1
|
Scholpa NE. Role of DNA methylation during recovery from spinal cord injury with and without β 2-adrenergic receptor agonism. Exp Neurol 2023; 368:114494. [PMID: 37488045 DOI: 10.1016/j.expneurol.2023.114494] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2023] [Revised: 07/14/2023] [Accepted: 07/20/2023] [Indexed: 07/26/2023]
Abstract
Daily treatment with the FDA-approved β2-adrenergic receptor agonist formoterol beginning 8 h after severe spinal cord injury (SCI) induces mitochondrial biogenesis and improves recovery in mice. We observed decreased DNA methyltransferase (DNMT) expression, global DNA methylation and methylation of the mitochondrial genes PGC-1α and NDUFS1 in the injury site of formoterol-treated mice 1 DPI, but this effect was lost by 7 DPI. To investigate the role of DNA methylation on recovery post-SCI, injured mice were treated daily with formoterol or vehicle, plus the DNMT inhibitor decitabine (DAC) on days 7-9. While DAC had no apparent effect on formoterol-induced recovery, mice treated with vehicle plus DAC exhibited increased BMS scores compared to vehicle alone beginning 15 DPI, reaching a degree of functional recovery similar to that of formoterol-treated mice by 21 DPI. Furthermore, DAC treatment increased injury site mitochondrial protein expression in vehicle-treated mice to levels comparable to that of formoterol-treated mice. The effect of DNMT inhibition on pain response with and without formoterol was assessed following moderate SCI. While all injured mice not treated with DAC displayed thermal hyperalgesia by 21 DPI, mice treated with formoterol exhibited decreased thermal hyperalgesia compared to vehicle-treated mice by 35 DPI. Injured mice treated with DAC, regardless of formoterol treatment, did not demonstrate thermal hyperalgesia at any time point assessed. Although these data do not suggest enhanced formoterol-induced recovery with DNMT inhibition, our findings indicate the importance of DNA methylation post-SCI and support both DNMT inhibition and formoterol as potential therapeutic avenues.
Collapse
Affiliation(s)
- Natalie E Scholpa
- Southern Arizona VA Health Care System, Tucson, AZ, United States of America; Department of Pharmacology and Toxicology, College of Pharmacy, University of Arizona, Tucson, AZ, United States of America.
| |
Collapse
|
2
|
Maugeri G, Amato A, Sortino M, D Agata V, Musumeci G. The Influence of Exercise on Oxidative Stress after Spinal Cord Injury: A Narrative Review. Antioxidants (Basel) 2023; 12:1401. [PMID: 37507940 PMCID: PMC10376509 DOI: 10.3390/antiox12071401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Revised: 06/30/2023] [Accepted: 07/05/2023] [Indexed: 07/30/2023] Open
Abstract
Spinal cord injury (SCI) is an irreversible disease resulting in partial or total loss of sensory and motor function. The pathophysiology of SCI is characterized by an initial primary injury phase followed by a secondary phase in which reactive oxygen species (ROSs) and associated oxidative stress play hallmark roles. Physical exercise is an indispensable means of promoting psychophysical well-being and improving quality of life. It positively influences the neuromuscular, cardiovascular, respiratory, and immune systems. Moreover, exercise may provide a mechanism to regulate the variation and equilibrium between pro-oxidants and antioxidants. After a brief overview of spinal cord anatomy and the different types of spinal cord injury, the purpose of this review is to investigate the evidence regarding the effect of exercise on oxidative stress among individuals with SCI.
Collapse
Affiliation(s)
- Grazia Maugeri
- Section of Anatomy, Histology and Movement Sciences, Department of Biomedical and Biotechnological Sciences, University of Catania, 95123 Catania, Italy
| | - Alessandra Amato
- Section of Anatomy, Histology and Movement Sciences, Department of Biomedical and Biotechnological Sciences, University of Catania, 95123 Catania, Italy
| | - Martina Sortino
- Section of Anatomy, Histology and Movement Sciences, Department of Biomedical and Biotechnological Sciences, University of Catania, 95123 Catania, Italy
| | - Velia D Agata
- Section of Anatomy, Histology and Movement Sciences, Department of Biomedical and Biotechnological Sciences, University of Catania, 95123 Catania, Italy
| | - Giuseppe Musumeci
- Section of Anatomy, Histology and Movement Sciences, Department of Biomedical and Biotechnological Sciences, University of Catania, 95123 Catania, Italy
- Research Center on Motor Activities (CRAM), University of Catania, 95123 Catania, Italy
| |
Collapse
|
3
|
The Impact of Activity-Based Interventions on Neuropathic Pain in Experimental Spinal Cord Injury. Cells 2022; 11:cells11193087. [PMID: 36231048 PMCID: PMC9563089 DOI: 10.3390/cells11193087] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Revised: 09/21/2022] [Accepted: 09/22/2022] [Indexed: 11/17/2022] Open
Abstract
Physical activity-based rehabilitative interventions represent the main treatment concept for people suffering from spinal cord injury (SCI). The role such interventions play in the relief of neuropathic pain (NP) states is emerging, along with underlying mechanisms resulting in SCI-induced NP (SCI-NP). Animal models have been used to investigate the benefits of activity-based interventions (ABI), such as treadmill training, wheel running, walking, swimming, and bipedal standing. These activity-based paradigms have been shown to modulate inflammatory-related alterations as well as induce functional and structural changes in the spinal cord gray matter circuitry correlated with pain behaviors. Thus far, the research available provides an incomplete picture of the cellular and molecular pathways involved in this beneficial effect. Continued research is essential for understanding how such interventions benefit SCI patients suffering from NP and allow the development of individualized rehabilitative therapies. This article reviews preclinical studies on this specific topic, goes over mechanisms involved in SCI-NP in relation to ABI, and then discusses the effectiveness of different activity-based paradigms as they relate to different forms, intensity, initiation times, and duration of ABI. This article also summarizes the mechanisms of respective interventions to ameliorate NP after SCI and provides suggestions for future research directions.
Collapse
|
4
|
Future Treatment of Neuropathic Pain in Spinal Cord Injury: The Challenges of Nanomedicine, Supplements or Opportunities? Biomedicines 2022; 10:biomedicines10061373. [PMID: 35740395 PMCID: PMC9219608 DOI: 10.3390/biomedicines10061373] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2022] [Revised: 05/28/2022] [Accepted: 06/08/2022] [Indexed: 12/12/2022] Open
Abstract
Neuropathic pain (NP) is a common chronic condition that severely affects patients with spinal cord injuries (SCI). It impairs the overall quality of life and is considered difficult to treat. Currently, clinical management of NP is often limited to drug therapy, primarily with opioid analgesics that have limited therapeutic efficacy. The persistence and intractability of NP following SCI and the potential health risks associated with opioids necessitate improved treatment approaches. Nanomedicine has gained increasing attention in recent years for its potential to improve therapeutic efficacy while minimizing toxicity by providing sensitive and targeted treatments that overcome the limitations of conventional pain medications. The current perspective begins with a brief discussion of the pathophysiological mechanisms underlying NP and the current pain treatment for SCI. We discuss the most frequently used nanomaterials in pain diagnosis and treatment as well as recent and ongoing efforts to effectively treat pain by proactively mediating pain signals following SCI. Although nanomedicine is a rapidly growing field, its application to NP in SCI is still limited. Therefore, additional work is required to improve the current treatment of NP following SCI.
Collapse
|
5
|
Tsivelekas KK, Evangelopoulos DS, Pallis D, Benetos IS, Papadakis SA, Vlamis J, Pneumaticos SG. Angiogenesis in Spinal Cord Injury: Progress and Treatment. Cureus 2022; 14:e25475. [PMID: 35800787 PMCID: PMC9246426 DOI: 10.7759/cureus.25475] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/29/2022] [Indexed: 11/22/2022] Open
Abstract
Traumatic spinal cord injury (SCI) provokes the onset of an intricate pathological process. Initial primary injury ruptures local micro-neuro-vascularcomplex triggering the commencement of multi-factorial secondary sequences which exert significant influence on neurological deterioration progress. Stimulating by local ischemia, neovascularization pathways emerge to provide neuroprotection and improve functional recovery. Although angiogenetic processes are prompted, newly formed vascular system is frequently inadequate to distribute sufficient blood supply and improve axonal recovery. Several treatment interventions have been endeavored to achieve the optimal conditions in SCI microenvironment, enhancing angiogenesis and improve functional recovery. In this study we review the revascularization pathogenesis and importance within the secondary processes and condense the proangiogenic influence of several angiogenetic-targeted treatment interventions.
Collapse
|
6
|
Stem Cell Secretome for Spinal Cord Repair: Is It More than Just a Random Baseline Set of Factors? Cells 2021; 10:cells10113214. [PMID: 34831436 PMCID: PMC8625005 DOI: 10.3390/cells10113214] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2021] [Revised: 11/02/2021] [Accepted: 11/16/2021] [Indexed: 11/29/2022] Open
Abstract
Hundreds of thousands of people suffer spinal cord injuries each year. The experimental application of stem cells following spinal cord injury has opened a new era to promote neuroprotection and neuroregeneration of damaged tissue. Currently, there is great interest in the intravenous administration of the secretome produced by mesenchymal stem cells in acute or subacute spinal cord injuries. However, it is important to highlight that undifferentiated neural stem cells and induced pluripotent stem cells are able to adapt to the damaged environment and produce the so-called lesion-induced secretome. This review article focuses on current research related to the secretome and the lesion-induced secretome and their roles in modulating spinal cord injury symptoms and functional recovery, emphasizing different compositions of the lesion-induced secretome in various models of spinal cord injury.
Collapse
|
7
|
Corticospinal Motor Circuit Plasticity After Spinal Cord Injury: Harnessing Neuroplasticity to Improve Functional Outcomes. Mol Neurobiol 2021; 58:5494-5516. [PMID: 34341881 DOI: 10.1007/s12035-021-02484-w] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Accepted: 07/07/2021] [Indexed: 10/20/2022]
Abstract
Spinal cord injury (SCI) is a devastating condition that affects approximately 294,000 people in the USA and several millions worldwide. The corticospinal motor circuitry plays a major role in controlling skilled movements and in planning and coordinating movements in mammals and can be damaged by SCI. While axonal regeneration of injured fibers over long distances is scarce in the adult CNS, substantial spontaneous neural reorganization and plasticity in the spared corticospinal motor circuitry has been shown in experimental SCI models, associated with functional recovery. Beneficially harnessing this neuroplasticity of the corticospinal motor circuitry represents a highly promising therapeutic approach for improving locomotor outcomes after SCI. Several different strategies have been used to date for this purpose including neuromodulation (spinal cord/brain stimulation strategies and brain-machine interfaces), rehabilitative training (targeting activity-dependent plasticity), stem cells and biological scaffolds, neuroregenerative/neuroprotective pharmacotherapies, and light-based therapies like photodynamic therapy (PDT) and photobiomodulation (PMBT). This review provides an overview of the spontaneous reorganization and neuroplasticity in the corticospinal motor circuitry after SCI and summarizes the various therapeutic approaches used to beneficially harness this neuroplasticity for functional recovery after SCI in preclinical animal model and clinical human patients' studies.
Collapse
|
8
|
Sex influence on sensory responses following spinothalamic tract injury in rats. PHYSIOLOGY AND PHARMACOLOGY 2021. [DOI: 10.52547/phypha.27.1.9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/14/2023]
|
9
|
Zhang Y, Al Mamun A, Yuan Y, Lu Q, Xiong J, Yang S, Wu C, Wu Y, Wang J. Acute spinal cord injury: Pathophysiology and pharmacological intervention (Review). Mol Med Rep 2021; 23:417. [PMID: 33846780 PMCID: PMC8025476 DOI: 10.3892/mmr.2021.12056] [Citation(s) in RCA: 53] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2020] [Accepted: 11/12/2020] [Indexed: 12/12/2022] Open
Abstract
Spinal cord injury (SCI) is one of the most debilitating of all the traumatic conditions that afflict individuals. For a number of years, extensive studies have been conducted to clarify the molecular mechanisms of SCI. Experimental and clinical studies have indicated that two phases, primary damage and secondary damage, are involved in SCI. The initial mechanical damage is caused by local impairment of the spinal cord. In addition, the fundamental mechanisms are associated with hyperflexion, hyperextension, axial loading and rotation. By contrast, secondary injury mechanisms are led by systemic and cellular factors, which may also be initiated by the primary injury. Although significant advances in supportive care have improved clinical outcomes in recent years, a number of studies continue to explore specific pharmacological therapies to minimize SCI. The present review summarized some important pathophysiologic mechanisms that are involved in SCI and focused on several pharmacological and non‑pharmacological therapies, which have either been previously investigated or have a potential in the management of this debilitating injury in the near future.
Collapse
Affiliation(s)
- Yi Zhang
- School of Chemical Engineering, Nanjing University of Science and Technology, Nanjing, Jiangsu 210094, P.R. China
- School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou, Zhejiang 325035, P.R. China
| | - Abdullah Al Mamun
- School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou, Zhejiang 325035, P.R. China
| | - Yuan Yuan
- School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou, Zhejiang 325035, P.R. China
| | - Qi Lu
- School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou, Zhejiang 325035, P.R. China
| | - Jun Xiong
- School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou, Zhejiang 325035, P.R. China
| | - Shulin Yang
- School of Chemical Engineering, Nanjing University of Science and Technology, Nanjing, Jiangsu 210094, P.R. China
| | - Chengbiao Wu
- School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou, Zhejiang 325035, P.R. China
| | - Yanqing Wu
- Institute of Life Sciences, Wenzhou University, Wenzhou, Zhejiang 325035, P.R. China
| | - Jian Wang
- Department of Hand Surgery and Peripheral Neurosurgery, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang 325035, P.R. China
| |
Collapse
|
10
|
Wang F, Zu Z, Wu TL, Yan X, Lu M, Yang PF, Byun NE, Reed JL, Gore JC, Chen LM. Sensitivity and specificity of CEST and NOE MRI in injured spinal cord in monkeys. NEUROIMAGE-CLINICAL 2021; 30:102633. [PMID: 33780866 PMCID: PMC8039857 DOI: 10.1016/j.nicl.2021.102633] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Revised: 02/18/2021] [Accepted: 03/12/2021] [Indexed: 11/04/2022]
Abstract
Compare sensitivity and specificity of CEST and NOE measures from 6-pool fitting. Differentiate regional molecular signatures at and around spinal cord injury. Provide parameters that improve the diagnostic accuracy of molecular alteration. Down-sampled data acquisition can capture the characteristic molecular profile. High translational potential for clinical assessment of spinal cord injury.
Purpose The sensitivity and accuracy of chemical exchange saturation transfer (CEST) and nuclear Overhauser enhancement (NOE) effects for assessing injury-associated changes in cervical spinal cords were evaluated in squirrel monkeys. Multiple interacting pools of protons, including one identified by an NOE at −1.6 ppm relative to water (NOE(-1.6)), were derived and quantified from fitting proton Z-spectra. The effects of down-sampled data acquisitions and corrections for non-specific factors including T1, semi-solid magnetization transfer, and direct saturation of free water (DS), were investigated. The overall goal is to develop a protocol for rapid data acquisition for assessing the molecular signatures of the injured spinal cord and its surrounding regions. Methods MRI scans were recorded of anesthetized squirrel monkeys at 9.4 T, before and after a unilateral dorsal column sectioning of the cervical spinal cord. Z-spectral images at 51 different RF offsets were acquired. The amplitudes of CEST and NOE effects from multiple proton pools were quantified using a six-pool Lorenzian fitting of each Z-spectrum (MTRmfit). In addition, down-sampled data using reduced selections of RF offsets were analyzed and compared. An apparent exchange-dependent relaxation (AREXmfit) method was also used to correct for non-specific factors in quantifying regional spectra around lesion sites. Results The parametric maps from multi-pool fitting using the complete sampling data (P51e) detected unilateral changes at and around the injury. The maps derived from selected twofold down-sampled data with appropriate interpolation (P26sI51) revealed quite similar spatial distributions of different pools as those obtained using P51e at each resonance shift. Across 10 subjects, both data acquisition schemes detected significant decreases in NOE(-3.5) and NOE(-1.6) and increases in DS(0.0) and CEST(3.5) at the lesion site relative to measures of the normal tissues before injury. AREXmfit of cysts and other abnormal tissues at and around the lesion site also exhibited significant changes, especially at 3.5, −1.6 and −3.5 ppm RF offsets. Conclusion These results confirm that a reduced set of RF offsets and down sampling are adequate for CEST imaging of injured spinal cord and allow shorter imaging times and/or permit additional signal averaging. AREXmfit correction improved the accuracy of CEST and NOE measures. The results provide a rapid (~13 mins), sensitive, and accurate protocol for deriving multiple NOE and CEST effects simultaneously in spinal cord imaging at high field.
Collapse
Affiliation(s)
- Feng Wang
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, USA; Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, TN, USA
| | - Zhongliang Zu
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, USA; Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, TN, USA
| | - Tung-Lin Wu
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, USA; Department of Biomedical Engineering, Vanderbilt University, TN, USA
| | - Xinqiang Yan
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, USA; Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, TN, USA
| | - Ming Lu
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, USA; Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, TN, USA
| | - Pai-Feng Yang
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, USA; Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, TN, USA
| | - Nellie E Byun
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, USA; Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, TN, USA
| | - Jamie L Reed
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, USA; Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, TN, USA
| | - John C Gore
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, USA; Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, TN, USA; Department of Biomedical Engineering, Vanderbilt University, TN, USA
| | - Li Min Chen
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, USA; Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, TN, USA.
| |
Collapse
|
11
|
Duan W, Huang Q, Chen Z, Raja SN, Yang F, Guan Y. Comparisons of motor and sensory abnormalities after lumbar and thoracic contusion spinal cord injury in male rats. Neurosci Lett 2019; 708:134358. [PMID: 31269465 DOI: 10.1016/j.neulet.2019.134358] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Revised: 06/25/2019] [Accepted: 06/28/2019] [Indexed: 12/23/2022]
Abstract
Rodent models of contusion spinal cord injury (SCI) are widely studied for the mechanisms underlying functional deficits after SCI. Yet, how does lesion level affect SCI-induced motor and sensory dysfunctions remains unclear. Using a computer-controlled impactor (Impact One™, Leica) and the same parameters (diameter, 2.0 mm; Speed: 4.0 m/s; Depth: 1.5 mm; Dwell time: 0.1 s), we produced contusions at mid-thoracic (T10) and rostral-lumbar (L2) spinal cord in male rats, and compared locomotor and sensory dysfunctions within the same experimental setting. The time courses of locomotor deficit were comparable between thoracic (n = 8) and lumbar (n = 7) SCI rats, but the severity was greater after thoracic SCI especially during the first week post-injury, as indicated by the lower Basso, Beattle and Bresnahan open-field locomotion scores. Both groups showed similar heightened avoiding response (hyper-reactivity) to mechanical stimulation applied at the hindpaws from day 21-56 post-injury, as indicated by decreased paw withdrawal thresholds. Compared to lumbar SCI, thoracic SCI induced a greater decrease of paw withdrawal latency in hot-plate test from day 28-56 post-injury. In contrast, lumbar SCI rats showed a greater reduction of avoidance threshold to mechanical stimulation at the girdle region, and larger overgroomed area than thoracic SCI rats at day 14 post-injury. Thus, thoracic SCI may induce greater motor deficits and hindpaw heat hyper-reactivity than did lumbar SCI. In contrast, lumbar SCI may elicit greater at-level mechanical hyper-reactivity and overgrooming behavior than thoracic SCI. Future study needs to examine the specific pathological changes underlying different dysfunctions in two SCI models.
Collapse
Affiliation(s)
- Wanru Duan
- Department of Neurosurgery, Xuanwu Hospital, Capital Medical University, Beijing, 100053, China; Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University, School of Medicine, Baltimore, Maryland, 21205, USA
| | - Qian Huang
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University, School of Medicine, Baltimore, Maryland, 21205, USA
| | - Zhiyong Chen
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University, School of Medicine, Baltimore, Maryland, 21205, USA
| | - Srinivasa N Raja
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University, School of Medicine, Baltimore, Maryland, 21205, USA
| | - Fei Yang
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University, School of Medicine, Baltimore, Maryland, 21205, USA; Department of Neurobiology, School of Basic Medical Sciences, Advanced Innovation Center for Human Brain Protection, Capital Medical University, Beijing, 100069, China
| | - Yun Guan
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University, School of Medicine, Baltimore, Maryland, 21205, USA; Department of Neurological Surgery, Johns Hopkins University, School of Medicine, Baltimore, Maryland, 21205, USA.
| |
Collapse
|
12
|
Park A, Uddin O, Li Y, Masri R, Keller A. Pain After Spinal Cord Injury Is Associated With Abnormal Presynaptic Inhibition in the Posterior Nucleus of the Thalamus. THE JOURNAL OF PAIN 2018; 19:727.e1-727.e15. [PMID: 29481977 DOI: 10.1016/j.jpain.2018.02.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2017] [Revised: 01/29/2018] [Accepted: 02/12/2018] [Indexed: 01/21/2023]
Abstract
Pain after spinal cord injury (SCI-Pain) is one of the most debilitating sequelae of spinal cord injury, characterized as relentless, excruciating pain that is largely refractory to treatments. Although it is generally agreed that SCI-Pain results from maladaptive plasticity in the pain processing pathway that includes the spinothalamic tract and somatosensory thalamus, the specific mechanisms underlying the development and maintenance of such pain are yet unclear. However, accumulating evidence suggests that SCI-Pain may be causally related to abnormal thalamic disinhibition, leading to hyperactivity in the posterior thalamic nucleus (PO), a higher-order nucleus involved in somatosensory and pain processing. We previously described several presynaptic mechanisms by which activity in PO is regulated, including the regulation of GABAergic as well as glutamatergic release by presynaptic metabotropic gamma-aminobutyric acid (GABAB) receptors. Using acute slices from a mouse model of SCI-Pain, we tested whether such mechanisms are affected by SCI-Pain. We reveal 2 abnormal changes in presynaptic signaling in the SCI-Pain condition. The substantial tonic activation of presynaptic GABAB receptors on GABAergic projections to PO-characteristic of normal animals-was absent in mice with SCI-Pain. Also absent in mice with SCI-Pain was the normal presynaptic regulation of glutamatergic projections to the PO by GABAB receptors. The loss of these regulatory presynaptic mechanisms in SCI-Pain may be an element of maladaptive plasticity leading to PO hyperexcitability and behavioral pain, and may suggest targets for development of novel treatments. PERSPECTIVE This report presents synaptic mechanisms that may underlie the development and maintenance of SCI-Pain. Because of the difficulty in treating SCI-Pain, a better understanding of the underlying neurobiological mechanisms is critical, and may allow development of better treatment modalities.
Collapse
Affiliation(s)
- Anthony Park
- Program in Neuroscience and Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, Maryland
| | - Olivia Uddin
- Program in Neuroscience and Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, Maryland
| | - Ying Li
- Program in Neuroscience and Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, Maryland
| | - Radi Masri
- Program in Neuroscience and Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, Maryland; Department of Endodontics, Periodontics and Prosthodontics, University of Maryland Baltimore, School of Dentistry, Baltimore, Maryland
| | - Asaf Keller
- Program in Neuroscience and Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, Maryland.
| |
Collapse
|
13
|
Neuronal-Glial Interactions Maintain Chronic Neuropathic Pain after Spinal Cord Injury. Neural Plast 2017; 2017:2480689. [PMID: 28951789 PMCID: PMC5603132 DOI: 10.1155/2017/2480689] [Citation(s) in RCA: 76] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2017] [Revised: 06/26/2017] [Accepted: 07/05/2017] [Indexed: 02/01/2023] Open
Abstract
The hyperactive state of sensory neurons in the spinal cord enhances pain transmission. Spinal glial cells have also been implicated in enhanced excitability of spinal dorsal horn neurons, resulting in pain amplification and distortions. Traumatic injuries of the neural system such as spinal cord injury (SCI) induce neuronal hyperactivity and glial activation, causing maladaptive synaptic plasticity in the spinal cord. Recent studies demonstrate that SCI causes persistent glial activation with concomitant neuronal hyperactivity, thus providing the substrate for central neuropathic pain. Hyperactive sensory neurons and activated glial cells increase intracellular and extracellular glutamate, neuropeptides, adenosine triphosphates, proinflammatory cytokines, and reactive oxygen species concentrations, all of which enhance pain transmission. In addition, hyperactive sensory neurons and glial cells overexpress receptors and ion channels that maintain this enhanced pain transmission. Therefore, post-SCI neuronal-glial interactions create maladaptive synaptic circuits and activate intracellular signaling events that permanently contribute to enhanced neuropathic pain. In this review, we describe how hyperactivity of sensory neurons contributes to the maintenance of chronic neuropathic pain via neuronal-glial interactions following SCI.
Collapse
|
14
|
Wang F, Zu Z, Wu R, Wu TL, Gore JC, Chen LM. MRI evaluation of regional and longitudinal changes in Z-spectra of injured spinal cord of monkeys. Magn Reson Med 2017; 79:1070-1082. [PMID: 28547862 DOI: 10.1002/mrm.26756] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2017] [Revised: 04/21/2017] [Accepted: 04/22/2017] [Indexed: 01/21/2023]
Abstract
PURPOSE In principle, MR methods that exploit magnetization transfer (MT) may be used to quantify changes in the molecular composition of tissues after injury. The ability to track such changes in injured spinal cord may allow more precise assessment of the state of neural tissues. METHODS Z-Spectra were obtained from the cervical spinal cord before and after a unilateral dorsal column lesion in monkeys at 9.4T. The amplitudes of chemical exchange saturation transfer (CEST) and nuclear Overhauser enhancement (NOE) effects from multiple proton pools, along with nonspecific semisolid MT effects from immobile macromolecules, were quantified using a five-peak Lorenzian fitting of each Z-spectrum. RESULTS Abnormal tissues/cysts that formed around lesion sites exhibited relatively low correlations between their Z-spectra and that of normal gray matter (GM). Compared with normal GM, cysts showed strong CEST but weak semisolid MT and NOE effects after injury. The abnormal tissues around lesion sites were heterogeneous and showed different regional Z-spectra. Different regional correlations between proton pools were observed. Longitudinally, injured spinal cord tissue exhibited remarkable recovery in all subjects. CONCLUSION Characterization of multiple proton pools from Z-spectra permitted noninvasive, regional, quantitative assessments of changes in tissue composition of injured spinal cord over time. Magn Reson Med 79:1070-1082, 2018. © 2017 International Society for Magnetic Resonance in Medicine.
Collapse
Affiliation(s)
- Feng Wang
- Institute of Imaging Science, Vanderbilt University, Nashville, Tennessee, USA.,Department of Radiology and Radiological Sciences, Vanderbilt University, Nashville, Tennessee, USA
| | - Zhongliang Zu
- Institute of Imaging Science, Vanderbilt University, Nashville, Tennessee, USA.,Department of Radiology and Radiological Sciences, Vanderbilt University, Nashville, Tennessee, USA
| | - Ruiqi Wu
- Institute of Imaging Science, Vanderbilt University, Nashville, Tennessee, USA.,Department of Radiology and Radiological Sciences, Vanderbilt University, Nashville, Tennessee, USA
| | - Tung-Lin Wu
- Institute of Imaging Science, Vanderbilt University, Nashville, Tennessee, USA.,Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee, USA
| | - John C Gore
- Institute of Imaging Science, Vanderbilt University, Nashville, Tennessee, USA.,Department of Radiology and Radiological Sciences, Vanderbilt University, Nashville, Tennessee, USA.,Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee, USA
| | - Li Min Chen
- Institute of Imaging Science, Vanderbilt University, Nashville, Tennessee, USA.,Department of Radiology and Radiological Sciences, Vanderbilt University, Nashville, Tennessee, USA
| |
Collapse
|
15
|
Li XM, Meng J, Li LT, Guo T, Yang LK, Shi QX, Li XB, Chen Y, Yang Q, Zhao JN. Effect of ZBD-2 on chronic pain, depressive-like behaviors, and recovery of motor function following spinal cord injury in mice. Behav Brain Res 2017; 322:92-99. [PMID: 28108322 PMCID: PMC5339413 DOI: 10.1016/j.bbr.2017.01.025] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Revised: 01/09/2017] [Accepted: 01/12/2017] [Indexed: 02/06/2023]
Abstract
ZBD-2 significantly attenuated the symptoms of chronic SCI-pain and pain-induced depressive-like behaviors. ZBD-2 inhibited the decreases in the expression of synaptic plasticity-related signaling proteins. ZBD-2 reversed chronic, SCI-induced gliocyte activation at the lesion site.
In addition to debilitating sensory and motor deficits, patients with spinal cord injury (SCI) may experience chronic hyperpathic pain (SCI-pain). Recent studies have revealed that translocator protein (TSPO) is involved in repairing neural cells as well as reducing anxiety and depression. However, the role of TSPO in SCI-pain and pain-induced depression remains unknown. The present study aimed to determine the effects of a new TSPO ligand, ZBD-2, on SCI-pain and consequent pain-induced depressive-like behaviors in mice. Treatment with ZBD-2 at either dose significantly attenuated the symptoms of chronic SCI-pain and pain-induced depressive-like behaviors. ZBD-2 reversed SCI-induced elevation of serum corticosterone levels, an index of hyper-activation of the hypothalamic–pituitary–adrenal (HPA) axis. Additionally, administration of ZBD-2 inhibited decreases in the expression of synaptic plasticity-related signaling proteins, including brain-derived neurotrophic factor (BDNF) and cyclic AMP-responsive element binding protein (CREB). Moreover, ZBD-2 administration reversed chronic, SCI-induced gliocyte activation at the lesion site. Therefore, ZBD-2 may improve chronic SCI-pain and pain-induced depressive-like behaviors via suppression of gliocyte activation and restoration of the synaptic plasticity-related signaling systems.
Collapse
Affiliation(s)
- Xiao-Ming Li
- Department of Orthopedics, Jinling Hospital, Clinical School of Nanjing, Second Military Medical University, Nanjing, 210002, China
| | - Jia Meng
- Department of Orthopedics, Jinling Hospital, Clinical School of Nanjing, Second Military Medical University, Nanjing, 210002, China
| | - Lin Tao Li
- Department of Orthopedics, Jinling Hospital, Clinical School of Nanjing, Second Military Medical University, Nanjing, 210002, China
| | - Ting Guo
- Department of Orthopedics, Jinling Hospital, Clinical School of Nanjing, Second Military Medical University, Nanjing, 210002, China
| | - Liu-Kun Yang
- Department of Pharmacology, School of Pharmacy, Fourth Military Medical University, Xi'an, 710032, China
| | - Qi-Xin Shi
- Department of Pharmacology, School of Pharmacy, Fourth Military Medical University, Xi'an, 710032, China
| | - Xu-Bo Li
- Department of Pharmacology, School of Pharmacy, Fourth Military Medical University, Xi'an, 710032, China
| | - Yong Chen
- Department of Orthopedics, Jinling Hospital, Clinical School of Nanjing, Second Military Medical University, Nanjing, 210002, China.
| | - Qi Yang
- Department of Pharmacology, School of Pharmacy, Fourth Military Medical University, Xi'an, 710032, China.
| | - Jian-Ning Zhao
- Department of Orthopedics, Jinling Hospital, Clinical School of Nanjing, Second Military Medical University, Nanjing, 210002, China.
| |
Collapse
|
16
|
Moon HC, Lee YJ, Cho CB, Park YS. Suppressed GABAergic signaling in the zona incerta causes neuropathic pain in a thoracic hemisection spinal cord injury rat model. Neurosci Lett 2016; 632:55-61. [DOI: 10.1016/j.neulet.2016.08.035] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Revised: 08/19/2016] [Accepted: 08/20/2016] [Indexed: 01/01/2023]
|
17
|
Kramer JLK, Minhas NK, Jutzeler CR, Erskine ELKS, Liu LJW, Ramer MS. Neuropathic pain following traumatic spinal cord injury: Models, measurement, and mechanisms. J Neurosci Res 2016; 95:1295-1306. [PMID: 27617844 DOI: 10.1002/jnr.23881] [Citation(s) in RCA: 72] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Revised: 07/19/2016] [Accepted: 07/19/2016] [Indexed: 02/06/2023]
Abstract
Neuropathic pain following spinal cord injury (SCI) is notoriously difficult to treat and is a high priority for many in the SCI population. Resolving this issue requires animal models fidelic to the clinical situation in terms of injury mechanism and pain phenotype. This Review discusses the means by which neuropathic pain has been induced and measured in experimental SCI and compares these with human outcomes, showing that there is a substantial disconnection between experimental investigations and clinical findings in a number of features. Clinical injury level is predominantly cervical, whereas injury in the laboratory is modeled mainly at the thoracic cord. Neuropathic pain is primarily spontaneous or tonic in people with SCI (with a relatively smaller incidence of allodynia), but measures of evoked responses (to thermal and mechanical stimuli) are almost exclusively used in animals. There is even the question of whether pain per se has been under investigation in most experimental SCI studies rather than simply enhanced reflex activity with no affective component. This Review also summarizes some of the problems related to clinical assessment of neuropathic pain and how advanced imaging techniques may circumvent a lack of patient/clinician objectivity and discusses possible etiologies of neuropathic pain following SCI based on evidence from both clinical studies and animal models, with examples of cellular and molecular changes drawn from the entire neuraxis from primary afferent terminals to cortical sensory and affective centers. © 2016 Wiley Periodicals, Inc.
Collapse
Affiliation(s)
- John L K Kramer
- International Collaboration on Repair Discoveries, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Nikita K Minhas
- International Collaboration on Repair Discoveries, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Catherine R Jutzeler
- International Collaboration on Repair Discoveries, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Erin L K S Erskine
- International Collaboration on Repair Discoveries, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Lisa J W Liu
- International Collaboration on Repair Discoveries, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Matt S Ramer
- International Collaboration on Repair Discoveries, The University of British Columbia, Vancouver, British Columbia, Canada
| |
Collapse
|
18
|
Hu D, Zhu S, Potas JR. Red LED photobiomodulation reduces pain hypersensitivity and improves sensorimotor function following mild T10 hemicontusion spinal cord injury. J Neuroinflammation 2016; 13:200. [PMID: 27561854 PMCID: PMC5000419 DOI: 10.1186/s12974-016-0679-3] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2016] [Accepted: 08/17/2016] [Indexed: 12/20/2022] Open
Abstract
Background The development of hypersensitivity following spinal cord injury can result in incurable persistent neuropathic pain. Our objective was to examine the effect of red light therapy on the development of hypersensitivity and sensorimotor function, as well as on microglia/macrophage subpopulations following spinal cord injury. Methods Wistar rats were treated (or sham treated) daily for 30 min with an LED red (670 nm) light source (35 mW/cm2), transcutaneously applied to the dorsal surface, following a mild T10 hemicontusion injury (or sham injury). The development of hypersensitivity was assessed and sensorimotor function established using locomotor recovery and electrophysiology of dorsal column pathways. Immunohistochemistry and TUNEL were performed to examine cellular changes in the spinal cord. Results We demonstrate that red light penetrates through the entire rat spinal cord and significantly reduces signs of hypersensitivity following a mild T10 hemicontusion spinal cord injury. This is accompanied with improved dorsal column pathway functional integrity and locomotor recovery. The functional improvements were preceded by a significant reduction of dying (TUNEL+) cells and activated microglia/macrophages (ED1+) in the spinal cord. The remaining activated microglia/macrophages were predominantly of the anti-inflammatory/wound-healing subpopulation (Arginase1+ED1+) which were expressed early, and up to sevenfold greater than that found in sham-treated animals. Conclusions These findings demonstrate that a simple yet inexpensive treatment regime of red light reduces the development of hypersensitivity along with sensorimotor improvements following spinal cord injury and may therefore offer new hope for a currently treatment-resistant pain condition.
Collapse
Affiliation(s)
- Di Hu
- The John Curtin School of Medical Research, The Australian National University, Building 131, Garran Rd, Canberra, ACT 2601, Australia
| | - Shuyu Zhu
- The John Curtin School of Medical Research, The Australian National University, Building 131, Garran Rd, Canberra, ACT 2601, Australia
| | - Jason Robert Potas
- The John Curtin School of Medical Research, The Australian National University, Building 131, Garran Rd, Canberra, ACT 2601, Australia. .,ANU Medical School, The Australian National University, Canberra, ACT 2601, Australia.
| |
Collapse
|
19
|
Wang F, Qi HX, Zu Z, Mishra A, Tang C, Gore JC, Chen LM. Multiparametric MRI reveals dynamic changes in molecular signatures of injured spinal cord in monkeys. Magn Reson Med 2014; 74:1125-37. [PMID: 25334025 DOI: 10.1002/mrm.25488] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2014] [Revised: 08/08/2014] [Accepted: 09/17/2014] [Indexed: 11/06/2022]
Abstract
PURPOSE To monitor the spontaneous recovery of cervical spinal cord injury (SCI) using longitudinal multiparametric MRI methods. METHODS Quantitative MRI imaging including diffusion tensor imaging, magnetization transfer (MT), and chemical exchange saturation transfer (CEST) were conducted in anesthetized squirrel monkeys at 9.4T. The structural, cellular, and molecular features of the spinal cord were examined before and at different time points after a dorsal column lesion in each monkey. RESULTS Images with MT contrast enhanced visualization of the gray and white matter boundaries and the lesion and permitted differentiation of core and rim compartments within an abnormal volume (AV). In the early weeks after SCI, both core and rim exhibited low cellular density and low protein content, with high levels of exchanging hydroxyl, amine, and amide protons, as evidenced by increased apparent diffusion coefficient, decreased fractional anisotropy, decreased MT ratio, decreased nuclear Overhauser effect, and large CEST effects. Over time, cellular density and fiber density increased, whereas amide, amine, and hydroxyl levels dropped significantly, but at differing rates. Histology confirmed the nature of the AV to be a cyst. CONCLUSION Multiparametric MRI offers a novel method to quantify the spontaneous changes in structure and cellular and molecular compositions of SC during spontaneous recovery from injury.
Collapse
Affiliation(s)
- Feng Wang
- Institute of Imaging Science, Vanderbilt University, Nashville, Tennessee, USA.,Department of Radiology and Radiological Sciences, Vanderbilt University, Nashville, Tennessee, USA
| | - Hui-Xin Qi
- Department of Psychology, Vanderbilt University, Nashville, Tennessee, USA
| | - Zhongliang Zu
- Institute of Imaging Science, Vanderbilt University, Nashville, Tennessee, USA.,Department of Radiology and Radiological Sciences, Vanderbilt University, Nashville, Tennessee, USA
| | - Arabinda Mishra
- Institute of Imaging Science, Vanderbilt University, Nashville, Tennessee, USA.,Department of Radiology and Radiological Sciences, Vanderbilt University, Nashville, Tennessee, USA
| | - Chaohui Tang
- Institute of Imaging Science, Vanderbilt University, Nashville, Tennessee, USA.,Department of Radiology and Radiological Sciences, Vanderbilt University, Nashville, Tennessee, USA
| | - John C Gore
- Institute of Imaging Science, Vanderbilt University, Nashville, Tennessee, USA.,Department of Radiology and Radiological Sciences, Vanderbilt University, Nashville, Tennessee, USA.,Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee, USA
| | - Li Min Chen
- Institute of Imaging Science, Vanderbilt University, Nashville, Tennessee, USA.,Department of Radiology and Radiological Sciences, Vanderbilt University, Nashville, Tennessee, USA.,Department of Psychology, Vanderbilt University, Nashville, Tennessee, USA
| |
Collapse
|
20
|
Liu S, Li C, Xing Y, Tao F. Effect of microenvironment modulation on stem cell therapy for spinal cord injury pain. Neural Regen Res 2014; 9:458-9. [PMID: 25206837 PMCID: PMC4153499 DOI: 10.4103/1673-5374.130057] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/02/2014] [Indexed: 11/17/2022] Open
Affiliation(s)
- Sufang Liu
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA ; Basic Medical College, Zhengzhou University, Zhengzhou, Henan Province, China
| | - Changsheng Li
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA ; Basic Medical College, Zhengzhou University, Zhengzhou, Henan Province, China
| | - Ying Xing
- Basic Medical College, Zhengzhou University, Zhengzhou, Henan Province, China ; Basic Medical College, Xinxiang Medical University, Xinxiang, Henan Province, China
| | - Feng Tao
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
| |
Collapse
|
21
|
Widerström-Noga E. Multidimensional clinical pain phenotypes after spinal cord injury. Pain Manag 2014; 2:467-78. [PMID: 24645863 DOI: 10.2217/pmt.12.44] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
SUMMARY Persistent neuropathic pain after spinal cord injury (SCI) is a serious problem that significantly affects general health and wellbeing over and above what is caused by other medical consequences after SCI. The ideal approach to the management of the neuropathic pain conditions after SCI would be to identify the primary contributing mechanisms of pain in each person and tailor the treatment to these. However, despite significant basic and clinical research progress, this approach remains elusive. One strategy to further this effort is to define neuropathic pain phenotypes based on pain symptoms, sensory function/dysfunction and psychosocial factors, and determine the relationship between these and treatment outcomes and biomarkers including brain imaging. This approach will facilitate the interaction between basic and clinical science and translational research, further the understanding of the mechanisms that contribute to the development and maintenance of neuropathic pain after SCI, and thus the development of effective mechanisms-based pain treatment strategies.
Collapse
Affiliation(s)
- Eva Widerström-Noga
- The Miami Project to Cure Paralysis, Miller School of Medicine, University of Miami, LPLC (R-48) and Departments of Neurological Surgery & Rehabilitation Medicine, Miller School of Medicine, University of Miami, LPLC (R-48), 1095 NW, 14th Terrace Miami, FL 33136, USA.
| |
Collapse
|
22
|
M'Dahoma S, Bourgoin S, Kayser V, Barthélémy S, Chevarin C, Chali F, Orsal D, Hamon M. Spinal cord transection-induced allodynia in rats--behavioral, physiopathological and pharmacological characterization. PLoS One 2014; 9:e102027. [PMID: 25019623 PMCID: PMC4096923 DOI: 10.1371/journal.pone.0102027] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2013] [Accepted: 06/14/2014] [Indexed: 12/31/2022] Open
Abstract
In humans, spinal cord lesions induce not only major motor and neurovegetative deficits but also severe neuropathic pain which is mostly resistant to classical analgesics. Better treatments can be expected from precise characterization of underlying physiopathological mechanisms. This led us to thoroughly investigate (i) mechanical and thermal sensory alterations, (ii) responses to acute treatments with drugs having patent or potential anti-allodynic properties and (iii) the spinal/ganglion expression of transcripts encoding markers of neuronal injury, microglia and astrocyte activation in rats that underwent complete spinal cord transection (SCT). SCT was performed at thoracic T8-T9 level under deep isoflurane anaesthesia, and SCT rats were examined for up to two months post surgery. SCT induced a marked hyper-reflexia at hindpaws and strong mechanical and cold allodynia in a limited (6 cm2) cutaneous territory just rostral to the lesion site. At this level, pressure threshold value to trigger nocifensive reactions to locally applied von Frey filaments was 100-fold lower in SCT- versus sham-operated rats. A marked up-regulation of mRNAs encoding ATF3 (neuronal injury) and glial activation markers (OX-42, GFAP, P2×4, P2×7, TLR4) was observed in spinal cord and/or dorsal root ganglia at T6-T11 levels from day 2 up to day 60 post surgery. Transcripts encoding the proinflammatory cytokines IL-1β, IL-6 and TNF-α were also markedly but differentially up-regulated at T6-T11 levels in SCT rats. Acute treatment with ketamine (50 mg/kg i.p.), morphine (3-10 mg/kg s.c.) and tapentadol (10-20 mg/kg i.p.) significantly increased pressure threshold to trigger nocifensive reaction in the von Frey filaments test, whereas amitriptyline, pregabalin, gabapentin and clonazepam were ineffective. Because all SCT rats developed long lasting, reproducible and stable allodynia, which could be alleviated by drugs effective in humans, thoracic cord transection might be a reliable model for testing innovative therapies aimed at reducing spinal cord lesion-induced central neuropathic pain.
Collapse
Affiliation(s)
- Saïd M'Dahoma
- Centre de Psychiatrie et Neurosciences, Institut National de la Santé et de la Recherche Médicale, INSERM U894, Université Paris Descartes, Paris, France
- Neuropsychopharmacologie, Faculté de Médecine Pierre et Marie Curie, site Pitié-Salpêtrière, Paris, France
- * E-mail:
| | - Sylvie Bourgoin
- Centre de Psychiatrie et Neurosciences, Institut National de la Santé et de la Recherche Médicale, INSERM U894, Université Paris Descartes, Paris, France
- Neuropsychopharmacologie, Faculté de Médecine Pierre et Marie Curie, site Pitié-Salpêtrière, Paris, France
| | - Valérie Kayser
- Centre de Psychiatrie et Neurosciences, Institut National de la Santé et de la Recherche Médicale, INSERM U894, Université Paris Descartes, Paris, France
- Neuropsychopharmacologie, Faculté de Médecine Pierre et Marie Curie, site Pitié-Salpêtrière, Paris, France
| | - Sandrine Barthélémy
- Centre de Psychiatrie et Neurosciences, Institut National de la Santé et de la Recherche Médicale, INSERM U894, Université Paris Descartes, Paris, France
- Neuropsychopharmacologie, Faculté de Médecine Pierre et Marie Curie, site Pitié-Salpêtrière, Paris, France
| | - Caroline Chevarin
- Centre de Psychiatrie et Neurosciences, Institut National de la Santé et de la Recherche Médicale, INSERM U894, Université Paris Descartes, Paris, France
- Neuropsychopharmacologie, Faculté de Médecine Pierre et Marie Curie, site Pitié-Salpêtrière, Paris, France
| | - Farah Chali
- Laboratoire de Neurobiologie des Signaux Intercellulaires, Centre National de la Recherche Scientifique, CNRS UMR 7101, Université Pierre et Marie Curie, Paris, France
| | - Didier Orsal
- Laboratoire de Neurobiologie des Signaux Intercellulaires, Centre National de la Recherche Scientifique, CNRS UMR 7101, Université Pierre et Marie Curie, Paris, France
| | - Michel Hamon
- Centre de Psychiatrie et Neurosciences, Institut National de la Santé et de la Recherche Médicale, INSERM U894, Université Paris Descartes, Paris, France
- Neuropsychopharmacologie, Faculté de Médecine Pierre et Marie Curie, site Pitié-Salpêtrière, Paris, France
| |
Collapse
|
23
|
Ghanbari A, Asgari AR, Kaka GR, Falahatpishe HR, Naderi A, Jorjani M. In vivo microdialysis of glutamate in ventroposterolateral nucleus of thalamus following electrolytic lesion of spinothalamic tract in rats. Exp Brain Res 2013; 232:415-21. [PMID: 24186197 DOI: 10.1007/s00221-013-3749-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2013] [Accepted: 10/14/2013] [Indexed: 01/08/2023]
Abstract
Central pain is one of the most important complications after spinal cord injury (SCI), and thereby, its treatment raises many challenges. After SCI, in a cascade of molecular events, a marked increase in glutamate at the injury site results in secondary changes which may impact on supraspinal regions, mainly ventroposterolateral (VPL). There is little information about the changes in glutamate metabolism in the VPL and whether it contributes to SCI-related central pain. The present study was performed to evaluate glutamate release in the VPL following electrolytic lesion of spinothalamic tract (STT). A laminectomy was performed at spinal segments of T9-T10 in male rats, and then, unilateral electrolytic lesions were made in the STT. Glutamate concentrations in ipsilateral VPL dialysate were measured by HPLC method at days 3, 7, 14, 21 and 28 post-injury. Tactile pain and motor activity were also examined. Glutamate levels were significantly increased in ipsilateral VPL of spinal-cord-injured rats 2 weeks after SCI and remained high up to day 28 post-surgery. The STT lesions had no marked effect on our measures of motor activity, but there was a significant decrease in paw withdrawal threshold in the hind paws at day 14 post-SCI. These findings suggest that an increased release of glutamate in VPL plays a role in secondary pathologic changes, leading to neuronal hyperexcitation and neuropathic pain after SCI.
Collapse
Affiliation(s)
- A Ghanbari
- Applied Neuroscience Research Center, Baqiyatallah University of Medical Sciences, Tehran, Iran
| | | | | | | | | | | |
Collapse
|
24
|
Figueroa JD, Cordero K, Serrano-Illan M, Almeyda A, Baldeosingh K, Almaguel FG, De Leon M. Metabolomics uncovers dietary omega-3 fatty acid-derived metabolites implicated in anti-nociceptive responses after experimental spinal cord injury. Neuroscience 2013; 255:1-18. [PMID: 24042033 DOI: 10.1016/j.neuroscience.2013.09.012] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2013] [Revised: 09/03/2013] [Accepted: 09/04/2013] [Indexed: 01/23/2023]
Abstract
Chronic neuropathic pain is a frequent comorbidity following spinal cord injury (SCI) and often fails to respond to conventional pain management strategies. Preventive administration of docosahexaenoic acid (DHA) or the consumption of a diet rich in omega-3 polyunsaturated fatty acids (O3PUFAs) confers potent prophylaxis against SCI and improves functional recovery. The present study examines whether this novel dietary strategy provides significant antinociceptive benefits in rats experiencing SCI-induced pain. Rats were fed control chow or chow enriched with O3PUFAs for 8weeks before being subjected to sham or cord contusion surgeries, continuing the same diets after surgery for another 8 more weeks. The paw sensitivity to noxious heat was quantified for at least 8weeks post-SCI using the Hargreaves test. We found that SCI rats consuming the preventive O3PUFA-enriched diet exhibited a significant reduction in thermal hyperalgesia compared to those consuming the normal diet. Functional neurometabolomic profiling revealed a distinctive deregulation in the metabolism of endocannabinoids (eCB) and related N-acyl ethanolamines (NAEs) at 8weeks post-SCI. We found that O3PUFAs consumption led to a robust accumulation of novel NAE precursors, including the glycerophospho-containing docosahexaenoyl ethanolamine (DHEA), docosapentaenoyl ethanolamine (DPEA), and eicosapentaenoyl ethanolamine (EPEA). The tissue levels of these metabolites were significantly correlated with the antihyperalgesic phenotype. In addition, rats consuming the O3PUFA-rich diet showed reduced sprouting of nociceptive fibers containing CGRP and dorsal horn neuron p38 mitogen-activated protein kinase (MAPK) expression, well-established biomarkers of pain. The spinal cord levels of inositols were positively correlated with thermal hyperalgesia, supporting their role as biomarkers of chronic neuropathic pain. Notably, the O3PUFA-rich dietary intervention reduced the levels of these metabolites. Collectively, these results demonstrate the prophylactic value of dietary O3PUFA against SCI-mediated chronic pain.
Collapse
Affiliation(s)
- J D Figueroa
- Center for Health Disparities and Molecular Medicine, Loma Linda University, Loma Linda, CA, United States; Department of Basic Sciences, Loma Linda University, Loma Linda, CA, United States; Department of Pathology and Human Anatomy, Loma Linda University, Loma Linda, CA, United States
| | | | | | | | | | | | | |
Collapse
|
25
|
Vierck CJ, King CD, Berens SA, Yezierski RP. Excitotoxic injury to thoracolumbar gray matter alters sympathetic activation and thermal pain sensitivity. Exp Brain Res 2013; 231:19-26. [PMID: 23925342 DOI: 10.1007/s00221-013-3666-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2013] [Accepted: 07/28/2013] [Indexed: 11/29/2022]
Abstract
Studies of humans, monkeys and rodents have implicated combined gray and white matter damage as important for development of chronic pain following spinal cord injury (SCI). Below-level chronic pain and hyperalgesia following injury to the spinal white matter, including the spinothalamic tract (STT), can be enhanced by excitotoxic influences within the gray matter at the site of SCI. Also, excitotoxic injury of thoracic gray matter without interruption of the STT results in below-level heat hyperalgesia. The present study evaluates the possibility that thoracolumbar gray matter injury increases sensitivity to nociceptive heat stimulation by altering spinal sympathetic outflow. Thermal preferences of rats for heat (45 °C) versus cold (15 °C) were evaluated before and after thoracolumbar injections of quisqualic acid (QUIS). A pre-injury preference for heat changed to a post-injury preference for cold. Systemic activation of the sympathetic nervous system by restraint stress decreased the heat preference pre-injury and increased the cold preference post-injury. The heat aversive effect of stress was magnified and prolonged post-injury, compared to pre-injury. Also, peripheral sympathetic activation by nociceptive stimulation was evaluated pre- and post-injury by measuring thermal transfer through a hindpaw during stimulation with 44.5 °C. Skin temperature recordings revealed enhanced sympathetic activation by nociceptive heat stimulation following spinal QUIS injury. However, increased sympathetic activation with peripheral vasoconstriction should enhance cold aversion, in contrast to the observed increase in heat aversion. Thus, peripheral sympathetic vasoconstriction can be ruled out as a mechanism for heat hyperalgesia following excitotoxic gray matter injury.
Collapse
Affiliation(s)
- Charles J Vierck
- Department of Neuroscience, College of Medicine, University of Florida, Gainesville, FL, 32610, USA,
| | | | | | | |
Collapse
|
26
|
Wu J, Raver C, Piao C, Keller A, Faden AI. Cell cycle activation contributes to increased neuronal activity in the posterior thalamic nucleus and associated chronic hyperesthesia after rat spinal cord contusion. Neurotherapeutics 2013; 10:520-38. [PMID: 23775067 PMCID: PMC3701760 DOI: 10.1007/s13311-013-0198-1] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Spinal cord injury (SCI) causes not only sensorimotor and cognitive deficits, but frequently also severe chronic pain that is difficult to treat (SCI pain). We previously showed that hyperesthesia, as well as spontaneous pain induced by electrolytic lesions in the rat spinothalamic tract, is associated with increased spontaneous and sensory-evoked activity in the posterior thalamic nucleus (PO). We have also demonstrated that rodent impact SCI increases cell cycle activation (CCA) in the injury region and that post-traumatic treatment with cyclin dependent kinase inhibitors reduces lesion volume and motor dysfunction. Here we examined whether CCA contributes to neuronal hyperexcitability of PO and hyperpathia after rat contusion SCI, as well as to microglial and astroglial activation (gliopathy) that has been implicated in delayed SCI pain. Trauma caused enhanced pain sensitivity, which developed weeks after injury and was correlated with increased PO neuronal activity. Increased CCA was found at the thoracic spinal lesion site, the lumbar dorsal horn, and the PO. Increased microglial activation and cysteine-cysteine chemokine ligand 21 expression was also observed in the PO after SCI. In vitro, neurons co-cultured with activated microglia showed up-regulation of cyclin D1 and cysteine-cysteine chemokine ligand 21 expression. In vivo, post-injury treatment with a selective cyclin dependent kinase inhibitor (CR8) significantly reduced cell cycle protein induction, microglial activation, and neuronal activity in the PO nucleus, as well as limiting chronic SCI-induced hyperpathia. These results suggest a mechanistic role for CCA in the development of SCI pain, through effects mediated in part by the PO nucleus. Moreover, cell cycle modulation may provide an effective therapeutic strategy to improve reduce both hyperpathia and motor dysfunction after SCI.
Collapse
Affiliation(s)
- Junfang Wu
- Department of Anesthesiology & Center for Shock, Trauma and Anesthesiology Research, National Study Center for Trauma and EMS, University of Maryland, School of Medicine, Bressler Research Building, 655 W. Baltimore Street, Room #6-009, Baltimore, MD 21201, USA.
| | | | | | | | | |
Collapse
|
27
|
Zeng J, Kim D, Li KW, Sharp K, Steward O, Zaucke F, Luo ZD. Thrombospondin-4 contributes to spinal cord injury-induced changes in nociception. Eur J Pain 2013; 17:1458-64. [PMID: 23649982 DOI: 10.1002/j.1532-2149.2013.00326.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/01/2013] [Indexed: 11/06/2022]
Abstract
BACKGROUND Our previous data have indicated that nerve injury-induced up-regulation of thrombospondin-4 (TSP4) proteins in dorsal spinal cord plays a causal role in neuropathic pain state development in a spinal nerve ligation model. To investigate whether TSP4 proteins also contribute to the development of centrally mediated changes in nociception after spinal cord injury (SCI), we investigated whether SCI induced TSP4 dysregulation, and if so, whether this change correlated with changes in nociception in a T9 spinal cord contusion injury model. METHODS Behavioural sensitivity to mechanical, thermal stimuli and locomotor function recovery were tested blindly in SCI or sham rats post-injury. Intrathecal antisense or mismatch control oligodeoxynucleotides were used to treat SCI rats with nociceptive hyperreflexia, and Western blots were used to measure TSP4 protein levels in dorsal spinal cord samples. RESULTS SCI induced below-level hindpaw hypersensitivity to stimuli. TSP4 protein levels are up-regulated in dorsal spinal cord of SCI rats with nociceptive hyperreflexia, but not in SCI rats without nociceptive hyperreflexia. There was no significant difference in motor function recovery post-injury between SCI rats with or without nociceptive hyperreflexia. Intrathecal treatment with TSP4 antisense, but not mismatch control, oligodeoxynucleotides led to reversal of injury-induced TSP4 up-regulation and nociceptive hyperreflexia in SCI rats. CONCLUSIONS SCI leads to TSP4 up-regulation in lumbar spinal cord that may play a critical role in mediating centrally mediated behavioural hypersensitivity. Blocking this pathway may be helpful in management of SCI-induced changes in nociception.
Collapse
Affiliation(s)
- J Zeng
- Department of Anesthesiology & Perioperative Care, University of California Irvine, USA
| | | | | | | | | | | | | |
Collapse
|
28
|
Bareiss SK, Gwaltney M, Hernandez K, Lee T, Brewer KL. Excitotoxic spinal cord injury induced dysesthesias are associated with enhanced intrinsic growth of sensory neurons. Neurosci Lett 2013; 542:113-7. [DOI: 10.1016/j.neulet.2013.03.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2013] [Revised: 03/02/2013] [Accepted: 03/07/2013] [Indexed: 11/25/2022]
|
29
|
Saghaei E, Abbaszadeh F, Naseri K, Ghorbanpoor S, Afhami M, Haeri A, Rahimi F, Jorjani M. Estradiol attenuates spinal cord injury-induced pain by suppressing microglial activation in thalamic VPL nuclei of rats. Neurosci Res 2013; 75:316-23. [PMID: 23419864 DOI: 10.1016/j.neures.2013.01.010] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2012] [Revised: 01/21/2013] [Accepted: 01/29/2013] [Indexed: 12/22/2022]
Abstract
In our previous study we showed that central pain syndrome (CPS) induced by electrolytic injury caused in the unilateral spinothalamic tract (STT) is a concomitant of glial alteration at the site of injury. Here, we investigated the activity of glial cells in thalamic ventral posterolateral nuclei (VPL) and their contribution to CPS. We also examined whether post-injury administration of a pharmacological dose of estradiol can attenuate CPS and associated molecular changes. Based on the results,in the ipsilateral VPL the microglial phenotype switched o hyperactive mode and Iba1 expression was increased significantly on days 21 and 28 post-injury. The same feature was observed in contralateral VPL on day 28 (P<.05). These changes were strongly correlated with the onset of CPS (r(2)=0.670). STT injury did not induce significant astroglial response in both ipsilateral and contralateral VPL. Estradiol attenuated bilateral mechanical hypersensitivity 14 days after STT lesion (P<.05). Estradiol also suppressed microglial activation in the VPL. Taken together, these findings indicate that selective STT lesion induces bilateral microglia activation in VPL which might contribute to mechanical hypersensitivity. Furthermore, a pharmacological dose of estradiol reduces central pain possibly via suppression of glial activity in VPL region.
Collapse
Affiliation(s)
- Elham Saghaei
- Department of Pharmacology, Shahid Beheshti University of Medical Sciences, Evin, Tehran, Iran.
| | | | | | | | | | | | | | | |
Collapse
|
30
|
Ferguson AR, Huie JR, Crown ED, Baumbauer KM, Hook MA, Garraway SM, Lee KH, Hoy KC, Grau JW. Maladaptive spinal plasticity opposes spinal learning and recovery in spinal cord injury. Front Physiol 2012; 3:399. [PMID: 23087647 PMCID: PMC3468083 DOI: 10.3389/fphys.2012.00399] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2012] [Accepted: 09/20/2012] [Indexed: 01/23/2023] Open
Abstract
Synaptic plasticity within the spinal cord has great potential to facilitate recovery of function after spinal cord injury (SCI). Spinal plasticity can be induced in an activity-dependent manner even without input from the brain after complete SCI. A mechanistic basis for these effects is provided by research demonstrating that spinal synapses have many of the same plasticity mechanisms that are known to underlie learning and memory in the brain. In addition, the lumbar spinal cord can sustain several forms of learning and memory, including limb-position training. However, not all spinal plasticity promotes recovery of function. Central sensitization of nociceptive (pain) pathways in the spinal cord may emerge in response to various noxious inputs, demonstrating that plasticity within the spinal cord may contribute to maladaptive pain states. In this review we discuss interactions between adaptive and maladaptive forms of activity-dependent plasticity in the spinal cord below the level of SCI. The literature demonstrates that activity-dependent plasticity within the spinal cord must be carefully tuned to promote adaptive spinal training. Prior work from our group has shown that stimulation that is delivered in a limb position-dependent manner or on a fixed interval can induce adaptive plasticity that promotes future spinal cord learning and reduces nociceptive hyper-reactivity. On the other hand, stimulation that is delivered in an unsynchronized fashion, such as randomized electrical stimulation or peripheral skin injuries, can generate maladaptive spinal plasticity that undermines future spinal cord learning, reduces recovery of locomotor function, and promotes nociceptive hyper-reactivity after SCI. We review these basic phenomena, how these findings relate to the broader spinal plasticity literature, discuss the cellular and molecular mechanisms, and finally discuss implications of these and other findings for improved rehabilitative therapies after SCI.
Collapse
Affiliation(s)
- Adam R Ferguson
- Department of Neurological Surgery, Brain and Spinal Injury Center, University of California San Francisco San Francisco, CA, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
31
|
Tenorio G, Kulkarni A, Kerr BJ. Resident glial cell activation in response to perispinal inflammation leads to acute changes in nociceptive sensitivity: implications for the generation of neuropathic pain. Pain 2012; 154:71-81. [PMID: 23103436 DOI: 10.1016/j.pain.2012.09.008] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2012] [Revised: 08/01/2012] [Accepted: 09/20/2012] [Indexed: 12/31/2022]
Abstract
Injury or disease affecting the spinal cord is often accompanied by abnormal, chronic pain. Recent estimates suggest that approximately 60% of patients with multiple sclerosis are affected by significant changes in pain sensitivity or experience ongoing neuropathic pain of unknown etiology. Chronic pain is also a significant concern after direct spinal cord trauma. Inflammatory events and the changes in astrocyte and microglia reactivity at the spinal level in response to injury or disease are now recognized as important processes that can initiate pain hypersensitivity. Changes in the structural integrity or permeability of the blood-brain barrier/blood-spinal cord barrier (BBB/BSCB) can facilitate the inflammatory events that result in these abnormal pain states. It remains unclear, however, whether chronic pain in these disorders is dependent on the influx of peripheral leukocytes or whether changes in the reactivity of resident glial cells within the central nervous system alone are sufficient. To address this question, we generated a model of perispinal inflammation that resulted in significant changes in the reactivity of resident astrocytes and microglia within the spinal cord but maintained the integrity of the BSCB. A number of similar changes at the behavioural and cellular level occur in this model that mimic the responses seen in animal models of multiple sclerosis or spinal cord injury (SCI). However, these changes are short lived and resolve over the course of a 2-week observation period. Our findings suggest that the chronicity of pain after injury or disease in the nervous system is dependent on the integrity of the BBB/BSCB.
Collapse
Affiliation(s)
- Gustavo Tenorio
- Department of Anesthesiology and Pain Medicine, University of Alberta, Edmonton, Alberta, Canada Centre for Neuroscience, University of Alberta, Edmonton, Alberta, Canada
| | | | | |
Collapse
|
32
|
Kim KY, Sim KC, Kim HS, Choi WS, Kim GD. Analgesic Effects of Transcranial Direct Current Stimulation on Central Neuropathic Pain in Spinal Cord Contusive Rat Model. INTERNATIONAL JOURNAL OF CONTENTS 2012. [DOI: 10.5392/ijoc.2012.8.1.074] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
|
33
|
Masri R, Keller A. Chronic pain following spinal cord injury. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2012; 760:74-88. [PMID: 23281514 PMCID: PMC3560294 DOI: 10.1007/978-1-4614-4090-1_5] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Most patients with insults to the spinal cord or central nervous system suffer from excruciating, unrelenting, chronic pain that is largely resistant to treatment. This condition affects a large percentage of spinal cord injury patients, and numerous patients with multiple sclerosis, stroke and other conditions. Despite the recent advances in basic science and clinical research the pathophysiological mechanisms of pain following spinal cord injury remain unknown. Here we describe a novel mechanism of loss of inhibition within the thalamus that may predispose for the development of this chronic pain and discuss a potential treatment that may restore inhibition and ameliorate pain.
Collapse
Affiliation(s)
- Radi Masri
- Department of Endodontics, Prosthodontics and Operative Dentistry, Baltimore College of Dental Surgery, University of Maryland Baltimore, Baltimore, Maryland, USA.
| | | |
Collapse
|
34
|
Lucas JM, Ji Y, Masri R. Motor cortex stimulation reduces hyperalgesia in an animal model of central pain. Pain 2011; 152:1398-1407. [PMID: 21396776 PMCID: PMC3098950 DOI: 10.1016/j.pain.2011.02.025] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2010] [Revised: 12/30/2010] [Accepted: 02/08/2011] [Indexed: 11/16/2022]
Abstract
Electrical stimulation of the primary motor cortex has been used since 1991 to treat chronic neuropathic pain. Since its inception, motor cortex stimulation (MCS) treatment has had varied clinical outcomes. Until this point, there has not been a systematic study of the stimulation parameters that most effectively treat chronic pain, or of the mechanisms by which MCS relieves pain. Here, using a rodent model of central pain, we perform a systematic study of stimulation parameters used for MCS and investigate the mechanisms by which MCS reduces hyperalgesia. Specifically, we study the role of the inhibitory nucleus zona incerta (ZI) in mediating the analgesic effects of MCS. In animals with mechanical and thermal hyperalgesia, we find that stimulation at 50 μA, 50 Hz, and 300 μs square pulses for 30 minutes is sufficient to reverse mechanical and thermal hyperalgesia. We also find that stimulation of the ZI mimics the effects of MCS and that reversible inactivation of ZI blocks the effects of MCS. These findings suggest that the reduction of hyperalgesia may be due to MCS effects on ZI. In an animal model of central pain syndrome, motor cortex stimulation reduces hyperalgesia by activating zona incerta and therefore restoring inhibition in the thalamus.
Collapse
Affiliation(s)
- Jessica M Lucas
- Program in Neuroscience, University of Maryland School of Medicine, Baltimore, MD, USA Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD, USA Department of Endodontics, Prosthodontics and Operative Dentistry, Baltimore College of Dental Surgery, Baltimore, MD, USA
| | | | | |
Collapse
|
35
|
Knerlich-Lukoschus F, von der Ropp-Brenner B, Lucius R, Mehdorn HM, Held-Feindt J. Spatiotemporal CCR1, CCL3(MIP-1α), CXCR4, CXCL12(SDF-1α) expression patterns in a rat spinal cord injury model of posttraumatic neuropathic pain. J Neurosurg Spine 2011; 14:583-97. [DOI: 10.3171/2010.12.spine10480] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Object
Central neuropathic pain is a frequent challenging complication after spinal cord injury (SCI), and specific therapeutic approaches remain elusive. The purpose of the present investigations was to identify potential key mediators of these pain syndromes by analyzing detailed expression profiles of important chemokines in an experimental SCI paradigm of posttraumatic neuropathic pain in rats.
Methods
Expression of CCR1, CCL3(MIP-1α), CXCR4, and CXCL12(SDF-1α) was investigated in parallel with behavioral testing for mechanical and thermal nociceptive thresholds after standardized SCI; 100-kdyn (moderate injury) and 200-kdyn (severe injury) force-defined thoracic spinal cord contusion lesions were applied via an Infinite Horizon Impactor at the T-9 level. Sham controls received laminectomies. Hindlimb locomotor function as well as mechanical and thermal sensitivities were monitored weekly by standardized behavioral testing after SCI. Chemokine expression was analyzed by real-time reverse transcriptase polymerase chain reaction in the early (7 days postoperatively) and late (42 days postoperatively) time courses after SCI, and immunohistochemical analysis (anatomical and quantitative) was performed 2, 7, 14, and 42 days after lesioning. Double staining with cellular markers and pain-related peptides (substance P and CGRP) or receptors (TRPV-1, TRPV-2, VRL-1, and TLR-4) was performed. Based on data obtained from behavioral testing, quantified immunohistochemical chemokine expressions in individual animals were correlated with the respective mechanical and thermal sensitivity thresholds 6 weeks after SCI.
Results
After 200-kdyn lesions, the animals exhibited prolonged reduction in their nociceptive thresholds, while 100-kdyn groups showed pain-related behaviors only in the early time course after SCI. Investigated chemokines were widely induced after SCI, involving cervical, thoracic, and lumbar spinal cord levels far beyond the lesion core. CCR1 and CCL3 were induced significantly in the dorsal horns 2 days after lesioning and remained at high levels after SCI with significantly higher intensities after 200-kdyn than 100-kdyn contusions. CXCR4 and CXCL12 levels continuously increased from 2 to 42 days after moderate and severe lesions. Additionally, chemokines were induced significantly in dorsal columns, with highest density levels 42 days after 200-kdyn lesions. In dorsal horns, CCR1 was coexpressed with TRPV-1 while CXCR4 and CXCL12 were partially coexpressed with substance P and CGRP. In dorsal columns, CCL3/CCR1 colabeled with GFAP, TRPV-2, TRPV-1, TLR-4; CXCR4/CXCL12 coexpressed with GFAP, CD68/ED1, and TLR4. Chemokine immunoreactivity density levels, especially CCL3 and its receptor, correlated in part significantly with nociceptive thresholds.
Conclusions
The authors report lesion grade–dependent upregulation of different chemokines/chemokine receptors after spinal cord contusion lesions in pain-processing spinal cord regions in a clinically relevant model of traumatic SCI in rats. Prolonged chemokine induction further correlated with below-level pain development in the delayed time course after severe SCI and was coexpressed with pain-associated peptides and receptors, suggesting that chemokines play a crucial role in chronic central pain mechanisms after SCI.
Collapse
Affiliation(s)
- Friederike Knerlich-Lukoschus
- 1Department of Neurosurgery, University of Schleswig-Holstein Medical Center, Kiel; and
- 2Department of Anatomy, University of Kiel, Germany
| | | | - Ralph Lucius
- 2Department of Anatomy, University of Kiel, Germany
| | | | - Janka Held-Feindt
- 1Department of Neurosurgery, University of Schleswig-Holstein Medical Center, Kiel; and
| |
Collapse
|
36
|
Davoody L, Quiton RL, Lucas JM, Ji Y, Keller A, Masri R. Conditioned place preference reveals tonic pain in an animal model of central pain. THE JOURNAL OF PAIN 2011; 12:868-74. [PMID: 21515090 DOI: 10.1016/j.jpain.2011.01.010] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2010] [Revised: 01/27/2011] [Accepted: 01/31/2011] [Indexed: 10/18/2022]
Abstract
UNLABELLED A limitation of animal models of central pain is their inability to recapitulate all clinical characteristics of the human condition. Specifically, many animal models rely on reflexive measures of hypersensitivity and ignore, or cannot assess, spontaneous pain, the hallmark characteristic of central pain in humans. Here, we adopt a conditioned place preference paradigm to test if animals with lesions in the anterolateral quadrant of the spinal cord develop signs consistent with spontaneous pain. This paradigm relies on the fact that pain relief is rewarding to animals, and has been used previously to show that animals with peripheral nerve injury develop tonic pain. With the use of 2 analgesic treatments commonly used to treat patients with central pain (clonidine infusion and motor cortex stimulation), we demonstrate that analgesic treatments are rewarding to animals with spinal cord lesions but not sham-operated controls. These findings are consistent with the conclusion that animals with spinal cord injury suffer from tonic pain. PERSPECTIVE The hallmark characteristic of central pain in humans is spontaneous pain. Animal models of central pain rely on reflexive measures of hypersensitivity and do not assess spontaneous pain. Demonstrating that animals with spinal cord injury suffer from tonic pain is important to study the etiology of central pain.
Collapse
Affiliation(s)
- Leyla Davoody
- Department of Endodontics,Prosthodontics and Operative Dentistry, Baltimore College of Dental Surgery, 650 West Baltimore Street, Baltimore, MD, USA
| | | | | | | | | | | |
Collapse
|
37
|
Hains B, Vera-Portocarrero LP. Animal Models of Central Neuropathic Pain. ANIMAL MODELS OF PAIN 2011. [DOI: 10.1007/978-1-60761-880-5_7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
|
38
|
Hama A, Sagen J. Antinociceptive Effect of Riluzole in Rats with Neuropathic Spinal Cord Injury Pain. J Neurotrauma 2011; 28:127-34. [DOI: 10.1089/neu.2010.1539] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Affiliation(s)
- Aldric Hama
- The Miami Project to Cure Paralysis, University of Miami Miller School of Medicine, Miami, Florida
| | - Jacqueline Sagen
- The Miami Project to Cure Paralysis, University of Miami Miller School of Medicine, Miami, Florida
| |
Collapse
|
39
|
Baastrup C, Maersk-Moller CC, Nyengaard JR, Jensen TS, Finnerup NB. Spinal-, brainstem- and cerebrally mediated responses at- and below-level of a spinal cord contusion in rats: evaluation of pain-like behavior. Pain 2010; 151:670-679. [PMID: 20863621 DOI: 10.1016/j.pain.2010.08.024] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2010] [Revised: 08/13/2010] [Accepted: 08/18/2010] [Indexed: 11/16/2022]
Abstract
Pain is a frequent consequence of spinal cord injury (SCI) which may profoundly impair the patients' quality of life. Valid experimental models and methods are therefore desirable in the search for better treatments. Usually, experimental pain assays depend on stimulus-evoked withdrawal responses; however, this spinal-mediated reflex response may be particularly problematic when evaluating below-level SCI pain due to the development of hyperactive reflex circuitries. In this study, we applied and compared assays measuring cold (acetone), static (von Frey filaments), and dynamic mechanical (soft brush) hypersensitivity at different levels of the neuroaxis at and below the level of injury in a rat model of SCI. We induced an experimental SCI (MASCIS 25 mm weight-drop) and evaluated the development of spinal reflexes (withdrawal), spinal-brainstem-spinal reflexes (licking, guarding, struggling, vocalizing, jumping, and biting) and cerebral-dependent behavior (place escape/avoidance paradigm (PEAP)). We demonstrated increased brainstem reflexes and cerebrally mediated aversive reactions to stimuli applied at the level of SCI, suggesting development of at-level evoked pain behavior. Furthermore, stimulation below-level increased innate reflex responses without increasing brainstem reflexes or aversive behavior in the PEAP, suggesting development of the spasticity syndrome rather than pain-like behavior. While spinal reflex measures are acceptable for studying changes in the spinal reflex pathways and spinal cord, they are not suited as nociceptive behavioral measures. Measuring brainstem organized responses eliminates the bias associated with the spastic syndrome, but pain requires cortical involvement. Methods depending on cortical structures, as the PEAP, are therefore optimal endpoints in animal models of central pain.
Collapse
Affiliation(s)
- Cathrine Baastrup
- Danish Pain Research Center, Aarhus University Hospital, Aarhus, Denmark Stereology & Electron Microscopy Research Laboratory, Aarhus University Hospital, Aarhus, Denmark
| | | | | | | | | |
Collapse
|
40
|
Hama AT, Plum AW, Sagen J. Antinociceptive effect of ambroxol in rats with neuropathic spinal cord injury pain. Pharmacol Biochem Behav 2010; 97:249-55. [PMID: 20732348 DOI: 10.1016/j.pbb.2010.08.006] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/16/2010] [Revised: 08/10/2010] [Accepted: 08/15/2010] [Indexed: 01/08/2023]
Abstract
Symptoms of neuropathic spinal cord injury (SCI) pain include evoked cutaneous hypersensitivity and spontaneous pain, which can be present below the level of the injury. Adverse side-effects obtained with currently available analgesics complicate effective pain management in SCI patients. Voltage-gated Na(+) channels expressed in primary afferent nociceptors have been identified to mediate persistent hyperexcitability in dorsal root ganglia (DRG) neurons, which in part underlies the symptoms of nerve injury-induced pain. Ambroxol has previously demonstrated antinociceptive effects in rat chronic pain models and has also shown to potently block Na(+) channel current in DRG neurons. Ambroxol was tested in rats that underwent a mid-thoracic spinal cord compression injury. Injured rats demonstrated robust hind paw (below-level) heat and mechanical hypersensitivity. Orally administered ambroxol significantly attenuated below-level hypersensitivity at doses that did not affect performance on the rotarod test. Intrathecal injection of ambroxol did not ameliorate below-level hypersensitivity. The current data suggest that ambroxol could be effective for clinical neuropathic SCI pain. Furthermore, the data suggest that peripherally expressed Na(+) channels could lend themselves as targets for the development of pharmacotherapies for SCI pain.
Collapse
Affiliation(s)
- Aldric T Hama
- The Miami Project to Cure Paralysis, University of Miami Miller School of Medicine, Miami, FL 33136, USA.
| | | | | |
Collapse
|
41
|
Masri R, Quiton RL, Lucas JM, Murray PD, Thompson SM, Keller A. Zona incerta: a role in central pain. J Neurophysiol 2009; 102:181-91. [PMID: 19403748 DOI: 10.1152/jn.00152.2009] [Citation(s) in RCA: 107] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Central pain syndrome (CPS) is a debilitating condition that affects a large number of patients with a primary lesion or dysfunction in the CNS. Despite its discovery over a century ago, the pathophysiological processes underlying the development and maintenance of CPS are poorly understood. We recently demonstrated that activity in the posterior thalamus (PO) is tightly regulated by inhibitory inputs from zona incerta (ZI). Here we test the hypothesis that CPS is associated with abnormal inhibitory regulation of PO by ZI. We recorded single units from ZI and PO in animals with CPS resulting from spinal cord lesions. Consistent with our hypothesis, the spontaneous firing rate and somatosensory evoked responses of ZI neurons were lower in lesioned animals compared with sham-operated controls. In PO, neurons recorded from lesioned rats exhibited significantly higher spontaneous firing rates and greater responses to noxious and innocuous stimuli applied to the hindpaw and to the face. These changes were not associated with increased afferent drive from the spinal trigeminal nucleus or changes in the ventroposterior thalamus. Thus CPS can result from suppressed inputs from the inhibitory nucleus zona incerta to the posterior thalamus.
Collapse
Affiliation(s)
- Radi Masri
- Department of Anatomy, University of Maryland School of Medicine, 20 Penn St., Baltimore, MD 21201, USA
| | | | | | | | | | | |
Collapse
|
42
|
Kalous A, Osborne PB, Keast JR. Spinal cord compression injury in adult rats initiates changes in dorsal horn remodeling that may correlate with development of neuropathic pain. J Comp Neurol 2009; 513:668-84. [DOI: 10.1002/cne.21986] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
|
43
|
Maladaptive homeostatic plasticity in a rodent model of central pain syndrome: thalamic hyperexcitability after spinothalamic tract lesions. J Neurosci 2009; 28:11959-69. [PMID: 19005061 DOI: 10.1523/jneurosci.3296-08.2008] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Central pain syndrome (CPS) is defined as pain associated with a lesion of the CNS and is a common consequence of spinal cord injuries. We generated a rodent model of CPS by making unilateral electrolytic or demyelinating lesions centered on the spinothalamic tract in rats. Thermal hyperalgesia and mechanical allodynia occurred in both hind paws and forepaws by 7 d postlesion and were maintained >31 d. Field potentials in the ventral posterior lateral nucleus (VPL) in thalamic brain slices from lesioned animals displayed an increased probability of burst responses. Ethosuximide, a T-type calcium channel blocker, eliminated busting in lesioned thalamic slices and attenuated lesion-induced hyperalgesia and allodynia. We conclude that CPS in this model results from an increase in the excitability of thalamic nuclei that have lost normal ascending inputs as the result of a spinal cord injury and suggest that ethosuximide will relieve human CPS by restoring normal thalamic excitability.
Collapse
|
44
|
Saab CY, Hains BC. Remote neuroimmune signaling: a long-range mechanism of nociceptive network plasticity. Trends Neurosci 2009; 32:110-7. [PMID: 19135730 DOI: 10.1016/j.tins.2008.11.004] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2008] [Revised: 10/28/2008] [Accepted: 11/04/2008] [Indexed: 01/19/2023]
Abstract
Chronic pain secondary to neuronal injury is actively and continuously modulated at multiple locations along the sensory neuraxis. Here, we describe how nociceptive neurons of the spinal cord and thalamus process and communicate nociceptive information in terms of precisely calibrated firing patterns. We then discuss how several cell types with immunogenic properties (e.g. blood cells and glia) cause system-wide interference in nociceptive processing through novel signaling schema, thus contributing to nociceptive network plasticity and chronic pain.
Collapse
Affiliation(s)
- Carl Y Saab
- Department of Surgery, Rhode Island Hospital, Brown Alpert Medical School and Department of Neuroscience, Brown University, Providence, RI 02903, USA.
| | | |
Collapse
|
45
|
Hulsebosch CE, Hains BC, Crown ED, Carlton SM. Mechanisms of chronic central neuropathic pain after spinal cord injury. ACTA ACUST UNITED AC 2008; 60:202-13. [PMID: 19154757 DOI: 10.1016/j.brainresrev.2008.12.010] [Citation(s) in RCA: 224] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/29/2008] [Indexed: 12/25/2022]
Abstract
Not all spinal contusions result in mechanical allodynia, in which non-noxious stimuli become noxious. The studies presented use the NYU impactor at 12.5 mm drop or the Infinite Horizons Impactor (150 kdyn, 1 s dwell) devices to model spinal cord injury (SCI). Both of these devices and injury parameters, if done correctly, will result in animals with above level (forelimb), at level (trunk) and below level (hindlimb) mechanical allodynia that model the changes in evoked somatosensation experienced by the majority of people with SCI. The sections are as follows: 1) Mechanisms of remote microglial activation and pain signaling in "below-level" central pain 2) Intracellular signaling mechanisms in central sensitization in "at-level" pain 3) Peripheral sensitization contributes to "above level" injury pain following spinal cord injury and 4) Role of reactive oxygen species in central sensitization in regional neuropathic pain following SCI. To summarize, differential regional mechanisms contribute to the regional chronic pain states. We propose the importance of understanding the mechanisms in the differential regional pain syndromes after SCI in the chronic condition. Targeting regional mechanisms will be of enormous benefit to the SCI population that suffer chronic pain, and will contribute to better treatment strategies for other chronic pain syndromes.
Collapse
Affiliation(s)
- Claire E Hulsebosch
- Department of Neuroscience and Cell Biology, University of Texas Medical Branch, 301 University Boulevard, Galveston, TX 77555-1043, USA.
| | | | | | | |
Collapse
|
46
|
Brewer KL, Lee JW, Downs H, Oaklander AL, Yezierski RP. Dermatomal scratching after intramedullary quisqualate injection: correlation with cutaneous denervation. THE JOURNAL OF PAIN 2008; 9:999-1005. [PMID: 18619906 PMCID: PMC3128346 DOI: 10.1016/j.jpain.2008.05.010] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2008] [Revised: 05/19/2008] [Accepted: 05/28/2008] [Indexed: 12/14/2022]
Abstract
UNLABELLED Central nervous system lesions cause peripheral dysfunctions currently attributed to central cell death that compromises function of intact peripheral nerves. Injecting quisqualate (QUIS) into the rat spinal cord models spinal cord injury (SCI) and causes at-level scratching and self-injury. Such overgrooming was interpreted to model pain until patients with self-injurious scratching after SCI reported itch motivated scratching that was painless because of sensory loss. Because self-injurious scratching is difficult to explain by central mechanisms alone, we hypothesized that QUIS injections damage peripheral axons of at-level afferents. QUIS was injected into thoracic spinal cords of 18 Long-Evans rats. Animals were killed 3 days after overgrooming began or 14 days after injection. Spinal cord lesions were localized and DRG-immunolabeled for ATF-3. At-level and control skin samples were PGP9.5-immunabeled to quantify axons. Eighty-four percent of QUIS rats overgroomed. Skin in these regions had lost two-thirds of epidermal innervation as compared with controls (P < .001). Rats that overgroomed had 47% less axon-length than nongrooming rats (P = .006). The presence of ATF-3 immunolabeled neurons within diagnosis-related groups of QUIS rats indicated death of afferent cell bodies. Overgrooming after QUIS injections may not be due entirely to central changes. As in humans, self-injurious neuropathic scratching appeared to require loss of protective pain sensations in addition to peripheral denervation. PERSPECTIVE This study suggests that intramedullary injection of quisqualic acid in rats causes death of at-level peripheral as well as central neurons. Self-injurious dermatomal scratching that develops in spinal-injured rats may reflect neuropathic itch and loss of protective pain sensations.
Collapse
Affiliation(s)
- Kori L Brewer
- Department of Emergency Medicine, Brody School of Medicine at East Carolina University, Greenville, North Carolina 27834, USA.
| | | | | | | | | |
Collapse
|
47
|
Lee JW, Furmanski O, Castellanos DA, Daniels LA, Hama AT, Sagen J. Prolonged nociceptive responses to hind paw formalin injection in rats with a spinal cord injury. Neurosci Lett 2008; 439:212-5. [PMID: 18524486 DOI: 10.1016/j.neulet.2008.05.030] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2008] [Revised: 05/06/2008] [Accepted: 05/07/2008] [Indexed: 11/29/2022]
Abstract
Unilateral lesioning of the spinal dorsal horn with the excitotoxin quisqualic acid (QUIS) leads to robust degeneration of dorsal horn grey matter, and robust pain-related symptoms, such as cutaneous hypersensitivity, persist long after injury. A possible mechanism that underlies the pain-related symptoms is the disruption of dorsal horn inhibitory neuron function, leading to decreased inhibition of nociceptive neurons. Five percent formalin was injected into the hind paw of rats with either a QUIS lesion or sham lesion. Both QUIS- and sham-lesioned rats displayed bi-phasic hind paw flinches following formalin injection, but a prolonged response was observed in QUIS-lesioned rats. The expression of the immediate-early gene product Fos in the dorsal horn ipsilateral to formalin injection was similar between QUIS- and sham-lesioned rats. In QUIS-lesioned rats, however, there was a marked absence of dorsal horn neurons, particularly GABAergic neurons, compared to sham-lesioned rats. The prolonged nociceptive response observed with a unilateral QUIS lesion may be due to generalized changes in dorsal horn neuron function including a loss of inhibitory neuron function.
Collapse
Affiliation(s)
- Jeung Woon Lee
- The Miami Project to Cure Paralysis, University of Miami, Miller School of Medicine, 1095 NW 14th Terrace (R-48), Miami, FL 33136, USA
| | | | | | | | | | | |
Collapse
|
48
|
Detloff MR, Fisher LC, McGaughy V, Longbrake EE, Popovich PG, Basso DM. Remote activation of microglia and pro-inflammatory cytokines predict the onset and severity of below-level neuropathic pain after spinal cord injury in rats. Exp Neurol 2008; 212:337-47. [PMID: 18511041 DOI: 10.1016/j.expneurol.2008.04.009] [Citation(s) in RCA: 203] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2007] [Revised: 03/19/2008] [Accepted: 04/08/2008] [Indexed: 12/29/2022]
Abstract
Spinal cord injury (SCI) impairs sensory systems causing chronic allodynia. Mechanisms underlying neuropathic pain have been more extensively studied following peripheral nerve injury (PNI) than after central trauma. Microglial activation, pro-inflammatory cytokine production and activation of p38 MAP kinase pathways may induce at-level allodynia following PNI. We investigated whether midthoracic SCI elicits similar behavioral and cellular responses below the level of injury (lumbar spinal cord; L5). Importantly, we show that anatomical connections between L5 and supraspinal centers remain intact after moderate SCI allowing direct comparison to a well-established model of peripheral nerve injury. We found that SCI elicits below-level allodynia of similar magnitude to at-level pain caused by a peripheral nerve injury. Moreover, the presence of robust microglial activation in L5 cord predicted allodynia in 86% of rats. Also increased phosphorylation of p38 MAP kinase occurred in the L5 dorsal horn of allodynic rats. For below-level allodynia after SCI, TNF-alpha and IL-1beta increased in the L5 dorsal horn by 7 dpo and returned to baseline by 35 dpo. Interestingly, IL-6 remains at normal levels early after SCI and increases at chronic time points. Increased levels of pro-inflammatory cytokines also occurred in the thalamus after SCI-induced allodynia. These data suggest that remote microglial activation is pivotal in the development and maintenance of below-level allodynia after SCI. Fractalkine, a known activator of microglia, and astrocytes were not primary modulators of below-level pain. Although the mechanisms of remote microglial activation are unknown, this response may be a viable target for limiting or preventing neuropathic pain after SCI in humans.
Collapse
Affiliation(s)
- Megan Ryan Detloff
- Center for Brain and Spinal Cord Repair, Neuroscience Graduate Studies Program, The Ohio State University 43210, USA
| | | | | | | | | | | |
Collapse
|
49
|
Intrathecal rosiglitazone acts at peroxisome proliferator-activated receptor-gamma to rapidly inhibit neuropathic pain in rats. THE JOURNAL OF PAIN 2008; 9:639-49. [PMID: 18387855 DOI: 10.1016/j.jpain.2008.02.002] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2007] [Revised: 02/01/2008] [Accepted: 02/02/2008] [Indexed: 12/30/2022]
Abstract
UNLABELLED In this report, we demonstrate the transcription, expression, and DNA-binding properties of the peroxisome proliferator-activated receptor (PPAR)-gamma subtype of the peroxisome proliferator-activated nuclear receptor family to the spinal cord with real-time PCR, Western blot, and electrophoretic mobility shift assay. To test the hypothesis that activation of spinal PPAR-gamma decreases nerve injury-induced allodynia, we intrathecally administered PPAR-gamma agonists and/or antagonists in rats after transection of the tibial and common peroneal branches of the sciatic nerve. Single injection of either a natural (15-deoxy-prostaglandin J2, 15d-PGJ2) or synthetic (rosiglitazone) PPAR-gamma agonist dose-dependently decreased mechanical and cold hypersensitivity. These effects were maximal at a dose of 100 microg and peaked at approximately 60 minutes after injection, a rapid time course suggestive of transcription-independent mechanisms of action. Concurrent administration of a PPAR-gamma antagonist (bisphenol A diglycidyl ether, BADGE) reversed the effects of 15d-PGJ2 and rosiglitazone, further indicating a receptor-mediated effect. In animals without nerve injury, rosiglitazone did not alter motor coordination, von Frey threshold, or withdrawal response to a cool stimulus. Intraperitoneal and intracerebroventricular administration of PPAR-gamma agonists (100 microg) did not decrease mechanical and cold hypersensitivity, arguing against effects subsequent to diffusion from the intrathecal space. We conclude that ligand-induced activation of spinal PPAR-gamma rapidly reverses nerve injury-induced mechanical allodynia. New or currently available drugs targeted at spinal PPAR-gamma may yield important therapeutic effects for the management of neuropathic pain. PERSPECTIVE PPAR-gamma receptor agonists such as rosiglitazone and pioglitazone are approved as insulin sensitizers by the United States Food and Drug Administration. We demonstrate PPAR-gamma expression in the spinal cord and report that activation of these receptors inhibits allodynia. BBB-permeant PPAR-gamma agonists may yield important therapeutic effects for the management of neuropathic pain.
Collapse
|
50
|
Berrocal Y, Pearse DD, Singh A, Andrade CM, McBroom JS, Puentes R, Eaton MJ. Social and environmental enrichment improves sensory and motor recovery after severe contusive spinal cord injury in the rat. J Neurotrauma 2008; 24:1761-72. [PMID: 18001204 DOI: 10.1089/neu.2007.0327] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Neuropathic pain and motor dysfunction are difficult problems following spinal cord injury (SCI). Social and environmental enrichment (SEE), which models much of the clinical rehabilitation environment for post-SCI persons, is the focus of the current investigation which examines the effects of multiple-housing and the addition of climbing spaces, improved bedding and crawl toys on the sensory and motor recovery following a severe contusive SCI. Efficacy was determined with sensory testing, open-field motor behavioral testing, lesion volume analysis and quantification of brain-derived neurotrophic factor (BDNF) in the lumbar spinal cord with and without SEE provided during the recovery period. Sensory and motor testing were performed weekly for 12 weeks following SCI. SEE significantly and permanently reversed cutaneous allodynia, but not thermal hyperalgesia, to near normal levels. The gross locomotor performance (BBB [Basso, Beattie, and Bresnahan] motor scores) significantly improved about two points. In addition, the BBB subscale scores were significantly improved nearly seven points by the end of the study. SEE also significantly improved foot rotation to normal levels and reduced gridwalk footfall errors nearly 50%, but had no effect on stride length or base of support dysfunctions. SEE significantly increased the total volume of a thoracic segment of cord encompassing the injury site at 12 weeks, by reducing cavitation and increasing both the volume of grey and white matter spared, compared to SCI alone. When BDNF levels were examined in the injured lumbar spinal cord, SEE significantly returned BDNF levels to near-normal. These data suggest that immediate use of SEE after contusive SCI is able to improve overall spinal cell survival and prevent much of the sensory and motor dysfunction that accompanies contusive SCI.
Collapse
Affiliation(s)
- Yerko Berrocal
- The Miami Project to Cure Paralysis, Miller School of Medicine at the University of Miami, Miami, Florida, USA
| | | | | | | | | | | | | |
Collapse
|