with isolated spinal cord preparations from neonatal mice in which rhythmic locomotor-related activity was induced pharmacologically. Bath application of the NO donor diethylamine NONOate (DEA/NO) decreased the frequency and modulated the amplitude of locomotor-related activity recorded from ventral roots. Removal of endogenous NO with coapplication of a NO scavenger (PTIO) and a nitric oxide synthase (NOS) blocker [nitro-l-arginine methyl ester (l-NAME)] increased the frequency and decreased the amplitude of locomotor-related activity. This demonstrates that endogenously derived NO can modulate both the timing and intensity of locomotor-related activity. The effects of DEA/NO were mimicked by the cGMP analog 8-bromo-cGMP. In addition, the soluble guanylyl cyclase (sGC) inhibitor ODQ blocked the effects of DEA/NO on burst amplitude and frequency, although the frequency effect was only blocked at low concentrations of DEA/NO. This suggests that NO-mediated modulation involves cGMP-dependent pathways. Sources of NO were studied within the lumbar spinal cord during postnatal development (postnatal days 1–12) with NADPH-diaphorase staining. NOS-positive cells in the ventral horn exhibited a rostrocaudal gradient, with more cells in rostral segments. The number of NOS-positive cells was also found to increase during postnatal development. In summary, we have shown that NO, derived from sources within the mammalian spinal cord, modulates the output of spinal motor networks and is therefore likely to contribute to the fine-tuning of locomotor behavior.
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Affiliation(s)
- Joshua D Foster
- School of Psychology and Neuroscience, University of St Andrews, St Andrews, Fife, United Kingdom
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79
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Zhong LR, Estes S, Artinian L, Rehder V. Nitric oxide regulates neuronal activity via calcium-activated potassium channels. PLoS One 2013; 8:e78727. [PMID: 24236040 PMCID: PMC3827272 DOI: 10.1371/journal.pone.0078727] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2013] [Accepted: 09/22/2013] [Indexed: 12/13/2022] Open
Abstract
Nitric oxide (NO) is an unconventional membrane-permeable messenger molecule that has been shown to play various roles in the nervous system. How NO modulates ion channels to affect neuronal functions is not well understood. In gastropods, NO has been implicated in regulating the feeding motor program. The buccal motoneuron, B19, of the freshwater pond snail Helisoma trivolvis is active during the hyper-retraction phase of the feeding motor program and is located in the vicinity of NO-producing neurons in the buccal ganglion. Here, we asked whether B19 neurons might serve as direct targets of NO signaling. Previous work established NO as a key regulator of growth cone motility and neuronal excitability in another buccal neuron involved in feeding, the B5 neuron. This raised the question whether NO might modulate the electrical activity and neuronal excitability of B19 neurons as well, and if so whether NO acted on the same or a different set of ion channels in both neurons. To study specific responses of NO on B19 neurons and to eliminate indirect effects contributed by other cells, the majority of experiments were performed on single cultured B19 neurons. Addition of NO donors caused a prolonged depolarization of the membrane potential and an increase in neuronal excitability. The effects of NO could mainly be attributed to the inhibition of two types of calcium-activated potassium channels, apamin-sensitive and iberiotoxin-sensitive potassium channels. NO was found to also cause a depolarization in B19 neurons in situ, but only after NO synthase activity in buccal ganglia had been blocked. The results suggest that NO acts as a critical modulator of neuronal excitability in B19 neurons, and that calcium-activated potassium channels may serve as a common target of NO in neurons.
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Affiliation(s)
- Lei Ray Zhong
- Biology Department, Georgia State University, Atlanta, Georgia, United States of America
| | - Stephen Estes
- Biology Department, Georgia State University, Atlanta, Georgia, United States of America
| | - Liana Artinian
- Biology Department, Georgia State University, Atlanta, Georgia, United States of America
| | - Vincent Rehder
- Biology Department, Georgia State University, Atlanta, Georgia, United States of America
- * E-mail:
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80
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Hardingham N, Dachtler J, Fox K. The role of nitric oxide in pre-synaptic plasticity and homeostasis. Front Cell Neurosci 2013; 7:190. [PMID: 24198758 PMCID: PMC3813972 DOI: 10.3389/fncel.2013.00190] [Citation(s) in RCA: 164] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2013] [Accepted: 10/05/2013] [Indexed: 11/13/2022] Open
Abstract
Since the observation that nitric oxide (NO) can act as an intercellular messenger in the brain, the past 25 years have witnessed the steady accumulation of evidence that it acts pre-synaptically at both glutamatergic and GABAergic synapses to alter release-probability in synaptic plasticity. NO does so by acting on the synaptic machinery involved in transmitter release and, in a coordinated fashion, on vesicular recycling mechanisms. In this review, we examine the body of evidence for NO acting as a retrograde factor at synapses, and the evidence from in vivo and in vitro studies that specifically establish NOS1 (neuronal nitric oxide synthase) as the important isoform of NO synthase in this process. The NOS1 isoform is found at two very different locations and at two different spatial scales both in the cortex and hippocampus. On the one hand it is located diffusely in the cytoplasm of a small population of GABAergic neurons and on the other hand the alpha isoform is located discretely at the post-synaptic density (PSD) in spines of pyramidal cells. The present evidence is that the number of NOS1 molecules that exist at the PSD are so low that a spine can only give rise to modest concentrations of NO and therefore only exert a very local action. The NO receptor guanylate cyclase is located both pre- and post-synaptically and this suggests a role for NO in the coordination of local pre- and post-synaptic function during plasticity at individual synapses. Recent evidence shows that NOS1 is also located post-synaptic to GABAergic synapses and plays a pre-synaptic role in GABAergic plasticity as well as glutamatergic plasticity. Studies on the function of NO in plasticity at the cellular level are corroborated by evidence that NO is also involved in experience-dependent plasticity in the cerebral cortex.
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Affiliation(s)
| | | | - Kevin Fox
- School of Biosciences, Cardiff UniversityCardiff, UK
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81
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Nitric oxide mediates local activity-dependent excitatory synapse development. Proc Natl Acad Sci U S A 2013; 110:E4142-51. [PMID: 24127602 DOI: 10.1073/pnas.1311927110] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Learning related paradigms play an important role in shaping the development and specificity of synaptic networks, notably by regulating mechanisms of spine growth and pruning. The molecular events underlying these synaptic rearrangements remain poorly understood. Here we identify NO signaling as a key mediator of activity-dependent excitatory synapse development. We find that chronic blockade of NO production in vitro and in vivo interferes with the development of hippocampal and cortical excitatory spine synapses. The effect results from a selective loss of activity-mediated spine growth mechanisms and is associated with morphological and functional alterations of remaining synapses. These effects of NO are mediated by a cGMP cascade and can be reproduced or prevented by postsynaptic expression of vasodilator-stimulated phosphoprotein phospho-mimetic or phospho-resistant mutants. In vivo analyses show that absence of NO prevents the increase in excitatory synapse density induced by environmental enrichment and interferes with the formation of local clusters of excitatory synapses. We conclude that NO plays an important role in regulating the development of excitatory synapses by promoting local activity-dependent spine-growth mechanisms.
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82
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Pigott B, Bartus K, Garthwaite J. On the selectivity of neuronal NOS inhibitors. Br J Pharmacol 2013; 168:1255-65. [PMID: 23072468 PMCID: PMC3594681 DOI: 10.1111/bph.12016] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2012] [Revised: 09/07/2012] [Accepted: 09/30/2012] [Indexed: 12/16/2022] Open
Abstract
Background and Purpose Isoform-selective inhibitors of NOS enzymes are desirable as research tools and for potential therapeutic purposes. Vinyl-l-N-5-(1-imino-3-butenyl)-l-ornithine (l-VNIO) and Nω-propyl-l-arginine (NPA) purportedly have good selectivity for neuronal over endothelial NOS under cell-free conditions, as does N-[(3-aminomethyl)benzyl]acetamidine (1400W), which is primarily an inducible NOS inhibitor. Although used in numerous investigations in vitro and in vivo, there have been surprisingly few tests of the potency and selectivity of these compounds in cells. This study addresses this deficiency and evaluates the activity of new and potentially better pyrrolidine-based compounds. Experimental Approach The inhibitors were evaluated by measuring their effect on NMDA-evoked cGMP accumulation in rodent hippocampal slices, a response dependent on neuronal NOS, and ACh-evoked cGMP synthesis in aortic rings of the same animals, an endothelial NOS-dependent phenomenon. Key Results l-VNIO, NPA and 1400W inhibited responses in both tissues but all showed less than fivefold higher potency in the hippocampus than in the aorta, implying useless selectivity for neuronal over endothelial NOS at the tissue level. In addition, the inhibitors had a 25-fold lower potency in the hippocampus than reported previously, the IC50 values being approximately 1 μM for l-VNIO and NPA, and 150 μM for 1400W. Pyrrolidine-based inhibitors were similarly weak and nonselective. Conclusion and Implications The results suggest that l-VNIO, NPA and 1400W, as well as the newer pyrrolidine-type inhibitors, cannot be used as neuronal NOS inhibitors in cells without stringent verification. The identification of inhibitors with useable selectivity in cells and tissues remains an important goal.
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Affiliation(s)
- B Pigott
- Wolfson Institute for Biomedical Research, University College London, London, UK
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83
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Protection from noise-induced hearing loss by Kv2.2 potassium currents in the central medial olivocochlear system. J Neurosci 2013; 33:9113-21. [PMID: 23699522 DOI: 10.1523/jneurosci.5043-12.2013] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
The central auditory brainstem provides an efferent projection known as the medial olivocochlear (MOC) system, which regulates the cochlear amplifier and mediates protection on exposure to loud sound. It arises from neurons of the ventral nucleus of the trapezoid body (VNTB), so control of neuronal excitability in this pathway has profound effects on hearing. The VNTB and the medial nucleus of the trapezoid body are the only sites of expression for the Kv2.2 voltage-gated potassium channel in the auditory brainstem, consistent with a specialized function of these channels. In the absence of unambiguous antagonists, we used recombinant and transgenic methods to examine how Kv2.2 contributes to MOC efferent function. Viral gene transfer of dominant-negative Kv2.2 in wild-type mice suppressed outward K(+) currents, increasing action potential (AP) half-width and reducing repetitive firing. Similarly, VNTB neurons from Kv2.2 knock-out mice (Kv2.2KO) also showed increased AP duration. Control experiments established that Kv2.2 was not expressed in the cochlea, so any changes in auditory function in the Kv2.2KO mouse must be of central origin. Further, in vivo recordings of auditory brainstem responses revealed that these Kv2.2KO mice were more susceptible to noise-induced hearing loss. We conclude that Kv2.2 regulates neuronal excitability in these brainstem nuclei by maintaining short APs and enhancing high-frequency firing. This safeguards efferent MOC firing during high-intensity sounds and is crucial in the mediation of protection after auditory overexposure.
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84
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Goyal RK, Chaudhury A. Structure activity relationship of synaptic and junctional neurotransmission. Auton Neurosci 2013; 176:11-31. [PMID: 23535140 PMCID: PMC3677731 DOI: 10.1016/j.autneu.2013.02.012] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2009] [Revised: 12/28/2012] [Accepted: 02/18/2013] [Indexed: 12/18/2022]
Abstract
Chemical neurotransmission may include transmission to local or remote sites. Locally, contact between 'bare' portions of the bulbous nerve terminal termed a varicosity and the effector cell may be in the form of either synapse or non-synaptic contact. Traditionally, all local transmissions between nerves and effector cells are considered synaptic in nature. This is particularly true for communication between neurons. However, communication between nerves and other effectors such as smooth muscles has been described as nonsynaptic or junctional in nature. Nonsynaptic neurotransmission is now also increasingly recognized in the CNS. This review focuses on the relationship between structure and function that orchestrate synaptic and junctional neurotransmissions. A synapse is a specialized focal contact between the presynaptic active zone capable of ultrafast release of soluble transmitters and the postsynaptic density that cluster ionotropic receptors. The presynaptic and the postsynaptic areas are separated by the 'closed' synaptic cavity. The physiological hallmark of the synapse is ultrafast postsynaptic potentials lasting milliseconds. In contrast, junctions are juxtapositions of nerve terminals and the effector cells without clear synaptic specializations and the junctional space is 'open' to the extracellular space. Based on the nature of the transmitters, postjunctional receptors and their separation from the release sites, the junctions can be divided into 'close' and 'wide' junctions. Functionally, the 'close' and the 'wide' junctions can be distinguished by postjunctional potentials lasting ~1s and tens of seconds, respectively. Both synaptic and junctional communications are common between neurons; however, junctional transmission is the rule at many neuro-non-neural effectors.
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Affiliation(s)
- Raj K Goyal
- Center for Swallowing and Motility Disorders, GI Division, VA Boston Healthcare System and Harvard Medical School, Boston, USA.
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85
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Abstract
Synaptic transmission is highly dependent on recent activity and can lead to depression or facilitation of synaptic strength. This phenomenon is called "short-term synaptic plasticity" and is shown at all synapses. While much work has been done to understand the mechanisms of short-term changes in the state of synapses, short-term plasticity is often thought of as a mechanistic consequence of the design of a synapse. This review will attempt to go beyond this view and discuss how, on one hand, complex neuronal activity affects the short-term state of synapses, but also how these dynamic changes in synaptic strength affect information processing in return.
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86
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Tricoire L, Vitalis T. Neuronal nitric oxide synthase expressing neurons: a journey from birth to neuronal circuits. Front Neural Circuits 2012; 6:82. [PMID: 23227003 PMCID: PMC3514612 DOI: 10.3389/fncir.2012.00082] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2012] [Accepted: 10/25/2012] [Indexed: 12/17/2022] Open
Abstract
Nitric oxide (NO) is an important signaling molecule crucial for many physiological processes such as synaptic plasticity, vasomotricity, and inflammation. Neuronal nitric oxide synthase (nNOS) is the enzyme responsible for the synthesis of NO by neurons. In the juvenile and mature hippocampus and neocortex nNOS is primarily expressed by subpopulations of GABAergic interneurons. Over the past two decades, many advances have been achieved in the characterization of neocortical and hippocampal nNOS expressing neurons. In this review, we summarize past and present studies that have characterized the electrophysiological, morphological, molecular, and synaptic properties of these neurons. We also discuss recent studies that have shed light on the developmental origins and specification of GABAergic neurons with specific attention to neocortical and hippocampal nNOS expressing GABAergic neurons. Finally, we summarize the roles of NO and nNOS-expressing inhibitory neurons.
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Affiliation(s)
- Ludovic Tricoire
- CNRS-UMR 7102, Laboratoire de Neurobiologie des Processus Adaptatifs, Université Pierre et Marie Curie Paris, France
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87
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Borsani E, Giovannozzi S, Cocchi MA, Boninsegna R, Rezzani R, Rodella LF. Endothelial nitric oxide synthase in dorsal root ganglia during chronic inflammatory nociception. Cells Tissues Organs 2012; 197:159-68. [PMID: 23095572 DOI: 10.1159/000342518] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/09/2012] [Indexed: 11/19/2022] Open
Abstract
Nitric oxide (NO) is a gaseous molecule implicated both in vascular tone and nociceptive transmission. The capillary blood supply to the dorsal root ganglia (DRG) is unique because it is highly permeable to several low and high molecular-weight compounds. This anatomical situation leads to a potential role of endothelial nitric oxide synthase (eNOS) in inflammatory nociception, which is not well established. Therefore, we examined the role of eNOS in DRG in a murine chronic inflammatory pain model induced by complete Freund's adjuvant using L-N(5)-(1-iminoethyl)ornithine (L-NIO), a potent inhibitor of eNOS activity. Pain state was examined using a behavioral test. The expression of eNOS, platelet endothelial cell adhesion molecule-1 (CD31) and vascular endothelial growth factor (VEGF) was examined by immunofluorescence. In control animals, CD31 was detected in vessels; VEGF was localized both in vessels and neurons while a weak eNOS immunopositivity was detected in both vessels and in neurons. Under inflammatory pain conditions, eNOS, CD31 and VEGF immunopositivity increased. Administration of L-NIO significantly attenuated thermal hyperalgesia by 24 h and decreased eNOS activity and CD31 immunopositivity by 7 days. VEGF was unaffected. Our results show that eNOS plays a nociceptive role in the early phases of inflammation while in the later phases it may be involved in neurotrophic support.
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Affiliation(s)
- Elisa Borsani
- Department of Biomedical Sciences and Biotechnologies, Division of Human Anatomy, University of Brescia, Brescia, Italy
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88
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Mitkovski M, Padovan-Neto FE, Raisman-Vozari R, Ginestet L, da-Silva CA, Del-Bel EA. Investigations into Potential Extrasynaptic Communication between the Dopaminergic and Nitrergic Systems. Front Physiol 2012; 3:372. [PMID: 23055978 PMCID: PMC3457048 DOI: 10.3389/fphys.2012.00372] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2012] [Accepted: 08/29/2012] [Indexed: 12/21/2022] Open
Abstract
Nitric oxide is unconstrained by cell membranes and can therefore act along a broad distance as a volume transmitter. Spillover of nitric oxide between neurons may have a major impact on central nervous system diseases and particularly on neurodegeneration. There is evidence whereby communication between nitrergic and dopaminergic systems plays an essential role in the control of the nigrostriatal pathway. However, there is sparse information for either the coexistence or overlap of nitric oxide and dopaminergic structures. The dual localization of immunoreactivity for nitric oxide synthase (NOS) and tyrosine hydroxylase, enzymes responsible for the synthesis of nitric oxide and dopamine, respectively, was examined in neurons of the nigrostriatal pathway in the rat brain by means of a double-immunohistochemical method and confocal laser scanning microscopy, acquired at the resolution limit. After perfusional fixation, the brains were cut and double-immunostained. A proximity analysis of tyrosine hydroxylase and NOS structures was done using binary masks generated from the respective maximum projections, using confocal laser microscopy. Unrevealed regions were determined somatodendritic positive for both NOS and tyrosine hydroxylase, within an image limit resolution at 2 μm-wide margin. The described interconnected localization of nNOS(+) and TH(+) containing neuronal fibers and cells bodies in the nigrostriatal pathway propose a close anatomical link between the two neurotransmitters.
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Affiliation(s)
- M Mitkovski
- Light Microscopy Facility, Max-Planck-Institute of Experimental Medicine Göttingen, Germany
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89
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Artinian L, Zhong L, Yang H, Rehder V. Nitric oxide as intracellular modulator: internal production of NO increases neuronal excitability via modulation of several ionic conductances. Eur J Neurosci 2012; 36:3333-43. [PMID: 22913584 DOI: 10.1111/j.1460-9568.2012.08260.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Nitric oxide (NO) has been shown to regulate neuronal excitability in the nervous system, but little is known as to whether NO, which is synthesized in certain neurons, also serves functional roles within NO-producing neurons themselves. We investigated this possibility by using a nitric oxide synthase (NOS)-expressing neuron, and studied the role of intrinsic NO production on neuronal firing properties in single-cell culture. B5 neurons of the pond snail Helisoma trivolvis fire spontaneous action potentials (APs), but once the intrinsic activity of NOS was inhibited, neurons became hyperpolarized and were unable to fire evoked APs. These striking long-term effects could be attributed to intrinsic NO acting on three types of conductances, a persistent sodium current (I(NaP) ), voltage-gated Ca currents (I(Ca) ) and small-conductance calcium-activated potassium (SK) channels. We show that NOS inhibitors 7-nitroindazole and S-methyl-l-thiocitrulline resulted in a decrease in I(NaP) , and that their hyperpolarizing and inhibiting effects on spontaneous spiking were mimicked by the inhibitor of I(NaP) , riluzole. Moreover, inhibition of NOS, soluble guanylate cyclase (sGC) or protein kinase G (PKG) attenuated I(Ca) , and blocked spontaneous and depolarization-induced spiking, suggesting that intrinsic NO controlled I(Ca) via the sGC/PKG pathway. The SK channel inhibitor apamin partially prevented the hyperpolarization observed after inhibition of NOS, suggesting a downregulation of SK channels by intrinsic NO. Taken together, we describe a novel mechanism by which neurons utilize their self-produced NO as an intrinsic modulator of neuronal excitability. In B5 neurons, intrinsic NO production is necessary to maintain spontaneous tonic and evoked spiking activity.
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Affiliation(s)
- Liana Artinian
- Department of Biology, Georgia State University, Atlanta, GA 30302-4010, USA
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90
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Higgins M, Miller M, Nighorn A. Nitric oxide has differential effects on currents in different subsets of Manduca sexta antennal lobe neurons. PLoS One 2012; 7:e42556. [PMID: 22880032 PMCID: PMC3411793 DOI: 10.1371/journal.pone.0042556] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2012] [Accepted: 07/10/2012] [Indexed: 12/15/2022] Open
Abstract
Nitric oxide has been shown to regulate many biological systems including olfaction. In the moth olfactory system nitric oxide is produced in the antennal lobe in response to odor stimulation and has complex effects on the activity of both projection neurons and local interneurons. To examine the cell autonomous effects of nitric oxide on these cells, we used patch-clamp recording in conjunction with pharmacological manipulation of nitric oxide to test the hypothesis that nitric oxide differentially regulates the channel properties of these different antennal lobe neuron subsets. We found that nitric oxide caused increasing inward currents in a subset of projection neurons while the effects on local neurons were variable but consistent within identifiable morphological subtypes.
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Affiliation(s)
| | | | - Alan Nighorn
- Department of Neuroscience, University of Arizona, Tucson, Arizona, United States of America
- * E-mail:
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91
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Eguchi K, Nakanishi S, Takagi H, Taoufiq Z, Takahashi T. Maturation of a PKG-dependent retrograde mechanism for exoendocytic coupling of synaptic vesicles. Neuron 2012; 74:517-29. [PMID: 22578503 DOI: 10.1016/j.neuron.2012.03.028] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/09/2012] [Indexed: 12/24/2022]
Abstract
At presynaptic terminals vesicular membranes are fused into plasma membrane upon exocytosis and retrieved by endocytosis. During a sustained high-frequency transmission, exoendocytic coupling is critical for the maintenance of synaptic transmission. Here, we show that this homeostatic coupling is supported by cGMP-dependent protein kinase (PKG) at the calyx of Held. This mechanism starts to operate after hearing onset during the second postnatal week, when PKG expression becomes upregulated in the brainstem. Pharmacological tests with capacitance measurements revealed that presynaptic PKG activity is supported by a retrograde signal cascade mediated by NO that is released by activation of postsynaptic NMDA receptors. Activation of PKG also upregulates phosphatidylinositol-4,5-bisphosphate, thereby accelerating endocytosis. Furthermore, presynaptic PKG activity upregulates synaptic fidelity during high-frequency transmission. We conclude that maturation of the PKG-dependent retrograde signal cascade strengthens the homeostatic plasticity for the maintenance of high-frequency synaptic transmission at the fast glutamatergic synapse.
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Affiliation(s)
- Kohgaku Eguchi
- Cellular & Molecular Synaptic Function Unit, Okinawa Institute of Science and Technology Graduate University, Onna-son, Kunigami, Okinawa 904-0412, Japan.
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92
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Laranjinha J, Santos RM, Lourenço CF, Ledo A, Barbosa RM. Nitric oxide signaling in the brain: translation of dynamics into respiration control and neurovascular coupling. Ann N Y Acad Sci 2012; 1259:10-8. [DOI: 10.1111/j.1749-6632.2012.06582.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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93
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Nitric oxide as a regulator of behavior: new ideas from Aplysia feeding. Prog Neurobiol 2012; 97:304-17. [PMID: 22575157 DOI: 10.1016/j.pneurobio.2012.03.004] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2011] [Revised: 12/28/2011] [Accepted: 03/12/2012] [Indexed: 12/29/2022]
Abstract
Nitric oxide (NO) regulates Aplysia feeding by novel mechanisms, suggesting new roles for NO in controlling the behavior of higher animals. In Aplysia, (1) NO helps maintain arousal when produced by neurons responding to attempts to swallow food; (2) NO biases the motor system to reject and reposition food that resists swallowing; (3) if mechanically resistant food is not successfully swallowed, NO mediates the formation and expression of memories of food inedibility; (4) NO production at rest inhibits feeding, countering the effects of food stimuli exciting feeding. At a cellular level, NO-dependent channels contribute to the resting potential of neurons controlling food finding and food consumption. Increases in L-arginine after animals eat act as a post-feeding inhibitory signal, presumably by modulating NO production at rest. NO also signals non-feeding behaviors that are associated with feeding inhibition. Thus, depending on context, NO may enhance or inhibit feeding behavior. The different functions of NO may reflect the evolution of NO signaling from a response to tissue damage that was then elaborated and used for additional functions. These results suggest that in higher animals (1) elicited and background transmitter release may have similar effects; (2) NO may be produced by neurons without firing, influencing adjacent neurons; (3) background NO production may contribute to a neuron's resting potential; (4) circulating factors affecting background NO production may regulate spatially separated neurons; (5) L-arginine can be used to regulate neural activity; (6) L-arginine may be an effective post-ingestion metabolic signal to regulate feeding.
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94
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Abstract
The action potential generally begins in the axon initial segment (AIS), a principle confirmed by 60 years of research; however, the most recent advances have shown that a very rich biology underlies this simple observation. The AIS has a remarkably complex molecular composition, with a wide variety of ion channels and attendant mechanisms for channel localization, and may feature membrane domains each with distinct roles in excitation. Its function may be regulated in the short term through the action of neurotransmitters, in the long term through activity- and Ca(2+)-dependent processes. Thus, the AIS is not merely the beginning of the axon, but rather a key site in the control of neuronal excitability.
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Affiliation(s)
- Kevin J Bender
- Oregon Hearing Research Center and Vollum Institute, Oregon Health and Science University, Portland, Oregon 97239, USA.
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95
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Kaczmarek LK. Gradients and modulation of K(+) channels optimize temporal accuracy in networks of auditory neurons. PLoS Comput Biol 2012; 8:e1002424. [PMID: 22438799 PMCID: PMC3305353 DOI: 10.1371/journal.pcbi.1002424] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2011] [Accepted: 01/29/2012] [Indexed: 11/18/2022] Open
Abstract
Accurate timing of action potentials is required for neurons in auditory brainstem nuclei to encode the frequency and phase of incoming sound stimuli. Many such neurons express "high threshold" Kv3-family channels that are required for firing at high rates (> -200 Hz). Kv3 channels are expressed in gradients along the medial-lateral tonotopic axis of the nuclei. Numerical simulations of auditory brainstem neurons were used to calculate the input-output relations of ensembles of 1-50 neurons, stimulated at rates between 100-1500 Hz. Individual neurons with different levels of potassium currents differ in their ability to follow specific rates of stimulation but all perform poorly when the stimulus rate is greater than the maximal firing rate of the neurons. The temporal accuracy of the combined synaptic output of an ensemble is, however, enhanced by the presence of gradients in Kv3 channel levels over that measured when neurons express uniform levels of channels. Surprisingly, at high rates of stimulation, temporal accuracy is also enhanced by the occurrence of random spontaneous activity, such as is normally observed in the absence of sound stimulation. For any pattern of stimulation, however, greatest accuracy is observed when, in the presence of spontaneous activity, the levels of potassium conductance in all of the neurons is adjusted to that found in the subset of neurons that respond better than their neighbors. This optimization of response by adjusting the K(+) conductance occurs for stimulus patterns containing either single and or multiple frequencies in the phase-locking range. The findings suggest that gradients of channel expression are required for normal auditory processing and that changes in levels of potassium currents across the nuclei, by mechanisms such as protein phosphorylation and rapid changes in channel synthesis, adapt the nuclei to the ongoing auditory environment.
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Affiliation(s)
- Leonard K Kaczmarek
- Department of Pharmacology, Yale University School of Medicine, New Haven, Connecticut, USA.
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96
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Tozer AJB, Forsythe ID, Steinert JR. Nitric oxide signalling augments neuronal voltage-gated L-type (Ca(v)1) and P/q-type (Ca(v)2.1) channels in the mouse medial nucleus of the trapezoid body. PLoS One 2012; 7:e32256. [PMID: 22389692 PMCID: PMC3289649 DOI: 10.1371/journal.pone.0032256] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2011] [Accepted: 01/25/2012] [Indexed: 12/19/2022] Open
Abstract
Nitric Oxide (NO) is a diffusible second messenger that modulates ion channels, intrinsic excitability and mediates synaptic plasticity. In light of its activity-dependent generation in the principal neurons of the medial nucleus of the trapezoid body (MNTB), we have investigated its potential modulatory effects on native voltage-gated calcium channels (CaV) within this nucleus. Whole-cell patch recordings were made from brain slices from P13–15 CBA mice. Slices were incubated with the inhibitor of neuronal nitric oxide synthase (nNOS) 7-nitroindazole (10 µM) and pharmacological blockers used to isolate Ca2+ current subtypes. Unpaired observations in the presence and absence of the NO-donors sodium nitroprusside (SNP, 100 µM) or Diethyl-ammonium-nonoate (DEA, 100 µM) were made to elucidate NO-dependent modulation of the expressed CaV subtypes. A differential effect of NO on the calcium channel subtypes was observed: CaV1 and CaV2.1 (L+R- and P/Q+R-type) conductances were potentiated, whereas N+R-type (CaV2.2) and R-type (CaV2.3) current amplitudes were unaffected. L+R-type currents increased from 0.36±0.04 nA to 0.64±0.11 nA and P/Q+R-type from 0.55±0.09 nA to 0.94±0.05 nA, thereby changing the balance and relative contribution of each subtype to the whole cell calcium current. In addition, N+R-type half-activation voltage was left shifted following NO exposure. NO-dependent modulation of P/Q+R and N+R-type, but not L+R-type, channels was removed by inhibition of soluble guanylyl cyclase (sGC) activity. This data demonstrates a differential effect of NO signalling on voltage-gated calcium entry, by distinct NO-dependent pathways.
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Affiliation(s)
- Adam J. B. Tozer
- Neurotoxicity at the Synaptic Interface, MRC Toxicology Unit, University of Leicester, Leicester, United Kingdom
| | - Ian D. Forsythe
- Neurotoxicity at the Synaptic Interface, MRC Toxicology Unit, University of Leicester, Leicester, United Kingdom
| | - Joern R. Steinert
- Neurotoxicity at the Synaptic Interface, MRC Toxicology Unit, University of Leicester, Leicester, United Kingdom
- * E-mail:
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97
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Couchman K, Grothe B, Felmy F. Functional localization of neurotransmitter receptors and synaptic inputs to mature neurons of the medial superior olive. J Neurophysiol 2012; 107:1186-98. [DOI: 10.1152/jn.00586.2011] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Neurons of the medial superior olive (MSO) code for the azimuthal location of low-frequency sound sources via a binaural coincidence detection system operating on microsecond time scales. These neurons are morphologically simple and stereotyped, and anatomical studies have indicated a functional segregation of excitatory and inhibitory inputs between cellular compartments. It is thought that this morphological arrangement holds important implications for the computational task of these cells. To date, however, there has been no functional investigation into synaptic input sites or functional receptor distributions on mature neurons of the MSO. Here, functional neurotransmitter receptor maps for amino-3-hydroxyl-5-methyl-4-isoxazole propionate (AMPA), N-methyl-d-aspartate (NMDA), glycine (Gly), and ionotropic γ-aminobutyric acid (GABAA) receptors (Rs) were compared and complemented by their corresponding synaptic input map. We find in MSO neurons from postnatal day 20–35 gerbils that AMPARs and their excitatory inputs target the soma and dendrites. Functional GlyRs and their inhibitory inputs are predominantly refined to the somata, although a pool of functional GlyRs is present extrasynaptically on MSO dendrites. GABAAR responses are present throughout the cell but lack direct synaptic contact indicating an involvement in volume transmission. NMDARs are present both synaptically and extrasynaptically with an overall distribution similar to GlyRs. Interestingly, even at physiological temperatures these functional NMDARs can be potentiated by synaptically released Gly. The functional receptor and synaptic input maps produced here led to the identification of a cross talk between transmitter systems and raises the possibility that extrasynaptic receptors could be modulating leak conductances as a homeostatic mechanism.
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Affiliation(s)
- Kiri Couchman
- Division of Neurobiology, Department Biology II, Ludwig-Maximilians-Universität Munich, and
| | - Benedikt Grothe
- Division of Neurobiology, Department Biology II, Ludwig-Maximilians-Universität Munich, and
- Bernstein Centre for Computational Neuroscience Munich, Martinsried, Germany
| | - Felix Felmy
- Division of Neurobiology, Department Biology II, Ludwig-Maximilians-Universität Munich, and
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98
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99
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Neal AP, Stansfield KH, Guilarte TR. Enhanced nitric oxide production during lead (Pb²⁺) exposure recovers protein expression but not presynaptic localization of synaptic proteins in developing hippocampal neurons. Brain Res 2011; 1439:88-95. [PMID: 22265330 DOI: 10.1016/j.brainres.2011.12.037] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2011] [Revised: 11/28/2011] [Accepted: 12/17/2011] [Indexed: 01/17/2023]
Abstract
We have previously reported that lead (Pb(2+)) exposure results in both presynaptic and postsynaptic changes in developing neurons as a result of inhibition of the N-methyl-d-aspartate receptor (NMDAR). NMDAR inhibition by Pb(2+) during synaptogenesis disrupts downstream trans-synaptic signaling of brain-derived neurotrophic factor (BDNF) and exogenous addition of BDNF can recover the effects of Pb(2+) on both presynaptic protein expression and presynaptic vesicular release. NMDAR activity can modulate other trans-synaptic signaling pathways, such as nitric oxide (NO) signaling. Thus, it is possible that other trans-synaptic pathways in addition to BDNF signaling may be disrupted by Pb(2+) exposure. The current study investigated whether exogenous addition of NO could recover the presynaptic vesicular proteins lost as a result of Pb(2+) exposure during synaptogenesis, namely Synaptophysin (Syn) and Synaptobrevin (Syb). We observed that exogenous addition of NO during Pb(2+) exposure results in complete recovery of whole-cell Syn levels and partial recovery of Syn and Syb synaptic targeting in Pb(2+)-exposed neurons.
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Affiliation(s)
- April P Neal
- Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD, USA.
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100
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Abstract
The calyx of Held is an axosomatic terminal in the auditory brainstem that has attracted anatomists because of its giant size and physiologists because of its accessibility to patch-clamp recordings. The calyx allows the principal neurons in the medial nucleus of the trapezoid body (MNTB) to provide inhibition that is both well timed and sustained to many other auditory nuclei. The special adaptations that allow the calyx to drive its principal neuron even when frequencies are high include a large number of release sites with low release probability, a large readily releasable pool, fast presynaptic calcium clearance and little delayed release, a large quantal size, and fast AMPA-type glutamate receptors. The transformation from a synapse that is unremarkable except for its giant size into a fast and reliable auditory relay happens in just a few days. In rodents this transformation is essentially ready when hearing starts.
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Affiliation(s)
- J Gerard G Borst
- Department of Neuroscience, Erasmus MC, University Medical Center, 3015 GE Rotterdam, The Netherlands.
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