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Coviello S, Gramuntell Y, Klimczak P, Varea E, Blasco-Ibañez JM, Crespo C, Gutierrez A, Nacher J. Phenotype and Distribution of Immature Neurons in the Human Cerebral Cortex Layer II. Front Neuroanat 2022; 16:851432. [PMID: 35464133 PMCID: PMC9027810 DOI: 10.3389/fnana.2022.851432] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2022] [Accepted: 03/22/2022] [Indexed: 11/13/2022] Open
Abstract
This work provides evidence of the presence of immature neurons in the human brain, specifically in the layer II of the cerebral cortex. Using surgical samples from epileptic patients and post-mortem tissue, we have found cells with different levels of dendritic complexity (type I and type II cells) expressing DCX and PSA-NCAM and lacking expression of the mature neuronal marker NeuN. These immature cells belonged to the excitatory lineage, as demonstrated both by the expression of CUX1, CTIP2, and TBR1 transcription factors and by the lack of the inhibitory marker GAD67. The type II cells had some puncta expressing inhibitory and excitatory synaptic markers apposed to their perisomatic and peridendritic regions and ultrastructural analysis suggest the presence of synaptic contacts. These cells did not present glial cell markers, although astroglial and microglial processes were found in close apposition to their somata and dendrites, particularly on type I cells. Our findings confirm the presence of immature neurons in several regions of the cerebral cortex of humans of different ages and define their lineage. The presence of some mature features in some of these cells suggests the possibility of a progressively integration as excitatory neurons, as described in the olfactory cortex of rodents.
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Affiliation(s)
- Simona Coviello
- Neurobiology Unit, Program in Neurosciences and Institute of Biotechnology and Biomedicine (BIOTECMED), Universitat de València, Burjassot, Spain
| | - Yaiza Gramuntell
- Neurobiology Unit, Program in Neurosciences and Institute of Biotechnology and Biomedicine (BIOTECMED), Universitat de València, Burjassot, Spain
| | - Patrycja Klimczak
- Neurobiology Unit, Program in Neurosciences and Institute of Biotechnology and Biomedicine (BIOTECMED), Universitat de València, Burjassot, Spain
- Spanish National Network for Research in Mental Health, Centro de Investigación Biomédica en Red de Salud Mental (CIBERSAM), Madrid, Spain
| | - Emilio Varea
- Neurobiology Unit, Program in Neurosciences and Institute of Biotechnology and Biomedicine (BIOTECMED), Universitat de València, Burjassot, Spain
| | - José Miguel Blasco-Ibañez
- Neurobiology Unit, Program in Neurosciences and Institute of Biotechnology and Biomedicine (BIOTECMED), Universitat de València, Burjassot, Spain
| | - Carlos Crespo
- Neurobiology Unit, Program in Neurosciences and Institute of Biotechnology and Biomedicine (BIOTECMED), Universitat de València, Burjassot, Spain
| | - Antonio Gutierrez
- Unidad de Cirugía de la Epilepsia, Hospital Universitario La Fe, Valencia, Spain
| | - Juan Nacher
- Neurobiology Unit, Program in Neurosciences and Institute of Biotechnology and Biomedicine (BIOTECMED), Universitat de València, Burjassot, Spain
- Spanish National Network for Research in Mental Health, Centro de Investigación Biomédica en Red de Salud Mental (CIBERSAM), Madrid, Spain
- Fundación Investigación Hospital Clínico de Valencia (INCLIVA), Valencia, Spain
- *Correspondence: Juan Nacher,
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2
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Genetic deletion of α7 nicotinic acetylcholine receptors induces an age-dependent Alzheimer's disease-like pathology. Prog Neurobiol 2021; 206:102154. [PMID: 34453977 DOI: 10.1016/j.pneurobio.2021.102154] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Revised: 05/29/2021] [Accepted: 08/18/2021] [Indexed: 11/22/2022]
Abstract
The accumulation of amyloid-beta peptide (Aβ) and the failure of cholinergic transmission are key players in Alzheimer's disease (AD). However, in the healthy brain, Aβ contributes to synaptic plasticity and memory acting through α7 subtype nicotinic acetylcholine receptors (α7nAChRs). Here, we hypothesized that the α7nAChR deletion blocks Aβ physiological function and promotes a compensatory increase in Aβ levels that, in turn, triggers an AD-like pathology. To validate this hypothesis, we studied the age-dependent phenotype of α7 knock out mice. We found that α7nAChR deletion caused an impairment of hippocampal synaptic plasticity and memory at 12 months of age, paralleled by an increase of Amyloid Precursor Protein expression and Aβ levels. This was accompanied by other classical AD features such as a hyperphosphorylation of tau at residues Ser 199, Ser 396, Thr 205, a decrease of GSK-3β at Ser 9, the presence of paired helical filaments and neurofibrillary tangles, neuronal loss and an increase of GFAP-positive astrocytes. Our findings suggest that α7nAChR malfunction might precede Aβ and tau pathology, offering a different perspective to interpret the failure of anti-Aβ therapies against AD and to find novel therapeutical approaches aimed at restoring α7nAChRs-mediated Aβ function at the synapse.
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3
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Cocaine Triggers Astrocyte-Mediated Synaptogenesis. Biol Psychiatry 2021; 89:386-397. [PMID: 33069367 PMCID: PMC7854999 DOI: 10.1016/j.biopsych.2020.08.012] [Citation(s) in RCA: 51] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Revised: 07/28/2020] [Accepted: 08/11/2020] [Indexed: 12/30/2022]
Abstract
BACKGROUND Synaptogenesis is essential in forming new neurocircuits during development, and this is mediated in part by astrocyte-released thrombospondins (TSPs) and activation of their neuronal receptor, α2δ-1. Here, we show that this developmental synaptogenic mechanism is utilized during cocaine experience to induce spinogenesis and the generation of AMPA receptor-silent glutamatergic synapses in the adult nucleus accumbens shell (NAcSh). METHODS Using multidisciplinary approaches including astrocyte Ca2+ imaging, genetic mouse lines, viral-mediated gene transfer, and operant behavioral procedures, we monitor the response of NAcSh astrocytes to cocaine administration and examine the role of astrocytic TSP-α2δ-1 signaling in cocaine-induced silent synapse generation as well as the behavioral impact of astrocyte-mediated synaptogenesis and silent synapse generation. RESULTS Cocaine administration acutely increases Ca2+ events in NAcSh astrocytes, while decreasing astrocytic Ca2+ blocks cocaine-induced generation of silent synapses. Furthermore, knockout of TSP2, or pharmacological inhibition or viral-mediated knockdown of α2δ-1, prevents cocaine-induced generation of silent synapses. Moreover, disrupting TSP2-α2δ-1-mediated spinogenesis and synapse generation in NAcSh decreases cue-induced cocaine seeking after withdrawal from cocaine self-administration and cue-induced reinstatement of cocaine seeking after drug extinction. CONCLUSIONS These results establish that silent synapses are generated by an astrocyte-mediated synaptogenic mechanism in response to cocaine experience and embed critical cue-associated memory traces that promote cocaine relapse.
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Cai WT, Han J, Kim WY, Kim JH. Immunohistochemical detection of GluA1 subunit of AMPA receptor in the rat nucleus accumbens following cocaine exposure. THE KOREAN JOURNAL OF PHYSIOLOGY & PHARMACOLOGY 2021; 25:79-85. [PMID: 33361540 PMCID: PMC7756536 DOI: 10.4196/kjpp.2021.25.1.79] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Revised: 11/20/2020] [Accepted: 11/23/2020] [Indexed: 11/15/2022]
Abstract
α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptors are differentially regulated in the nucleus accumbens (NAcc) of the brain after cocaine exposure. However, these results are supported only by biochemical and electrophysiological methods, but have not been validated with immunohistochemistry. To overcome the restriction of antigen loss on the postsynaptic target molecules that occurs during perfusion-fixation, we adopted an immersion-fixation method that enabled us to immunohistochemically quantify the expression levels of the AMPA receptor GluA1 subunit in the NAcc. Interestingly, compared to saline exposure, cocaine significantly increased the immunofluorescence intensity of GluA1 in two sub-regions, the core and the shell, of the NAcc on withdrawal day 21 following cocaine exposure, which led to locomotor sensitization. Increases in GluA1 intensity were observed in both the extra-post synaptic density (PSD) and PSD areas in the two sub-regions of the NAcc. These results clearly indicate that AMPA receptor plasticity, as exemplified by GluA1, in the NAcc can be visually detected by immunohistochemistry and confocal imaging. These results expand our understanding of the molecular changes occurring in neuronal synapses by adding a new form of analysis to conventional biochemical and electrophysiological methods.
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Affiliation(s)
- Wen Ting Cai
- Department of Physiology, Graduate School of Medical Sciences, Yonsei University College of Medicine, Seoul 03722, Korea
| | - Joonyeup Han
- Department of Physiology, Graduate School of Medical Sciences, Yonsei University College of Medicine, Seoul 03722, Korea
| | - Wha Young Kim
- Department of Physiology, Graduate School of Medical Sciences, Yonsei University College of Medicine, Seoul 03722, Korea
| | - Jeong-Hoon Kim
- Department of Physiology, Graduate School of Medical Sciences, Yonsei University College of Medicine, Seoul 03722, Korea
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5
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Melone M, Ciriachi C, Pietrobon D, Conti F. Heterogeneity of Astrocytic and Neuronal GLT-1 at Cortical Excitatory Synapses, as Revealed by its Colocalization With Na+/K+-ATPase α Isoforms. Cereb Cortex 2020; 29:3331-3350. [PMID: 30260367 DOI: 10.1093/cercor/bhy203] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2018] [Revised: 08/01/2018] [Accepted: 08/03/2018] [Indexed: 12/29/2022] Open
Abstract
GLT-1, the major glutamate transporter, is expressed at perisynaptic astrocytic processes (PAP) and axon terminals (AxT). GLT-1 is coupled to Na+/K+-ATPase (NKA) α1-3 isoforms, whose subcellular distribution and spatial organization in relationship to GLT-1 are largely unknown. Using several microscopy techniques, we showed that at excitatory synapses α1 and α3 are exclusively neuronal (mainly in dendrites and in some AxT), while α2 is predominantly astrocytic. GLT-1 displayed a differential colocalization with α1-3. GLT-1/α2 and GLT-1/α3 colocalization was higher in GLT-1 positive puncta partially (for GLT-1/α2) or almost totally (for GLT-1/α3) overlapping with VGLUT1 positive terminals than in nonoverlapping ones. GLT-1 colocalized with α2 at PAP, and with α1 and α3 at AxT. GLT-1 and α2 gold particles were ∼1.5-2 times closer than GLT-1/α1 and GLT-1/α3 particles. GLT-1/α2 complexes (edge to edge interdistance of gold particles ≤50 nm) concentrated at the perisynaptic region of PAP membranes, whereas neuronal GLT-1/α1 and GLT-1/α3 complexes were fewer and more uniformly distributed in AxT. These data unveil different composition of GLT-1 and α subunits complexes in the glial and neuronal domains of excitatory synapses. The spatial organization of GLT-1/α1-3 complexes suggests that GLT-1/NKA interaction is more efficient in astrocytes than in neurons, further supporting the dominant role of astrocytic GLT-1 in glutamate homeostasis.
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Affiliation(s)
- Marcello Melone
- Section of Neuroscience and Cell Biology, Department of Experimental and Clinical Medicine, Università Politecnica delle Marche, Ancona, Italy.,Center for Neurobiology of Aging, IRCCS INRCA, Ancona, Italy
| | - Chiara Ciriachi
- Section of Neuroscience and Cell Biology, Department of Experimental and Clinical Medicine, Università Politecnica delle Marche, Ancona, Italy
| | - Daniela Pietrobon
- Department of Biomedical Sciences, University of Padova, and CNR Institute of Neuroscience, Padova, Italy
| | - Fiorenzo Conti
- Section of Neuroscience and Cell Biology, Department of Experimental and Clinical Medicine, Università Politecnica delle Marche, Ancona, Italy.,Center for Neurobiology of Aging, IRCCS INRCA, Ancona, Italy.,Foundation for Molecular Medicine, Università Politecnica delle Marche, Ancona, Italy
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6
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Lama A, Pirozzi C, Annunziata C, Morgese MG, Senzacqua M, Severi I, Calignano A, Trabace L, Giordano A, Meli R, Mattace Raso G. Palmitoylethanolamide counteracts brain fog improving depressive-like behaviour in obese mice: Possible role of synaptic plasticity and neurogenesis. Br J Pharmacol 2020; 178:845-859. [PMID: 32346865 DOI: 10.1111/bph.15071] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2019] [Revised: 03/28/2020] [Accepted: 04/17/2020] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND AND PURPOSE High-fat diet (HFD)-induced obesity is accompanied by metabolic and neurochemical changes that have been associated with depression. Recent studies indicate that palmitoylethanolamide (PEA) exerts metabolic effects and holds neuroprotective potential. However, studies on HFD exposure in mice which investigate the effects of PEA on monoamine system and synaptic plasticity are limited. EXPERIMENTAL APPROACH In C57Bl/6J male mice, obesity was established by HFD feeding for 12 weeks. Then, mice were treated with ultra-micronized PEA (30 mg·kg-1 daily p.o.) or vehicle for 7 weeks along with HFD. Mice receiving chow diet and vehicle served as controls. Thereafter, depressive-, anhedonic-like behaviour and cognitive performance were measured. Monoamine analyses were performed on brain areas (nucleus accumbens, Nac; prefrontal cortex, PFC; hippocampus), and markers of synaptic plasticity and neurogenesis were evaluated in hippocampus. KEY RESULTS PEA limited depressive- and anhedonic-like behaviour, and cognitive deficits induced by HFD. PEA induced an increase in 5-HT levels in PFC, and a reduction of dopamine and 5-HT turnover in Nac and PFC, respectively. Moreover, PEA increased dopamine levels in the hippocampus and PFC. At a molecular level, PEA restored brain-derived neurotrophic factor signalling pathway in hippocampus and PFC, indicating an improvement of synaptic plasticity. In particular, PEA counteracted the reduction of glutamatergic synaptic density induced by HFD in the stratum radiatum of the CA1 of the hippocampus, where it also exhibited neurogenesis-promoting abilities. CONCLUSION AND IMPLICATIONS PEA may represent an adjuvant therapy to limit depressive-like behaviours and memory deficit, affecting monoamine homeostasis, synaptic plasticity and neurogenesis. LINKED ARTICLES This article is part of a themed issue on Neurochemistry in Japan. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v178.4/issuetoc.
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Affiliation(s)
- Adriano Lama
- Department of Pharmacy, School of Medicine, University of Naples Federico II, Naples, Italy
| | - Claudio Pirozzi
- Department of Pharmacy, School of Medicine, University of Naples Federico II, Naples, Italy
| | - Chiara Annunziata
- Department of Pharmacy, School of Medicine, University of Naples Federico II, Naples, Italy
| | - Maria Grazia Morgese
- Department of Clinical and Experimental Medicine, University of Foggia, Foggia, Italy
| | - Martina Senzacqua
- Department of Experimental and Clinical Medicine, Marche Polytechnic University, Ancona, Italy
| | - Ilenia Severi
- Department of Experimental and Clinical Medicine, Marche Polytechnic University, Ancona, Italy
| | - Antonio Calignano
- Department of Pharmacy, School of Medicine, University of Naples Federico II, Naples, Italy
| | - Luigia Trabace
- Department of Clinical and Experimental Medicine, University of Foggia, Foggia, Italy
| | - Antonio Giordano
- Department of Experimental and Clinical Medicine, Marche Polytechnic University, Ancona, Italy
| | - Rosaria Meli
- Department of Pharmacy, School of Medicine, University of Naples Federico II, Naples, Italy
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7
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Carceller H, Guirado R, Nacher J. Dark exposure affects plasticity‐related molecules and interneurons throughout the visual system during adulthood. J Comp Neurol 2020; 528:1349-1366. [DOI: 10.1002/cne.24832] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Revised: 11/16/2019] [Accepted: 11/22/2019] [Indexed: 11/08/2022]
Affiliation(s)
- Hector Carceller
- Neurobiology Unit, Department of Cell Biology, Interdisciplinary Research Structure for Biotechnology and Biomedicine (BIOTECMED)Universitat de Valencia Valencia Spain
| | - Ramon Guirado
- Neurobiology Unit, Department of Cell Biology, Interdisciplinary Research Structure for Biotechnology and Biomedicine (BIOTECMED)Universitat de Valencia Valencia Spain
| | - Juan Nacher
- Neurobiology Unit, Department of Cell Biology, Interdisciplinary Research Structure for Biotechnology and Biomedicine (BIOTECMED)Universitat de Valencia Valencia Spain
- CIBERSAM: Spanish National Network for Research in Mental Health Madrid Spain
- Fundación Investigación Hospital Clínico de Valencia, INCLIVA Valencia Spain
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8
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McDonald AJ, Jones GC, Mott DD. Diverse glutamatergic inputs target spines expressing M1 muscarinic receptors in the basolateral amygdala: An ultrastructural analysis. Brain Res 2019; 1722:146349. [PMID: 31348911 PMCID: PMC6755062 DOI: 10.1016/j.brainres.2019.146349] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2019] [Revised: 07/21/2019] [Accepted: 07/22/2019] [Indexed: 11/19/2022]
Abstract
Although it is known that acetylcholine acting through M1 muscarinic receptors (M1Rs) is essential for memory consolidation in the anterior basolateral nucleus of the amygdala (BLa), virtually nothing is known about the circuits involved. In the hippocampus M1R activation facilitates long-term potentiation (LTP) by potentiating NMDA glutamate receptor (NMDAR) currents. The majority of NMDAR+ profiles in the BLa are spines. Since about half of dendritic spines of BLa pyramidal neurons (PNs) receiving glutamatergic inputs are M1R-immunoreactive (M1R+) it is possible that the role of M1Rs in BLa mnemonic functions also involves potentiation of NMDAR currents in spines. However, the finding that only about half of BLa spines are M1R+ suggests that this proposed mechanism may only apply to a subset of glutamatergic inputs. As a first step in the identification of differential glutamatergic inputs to M1R+ spines in the BLa, the present electron microscopic study used antibodies to two different vesicular glutamate transporter proteins (VGluTs) to label two different subsets of glutamatergic inputs to M1R+ spines. These inputs are largely complimentary with VGluT1+ inputs arising mainly from cortical structures and the basolateral nucleus, and VGluT2+ inputs arising mainly from the thalamus. It was found that about one-half of the spines that were postsynaptic to VGluT1+ or VGluT2+ terminals were M1R+. In addition, a subset of the VGluT1+ or VGluT2+ axon terminals were M1R+, including those that synapsed with M1R+ spines. These results suggest that acetylcholine can modulate glutamatergic inputs to BLa spines by presynaptic as well as postsynaptic M1R-mediated mechanisms.
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Affiliation(s)
- Alexander J McDonald
- Department of Pharmacology, Physiology and Neuroscience, University of South Carolina School of Medicine, Columbia, SC, USA.
| | - Grace C Jones
- Department of Pharmacology, Physiology and Neuroscience, University of South Carolina School of Medicine, Columbia, SC, USA
| | - David D Mott
- Department of Pharmacology, Physiology and Neuroscience, University of South Carolina School of Medicine, Columbia, SC, USA
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9
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Tulloch AJ, Teo S, Carvajal BV, Tessier-Lavigne M, Jaworski A. Diverse spinal commissural neuron populations revealed by fate mapping and molecular profiling using a novel Robo3 Cre mouse. J Comp Neurol 2019; 527:2948-2972. [PMID: 31152445 DOI: 10.1002/cne.24720] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Revised: 04/22/2019] [Accepted: 05/21/2019] [Indexed: 12/19/2022]
Abstract
The two sides of the nervous system coordinate and integrate information via commissural neurons, which project axons across the midline. Commissural neurons in the spinal cord are a highly heterogeneous population of cells with respect to their birthplace, final cell body position, axonal trajectory, and neurotransmitter phenotype. Although commissural axon guidance during development has been studied in great detail, neither the developmental origins nor the mature phenotypes of commissural neurons have been characterized comprehensively, largely due to lack of selective genetic access to these neurons. Here, we generated mice expressing Cre recombinase from the Robo3 locus specifically in commissural neurons. We used Robo3 Cre mice to characterize the transcriptome and various origins of developing commissural neurons, revealing new details about their extensive heterogeneity in molecular makeup and developmental lineage. Further, we followed the fate of commissural neurons into adulthood, thereby elucidating their settling positions and molecular diversity and providing evidence for possible functions in various spinal cord circuits. Our studies establish an important genetic entry point for further analyses of commissural neuron development, connectivity, and function.
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Affiliation(s)
- Alastair J Tulloch
- Department of Neuroscience, Brown University, Providence, Rhode Island.,Robert J. and Nancy D. Carney Institute for Brain Science, Providence, Rhode Island
| | - Shaun Teo
- Laboratory of Brain Development and Repair, The Rockefeller University, New York, New York
| | | | - Marc Tessier-Lavigne
- Laboratory of Brain Development and Repair, The Rockefeller University, New York, New York.,Department of Biology, Stanford University, Stanford, California
| | - Alexander Jaworski
- Department of Neuroscience, Brown University, Providence, Rhode Island.,Robert J. and Nancy D. Carney Institute for Brain Science, Providence, Rhode Island
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10
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Hoffmann J, Storer RJ, Park JW, Goadsby PJ. N-Methyl-d-aspartate receptor open-channel blockers memantine and magnesium modulate nociceptive trigeminovascular neurotransmission in rats. Eur J Neurosci 2019; 50:2847-2859. [PMID: 31009120 DOI: 10.1111/ejn.14423] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2017] [Revised: 04/02/2019] [Accepted: 04/05/2019] [Indexed: 02/01/2023]
Abstract
Experimental and clinical studies suggest that the low-affinity N-methyl-d-aspartate (NMDA) receptor open-channel blockers Mg2+ and memantine are effective in reducing trigeminal nociceptive activation. The aim of this study was to investigate the apparent effectiveness of these channel blockers using a model of trigeminal activation in vivo. Rats were anaesthetized before electrically stimulating the dura mater adjacent the middle meningeal artery. Neurons responding to stimulation were recorded extracellularly using electrophysiological methods. l-Glutamate or NMDA, and Mg2+ , memantine, or sodium controls were applied locally using microiontophoresis. Microiontophoretic application of Mg2+ or memantine into the trigeminocervical complex inhibited mechanically and electrically stimulated craniovascular afferents, and l-glutamate or NMDA-evoked neuronal activity at the second-order trigeminal synapse of craniovascular afferents. By contrast, intravenous administration of MgSO4 (100 mg/kg) or memantine (10 mg/kg) did not significantly affect electrically stimulated afferent-evoked activity within the trigeminocervical complex. The Mg2+ and memantine concentrations achieved after systemic administration may not effectively inhibit activation of the trigeminocervical complex, perhaps providing an explanation for the relatively poor efficacy of these NMDA receptor open-channel blockers for headache treatment in clinical studies. Nevertheless, the present results suggest blocking of NMDA-receptor open channels inhibits nociceptive activation of the trigeminocervical complex. Further exploration of such channel blockers as a therapeutic strategy for primary head pain is warranted.
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Affiliation(s)
- Jan Hoffmann
- Department of Neurology, University of California, San Francisco, California, USA.,Headache Group, Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK
| | - Robin James Storer
- Department of Neurology, University of California, San Francisco, California, USA.,Office of Research Affairs, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand
| | - Jeong-Wook Park
- Department of Neurology, Catholic University, Seoul, South Korea
| | - Peter J Goadsby
- Department of Neurology, University of California, San Francisco, California, USA.,Headache Group, Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK
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11
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Kameda H, Murabe N, Odagaki K, Mizukami H, Ozawa K, Sakurai M. Differential innervation within a transverse plane of spinal gray matter by sensorimotor cortices, with special reference to the somatosensory cortices. J Comp Neurol 2019; 527:1401-1415. [PMID: 30620045 DOI: 10.1002/cne.24626] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2018] [Revised: 12/07/2018] [Accepted: 12/20/2018] [Indexed: 11/06/2022]
Abstract
The corticospinal (CS) neurons projecting to the cervical cord distribute not only in motor-related cortical areas, but also in somatosensory areas, including the primary somatosensory cortex (S1). The exact functions of these widely distributed CS neurons are largely unknown, however. In this study, we injected mice with adeno-associated virus encoding membrane-binding fluorescent proteins to investigate the distribution of axons from CS neurons in different regions within a broad cortical area. We found that CS axons from the primary motor cortex (M1), the rostral part of S1 (S1r), and the caudal part of S1 (S1c) differentially project to specific compartments within the spinal gray matter of the seventh cervical cord segment: (a) M1 projects mainly to intermediate and ventral areas, (b) S1r to the mediodorsal area, and (c) S1c to the dorsolateral area. We also found that the projection from S1r, which corresponds to the forelimb area, largely overlaps the cutaneous afferent terminals from the forepaw (hand) in the dorsal horn, and we detected a similar relation between S1c and the trunk. Our findings suggest the existence of considerably fine somatotopic compartments within the dorsal horn that process somatosensation and descending information, which is provided mainly by S1 CS neurons and contribute to delicate control of sensory information in generation of movement.
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Affiliation(s)
- Hiroshi Kameda
- Department of Physiology, Teikyo University School of Medicine, Tokyo, Japan
| | - Naoyuki Murabe
- Department of Physiology, Teikyo University School of Medicine, Tokyo, Japan
| | - Kaoru Odagaki
- Department of Physiology, Teikyo University School of Medicine, Tokyo, Japan
| | - Hiroaki Mizukami
- Division of Genetic Therapeutics, Jichi Medical University, Tochigi, Japan
| | - Keiya Ozawa
- Division of Genetic Therapeutics, Jichi Medical University, Tochigi, Japan.,Division of Genetic Therapeutics, The Institute of Medical Science, The University of Tokyo, Tokyo, Japan
| | - Masaki Sakurai
- Department of Physiology, Teikyo University School of Medicine, Tokyo, Japan
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12
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Bragina L, Conti F. Expression of Neurofilament Subunits at Neocortical Glutamatergic and GABAergic Synapses. Front Neuroanat 2018; 12:74. [PMID: 30254572 PMCID: PMC6141662 DOI: 10.3389/fnana.2018.00074] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2018] [Accepted: 08/27/2018] [Indexed: 11/29/2022] Open
Abstract
Neurofilaments (NFs) are neuron-specific heteropolymers that have long been considered as structural proteins. However, it has recently been documented that they may play a functional role at synapses. Indeed, the four NF subunits—NFL, NFM, NFH and α-internexin—are integral components of synapses in the striatum and hippocampus, since their elimination disrupts synaptic plasticity and impairs social memory, an observation that might have important implications for some neuropsychiatric diseases. Here, we studied NFs localization in VGLUT1-, VGLUT2-, VGAT-, PSD-95- and gephyrin-positive (+) puncta, and in glutamatergic and GABAergic synapses in the cerebral cortex of adult rats. Synapses were identified by pre- and postsynaptic markers: glutamatergic synapses by VGLUT1+ or VGLUT2+ puncta contacting PSD-95+ puncta; and GABAergic synapses by VGAT+ puncta contacting gephyrin+ puncta. In VGLUT1 glutamatergic synapses NF showed a greater expression in the compartment labeled by postsynaptic markers (20%–30%) than in those labeled by presynaptic markers (10%–20%), whereas in GABAergic synapses a similar expression was detected in both compartments (20%–30%). Moreover, NF expression was higher in the GABAergic (20%–30%) than in the glutamatergic (10%–15%) compartments labeled by presynaptic markers. Finally, a higher colocalization of VGLUT1+, VGLUT2+ and VGAT+ puncta with NFs was seen when presynaptic puncta contacted elements labeled by postsynaptic markers. These findings show that the four NF subunits are expressed at some neocortical synapses, and contribute to glutamatergic and GABAergic synapse heterogeneity.
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Affiliation(s)
- Luca Bragina
- Section of Neuroscience and Cell Biology, Department of Experimental and Clinical Medicine, Università Politecnica delle Marche, Ancona, Italy.,Center for Neurobiology of Aging, IRCCS INRCA, Ancona, Italy
| | - Fiorenzo Conti
- Section of Neuroscience and Cell Biology, Department of Experimental and Clinical Medicine, Università Politecnica delle Marche, Ancona, Italy.,Center for Neurobiology of Aging, IRCCS INRCA, Ancona, Italy
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13
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Oda S, Tsuneoka Y, Yoshida S, Adachi-Akahane S, Ito M, Kuroda M, Funato H. Immunolocalization of muscarinic M1 receptor in the rat medial prefrontal cortex. J Comp Neurol 2018; 526:1329-1350. [PMID: 29424434 PMCID: PMC5900831 DOI: 10.1002/cne.24409] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2017] [Revised: 01/23/2018] [Accepted: 01/27/2018] [Indexed: 12/20/2022]
Abstract
The medial prefrontal cortex (mPFC) has been considered to participate in many higher cognitive functions, such as memory formation and spatial navigation. These cognitive functions are modulated by cholinergic afferents via muscarinic acetylcholine receptors. Previous pharmacological studies have strongly suggested that the M1 receptor (M1R) is the most important subtype among muscarinic receptors to perform these cognitive functions. Actually, M1R is abundant in mPFC. However, the proportion of somata containing M1R among cortical cellular types, and the precise intracellular localization of M1R remain unclear. In this study, to clarify the precise immunolocalization of M1R in rat mPFC, we examined three major cellular types, pyramidal neurons, inhibitory neurons, and astrocytes. M1R immunopositivity signals were found in the majority of the somata of both pyramidal neurons and inhibitory neurons. In pyramidal neurons, strong M1R immunopositivity signals were usually found throughout their somata and dendrites including spines. On the other hand, the signal strength of M1R immunopositivity in the somata of inhibitory neurons significantly varied. Some neurons showed strong signals. Whereas about 40% of GAD67‐immunopositive neurons and 30% of parvalbumin‐immunopositive neurons (PV neurons) showed only weak signals. In PV neurons, M1R immunopositivity signals were preferentially distributed in somata. Furthermore, we found that many astrocytes showed substantial M1R immunopositivity signals. These signals were also mainly distributed in their somata. Thus, the distribution pattern of M1R markedly differs between cellular types. This difference might underlie the cholinergic modulation of higher cognitive functions subserved by mPFC.
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Affiliation(s)
- Satoko Oda
- Department of Anatomy, Faculty of Medicine, Toho University, Tokyo, 143-8540, Japan
| | - Yousuke Tsuneoka
- Department of Anatomy, Faculty of Medicine, Toho University, Tokyo, 143-8540, Japan
| | - Sachine Yoshida
- Department of Anatomy, Faculty of Medicine, Toho University, Tokyo, 143-8540, Japan.,Precursory Research for Embryonic Science and Technology (PRESTO), Japan Science and Technology Agency, Saitama, 332-0012, Japan
| | - Satomi Adachi-Akahane
- Department of Physiology, Faculty of Medicine, Toho University, Tokyo, 143-8540, Japan
| | - Masanori Ito
- Department of Physiology, Faculty of Medicine, Toho University, Tokyo, 143-8540, Japan
| | - Masaru Kuroda
- Department of Anatomy, Faculty of Medicine, Toho University, Tokyo, 143-8540, Japan
| | - Hiromasa Funato
- Department of Anatomy, Faculty of Medicine, Toho University, Tokyo, 143-8540, Japan.,International institute for integrative sleep medicine (IIIS), Tsukuba University, Ibaraki, 305-8575, Japan
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14
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Mitochondrial Ultrastructure Is Coupled to Synaptic Performance at Axonal Release Sites. eNeuro 2018; 5:eN-NWR-0390-17. [PMID: 29383328 PMCID: PMC5788698 DOI: 10.1523/eneuro.0390-17.2018] [Citation(s) in RCA: 56] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2017] [Revised: 12/28/2017] [Accepted: 01/06/2018] [Indexed: 01/08/2023] Open
Abstract
Mitochondrial function in neurons is tightly linked with metabolic and signaling mechanisms that ultimately determine neuronal performance. The subcellular distribution of these organelles is dynamically regulated as they are directed to axonal release sites on demand, but whether mitochondrial internal ultrastructure and molecular properties would reflect the actual performance requirements in a synapse-specific manner, remains to be established. Here, we examined performance-determining ultrastructural features of presynaptic mitochondria in GABAergic and glutamatergic axons of mice and human. Using electron-tomography and super-resolution microscopy we found, that these features were coupled to synaptic strength: mitochondria in boutons with high synaptic activity exhibited an ultrastructure optimized for high rate metabolism and contained higher levels of the respiratory chain protein cytochrome-c (CytC) than mitochondria in boutons with lower activity. The strong, cell type-independent correlation between mitochondrial ultrastructure, molecular fingerprints and synaptic performance suggests that changes in synaptic activity could trigger ultrastructural plasticity of presynaptic mitochondria, likely to adjust their performance to the actual metabolic demand.
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15
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Marcotulli D, Fattorini G, Bragina L, Perugini J, Conti F. Levetiracetam Affects Differentially Presynaptic Proteins in Rat Cerebral Cortex. Front Cell Neurosci 2017; 11:389. [PMID: 29311825 PMCID: PMC5732259 DOI: 10.3389/fncel.2017.00389] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2017] [Accepted: 11/24/2017] [Indexed: 01/23/2023] Open
Abstract
Presynaptic proteins are potential therapeutic targets for epilepsy and other neurological diseases. We tested the hypothesis that chronic treatment with the SV2A ligand levetiracetam affects the expression of other presynaptic proteins. Results showed that in rat neocortex no significant difference was detected in SV2A protein levels in levetiracetam treated animals compared to controls, whereas levetiracetam post-transcriptionally decreased several vesicular proteins and increased LRRK2, without any change in mRNA levels. Analysis of SV2A interactome indicates that the presynaptic proteins regulation induced by levetiracetam reported here is mediated by this interactome, and suggests that LRRK2 plays a role in forging the pattern of effects.
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Affiliation(s)
- Daniele Marcotulli
- Department of Experimental and Clinical Medicine, Università Politecnica delle Marche, Ancona, Italy
| | - Giorgia Fattorini
- Department of Experimental and Clinical Medicine, Università Politecnica delle Marche, Ancona, Italy.,Center for Neurobiology of Aging, INRCA IRCCS, Ancona, Italy
| | - Luca Bragina
- Department of Experimental and Clinical Medicine, Università Politecnica delle Marche, Ancona, Italy.,Center for Neurobiology of Aging, INRCA IRCCS, Ancona, Italy
| | - Jessica Perugini
- Department of Experimental and Clinical Medicine, Università Politecnica delle Marche, Ancona, Italy
| | - Fiorenzo Conti
- Department of Experimental and Clinical Medicine, Università Politecnica delle Marche, Ancona, Italy.,Center for Neurobiology of Aging, INRCA IRCCS, Ancona, Italy
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16
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Fattorini G, Ciriachi C, Conti F. Few, Activity-Dependent, and Ubiquitous VGLUT1/VGAT Terminals in Rat and Mouse Brain. Front Cell Neurosci 2017; 11:229. [PMID: 28848395 PMCID: PMC5550726 DOI: 10.3389/fncel.2017.00229] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2017] [Accepted: 07/20/2017] [Indexed: 11/13/2022] Open
Abstract
In the neocortex of adult rats VGLUT1 and VGAT co-localize in axon terminals which form both symmetric and asymmetric synapses. They are expressed in the same synaptic vesicles which participate in the exo-endocytotic cycle. Virtually nothing, however, is known on whether VGLUT1/VGAT co-localization occurs in other brain regions. We therefore mapped the distribution of terminals co-expressing VGLUT1/VGAT in the striatum, hippocampus, thalamus, and cerebellar and cerebral cortices of rats and mice. Confocal microscopy analysis revealed that, in both rat and mouse brain, VGLUT1/VGAT+ terminals were present in all brain regions studied, and that their percentage was low and comparable in both species. These results provide the first demonstration that co-expression of VGLUT1 and VGAT is a widespread phenomenon. Since VGLUT1/VGAT+ axon terminals are regulated in an activity-dependent manner and co-release glutamate and GABA, we hypothesize that, though not numerous, they can contribute to regulating excitation/inhibition balance in physiological conditions, thereby playing a role in several neurological and psychiatric diseases.
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Affiliation(s)
- Giorgia Fattorini
- Department of Experimental and Clinical Medicine, Section of Neuroscience and Cell Biology, Università Politecnica delle MarcheAncona, Italy.,Center for Neurobiology of Aging, Istituto Nazionale di Riposo e Cura per Anziani - Istituto di Ricovero e Cura a Carattere ScientificoAncona, Italy
| | - Chiara Ciriachi
- Department of Experimental and Clinical Medicine, Section of Neuroscience and Cell Biology, Università Politecnica delle MarcheAncona, Italy
| | - Fiorenzo Conti
- Department of Experimental and Clinical Medicine, Section of Neuroscience and Cell Biology, Università Politecnica delle MarcheAncona, Italy.,Center for Neurobiology of Aging, Istituto Nazionale di Riposo e Cura per Anziani - Istituto di Ricovero e Cura a Carattere ScientificoAncona, Italy.,Fondazione di Medicina Molecolare, Università Politecnica delle MarcheAncona, Italy
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17
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Axonal Type III Nrg1 Controls Glutamate Synapse Formation and GluA2 Trafficking in Hippocampal-Accumbens Connections. eNeuro 2017; 4:eN-NWR-0232-16. [PMID: 28275713 PMCID: PMC5329619 DOI: 10.1523/eneuro.0232-16.2017] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2016] [Revised: 01/23/2017] [Accepted: 02/06/2017] [Indexed: 11/21/2022] Open
Abstract
Altered neuregulin 1 (Nrg1)/ErbB signaling and glutamatergic hypofunction have been implicated in the pathophysiology of schizophrenia. Here, we employed gene chimeric ventral hippocampus (vHipp)-nucleus accumbens (nAcc) coculture from mouse, electrophysiology, immunocytochemistry, FM1-43 vesicle fusion, and electron microscopy techniques to examine the pre- and postsynaptic mechanisms of genetic deficits in Nrg1/ErbB signaling-induced glutamatergic dysfunctions. Reduced presynaptic type III Nrg1 expression along vHipp axons decreases the number of glutamate synapses and impairs GluA2 trafficking in the postsynaptic nAcc neurons, resulting in decreased frequency and amplitude of miniature EPSCs (mEPSCs). Reduced expression of axonal type III Nrg1 along vHipp projections also decreases functional synaptic vesicle (SV) clustering and vesicular trafficking to presynaptic vHipp axonal terminals. These findings suggest that Nrg1/ErbB signaling modulate glutamatergic transmission via both pre- and postsynaptic mechanisms.
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18
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Capuani C, Melone M, Tottene A, Bragina L, Crivellaro G, Santello M, Casari G, Conti F, Pietrobon D. Defective glutamate and K+ clearance by cortical astrocytes in familial hemiplegic migraine type 2. EMBO Mol Med 2016; 8:967-86. [PMID: 27354390 PMCID: PMC4967947 DOI: 10.15252/emmm.201505944] [Citation(s) in RCA: 105] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Migraine is a common disabling brain disorder. A subtype of migraine with aura (familial hemiplegic migraine type 2: FHM2) is caused by loss‐of‐function mutations in α2 Na+,K+ATPase (α2NKA), an isoform almost exclusively expressed in astrocytes in adult brain. Cortical spreading depression (CSD), the phenomenon that underlies migraine aura and activates migraine headache mechanisms, is facilitated in heterozygous FHM2‐knockin mice with reduced expression of α2NKA. The mechanisms underlying an increased susceptibility to CSD in FHM2 are unknown. Here, we show reduced rates of glutamate and K+ clearance by cortical astrocytes during neuronal activity and reduced density of GLT‐1a glutamate transporters in cortical perisynaptic astrocytic processes in heterozygous FHM2‐knockin mice, demonstrating key physiological roles of α2NKA and supporting tight coupling with GLT‐1a. Using ceftriaxone treatment of FHM2 mutants and partial inhibition of glutamate transporters in wild‐type mice, we obtain evidence that defective glutamate clearance can account for most of the facilitation of CSD initiation in FHM2‐knockin mice, pointing to excessive glutamatergic transmission as a key mechanism underlying the vulnerability to CSD ignition in migraine.
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Affiliation(s)
- Clizia Capuani
- Department of Biomedical Sciences, University of Padova, Padova, Italy
| | - Marcello Melone
- Department of Experimental and Clinical Medicine, Università Politecnica delle Marche, Ancona, Italy Center for Neurobiology of Aging, INRCA IRCCS, Ancona, Italy
| | - Angelita Tottene
- Department of Biomedical Sciences, University of Padova, Padova, Italy
| | - Luca Bragina
- Department of Experimental and Clinical Medicine, Università Politecnica delle Marche, Ancona, Italy Center for Neurobiology of Aging, INRCA IRCCS, Ancona, Italy
| | | | - Mirko Santello
- Institute of Pharmacology and Toxicology, University of Zurich, Zürich, Switzerland
| | - Giorgio Casari
- Vita-Salute San Raffaele University and San Raffaele Scientific Institute, Milano, Italy
| | - Fiorenzo Conti
- Department of Experimental and Clinical Medicine, Università Politecnica delle Marche, Ancona, Italy Center for Neurobiology of Aging, INRCA IRCCS, Ancona, Italy Fondazione di Medicina Molecolare, Università Politecnica delle Marche, Ancona, Italy
| | - Daniela Pietrobon
- Department of Biomedical Sciences, University of Padova, Padova, Italy CNR Institute of Neuroscience, Padova, Italy
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19
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Bragina L, Bonifacino T, Bassi S, Milanese M, Bonanno G, Conti F. Differential expression of metabotropic glutamate and GABA receptors at neocortical glutamatergic and GABAergic axon terminals. Front Cell Neurosci 2015; 9:345. [PMID: 26388733 PMCID: PMC4559644 DOI: 10.3389/fncel.2015.00345] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2015] [Accepted: 08/18/2015] [Indexed: 12/04/2022] Open
Abstract
Metabotropic glutamate (Glu) receptors (mGluRs) and GABAB receptors are highly expressed at presynaptic sites. To verify the possibility that the two classes of metabotropic receptors contribute to axon terminals heterogeneity, we studied the localization of mGluR1α, mGluR5, mGluR2/3, mGluR7, and GABAB1 in VGLUT1-, VGLUT2-, and VGAT- positive terminals in the cerebral cortex of adult rats. VGLUT1-positive puncta expressed mGluR1α (∼5%), mGluR5 (∼6%), mGluR2/3 (∼22%), mGluR7 (∼17%), and GABAB1 (∼40%); VGLUT2-positive terminals expressed mGluR1α (∼10%), mGluR5 (∼11%), mGluR2/3 (∼20%), mGluR7 (∼28%), and GABAB1 (∼25%); whereas VGAT-positive puncta expressed mGluR1α (∼27%), mGluR5 (∼24%), mGluR2/3 (∼38%), mGluR7 (∼31%), and GABAB1 (∼19%). Control experiments ruled out the possibility that postsynaptic mGluRs and GABAB1 might have significantly biased our results. We also performed functional assays in synaptosomal preparations, and showed that all agonists modify Glu and GABA levels, which return to baseline upon exposure to antagonists. Overall, these findings indicate that mGluR1α, mGluR5, mGluR2/3, mGluR7, and GABAB1 expression differ significantly between glutamatergic and GABAergic axon terminals, and that the robust expression of heteroreceptors may contribute to the homeostatic regulation of the balance between excitation and inhibition.
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Affiliation(s)
- Luca Bragina
- Section of Neuroscience and Cell Biology, Department of Experimental and Clinical Medicine, Università Politecnica delle MarcheAncona, Italy
- Center for Neurobiology of Aging, Istituto Nazionale di Riposo e Cura per Anziani – Istituto di Ricovero e Cura a Carattere ScientificoAncona, Italy
| | - Tiziana Bonifacino
- Department of Pharmacy, Unit of Pharmacology and Toxicology, University of GenoaGenoa, Italy
| | - Silvia Bassi
- Section of Neuroscience and Cell Biology, Department of Experimental and Clinical Medicine, Università Politecnica delle MarcheAncona, Italy
| | - Marco Milanese
- Department of Pharmacy, Unit of Pharmacology and Toxicology, University of GenoaGenoa, Italy
| | - Giambattista Bonanno
- Department of Pharmacy, Unit of Pharmacology and Toxicology, University of GenoaGenoa, Italy
- Center of Excellence for Biomedical Research, University of GenoaGenoa, Italy
| | - Fiorenzo Conti
- Section of Neuroscience and Cell Biology, Department of Experimental and Clinical Medicine, Università Politecnica delle MarcheAncona, Italy
- Center for Neurobiology of Aging, Istituto Nazionale di Riposo e Cura per Anziani – Istituto di Ricovero e Cura a Carattere ScientificoAncona, Italy
- Fondazione di Medicina Molecolare, Università Politecnica delle MarcheAncona, Italy
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20
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Hackett TA, Clause AR, Takahata T, Hackett NJ, Polley DB. Differential maturation of vesicular glutamate and GABA transporter expression in the mouse auditory forebrain during the first weeks of hearing. Brain Struct Funct 2015; 221:2619-73. [PMID: 26159773 DOI: 10.1007/s00429-015-1062-3] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2014] [Accepted: 05/07/2015] [Indexed: 02/04/2023]
Abstract
Vesicular transporter proteins are an essential component of the presynaptic machinery that regulates neurotransmitter storage and release. They also provide a key point of control for homeostatic signaling pathways that maintain balanced excitation and inhibition following changes in activity levels, including the onset of sensory experience. To advance understanding of their roles in the developing auditory forebrain, we tracked the expression of the vesicular transporters of glutamate (VGluT1, VGluT2) and GABA (VGAT) in primary auditory cortex (A1) and medial geniculate body (MGB) of developing mice (P7, P11, P14, P21, adult) before and after ear canal opening (~P11-P13). RNA sequencing, in situ hybridization, and immunohistochemistry were combined to track changes in transporter expression and document regional patterns of transcript and protein localization. Overall, vesicular transporter expression changed the most between P7 and P21. The expression patterns and maturational trajectories of each marker varied by brain region, cortical layer, and MGB subdivision. VGluT1 expression was highest in A1, moderate in MGB, and increased with age in both regions. VGluT2 mRNA levels were low in A1 at all ages, but high in MGB, where adult levels were reached by P14. VGluT2 immunoreactivity was prominent in both regions. VGluT1 (+) and VGluT2 (+) transcripts were co-expressed in MGB and A1 somata, but co-localization of immunoreactive puncta was not detected. In A1, VGAT mRNA levels were relatively stable from P7 to adult, while immunoreactivity increased steadily. VGAT (+) transcripts were rare in MGB neurons, whereas VGAT immunoreactivity was robust at all ages. Morphological changes in immunoreactive puncta were found in two regions after ear canal opening. In the ventral MGB, a decrease in VGluT2 puncta density was accompanied by an increase in puncta size. In A1, perisomatic VGAT and VGluT1 terminals became prominent around the neuronal somata. Overall, the observed changes in gene and protein expression, regional architecture, and morphology relate to-and to some extent may enable-the emergence of mature sound-evoked activity patterns. In that regard, the findings of this study expand our understanding of the presynaptic mechanisms that regulate critical period formation associated with experience-dependent refinement of sound processing in auditory forebrain circuits.
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Affiliation(s)
- Troy A Hackett
- Department of Hearing and Speech Sciences, Vanderbilt University School of Medicine, 465 21st Avenue South, MRB-3 Suite 7110, Nashville, TN, 37232, USA.
| | - Amanda R Clause
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear Infirmary, Department of Otology and Laryngology, Harvard Medical School, Boston, MA, USA
| | - Toru Takahata
- Department of Hearing and Speech Sciences, Vanderbilt University School of Medicine, 465 21st Avenue South, MRB-3 Suite 7110, Nashville, TN, 37232, USA
| | | | - Daniel B Polley
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear Infirmary, Department of Otology and Laryngology, Harvard Medical School, Boston, MA, USA
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21
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Burette AC, Phend KD, Burette S, Lin Q, Liang M, Foltz G, Taylor N, Wang Q, Brandon NJ, Bates B, Ehlers MD, Weinberg RJ. Organization of TNIK in dendritic spines. J Comp Neurol 2015; 523:1913-24. [PMID: 25753355 DOI: 10.1002/cne.23770] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2014] [Revised: 02/25/2015] [Accepted: 02/26/2015] [Indexed: 01/16/2023]
Abstract
Tumor necrosis factor receptor-associated factor 2 (TRAF2)- and noncatalytic region of tyrosine kinase (NCK)-interacting kinase (TNIK) has been identified as an interactor in the psychiatric risk factor, Disrupted in Schizophrenia 1 (DISC1). As a step toward deciphering its function in the brain, we performed high-resolution light and electron microscopic immunocytochemistry. We demonstrate here that TNIK is expressed in neurons throughout the adult mouse brain. In striatum and cerebral cortex, TNIK concentrates in dendritic spines, especially in the vicinity of the lateral edge of the synapse. Thus, TNIK is highly enriched at a microdomain critical for glutamatergic signaling.
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Affiliation(s)
- Alain C Burette
- Department of Cell Biology & Physiology, University of North Carolina, Chapel Hill, North Carolina, 27599
| | - Kristen D Phend
- Department of Cell Biology & Physiology, University of North Carolina, Chapel Hill, North Carolina, 27599
| | - Susan Burette
- Department of Cell Biology & Physiology, University of North Carolina, Chapel Hill, North Carolina, 27599
| | - Qingcong Lin
- Shenogen Pharma Group, Beijing, People's Republic of China 102206
| | - Musen Liang
- Department of Pharmacokinetics, Dynamics, and Metabolism, Pfizer, Andover, Massachusetts 01810
| | - Gretchen Foltz
- Clinical Research Unit, Pfizer, New Haven, Connecticut 06511
| | - Noël Taylor
- Biomarker and Personalized Medicine Group, Eisai Product Creation Systems, Eisai, Andover, Massachusetts 01810
| | - Qi Wang
- Neuroscience Research Unit, Pfizer, Cambridge, Massachusetts 02139
| | | | - Brian Bates
- Centers for Therapeutic Innovation, Pfizer, Boston, Massachusetts 02115
| | - Michael D Ehlers
- Neuroscience Research Unit, Pfizer, Cambridge, Massachusetts 02139
| | - Richard J Weinberg
- Department of Cell Biology & Physiology, University of North Carolina, Chapel Hill, North Carolina, 27599.,Neuroscience Center, University of North Carolina, Chapel Hill, North Carolina, 27599
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22
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Abstract
Synapses of the mammalian CNS are diverse in size, structure, molecular composition, and function. Synapses in their myriad variations are fundamental to neural circuit development, homeostasis, plasticity, and memory storage. Unfortunately, quantitative analysis and mapping of the brain's heterogeneous synapse populations has been limited by the lack of adequate single-synapse measurement methods. Electron microscopy (EM) is the definitive means to recognize and measure individual synaptic contacts, but EM has only limited abilities to measure the molecular composition of synapses. This report describes conjugate array tomography (AT), a volumetric imaging method that integrates immunofluorescence and EM imaging modalities in voxel-conjugate fashion. We illustrate the use of conjugate AT to advance the proteometric measurement of EM-validated single-synapse analysis in a study of mouse cortex.
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23
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Fattorini G, Antonucci F, Menna E, Matteoli M, Conti F. Co-expression of VGLUT1 and VGAT sustains glutamate and GABA co-release and is regulated by activity in cortical neurons. J Cell Sci 2015; 128:1669-73. [PMID: 25749864 DOI: 10.1242/jcs.164210] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2014] [Accepted: 02/26/2015] [Indexed: 02/02/2023] Open
Abstract
In adult neocortex, VGLUT1 (also known as SLC17A7), the main glutamate vesicular transporter, and VGAT (also known as SLC32A1), the γ-aminobutyric acid (GABA) vesicular transporter, are co-expressed in a subset of axon terminals forming both symmetric and asymmetric synapses, where they are sorted into the same vesicles. However, the functional consequence of this colocalization in cortical neurons has not been clarified. Here, we tested the hypothesis that cortical axon terminals co-expressing VGLUT1 and VGAT can evoke simultaneously monosynaptic glutamate and GABA responses, and investigated whether the amount of terminals co-expressing VGLUT1 and VGAT is affected by perturbations of excitation-inhibition balance. In rat primary cortical neurons, we found that a proportion of synaptic and autaptic responses were indeed sensitive to consecutive application of selective glutamate and GABAA receptor blockers. These 'mixed' synapses exhibited paired-pulse depression. Notably, reducing the activity of the neuronal network by treatment with glutamate receptor antagonists decreased the amount of 'mixed' synapses, whereas reducing spontaneous inhibition by treatment with bicuculline increased them. These synapses might contribute to homeostatic regulation of excitation-inhibition balance.
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Affiliation(s)
- Giorgia Fattorini
- Department of Experimental and Clinical Medicine, Università Politecnica delle Marche, 60126 Ancona, Italy Center for Neurobiology of Aging, INRCA IRCCS, 60121 Ancona, Italy
| | - Flavia Antonucci
- Department of Medical Biotechnology and Translational Medicine, University of Milan, 20129 Milano, Italy CNR Institute of Neuroscience, 20129 Milano, Italy
| | - Elisabetta Menna
- CNR Institute of Neuroscience, 20129 Milano, Italy Istituto Clinico Humanitas, IRCCS, 20089 Rozzano (Milano), Italy
| | - Michela Matteoli
- CNR Institute of Neuroscience, 20129 Milano, Italy Istituto Clinico Humanitas, IRCCS, 20089 Rozzano (Milano), Italy
| | - Fiorenzo Conti
- Department of Experimental and Clinical Medicine, Università Politecnica delle Marche, 60126 Ancona, Italy Center for Neurobiology of Aging, INRCA IRCCS, 60121 Ancona, Italy Fondazione di Medicina Molecolare, Università Politecnica delle Marche, 60126 Ancona, Italy
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24
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Oda S, Funato H, Sato F, Adachi-Akahane S, Ito M, Takase K, Kuroda M. A subset of thalamocortical projections to the retrosplenial cortex possesses two vesicular glutamate transporter isoforms, VGluT1 and VGluT2, in axon terminals and somata. J Comp Neurol 2015; 522:2089-106. [PMID: 24639017 DOI: 10.1002/cne.23519] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2013] [Revised: 11/21/2013] [Accepted: 12/04/2013] [Indexed: 01/14/2023]
Abstract
Vesicular glutamate transporter isoforms, VGluT1-VGluT3, accumulate glutamate into synaptic vesicles and are considered to be important molecules in glutamatergic transmission. Among them, VGluT2 mRNA is expressed predominantly throughout the dorsal thalamus, whereas VGluT1 mRNA is expressed in a few thalamic nuclei. In the thalamic nuclei that project to the retrosplenial cortex (RSC), VGluT1 mRNA is expressed strongly in the anterodorsal thalamic nucleus (AD), is expressed moderately in the anteroventral and laterodorsal thalamic nuclei, and is not expressed in the anteromedial thalamic nucleus. Thus, it has been strongly suggested that a subset of thalamocortical projections to RSC possesses both VGluT1 and VGluT2. In this study, double-labeled neuronal somata showing both VGluT1 and VGluT2 immunolabelings were found exclusively in the ventral region of AD (vAD). Many double-labeled axon terminals were also found in two major targets of vAD, the rostral part of the reticular thalamic nucleus and layers Ia and III-IV of the retrosplenial granular b cortex (RSGb). Some were also found in layer Ia of the retrosplenial granular a cortex (RSGa). These axon terminals contain significant amounts of both VGluTs. Because the subset of thalamocortical projections to RSC has a unique molecular basis in the glutamatergic transmission system, it might play an important role in the higher cognitive functions processed in the RSC. Furthermore, double-labeled axon terminals of a different type were distributed in RSGb and RSGa. Because they are small and the immunoreactivity of VGluT2 is significantly weaker than that of VGluT1, they seemed to be a subset of corticocortical terminals.
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Affiliation(s)
- Satoko Oda
- Department of Anatomy, School of Medicine, Toho University, Tokyo, 143-8540, Japan
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25
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Abstract
Anatomically incomplete spinal cord injuries are often followed by considerable functional recovery in patients and animal models, largely because of processes of neuronal plasticity. In contrast to the corticospinal system, where sprouting of fibers and rearrangements of circuits in response to lesions have been well studied, structural adaptations within descending brainstem pathways and intraspinal networks are poorly investigated, despite the recognized physiological significance of these systems across species. In the present study, spontaneous neuroanatomical plasticity of severed bulbospinal systems and propriospinal neurons was investigated following unilateral C4 spinal hemisection in adult rats. Injection of retrograde tracer into the ipsilesional segments C3-C4 revealed a specific increase in the projection from the ipsilesional gigantocellular reticular nucleus in response to the injury. Substantial regenerative fiber sprouting of reticulospinal axons above the injury site was demonstrated by anterograde tracing. Regrowing reticulospinal fibers exhibited excitatory, vGLUT2-positive varicosities, indicating their synaptic integration into spinal networks. Reticulospinal fibers formed close appositions onto descending, double-midline crossing C3-C4 propriospinal neurons, which crossed the lesion site in the intact half of the spinal cord and recrossed to the denervated cervical hemicord below the injury. These propriospinal projections around the lesion were significantly enhanced after injury. Our results suggest that severed reticulospinal fibers, which are part of the phylogenetically oldest motor command system, spontaneously arborize and form contacts onto a plastic propriospinal relay, thereby bypassing the lesion. These rearrangements were accompanied by substantial locomotor recovery, implying a potential physiological relevance of the detour in restoration of motor function after spinal injury.
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Fuentes-Santamaría V, Alvarado JC, Rodríguez-de la Rosa L, Murillo-Cuesta S, Contreras J, Juiz JM, Varela-Nieto I. IGF-1 deficiency causes atrophic changes associated with upregulation of VGluT1 and downregulation of MEF2 transcription factors in the mouse cochlear nuclei. Brain Struct Funct 2014; 221:709-34. [PMID: 25378055 DOI: 10.1007/s00429-014-0934-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2014] [Accepted: 10/28/2014] [Indexed: 02/08/2023]
Abstract
Insulin-like growth factor 1 (IGF-1) is a neurotrophic protein that plays a crucial role in modulating neuronal function and synaptic plasticity in the adult brain. Mice lacking the Igf1 gene exhibit profound deafness and multiple anomalies in the inner ear and spiral ganglion. An issue that remains unknown is whether, in addition to these peripheral abnormalities, IGF-1 deficiency also results in structural changes along the central auditory pathway that may contribute to an imbalance between excitation and inhibition, which might be reflected in abnormal auditory brainstem responses (ABR). To assess such a possibility, we evaluated the morphological and physiological alterations in the cochlear nucleus complex of the adult mouse. The expression and distribution of the vesicular glutamate transporter 1 (VGluT1) and the vesicular inhibitory transporter (VGAT), which were used as specific markers for labeling excitatory and inhibitory terminals, and the involvement of the activity-dependent myocyte enhancer factor 2 (MEF2) transcription factors in regulating excitatory synapses were assessed in a 4-month-old mouse model of IGF-1 deficiency and neurosensorial deafness (Igf1 (-/-) homozygous null mice). The results demonstrate decreases in the cochlear nucleus area and cell size along with cell loss in the cochlear nuclei of the deficient mouse. Additionally, our results demonstrate that there is upregulation of VGluT1, but not VGAT, immunostaining and downregulation of MEF2 transcription factors together with increased wave II amplitude in the ABR recording. Our observations provide evidence of an abnormal neuronal cytoarchitecture in the cochlear nuclei of Igf1 (-/-) null mice and suggest that the increased efficacy of glutamatergic synapses might be mediated by MEF2 transcription factors.
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Affiliation(s)
- V Fuentes-Santamaría
- Instituto de Investigación en Discapacidades Neurológicas (IDINE), Albacete, Spain.
| | - J C Alvarado
- Instituto de Investigación en Discapacidades Neurológicas (IDINE), Albacete, Spain
| | - L Rodríguez-de la Rosa
- Facultad de Medicina, Universidad de Castilla-La Mancha, Campus de Albacete. C/Almansa, 14, 02006, Albacete, Spain
| | - S Murillo-Cuesta
- Grupo de Neurobiología de la Audición, Instituto de Investigaciones Biomédicas Alberto Sols, Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid, Madrid, Spain.,Centro Investigaciones Biomédicas en Red de Enfermedades Raras (CIBERER), Instituto de Salud Carlos III, Madrid, Spain.,IdiPAZ Instituto de Investigación en Salud, Madrid, Spain
| | - J Contreras
- Grupo de Neurobiología de la Audición, Instituto de Investigaciones Biomédicas Alberto Sols, Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid, Madrid, Spain.,Centro Investigaciones Biomédicas en Red de Enfermedades Raras (CIBERER), Instituto de Salud Carlos III, Madrid, Spain.,IdiPAZ Instituto de Investigación en Salud, Madrid, Spain.,Facultad de Veterinaria, Universidad Complutense, Madrid, Spain
| | - J M Juiz
- Instituto de Investigación en Discapacidades Neurológicas (IDINE), Albacete, Spain
| | - I Varela-Nieto
- Grupo de Neurobiología de la Audición, Instituto de Investigaciones Biomédicas Alberto Sols, Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid, Madrid, Spain.,Centro Investigaciones Biomédicas en Red de Enfermedades Raras (CIBERER), Instituto de Salud Carlos III, Madrid, Spain.,IdiPAZ Instituto de Investigación en Salud, Madrid, Spain
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27
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Deng YP, Wong T, Wan JY, Reiner A. Differential loss of thalamostriatal and corticostriatal input to striatal projection neuron types prior to overt motor symptoms in the Q140 knock-in mouse model of Huntington's disease. Front Syst Neurosci 2014; 8:198. [PMID: 25360089 PMCID: PMC4197654 DOI: 10.3389/fnsys.2014.00198] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2014] [Accepted: 09/23/2014] [Indexed: 11/13/2022] Open
Abstract
Motor slowing and forebrain white matter loss have been reported in premanifest Huntington's disease (HD) prior to substantial striatal neuron loss. These findings raise the possibility that early motor defects in HD may be related to loss of excitatory input to striatum. In a prior study, we showed that in the heterozygous Q140 knock-in mouse model of HD that loss of thalamostriatal axospinous terminals is evident by 4 months, and loss of corticostriatal axospinous terminals is evident at 12 months, before striatal projection neuron pathology. In the present study, we specifically characterized the loss of thalamostriatal and corticostriatal terminals on direct (dSPN) and indirect (iSPN) pathway striatal projection neurons, using immunolabeling to identify thalamostriatal (VGLUT2+) and corticostriatal (VGLUT1+) axospinous terminals, and D1 receptor immunolabeling to distinguish dSPN (D1+) and iSPN (D1-) synaptic targets. We found that the loss of corticostriatal terminals at 12 months of age was preferential for D1+ spines, and especially involved smaller terminals, presumptively of the intratelencephalically projecting (IT) type. By contrast, indirect pathway D1- spines showed little loss of axospinous terminals at the same age. Thalamostriatal terminal loss was comparable for D1+ and D1- spines at both 4 and 12 months. Regression analysis showed that the loss of VGLUT1+ terminals on D1+ spines was correlated with a slight decline in open field motor parameters at 12 months. Our overall results raise the possibility that differential thalamic and cortical input loss to SPNs is an early event in human HD, with cortical loss to dSPNs in particular contributing to premanifest motor slowing.
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Affiliation(s)
- Yun-Ping Deng
- Department of Anatomy and Neurobiology, The University of Tennessee Health Science Center Memphis, TN, USA
| | - Ting Wong
- Department of Anatomy and Neurobiology, The University of Tennessee Health Science Center Memphis, TN, USA
| | - Jim Y Wan
- Department of Preventive Medicine, The University of Tennessee Health Science Center Memphis, TN, USA
| | - Anton Reiner
- Department of Anatomy and Neurobiology, The University of Tennessee Health Science Center Memphis, TN, USA
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28
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Vessey KA, Greferath U, Aplin FP, Jobling AI, Phipps JA, Ho T, De Iongh RU, Fletcher EL. Adenosine triphosphate-induced photoreceptor death and retinal remodeling in rats. J Comp Neurol 2014; 522:2928-50. [PMID: 24639102 PMCID: PMC4265795 DOI: 10.1002/cne.23558] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2013] [Revised: 02/06/2014] [Accepted: 02/07/2014] [Indexed: 02/06/2023]
Abstract
Many common causes of blindness involve the death of retinal photoreceptors, followed by progressive inner retinal cell remodeling. For an inducible model of retinal degeneration to be useful, it must recapitulate these changes. Intravitreal administration of adenosine triphosphate (ATP) has recently been found to induce acute photoreceptor death. The aim of this study was to characterize the chronic effects of ATP on retinal integrity. Five-week-old, dark agouti rats were administered 50 mM ATP into the vitreous of one eye and saline into the other. Vision was assessed using the electroretinogram and optokinetic response and retinal morphology investigated via histology. ATP caused significant loss of visual function within 1 day and loss of 50% of the photoreceptors within 1 week. At 3 months, 80% of photoreceptor nuclei were lost, and total photoreceptor loss occurred by 6 months. The degeneration and remodeling were similar to those found in heritable retinal dystrophies and age-related macular degeneration and included inner retinal neuronal loss, migration, and formation of new synapses; Müller cell gliosis, migration, and scarring; blood vessel loss; and retinal pigment epithelium migration. In addition, extreme degeneration and remodeling events, such as neuronal and glial migration outside the neural retina and proliferative changes in glial cells, were observed. These extreme changes were also observed in the 2-year-old P23H rhodopsin transgenic rat model of retinitis pigmentosa. This ATP-induced model of retinal degeneration may provide a valuable tool for developing pharmaceutical therapies or for testing electronic implants aimed at restoring vision.
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Affiliation(s)
- Kirstan A Vessey
- Department of Anatomy and Neuroscience, The University of Melbourne,Melbourne, Victoria, 3010, Australia
| | - Ursula Greferath
- Department of Anatomy and Neuroscience, The University of Melbourne,Melbourne, Victoria, 3010, Australia
| | - Felix P Aplin
- Department of Anatomy and Neuroscience, The University of Melbourne,Melbourne, Victoria, 3010, Australia
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital,East Melbourne, Victoria, 3002, Australia
- The Bionics Institute,East Melbourne, Victoria, 3002, Australia
| | - Andrew I Jobling
- Department of Anatomy and Neuroscience, The University of Melbourne,Melbourne, Victoria, 3010, Australia
| | - Joanna A Phipps
- Department of Anatomy and Neuroscience, The University of Melbourne,Melbourne, Victoria, 3010, Australia
| | - Tracy Ho
- Department of Anatomy and Neuroscience, The University of Melbourne,Melbourne, Victoria, 3010, Australia
| | - Robbert U De Iongh
- Department of Anatomy and Neuroscience, The University of Melbourne,Melbourne, Victoria, 3010, Australia
| | - Erica L Fletcher
- Department of Anatomy and Neuroscience, The University of Melbourne,Melbourne, Victoria, 3010, Australia
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Hermes SM, Colbert JF, Aicher SA. Differential content of vesicular glutamate transporters in subsets of vagal afferents projecting to the nucleus tractus solitarii in the rat. J Comp Neurol 2014; 522:642-53. [PMID: 23897509 DOI: 10.1002/cne.23438] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2013] [Revised: 05/15/2013] [Accepted: 07/11/2013] [Indexed: 11/06/2022]
Abstract
The vagus nerve contains primary visceral afferents that convey sensory information from cardiovascular, pulmonary, and gastrointestinal tissues to the nucleus tractus solitarii (NTS). The heterogeneity of vagal afferents and their central terminals within the NTS is a common obstacle for evaluating functional groups of afferents. To determine whether different anterograde tracers can be used to identify distinct subpopulations of vagal afferents within NTS, we injected cholera toxin B subunit (CTb) and isolectin B4 (IB4) into the vagus nerve. Confocal analyses of medial NTS following injections of both CTb and IB4 into the same vagus nerve resulted in labeling of two exclusive populations of fibers. The ultrastructural patterns were also distinct. CTb was found in both myelinated and unmyelinated vagal axons and terminals in medial NTS, whereas IB4 was found only in unmyelinated afferents. Both tracers were observed in terminals with asymmetric synapses, suggesting excitatory transmission. Because glutamate is thought to be the neurotransmitter at this first primary afferent synapse in NTS, we determined whether vesicular glutamate transporters (VGLUTs) were differentially distributed among the two distinct populations of vagal afferents. Anterograde tracing from the vagus with CTb or IB4 was combined with immunohistochemistry for VGLUT1 or VGLUT2 in medial NTS and evaluated with confocal microscopy. CTb-labeled afferents contained primarily VGLUT2 (83%), whereas IB4-labeled afferents had low levels of vesicular transporters, VGLUT1 (5%) or VGLUT2 (21%). These findings suggest the possibility that glutamate release from unmyelinated vagal afferents may be regulated by a distinct, non-VGLUT, mechanism.
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Affiliation(s)
- Sam M Hermes
- Department of Physiology and Pharmacology, Oregon Health and Science University, Portland, Oregon, 97239-3098
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Yokoyama T, Nakamuta N, Kusakabe T, Yamamoto Y. Vesicular glutamate transporter 2-immunoreactive afferent nerve terminals in the carotid body of the rat. Cell Tissue Res 2014; 358:271-5. [DOI: 10.1007/s00441-014-1921-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2014] [Accepted: 05/15/2014] [Indexed: 01/24/2023]
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Singh RK, Kolandaivelu S, Ramamurthy V. Early alteration of retinal neurons in Aipl1-/- animals. Invest Ophthalmol Vis Sci 2014; 55:3081-92. [PMID: 24736053 DOI: 10.1167/iovs.13-13728] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE Mutations in the photoreceptor cell-specific gene encoding aryl hydrocarbon receptor-interacting protein-like 1 (AIPL1) lead to Leber congenital amaurosis (LCA4), retinitis pigmentosa, and cone-rod dystrophy. Gene therapy appears to be promising in the treatment for AIPL1-mediated vision loss in humans. Prior to initiating these treatments, however, it is crucial to understand how the retinal neurons remodel themselves in response to photoreceptor cell degeneration. In this study, using an animal model for AIPL1-LCA, Aipl1(-/-) mice, we investigate the changes in postreceptoral retinal neurons during the course of photoreceptor cell loss. METHODS Morphology of the Aipl1(-/-) retina from postnatal day 8 to 150 was compared to that of age-matched, wild-type C57Bl6/J retina (WT) by immunocytochemistry using cell-specific markers. RESULTS Expression of postsynaptic proteins in bipolar cells is reduced prior to photoreceptor cell degeneration at postnatal day 8. Bipolar and horizontal cells retract their dendrites. Cell bodies and axons of bipolar and horizontal cells are disorganized during the course of degeneration. Müller cell processes become hypertrophic and form a dense fibrotic layer outside the inner nuclear layer. CONCLUSIONS An early defect in photoreceptor cells in the AIPL1-LCA mouse model affects the expression of postsynaptic markers, suggesting abnormal development of bipolar synapses. Once degeneration of photoreceptor cells is initiated, remodeling of retinal neurons in the Aipl1(-/-) animal is rapid.
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Affiliation(s)
- Ratnesh Kumar Singh
- Departments of Ophthalmology and Biochemistry, Center for Neuroscience, West Virginia University, Morgantown, West Virginia, United States
| | - Saravanan Kolandaivelu
- Departments of Ophthalmology and Biochemistry, Center for Neuroscience, West Virginia University, Morgantown, West Virginia, United States
| | - Visvanathan Ramamurthy
- Departments of Ophthalmology and Biochemistry, Center for Neuroscience, West Virginia University, Morgantown, West Virginia, United States
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Alvarado JC, Fuentes-Santamaría V, Gabaldón-Ull MC, Blanco JL, Juiz JM. Wistar rats: a forgotten model of age-related hearing loss. Front Aging Neurosci 2014; 6:29. [PMID: 24634657 PMCID: PMC3942650 DOI: 10.3389/fnagi.2014.00029] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2014] [Accepted: 02/17/2014] [Indexed: 11/13/2022] Open
Abstract
Age-related hearing loss (ARHL) is one of the most frequent sensory impairments in senescence and is a source of important socio-economic consequences. Understanding the pathological responses that occur in the central auditory pathway of patients who suffer from this disability is vital to improve its diagnosis and treatment. Therefore, the goal of this study was to characterize age-related modifications in auditory brainstem responses (ABR) and to determine whether these functional responses might be accompanied by an imbalance between excitation and inhibition in the cochlear nucleus of Wistar rats. To do so, ABR recordings at different frequencies and immunohistochemistry for the vesicular glutamate transporter 1 (VGLUT1) and the vesicular GABA transporter (VGAT) in the ventral cochlear nucleus (VCN) were performed in young, middle-aged and old male Wistar rats. The results demonstrate that there was a significant increase in the auditory thresholds, a significant decrease in the amplitudes and an increase in the latencies of the ABR waves as the age of the rat increased. Additionally, there were decreases in VGLUT1 and VGAT immunostaining in the VCN of older rats compared to younger rats. Therefore, the observed age-related decline in the magnitude of auditory evoked responses might be due in part to a reduction in markers of excitatory function; meanwhile, the concomitant reduction in both excitatory and inhibitory markers might reflect a common central alteration in animal models of ARLH. Together, these findings highlight the suitability of the Wistar rat as an excellent model to study ARHL.
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Affiliation(s)
- Juan C Alvarado
- Facultad de Medicina, Instituto de Investigación en Discapacidades Neurológicas, Universidad de Castilla-La Mancha Albacete, Spain
| | - Verónica Fuentes-Santamaría
- Facultad de Medicina, Instituto de Investigación en Discapacidades Neurológicas, Universidad de Castilla-La Mancha Albacete, Spain
| | - María C Gabaldón-Ull
- Facultad de Medicina, Instituto de Investigación en Discapacidades Neurológicas, Universidad de Castilla-La Mancha Albacete, Spain
| | - José L Blanco
- Facultad de Medicina, Instituto de Investigación en Discapacidades Neurológicas, Universidad de Castilla-La Mancha Albacete, Spain
| | - José M Juiz
- Facultad de Medicina, Instituto de Investigación en Discapacidades Neurológicas, Universidad de Castilla-La Mancha Albacete, Spain
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Neck muscle afferents influence oromotor and cardiorespiratory brainstem neural circuits. Brain Struct Funct 2014; 220:1421-36. [PMID: 24595534 PMCID: PMC4409642 DOI: 10.1007/s00429-014-0734-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2013] [Accepted: 02/11/2014] [Indexed: 12/17/2022]
Abstract
Sensory information arising from the upper neck is important in the reflex control of posture and eye position. It has also been linked to the autonomic control of the cardiovascular and respiratory systems. Whiplash associated disorders (WAD) and cervical dystonia, which involve disturbance to the neck region, can often present with abnormalities to the oromotor, respiratory and cardiovascular systems. We investigated the potential neural pathways underlying such symptoms. Simulating neck afferent activity by electrical stimulation of the second cervical nerve in a working heart brainstem preparation (WHBP) altered the pattern of central respiratory drive and increased perfusion pressure. Tracing central targets of these sensory afferents revealed projections to the intermedius nucleus of the medulla (InM). These anterogradely labelled afferents co-localised with parvalbumin and vesicular glutamate transporter 1 indicating that they are proprioceptive. Anterograde tracing from the InM identified projections to brain regions involved in respiratory, cardiovascular, postural and oro-facial behaviours—the neighbouring hypoglossal nucleus, facial and motor trigeminal nuclei, parabrachial nuclei, rostral and caudal ventrolateral medulla and nucleus ambiguus. In brain slices, electrical stimulation of afferent fibre tracts lateral to the cuneate nucleus monosynaptically excited InM neurones. Direct stimulation of the InM in the WHBP mimicked the response of second cervical nerve stimulation. These results provide evidence of pathways linking upper cervical sensory afferents with CNS areas involved in autonomic and oromotor control, via the InM. Disruption of these neuronal pathways could, therefore, explain the dysphagic and cardiorespiratory abnormalities which may accompany cervical dystonia and WAD.
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Corson JA, Erisir A. Monosynaptic convergence of chorda tympani and glossopharyngeal afferents onto ascending relay neurons in the nucleus of the solitary tract: a high-resolution confocal and correlative electron microscopy approach. J Comp Neurol 2014; 521:2907-26. [PMID: 23640852 DOI: 10.1002/cne.23357] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2012] [Revised: 04/16/2013] [Accepted: 04/25/2013] [Indexed: 01/22/2023]
Abstract
Physiological studies suggest convergence of chorda tympani and glossopharyngeal afferent axons onto single neurons of the rostral nucleus of the solitary tract (rNTS), but anatomical evidence has been elusive. The current study uses high-magnification confocal microscopy to identify putative synaptic contacts from afferent fibers of the two nerves onto individual projection neurons. Imaged tissue is revisualized with electron microscopy, confirming that overlapping fluorescent signals in confocal z-stacks accurately identify appositions between labeled terminal and dendrite pairs. Monte Carlo modeling reveals that the probability of overlapping fluorophores is stochastically unrelated to the density of afferent label, suggesting that convergent innervation in the rNTS is selective rather than opportunistic. Putative synaptic contacts from each nerve are often compartmentalized onto dendrite segments of convergently innervated neurons. These results have important implications for orosensory processing in the rNTS, and the techniques presented here have applications in investigations of neural microcircuitry with an emphasis on innervation patterning.
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Affiliation(s)
- James A Corson
- Department of Psychology, University of Virginia, Charlottesville, Virginia, 22904, USA
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35
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Lei W, Deng Y, Liu B, Mu S, Guley NM, Wong T, Reiner A. Confocal laser scanning microscopy and ultrastructural study of VGLUT2 thalamic input to striatal projection neurons in rats. J Comp Neurol 2013; 521:1354-77. [PMID: 23047588 DOI: 10.1002/cne.23235] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2012] [Revised: 08/31/2012] [Accepted: 10/02/2012] [Indexed: 01/17/2023]
Abstract
We examined thalamic input to striatum in rats using immunolabeling for the vesicular glutamate transporter (VGLUT2). Double immunofluorescence viewed with confocal laser scanning microscopy (CLSM) revealed that VGLUT2+ terminals are distinct from VGLUT1+ terminals. CLSM of Phaseolus vulgaris-leucoagglutinin (PHAL)-labeled cortical or thalamic terminals revealed that VGLUT2 is rare in corticostriatal terminals but nearly always present in thalamostriatal terminals. Electron microscopy revealed that VGLUT2+ terminals made up 39.4% of excitatory terminals in striatum (with VGLUT1+ corticostriatal terminals constituting the rest), and 66.8% of VGLUT2+ terminals synapsed on spines and the remainder on dendrites. VGLUT2+ axospinous terminals had a mean diameter of 0.624 μm, while VGLUT2+ axodendritic terminals a mean diameter of 0.698 μm. In tissue in which we simultaneously immunolabeled thalamostriatal terminals for VGLUT2 and striatal neurons for D1 (with about half of spines immunolabeled for D1), 54.6% of VGLUT2+ terminals targeted D1+ spines (i.e., direct pathway striatal neurons), and 37.3% of D1+ spines received VGLUT2+ synaptic contacts. By contrast, 45.4% of VGLUT2+ terminals targeted D1-negative spines (i.e., indirect pathway striatal neurons), and only 25.8% of D1-negative spines received VGLUT2+ synaptic contacts. Similarly, among VGLUT2+ axodendritic synaptic terminals, 59.1% contacted D1+ dendrites, and 40.9% contacted D1-negative dendrites. VGLUT2+ terminals on D1+ spines and dendrites tended to be slightly smaller than those on D1-negative spines and dendrites. Thus, thalamostriatal terminals contact both direct and indirect pathway striatal neurons, with a slight preference for direct. These results are consistent with physiological studies indicating slightly different effects of thalamic input on the two types of striatal projection neurons.
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Affiliation(s)
- Wanlong Lei
- Department of Anatomy, Zhongshan Medical School of Sun Yat-Sen University, Guangzhou, 510080, PR China.
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Loss of corticostriatal and thalamostriatal synaptic terminals precedes striatal projection neuron pathology in heterozygous Q140 Huntington's disease mice. Neurobiol Dis 2013; 60:89-107. [PMID: 23969239 DOI: 10.1016/j.nbd.2013.08.009] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2013] [Revised: 07/22/2013] [Accepted: 08/07/2013] [Indexed: 01/18/2023] Open
Abstract
Motor slowing, forebrain white matter loss, and striatal shrinkage have been reported in premanifest Huntington's disease (HD) prior to overt striatal neuron loss. We carried out detailed LM and EM studies in a genetically precise HD mimic, heterozygous Q140 HD knock-in mice, to examine the possibility that loss of corticostriatal and thalamostriatal terminals prior to striatal neuron loss underlies these premanifest HD abnormalities. In our studies, we used VGLUT1 and VGLUT2 immunolabeling to detect corticostriatal and thalamostriatal (respectively) terminals in dorsolateral (motor) striatum over the first year of life, prior to striatal projection neuron pathology. VGLUT1+ axospinous corticostriatal terminals represented about 55% of all excitatory terminals in striatum, and VGLUT2+ axospinous thalamostriatal terminals represented about 35%, with VGLUT1+ and VGLUT2+ axodendritic terminals accounting for the remainder. In Q140 mice, a significant 40% shortfall in VGLUT2+ axodendritic thalamostriatal terminals and a 20% shortfall in axospinous thalamostriatal terminals were already observed at 1 month of age, but VGLUT1+ terminals were normal in abundance. The 20% deficiency in VGLUT2+ thalamostriatal axospinous terminals persisted at 4 and 12 months in Q140 mice, and an additional 30% loss of VGLUT1+ corticostriatal terminals was observed at 12 months. The early and persistent deficiency in thalamostriatal axospinous terminals in Q140 mice may reflect a development defect, and the impoverishment of this excitatory drive to striatum may help explain early motor defects in Q140 mice and in premanifest HD. The loss of corticostriatal terminals at 1 year in Q140 mice is consistent with prior evidence from other mouse models of corticostriatal disconnection early during progression, and can explain both the measurable bradykinesia and striatal white matter loss in late premanifest HD.
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Cox DJ, Racca C. Differential dendritic targeting of AMPA receptor subunit mRNAs in adult rat hippocampal principal neurons and interneurons. J Comp Neurol 2013; 521:1954-2007. [DOI: 10.1002/cne.23292] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2011] [Revised: 12/13/2012] [Accepted: 12/14/2012] [Indexed: 12/19/2022]
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38
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Aizawa H, Kobayashi M, Tanaka S, Fukai T, Okamoto H. Molecular characterization of the subnuclei in rat habenula. J Comp Neurol 2013; 520:4051-66. [PMID: 22700183 DOI: 10.1002/cne.23167] [Citation(s) in RCA: 203] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The mammalian habenula is involved in regulating the activities of serotonergic and dopaminergic neurons. It consists of the medial and lateral habenulae, with each subregion having distinct neural connectivity. Despite the functional significance, manipulating neural activity in a subset of habenular pathways remains difficult because of the poor availability of molecular markers that delineate the subnuclear structures. Thus, we examined the molecular nature of neurons in the habenular subnuclei by analyzing the gene expressions of neurotransmitter markers. The results showed that different subregions of the medial habenula (MHb) use different combinations of neurotransmitter systems and could be categorized as either exclusively glutamatergic (superior part of MHb), both substance P-ergic and glutamatergic (dorsal region of central part of MHb), or both cholinergic and glutamatergic (inferior part, ventral region of central part, and lateral part of MHb). The superior part of the MHb strongly expressed interleukin-18 and was innervated by noradrenergic fibers. In contrast, the inferior part, ventral region of the central part, and lateral part of the MHb were peculiar in that acetylcholine and glutamate were cotransmitted from the axonal terminals. In contrast, neurons in the lateral habenula (LHb) were almost uniformly glutamatergic. Finally, the expressions of Htr2c and Drd2 seemed complementary in the medial LHb division, whereas they coincided in the lateral division, suggesting that the medial and lateral divisions of LHb show strong heterogeneity with respect to monoamine receptor expression. These analyses clarify molecular differences between subnuclei in the mammalian habenula that support their respective functional implications.
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Affiliation(s)
- Hidenori Aizawa
- Laboratory for Developmental Gene Regulation, RIKEN Brain Science Institute, Wako, Saitama, Japan
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Percival KA, Martin PR, Grünert U. Organisation of koniocellular-projecting ganglion cells and diffuse bipolar cells in the primate fovea. Eur J Neurosci 2013; 37:1072-89. [DOI: 10.1111/ejn.12117] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2012] [Revised: 11/26/2012] [Accepted: 11/28/2012] [Indexed: 11/28/2022]
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Burette AC, Weinberg RJ, Sassani P, Abuladze N, Kao L, Kurtz I. The sodium-driven chloride/bicarbonate exchanger in presynaptic terminals. J Comp Neurol 2012; 520:1481-92. [PMID: 22102085 DOI: 10.1002/cne.22806] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
The sodium-driven chloride/bicarbonate exchanger (NDCBE), a member of the SLC4 family of bicarbonate transporters, was recently found to modulate excitatory neurotransmission in hippocampus. By using light and electron microscopic immunohistochemistry, we demonstrate here that NDCBE is expressed throughout the adult rat brain, and selectively concentrates in presynaptic terminals, where it is closely associated with synaptic vesicles. NDCBE is in most glutamatergic axon terminals, and is also present in the terminals of parvalbumin-positive γ-aminobutyric acid (GABA)ergic cells. These findings suggest that NDCBE can regulate glutamatergic transmission throughout the brain, and point to a role for NDCBE as a possible regulator of GABAergic neurotransmission.
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Affiliation(s)
- Alain C Burette
- Department of Cell and Developmental Biology, University of North Carolina, Chapel Hill, North Carolina 27599, USA.
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Cserép C, Szabadits E, Szőnyi A, Watanabe M, Freund TF, Nyiri G. NMDA receptors in GABAergic synapses during postnatal development. PLoS One 2012; 7:e37753. [PMID: 22662211 PMCID: PMC3360635 DOI: 10.1371/journal.pone.0037753] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2012] [Accepted: 04/25/2012] [Indexed: 01/30/2023] Open
Abstract
GABA (gamma-aminobutyric-acid), the main inhibitory neurotransmitter in the adult brain, exerts depolarizing (excitatory) actions during development and this GABAergic depolarization cooperates with NMDARs (N-methyl-D-aspartate receptors) to drive spontaneous synchronous activity (SSA) that is fundamentally important for developing neuronal networks. Although GABAergic depolarization is known to assist in the activation of NMDARs during development, the subcellular localization of NMDARs relative to GABAergic synapses is still unknown. Here, we investigated the subcellular distribution of NMDARs in association with GABAergic synapses at the developmental stage when SSA is most prominent in mice. Using multiple immunofluorescent labeling and confocal laser-scanning microscopy in the developing mouse hippocampus, we found that NMDARs were associated with both glutamatergic and GABAergic synapses at postnatal day 6–7 and we observed a direct colocalization of GABAA- and NMDA-receptor labeling in GABAergic synapses. Electron microscopy of pre-embedding immunogold-immunoperoxidase reactions confirmed that GluN1, GluN2A and GluN2B NMDAR subunits were all expressed in glutamatergic and GABAergic synapses postsynaptically. Finally, quantitative post-embedding immunogold labeling revealed that the density of NMDARs was 3 times higher in glutamatergic than in GABAergic synapses. Since GABAergic synapses were larger, there was little difference in the total number of NMDA receptors in the two types of synapses. In addition, receptor density in synapses was substantially higher than extrasynaptically. These data can provide the neuroanatomical basis of a new interpretation of previous physiological data regarding the GABAAR-NMDAR cooperation during early development. We suggest that during SSA, synaptic GABAAR-mediated depolarization assists NMDAR activation right inside GABAergic synapses and this effective spatial cooperation of receptors and local change of membrane potential will reach developing glutamatergic synapses with a higher probability and efficiency even further away on the dendrites. This additional level of cooperation that operates within the depolarizing GABAergic synapse, may also allow its own modification triggered by Ca2+-influx through the NMDA receptors.
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Affiliation(s)
- Csaba Cserép
- Laboratory of Cerebral Cortex Research, Department of Cellular and Network Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary
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Soda Y, Yamamoto Y. Morphology and chemical characteristics of subepithelial laminar nerve endings in the rat epiglottic mucosa. Histochem Cell Biol 2012; 138:25-39. [DOI: 10.1007/s00418-012-0939-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/11/2012] [Indexed: 01/13/2023]
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Bragina L, Fattorini G, Giovedí S, Melone M, Bosco F, Benfenati F, Conti F. Analysis of Synaptotagmin, SV2, and Rab3 Expression in Cortical Glutamatergic and GABAergic Axon Terminals. Front Cell Neurosci 2012; 5:32. [PMID: 22275882 PMCID: PMC3254050 DOI: 10.3389/fncel.2011.00032] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2011] [Accepted: 12/25/2011] [Indexed: 11/13/2022] Open
Abstract
We investigated whether cortical glutamatergic and GABAergic release machineries can be differentiated on the basis of the nature and amount of proteins they express, by performing a quantitative analysis of the degree of co-localization of synaptotagmin (SYT) 1 and 2, synaptic vesicle protein 2 (SV2) A and B, and Rab3a and c in VGLUT1+, VGLUT2+, and VGAT+ terminals and synaptic vesicles (SVs) in rat cerebral cortex. Co-localization studies showed that VGLUT1 puncta had high levels of SV2A and B and of Rab3c, intermediate levels of SYT1, and low levels of SYT2 and Rab3c; VGLUT2 puncta exhibited intermediate levels of all presynaptic proteins studied; whereas vesicular GABA transporter (VGAT) puncta had high levels of SV2A and SYT2, intermediate levels of SYT1, Rab3a, and Rab3c, and low levels of SV2B. Since SV2B is reportedly expressed by glutamatergic neurons and we observed SV2B expression in VGAT puncta, we performed electron microscopic studies and found SV2B positive axon terminals forming symmetric synapses. Immunoisolation studies showed that the expression levels of the protein isoforms varied in the three populations of SVs. Expression of SYT1 was highest in VGLUT1–SVs, while SYT2 expression was similar in the three SV groups. Expression of SV2A was similarly high in all three SV populations, except for SV2B levels that were very low in VGAT SVs. Finally, Rab3a levels were similar in the three SV groups, while Rab3c levels were highest in VGLUT1–SVs. These quantitative results extend our previous studies on the differential expression of presynaptic proteins involved in neurotransmitter release in GABAergic and glutamatergic terminals and indicate that heterogeneity of the respective release machineries can be generated by the differential complement of SV proteins involved in distinct stages of the release process.
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Affiliation(s)
- Luca Bragina
- Section of Neuroscience and Cell Biology, Department of Experimental and Clinical Medicine, Università Politecnica delle Marche Ancona, Italy
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Sun C, Wang Y, Chen XY. WITHDRAWN: H-reflex up-conditioning after sciatic nerve transection and regeneration may increase VGLUT-1 terminals and GluR2/3 immunoreactivity in spinal motoneurons. Neurosci Lett 2011:S0304-3940(11)01597-7. [PMID: 22198372 DOI: 10.1016/j.neulet.2011.12.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2011] [Revised: 12/08/2011] [Accepted: 12/08/2011] [Indexed: 11/23/2022]
Abstract
This article has been withdrawn at the request of the author(s) and/or editor. The Publisher apologizes for any inconvenience this may cause. The full Elsevier Policy on Article Withdrawal can be found at http://www.elsevier.com/locate/withdrawalpolicy.
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Affiliation(s)
- Chenyou Sun
- Wadsworth Center, Laboratory of Neural Injury and Repair, New York State Department Health and State University of New York at Albany, Albany, NY 12201-0509, United States; Department of Anatomy, Wenzhou Medical College, Zhejiang Province 325035, China
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Soiza-Reilly M, Commons KG. Quantitative analysis of glutamatergic innervation of the mouse dorsal raphe nucleus using array tomography. J Comp Neurol 2011; 519:3802-14. [PMID: 21800318 PMCID: PMC3268343 DOI: 10.1002/cne.22734] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Serotonin (5-hydroxytryptamine, 5-HT) containing neurons located in the dorsal raphe nucleus (DR) comprise the main source of forebrain 5-HT and regulate emotional states in normal and pathological conditions including affective disorders. However, there are many features of the local circuit architecture within the DR that remain poorly understood. DR neurons receive glutamatergic innervation from different brain areas that selectively express three different types of the vesicular glutamate transporter (VGLUT). In this study we used a new high-resolution imaging technique, array tomography, to quantitatively analyze the glutamatergic innervation of the mouse DR. In the same volumetric images, we studied the distribution of five antigens: VGLUT1, VGLUT2, VGLUT3, the postsynaptic protein PSD-95, and a marker for 5-HT cells, the enzyme tryptophan hydroxylase (TPOH). We found that all three populations of glutamatergic boutons are present in the DR; however, the density of paired association between VGLUT2 boutons and PSD-95 was ≈2-fold higher than that of either VGLUT1- or VGLUT3-PSD-95 pairs. In addition, VGLUT2-PSD-95 pairs were more commonly found associated with 5-HT cells than the other VGLUT types. These data support a prominent contribution of glutamate axons expressing VGLUT2 to the excitatory drive of DR neurons. The current study also emphasizes the use of array tomography as a quantitative approach to understand the fine molecular architecture of microcircuits in a well-preserved neuroanatomical context.
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Affiliation(s)
- Mariano Soiza-Reilly
- Department of Anesthesiology, Perioperative, and Pain Medicine, Children's Hospital Boston, Boston, Massachusetts 02115, USA.
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Cooper AP, Gillespie DC. Synaptotagmins I and II in the developing rat auditory brainstem: Synaptotagmin I is transiently expressed in glutamate-releasing immature inhibitory terminals. J Comp Neurol 2011; 519:2417-33. [DOI: 10.1002/cne.22634] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Schubert V, Bouvier D, Volterra A. SNARE protein expression in synaptic terminals and astrocytes in the adult hippocampus: a comparative analysis. Glia 2011; 59:1472-88. [PMID: 21656854 DOI: 10.1002/glia.21190] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2010] [Accepted: 04/27/2011] [Indexed: 01/02/2023]
Abstract
Several evidences suggest that astrocytes release small transmitter molecules, peptides, and protein factors via regulated exocytosis, implying that they function as specialized neurosecretory cells. However, very little is known about the molecular and functional properties of regulated secretion in astrocytes in the adult brain. Establishing these properties is central to the understanding of the communication mode(s) of these cells and their role(s) in the control of synaptic functions and of cerebral blood flow. In this study, we have set-up a high-resolution confocal microscopy approach to distinguish protein expression in astrocytic structures and neighboring synaptic terminals in adult brain tissue. This approach was applied to investigate the expression pattern of core SNARE proteins for vesicle fusion in the dentate gyrus and CA1 regions of the mouse hippocampus. Our comparative analysis shows that astrocytes abundantly express, in their cell body and main processes, all three protein partners necessary to form an operational SNARE complex but not in the same isoforms expressed in neighbouring synaptic terminals. Thus, SNAP25 and VAMP2 are absent from astrocytic processes and typically concentrated in terminals, while SNAP23 and VAMP3 have the opposite expression pattern. Syntaxin 1 is present in both synaptic terminals and astrocytes. These data support the view that astrocytes in the adult hippocampus can communicate via regulated exocytosis and also indicates that astrocytic exocytosis may differ in its properties from action potential-dependent exocytosis at neuronal synapses, as it relies on a distinctive set of SNARE proteins.
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Affiliation(s)
- Vanessa Schubert
- Department of Cell Biology and Morphology, University of Lausanne, Lausanne, Switzerland
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Soria Van Hoeve JS, Borst JGG. Delayed appearance of the scaffolding proteins PSD-95 and Homer-1 at the developing rat calyx of Held synapse. J Comp Neurol 2011; 518:4581-90. [PMID: 20886623 DOI: 10.1002/cne.22479] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The calyx of Held synapse is a giant axosomatic synapse that acts as a fast relay in the sound localization circuit of the brainstem. In rodents it forms within a relatively brief period starting around the second postnatal day (P2). The relative timing of the formation of its pre- and the postsynaptic compartment are not yet known. By means of fluorescent immunohistochemistry in neonatal rats we therefore compared the developmental expression patterns of the vesicular glutamate transporter (VGLUT)-1 and the postsynaptic density scaffolding proteins Homer-1 and PSD-95 in the medial nucleus of the trapezoid body (MNTB). Before its formation, colocalized punctate staining of VGLUT-1 and Homer-1 or PSD-95 was observed on principal neurons, in agreement with earlier work showing that they are already innervated by fibers from the cochlear nucleus before the calyx forms. The expression of VGLUT-1 clusters within the nascent calyx of Held synapse preceded the expression of Homer-1 and PSD-95 clusters, as indicated by the presence of principal neurons with only a large contiguous cluster (LCC) of VGLUT-1 at P2-3, whereas no neurons with only an LCC for Homer-1 or PSD-95 were seen. At P3 the first principal neurons with both a pre- and a postsynaptic LCC were observed, and at P12 all principal neurons had both a pre- and a postsynaptic LCC. The relatively late appearance of Homer-1 and PSD-95 within the developing calyx of Held synapse suggests that they play a role in its stabilization and the recruitment of additional receptors to its postsynaptic density.
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Affiliation(s)
- John S Soria Van Hoeve
- Department of Neuroscience, Erasmus MC, University Medical Center Rotterdam, 3015 GE Rotterdam, The Netherlands
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Melone M, Bellesi M, Ducati A, Iacoangeli M, Conti F. Cellular and Synaptic Localization of EAAT2a in Human Cerebral Cortex. Front Neuroanat 2011; 4:151. [PMID: 21258616 PMCID: PMC3024003 DOI: 10.3389/fnana.2010.00151] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2010] [Accepted: 12/24/2010] [Indexed: 11/23/2022] Open
Abstract
We used light and electron microscopic immunocytochemical techniques to analyze the distribution, cellular and synaptic localization of EAAT2, the main glutamate transporter, in normal human neocortex. EAAT2a-immunoreactivity (ir) was in all layers and consisted of small neuropilar puncta and rare cells. In white matter EAAT2a+ cells were numerous. Electron microscopic studies showed that in gray matter ∼77% of immunoreactive elements were astrocytic processes, ∼14% axon terminals, ∼2.8% dendrites, whereas ∼5% were unidentifiable. In white matter, ∼81% were astrocytic processes, ∼17% were myelinated axons, and ∼2.0% were unidentified. EAAT2a-ir was never in microglial cells and oligodendrocytes. Pre-embedding electron microscopy showed that ∼67% of EAAT2a expressed at (or in the vicinity of) asymmetric synapses was in astrocytes, ∼17% in axon terminals, while ∼13% was both in astrocytes and in axons. Post-embedding electron microscopy studies showed that in astrocytic processes contacting asymmetric synapses and in axon terminals, gold particle density was ∼25.1 and ∼2.8 particles/μm2, respectively, and was concentrated in a membrane region extending for ∼300 nm from the active zone edge. Besides representing the first detailed description of EAAT2a in human cerebral cortex, these findings may contribute to understanding its role in the pathophysiology of neuropsychiatric diseases.
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Affiliation(s)
- Marcello Melone
- Department of Neuroscience, Section of Physiology, Università Politecnica delle Marche Ancona, Italy
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Hegarty DM, Tonsfeldt K, Hermes SM, Helfand H, Aicher SA. Differential localization of vesicular glutamate transporters and peptides in corneal afferents to trigeminal nucleus caudalis. J Comp Neurol 2010; 518:3557-69. [PMID: 20593358 DOI: 10.1002/cne.22414] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Trigeminal afferents convey nociceptive information from the corneal surface of the eye to the trigeminal subnucleus caudalis (Vc). Trigeminal afferents, like other nociceptors, are thought to use glutamate and neuropeptides as neurotransmitters. The current studies examined whether corneal afferents contain both neuropeptides and vesicular glutamate transporters. Corneal afferents to the Vc were identified by using cholera toxin B (CTb). Corneal afferents project in two clusters to the rostral and caudal borders of the Vc, regions that contain functionally distinct nociceptive neurons. Thus, corneal afferents projecting to these two regions were examined separately. Dual immunocytochemical studies combined CTb with either calcitonin gene-related peptide (CGRP), substance P (SP), vesicular glutamate transporter 1 (VGluT1), or VGluT2. Corneal afferents were more likely to contain CGRP than SP, and corneal afferents projecting to the rostral region were more likely to contain CGRP than afferents projecting caudally. Overall, corneal afferents were equally likely to contain VGluT1 or VGluT2. Together, 61% of corneal afferents contained either VGluT1 or VGluT2, suggesting that some afferents lack a VGluT. Caudal corneal afferents were more likely to contain VGluT2 than VGluT1, whereas rostral corneal afferents were more likely to contain VGluT1 than VGluT2. Triple-labeling studies combining CTb, CGRP, and VGluT2 showed that very few corneal afferents contain both CGRP and VGluT2, caudally (1%) and rostrally (2%). These results suggest that most corneal afferents contain a peptide or a VGluT, but rarely both. Our results are consistent with a growing literature suggesting that glutamatergic and peptidergic sensory afferents may be distinct populations.
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Affiliation(s)
- Deborah M Hegarty
- Department of Physiology and Pharmacology, Oregon Health & Science University, Beaverton, Oregon 97006, USA
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