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Barbay T, Pecchi E, Ducrocq M, Rouach N, Brocard F, Bos R. Astrocytic Kir4.1 channels regulate locomotion by orchestrating neuronal rhythmicity in the spinal network. Glia 2023; 71:1259-1277. [PMID: 36645018 DOI: 10.1002/glia.24337] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2022] [Revised: 12/22/2022] [Accepted: 01/02/2023] [Indexed: 01/17/2023]
Abstract
Neuronal rhythmogenesis in the spinal cord is correlated with variations in extracellular K+ levels ([K+ ]e ). Astrocytes play important role in [K+ ]e homeostasis and compute neuronal information. Yet it is unclear how neuronal oscillations are regulated by astrocytic K+ homeostasis. Here we identify the astrocytic inward-rectifying K+ channel Kir4.1 (a.k.a. Kcnj10) as a key molecular player for neuronal rhythmicity in the spinal central pattern generator (CPG). By combining two-photon calcium imaging with electrophysiology, immunohistochemistry and genetic tools, we report that astrocytes display Ca2+ transients before and during oscillations of neighboring neurons. Inhibition of astrocytic Ca2+ transients with BAPTA decreases the barium-sensitive Kir4.1 current responsible of K+ clearance. Finally, we show in mice that Kir4.1 knockdown in astrocytes progressively prevents neuronal oscillations and alters the locomotor pattern resulting in lower motor performances in challenging tasks. These data identify astroglial Kir4.1 channels as key regulators of neuronal rhythmogenesis in the CPG driving locomotion.
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Affiliation(s)
- Tony Barbay
- Aix Marseille Univ, CNRS, Institut de Neurosciences de la Timone (INT), UMR 7289, Marseille, France
| | - Emilie Pecchi
- Aix Marseille Univ, CNRS, Institut de Neurosciences de la Timone (INT), UMR 7289, Marseille, France
| | - Myriam Ducrocq
- Aix Marseille Univ, CNRS, Institut de Neurosciences de la Timone (INT), UMR 7289, Marseille, France
| | - Nathalie Rouach
- Center for Interdisciplinary Research in Biology, Collège de France, CNRS, INSERM, Labex Memolife, Université PSL, Paris, France
| | - Frédéric Brocard
- Aix Marseille Univ, CNRS, Institut de Neurosciences de la Timone (INT), UMR 7289, Marseille, France
| | - Rémi Bos
- Aix Marseille Univ, CNRS, Institut de Neurosciences de la Timone (INT), UMR 7289, Marseille, France
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Bykowski EA, Petersson JN, Dukelow S, Ho C, Debert CT, Montina T, Metz GAS. Identification of Serum Metabolites as Prognostic Biomarkers Following Spinal Cord Injury: A Pilot Study. Metabolites 2023; 13:metabo13050605. [PMID: 37233646 DOI: 10.3390/metabo13050605] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Revised: 04/06/2023] [Accepted: 04/24/2023] [Indexed: 05/27/2023] Open
Abstract
The assessment, management, and prognostication of spinal cord injury (SCI) mainly rely upon observer-based ordinal scales measures. 1H nuclear magnetic resonance (NMR) spectroscopy provides an effective approach for the discovery of objective biomarkers from biofluids. These biomarkers have the potential to aid in understanding recovery following SCI. This proof-of-principle study determined: (a) If temporal changes in blood metabolites reflect the extent of recovery following SCI; (b) whether changes in blood-derived metabolites serve as prognostic indicators of patient outcomes based on the spinal cord independence measure (SCIM); and (c) whether metabolic pathways involved in recovery processes may provide insights into mechanisms that mediate neural damage and repair. Morning blood samples were collected from male complete and incomplete SCI patients (n = 7) following injury and at 6 months post-injury. Multivariate analyses were used to identify changes in serum metabolic profiles and were correlated to clinical outcomes. Specifically, acetyl phosphate, 1,3,7-trimethyluric acid, 1,9-dimethyluric acid, and acetic acid significantly related to SCIM scores. These preliminary findings suggest that specific metabolites may serve as proxy measures of the SCI phenotype and prognostic markers of recovery. Thus, serum metabolite analysis combined with machine learning holds promise in understanding the physiology of SCI and aiding in prognosticating outcomes following injury.
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Affiliation(s)
- Elani A Bykowski
- Canadian Centre for Behavioural Neuroscience, Department of Neuroscience, University of Lethbridge, Lethbridge, AB T1K 3M4, Canada
- Southern Alberta Genome Sciences Centre, University of Lethbridge, Lethbridge, AB T1K 3M4, Canada
| | - Jamie N Petersson
- Canadian Centre for Behavioural Neuroscience, Department of Neuroscience, University of Lethbridge, Lethbridge, AB T1K 3M4, Canada
- Southern Alberta Genome Sciences Centre, University of Lethbridge, Lethbridge, AB T1K 3M4, Canada
- Department of Chemistry and Biochemistry, University of Lethbridge, Lethbridge, AB T1K 3M4, Canada
| | - Sean Dukelow
- Department of Clinical Neurosciences, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 1N4, Canada
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB T2N 1N4, Canada
| | - Chester Ho
- Division of Physical Medicine and Rehabilitation, University of Alberta, Edmonton, AB T6G 2R7, Canada
| | - Chantel T Debert
- Department of Clinical Neurosciences, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 1N4, Canada
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB T2N 1N4, Canada
| | - Tony Montina
- Southern Alberta Genome Sciences Centre, University of Lethbridge, Lethbridge, AB T1K 3M4, Canada
- Department of Chemistry and Biochemistry, University of Lethbridge, Lethbridge, AB T1K 3M4, Canada
| | - Gerlinde A S Metz
- Canadian Centre for Behavioural Neuroscience, Department of Neuroscience, University of Lethbridge, Lethbridge, AB T1K 3M4, Canada
- Southern Alberta Genome Sciences Centre, University of Lethbridge, Lethbridge, AB T1K 3M4, Canada
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Broadhead MJ, Bonthron C, Waddington J, Smith WV, Lopez MF, Burley S, Valli J, Zhu F, Komiyama NH, Smith C, Grant SGN, Miles GB. Selective vulnerability of tripartite synapses in amyotrophic lateral sclerosis. Acta Neuropathol 2022; 143:471-486. [PMID: 35305541 PMCID: PMC8960590 DOI: 10.1007/s00401-022-02412-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Revised: 02/23/2022] [Accepted: 03/09/2022] [Indexed: 12/12/2022]
Abstract
Amyotrophic Lateral Sclerosis (ALS) is a fatal neurodegenerative disorder. Separate lines of evidence suggest that synapses and astrocytes play a role in the pathological mechanisms underlying ALS. Given that astrocytes make specialised contacts with some synapses, called tripartite synapses, we hypothesise that tripartite synapses could act as the fulcrum of disease in ALS. To test this hypothesis, we have performed an extensive microscopy-based investigation of synapses and tripartite synapses in the spinal cord of ALS model mice and post-mortem human tissue from ALS cases. We reveal widescale synaptic changes at the early symptomatic stages of the SOD1G93a mouse model. Super-resolution microscopy reveals that large complex postsynaptic structures are lost in ALS mice. Most surprisingly, tripartite synapses are selectively lost, while non-tripartite synapses remain in equal number to healthy controls. Finally, we also observe a similar selective loss of tripartite synapses in human post-mortem ALS spinal cords. From these data we conclude that tripartite synaptopathy is a key hallmark of ALS.
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Yazawa I, Okazaki S, Yokota S, Takeda K, Fukushi I, Yoshizawa M, Onimaru H, Okada Y. Coherence analysis of the calcium activity of putative astrocytic and neuronal cells on the L5 ventral horn and neural output in activated lumbar CPG networks. Neurosci Lett 2021; 771:136421. [PMID: 34968723 DOI: 10.1016/j.neulet.2021.136421] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Revised: 12/03/2021] [Accepted: 12/22/2021] [Indexed: 11/18/2022]
Abstract
Astrocytes are thought to play a crucial role in providing structure to the spinal cord and maintaining efficient synaptic function and metabolism because their fine processes envelop the synapses of neurons and form many neuronal networks within the central nervous system (CNS). To investigate whether putative astrocytes and putative neurons distributed on the ventral horn play a role in the modulation of lumbar locomotor central pattern generator (CPG) networks, we used extracellular recording and optical imaging techniques and recorded the neural output from the left L5 ventral root and the calcium activity of putative astrocytes and neurons in the L5 ventral horn at the same time when activating an isolated L1-L5 spinal cord preparation from rats aged 0-2 days. Optical measurements detected cells that showed a fluorescence intensity change under all experimental conditions, namely, (1) 5-HT + NMDA, (2) TTX, and (3) TTX + Low K+. These cells were semiautomatically identified using an in-house MATLAB-based program, as putative astrocytes and neurons according to the cell classification, i.e., increased or decreased fluorescence intensity change (ΔF/F0), and subjective judgment based on their soma size. Coherence and its phase were calculated according to the calcium activity of the putative astrocytes and putative neurons, and neural output was calculated during fictive locomotion with in-house MATLAB-based programs. We found that the number of putative astrocytes activated by applying low K+ tends not to differ from that activated by applying the protease-activated receptor 1 (PAR1) selective agonist TFLLR-NH2 (TFLLR). Moreover, the calcium activity of several putative astrocytes and neurons synchronized with locomotor-like activity at a frequency range below 0.5 Hz and the time lag between peaks of cellular calcium activity and locomotor-like activity ranged from -1000 to + 1000 ms. These findings presumably indicates that these putative astrocytes and neurons in the left L5 ventral horn require -1000 to + 1000 ms to communicate with lumbar CPG networks and maintain efficient synaptic function and metabolism in activated lumbar CPG networks. This finding suggests the possibility that putative astrocytic and neuronal cells in the L5 ventral horn contribute to generating the rhythms and patterns of locomotor-like activity by activated CPG networks in the first to fifth lumbar spinal cord.
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Affiliation(s)
- Itaru Yazawa
- Global Research Center for Innovative Life Science, Hoshi University School of Pharmacy and Pharmaceutical Sciences, Shinagawa, Tokyo 142-8501, Japan.
| | - Shuntaro Okazaki
- Clinical Research Center, Murayama Medical Center, Musashimurayama, Tokyo 208-0011, Japan; Faculty of Human Sciences, Waseda University School of Human Sciences, Tokorozawa, Saitama 359-1192, Japan
| | - Shigefumi Yokota
- Department of Anatomy and Neurosciences, Shimane University School of Medicine, Izumo, Shimane 693-8501, Japan
| | - Kotaro Takeda
- Clinical Research Center, Murayama Medical Center, Musashimurayama, Tokyo 208-0011, Japan; Faculty of Rehabilitation, Fujita Health University School of Healthcare, Toyoake, Aichi 470-1192, Japan
| | - Isato Fukushi
- Clinical Research Center, Murayama Medical Center, Musashimurayama, Tokyo 208-0011, Japan; Faculty of Health Sciences, Uekusa Gakuen University, Chiba, Chiba 264-0007, Japan
| | - Masashi Yoshizawa
- Clinical Research Center, Murayama Medical Center, Musashimurayama, Tokyo 208-0011, Japan; Department of Pediatrics, Faculty of Medicine, University of Yamanashi, Chuo, Yamanashi 409-3898, Japan
| | - Hiroshi Onimaru
- Department of Physiology, Showa University School of Medicine, Shinagawa, Tokyo 142-8555, Japan
| | - Yasumasa Okada
- Clinical Research Center, Murayama Medical Center, Musashimurayama, Tokyo 208-0011, Japan
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Broadhead MJ, Miles GB. A common role for astrocytes in rhythmic behaviours? Prog Neurobiol 2021; 202:102052. [PMID: 33894330 DOI: 10.1016/j.pneurobio.2021.102052] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Revised: 03/03/2021] [Accepted: 04/13/2021] [Indexed: 01/16/2023]
Abstract
Astrocytes are a functionally diverse form of glial cell involved in various aspects of nervous system infrastructure, from the metabolic and structural support of neurons to direct neuromodulation of synaptic activity. Investigating how astrocytes behave in functionally related circuits may help us understand whether there is any conserved logic to the role of astrocytes within neuronal networks. Astrocytes are implicated as key neuromodulatory cells within neural circuits that control a number of rhythmic behaviours such as breathing, locomotion and circadian sleep-wake cycles. In this review, we examine the evidence that astrocytes are directly involved in the regulation of the neural circuits underlying six different rhythmic behaviours: locomotion, breathing, chewing, gastrointestinal motility, circadian sleep-wake cycles and oscillatory feeding behaviour. We discuss how astrocytes are integrated into the neuronal networks that regulate these behaviours, and identify the potential gliotransmission signalling mechanisms involved. From reviewing the evidence of astrocytic involvement in a range of rhythmic behaviours, we reveal a heterogenous array of gliotransmission mechanisms, which help to regulate neuronal networks. However, we also observe an intriguing thread of commonality, in the form of purinergic gliotransmission, which is frequently utilised to facilitate feedback inhibition within rhythmic networks to constrain a given behaviour within its operational range.
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Affiliation(s)
- Matthew J Broadhead
- School of Psychology and Neuroscience, University of St Andrews, St Andrews, UK.
| | - Gareth B Miles
- School of Psychology and Neuroscience, University of St Andrews, St Andrews, UK
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Hodges NA, Barr RW, Murfee WL. The maintenance of adult peripheral adult nerve and microvascular networks in the rat mesentery culture model. J Neurosci Methods 2020; 346:108923. [PMID: 32888964 DOI: 10.1016/j.jneumeth.2020.108923] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Revised: 08/23/2020] [Accepted: 08/24/2020] [Indexed: 11/18/2022]
Abstract
BACKGROUND Neurovascular patterning is an emerging area of microvascular research. While overlapping molecular signals highlight links between angiogenesis and neurogenesis, advancing our understanding is limited by a lack of in vitro models containing both systems. One potential model is the rat mesentery culture model, which our laboratory has recently introduced as an ex vivo tool to investigate cellular dynamics during angiogenesis in a microvascular network scenario. The objective of this study was to demonstrate the use of the rat mesentery culture model as an ex vivo platform for maintaining the spatiotemporal relationship between blood vessels and peripheral nerves during angiogenesis in adult microvascular networks. METHODS Adult male Wistar rat mesenteric tissue windows were harvested, rinsed in sterile DPBS and medium and then cultured per group: 1) MEM alone and 2) NBM with NGF and 20 % FBS (nerve culture medium). On day 3 post culture tissues were labeled for endothelial (PECAM) and neural (class III β-tubulin, NG2, tyrosine hydroxylase, CGRP) markers. RESULTS In MEM alone tissues nerve segment degeneration was supported by discontinuous nerve or absence of nerve marker labeling. Nerve presence at the arteriole level and capillary level was maintained for the nerve culture medium group compared to day 0, non-cultured control group (unstimulated). COMPARISON WITH EXISTING METHODS AND CONCLUSIONS The results support the use of specific medium types to maintain nerve presence across cultured microvascular networks and implicates the rat mesentery culture model as a novel ex vivo tool for investigating neurovascular patterning in adult tissues.
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Affiliation(s)
- Nicholas A Hodges
- Tulane University, Department of Biomedical Engineering, New Orleans, LA, 70118, United States; University of Florida, Department of Biomedical Engineering, Gainesville, FL, 32611, United States
| | - Ryan W Barr
- Tulane University, Department of Biomedical Engineering, New Orleans, LA, 70118, United States
| | - Walter L Murfee
- Tulane University, Department of Biomedical Engineering, New Orleans, LA, 70118, United States; University of Florida, Department of Biomedical Engineering, Gainesville, FL, 32611, United States.
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7
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Taccola G, Salazar BH, Apicella R, Hogan MK, Horner PJ, Sayenko D. Selective Antagonism of A1 Adenosinergic Receptors Strengthens the Neuromodulation of the Sensorimotor Network During Epidural Spinal Stimulation. Front Syst Neurosci 2020; 14:44. [PMID: 32760254 PMCID: PMC7372902 DOI: 10.3389/fnsys.2020.00044] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2020] [Accepted: 06/16/2020] [Indexed: 01/02/2023] Open
Abstract
Although epidural spinal stimulation (ESS) results in promising therapeutic effects in individuals with spinal cord injury (SCI), its potential to generate functional motor recovery varies between individuals and remains largely unclear. However, both preclinical and clinical studies indicate the capacity of electrical and pharmacological interventions to synergistically increase the engagement of spinal sensorimotor networks and regain motor function after SCI. This study explored whether selective pharmacological antagonism of the adenosine A1 receptor subtype synergizes with ESS, thereby increasing motor response. We hypothesized that selective pharmacological antagonism of A1 receptors during ESS would produce facilitatory effects in spinal sensorimotor networks detected as an increased amplitude of spinally-evoked motor potentials and sustained duration of ESS induced activity. Terminal experiments were performed in adult rats using trains of stereotyped pulses at 40 Hz delivered at L5 with the local administration to the cord of 8-cyclopentyl-1,3-dipropylxanthine (DPCPX). We demonstrated that ESS combined with the blockage of A1 receptors increased the magnitude of the endogenous modulation and postponed the decay of responses that occur during ESS alone. Although DPCPX significantly increased the yield of repetitive stimulation in intact spinal cords, the effects of A1 antagonism on motor evoked responses after an acute spinal transection was not detected. These studies support the future investigation of the optimal dosage, methods of delivery, and systemic effects of the synergistic application of A1 antagonists and spinal stimulation in the intact and injured spinal cord.
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Affiliation(s)
- Giuliano Taccola
- Department of Neuroscience, International School for Advanced Studies (SISSA), Trieste, Italy
- Department of Neurosurgery, Center for Neuroregeneration, Houston Methodist Research Institute, Houston, TX, United States
| | - Betsy Habeth Salazar
- Department of Neurosurgery, Center for Neuroregeneration, Houston Methodist Research Institute, Houston, TX, United States
| | - Rosamaria Apicella
- Department of Neuroscience, International School for Advanced Studies (SISSA), Trieste, Italy
| | - Matthew Kevin Hogan
- Department of Neurosurgery, Center for Neuroregeneration, Houston Methodist Research Institute, Houston, TX, United States
| | - Philip John Horner
- Department of Neurosurgery, Center for Neuroregeneration, Houston Methodist Research Institute, Houston, TX, United States
| | - Dimitry Sayenko
- Department of Neurosurgery, Center for Neuroregeneration, Houston Methodist Research Institute, Houston, TX, United States
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Nanostructural Diversity of Synapses in the Mammalian Spinal Cord. Sci Rep 2020; 10:8189. [PMID: 32424125 PMCID: PMC7235094 DOI: 10.1038/s41598-020-64874-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Accepted: 04/21/2020] [Indexed: 11/25/2022] Open
Abstract
Functionally distinct synapses exhibit diverse and complex organisation at molecular and nanoscale levels. Synaptic diversity may be dependent on developmental stage, anatomical locus and the neural circuit within which synapses reside. Furthermore, astrocytes, which align with pre and post-synaptic structures to form ‘tripartite synapses’, can modulate neural circuits and impact on synaptic organisation. In this study, we aimed to determine which factors impact the diversity of excitatory synapses throughout the lumbar spinal cord. We used PSD95-eGFP mice, to visualise excitatory postsynaptic densities (PSDs) using high-resolution and super-resolution microscopy. We reveal a detailed and quantitative map of the features of excitatory synapses in the lumbar spinal cord, detailing synaptic diversity that is dependent on developmental stage, anatomical region and whether associated with VGLUT1 or VGLUT2 terminals. We report that PSDs are nanostructurally distinct between spinal laminae and across age groups. PSDs receiving VGLUT1 inputs also show enhanced nanostructural complexity compared with those receiving VGLUT2 inputs, suggesting pathway-specific diversity. Finally, we show that PSDs exhibit greater nanostructural complexity when part of tripartite synapses, and we provide evidence that astrocytic activation enhances PSD95 expression. Taken together, these results provide novel insights into the regulation and diversification of synapses across functionally distinct spinal regions and advance our general understanding of the ‘rules’ governing synaptic nanostructural organisation.
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Broadhead MJ, Miles GB. Bi-Directional Communication Between Neurons and Astrocytes Modulates Spinal Motor Circuits. Front Cell Neurosci 2020; 14:30. [PMID: 32180706 PMCID: PMC7057799 DOI: 10.3389/fncel.2020.00030] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2019] [Accepted: 02/03/2020] [Indexed: 01/22/2023] Open
Abstract
Evidence suggests that astrocytes are not merely supportive cells in the nervous system but may actively participate in the control of neural circuits underlying cognition and behavior. In this study, we examined the role of astrocytes within the motor circuitry of the mammalian spinal cord. Pharmacogenetic manipulation of astrocytic activity in isolated spinal cord preparations obtained from neonatal mice revealed astrocyte-derived, adenosinergic modulation of the frequency of rhythmic output generated by the locomotor central pattern generator (CPG) network. Live Ca2+ imaging demonstrated increased activity in astrocytes during locomotor-related output and in response to the direct stimulation of spinal neurons. Finally, astrocytes were found to respond to neuronally-derived glutamate in a metabotropic glutamate receptor 5 (mGluR5) dependent manner, which in turn drives astrocytic modulation of the locomotor network. Our work identifies bi-directional signaling mechanisms between neurons and astrocytes underlying modulatory feedback control of motor circuits, which may act to constrain network output within optimal ranges for movement.
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Affiliation(s)
- Matthew J Broadhead
- School of Psychology and Neuroscience, University of St Andrews, St Andrews, United Kingdom
| | - Gareth B Miles
- School of Psychology and Neuroscience, University of St Andrews, St Andrews, United Kingdom
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Steuer I, Guertin PA. Central pattern generators in the brainstem and spinal cord: an overview of basic principles, similarities and differences. Rev Neurosci 2019; 30:107-164. [PMID: 30543520 DOI: 10.1515/revneuro-2017-0102] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2017] [Accepted: 03/30/2018] [Indexed: 12/11/2022]
Abstract
Central pattern generators (CPGs) are generally defined as networks of neurons capable of enabling the production of central commands, specifically controlling stereotyped, rhythmic motor behaviors. Several CPGs localized in brainstem and spinal cord areas have been shown to underlie the expression of complex behaviors such as deglutition, mastication, respiration, defecation, micturition, ejaculation, and locomotion. Their pivotal roles have clearly been demonstrated although their organization and cellular properties remain incompletely characterized. In recent years, insightful findings about CPGs have been made mainly because (1) several complementary animal models were developed; (2) these models enabled a wide variety of techniques to be used and, hence, a plethora of characteristics to be discovered; and (3) organizations, functions, and cell properties across all models and species studied thus far were generally found to be well-preserved phylogenetically. This article aims at providing an overview for non-experts of the most important findings made on CPGs in in vivo animal models, in vitro preparations from invertebrate and vertebrate species as well as in primates. Data about CPG functions, adaptation, organization, and cellular properties will be summarized with a special attention paid to the network for locomotion given its advanced level of characterization compared with some of the other CPGs. Similarities and differences between these networks will also be highlighted.
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Affiliation(s)
- Inge Steuer
- Neuroscience Unit, Laval University Medical Center (CHUL - CHU de Québec), 2705 Laurier Blvd, Quebec City, Quebec G1V 4G2, Canada
| | - Pierre A Guertin
- Neuroscience Unit, Laval University Medical Center (CHUL - CHU de Québec), 2705 Laurier Blvd, Quebec City, Quebec G1V 4G2, Canada
- Faculty of Medicine, Department of Psychiatry and Neurosciences, Laval University, Quebec City, Quebec G1V 0A6, Canada
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Cortés A, Casadó-Anguera V, Moreno E, Casadó V. The heterotetrameric structure of the adenosine A 1-dopamine D 1 receptor complex: Pharmacological implication for restless legs syndrome. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2019; 84:37-78. [PMID: 31229177 DOI: 10.1016/bs.apha.2019.01.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Dopaminergic and purinergic signaling play a pivotal role in neurological diseases associated with motor symptoms, including Parkinson's disease (PD), multiple sclerosis, amyotrophic lateral sclerosis, Huntington disease, Restless Legs Syndrome (RLS), spinal cord injury (SCI), and ataxias. Extracellular dopamine and adenosine exert their functions interacting with specific dopamine (DR) or adenosine (AR) receptors, respectively, expressed on the surface of target cells. These receptors are members of the family A of G protein-coupled receptors (GPCRs), which is the largest protein superfamily in mammalian genomes. GPCRs are target of about 40% of all current marketed drugs, highlighting their importance in clinical medicine. The striatum receives the densest dopamine innervations and contains the highest density of dopamine receptors. The modulatory role of adenosine on dopaminergic transmission depends largely on the existence of antagonistic interactions mediated by specific subtypes of DRs and ARs, the so-called A2AR-D2R and A1R-D1R interactions. Due to the dopamine/adenosine antagonism in the CNS, it was proposed that ARs and DRs could form heteromers in the neuronal cell surface. Therefore, adenosine can affect dopaminergic signaling through receptor-receptor interactions and by modulations in their shared intracellular pathways in the striatum and spinal cord. In this work we describe the allosteric modulations between GPCR protomers, focusing in those of adenosine and dopamine within the A1R-D1R heteromeric complex, which is involved in RLS. We also propose that the knowledge about the intricate allosteric interactions within the A1R-D1R heterotetramer, may facilitate the treatment of motor alterations, not only when the dopamine pathway is hyperactivated (RLS, chorea, etc.) but also when motor function is decreased (SCI, aging, PD, etc.).
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Affiliation(s)
- Antoni Cortés
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain; Institute of Biomedicine of the University of Barcelona (IBUB), Barcelona, Spain; Department of Biochemistry and Molecular Biomedicine, Faculty of Biology, University of Barcelona, Barcelona, Spain
| | - Verònica Casadó-Anguera
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain; Institute of Biomedicine of the University of Barcelona (IBUB), Barcelona, Spain; Department of Biochemistry and Molecular Biomedicine, Faculty of Biology, University of Barcelona, Barcelona, Spain
| | - Estefanía Moreno
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain; Institute of Biomedicine of the University of Barcelona (IBUB), Barcelona, Spain; Department of Biochemistry and Molecular Biomedicine, Faculty of Biology, University of Barcelona, Barcelona, Spain
| | - Vicent Casadó
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain; Institute of Biomedicine of the University of Barcelona (IBUB), Barcelona, Spain; Department of Biochemistry and Molecular Biomedicine, Faculty of Biology, University of Barcelona, Barcelona, Spain.
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12
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Ferré S, Díaz-Ríos M, Salamone JD, Prediger RD. New Developments on the Adenosine Mechanisms of the Central Effects of Caffeine and Their Implications for Neuropsychiatric Disorders. J Caffeine Adenosine Res 2018; 8:121-131. [PMID: 30596206 PMCID: PMC6306650 DOI: 10.1089/caff.2018.0017] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Recent studies on interactions between striatal adenosine and dopamine and one of its main targets, the adenosine A2A receptor–dopamine D2 receptor (A2AR–D2R) heteromer, have provided a better understanding of the mechanisms involved in the psychostimulant effects of caffeine and have brought forward new data on the mechanisms of operation of classical orthosteric ligands within G protein-coupled receptor heteromers. The striatal A2AR–D2R heteromer has a tetrameric structure and forms part of a signaling complex that includes a Gs and a Gi protein and the effector adenyl cyclase (subtype AC5). Another target of caffeine, the adenosine A1 receptor–dopamine D1 receptor (A1R–D1R) heteromer, seems to have a very similar structure. Initially suggested to be localized in the striatum, the A1R–D1R heteromer has now been identified in the spinal motoneuron and shown to mediate the spinally generated caffeine-induced locomotion. In this study, we review the recently discovered properties of A2AR–D2R and A1R–D1R heteromers. Our studies demonstrate that these complexes are a necessary condition to sustain the canonical antagonistic interaction between a Gs-coupled receptor (A2AR or D1R) and a Gi-coupled receptor (D2R or A1R) at the adenylyl cyclase level, which constitutes a new concept in the field of G protein-coupled receptor physiology and pharmacology. A2AR antagonists targeting the striatal A2AR–D2R heteromer are already being considered as therapeutic agents in Parkinson's disease. In this study, we review the preclinical evidence that indicates that caffeine and A2AR antagonists could be used to treat the motivational symptoms of depression and attention-deficit/hyperactivity disorder, while A1R antagonists selectively targeting the spinal A1R–D1R heteromer could be used in the recovery of spinal cord injury.
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Affiliation(s)
- Sergi Ferré
- Integrative Neurobiology Section, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Baltimore, Maryland
| | - Manuel Díaz-Ríos
- Department of Anatomy and Neurobiology, Institute of Neurobiology, University of Puerto Rico, Medical Sciences Campus, San Juan, Puerto Rico
| | - John D Salamone
- Department of Psychological Sciences, University of Connecticut, Storrs, Connecticut
| | - Rui Daniel Prediger
- Department of Pharmacology, Federal University of Santa Catarina, Florianópolis, Brazil
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13
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Rivera-Oliver M, Moreno E, Álvarez-Bagnarol Y, Ayala-Santiago C, Cruz-Reyes N, Molina-Castro GC, Clemens S, Canela EI, Ferré S, Casadó V, Díaz-Ríos M. Adenosine A 1-Dopamine D 1 Receptor Heteromers Control the Excitability of the Spinal Motoneuron. Mol Neurobiol 2018; 56:797-811. [PMID: 29797183 DOI: 10.1007/s12035-018-1120-y] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2018] [Accepted: 05/11/2018] [Indexed: 10/16/2022]
Abstract
While the role of the ascending dopaminergic system in brain function and dysfunction has been a subject of extensive research, the role of the descending dopaminergic system in spinal cord function and dysfunction is just beginning to be understood. Adenosine plays a key role in the inhibitory control of the ascending dopaminergic system, largely dependent on functional complexes of specific subtypes of adenosine and dopamine receptors. Combining a selective destabilizing peptide strategy with a proximity ligation assay and patch-clamp electrophysiology in slices from male mouse lumbar spinal cord, the present study demonstrates the existence of adenosine A1-dopamine D1 receptor heteromers in the spinal motoneuron by which adenosine tonically inhibits D1 receptor-mediated signaling. A1-D1 receptor heteromers play a significant control of the motoneuron excitability, represent main targets for the excitatory effects of caffeine in the spinal cord and can constitute new targets for the pharmacological therapy after spinal cord injury, motor aging-associated disorders and restless legs syndrome.
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Affiliation(s)
- Marla Rivera-Oliver
- Department of Anatomy and Neurobiology and Institute of Neurobiology, University of Puerto Rico, Medical Sciences, Rio Piedras and Cayey Campuses, San Juan, 00936, Puerto Rico
| | - Estefanía Moreno
- Center for Biomedical Research in Neurodegenerative Diseases Network (CIBERNED) and Department of Biochemistry and Molecular Biomedicine, Faculty of Biology, Institute of Biomedicine of the University of Barcelona, University of Barcelona, 08028, Barcelona, Spain
| | - Yocasta Álvarez-Bagnarol
- Department of Anatomy and Neurobiology and Institute of Neurobiology, University of Puerto Rico, Medical Sciences, Rio Piedras and Cayey Campuses, San Juan, 00936, Puerto Rico
| | - Christian Ayala-Santiago
- Department of Anatomy and Neurobiology and Institute of Neurobiology, University of Puerto Rico, Medical Sciences, Rio Piedras and Cayey Campuses, San Juan, 00936, Puerto Rico
| | - Nicole Cruz-Reyes
- Department of Anatomy and Neurobiology and Institute of Neurobiology, University of Puerto Rico, Medical Sciences, Rio Piedras and Cayey Campuses, San Juan, 00936, Puerto Rico
| | - Gian Carlo Molina-Castro
- Department of Anatomy and Neurobiology and Institute of Neurobiology, University of Puerto Rico, Medical Sciences, Rio Piedras and Cayey Campuses, San Juan, 00936, Puerto Rico
| | - Stefan Clemens
- Department of Physiology, Brody School of Medicine, East Carolina University, Greenville, NC, 27834, USA
| | - Enric I Canela
- Center for Biomedical Research in Neurodegenerative Diseases Network (CIBERNED) and Department of Biochemistry and Molecular Biomedicine, Faculty of Biology, Institute of Biomedicine of the University of Barcelona, University of Barcelona, 08028, Barcelona, Spain
| | - Sergi Ferré
- Integrative Neurobiology Section, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Triad Technology Building, 333 Cassell Drive, Baltimore, MD, 21224, USA.
| | - Vicent Casadó
- Center for Biomedical Research in Neurodegenerative Diseases Network (CIBERNED) and Department of Biochemistry and Molecular Biomedicine, Faculty of Biology, Institute of Biomedicine of the University of Barcelona, University of Barcelona, 08028, Barcelona, Spain
| | - Manuel Díaz-Ríos
- Department of Anatomy and Neurobiology and Institute of Neurobiology, University of Puerto Rico, Medical Sciences, Rio Piedras and Cayey Campuses, San Juan, 00936, Puerto Rico
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14
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Acton D, Broadhead MJ, Miles GB. Modulation of spinal motor networks by astrocyte-derived adenosine is dependent on D 1-like dopamine receptor signaling. J Neurophysiol 2018; 120:998-1009. [PMID: 29790837 PMCID: PMC6171060 DOI: 10.1152/jn.00783.2017] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Astrocytes modulate many neuronal networks, including spinal networks responsible for the generation of locomotor behavior. Astrocytic modulation of spinal motor circuits involves release of ATP from astrocytes, hydrolysis of ATP to adenosine, and subsequent activation of neuronal A1 adenosine receptors (A1Rs). The net effect of this pathway is a reduction in the frequency of locomotor-related activity. Recently, it was proposed that A1Rs modulate burst frequency by blocking the D1-like dopamine receptor (D1LR) signaling pathway; however, adenosine also modulates ventral horn circuits by dopamine-independent pathways. Here, we demonstrate that adenosine produced upon astrocytic stimulation modulates locomotor-related activity by counteracting the excitatory effects of D1LR signaling and does not act by previously described dopamine-independent pathways. In spinal cord preparations from postnatal mice, a D1LR agonist, SKF 38393, increased the frequency of locomotor-related bursting induced by 5-hydroxytryptamine and N-methyl-d-aspartate. Bath-applied adenosine reduced burst frequency only in the presence of SKF 38393, as did adenosine produced after activation of protease-activated receptor-1 to stimulate astrocytes. Furthermore, the A1R antagonist 8-cyclopentyl-1,3-dipropylxanthine enhanced burst frequency only in the presence of SKF 38393, indicating that endogenous adenosine produced by astrocytes during network activity also acts by modulating D1LR signaling. Finally, modulation of bursting by adenosine released upon stimulation of astrocytes was blocked by protein kinase inhibitor-(14-22) amide, a protein kinase A (PKA) inhibitor, consistent with A1R-mediated antagonism of the D1LR/adenylyl cyclase/PKA pathway. Together, these findings support a novel, astrocytic mechanism of metamodulation within the mammalian spinal cord, highlighting the complexity of the molecular interactions that specify motor output. NEW & NOTEWORTHY Astrocytes within the spinal cord produce adenosine during ongoing locomotor-related activity or when experimentally stimulated. Here, we show that adenosine derived from astrocytes acts at A1 receptors to inhibit a pathway by which D1-like receptors enhance the frequency of locomotor-related bursting. These data support a novel form of metamodulation within the mammalian spinal cord, enhancing our understanding of neuron-astrocyte interactions and their importance in shaping network activity.
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Affiliation(s)
- David Acton
- School of Psychology and Neuroscience, University of St Andrews , St Andrews , United Kingdom
| | - Matthew J Broadhead
- School of Psychology and Neuroscience, University of St Andrews , St Andrews , United Kingdom
| | - Gareth B Miles
- School of Psychology and Neuroscience, University of St Andrews , St Andrews , United Kingdom
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15
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Sebastião AM, Rei N, Ribeiro JA. Amyotrophic Lateral Sclerosis (ALS) and Adenosine Receptors. Front Pharmacol 2018; 9:267. [PMID: 29713276 PMCID: PMC5911503 DOI: 10.3389/fphar.2018.00267] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2017] [Accepted: 03/09/2018] [Indexed: 12/11/2022] Open
Abstract
In the present review we discuss the potential involvement of adenosinergic signaling, in particular the role of adenosine receptors, in amyotrophic lateral sclerosis (ALS). Though the literature on this topic is not abundant, the information so far available on adenosine receptors in animal models of ALS highlights the interest to continue to explore the role of these receptors in this neurodegenerative disease. Indeed, all motor neurons affected in ALS are responsive to adenosine receptor ligands but interestingly, there are alterations in pre-symptomatic or early symptomatic stages that mirror those in advanced disease stages. Information starts to emerge pointing toward a beneficial role of A2A receptors (A2AR), most probably at early disease states, and a detrimental role of caffeine, in clear contrast with what occurs in other neurodegenerative diseases. However, some evidence also exists on a beneficial action of A2AR antagonists. It may happen that there are time windows where A2AR prove beneficial and others where their blockade is required. Furthermore, the same changes may not occur simultaneously at the different synapses. In line with this, it is not fully understood if ALS is a dying back disease or if it propagates in a centrifugal way. It thus seems crucial to understand how motor neuron dysfunction occurs, how adenosine receptors are involved in those dysfunctions and whether the early changes in purinergic signaling are compensatory or triggers for the disease. Getting this information is crucial before starting the design of purinergic based strategies to halt or delay disease progression.
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Affiliation(s)
- Ana M Sebastião
- Instituto de Farmacologia e Neurociências, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal.,Instituto de Medicina Molecular, Universidade de Lisboa, Lisbon, Portugal
| | - Nádia Rei
- Instituto de Farmacologia e Neurociências, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal.,Instituto de Medicina Molecular, Universidade de Lisboa, Lisbon, Portugal
| | - Joaquim A Ribeiro
- Instituto de Farmacologia e Neurociências, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal.,Instituto de Medicina Molecular, Universidade de Lisboa, Lisbon, Portugal
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16
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Acton D, Miles GB. Gliotransmission and adenosinergic modulation: insights from mammalian spinal motor networks. J Neurophysiol 2017; 118:3311-3327. [PMID: 28954893 DOI: 10.1152/jn.00230.2017] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Astrocytes are proposed to converse with neurons at tripartite synapses, detecting neurotransmitter release and responding with release of gliotransmitters, which in turn modulate synaptic strength and neuronal excitability. However, a paucity of evidence from behavioral studies calls into question the importance of gliotransmission for the operation of the nervous system in healthy animals. Central pattern generator (CPG) networks in the spinal cord and brain stem coordinate the activation of muscles during stereotyped activities such as locomotion, inspiration, and mastication and may therefore provide tractable models in which to assess the contribution of gliotransmission to behaviorally relevant neural activity. We review evidence for gliotransmission within spinal locomotor networks, including studies indicating that adenosine derived from astrocytes regulates the speed of locomotor activity via metamodulation of dopamine signaling.
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Affiliation(s)
- David Acton
- School of Psychology and Neuroscience, University of St Andrews, St Andrews, Fife , United Kingdom
| | - Gareth B Miles
- School of Psychology and Neuroscience, University of St Andrews, St Andrews, Fife , United Kingdom
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