1
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Wong HTC, Drerup CM. Using fluorescent indicators for in vivo quantification of spontaneous or evoked motor neuron presynaptic activity in transgenic zebrafish. STAR Protoc 2022; 3:101766. [PMID: 36240058 PMCID: PMC9568885 DOI: 10.1016/j.xpro.2022.101766] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Revised: 08/22/2022] [Accepted: 09/20/2022] [Indexed: 11/07/2022] Open
Abstract
In this protocol, we describe steps that utilize the optical clarity of the zebrafish larvae and the stereotyped motor neuron axon structure in the trunk to measure spontaneous or evoked motor neuron axon activity. This activity is detected with transgenic fluorescent indicators introduced into the larvae by zygotic injection. Fluorescent indicator intensity changes in the small neuromuscular junctions are quantified to measure the presynaptic calcium activity and consequent synaptic vesicle release. For complete details on the use and execution of this protocol, please refer to Mandal et al. (2020).
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Affiliation(s)
- Hiu-tung Candy Wong
- Department of Integrative Biology, University of Wisconsin-Madison, Madison, WI 53706, USA,Corresponding author
| | - Catherine M. Drerup
- Department of Integrative Biology, University of Wisconsin-Madison, Madison, WI 53706, USA,Corresponding author
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2
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Hong X, Chen R, Zhang L, Yan L, Xin J, Li J, Zha J. Long-Term Exposure to SSRI Citalopram Induces Neurotoxic Effects in Zebrafish. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2022; 56:12380-12390. [PMID: 35985052 DOI: 10.1021/acs.est.2c01514] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Residual antidepressants are of increasing concern worldwide, yet critical information on their long-term neurotoxic impacts on nontarget aquatic animals is lacking. Here, we investigated the long-term effects (from 0 to 150 days postfertilization) of the selective serotonin reuptake inhibitor citalopram (0.1-100 μg/L) on motor function, learning, and memory in zebrafish over two generations and explored the reversibility of the effect in F1 larvae. Unlike F0+ larvae, we found that F1+ larvae displayed decreased sensorimotor performance when continuously exposed to citalopram at 100 μg/L. No adverse effects were found in F1- larvae after they were transferred to a clean medium. Whole-mount immunofluorescence assays suggested that the motor impairments were related to axonal projections of the spinal motor neurons (MNs). For F0+ adults, long-term citalopram exposure mainly caused male-specific declines in motor, learning, and memory performance. Analysis of serotonergic and cholinergic MNs revealed no significant changes in the male zebrafish spinal cord. In contrast, the number of glutamatergic spinal MNs decreased, likely associated with the impairment of motor function. Additionally, treatment with 100 μg/L citalopram significantly reduced the number of dopaminergic neurons, but no significant neuronal apoptosis was observed in the adult telencephalon. Overall, this study provides neurobehavioral evidence and novel insights into the neurotoxic mechanisms of long-term citalopram exposure and may facilitate the assessment of the environmental and health risks posed by citalopram-containing antidepressant drugs.
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Affiliation(s)
- Xiangsheng Hong
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
- State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
| | - Rui Chen
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
- State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
| | - Le Zhang
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Liang Yan
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jiajing Xin
- Department of Public Health, Shaanxi University of Chinese Medicine, Xianyang, Shaanxi 712046, China
| | - Jiasu Li
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
| | - Jinmiao Zha
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
- University of Chinese Academy of Sciences, Beijing 100049, China
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3
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Panlilio JM, Jones IT, Salanga MC, Aluru N, Hahn ME. Developmental Exposure to Domoic Acid Disrupts Startle Response Behavior and Circuitry in Zebrafish. Toxicol Sci 2021; 182:310-326. [PMID: 34097058 DOI: 10.1093/toxsci/kfab066] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Harmful algal blooms produce potent neurotoxins that accumulate in seafood and are hazardous to human health. Developmental exposure to the harmful algal bloom toxin, domoic acid (DomA), has behavioral consequences well into adulthood, but the cellular and molecular mechanisms of DomA developmental neurotoxicity are largely unknown. To assess these, we exposed zebrafish embryos to DomA during the previously identified window of susceptibility and used the well-known startle response circuit as a tool to identify specific neuronal components that are targeted by exposure to DomA. Exposure to DomA reduced startle responsiveness to both auditory/vibrational and electrical stimuli, and even at the highest stimulus intensities tested, led to a dramatic reduction of one type of startle (short-latency c-starts). Furthermore, DomA-exposed larvae had altered kinematics for both types of startle responses tested, exhibiting shallower bend angles and slower maximal angular velocities. Using vital dye staining, immunolabeling, and live imaging of transgenic lines, we determined that although the sensory inputs were intact, the reticulospinal neurons required for short-latency c-starts were absent in most DomA-exposed larvae. Furthermore, axon tracing revealed that DomA-treated larvae also showed significantly reduced primary motor neuron axon collaterals. Overall, these results show that developmental exposure to DomA targets large reticulospinal neurons and motor neuron axon collaterals, resulting in measurable deficits in startle behavior. They further provide a framework for using the startle response circuit to identify specific neural populations disrupted by toxins or toxicants and to link these disruptions to functional consequences for neural circuit function and behavior.
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Affiliation(s)
- Jennifer M Panlilio
- Biology Department, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, USA.,Massachusetts Institute of Technology (MIT) - Woods Hole Oceanographic Institution (WHOI) Joint Graduate Program in Oceanography and Oceanographic Engineering, Massachusetts 02543, USA.,Woods Hole Center for Oceans and Human Health, Woods Hole, Massachusetts 02543, USA
| | - Ian T Jones
- Biology Department, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, USA.,Massachusetts Institute of Technology (MIT) - Woods Hole Oceanographic Institution (WHOI) Joint Graduate Program in Oceanography and Oceanographic Engineering, Massachusetts 02543, USA
| | - Matthew C Salanga
- Biology Department, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, USA
| | - Neelakanteswar Aluru
- Biology Department, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, USA.,Woods Hole Center for Oceans and Human Health, Woods Hole, Massachusetts 02543, USA
| | - Mark E Hahn
- Biology Department, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, USA.,Woods Hole Center for Oceans and Human Health, Woods Hole, Massachusetts 02543, USA
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Baicalein 5,6-Dimethyl Ether Prevents Memory Deficits in the Scopolamine Zebrafish Model by Regulating Cholinergic and Antioxidant Systems. PLANTS 2021; 10:plants10061245. [PMID: 34207381 PMCID: PMC8233988 DOI: 10.3390/plants10061245] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Revised: 06/14/2021] [Accepted: 06/17/2021] [Indexed: 11/17/2022]
Abstract
Baicalein 5,6-dimethyl ether, a bioactive flavonoid isolated for the first time from Alnus rugosa, was explored for its capability to relieve memory deficits and decrease oxidative stress. We examined the neuropharmacological effects of baicalein 5,6-dimethyl ether on scopolamine (Sco)-induced zebrafish (Danio rerio) anxiety, amnesia, and brain oxidative stress and attempted to elucidate the underlying mechanisms. Anxiety-like behavior, exploratory behavior, and memory performance were measured using novel tank-diving test (NTT), Y-maze, and novel object recognition (NOR) tests. For 10 days, baicalein 5,6-dimethyl ether (1, 3, and 5 µg/L) was administered through immersion, whereas Sco (100 μM) was delivered 30 min before behavioral tests. Treatment with baicalein 5,6-dimethyl ether reduced anxiety and memory impairment, and increased exploratory behavior in specific tests, along with significant protection from neuronal oxidative stress in the brain tissue of Sco-treated zebrafish. Antioxidant and anti-acetylcholinesterase (AChE) activities of baicalein 5,6-dimethyl ether in the Sco-induced zebrafish were further confirmed using in vivo assays. In Sco-treated zebrafish, baicalein 5,6-dimethyl ether regulated cholinergic function by inhibiting AChE activity. Baicalein 5,6-dimethyl ether may be a promising candidate compound for treating anxiety and amnesia by restoring cholinergic activity and reducing brain oxidative stress, according to our findings.
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5
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Glutamate at the Vertebrate Neuromuscular Junction: From Modulation to Neurotransmission. Cells 2019; 8:cells8090996. [PMID: 31466388 PMCID: PMC6770210 DOI: 10.3390/cells8090996] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Revised: 08/21/2019] [Accepted: 08/27/2019] [Indexed: 12/23/2022] Open
Abstract
Although acetylcholine is the major neurotransmitter operating at the skeletal neuromuscular junction of many invertebrates and of vertebrates, glutamate participates in modulating cholinergic transmission and plastic changes in the last. Presynaptic terminals of neuromuscular junctions contain and release glutamate that contribute to the regulation of synaptic neurotransmission through its interaction with pre- and post-synaptic receptors activating downstream signaling pathways that tune synaptic efficacy and plasticity. During vertebrate development, the chemical nature of the neurotransmitter at the vertebrate neuromuscular junction can be experimentally shifted from acetylcholine to other mediators (including glutamate) through the modulation of calcium dynamics in motoneurons and, when the neurotransmitter changes, the muscle fiber expresses and assembles new receptors to match the nature of the new mediator. Finally, in adult rodents, by diverting descending spinal glutamatergic axons to a denervated muscle, a functional reinnervation can be achieved with the formation of new neuromuscular junctions that use glutamate as neurotransmitter and express ionotropic glutamate receptors and other markers of central glutamatergic synapses. Here, we summarize the past and recent experimental evidences in support of a role of glutamate as a mediator at the synapse between the motor nerve ending and the skeletal muscle fiber, focusing on the molecules and signaling pathways that are present and activated by glutamate at the vertebrate neuromuscular junction.
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Adult spinal motoneurons change their neurotransmitter phenotype to control locomotion. Proc Natl Acad Sci U S A 2018; 115:E9926-E9933. [PMID: 30275331 PMCID: PMC6196516 DOI: 10.1073/pnas.1809050115] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
An intriguing feature of the nervous system is its plasticity—the remarkable lifelong capacity to change and adapt in light of intrinsic and extrinsic stimuli. Among the many different adaptive mechanisms that occur within the nervous system, changes in neurotransmission form an important plasticity-bestowing mechanism in the reconfiguration of neuronal circuits. Here, we reveal that physical activity and spinal cord injury can switch the neurotransmitter phenotype of the fast axial motoneurons to coexpress glutamate. Furthermore, our study shows that the adult vertebrate spinal motoneurons corelease glutamate alongside ACh in neuromuscular junctions to regulate motor behaviors. Thus, our findings suggest that fast motoneuron glutamatergic respecification enables a motor function-enhancing mechanism in vertebrates. A particularly essential determinant of a neuron’s functionality is its neurotransmitter phenotype. While the prevailing view is that neurotransmitter phenotypes are fixed and determined early during development, a growing body of evidence suggests that neurons retain the ability to switch between different neurotransmitters. However, such changes are considered unlikely in motoneurons due to their crucial functional role in animals’ behavior. Here we describe the expression and dynamics of glutamatergic neurotransmission in the adult zebrafish spinal motoneuron circuit assembly. We demonstrate that part of the fast motoneurons retain the ability to switch their neurotransmitter phenotype under physiological (exercise/training) and pathophysiological (spinal cord injury) conditions to corelease glutamate in the neuromuscular junctions to enhance animals’ motor output. Our findings suggest that motoneuron neurotransmitter switching is an important plasticity-bestowing mechanism in the reconfiguration of spinal circuits that control movements.
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Wang JS, Bojovic D, Chen Y, Lindgren CA. Homocysteine sensitizes the mouse neuromuscular junction to oxidative stress by nitric oxide. Neuroreport 2018; 29:1030-1035. [PMID: 29939872 PMCID: PMC6044473 DOI: 10.1097/wnr.0000000000001073] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Homocysteine (HCY), a redox-active metabolite of the methionine cycle, is of particular clinical interest because of its association with various neurodegenerative diseases including amyotrophic lateral sclerosis. It has been previously established that HCY exacerbates damage to motor neurons from reactive oxygen species (ROS) such as hydrogen peroxide. To assess the role of HCY at the mammalian neuromuscular junction, neurotransmission was monitored by electrophysiology at the mouse epitrochleoanconeus muscle. Preparations were preincubated in HCY before inducing ROS and recordings were taken before and after ROS treatment. In this study, HCY was observed to sensitize the neuromuscular junction to ROS-induced depression of spontaneous transmission frequency, an effect we found to be mediated by a N-methyl-D-aspartate receptor (NMDAR) and nitric oxide (NO). The NMDAR antagonist D, L-2-amino-5-phosphonopentanoic acid prevented the HCY-induced sensitization to oxidative stress. Disrupting NO activity with either the nitric oxide synthase I antagonist Nω-nitro-L-arginine methyl ester hydrochloride or the NO scavenger 2-(4-carboxyphenyl)-4,4,5,5-tetramethyl-imidazoline-1-oxyl-3-oxide potassium salt also prevented sensitization. Moreover, replacing HCY with the exogenous NO donor Diethylamine NONOate diethylammonium was sufficient to reconstitute the effects of HCY-induced sensitization to ROS. Interestingly, a novel secondary effect was observed where HCY itself depresses quantal content, an effect found to be mediated by NMDARs independently of nitric oxide and ROS. Collectively, these data present a novel model of two distinct pathways through which HCY alters neurotransmission at the neuromuscular junction. Characterizing HCY's mechanism of action is of particular clinical relevance as many treatments for amyotrophic lateral sclerosis are centered on mitigating HCY-induced pathologies.
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Affiliation(s)
- John S Wang
- Department of Biology, Grinnell College, Grinnell, Iowa, USA
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8
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Lambert FM, Cardoit L, Courty E, Bougerol M, Thoby-Brisson M, Simmers J, Tostivint H, Le Ray D. Functional limb muscle innervation prior to cholinergic transmitter specification during early metamorphosis in Xenopus. eLife 2018; 7:30693. [PMID: 29845935 PMCID: PMC5997451 DOI: 10.7554/elife.30693] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2017] [Accepted: 05/06/2018] [Indexed: 12/28/2022] Open
Abstract
In vertebrates, functional motoneurons are defined as differentiated neurons that are connected to a central premotor network and activate peripheral muscle using acetylcholine. Generally, motoneurons and muscles develop simultaneously during embryogenesis. However, during Xenopus metamorphosis, developing limb motoneurons must reach their target muscles through the already established larval cholinergic axial neuromuscular system. Here, we demonstrate that at metamorphosis onset, spinal neurons retrogradely labeled from the emerging hindlimbs initially express neither choline acetyltransferase nor vesicular acetylcholine transporter. Nevertheless, they are positive for the motoneuronal transcription factor Islet1/2 and exhibit intrinsic and axial locomotor-driven electrophysiological activity. Moreover, the early appendicular motoneurons activate developing limb muscles via nicotinic antagonist-resistant, glutamate antagonist-sensitive, neuromuscular synapses. Coincidently, the hindlimb muscles transiently express glutamate, but not nicotinic receptors. Subsequently, both pre- and postsynaptic neuromuscular partners switch definitively to typical cholinergic transmitter signaling. Thus, our results demonstrate a novel context-dependent re-specification of neurotransmitter phenotype during neuromuscular system development.
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Affiliation(s)
- Francois M Lambert
- Institut de Neurosciences Cognitives et Intégratives d'Aquitaine, Université de Bordeaux, Bordeaux, France
| | - Laura Cardoit
- Institut de Neurosciences Cognitives et Intégratives d'Aquitaine, Université de Bordeaux, Bordeaux, France
| | - Elric Courty
- Institut de Neurosciences Cognitives et Intégratives d'Aquitaine, Université de Bordeaux, Bordeaux, France
| | - Marion Bougerol
- Evolution des Régulations Endocriniennes, Muséum National d'Histoire Naturelle, Paris, France
| | - Muriel Thoby-Brisson
- Institut de Neurosciences Cognitives et Intégratives d'Aquitaine, Université de Bordeaux, Bordeaux, France
| | - John Simmers
- Institut de Neurosciences Cognitives et Intégratives d'Aquitaine, Université de Bordeaux, Bordeaux, France
| | - Hervé Tostivint
- Evolution des Régulations Endocriniennes, Muséum National d'Histoire Naturelle, Paris, France
| | - Didier Le Ray
- Institut de Neurosciences Cognitives et Intégratives d'Aquitaine, Université de Bordeaux, Bordeaux, France
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9
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Bortolotto JW, Melo GMD, Cognato GDP, Vianna MRM, Bonan CD. Modulation of adenosine signaling prevents scopolamine-induced cognitive impairment in zebrafish. Neurobiol Learn Mem 2014; 118:113-9. [PMID: 25490060 DOI: 10.1016/j.nlm.2014.11.016] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2014] [Revised: 11/21/2014] [Accepted: 11/27/2014] [Indexed: 12/29/2022]
Abstract
Adenosine, a purine ribonucleoside, exhibits neuromodulatory and neuroprotective effects in the brain and is involved in memory formation and cognitive function. Adenosine signaling is mediated by adenosine receptors (A1, A2A, A2B, and A3); in turn, nucleotide and nucleoside-metabolizing enzymes and adenosine transporters regulate its levels. Scopolamine, a muscarinic cholinergic receptor antagonist, has profound amnesic effects in a variety of learning paradigms and has been used to induce cognitive deficits in animal models. This study investigated the effects of acute exposure to caffeine (a non-selective antagonist of adenosine receptors A1 and A2A), ZM 241385 (adenosine receptor A2A antagonist), DPCPX (adenosine receptor A1 antagonist), dipyridamole (inhibitor of nucleoside transporters) and EHNA (inhibitor of adenosine deaminase) in a model of pharmacological cognitive impairment induced by scopolamine in adult zebrafish. Caffeine, ZM 241385, DPCPX, dipyridamole, and EHNA were acutely administered independently via i.p. in zebrafish, followed by exposure to scopolamine dissolved in tank water (200μM). These compounds prevented the scopolamine-induced amnesia without impacting locomotor activity or social interaction. Together, these data support the hypothesis that adenosine signaling may modulate memory processing, suggesting that these compounds present a potential preventive strategy against cognitive impairment.
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Affiliation(s)
- Josiane Woutheres Bortolotto
- Laboratório de Neuroquímica e Psicofarmacologia, Departamento de Biologia Celular e Molecular, Programa de Pós-Graduação em Biologia Celular e Molecular, Faculdade de Biociências, Pontifícia Universidade Católica do Rio Grande do Sul, Avenida Ipiranga, 6681, 90619-900 Porto Alegre, RS, Brazil; ZebLab - Grupo de Pesquisa em modelos experimentais em zebrafish, Faculdade de Biociências, Pontifícia Universidade Católica do Rio Grande do Sul, Avenida Ipiranga, 6681, 90619-900 Porto Alegre, RS, Brazil
| | - Gabriela Madalena de Melo
- Laboratório de Neuroquímica e Psicofarmacologia, Departamento de Biologia Celular e Molecular, Programa de Pós-Graduação em Biologia Celular e Molecular, Faculdade de Biociências, Pontifícia Universidade Católica do Rio Grande do Sul, Avenida Ipiranga, 6681, 90619-900 Porto Alegre, RS, Brazil; ZebLab - Grupo de Pesquisa em modelos experimentais em zebrafish, Faculdade de Biociências, Pontifícia Universidade Católica do Rio Grande do Sul, Avenida Ipiranga, 6681, 90619-900 Porto Alegre, RS, Brazil
| | - Giana de Paula Cognato
- Laboratório de Neuroquímica e Psicofarmacologia, Departamento de Biologia Celular e Molecular, Programa de Pós-Graduação em Biologia Celular e Molecular, Faculdade de Biociências, Pontifícia Universidade Católica do Rio Grande do Sul, Avenida Ipiranga, 6681, 90619-900 Porto Alegre, RS, Brazil; Programa de Pós-Graduação em Bioquímica e Bioprospecção, Universidade Federal de Pelotas, Campus Universitário Capão do Leão, s/n°, CEP 96010-900, Pelotas, RS, Brazil
| | - Mônica Ryff Moreira Vianna
- Laboratório de Biologia e Desenvolvimento do Sistema Nervoso, Departamento de Ciências Morfofisiológicas, Programa de Pós-Graduação em Biologia Celular e Molecular, Faculdade de Biociências, Pontifícia Universidade Católica do Rio Grande do Sul, Avenida Ipiranga, 6681, 90619-900 Porto Alegre, RS, Brazil; ZebLab - Grupo de Pesquisa em modelos experimentais em zebrafish, Faculdade de Biociências, Pontifícia Universidade Católica do Rio Grande do Sul, Avenida Ipiranga, 6681, 90619-900 Porto Alegre, RS, Brazil
| | - Carla Denise Bonan
- Laboratório de Neuroquímica e Psicofarmacologia, Departamento de Biologia Celular e Molecular, Programa de Pós-Graduação em Biologia Celular e Molecular, Faculdade de Biociências, Pontifícia Universidade Católica do Rio Grande do Sul, Avenida Ipiranga, 6681, 90619-900 Porto Alegre, RS, Brazil; ZebLab - Grupo de Pesquisa em modelos experimentais em zebrafish, Faculdade de Biociências, Pontifícia Universidade Católica do Rio Grande do Sul, Avenida Ipiranga, 6681, 90619-900 Porto Alegre, RS, Brazil.
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10
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Cuevas E, Trickler WJ, Guo X, Ali SF, Paule MG, Kanungo J. Acetyl L-carnitine protects motor neurons and Rohon-Beard sensory neurons against ketamine-induced neurotoxicity in zebrafish embryos. Neurotoxicol Teratol 2013; 39:69-76. [PMID: 23896048 DOI: 10.1016/j.ntt.2013.07.005] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2013] [Revised: 07/15/2013] [Accepted: 07/16/2013] [Indexed: 12/13/2022]
Abstract
Ketamine, a non-competitive antagonist of N-methyl-D-aspartate (NMDA) type glutamate receptors is commonly used as a pediatric anesthetic. Multiple studies have shown ketamine to be neurotoxic, particularly when administered during the brain growth spurt. Previously, we have shown that ketamine is detrimental to motor neuron development in the zebrafish embryos. Here, using both wild type (WT) and transgenic (hb9:GFP) zebrafish embryos, we demonstrate that ketamine is neurotoxic to both motor and sensory neurons. Drug absorption studies showed that in the WT embryos, ketamine accumulation was approximately 0.4% of the original dose added to the exposure medium. The transgenic embryos express green fluorescent protein (GFP) localized in the motor neurons making them ideal for evaluating motor neuron development and toxicities in vivo. The hb9:GFP zebrafish embryos (28 h post fertilization) treated with 2 mM ketamine for 20 h demonstrated significant reductions in spinal motor neuron numbers, while co-treatment with acetyl L-carnitine proved to be neuroprotective. In whole mount immunohistochemical studies using WT embryos, a similar effect was observed for the primary sensory neurons. In the ketamine-treated WT embryos, the number of primary sensory Rohon-Beard (RB) neurons was significantly reduced compared to that in controls. However, acetyl L-carnitine co-treatment prevented ketamine-induced adverse effects on the RB neurons. These results suggest that acetyl L-carnitine protects both motor and sensory neurons from ketamine-induced neurotoxicity.
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Affiliation(s)
- Elvis Cuevas
- Division of Neurotoxicology, National Center for Toxicological Research, US Food and Drug Administration, 3900 NCTR Road, Jefferson, AR 72079, USA
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11
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Walder KK, Ryan SB, Bzdega T, Olszewski RT, Neale JH, Lindgren CA. Immunohistological and electrophysiological evidence that N-acetylaspartylglutamate is a co-transmitter at the vertebrate neuromuscular junction. Eur J Neurosci 2012; 37:118-29. [PMID: 23134476 DOI: 10.1111/ejn.12027] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2012] [Revised: 09/18/2012] [Accepted: 09/20/2012] [Indexed: 12/21/2022]
Abstract
Immunohistochemical studies previously revealed the presence of the peptide transmitter N-acetylaspartylglutamate (NAAG) in spinal motor neurons, axons and presumptive neuromuscular junctions (NMJs). At synapses in the central nervous system, NAAG has been shown to activate the type 3 metabotropic glutamate receptor (mGluR3) and is inactivated by an extracellular peptidase, glutamate carboxypeptidase II. The present study tested the hypothesis that NAAG meets the criteria for classification as a co-transmitter at the vertebrate NMJ. Confocal microscopy confirmed the presence of NAAG immunoreactivity and extended the resolution of the peptide's location in the lizard (Anolis carolinensis) NMJ. NAAG was localised to a presynaptic region immediately adjacent to postsynaptic acetylcholine receptors. NAAG was depleted by potassium-induced depolarisation and by electrical stimulation of motor axons. The NAAG receptor, mGluR3, was localised to the presynaptic terminal consistent with NAAG's demonstrated role as a regulator of synaptic release at central synapses. In contrast, glutamate receptors, type 2 metabotropic glutamate receptor (mGluR2) and N-methyl-d-aspartate, were closely associated with acetylcholine receptors in the postsynaptic membrane. Glutamate carboxypeptidase II, the NAAG-inactivating enzyme, was identified exclusively in perisynaptic glial cells. This localisation was confirmed by the loss of immunoreactivity when these cells were selectively eliminated. Finally, electrophysiological studies showed that exogenous NAAG inhibited evoked neurotransmitter release by activating a group II metabotropic glutamate receptor (mGluR2 or mGluR3). Collectively, these data support the conclusion that NAAG is a co-transmitter at the vertebrate NMJ.
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Affiliation(s)
- Kathryn K Walder
- Department of Biology, Grinnell College, Grinnell, IA 50112, USA
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12
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Y-Maze memory task in zebrafish (Danio rerio): The role of glutamatergic and cholinergic systems on the acquisition and consolidation periods. Neurobiol Learn Mem 2012; 98:321-8. [DOI: 10.1016/j.nlm.2012.09.008] [Citation(s) in RCA: 111] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2012] [Revised: 08/18/2012] [Accepted: 09/27/2012] [Indexed: 11/18/2022]
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13
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Braida D, Donzelli A, Martucci R, Ponzoni L, Pauletti A, Sala M. Neurohypophyseal hormones protect against pentylenetetrazole-induced seizures in zebrafish: role of oxytocin-like and V1a-like receptor. Peptides 2012; 37:327-33. [PMID: 22828174 DOI: 10.1016/j.peptides.2012.07.013] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/26/2012] [Revised: 07/16/2012] [Accepted: 07/16/2012] [Indexed: 02/04/2023]
Abstract
Oxytocin (OT) and arginine-vasopressin (AVP) are involved in the physiological response to different stressors like the occurrence of seizures which is regarded as a severe stress factor. Zebrafish (Danio rerio) is recently featured as a model of epilepsy but the role of neurohypophyseal hormones on this teleost is still unknown. We attempted to determine whether non-mammalian homologues like isotocin (IT) and vasotocin (AVT) affected pentylenetetrazole (PTZ)-induced seizures in adult zebrafish in comparison with OT/AVP. The mechanism was studied using the most selective OT and AVP receptor antagonists. Zebrafish were injected i.m. with increasing doses (0.1-40 ng/kg) of the neuropeptides 10 min before PTZ exposure. DesGly-NH2-d(CH2)5-[D-Tyr2,Thr4]OVT (desglyDTyrOVT) for OT receptor and SR49059 for V1a subtype receptor, were injected together with each agonist 20 min before PTZ exposure. All the peptides significantly decreased the number of seizures, increased the mean latency time to the first seizure and decreased lethality. This protective effect led to a dose-response curve following a U-shaped form. IT was approximately 40 times more active than OT while AVT was 20 times more potent than AVP in reducing the number of seizures. DesglyDTyrOVT was more effective in antagonizing OT/IT, while SR49059 mainly blocked AVP/AVT-induced protection against PTZ-induced seizures. The present findings provide direct evidence of an important involvement of IT/OT and AVP/AVT as anticonvulsant agents against PTZ-induced seizures with a receptor-mediated mechanism in zebrafish. These data reinforce zebrafish as an emerging experimental model to study and identify new antiepileptic drugs.
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Affiliation(s)
- Daniela Braida
- Dipartimento di Biotecnologie mediche e Medicina traslazionale, Università degli Studi di Milano, Via Vanvitelli 32, Milan, Italy
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14
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Kanungo J, Cuevas E, Ali SF, Paule MG. Ketamine induces motor neuron toxicity and alters neurogenic and proneural gene expression in zebrafish. J Appl Toxicol 2011; 33:410-7. [PMID: 22045596 DOI: 10.1002/jat.1751] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2011] [Revised: 09/06/2011] [Accepted: 09/06/2011] [Indexed: 01/06/2023]
Abstract
Ketamine, a noncompetitive antagonist of N-methyl-d-aspartate-type glutamate receptors, is a pediatric anesthetic that has been shown to be neurotoxic in rodents and nonhuman primates when administered during the brain growth spurt. Recently, the zebrafish has become an attractive model for toxicity assays, in part because the predictive capability of the zebrafish model, with respect to chemical effects, compares well with that from mammalian models. In the transgenic (hb9:GFP) embryos used in this study, green fluorescent protein (GFP) is expressed in the motor neurons, facilitating the visualization and analysis of motor neuron development in vivo. In order to determine whether ketamine induces motor neuron toxicity in zebrafish, embryos of these transgenic fish were treated with different concentrations of ketamine (0.5 and 2.0 mm). For ketamine exposures lasting up to 20 h, larvae showed no gross morphological abnormalities. Analysis of GFP-expressing motor neurons in the live embryos, however, revealed that 2.0 mm ketamine adversely affected motor neuron axon length and decreased cranial and motor neuron populations. Quantitative reverse transcriptase-polymerase chain reaction analysis demonstrated that ketamine down-regulated the motor neuron-inducing zinc finger transcription factor Gli2b and the proneural gene NeuroD even at 0.5 mm concentration, while up-regulating the expression of the proneural gene Neurogenin1 (Ngn1). Expression of the neurogenic gene, Notch1a, was suppressed, indicating that neuronal precursor generation from uncommitted cells was favored. These results suggest that ketamine is neurotoxic to motor neurons in zebrafish and possibly affects the differentiating/differentiatedneurons rather than neuronal progenitors. Published 2011. This article is a US Government work and is in the public domain in the USA.
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Affiliation(s)
- Jyotshna Kanungo
- Division of Neurotoxicology, National Center for Toxicological Research, US Food and Drug Administration, 3900 NCTR Road, Jefferson, AR 72079, USA.
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15
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Rico EP, Rosemberg DB, Seibt KJ, Capiotti KM, Da Silva RS, Bonan CD. Zebrafish neurotransmitter systems as potential pharmacological and toxicological targets. Neurotoxicol Teratol 2011; 33:608-17. [PMID: 21907791 DOI: 10.1016/j.ntt.2011.07.007] [Citation(s) in RCA: 147] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2011] [Revised: 05/20/2011] [Accepted: 07/20/2011] [Indexed: 01/23/2023]
Abstract
Recent advances in neurobiology have emphasized the study of brain structure and function and its association with numerous pathological and toxicological events. Neurotransmitters are substances that relay, amplify, and modulate electrical signals between neurons and other cells. Neurotransmitter signaling mediates rapid intercellular communication by interacting with cell surface receptors, activating second messenger systems and regulating the activity of ion channels. Changes in the functional balance of neurotransmitters have been implicated in the failure of central nervous system function. In addition, abnormalities in neurotransmitter production or functioning can be induced by several toxicological compounds, many of which are found in the environment. The zebrafish has been increasingly used as an animal model for biomedical research, primarily due to its genetic tractability and ease of maintenance. These features make this species a versatile tool for pre-clinical drug discovery and toxicological investigations. Here, we present a review regarding the role of different excitatory and inhibitory neurotransmitter systems in zebrafish, such as dopaminergic, serotoninergic, cholinergic, purinergic, histaminergic, nitrergic, glutamatergic, glycinergic, and GABAergic systems, and emphasizing their features as pharmacological and toxicological targets. The increase in the global knowledge of neurotransmitter systems in zebrafish and the elucidation of their pharmacological and toxicological aspects may lead to new strategies and appropriate research priorities to offer insights for biomedical and environmental research.
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Affiliation(s)
- E P Rico
- Programa de Pós-Graduação em Ciências Biológicas: Bioquímica, Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Rua Ramiro Barcelos 2600-Anexo, Porto Alegre, RS, Brazil
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16
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Alfaro JM, Ripoll-Gómez J, Burgos JS. Kainate administered to adult zebrafish causes seizures similar to those in rodent models. Eur J Neurosci 2011; 33:1252-5. [PMID: 21375600 DOI: 10.1111/j.1460-9568.2011.07622.x] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Glutamate is the major excitatory neurotransmitter of the central nervous system in vertebrates. Excitotoxicity, caused by over-stimulation of the glutamate receptors, is a major cause of neuron death in several brain diseases, including epilepsy. We describe here how behavioural seizures can be triggered in adult zebrafish by the administration of kainate and are very similar to those observed in rodent models. Kainate induced a dose-dependent sequence of behavioural changes culminating in clonus-like convulsions. Behavioural seizures were suppressed by DNQX (6,7-dinitroquinoxaline-2,3-dione) dose-dependently, whilst MK-801 (a non-competitive NMDA receptor antagonist) had a lesser effect. Kainate triggers seizures in adult zebrafish, and thus this species can be considered as a new model for studying seizures and subsequent excitotoxic brain injury.
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Affiliation(s)
- Juan M Alfaro
- NEURON BPh, BioPharma Division, Parque Tecnológico de Ciencias de la Salud, Edif. BIC-Granada, Av. Innovación 1, Armilla 18100, Granada, Spain
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17
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Pietri T, Manalo E, Ryan J, Saint-Amant L, Washbourne P. Glutamate drives the touch response through a rostral loop in the spinal cord of zebrafish embryos. Dev Neurobiol 2009; 69:780-95. [PMID: 19634126 DOI: 10.1002/dneu.20741] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Characterizing connectivity in the spinal cord of zebrafish embryos is not only prerequisite to understanding the development of locomotion, but is also necessary for maximizing the potential of genetic studies of circuit formation in this model system. During their first day of development, zebrafish embryos show two simple motor behaviors. First, they coil their trunks spontaneously, and a few hours later they start responding to touch with contralateral coils. These behaviors are contemporaneous until spontaneous coils become infrequent by 30 h. Glutamatergic neurons are distributed throughout the embryonic spinal cord, but their contribution to these early motor behaviors in immature zebrafish is still unclear. We demonstrate that the kinetics of spontaneous coiling and touch-evoked responses show distinct developmental time courses and that the touch response is dependent on AMPA-type glutamate receptor activation. Transection experiments suggest that the circuits required for touch-evoked responses are confined to the spinal cord and that only the most rostral part of the spinal cord is sufficient for triggering the full response. This rostral sensory connection is presumably established via CoPA interneurons, as they project to the rostral spinal cord. Electrophysiological analysis demonstrates that these neurons receive short latency AMPA-type glutamatergic inputs in response to ipsilateral tactile stimuli. We conclude that touch responses in early embryonic zebrafish arise only after glutamatergic synapses connect sensory neurons and interneurons to the contralateral motor network via a rostral loop. This helps define an elementary circuit that is modified by the addition of sensory inputs, resulting in behavioral transformation.
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Affiliation(s)
- Thomas Pietri
- Institute of Neuroscience, University of Oregon, Eugene, Oregon 97403, USA
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18
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Guo S. Using zebrafish to assess the impact of drugs on neural development and function. Expert Opin Drug Discov 2009; 4:715-726. [PMID: 19774094 DOI: 10.1517/17460440902988464] [Citation(s) in RCA: 106] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
BACKGROUND: Zebrafish is becoming an increasingly attractive model organism for understanding biology and developing therapeutics, because as a vertebrate, it shares considerable similarity with mammals in both genetic compositions and tissue/organ structures, and yet remains accessible to high throughput phenotype-based genetic and small molecule compound screening. OBJECTIVE/METHOD: The focus of this review is on the nervous system, which is arguably the most complex organ and known to be afflicted by more than six hundred disorders in humans. I discuss the past, present, and future of using zebrafish to assess the impact of small molecule drugs on neural development and function, in light of understanding and treating neurodevelopmental disorders such as autism, neurodegenerative disorders including Alzheimer's, Parkinson's, and Hungtington's disease, and neural system dysfunctions such as anxiety/depression and addiction. CONCLUSION: These studies hold promise to reveal fundamental mechanisms governing nervous system development and function, and to facilitate small molecule drug discovery for the many types of neurological disorders.
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Affiliation(s)
- Su Guo
- Department of Biopharmaceutical Sciences, Programs in Biological Sciences and Human Genetics, Institute for Regenerative Medicine, University of California San Francisco, CA 94143-2811
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19
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Coutts CA, Balt LN, Ali DW. Protein kinase A modulates A-type potassium currents of larval zebrafish (Danio rerio) white muscle fibres. Acta Physiol (Oxf) 2009; 195:259-72. [PMID: 18702677 DOI: 10.1111/j.1748-1716.2008.01889.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
AIMS Potassium (K(+)) channels are involved in regulating cell excitability and action potential shape. To our knowledge, very little is known about the modulation of A-type K(+) currents in skeletal muscle fibres. Therefore, we sought to determine whether K(+) currents of zebrafish white skeletal muscle were modulated by protein kinase A (PKA). METHODS Pharmacology and whole-cell patch clamp were used to examine A-type K(+) currents and action potentials associated with zebrafish white skeletal muscle fibres. RESULTS Activation of PKA by a combination of forskolin + 3-isobutyl-1-methylxanthine (Fsk + IBMX) decreased the peak current density by approximately 60% and altered the inactivation kinetics of A-type K(+) currents. The specific PKA inhibitor H-89 partially blocked the Fsk + IBMX-induced reduction in peak current density, but had no effect on the change in decay kinetics. Fsk + IBMX treatment did not shift the activation curve, but it significantly reduced the slope factor of activation. Activation of PKA by Fsk + IBMX resulted in a negative shift in the V(50) of inactivation. H-89 prevented all Fsk + IBMX-induced changes in the steady-state properties of K(+) currents. Application of Fsk + IBMX increased action potential amplitude, but had no significant effect on action potential threshold, half width or recovery rate, when fibres were depolarized with single pulses, paired pulses or with high-frequency stimuli. CONCLUSION PKA modulates the A-type K(+) current in zebrafish skeletal muscle and affects action potential properties. Our results provide new insights into the role of A-type K(+) channels in muscle physiology.
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20
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Pinard A, Robitaille R. Nitric oxide dependence of glutamate-mediated modulation at a vertebrate neuromuscular junction. Eur J Neurosci 2008; 28:577-87. [PMID: 18702729 DOI: 10.1111/j.1460-9568.2008.06355.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Recent evidence has revealed a contribution of glutamate in the stereotyped cholinergic neuromuscular transmission. Indeed, receptors, transporters and glutamate itself are present at the neuromuscular junction (NMJ) while glutamate activation of metabotropic receptors (mGluRs) decreases synaptic transmission and mediates depression through presynaptic mechanisms. However, we have shown that the mGluRs are located postsynaptically, inconsistent with the presynaptic action of glutamate. In the present study, we tested whether nitric oxide (NO) serves as a retrograde messenger mediating the distant effect of glutamate. Glutamate or an mGluR agonist [trans-(1S,3R)-aminocyclopentanedicarboxylic acid (ACPD)] failed to reduce synaptic transmission in the presence of an NOS inhibitor (3Br7NINa, 3-bromo-7-nitroindazole sodium salt). Moreover, application of 3Br7NINa precluded the effect of the mGluR antagonist MCPG [(S)-alpha-methyl-4-carboxyphenylglycine] on high-frequency-induced synaptic depression. Iontophoretic injections of BAPTA [1,2-bis(2-aminophenoxy)ethane-N,N,N'-tetraacetic acid] in muscle fibres abolished the effect of trans-ACPD on synaptic transmission and blocked the mGluR component of depression, indicating the involvement of muscular calcium in mGluR-induced depression. Also, the use of this protocol unveiled a muscular calcium-dependent potentiating pathway dependent on cyclo-oxygenase activity. In addition, local application of trans-ACPD induced an increase in NO production by muscle fibres visualized with the indicator DAF-FM (4-amino-5-methylamino-2',7'-difluorofluorescein). This was prevented by 3Br7NINa or the iontophoretic injection of BAPTA. Moreover, motor nerve stimulation (50 Hz, 30 s) induced an increase in DAF-FM fluorescence that was abolished by 3Br7NINa and MCPG. Hence, the data suggest that the production of the retrograde molecule NO depends on the postsynaptic calcium-dependent activation of nitric oxide synthase following mGluRs stimulation and is essential for the glutamatergic modulation of synaptic efficacy and plasticity at the NMJ.
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Affiliation(s)
- Audrée Pinard
- Département de physiologie, Groupe de Recherche sur leSystème Nerveux Central, Université de Montréal, Montréal, QC, Canada
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21
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Hoppmann V, Wu JJ, Søviknes AM, Helvik JV, Becker TS. Expression of the eight AMPA receptor subunit genes in the developing central nervous system and sensory organs of zebrafish. Dev Dyn 2008; 237:788-99. [PMID: 18224707 DOI: 10.1002/dvdy.21447] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The AMPA type glutamate receptors mediate the majority of fast synaptic transmission in the vertebrate nervous system. Whereas mammals have four subunit genes, Gria1-4, zebrafish has retained a duplicated set of eight genes named gria1-4a and b. We give here a detailed overview of the expression patterns of all eight zebrafish subunits within the developing central nervous system and sensory organs at 24, 48, and 72 hr after fertilization. Expression domains include distinct neuronal subsets in the developing forebrain, midbrain, hindbrain, and spinal cord, as well as in the ganglion- and inner nuclear layers of the retina. As a general rule, each pair of duplicated gria genes is differentially expressed, indicating subfunctionalization of AMPA receptor subunit expression in the teleost lineage. Our findings suggest that zebrafish can serve as a useful model system to investigate the role of AMPA receptors and their differential expression in the vertebrate nervous system.
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Affiliation(s)
- Verena Hoppmann
- Sars International Centre for Molecular Marine Biology, University Bergen, Thormøhlensgate, Bergen, Norway
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22
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Abstract
As the population ages, there is a growing need for effective therapies for the treatment of neurological diseases. A limited number of therapeutics are currently available to improve cognitive function and research is limited by the need for in vivo models. Zebrafish have recently become a focus of neurobehavioral studies since larvae display neuropathological and behavioral phenotypes that are quantifiable and relate to those seen in man. Due to the small size of Zebrafish larvae, assays can be undertaken in 96 well plates and as the larvae can live in as little as 200 mul of fluid, only a few milligrams of compound are needed for screening. Thus in vivo analysis of the effects of compounds can be undertaken at much earlier stages in the drug discovery process. This review will look at the utility of the zebrafish in the study of neurological diseases and its role in improving the throughput of candidate compounds in in vivo screens.
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Affiliation(s)
- J D Best
- Summit (Cambridge) Ltd., Beach Drive Cambridge, UK
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23
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Cervetto C, Taccola G. GABAA and strychnine-sensitive glycine receptors modulate N-methyl-D-aspartate-evoked acetylcholine release from rat spinal motoneurons: a possible role in neuroprotection. Neuroscience 2008; 154:1517-24. [PMID: 18554813 DOI: 10.1016/j.neuroscience.2008.04.066] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2008] [Revised: 04/25/2008] [Accepted: 04/30/2008] [Indexed: 01/05/2023]
Abstract
Increasing experimental and clinical evidence suggests that abnormal glutamate transmission might play a major role in a vast number of neurological disorders. As a measure of glutamatergic excitation, we have studied the acetylcholine (ACh) release induced by N-methyl-D-aspartate (NMDA) receptor stimulation in primary cultured rat ventral horn spinal neurons and we have evaluated the possibility to limit the consequences of the hyperactivation of glutamatergic receptors, by recruiting the inhibitory transmission mediated by GABA and glycine. For this purpose, we have exposed cell cultures, previously loaded with [(3)H]choline, to NMDA, which increased the spontaneous tritium efflux in a concentration-dependent manner. Tritium release is dependent upon external Ca(2+), tetrodotoxin, Cd(2+) ions and omega-conotoxin GVIA, but not on omega-conotoxin MVIIC nor nifedipine, suggesting the involvement of N-type voltage-sensitive calcium channels. NMDA-mediated [(3)H]ACh release was completely prevented by MK-801, 5,7-diclorokynurenic acid and ifenprodil, while it was strongly inhibited by a lower external pH, suggesting that the involved NMDA receptors contain NR1 and NR2B subunits. Muscimol inhibited NMDA-evoked [(3)H]ACh release and its effect was antagonized by SR95531 and potentiated by diazepam, indicating the involvement of benzodiazepine-sensitive GABA(A) receptors. Also glycine, via strychnine-sensitive receptors, inhibited the effect of NMDA. It is concluded that glutamate acts on the NMDA receptors situated on spinal motoneurons to evoke ACh release, which can be inhibited through the activation of GABA(A) and glycine receptors present on the same neurons. These data suggest that glutamatergic overload of receptors located onto spinal cord motoneurons might be decreased by activating GABA(A) and glycine receptors.
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Affiliation(s)
- C Cervetto
- Dipartimento di Medicina Sperimentale, Sezione di Farmacologia e Tossicologia, Università di Genova, Genova, Italy
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24
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Geuna S. Spinal cord injury treatment by induction of a shift from cholinergic to glutamatergic innervation of muscle fibers. Muscle Nerve 2006; 35:5-7. [PMID: 17058276 DOI: 10.1002/mus.20687] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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25
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Pizzi M, Brunelli G, Barlati S, Spano P. Glutamatergic innervation of rat skeletal muscle by supraspinal neurons: a new paradigm in spinal cord injury repair. Curr Opin Neurobiol 2006; 16:323-8. [PMID: 16723220 DOI: 10.1016/j.conb.2006.05.013] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2006] [Accepted: 05/08/2006] [Indexed: 10/24/2022]
Abstract
Acetylcholine is the specific chemical code of spinal nerve terminal transmission at the mammalian neuromuscular junction (NMJ), whereas nicotinic acetylcholine receptors inserted into the membrane of muscle fibres mediate signalling for the muscle response. Glutamate has a primary role in neuromuscular transmission of organisms that are phylogenetically distant from mammals, the invertebrates, including insect and molluscs. Recent research has shown that diverting descending glutamatergic fibres in the spinal cord to rat skeletal muscle by means of a peripheral nerve graft causes the cholinergic synapse to switch to the glutamatergic type. These data demonstrate that under appropriate surgical manipulation supraspinal neurons can directly target muscle fibres and specify the postsynaptic receptors to achieve a functional glutamatergic NMJ.
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Affiliation(s)
- Marina Pizzi
- Divisions of Pharmacology and Experimental Therapeutics, Italy
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26
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Brunelli G, Spano P, Barlati S, Guarneri B, Barbon A, Bresciani R, Pizzi M. Glutamatergic reinnervation through peripheral nerve graft dictates assembly of glutamatergic synapses at rat skeletal muscle. Proc Natl Acad Sci U S A 2005; 102:8752-7. [PMID: 15937120 PMCID: PMC1142481 DOI: 10.1073/pnas.0500530102] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Acetylcholine is the main neurotransmitter at the mammalian neuromuscular junction (NMJ) where nicotinic acetylcholine receptors mediate the signaling between nerve terminals and muscle fibers. We show that under glutamatergic transmission, rat NMJ switches from cholinergic type synapse to glutamatergic synapse. Connecting skeletal muscle to the lateral white matter of the spinal cord by grafting the distal stump of the transected motor nerve produced functional muscle reinnervation. The restored neuromuscular activity became resistant to common curare blockers but sensitive to the glutamate alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor antagonist. Analysis of the regenerated nerve disclosed new glutamatergic axons and the disappearance of cholinergic fibers. Many axons belonged to the supraspinal neurons located in the red nucleus and the brainstem nuclei. Finally, the innervated muscle displayed high expression and clustering of alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor subunits glutamate receptors 1 and 2. Our data suggest that supraspinal neurons can target skeletal muscle, which retains the plasticity to generate functional glutamatergic NMJ.
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Affiliation(s)
- Giorgio Brunelli
- Foundation for Experimental Spinal Cord Research, School of Medicine, University of Brescia, 25123 Brescia, Italy
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