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Verge VMK, Tokarska N, Naniong JM. Unraveling the potential of acute intermittent hypoxia as a strategy for inducing robust repair in multiple sclerosis. Neural Regen Res 2024; 19:2339-2340. [PMID: 38526264 DOI: 10.4103/nrr.nrr-d-23-01663] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2023] [Accepted: 01/08/2024] [Indexed: 03/26/2024] Open
Affiliation(s)
- Valerie M K Verge
- Department of Anatomy, Physiology and Pharmacology, University of Saskatchewan, Saskatoon, SK, Canada (Verge VMK, Tokarska N, Naniong JM)
- Cameco MS Neuroscience Research Center, University of Saskatchewan, Saskatoon, SK, Canada (Verge VMK, Tokarska N, Naniong JM)
| | - Nataliya Tokarska
- Department of Anatomy, Physiology and Pharmacology, University of Saskatchewan, Saskatoon, SK, Canada (Verge VMK, Tokarska N, Naniong JM)
- Cameco MS Neuroscience Research Center, University of Saskatchewan, Saskatoon, SK, Canada (Verge VMK, Tokarska N, Naniong JM)
| | - Justin M Naniong
- Department of Anatomy, Physiology and Pharmacology, University of Saskatchewan, Saskatoon, SK, Canada (Verge VMK, Tokarska N, Naniong JM)
- Cameco MS Neuroscience Research Center, University of Saskatchewan, Saskatoon, SK, Canada (Verge VMK, Tokarska N, Naniong JM)
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2
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Krishnan A, Verge VMK, Zochodne DW. Hallmarks of peripheral nerve injury and regeneration. Handb Clin Neurol 2024; 201:1-17. [PMID: 38697733 DOI: 10.1016/b978-0-323-90108-6.00014-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2024]
Abstract
Peripheral nerves are functional networks in the body. Disruption of these networks induces varied functional consequences depending on the types of nerves and organs affected. Despite the advances in microsurgical repair and understanding of nerve regeneration biology, restoring full functions after severe traumatic nerve injuries is still far from achieved. While a blunted growth response from axons and errors in axon guidance due to physical barriers may surface as the major hurdles in repairing nerves, critical additional cellular and molecular aspects challenge the orderly healing of injured nerves. Understanding the systematic reprogramming of injured nerves at the cellular and molecular levels, referred to here as "hallmarks of nerve injury regeneration," will offer better ideas. This chapter discusses the hallmarks of nerve injury and regeneration and critical points of failures in the natural healing process. Potential pharmacological and nonpharmacological intervention points for repairing nerves are also discussed.
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Affiliation(s)
- Anand Krishnan
- Department of Anatomy, Physiology, and Pharmacology, College of Medicine, University of Saskatchewan, Saskatoon, SK, Canada; Cameco MS Neuroscience Research Centre (CMSNRC), Saskatoon, SK, Canada.
| | - Valerie M K Verge
- Department of Anatomy, Physiology, and Pharmacology, College of Medicine, University of Saskatchewan, Saskatoon, SK, Canada; Cameco MS Neuroscience Research Centre (CMSNRC), Saskatoon, SK, Canada.
| | - Douglas W Zochodne
- Neuroscience and Mental Health Institute and Division of Neurology, Department of Medicine, University of Alberta, Edmonton, AB, Canada.
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3
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Tokarska N, Naniong JMA, Johnston JM, Salapa HE, Muir GD, Levin MC, Popescu BF, Verge VMK. Acute intermittent hypoxia alters disease course and promotes CNS repair including resolution of inflammation and remyelination in the experimental autoimmune encephalomyelitis model of MS. Glia 2023; 71:2045-2066. [PMID: 37132422 DOI: 10.1002/glia.24381] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Revised: 04/09/2023] [Accepted: 04/15/2023] [Indexed: 05/04/2023]
Abstract
Remyelination and neurodegeneration prevention mitigate disability in Multiple Sclerosis (MS). We have shown acute intermittent hypoxia (AIH) is a novel, non-invasive and effective therapy for peripheral nerve repair, including remyelination. Thus, we posited AIH would improve repair following CNS demyelination and address the paucity of MS repair treatments. AIH's capacity to enhance intrinsic repair, functional recovery and alter disease course in the experimental autoimmune encephalomyelitis (EAE) model of MS was assessed. EAE was induced by MOG35-55 immunization in C57BL/6 female mice. EAE mice received either AIH (10 cycles-5 min 11% oxygen alternating with 5 min 21% oxygen) or Normoxia (control; 21% oxygen for same duration) once daily for 7d beginning at near peak EAE disease score of 2.5. Mice were followed post-treatment for an additional 7d before assessing histopathology or 14d to examine maintenance of AIH effects. Alterations in histopathological correlates of multiple repair indices were analyzed quantitatively in focally demyelinated ventral lumbar spinal cord areas to assess AIH impacts. AIH begun at near peak disease significantly improved daily clinical scores/functional recovery and associated histopathology relative to Normoxia controls and the former were maintained for at least 14d post-treatment. AIH enhanced correlates of myelination, axon protection and oligodendrocyte precursor cell recruitment to demyelinated areas. AIH also effected a dramatic reduction in inflammation, while polarizing remaining macrophages/microglia toward a pro-repair state. Collectively, this supports a role for AIH as a novel non-invasive therapy to enhance CNS repair and alter disease course following demyelination and holds promise as a neuroregenerative MS strategy.
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Affiliation(s)
- Nataliya Tokarska
- Department of Anatomy, Physiology and Pharmacology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
- Cameco MS Neuroscience Research Centre, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Justin M A Naniong
- Department of Anatomy, Physiology and Pharmacology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
- Cameco MS Neuroscience Research Centre, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Jayne M Johnston
- Department of Anatomy, Physiology and Pharmacology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
- Cameco MS Neuroscience Research Centre, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Hannah E Salapa
- Cameco MS Neuroscience Research Centre, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
- Office of the Saskatchewan Multiple Sclerosis Clinical Research Chair, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
- College of Medicine, Neurology Division, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Gillian D Muir
- Cameco MS Neuroscience Research Centre, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
- Department of Biomedical Sciences, WCVM, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Michael C Levin
- Cameco MS Neuroscience Research Centre, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
- Office of the Saskatchewan Multiple Sclerosis Clinical Research Chair, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
- College of Medicine, Neurology Division, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Bogdan F Popescu
- Department of Anatomy, Physiology and Pharmacology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
- Cameco MS Neuroscience Research Centre, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Valerie M K Verge
- Department of Anatomy, Physiology and Pharmacology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
- Cameco MS Neuroscience Research Centre, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
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4
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Ayanwuyi L, Tokarska N, McLean NA, Johnston JM, Verge VMK. Brief electrical nerve stimulation enhances intrinsic repair capacity of the focally demyelinated central nervous system. Neural Regen Res 2021; 17:1042-1050. [PMID: 34558531 PMCID: PMC8552867 DOI: 10.4103/1673-5374.324848] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Our lab has shown that brief electrical nerve stimulation (ES) has a dramatic impact on remyelination of lysophosphatidyl choline (LPC)-induced focally demyelinated rat peripheral nerves, while also inducing an axon-protective phenotype and shifting macrophages from a predominantly pro-inflammatory toward a pro-repair phenotype. Whether this same potential exists in the central nervous system is not known. Thus, for proof of principle studies, the peripheral nerve demyelination and ES model was adapted to the central nervous system, whereby a unilateral focal LPC-induced demyelination of the dorsal column at the lumbar enlargement where the sciatic nerve afferents enter was created, so that subsequent ipsilateral sciatic nerve ES results in increased neural activity in the demyelinated axons. Data reveal a robust focal demyelination at 7 days post-LPC injection. Delivery of 1-hour ES at 7 days post-LPC polarizes macrophages/microglia toward a pro-repair phenotype when examined at 14 days post-LPC; results in smaller LPC-associated regions of inflammation compared to non-stimulated controls; results in significantly more cells of the oligodendroglial lineage in the demyelinated region; elevates myelin basic protein levels; and shifts the paranodal protein Caspr along demyelinated axons to a more restricted distribution, consistent with reformation of the paranodes of the nodes of Ranvier. ES also significantly enhanced levels of phosphorylated neurofilaments detected in the zones of demyelination, which has been shown to confer axon protection. Collectively these findings support that strategies that increase neural activity, such as brief electrical stimulation, can be beneficial for promoting intrinsic repair following focal demyelinating insults in demyelinating diseases such as multiple sclerosis. All animal procedures performed were approved by the University of Saskatchewan's Animal Research Ethics Board (protocol# 20090087; last approval date: November 5, 2020).
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Affiliation(s)
- Lydia Ayanwuyi
- Department of Anatomy, Physiology and Pharmacology; Cameco MS Neuroscience Research Center, University of Saskatchewan, Saskatoon, SK, Canada
| | - Nataliya Tokarska
- Department of Anatomy, Physiology and Pharmacology; Cameco MS Neuroscience Research Center, University of Saskatchewan, Saskatoon, SK, Canada
| | - Nikki A McLean
- Department of Anatomy, Physiology and Pharmacology; Cameco MS Neuroscience Research Center, University of Saskatchewan, Saskatoon, SK, Canada
| | - Jayne M Johnston
- Department of Anatomy, Physiology and Pharmacology; Cameco MS Neuroscience Research Center, University of Saskatchewan, Saskatoon, SK, Canada
| | - Valerie M K Verge
- Department of Anatomy, Physiology and Pharmacology; Cameco MS Neuroscience Research Center, University of Saskatchewan, Saskatoon, SK, Canada
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Nadeau JR, Arnold BM, Johnston JM, Muir GD, Verge VMK. Acute intermittent hypoxia enhances regeneration of surgically repaired peripheral nerves in a manner akin to electrical stimulation. Exp Neurol 2021; 341:113671. [PMID: 33684407 DOI: 10.1016/j.expneurol.2021.113671] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2020] [Revised: 02/16/2021] [Accepted: 02/25/2021] [Indexed: 12/12/2022]
Abstract
The intrinsic repair response of injured peripheral neurons is enhanced by brief electrical stimulation (ES) at time of surgical repair, resulting in improved regeneration in rodents and humans. However, ES is invasive. Acute intermittent hypoxia (AIH) - breathing alternate cycles of regular air and air with ~50% normal oxygen levels (11% O2), considered mild hypoxia, is an emerging, promising non-invasive therapy that promotes motor function in spinal cord injured rats and humans. AIH can increase neural activity and under moderately severe hypoxic conditions improves repair of peripherally crushed nerves in mice. Thus, we posited an AIH paradigm similar to that used clinically for spinal cord injury, will improve surgically repaired peripheral nerves akin to ES, including an impact on regeneration-associated gene (RAG) expression-a predictor of growth states. Alterations in early RAG expression were examined in adult male Lewis rats that underwent tibial nerve coaptation repair with either 2 days AIH or normoxia control treatment begun on day 2 post-repair, or 1 h ES treatment (20 Hz) at time of repair. Three days post-repair, AIH or ES treatments effected significant and parallel elevated RAG expression relative to normoxia control at the level of injured sensory and motor neuron cell bodies and proximal axon front. These parallel impacts on RAG expression were coupled with significant improvements in later indices of regeneration, namely enhanced myelination and increased numbers of newly myelinated fibers detected 20 mm distal to the tibial nerve repair site or sensory and motor neurons retrogradely labeled 28 mm distal to the repair site, both at 25 days post nerve repair; and improved return of toe spread function 5-10 weeks post-repair. Collectively, AIH mirrors many beneficial effects of ES on peripheral nerve repair outcomes. This highlights its potential for clinical translation as a non-invasive means to effect improved regeneration of injured peripheral nerves.
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Affiliation(s)
- J R Nadeau
- Department of Anatomy, Physiology and Pharmacology, University of Saskatchewan, Saskatoon, SK S7N 5E5, Canada; Biomedical Sciences, WCVM, University of Saskatchewan, 52 Campus Drive, Saskatoon, SK S7N 5B4, Canada; Cameco MS Neuroscience Research Centre, University of Saskatchewan, Saskatoon, SK S7K 0M7, Canada
| | - B M Arnold
- Biomedical Sciences, WCVM, University of Saskatchewan, 52 Campus Drive, Saskatoon, SK S7N 5B4, Canada; Cameco MS Neuroscience Research Centre, University of Saskatchewan, Saskatoon, SK S7K 0M7, Canada
| | - J M Johnston
- Department of Anatomy, Physiology and Pharmacology, University of Saskatchewan, Saskatoon, SK S7N 5E5, Canada; Cameco MS Neuroscience Research Centre, University of Saskatchewan, Saskatoon, SK S7K 0M7, Canada
| | - G D Muir
- Biomedical Sciences, WCVM, University of Saskatchewan, 52 Campus Drive, Saskatoon, SK S7N 5B4, Canada; Cameco MS Neuroscience Research Centre, University of Saskatchewan, Saskatoon, SK S7K 0M7, Canada
| | - V M K Verge
- Department of Anatomy, Physiology and Pharmacology, University of Saskatchewan, Saskatoon, SK S7N 5E5, Canada; Cameco MS Neuroscience Research Centre, University of Saskatchewan, Saskatoon, SK S7K 0M7, Canada.
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Wang Z, Baharani A, Wei Z, Truong D, Bi X, Wang F, Li XM, Verge VMK, Zhang Y. Low field magnetic stimulation promotes myelin repair and cognitive recovery in chronic cuprizone mouse model. Clin Exp Pharmacol Physiol 2021; 48:1090-1102. [PMID: 33638234 DOI: 10.1111/1440-1681.13490] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Revised: 02/09/2021] [Accepted: 02/23/2021] [Indexed: 11/26/2022]
Abstract
BACKGROUND Multiple sclerosis (MS) is an inflammatory demyelinating disease featured with neuroinflammation, demyelination, and the loss of oligodendrocytes. Cognitive impairment and depression are common neuropsychiatric symptoms in MS that are poorly managed with the present interventions. OBJECTIVE This study aimed to investigate the effects of low field magnetic stimulation (LFMS), a novel non-invasive neuromodulation technology, on cognitive impairment and depressive symptoms associated with MS using a mouse model of demyelination. METHODS C57BL female mice were fed with a 0.2% cuprizone diet for 12 weeks to induce a chronic demyelinating model followed by 4 weeks of cuprizone withdrawal with either sham or LFMS treatment. RESULTS Improved cognition and depression-like behaviour and restored weight gain were observed in mice with LFMS treatment. Immunohistochemical and immunoblotting data showed enhanced myelin basic protein (MBP) and myelin oligodendrocyte glycoprotein expressions (MOG) in the prefrontal cortex of mice with LFMS treatment, supporting that myelin repair was promoted. LFMS also increased the protein expression of mature oligodendrocyte biomarker glutathione-S-transferase (GST-π). In addition, expression of TGF-β and associated receptors were elevated with LFMS treatment, implicating this pathway in the response. CONCLUSION Results from the present study revealed LFMS to have neuroprotective effects, suggesting that LFMS has potential therapeutic value for treating cognitive impairment and depression related to demyelination disorders.
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Affiliation(s)
- Zitong Wang
- Department of Psychiatry, College of Medicine, University of Saskatchewan, Saskatoon, SK, Canada.,Department of Psychiatry, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada
| | - Akanksha Baharani
- Department of Psychiatry, College of Medicine, University of Saskatchewan, Saskatoon, SK, Canada
| | - Zelan Wei
- College of Dentistry, University of Saskatchewan, Saskatoon, SK, Canada
| | - Davin Truong
- College of Dentistry, University of Saskatchewan, Saskatoon, SK, Canada
| | - Xiaoying Bi
- Department of Neurology, Shanghai Changhai Hospital, the Second Military Medical University, Shanghai, China
| | - Fei Wang
- Nanjing Brain Hospital, Nanjing Medical University, Nanjing, China
| | - Xin-Min Li
- Department of Psychiatry, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada
| | - Valerie M K Verge
- Department of Anatomy, Physiology and Pharmacology, College of Medicine, University of Saskatchewan, Saskatoon, SK, Canada.,Cameco MS Neuroscience Research Centre, College of Medicine, University of Saskatchewan, Saskatoon, SK, Canada
| | - Yanbo Zhang
- Department of Psychiatry, College of Medicine, University of Saskatchewan, Saskatoon, SK, Canada.,Cameco MS Neuroscience Research Centre, College of Medicine, University of Saskatchewan, Saskatoon, SK, Canada.,Department of Psychiatry, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada
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Hasmatali JCD, De Guzman J, Zhai R, Yang L, McLean NA, Hutchinson C, Johnston JM, Misra V, Verge VMK. Axotomy Induces Phasic Alterations in Luman/CREB3 Expression and Nuclear Localization in Injured and Contralateral Uninjured Sensory Neurons: Correlation With Intrinsic Axon Growth Capacity. J Neuropathol Exp Neurol 2020; 78:348-364. [PMID: 30863858 DOI: 10.1093/jnen/nlz008] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Luman/CREB3 is an important early retrograde axotomy signal regulating acute axon outgrowth in sensory neurons through the adaptive unfolded protein response. As the injury response is transcriptionally multiphasic, a spatiotemporal analysis of Luman/CREB3 localization in rat dorsal root ganglion (DRG) with unilateral L4-L6 spinal nerve injury was conducted to determine if Luman/CREB3 expression was similarly regulated. Biphasic alterations in Luman/CREB3 immunofluorescence and nuclear localization occurred in neurons ipsilateral to 1-hour, 1-day, 2-day, 4-day, and 1-week injury, with a largely parallel, but less avid response contralaterally. This biphasic response was not observed at the transcript level. To assess whether changes in neuronal Luman expression corresponded with an altered intrinsic capacity to grow an axon/neurite in vitro, injury-conditioned and contralateral uninjured DRG neurons underwent a 24-hour axon growth assay. Two-day injury-conditioned neurons exhibited maximal outgrowth capacity relative to naïve, declining at later injury-conditioned timepoints. Only neurons contralateral to 1-week injury exhibited significantly higher axon growth capacity than naïve. In conclusion, alterations in neuronal injury-associated Luman/CREB3 expression support that a multiphasic cell body response occurs and reveal a novel contralateral plasticity in axon growth capacity at 1-week post-injury. These adaptive responses have the potential to inform when repair or therapeutic intervention may be most effective.
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Affiliation(s)
- Jovan C D Hasmatali
- Department of Anatomy, Physiology and Pharmacology.,Cameco MS Neuroscience Research Center.,Department of Veterinary Microbiology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.,Department of Critical Care Medicine, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Jolly De Guzman
- Department of Anatomy, Physiology and Pharmacology.,Cameco MS Neuroscience Research Center
| | - Ruiling Zhai
- Department of Anatomy, Physiology and Pharmacology.,Cameco MS Neuroscience Research Center
| | - Lisa Yang
- Cameco MS Neuroscience Research Center
| | - Nikki A McLean
- Department of Anatomy, Physiology and Pharmacology.,Cameco MS Neuroscience Research Center
| | - Catherine Hutchinson
- Department of Anatomy, Physiology and Pharmacology.,Cameco MS Neuroscience Research Center
| | - Jayne M Johnston
- Department of Anatomy, Physiology and Pharmacology.,Cameco MS Neuroscience Research Center
| | - Vikram Misra
- Department of Veterinary Microbiology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Valerie M K Verge
- Department of Anatomy, Physiology and Pharmacology.,Cameco MS Neuroscience Research Center
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Hasmatali JCD, De Guzman J, Johnston JM, Noyan H, Juurlink BH, Misra V, Verge VMK. FOXO3a as a sensor of unilateral nerve injury in sensory neurons ipsilateral, contralateral and remote to injury. Neural Regen Res 2020; 15:2353-2361. [PMID: 32594060 PMCID: PMC7749464 DOI: 10.4103/1673-5374.284999] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Emerging evidence supports that the stress response to peripheral nerve injury extends beyond the injured neuron, with alterations in associated transcription factors detected both locally and remote to the lesion. Stress-induced nuclear translocation of the transcription factor forkhead class box O3a (FOXO3a) was initially linked to activation of apoptotic genes in many neuronal subtypes. However, a more complex role of FOXO3a has been suggested in the injury response of sensory neurons, with the injured neuron expressing less FOXO3a. To elucidate this response and test whether non-injured sensory neurons also alter FOXO3a expression, the temporal impact of chronic unilateral L4–6 spinal nerve transection on FOXO3a expression and nuclear localization in adult rat dorsal root ganglion neurons ipsilateral, contralateral or remote to injury relative to naïve controls was examined. In naïve neurons, high cytoplasmic and nuclear levels of FOXO3a colocalized with calcitonin gene related peptide, a marker of the nociceptive subpopulation. One hour post-injury, an acute increase in nuclear FOXO3a in small size injured neurons occurred followed by a significant decrease after 1, 2 and 4 days, with levels increasing toward pre-injury levels by 1 week post-injury. A more robust biphasic response to the injury was observed in uninjured neurons contralateral to and those remote to injury. Nuclear levels of FOXO3a peaked at 1 day, decreased by 4 days, then increased by 1 week post-injury, a response mirrored in C4 dorsal root ganglion neurons remote to injury. This altered expression contralateral and remote to injury supports that spinal nerve damage has broader systemic impacts, a response we recently reported for another stress transcription factor, Luman/CREB3. The early decreased expression and nuclear localization of FOXO3a in the injured neuron implicate these changes in the cell body response to injury that may be protective. Finally, the broader systemic changes support the existence of stress/injury-induced humeral factor(s) influencing transcriptional and potentially behavioral changes in uninjured dorsal root ganglion neurons. Approval to conduct this study was obtained from the University of Saskatchewan Animal Research Ethics Board (protocol #19920164).
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Affiliation(s)
- Jovan C D Hasmatali
- Department of Anatomy, Physiology, and Pharmacology; Cameco MS Neuroscience Research Center; Department of Veterinary Microbiology, University of Saskatchewan, Saskatoon, SK; Current affiliation: Department of Critical Care Medicine, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, Canada
| | - Jolly De Guzman
- Department of Anatomy, Physiology, and Pharmacology; Cameco MS Neuroscience Research Center, University of Saskatchewan, Saskatoon, SK, Canada
| | - Jayne M Johnston
- Department of Anatomy, Physiology, and Pharmacology; Cameco MS Neuroscience Research Center, University of Saskatchewan, Saskatoon, SK, Canada
| | - Hossein Noyan
- Department of Anatomy, Physiology, and Pharmacology; Cameco MS Neuroscience Research Center, University of Saskatchewan, Saskatoon, SK; Current affiliation: Department of Chemistry and Biology, Ryerson University, Toronto, ON, Canada
| | - Bernhard H Juurlink
- Department of Anatomy, Physiology, and Pharmacology; Cameco MS Neuroscience Research Center, University of Saskatchewan, Saskatoon, SK, Canada
| | - Vikram Misra
- Department of Veterinary Microbiology, University of Saskatchewan, Saskatoon, SK, Canada
| | - Valerie M K Verge
- Department of Anatomy, Physiology, and Pharmacology; Cameco MS Neuroscience Research Center, University of Saskatchewan, Saskatoon, SK, Canada
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9
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Verge VMK, Hasmatali JCD, Misra V. When the left side knows something happened to the right - sensing injury in neurons contralateral and remote to injury. Neural Regen Res 2020; 15:1854-1855. [PMID: 32246633 PMCID: PMC7513984 DOI: 10.4103/1673-5374.280316] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Affiliation(s)
- Valerie M K Verge
- Department of Anatomy, Physiology and Pharmacology, Cameco MS Neuroscience Research Center, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Jovan C D Hasmatali
- Department of Anatomy, Physiology and Pharmacology, Cameco MS Neuroscience Research Center, University of Saskatchewan, Saskatoon, Saskatchewan; Department of Critical Care Medicine, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, Manitoba; Department of Veterinary Microbiology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Vikram Misra
- Department of Veterinary Microbiology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
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10
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Senger JL, Chan KM, Macandili H, Chan AWM, Verge VMK, Jones KE, Webber CA. Conditioning electrical stimulation promotes functional nerve regeneration. Exp Neurol 2019; 315:60-71. [PMID: 30731076 DOI: 10.1016/j.expneurol.2019.02.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2018] [Revised: 01/30/2019] [Accepted: 02/01/2019] [Indexed: 12/11/2022]
Abstract
Peripheral nerve regeneration following injury is often incomplete, resulting in significant personal and socioeconomic costs. Although a conditioning crush lesion prior to surgical nerve transection and repair greatly promotes nerve regeneration and functional recovery, feasibility and ethical considerations have hindered its clinical applicability. In a recent proof of principle study, we demonstrated that conditioning electrical stimulation (CES) had effects on early nerve regeneration, similar to that seen in conditioning crush lesions (CCL). To convincingly determine its clinical utility, establishing the effects of CES on target reinnervation and functional outcomes is of utmost importance. In this study, we found that CES improved nerve regeneration and reinnervation well beyond that of CCL. Specifically, compared to CCL, CES resulted in greater intraepidermal skin and NMJ reinnervation, and greater physiological and functional recovery including mechanosensation, compound muscle action potential on nerve conduction studies, normalization of gait pattern, and motor performance on the horizontal ladder test. These findings have direct clinical relevance as CES could be delivered at the bedside before scheduled nerve surgery.
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Affiliation(s)
- Jenna-Lynn Senger
- Department of Surgery, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - K Ming Chan
- Division of Physical Rehabilitation, University of Alberta, Edmonton, AB T6G 2G3, Canada
| | - Haecy Macandili
- Department of Surgery, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - Ashley W M Chan
- Department of Surgery, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - Valerie M K Verge
- Department of Anatomy and Cell Biology, Cameco MS Neuroscience Research Center, University of Saskatchewan, Saskatoon, SK S7K 0M7, Canada
| | - Kelvin E Jones
- Department of Biomedical Engineering, University of Alberta, Edmonton, AB T6G 2H9, Canada
| | - Christine A Webber
- Department of Surgery, University of Alberta, Edmonton, AB T6G 2H7, Canada.
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11
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Affiliation(s)
| | - Valerie M. K. Verge
- Department of Anatomy and Cell Biology, and Cameco MS Neuroscience Research Center; University of Saskatchewan; Saskatoon Saskatchewan
| | - K. Ming Chan
- Department of Physical Rehabilitation; University of Alberta; Edmonton Alberta Canada
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12
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Senger JLB, Verge VMK, Macandili HSJ, Olson JL, Chan KM, Webber CA. Electrical stimulation as a conditioning strategy for promoting and accelerating peripheral nerve regeneration. Exp Neurol 2017; 302:75-84. [PMID: 29291403 DOI: 10.1016/j.expneurol.2017.12.013] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Revised: 12/23/2017] [Accepted: 12/26/2017] [Indexed: 02/07/2023]
Abstract
The delivery of a nerve insult (a "conditioning lesion") prior to a subsequent test lesion increases the number of regenerating axons and accelerates the speed of regeneration from the test site. A major barrier to clinical translation is the lack of an ethically acceptable and clinically feasible method of conditioning that does not further damage the nerve. Conditioning electrical stimulation (CES), a non-injurious intervention, has previously been shown to improve neurite outgrowth in vitro. In this study, we examined whether CES upregulates regeneration-associated gene (RAG) expression and promotes nerve regeneration in vivo, similar to a traditional nerve crush conditioning lesion (CCL). Adult rats were divided into four cohorts based on conditioning treatment to the common peroneal (fibular) nerve: i) CES (1h, 20Hz); ii) CCL (10s crush); iii) sham CES (1h, 0Hz); or iv) naïve (unconditioned). Immunofluorescence and qRT-PCR revealed significant RAG upregulation in the dorsal root ganglia of both CES and CCL animals, evident at 3-14days post-conditioning. To mimic a clinical microsurgical nerve repair, all cohorts underwent a common peroneal nerve cut and coaptation one week following conditioning. Both CES and CCL animals increased the length of nerve regeneration (3.8-fold) as well as the total number of regenerating axons (2.2-fold), compared to the sham and naïve-conditioned animals (p<0.001). These data support CES as a non-injurious conditioning paradigm that is comparable to a traditional CCL and is therefore a novel means to potentially enhance peripheral nerve repair in the clinical setting.
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Affiliation(s)
- J L B Senger
- Department of Surgery, University of Alberta, Alberta, Canada
| | - V M K Verge
- Department of Anatomy and Cell Biology & Cameco MS Neuroscience Research Center, University of Saskatchewan, Saskatchewan, Canada
| | - H S J Macandili
- Department of Surgery, University of Alberta, Alberta, Canada
| | - J L Olson
- Department of Surgery, University of Alberta, Alberta, Canada
| | - K M Chan
- Division of Physical Medicine and Rehabilitation, University of Alberta, Alberta, Canada
| | - C A Webber
- Department of Surgery, University of Alberta, Alberta, Canada.
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13
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McLean NA, Verge VMK. Dynamic impact of brief electrical nerve stimulation on the neural immune axis-polarization of macrophages toward a pro-repair phenotype in demyelinated peripheral nerve. Glia 2016; 64:1546-61. [PMID: 27353566 DOI: 10.1002/glia.23021] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2016] [Revised: 06/06/2016] [Accepted: 06/07/2016] [Indexed: 12/13/2022]
Abstract
Demyelinating peripheral nerves are infiltrated by cells of the monocyte lineage, including macrophages, which are highly plastic, existing on a continuum from pro-inflammatory M1 to pro-repair M2 phenotypic states. Whether one can therapeutically manipulate demyelinated peripheral nerves to promote a pro-repair M2 phenotype remains to be elucidated. We previously identified brief electrical nerve stimulation (ES) as therapeutically beneficial for remyelination, benefits which include accelerated clearance of macrophages, making us theorize that ES alters the local immune response. Thus, the impact of ES on the immune microenvironment in the zone of demyelination was examined. Adult male rat tibial nerves were focally demyelinated via 1% lysophosphatidyl choline (LPC) injection. Five days later, half underwent 1 hour 20 Hz sciatic nerve ES proximal to the LPC injection site. ES had a remarkable and significant impact, shifting the macrophage phenotype from predominantly pro-inflammatory/M1 toward a predominantly pro-repair/M2 one, as evidenced by an increased incidence of expression of M2-associated phenotypic markers in identified macrophages and a decrease in M1-associated marker expression. This was discernible at 3 days post-ES (8 days post-LPC) and continued at the 5 day post-ES (10 days post-LPC) time point examined. ES also affected chemokine (C-C motif) ligand 2 (CCL2; aka MCP-1) expression in a manner that correlated with increases and decreases in macrophage numbers observed in the demyelination zone. The data establish that briefly increasing neuronal activity favorably alters the immune microenvironment in demyelinated nerve, rapidly polarizing macrophages toward a pro-repair phenotype, a beneficial therapeutic concept that may extend to other pathologies. GLIA 2016;64:1546-1561.
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Affiliation(s)
- Nikki A McLean
- Department of Anatomy and Cell Biology, CMSNRC (Cameco MS Neuroscience Research Center), University of Saskatchewan, Saskatoon, SK, Canada
| | - Valerie M K Verge
- Department of Anatomy and Cell Biology, CMSNRC (Cameco MS Neuroscience Research Center), University of Saskatchewan, Saskatoon, SK, Canada
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14
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McLean NA, Popescu BF, Gordon T, Zochodne DW, Verge VMK. Delayed nerve stimulation promotes axon-protective neurofilament phosphorylation, accelerates immune cell clearance and enhances remyelination in vivo in focally demyelinated nerves. PLoS One 2014; 9:e110174. [PMID: 25310564 PMCID: PMC4195712 DOI: 10.1371/journal.pone.0110174] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2014] [Accepted: 09/17/2014] [Indexed: 01/19/2023] Open
Abstract
Rapid and efficient axon remyelination aids in restoring strong electrochemical communication with end organs and in preventing axonal degeneration often observed in demyelinating neuropathies. The signals from axons that can trigger more effective remyelination in vivo are still being elucidated. Here we report the remarkable effect of delayed brief electrical nerve stimulation (ES; 1 hour @ 20 Hz 5 days post-demyelination) on ensuing reparative events in a focally demyelinated adult rat peripheral nerve. ES impacted many parameters underlying successful remyelination. It effected increased neurofilament expression and phosphorylation, both implicated in axon protection. ES increased expression of myelin basic protein (MBP) and promoted node of Ranvier re-organization, both of which coincided with the early reappearance of remyelinated axons, effects not observed at the same time points in non-stimulated demyelinated nerves. The improved ES-associated remyelination was accompanied by enhanced clearance of ED-1 positive macrophages and attenuation of glial fibrillary acidic protein expression in accompanying Schwann cells, suggesting a more rapid clearance of myelin debris and return of Schwann cells to a nonreactive myelinating state. These benefits of ES correlated with increased levels of brain derived neurotrophic factor (BDNF) in the acute demyelination zone, a key molecule in the initiation of the myelination program. In conclusion, the tremendous impact of delayed brief nerve stimulation on enhancement of the innate capacity of a focally demyelinated nerve to successfully remyelinate identifies manipulation of this axis as a novel therapeutic target for demyelinating pathologies.
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Affiliation(s)
- Nikki A. McLean
- CMSNRC (Cameco MS Neuroscience Research Center) and Department of Anatomy and Cell Biology, University of Saskatchewan, Saskatoon, SK, Canada
| | - Bogdan F. Popescu
- CMSNRC (Cameco MS Neuroscience Research Center) and Department of Anatomy and Cell Biology, University of Saskatchewan, Saskatoon, SK, Canada
| | - Tessa Gordon
- Department of Surgery, Division of Plastic Reconstructive Surgery, University of Toronto, Toronto, ON, Canada
| | - Douglas W. Zochodne
- Department of Medicine, Division of Neurology, University of Alberta, Edmonton, AB, Canada
| | - Valerie M. K. Verge
- CMSNRC (Cameco MS Neuroscience Research Center) and Department of Anatomy and Cell Biology, University of Saskatchewan, Saskatoon, SK, Canada
- * E-mail:
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15
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Pettersson LME, Geremia NM, Ying Z, Verge VMK. Injury-associated PACAP expression in rat sensory and motor neurons is induced by endogenous BDNF. PLoS One 2014; 9:e100730. [PMID: 24968020 PMCID: PMC4072603 DOI: 10.1371/journal.pone.0100730] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2014] [Accepted: 05/28/2014] [Indexed: 11/19/2022] Open
Abstract
Peripheral nerve injury results in dramatic upregulation in pituitary adenylate cyclase activating polypeptide (PACAP) expression in adult rat dorsal root ganglia and spinal motor neurons mirroring that described for the neurotrophin brain derived neurotrophic factor (BDNF). Thus, we posited that injury-associated alterations in BDNF expression regulate the changes in PACAP expression observed in the injured neurons. The role of endogenous BDNF in induction and/or maintenance of PACAP mRNA expression in injured adult rat motor and sensory neurons was examined by intrathecally infusing or intraperitoneally injecting BDNF-specific antibodies or control IgGs immediately at the time of L4-L6 spinal nerve injury, or in a delayed fashion one week later for 3 days followed by analysis of impact on PACAP expression. PACAP mRNA in injured lumbar sensory and motor neurons was detected using in situ hybridization, allowing quantification of relative changes between experimental groups, with ATF-3 immunofluorescence serving to identify the injured subpopulation of motor neurons. Both the incidence and level of PACAP mRNA expression were dramatically reduced in injured sensory and motor neurons in response to immediate intrathecal anti-BDNF treatment. In contrast, neither intraperitoneal injections nor delayed intrathecal infusions of anti-BDNF had any discernible impact on PACAP expression. This impact on PACAP expression in response to BDNF immunoneutralization in DRG was confirmed using qRT-PCR or by using BDNF selective siRNAs to reduce neuronal BDNF expression. Collectively, our findings support that endogenous injury-associated BDNF expression is critically involved in induction, but not maintenance, of injury-associated PACAP expression in sensory and motor neurons.
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Affiliation(s)
- Lina M. E. Pettersson
- CMSNRC & Department of Anatomy & Cell Biology, University of Saskatchewan, Saskatoon, SK, Canada
- * E-mail:
| | - Nicole M. Geremia
- CMSNRC & Department of Anatomy & Cell Biology, University of Saskatchewan, Saskatoon, SK, Canada
| | - Zhengxin Ying
- CMSNRC & Department of Anatomy & Cell Biology, University of Saskatchewan, Saskatoon, SK, Canada
| | - Valerie M. K. Verge
- CMSNRC & Department of Anatomy & Cell Biology, University of Saskatchewan, Saskatoon, SK, Canada
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16
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Ying Z, Zhang R, Verge VMK, Misra V. Cloning and characterization of rat Luman/CREB3, a transcription factor highly expressed in nervous system tissue. J Mol Neurosci 2014; 55:347-54. [PMID: 24894591 DOI: 10.1007/s12031-014-0330-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2014] [Accepted: 05/12/2014] [Indexed: 11/24/2022]
Abstract
Human Luman/CREB3 is a basic leucine zipper transcription factor involved in regulation of the unfolded protein response, dendritic cell maturation, and cell migration. But despite reported expression in primary sensory neurons, little is known about its role in the nervous system. To begin investigations into its role in the adult rat nervous system, the rat Luman/CREB3 coding sequence was isolated so its expression within the nervous system could be determined. The rat Luman/CREB3 clone contains a full-length open reading frame encoding 387 amino acids. The recombinant protein generated from this clone activated transcription in a manner equivalent to human Luman/CREB3 from a CAT reporter plasmid construct containing the unfolded protein response element. Quantitative RT-PCR revealed that rat Luman/CREB3 transcripts in a variety of rat tissues with the highest levels in nervous system tissue. In situ hybridization performed on tissue sections confirmed the findings and demonstrated that the Luman/CREB3 mRNA hybridization signal localizes to neurons and satellite glial cells in dorsal root ganglia, the cytoplasm of hepatocytes in liver, and the hippocampal pyramidal cell layers of CA1 and CA3 and the granular cell layer of the dentate gyrus. Collectively, these findings support a role for Luman/CREB3 in the regulation of nervous system function.
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Affiliation(s)
- Zhengxin Ying
- Department of Anatomy and Cell Biology, University of Saskatchewan, Saskatoon, SK, S7N 5E5, Canada
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17
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Nadeau JR, Wilson-Gerwing TD, Verge VMK. Induction of a reactive state in perineuronal satellite glial cells akin to that produced by nerve injury is linked to the level of p75NTR expression in adult sensory neurons. Glia 2014; 62:763-77. [PMID: 24616056 DOI: 10.1002/glia.22640] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2013] [Accepted: 01/16/2014] [Indexed: 12/19/2022]
Abstract
Satellite glial cells (SGCs) surrounding primary sensory neurons are similar to astrocytes of the central nervous system in that they buffer the extracellular environment via potassium and calcium channels and express the intermediate filament glial fibrillary acidic protein (GFAP). Peripheral nerve injury induces a reactive state in SGCs that includes SGC proliferation, increased SGC/SGC coupling via gap junctions, decreased inward rectifying potassium channel 4.1 (Kir 4.1) expression and increased expression of GFAP and the common neurotrophin receptor, p75NTR. In contrast, neuronal p75NTR expression, normally detected in ∼80% of adult rat sensory neurons, decreases in response to peripheral axotomy. Given the differential regulation of p75NTR expression in neurons versus SGCs with injury, we hypothesized that reduced signaling via neuronal p75NTR contributes to the induction of a reactive state in SGCs. We found that reducing neuronal p75NTR protein expression in uninjured sensory neurons by intrathecal subarachnoid infusion of p75NTR-selective anti-sense oligodeoxynucleotides for one week was sufficient to induce a "reactive-like" state in the perineuronal SGCs akin to that normally observed following peripheral nerve injury. This reactive state included significantly increased SGC p75NTR, GFAP and gap junction protein connexin-43 protein expression, increased numbers of SGCs surrounding individual sensory neurons and decreased SGC Kir 4.1 channel expression. Collectively, this supports the tenet that reductions in target-derived trophic support leading to, or as a consequence of, reduced neuronal p75NTR expression plays a critical role in switching the SGC to a reactive state.
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Affiliation(s)
- Joelle R Nadeau
- Department of Anatomy and Cell Biology, University of Saskatchewan/Cameco MS Neuroscience Research Center, Saskatoon City Hospital, Saskatoon, SK, Canada
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18
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Abstract
Neuropathy is an insidious and devastating consequence of diabetes. Early studies provided a strong rationale for deficient neurotrophin support in the pathogenesis of diabetic neuropathy in a number of critical tissues and organs. It has now been over a decade since the first failed human neurotrophin supplementation clinical trials, but mounting evidence still implicates these trophic factors in diabetic neuropathy. Since then, tremendous advances have been made in our understanding of the complexities of neurotrophin signaling and processing and how the diabetic milieu might impact this. This in turn changes both our perception of how the altered trophic environment contributes to the etiology of diabetic neuropathy and the design of future neurotrophin therapeutic interventions. This chapter summarizes some of these findings and attempts to integrate neurotrophin actions on the nervous system with an increasing appreciation of their role in the regulation of metabolic processes in diabetes that impact the diabetic neuropathic state.
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Affiliation(s)
- Valerie M K Verge
- Department of Anatomy and Cell Biology, University of Saskatchewan, Saskatoon, Canada; Cameco MS Neuroscience Research Center, University of Saskatchewan, Saskatoon City Hospital, Saskatoon, Canada.
| | - Christer S Andreassen
- Department of Otorhinolaryngology and Head and Neck Surgery, Aarhus University Hospital, Aarhus, Denmark
| | - Terra G Arnason
- Department of Anatomy and Cell Biology, University of Saskatchewan, Saskatoon, Canada; Department of Medicine, Division of Endocrinology and Metabolism, University of Saskatchewan, Saskatoon, Canada
| | - Henning Andersen
- Department of Neurology, Aarhus University Hospital, Aarhus, Denmark
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19
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Singh B, Xu QG, Franz CK, Zhang R, Dalton C, Gordon T, Verge VMK, Midha R, Zochodne DW. Accelerated axon outgrowth, guidance, and target reinnervation across nerve transection gaps following a brief electrical stimulation paradigm. J Neurosurg 2011; 116:498-512. [PMID: 22149377 DOI: 10.3171/2011.10.jns11612] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECT Regeneration of peripheral nerves is remarkably restrained across transection injuries, limiting recovery of function. Strategies to reverse this common and unfortunate outcome are limited. Remarkably, however, new evidence suggests that a brief extracellular electrical stimulation (ES), delivered at the time of injury, improves the regrowth of motor and sensory axons. METHODS In this work, the authors explored and tested this ES paradigm, which was applied proximal to transected sciatic nerves in mice, and identified several novel and compelling impacts of the approach. Using thy-1 yellow fluorescent protein mice with fluorescent axons that allow serial in vivo tracking of regeneration, the morphological, electrophysiological, and behavioral indices of nerve regrowth were measured. RESULTS The authors show that ES is associated with a 30%-50% improvement in several indices of regeneration: regrowth of axons and their partnered Schwann cells across transection sites, maturation of regenerated fibers in gaps spanning transection zones, and entry of axons into their muscle and cutaneous target zones. In parallel studies, the authors analyzed adult sensory neurons and their response to extracellular ES while plated on a novel microelectrode array construct designed to deliver the identical ES paradigm used in vivo. The ES accelerated neurite outgrowth, supporting the concept of a neuron-autonomous mechanism of action. CONCLUSIONS Taken together, these results support a robust role for brief ES following peripheral nerve injuries in promoting regeneration. Electrical stimulation has a wider repertoire of impact than previously recognized, and its impact in vitro supports the hypothesis that a neuron-specific reprogrammed injury response is recruited by the ES protocol.
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Affiliation(s)
- Bhagat Singh
- Hotchkiss Brain Institute and Department of Clinical Neurosciences, Faculty of Medicine, University of Calgary, Alberta, Canada
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20
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Prosser-Loose EJ, Verge VMK, Cayabyab FS, Paterson PG. Protein-energy malnutrition alters hippocampal plasticity-associated protein expression following global ischemia in the gerbil. Curr Neurovasc Res 2011; 7:341-60. [PMID: 20883206 DOI: 10.2174/156720210793180792] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2010] [Accepted: 09/19/2010] [Indexed: 11/22/2022]
Abstract
Previously it has been demonstrated that protein-energy malnutrition (PEM) impairs habituation in the open field test following global ischemia. The present study examined the hypothesis that PEM exerts some of its deleterious effects on functional outcome by altering the post-ischemic expression of the plasticity-associated genes brain-derived neurotrophic factor (BDNF), its receptor tropomyosin-related kinase B (trkB), and growth-associated protein-43 (GAP-43). Male, Mongolian gerbils (11-12 wk) were randomized to either control diet (12.5% protein) or PEM (2% protein) for 4 wk, and then underwent 5 min bilateral common carotid artery occlusion or sham surgery. Tympanic temperature was maintained at 36.5 ± 0.5°C during surgery. Brains collected at 1, 3 and 7 d post-surgery were processed by in-situ hybridization or immunofluorescence. BDNF and trkB mRNA expression was increased in hippocampal CA1 neurons after ischemia at all time points and was not significantly influenced by diet. However, increased trkB protein expression after ischemia was exacerbated by PEM at 7 d in the CA1 region. Post-ischemic GAP-43 protein increased at 3 and 7 d in the CA1 region, and PEM intensified this response and extended it to the CA3 and hilar regions. PEM exerted these effects without exacerbating CA1 neuron loss caused by global ischemia. The findings suggest that PEM increases the stress response and/or hyper-excitability in the hippocampus after global ischemia. Nutritional care appears to have robust effects on plasticity mechanisms important to recovery after brain ischemia.
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Affiliation(s)
- Erin J Prosser-Loose
- College of Pharmacy and Nutrition, University of Saskatchewan, Saskatoon, SK, S7N 5C9, Canada
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21
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Wilson-Gerwing TD, Johnston JM, Verge VMK. p75 neurotrophin receptor is implicated in the ability of neurotrophin-3 to negatively modulate activated ERK1/2 signaling in TrkA-expressing adult sensory neurons. J Comp Neurol 2009; 516:49-58. [PMID: 19565663 DOI: 10.1002/cne.22098] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Neurotrophin-3 (NT-3) can negatively modulate trkA and associated phenotype in intact sensory neurons, while positively regulating trkC and associated phenotype. How NT-3 effects this response is not clear. Whether NT-3 exerts a differential influence on levels of activated ERK1/2 signaling in trkA- versus trkC-mRNA-positive subpopulations of neurons and the role that the common neurotrophin receptor, p75NTR, plays in this response was assessed by examining alterations in the levels of phospho-ERK1/2 immunofluorescence signal over nuclei of sensory neurons expressing trkA alone, trkC alone, or both trkA and trkC mRNA. NT-3 intrathecal infusion differentially modulated nuclear phospho-ERK1/2 levels detected over neurons expressing trkA alone or trkC alone. Levels were significantly decreased over nuclei of neurons expressing trkA alone and significantly increased over the nuclei of neurons expressing trkC alone. Neurons expressing both trkA and trkC or neurons expressing neither trkA nor trkC had no significant alteration in phospho-ERK1/2. Antisense oligonucleotides directed against p75NTR were infused intrathecally with or without NT-3 infusion to examine the impact of suppressing p75NTR expression on the ability of NT-3 to diminish phospho-ERK1/2 signaling in neurons expressing only trkA. NT-3 did not significantly attenuate levels of phospho-ERK1/2 when p75NTR expression was suppressed by antisense infusion, despite being able to do so when NT-3 was infused alone. In conclusion, NT-3's ability to negatively modulate ERK1/2 signaling in a p75-dependent manner in sensory neurons that express trkA to the exclusion of trkC provides a feasible mechanism by which it negatively modulates other aspects of nociceptive phenotype in these neurons.
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Affiliation(s)
- Tracy D Wilson-Gerwing
- Department of Anatomy and Cell Biology, Cameco MS Neuroscience Research Center University of Saskatchewan, Saskatoon, Saskatchewan, Canada
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22
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Geremia NM, Pettersson LME, Hasmatali JC, Hryciw T, Danielsen N, Schreyer DJ, Verge VMK. Endogenous BDNF regulates induction of intrinsic neuronal growth programs in injured sensory neurons. Exp Neurol 2009; 223:128-42. [PMID: 19646438 DOI: 10.1016/j.expneurol.2009.07.022] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2009] [Revised: 07/11/2009] [Accepted: 07/15/2009] [Indexed: 12/21/2022]
Abstract
Identification of the molecule(s) that globally induce a robust regenerative state in sensory neurons following peripheral nerve injury remains elusive. A potential candidate is brain-derived neurotrophic factor (BDNF), the sole neurotrophin upregulated in sensory neurons after peripheral nerve injury. Here we tested the hypothesis that BDNF plays a critical role in the regenerative response of mature rat sensory neurons following peripheral nerve lesion. Neutralization of endogenous BDNF was performed by infusing BDNF antibodies intrathecally via a mini-osmotic pump for 3 days at the level of the fifth lumbar dorsal root ganglion, immediately following unilateral spinal nerve injury. This resulted in decreased expression of the injury/regeneration-associated genes growth-associated protein-43 and Talpha1 tubulin in the injured sensory neurons as compared to injury plus control IgG infused or injury alone animals. Similar results were observed following inhibition of BDNF expression by intrathecal delivery of small interfering RNAs (siRNA) targeting BDNF starting 3 days prior to injury. The reduced injury/regeneration-associated gene expression correlated with a significantly reduced intrinsic capacity of these neurons to extend neurites when assayed in vitro. In contrast, delayed infusion of BDNF antibody for 3 days beginning 1 week post-lesion had no discernible influence on the elevated expression of these regeneration-associated markers. These results support an important role for endogenous BDNF in induction of the cell body response in injured sensory neurons and their intrinsic ability to extend neurites, but BDNF does not appear to be necessary for maintaining the response once it is induced.
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Affiliation(s)
- Nicole M Geremia
- Department of Anatomy and Cell Biology, Cameco MS Neuroscience Research Center University of Saskatchewan, Saskatoon, Saskatchewan, Canada S7N 5E5
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23
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Valderrama X, Rapin N, Verge VMK, Misra V. Zhangfei induces the expression of the nerve growth factor receptor, trkA, in medulloblastoma cells and causes their differentiation or apoptosis. J Neurooncol 2008; 91:7-17. [DOI: 10.1007/s11060-008-9682-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2008] [Accepted: 08/08/2008] [Indexed: 12/29/2022]
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24
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Wilson-Gerwing TD, Stucky CL, McComb GW, Verge VMK. Neurotrophin-3 significantly reduces sodium channel expression linked to neuropathic pain states. Exp Neurol 2008; 213:303-14. [PMID: 18601922 DOI: 10.1016/j.expneurol.2008.06.002] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2007] [Revised: 04/29/2008] [Accepted: 06/06/2008] [Indexed: 10/21/2022]
Abstract
Neuropathic pain resulting from chronic constriction injury (CCI) is critically linked to sensitization of peripheral nociceptors. Voltage gated sodium channels are major contributors to this state and their expression can be upregulated by nerve growth factor (NGF). We have previously demonstrated that neurotrophin-3 (NT-3) acts antagonistically to NGF in modulation of aspects of CCI-induced changes in trkA-associated nociceptor phenotype and thermal hyperalgesia. Thus, we hypothesized that exposure of neurons to increased levels of NT-3 would reduce expression of Na(v)1.8 and Na(v)1.9 in DRG neurons subject to CCI. In adult male rats, Na(v)1.8 and Na(v)1.9 mRNAs are expressed at high levels in predominantly small to medium size neurons. One week following CCI, there is reduced incidence of neurons expressing detectable Na(v)1.8 and Na(v)1.9 mRNA, but without a significant decline in mean level of neuronal expression, and similar findings observed immunohistochemically. There is also increased accumulation/redistribution of channel protein in the nerve most apparent proximal to the first constriction site. Intrathecal infusion of NT-3 significantly attenuates neuronal expression of Na(v)1.8 and Na(v)1.9 mRNA contralateral and most notably, ipsilateral to CCI, with a similar impact on relative protein expression at the level of the neuron and constricted nerve. We also observe reduced expression of the common neurotrophin receptor p75 in response to CCI that is not reversed by NT-3 in small to medium sized neurons and may confer an enhanced ability of NT-3 to signal via trkA, as has been previously shown in other cell types. These findings are consistent with an analgesic role for NT-3.
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Affiliation(s)
- Tracy D Wilson-Gerwing
- Department of Anatomy and Cell Biology, Cameco MS Neuroscience Research Center University of Saskatchewan, Saskatoon, Saskatchewan, Canada
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25
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Geremia NM, Gordon T, Brushart TM, Al-Majed AA, Verge VMK. Electrical stimulation promotes sensory neuron regeneration and growth-associated gene expression. Exp Neurol 2007; 205:347-59. [PMID: 17428474 DOI: 10.1016/j.expneurol.2007.01.040] [Citation(s) in RCA: 284] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2006] [Revised: 01/16/2007] [Accepted: 01/19/2007] [Indexed: 12/29/2022]
Abstract
Brief electrical stimulation enhances the regenerative ability of axotomized motor [Nix, W.A., Hopf, H.C., 1983. Electrical stimulation of regenerating nerve and its effect on motor recovery. Brain Res. 272, 21-25; Al-Majed, A.A., Neumann, C.M., Brushart, T.M., Gordon, T., 2000. Brief electrical stimulation promotes the speed and accuracy of motor axonal regeneration. J. Neurosci. 20, 2602-2608] and sensory [Brushart, T.M., Jari, R., Verge, V., Rohde, C., Gordon, T., 2005. Electrical stimulation restores the specificity of sensory axon regeneration. Exp. Neurol. 194, 221-229] neurons. Here we examined the parameter of duration of stimulation on regenerative capacity, including the intrinsic growth programs, of sensory neurons. The effect of 20 Hz continuous electrical stimulation on the number of DRG sensory neurons that regenerate their axons was evaluated following transection and surgical repair of the femoral nerve trunk. Stimulation was applied proximal to the repair site for 1 h, 3 h, 1 day, 7 days or 14 days at the time of nerve repair. Following a 21-day regeneration period, DRG neurons that regenerated axons into the muscle and cutaneous sensory nerve branches were retrogradely identified. Stimulation of 1 h led to a significant increase in DRG neurons regenerating into cutaneous and muscle branches when compared to 0 h (sham) stimulation or longer periods of stimulation. Stimulation for 1 h also significantly increased the numbers of neurons that regenerated axons beyond the repair site 4 days after lesion and was correlated with a significant increase in expression of growth-associated protein 43 (GAP-43) mRNA in the regenerating neurons at 2 days post-repair. An additional indicator of heightened plasticity following 1 h stimulation was elevated expression of brain-derived neurotrophic factor (BDNF). The effect of brief stimulation on enhancing sensory and motoneuron regeneration holds promise for inducing improved peripheral nerve repair in the clinical setting.
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Affiliation(s)
- Nicole M Geremia
- Department of Anatomy and Cell Biology, Cameco MS/Neuroscience Research Center University of Saskatchewan, Saskatoon City Hospital, Saskatchewan, Canada
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Wilson-Gerwing TD, Verge VMK. Neurotrophin-3 attenuates galanin expression in the chronic constriction injury model of neuropathic pain. Neuroscience 2006; 141:2075-85. [PMID: 16843605 DOI: 10.1016/j.neuroscience.2006.05.056] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2006] [Revised: 05/11/2006] [Accepted: 05/12/2006] [Indexed: 11/28/2022]
Abstract
We have recently shown that exogenous neurotrophin-3 (NT-3) acts antagonistically to nerve growth factor (NGF) in regulation of nociceptor phenotype in intact neurons and suppresses thermal hyperalgesia and expression of molecules complicit in this behavioral response induced by chronic constriction injury (CCI) of the sciatic nerve. The present study examines whether there is a global influence of NT-3 in mitigating alterations in peptide and NGF receptor expression; molecules believed to also contribute to CCI-associated pain. Thus, the influence of NT-3 on phenotypic changes in dorsal root ganglion (DRG) neurons in rats coincident with CCI was examined using in situ hybridization. Seven days following injury, the incidence of expression of the neuropeptides galanin and pituitary adenylate cyclase-activating polypeptide (PACAP) was increased in L5 sensory neurons ipsilateral to the injury from 12% to 60% and 16% to 37% respectively, in addition to an increased level of expression. In contrast, there was no consistent significant change in tropomyosin-related kinase A (trkA) expression following CCI. Intrathecal infusion of NT-3 globally mitigated both the increased incidence and elevated levels of galanin messenger RNA (mRNA) expression observed following CCI, reducing the former from 60% to 39%. NT-3 infusion resulted in a limited reduction in the incidence and level of neuronal PACAP in medium to large size, but not small size, DRG neurons. NT-3 had no significant net effect on CCI-induced alterations in trkA mRNA expression.
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Affiliation(s)
- T D Wilson-Gerwing
- Department of Anatomy and Cell Biology, Cameco MS Neuroscience Research Center, University of Saskatchewan, 701 Queen Street, Saskatoon, Saskatchewan, Canada S7N 5E5
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Wilson-Gerwing TD, Dmyterko MV, Zochodne DW, Johnston JM, Verge VMK. Neurotrophin-3 suppresses thermal hyperalgesia associated with neuropathic pain and attenuates transient receptor potential vanilloid receptor-1 expression in adult sensory neurons. J Neurosci 2005; 25:758-67. [PMID: 15659614 PMCID: PMC6725322 DOI: 10.1523/jneurosci.3909-04.2005] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2004] [Revised: 12/01/2004] [Accepted: 12/02/2004] [Indexed: 01/09/2023] Open
Abstract
Neurotrophin-3 (NT-3) negatively modulates nerve growth factor (NGF) receptor expression and associated nociceptive phenotype in intact neurons, suggesting a beneficial role in treating aspects of neuropathic pain mediated by NGF. We report that NT-3 is effective at suppressing thermal hyperalgesia associated with chronic constriction injury (CCI); however, NT-3 does not alter the mechanical hypersensitivity that also develops with CCI. Thermal hyperalgesia is critically linked to expression and activation of the capsaicin receptor, transient receptor potential vanilloid receptor-1 (TRPV1). Thus, its modulation by NT-3 after CCI was examined. CCI results in elevated TRPV1 expression at both the mRNA and protein levels in predominantly small-to-medium neurons, with the percentage of neurons expressing TRPV1 remaining unchanged at approximately 56%. Attenuation of thermal hyperalgesia mediated by NT-3 correlates with decreased TRPV1 expression such that only approximately 26% of neurons ipsilateral to CCI expressed detectable TRPV1 mRNA. NT-3 effected a decrease in expression of the activated component of the signaling pathway linked to regulation of TRPV1 expression, phospho-p38 MAPK (Ji et al., 2002), in neurons ipsilateral to CCI. Exogenous NT-3 could both prevent the onset of thermal hyperalgesia and reverse established thermal hyperalgesia and elevated TRPV1 expression 1 week after CCI. Continuous infusion is required for suppression of both thermal hyperalgesia and TRPV1 expression, because removal of NT-3 resulted in a prompt reestablishment of the hyperalgesic state and corresponding CCI-associated TRPV1 phenotype. In conclusion, although NGF drives inflammation-associated thermal hyperalgesia via its regulation of TRPV1 expression, NT-3 is now identified as a potent negative modulator of this state.
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Affiliation(s)
- Tracy D Wilson-Gerwing
- Department of Anatomy and Cell Biology, Cameco Multiple Sclerosis Neuroscience Research Center, University of Saskatchewan, Saskatoon, Saskatchewan, Canada S7N 5E5
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28
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Abstract
CGRP peptide, a widely expressed constituent of sensory neurons, plays important roles in nerve function and repair when axons are severed. CGRP synthesis declines, yet peptide nonetheless accumulates in severed axon endbulbs. In this work we explore an apparent selective and ongoing expression of CGRP peptide in regenerative sensory axon sprouts. Following sural nerve crush in rats out to 14 days, regenerating and branching sensory axons had intense and selective expression of CGRP, not associated with endbulbs. Parent L4 and L5 perikarya and axons in the sural nerve proximal to crush, however, did not exhibit such heightened CGRP presence. Instead, back labeling of regenerating axons with fluorogold or diamidino yellow labeled perikarya with reduced CGRP expression. Similarly, ATF-3, a robust marker of axotomized neurons, was associated with reduced, rather than elevated expression of alphaCGRP mRNA. Unexpectedly, however, we identified an enlarged secondary population of intact uninjured neurons, frequently smaller and projecting to the dorsal horn with new and heightened intense CGRP expression but not ATF-3- or tracer-labeled. Distal regenerating sensory axons selectively express CGRP peptide despite reduced perikaryal content, a phenomenon not explained by simple accumulation. Having an injured neighbor neuron, however, may also paradoxically alter how CGRP is expressed in intact neurons.
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Affiliation(s)
- Xia-Qing Li
- Department of Clinical Neurosciences, Neuroscience Research Group, University of Calgary, Alberta, Canada
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Abstract
This study examines the expression of pituitary adenylate cyclase activating polypeptide (PACAP) mRNA in the rat spinal cord during normal conditions and in response to sciatic nerve transection. Previously, PACAP immunoreactivity has been found in fibers in the spinal cord dorsal horn and around the central canal and in neurons in the intermediolateral column (IML). Furthermore, in the dorsal root ganglia, PACAP immunoreactivity and PACAP mRNA expression have been observed preferentially in nerve cell bodies of smaller diameter terminating in the superficial laminae of the dorsal horn. However, neuronal expression of PACAP mRNA in adult rat spinal cord appeared limited to neurons of the IML. By using a refined in situ hybridization protocol, we now detect PACAP mRNA expression in neurons primarily in laminae I and II, but also in deeper laminae of the spinal cord dorsal horn and around the central canal. In addition, PACAP mRNA expression is observed in a few neurons in the ventral horn. PACAP expression in the ventral horn is increased in a population of large neurons, most likely motor neurons, both after distal and proximal sciatic nerve transection. The proposed role of PACAP in nociception is strengthened by our findings of PACAP mRNA-expressing neurons in the superficial laminae of the dorsal horn. Furthermore, increased expression of PACAP in ventral horn neurons, in response to nerve transection, suggests a role for PACAP in repair/regeneration of motor neurons.
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Affiliation(s)
- Lina M E Pettersson
- Department of Physiological Sciences, Section for Neuroendocrine Cell Biology, Lund University, SE-221 84 Lund, Sweden.
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Jongsma Wallin H, Pettersson LME, Verge VMK, Danielsen N. Effect of anti-nerve growth factor treatment on pituitary adenylate cyclase activating polypeptide expression in adult sensory neurons exposed to adjuvant induced inflammation. Neuroscience 2003; 120:325-31. [PMID: 12890505 DOI: 10.1016/s0306-4522(03)00118-0] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Expression of pituitary adenylate cyclase activating polypeptide (PACAP) is increased in sensory neurons exposed to adjuvant induced peripheral inflammation. Local elevation in expression of the neurotrophin nerve growth factor (NGF) is a main factor contributing to the neuronal response to inflammation. This study examines the role of endogenous NGF in inflammation-associated increases in PACAP expression using the adjuvant-induced peripheral inflammation model with or without systemic administration of antibodies against NGF. Quantitative in situ hybridization was used to detect changes in neuronal PACAP mRNA expression and to correlate this expression with neuronal mRNA expression of the NGF receptor tyrosine kinase (trk) A. The results from this study show that inflammation triggered increases in PACAP expression occurs in small- to medium-sized dorsal root ganglion (DRG) neurons that also express trkA, and that this elevation in PACAP expression is prevented by systemic injection of anti-NGF. This supports a role for NGF as a positive regulator of PACAP expression during inflammation.
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Affiliation(s)
- H Jongsma Wallin
- Department of Physiological Sciences, BMC F10, Lund University, SE-221 84 Lund, Sweden.
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Abstract
Neurotrophin-3 (NT-3) binds to multiple trks, not only its initially identified receptor trkC. Recent studies in our laboratory show that NT-3 negatively regulates nociceptive phenotype associated with the trkA subpopulation. Due to the extensive overlap in trkA and trkC expression it is uncertain whether there is a direct influence of NT-3 on trkA in adult sensory neurons. Thus, the aim of this study was to examine whether NT-3 might alter trkA and associated neuronal phenotype outside of the trkC subpopulation. The effect of a seven-day intrathecal infusion of NT-3 on intact, uninjured adult rat dorsal root ganglion neurons was investigated. Serial sections were processed for receptor radioautography or in situ hybridization to identify and colocalize neurons expressing high-affinity nerve growth factor (NGF) binding sites, substance P (SP), trkC, or trkA mRNAs and to examine the influence of NT-3 on these populations. NT-3 does not appear to alter trkC expression, but evokes a notable reduction in trkA, high-affinity NGF binding sites, and SP levels. It is unlikely that signalling by trkC greatly influences this response because the down-regulation of SP occurs most notably in trkA neurons that lack trkC. Moreover, we have shown here that message levels of two trkA isoforms are differentially modulated by NT-3; infusion results in greater down-regulation of the noninsert containing isoform. These findings suggest a clinically relevant role for NT-3 as an antagonist to NGF, but also raise the caution that not just trkC-positive neurons are influenced following exposure to the neurotrophin.
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Affiliation(s)
- Kelly A Gratto
- Department of Anatomy and Cell Biology, Cameco MS Neuroscience Research Center, University of Saskatchewan, Saskatoon, SK, Canada S7N 5E5
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Abstract
It has been suggested that altered retrograde neurotrophin support contributes to the phenotypic switch observed in BDNF expression in injured sensory neurons. Thus, modulatory influences of NGF and NT-3 on BDNF expression in injured adult rat DRG neurons were examined using in situ hybridization and immunohistochemical approaches. Quantitative analysis reveals a biphasic response to sciatic nerve injury, whereby in the first day following injury, BDNF expression is up-regulated in approximately 83% of injured neurons including all small neurons, and a larger pool of trkB expressing neurons than in intact. By 1 week and up to 3 weeks later expression is still seen in approximately 66% of injured neurons, but the characteristic phenotypic switch in the subpopulations expressing BDNF occurs, whereby expression in the trkA population is reduced and expression in trkB- and in trkC-positive neurons is elevated. NGF infusion results in elevated levels of BDNF expression in both intact and injured trkA-positive neurons, accompanied by reduced trkB expression. NT-3 acts in an opposite fashion effecting a down-regulation in BDNF expression in intact neurons and preventing/reducing the injury-associated increases in BDNF expression in both trkC- and nontrkC-expressing subpopulations of injured neurons. These effects suggest NGF can regulate BDNF expression in trkA-expressing neurons regardless of the axonal state and that elevated levels of BDNF may contribute to the down-regulation in trkB expression associated with these states. Furthermore, the findings demonstrate that NT-3 can act in an antagonistic fashion to NGF in the regulation of BDNF expression in intact neurons, and mitigate BDNF's expression in injured neurons.
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MESH Headings
- Animals
- Brain-Derived Neurotrophic Factor/genetics
- Brain-Derived Neurotrophic Factor/metabolism
- Cell Size/physiology
- Ganglia, Spinal/injuries
- Ganglia, Spinal/metabolism
- Ganglia, Spinal/physiopathology
- Gene Expression/drug effects
- Gene Expression/physiology
- Immunohistochemistry
- Male
- Nerve Growth Factor/metabolism
- Nerve Growth Factor/pharmacology
- Nerve Regeneration/drug effects
- Nerve Regeneration/physiology
- Neurons, Afferent/drug effects
- Neurons, Afferent/metabolism
- Neurons, Afferent/pathology
- Neurotrophin 3/metabolism
- Neurotrophin 3/pharmacology
- RNA, Messenger/metabolism
- Rats
- Rats, Wistar
- Receptor, trkA/genetics
- Receptor, trkA/metabolism
- Receptor, trkB/genetics
- Receptor, trkB/metabolism
- Receptor, trkC/genetics
- Receptor, trkC/metabolism
- Sciatic Nerve/injuries
- Sciatic Nerve/metabolism
- Sciatic Nerve/physiopathology
- Time Factors
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Affiliation(s)
- L A Karchewski
- Department of Anat. & Cell Biol., University of Saskatchewan, S7N 5E5, Canada
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Karimi-Abdolrezaee S, Verge VMK, Schreyer DJ. Developmental down-regulation of GAP-43 expression and timing of target contact in rat corticospinal neurons. Exp Neurol 2002; 176:390-401. [PMID: 12359181 DOI: 10.1006/exnr.2002.7964] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
During early nervous system development axons grow toward the target tissue that they will innervate. As axons invade target tissue, growth slows and ceases. Neurons express high levels of the growth-associated protein GAP-43 during developmental axon growth, declining with maturation. It has been suggested that target contact provides a signal which down-regulates GAP-43 expression. To study this issue in more detail, we used in situ hybridization to quantify relative changes in GAP-43 mRNA in corticospinal tract neurons identified by Fast Blue retrograde labeling. We also used anterograde transport of biotinylated dextran amine to study the invasion of target by corticospinal axons. We find that GAP-43 mRNA is high during the first postnatal week and then declines in two phases. Approximately half of the initial level of GAP-43 expression in corticospinal neurons is lost by P12; then expression remains at a plateau until P21. Between P21 and P28, GAP-43 expression again declines by half and then remains steady at the adult level (one fourth of initial level). Corticospinal axons initially invade spinal gray matter during the first 2 postnatal weeks, in a rostrocaudal gradient. Varicosities suggestive of terminal boutons become numerous during the third and fourth week, and the morphology of corticospinal axon terminals achieves the mature form at the end of the fourth week. These data suggest that the first phase of down-regulation of GAP-43 in corticospinal neurons is coincident with initial target contact and that the second phase is coincident with final maturation of terminal arborization.
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Affiliation(s)
- Soheila Karimi-Abdolrezaee
- Cameco MS Neuroscience Research Center, Department of Anatomy and Cell Biology, University of Saskatchewan, Saskatoon, Canada S7K 0M7
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