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Miranda CO, Hegedüs K, Kis G, Antal M. Synaptic Targets of Glycinergic Neurons in Laminae I-III of the Spinal Dorsal Horn. Int J Mol Sci 2023; 24:ijms24086943. [PMID: 37108107 PMCID: PMC10139066 DOI: 10.3390/ijms24086943] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2023] [Revised: 04/04/2023] [Accepted: 04/07/2023] [Indexed: 04/29/2023] Open
Abstract
A great deal of evidence supports the inevitable importance of spinal glycinergic inhibition in the development of chronic pain conditions. However, it remains unclear how glycinergic neurons contribute to the formation of spinal neural circuits underlying pain-related information processing. Thus, we intended to explore the synaptic targets of spinal glycinergic neurons in the pain processing region (laminae I-III) of the spinal dorsal horn by combining transgenic technology with immunocytochemistry and in situ hybridization accompanied by light and electron microscopy. First, our results suggest that, in addition to neurons in laminae I-III, glycinergic neurons with cell bodies in lamina IV may contribute substantially to spinal pain processing. On the one hand, we show that glycine transporter 2 immunostained glycinergic axon terminals target almost all types of excitatory and inhibitory interneurons identified by their neuronal markers in laminae I-III. Thus, glycinergic postsynaptic inhibition, including glycinergic inhibition of inhibitory interneurons, must be a common functional mechanism of spinal pain processing. On the other hand, our results demonstrate that glycine transporter 2 containing axon terminals target only specific subsets of axon terminals in laminae I-III, including nonpeptidergic nociceptive C fibers binding IB4 and nonnociceptive myelinated A fibers immunoreactive for type 1 vesicular glutamate transporter, indicating that glycinergic presynaptic inhibition may be important for targeting functionally specific subpopulations of primary afferent inputs.
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Affiliation(s)
- Camila Oliveira Miranda
- Department of Anatomy, Histology and Embryology, Faculty of Medicine, University of Debrecen, H-4032 Debrecen, Hungary
| | - Krisztina Hegedüs
- Department of Anatomy, Histology and Embryology, Faculty of Medicine, University of Debrecen, H-4032 Debrecen, Hungary
| | - Gréta Kis
- Department of Anatomy, Histology and Embryology, Faculty of Medicine, University of Debrecen, H-4032 Debrecen, Hungary
| | - Miklós Antal
- Department of Anatomy, Histology and Embryology, Faculty of Medicine, University of Debrecen, H-4032 Debrecen, Hungary
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Chemogenetic activation of VGLUT3-expressing neurons decreases movement. Eur J Pharmacol 2022; 935:175298. [PMID: 36198338 DOI: 10.1016/j.ejphar.2022.175298] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2022] [Revised: 09/16/2022] [Accepted: 09/21/2022] [Indexed: 11/24/2022]
Abstract
Vesicular glutamate transporters (VGLUTs) are responsible for the storage of glutamate into secretory vesicles. The VGLUT3 isoform is mainly expressed in neurons that secrete other classical neurotransmitters, including the cholinergic interneurons in the striatum, and VGLUT3-expressing neurons often secrete two distinct neurotransmitters. VGLUT3 is discretely distributed throughout the brain and is found in subpopulations of spinal cord interneurons, in subset of neurons in the dorsal root ganglion, and in Merkel cells. Mice with a global loss of VGLUT3 are hyperactive and the modulation of specific VGLUT3-expressing circuits can lead to changes in movement. In this study, we tested the hypothesis that increased activity of VGLUT3-expressing neurons is associated with decreased movement. Using a mouse line expressing excitatory designer receptor exclusively activated by designer drugs (hM3Dq-DREADD) on VGLUT3-expressing neurons, we showed that activation of hM3Dq signalling acutely decreased locomotor activity. This decreased locomotion was likely not due to circuit changes mediated by glutamate nor acetylcholine released from VGLUT3-expressing neurons, as activation of hM3Dq signalling in mice that do not release glutamate or acetylcholine from VGLUT3-expressing neurons also decreased locomotor activity. This suggests that other neurotransmitters are likely driving this hypoactive phenotype. We used these mouse lines to compare the effects of DREADD agonists in vivo. We observed that clozapine-N-oxide (CNO), clozapine, compound 21 and perlapine show small differences in the speed at which they prompt behavioural responses but the four of them are selective DREADD ligands.
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Kókai É, Alsulaiman WAA, Dickie AC, Bell AM, Goffin L, Watanabe M, Gutierrez-Mecinas M, Todd AJ. Characterisation of deep dorsal horn projection neurons in the spinal cord of the Phox2a::Cre mouse line. Mol Pain 2022; 18:17448069221119614. [PMID: 36000342 PMCID: PMC9445510 DOI: 10.1177/17448069221119614] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Revised: 07/20/2022] [Accepted: 07/27/2022] [Indexed: 11/16/2022] Open
Abstract
Projection neurons belonging to the anterolateral system (ALS) underlie the perception of pain, skin temperature and itch. Many ALS cells are located in laminae III-V of the dorsal horn and the adjacent lateral white matter. However, relatively little is known about the excitatory synaptic input to these deep ALS cells, and therefore about their engagement with the neuronal circuitry of the region. We have used a recently developed mouse line, Phox2a::Cre, to investigate a population of deep dorsal horn ALS neurons known as "antenna cells", which are characterised by dense innervation from peptidergic nociceptors, and to compare these with other ALS cells in the deep dorsal horn and lateral white matter. We show that these two classes differ, both in the density of excitatory synapses, and in the source of input at these synapses. Peptidergic nociceptors account for around two-thirds of the excitatory synapses on the antenna cells, but for only a small proportion of the input to the non-antenna cells. Conversely, boutons with high levels of VGLUT2, which are likely to originate mainly from glutamatergic spinal neurons, account for only ∼5% of the excitatory synapses on antenna cells, but for a much larger proportion of the input to the non-antenna cells. VGLUT1 is expressed by myelinated low-threshold mechanoreceptors and corticospinal axons, and these innervate both antenna and non-antenna cells. However, the density of VGLUT1 input to the non-antenna cells is highly variable, consistent with the view that these neurons are functionally heterogeneous.
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Affiliation(s)
- Éva Kókai
- School of Psychology and Neuroscience, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - Wafa AA Alsulaiman
- School of Psychology and Neuroscience, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - Allen C Dickie
- School of Psychology and Neuroscience, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - Andrew M Bell
- School of Psychology and Neuroscience, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
- School of Veterinary Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - Luca Goffin
- School of Psychology and Neuroscience, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - Masahiko Watanabe
- Department of Anatomy, Hokkaido University School of Medicine, Sapporo, Japan
| | - Maria Gutierrez-Mecinas
- School of Psychology and Neuroscience, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - Andrew J Todd
- School of Psychology and Neuroscience, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
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Todd AJ. An Historical Perspective: The Second Order Neuron in the Pain Pathway. FRONTIERS IN PAIN RESEARCH (LAUSANNE, SWITZERLAND) 2022; 3:845211. [PMID: 35295811 PMCID: PMC8915774 DOI: 10.3389/fpain.2022.845211] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/29/2021] [Accepted: 02/02/2022] [Indexed: 11/13/2022]
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Fazekas CL, Szabó A, Török B, Bánrévi K, Correia P, Chaves T, Daumas S, Zelena D. A New Player in the Hippocampus: A Review on VGLUT3+ Neurons and Their Role in the Regulation of Hippocampal Activity and Behaviour. Int J Mol Sci 2022; 23:790. [PMID: 35054976 PMCID: PMC8775679 DOI: 10.3390/ijms23020790] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2021] [Revised: 01/06/2022] [Accepted: 01/08/2022] [Indexed: 01/05/2023] Open
Abstract
Glutamate is the most abundant excitatory amino acid in the central nervous system. Neurons using glutamate as a neurotransmitter can be characterised by vesicular glutamate transporters (VGLUTs). Among the three subtypes, VGLUT3 is unique, co-localising with other "classical" neurotransmitters, such as the inhibitory GABA. Glutamate, manipulated by VGLUT3, can modulate the packaging as well as the release of other neurotransmitters and serve as a retrograde signal through its release from the somata and dendrites. Its contribution to sensory processes (including seeing, hearing, and mechanosensation) is well characterised. However, its involvement in learning and memory can only be assumed based on its prominent hippocampal presence. Although VGLUT3-expressing neurons are detectable in the hippocampus, most of the hippocampal VGLUT3 positivity can be found on nerve terminals, presumably coming from the median raphe. This hippocampal glutamatergic network plays a pivotal role in several important processes (e.g., learning and memory, emotions, epilepsy, cardiovascular regulation). Indirect information from anatomical studies and KO mice strains suggests the contribution of local VGLUT3-positive hippocampal neurons as well as afferentations in these events. However, further studies making use of more specific tools (e.g., Cre-mice, opto- and chemogenetics) are needed to confirm these assumptions.
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Affiliation(s)
- Csilla Lea Fazekas
- Institute of Experimental Medicine, 1083 Budapest, Hungary; (C.L.F.); (A.S.); (B.T.); (K.B.); (P.C.); (T.C.)
- Centre for Neuroscience, Szentágothai Research Centre, Institute of Physiology, Medical School, University of Pécs, 7624 Pécs, Hungary
- János Szentágothai Doctoral School of Neurosciences, Semmelweis University, 1085 Budapest, Hungary
- Neuroscience Paris Seine-Institut de Biologie Paris Seine (NPS-IBPS) INSERM, Sorbonne Université, CNRS, 75005 Paris, France;
| | - Adrienn Szabó
- Institute of Experimental Medicine, 1083 Budapest, Hungary; (C.L.F.); (A.S.); (B.T.); (K.B.); (P.C.); (T.C.)
- Centre for Neuroscience, Szentágothai Research Centre, Institute of Physiology, Medical School, University of Pécs, 7624 Pécs, Hungary
- János Szentágothai Doctoral School of Neurosciences, Semmelweis University, 1085 Budapest, Hungary
| | - Bibiána Török
- Institute of Experimental Medicine, 1083 Budapest, Hungary; (C.L.F.); (A.S.); (B.T.); (K.B.); (P.C.); (T.C.)
- Centre for Neuroscience, Szentágothai Research Centre, Institute of Physiology, Medical School, University of Pécs, 7624 Pécs, Hungary
- János Szentágothai Doctoral School of Neurosciences, Semmelweis University, 1085 Budapest, Hungary
| | - Krisztina Bánrévi
- Institute of Experimental Medicine, 1083 Budapest, Hungary; (C.L.F.); (A.S.); (B.T.); (K.B.); (P.C.); (T.C.)
| | - Pedro Correia
- Institute of Experimental Medicine, 1083 Budapest, Hungary; (C.L.F.); (A.S.); (B.T.); (K.B.); (P.C.); (T.C.)
- Centre for Neuroscience, Szentágothai Research Centre, Institute of Physiology, Medical School, University of Pécs, 7624 Pécs, Hungary
- János Szentágothai Doctoral School of Neurosciences, Semmelweis University, 1085 Budapest, Hungary
| | - Tiago Chaves
- Institute of Experimental Medicine, 1083 Budapest, Hungary; (C.L.F.); (A.S.); (B.T.); (K.B.); (P.C.); (T.C.)
- Centre for Neuroscience, Szentágothai Research Centre, Institute of Physiology, Medical School, University of Pécs, 7624 Pécs, Hungary
- János Szentágothai Doctoral School of Neurosciences, Semmelweis University, 1085 Budapest, Hungary
| | - Stéphanie Daumas
- Neuroscience Paris Seine-Institut de Biologie Paris Seine (NPS-IBPS) INSERM, Sorbonne Université, CNRS, 75005 Paris, France;
| | - Dóra Zelena
- Institute of Experimental Medicine, 1083 Budapest, Hungary; (C.L.F.); (A.S.); (B.T.); (K.B.); (P.C.); (T.C.)
- Centre for Neuroscience, Szentágothai Research Centre, Institute of Physiology, Medical School, University of Pécs, 7624 Pécs, Hungary
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Beato M, Bhumbra G. Synaptic Projections of Motoneurons Within the Spinal Cord. ADVANCES IN NEUROBIOLOGY 2022; 28:151-168. [PMID: 36066825 DOI: 10.1007/978-3-031-07167-6_7] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Motoneurons have long been considered as the final common pathway of the nervous system, transmitting the neural impulses that are transduced into action.While many studies have focussed on the inputs that motoneurons receive from local circuits within the spinal cord and from other parts of the CNS, relatively few have investigated the targets of local axonal projections from motoneurons themselves, with the notable exception of those contacting Renshaw cells or other motoneurons.Recent research has not only characterised the detailed features of the excitatory connections between motoneurons and Renshaw cells but has also established that Renshaw cells are not the only target of motoneurons axons within the spinal cord. Motoneurons also form synaptic contacts with other motoneurons as well as with a subset of ventrally located V3 interneurons. These findings indicate that motoneurons cannot be simply viewed as the last relay station delivering the command drive to muscles, but perform an active role in the generation and modulation of motor patterns.
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Affiliation(s)
- Marco Beato
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, UK.
| | - Gary Bhumbra
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, UK
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Elimination of glutamatergic transmission from Hb9 interneurons does not impact treadmill locomotion. Sci Rep 2021; 11:16008. [PMID: 34362940 PMCID: PMC8346588 DOI: 10.1038/s41598-021-95143-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Accepted: 07/20/2021] [Indexed: 11/08/2022] Open
Abstract
The spinal cord contains neural circuits that can produce the rhythm and pattern of locomotor activity. It has previously been postulated that a population of glutamatergic neurons, termed Hb9 interneurons, contributes to locomotor rhythmogenesis. These neurons were identified by their expression of the homeobox gene, Hb9, which is also expressed in motor neurons. We developed a mouse line in which Cre recombinase activity is inducible in neurons expressing Hb9. We then used this line to eliminate vesicular glutamate transporter 2 from Hb9 interneurons, and found that there were no deficits in treadmill locomotion. We conclude that glutamatergic neurotransmission by Hb9 interneurons is not required for locomotor behaviour. The role of these neurons in neural circuits remains elusive.
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Löken LS, Braz JM, Etlin A, Sadeghi M, Bernstein M, Jewell M, Steyert M, Kuhn J, Hamel K, Llewellyn-Smith IJ, Basbaum A. Contribution of dorsal horn CGRP-expressing interneurons to mechanical sensitivity. eLife 2021; 10:e59751. [PMID: 34061020 PMCID: PMC8245130 DOI: 10.7554/elife.59751] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2020] [Accepted: 05/29/2021] [Indexed: 11/13/2022] Open
Abstract
Primary sensory neurons are generally considered the only source of dorsal horn calcitonin gene-related peptide (CGRP), a neuropeptide critical to the transmission of pain messages. Using a tamoxifen-inducible CalcaCreER transgenic mouse, here we identified a distinct population of CGRP-expressing excitatory interneurons in lamina III of the spinal cord dorsal horn and trigeminal nucleus caudalis. These interneurons have spine-laden, dorsally directed, dendrites, and ventrally directed axons. As under resting conditions, CGRP interneurons are under tonic inhibitory control, neither innocuous nor noxious stimulation provoked significant Fos expression in these neurons. However, synchronous, electrical non-nociceptive Aβ primary afferent stimulation of dorsal roots depolarized the CGRP interneurons, consistent with their receipt of a VGLUT1 innervation. On the other hand, chemogenetic activation of the neurons produced a mechanical hypersensitivity in response to von Frey stimulation, whereas their caspase-mediated ablation led to mechanical hyposensitivity. Finally, after partial peripheral nerve injury, innocuous stimulation (brush) induced significant Fos expression in the CGRP interneurons. These findings suggest that CGRP interneurons become hyperexcitable and contribute either to ascending circuits originating in deep dorsal horn or to the reflex circuits in baseline conditions, but not in the setting of nerve injury.
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Affiliation(s)
- Line S Löken
- Department of Anatomy, University California, San FranciscoSan FranciscoUnited States
| | - Joao M Braz
- Department of Anatomy, University California, San FranciscoSan FranciscoUnited States
| | - Alexander Etlin
- Department of Anatomy, University California, San FranciscoSan FranciscoUnited States
| | - Mahsa Sadeghi
- Department of Anatomy, University California, San FranciscoSan FranciscoUnited States
| | - Mollie Bernstein
- Department of Anatomy, University California, San FranciscoSan FranciscoUnited States
| | - Madison Jewell
- Department of Anatomy, University California, San FranciscoSan FranciscoUnited States
| | - Marilyn Steyert
- Department of Anatomy, University California, San FranciscoSan FranciscoUnited States
| | - Julia Kuhn
- Department of Anatomy, University California, San FranciscoSan FranciscoUnited States
| | - Katherine Hamel
- Department of Anatomy, University California, San FranciscoSan FranciscoUnited States
| | - Ida J Llewellyn-Smith
- Discipline of Physiology, Adelaide Medical School, University of AdelaideAdelaideAustralia
- Department of Cardiology, Flinders Medical CentreBedford ParkAustralia
| | - Allan Basbaum
- Department of Anatomy, University California, San FranciscoSan FranciscoUnited States
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Rodríguez-Campuzano AG, Ortega A. Glutamate transporters: Critical components of glutamatergic transmission. Neuropharmacology 2021; 192:108602. [PMID: 33991564 DOI: 10.1016/j.neuropharm.2021.108602] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Revised: 04/09/2021] [Accepted: 04/27/2021] [Indexed: 02/06/2023]
Abstract
Glutamate is the major excitatory neurotransmitter in the vertebrate central nervous system. Once released, it binds to specific membrane receptors and transporters activating a wide variety of signal transduction cascades, as well as its removal from the synaptic cleft in order to avoid its extracellular accumulation and the overstimulation of extra-synaptic receptors that might result in neuronal death through a process known as excitotoxicity. Although neurodegenerative diseases are heterogenous in clinical phenotypes and genetic etiologies, a fundamental mechanism involved in neuronal degeneration is excitotoxicity. Glutamate homeostasis is critical for brain physiology and Glutamate transporters are key players in maintaining low extracellular Glutamate levels. Therefore, the characterization of Glutamate transporters has been an active area of glutamatergic research for the last 40 years. Transporter activity its regulated at different levels: transcriptional and translational control, transporter protein trafficking and membrane mobility, and through extensive post-translational modifications. The elucidation of these mechanisms has emerged as an important piece to shape our current understanding of glutamate actions in the nervous system.
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Affiliation(s)
- Ada G Rodríguez-Campuzano
- Departamento de Toxicología, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Apartado Postal 14-740, Ciudad de México, 07000, Mexico
| | - Arturo Ortega
- Departamento de Toxicología, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Apartado Postal 14-740, Ciudad de México, 07000, Mexico.
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Cho YS, Ko HG, Han HM, Park SK, Moozhayil SJ, Choi SY, Bae YC. Vesicular glutamate transporter-immunopositive axons that coexpress neuropeptides in the rat and human dental pulp. Int Endod J 2020; 54:377-387. [PMID: 33090483 DOI: 10.1111/iej.13427] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2020] [Revised: 10/05/2020] [Accepted: 10/05/2020] [Indexed: 12/17/2022]
Abstract
AIM To examine the type of vesicular glutamate transporter (VGLUT)-immunopositive (+) axons that coexpress neuropeptides in the rat and human dental pulp, which may help understand peripheral mechanism of pulpal inflammatory pain in rats and humans. METHODOLOGY The trigeminal ganglia (TG) and the dental pulp of the maxillary molar teeth from three male Sprague-Dawley rats weighing 300-330 g and dental pulps of three healthy human (male) maxillary premolar teeth from three 16 to 28-year-old patients extracted for orthodontic treatment were used. The type of VGLUT + axons that coexpress substance P (SP)- and/or calcitonin gene-related peptide (CGRP) and parvalbumin in the rat TG and in the axons of the rat and the human dental pulp was examined by double fluorescence immunohistochemistry and quantitative analysis. Results were analyzed using one-way anova and the Kruskal-Wallis test. RESULTS SP and CGRP were expressed in many human VGLUT1 + pulpal axons but not in the rat VGLUT1 + TG neurons and pulpal axons (P < 0.05). SP and CGRP were expressed in a considerable number of human VGLUT2 + pulpal axons and also in many rat TG neurons and pulpal axons. The fraction of VGLUT1 + axons expressing parvalbumin was about three times higher in the rat than in the human dental pulp (P < 0.05). CONCLUSIONS These findings suggest that the types of VGLUT + axons, which release neuropeptides, may be different between the rat and the human dental pulp, raising a possibility that peripheral mechanism of pulpal inflammatory pain may be different between rats and humans.
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Affiliation(s)
- Y S Cho
- Department of Anatomy and Neurobiology, School of Dentistry, Kyungpook National University, Daegu, South Korea
| | - H G Ko
- Department of Anatomy and Neurobiology, School of Dentistry, Kyungpook National University, Daegu, South Korea
| | - H M Han
- Department of Anatomy and Neurobiology, School of Dentistry, Kyungpook National University, Daegu, South Korea
| | - S K Park
- Department of Anatomy and Neurobiology, School of Dentistry, Kyungpook National University, Daegu, South Korea
| | - S J Moozhayil
- Department of Anatomy and Neurobiology, School of Dentistry, Kyungpook National University, Daegu, South Korea
| | - S Y Choi
- Department of Oral & Maxillofacial Surgery, School of Dentistry, Kyungpook National University, Daegu, South Korea
| | - Y C Bae
- Department of Anatomy and Neurobiology, School of Dentistry, Kyungpook National University, Daegu, South Korea
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Hu QX, Klatt GM, Gudmundsrud R, Ottestad-Hansen S, Verbruggen L, Massie A, Danbolt NC, Zhou Y. Semi-quantitative distribution of excitatory amino acid (glutamate) transporters 1–3 (EAAT1-3) and the cystine-glutamate exchanger (xCT) in the adult murine spinal cord. Neurochem Int 2020; 140:104811. [DOI: 10.1016/j.neuint.2020.104811] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Revised: 06/21/2020] [Accepted: 07/09/2020] [Indexed: 01/01/2023]
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12
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Leiguarda C, McCarthy CJ, Casadei M, Lundgren KH, Coronel MF, Trigosso-Venario H, Seal RP, Seroogy KB, Brumovsky PR. Transcript Expression of Vesicular Glutamate Transporters in Rat Dorsal Root Ganglion and Spinal Cord Neurons: Impact of Spinal Blockade during Hindpaw Inflammation. ACS Chem Neurosci 2020; 11:2602-2614. [PMID: 32697906 DOI: 10.1021/acschemneuro.0c00272] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Studies in mouse, and to a lesser extent in rat, have revealed the neuroanatomical distribution of vesicular glutamate transporters (VGLUTs) and begun exposing the critical role of VGLUT2 and VGLUT3 in pain transmission. In the present study in rat, we used specific riboprobes to characterize the transcript expression of all three VGLUTs in lumbar dorsal root ganglia (DRGs) and in the thoracolumbar, lumbar, and sacral spinal cord. We show for the first time in rat a very discrete VGLUT3 expression in DRGs and in deep layers of the dorsal horn. We confirm the abundant expression of VGLUT2, in both DRGs and the spinal cord, including presumable motorneurons in the latter. As expected, VGLUT1 was present in many DRG neuron profiles, and in the spinal cord it was mostly localized to neurons in the dorsal nucleus of Clarke. In rats with a 10 day long hindpaw inflammation, increased spinal expression of VGLUT2 transcript was detected by qRT-PCR, and intrathecal administration of the nonselective VGLUT inhibitor Chicago Sky Blue 6B resulted in reduced mechanical and thermal allodynia for up to 24 h. In conclusion, our results provide a collective characterization of VGLUTs in rat DRGs and the spinal cord, demonstrate increased spinal expression of VGLUT2 during chronic peripheral inflammation, and support the use of spinal VGLUT blockade as a strategy for attenuating inflammatory pain.
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Affiliation(s)
- Candelaria Leiguarda
- Instituto de Investigaciones en Medicina Traslacional (IIMT), CONICET-Austral, Derqui, Pilar B1629AHJ, Buenos Aires, Argentina
| | - Carly J. McCarthy
- Instituto de Investigaciones en Medicina Traslacional (IIMT), CONICET-Austral, Derqui, Pilar B1629AHJ, Buenos Aires, Argentina
| | - Mailin Casadei
- Instituto de Investigaciones en Medicina Traslacional (IIMT), CONICET-Austral, Derqui, Pilar B1629AHJ, Buenos Aires, Argentina
| | - Kerstin H. Lundgren
- Department of Neurology, University of Cincinnati, Cincinnati, Ohio 45267, United States
| | - María Florencia Coronel
- Instituto de Investigaciones en Medicina Traslacional (IIMT), CONICET-Austral, Derqui, Pilar B1629AHJ, Buenos Aires, Argentina
| | - Harry Trigosso-Venario
- Hospital Universitario Austral, Austral University, Pilar B1629AHJ, Buenos Aires, Argentina
| | - Rebecca P. Seal
- Pittsburgh Center for Pain Research, Department of Neurobiology, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, United States
| | - Kim B. Seroogy
- Department of Neurology, University of Cincinnati, Cincinnati, Ohio 45267, United States
| | - Pablo R. Brumovsky
- Instituto de Investigaciones en Medicina Traslacional (IIMT), CONICET-Austral, Derqui, Pilar B1629AHJ, Buenos Aires, Argentina
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Abo-Ahmed AI, Emam MA. Expression of vesicular glutamate transporter 2 and 3 and glutamate receptor 1 and 2 mRNAs in the retina of adult laughing doves (Streptopelia senegalensis): An in situ hybridization study. Acta Histochem 2020; 122:151597. [PMID: 32778249 DOI: 10.1016/j.acthis.2020.151597] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Revised: 07/12/2020] [Accepted: 07/13/2020] [Indexed: 10/23/2022]
Abstract
The retina possesses few types of neurons so; it is considered an excellent model for understanding the neural mechanisms underlying basic neural information processing in the brain. Glutamate is the major excitatory neurotransmitter in the vertebrate central nervous system and retina. The present study was carried out to characterize the expression pattern of vesicular glutamate transporter 2 (Vglut2) and 3 (Vglut3) and glutamate receptor 1 (GluR1) and 2 (GluR2) mRNAs in the retina of adult laughing dove (Streptopelia senegalensis) by RT-PCR and in situ hybridization histochemistry. The cerebellum of adult laughing dove was used as a positive control in this study. Vglut2 mRNA was highly expressed only in the granular layer of the cerebellum while Vglut3 mRNA was weakly expressed only in the Purkinje cells layer. In the retina, Vglut2 mRNA was highly expressed in the ganglion cell layer and moderately expressed in the inner nuclear layer while Vglut3 mRNA was moderately expressed only in the inner nuclear layer. GluR1 mRNA was intensely expressed in the Purkinje cells layer while GluR2 mRNA signals were highly detectable in both granular and Purkinje cells layers of the cerebellum. In the retina, moderate expression of GluR1 and intense expression of GluR2 was found in both ganglion cell layer and the internal half of inner nuclear layer mostly amacrine cells. These results suggest that some retinal neuronal cells in the adult laughing dove are glutamatergic. Therefore, GluR1 and 2 are suggested as useful markers for glutamatergic retinal neuronal cells in the adult laughing doves.
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14
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Rana S, Zhan WZ, Mantilla CB, Sieck GC. Disproportionate loss of excitatory inputs to smaller phrenic motor neurons following cervical spinal hemisection. J Physiol 2020; 598:4693-4711. [PMID: 32735344 DOI: 10.1113/jp280130] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Accepted: 07/20/2020] [Indexed: 12/18/2022] Open
Abstract
KEY POINTS Motor units, comprising a motor neuron and the muscle fibre it innervates, are activated in an orderly fashion to provide varying amounts of force. A unilateral C2 spinal hemisection (C2SH) disrupts predominant excitatory input from medulla, causing cessation of inspiratory-related diaphragm muscle activity, whereas higher force, non-ventilatory diaphragm activity persists. In this study, we show a disproportionately larger loss of excitatory glutamatergic innervation to small phrenic motor neurons (PhMNs) following C2SH, as compared with large PhMNs ipsilateral to injury. Our data suggest that there is a dichotomy in the distribution of inspiratory-related descending excitatory glutamatergic input to small vs. large PhMNs that reflects their differential recruitment. ABSTRACT Excitatory glutamatergic input mediating inspiratory drive to phrenic motor neurons (PhMNs) emanates primarily from the ipsilateral ventrolateral medulla. Unilateral C2 hemisection (C2SH) disrupts this excitatory input, resulting in cessation of inspiratory-related diaphragm muscle (DIAm) activity. In contrast, after C2SH, higher force, non-ventilatory DIAm activity persists. Inspiratory behaviours require recruitment of only smaller PhMNs, whereas with more forceful expulsive/straining behaviours, larger PhMNs are recruited. Accordingly, we hypothesize that C2SH primarily disrupts glutamatergic synaptic inputs to smaller PhMNs, whereas glutamatergic synaptic inputs to larger PhMNs are preserved. We examined changes in glutamatergic presynaptic input onto retrogradely labelled PhMNs using immunohistochemistry for VGLUT1 and VGLUT2. We found that 7 days after C2SH there was an ∼60% reduction in glutamatergic inputs to smaller PhMNs compared with an ∼35% reduction at larger PhMNs. These results are consistent with a more pronounced impact of C2SH on inspiratory behaviours of the DIAm, and the preservation of higher force behaviours after C2SH. These results indicate that the source of glutamatergic synaptic input to PhMNs varies depending on motor neuron size and reflects different functional control - perhaps separate central pattern generator and premotor circuits. For smaller PhMNs, the central pattern generator for inspiration is located in the pre-Bötzinger complex and premotor neurons in the ventrolateral medulla, sending predominantly ipsilateral projections via the dorsolateral funiculus. C2SH disrupts this glutamatergic input. For larger PhMNs, a large proportion of excitatory inputs appear to exist below the C2 level or from contralateral regions of the brainstem and spinal cord.
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Affiliation(s)
- Sabhya Rana
- Departments of Physiology & Biomedical Engineering and
| | - Wen-Zhi Zhan
- Departments of Physiology & Biomedical Engineering and
| | - Carlos B Mantilla
- Departments of Physiology & Biomedical Engineering and.,Anaesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, MN
| | - Gary C Sieck
- Departments of Physiology & Biomedical Engineering and.,Anaesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, MN
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15
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Differential expression of Na +/K +/Cl - cotransporter 1 in neurons and glial cells within the superficial spinal dorsal horn of rodents. Sci Rep 2020; 10:11715. [PMID: 32678166 PMCID: PMC7367302 DOI: 10.1038/s41598-020-68638-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2020] [Accepted: 06/30/2020] [Indexed: 12/30/2022] Open
Abstract
Although convincing experimental evidence indicates that Na+/K+/Cl- cotransporter 1 (NKCC1) is involved in spinal nociceptive information processing and in the generation of hyperalgesia and allodynia in chronic pain states, the cellular distribution of NKCC1 in the superficial spinal dorsal horn is still poorly understood. Because this important piece of knowledge is missing, the effect of NKCC1 on pain processing is still open to conflicting interpretations. In this study, to provide the missing experimental data, we investigated the cellular distribution of NKCC1 in the superficial spinal dorsal horn by immunohistochemical methods. We demonstrated for the first time that almost all spinal axon terminals of peptidergic nociceptive primary afferents express NKCC1. In contrast, virtually all spinal axon terminals of nonpeptidergic nociceptive primary afferents were negative for NKCC1. Data on the colocalization of NKCC1 with axonal and glial markers indicated that it is almost exclusively expressed by axon terminals and glial cells in laminae I-IIo. In lamina IIi, however, we observed a strong immunostaining for NKCC1 also in the dendrites and cell bodies of PV-containing inhibitory neurons and a weak staining in PKCγ-containing excitatory neurons. Our results facilitate further thinking about the role of NKCC1 in spinal pain processing.
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16
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Pietrancosta N, Djibo M, Daumas S, El Mestikawy S, Erickson JD. Molecular, Structural, Functional, and Pharmacological Sites for Vesicular Glutamate Transporter Regulation. Mol Neurobiol 2020; 57:3118-3142. [PMID: 32474835 PMCID: PMC7261050 DOI: 10.1007/s12035-020-01912-7] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Accepted: 03/30/2020] [Indexed: 12/11/2022]
Abstract
Vesicular glutamate transporters (VGLUTs) control quantal size of glutamatergic transmission and have been the center of numerous studies over the past two decades. VGLUTs contain two independent transport modes that facilitate glutamate packaging into synaptic vesicles and phosphate (Pi) ion transport into the synaptic terminal. While a transmembrane proton electrical gradient established by a vacuolar-type ATPase powers vesicular glutamate transport, recent studies indicate that binding sites and flux properties for chloride, potassium, and protons within VGLUTs themselves regulate VGLUT activity as well. These intrinsic ionic binding and flux properties of VGLUTs can therefore be modulated by neurophysiological conditions to affect levels of glutamate available for release from synapses. Despite their extraordinary importance, specific and high-affinity pharmacological compounds that interact with these sites and regulate VGLUT function, distinguish between the various modes of transport, and the different isoforms themselves, are lacking. In this review, we provide an overview of the physiologic sites for VGLUT regulation that could modulate glutamate release in an over-active synapse or in a disease state.
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Affiliation(s)
- Nicolas Pietrancosta
- Neuroscience Paris Seine - Institut de Biologie Paris Seine (NPS - IBPS) INSERM, CNRS, Sorbonne Université, Paris, France. .,Laboratoire des Biomolécules, Sorbonne Université, CNRS, ENS, LBM, 75005, Paris, France.
| | - Mahamadou Djibo
- Sorbonne Paris Cité, Université Paris Descartes, LCBPT, UMR 8601, 75006, Paris, France
| | - Stephanie Daumas
- Neuroscience Paris Seine - Institut de Biologie Paris Seine (NPS - IBPS) INSERM, CNRS, Sorbonne Université, Paris, France
| | - Salah El Mestikawy
- Neuroscience Paris Seine - Institut de Biologie Paris Seine (NPS - IBPS) INSERM, CNRS, Sorbonne Université, Paris, France. .,Douglas Hospital Research Center, Department of Psychiatry, McGill University, 6875 boulevard Lasalle, Verdun, Montreal, QC, Canada.
| | - Jeffrey D Erickson
- Neuroscience Center, Louisiana State University, New Orleans, LA, 70112, USA. .,Department of Pharmacology, Louisiana State University, New Orleans, LA, 70112, USA.
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17
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Tudeau L, Acuña MA, Albisetti GW, Neumann E, Ralvenius WT, Scheurer L, Poe M, Cook JM, Johannssen HC, Zeilhofer HU. Mice lacking spinal α2GABA A receptors: Altered GABAergic neurotransmission, diminished GABAergic antihyperalgesia, and potential compensatory mechanisms preventing a hyperalgesic phenotype. Brain Res 2020; 1741:146889. [PMID: 32439345 DOI: 10.1016/j.brainres.2020.146889] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Revised: 04/24/2020] [Accepted: 05/12/2020] [Indexed: 12/11/2022]
Abstract
Diminished synaptic inhibition in the superficial spinal dorsal horn contributes to exaggerated pain responses that accompany peripheral inflammation and neuropathy. α2GABAA receptors (α2GABAAR) constitute the most abundant GABAAR subtype at this site and are the targets of recently identified antihyperalgesic compounds. Surprisingly, hoxb8-α2-/- mice that lack α2GABAAR from the spinal cord and peripheral sensory neurons exhibit unaltered sensitivity to acute painful stimuli and develop normal inflammatory and neuropathic hyperalgesia. Here, we provide a comprehensive analysis of GABAergic neurotransmission, of behavioral phenotypes and of possible compensatory mechanisms in hoxb8-α2-/- mice. Our results confirm that hoxb8-α2-/- mice show significantly diminished GABAergic inhibitory postsynaptic currents (IPSCs) in the superficial dorsal horn but no hyperalgesic phenotype. We also confirm that the potentiation of dorsal horn GABAergic IPSCs by the α2-preferring GABAAR modulator HZ-166 is reduced in hoxb8-α2-/- mice and that hoxb8-α2-/- mice are resistant to the analgesic effects of HZ-166. Tonic GABAergic currents, glycinergic IPSCs, and sensory afferent-evoked EPSCs did not show significant changes in hoxb8-α2-/- mice rendering a compensatory up-regulation of other GABAAR subtypes or of glycine receptors unlikely. Although expression of serotonin and of the serotonin producing enzyme tryptophan hydroxylase (TPH2) was significantly increased in the dorsal horn of hoxb8-α2-/- mice, ablation of serotonergic terminals from the lumbar spinal cord failed to unmask a nociceptive phenotype. Our results are consistent with an important contribution of α2GABAAR to spinal nociceptive control but their ablation early in development appears to activate yet-to-be identified compensatory mechanisms that protect hoxb8-α2-/- mice from hyperalgesia.
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Affiliation(s)
- Laetitia Tudeau
- Institute of Pharmacology and Toxicology, University of Zurich, CH-8057 Zurich, Switzerland
| | - Mario A Acuña
- Institute of Pharmacology and Toxicology, University of Zurich, CH-8057 Zurich, Switzerland
| | - Gioele W Albisetti
- Institute of Pharmacology and Toxicology, University of Zurich, CH-8057 Zurich, Switzerland
| | - Elena Neumann
- Institute of Pharmacology and Toxicology, University of Zurich, CH-8057 Zurich, Switzerland
| | - William T Ralvenius
- Institute of Pharmacology and Toxicology, University of Zurich, CH-8057 Zurich, Switzerland
| | - Louis Scheurer
- Institute of Pharmacology and Toxicology, University of Zurich, CH-8057 Zurich, Switzerland
| | - Michael Poe
- Department of Chemistry and Biochemistry, University of Wisconsin-Milwaukee, Milwaukee, USA
| | - James M Cook
- Department of Chemistry and Biochemistry, University of Wisconsin-Milwaukee, Milwaukee, USA
| | - Helge C Johannssen
- Institute of Pharmacology and Toxicology, University of Zurich, CH-8057 Zurich, Switzerland
| | - Hanns Ulrich Zeilhofer
- Institute of Pharmacology and Toxicology, University of Zurich, CH-8057 Zurich, Switzerland; Institute of Pharmaceutical Sciences, Swiss Federal Institute of Technology (ETH) Zurich, CH-8093 Zurich, Switzerland.
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18
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Godinho MJ, Staal JL, Krishnan VS, Hodgetts SI, Pollett MA, Goodman DP, Teh L, Verhaagen J, Plant GW, Harvey AR. Regeneration of adult rat sensory and motor neuron axons through chimeric peroneal nerve grafts containing donor Schwann cells engineered to express different neurotrophic factors. Exp Neurol 2020; 330:113355. [PMID: 32422148 DOI: 10.1016/j.expneurol.2020.113355] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Revised: 04/28/2020] [Accepted: 05/04/2020] [Indexed: 11/18/2022]
Abstract
Large peripheral nerve (PN) defects require bridging substrates to restore tissue continuity and permit the regrowth of sensory and motor axons. We previously showed that cell-free PN segments repopulated ex vivo with Schwann cells (SCs) transduced with lentiviral vectors (LV) to express different growth factors (BDNF, CNTF or NT-3) supported the regeneration of axons across a 1 cm peroneal nerve defect (Godinho et al., 2013). Graft morphology, the number of regrown axons, the ratio of myelinated to unmyelinated axons, and hindlimb locomotor function differed depending on the growth factor engineered into SCs. Here we extend these observations, adding more LVs (expressing GDNF or NGF) and characterising regenerating sensory and motor neurons after injection of the retrograde tracer Fluorogold (FG) into peroneal nerve distal to grafts, 10 weeks after surgery. Counts were also made in rats with intact nerves and in animals receiving autografts, acellular grafts, or grafts containing LV-GFP transduced SCs. Counts and analysis of FG positive (+) DRG neurons were made from lumbar (L5) ganglia. Graft groups contained fewer labeled sensory neurons than non-operated controls, but this decrease was only significant in the LV-GDNF group. These grafts had a complex fascicular morphology that may have resulted in axon trapping. The proportion of FG+ sensory neurons immunopositive for calcitonin-gene related peptide (CGRP) varied between groups, there being a significantly higher percentage in autografts and most neurotrophic factor groups compared to the LV-CNTF, LV-GFP and acellular groups. Furthermore, the proportion of regenerating isolectin B4+ neurons was significantly greater in the LV-NT-3 group compared to other groups, including autografts and non-lesion controls. Immunohistochemical analysis of longitudinal graft sections revealed that all grafts contained a reduced number of choline acetyltransferase (ChAT) positive axons, but this decrease was significant only in the GDNF and NT-3 graft groups. We also assessed the number and phenotype of regrowing lumbar FG+ motor neurons in non-lesioned animals, and in rats with autografts, acellular grafts, or in grafts containing SCs expressing GFP, CNTF, NGF or NT-3. The overall number of FG+ motor neurons per section was similar in all groups; however in tissue immunostained for NeuN (expressed in α- but not γ-motor neurons) the proportion of NeuN negative FG+ neurons ranged from about 40-50% in all groups except the NT-3 group, where the percentage was 82%, significantly more than the SC-GFP group. Immunostaining for the vesicular glutamate transporter VGLUT-1 revealed occasional proprioceptive terminals in 'contact' with regenerating FG+ α-motor neurons in PN grafted animals, the acellular group having the lowest counts. In sum, while all graft types supported sensory and motor axon regrowth, there appeared to be axon trapping in SC-GDNF grafts, and data from the SC-NT-3 group revealed greater regeneration of sensory CGRP+ and IB4+ neurons, preferential regeneration of γ-motor neurons and perhaps partial restoration of monosynaptic sensorimotor relays.
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Affiliation(s)
- Maria João Godinho
- School of Human Sciences, The University of Western Australia, Crawley, WA 6009, Australia
| | - Jonas L Staal
- School of Human Sciences, The University of Western Australia, Crawley, WA 6009, Australia
| | - Vidya S Krishnan
- School of Human Sciences, The University of Western Australia, Crawley, WA 6009, Australia
| | - Stuart I Hodgetts
- School of Human Sciences, The University of Western Australia, Crawley, WA 6009, Australia; Perron Institute for Neurological and Translational Science, Nedlands, WA 6009, Australia
| | - Margaret A Pollett
- School of Human Sciences, The University of Western Australia, Crawley, WA 6009, Australia
| | - Douglas P Goodman
- School of Veterinary and Biomedical Sciences, Murdoch University, Murdoch, WA 6150, Australia
| | - Lip Teh
- Plastic Surgery Centre, St John of God Hospital, Murdoch, WA 6150, Australia
| | - Joost Verhaagen
- Netherlands Institute for Neuroscience, Meibergdreef 47, Amsterdam, the Netherlands
| | - Giles W Plant
- Department of Neurosurgery, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Alan R Harvey
- School of Human Sciences, The University of Western Australia, Crawley, WA 6009, Australia; Perron Institute for Neurological and Translational Science, Nedlands, WA 6009, Australia.
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19
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Peirs C, Dallel R, Todd AJ. Recent advances in our understanding of the organization of dorsal horn neuron populations and their contribution to cutaneous mechanical allodynia. J Neural Transm (Vienna) 2020; 127:505-525. [PMID: 32239353 PMCID: PMC7148279 DOI: 10.1007/s00702-020-02159-1] [Citation(s) in RCA: 66] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Accepted: 02/10/2020] [Indexed: 02/07/2023]
Abstract
The dorsal horns of the spinal cord and the trigeminal nuclei in the brainstem contain neuron populations that are critical to process sensory information. Neurons in these areas are highly heterogeneous in their morphology, molecular phenotype and intrinsic properties, making it difficult to identify functionally distinct cell populations, and to determine how these are engaged in pathophysiological conditions. There is a growing consensus concerning the classification of neuron populations, based on transcriptomic and transductomic analyses of the dorsal horn. These approaches have led to the discovery of several molecularly defined cell types that have been implicated in cutaneous mechanical allodynia, a highly prevalent and difficult-to-treat symptom of chronic pain, in which touch becomes painful. The main objective of this review is to provide a contemporary view of dorsal horn neuronal populations, and describe recent advances in our understanding of on how they participate in cutaneous mechanical allodynia.
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Affiliation(s)
- Cedric Peirs
- Université Clermont Auvergne, CHU Clermont-Ferrand, Inserm, Neuro-Dol, Clermont-Ferrand, F-63000, France.
- Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, G12 8QQ, UK.
| | - Radhouane Dallel
- Université Clermont Auvergne, CHU Clermont-Ferrand, Inserm, Neuro-Dol, Clermont-Ferrand, F-63000, France
- Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Andrew J Todd
- Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, G12 8QQ, UK
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20
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Leyva-Díaz E, Masoudi N, Serrano-Saiz E, Glenwinkel L, Hobert O. Brn3/POU-IV-type POU homeobox genes-Paradigmatic regulators of neuronal identity across phylogeny. WILEY INTERDISCIPLINARY REVIEWS-DEVELOPMENTAL BIOLOGY 2020; 9:e374. [PMID: 32012462 DOI: 10.1002/wdev.374] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2019] [Revised: 12/18/2019] [Accepted: 01/07/2020] [Indexed: 02/06/2023]
Abstract
One approach to understand the construction of complex systems is to investigate whether there are simple design principles that are commonly used in building such a system. In the context of nervous system development, one may ask whether the generation of its highly diverse sets of constituents, that is, distinct neuronal cell types, relies on genetic mechanisms that share specific common features. Specifically, are there common patterns in the function of regulatory genes across different neuron types and are those regulatory mechanisms not only used in different parts of one nervous system, but are they conserved across animal phylogeny? We address these questions here by focusing on one specific, highly conserved and well-studied regulatory factor, the POU homeodomain transcription factor UNC-86. Work over the last 30 years has revealed a common and paradigmatic theme of unc-86 function throughout most of the neuron types in which Caenorhabditis elegans unc-86 is expressed. Apart from its role in preventing lineage reiterations during development, UNC-86 operates in combination with distinct partner proteins to initiate and maintain terminal differentiation programs, by coregulating a vast array of functionally distinct identity determinants of specific neuron types. Mouse orthologs of unc-86, the Brn3 genes, have been shown to fulfill a similar function in initiating and maintaining neuronal identity in specific parts of the mouse brain and similar functions appear to be carried out by the sole Drosophila ortholog, Acj6. The terminal selector function of UNC-86 in many different neuron types provides a paradigm for neuronal identity regulation across phylogeny. This article is categorized under: Gene Expression and Transcriptional Hierarchies > Regulatory Mechanisms Invertebrate Organogenesis > Worms Nervous System Development > Vertebrates: Regional Development.
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Affiliation(s)
- Eduardo Leyva-Díaz
- Department of Biological Sciences, Howard Hughes Medical Institute, Columbia University, New York, New York
| | - Neda Masoudi
- Department of Biological Sciences, Howard Hughes Medical Institute, Columbia University, New York, New York
| | | | - Lori Glenwinkel
- Department of Biological Sciences, Howard Hughes Medical Institute, Columbia University, New York, New York
| | - Oliver Hobert
- Department of Biological Sciences, Howard Hughes Medical Institute, Columbia University, New York, New York
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21
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Wang Y, Wu H, Zelenin P, Fontanet P, Wanderoy S, Petitpré C, Comai G, Bellardita C, Xue-Franzén Y, Huettl RE, Huber AB, Tajbakhsh S, Kiehn O, Ernfors P, Deliagina TG, Lallemend F, Hadjab S. Muscle-selective RUNX3 dependence of sensorimotor circuit development. Development 2019; 146:dev.181750. [PMID: 31575648 PMCID: PMC6826036 DOI: 10.1242/dev.181750] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Accepted: 09/17/2019] [Indexed: 11/20/2022]
Abstract
The control of all our motor outputs requires constant monitoring by proprioceptive sensory neurons (PSNs) that convey continuous muscle sensory inputs to the spinal motor network. Yet the molecular programs that control the establishment of this sensorimotor circuit remain largely unknown. The transcription factor RUNX3 is essential for the early steps of PSNs differentiation, making it difficult to study its role during later aspects of PSNs specification. Here, we conditionally inactivate Runx3 in PSNs after peripheral innervation and identify that RUNX3 is necessary for maintenance of cell identity of only a subgroup of PSNs, without discernable cell death. RUNX3 also controls the sensorimotor connection between PSNs and motor neurons at limb level, with muscle-by-muscle variable sensitivities to the loss of Runx3 that correlate with levels of RUNX3 in PSNs. Finally, we find that muscles and neurotrophin 3 signaling are necessary for maintenance of RUNX3 expression in PSNs. Hence, a transcriptional regulator that is crucial for specifying a generic PSN type identity after neurogenesis is later regulated by target muscle-derived signals to contribute to the specialized aspects of the sensorimotor connection selectivity.
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Affiliation(s)
- Yiqiao Wang
- Department of Neuroscience, Karolinska Institutet, Stockholm 17177, Sweden
| | - Haohao Wu
- Department of Neuroscience, Karolinska Institutet, Stockholm 17177, Sweden
| | - Pavel Zelenin
- Department of Neuroscience, Karolinska Institutet, Stockholm 17177, Sweden
| | - Paula Fontanet
- Department of Neuroscience, Karolinska Institutet, Stockholm 17177, Sweden
| | - Simone Wanderoy
- Department of Neuroscience, Karolinska Institutet, Stockholm 17177, Sweden
| | - Charles Petitpré
- Department of Neuroscience, Karolinska Institutet, Stockholm 17177, Sweden
| | - Glenda Comai
- Department of Developmental and Stem Cell Biology, Institut Pasteur, CNRS UMR3738, Paris 75015, France
| | - Carmelo Bellardita
- Department of Neuroscience, University of Copenhagen, Copenhagen 2200, Denmark
| | | | - Rosa-Eva Huettl
- Helmholtz Zentrum München, German Research Center for Environmental Health, Institute of Developmental Genetics, Neuherberg 85764, Germany
| | - Andrea B Huber
- Helmholtz Zentrum München, German Research Center for Environmental Health, Institute of Developmental Genetics, Neuherberg 85764, Germany
| | - Shahragim Tajbakhsh
- Department of Developmental and Stem Cell Biology, Institut Pasteur, CNRS UMR3738, Paris 75015, France
| | - Ole Kiehn
- Department of Neuroscience, Karolinska Institutet, Stockholm 17177, Sweden.,Department of Neuroscience, University of Copenhagen, Copenhagen 2200, Denmark
| | - Patrik Ernfors
- Unit of Molecular Neurobiology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm 17177, Sweden
| | | | - François Lallemend
- Department of Neuroscience, Karolinska Institutet, Stockholm 17177, Sweden .,Ming Wai Lau Centre for Reparative Medicine, Stockholm node, Karolinska Institutet, Stockholm 17177, Sweden
| | - Saida Hadjab
- Department of Neuroscience, Karolinska Institutet, Stockholm 17177, Sweden
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22
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Grycz K, Głowacka A, Ji B, Czarkowska-Bauch J, Gajewska-Woźniak O, Skup M. Early pre- and postsynaptic decrease in glutamatergic and cholinergic signaling after spinalization is not modified when stimulating proprioceptive input to the ankle extensor α-motoneurons: Anatomical and neurochemical study. PLoS One 2019; 14:e0222849. [PMID: 31557259 PMCID: PMC6763201 DOI: 10.1371/journal.pone.0222849] [Citation(s) in RCA: 4] [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: 03/09/2019] [Accepted: 09/08/2019] [Indexed: 12/23/2022] Open
Abstract
Alpha-motoneurons (MNs) innervating ankle extensor muscles show reduced peripheral inputs from Ia proprioceptive afferents and cholinergic afferents after chronic spinalization (SCT). That phenomenon is not observed on ankle flexor MNs, indicating a smaller vulnerability of the latter MNs circuit to SCT. Locomotor training of spinal rats which partially restored those inputs to extensor MNs tended to hyper innervate flexor MNs, disclosing a need for selective approaches. In rats with intact spinal cord 7-days of low-threshold proprioceptive stimulation of the tibial nerve enriched glutamatergic Ia and cholinergic innervation of lateral gastrocnemius (LG) MNs, suggesting usefulness of selective stimulation for restoration of inputs to extensor MNs after SCT. Accordingly, to examine its effectiveness after SCT, tibial nerves and soleus muscles were implanted bilaterally, and for MN identification fluorescence tracers to LG and tibialis anterior (TA) muscles were injected two weeks prior to spinalization. Stimulation of tibial nerve, controlled by H-reflex recorded in the soleus muscle, started on the third post-SCT day and continued for 7 days. Nine days post-SCT the number and volume of glutamatergic Ia and of cholinergic C-boutons on LG MNs was decreased, but stimulation affected neither of them. Postsynaptically, a threefold decrease of NMDAR NR1 subunit and thirtyfold decrease of M2 muscarinic receptor transcripts caused by SCT were not counteracted by stimulation, whereas a threefold decrease of AMPAR GluR2 subunit tended to deepen after stimulation. We conclude that LG MNs, supported with proprioceptive stimuli after SCT, do not transcribe the perceived cues into compensatory response at the transcriptional level in the early post-SCT period.
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Affiliation(s)
- Kamil Grycz
- Nencki Institute of Experimental Biology, Warsaw, Poland
| | - Anna Głowacka
- Nencki Institute of Experimental Biology, Warsaw, Poland
| | - Benjun Ji
- Nencki Institute of Experimental Biology, Warsaw, Poland
| | | | | | - Małgorzata Skup
- Nencki Institute of Experimental Biology, Warsaw, Poland
- * E-mail: (OG-W); (MS)
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23
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Rana S, Mantilla CB, Sieck GC. Glutamatergic input varies with phrenic motor neuron size. J Neurophysiol 2019; 122:1518-1529. [PMID: 31389739 DOI: 10.1152/jn.00430.2019] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Like all skeletal muscles, the diaphragm muscle accomplishes a range of motor behaviors by recruiting different motor unit types in an orderly fashion. Recruitment of phrenic motor neurons (PhMNs) is generally assumed to be based primarily on the intrinsic properties of PhMNs with an equal distribution of descending excitatory inputs to all PhMNs. However, differences in presynaptic excitatory input across PhMNs of varying sizes could also contribute to the orderly recruitment pattern. In the spinal cord of Sprague-Dawley rats, we retrogradely labeled PhMNs using cholera toxin B (CTB) and validated a robust confocal imaging-based technique that utilizes semiautomated processing to identify presynaptic glutamatergic (Glu) terminals within a defined distance around the somal membrane of PhMNs of varying size. Our results revealed an ~10% higher density of Glu terminals at PhMNs in the lower tertile of somal surface area. These smaller PhMNs are likely recruited first to accomplish lower force ventilatory behaviors of the diaphragm as compared with larger PhMNs in the upper tertile that are recruited to accomplish higher force expulsive behaviors. These results suggest that differences in excitatory synaptic input to PhMNs may also contribute to the orderly recruitment of diaphragm motor units.NEW & NOTEWORTHY The distribution of excitatory glutamatergic synaptic input to phrenic motor neurons differs across motor neurons of varying size. These findings support the size principle of motor unit recruitment that underlies graded force generation in a muscle, which is based on intrinsic electrophysiological properties of motor neurons resulting from differences in somal surface area. A higher density of glutamatergic inputs at smaller, more excitable motor neurons substantiates the earlier and more frequent recruitment of these units.
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Affiliation(s)
- Sabhya Rana
- Department of Physiology & Biomedical Engineering, Mayo Clinic, Rochester, Minnesota
| | - Carlos B Mantilla
- Department of Physiology & Biomedical Engineering, Mayo Clinic, Rochester, Minnesota.,Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, Minnesota
| | - Gary C Sieck
- Department of Physiology & Biomedical Engineering, Mayo Clinic, Rochester, Minnesota.,Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, Minnesota
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24
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Castro MVD, Silva MVRD, Chiarotto GB, Volpe BB, Santana MH, Malheiros Luzo ÂC, Oliveira ALRD. Reflex arc recovery after spinal cord dorsal root repair with platelet rich plasma (PRP). Brain Res Bull 2019; 152:212-224. [PMID: 31351157 DOI: 10.1016/j.brainresbull.2019.07.024] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Revised: 07/20/2019] [Accepted: 07/22/2019] [Indexed: 02/01/2023]
Abstract
Spinal dorsal roots can be affected by a wide range of lesions, leading to a significant loss of proprioceptive information transmission and greatly affecting motor behavior. In this context, the reimplantation of lesioned roots with platelet-rich plasma (PRP) may allow nerve regeneration. Therefore, the present study evaluated sensorimotor improvement following dorsal root rhizotomy and repair with PRP. For this purpose, female Lewis rats were subjected to unilateral rhizotomy (RZ) of the L4-L6 dorsal roots and divided into the following groups: (1) the unlesioned control group; (2) the group that underwent rhizotomy (RZ) without repair; and (3) the group that underwent RZ followed by root repair with PRP. PRP was obtained from human blood and characterized regarding platelet concentration, integrity, and viability. Reflex arc recovery was evaluated weekly for eight weeks by the electronic von Frey method. The spinal cords were processed 1 week postlesion to evaluate the in vivo gene expression of TNFα, TGF-β, BDNF, GDNF, VEGF, NGF, IL-4, IL-6, IL-13 by qRT-PCR and eight weeks postlesion to evaluate changes in the glial response (GFAP and Iba-1) and excitatory synaptic circuits (VGLUT1) by immunofluorescence. The results indicated that PRP therapy partially restores the paw withdrawal reflex over time, indicating the reentry of primary afferents from the dorsal root ganglia into the spinal cord without exacerbating glial reactivity. Additionally, the analysis of mRNA levels showed that PRP therapy has immunomodulatory properties. Overall, the present data suggest that the repair of dorsal roots with PRP may be considered a promising approach to improve sensorimotor recovery following dorsal rhizotomy.
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Affiliation(s)
- Mateus Vidigal de Castro
- Department of Structural and Functional Biology, Institute of Biology, University of Campinas, Campinas, Sao Paulo, Brazil
| | - Moníze Valéria Ramos da Silva
- Department of Structural and Functional Biology, Institute of Biology, University of Campinas, Campinas, Sao Paulo, Brazil
| | | | - Bruno Bosh Volpe
- Regional Center University of Espirito Santo do Pinhal, Espirito Santo do Pinhal, Sao Paulo, Brazil
| | - Maria Helena Santana
- Department of Engineering of Materials and Bioprocesses, School of Chemical Engineering, University of Campinas, Campinas, Sao Paulo, Brazil
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25
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Chung J, Franklin JF, Lee HJ. Central expression of synaptophysin and synaptoporin in nociceptive afferent subtypes in the dorsal horn. Sci Rep 2019; 9:4273. [PMID: 30862809 PMCID: PMC6414693 DOI: 10.1038/s41598-019-40967-y] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2018] [Accepted: 02/20/2019] [Indexed: 11/09/2022] Open
Abstract
Central sprouting of nociceptive afferents in response to neural injury enhances excitability of nociceptive pathways in the central nervous system, often causing pain. A reliable quantification of central projections of afferent subtypes and their synaptic terminations is essential for understanding neural plasticity in any pathological condition. We previously characterized central projections of cutaneous nociceptive A and C fibers, selectively labeled with cholera toxin subunit B (CTB) and Isolectin B4 (IB4) respectively, and found that they expressed a general synaptic molecule, synaptophysin, largely depending on afferent subtypes (A vs. C fibers) across thoracic dorsal horns. The current studies extended the central termination profiles of nociceptive afferents with synaptoporin, an isoform of synaptophysin, known to be preferentially expressed in C fibers in lumbar dorsal root ganglions. Our findings demonstrated that synaptophysin was predominantly expressed in both peptidergic and IB4-binding C fiber populations in superficial laminae of the thoracic dorsal horn. Cutaneous IB4-labeled C fibers showed comparable expression levels of both isoforms, while cutaneous CTB-labeled A fibers exclusively expressed synaptophysin. These data suggest that central expression of synaptophysin consistently represents synaptic terminations of projecting afferents, at least in part, including nociceptive A-delta and C fibers in the dorsal horn.
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Affiliation(s)
- Jumi Chung
- Department of Neurobiology and Anatomical Sciences, University of Mississippi Medical Center, Jackson, MS, 39216, USA.,Research Service, G.V. (Sonny) Montgomery VA Medical Center, Jackson, MS, 39216, USA
| | - John F Franklin
- School of Medicine, University of Mississippi Medical Center, Jackson, MS, 39216, USA
| | - Hyun Joon Lee
- Department of Neurobiology and Anatomical Sciences, University of Mississippi Medical Center, Jackson, MS, 39216, USA. .,Research Service, G.V. (Sonny) Montgomery VA Medical Center, Jackson, MS, 39216, USA.
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26
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Atoji Y, Sarkar S. Gene expression of AMPA, kainate, and NMDA receptor subunits in the pigeon spinal cord. J Chem Neuroanat 2019; 96:148-156. [DOI: 10.1016/j.jchemneu.2018.12.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Revised: 11/01/2018] [Accepted: 12/07/2018] [Indexed: 10/27/2022]
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27
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Spejo AB, Teles CB, Zuccoli GDS, Oliveira ALRD. Synapse preservation and decreased glial reactions following ventral root crush (VRC) and treatment with 4‐hydroxy‐tempo (TEMPOL). J Neurosci Res 2018; 97:520-534. [DOI: 10.1002/jnr.24365] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2018] [Revised: 11/20/2018] [Accepted: 11/20/2018] [Indexed: 11/06/2022]
Affiliation(s)
- Aline Barroso Spejo
- Department of Structural and Functional Biology, Institute of Biology University of Campinas (UNICAMP) Campinas Brazil
| | - Caroline Brandão Teles
- Department of Structural and Functional Biology, Institute of Biology University of Campinas (UNICAMP) Campinas Brazil
| | - Giuliana da Silva Zuccoli
- Department of Structural and Functional Biology, Institute of Biology University of Campinas (UNICAMP) Campinas Brazil
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28
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Wang L, Chen SR, Ma H, Chen H, Hittelman WN, Pan HL. Regulating nociceptive transmission by VGluT2-expressing spinal dorsal horn neurons. J Neurochem 2018; 147:526-540. [PMID: 30203849 DOI: 10.1111/jnc.14588] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2018] [Revised: 08/28/2018] [Accepted: 08/29/2018] [Indexed: 11/28/2022]
Abstract
Vesicular glutamate transporter-2 (VGluT2) mediates the uptake of glutamate into synaptic vesicles in neurons. Spinal cord dorsal horn interneurons are highly heterogeneous and molecularly diverse. The functional significance of VGluT2-expressing dorsal horn neurons in physiological and pathological pain conditions has not been explicitly demonstrated. Designer receptors exclusively activated by designer drugs (DREADDs) are a powerful chemogenetic tool to reversibly control neuronal excitability and behavior. Here, we used transgenic mice with Cre recombinase expression driven by the VGluT2 promoter, combined with the chemogenetic approach, to determine the contribution of VGluT2-expressing dorsal horn neurons to nociceptive regulation. Adeno-associated viral vectors expressing double-floxed Cre-dependent Gαq-coupled human M3 muscarinic receptor DREADD (hM3D)-mCherry or Gαi-coupled κ-opioid receptor DREADD (KORD)-IRES-mCitrine were microinjected into the superficial spinal dorsal horn of VGluT2-Cre mice. Immunofluorescence labeling showed that VGluT2 was predominantly expressed in lamina II excitatory interneurons. Activation of excitatory hM3D in VGluT2-expressing neurons with clozapine N-oxide caused a profound increase in neuronal firing and synaptic glutamate release. Conversely, activation of inhibitory KORD in VGluT2-expressing neurons with salvinorin B markedly inhibited neuronal activity and synaptic glutamate release. In addition, chemogenetic stimulation of VGluT2-expressing neurons increased mechanical and thermal sensitivities in naive mice, whereas chemogenetic silencing of VGluT2-expressing neurons reversed pain hypersensitivity induced by tissue inflammation and peripheral nerve injury. These findings indicate that VGluT2-expressing excitatory neurons play a crucial role in mediating nociceptive transmission in the spinal dorsal horn. Targeting glutamatergic dorsal horn neurons with inhibitory DREADDs may be a new strategy for treating inflammatory pain and neuropathic pain.
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Affiliation(s)
- Li Wang
- Center for Neuroscience and Pain Research, Department of Anesthesiology and Perioperative Medicine, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
| | - Shao-Rui Chen
- Center for Neuroscience and Pain Research, Department of Anesthesiology and Perioperative Medicine, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
| | - Huijie Ma
- Center for Neuroscience and Pain Research, Department of Anesthesiology and Perioperative Medicine, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA.,Department of Physiology, Hebei Medical University, Shijiazhuang, Hebei, China
| | - Hong Chen
- Center for Neuroscience and Pain Research, Department of Anesthesiology and Perioperative Medicine, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
| | - Walter N Hittelman
- Department of Experimental Therapeutics, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
| | - Hui-Lin Pan
- Center for Neuroscience and Pain Research, Department of Anesthesiology and Perioperative Medicine, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
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29
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Zhang FX, Ge SN, Dong YL, Shi J, Feng YP, Li Y, Li YQ, Li JL. Vesicular glutamate transporter isoforms: The essential players in the somatosensory systems. Prog Neurobiol 2018; 171:72-89. [PMID: 30273635 DOI: 10.1016/j.pneurobio.2018.09.006] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2018] [Revised: 08/28/2018] [Accepted: 09/23/2018] [Indexed: 02/08/2023]
Abstract
In nervous system, glutamate transmission is crucial for centripetal conveyance and cortical perception of sensory signals of different modalities, which necessitates vesicular glutamate transporters 1-3 (VGLUT 1-3), the three homologous membrane-bound protein isoforms, to load glutamate into the presysnaptic vesicles. These VGLUTs, especially VGLUT1 and VGLUT2, selectively label and define functionally distinct neuronal subpopulations at each relay level of the neural hierarchies comprising spinal and trigeminal sensory systems. In this review, by scrutinizing each structure of the organism's fundamental hierarchies including dorsal root/trigeminal ganglia, spinal dorsal horn/trigeminal sensory nuclear complex, somatosensory thalamic nuclei and primary somatosensory cortex, we summarize and characterize in detail within each relay the neuronal clusters expressing distinct VGLUT protein/transcript isoforms, with respect to their regional distribution features (complementary distribution in some structures), axonal terminations/peripheral innervations and physiological functions. Equally important, the distribution pattern and characteristics of VGLUT1/VGLUT2 axon terminals within these structures are also epitomized. Finally, the correlation of a particular VGLUT isoform and its physiological role, disclosed thus far largely via studying the peripheral receptors, is generalized by referring to reports on global and conditioned VGLUT-knockout mice. Also, researches on VGLUTs relating to future direction are tentatively proposed, such as unveiling the elusive differences between distinct VGLUTs in mechanism and/or pharmacokinetics at ionic/molecular level, and developing VGLUT-based pain killers.
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Affiliation(s)
- Fu-Xing Zhang
- Department of Anatomy and K.K. Leung Brain Research Centre, School of Basic Medicine, The Fourth Military Medical University, Xi'an 710032, PR China
| | - Shun-Nan Ge
- Department of Anatomy and K.K. Leung Brain Research Centre, School of Basic Medicine, The Fourth Military Medical University, Xi'an 710032, PR China; Department of Neurosurgery, Tangdu Hospital, The Fourth Military Medical University, Xi'an 710038, PR China
| | - Yu-Lin Dong
- Department of Anatomy and K.K. Leung Brain Research Centre, School of Basic Medicine, The Fourth Military Medical University, Xi'an 710032, PR China
| | - Juan Shi
- Department of Anatomy and K.K. Leung Brain Research Centre, School of Basic Medicine, The Fourth Military Medical University, Xi'an 710032, PR China
| | - Yu-Peng Feng
- Department of Anatomy and K.K. Leung Brain Research Centre, School of Basic Medicine, The Fourth Military Medical University, Xi'an 710032, PR China
| | - Yang Li
- Department of Neurosurgery, Tangdu Hospital, The Fourth Military Medical University, Xi'an 710038, PR China
| | - Yun-Qing Li
- Department of Anatomy and K.K. Leung Brain Research Centre, School of Basic Medicine, The Fourth Military Medical University, Xi'an 710032, PR China; Collaborative Innovation Center for Brain Science, Fudan University, Shanghai 200032, PR China.
| | - Jin-Lian Li
- Department of Anatomy and K.K. Leung Brain Research Centre, School of Basic Medicine, The Fourth Military Medical University, Xi'an 710032, PR China.
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30
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Botulinum Neurotoxin Application to the Severed Femoral Nerve Modulates Spinal Synaptic Responses to Axotomy and Enhances Motor Recovery in Rats. Neural Plast 2018; 2018:7975013. [PMID: 30254669 PMCID: PMC6145158 DOI: 10.1155/2018/7975013] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2018] [Revised: 07/15/2018] [Accepted: 08/05/2018] [Indexed: 12/22/2022] Open
Abstract
Botulinum neurotoxin A (BoNT) and brain-derived neurotrophic factor (BDNF) are known for their ability to influence synaptic inputs to neurons. Here, we tested if these drugs can modulate the deafferentation of motoneurons following nerve section/suture and, as a consequence, modify the outcome of peripheral nerve regeneration. We applied drug solutions to the proximal stump of the freshly cut femoral nerve of adult rats to achieve drug uptake and transport to the neuronal perikarya. The most marked effect of this application was a significant reduction of the axotomy-induced loss of perisomatic cholinergic terminals by BoNT at one week and two months post injury. The attenuation of the synaptic deficit was associated with enhanced motor recovery of the rats 2–20 weeks after injury. Although BDNF also reduced cholinergic terminal loss at 1 week, it had no effect on this parameter at two months and no effect on functional recovery. These findings strengthen the idea that persistent partial deafferentation of axotomized motoneurons may have a significant negative impact on functional outcome after nerve injury. Intraneural application of drugs may be a promising way to modify deafferentation and, thus, elucidate relationships between synaptic plasticity and restoration of function.
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31
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Krishnan VS, Shavlakadze T, Grounds MD, Hodgetts SI, Harvey AR. Age-related loss of VGLUT1 excitatory, but not VGAT inhibitory, immunoreactive terminals on motor neurons in spinal cords of old sarcopenic male mice. Biogerontology 2018; 19:385-399. [DOI: 10.1007/s10522-018-9765-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Accepted: 08/04/2018] [Indexed: 12/13/2022]
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32
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Merighi A. The histology, physiology, neurochemistry and circuitry of the substantia gelatinosa Rolandi (lamina II) in mammalian spinal cord. Prog Neurobiol 2018; 169:91-134. [PMID: 29981393 DOI: 10.1016/j.pneurobio.2018.06.012] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2017] [Revised: 06/07/2018] [Accepted: 06/30/2018] [Indexed: 02/06/2023]
Abstract
The substantia gelatinosa Rolandi (SGR) was first described about two centuries ago. In the following decades an enormous amount of information has permitted us to understand - at least in part - its role in the initial processing of pain and itch. Here, I will first provide a comprehensive picture of the histology, physiology, and neurochemistry of the normal SGR. Then, I will analytically discuss the SGR circuits that have been directly demonstrated or deductively envisaged in the course of the intensive research on this area of the spinal cord, with particular emphasis on the pathways connecting the primary afferent fibers and the intrinsic neurons. The perspective existence of neurochemically-defined sets of primary afferent neurons giving rise to these circuits will be also discussed, with the proposition that a cross-talk between different subsets of peptidergic fibers may be the structural and functional substrate of additional gating mechanisms in SGR. Finally, I highlight the role played by slow acting high molecular weight modulators in these gating mechanisms.
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Affiliation(s)
- Adalberto Merighi
- Department of Veterinary Sciences, University of Turin, Largo Paolo Braccini 2, I-10095 Grugliasco (TO), Italy.
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33
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Vesicular glutamate transporter 1 (VGLUT1)- and VGLUT2-immunopositive axon terminals on the rat jaw-closing and jaw-opening motoneurons. Brain Struct Funct 2018; 223:2323-2334. [DOI: 10.1007/s00429-018-1636-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Accepted: 02/19/2018] [Indexed: 12/16/2022]
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34
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Fernández-Montoya J, Avendaño C, Negredo P. The Glutamatergic System in Primary Somatosensory Neurons and Its Involvement in Sensory Input-Dependent Plasticity. Int J Mol Sci 2017; 19:ijms19010069. [PMID: 29280965 PMCID: PMC5796019 DOI: 10.3390/ijms19010069] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2017] [Revised: 12/19/2017] [Accepted: 12/21/2017] [Indexed: 01/25/2023] Open
Abstract
Glutamate is the most common neurotransmitter in both the central and the peripheral nervous system. Glutamate is present in all types of neurons in sensory ganglia, and is released not only from their peripheral and central axon terminals but also from their cell bodies. Consistently, these neurons express ionotropic and metabotropic receptors, as well as other molecules involved in the synthesis, transport and release of the neurotransmitter. Primary sensory neurons are the first neurons in the sensory channels, which receive information from the periphery, and are thus key players in the sensory transduction and in the transmission of this information to higher centers in the pathway. These neurons are tightly enclosed by satellite glial cells, which also express several ionotropic and metabotropic glutamate receptors, and display increases in intracellular calcium accompanying the release of glutamate. One of the main interests in our group has been the study of the implication of the peripheral nervous system in sensory-dependent plasticity. Recently, we have provided novel evidence in favor of morphological changes in first- and second-order neurons of the trigeminal system after sustained alterations of the sensory input. Moreover, these anatomical changes are paralleled by several molecular changes, among which those related to glutamatergic neurotransmission are particularly relevant. In this review, we will describe the state of the art of the glutamatergic system in sensory ganglia and its involvement in input-dependent plasticity, a fundamental ground for advancing our knowledge of the neural mechanisms of learning and adaptation, reaction to injury, and chronic pain.
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Affiliation(s)
- Julia Fernández-Montoya
- Department of Anatomy, Histology and Neuroscience, Medical School, Autonoma University of Madrid, 28029 Madrid, Spain.
| | - Carlos Avendaño
- Department of Anatomy, Histology and Neuroscience, Medical School, Autonoma University of Madrid, 28029 Madrid, Spain.
| | - Pilar Negredo
- Department of Anatomy, Histology and Neuroscience, Medical School, Autonoma University of Madrid, 28029 Madrid, Spain.
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35
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Reversible silencing of lumbar spinal interneurons unmasks a task-specific network for securing hindlimb alternation. Nat Commun 2017; 8:1963. [PMID: 29213073 PMCID: PMC5719045 DOI: 10.1038/s41467-017-02033-x] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2016] [Accepted: 11/02/2017] [Indexed: 12/05/2022] Open
Abstract
Neural circuitry in the lumbar spinal cord governs two principal features of locomotion, rhythm and pattern, which reflect intra- and interlimb movement. These features are functionally organized into a hierarchy that precisely controls stepping in a stereotypic, speed-dependent fashion. Here, we show that a specific component of the locomotor pattern can be independently manipulated. Silencing spinal L2 interneurons that project to L5 selectively disrupts hindlimb alternation allowing a continuum of walking to hopping to emerge from the otherwise intact network. This perturbation, which is independent of speed and occurs spontaneously with each step, does not disrupt multi-joint movements or forelimb alternation, nor does it translate to a non-weight-bearing locomotor activity. Both the underlying rhythm and the usual relationship between speed and spatiotemporal characteristics of stepping persist. These data illustrate that hindlimb alternation can be manipulated independently from other core features of stepping, revealing a striking freedom in an otherwise precisely controlled system. Intra- and interlimb coordination during locomotion is governed by hierarchically organized lumbar spinal networks. Here, the authors show that reversible silencing of spinal L2–L5 interneurons specifically disrupts hindlimb alternation leading to a continuum of walking to hopping.
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36
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Imai F, Chen X, Weirauch MT, Yoshida Y. Requirement for Dicer in Maintenance of Monosynaptic Sensory-Motor Circuits in the Spinal Cord. Cell Rep 2017; 17:2163-2172. [PMID: 27880894 DOI: 10.1016/j.celrep.2016.10.083] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2015] [Revised: 08/08/2016] [Accepted: 10/24/2016] [Indexed: 01/19/2023] Open
Abstract
In contrast to our knowledge of mechanisms governing circuit formation, our understanding of how neural circuits are maintained is limited. Here, we show that Dicer, an RNaseIII protein required for processing microRNAs (miRNAs), is essential for maintenance of the spinal monosynaptic stretch reflex circuit in which group Ia proprioceptive sensory neurons form direct connections with motor neurons. In postnatal mice lacking Dicer in proprioceptor sensory neurons, there are no obvious defects in specificity or formation of monosynaptic sensory-motor connections. However, these circuits degrade through synapse loss and retraction of proprioceptive axonal projections from the ventral spinal cord. Peripheral terminals are also impaired without retracting from muscle targets. Interestingly, despite these central and peripheral axonal defects, proprioceptive neurons survive in the absence of Dicer-processed miRNAs. These findings reveal that Dicer, through its production of mature miRNAs, plays a key role in the maintenance of monosynaptic sensory-motor circuits.
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Affiliation(s)
- Fumiyasu Imai
- Division of Developmental Biology, Cincinnati Children's Hospital Medical Center, 3333 Burnet Avenue, Cincinnati, OH 45229, USA
| | - Xiaoting Chen
- Center for Autoimmune Genomics and Etiology, Cincinnati Children's Hospital Medical Center, 3333 Burnet Avenue, Cincinnati, OH 45229, USA
| | - Matthew T Weirauch
- Division of Developmental Biology, Cincinnati Children's Hospital Medical Center, 3333 Burnet Avenue, Cincinnati, OH 45229, USA; Center for Autoimmune Genomics and Etiology, Cincinnati Children's Hospital Medical Center, 3333 Burnet Avenue, Cincinnati, OH 45229, USA; Division of Biomedical Informatics, Cincinnati Children's Hospital Medical Center, 3333 Burnet Avenue, Cincinnati, OH 45229, USA
| | - Yutaka Yoshida
- Division of Developmental Biology, Cincinnati Children's Hospital Medical Center, 3333 Burnet Avenue, Cincinnati, OH 45229, USA.
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37
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Nishida K, Ito S. Developmental origin of long-range neurons in the superficial dorsal spinal cord. Eur J Neurosci 2017; 46:2608-2619. [DOI: 10.1111/ejn.13736] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2017] [Revised: 09/27/2017] [Accepted: 09/28/2017] [Indexed: 01/08/2023]
Affiliation(s)
- Kazuhiko Nishida
- Department of Medical Chemistry; Kansai Medical University; Shinmachi 2-5-1 Hirakata Osaka 573-1010 Japan
| | - Seiji Ito
- Department of Medical Chemistry; Kansai Medical University; Shinmachi 2-5-1 Hirakata Osaka 573-1010 Japan
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38
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Floyd TL, Dai Y, Ladle DR. Characterization of calbindin D28k expressing interneurons in the ventral horn of the mouse spinal cord. Dev Dyn 2017; 247:185-193. [PMID: 29090497 DOI: 10.1002/dvdy.24601] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2017] [Revised: 10/24/2017] [Accepted: 10/24/2017] [Indexed: 01/01/2023] Open
Abstract
BACKGROUND Expression of the calcium binding protein, calbindin (CB), is well established as a hallmark of Renshaw cells, a class of interneurons found in spatially restricted areas in the ventral spinal cord that directly modulate motor neuron activity. CB expression, however, is not restricted only to Renshaw cells in the ventral horn, and within this population other interneuron subtypes may be identifiable on the basis of cell position and the potential for coexpression of other calcium binding proteins. RESULTS Here we have quantified the changing CB expression pattern in the ventral spinal cord across postnatal development in the mouse. Fewer neurons express CB as postnatal development progresses, and those neurons frequently coexpress other calcium binding proteins (calretinin and parvalbumin) in subpopulations with distinct spatial distributions. We also found a significant portion of CB-expressing interneurons receive putative synaptic contacts from primary sensory afferents. CONCLUSIONS These findings suggest CB labels a heterogeneous group of interneurons in the ventral horn, some of which may process sensory information. Based on cellular position, CB expression may be a shared feature of subsets of interneurons arising from multiple ventral progenitor domains. Developmental Dynamics 247:185-193, 2018. © 2017 Wiley Periodicals, Inc.
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Affiliation(s)
- Taylor L Floyd
- Department of Neuroscience, Cell Biology, and Physiology, Wright State University, Dayton, Ohio, USA
| | - Yiyun Dai
- Department of Neuroscience, Cell Biology, and Physiology, Wright State University, Dayton, Ohio, USA
| | - David R Ladle
- Department of Neuroscience, Cell Biology, and Physiology, Wright State University, Dayton, Ohio, USA
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Ziskind-Conhaim L, Hochman S. Diversity of molecularly defined spinal interneurons engaged in mammalian locomotor pattern generation. J Neurophysiol 2017; 118:2956-2974. [PMID: 28855288 DOI: 10.1152/jn.00322.2017] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2017] [Revised: 08/29/2017] [Accepted: 08/30/2017] [Indexed: 01/18/2023] Open
Abstract
Mapping the expression of transcription factors in the mouse spinal cord has identified ten progenitor domains, four of which are cardinal classes of molecularly defined, ventrally located interneurons that are integrated in the locomotor circuitry. This review focuses on the properties of these interneuronal populations and their contribution to hindlimb locomotor central pattern generation. Interneuronal populations are categorized based on their excitatory or inhibitory functions and their axonal projections as predictors of their role in locomotor rhythm generation and coordination. The synaptic connectivity and functions of these interneurons in the locomotor central pattern generators (CPGs) have been assessed by correlating their activity patterns with motor output responses to rhythmogenic neurochemicals and sensory and descending fibers stimulations as well as analyzing kinematic gait patterns in adult mice. The observed complex organization of interneurons in the locomotor CPG circuitry, some with seemingly similar physiological functions, reflects the intricate repertoire associated with mammalian motor control and is consistent with high transcriptional heterogeneity arising from cardinal interneuronal classes. This review discusses insights derived from recent studies to describe innovative approaches and limitations in experimental model systems and to identify missing links in current investigational enterprise.
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Affiliation(s)
- Lea Ziskind-Conhaim
- Department of Neuroscience, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin; and
| | - Shawn Hochman
- Department of Physiology, Emory University School of Medicine, Atlanta, Georgia
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Synapse Formation in Monosynaptic Sensory-Motor Connections Is Regulated by Presynaptic Rho GTPase Cdc42. J Neurosci 2017; 36:5724-35. [PMID: 27225763 DOI: 10.1523/jneurosci.2146-15.2016] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2015] [Accepted: 04/13/2016] [Indexed: 01/04/2023] Open
Abstract
UNLABELLED Spinal reflex circuit development requires the precise regulation of axon trajectories, synaptic specificity, and synapse formation. Of these three crucial steps, the molecular mechanisms underlying synapse formation between group Ia proprioceptive sensory neurons and motor neurons is the least understood. Here, we show that the Rho GTPase Cdc42 controls synapse formation in monosynaptic sensory-motor connections in presynaptic, but not postsynaptic, neurons. In mice lacking Cdc42 in presynaptic sensory neurons, proprioceptive sensory axons appropriately reach the ventral spinal cord, but significantly fewer synapses are formed with motor neurons compared with wild-type mice. Concordantly, electrophysiological analyses show diminished EPSP amplitudes in monosynaptic sensory-motor circuits in these mutants. Temporally targeted deletion of Cdc42 in sensory neurons after sensory-motor circuit establishment reveals that Cdc42 does not affect synaptic transmission. Furthermore, addition of the synaptic organizers, neuroligins, induces presynaptic differentiation of wild-type, but not Cdc42-deficient, proprioceptive sensory neurons in vitro Together, our findings demonstrate that Cdc42 in presynaptic neurons is required for synapse formation in monosynaptic sensory-motor circuits. SIGNIFICANCE STATEMENT Group Ia proprioceptive sensory neurons form direct synapses with motor neurons, but the molecular mechanisms underlying synapse formation in these monosynaptic sensory-motor connections are unknown. We show that deleting Cdc42 in sensory neurons does not affect proprioceptive sensory axon targeting because axons reach the ventral spinal cord appropriately, but these neurons form significantly fewer presynaptic terminals on motor neurons. Electrophysiological analysis further shows that EPSPs are decreased in these mice. Finally, we demonstrate that Cdc42 is involved in neuroligin-dependent presynaptic differentiation of proprioceptive sensory neurons in vitro These data suggest that Cdc42 in presynaptic sensory neurons is essential for proper synapse formation in the development of monosynaptic sensory-motor circuits.
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Holló K, Ducza L, Hegyi Z, Dócs K, Hegedűs K, Bakk E, Papp I, Kis G, Mészár Z, Bardóczi Z, Antal M. Interleukin-1 receptor type 1 is overexpressed in neurons but not in glial cells within the rat superficial spinal dorsal horn in complete Freund adjuvant-induced inflammatory pain. J Neuroinflammation 2017. [PMID: 28645297 PMCID: PMC5482961 DOI: 10.1186/s12974-017-0902-x] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Background All known biological functions of the pro-inflammatory cytokine interleukin-1β (IL-1β) are mediated by type 1 interleukin receptor (IL-1R1). IL-1β–IL-1R1 signaling modulates various neuronal functions including spinal pain processing. Although the role of IL-1β in pain processing is generally accepted, there is a discussion in the literature whether IL-1β exerts its effect on spinal pain processing by activating neuronal or glial IL-1R1. To contribute to this debate, here we investigated the expression and cellular distribution of IL-1R1 in the superficial spinal dorsal horn in control animals and also in inflammatory pain. Methods Experiments were performed on rats and wild type as well as IL-1R1-deficient mice. Inflammatory pain was evoked by unilateral intraplantar injection of complete Freund adjuvant (CFA). The nociceptive responsiveness of control and CFA-treated animals were tested daily for withdrawal responses to mechanical and thermal stimuli before and after CFA injection. Changes in the expression of 48 selected genes/mRNAs and in the quantity of IL-1R1 protein during the first 3 days after CFA injection were measured with the TaqMan low-density array method and Western blot analysis, respectively. The cellular localization of IL-1R1 protein was investigated with single and double staining immunocytochemical methods. Results We found a six times and two times increase in IL-1R1 mRNA and protein levels, respectively, in the dorsal horn of CFA-injected animals 3 days after CFA injection, at the time of the summit of mechanical and thermal allodynia. Studying the cellular distribution of IL-1R1, we found an abundant expression of IL-1R1 on the somatodendritic compartment of neurons and an enrichment of the receptor in the postsynaptic membranes of some excitatory synapses. In contrast to the robust neuronal localization, we observed only a moderate expression of IL-1R1 on astrocytes and a negligible one on microglial cells. CFA injection into the hind paw caused a remarkable increase in the expression of IL-1R1 in neurons, but did not alter the glial expression of the receptor. Conclusion The results suggest that IL-1β exerts its effect on spinal pain processing primarily through neuronal IL-1R1, but it can also interact in some extent with IL-1R1 expressed by astrocytes.
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Affiliation(s)
- Krisztina Holló
- Department of Anatomy, Histology and Embryology, Faculty of Medicine, University of Debrecen, Nagyerdei krt. 98, 4012, Debrecen, Hungary
| | - László Ducza
- Department of Anatomy, Histology and Embryology, Faculty of Medicine, University of Debrecen, Nagyerdei krt. 98, 4012, Debrecen, Hungary
| | - Zoltán Hegyi
- Department of Anatomy, Histology and Embryology, Faculty of Medicine, University of Debrecen, Nagyerdei krt. 98, 4012, Debrecen, Hungary
| | - Klaudia Dócs
- Department of Anatomy, Histology and Embryology, Faculty of Medicine, University of Debrecen, Nagyerdei krt. 98, 4012, Debrecen, Hungary
| | - Krisztina Hegedűs
- Department of Anatomy, Histology and Embryology, Faculty of Medicine, University of Debrecen, Nagyerdei krt. 98, 4012, Debrecen, Hungary
| | - Erzsébet Bakk
- Department of Anatomy, Histology and Embryology, Faculty of Medicine, University of Debrecen, Nagyerdei krt. 98, 4012, Debrecen, Hungary
| | - Ildikó Papp
- Department of Anatomy, Histology and Embryology, Faculty of Medicine, University of Debrecen, Nagyerdei krt. 98, 4012, Debrecen, Hungary.,Department of Anatomy, Histology and Embryology, Faculty of Pharmacy, University of Debrecen, Nagyerdei krt. 98, 4012, Debrecen, Hungary
| | - Gréta Kis
- Department of Anatomy, Histology and Embryology, Faculty of Medicine, University of Debrecen, Nagyerdei krt. 98, 4012, Debrecen, Hungary
| | - Zoltán Mészár
- Department of Anatomy, Histology and Embryology, Faculty of Medicine, University of Debrecen, Nagyerdei krt. 98, 4012, Debrecen, Hungary
| | - Zsuzsanna Bardóczi
- Laboratory of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary
| | - Miklós Antal
- Department of Anatomy, Histology and Embryology, Faculty of Medicine, University of Debrecen, Nagyerdei krt. 98, 4012, Debrecen, Hungary. .,MTA-DE Neuroscience Research Group, Nagyerdei krt. 98, 4012, Debrecen, Hungary.
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Lamotte d'Incamps B, Bhumbra GS, Foster JD, Beato M, Ascher P. Segregation of glutamatergic and cholinergic transmission at the mixed motoneuron Renshaw cell synapse. Sci Rep 2017. [PMID: 28642492 PMCID: PMC5481398 DOI: 10.1038/s41598-017-04266-8] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In neonatal mice motoneurons excite Renshaw cells by releasing both acetylcholine (ACh) and glutamate. These two neurotransmitters activate two types of nicotinic receptors (nAChRs) (the homomeric α7 receptors and the heteromeric α*ß* receptors) as well as the two types of glutamate receptors (GluRs) (AMPARs and NMDARs). Using paired recordings, we confirm that a single motoneuron can release both transmitters on a single post-synaptic Renshaw cell. We then show that co-transmission is preserved in adult animals. Kinetic analysis of miniature EPSCs revealed quantal release of mixed events associating AMPARs and NMDARs, as well as α7 and α*ß* nAChRs, but no evidence was found for mEPSCs associating nAChRs with GluRs. Bayesian Quantal Analysis (BQA) of evoked EPSCs showed that the number of functional contacts on a single Renshaw cell is more than halved when the nicotinic receptors are blocked, confirming that the two neurotransmitters systems are segregated. Our observations can be explained if ACh and glutamate are released from common vesicles onto spatially segregated post-synaptic receptors clusters, but a pre-synaptic segregation of cholinergic and glutamatergic release sites is also possible.
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Affiliation(s)
- Boris Lamotte d'Incamps
- Center for Neurophysics, Physiology and Pathologies, CNRS UMR 8119, Université Paris Descartes, Paris, France.
| | - Gardave S Bhumbra
- Department of Neuroscience, Physiology and Pharmacology, UCL, Gower Street, London, United Kingdom
| | - Joshua D Foster
- Department of Neuroscience, Physiology and Pharmacology, UCL, Gower Street, London, United Kingdom
| | - Marco Beato
- Department of Neuroscience, Physiology and Pharmacology, UCL, Gower Street, London, United Kingdom
| | - Philippe Ascher
- Physiologie cérébrale, CNRS UMR 8118, Université Paris Descartes, Paris, France
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Chen K, Marsh BC, Cowan M, Al'Joboori YD, Gigout S, Smith CC, Messenger N, Gamper N, Schwab ME, Ichiyama RM. Sequential therapy of anti-Nogo-A antibody treatment and treadmill training leads to cumulative improvements after spinal cord injury in rats. Exp Neurol 2017; 292:135-144. [DOI: 10.1016/j.expneurol.2017.03.012] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2016] [Revised: 03/15/2017] [Accepted: 03/21/2017] [Indexed: 11/16/2022]
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Biscola NP, Cartarozzi LP, Ulian-Benitez S, Barbizan R, Castro MV, Spejo AB, Ferreira RS, Barraviera B, Oliveira ALR. Multiple uses of fibrin sealant for nervous system treatment following injury and disease. J Venom Anim Toxins Incl Trop Dis 2017; 23:13. [PMID: 28293254 PMCID: PMC5348778 DOI: 10.1186/s40409-017-0103-1] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2016] [Accepted: 02/23/2017] [Indexed: 12/14/2022] Open
Abstract
Lesions to the nervous system often produce hemorrhage and tissue loss that are difficult, if not impossible, to repair. Therefore, scar formation, inflammation and cavitation take place, expanding the lesion epicenter. This significantly worsens the patient conditions and impairment, increasing neuronal loss and glial reaction, which in turn further decreases the chances of a positive outcome. The possibility of using hemostatic substances that also function as a scaffold, such as the fibrin sealant, reduces surgical time and improve postoperative recovery. To date, several studies have demonstrated that human blood derived fibrin sealant produces positive effects in different interventions, becoming an efficient alternative to suturing. To provide an alternative to homologous fibrin sealants, the Center for the Study of Venoms and Venomous Animals (CEVAP, Brazil) has proposed a new bioproduct composed of certified animal components, including a thrombin-like enzyme obtained from snake venom and bubaline fibrinogen. Thus, the present review brings up to date literature assessment on the use of fibrin sealant for nervous system repair and positions the new heterologous bioproduct from CEVAP as an alternative to the commercial counterparts. In this way, clinical and pre-clinical data are discussed in different topics, ranging from central nervous system to peripheral nervous system applications, specifying positive results as well as future enhancements that are necessary for improving the use of fibrin sealant therapy.
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Affiliation(s)
- Natalia Perussi Biscola
- Graduate Program in Tropical Diseases, Botucatu Medical School, Univ Estadual Paulista (UNESP), Botucatu, SP Brazil.,Center for the Study of Venoms and Venomous Animals (CEVAP), Univ Estadual Paulista (UNESP), Botucatu, SP Brazil.,Department of Structural and Functional Biology, Institute of Biology, University of Campinas (UNICAMP), Laboratory of Nerve Regeneration, CEP 13083-970 Campinas, SP Brazil
| | - Luciana Politti Cartarozzi
- Department of Structural and Functional Biology, Institute of Biology, University of Campinas (UNICAMP), Laboratory of Nerve Regeneration, CEP 13083-970 Campinas, SP Brazil
| | - Suzana Ulian-Benitez
- Department of Structural and Functional Biology, Institute of Biology, University of Campinas (UNICAMP), Laboratory of Nerve Regeneration, CEP 13083-970 Campinas, SP Brazil.,Neuro Development Lab, School of Biosciences, University of Birmingham, Birmingham, England UK
| | - Roberta Barbizan
- Department of Structural and Functional Biology, Institute of Biology, University of Campinas (UNICAMP), Laboratory of Nerve Regeneration, CEP 13083-970 Campinas, SP Brazil.,The School of Medicine at Mucuri (FAMMUC), Federal University of Jequitinhonha and Mucuri Valleys (UFVJM), 39803-371 Teófilo Otoni, MG Brazil
| | - Mateus Vidigal Castro
- Department of Structural and Functional Biology, Institute of Biology, University of Campinas (UNICAMP), Laboratory of Nerve Regeneration, CEP 13083-970 Campinas, SP Brazil
| | - Aline Barroso Spejo
- Department of Structural and Functional Biology, Institute of Biology, University of Campinas (UNICAMP), Laboratory of Nerve Regeneration, CEP 13083-970 Campinas, SP Brazil
| | - Rui Seabra Ferreira
- Graduate Program in Tropical Diseases, Botucatu Medical School, Univ Estadual Paulista (UNESP), Botucatu, SP Brazil.,Center for the Study of Venoms and Venomous Animals (CEVAP), Univ Estadual Paulista (UNESP), Botucatu, SP Brazil
| | - Benedito Barraviera
- Graduate Program in Tropical Diseases, Botucatu Medical School, Univ Estadual Paulista (UNESP), Botucatu, SP Brazil.,Center for the Study of Venoms and Venomous Animals (CEVAP), Univ Estadual Paulista (UNESP), Botucatu, SP Brazil
| | - Alexandre Leite Rodrigues Oliveira
- Department of Structural and Functional Biology, Institute of Biology, University of Campinas (UNICAMP), Laboratory of Nerve Regeneration, CEP 13083-970 Campinas, SP Brazil
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Deletion of the Fractalkine Receptor, CX3CR1, Improves Endogenous Repair, Axon Sprouting, and Synaptogenesis after Spinal Cord Injury in Mice. J Neurosci 2017; 37:3568-3587. [PMID: 28264978 DOI: 10.1523/jneurosci.2841-16.2017] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2016] [Revised: 02/21/2017] [Accepted: 02/22/2017] [Indexed: 01/12/2023] Open
Abstract
Impaired signaling via CX3CR1, the fractalkine receptor, promotes recovery after traumatic spinal contusion injury in mice, a benefit achieved in part by reducing macrophage-mediated injury at the lesion epicenter. Here, we tested the hypothesis that CX3CR1-dependent changes in microglia and macrophage functions also will enhance neuroplasticity, at and several segments below the injury epicenter. New data show that in the presence of inflammatory stimuli, CX3CR1-deficient (CX3CR1-/-) microglia and macrophages adopt a reparative phenotype and increase expression of genes that encode neurotrophic and gliogenic proteins. At the lesion epicenter (mid-thoracic spinal cord), the microenvironment created by CX3CR1-/- microglia/macrophages enhances NG2 cell responses, axon sparing, and sprouting of serotonergic axons. In lumbar spinal cord, inflammatory signaling is reduced in CX3CR1-/- microglia. This is associated with reduced dendritic pathology and improved axonal and synaptic plasticity on ventral horn motor neurons. Together, these data indicate that CX3CR1, a microglia-specific chemokine receptor, is a novel therapeutic target for enhancing neuroplasticity and recovery after SCI. Interventions that specifically target CX3CR1 could reduce the adverse effects of inflammation and augment activity-dependent plasticity and restoration of function. Indeed, limiting CX3CR1-dependent signaling could improve rehabilitation and spinal learning.SIGNIFICANCE STATEMENT Published data show that genetic deletion of CX3CR1, a microglia-specific chemokine receptor, promotes recovery after traumatic spinal cord injury in mice, a benefit achieved in part by reducing macrophage-mediated injury at the lesion epicenter. Data in the current manuscript indicate that CX3CR1 deletion changes microglia and macrophage function, creating a tissue microenvironment that enhances endogenous repair and indices of neuroplasticity, at and several segments below the injury epicenter. Interventions that specifically target CX3CR1 might be used in the future to reduce the adverse effects of intraspinal inflammation and augment activity-dependent plasticity (e.g., rehabilitation) and restoration of function.
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Kodama D, Hirai T, Kondo H, Hamamura K, Togari A. Bidirectional communication between sensory neurons and osteoblasts in an in vitro coculture system. FEBS Lett 2017; 591:527-539. [PMID: 28094440 DOI: 10.1002/1873-3468.12561] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2016] [Revised: 12/30/2016] [Accepted: 01/11/2017] [Indexed: 12/18/2022]
Abstract
Recent studies have revealed that the sensory nervous system is involved in bone metabolism. However, the mechanism of communication between neurons and osteoblasts is yet to be elucidated. In this study, we investigated the signaling pathways between sensory neurons of the dorsal root ganglion (DRG) and the osteoblast-like MC3T3-E1 cells using an in vitro coculture system. Our findings indicate that signal transduction from DRG-derived neurons to MC3T3-E1 cells is suppressed by antagonists of the AMPA receptor and the NK1 receptor. Conversely, signal transduction from MC3T3-E1 cells to DRG-derived neurons is suppressed by a P2X7 receptor antagonist. Our results suggest that these cells communicate with each other by exocytosis of glutamate, substance P in the efferent signal, and ATP in the afferent signal.
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Affiliation(s)
- Daisuke Kodama
- Laboratory of Neuropharmacology, School of Pharmacy, Aichi-Gakuin University, Chikusa-ku, Nagoya, Japan.,Department of Pharmacology, School of Dentistry, Aichi-Gakuin University, Chikusa-ku, Nagoya, Japan
| | - Takao Hirai
- Laboratory of Medicinal Resources, School of Pharmacy, Aichi-Gakuin University, Chikusa-ku, Nagoya, Japan
| | - Hisataka Kondo
- Department of Pharmacology, School of Dentistry, Aichi-Gakuin University, Chikusa-ku, Nagoya, Japan
| | - Kazunori Hamamura
- Department of Pharmacology, School of Dentistry, Aichi-Gakuin University, Chikusa-ku, Nagoya, Japan
| | - Akifumi Togari
- Department of Pharmacology, School of Dentistry, Aichi-Gakuin University, Chikusa-ku, Nagoya, Japan
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47
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Fujimoto H, Konno K, Watanabe M, Jinno S. Late postnatal shifts of parvalbumin and nitric oxide synthase expression within the GABAergic and glutamatergic phenotypes of inferior colliculus neurons. J Comp Neurol 2016; 525:868-884. [PMID: 27560447 DOI: 10.1002/cne.24104] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2016] [Revised: 08/22/2016] [Accepted: 08/22/2016] [Indexed: 01/24/2023]
Abstract
The inferior colliculus (IC) is partitioned into three subdivisions: the dorsal and lateral cortices (DC and LC) and the central nucleus (ICC), and serves as an integration center of auditory information. Recent studies indicate that a certain population of IC neurons may represent the non-GABAergic phenotype, while they express well-established cortical/hippocampal GABAergic neuron markers. In this study we used the optical disector to investigate the phenotype of IC neurons expressing parvalbumin (PV) and/or nitric oxide synthase (NOS) in C57BL/6J mice during the late postnatal period. Four major types of IC neurons were defined by the presence (+) or absence (-) of PV, NOS, and glutamic acid decarboxylase 67 (GAD67): PV+ /NOS- /GAD67+ , PV+ /NOS+ /GAD67+ , PV+ /NOS- /GAD67- , and PV- /NOS+ /GAD67- . Fluorescent in situ hybridization for vesicular glutamate transporter 2 mRNA indicated that almost all GAD67- IC neurons represented the glutamatergic phenotype. The numerical densities (NDs) of total GAD67+ IC neurons remained unchanged in all subdivisions. The NDs of PV+ /NOS- /GAD67+ neurons and PV- /NOS+ /GAD67- neurons were reduced with age in the ICC, while they remained unchanged in the DC and LC. By contrast, the NDs of PV+ /NOS+ /GAD67+ neurons and PV+ /NOS- /GAD67- neurons were increased with age in the ICC, although there were no changes in the DC and LC. The cell body size of GAD67+ IC neurons did not vary according to the expression of PV with or without NOS. The present findings indicate that the expression of PV and NOS may shift with age within the GABAergic and glutamatergic phenotypes of IC neurons during the late postnatal period. J. Comp. Neurol. 525:868-884, 2017. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Hisataka Fujimoto
- Department of Anatomy and Neuroscience, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Kotaro Konno
- Department of Anatomy, Hokkaido University Graduate School of Medicine, Sapporo, Japan
| | - Masahiko Watanabe
- Department of Anatomy, Hokkaido University Graduate School of Medicine, Sapporo, Japan
| | - Shozo Jinno
- Department of Anatomy and Neuroscience, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
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Torres-da-Silva KR, Da Silva AV, Barioni NO, Tessarin GWL, De Oliveira JA, Ervolino E, Horta-Junior JAC, Casatti CA. Neurochemistry study of spinal cord in non-human primate (Sapajus spp.). Eur J Histochem 2016; 60:2623. [PMID: 27734991 PMCID: PMC5062631 DOI: 10.4081/ejh.2016.2623] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2016] [Revised: 08/07/2016] [Accepted: 08/17/2016] [Indexed: 02/06/2023] Open
Abstract
The spinal cord is involved in local, ascending and descending neural pathways. Few studies analyzed the distribution of neuromediators in the laminae of non-human primates along all segments. The present study described the classic neuromediators in the spinal cord of the non-human primate Sapajus spp. through histochemical and immunohistochemical methods. Nicotinamide adenine dinucleotide hydrogen phosphate-diaphorase (NADPH-d) method showed neuronal somata in the intermediolateral column (IML), central cervical nucleus (CCN), laminae I, II, III, IV, V, VI, VII, VIII and X, besides dense presence of nerve fibers in laminae II and IX. Acetylcholinesterase (AChE) activity was evident in the neuronal somata in laminae V, VI, VII, VIII, IX, CCN, IML and in the Clarke’s column (CC). Immunohistochemistry data revealed neuronal nitric oxide synthase (nNOS) immunoreactivity in neuronal somata and in fibers of laminae I, II, III, VII, VIII, X and IML; choline acetyltransferase (ChAT) in neuronal somata and in fibers of laminae VII, VIII and IX; calcitonin gene-related peptide (CGRP) was noticed in neuronal somata of lamina IX and in nerve fibers of laminae I, II, III, IV, V, VI and VII; substance P (SP) in nerve fibers of laminae I, II, III, IV, V, VI, VII, VIII, IX, X, CCN, CC and IML; serotonin (5-HT) and vesicular glutamate transporter-1 (VGLUT1) was noticed in nerve fibers of all laminae; somatostatin (SOM) in neuronal somata of laminae III, IV, V, VI, VII, VIII and IX and nerve fibers in laminae I, II, V, VI, VII, X and IML; calbindin (Cb) in neuronal somata of laminae I, II, VI, VII, IX and X; parvalbumin (PV) was found in neuronal somata and in nerve fibers of laminae III, IV, V, VI, VII, VIII, IX and CC; finally, gamma-amino butyric acid (GABA) was present in neuronal somata of laminae V, VI, VII, VIII, IX and X. This study revealed interesting results concerning the chemoarchitecture of the Sapajus spp. spinal cord with a distribution pattern mostly similar to other mammals. The data corroborate the result described in literature, except for some differences in CGRP, SP, Cb, PV and GABA immunoreactivities present in neuronal somata and in nerve fibers. This could suggest certain specificity for the neurochemistry distribution in this non-human primate species, besides adding relevant data to support further studies related to processes involving spinal cord components.
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Hulse RP, Drake RAR, Bates DO, Donaldson LF. The control of alternative splicing by SRSF1 in myelinated afferents contributes to the development of neuropathic pain. Neurobiol Dis 2016; 96:186-200. [PMID: 27616424 PMCID: PMC5113660 DOI: 10.1016/j.nbd.2016.09.009] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2016] [Revised: 08/24/2016] [Accepted: 09/06/2016] [Indexed: 02/07/2023] Open
Abstract
Neuropathic pain results from neuroplasticity in nociceptive neuronal networks. Here we demonstrate that control of alternative pre-mRNA splicing, through the splice factor serine-arginine splice factor 1 (SRSF1), is integral to the processing of nociceptive information in the spinal cord. Neuropathic pain develops following a partial saphenous nerve ligation injury, at which time SRSF1 is activated in damaged myelinated primary afferent neurons, with minimal found in small diameter (IB4 positive) dorsal root ganglia neurons. Serine arginine protein kinase 1 (SRPK1) is the principal route of SRSF1 activation. Spinal SRPK1 inhibition attenuated SRSF1 activity, abolished neuropathic pain behaviors and suppressed central sensitization. SRSF1 was principally expressed in large diameter myelinated (NF200-rich) dorsal root ganglia sensory neurons and their excitatory central terminals (vGLUT1+ve) within the dorsal horn of the lumbar spinal cord. Expression of pro-nociceptive VEGF-Axxxa within the spinal cord was increased after nerve injury, and this was prevented by SRPK1 inhibition. Additionally, expression of anti-nociceptive VEGF-Axxxb isoforms was elevated, and this was associated with reduced neuropathic pain behaviors. Inhibition of VEGF receptor-2 signaling in the spinal cord attenuated behavioral nociceptive responses to mechanical, heat and formalin stimuli, indicating that spinal VEGF receptor-2 activation has potent pro-nociceptive actions. Furthermore, intrathecal VEGF-A165a resulted in mechanical and heat hyperalgesia, whereas the sister inhibitory isoform VEGF-A165b resulted in anti-nociception. These results support a role for myelinated fiber pathways, and alternative pre-mRNA splicing of factors such as VEGF-A in the spinal processing of neuropathic pain. They also indicate that targeting pre-mRNA splicing at the spinal level could lead to a novel target for analgesic development.
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Affiliation(s)
- Richard P Hulse
- Cancer Biology, School of Medicine, University of Nottingham, Nottingham, NG7 7UH, United Kingdom; School of Physiology and Pharmacology, University of Bristol, University Walk, Bristol BS8 1TD, United Kingdom.
| | - Robert A R Drake
- School of Physiology and Pharmacology, University of Bristol, University Walk, Bristol BS8 1TD, United Kingdom
| | - David O Bates
- Cancer Biology, School of Medicine, University of Nottingham, Nottingham, NG7 7UH, United Kingdom; School of Physiology and Pharmacology, University of Bristol, University Walk, Bristol BS8 1TD, United Kingdom
| | - Lucy F Donaldson
- School of Physiology and Pharmacology, University of Bristol, University Walk, Bristol BS8 1TD, United Kingdom; School of Life Sciences and Arthritis Research UK Pain Centre, University of Nottingham, Nottingham NG7 7UH, United Kingdom.
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Neuronal networks and nociceptive processing in the dorsal horn of the spinal cord. Neuroscience 2016; 338:230-247. [PMID: 27595888 DOI: 10.1016/j.neuroscience.2016.08.048] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2016] [Revised: 08/23/2016] [Accepted: 08/28/2016] [Indexed: 12/31/2022]
Abstract
The dorsal horn (DH) of the spinal cord receives a variety of sensory information arising from the inner and outer environment, as well as modulatory inputs from supraspinal centers. This information is integrated by the DH before being forwarded to brain areas where it may lead to pain perception. Spinal integration of this information relies on the interplay between different DH neurons forming complex and plastic neuronal networks. Elements of these networks are therefore potential targets for new analgesics and pain-relieving strategies. The present review aims at providing an overview of the current knowledge on these networks, with a special emphasis on those involving interlaminar communication in both physiological and pathological conditions.
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