1
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Deng Y, Tang S, Cheng J, Zhang X, Jing D, Lin Z, Zhou J. Integrated analysis reveals Atf3 promotes neuropathic pain via orchestrating JunB mediated release of inflammatory cytokines in DRG macrophage. Life Sci 2023; 329:121939. [PMID: 37451398 DOI: 10.1016/j.lfs.2023.121939] [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: 03/17/2023] [Revised: 06/08/2023] [Accepted: 07/11/2023] [Indexed: 07/18/2023]
Abstract
The dorsal root ganglion (DRG) is actively involved in the development of neuropathic pain (NP), serving as an intermediate station for pain signals from the peripheral nervous system to the central nervous system. The mechanism by which DRG is involved in NP regulation is not fully understood. The immune system plays a pivotal role in the physiological and pathological states of the human body. In recent years, the immune system has been thought to play an increasingly important role in the pathogenesis of NP. The immune system plays a key role in pain through specific immune cells and their immune-related genes (IRGs). However, the mechanism by which IRGs of DRG regulate NP action has not been fully elucidated. Here, we performed Gene Ontology (GO) and the Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses of IRGs in DRG bulk-RNA sequencing data from spared nerve injury (SNI) model mice and found that their IRGs were enriched in many pathways, especially in the immune response pathway. Subsequently, we analyzed single-cell RNA sequencing (scRNA-seq) data from DRGs extracted from the SNI model and identified eight cell populations. Among them, the highest IRG activity was presented in macrophages. Next, we analyzed the scRNA and bulk-sequencing data and deduced five common transcription factors (TFs) from differentially expressed genes (DEGs). The protein-protein interaction (PPI) network suggested that Atf3 and JunB are closely related. In vitro experiments, we verified that the protein and mRNA expressions of Atf3 and JunB were up-regulated in macrophages after lipopolysaccharide (LPS) stimulation. Moreover, the down-regulation of Atf3 reduced the release of inflammatory cytokines and decreased the protein and mRNA expression levels of JunB. The down-regulation of JunB also reduced the release of inflammatory cytokines. Furthermore, overexpression of JunB attenuated the effect of Atf3 down-regulation in reducing the release of inflammatory cytokines. Therefore, we speculated that Atf3 might promote NP through JunB-mediated release of inflammatory factors in DRG macrophages.
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Affiliation(s)
- Yingdong Deng
- Department of Anesthesiology, The Third Affiliated Hospital of Southern Medical University, Guangzhou, Guangdong Province 510000, China
| | - Simin Tang
- Department of Anesthesiology, The Third Affiliated Hospital of Southern Medical University, Guangzhou, Guangdong Province 510000, China
| | - Jiurong Cheng
- Department of Anesthesiology, The Third Affiliated Hospital of Southern Medical University, Guangzhou, Guangdong Province 510000, China
| | - Xiangsheng Zhang
- Department of Anesthesiology, The Third Affiliated Hospital of Southern Medical University, Guangzhou, Guangdong Province 510000, China
| | - Danqin Jing
- College of Anesthesiology, Shanxi Medical University, Taiyuan, Shanxi Province 030001, China
| | - Ziqiang Lin
- Department of Anesthesiology, The Third Affiliated Hospital of Southern Medical University, Guangzhou, Guangdong Province 510000, China
| | - Jun Zhou
- Department of Anesthesiology, The Third Affiliated Hospital of Southern Medical University, Guangzhou, Guangdong Province 510000, China.
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2
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Katz HR, Arcese AA, Bloom O, Morgan JR. Activating Transcription Factor 3 (ATF3) is a Highly Conserved Pro-regenerative Transcription Factor in the Vertebrate Nervous System. Front Cell Dev Biol 2022; 10:824036. [PMID: 35350379 PMCID: PMC8957905 DOI: 10.3389/fcell.2022.824036] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2021] [Accepted: 02/17/2022] [Indexed: 12/24/2022] Open
Abstract
The vertebrate nervous system exhibits dramatic variability in regenerative capacity across species and neuronal populations. For example, while the mammalian central nervous system (CNS) is limited in its regenerative capacity, the CNS of many other vertebrates readily regenerates after injury, as does the peripheral nervous system (PNS) of mammals. Comparing molecular responses across species and tissues can therefore provide valuable insights into both conserved and distinct mechanisms of successful regeneration. One gene that is emerging as a conserved pro-regenerative factor across vertebrates is activating transcription factor 3 (ATF3), which has long been associated with tissue trauma. A growing number of studies indicate that ATF3 may actively promote neuronal axon regrowth and regeneration in species ranging from lampreys to mammals. Here, we review data on the structural and functional conservation of ATF3 protein across species. Comparing RNA expression data across species that exhibit different abilities to regenerate their nervous system following traumatic nerve injury reveals that ATF3 is consistently induced in neurons within the first few days after injury. Genetic deletion or knockdown of ATF3 expression has been shown in mouse and zebrafish, respectively, to reduce axon regeneration, while inducing ATF3 promotes axon sprouting, regrowth, or regeneration. Thus, we propose that ATF3 may be an evolutionarily conserved regulator of neuronal regeneration. Identifying downstream effectors of ATF3 will be a critical next step in understanding the molecular basis of vertebrate CNS regeneration.
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Affiliation(s)
- Hilary R Katz
- The Eugene Bell Center for Regenerative Biology and Tissue Engineering, Marine Biological Laboratory, Woods Hole, MA, United States
| | - Anthony A Arcese
- The Feinstein Institutes for Medical Research, Manhasset, NY, United States
| | - Ona Bloom
- The Feinstein Institutes for Medical Research, Manhasset, NY, United States.,The Donald and Barbara Zucker School of Medicine, Hempstead, NY, United States
| | - Jennifer R Morgan
- The Eugene Bell Center for Regenerative Biology and Tissue Engineering, Marine Biological Laboratory, Woods Hole, MA, United States
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3
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Avraham O, Feng R, Ewan EE, Rustenhoven J, Zhao G, Cavalli V. Profiling sensory neuron microenvironment after peripheral and central axon injury reveals key pathways for neural repair. eLife 2021; 10:e68457. [PMID: 34586065 PMCID: PMC8480984 DOI: 10.7554/elife.68457] [Citation(s) in RCA: 45] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Accepted: 09/12/2021] [Indexed: 12/19/2022] Open
Abstract
Sensory neurons with cell bodies in dorsal root ganglia (DRG) represent a useful model to study axon regeneration. Whereas regeneration and functional recovery occurs after peripheral nerve injury, spinal cord injury or dorsal root injury is not followed by regenerative outcomes. Regeneration of sensory axons in peripheral nerves is not entirely cell autonomous. Whether the DRG microenvironment influences the different regenerative capacities after injury to peripheral or central axons remains largely unknown. To answer this question, we performed a single-cell transcriptional profiling of mouse DRG in response to peripheral (sciatic nerve crush) and central axon injuries (dorsal root crush and spinal cord injury). Each cell type responded differently to the three types of injuries. All injuries increased the proportion of a cell type that shares features of both immune cells and glial cells. A distinct subset of satellite glial cells (SGC) appeared specifically in response to peripheral nerve injury. Activation of the PPARα signaling pathway in SGC, which promotes axon regeneration after peripheral nerve injury, failed to occur after central axon injuries. Treatment with the FDA-approved PPARα agonist fenofibrate increased axon regeneration after dorsal root injury. This study provides a map of the distinct DRG microenvironment responses to peripheral and central injuries at the single-cell level and highlights that manipulating non-neuronal cells could lead to avenues to promote functional recovery after CNS injuries or disease.
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Affiliation(s)
- Oshri Avraham
- Department of Neuroscience, Washington University School of MedicineSaint LouisUnited States
| | - Rui Feng
- Department of Neuroscience, Washington University School of MedicineSaint LouisUnited States
| | - Eric Edward Ewan
- Department of Neuroscience, Washington University School of MedicineSaint LouisUnited States
| | - Justin Rustenhoven
- Department of Pathology and Immunology, Washington University School of MedicineSt LouisUnited States
- Center for Brain Immunology and Glia (BIG), Washington University School of MedicineSt LouisUnited States
| | - Guoyan Zhao
- Department of Neuroscience, Washington University School of MedicineSaint LouisUnited States
- Department of Pathology and Immunology, Washington University School of MedicineSt LouisUnited States
| | - Valeria Cavalli
- Department of Neuroscience, Washington University School of MedicineSaint LouisUnited States
- Center of Regenerative Medicine, Washington University School of MedicineSt. LouisUnited States
- Hope Center for Neurological Disorders, Washington University School of MedicineSt. LouisUnited States
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4
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Cheng YC, Snavely A, Barrett LB, Zhang X, Herman C, Frost DJ, Riva P, Tochitsky I, Kawaguchi R, Singh B, Ivanis J, Huebner EA, Arvanites A, Oza V, Davidow L, Maeda R, Sakuma M, Grantham A, Wang Q, Chang AN, Pfaff K, Costigan M, Coppola G, Rubin LL, Schwer B, Alt FW, Woolf CJ. Topoisomerase I inhibition and peripheral nerve injury induce DNA breaks and ATF3-associated axon regeneration in sensory neurons. Cell Rep 2021; 36:109666. [PMID: 34496254 PMCID: PMC8462619 DOI: 10.1016/j.celrep.2021.109666] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Revised: 07/16/2021] [Accepted: 08/13/2021] [Indexed: 11/24/2022] Open
Abstract
Although axonal damage induces rapid changes in gene expression in primary sensory neurons, it remains unclear how this process is initiated. The transcription factor ATF3, one of the earliest genes responding to nerve injury, regulates expression of downstream genes that enable axon regeneration. By exploiting ATF3 reporter systems, we identify topoisomerase inhibitors as ATF3 inducers, including camptothecin. Camptothecin increases ATF3 expression and promotes neurite outgrowth in sensory neurons in vitro and enhances axonal regeneration after sciatic nerve crush in vivo. Given the action of topoisomerases in producing DNA breaks, we determine that they do occur immediately after nerve damage at the ATF3 gene locus in injured sensory neurons and are further increased after camptothecin exposure. Formation of DNA breaks in injured sensory neurons and enhancement of it pharmacologically may contribute to the initiation of those transcriptional changes required for peripheral nerve regeneration.
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Affiliation(s)
- Yung-Chih Cheng
- F.M. Kirby Neurobiology Center, Program in Neurobiology, Boston Children's Hospital, Boston, MA 02115, USA; Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Andrew Snavely
- F.M. Kirby Neurobiology Center, Program in Neurobiology, Boston Children's Hospital, Boston, MA 02115, USA; Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Lee B Barrett
- F.M. Kirby Neurobiology Center, Program in Neurobiology, Boston Children's Hospital, Boston, MA 02115, USA; Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Xuefei Zhang
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Howard Hughes Medical Institute, Boston, MA 02115, USA; Department of Genetics, Harvard Medical School, Boston, MA 02115, USA; Department of Pediatrics, Harvard Medical School, Boston, MA 02115, USA
| | - Crystal Herman
- F.M. Kirby Neurobiology Center, Program in Neurobiology, Boston Children's Hospital, Boston, MA 02115, USA
| | - Devlin J Frost
- F.M. Kirby Neurobiology Center, Program in Neurobiology, Boston Children's Hospital, Boston, MA 02115, USA
| | - Priscilla Riva
- F.M. Kirby Neurobiology Center, Program in Neurobiology, Boston Children's Hospital, Boston, MA 02115, USA
| | - Ivan Tochitsky
- F.M. Kirby Neurobiology Center, Program in Neurobiology, Boston Children's Hospital, Boston, MA 02115, USA; Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Riki Kawaguchi
- Departments of Psychiatry and Neurology, Semel Institute for Neuroscience and Human Behavior, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA
| | - Bhagat Singh
- F.M. Kirby Neurobiology Center, Program in Neurobiology, Boston Children's Hospital, Boston, MA 02115, USA; Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Jelena Ivanis
- F.M. Kirby Neurobiology Center, Program in Neurobiology, Boston Children's Hospital, Boston, MA 02115, USA
| | - Eric A Huebner
- F.M. Kirby Neurobiology Center, Program in Neurobiology, Boston Children's Hospital, Boston, MA 02115, USA; Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Anthony Arvanites
- Harvard Stem Cell Institute, Harvard University, Cambridge, MA 02138, USA
| | - Vatsal Oza
- Harvard Stem Cell Institute, Harvard University, Cambridge, MA 02138, USA
| | - Lance Davidow
- Harvard Stem Cell Institute, Harvard University, Cambridge, MA 02138, USA
| | - Rie Maeda
- F.M. Kirby Neurobiology Center, Program in Neurobiology, Boston Children's Hospital, Boston, MA 02115, USA
| | - Miyuki Sakuma
- F.M. Kirby Neurobiology Center, Program in Neurobiology, Boston Children's Hospital, Boston, MA 02115, USA; Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Alyssa Grantham
- F.M. Kirby Neurobiology Center, Program in Neurobiology, Boston Children's Hospital, Boston, MA 02115, USA
| | - Qing Wang
- Departments of Psychiatry and Neurology, Semel Institute for Neuroscience and Human Behavior, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA
| | - Amelia N Chang
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Howard Hughes Medical Institute, Boston, MA 02115, USA; Department of Genetics, Harvard Medical School, Boston, MA 02115, USA; Department of Pediatrics, Harvard Medical School, Boston, MA 02115, USA
| | - Kathleen Pfaff
- Harvard Stem Cell Institute, Harvard University, Cambridge, MA 02138, USA
| | - Michael Costigan
- F.M. Kirby Neurobiology Center, Program in Neurobiology, Boston Children's Hospital, Boston, MA 02115, USA; Anaesthesia Department, Boston Children's Hospital, Boston, MA 02115, USA
| | - Giovanni Coppola
- Departments of Psychiatry and Neurology, Semel Institute for Neuroscience and Human Behavior, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA
| | - Lee L Rubin
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, MA 02138, USA; Harvard Stem Cell Institute, Harvard University, Cambridge, MA 02138, USA
| | - Bjoern Schwer
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Howard Hughes Medical Institute, Boston, MA 02115, USA; Department of Genetics, Harvard Medical School, Boston, MA 02115, USA; Department of Pediatrics, Harvard Medical School, Boston, MA 02115, USA
| | - Frederick W Alt
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Howard Hughes Medical Institute, Boston, MA 02115, USA; Department of Genetics, Harvard Medical School, Boston, MA 02115, USA; Department of Pediatrics, Harvard Medical School, Boston, MA 02115, USA
| | - Clifford J Woolf
- F.M. Kirby Neurobiology Center, Program in Neurobiology, Boston Children's Hospital, Boston, MA 02115, USA; Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA; Harvard Stem Cell Institute, Harvard University, Cambridge, MA 02138, USA.
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5
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Yasko JR, Moss IL, Mains RE. Transcriptional Profiling of Non-injured Nociceptors After Spinal Cord Injury Reveals Diverse Molecular Changes. Front Mol Neurosci 2019; 12:284. [PMID: 32038157 PMCID: PMC6988781 DOI: 10.3389/fnmol.2019.00284] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Accepted: 11/08/2019] [Indexed: 01/01/2023] Open
Abstract
Traumatic spinal cord injury (SCI) has devastating implications for patients, including a high predisposition for developing chronic pain distal to the site of injury. Chronic pain develops weeks to months after injury, consequently, patients are treated after irreparable changes have occurred. Nociceptors are central to chronic pain; however, the diversity of this cellular population presents challenges to understanding mechanisms and attributing pain modalities to specific cell types. To begin to address how peripheral sensory neurons below the injury level may contribute to the below-level pain reported by SCI patients, we examined SCI-induced changes in gene expression in lumbar dorsal root ganglia (DRG) below the site of injury. SCI was performed at the T10 vertebral level, with injury produced by a vessel clip with a closing pressure of 15 g for 1 min. Alterations in gene expression produce long-term sensory changes, therefore, we were interested in studying SCI-induced transcripts before the onset of chronic pain, which may trigger changes in downstream signaling pathways and ultimately facilitate the transmission of pain. To examine changes in the nociceptor subpopulation in DRG distal to the site of injury, we retrograde labeled sensory neurons projecting to the hairy hindpaw skin with fluorescent dye and collected the corresponding lumbar (L2–L6) DRG 4 days post-injury. Following dissociation, labeled neurons were purified by fluorescence-activated cell sorting (FACS). RNA was extracted from sorted sensory neurons of naïve, sham, or SCI mice and sequenced. Transcript abundances validated that the desired population of nociceptors were isolated. Cross-comparisons to data sets from similar studies confirmed, we were able to isolate our cells of interest and identify a unique pattern of gene expression within a subpopulation of neurons projecting to the hairy hindpaw skin. Differential gene expression analysis showed high expression levels and significant transcript changes 4 days post-injury in SCI cell populations relevant to the onset of chronic pain. Regulatory interrelationships predicted by pathway analysis implicated changes within the synaptogenesis signaling pathway as well as networks related to inflammatory signaling mechanisms, suggesting a role for synaptic plasticity and a correlation with pro-inflammatory signaling in the transition from acute to chronic pain.
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Affiliation(s)
- Jessica R Yasko
- Department of Neuroscience, University of Connecticut Health Center, Farmington, CT, United States
| | - Isaac L Moss
- Department of Orthopedic Surgery and the Comprehensive Spine Center, University of Connecticut Health Center, Farmington, CT, United States
| | - Richard E Mains
- Department of Neuroscience, University of Connecticut Health Center, Farmington, CT, United States
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6
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Yu B, Yao C, Wang Y, Mao S, Wang Y, Wu R, Feng W, Chen Y, Yang J, Xue C, Liu D, Ding F, Gu X. The Landscape of Gene Expression and Molecular Regulation Following Spinal Cord Hemisection in Rats. Front Mol Neurosci 2019; 12:287. [PMID: 31824262 PMCID: PMC6883948 DOI: 10.3389/fnmol.2019.00287] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2019] [Accepted: 11/12/2019] [Indexed: 01/25/2023] Open
Abstract
Spinal cord injury (SCI) is a challenging clinical problem worldwide. The cellular state and molecular expression in spinal cord tissue after injury are extremely complex and closely related to functional recovery. However, the spatial and temporal changes of gene expression and regulation in various cell types after SCI are still unclear. Here, we collected the rostral and caudal regions to the lesion at 11 time points over a period of 28 days after rat hemisection SCI. Combining whole-transcriptome sequencing and bioinformatic analysis, we identified differentially expressed genes (DEGs) between spinal cord tissue from injured and sham-operated animals. Significantly altered biological processes were enriched from DEGs in astrocytes, microglia, oligodendrocytes, immune cells, and vascular systems after SCI. We then identified dynamic trends in these processes using the average expression profiles of DEGs. Gene expression and regulatory networks for selected biological processes were also constructed to illustrate the complicate difference between rostral and caudal tissues. Finally, we validated the expressions of some key genes from these networks, including α-synuclein, heme oxygenase 1, bone morphogenetic protein 2, activating transcription factor 3, and leukemia inhibitory factor. Collectively, we provided a comprehensive network of gene expression and regulation to shed light on the molecular characteristics of critical biological processes that occur after SCI, which will broaden the understanding of SCI and facilitate clinical therapeutics for SCI.
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Affiliation(s)
- Bin Yu
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, Co-innovation Center of Neuroregeneration, Nantong University, Nantong, China.,Jiangsu Clinical Medicine Center of Tissue Engineering and Nerve Injury Repair, Affiliated Hospital of Nantong University, Nantong University, Nantong, China
| | - Chun Yao
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, Co-innovation Center of Neuroregeneration, Nantong University, Nantong, China
| | - Yongjun Wang
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, Co-innovation Center of Neuroregeneration, Nantong University, Nantong, China
| | - Susu Mao
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, Co-innovation Center of Neuroregeneration, Nantong University, Nantong, China
| | - Yaxian Wang
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, Co-innovation Center of Neuroregeneration, Nantong University, Nantong, China
| | - Ronghua Wu
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, Co-innovation Center of Neuroregeneration, Nantong University, Nantong, China
| | - Wei Feng
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, Co-innovation Center of Neuroregeneration, Nantong University, Nantong, China
| | - Yanping Chen
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, Co-innovation Center of Neuroregeneration, Nantong University, Nantong, China
| | - Jian Yang
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, Co-innovation Center of Neuroregeneration, Nantong University, Nantong, China
| | - Chengbin Xue
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, Co-innovation Center of Neuroregeneration, Nantong University, Nantong, China
| | - Dong Liu
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, Co-innovation Center of Neuroregeneration, Nantong University, Nantong, China
| | - Fei Ding
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, Co-innovation Center of Neuroregeneration, Nantong University, Nantong, China
| | - Xiaosong Gu
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, Co-innovation Center of Neuroregeneration, Nantong University, Nantong, China.,Jiangsu Clinical Medicine Center of Tissue Engineering and Nerve Injury Repair, Affiliated Hospital of Nantong University, Nantong University, Nantong, China
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7
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Coelho A, Oliveira R, Cruz F, Cruz CD. Impairment of sensory afferents by intrathecal administration of botulinum toxin A improves neurogenic detrusor overactivity in chronic spinal cord injured rats. Exp Neurol 2016; 285:159-166. [PMID: 27235935 DOI: 10.1016/j.expneurol.2016.05.029] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Revised: 05/13/2016] [Accepted: 05/23/2016] [Indexed: 10/21/2022]
Abstract
Spinal cord injury (SCI) often leads to neurogenic detrusor overactivity (NDO) due to sprouting of sensory afferents on the lumbosacral spinal cord. NDO is characterized by high frequency of voiding contractions and increased intravesical pressure that may lead to urinary incontinence. The latter has been described as one of the consequences of SCI that mostly decreases quality of life. Bladder wall injections of botulinum toxin A (Onabot/A) are an effective option to manage NDO. The toxin strongly impairs parasympathetic and sensory fibres coursing the bladder wall. However the robust parasympathetic inhibition may inhibit voiding contractions and cause urinary retention in patients that retain voluntary voiding. Here, we hypothesised that by restricting the toxin activity to sensory fibres we can improve NDO without impairing voiding contractions. In the present work, we assessed the effect of Onabot/A on sensory neurons in chronic (4weeks) SCI rats by injecting the toxin intrathecally (IT), at lumbosacral spinal cord level. This route of administration was shown before to have an effect on bladder pain and contractility in an animal model of bladder inflammation. We found that IT Onabot/A led to a significant reduction in the frequency of expulsive contractions and a normalization of bladder basal pressure while maintaining voiding contractions of normal amplitude. Cleavage of SNAP-25 protein occurred mainly at the dorsal horn regions where most of the bladder afferents end. Cleaved SNAP-25 was not detected in motor or preganglionic parasympathetic neurons. A significant decrease in CGRP expression, a peptide exclusively present in sensory fibres in the spinal cord, occurred at the L5/L6 segments and associated dorsal root ganglia (DRG) after Onabot/A injection in SCI animals. Onabot/A strongly increased the expression of ATF3, a marker of neuronal stress, in L5/L6 DRG neurons. Taken together, our results suggest that IT Onabot/A has a predominant effect on bladder sensory fibres, and that such effect is enough to control NDO following chronic SCI. The mechanism of action of Onabot/A includes not only the cleavage of SNAP-25 in sensory terminals but also impairment of basic cellular machinery in the cell body of sensory neurons.
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Affiliation(s)
- Ana Coelho
- Department of Experimental Biology, Faculty of Medicine of Porto, University of Porto, Portugal; Translational NeuroUrology, IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Portugal; Instituto de Investigação e Inovação em Saúde - i3S, Universidade do Porto, Portugal.
| | - Raquel Oliveira
- Department of Experimental Biology, Faculty of Medicine of Porto, University of Porto, Portugal; Translational NeuroUrology, IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Portugal; Instituto de Investigação e Inovação em Saúde - i3S, Universidade do Porto, Portugal.
| | - Francisco Cruz
- Translational NeuroUrology, IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Portugal; Instituto de Investigação e Inovação em Saúde - i3S, Universidade do Porto, Portugal; Department of Urology, Hospital de S. João, Porto, Portugal.
| | - Célia Duarte Cruz
- Department of Experimental Biology, Faculty of Medicine of Porto, University of Porto, Portugal; Translational NeuroUrology, IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Portugal; Instituto de Investigação e Inovação em Saúde - i3S, Universidade do Porto, Portugal.
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8
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Detloff MR, Quiros-Molina D, Javia AS, Daggubati L, Nehlsen AD, Naqvi A, Ninan V, Vannix KN, McMullen MK, Amin S, Ganzer PD, Houlé JD. Delayed Exercise Is Ineffective at Reversing Aberrant Nociceptive Afferent Plasticity or Neuropathic Pain After Spinal Cord Injury in Rats. Neurorehabil Neural Repair 2015; 30:685-700. [PMID: 26671215 DOI: 10.1177/1545968315619698] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Neuropathic pain is a debilitating consequence of spinal cord injury (SCI) that correlates with sensory fiber sprouting. Recent data indicate that exercise initiated early after SCI prevents the development of allodynia and modulated nociceptive afferent plasticity. This study determined if delaying exercise intervention until pain is detected would similarly ameliorate established SCI-induced pain. Adult, female Sprague-Dawley rats with a C5 unilateral contusion were separated into SCI allodynic and SCI non-allodynic cohorts at 14 or 28 days postinjury when half of each group began exercising on automated running wheels. Allodynia, assessed by von Frey testing, was not ameliorated by exercise. Furthermore, rats that began exercise with no allodynia developed paw hypersensitivity within 2 weeks. At the initiation of exercise, the SCI Allodynia group displayed marked overlap of peptidergic and non-peptidergic nociceptive afferents in the C7 and L5 dorsal horn, while the SCI No Allodynia group had scant overlap. At the end of 5 weeks of exercise both the SCI Allodynia and SCI No Allodynia groups had extensive overlap of the 2 c-fiber types. Our findings show that exercise therapy initiated at early stages of allodynia is ineffective at attenuating neuropathic pain, but rather that it induces allodynia-aberrant afferent plasticity in previously pain-free rats. These data, combined with our previous results, suggest that there is a critical therapeutic window when exercise therapy may be effective at treating SCI-induced allodynia and that there are postinjury periods when exercise can be deleterious.
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Affiliation(s)
| | | | - Amy S Javia
- Drexel University College of Medicine, Philadelphia, PA, USA
| | | | | | - Ali Naqvi
- Drexel University College of Medicine, Philadelphia, PA, USA
| | - Vinu Ninan
- Drexel University College of Medicine, Philadelphia, PA, USA
| | | | | | - Sheena Amin
- Drexel University College of Medicine, Philadelphia, PA, USA
| | | | - John D Houlé
- Drexel University College of Medicine, Philadelphia, PA, USA
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9
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Petruska JC, Hubscher CH, Rabchevsky AG. Challenges and opportunities of sensory plasticity after SCI. Front Physiol 2013; 4:231. [PMID: 23986722 PMCID: PMC3753431 DOI: 10.3389/fphys.2013.00231] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2013] [Accepted: 08/07/2013] [Indexed: 12/30/2022] Open
Affiliation(s)
- Jeffrey C Petruska
- Department of Anatomical Sciences and Neurobiology, Kentucky Spinal Cord Injury Research Center, University of Louisville Louisville, KY, USA
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10
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Hougland MT, Harrison BJ, Magnuson DSK, Rouchka EC, Petruska JC. The Transcriptional Response of Neurotrophins and Their Tyrosine Kinase Receptors in Lumbar Sensorimotor Circuits to Spinal Cord Contusion is Affected by Injury Severity and Survival Time. Front Physiol 2013; 3:478. [PMID: 23316162 PMCID: PMC3540763 DOI: 10.3389/fphys.2012.00478] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2012] [Accepted: 12/07/2012] [Indexed: 01/19/2023] Open
Abstract
Traumatic spinal cord injury (SCI) results in changes to the anatomical, neurochemical, and physiological properties of cells in the central and peripheral nervous system. Neurotrophins, acting by binding to their cognate Trk receptors on target cell membranes, contribute to modulation of anatomical, neurochemical, and physiological properties of neurons in sensorimotor circuits in both the intact and injured spinal cord. Neurotrophin signaling is associated with many post-SCI changes including maladaptive plasticity leading to pain and autonomic dysreflexia, but also therapeutic approaches such as training-induced locomotor improvement. Here we characterize expression of mRNA for neurotrophins and Trk receptors in lumbar dorsal root ganglia (DRG) and spinal cord after two different severities of mid-thoracic injury and at 6 and 12 weeks post-SCI. There was complex regulation that differed with tissue, injury severity, and survival time, including reversals of regulation between 6 and 12 weeks, and the data suggest that natural regulation of neurotrophins in the spinal cord may continue for months after birth. Our assessments determined that a coordination of gene expression emerged at the 12-week post-SCI time point and bioinformatic analyses address possible mechanisms. These data can inform studies meant to determine the role of the neurotrophin signaling system in post-SCI function and plasticity, and studies using this signaling system as a therapeutic approach.
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Affiliation(s)
- M Tyler Hougland
- Department of Anatomical Sciences and Neurobiology, University of Louisville Louisville, KY, USA ; Laboratory of Neural Physiology and Plasticity, Kentucky Spinal Cord Injury Research Center, Department of Neurological Surgery Louisville, KY, USA
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11
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Abstract
SUMMARY Low back and leg pain can arise for a variety reasons, including epidural scarring caused by post lumbar surgery syndrome, infection or bleeding. Treatment options for low back and/or leg pain caused by epidural scarring include conservative approaches, such as physical therapy and medication management, and procedures, such as epidural steroid injections. Despite appropriate treatment, pain can persist in these patients. Surgery is often not an option for patients whose pain is caused by scarring. Percutaneous adhesiolysis is a minimally invasive technique, which is effective in treating refractory low back and leg pain arising from epidural scarring. It involves the use of a spring-wound, shear-resistant catheter, ideally placed in the ventrolateral aspect of the epidural space for the lysis of adhesions, allowing medications to reach the involved nerve and removing compression of the nerve. After mechanical lysis of adhesions, relatively large volumes of local anesthetic, saline, steroid and radiopaque contrast material are injected. Either hypertonic or normal saline may be used, along with hyaluronidase. After the procedure, the patient should perform exercises to stretch the nerve roots. While this has been studied as a caudal procedure, thoracic and cervical procedures have also been described, using both transforaminal and interlaminar approaches. With trained practitioners, complications are minimal. The effectiveness of the procedure has been documented by high-quality randomized controlled trials and observational studies for both postlumbar surgery syndrome and spinal stenosis.
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Walters ET. Nociceptors as chronic drivers of pain and hyperreflexia after spinal cord injury: an adaptive-maladaptive hyperfunctional state hypothesis. Front Physiol 2012; 3:309. [PMID: 22934060 PMCID: PMC3429080 DOI: 10.3389/fphys.2012.00309] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2012] [Accepted: 07/13/2012] [Indexed: 11/13/2022] Open
Abstract
Spinal cord injury (SCI) causes chronic peripheral sensitization of nociceptors and persistent generation of spontaneous action potentials (SA) in peripheral branches and the somata of hyperexcitable nociceptors within dorsal root ganglia (DRG). Here it is proposed that SCI triggers in numerous nociceptors a persistent hyperfunctional state (peripheral, synaptic, and somal) that originally evolved as an adaptive response to compensate for loss of sensory terminals after severe but survivable peripheral injury. In this hypothesis, nociceptor somata monitor the status of their own receptive field and the rest of the body by integrating signals received by their peripheral and central branches and the soma itself. A nociceptor switches into a potentially permanent hyperfunctional state when central neural, glial, and inflammatory signal combinations are detected that indicate extensive peripheral injury. Similar signal combinations are produced by SCI and disseminated widely to uninjured as well as injured nociceptors. This paper focuses on the uninjured nociceptors that are altered by SCI. Enhanced activity generated in below-level nociceptors promotes below-level central sensitization, somatic and autonomic hyperreflexia, and visceral dysfunction. If sufficient ascending fibers survive, enhanced activity in below-level nociceptors contributes to below-level pain. Nociceptor activity generated above the injury level contributes to at- and above-level sensitization and pain (evoked and spontaneous). Thus, SCI triggers a potent nociceptor state that may have been adaptive (from an evolutionary perspective) after severe peripheral injury but is maladaptive after SCI. Evidence that hyperfunctional nociceptors make large contributions to behavioral hypersensitivity after SCI suggests that nociceptor-specific ion channels required for nociceptor SA and hypersensitivity offer promising targets for treating chronic pain and hyperreflexia after SCI.
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Affiliation(s)
- Edgar T Walters
- Department of Integrative Biology and Pharmacology, University of Texas Medical School at Houston Houston, TX, USA
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13
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Hunt D, Raivich G, Anderson PN. Activating transcription factor 3 and the nervous system. Front Mol Neurosci 2012; 5:7. [PMID: 22347845 PMCID: PMC3278981 DOI: 10.3389/fnmol.2012.00007] [Citation(s) in RCA: 109] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2011] [Accepted: 01/20/2012] [Indexed: 12/18/2022] Open
Abstract
Activating transcription factor 3 (ATF3) belongs to the ATF/cyclic AMP responsive element binding family of transcription factors and is often described as an adaptive response gene whose activity is usually regulated by stressful stimuli. Although expressed in a number of splice variants and generally recognized as a transcriptional repressor, ATF3 has the ability to interact with a number of other transcription factors including c-Jun to form complexes which not only repress, but can also activate various genes. ATF3 expression is modulated mainly at the transcriptional level and has markedly different effects in different types of cell. The levels of ATF3 mRNA and protein are normally very low in neurons and glia but their expression is rapidly upregulated in response to injury. ATF3 expression in neurons is closely linked to their survival and the regeneration of their axons following axotomy, and that in peripheral nerves correlates with the generation of a Schwann cell phenotype that is conducive to axonal regeneration. ATF3 is also induced by Toll-like receptor (TLR) ligands but acts as a negative regulator of TLR signaling, suppressing the innate immune response which is involved in immuno-surveillance and can enhance or reduce the survival of injured neurons and promote the regeneration of their axons.
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Affiliation(s)
- David Hunt
- Medical Education Centre, Newham University Hospital London, UK
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14
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Huang W, Begum R, Barber T, Ibba V, Tee N, Hussain M, Arastoo M, Yang Q, Robson L, Lesage S, Gheysens T, Skaer NJ, Knight D, Priestley J. Regenerative potential of silk conduits in repair of peripheral nerve injury in adult rats. Biomaterials 2012; 33:59-71. [DOI: 10.1016/j.biomaterials.2011.09.030] [Citation(s) in RCA: 94] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2011] [Accepted: 09/13/2011] [Indexed: 01/03/2023]
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15
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Lindå H, Sköld MK, Ochsmann T. Activating transcription factor 3, a useful marker for regenerative response after nerve root injury. Front Neurol 2011; 2:30. [PMID: 21629765 PMCID: PMC3099310 DOI: 10.3389/fneur.2011.00030] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2011] [Accepted: 05/04/2011] [Indexed: 11/22/2022] Open
Abstract
Activating transcription factor 3 (ATF3) is induced in various tissues in response to stress. In this experiment, ATF3 expression was studied in adult rats subjected either to a dorsal or ventral root avulsion (VRA; L4-6), or sciatic nerve transection (SNT). Post-operative survival times varied between 1.5 h and 3 weeks. In additional experiments an avulsed ventral root was directly replanted to the spinal cord. Dorsal root ganglias (DRGs) from humans exposed to traumatic dorsal root avulsions were also examined. After SNT ATF3 immunoreactivity (ATF3 IR) was detected in a few DRG neurons already 6 h after the lesion. After 24 h the number had clearly increased and still at 3 weeks DRG neurons remained labeled. In the ventral horn, ATF3 IR in motoneurons (MN) was first detected 24 h after the SNT, and still 3 weeks post-operatively lesioned MN showed ATF3 labeling. After a VRA many spinal MN showed ATF3 IR already after 3 h, and after 6 h all MN were labeled. At 3 weeks a majority of the lesioned MN had died, but all the remaining ones were labeled. When an avulsed ventral root was directly replanted, MN survived and were still labeled at 5 weeks. In DRG, a few neurons were labeled already at 1.5 h after a dorsal root avulsion. At 24 h the number had increased but still only a minority of the neurons were labeled. At 3 days the number of labeled neurons was reduced, and a further reduction was at hand at 7 days and 3 weeks. In parallel, in humans, 3 days after a traumatic dorsal root avulsion, only a few DRG neurons showed ATF3 IR. At 6 weeks no labeled neurons could be detected. These facts imply that ATF3 response to axotomy involves a distance-dependent mechanism. ATF3 also appears to be a useful and reliable neuronal marker of nerve lesions even in humans. In addition, ATF3 up-regulation in both motor and sensory neurons seems to be linked to regenerative competence.
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Affiliation(s)
- Hans Lindå
- Department of Neuroscience, Karolinska Institutet Stockholm, Sweden
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16
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Peeraer E, Van Lutsenborg A, Verheyen A, De Jongh R, Nuydens R, Meert TF. Pharmacological evaluation of rat dorsal root ganglion neurons as an in vitro model for diabetic neuropathy. J Pain Res 2011; 4:55-65. [PMID: 21559351 PMCID: PMC3085264 DOI: 10.2147/jpr.s15452] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2011] [Indexed: 01/29/2023] Open
Abstract
BACKGROUND Diabetic neuropathy is a complication of diabetes mellitus that develops in about 50% of people with diabetes. Despite its widespread occurrence and devastating effects, this complication is still not fully understood, and there is no treatment available to prevent its development. METHODS In this study, immunocytochemistry for activating transcription factor 3, a marker for cell injury, was used to investigate the stress response in dorsal root ganglion neurons in both in vitro and ex vivo models of diabetic neuropathy. RESULTS Our findings showed increased activating transcription factor 3 expression in hyperglycemic culture conditions and in dorsal root ganglion neurons isolated from diabetic rats. Glial cell line-derived neurotrophic factor, a substance with known neuroprotective properties, was able to reduce diabetes mellitus-induced neuronal stress in vitro, while gabapentin and carbamazepine, currently used to treat neuropathic pain, showed only limited effects. CONCLUSION Growth factors may have a therapeutic benefit as neurotrophic agents in the treatment of diabetic peripheral neuropathy, but gabapentin and carbamazepine have no direct protective effect on sensory neurons. This research also indicates that immunocytochemistry for activating transcription factor 3 is a valuable tool for evaluation of pharmacological substances in dorsal root ganglion cultures.
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Affiliation(s)
- Eve Peeraer
- Johnson & Johnson Pharmaceutical Research and Development, Beerse, Belgium
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17
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Chronic spontaneous activity generated in the somata of primary nociceptors is associated with pain-related behavior after spinal cord injury. J Neurosci 2010; 30:14870-82. [PMID: 21048146 DOI: 10.1523/jneurosci.2428-10.2010] [Citation(s) in RCA: 111] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Mechanisms underlying chronic pain that develops after spinal cord injury (SCI) are incompletely understood. Most research on SCI pain mechanisms has focused on neuronal alterations within pain pathways at spinal and supraspinal levels associated with inflammation and glial activation. These events might also impact central processes of primary sensory neurons, triggering in nociceptors a hyperexcitable state and spontaneous activity (SA) that drive behavioral hypersensitivity and pain. SCI can sensitize peripheral fibers of nociceptors and promote peripheral SA, but whether these effects are driven by extrinsic alterations in surrounding tissue or are intrinsic to the nociceptor, and whether similar SA occurs in nociceptors in vivo are unknown. We show that small DRG neurons from rats (Rattus norvegicus) receiving thoracic spinal injury 3 d to 8 months earlier and recorded 1 d after dissociation exhibit an elevated incidence of SA coupled with soma hyperexcitability compared with untreated and sham-treated groups. SA incidence was greatest in lumbar DRG neurons (57%) and least in cervical neurons (28%), and failed to decline over 8 months. Many sampled SA neurons were capsaicin sensitive and/or bound the nociceptive marker, isolectin B4. This intrinsic SA state was correlated with increased behavioral responsiveness to mechanical and thermal stimulation of sites below and above the injury level. Recordings from C- and Aδ-fibers revealed SCI-induced SA generated in or near the somata of the neurons in vivo. SCI promotes the entry of primary nociceptors into a chronic hyperexcitable-SA state that may provide a useful therapeutic target in some forms of persistent pain.
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18
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Malaspina A, Ngoh SFA, Ward RE, Hall JCE, Tai FWD, Yip PK, Jones C, Jokic N, Averill SA, Michael-Titus AT, Priestley JV. Activation transcription factor-3 activation and the development of spinal cord degeneration in a rat model of amyotrophic lateral sclerosis. Neuroscience 2010; 169:812-27. [PMID: 20470869 DOI: 10.1016/j.neuroscience.2010.04.053] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2010] [Accepted: 04/23/2010] [Indexed: 12/17/2022]
Abstract
It has been reported that an early activation of glial fibrillary acid protein (GFAP) in astroglial cells occurs simultaneously in peripheral nerves and spinal cord from the G93A SOD1 mouse model of amyotrophic lateral sclerosis (ALS), an invariably fatal neurodegenerative disorder. In ALS, the contribute to the pathological process of different cell types varies according to the disease stage, with a florid immune response in spinal cord at end stage disease. In this study, we have mapped in different anatomical sites the process of disease-induced functional perturbation from a pre-symptomatic stage using a marker of cellular distress expressed in neurons and glial cells, the activating transcription factor 3 (ATF-3), and applied large-scale gene expression analysis to define the pattern or transcriptional changes occurring in spinal cord from the G93A SOD1 rat model of ALS in parallel with ATF-3 neuronal activation. From the disease onset onward, transgenic lumbar spinal cord displayed ATF-3 transcriptional regulation and motor cells immunostaining in association with the over-expression of genes promoting cell growth, the functional integrity of cell organelles and involved in the modulation of immune responses. While spinal cord from the pre-symptomatic rat showed no detectable ATF-3 transcriptional regulation, ATF-3 activation was appreciated in large size neurofilament-rich, small size non-peptidergic and parvalbumin-positive neurons within the dorsal root ganglia (DRG), and in ventral roots Schwann cells alongside macrophages infiltration. This pattern of peripheral ATF-3 activation remained detectable throughout the disease process. In the G93A SOD1 rat model of ALS, signs of roots and nerves subtle distress preceded overt clinical-pathological changes, involving both glial cells and neurons that function as receptors of peripheral sensory stimuli from the muscle. In addition, factors previously described to be linked to ATF-3 activation under various experimental conditions of stress, become switched on in spinal cord from the end-stage transgenic rat model of ALS.
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Affiliation(s)
- A Malaspina
- Centre for Neuroscience and Trauma, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, Blizard Institute, 4 Newark Street, London E1 2AT, UK.
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19
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Robson LG, Dyall SC, Sidloff D, Michael-Titus AT. Omega-3 polyunsaturated fatty acids increase the neurite outgrowth of rat sensory neurones throughout development and in aged animals. Neurobiol Aging 2010; 31:678-87. [PMID: 18620782 DOI: 10.1016/j.neurobiolaging.2008.05.027] [Citation(s) in RCA: 101] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2008] [Revised: 05/07/2008] [Accepted: 05/28/2008] [Indexed: 01/25/2023]
Abstract
Polyunsaturated fatty acids (PUFA) of the omega-3 series and omega-6 series modulate neurite outgrowth in immature neurones. However, it has not been determined if their neurotrophic effects persist in adult and aged tissue. We prepared cultures of primary sensory neurones from male and female rat dorsal root ganglia (DRG), isolated at different ages: post-natal day 3 (P3) and day 9 (P9), adult (2-4 months) and aged (18-20 months). Cultures were incubated with the omega-6 PUFA arachidonic acid (AA) and the omega-3 PUFA eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), at 0.8, 4, 8 and 40muM. PUFA increased neurite outgrowth throughout the developmental stages studied. The effects of omega-3 PUFA, in particular DHA, were still prominent in aged tissue. The amplitude of the effects was comparable to that of nerve growth factor (NGF; 50ng/ml) and all-trans-retinoic acid (ATRA; 0.1muM). The effects of PUFA were similar in cells positive or negative for the N52 neurofilament marker. Our results show that omega-3 PUFA have a marked neurite-promoting potential in neurones from adult and aged animals.
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Affiliation(s)
- Lesley G Robson
- Neuroscience Centre, Institute of Cell and Molecular Science, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, 4 Newark Street, Whitechapel, London E1 2AT, United Kingdom
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20
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Carlton SM, Du J, Tan HY, Nesic O, Hargett GL, Bopp AC, Yamani A, Lin Q, Willis WD, Hulsebosch CE. Peripheral and central sensitization in remote spinal cord regions contribute to central neuropathic pain after spinal cord injury. Pain 2009; 147:265-76. [PMID: 19853381 DOI: 10.1016/j.pain.2009.09.030] [Citation(s) in RCA: 175] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2009] [Revised: 09/22/2009] [Accepted: 09/23/2009] [Indexed: 12/13/2022]
Abstract
Central neuropathic pain (CNP) developing after spinal cord injury (SCI) is described by the region affected: above-level, at-level and below-level pain occurs in dermatomes rostral, at/near, or below the SCI level, respectively. People with SCI and rodent models of SCI develop above-level pain characterized by mechanical allodynia and thermal hyperalgesia. Mechanisms underlying this pain are unknown and the goals of this study were to elucidate components contributing to the generation of above-level CNP. Following a thoracic (T10) contusion, forelimb nociceptors had enhanced spontaneous activity and were sensitized to mechanical and thermal stimulation of the forepaws 35 days post-injury. Cervical dorsal horn neurons showed enhanced responses to non-noxious and noxious mechanical stimulation as well as thermal stimulation of receptive fields. Immunostaining dorsal root ganglion (DRG) cells and cord segments with activating transcription factor 3 (ATF3, a marker for neuronal injury) ruled out neuronal damage as a cause for above-level sensitization since few C8 DRG cells expressed AFT3 and cervical cord segments had few to no ATF3-labeled cells. Finally, activated microglia and astrocytes were present in thoracic and cervical cord at 35 days post-SCI, indicating a rostral spread of glial activation from the injury site. Based on these data, we conclude that peripheral and central sensitization as well as reactive glia in the uninjured cervical cord contribute to CNP. We hypothesize that reactive glia in the cervical cord release pro-inflammatory substances which drive chronic CNP. Thus a complex cascade of events spanning many cord segments underlies above-level CNP.
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Affiliation(s)
- Susan M Carlton
- Department of Neuroscience and Cell Biology, University of Texas Medical Branch, Galveston, TX 77555-1069, USA.
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21
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Chen HM, Wang L, D'Mello SR. A chemical compound commonly used to inhibit PKR, {8-(imidazol-4-ylmethylene)-6H-azolidino[5,4-g] benzothiazol-7-one}, protects neurons by inhibiting cyclin-dependent kinase. Eur J Neurosci 2009; 28:2003-16. [PMID: 19046382 DOI: 10.1111/j.1460-9568.2008.06491.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Activation of the double-stranded RNA-dependent protein kinase (PKR) has been implicated in the pathogenesis of several neurodegenerative diseases. We find that a compound widely used as a pharmacological inhibitor of this enzyme, referred to as PKR inhibitor (PKRi), {8-(imidazol-4-ylmethylene)-6H-azolidino[5,4-g]benzothiazol-7-one}, protects against the death of cultured cerebellar granule and cortical neurons. PKRi also prevents striatal neurodegeneration and improves behavioral outcomes in a chemically induced mouse model of Huntington's disease. Surprisingly, PKRi fails to block the phosphorylation of eIF2alpha, a downstream target of PKR, and does not reduce the autophosphorylation of PKR enzyme immunoprecipitated from neurons. Furthermore, neurons lacking PKR are fully protected from apoptosis by PKRi, demonstrating that neuroprotection by this compound is not mediated by PKR inhibition. Using in vitro kinase assays we investigated whether PKRi affects any other protein kinase. These analyses demonstrated that PKRi has no major inhibitory effect on pro-apoptotic kinases such as the c-Jun N-terminal kinases, the p38 MAP kinases and the death-associated protein kinases, or on other kinases including c-Raf, MEK1, MKK6 and MKK7. PKRi does, however, inhibit the activity of certain cyclin-dependent kinases (CDKs), including CDK1, CDK2 and CDK5 both in vitro and in low potassium-treated neurons. Consistent with its inhibitory action on mitotic CDKs, the treatment of HT-22 and HEK293T cell lines with PKRi sharply reduces the rate of cell cycle progression. Taken together with the established role of CDK activation in the promotion of neurodegeneration, our results suggest that PKRi exerts its neuroprotective action by inhibiting CDK.
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Affiliation(s)
- Hsin-Mei Chen
- Department of Molecular and Cell Biology, University of Texas at Dallas, Richardson, TX 75083, USA
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22
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Zhou LH, Han S, Xie YY, Wang LL, Yao ZB. Differences in c-jun and nNOS expression levels in motoneurons following different kinds of axonal injury in adult rats. ACTA ACUST UNITED AC 2009; 36:213-27. [PMID: 19238548 DOI: 10.1007/s11068-009-9040-4] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2008] [Revised: 12/13/2008] [Accepted: 12/18/2008] [Indexed: 11/28/2022]
Abstract
In the peripheral nervous system (PNS), root avulsion causes motoneuron degeneration, but the majority of motoneurons can survive axotomy. In order to study the mechanism of motoneuron degeneration, we compared the expression patterns of c-jun and neuronal nitric oxide synthase (nNOS), the well-known molecular players in PNS regeneration and degeneration, among adult rats having undergone axotomy (Ax), avulsion (Av), or pre-axotomy plus secondary avulsion (Ax + Av) of the brachial plexus. Our results showed that the highest and longest-lasting c-jun activation occurred in Ax, which was much stronger than those in Av and Ax + Av. The time course and intensity of c-jun expression in Ax + Av were similar to those in Av except on day 1, while the pre-axotomy condition resulted in a transient up-regulation of c-jun to a level comparable to that in Ax. Axotomy alone did not induce nNOS expression in motoneurons. Pre-axotomy left-shifted the time course of nNOS induction in Ax + Av compared to that in Av. Motoneuron loss was not evident in Ax, while it was 70% in Av and more than 85% in Ax + Av at 8 weeks postinjury. The survival of motoneurons was positively correlated with c-jun induction, but not with nNOS expression in motoneurons. Moreover, c-jun induction was negatively correlated with nNOS induction in injured motoneurons. Our results indicate that functional crosstalk between c-jun and nNOS might play an important role in avulsion-induced motoneuron degeneration, while c-jun might act as a prerequisite survival factor and nNOS might act as a predictor for the onset of motoneuron degeneration.
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Affiliation(s)
- Li-Hua Zhou
- Department of Anatomy, Zhong Shan School of Medicine, Sun Yat-sen University, Guangzhou 510080, PR China
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23
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Phillips JP, George KJ, Kyriacou PA, Langford RM. Investigation of photoplethysmographic changes using a static compression model of spinal cord injury. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2009; 2009:1493-1496. [PMID: 19964532 DOI: 10.1109/iembs.2009.5334166] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Little is known about cell death in spinal cord tissue following compression injury, despite compression being a key component of spinal injuries. Currently models are used to mimic compression injury in animals and the effects of the compression evaluated by observing the extent and duration of recovery of normal motor function in the days and weeks following the injury. A fiber-optic photoplethysmography system was used to investigate whether pulsation of the small arteries in the spinal cord occurred before, during and after compressive loads were applied to the tissue. It was found that the signal amplitudes were reduced and this reduction persisted for at least five minutes after the compression ceased. It is hoped that results from this preliminary study may improve knowledge of the mechanism of spinal cord injury.
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Affiliation(s)
- Justin P Phillips
- School of Engineering and Mathematical Sciences, City University, London, EC1V 0HB, UK.
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24
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Chen HM, Wang L, D’Mello SR. Inhibition of ATF-3 expression by B-Raf mediates the neuroprotective action of GW5074. J Neurochem 2008; 105:1300-12. [DOI: 10.1111/j.1471-4159.2008.05226.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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25
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Mei Y, Yuan Z, Song B, Li D, Ma C, Hu C, Ching YP, Li M. Activating transcription factor 3 up-regulated by c-Jun NH(2)-terminal kinase/c-Jun contributes to apoptosis induced by potassium deprivation in cerebellar granule neurons. Neuroscience 2007; 151:771-9. [PMID: 18178318 DOI: 10.1016/j.neuroscience.2007.10.057] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2007] [Revised: 10/04/2007] [Accepted: 11/28/2007] [Indexed: 11/30/2022]
Abstract
Cerebellar granule neurons (CGNs) depend on potassium depolarization for survival and undergo apoptosis when deprived of depolarizing concentration of potassium. Activating transcription factor 3 (ATF3), a stress-inducible protein, belongs to the ATF/CREB family of transcription factors family and is involved in cell growth and apoptosis. However, the role of ATF3 in neuronal apoptosis remains unknown. Here, we showed that ATF3 was up-regulated under potassium deprivation in CGNs, and this induction was preceded by a rapid and sustained activation of c-Jun NH(2)-terminal kinase/c-Jun signaling pathway, which plays a fundamental role in neuronal apoptosis. Furthermore, ATF3 up-regulation was abolished by inhibition of JNK or knockdown of c-Jun. Finally, knockdown of ATF3 by RNA interference protected CGNs from potassium deprivation-induced apoptosis. Taken together, our results indicate that ATF3 is a downstream target of JNK/c-Jun pathway and contributes to apoptosis induced by potassium deprivation in rat CGNs.
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Affiliation(s)
- Y Mei
- Department of Pharmacology, Zhongshan School of Medicine, Sun Yat-sen University, 74 Zhongshan Road II, Guangzhou 510080, China
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26
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Huang WL, George KJ, Ibba V, Liu MC, Averill S, Quartu M, Hamlyn PJ, Priestley JV. The characteristics of neuronal injury in a static compression model of spinal cord injury in adult rats. Eur J Neurosci 2007; 25:362-72. [PMID: 17284176 DOI: 10.1111/j.1460-9568.2006.05284.x] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Studies of spinal cord injury using contusion (impact) injury paradigms have shown that neuronal death is an acute event that is largely over within 24 h. However, much less is known about cell death following compression injury, despite compression being a key component of natural spinal injuries. We have therefore used neuronal nuclei (NeuN) immunostaining to examine the spatiotemporal pattern of neuronal loss after static compression injury in adult rats. 3D reconstruction was used to reveal the full effect of the injury. Neuronal loss at the injury epicentre, assessed by NeuN immunostaining, amounted to 44% at 1 day but increased to 73% at 3 days and 81% at 1 month. Neuronal loss was also seen 5 mm rostral and caudal to the epicentre, but was not significant until 3 days. NeuN loss was greatest in the ventral horns and in the intermediate grey matter, with the lateral dorsal horns relatively spared. Cystic cavities formed after injury, but were not evident until 4 weeks and were small in size. In contrast to the slow profile of neuronal loss, the compression injury also evoked a transient expression of activating transcription factor-3 (ATF3) and activated c-Jun in neurons. ATF3 expression peaked at 3 days and declined at 7 days. Our spatiotemporal analysis of compression injury shows that neuronal loss is much more protracted than in contusion injury, and highlights the potential for neuroprotective strategies. This study is also the first indication of ATF3 involvement in spinal cord injury.
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Affiliation(s)
- W L Huang
- Neuroscience Centre, Institute of Cell and Molecular Science, Queen Mary University of London, UK.
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King VR, Huang WL, Dyall SC, Curran OE, Priestley JV, Michael-Titus AT. Omega-3 fatty acids improve recovery, whereas omega-6 fatty acids worsen outcome, after spinal cord injury in the adult rat. J Neurosci 2006; 26:4672-80. [PMID: 16641248 PMCID: PMC6674074 DOI: 10.1523/jneurosci.5539-05.2006] [Citation(s) in RCA: 159] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Spinal cord injury (SCI) is a cause of major neurological disability, and no satisfactory treatment is currently available. Evidence suggests that polyunsaturated fatty acids (PUFAs) could target some of the pathological mechanisms that underlie damage after SCI. We examined the effects of treatment with PUFAs after lateral spinal cord hemisection in the rat. The omega-3 PUFAs alpha-linolenic acid and docosahexaenoic acid (DHA) injected 30 min after injury induced significantly improved locomotor performance and neuroprotection, including decreased lesion size and apoptosis and increased neuronal and oligodendrocyte survival. Evidence showing a decrease in RNA/DNA oxidation suggests that the neuroprotective effect of omega-3 PUFAs involved a significant antioxidant function. In contrast, animals treated with arachidonic acid, an omega-6 PUFA, had a significantly worse outcome than controls. We confirmed the neuroprotective effect of omega-3 PUFAs by examining the effects of DHA treatment after spinal cord compression injury. Results indicated that DHA administered 30 min after spinal cord compression not only greatly increased survival of neurons but also resulted in significantly better locomotor performance for up to 6 weeks after injury. This report shows a striking difference in efficacy between the effects of treatment with omega-3 and omega-6 PUFAs on the outcome of SCI, with omega-3 PUFAs being neuroprotective and omega-6 PUFAs having a damaging effect. Given the proven clinical safety of omega-3 PUFAs, our observations show that these PUFAs have significant therapeutic potential in SCI. In contrast, the use of preparations enriched in omega-6 PUFAs after injury could worsen outcome after SCI.
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Affiliation(s)
- Von R King
- Institute of Cell and Molecular Science, St. Bartholomew's and the Royal London School of Medicine and Dentistry, Queen Mary University of London, London E1 2AT, United Kingdom.
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