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Lin CL, Li YL, Chen YW, Kuo CH, Tu TY, Liu YF, Tsai JC, Shyong YJ. Amphiphilic NLC-Gel formulation loaded with Sebacoyl dinalbuphine ester and Nalbuphine for localized postoperative pain management. Int J Pharm 2024; 659:124295. [PMID: 38823469 DOI: 10.1016/j.ijpharm.2024.124295] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2024] [Revised: 05/13/2024] [Accepted: 05/29/2024] [Indexed: 06/03/2024]
Abstract
Opioids are powerful analgesics; however, their significant systemic adverse effects and the need for frequent administration restrict their use. Nalbuphine (NA) is a κ-agonist narcotic with limited adverse effects, but needs to be frequently administrated due to its short elimination half-life. Whereas sebacoyl dinalbuphine ester (SDE) is a NA prodrug, which can effectively prolong the analgesic effect, but lacks immediate pain relief. Therefore, in this study, a rapid and sustained local delivery formulation to introduce NA and SDE directly into surgical sites was developed. An amphiphilic nanostructured lipid carrier (NLC) poloxamer 407 (P407) gel (NLC-Gel) was developed to permit concurrent delivery of hydrophobic SDE from the NLC core and hydrophilic NA from P407, offering a dual rapid and prolonged analgesic effect. Benefiting from the thermal-sensitive characteristic of P407, the formulation can be injected in liquid phase and instantly transit into gel at wound site. NLC-Gel properties, including particle size, drug release, rheology, and stability, were assessed. In vivo evaluation using a rat spinal surgery model highlighted the effect of the formulation through pain behavior test and hematology analysis. NLC-Gels demonstrated an analgesic effect comparable with that of commercial intramuscular injected SDE formulation (IM SDE), with only 15 % of the drug dosage. The inclusion of supplemental NA in the exterior gel (PA12-Gel + NA) provided rapid drug onset owing to swift NA dispersion, addressing acute pain within hours along with prolonged analgesic effects. Our findings suggest that this amphiphilic formulation significantly enhanced postoperative pain management in terms of safety and efficacy.
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Affiliation(s)
- Cheng-Li Lin
- Department of Orthopedic Surgery, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Yi-Lian Li
- School of Pharmacy, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Yu-Wei Chen
- School of Pharmacy, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Cheng-Hsiang Kuo
- International Center for Wound Repair and Regeneration, National Cheng Kung University, Tainan, Taiwan
| | - Ting-Yuan Tu
- Department of Biomedical Engineering, National Cheng Kung University, Tainan, Taiwan
| | - Yuan-Fu Liu
- Department of Orthopedic Surgery, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Jui-Chen Tsai
- School of Pharmacy, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Yan-Jye Shyong
- School of Pharmacy, College of Medicine, National Cheng Kung University, Tainan, Taiwan.
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Yan L, Li Z, Li C, Chen J, Zhou X, Cui J, Liu P, Shen C, Chen C, Hong H, Xu G, Cui Z. Hspb1 and Lgals3 in spinal neurons are closely associated with autophagy following excitotoxicity based on machine learning algorithms. PLoS One 2024; 19:e0303235. [PMID: 38728287 PMCID: PMC11086895 DOI: 10.1371/journal.pone.0303235] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2023] [Accepted: 04/23/2024] [Indexed: 05/12/2024] Open
Abstract
Excitotoxicity represents the primary cause of neuronal death following spinal cord injury (SCI). While autophagy plays a critical and intricate role in SCI, the specific mechanism underlying the relationship between excitotoxicity and autophagy in SCI has been largely overlooked. In this study, we isolated primary spinal cord neurons from neonatal rats and induced excitotoxic neuronal injury by high concentrations of glutamic acid, mimicking an excitotoxic injury model. Subsequently, we performed transcriptome sequencing. Leveraging machine learning algorithms, including weighted correlation network analysis (WGCNA), random forest analysis (RF), and least absolute shrinkage and selection operator analysis (LASSO), we conducted a comprehensive investigation into key genes associated with spinal cord neuron injury. We also utilized protein-protein interaction network (PPI) analysis to identify pivotal proteins regulating key gene expression and analyzed key genes from public datasets (GSE2599, GSE20907, GSE45006, and GSE174549). Our findings revealed that six genes-Anxa2, S100a10, Ccng1, Timp1, Hspb1, and Lgals3-were significantly upregulated not only in vitro in neurons subjected to excitotoxic injury but also in rats with subacute SCI. Furthermore, Hspb1 and Lgals3 were closely linked to neuronal autophagy induced by excitotoxicity. Our findings contribute to a better understanding of excitotoxicity and autophagy, offering potential targets and a theoretical foundation for SCI diagnosis and treatment.
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Affiliation(s)
- Lei Yan
- The First People’s Hospital of Nantong, Research Institute for Spine and Spinal Cord Disease of Nantong University, The Second Affiliated Hospital of Nantong University, Nantong, China
| | - Zihao Li
- The First People’s Hospital of Nantong, Research Institute for Spine and Spinal Cord Disease of Nantong University, The Second Affiliated Hospital of Nantong University, Nantong, China
| | - Chuanbo Li
- The First People’s Hospital of Nantong, Research Institute for Spine and Spinal Cord Disease of Nantong University, The Second Affiliated Hospital of Nantong University, Nantong, China
| | - Jingyu Chen
- The First People’s Hospital of Nantong, Research Institute for Spine and Spinal Cord Disease of Nantong University, The Second Affiliated Hospital of Nantong University, Nantong, China
| | - Xun Zhou
- The First People’s Hospital of Nantong, Research Institute for Spine and Spinal Cord Disease of Nantong University, The Second Affiliated Hospital of Nantong University, Nantong, China
| | - Jiaming Cui
- The First People’s Hospital of Nantong, Research Institute for Spine and Spinal Cord Disease of Nantong University, The Second Affiliated Hospital of Nantong University, Nantong, China
| | - Peng Liu
- The First People’s Hospital of Nantong, Research Institute for Spine and Spinal Cord Disease of Nantong University, The Second Affiliated Hospital of Nantong University, Nantong, China
| | - Chong Shen
- The First People’s Hospital of Nantong, Research Institute for Spine and Spinal Cord Disease of Nantong University, The Second Affiliated Hospital of Nantong University, Nantong, China
| | - Chu Chen
- The First People’s Hospital of Nantong, Research Institute for Spine and Spinal Cord Disease of Nantong University, The Second Affiliated Hospital of Nantong University, Nantong, China
| | - Hongxiang Hong
- The First People’s Hospital of Nantong, Research Institute for Spine and Spinal Cord Disease of Nantong University, The Second Affiliated Hospital of Nantong University, Nantong, China
| | - Guanhua Xu
- The First People’s Hospital of Nantong, Research Institute for Spine and Spinal Cord Disease of Nantong University, The Second Affiliated Hospital of Nantong University, Nantong, China
| | - Zhiming Cui
- The First People’s Hospital of Nantong, Research Institute for Spine and Spinal Cord Disease of Nantong University, The Second Affiliated Hospital of Nantong University, Nantong, China
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Li L, Guo L, Gao R, Yao M, Qu X, Sun G, Fu Q, Hu C, Han G. Ferroptosis: a new regulatory mechanism in neuropathic pain. Front Aging Neurosci 2023; 15:1206851. [PMID: 37810619 PMCID: PMC10556472 DOI: 10.3389/fnagi.2023.1206851] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2023] [Accepted: 09/11/2023] [Indexed: 10/10/2023] Open
Abstract
Neuropathic pain (NP) is pain caused by damage to the somatosensory system. It is a common progressive neurodegenerative disease that usually presents with clinical features such as spontaneous pain, touch-evoked pain, nociceptive hyperalgesia, and sensory abnormalities. Due to the complexity of the mechanism, NP often persists. In addition to the traditionally recognized mechanisms of peripheral nerve damage and central sensitization, excessive iron accumulation, oxidative stress, neuronal inflammation, and lipid peroxidation damage are distinctive features of NP in pathophysiology. However, the mechanisms linking these pathological features to NP are not fully understood. The complexity of the pathogenesis of NP greatly limits the development of therapeutic approaches for NP. Ferroptosis is a novel form of cell death discovered in recent years, in which cell death is usually accompanied by massive iron accumulation and lipid peroxidation. Ferroptosis-inducing factors can affect glutathione peroxidase directly or indirectly through different pathways, leading to decreased antioxidant capacity and accumulation of lipid reactive oxygen species (ROS) in cells, ultimately leading to oxidative cell death. It has been shown that ferroptosis is closely related to the pathophysiological process of many neurological disorders such as NP. Possible mechanisms involved are changes in intracellular iron ion levels, alteration of glutamate excitability, and the onset of oxidative stress. However, the functional changes and specific molecular mechanisms of ferroptosis during this process still need to be further explored. How to intervene in the development of NP by regulating cellular ferroptosis has become a hot issue in etiological research and treatment. In this review, we systematically summarize the recent progress of ferroptosis research in NP, to provide a reference for further understanding of its pathogenesis and propose new targets for treatment.
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Affiliation(s)
- Lu Li
- Department of Anesthesiology, Shengjing Hospital of China Medical University, Shenyang, China
| | - Lingling Guo
- Department of Anesthesiology, Shengjing Hospital of China Medical University, Shenyang, China
| | - Rui Gao
- Department of Anesthesiology, The Fourth Affiliated Hospital of China Medical University, Shenyang, China
| | - Mengwen Yao
- Department of Anesthesiology, Shengjing Hospital of China Medical University, Shenyang, China
| | - Xinyu Qu
- Department of Anesthesiology, Shengjing Hospital of China Medical University, Shenyang, China
| | - Guangwei Sun
- Department of Anesthesiology, Shengjing Hospital of China Medical University, Shenyang, China
| | - Qi Fu
- Department of Anesthesiology, Shengjing Hospital of China Medical University, Shenyang, China
| | - Cuntao Hu
- Department of Anesthesiology, Shengjing Hospital of China Medical University, Shenyang, China
| | - Guang Han
- Department of Anesthesiology, Shengjing Hospital of China Medical University, Shenyang, China
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Sachdeva R, Hosseinzadeh A, Rizzardo A, Maharaj A, Berger M, Krassioukov A. No pain, no strain: Targin® mitigates pain and constipation following spinal cord injury. Ann Clin Transl Neurol 2023; 10:453-458. [PMID: 36692221 PMCID: PMC10014000 DOI: 10.1002/acn3.51734] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Revised: 12/30/2022] [Accepted: 01/10/2023] [Indexed: 01/25/2023] Open
Abstract
BACKGROUND Opioids effectively reduce chronic pain, but present significant side effects including opioid-induced constipation. Oxycodone/naloxone decreases pain and constipation in cancer patients, however its effect on spinal cord injury population remains understudied. METHODS We assessed whether oxycodone/naloxone reduces pain, constipation, and severity of autonomic dysreflexia in an individual with spinal cord injury. A 55-year-old male with C5 lesion presented with chief complaint of chronic pain received 5/2.5 mg and 20/10 mg oxycodone/naloxone for 6 and 2 weeks, respectively. RESULTS Oxycodone/naloxone improved pain, bowel function, and autonomic dysreflexia severity. INTERPRETATION Oxycodone/naloxone was effective in managing chronic pain and constipation in the studied case.
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Affiliation(s)
- Rahul Sachdeva
- International Collaboration on Repair Discoveries, University of British Columbia, British Columbia, Vancouver, Canada
| | - Ali Hosseinzadeh
- International Collaboration on Repair Discoveries, University of British Columbia, British Columbia, Vancouver, Canada
| | - Aaron Rizzardo
- Department of Medicine, Division of Community Internal Medicine, University of British Columbia, British Columbia, Vancouver, Canada
| | - Andrea Maharaj
- International Collaboration on Repair Discoveries, University of British Columbia, British Columbia, Vancouver, Canada
| | - Michael Berger
- International Collaboration on Repair Discoveries, University of British Columbia, British Columbia, Vancouver, Canada.,Department of Medicine, Division of Physical Medicine and Rehabilitation, University of British Columbia, British Columbia, Vancouver, Canada
| | - Andrei Krassioukov
- International Collaboration on Repair Discoveries, University of British Columbia, British Columbia, Vancouver, Canada.,Department of Medicine, Division of Physical Medicine and Rehabilitation, University of British Columbia, British Columbia, Vancouver, Canada.,Spinal Cord Program, GF Strong Rehabilitation Centre, University of British Columbia, British Columbia, Vancouver, Canada
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Wilkinson RL, Castillo C, Herrity A, Wang D, Sharma M, Dietz N, Adams S, Khattar N, Nuno M, Drazin D, Boakye M, Ugiliweneza B. Opioid Dependence and Associated Health Care Utilization and Cost in Traumatic Spinal Cord Injury Population: Analysis Using Marketscan Database. Top Spinal Cord Inj Rehabil 2023; 29:118-130. [PMID: 36819927 PMCID: PMC9936895 DOI: 10.46292/sci22-00026] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2023]
Abstract
Background Postinjury pain is a well-known debilitating complication of spinal cord injury (SCI), often resulting in long-term, high-dose opioid use with the potential for dependence. There is a gap in knowledge about the risk of opioid dependence and the associated health care utilization and cost in SCI. Objectives To evaluate the association of SCI with postinjury opioid use and dependence and evaluate the effect of this opioid dependence on postinjury health care utilization. Methods Using the MarketScan Database, health care utilization claims data were queried to extract 7187 adults with traumatic SCI from 2000 to 2019. Factors associated with post-SCI opioid use and dependence, postinjury health care utilization, and payments were analyzed with generalized linear regression models. Results After SCI, individuals were more likely to become opioid users or transition from nondependent to dependent users (negative change: 31%) than become nonusers or transition from dependent to nondependent users (positive change: 14%, p < .0001). Individuals who were opioid-dependent users pre-SCI had more than 30 times greater odds of becoming dependent after versus not (OR 34; 95% CI, 26-43). Dependent users after injury (regardless of prior use status) had 2 times higher utilization payments and 1.2 to 6 times more health care utilization than nonusers. Conclusion Opioid use and dependence were associated with high health care utilization and cost after SCI. Pre-SCI opioid users were more likely to remain users post-SCI and were heavier consumers of health care. Pre- and postopioid use history should be considered for treatment decision-making in all individuals with SCI.
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Affiliation(s)
| | - Camilo Castillo
- Department of Neurological Surgery, University of Louisville, Louisville, Kentucky
| | - April Herrity
- Department of Neurological Surgery, University of Louisville, Louisville, Kentucky
- Kentucky Spinal Cord Injury Research Center, University of Louisville, Lousville, Kentucky
| | - Dengzhi Wang
- Department of Neurological Surgery, University of Louisville, Louisville, Kentucky
- Kentucky Spinal Cord Injury Research Center, University of Louisville, Lousville, Kentucky
| | - Mayur Sharma
- Department of Neurological Surgery, University of Louisville, Louisville, Kentucky
| | - Nick Dietz
- Department of Neurological Surgery, University of Louisville, Louisville, Kentucky
| | - Shawn Adams
- Department of Neurological Surgery, University of Louisville, Louisville, Kentucky
| | - Nicholas Khattar
- Department of Neurological Surgery, University of Louisville, Louisville, Kentucky
| | - Miriam Nuno
- Department of Public Health Science, University of California, Davis
| | - Doniel Drazin
- College of Medicine Pacific Northwest, Yamika, Washington
| | - Maxwell Boakye
- Department of Neurological Surgery, University of Louisville, Louisville, Kentucky
- Kentucky Spinal Cord Injury Research Center, University of Louisville, Lousville, Kentucky
| | - Beatrice Ugiliweneza
- Department of Neurological Surgery, University of Louisville, Louisville, Kentucky
- Kentucky Spinal Cord Injury Research Center, University of Louisville, Lousville, Kentucky
- Department of Health Management and Systems Science, University of Louisville, Louisville, Kentucky
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6
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Karran EL, Fryer CE, Middleton JW, Moseley GL. Pain and pain management experiences following spinal cord injury - a mixed methods study of Australian community-dwelling adults. Disabil Rehabil 2023; 45:455-468. [PMID: 35156498 DOI: 10.1080/09638288.2022.2034994] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
PURPOSE There is a high prevalence of persistent pain following SCI yet insights into its impact and the quality of pain care are limited. We aimed to explore, in-depth, the problem of persistent pain in Australian community-dwelling adults with a spinal cord injury (SCI). Our objectives were to investigate (i) how individuals experience persistent pain, (ii) how they experience pain care and (iii) the concordance between clinical practice guidelines for managing pain and reported care practices. METHODS We conducted a mixed-methods convergent parallel study. Adults with SCI and persistent pain completed a survey (n = 43); a subset of participants completed interviews (n = 10). We analysed the data from each method separately and then integrated the findings. RESULTS Results indicated that the life impact of persistent pain is variable but it can be more disabling than physical impairments and compound a sense of isolation and despair. Community-based management was reported to predominantly have a pharmacological focus, with occurrences of opioid misuse apparent in the data. Access to expert, comprehensive and individualised care was frequently reported as inadequate. CONCLUSION While some people with SCI and persistent pain can effectively self-manage their pain, for others the impact on quality of life is profound and complex care needs are commonly unmet.IMPLICATIONS FOR REHABILITATIONPersistent pain is a common consequence of SCI and profoundly impacts quality of life.Complex pain care needs are commonly unmet.Individuals require regular, comprehensive, biopsychosocial assessment.The effectiveness of pain management strategies must be monitored on an ongoing basis.Opportunities for personal self-management support must be available long-term.
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Affiliation(s)
- Emma L Karran
- Innovation, Implementation & Clinical Translation (IIMPACT) in Health, Kaurna Country, University of South Australia, Adelaide, Australia
| | - Caroline E Fryer
- Innovation, Implementation & Clinical Translation (IIMPACT) in Health, Kaurna Country, University of South Australia, Adelaide, Australia
| | - James W Middleton
- State Spinal Cord Injury Service, NSW Agency for Clinical Innovation, Sydney, Australia
- John Walsh Centre for Rehabilitation Research, Kolling Institute, Royal North Shore Hospital, St Leonards, Sydney, Australia
- Faculty of Medicine and Health, The University of Sydney, Sydney, Australia
| | - G Lorimer Moseley
- Innovation, Implementation & Clinical Translation (IIMPACT) in Health, Kaurna Country, University of South Australia, Adelaide, Australia
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Rau J, Weise L, Moore R, Terminel M, Brakel K, Cunningham R, Bryan J, Stefanov A, Hook MA. Intrathecal minocycline does not block the adverse effects of repeated, intravenous morphine administration on recovery of function after SCI. Exp Neurol 2023; 359:114255. [PMID: 36279935 DOI: 10.1016/j.expneurol.2022.114255] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2022] [Revised: 09/18/2022] [Accepted: 10/13/2022] [Indexed: 11/05/2022]
Abstract
Opioids are among the most effective analgesics for the management of pain in the acute phase of a spinal cord injury (SCI), and approximately 80% of patients are treated with morphine in the first 24 h following SCI. We have found that morphine treatment in the first 7 days after SCI increases symptoms of pain at 42 days post-injury and undermines the recovery of locomotor function in a rodent model. Prior research has implicated microglia/macrophages in opioid-induced hyperalgesia and the development of neuropathic pain. We hypothesized that glial activation may also underlie the development of morphine-induced pain and cell death after SCI. Supporting this hypothesis, our previous studies found that intrathecal and intravenous morphine increase the number of activated microglia and macrophages present at the spinal lesion site, and that the adverse effects of intrathecal morphine can be blocked with intrathecal minocycline. Recognizing that the cellular expression of opioid receptors, and the intracellular signaling pathways engaged, can change with repeated administration of opioids, the current study tested whether minocycline was also protective with repeated intravenous morphine administration, more closely simulating clinical treatment. Using a rat model of SCI, we co-administered intravenous morphine and intrathecal minocycline for the first 7 days post injury and monitored sensory and locomotor recovery. Contrary to our hypothesis and previous findings with intrathecal morphine, we found that minocycline did not prevent the negative effects of morphine. Surprisingly, we also found that intrathecal minocycline alone is detrimental for locomotor recovery after SCI. Using ex vivo cell cultures, we investigated how minocycline and morphine altered microglia/macrophage function. Commensurate with published studies, we found that minocycline blocked the effects of morphine on the release of pro-inflammatory cytokines but, like morphine, it increased glial phagocytosis. While phagocytosis is critical for the removal of cellular and extracellular debris at the spinal injury site, increased phagocytosis after injury has been linked to the clearance of stressed but viable neurons and protracted inflammation. In sum, our data suggest that both morphine and minocycline alter the acute immune response, and reduce locomotor recovery after SCI.
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Affiliation(s)
- Josephina Rau
- Department of Neuroscience and Experimental Therapeutics, Texas A&M Health Science Center, Address: 8447 Riverside Parkway, Medical and Research Education Building 1, Bryan, TX 77807, USA; Texas A&M Institute for Neuroscience, Address: 301 Old Main Drive, Interdisciplinary Life Sciences Building, College Station, TX 77843, USA.
| | - Lara Weise
- Department of Neuroscience and Experimental Therapeutics, Texas A&M Health Science Center, Address: 8447 Riverside Parkway, Medical and Research Education Building 1, Bryan, TX 77807, USA.
| | - Robbie Moore
- Department of Microbial Pathogenesis and Immunology, Texas A&M Institute for Neuroscience, Address: 8447 Riverside Parkway, Medical and Research Education Building 2, Bryan, TX 77807, USA.
| | - Mabel Terminel
- Department of Neuroscience and Experimental Therapeutics, Texas A&M Health Science Center, Address: 8447 Riverside Parkway, Medical and Research Education Building 1, Bryan, TX 77807, USA; Texas A&M Institute for Neuroscience, Address: 301 Old Main Drive, Interdisciplinary Life Sciences Building, College Station, TX 77843, USA
| | - Kiralyn Brakel
- Department of Neuroscience and Experimental Therapeutics, Texas A&M Health Science Center, Address: 8447 Riverside Parkway, Medical and Research Education Building 1, Bryan, TX 77807, USA; Texas A&M Institute for Neuroscience, Address: 301 Old Main Drive, Interdisciplinary Life Sciences Building, College Station, TX 77843, USA
| | - Rachel Cunningham
- Department of Neuroscience and Experimental Therapeutics, Texas A&M Health Science Center, Address: 8447 Riverside Parkway, Medical and Research Education Building 1, Bryan, TX 77807, USA
| | - Jessica Bryan
- Department of Neuroscience and Experimental Therapeutics, Texas A&M Health Science Center, Address: 8447 Riverside Parkway, Medical and Research Education Building 1, Bryan, TX 77807, USA; Texas A&M Institute for Neuroscience, Address: 301 Old Main Drive, Interdisciplinary Life Sciences Building, College Station, TX 77843, USA.
| | - Alexander Stefanov
- Department of Neuroscience and Experimental Therapeutics, Texas A&M Health Science Center, Address: 8447 Riverside Parkway, Medical and Research Education Building 1, Bryan, TX 77807, USA; Texas A&M Institute for Neuroscience, Address: 301 Old Main Drive, Interdisciplinary Life Sciences Building, College Station, TX 77843, USA.
| | - Michelle A Hook
- Department of Neuroscience and Experimental Therapeutics, Texas A&M Health Science Center, Address: 8447 Riverside Parkway, Medical and Research Education Building 1, Bryan, TX 77807, USA; Texas A&M Institute for Neuroscience, Address: 301 Old Main Drive, Interdisciplinary Life Sciences Building, College Station, TX 77843, USA.
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Rau J, Hemphill A, Araguz K, Cunningham R, Stefanov A, Weise L, Hook MA. Adverse Effects of Repeated, Intravenous Morphine on Recovery after Spinal Cord Injury in Young, Male Rats Are Blocked by a Kappa Opioid Receptor Antagonist. J Neurotrauma 2022; 39:1741-1755. [PMID: 35996351 PMCID: PMC10039279 DOI: 10.1089/neu.2022.0208] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Immediately following spinal cord injury (SCI) patients experience pain associated with injury to the spinal cord and nerves as well as with accompanying peripheral injuries. This pain is usually treated with opioids, and most commonly with morphine. However, in a rodent model we have shown that, irrespective of the route of administration, morphine administered in the acute phase of SCI undermines long-term locomotor recovery. Our previous data suggest that activation of kappa opioid receptors (KORs) mediates these negative effects. Blocking KORs with norbinaltorphimine (norBNI), prior to a single dose of epidural morphine, prevented the morphine-induced attenuation of locomotor recovery. Because numerous cellular changes occur with chronic opioid administration compared with a single dose, the current study tested whether norBNI was also effective in a more clinically relevant paradigm of repeated, intravenous morphine administration after SCI. We hypothesized that blocking KOR activation during repeated, intravenous morphine administration would also protect recovery. Supporting this hypothesis, we found that blocking KOR activation in young, male rats prevented the negative effects of morphine on locomotor recovery, although neither norBNI nor morphine had an effect on long-term pain at the doses used. We also found that norBNI treatment blocked the adverse effects of morphine on lesion size. These data suggest that a KOR antagonist given in conjunction with morphine may provide a clinical strategy for effective analgesia without compromising locomotor recovery after SCI.
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Affiliation(s)
- Josephina Rau
- Department of Neuroscience and Experimental Therapeutics, Texas A&M Health Science Center, Bryan, Texas, USA
- Texas A&M Institute for Neuroscience, Bryan, Texas, USA
| | - Annebel Hemphill
- Department of Neuroscience and Experimental Therapeutics, Texas A&M Health Science Center, Bryan, Texas, USA
| | - Kendall Araguz
- Department of Neuroscience and Experimental Therapeutics, Texas A&M Health Science Center, Bryan, Texas, USA
| | - Rachel Cunningham
- Department of Neuroscience and Experimental Therapeutics, Texas A&M Health Science Center, Bryan, Texas, USA
| | - Alexander Stefanov
- Department of Neuroscience and Experimental Therapeutics, Texas A&M Health Science Center, Bryan, Texas, USA
- Texas A&M Institute for Neuroscience, Bryan, Texas, USA
| | - Lara Weise
- Department of Neuroscience and Experimental Therapeutics, Texas A&M Health Science Center, Bryan, Texas, USA
| | - Michelle A. Hook
- Department of Neuroscience and Experimental Therapeutics, Texas A&M Health Science Center, Bryan, Texas, USA
- Texas A&M Institute for Neuroscience, Bryan, Texas, USA
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Eller OC, Willits AB, Young EE, Baumbauer KM. Pharmacological and non-pharmacological therapeutic interventions for the treatment of spinal cord injury-induced pain. FRONTIERS IN PAIN RESEARCH 2022; 3:991736. [PMID: 36093389 PMCID: PMC9448954 DOI: 10.3389/fpain.2022.991736] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2022] [Accepted: 08/05/2022] [Indexed: 11/29/2022] Open
Abstract
Spinal cord injury (SCI) is a complex neurophysiological disorder, which can result in many long-term complications including changes in mobility, bowel and bladder function, cardiovascular function, and metabolism. In addition, most individuals with SCI experience some form of chronic pain, with one-third of these individuals rating their pain as severe and unrelenting. SCI-induced chronic pain is considered to be "high impact" and broadly affects a number of outcome measures, including daily activity, physical and cognitive function, mood, sleep, and overall quality of life. The majority of SCI pain patients suffer from pain that emanates from regions located below the level of injury. This pain is often rated as the most severe and the underlying mechanisms involve injury-induced plasticity along the entire neuraxis and within the peripheral nervous system. Unfortunately, current therapies for SCI-induced chronic pain lack universal efficacy. Pharmacological treatments, such as opioids, anticonvulsants, and antidepressants, have been shown to have limited success in promoting pain relief. In addition, these treatments are accompanied by many adverse events and safety issues that compound existing functional deficits in the spinally injured, such as gastrointestinal motility and respiration. Non-pharmacological treatments are safer alternatives that can be specifically tailored to the individual and used in tandem with pharmacological therapies if needed. This review describes existing non-pharmacological therapies that have been used to treat SCI-induced pain in both preclinical models and clinical populations. These include physical (i.e., exercise, acupuncture, and hyper- or hypothermia treatments), psychological (i.e., meditation and cognitive behavioral therapy), and dietary interventions (i.e., ketogenic and anti-inflammatory diet). Findings on the effectiveness of these interventions in reducing SCI-induced pain and improving quality of life are discussed. Overall, although studies suggest non-pharmacological treatments could be beneficial in reducing SCI-induced chronic pain, further research is needed. Additionally, because chronic pain, including SCI pain, is complex and has both emotional and physiological components, treatment should be multidisciplinary in nature and ideally tailored specifically to the patient.
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Affiliation(s)
- Olivia C. Eller
- Department of Cell Biology and Physiology, University of Kansas Medical Center, Kansas City, KS, United States
| | - Adam B. Willits
- Department of Anesthesiology, University of Kansas Medical Center, Kansas City, KS, United States
| | - Erin E. Young
- Department of Cell Biology and Physiology, University of Kansas Medical Center, Kansas City, KS, United States
- Department of Anesthesiology, University of Kansas Medical Center, Kansas City, KS, United States
| | - Kyle M. Baumbauer
- Department of Cell Biology and Physiology, University of Kansas Medical Center, Kansas City, KS, United States
- Department of Anesthesiology, University of Kansas Medical Center, Kansas City, KS, United States
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10
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Lovell S, Simon B, Boudreau EC, Mankin J, Jeffery N. Randomized clinical trial comparing outcomes after fentanyl or ketamine-dexmedetomidine analgesia in thoracolumbar spinal surgery in dogs. J Vet Intern Med 2022; 36:1742-1751. [PMID: 35962706 PMCID: PMC9511085 DOI: 10.1111/jvim.16514] [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: 04/06/2022] [Accepted: 07/28/2022] [Indexed: 11/30/2022] Open
Abstract
Background Opioids are widely used for perioperative pain control in dogs undergoing spinal surgery, but alternatives may be required because data suggest that opioids exacerbate inflammation in the injured spinal cord and veterinary access to opioids may become more restricted in the future. Objectives To compare recovery of ambulation and other functions between spinal cord‐injured dogs receiving peri‐operative fentanyl and those receiving a ketamine‐dexmedetomidine combination. Animals A total of 102 client‐owned dogs undergoing decompressive surgery for thoracolumbar intervertebral disc herniation. Methods Randomized clinical trial. Dogs were randomized 1:1 to fentanyl or a ketamine‐dexmedetomidine combination for intra and postoperative analgesia. Primary outcome was time to recovery of ambulation; secondary outcomes were the postoperative Colorado Acute Pain Scale, the short‐form Glasgow Composite Measure Pain Scale, time to recovery of voluntary urination and time to unassisted eating. Results No difference was found in time to recovery of ambulation between groups (adjusted sub‐hazard ratio, 0.83; 95% confidence interval [CI], 0.55‐1.24; P = .36) or in pain scores (Colorado: χ2 = 14.74; P = .32; Glasgow: χ2 = 6.61; P = .76). Differences in time to recovery of eating and urination were small but favored ketamine‐dexmedetomidine (adjusted odds ratios, 3.31; 95% CI, 1.53‐7.16; P = .002 and 2.43; 95% CI, 1.00‐5.96; P = .05, respectively). Conclusions and Clinical Importance There was no evidence that, at the doses used, fentanyl impaired ambulatory outcome after surgery for thoracolumbar intervertebral disc herniation in dogs. Pain control appeared similar between groups. Secondary outcomes suggested minor benefits associated with ketamine‐dexmedetomidine. The ketamine‐dexmedetomidine combination appears to be a reasonable alternative to peri‐operative opioids.
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Affiliation(s)
- Stephanie Lovell
- Small Animal Clinical Sciences, Texas A&M University, College Station, Texas, USA
| | - Bradley Simon
- Small Animal Clinical Sciences, Texas A&M University, College Station, Texas, USA
| | - Elizabeth C Boudreau
- Small Animal Clinical Sciences, Texas A&M University, College Station, Texas, USA
| | - Joseph Mankin
- Small Animal Clinical Sciences, Texas A&M University, College Station, Texas, USA
| | - Nicholas Jeffery
- Small Animal Clinical Sciences, Texas A&M University, College Station, Texas, USA
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11
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Eller OC, Stair RN, Neal C, Rowe PS, Nelson-Brantley J, Young EE, Baumbauer KM. Comprehensive phenotyping of cutaneous afferents reveals early-onset alterations in nociceptor response properties, release of CGRP, and hindpaw edema following spinal cord injury. NEUROBIOLOGY OF PAIN (CAMBRIDGE, MASS.) 2022; 12:100097. [PMID: 35756343 PMCID: PMC9218836 DOI: 10.1016/j.ynpai.2022.100097] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/29/2021] [Revised: 06/09/2022] [Accepted: 06/10/2022] [Indexed: 11/30/2022]
Abstract
Spinal cord injury (SCI) is a complex syndrome that has profound effects on patient well-being, including the development of medically-resistant chronic pain. The mechanisms underlying SCI pain have been the subject of thorough investigation but remain poorly understood. While the majority of the research has focused on changes occurring within and surrounding the site of injury in the spinal cord, there is now a consensus that alterations within the peripheral nervous system, namely sensitization of nociceptors, contribute to the development and maintenance of chronic SCI pain. Using an ex vivo skin/nerve/DRG/spinal cord preparation to characterize afferent response properties following SCI, we found that SCI increased mechanical and thermal responding, as well as the incidence of spontaneous activity (SA) and afterdischarge (AD), in below-level C-fiber nociceptors 24 hr following injury relative to naïve controls. Interestingly, the distribution of nociceptors that exhibit SA and AD are not identical, and the development of SA was observed more frequently in nociceptors with low heat thresholds, while AD was found more frequently in nociceptors with high heat thresholds. We also found that SCI resulted in hindpaw edema and elevated cutaneous calcitonin gene-related peptide (CGRP) concentration that were not observed in naïve mice. These results suggest that SCI causes a rapidly developing nociceptor sensitization and peripheral inflammation that may contribute to the early emergence and persistence of chronic SCI pain.
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Affiliation(s)
- Olivia C. Eller
- Department of Anatomy and Cell Biology, University of Kansas Medical Center, Kansas City, KS, United States
| | - Rena N. Stair
- Department of Anatomy and Cell Biology, University of Kansas Medical Center, Kansas City, KS, United States
| | - Christopher Neal
- Kansas Intellectual and Developmental Disabilities Research Center, University of Kansas Medical Center, Kansas City, KS, United States
| | - Peter S.N. Rowe
- Department of Internal Medicine, University of Kansas Medical Center, Kansas City, KS, United States
- The Kidney Institute & Division of Nephrology, University of Kansas Medical Center, Kansas City, KS, United States
| | - Jennifer Nelson-Brantley
- Department of Anatomy and Cell Biology, University of Kansas Medical Center, Kansas City, KS, United States
| | - Erin E. Young
- Department of Anatomy and Cell Biology, University of Kansas Medical Center, Kansas City, KS, United States
- Department of Anesthesiology, University of Kansas Medical Center, Kansas City, KS, United States
- Center for Advancement in Managing Pain, School of Nursing, University of Connecticut, Storrs, CT, United States
- Department of Genetics and Genome Sciences, UConn Health, Farmington, CT, United States
- Department of Neuroscience, UConn Health, Farmington, CT, United States
| | - Kyle M. Baumbauer
- Department of Anatomy and Cell Biology, University of Kansas Medical Center, Kansas City, KS, United States
- Department of Anesthesiology, University of Kansas Medical Center, Kansas City, KS, United States
- Center for Advancement in Managing Pain, School of Nursing, University of Connecticut, Storrs, CT, United States
- Department of Neuroscience, UConn Health, Farmington, CT, United States
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12
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Peterson MD, Kamdar N, Haapala HJ, Brummett C, Hurvitz EA. Opioid prescription patterns among adults with cerebral palsy and spina bifida. Heliyon 2022; 8:e09918. [PMID: 35847615 PMCID: PMC9284449 DOI: 10.1016/j.heliyon.2022.e09918] [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: 02/07/2022] [Revised: 03/14/2022] [Accepted: 07/06/2022] [Indexed: 11/29/2022] Open
Abstract
Background Pain is the most common symptom of cerebral palsy and spina bifida (CP/SB). The objective of this study was to compare the opioid prescription patterns for differing pain types and overlapping pain among adults living with and without CP/SB. Methods Privately-insured beneficiaries were included if they had CP/SB (n = 22,647). Adults without CP/SB were also included as controls (n = 931,528). Oral morphine equivalents (OMEs) were calculated. A multivariable logistic regression was used to analyze the association between CP/SB and OMEs, across the three pain categories: (1) no pain, (2) isolated pain, and (3) pain multimorbidity. Results Adults living with CP/SB had a higher OME prescription pattern per year than adults without CP or SB (8,981.0 ± 5,183.0 vs. 4,549.1 ± 2,988.0), and for no pain (4,010.8 ± 828.1 vs. 1,623.53 ± 47.5), isolated pain (7,179.9 ± 378.8 vs. 3,531.0 ± 131.0), and pain multimorbidity (15,752.4 ± 1,395.5 vs. 8,492.9 ± 398.0) (all p < 0.001), and differences were to a clinically meaningful extent. Adjusted odds ratios (OR) for prescribed OMEs were higher for adults with CP/SB vs. control and (1) no pain (OR: 1.51; 95%CI: 1.46, 1.56), (2) isolated pain (OR: 1.48; 95%CI: 1.44, 1.52), and (3) pain multimorbidity (OR: 1.79; 95%CI: 1.72, 1.86). Conclusions Adults with CP/SB obtain significantly higher prescription of OMEs than adults without CP/SB.
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Affiliation(s)
- Mark D Peterson
- Department of Physical Medicine and Rehabilitation, Michigan Medicine, University of Michigan, Ann Arbor, MI, USA.,Institute for Healthcare Policy and Innovation, Michigan Medicine, University of Michigan, Ann Arbor, MI, USA
| | - Neil Kamdar
- Institute for Healthcare Policy and Innovation, Michigan Medicine, University of Michigan, Ann Arbor, MI, USA.,Department of Obstetrics and Gynecology, Michigan Medicine, University of Michigan, USA.,Department of Emergency Medicine, Michigan Medicine, University of Michigan, USA.,Department of Surgery, Michigan Medicine, University of Michigan, USA
| | - Heidi J Haapala
- Department of Anesthesiology, Michigan Medicine, University of Michigan, USA
| | - Chad Brummett
- Department of Anesthesiology, Michigan Medicine, University of Michigan, USA
| | - Edward A Hurvitz
- Department of Physical Medicine and Rehabilitation, Michigan Medicine, University of Michigan, Ann Arbor, MI, USA
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13
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Zhang XM, Lun MH, Du W, Ma F, Huang ZQ. The κ-Opioid Receptor Agonist U50488H Ameliorates Neuropathic Pain Through the Ca2+/CaMKII/CREB Pathway in Rats. J Inflamm Res 2022; 15:3039-3051. [PMID: 35645576 PMCID: PMC9140919 DOI: 10.2147/jir.s327234] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Accepted: 11/02/2021] [Indexed: 11/23/2022] Open
Abstract
Objective To observe the ameliorative effect of kappa opioid receptor (KOR) agonist on rats with neuropathic pain (NP) and investigate the mechanism of action of the calcium ion (Ca2+)/calcium/calmodulin-dependent protein kinase II (CaMKII)/cyclic AMP response element-binding protein (CREB) pathway. Methods A total of 40 Sprague Dawley rats were randomly divided into four groups: sham-operation group (Sham group), NP model group (NP group), NP + KOR agonist U50488H group (NU group) and NP + specific CaMKII antagonist (KN93) + U50488H group (NKU group). The thermal withdrawal latency (TWL) and mechanical withdrawal threshold (MWT) of each group of rats were determined. ELISA was applied to examine the changes in inflammatory factors and oxidative stress factors, and the apoptotic rate in dorsal root ganglia was observed using TUNEL staining. Ca2+ concentration, content of oxidative stress index ROS and the release of calcitonin gene-related peptide (CGRP) and N-methyl-D-aspartate receptor (NMDAR) in the dorsal root ganglia were measured by the immunofluorescence assay. Finally, Western blotting was performed to detect expression changes in the Ca2+/CaMKII/CREB pathway. Results The KOR agonist U50488H could improve the values of TWL and MWT of NP the rats, inhibit inflammatory responses and relieve oxidative stress injury. Its mechanisms of action were associated with U50488H repression of Ca2+ influx, reduction of CGRP and NMDAR releases in the dorsal root ganglia and decreases in CaMKII and CREB phosphorylations in NP rats. Conclusion The KOR agonist ameliorates NP through suppressing the activity of the Ca2+/CaMKII/CREB pathway.
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Affiliation(s)
- Xiao-Min Zhang
- Department of Anesthesiology, Cancer Hospital of China Medical University, Liaoning Cancer Hospital & Institution, NO.44 Xiaoheyan Road, Dadong District, Shenyang, Liaoning Province, 110042, People’s Republic of China
- Correspondence: Xiao-Min Zhang; Ze-Qing Huang Department of Anesthesiology, Cancer Hospital of China Medical University, Liaoning Cancer Hospital & Institution, No.44 Xiaoheyan Road, Dadong District, Shenyang, Liaoning Province, 110042, People’s Republic of China Email
| | - Ming-Hui Lun
- Department of Anesthesiology, Cancer Hospital of China Medical University, Liaoning Cancer Hospital & Institution, NO.44 Xiaoheyan Road, Dadong District, Shenyang, Liaoning Province, 110042, People’s Republic of China
| | - Wei Du
- Department of Anesthesiology, Cancer Hospital of China Medical University, Liaoning Cancer Hospital & Institution, NO.44 Xiaoheyan Road, Dadong District, Shenyang, Liaoning Province, 110042, People’s Republic of China
| | - Fang Ma
- Department of Anesthesiology, Cancer Hospital of China Medical University, Liaoning Cancer Hospital & Institution, NO.44 Xiaoheyan Road, Dadong District, Shenyang, Liaoning Province, 110042, People’s Republic of China
| | - Ze-Qing Huang
- Department of Anesthesiology, Cancer Hospital of China Medical University, Liaoning Cancer Hospital & Institution, NO.44 Xiaoheyan Road, Dadong District, Shenyang, Liaoning Province, 110042, People’s Republic of China
- Correspondence: Xiao-Min Zhang; Ze-Qing Huang Department of Anesthesiology, Cancer Hospital of China Medical University, Liaoning Cancer Hospital & Institution, No.44 Xiaoheyan Road, Dadong District, Shenyang, Liaoning Province, 110042, People’s Republic of China Email
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14
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Broad opioid antagonism amplifies disruption of locomotor function following therapy-like hindlimb stretching in spinal cord injured rats. Spinal Cord 2021; 60:312-319. [PMID: 34561547 DOI: 10.1038/s41393-021-00705-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Revised: 09/01/2021] [Accepted: 09/02/2021] [Indexed: 11/08/2022]
Abstract
STUDY DESIGN Preclinical pilot study. OBJECTIVES To test the hypothesis that spinal opioidergic circuitry contributes to muscle stretch-induced locomotor deficits. SETTING Kentucky Spinal Cord Injury Research Center, Louisville, KY, USA. METHODS A pilot study with eight female Sprague-Dawley rats that received 25 g-cm T10 contusion injuries and recovered for 5 weeks. Rats were divided into two groups with one group receiving subcutaneous injections of naltrexone dissolved in saline (15 mg/kg) or an equal volume of saline. Each group received a daily 24-minute stretching protocol during weeks 6, 8, and 11 post-injury. Locomotor function was assessed throughout using the BBB Open Field Locomotor Scale. RESULTS Consistent with previous findings, stretching reduced locomotor function in both naltrexone and saline groups. However, the loss of locomotor function appeared earlier in the naltrexone group. Animals in both groups had a similar rate of recovery following the termination of stretching. Interestingly, the administration of naltrexone did not influence acute thermal cutaneous nociceptive responses as measured by a tail-flick assay but caused a significant increase in spasticity following stretch. CONCLUSIONS The results of this study suggest that the endogenous opioid system plays a role in modulating the negative impact of muscle stretch on spinal cord motor circuitry that is vulnerable due to loss of descending input. The observed actions of the broad-spectrum opioid antagonist naltrexone imply that pharmaceuticals targeting the endogenous opioid system post-SCI may have unintended consequences.
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15
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Tadjalli A, Seven YB, Sharma A, McCurdy CR, Bolser DC, Levitt ES, Mitchell GS. Acute morphine blocks spinal respiratory motor plasticity via long-latency mechanisms that require toll-like receptor 4 signalling. J Physiol 2021; 599:3771-3797. [PMID: 34142718 DOI: 10.1113/jp281362] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2021] [Accepted: 06/15/2021] [Indexed: 12/22/2022] Open
Abstract
KEY POINTS While respiratory complications following opioid use are mainly mediated via activation of mu opioid receptors, long-latency off-target signalling via innate immune toll-like receptor 4 (TLR4) may impair other essential elements of breathing control such as respiratory motor plasticity. In adult rats, pre-treatment with a single dose of morphine blocked long-term facilitation (LTF) of phrenic motor output via a long-latency TLR4-dependent mechanism. In the phrenic motor nucleus, morphine triggered TLR4-dependent activation of microglial p38 MAPK - a key enzyme that orchestrates inflammatory signalling and is known to undermine phrenic LTF. Morphine-induced LTF loss may destabilize breathing, potentially contributing to respiratory side effects. Therefore, we suggest minimizing TLR-4 signalling may improve breathing stability during opioid therapy. ABSTRACT Opioid-induced respiratory dysfunction is a significant public health burden. While respiratory effects are mediated via mu opioid receptors, long-latency off-target opioid signalling through innate immune toll-like receptor 4 (TLR4) may modulate essential elements of breathing control, particularly respiratory motor plasticity. Plasticity in respiratory motor circuits contributes to the preservation of breathing in the face of destabilizing influences. For example, respiratory long-term facilitation (LTF), a well-studied model of respiratory motor plasticity triggered by acute intermittent hypoxia, promotes breathing stability by increasing respiratory motor drive to breathing muscles. Some forms of respiratory LTF are exquisitely sensitive to inflammation and are abolished by even a mild inflammation triggered by TLR4 activation (e.g. via systemic lipopolysaccharides). Since opioids induce inflammation and TLR4 activation, we hypothesized that opioids would abolish LTF through a TLR4-dependent mechanism. In adult Sprague Dawley rats, pre-treatment with a single systemic injection of the prototypical opioid agonist morphine blocks LTF expression several hours later in the phrenic motor system - the motor pool driving diaphragm muscle contractions. Morphine blocked phrenic LTF via TLR4-dependent mechanisms because pre-treatment with (+)-naloxone - the opioid inactive stereoisomer and novel small molecule TLR4 inhibitor - prevented impairment of phrenic LTF in morphine-treated rats. Morphine triggered TLR4-dependent activation of microglial p38 MAPK within the phrenic motor system - a key enzyme that orchestrates inflammatory signalling and undermines phrenic LTF. Morphine-induced LTF loss may destabilize breathing, potentially contributing to respiratory side effects. We suggest minimizing TLR-4 signalling may improve breathing stability during opioid therapy by restoring endogenous mechanisms of plasticity within respiratory motor circuits.
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Affiliation(s)
- Arash Tadjalli
- Breathing Research and Therapeutics Center, University of Florida, Gainesville, FL, USA.,Department of Physical Therapy, University of Florida, Gainesville, FL, USA
| | - Yasin B Seven
- Breathing Research and Therapeutics Center, University of Florida, Gainesville, FL, USA.,Department of Physical Therapy, University of Florida, Gainesville, FL, USA
| | - Abhisheak Sharma
- Department of Pharmaceutics, University of Florida, Gainesville, FL, USA
| | | | - Donald C Bolser
- Breathing Research and Therapeutics Center, University of Florida, Gainesville, FL, USA.,Department of Physiological Sciences, University of Florida, Gainesville, FL, USA
| | - Erica S Levitt
- Breathing Research and Therapeutics Center, University of Florida, Gainesville, FL, USA.,Department of Pharmacology and Therapeutics, University of Florida, Gainesville, FL, USA
| | - Gordon S Mitchell
- Breathing Research and Therapeutics Center, University of Florida, Gainesville, FL, USA.,Department of Physical Therapy, University of Florida, Gainesville, FL, USA
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16
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Round AM, Joo MC, Barakso CM, Fallah N, Noonan VK, Krassioukov AV. Neurogenic Bowel in Acute Rehabilitation Following Spinal Cord Injury: Impact of Laxatives and Opioids. J Clin Med 2021; 10:jcm10081673. [PMID: 33919666 PMCID: PMC8069767 DOI: 10.3390/jcm10081673] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Revised: 03/16/2021] [Accepted: 04/10/2021] [Indexed: 12/27/2022] Open
Abstract
Objective: To explore the association between bowel dysfunction and use of laxatives and opioids in an acute rehabilitation setting following spinal cord injury (SCI). Methods: Data was collected regarding individuals with acute traumatic/non-traumatic SCI over a two-year period (2012–2013) during both the week of admission and discharge of their inpatient stay. Results: An increase in frequency of bowel movement (BM) (p = 0.003) and a decrease in frequency of fecal incontinence (FI) per week (p < 0.001) between admission and discharge was found across all participants. There was a reduction in the number of individuals using laxatives (p = 0.004) as well as the number of unique laxatives taken (p < 0.001) between admission and discharge in our cohort. The number of individuals using opioids and the average dose of opioids in morphine milligram equivalents (MME) from admission to discharge were significantly reduced (p = 0.001 and p = 0.02, respectively). There was a positive correlation between the number of laxatives and frequency of FI at discharge (r = 0.194, p = 0.014), suggesting that an increase in laxative use results in an increased frequency of FI. Finally, there was a significant negative correlation between average dose of opioids (MME) and frequency of BM at discharge, confirming the constipating effect of opioids (r = −0.20, p = 0.009).
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Affiliation(s)
- Andrew M. Round
- International Collaboration on Repair Discoveries (ICORD), Department of Medicine, University of British Columbia, Vancouver, BC V5Z 1M9, Canada; (A.M.R.); (C.M.B.); (V.K.N.)
- Department of Medicine, University of British Columbia, Vancouver, BC V5Z 1M9, Canada;
- Department of Physical Medicine and Rehabilitation, University of Ottawa, Ottawa, ON K1H 8M2, Canada
| | - Min Cheol Joo
- Department of Rehabilitation Medicine and Institute of Wonkwang Medical Science, Wonkwang University School of Medicine, Iksan 570-749, Korea;
| | - Carolyn M. Barakso
- International Collaboration on Repair Discoveries (ICORD), Department of Medicine, University of British Columbia, Vancouver, BC V5Z 1M9, Canada; (A.M.R.); (C.M.B.); (V.K.N.)
| | - Nader Fallah
- Department of Medicine, University of British Columbia, Vancouver, BC V5Z 1M9, Canada;
- Praxis Spinal Cord Institute, Vancouver, BC V5Z 1M9, Canada
| | - Vanessa K. Noonan
- International Collaboration on Repair Discoveries (ICORD), Department of Medicine, University of British Columbia, Vancouver, BC V5Z 1M9, Canada; (A.M.R.); (C.M.B.); (V.K.N.)
- Praxis Spinal Cord Institute, Vancouver, BC V5Z 1M9, Canada
| | - Andrei V. Krassioukov
- International Collaboration on Repair Discoveries (ICORD), Department of Medicine, University of British Columbia, Vancouver, BC V5Z 1M9, Canada; (A.M.R.); (C.M.B.); (V.K.N.)
- Division of Physical Medicine and Rehabilitation, Department of Medicine, University of British Columbia, Vancouver, BC V5Z 2G9, Canada
- GF Strong Rehabilitation Centre, Vancouver Coastal Health, Vancouver, BC V5Z 2G9, Canada
- Correspondence: ; Tel.: +1-604-675-8819
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17
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DiPiro ND, Murday D, Corley EH, DiPiro TV, Krause JS. Opioid Use Among Individuals With Spinal Cord Injury: Prevalence Estimates Based on State Prescription Drug Monitoring Program Data. Arch Phys Med Rehabil 2020; 102:828-834. [PMID: 33227268 DOI: 10.1016/j.apmr.2020.10.128] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Revised: 09/21/2020] [Accepted: 10/13/2020] [Indexed: 11/26/2022]
Abstract
OBJECTIVE To identify the prevalence of opioid use in individuals with chronic spinal cord injury (SCI) living in South Carolina. DESIGN Cohort study. SETTING Data from 2 statewide population-based databases, an SCI Registry and the state prescription drug monitoring program, were linked and analyzed. PARTICIPANTS The study included individuals (N=503) with chronic (>1y) SCI who were injured between 2013 and 2014 in South Carolina and who survived at least 3 years postinjury. INTERVENTIONS Not applicable. MAIN OUTCOME MEASURES Filled opioid prescriptions over a 2-year period (months 13-36 after injury). The main outcomes were total number of days with an opioid prescription over the 2-year period, length of coverage period [(final day of prescription coverage+the days supplied)-first day of prescription coverage], average daily morphine milligram equivalents (MME) over the coverage period, and concurrent days covered by an opioid and a prescription for benzodiazepines, sedatives, or hypnotics. RESULTS A total of 53.5% of the cohort (269 individuals) filled at least 1 opioid prescription during their second or third year after SCI. In total, there were 3386 opioid fills during the 2-year study. On average, the total number of opioid prescription days was 293±367. The average coverage period was 389±290 days, and the average daily MME during the coverage period was 41±70 MME. Of those who filled an opioid prescription, 23% had high-risk fills (>50 MME), and 38% had concurrent prescriptions for benzodiazepines, sedatives, or hypnotics. CONCLUSIONS The prevalence of opioid use was high among individuals with chronic SCI, exceeding rates observed in the general population. Also concerning were the rates of high-risk fills, based on average daily MME and concurrent benzodiazepine, sedative, or hypnotic prescriptions. These findings, taken together with those of earlier studies, should be used by providers to assess and monitor opioid use, decrease concurrent high-risk medication use, and attenuate the risk of adverse outcomes.
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Affiliation(s)
- Nicole D DiPiro
- College of Health Professions, Medical University of South Carolina, Charleston, SC
| | - David Murday
- Arnold School of Public Health, University of South Carolina, Columbia, SC
| | - Elizabeth H Corley
- Arnold School of Public Health, University of South Carolina, Columbia, SC
| | | | - James S Krause
- College of Health Professions, Medical University of South Carolina, Charleston, SC.
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18
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Shaw E, Saulino M. Management Strategies for Spinal Cord Injury Pain Updated for the Twenty-First Century. Phys Med Rehabil Clin N Am 2020; 31:369-378. [PMID: 32624100 DOI: 10.1016/j.pmr.2020.03.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Traumatic spinal cord injury (SCI) often results in several life-altering impairments, including paralysis, sensory loss, and neurogenic bowel/bladder dysfunction. Some of these SCI-related conditions can be accommodated with compensatory strategies. Perhaps no SCI-associated condition is more troublesome and recalcitrant to the treating physiatrist than chronic neuropathic pain. In addition to the expected challenges in treating any chronic pain condition, treatment of SCI-related pain has the added difficulty of disruption of normal neural pathways that subserve pain transmission and attenuation. This article reviews selected treatment strategies for SCI-associated neuropathic pain.
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Affiliation(s)
- Erik Shaw
- Shepherd Spine and Pain Institute, 2020 Peachtree Street Northwest, Atlanta, GA 30309, USA.
| | - Michael Saulino
- Sidney Kimmel Medical College, MossRehab, 60 Township Line Road, Elkins Park, PA 19027, USA
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19
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Janzadeh A, Karami Z, Hosseini M, Zarepour L, Yousefifard M, Nasirinezhad F. The role of CGRP receptor antagonist (CGRP8-37) and Endomorphin-1 combination therapy on neuropathic pain alleviation and expression of Sigma-1 receptors and antioxidants in rats. J Chem Neuroanat 2020; 106:101771. [PMID: 32092447 DOI: 10.1016/j.jchemneu.2020.101771] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2019] [Revised: 01/19/2020] [Accepted: 02/20/2020] [Indexed: 12/22/2022]
Abstract
BACKGROUND Spinal cord injury is one of the most common causes of neuropathic pain which is not responsive to common treatments. Owing to the adverse effects of drugs, it seems that the use of Calcitonin Gene-Related Protein (CGRP) receptor antagonist or Morphine and their combination could be an appropriate strategy for pain alleviation. METHOD To achieve the objective, fifty six male Wistar rats were divided into seven groups. CGRP8-37 and Endomorphin-1 alone, and in combinated administration, as bolus and continues dose. Both mechanical and cold allodynia, and mechanical hyperalgesia were evaluated before and also15 and 60 min after injection to indicate the efficacy of the therapies in the acute and chronic circumstances on pain induced by spinal cord compression injury. Sigma-1 receptor experssion, oxidant and antioxidant activity after the seven days of the drug adminestration were evaluated. RESULT The results showed that Endomorphin-1and CGRP8-37 injections were able to reduce neuropathic pain after spinal cord compression injury. Compared to Endomorphin-1, or CGRP8-37 monotherapy, combination therapy did not show more attenuating effects on the pain threshold. Compared to the continous administration of Endomorphin-1 alone, and CGRP8-37 alone, the continous combination therapy did not reduce the pain further. Molecular studies disclosed the increased expression of the Sigma1 receptor, in the spinal cord after administration of Endomorphin-1, and CGRP8-37 alone, as well as combination therapy. Although, an increase in GPx and SOD activity, and decrease in MDA activity was observed in the combination therapy. CONCLUSION Our results demonstrate that either Endomorphin-1 or CGRP receptor antagonist is able to decrease the neuropathic pain after SCI but combination therapy by a CGRP receptor antagonist and Endomorphin-1 did not make any further reduction in pain sensation.
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Affiliation(s)
- Atousa Janzadeh
- Radiation Biology Research Center, Iran University of Medical Sciences, Tehran, Iran
| | - Zohreh Karami
- Physiology Research Center, Iran University of Medical Sciences, Tehran, Iran
| | - Marjan Hosseini
- Physiology Research Center, Iran University of Medical Sciences, Tehran, Iran
| | - Leila Zarepour
- Physiology Research Center, Iran University of Medical Sciences, Tehran, Iran
| | - Mahmoud Yousefifard
- Physiology Research Center, Iran University of Medical Sciences, Tehran, Iran
| | - Farinaz Nasirinezhad
- Physiology Research Center, Iran University of Medical Sciences, Tehran, Iran; Department of Physiology, Faculty of Medicine, Iran University of Medical Sciences, Tehran, Iran.
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Vierck C. Mechanisms of Below-Level Pain Following Spinal Cord Injury (SCI). THE JOURNAL OF PAIN 2019; 21:262-280. [PMID: 31493490 DOI: 10.1016/j.jpain.2019.08.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Revised: 07/05/2019] [Accepted: 08/07/2019] [Indexed: 12/18/2022]
Abstract
Mechanisms of below-level pain are discoverable as neural adaptations rostral to spinal injury. Accordingly, the strategy of investigations summarized here has been to characterize behavioral and neural responses to below-level stimulation over time following selective lesions of spinal gray and/or white matter. Assessments of human pain and the pain sensitivity of humans and laboratory animals following spinal injury have revealed common disruptions of pain processing. Interruption of the spinothalamic pathway partially deafferents nocireceptive cerebral neurons, rendering them spontaneously active and hypersensitive to remaining inputs. The spontaneous activity among these neurons is disorganized and unlikely to generate pain. However, activation of these neurons by their remaining inputs can result in pain. Also, injury to spinal gray matter results in a cascade of secondary events, including excitotoxicity, with rostral propagation of excitatory influences that contribute to chronic pain. Establishment and maintenance of below-level pain results from combined influences of injured and spared axons in the spinal white matter and injured neurons in spinal gray matter on processing of nociception by hyperexcitable cerebral neurons that are partially deafferented. A model of spinal stenosis suggests that ischemic injury to the core spinal region can generate below-level pain. Additional questions are raised about demyelination, epileptic discharge, autonomic activation, prolonged activity of C nocireceptive neurons, and thalamocortical plasticity in the generation of below-level pain. PERSPECTIVE: An understanding of mechanisms can direct therapeutic approaches to prevent development of below-level pain or arrest it following spinal cord injury. Among the possibilities covered here are surgical and other means of attenuating gray matter excitotoxicity and ascending propagation of excitatory influences from spinal lesions to thalamocortical systems involved in pain encoding and arousal.
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Affiliation(s)
- Chuck Vierck
- Department of Neuroscience, University of Florida College of Medicine and McKnight Brain Institute, Gainesville, Florida.
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21
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Franz S, Schulz B, Wang H, Gottschalk S, Grüter F, Friedrich J, Glaesener JJ, Bock F, Schott C, Müller R, Schultes K, Landmann G, Gerner HJ, Dietz V, Treede RD, Weidner N. Management of pain in individuals with spinal cord injury: Guideline of the German-Speaking Medical Society for Spinal Cord Injury. GERMAN MEDICAL SCIENCE : GMS E-JOURNAL 2019; 17:Doc05. [PMID: 31354397 PMCID: PMC6637293 DOI: 10.3205/000271] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Indexed: 12/19/2022]
Abstract
Introduction: Pain is a prominent complication in spinal cord injury (SCI). It can either occur as a direct or as an indirect consequence of SCI and it often heavily influences the quality of life of affected individuals. In SCI, nociceptive and neuropathic pain can equally emerge at the same time above or below the level of injury. Thus, classification and grading of pain is frequently difficult. Effective treatment of SCI-related pain in general and of neuropathic pain in particular is challenging. Current treatment options are sparse and their evidence is considered to be limited. Considering these aspects, a clinical practice guideline was developed as basis for an optimized, comprehensive and standardized pain management in SCI-related pain. Methods: The German-Speaking Medical Society for Spinal Cord Injury (Deutschsprachige Medizinische Gesellschaft für Paraplegiologie – DMGP) developed a clinical practice guideline that received consensus from seven further German-speaking medical societies and one patient organization. The evidence base from clinical trials and meta-analyses was summarized and subjected to a structured consensus-process in accordance with the regulations of the Association of Scientific Medical Societies in Germany (AWMF) and the methodological requirements of the “German instrument for methodological guideline appraisal”. Results: This consensus-based guideline (S2k classification according to the AWMF guidance manual and rules) resulted in seven on-topic statements and 17 specific recommendations relevant to the classification, assessment and therapy of pain directly or indirectly caused by SCI. Recommended therapeutic approaches comprise pharmacological (e.g. nonsteroidal anti-inflammatory drugs or anticonvulsants) and non-pharmacological (e.g. physical activity or psychotherapeutic techniques) strategies for both nociceptive and neuropathic pain. Discussion: Assessment of SCI-related pain is standardized and respective methods in terms of examination, classification and grading of pain are already in use and validated in German language. In contrast, valid, evidence-based and efficient therapeutic options are limited and ask for further clinical studies, ideally randomized controlled trials and meta-analyses.
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Affiliation(s)
- Steffen Franz
- Spinal Cord Injury Center, Heidelberg University Hospital, Heidelberg, Germany
| | - Barbara Schulz
- BG Klinikum Bergmannstrost, Abteilung Medizinische Psychologie, Spezielle Traumatherapie (DeGPT), Hypnotherapie und Hypnose (DGH), Halle, Germany
| | - Haili Wang
- Spinal Cord Injury Center, Heidelberg University Hospital, Heidelberg, Germany
| | - Sabine Gottschalk
- Zentralklinik Bad Berka GmbH, Querschnittgelähmten-Zentrum/Klinik für Paraplegiologie und Neuro-Urologie, Bad Berka, Germany
| | - Florian Grüter
- Kliniken Beelitz GmbH, Neurologische Rehabilitationsklinik, Beelitz-Heilstätten, Germany
| | | | | | | | - Cordelia Schott
- Orthopädische Privatpraxis Schott (OPS), Im Medizinischen Zentrum Essen, Germany
| | | | - Kevin Schultes
- Fördergemeinschaft der Querschnittgelähmten in Deutschland e.V., Lobbach, Germany
| | - Gunther Landmann
- Center for Pain Medicine, Swiss Paraplegic Centre, Nottwil, Switzerland
| | - Hans Jürgen Gerner
- Fördergemeinschaft der Querschnittgelähmten in Deutschland e.V., Lobbach, Germany
| | - Volker Dietz
- Spinal Cord Injury Center, University Hospital Balgrist, Zurich, Switzerland
| | - Rolf-Detlef Treede
- Chair of Neurophysiology, Centre of Biomedicine and Medical Technology Mannheim, Heidelberg University, Mannheim, Germany
| | - Norbert Weidner
- Spinal Cord Injury Center, Heidelberg University Hospital, Heidelberg, Germany
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Medicate or Meditate? Greater Pain Acceptance is Related to Lower Pain Medication Use in Persons With Chronic Pain and Spinal Cord Injury. Clin J Pain 2019; 34:357-365. [PMID: 28877136 DOI: 10.1097/ajp.0000000000000550] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
OBJECTIVES There is little information about whether use of pain self-management skills that are common targets of psychosocial interventions for pain are associated with reduced reliance on pain medications. The aim of this study was to test whether higher chronic pain acceptance, which is a readily modified pain self-management approach, is related to lower use of pain medications (eg, opioid medications, and gabapentinoids) in a sample with chronic pain and spinal cord injury (SCI). MATERIALS AND METHODS This is a cross-sectional survey study of pain medication use, pain severity and distribution (Brief Pain Inventory [BPI]), depressive symptoms (Patient Health Questionnaire-9 [PHQ-9]), and chronic pain acceptance (Chronic Pain Acceptance Questionnaire [CPAQ]) administered to a sample of 120 adults with chronic pain and SCI. RESULTS Regression results indicated that, above and beyond the effects of pain intensity, pain distribution, and depressive symptoms, higher pain acceptance was related to lower use of all types of pain medications, and lower odds of using opioid medications or gabapentinoids. Pain intensity was not related to pain medication use, but greater pain distribution was related to using more pain medications in general and to greater odds of using gabapentinoids. DISCUSSION Findings from this study indicate that those with chronic pain and SCI who have a more accepting orientation to pain are less reliant on pain medications, and thereby experience lower risks associated with medication consumption. Longitudinal, daily process, and clinical trial studies are needed to better understand the association between pain acceptance and pain medication consumption.
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23
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Wang Y, Ye F, Huang C, Xue F, Li Y, Gao S, Qiu Z, Li S, Chen Q, Zhou H, Song Y, Huang W, Tan W, Wang Z. Bioinformatic Analysis of Potential Biomarkers for Spinal Cord-injured Patients with Intractable Neuropathic Pain. Clin J Pain 2018; 34:825-830. [PMID: 29547407 PMCID: PMC6078488 DOI: 10.1097/ajp.0000000000000608] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2017] [Revised: 10/05/2017] [Accepted: 10/22/2017] [Indexed: 12/30/2022]
Abstract
BACKGROUND Neuropathic pain is one of the common complications after spinal cord injury (SCI), affecting individuals' quality of life. The molecular mechanism for neuropathic pain after SCI is still unclear. We aimed to discover potential genes and microRNAs (miRNAs) related to neuropathic pain by the bioinformatics method. METHODS Microarray data of GSE69901 were obtained from Gene Expression Omnibus (GEO) database. Peripheral blood samples from individuals with or without neuropathic pain after SCI were collected. Twelve samples from individuals with neuropathic pain and 13 samples from individuals without pain as controls were included in the downloaded microarray. Differentially expressed genes (DEGs) between the neuropathic pain group and the control group were detected using the GEO2R online tool. Functional enrichment analysis of DEGs was performed using the DAVID database. Protein-protein interaction network was constructed from the STRING database. MiRNAs targeting these DEGs were obtained from the miRNet database. A merged miRNA-DEG network was constructed and analyzed with Cytoscape software. RESULTS In total, 1134 DEGs were identified between individuals with or without neuropathic pain (case and control), and 454 biological processes were enriched. We identified 4 targeted miRNAs, including mir-204-5p, mir-519d-3p, mir-20b-5p, mir-6838-5p, which may be potential biomarkers for SCI patients. CONCLUSION Protein modification and regulation of the biological process of the central nervous system may be a risk factor in SCI. Certain genes and miRNAs may be potential biomarkers for the prediction of and potential targets for the prevention and treatment of neuropathic pain after SCI.
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Affiliation(s)
- Yimin Wang
- Department of Anesthesiology, The First Affiliated Hospital of Sun Yat-sen University
- Department of Anesthesiology, Guangdong Second Provincial General Hospital, Guangzhou
| | - Fang Ye
- Department of Anesthesiology, The First Affiliated Hospital of Sun Yat-sen University
| | - Chanyan Huang
- Department of Anesthesiology, The First Affiliated Hospital of Sun Yat-sen University
| | - Faling Xue
- Department of Anesthesiology, The First Affiliated Hospital of Sun Yat-sen University
| | - Yingyuan Li
- Department of Anesthesiology, The First Affiliated Hospital of Sun Yat-sen University
| | - Shaowei Gao
- Department of Anesthesiology, The First Affiliated Hospital of Sun Yat-sen University
| | - Zeting Qiu
- Zhongshan School of Medicine, Sun Yat-sen University, Guangdong, China
| | - Si Li
- Zhongshan School of Medicine, Sun Yat-sen University, Guangdong, China
| | - Qinchang Chen
- Zhongshan School of Medicine, Sun Yat-sen University, Guangdong, China
| | - Huaqiang Zhou
- Zhongshan School of Medicine, Sun Yat-sen University, Guangdong, China
| | - Yiyan Song
- Zhongshan School of Medicine, Sun Yat-sen University, Guangdong, China
| | - Wenqi Huang
- Department of Anesthesiology, The First Affiliated Hospital of Sun Yat-sen University
| | - Wulin Tan
- Department of Anesthesiology, The First Affiliated Hospital of Sun Yat-sen University
| | - Zhongxing Wang
- Department of Anesthesiology, The First Affiliated Hospital of Sun Yat-sen University
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Emamhadi M, Andalib S. Nerve transfer to relieve pain in upper brachial plexus injuries: Does it work? Clin Neurol Neurosurg 2017; 163:67-70. [DOI: 10.1016/j.clineuro.2017.10.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2017] [Revised: 10/05/2017] [Accepted: 10/13/2017] [Indexed: 11/16/2022]
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25
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Krause JS, Cao Y, Clark JMR. Pain Intensity, Interference, and Medication Use After Spinal Cord Injury: Association With Risk of Mortality After Controlling for Socioeconomic and Other Health Factors. Arch Phys Med Rehabil 2017; 98:2464-2470. [PMID: 28652067 DOI: 10.1016/j.apmr.2017.05.024] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2017] [Revised: 05/08/2017] [Accepted: 05/25/2017] [Indexed: 11/15/2022]
Abstract
OBJECTIVE To identify the association of pain intensity, pain interference, and pain medication use with risk of mortality after spinal cord injury, controlling for demographic, injury, socioeconomic, and health factors. DESIGN Prospective cohort study. SETTING Academic medical center. PARTICIPANTS All participants (N=2535) had traumatic spinal cord injury of at least 1-year duration at enrollment, with noncomplete recovery (American Spinal Injury Association Impairment Scale grades A-D). Mortality status was obtained for 2535 individuals, and 335 were deceased as of 2014. INTERVENTIONS Not applicable. MAIN OUTCOME MEASURES Mortality status as of December 31, 2014, identified by the National Death Index. RESULTS Preliminary bivariate analyses indicated that deceased participants were more likely to be older at injury, have more years postinjury, be men, and have a severe injury, low income, less education, and poorer health indicators. The final Cox model indicated that those who used pain medication daily were 51% more likely to be deceased at follow-up (hazard ratio [HR], 1.51). Pain intensity and pain interference were not statistically significant. Nonchronic pressure ulcer was related to 67% higher mortality risk (HR, 1.67), and chronic pressure ulcer was related to 122% higher risk (HR, 2.22). Other health indicators also increased the risk of mortality from 43% to 73%, including hospitalization (HR, 1.54), depression (HR, 1.43), and amputation (HR, 1.73). CONCLUSIONS Prescription pain medication use appears to have a direct association with mortality, beyond that associated with other characteristics, and should become a strong focus of prevention efforts.
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Affiliation(s)
- James S Krause
- College of Health Professions, Medical University of South Carolina, Charleston, SC.
| | - Yue Cao
- College of Health Professions, Medical University of South Carolina, Charleston, SC
| | - Jillian M R Clark
- College of Health Professions, Medical University of South Carolina, Charleston, SC
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26
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Bonacorso HG, Rosa WC, Oliveira SM, Brusco I, Brum ES, Rodrigues MB, Frizzo CP, Zanatta N. Synthesis of novel trifluoromethyl-substituted spiro-[chromeno[4,3-d]pyrimidine-5,1'-cycloalkanes], and evaluation of their analgesic effects in a mouse pain model. Bioorg Med Chem Lett 2017; 27:1551-1556. [PMID: 28259627 DOI: 10.1016/j.bmcl.2017.02.036] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2016] [Revised: 02/14/2017] [Accepted: 02/16/2017] [Indexed: 11/29/2022]
Abstract
Herein we report the synthesis of twelve 2,5-substituted 4-(trifluoromethyl)-spirochromeno[4,3-d]pyrimidines (7-10), as well as an evaluation of their analgesic effect in a mouse pain model. The nine new chromeno[4,3-d]pyrimidines (7-9) were synthesized from the cyclocondensation reactions of three 2,2,2-trifluoro-1-(4-methoxyspiro[chromene-2,1'-cycloalkane]-3-yl)ethanones (3) containing 5-, 6- and 7-membered spirocycloalkanes, with some well-known amidine salts (4-6) [NH2CR(NH)]-in which R=Me, Ph, and NH2-at yields of 60-95%. Subsequently, three new 2-(pyrrol-1-yl)-4-(trifluoromethyl)-chromeno[4,3-d]pyrimidines (10) were obtained through a Clauson-Kaas reaction between the respective 2-(amino)-4-(trifluoromethyl)-chromeno[4,3-d]pyrimidines (9) and 2,5-dimethoxy-tetrahydrofuran. The analgesic evaluation showed that these 4-(trifluoromethyl)chromeno[4,3-d]pyrimidines (100mg/kg, p.o.) and Ketoprofen (100mg/kg, p.o.) significantly reduced capsaicin-induced spontaneous nociception. Moreover, the 2-pyrrolyl-spirocyclohexane derivative 10b (100 and 300mg/kg, p.o.) had an anti-allodynic effect comparable to Ketoprofen (100 and 300mg/kg, p.o.) in the arthritic pain model, without causing locomotor alterations in the mice. These results suggest that the compound 10b is a promising molecule for new analgesic drugs in the treatment of pathological pain, such as in arthritis.
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Affiliation(s)
- Helio G Bonacorso
- Núcleo de Química de Heterociclos (NUQUIMHE), Departamento de Química, Universidade Federal de Santa Maria, 97.105-900 Santa Maria, RS, Brazil.
| | - Wilian C Rosa
- Núcleo de Química de Heterociclos (NUQUIMHE), Departamento de Química, Universidade Federal de Santa Maria, 97.105-900 Santa Maria, RS, Brazil
| | - Sara M Oliveira
- Laboratório de Neurotoxicidade e Psicofarmacologia, Departamento de Bioquímica Toxicológica, Universidade Federal de Santa Maria, 97.105-900 Santa Maria, RS, Brazil
| | - Indiara Brusco
- Laboratório de Neurotoxicidade e Psicofarmacologia, Departamento de Bioquímica Toxicológica, Universidade Federal de Santa Maria, 97.105-900 Santa Maria, RS, Brazil
| | - Evelyne S Brum
- Laboratório de Neurotoxicidade e Psicofarmacologia, Departamento de Bioquímica Toxicológica, Universidade Federal de Santa Maria, 97.105-900 Santa Maria, RS, Brazil
| | - Melissa B Rodrigues
- Núcleo de Química de Heterociclos (NUQUIMHE), Departamento de Química, Universidade Federal de Santa Maria, 97.105-900 Santa Maria, RS, Brazil
| | - Clarissa P Frizzo
- Núcleo de Química de Heterociclos (NUQUIMHE), Departamento de Química, Universidade Federal de Santa Maria, 97.105-900 Santa Maria, RS, Brazil
| | - Nilo Zanatta
- Núcleo de Química de Heterociclos (NUQUIMHE), Departamento de Química, Universidade Federal de Santa Maria, 97.105-900 Santa Maria, RS, Brazil
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27
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Hook MA, Woller SA, Bancroft E, Aceves M, Funk MK, Hartman J, Garraway SM. Neurobiological Effects of Morphine after Spinal Cord Injury. J Neurotrauma 2016; 34:632-644. [PMID: 27762659 DOI: 10.1089/neu.2016.4507] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Opioids and non-steroidal anti-inflammatory drugs are used commonly to manage pain in the early phase of spinal cord injury (SCI). Despite its analgesic efficacy, however, our studies suggest that intrathecal morphine undermines locomotor recovery and increases lesion size in a rodent model of SCI. Similarly, intravenous (IV) morphine attenuates locomotor recovery. The current study explores whether IV morphine also increases lesion size after a spinal contusion (T12) injury and quantifies the cell types that are affected by early opioid administration. Using an experimenter-administered escalating dose of IV morphine across the first seven days post-injury, we quantified the expression of neuron, astrocyte, and microglial markers at the injury site. SCI decreased NeuN expression relative to shams. In subjects with SCI treated with IV morphine, virtually no NeuN+ cells remained across the rostral-caudal extent of the lesion. Further, whereas SCI per se increased the expression of astrocyte and microglial markers (glial fibrillary acidic protein and OX-42, respectively), morphine treatment decreased the expression of these markers. These cellular changes were accompanied by attenuation of locomotor recovery (Basso, Beattie, Bresnahan scores), decreased weight gain, and the development of opioid-induced hyperalgesia (increased tactile reactivity) in morphine-treated subjects. These data suggest that morphine use is contraindicated in the acute phase of a spinal injury. Faced with a lifetime of intractable pain, however, simply removing any effective analgesic for the management of SCI pain is not an ideal option. Instead, these data underscore the critical need for further understanding of the molecular pathways engaged by conventional medications within the pathophysiological context of an injury.
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Affiliation(s)
- Michelle A Hook
- 1 Texas A&M University Institute for Neuroscience, Texas A&M University , College Station, Texas.,2 Department of Neuroscience and Experimental Therapeutics, Texas A&M Health Science Center , Bryan, Texas
| | - Sarah A Woller
- 3 Department of Anesthesiology, University of California , San Diego, California
| | - Eric Bancroft
- 2 Department of Neuroscience and Experimental Therapeutics, Texas A&M Health Science Center , Bryan, Texas
| | - Miriam Aceves
- 1 Texas A&M University Institute for Neuroscience, Texas A&M University , College Station, Texas.,2 Department of Neuroscience and Experimental Therapeutics, Texas A&M Health Science Center , Bryan, Texas
| | - Mary Katherine Funk
- 2 Department of Neuroscience and Experimental Therapeutics, Texas A&M Health Science Center , Bryan, Texas
| | - John Hartman
- 2 Department of Neuroscience and Experimental Therapeutics, Texas A&M Health Science Center , Bryan, Texas
| | - Sandra M Garraway
- 4 Department of Physiology, Emory University School of Medicine , Atlanta, Georgia
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28
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Ellis A, Grace PM, Wieseler J, Favret J, Springer K, Skarda B, Hutchinson MR, Falci S, Rice KC, Maier SF, Watkins LR, Watkins LR. Morphine amplifies mechanical allodynia via TLR4 in a rat model of spinal cord injury. Brain Behav Immun 2016; 58:348-356. [PMID: 27519154 PMCID: PMC5067205 DOI: 10.1016/j.bbi.2016.08.004] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/02/2016] [Revised: 08/07/2016] [Accepted: 08/07/2016] [Indexed: 01/09/2023] Open
Abstract
Central neuropathic pain (CNP) is a pervasive, debilitating problem that impacts thousands of people living with central nervous system disorders, including spinal cord injury (SCI). Current therapies for treating this type of pain are ineffective and often have dose-limiting side effects. Although opioids are one of the most commonly used CNP treatments, recent animal literature has indicated that administering opioids shortly after a traumatic injury can actually have deleterious effects on long-term health and recovery. In order to study the deleterious effects of administering morphine shortly after trauma, we employed our low thoracic (T13) dorsal root avulsion model (Spinal Neuropathic Avulsion Pain, SNAP). Administering a weeklong course of 10mg/kg/day morphine beginning 24h after SNAP resulted in amplified mechanical allodynia. Co-administering the non-opioid toll-like receptor 4 (TLR4) antagonist (+)-naltrexone throughout the morphine regimen prevented morphine-induced amplification of SNAP. Exploration of changes induced by early post-trauma morphine revealed that this elevated gene expression of TLR4, TNF, IL-1β, and NLRP3, as well as IL-1β protein at the site of spinal cord injury. These data suggest that a short course of morphine administered early after spinal trauma can exacerbate CNP in the long term. TLR4 initiates this phenomenon and, as such, may be potential therapeutic targets for preventing the deleterious effects of administering opioids after traumatic injury.
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Affiliation(s)
- Amanda Ellis
- University of Colorado Boulder, Department of Psychology and Neuroscience, Center for Neuroscience, Boulder, CO, USA
| | - Peter M. Grace
- University of Colorado Boulder, Department of Psychology and Neuroscience, Center for Neuroscience, Boulder, CO, USA,School of Medicine, University of Adelaide, Adelaide, SA, Australia
| | - Julie Wieseler
- University of Colorado Boulder, Department of Psychology and Neuroscience, Center for Neuroscience, Boulder, CO, USA
| | - Jacob Favret
- University of Colorado Boulder, Department of Psychology and Neuroscience, Center for Neuroscience, Boulder, CO, USA
| | - Kendra Springer
- University of Colorado Boulder, Department of Psychology and Neuroscience, Center for Neuroscience, Boulder, CO, USA
| | - Bryce Skarda
- University of Colorado Boulder, Department of Psychology and Neuroscience, Center for Neuroscience, Boulder, CO, USA
| | - Mark R. Hutchinson
- School of Medicine, University of Adelaide, Adelaide, SA, Australia,Australian Research Council Centre of Excellence for Nanoscale BioPhotonics, Australia
| | | | - Kenner C. Rice
- Chemical Biology Research Branch, National Institute on Drug Abuse and National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Rockville, MD, USA
| | - Steven F. Maier
- University of Colorado Boulder, Department of Psychology and Neuroscience, Center for Neuroscience, Boulder, CO, USA
| | - Linda R. Watkins
- University of Colorado Boulder, Department of Psychology and Neuroscience, Center for Neuroscience, Boulder, CO, USA,Corresponding author: Linda R. Watkins, Department of Psychology & Neuroscience, Campus Box 345, University of Colorado Boulder, Boulder, CO 80309-0345, , Phone: 303-492-7034, Fax: 303-492-2967
| | - Linda R Watkins
- University of Colorado Boulder, Department of Psychology and Neuroscience, Center for Neuroscience, Boulder, CO, USA.
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29
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Hu HZ, Granger N, Jeffery ND. Pathophysiology, Clinical Importance, and Management of Neurogenic Lower Urinary Tract Dysfunction Caused by Suprasacral Spinal Cord Injury. J Vet Intern Med 2016; 30:1575-1588. [PMID: 27527382 PMCID: PMC5032886 DOI: 10.1111/jvim.14557] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2016] [Revised: 06/30/2016] [Accepted: 07/06/2016] [Indexed: 12/24/2022] Open
Abstract
Management of persistent lower urinary tract dysfunction resulting from severe thoracolumbar spinal cord injury can be challenging. Severe suprasacral spinal cord injury releases the spinal cord segmental micturition reflex from supraspinal modulation and increases nerve growth factor concentration in the bladder wall, lumbosacral spinal cord, and dorsal root ganglion, which subsequently activates hypermechanosensitive C-fiber bladder wall afferents. Hyperexcitability of bladder afferents and detrusor overactivity can cause urine leaking during the storage phase. During urine voiding, the loss of supraspinal control that normally coordinates detrusor contraction with sphincter relaxation can lead to spinal cord segmental reflex-mediated simultaneous detrusor and sphincter contractions or detrusor-sphincter dyssynergia, resulting in inefficient urine voiding and high residual volume. These disease-associated changes can impact on the quality of life and life expectancy of spinal-injured animals. Here, we discuss the pathophysiology and management considerations of lower urinary tract dysfunction as the result of severe, acute, suprasacral spinal cord injury. In addition, drawing from experimental, preclinical, and clinical medicine, we introduce some treatment options for neurogenic lower urinary tract dysfunction that are designed to: (1) prevent urine leakage arising because of detrusor overactivity during bladder filling, (2) preserve upper urinary tract integrity and function by reducing intravesical pressure and subsequent vesicoureteral reflux, and (3) prevent urinary tract and systemic complications by treating and preventing urinary tract infections.
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Affiliation(s)
- H Z Hu
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA
| | - N Granger
- School of Veterinary Sciences, University of Bristol, Langford House, Langford, North Somerset, UK
| | - N D Jeffery
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA.
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30
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Regioselectively controlled synthesis of 3(5)-(trifluoromethyl)pyrazolylbenzenesulfonamides and their effects on a pathological pain model in mice. Eur J Med Chem 2015; 102:143-52. [DOI: 10.1016/j.ejmech.2015.07.036] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2015] [Revised: 07/17/2015] [Accepted: 07/18/2015] [Indexed: 11/20/2022]
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31
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Giron SE, Griffis CA, Burkard JF. Chronic Pain and Decreased Opioid Efficacy: An Inflammatory Link. Pain Manag Nurs 2015; 16:819-31. [PMID: 25962543 DOI: 10.1016/j.pmn.2015.04.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2015] [Revised: 03/16/2015] [Accepted: 04/02/2015] [Indexed: 01/08/2023]
Abstract
Chronic pain is a devastating amalgam of symptoms that affects millions of Americans at tremendous cost to our healthcare system and, more importantly, to patients' quality of life. Literature and research demonstrate that neuroimmune cells called glia are not only responsible for initiating and maintaining part of the chronic pain disease process, but also release inflammatory molecules responsible for decreasing the efficacy of one of the most prominent treatments for pain, opioid analgesia. This article describes chronic pain as a disease process that has ineffective treatment modalities, explores the mechanisms of glial cell activation and inflammatory responses that lead to chronic pain and decreased opioid treatment efficacy, and hypothesizes novel chronic pain treatment modalities based on the glial cell inactivation and anti-inflammatory pathways.
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Affiliation(s)
- Sarah E Giron
- Department of Anesthesiology, University of Southern California Keck School of Medicine, Los Angeles, California.
| | - Charles A Griffis
- Department of Anesthesiology, University of California at Los Angeles David Geffen School of Medicine, Los Angeles, California
| | - Joseph F Burkard
- University of San Diego Hahn School of Nursing and Health Science, San Diego, California
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Lemmens S, Brône B, Dooley D, Hendrix S, Geurts N. Alpha-adrenoceptor modulation in central nervous system trauma: pain, spasms, and paralysis--an unlucky triad. Med Res Rev 2014; 35:653-77. [PMID: 25546087 DOI: 10.1002/med.21337] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Many researchers have attempted to pharmacologically modulate the adrenergic system to control locomotion, pain, and spasms after central nervous system (CNS) trauma, although such efforts have led to conflicting results. Despite this, multiple studies highlight that α-adrenoceptors (α-ARs) are promising therapeutic targets because in the CNS, they are involved in reactivity to stressors and regulation of locomotion, pain, and spasms. These functions can be activated by direct modulation of these receptors on neuronal networks in the brain and the spinal cord. In addition, these multifunctional receptors are also broadly expressed on immune cells. This suggests that they might play a key role in modulating immunological responses, which may be crucial in treating spinal cord injury and traumatic brain injury as both diseases are characterized by a strong inflammatory component. Reducing the proinflammatory response will create a more permissive environment for axon regeneration and may support neuromodulation in combination therapies. However, pharmacological interventions are hindered by adrenergic system complexity and the even more complicated anatomical and physiological changes in the CNS after trauma. This review is the first concise overview of the pros and cons of α-AR modulation in the context of CNS trauma.
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Affiliation(s)
- Stefanie Lemmens
- Department of Morphology, Biomedical Research Institute, Hasselt University, Diepenbeek, Belgium
| | - Bert Brône
- Department of Physiology, Biomedical Research Institute, Hasselt University, Diepenbeek, Belgium
| | - Dearbhaile Dooley
- Department of Morphology, Biomedical Research Institute, Hasselt University, Diepenbeek, Belgium
| | - Sven Hendrix
- Department of Morphology, Biomedical Research Institute, Hasselt University, Diepenbeek, Belgium
| | - Nathalie Geurts
- Department of Morphology, Biomedical Research Institute, Hasselt University, Diepenbeek, Belgium
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Oliveira SM, Silva CR, Wentz AP, Paim GR, Correa MS, Bonacorso HG, Prudente AS, Otuki MF, Ferreira J. Antinociceptive effect of 3-(4-fluorophenyl)-5-trifluoromethyl-1H-1-tosylpyrazole. A Celecoxib structural analog in models of pathological pain. Pharmacol Biochem Behav 2014; 124:396-404. [DOI: 10.1016/j.pbb.2014.07.005] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/24/2014] [Revised: 06/11/2014] [Accepted: 07/06/2014] [Indexed: 01/27/2023]
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Woller SA, Malik JS, Aceves M, Hook MA. Morphine self-administration following spinal cord injury. J Neurotrauma 2014; 31:1570-83. [PMID: 24827476 DOI: 10.1089/neu.2013.3293] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Neuropathic pain develops in up to two-thirds of people following spinal cord injury (SCI). Opioids are among the most effective treatments for this pain and are commonly prescribed. There is concern surrounding the use of these analgesics, however, because use is often associated with the development of addiction. Previous data suggests that this concern may not be relevant in the presence of neuropathic pain. Yet, despite the common prescription of opioids for the treatment of SCI-related pain, there has been only one previous study examining the addictive potential of morphine following spinal injury. To address this, the present study used a self-administration paradigm to examine the addictive potential of morphine in a rodent model of SCI. Animals were placed into self-administration chambers 24 h, 14 d, or 35 d following a moderate spinal contusion injury. They were placed into the chambers for seven 12-hour sessions with access to 1.5 mg morphine/lever depression (up to 30 mg/d). In the acute phase of SCI, contused animals self-administered significantly less morphine than their sham counterparts, as previously shown. However, contused animals showing signs of neuropathic pain did not self-administer less morphine than their sham counterparts when administration began 14 or 35 d after injury. Instead, these animals administered nearly the full amount of morphine available each session. This amount of morphine did not affect recovery of locomotor function but did cause significant weight loss. We suggest caution is warranted when prescribing opioids for the treatment of neuropathic pain resulting from SCI, as the addictive potential is not reduced in this model.
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Affiliation(s)
- Sarah A Woller
- 1 Texas A&M University Institute for Neuroscience , Texas A&M Health Science Center, Bryan, Texas
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