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Rusbridge C. Neuropathic pain in cats: Mechanisms and multimodal management. J Feline Med Surg 2024; 26:1098612X241246518. [PMID: 38710218 PMCID: PMC11156241 DOI: 10.1177/1098612x241246518] [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] [Indexed: 05/08/2024]
Abstract
PRACTICAL RELEVANCE Chronic pain is a significant welfare concern in cats, and neuropathic pain, which arises from aberrant processing of sensory signals within the nervous system, is a subcategory of this type of pain. To comprehend this condition and how multimodal pharmacotherapy plays a central role in alleviating discomfort, it is crucial to delve into the anatomy of nociception and pain perception. In addition, there is an intricate interplay between emotional health and chronic pain in cats, and understanding and addressing the emotional factors that contribute to pain perception, and vice versa, is essential for comprehensive care.Clinical approach:Neuropathic pain is suspected if there is abnormal sensation in the area of the distribution of pain, together with a positive response to trial treatment with drugs effective for neuropathic pain. Ideally, this clinical suspicion would be supported by confirmation of a lesion at this neurolocalisation using diagnostic modalities such as MRI and neuroelectrophysiology. Alternatively, there may be a history of known trauma at that site. A variety of therapies, including analgesic, anti-inflammatory and adjuvant drugs, and neuromodulation (eg, TENS or acupuncture), can be employed to address different facets of pain pathways.Aim:This review article, aimed at primary care/ general practitioners, focuses on the identification and management of neuropathic pain in cats. Three case vignettes are included and a structured treatment algorithm is presented to guide veterinarians in tailoring interventions.Evidence base:The review draws on current literature, where available, along with the author's extensive experience and research.
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Affiliation(s)
- Clare Rusbridge
- BVMS, PhD, DipECVN, FRCVS School of Veterinary Medicine, The University of Surrey, Guildford, Surrey, UK; and Wear Referrals Veterinary Specialist & Emergency Hospital, Bradbury, Stockton-on-Tees, UK
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Campos RM, Barbosa-Silva MC, Ribeiro-Resende VT. Comparison of effect of crush or transection peripheral nerve lesion on lumbar spinal cord synaptic plasticity and microglial dynamics. IBRO Neurosci Rep 2021; 10:225-235. [PMID: 34179871 PMCID: PMC8211924 DOI: 10.1016/j.ibneur.2021.05.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Revised: 05/10/2021] [Accepted: 05/12/2021] [Indexed: 11/22/2022] Open
Abstract
In an injury to the peripheral nervous system, the spinal cord and brain structure reorganize connections to optimize the function of the remaining parts. Many cell events are triggered in the spinal cord to support changes in the synaptic connections around motoneurons, where old connections are removed, and new ones created. Microglial cells are primitive macrophages that invade the central nervous system in early stages of neurodevelopment and have several functions, such as eliminating synapses. We investigated the synaptic plasticity after different types of peripheral (sciatic) nerve injury (crush or total transection), as well as the behavior of microglial cells for 2 weeks after a peripheral lesion. As expected, sciatic-nerve injury reduced motor performance in mice, but crushed animals regained partial motor control. Because of sciatic-nerve injury, pre-synaptic inputs decreased around the motoneurons in the ventro-lateral horn, while microglial cells increased around these cells. Microglial cells also exhibited altered morphology in both types of peripheral lesion, indicating a similar underlying mechanism of plasticity. To investigate the involvement of microglia in this scenario, microglial activation was modulated by daily administration of minocycline. The minocycline treatment directly affected the microglial response and impacted the synapse rearrangement in the spinal cord. Together, these results demonstrate that microglia cells are involved in synaptic plasticity in the lumbar spinal cord in both nerve-injury scenarios. SUMMARY OF STATEMENT Here, we demonstrated that acute plasticity in the lumbar spinal cord (LSC) did not differ between crush and transection of peripheral nerve, and that microglial reactivity in the LSC was important after both injury types.
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Affiliation(s)
- Raquel M.P. Campos
- Instituto de Biofísica Carlos Chagas Filho, Laboratório de Neuroquímica, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ 21941-902, Brazil
| | - Maria Carolina Barbosa-Silva
- Instituto de Biofísica Carlos Chagas Filho, Laboratório de Neuroquímica, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ 21941-902, Brazil
| | - Victor T. Ribeiro-Resende
- Instituto de Biofísica Carlos Chagas Filho, Laboratório de Neuroquímica, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ 21941-902, Brazil
- Núcleo Multidisciplinar de Pesquisa em Biologia (Numpex-Bio), Campus de Duque de Caxias Geraldo Guerra Cidade, Universidade Federal do Rio de Janeiro, Duque de Caxias, RJ 25255-030, Brazil
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Sántha P, Dobos I, Kis G, Jancsó G. Role of Gangliosides in Peripheral Pain Mechanisms. Int J Mol Sci 2020; 21:E1005. [PMID: 32028715 PMCID: PMC7036959 DOI: 10.3390/ijms21031005] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2020] [Revised: 01/31/2020] [Accepted: 02/01/2020] [Indexed: 12/21/2022] Open
Abstract
Gangliosides are abundantly occurring sialylated glycosphingolipids serving diverse functions in the nervous system. Membrane-localized gangliosides are important components of lipid microdomains (rafts) which determine the distribution of and the interaction among specific membrane proteins. Different classes of gangliosides are expressed in nociceptive primary sensory neurons involved in the transmission of nerve impulses evoked by noxious mechanical, thermal, and chemical stimuli. Gangliosides, in particular GM1, have been shown to participate in the regulation of the function of ion channels, such as transient receptor potential vanilloid type 1 (TRPV1), a molecular integrator of noxious stimuli of distinct nature. Gangliosides may influence nociceptive functions through their association with lipid rafts participating in the organization of functional assemblies of specific nociceptive ion channels with neurotrophins, membrane receptors, and intracellular signaling pathways. Genetic and experimentally induced alterations in the expression and/or metabolism of distinct ganglioside species are involved in pathologies associated with nerve injuries, neuropathic, and inflammatory pain in both men and animals. Genetic and/or pharmacological manipulation of neuronal ganglioside expression, metabolism, and action may offer a novel approach to understanding and management of pain.
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Affiliation(s)
| | | | | | - Gábor Jancsó
- Department of Physiology, University of Szeged, Dóm tér 10, H-6720 Szeged, Hungary; (P.S.); (I.D.); (G.K.)
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Rezaee L, Manaheji H, Haghparast A. Role of spinal glial cells in excitability of wide dynamic range neurons and the development of neuropathic pain with the L5 spinal nerve transection in the rats: Behavioral and electrophysiological study. Physiol Behav 2019; 209:112597. [PMID: 31271834 DOI: 10.1016/j.physbeh.2019.112597] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2019] [Revised: 06/29/2019] [Accepted: 06/29/2019] [Indexed: 12/24/2022]
Abstract
The activation of glial cells affects the neuronal excitability in the spinal cord. Therefore, in this study, we tried to find out the modulatory role of spinal glial cells in the excitability of wide dynamic range (WDR) neurons, induction of the long-term potentiation (LTP) and development of neuropathic pain by L5 spinal nerve transection model in the rats. Forty-eight adult male Wistar rats were used to measure the paw withdrawal threshold to mechanical stimuli and also, to carry out the spinal extracellular single unit recording experiments. In these experiments, spinal nerve ligation (SNL) and a daily injection of propentofylline (1 mg/kg, ip) as a glial cell inhibitor agent, 1 h following nerve ligation during 7-day post-SNL period, were performed. Our findings showed that the mechanical allodynia, and synaptically-evoked firing were caused LTP in the Aδ-fiber, C-fiber and lesser in the Aβ-fiber after high frequency stimulation. Daily injection of propentofylline considerably decreased LTP induction in the Aδ- and C-fibers (P < .001). It was concluded that glial cell activation mediates LTP induction in the spinal cord following peripheral nerve injury. It seems that pain modulatory role of glial cells is partly parallel to changes in neural excitability of the WDR neurons in the dorsal horn of spinal cord.
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Affiliation(s)
- Laleh Rezaee
- Neuroscience Research Center, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Homa Manaheji
- Neurophysiology Research Center, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran; Department of Physiology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Abbas Haghparast
- Neuroscience Research Center, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
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Zhu YF, Kwiecien JM, Dabrowski W, Ungard R, Zhu KL, Huizinga JD, Henry JL, Singh G. Cancer pain and neuropathic pain are associated with A β sensory neuronal plasticity in dorsal root ganglia and abnormal sprouting in lumbar spinal cord. Mol Pain 2018; 14:1744806918810099. [PMID: 30324862 PMCID: PMC6243409 DOI: 10.1177/1744806918810099] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Evidence suggests that there are both nociceptive and neuropathic components of cancer-induced pain. We have observed that changes in intrinsic membrane properties and excitability of normally non-nociceptive Aβ sensory neurons are consistent in rat models of peripheral neuropathic pain and cancer-induced pain. This has prompted a comparative investigation of the intracellular electrophysiological characteristics of sensory neurons and of the ultrastructural morphology of the dorsal horn in rat models of neuropathic pain and cancer-induced pain. Neuropathic pain model rats were induced with a polyethylene cuff implanted around a sciatic nerve. Cancer-induced pain model rats were induced with mammary rat metastasis tumour-1 rat breast cancer or MATLyLu rat prostate cancer cells implanted into the distal epiphysis of a femur. Behavioural evidence of nociception was detected using von Frey tactile assessment. Aβ-fibre low threshold mechanoreceptor neurons in both cancer-induced pain and neuropathic pain models exhibited slower dynamics of action potential genesis, including a wider action potential duration and lower action potential amplitude compared to those in control animals. Enhanced excitability of Aβ-fibre low threshold mechanoreceptor neurons was also observed in cancer-induced pain and neuropathic pain models. Furthermore, both cancer-induced pain and neuropathic pain models showed abundant abnormal axonal sprouting in bundles of myelinated axons in the ipsilateral spinal laminae IV and V. The patterns of changes show consistency between rat models of cancer-induced pain and neuropathic pain. These findings add to the body of evidence that animal models of cancer-induced pain and neuropathic pain share features that may contribute to the peripheral and central sensitization and tactile hypersensitivity in both pain states.
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Affiliation(s)
- Yong Fang Zhu
- 1 Michael G. DeGroote Institute for Pain Research and Care, McMaster University, Hamilton, ON, Canada.,2 Department of Pathology and Molecular Medicine, McMaster University, Hamilton, ON, Canada
| | - Jacek M Kwiecien
- 2 Department of Pathology and Molecular Medicine, McMaster University, Hamilton, ON, Canada.,3 Department of Clinical Pathomorphology, Medical University of Lublin, Lublin, Poland
| | - Wojciech Dabrowski
- 4 Department of Anaesthesiology and Intensive Therapy, Medical University of Lublin, Lublin, Poland
| | - Robert Ungard
- 1 Michael G. DeGroote Institute for Pain Research and Care, McMaster University, Hamilton, ON, Canada.,2 Department of Pathology and Molecular Medicine, McMaster University, Hamilton, ON, Canada
| | - Kan Lun Zhu
- 2 Department of Pathology and Molecular Medicine, McMaster University, Hamilton, ON, Canada
| | - Jan D Huizinga
- 5 Department of Medicine, Farncombe Family Digestive Health Research Institute, McMaster University, Hamilton, ON, Canada
| | - James L Henry
- 6 Department of Psychiatry and Behavioural Neurosciences, McMaster University, Hamilton, ON, Canada
| | - Gurmit Singh
- 1 Michael G. DeGroote Institute for Pain Research and Care, McMaster University, Hamilton, ON, Canada.,2 Department of Pathology and Molecular Medicine, McMaster University, Hamilton, ON, Canada
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6
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Woolf CJ. Pain amplification-A perspective on the how, why, when, and where of central sensitization. ACTA ACUST UNITED AC 2018. [DOI: 10.1111/jabr.12124] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- Clifford J. Woolf
- FM Kirby Neurobiology Center; Boston Children's Hospital; Boston MA USA
- Department of Neurobiology; Harvard Medical School; Boston MA USA
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Ding Y, Yao P, Hong T, Han Z, Zhao B, Chen W, Zhou G. Early hyperbaric oxygen effects on neuropathic pain and nitric oxide synthase isoforms in CCI rats. Oncotarget 2018; 9:7513-7521. [PMID: 29484128 PMCID: PMC5800920 DOI: 10.18632/oncotarget.23867] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2017] [Accepted: 12/24/2017] [Indexed: 12/20/2022] Open
Abstract
Neuropathic pain is pain caused by injury or dysfunction in the central and/or peripheral nervous system. Neuropathic pain has a high incidence with a complex mechanism, but effective treatment remains elusive. Hyperbaric oxygen (HBO) therapy has been widely used in the treatment of a variety of neurological diseases. The current study used a rat model of neuropathic pain induced by chronic constriction injury (CCI) of the sciatic nerve. We observed the effects of early use of 2.5 absolute atmosphere (ATA) HBO on neuropathic pain-related behaviors and the expression of nitric oxide synthase (NOS) isoforms in the spinal dorsal horn. In the CCI group, mechanical withdrawal threshold (MWT) was decreased, Thermal withdrawal latency (TWL) was shortened, and mRNA and protein levels of iNOS and nNOS were significantly increased compared to the sham group. MWT was increased, TWL was enhanced, and iNOS and nNOS levels were significantly decreased in the HBO group compared to the CCI group. There was no change in eNOS levels across all groups. HBO treatment at early stages can improve hyperalgesia.
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Affiliation(s)
- Yuanyuan Ding
- Department of Pain Management, Shengjing Hospital of China Medical University, Shenyang, China
| | - Peng Yao
- Department of Pain Management, Shengjing Hospital of China Medical University, Shenyang, China
| | - Tao Hong
- Department of Pain Management, Shengjing Hospital of China Medical University, Shenyang, China
| | - Zhenkai Han
- Department of Pain Management, Shengjing Hospital of China Medical University, Shenyang, China
| | - Baisong Zhao
- Department of Anesthesiology, Guangzhou Women and Children's Medical Center, Guangzhou, China
| | - Weimin Chen
- Department of Anesthesiology, Shengjing Hospital of China Medical University, Shenyang, China
| | - Guangyu Zhou
- Department of Nephrology, Shengjing Hospital of China Medical University, Shenyang, China
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8
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Fernández-Montoya J, Martin YB, Negredo P, Avendaño C. Changes in the axon terminals of primary afferents from a single vibrissa in the rat trigeminal nuclei after active touch deprivation or exposure to an enriched environment. Brain Struct Funct 2017; 223:47-61. [PMID: 28702736 DOI: 10.1007/s00429-017-1472-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2017] [Accepted: 07/05/2017] [Indexed: 02/03/2023]
Abstract
Lasting modifications of sensory input induce structural and functional changes in the brain, but the involvement of primary sensory neurons in this plasticity has been practically ignored. Here, we examine qualitatively and quantitatively the central axonal terminations of a population of trigeminal ganglion neurons, whose peripheral axons innervate a single mystacial vibrissa. Vibrissa follicles are heavily innervated by myelinated and unmyelinated fibers that exit the follicle mainly through a single deep vibrissal nerve. We made intraneural injections of a mixture of cholera-toxin B (CTB) and isolectin B4, tracers for myelinated and unmyelinated fibers, respectively, in three groups of young adult rats: controls, animals subjected to chronic haptic touch deprivation by unilateral whisker trimming, and rats exposed for 2 months to environmental enrichment. The regional and laminar pattern of terminal arborizations in the trigeminal nuclei of the brain stem did not show gross changes after sensory input modification. However, there were significant and widespread increases in the number and size of CTB-labeled varicosities in the enriched condition, and a prominent expansion in both parameters in laminae III-IV of the caudal division of the spinal nucleus in the whisker trimming condition. No obvious changes were detected in IB4-labeled terminals in laminae I-II. These results show that a prolonged exposure to changes in sensory input without any neural damage is capable of inducing structural changes in terminals of primary afferents in mature animals, and highlight the importance of peripheral structures as the presumed earliest players in sensory experience-dependent plasticity.
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Affiliation(s)
- Julia Fernández-Montoya
- Department of Anatomy, Histology and Neuroscience, Medical School, Autonoma University of Madrid, c/Arzobispo Morcillo 2, 28029, Madrid, Spain
| | - Yasmina B Martin
- Departamento de Anatomía, Facultad de Ciencias de la Salud, Universidad Francisco de Vitoria, UFV, Edificio E, Ctra. M-115, Pozuelo-Majadahonda Km 1,800, Pozuelo de Alarcón, 28223, Madrid, Spain
| | - Pilar Negredo
- Department of Anatomy, Histology and Neuroscience, Medical School, Autonoma University of Madrid, c/Arzobispo Morcillo 2, 28029, Madrid, Spain
| | - Carlos Avendaño
- Department of Anatomy, Histology and Neuroscience, Medical School, Autonoma University of Madrid, c/Arzobispo Morcillo 2, 28029, Madrid, Spain.
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Painful Cervical Facet Joint Injury Is Accompanied by Changes in the Number of Excitatory and Inhibitory Synapses in the Superficial Dorsal Horn That Differentially Relate to Local Tissue Injury Severity. Spine (Phila Pa 1976) 2017; 42:E695-E701. [PMID: 27755498 PMCID: PMC5393960 DOI: 10.1097/brs.0000000000001934] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
STUDY DESIGN Immunohistochemistry labeled pre- and postsynaptic structural markers to quantify excitatory and inhibitory synapses in the spinal superficial dorsal horn at 14 days after painful facet joint injury in the rat. OBJECTIVE The objective of this study was to investigate the relationship between pain and synapse density in the spinal cord after facet injury. SUMMARY OF BACKGROUND DATA Neck pain is a major contributor to disability and often becomes chronic. The cervical facet joints are susceptible to loading-induced painful injury, initiating spinal central sensitization responses. Although excitatory synapse plasticity has been reported in the superficial dorsal horn early after painful facet injury, whether excitatory and/or inhibitory synapse density is altered at a time when pain is maintained is unknown. METHODS Rats underwent either a painful C6/C7 facet joint distraction or sham surgery. Mechanical hyperalgesia was measured and immunohistochemistry techniques for synapse quantification were used to quantify excitatory and inhibitory synapse densities in the superficial dorsal horn at day 14. Logarithmic correlation analyses evaluated whether the severity of facet injury correlated with either behavioral or synaptic outcomes. RESULTS Facet joint injury induces pain that is sustained until day 14 (P <0.001) and both significantly greater excitatory synapse density (P = 0.042) and lower inhibitory synapse density (P = 0.0029) in the superficial dorsal horn at day 14. Injury severity is significantly correlated with pain at days 1 (P = 0.0011) and 14 (P = 0.0002), but only with inhibitory, not excitatory, synapse density (P = 0.0025) at day 14. CONCLUSION This study demonstrates a role for structural plasticity in both excitatory and inhibitory synapses in the maintenance of facet-mediated joint pain, and that altered inhibitory, but not excitatory, synapse density correlates to the severity of painful joint injury. Understanding the functional consequences of this spinal structural plasticity is critical to elucidate mechanisms of chronic joint pain. LEVEL OF EVIDENCE N /A.
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10
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Ding YQ, Xie WZ, Qi JG. Regenerative peripheral neuropathic pain: novel pathological pain, new therapeutic dimension. Rev Neurosci 2017; 28:65-76. [PMID: 27664772 DOI: 10.1515/revneuro-2016-0014] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2016] [Accepted: 08/07/2016] [Indexed: 01/02/2023]
Abstract
AbstractAfter peripheral nerve damage, injured or stressed primary sensory neurons (PSNs) transmitting pathological pain (pathopain) sensitize central nervous system (CNS) neural circuits and determine behavioral phenotypes of peripheral neuropathic pain (PNP). Therefore, phenotypic profiling of pathopain-transmitting PSNs is vital for probing and discovering PNP conditions. Following peripheral nerve injuries (PNIs), PNP might be potentially transmitted by distinct classes of damaged or stressed PSNs, such as axotomized PSNs without regeneration (axotomy-non-regenerative neurons), axotomized PSNs with accurate regeneration (axotomy-regenerative neurons), and spared intact PSNs adjacent to axotomized neurons (axotomy-spared neurons). Both axotomy-non-regenerative neurons and axotomy-spared neurons have been definitely shown to participate in specific PNP transmission. However, whether axotomy-regenerative neurons could transmit PNP with unique features has remained unclear. Recent studies in rodent models of axonotmesis have clearly demonstrated that axotomy-regenerative neurons alone transmit persistent pathological pain with unique behavioral phenotypes. In this review, we exclusively review this novel category of PNP, reasonably term it ‘regenerative peripheral neuropathic pain’, and finally discuss its potential clinical significance as a new therapeutic dimension for PNIs beyond nerve regeneration.
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Nakamura M, Kim DY, Jang IS. Acid modulation of tetrodotoxin-sensitive Na + channels in large-sized trigeminal ganglion neurons. Brain Res 2016; 1651:44-52. [PMID: 27639809 DOI: 10.1016/j.brainres.2016.09.019] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2016] [Revised: 07/29/2016] [Accepted: 09/13/2016] [Indexed: 12/13/2022]
Abstract
Voltage-gated Na+ channels in primary afferent neurons can be divided into tetrodotoxin-sensitive (TTX-S) and tetrodotoxin-resistant (TTX-R) Na+ channels. Although previous studies have shown the acid modulation of TTX-R Na+ channels, the effect of acidic pH on tetrodotoxin-sensitive (TTX-S) Na+ channels is still unknown. Here we report the effect of acidic pH on TTX-S Na+ channels expressed in large-sized trigeminal ganglion (TG) neurons using a whole-cell patch clamp technique. The application of acidic extracellular solution decreased the peak amplitude of TTX-S currents (INa) in a pH-dependent manner, but weak acid (≥pH 6.0) had no inhibitory effect on TTX-S INa. Acidic pH (pH 6.0) shifted both the activation and steady-state fast inactivation relationships of TTX-S Na+ channels toward depolarized potentials. However, acidic pH (pH 6.0) had no effect on use-dependent inhibition in response to high-frequency stimuli, development of inactivation, and accelerated the recovery from inactivation of TTX-S Na+ channels, suggesting that TTX-S Na+ channels in large-sized TG neurons are less sensitive to acidic pH. Given that voltage-gated Na+ channels play a pivotal role in the generation and conduction of action potentials in neural tissues, the insensitivity of TTX-S Na+ channels expressed in large-sized TG neurons to acidic pH would ensure transmission of innocuous tactile sensation from orofacial regions at acidic pH conditions.
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Affiliation(s)
- Michiko Nakamura
- Department of Pharmacology, School of Dentistry, Kyungpook National University, Daegu 700-412, Republic of Korea; Brain Science & Engineering Institute, Kyungpook National University, Daegu 700-412, Republic of Korea
| | - Do-Yeon Kim
- Department of Pharmacology, School of Dentistry, Kyungpook National University, Daegu 700-412, Republic of Korea; Brain Science & Engineering Institute, Kyungpook National University, Daegu 700-412, Republic of Korea
| | - Il-Sung Jang
- Department of Pharmacology, School of Dentistry, Kyungpook National University, Daegu 700-412, Republic of Korea; Brain Science & Engineering Institute, Kyungpook National University, Daegu 700-412, Republic of Korea.
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12
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Naro A, Milardi D, Russo M, Terranova C, Rizzo V, Cacciola A, Marino S, Calabro RS, Quartarone A. Non-invasive Brain Stimulation, a Tool to Revert Maladaptive Plasticity in Neuropathic Pain. Front Hum Neurosci 2016; 10:376. [PMID: 27512368 PMCID: PMC4961691 DOI: 10.3389/fnhum.2016.00376] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2016] [Accepted: 07/12/2016] [Indexed: 12/18/2022] Open
Abstract
Neuromodulatory effects of non-invasive brain stimulation (NIBS) have been extensively studied in chronic pain. A hypothetic mechanism of action would be to prevent or revert the ongoing maladaptive plasticity within the pain matrix. In this review, the authors discuss the mechanisms underlying the development of maladaptive plasticity in patients with chronic pain and the putative mechanisms of NIBS in modulating synaptic plasticity in neuropathic pain conditions.
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Affiliation(s)
- Antonino Naro
- IRCCS Centro Neurolesi "Bonino-Pulejo" Messina, Italy
| | - Demetrio Milardi
- IRCCS Centro Neurolesi "Bonino-Pulejo"Messina, Italy; Department of Biomedical, Dental Sciences and Morphological and Functional Images, University of MessinaMessina, Italy
| | | | - Carmen Terranova
- Department of Clinical and Experimental Medicine, University of Messina Messina, Italy
| | - Vincenzo Rizzo
- Department of Clinical and Experimental Medicine, University of Messina Messina, Italy
| | - Alberto Cacciola
- IRCCS Centro Neurolesi "Bonino-Pulejo"Messina, Italy; Department of Biomedical, Dental Sciences and Morphological and Functional Images, University of MessinaMessina, Italy
| | - Silvia Marino
- IRCCS Centro Neurolesi "Bonino-Pulejo" Messina, Italy
| | | | - Angelo Quartarone
- IRCCS Centro Neurolesi "Bonino-Pulejo"Messina, Italy; Department of Biomedical, Dental Sciences and Morphological and Functional Images, University of MessinaMessina, Italy
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Mowery TM, Sarin RM, Kostylev PV, Garraghty PE. Differences in AMPA and GABAA/B receptor subunit expression between the chronically reorganized cortex and brainstem of adult squirrel monkeys. Brain Res 2015; 1611:44-55. [PMID: 25791620 DOI: 10.1016/j.brainres.2015.03.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Revised: 03/04/2015] [Accepted: 03/05/2015] [Indexed: 12/12/2022]
Abstract
The primate somatosensory neuraxis provides a highly translational model system with which to investigate adult neural plasticity. Here, we report immunohistochemical staining data for AMPA and GABAA/B receptor subunits of area 3b cortex and cuneate nucleus of adult squirrel monkeys one to five years after median and ulnar nerve transection. In Area 3B cortex, the expression of GluR1 AMPAR subunits in reorganized regions are significantly increased, while the expression of GluR2/3 AMPAR subunits are not. GABAA α1 subunit expression in the reorganized region is not significantly different from control regions. Presynaptic GABABR1a subunit expression was also not significantly different between reorganized and control regions, while postsynaptic GABABR1b subunit expression was significantly decreased. In the cuneate nucleus of the brainstem, the expression of GluR1 AMPAR subunits in reorganized regions was not significantly different, while GluR2/3 AMPAR subunit expression was significantly elevated. GABAA α1 subunit expression in the reorganized region was significantly decreased. Presynaptic GABABR1a subunit expression was not significantly different, while postsynaptic GABABR1b subunit expression was significantly decreased. When subunit expression is compared, brainstem and cortical patterns diverge over longer periods of recovery. Persistent patterns of change in the cortex are stable by 1-year. Alternatively, subunit expression in the cuneate nucleus one to five years after nerve injury is similar to that seen 1-month after a reorganizing injury. This suggests that cortical plasticity continues to change over many months as receptive field reorganization occurs, while brainstem plasticity obtains a level of stable persistence by one month.
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Affiliation(s)
- Todd M Mowery
- Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN United States.
| | - Rohini M Sarin
- Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN United States
| | - Polina V Kostylev
- Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN United States
| | - Preston E Garraghty
- Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN United States; Program in Neuroscience, Indiana University, Bloomington, IN United States
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Schuelert N, Gorodetskaya N, Just S, Doods H, Corradini L. Electrophysiological characterization of spinal neurons in different models of diabetes type 1- and type 2-induced neuropathy in rats. Neuroscience 2015; 291:146-54. [PMID: 25686525 DOI: 10.1016/j.neuroscience.2015.02.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2014] [Revised: 01/15/2015] [Accepted: 02/03/2015] [Indexed: 10/24/2022]
Abstract
Diabetic polyneuropathy (DPN) is a devastating complication of diabetes. The underlying pathogenesis of DPN is still elusive and an effective treatment devoid of side effects presents a challenge. There is evidence that in type-1 and -2 diabetes, metabolic and morphological changes lead to peripheral nerve damage and altered central nociceptive transmission, which may contribute to neuropathic pain symptoms. We characterized the electrophysiological response properties of spinal wide dynamic range (WDR) neurons in three diabetic models. The streptozotocin (STZ) model was used as a drug-induced model of type-1 diabetes, and the BioBreeding/Worcester (BB/Wor) and Zucker diabetic fatty (ZDF) rat models were used for genetic DPN models. Data were compared to the respective control group (BB/Wor diabetic-resistant, Zucker lean (ZL) and saline-injected Wistar rat). Response properties of WDR neurons to mechanical stimulation and spontaneous activity were assessed. We found abnormal response properties of spinal WDR neurons in all diabetic rats but not controls. Profound differences between models were observed. In BB/Wor diabetic rats evoked responses were increased, while in ZDF rats spontaneous activity was increased and in STZ rats mainly after discharges were increased. The abnormal response properties of neurons might indicate differential pathological, diabetes-induced, changes in spinal neuronal transmission. This study shows for the first time that specific electrophysiological response properties are characteristic for certain models of DPN and that these might reflect the diverse and complex symptomatology of DPN in the clinic.
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Affiliation(s)
- N Schuelert
- Department of CNS Diseases Research, Boehringer Ingelheim Pharma GmbH & Co KG, 88397 Biberach, Germany.
| | - N Gorodetskaya
- Department of CNS Diseases Research, Boehringer Ingelheim Pharma GmbH & Co KG, 88397 Biberach, Germany
| | - S Just
- Department of CNS Diseases Research, Boehringer Ingelheim Pharma GmbH & Co KG, 88397 Biberach, Germany
| | - H Doods
- Department of CNS Diseases Research, Boehringer Ingelheim Pharma GmbH & Co KG, 88397 Biberach, Germany
| | - L Corradini
- Department of CNS Diseases Research, Boehringer Ingelheim Pharma GmbH & Co KG, 88397 Biberach, Germany
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Abstract
Three theories of regeneration dominate neuroscience today, all purporting to explain why the adult central nervous system (CNS) cannot regenerate. One theory proposes that Nogo, a molecule expressed by myelin, prevents axonal growth. The second theory emphasizes the role of glial scars. The third theory proposes that chondroitin sulfate proteoglycans (CSPGs) prevent axon growth. Blockade of Nogo, CSPG, and their receptors indeed can stop axon growth in vitro and improve functional recovery in animal spinal cord injury (SCI) models. These therapies also increase sprouting of surviving axons and plasticity. However, many investigators have reported regenerating spinal tracts without eliminating Nogo, glial scar, or CSPG. For example, many motor and sensory axons grow spontaneously in contused spinal cords, crossing gliotic tissue and white matter surrounding the injury site. Sensory axons grow long distances in injured dorsal columns after peripheral nerve lesions. Cell transplants and treatments that increase cAMP and neurotrophins stimulate motor and sensory axons to cross glial scars and to grow long distances in white matter. Genetic studies deleting all members of the Nogo family and even the Nogo receptor do not always improve regeneration in mice. A recent study reported that suppressing the phosphatase and tensin homolog (PTEN) gene promotes prolific corticospinal tract regeneration. These findings cannot be explained by the current theories proposing that Nogo and glial scars prevent regeneration. Spinal axons clearly can and will grow through glial scars and Nogo-expressing tissue under some circumstances. The observation that deleting PTEN allows corticospinal tract regeneration indicates that the PTEN/AKT/mTOR pathway regulates axonal growth. Finally, many other factors stimulate spinal axonal growth, including conditioning lesions, cAMP, glycogen synthetase kinase inhibition, and neurotrophins. To explain these disparate regenerative phenomena, I propose that the spinal cord has evolved regenerative mechanisms that are normally suppressed by multiple extrinsic and intrinsic factors but can be activated by injury, mediated by the PTEN/AKT/mTOR, cAMP, and GSK3b pathways, to stimulate neural growth and proliferation.
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Affiliation(s)
- Wise Young
- W. M. Keck Center for Collaborative Neuroscience, Rutgers, State University of New Jersey, Piscataway, NJ, USA
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Hu Q, Fang L, Li F, Thomas S, Yang Z. Hyperbaric oxygenation treatment alleviates CCI-induced neuropathic pain and decreases spinal apoptosis. Eur J Pain 2014; 19:920-8. [DOI: 10.1002/ejp.618] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/28/2014] [Indexed: 12/19/2022]
Affiliation(s)
- Q. Hu
- Department of Anesthesiology; SUNY Upstate Medical University; Syracuse USA
| | - L. Fang
- Department of Anesthesiology; SUNY Upstate Medical University; Syracuse USA
| | - F. Li
- Department of Anesthesiology; SUNY Upstate Medical University; Syracuse USA
| | - S. Thomas
- Department of Anaesthesiology; Upstate Comprehensive Pain Medicine; Syracuse USA
| | - Z. Yang
- Department of Anesthesiology; SUNY Upstate Medical University; Syracuse USA
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Baseer N, Al-Baloushi AS, Watanabe M, Shehab SAS, Todd AJ. Selective innervation of NK1 receptor-lacking lamina I spinoparabrachial neurons by presumed nonpeptidergic Aδ nociceptors in the rat. Pain 2014; 155:2291-300. [PMID: 25168670 PMCID: PMC4247378 DOI: 10.1016/j.pain.2014.08.023] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2014] [Revised: 07/20/2014] [Accepted: 08/19/2014] [Indexed: 11/30/2022]
Abstract
Fine myelinated (Aδ) nociceptors are responsible for fast, well-localised pain, but relatively little is known about their postsynaptic targets in the spinal cord, and therefore about their roles in the neuronal circuits that process nociceptive information. Here we show that transganglionically transported cholera toxin B subunit (CTb) labels a distinct set of afferents in lamina I that are likely to correspond to Aδ nociceptors, and that most of these lack neuropeptides. The vast majority of lamina I projection neurons can be retrogradely labelled from the lateral parabrachial area, and these can be divided into 2 major groups based on expression of the neurokinin 1 receptor (NK1r). We show that CTb-labelled afferents form contacts on 43% of the spinoparabrachial lamina I neurons that lack the NK1r, but on a significantly smaller proportion (26%) of those that express the receptor. We also confirm with electron microscopy that these contacts are associated with synapses. Among the spinoparabrachial neurons that received contacts from CTb-labelled axons, contact density was considerably higher on NK1r-lacking cells than on those with the NK1r. By comparing the density of CTb contacts with those from other types of glutamatergic bouton, we estimate that nonpeptidergic Aδ nociceptors may provide over half of the excitatory synapses on some NK1r-lacking spinoparabrachial cells. These results provide further evidence that synaptic inputs to dorsal horn projection neurons are organised in a specific way. Taken together with previous studies, they suggest that both NK1r(+) and NK1r-lacking lamina I projection neurons are directly innervated by Aδ nociceptive afferents.
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Affiliation(s)
- Najma Baseer
- Institute of Neuroscience and Psychology, College of Medical, Veterinary, and Life Sciences, University of Glasgow, Glasgow, UK
| | - Abdullah S Al-Baloushi
- Department of Anatomy, College of Medicine and Health Sciences, United Arab Emirates University, Al Ain, United Arab Emirates
| | - Masahiko Watanabe
- Department of Anatomy, Hokkaido University School of Medicine, Sapporo, Japan
| | - Safa A S Shehab
- Department of Anatomy, College of Medicine and Health Sciences, United Arab Emirates University, Al Ain, United Arab Emirates.
| | - Andrew J Todd
- Institute of Neuroscience and Psychology, College of Medical, Veterinary, and Life Sciences, University of Glasgow, Glasgow, UK.
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Zhang TC, Janik JJ, Grill WM. Mechanisms and models of spinal cord stimulation for the treatment of neuropathic pain. Brain Res 2014; 1569:19-31. [PMID: 24802658 DOI: 10.1016/j.brainres.2014.04.039] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2014] [Revised: 04/25/2014] [Accepted: 04/27/2014] [Indexed: 12/23/2022]
Abstract
Spinal cord stimulation (SCS) is an established and cost-effective therapy for treating severe chronic pain. However, despite over 40 years of clinical practice and the development of novel electrode designs and treatment protocols, increases in clinical success, defined as the proportion of patients that experience 50% or greater self-reported pain relief, have stalled. An incomplete knowledge of the neural circuits and systems underlying chronic pain and the interaction of SCS with these circuits may underlie this plateau in clinical efficacy. This review summarizes prior work and identifies gaps in our knowledge regarding the neural circuits related to pain and SCS in the dorsal horn, supraspinal structures, and the Pain Matrix. In addition, this review discusses and critiques current experimental and computational models used to investigate and optimize SCS. Further research into the interactions between SCS and pain pathways in the nervous system using animal and computational models is a fruitful approach to improve this promising therapy.
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Affiliation(s)
- Tianhe C Zhang
- Department of Biomedical Engineering, Duke University, Durham, NC, USA
| | | | - Warren M Grill
- Department of Biomedical Engineering, Duke University, Durham, NC, USA; Department of Electrical and Computer Engineering, Duke University, Durham, NC, USA; Department of Neurobiology, Duke University, Durham, NC, USA; Department of Surgery, Duke University, Durham, NC, USA.
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Evaluation of pain behavior and calcitonin gene-related peptide immunoreactive sensory nerve fibers in the spinal dorsal horn after sciatic nerve compression and application of nucleus pulposus in rats. Spine (Phila Pa 1976) 2014; 39:455-62. [PMID: 24384662 DOI: 10.1097/brs.0000000000000180] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
STUDY DESIGN Animal study. OBJECTIVE To evaluate pain behavior and neuropeptide changes in the spinal dorsal horn after sciatic nerve compression and application of nucleus pulposus (NP) in rats. SUMMARY OF BACKGROUND DATA The pathomechanisms of lumbar disc herniation pain have not been fully elucidated. Pain-associated neuropeptides, including substance P and calcitonin gene-related peptide (CGRP), are produced in dorsal root ganglion neurons and transported to spinal dorsal horn nerve terminals where they function in pain transmission. However, changes in CGRP-immunoreactive (IR) sensory nerve terminals have not been reported in models of disc herniation. This study evaluated pain-related behavior and changes in CGRP-IR terminals in the spinal dorsal horn after combined sciatic nerve compression and NP application. METHODS Five groups of rats underwent either sciatic nerve compression with NP (n = 20), application of NP only (n = 20), nerve compression only (n = 20), and sham operation with neither compression nor NP (n = 20) or no operation (controls, n = 20). Mechanical hyperalgesia was measured every second day for 3 weeks. CGRP-IR terminals in each spinal dorsal horn lamina were examined 7 and 14 days postsurgery. Pain behavior and CGRP immunoreactivity were compared among the 5 groups. RESULTS Mechanical hyperalgesia was found in the NP only, nerve compression only, and the NP with nerve compression groups (P ≤ 0.05). CGRP-IR nerve terminals in the superficial laminae (I and II) and the deep laminae (III-VI) significantly increased in the NP only, nerve compression only, and NP with nerve compression groups compared with control and sham groups (P ≤ 0.05). Significant mechanical hyperalgesia and increased CGRP-IR nerve terminals were found in the NP with nerve compression group compared with the NP only and nerve compression only groups (P ≤ 0.05). CONCLUSION Our results indicate that nerve compression plus NP application produces the most pain-related behavior. CGRP-IR nerve terminals increased in laminae I and II that transmit pain and in laminae III to VI that transmit proprioception. Findings suggest that nerve compression plus NP application induces changes in CGRP expression in the superficial and deep laminae, and these changes are partly responsible for disc herniation pain.
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Belkouch M, Dansereau MA, Tétreault P, Biet M, Beaudet N, Dumaine R, Chraibi A, Mélik-Parsadaniantz S, Sarret P. Functional up-regulation of Nav1.8 sodium channel in Aβ afferent fibers subjected to chronic peripheral inflammation. J Neuroinflammation 2014; 11:45. [PMID: 24606981 PMCID: PMC4007624 DOI: 10.1186/1742-2094-11-45] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2013] [Accepted: 02/21/2014] [Indexed: 02/05/2023] Open
Abstract
Background Functional alterations in the properties of Aβ afferent fibers may account for the increased pain sensitivity observed under peripheral chronic inflammation. Among the voltage-gated sodium channels involved in the pathophysiology of pain, Nav1.8 has been shown to participate in the peripheral sensitization of nociceptors. However, to date, there is no evidence for a role of Nav1.8 in controlling Aβ-fiber excitability following persistent inflammation. Methods Distribution and expression of Nav1.8 in dorsal root ganglia and sciatic nerves were qualitatively or quantitatively assessed by immunohistochemical staining and by real time-polymerase chain reaction at different time points following complete Freund’s adjuvant (CFA) administration. Using a whole-cell patch-clamp configuration, we further determined both total INa and TTX-R Nav1.8 currents in large-soma dorsal root ganglia (DRG) neurons isolated from sham or CFA-treated rats. Finally, we analyzed the effects of ambroxol, a Nav1.8-preferring blocker on the electrophysiological properties of Nav1.8 currents and on the mechanical sensitivity and inflammation of the hind paw in CFA-treated rats. Results Our findings revealed that Nav1.8 is up-regulated in NF200-positive large sensory neurons and is subsequently anterogradely transported from the DRG cell bodies along the axons toward the periphery after CFA-induced inflammation. We also demonstrated that both total INa and Nav1.8 peak current densities are enhanced in inflamed large myelinated Aβ-fiber neurons. Persistent inflammation leading to nociception also induced time-dependent changes in Aβ-fiber neuron excitability by shifting the voltage-dependent activation of Nav1.8 in the hyperpolarizing direction, thus decreasing the current threshold for triggering action potentials. Finally, we found that ambroxol significantly reduces the potentiation of Nav1.8 currents in Aβ-fiber neurons observed following intraplantar CFA injection and concomitantly blocks CFA-induced mechanical allodynia, suggesting that Nav1.8 regulation in Aβ-fibers contributes to inflammatory pain. Conclusions Collectively, these findings support a key role for Nav1.8 in controlling the excitability of Aβ-fibers and its potential contribution to the development of mechanical allodynia under persistent inflammation.
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Affiliation(s)
| | | | | | | | | | | | | | | | - Philippe Sarret
- Department of Physiology and Biophysics, Faculty of Medicine and Health Sciences, Université de Sherbrooke, 3001, 12th Avenue North, Sherbrooke, Quebec J1H 5N4, Canada.
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Yasaka T, Tiong SY, Polgár E, Watanabe M, Kumamoto E, Riddell JS, Todd AJ. A putative relay circuit providing low-threshold mechanoreceptive input to lamina I projection neurons via vertical cells in lamina II of the rat dorsal horn. Mol Pain 2014; 10:3. [PMID: 24433581 PMCID: PMC3897975 DOI: 10.1186/1744-8069-10-3] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2013] [Accepted: 01/14/2014] [Indexed: 12/01/2022] Open
Abstract
Background Lamina I projection neurons respond to painful stimuli, and some are also activated by touch or hair movement. Neuropathic pain resulting from peripheral nerve damage is often associated with tactile allodynia (touch-evoked pain), and this may result from increased responsiveness of lamina I projection neurons to non-noxious mechanical stimuli. It is thought that polysynaptic pathways involving excitatory interneurons can transmit tactile inputs to lamina I projection neurons, but that these are normally suppressed by inhibitory interneurons. Vertical cells in lamina II provide a potential route through which tactile stimuli can activate lamina I projection neurons, since their dendrites extend into the region where tactile afferents terminate, while their axons can innervate the projection cells. The aim of this study was to determine whether vertical cell dendrites were contacted by the central terminals of low-threshold mechanoreceptive primary afferents. Results We initially demonstrated contacts between dendritic spines of vertical cells that had been recorded in spinal cord slices and axonal boutons containing the vesicular glutamate transporter 1 (VGLUT1), which is expressed by myelinated low-threshold mechanoreceptive afferents. To confirm that the VGLUT1 boutons included primary afferents, we then examined vertical cells recorded in rats that had received injections of cholera toxin B subunit (CTb) into the sciatic nerve. We found that over half of the VGLUT1 boutons contacting the vertical cells were CTb-immunoreactive, indicating that they were of primary afferent origin. Conclusions These results show that vertical cell dendritic spines are frequently contacted by the central terminals of myelinated low-threshold mechanoreceptive afferents. Since dendritic spines are associated with excitatory synapses, it is likely that most of these contacts were synaptic. Vertical cells in lamina II are therefore a potential route through which tactile afferents can activate lamina I projection neurons, and this pathway could play a role in tactile allodynia.
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Affiliation(s)
- Toshiharu Yasaka
- Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK.
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Detloff MR, Wade RE, Houlé JD. Chronic at- and below-level pain after moderate unilateral cervical spinal cord contusion in rats. J Neurotrauma 2013; 30:884-90. [PMID: 23216008 DOI: 10.1089/neu.2012.2632] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Chronic neuropathic pain is a significant consequence of spinal cord injury (SCI) that is associated with evoked pain, including allodynia and/or hyperalgesia. Allodynia is defined as a painful response to normally innocuous stimuli, and hyperalgesia occurs when there is an amplified pain response to normally noxious stimuli. We describe a model of a unilateral cervical level (C5) contusion injury where sensory recovery was assessed weekly for 6 weeks in 32 adult, female, Sprague-Dawley rats. Bilateral thermal hyperalgesia and tactile allodynia are detectable in the fore- and hindpaws as early as 7 days post-injury (dpi) and persist for at least 42 days. Paw withdrawal latency in response to a noxious thermal stimulus significantly intra-animal pre-operative values. Change in paw withdrawal latency plateaued at 21 dpi. Interestingly, bilateral forepaw allodynia develops in fewer than 40% of rats as measured by von Frey monofilament testing. Similar results occur in the hindpaws, where bilateral allodynia occurs in 46% of rats with SCI. The contralesional forepaw and both hindpaws of rats showed a slight increase in paw withdrawal threshold to tactile stimuli acutely after SCI, corresponding to ipsilesional forelimb motor deficits that resolve over time. That there is no difference among allodynic and non-allodynic groups in overall spared tissue or specifically of the dorsal column or ventrolateral white matter where ascending sensory tracts reside suggests that SCI-induced pain does not depend solely on the size or extent of the lesion, but that other mechanisms are in play. These observations provide a valid model system for future testing of therapeutic interventions to prevent the onset or to reduce the debilitating effects of chronic neuropathic pain after SCI.
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Affiliation(s)
- Megan Ryan Detloff
- Spinal Cord Research Center, Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, Pennsylvania, USA.
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AMPA and GABA(A/B) receptor subunit expression in the cuneate nucleus of adult squirrel monkeys during peripheral nerve regeneration. Neurosci Lett 2013; 559:141-6. [PMID: 24315976 DOI: 10.1016/j.neulet.2013.11.054] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2013] [Revised: 11/23/2013] [Accepted: 11/26/2013] [Indexed: 11/22/2022]
Abstract
The primate somatosensory neuroaxis provides an excellent model system with which to investigate adult neural plasticity. Here, we report immunohistochemical staining data for AMPA and GABAA/B receptor subunits in the cuneate nucleus of adult squirrel monkeys 1 and 5 months after median nerve compression. This method of nerve injury allowed the investigation of the way in which patterns of receptor correlates change during peripheral nerve regeneration. These results are compared to cortical data collected within the same animals. As observed in the cortex, the pattern of subunit staining in the brainstem 1 month after nerve compression suggests that the sensory deprived nucleus enters a state of reorganization. That is, the expression of GluR2/3 AMPA receptor subunits is significantly increased, while GABA α1 and GABABR1b receptor subunits are significantly decreased. Five months after nerve injury, the pattern of subunit expression is again very similar to that observed in the infragranular layers of cortex. At this later time we observe a significant increase in GluR2/3 and GABABR1a, with no change in GABAAα1, and a significant decrease in GABABR1b. Together these results suggest that during reorganization and recovery from injury the brainstem and cortex are governed by homogeneous mechanisms of plasticity.
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Abe T, Shimoda T, Urade M, Hasegawa M, Sugiyo S, Takemura M. c-Fos induction in the brainstem following electrical stimulation of the trigeminal ganglion of chronically mandibular nerve-transected rats. Somatosens Mot Res 2013; 30:175-84. [DOI: 10.3109/08990220.2013.790805] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Mowery TM, Walls SM, Garraghty PE. AMPA and GABA(A/B) receptor subunit expression in the cortex of adult squirrel monkeys during peripheral nerve regeneration. Brain Res 2013; 1520:80-94. [PMID: 23643858 DOI: 10.1016/j.brainres.2013.04.032] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2012] [Revised: 04/11/2013] [Accepted: 04/15/2013] [Indexed: 10/26/2022]
Abstract
The primate somatosensory neuroaxis provides a highly translational model system with which to investigate adult neural plasticity. Here, we report immunohistochemical staining data for AMPA and GABAA/B receptor subunits in the area 3b cortex of adult squirrel monkeys one and five months after median nerve compression. This method of nerve injury was selected because it allows unique insight into how receptor expression changes during the regeneration of the peripheral nerve. One month after nerve compression, the pattern of subunit staining provides evidence that the cortex enters a state of reorganization. GABA α1 receptor subunits are significantly down-regulated in layer IV, V, and VI. Glur2/3 AMPA receptor subunits and postsynaptic GABABR1b receptor subunits are up and down regulated respectively across all layers of cortex. After five months of recovery from nerve compression, the pattern of AMPA and GABAA/B receptor subunits remain significantly altered in a layer specific manner. In layer II/III, GluR1, GluR2/3, and GABA α1 subunit expression is significantly up-regulated while post synaptic GABABR1b receptor subunits are significantly down regulated. In layer VI, V, and VI the GluR2/3 and presynaptic GABABR1a receptor subunits are significantly up-regulated, while the postsynaptic GABABR1b receptor subunits remain significantly down-regulated. Taken together, these results suggest that following nerve injury the cortex enters a state of reorganization that has persistent effects on cortical plasticity even after partial or total reinnervation of the peripheral nerve.
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Affiliation(s)
- Todd M Mowery
- Department of Psychological and Brain Sciences, 4 Washington Place, NY 10003, USA.
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Wu CH, Lv ZT, Zhao Y, Gao Y, Li JQ, Gao F, Meng XF, Tian B, Shi J, Pan HL, Li M. Electroacupuncture improves thermal and mechanical sensitivities in a rat model of postherpetic neuralgia. Mol Pain 2013; 9:18. [PMID: 23551937 PMCID: PMC3626545 DOI: 10.1186/1744-8069-9-18] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2013] [Accepted: 03/14/2013] [Indexed: 11/10/2022] Open
Abstract
Background Electroacupuncture (EA) is effective in relieving pain in patients with postherpetic neuralgia (PHN). However, the mechanism underlying the therapeutic effect of EA in PHN is still unclear. Systemic injection of resiniferatoxin (RTX), an ultrapotent analog of TRPV1 agonist, in adult rats can reproduce the clinical symptoms of PHN by ablating TRPV1-expressing sensory neurons. In this study, we determined the beneficial effect of EA and the potential mechanisms in this rat model of PHN. Methods PHN was induced in rats by a single injection of RTX. Thermal hyperalgesia was tested with a radiant heat stimulus, and mechanical allodynia was quantified with von Frey filaments. TRPV1 receptors were shown by using immunofluorescence labeling. The ultrastructural changes of the sciatic nerve were assessed by electron microscopic examination. The sprouting of myelinated primary afferent terminals into the spinal dorsal horn was mapped by using the transganglionic tracer cholera toxin B-subunit (CTB). Results RTX injection diminished thermal sensitivity and gradually induced tactile allodynia within 3 weeks. EA applied to GB30 and GB34 at 2 and 15 Hz, but not 100 Hz, significantly increased the thermal sensitivity 4 weeks after treatment and decreased the tactile allodynia 2 weeks after treatment in RTX-treated rats. EA treatment at 2 and 15 Hz recovered the loss of TRPV1-positive dorsal root ganglion neurons and their central terminals of afferent fibers in the spinal superficial dorsal horn of RTX-treated rats. Moreover, EA significantly reduced the loss of unmyelinated fibers and the damage of the myelinated nerve fibers of RTX-treated rats. Furthermore, EA at 2 and 15 Hz inhibited the sprouting of myelinated primary afferent terminals into the spinal lamina II of RTX-treated rats. Conclusions EA treatment improves thermal perception by recovering TRPV1-positive sensory neurons and nerve terminals damaged by RTX. EA Also reduces RTX-induced tactile allodynia by attenuating the damage of myelinated afferent nerves and their abnormal sprouting into the spinal lamina II. Our study provides new information about the mechanisms of the therapeutic actions of EA in the treatment of PHN.
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Affiliation(s)
- Cai-hua Wu
- Department of Neurobiology, School of Basic Medicine, Tongji Medical College of Huazhong University of Science and Technology, 13 Hangkong Road, Wuhan, 430030, PR China
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Tan AM, Chakrabarty S, Kimura H, Martin JH. Selective corticospinal tract injury in the rat induces primary afferent fiber sprouting in the spinal cord and hyperreflexia. J Neurosci 2012; 32:12896-908. [PMID: 22973013 PMCID: PMC3499628 DOI: 10.1523/jneurosci.6451-11.2012] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2011] [Revised: 06/19/2012] [Accepted: 07/15/2012] [Indexed: 12/28/2022] Open
Abstract
The corticospinal tract (CST) has dense contralateral and sparse ipsilateral spinal cord projections that converge with proprioceptive afferents on common spinal targets. Previous studies in adult rats indicate that the loss of dense contralateral spinal CST connections after unilateral pyramidal tract section (PTx), which models CST loss after stroke or spinal cord injury, leads to outgrowth from the spared side into the affected, ipsilateral, spinal cord. The reaction of proprioceptive afferents after this CST injury, however, is not known. Knowledge of proprioceptive afferent responses after loss of the CST could inform mechanisms of maladaptive plasticity in spinal sensorimotor circuits after injury. Here, we hypothesize that the loss of the contralateral CST results in a reactive increase in muscle afferents from the impaired limb and enhancement of their physiological actions within the cervical spinal cord. We found that 10 d after PTx, proprioceptive afferents sprout into cervical gray matter regions denervated by the loss of CST terminations. Furthermore, VGlut1-positive boutons, indicative of group 1A afferent terminals, increased on motoneurons. PTx also produced an increase in microglial density within the gray matter regions where CST terminations were lost. These anatomical changes were paralleled by reduction in frequency-dependent depression of the H-reflex, suggesting hyperreflexia. Our data demonstrate for the first time that selective CST injury induces maladaptive afferent fiber plasticity remote from the lesion. Our findings suggest a novel structural reaction of proprioceptive afferents to the loss of CST terminations and provide insight into mechanisms underlying spasticity.
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Affiliation(s)
- Andrew M. Tan
- Department of Physiology, Pharmacology, and Neuroscience, The City College of the City University of New York, New York, New York 10031, and
| | - Samit Chakrabarty
- Department of Physiology, Pharmacology, and Neuroscience, The City College of the City University of New York, New York, New York 10031, and
- Institute of Membrane and Systems Biology, University of Leeds, Leeds LS29JT, United Kingdom
| | - Hiroki Kimura
- Department of Physiology, Pharmacology, and Neuroscience, The City College of the City University of New York, New York, New York 10031, and
| | - John H. Martin
- Department of Physiology, Pharmacology, and Neuroscience, The City College of the City University of New York, New York, New York 10031, and
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Conde D, Komisaruk BR. A neuroanatomical correlate of sensorimotor recovery in response to repeated vaginocervical stimulation in rats. Front Physiol 2012; 3:100. [PMID: 22529817 PMCID: PMC3329629 DOI: 10.3389/fphys.2012.00100] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2012] [Accepted: 03/30/2012] [Indexed: 11/13/2022] Open
Abstract
Gentle probing against the cervix via the vagina (vaginocervical stimulation, VCS) increases tail flick latency (TFL) to radiant heat; greater force abolishes the tail flick response and other withdrawal responses. This effect occurs in spinal cord-transected rats and in intact rats. On the basis of our earlier finding that VCS releases vasoactive intestinal peptide (VIP) into the spinal cord, and others’ reports of neurotrophic effects of VIP in vitro, we hypothesized that repeated VCS would stimulate sprouting and sensorimotor function of terminals of genital nerve primary afferents in the sacral spinal cord. To test this hypothesis, in the present study, we denervated the genital tract only unilaterally, which significantly reduced the TFL-elevating effect of VCS. Then we applied repeated daily VCS for 1 week and compared the subsequent effectiveness of acute VCS in elevating TFL. The rats that received the repeated daily VCS showed a significantly greater elevation in TFL in response to acute VCS than control rats that did not receive the repeated stimulation. Then, to test whether daily repeated VCS stimulates sprouting of genital primary afferents in such unilaterally genital tract-denervated rats, we transected the contralateral remaining intact pelvic nerve, applied horseradish peroxidase (HRP) to its proximal cut end for 1–2 h, and 2–3 days later counted HRP particles in its terminal zone (L6–S1) in the spinal cord. There were significantly more HRP particles in the rats that received the daily repeated VCS than in the control rats. In the context of these findings, we conclude that VCS in rats can produce a functional sensorimotor recovery via a neurotrophic effect on compromised primary afferents in the spinal cord.
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Affiliation(s)
- Dina Conde
- Department of Biology, Rutgers, The State University of New Jersey, Newark, NJ, USA
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Takahashil K, Watanabel M, Suekawal Y, Itol G, Inubushil T, Hirosel N, Murasakil K, Hiyamal S, Uchidal T, Tannel K. IL-1beta in the trigeminal subnucleus caudalis contributes to extra-territorial allodynia/hyperalgesia following a trigeminal nerve injury. Eur J Pain 2012; 15:467.e1-14. [DOI: 10.1016/j.ejpain.2010.10.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2010] [Revised: 10/08/2010] [Accepted: 10/15/2010] [Indexed: 11/26/2022]
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Shortland P, Kinman E, Molander C. Sprouting of A-fibre primary afferents into lamina II in two rat models of neuropathic pain. Eur J Pain 2012; 1:215-27. [PMID: 15102403 DOI: 10.1016/s1090-3801(97)90107-5] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/1997] [Accepted: 08/20/1997] [Indexed: 10/26/2022]
Abstract
Following peripheral nerve section, injured sensory A-fibres into lamina II of the dorsal horn and form aberrant functional synapses. Such structural changes may underlie some of the sensory abnormalities observed in nerve-injured patients, including neuropathic pain. This study compared the ability of intact and injured A-fibres to sprout in two experimental models of neuropathic pain, where the onset and presence of abnormal behaviours indicative of neuropathic pain have been well described. Rats received either a unilateral chronic constriction injury of the sciatic nerve (CCI) or lesion of the L5 spinal nerve (SNL). The central distribution of the injured and uninjured afferents labelled with choleragenoid conjugated to horseradish peroxidase (B-HRP) was examined at different postoperative survival times. In both models, the contralateral uninjured side, used for control nerve or ganglion injections, showed labelling of the L3-6 spinal segments in laminae I, III-V, leaving lamina II unlabelled. In CCI rats, injured sciatic afferents sprouted in lamina II of the L4-5 dorsal horn by 10 days postinjury. In SNL rats, injured L5 afferents sprouted into lamina II of the L4-5 dorsal horn by 24 h postinjury and were robust from 3 to 10 days. In both models, the labelling in lamina II was absent by 4 months. Labelling of the adjacent uninjured saphenous or intact L4 spinal nerve afferents did not reveal A-fibre sprouting. As the time-course of sprouting of injured A-fibres parallels the previously described behaviour interpreted as neuropathic pain in these models, this may be a phenomenon that contributes to sensory abnormalities such as ongoing pain and mechanical hypersensitivity.
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Affiliation(s)
- P Shortland
- Department of Neuroscience, Division of Neuroanatomy and Neuronal Plasticity, Karolinska Institutet, Stockholm, Sweden
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Jaken RJ, van Gorp S, Joosten EA, Losen M, Martínez-Martínez P, De Baets M, Marcus MA, Deumens R. Neuropathy-induced spinal GAP-43 expression is not a main player in the onset of mechanical pain hypersensitivity. J Neurotrauma 2011; 28:2463-73. [PMID: 21671799 DOI: 10.1089/neu.2011.1833] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Structural plasticity within the spinal nociceptive network may be fundamental to the chronic nature of neuropathic pain. In the present study, the spatiotemporal expression of growth-associated protein-43 (GAP-43), a protein which has been traditionally implicated in nerve fiber growth and sprouting, was investigated in relation to mechanical pain hypersensitivity. An L5 spinal nerve transection model was validated by the presence of mechanical pain hypersensitivity and an increase in the early neuronal activation marker cFos within the superficial spinal dorsal horn upon innocuous hindpaw stimulation. Spinal GAP-43 was found to be upregulated in the superficial L5 dorsal horn from 5 up to 10 days after injury. GAP-43 was co-localized with calcitonin-gene related peptide (CGRP), but not vesicular glutamate transporter-1 (VGLUT-1), IB4, or protein kinase-γ (PKC-γ), suggesting the regulation of GAP-43 in peptidergic nociceptive afferents. These GAP-43/CGRP fibers may be indicative of sprouting peptidergic fibers. Fiber sprouting largely depends on growth factors, which are typically associated with neuro-inflammatory processes. The putative role of neuropathy-induced GAP-43 expression in the development of mechanical pain hypersensitivity was investigated using the immune modulator propentofylline. Propentofylline treatment strongly attenuated the development of mechanical pain hypersensitivity and glial responses to nerve injury as measured by microglial and astroglial markers, but did not affect neuropathy-induced levels of spinal GAP-43 or GAP-43 regulation in CGRP fibers. We conclude that nerve injury induces structural plasticity in fibers expressing CGRP, which is regarded as a main player in central sensitization. Our data do not, however, support a major role of these structural changes in the onset of mechanical pain hypersensitivity.
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Affiliation(s)
- Robby J Jaken
- Pain Management and Research Center, Department of Anesthesiology, Maastricht University Medical Center, Maastricht, The Netherlands
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A quantitative evaluation of gross versus histologic neuroma formation in a rabbit forelimb amputation model: potential implications for the operative treatment and study of neuromas. J Brachial Plex Peripher Nerve Inj 2011; 6:8. [PMID: 21992517 PMCID: PMC3207865 DOI: 10.1186/1749-7221-6-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/28/2010] [Accepted: 10/13/2011] [Indexed: 11/28/2022] Open
Abstract
Background Surgical treatment of neuromas involves excision of neuromas proximally to the level of grossly "normal" fascicles; however, proximal changes at the axonal level may have both functional and therapeutic implications with regard to amputated nerves. In order to better understand the retrograde "zone of injury" that occurs after nerve transection, we investigated the gross and histologic changes in transected nerves using a rabbit forelimb amputation model. Methods Four New Zealand White rabbits underwent a forelimb amputation with transection and preservation of the median, radial, and ulnar nerves. After 8 weeks, serial sections of the amputated nerves were then obtained in a distal-to-proximal direction toward the brachial plexus. Quantitative histomorphometric analysis was performed on all nerve specimens. Results All nerves demonstrated statistically significant increases in nerve cross-sectional area between treatment and control limbs at the distal nerve end, but these differences were not observed 10 mm more proximal to the neuroma bulb. At the axonal level, an increased number of myelinated fibers were seen at the distal end of all amputated nerves. The number of myelinated fibers progressively decreased in proximal sections, normalizing at 15 mm proximally, or the level of the brachial plexus. The cross-sectional area of myelinated fibers was significantly decreased in all sections of the treatment nerves, indicating that atrophic axonal changes proceed proximally at least to the level of the brachial plexus. Conclusions Morphologic changes at the axonal level extend beyond the region of gross neuroma formation in a distal-to-proximal fashion after nerve transection. This discrepancy between gross and histologic neuromas signifies the need for improved standardization among neuroma models, while also providing a fresh perspective on how we should view neuromas during peripheral nerve surgery.
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Ueda H, Ueda M. Lysophosphatidic acid as an initiator of neuropathic pain: biosynthesis and demyelination. ACTA ACUST UNITED AC 2011. [DOI: 10.2217/clp.10.88] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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Berger JV, Knaepen L, Janssen SPM, Jaken RJP, Marcus MAE, Joosten EAJ, Deumens R. Cellular and molecular insights into neuropathy-induced pain hypersensitivity for mechanism-based treatment approaches. ACTA ACUST UNITED AC 2011; 67:282-310. [PMID: 21440003 DOI: 10.1016/j.brainresrev.2011.03.003] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2010] [Revised: 02/16/2011] [Accepted: 03/18/2011] [Indexed: 12/15/2022]
Abstract
Neuropathic pain is currently being treated by a range of therapeutic interventions that above all act to lower neuronal activity in the somatosensory system (e.g. using local anesthetics, calcium channel blockers, and opioids). The present review highlights novel and often still largely experimental treatment approaches based on insights into pathological mechanisms, which impact on the spinal nociceptive network, thereby opening the 'gate' to higher brain centers involved in the perception of pain. Cellular and molecular mechanisms such as ectopia, sensitization of nociceptors, phenotypic switching, structural plasticity, disinhibition, and neuroinflammation are discussed in relation to their involvement in pain hypersensitivity following either peripheral neuropathies or spinal cord injury. A mechanism-based treatment approach may prove to be successful in effective treatment of neuropathic pain, but requires more detailed insights into the persistence of cellular and molecular pain mechanisms which renders neuropathic pain unremitting. Subsequently, identification of the therapeutic window-of-opportunities for each specific intervention in the particular peripheral and/or central neuropathy is essential for successful clinical trials. Most of the cellular and molecular pain mechanisms described in the present review suggest pharmacological interference for neuropathic pain management. However, also more invasive treatment approaches belong to current and/or future options such as neuromodulatory interventions (including spinal cord stimulation) and cell or gene therapies, respectively.
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Affiliation(s)
- Julie V Berger
- Department of Anesthesiology, Maastricht University Medical Centre, Maastricht, The Netherlands
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Fukushima T, Takasusuki T, Tomitori H, Hori Y. Possible involvement of syntaxin 1A downregulation in the late phase of allodynia induced by peripheral nerve injury. Neuroscience 2011; 175:344-57. [DOI: 10.1016/j.neuroscience.2010.11.049] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2010] [Revised: 11/11/2010] [Accepted: 11/22/2010] [Indexed: 11/16/2022]
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Abstract
The main text of this chapter, written by James P. Lund, summarizes most of the work related to the neural control of mastication that he conducted with his collaborators throughout the years. From his early PhD work showing that mastication is centrally patterned to his latest work related to the interaction between pain and movement, Lund will have addressed many essential questions regarding the organization and functioning of the masticatory central pattern generator (CPG). His earliest studies examined how the CPG modulates reflexes and the excitability of primary afferents, interneurons, and motoneurons forming their circuitry. He then tackled the question of how the CPG itself was modulated by different types of sensory and cortical inputs. Another series of studies focused on the organization of the subpopulations of neurons forming the CPG, their intrinsic and network properties. Shortly before his untimely passing, he had turned his attention to the potential contribution of muscle spindle afferents to the patterning of mastication as well as to the development of chronic muscle pain.
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Affiliation(s)
- James P Lund
- Faculty of Dentistry, McGill University, Montreal, Quebec, Canada
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Peng B, Lin JY, Shang Y, Yang ZW, Wang YP. Plasticity in the synaptic number associated with neuropathic pain in the rat spinal dorsal horn: A stereological study. Neurosci Lett 2010; 486:24-8. [DOI: 10.1016/j.neulet.2010.09.037] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2010] [Revised: 08/24/2010] [Accepted: 09/13/2010] [Indexed: 11/17/2022]
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Hayashi M, Kamiya Y, Itoh H, Higashi T, Miyazaki T, Funakoshi K, Yamashita N, Goshima Y, Andoh T, Yamada Y, Goto T. Intrathecally administered Sema3A protein attenuates neuropathic pain behavior in rats with chronic constriction injury of the sciatic nerve. Neurosci Res 2010; 69:17-24. [PMID: 20888378 DOI: 10.1016/j.neures.2010.09.006] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2010] [Revised: 08/24/2010] [Accepted: 09/21/2010] [Indexed: 10/19/2022]
Abstract
Semaphorins, one of the repulsive axonal guidance factors during development, are produced under pathological conditions in adult animals. In the neuropathic pain state associated with peripheral nerve injury, synaptic reorganization occurs in spinal cord dorsal horn. In the present study, we investigated the roles of intrathecal administration of Sema3A, a secreted semaphorin, in the spinal cord of chronic constriction injury (CCI) model rat. Neuropilin 1 (NPR1) and Plexin A (PlexA), co-receptors of Sema3A, were expressed in the dorsal horn of naïve rats. NPR1, and not PlexA, protein expression increased in the dorsal spinal cord of CCI rats. Recombinant Sema3A protein attenuated mechanical allodynia and heat hyperalgesia in CCI rats, whereas heat-inactivated Sema3A had no effect. Immunohistochemistry revealed that Sema3A partially restored the decrease of isolectin B4-positive unmyelinated nerve terminals in lamina II of the ipsilateral dorsal horn of CCI rats. Contrary to our expectations, Sema3A did not change the distribution of myelinated fibers in lamina II at 7 days after CCI. Those results suggested that the suppressive role for Sema3A in the development of neuropathic pain associated with peripheral nerve injury in adult rats, which seemed to be independent from prevention of the myelinated fiber sprouting into lamina II.
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Affiliation(s)
- Michiko Hayashi
- Department of Anesthesiology and Critical Care Medicine, Yokohama City University Graduate School of Medicine, Kanazawa-ku, Yokohama, Japan
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Oaklander AL. Role of Minimal Distal Nerve Injury in Complex Regional Pain Syndrome-I. PAIN MEDICINE 2010; 11:1251-6. [DOI: 10.1111/j.1526-4637.2010.00917.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Inhibition of glucosylceramide synthase reversibly decreases the capsaicin-induced activation and TRPV1 expression of cultured dorsal root ganglion neurons. Pain 2010; 150:103-112. [DOI: 10.1016/j.pain.2010.04.006] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2009] [Revised: 03/25/2010] [Accepted: 04/05/2010] [Indexed: 11/22/2022]
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Baloui H, Stettler O, Weiss S, Nothias F, von Boxberg Y. Upregulation in rat spinal cord microglia of the nonintegrin laminin receptor 37 kDa-LRP following activation by a traumatic lesion or peripheral injury. J Neurotrauma 2009; 26:195-207. [PMID: 19196078 DOI: 10.1089/neu.2008.0677] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The molecular mechanisms triggering microglial activation after injury to the central nervous system, involving cell-extracellular matrix interactions and cytokine signaling, are not yet fully understood. Here, we report that resident microglia in spinal cord express low levels of the non-integrin laminin receptor precursor (LRP), also found on certain neurons and glial cells in the peripheral nervous system. 37LRP/p40 and its 67-kDa isoform laminin receptor (LR) were the first high-affinity laminin binding proteins identified. While the role of laminin receptor was later attributed to integrins, LRP/LR gained new interest as receptors for prions, and their interaction with laminin seems important for migration of metastatic cancer cells. Using immunohistochemistry and Western blotting, we demonstrate that traumatic spinal cord injury leads to a strong and rapid increase in LRP levels in relation to activated microglia/macrophages. Associated with laminin re-expression in the lesion epicenter, LRP-positive microglia/macrophages exhibit a rounded, ameboid-like shape characteristic of phagocytic cells, whereas in more distant loci they reveal a hypertrophied cell body and short ramifications. The same morphological difference is observed in vitro for purified microglia cultured with or without laminin. Strong, transient upregulation of LRP by activated spinal cord microglia is also induced by transection of the sciatic nerve that affects the spinal cord circuitry without blood-brain barrier dysruption. LRP expression is maximal by 1 week post-lesion, before becoming restricted to dorsal and ventral horns, sites of major structural reorganization. Our findings strongly suggest the involvement of LRP in lesion-induced activation and migration of microglia.
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Affiliation(s)
- Hasna Baloui
- Université Pierre et Marie Curie-Paris6, UMR7101 NSI; and CNRS, UMR7101 IFR-83, Paris, France
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Shehab SAS. Acute and chronic sectioning of fifth lumbar spinal nerve has equivalent effects on the primary afferents of sciatic nerve in rat spinal cord. J Comp Neurol 2009; 517:481-92. [PMID: 19790268 DOI: 10.1002/cne.22163] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The mechanism of neuropathic pain may be associated with sprouting of uninjured primary afferents of peripheral nerves into regions of the spinal cord denervated through peripheral injury. However, this remains controversial. Therefore, the purpose of the present investigation was, first, to determine in detail the central distributions of the unmyelinated primary afferents of each of the L4, L5, and L6 components of sciatic nerve, then to assess the distribution of afferent sciatic terminals following acute and chronic injury to (L5) nerve. First, we injected isolectin B4 (IB4), into the sciatic nerves in three groups of rats, each of which had two of the three L4, L5, or L6 components ligated and cut, and the one remaining, uninjured. Although the terminal labelling found in the L5 segment of the spinal cord originated from the L5 component, some terminal labelling remained in cases when either the L4 or L6 component was intact. Second, tracers transported in predominantly unmyelinated (IB4 and WGA-HRP) or myelinated (cholera toxin subunit B) nerves were injected into the sciatic nerve following acute or chronic (21-day) injury restricted to the L5 component. In each case, the central distribution of nerve terminals in the spinal dorsal horn was equivalent following either acute or chronic injury to the L5 component. Consequently, these data provide no support for the suggestion that neuropathic pain in spinal ligation model results from uninjured L4 and L6 components sprouting to occupy sites vacated by the injured L5 component of the sciatic nerve.
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Affiliation(s)
- Safa Aldeen S Shehab
- Department of Anatomy, Faculty of Medicine and Health Sciences, United Arab Emirates University, Al-Ain, United Arab Emirates.
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Central sensitization: a generator of pain hypersensitivity by central neural plasticity. THE JOURNAL OF PAIN 2009; 10:895-926. [PMID: 19712899 DOI: 10.1016/j.jpain.2009.06.012] [Citation(s) in RCA: 2262] [Impact Index Per Article: 150.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2009] [Revised: 06/08/2009] [Accepted: 06/08/2009] [Indexed: 02/08/2023]
Abstract
UNLABELLED Central sensitization represents an enhancement in the function of neurons and circuits in nociceptive pathways caused by increases in membrane excitability and synaptic efficacy as well as to reduced inhibition and is a manifestation of the remarkable plasticity of the somatosensory nervous system in response to activity, inflammation, and neural injury. The net effect of central sensitization is to recruit previously subthreshold synaptic inputs to nociceptive neurons, generating an increased or augmented action potential output: a state of facilitation, potentiation, augmentation, or amplification. Central sensitization is responsible for many of the temporal, spatial, and threshold changes in pain sensibility in acute and chronic clinical pain settings and exemplifies the fundamental contribution of the central nervous system to the generation of pain hypersensitivity. Because central sensitization results from changes in the properties of neurons in the central nervous system, the pain is no longer coupled, as acute nociceptive pain is, to the presence, intensity, or duration of noxious peripheral stimuli. Instead, central sensitization produces pain hypersensitivity by changing the sensory response elicited by normal inputs, including those that usually evoke innocuous sensations. PERSPECTIVE In this article, we review the major triggers that initiate and maintain central sensitization in healthy individuals in response to nociceptor input and in patients with inflammatory and neuropathic pain, emphasizing the fundamental contribution and multiple mechanisms of synaptic plasticity caused by changes in the density, nature, and properties of ionotropic and metabotropic glutamate receptors.
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Chakravarty A, Sen A. Migraine, neuropathic pain and nociceptive pain: towards a unifying concept. Med Hypotheses 2009; 74:225-31. [PMID: 19765908 DOI: 10.1016/j.mehy.2009.08.034] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2009] [Accepted: 08/19/2009] [Indexed: 01/24/2023]
Abstract
Migraine, neuropathic pain and nociceptive pain are the three commonest pain syndromes affecting human. In the present article, we first present the salient features of the pathophysiology of the three conditions particularly highlighting the core features that are similar in the three conditions. We argue on the validity of the prevailing concept that maintenance of structural integrity of the nervous system differentiates nociceptive pain from neuropathic pain and point out that the fundamental pathophysiology of lasting nociceptive pain (like cancer pain) and neuropathic pain (like nerve injury pain) is essentially same. Migraine pathophysiology is complex and complicated by two opposing views on site of migraine pain generation - peripheral versus central. We hypothesize that this dichotomy has resulted from focusing on two different sites on a single, somewhat complicated, pain mediating circuitry from the peripheral meningeal and vascular structures through several cell stations in the brain stem and thalamus up to the sensory cortical matrix. At the end, we suggest that fundamentally all the three pain syndromes referred to in the article share a common pathophysiological mechanism, namely peripheral pain perception, peripheral sensitization at dorsal root ganglion or its intracranial counterpart (like trigeminal ganglion) and central sensitization at the spinal cord (dorsal horn for somatic pain), brain stem nuclei and thalamus before final pain perception at the sensory cortical matrix.
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Affiliation(s)
- A Chakravarty
- Department of Neurology, Vivekananda Institute of Medical Sciences, Calcutta, India.
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Swartz JB, Weinreich D. Influence of vagotomy on monosynaptic transmission at second-order nucleus tractus solitarius synapses. J Neurophysiol 2009; 102:2846-55. [PMID: 19726730 DOI: 10.1152/jn.00168.2009] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Manipulations of vagal activity are used to treat medical pathologies, but the underlying CNS changes caused by these treatments are not well understood. Furthermore, heart and lung transplant as well as treatments for many gastrointestinal disorders result in section of the vagus nerve (vagotomy). Following unilateral vagotomy under isoflurane anesthesia of Sprague-Dawley rats, electrophysiological properties were recorded with whole cell patch techniques in horizontal brain stem slices. Vagotomy significantly reduced the median amplitude of evoked excitatory postsynaptic currents (evEPSCs; -121; n = 43) in the nucleus tractus solitarius (NTS) when compared with controls (-157 pA; n = 66; P < 0.05) but had no significant effect on the passive properties or on the average amplitude or frequency of miniature EPSCs. The degree of synaptic failure exhibited during a 50-Hz train of stimuli was used to define two separate classes of synapses: "low failure" and "high failure" (HF); failure rates <5 and > or =5%, respectively. HF synapses had significantly smaller median evEPSCs (-88 vs. -184 pA; P < 0.05). After vagotomy, the percentage of HF synapses nearly doubled to 56% (n = 24/43) when compared with controls (30%; n = 20/66). Additionally, the overall percentage of failures after the second to fifth stimuli significantly increased by at least twofold. These results suggest that vagotomy causes a decrease in synaptic efficacy by both increasing the overall percentage of synaptic failures and shifting the population of NTS synapses toward more HF transmission. In addition, the alterations due to vagotomy are likely to be presynaptic in nature.
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Affiliation(s)
- Jessica B Swartz
- Program in Neuroscience, University of Maryland, School of Medicine, Baltimore, Maryland, USA
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Abstract
Spinal cord injury research has greatly expanded in recent years, but our understanding of the mechanisms that underlie the functional recovery that can occur over the weeks and months following the initial injury, is far from complete. To grasp the scope of the problem, it is important to begin by defining the sensorimotor pathways that might be involved by a spinal injury. This is done in the rodent and nonhuman primate, which are two of the most commonly used animal models in basic and translational spinal injury research. Many of the better known experimentally induced models are then reviewed in terms of the pathways they involve and the reorganization and recovery that have been shown to follow. The better understood neuronal mechanisms mediating such post-injury plasticity, including dendritic spine growth and axonal sprouting, are then examined.
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Affiliation(s)
- Corinna Darian-Smith
- Department of Comparative Medicine, Stanford University School of Medicine, Stanford, California 94305, USA.
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Wu A, Lauschke JL, Morris R, Waite PM. Characterization of Rat Forepaw Function in Two Models of Cervical Dorsal Root Injury. J Neurotrauma 2009; 26:17-29. [DOI: 10.1089/neu.2008.0675] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Affiliation(s)
- Ann Wu
- Neural Injury Research Unit, School of Medical Sciences, University of New South Wales, New South Wales, Sydney, Australia
| | - Jenny L. Lauschke
- Neural Injury Research Unit, School of Medical Sciences, University of New South Wales, New South Wales, Sydney, Australia
| | - Renée Morris
- Neural Injury Research Unit, School of Medical Sciences, University of New South Wales, New South Wales, Sydney, Australia
| | - Phil M.E. Waite
- Neural Injury Research Unit, School of Medical Sciences, University of New South Wales, New South Wales, Sydney, Australia
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