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Vincenzi M, Milella MS, D’Ottavio G, Caprioli D, Reverte I, Maftei D. Targeting Chemokines and Chemokine GPCRs to Enhance Strong Opioid Efficacy in Neuropathic Pain. Life (Basel) 2022; 12:life12030398. [PMID: 35330149 PMCID: PMC8955776 DOI: 10.3390/life12030398] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Revised: 03/06/2022] [Accepted: 03/07/2022] [Indexed: 12/21/2022] Open
Abstract
Neuropathic pain (NP) originates from an injury or disease of the somatosensory nervous system. This heterogeneous origin and the possible association with other pathologies make the management of NP a real challenge. To date, there are no satisfactory treatments for this type of chronic pain. Even strong opioids, the gold-standard analgesics for nociceptive and cancer pain, display low efficacy and the paradoxical ability to exacerbate pain sensitivity in NP patients. Mounting evidence suggests that chemokine upregulation may be a common mechanism driving NP pathophysiology and chronic opioid use-related consequences (analgesic tolerance and hyperalgesia). Here, we first review preclinical studies on the role of chemokines and chemokine receptors in the development and maintenance of NP. Second, we examine the change in chemokine expression following chronic opioid use and the crosstalk between chemokine and opioid receptors. Then, we examine the effects of inhibiting specific chemokines or chemokine receptors as a strategy to increase opioid efficacy in NP. We conclude that strong opioids, along with drugs that block specific chemokine/chemokine receptor axis, might be the right compromise for a favorable risk/benefit ratio in NP management.
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Affiliation(s)
- Martina Vincenzi
- Department of Physiology and Pharmacology “Vittorio Erspamer”, Sapienza University of Rome, 00185 Rome, Italy;
- Correspondence: (M.V.); (I.R.)
| | - Michele Stanislaw Milella
- Toxicology and Poison Control Center Unit, Department of Emergency, Anesthesia and Critical Care, Policlinico Umberto I Hospital-Sapienza University of Rome, 00161 Rome, Italy;
| | - Ginevra D’Ottavio
- Santa Lucia Foundation (IRCCS Fondazione Santa Lucia), 00143 Rome, Italy; (G.D.); (D.C.)
- Laboratory Affiliated to Institute Pasteur Italia-Fondazione Cenci Bolognetti, Department of Physiology and Pharmacology “Vittorio Erspamer”, Sapienza University of Rome, 00185 Rome, Italy
| | - Daniele Caprioli
- Santa Lucia Foundation (IRCCS Fondazione Santa Lucia), 00143 Rome, Italy; (G.D.); (D.C.)
- Laboratory Affiliated to Institute Pasteur Italia-Fondazione Cenci Bolognetti, Department of Physiology and Pharmacology “Vittorio Erspamer”, Sapienza University of Rome, 00185 Rome, Italy
| | - Ingrid Reverte
- Department of Physiology and Pharmacology “Vittorio Erspamer”, Sapienza University of Rome, 00185 Rome, Italy;
- Santa Lucia Foundation (IRCCS Fondazione Santa Lucia), 00143 Rome, Italy; (G.D.); (D.C.)
- Correspondence: (M.V.); (I.R.)
| | - Daniela Maftei
- Department of Physiology and Pharmacology “Vittorio Erspamer”, Sapienza University of Rome, 00185 Rome, Italy;
- Santa Lucia Foundation (IRCCS Fondazione Santa Lucia), 00143 Rome, Italy; (G.D.); (D.C.)
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Srikanth M, Chew WS, Hind T, Lim SM, Hay NWJ, Lee JHM, Rivera R, Chun J, Ong WY, Herr DR. Lysophosphatidic acid and its receptor LPA1 mediate carrageenan induced inflammatory pain in mice. Eur J Pharmacol 2018; 841:49-56. [DOI: 10.1016/j.ejphar.2018.10.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Revised: 09/28/2018] [Accepted: 10/09/2018] [Indexed: 10/28/2022]
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Galán-Arriero I, Serrano-Muñoz D, Gómez-Soriano J, Goicoechea C, Taylor J, Velasco A, Ávila-Martín G. The role of Omega-3 and Omega-9 fatty acids for the treatment of neuropathic pain after neurotrauma. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2017; 1859:1629-1635. [PMID: 28495596 DOI: 10.1016/j.bbamem.2017.05.003] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Revised: 05/02/2017] [Accepted: 05/04/2017] [Indexed: 12/22/2022]
Abstract
Omega-3 polyunsaturated fatty acids (PUFAs), such as docosaexaenoic acid (DHA) and eicosapentaenoic acid (EPA), mediate neuroactive effects in experimental models of traumatic peripheral nerve and spinal cord injury. Cellular mechanisms of PUFAs include reduced neuroinflammation and oxidative stress, enhanced neurotrophic support, and activation of cell survival pathways. Bioactive Omega-9 monounsaturated fatty acids, such as oleic acid (OA) and 2-hydroxy oleic acid (2-OHOA), also show therapeutic effects in neurotrauma models. These FAs reduces noxious hyperreflexia and pain-related anxiety behavior following peripheral nerve injury and improves sensorimotor function following spinal cord injury (SCI), including facilitation of descending inhibitory antinociception. The relative safe profile of neuroactive fatty acids (FAs) holds promise for the future clinical development of these molecules as analgesic agents. This article is part of a Special Issue entitled: Membrane Lipid Therapy: Drugs Targeting Biomembranes edited by Pablo V. Escribá.
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Affiliation(s)
- Iriana Galán-Arriero
- Sensorimotor Function Group, Hospital Nacional de Parapléjicos, SESCAM, 45071 Toledo, Spain.
| | - Diego Serrano-Muñoz
- Sensorimotor Function Group, Hospital Nacional de Parapléjicos, SESCAM, 45071 Toledo, Spain.
| | - Julio Gómez-Soriano
- GIFTO, Nursing and Physiotherapy Faculty, Universidad de Castilla la Mancha, 45072 Toledo, Spain.
| | - Carlos Goicoechea
- Pharmacology and Nutrition Department, Health Sciences Faculty, Universidad Rey Juan Carlos, 28922 Alcorcón, Madrid, Spain.
| | - Julian Taylor
- Sensorimotor Function Group, Hospital Nacional de Parapléjicos, SESCAM, 45071 Toledo, Spain; Stoke Mandeville Spinal Research, National Spinal Injuries Centre, Buckinghamshire Healthcare NHS Trust, HP21 8AL Aylesbury, UK; Harris Manchester College, OX1 3TD University of Oxford, UK.
| | - Ana Velasco
- Instituto de Neurociencias de Castilla y León, 37007 Salamanca, Spain.
| | - Gerardo Ávila-Martín
- Sensorimotor Function Group, Hospital Nacional de Parapléjicos, SESCAM, 45071 Toledo, Spain.
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Avila-Martin G, Galan-Arriero I, Ferrer-Donato A, Busquets X, Gomez-Soriano J, Escribá PV, Taylor J. Oral 2-hydroxyoleic acid inhibits reflex hypersensitivity and open-field-induced anxiety after spared nerve injury. Eur J Pain 2014; 19:111-22. [PMID: 24824524 DOI: 10.1002/ejp.528] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/06/2014] [Indexed: 12/19/2022]
Abstract
BACKGROUND Recently, fatty acids have been shown to modulate sensory function in animal models of neuropathic pain. In this study, the antinociceptive effect of 2-hydroxyoleic acid (2-OHOA) was assessed following spared nerve injury (SNI) with reflex and cerebrally mediated behavioural responses. METHODS Initial antinociceptive behavioural screening of daily administration of 2-OHOA (400 mg/kg, p.o.) was assessed in Wistar rats by measuring hindlimb reflex hypersensitivity to von Frey and thermal plate stimulation up to 7 days after SNI, while its modulatory effect on lumbar spinal dorsal horn microglia reactivity was assessed with OX-42 immunohistochemistry. In vitro the effect of 2-OHOA (120 μM) on cyclooxygenase protein expression (COX-2/COX-1 ratio) in lipopolysaccharide-activated macrophage cells was tested with Western blot analysis. Finally, the effects of 2-OHOA treatment on the place escape aversion paradigm (PEAP) and the open-field-induced anxiety test were tested at 21 days following nerve injury compared with vehicle-treated sham and pregabalin-SNI (30 mg/kg, p.o.) control groups. RESULTS Oral 2-OHOA significantly reduced ipsilateral mechanical and thermal hypersensitivity up to 7 days after SNI. Additionally 2-OHOA decreased the COX-2/COX-1 ratio in lipopolysaccharide-activated macrophage cells and OX-42 expression within the ipsilateral lumbar spinal dorsal horn 7 days after SNI. 2-OHOA significantly restored inner-zone exploration in the open-field test compared with the vehicle-treated sham group at 21 days after SNI. CONCLUSIONS Oral administration of the modified omega 9 fatty acid, 2-OHOA, mediates antinociception and prevents open-field-induced anxiety in the SNI model in Wistar rats, which is mediated by an inhibition of spinal dorsal horn microglia activation.
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Affiliation(s)
- G Avila-Martin
- Sensorimotor Function Group, SESCAM, Hospital Nacional de Parapléjicos, Toledo, Spain
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Castilla-Ortega E, Escuredo L, Bilbao A, Pedraza C, Orio L, Estivill-Torrús G, Santín LJ, de Fonseca FR, Pavón FJ. 1-Oleoyl lysophosphatidic acid: a new mediator of emotional behavior in rats. PLoS One 2014; 9:e85348. [PMID: 24409327 PMCID: PMC3883702 DOI: 10.1371/journal.pone.0085348] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2013] [Accepted: 12/04/2013] [Indexed: 11/18/2022] Open
Abstract
The role of lysophosphatidic acid (LPA) in the control of emotional behavior remains to be determined. We analyzed the effects of the central administration of 1-oleoyl-LPA (LPA 18∶1) in rats tested for food consumption and anxiety-like and depression-like behaviors. For this purpose, the elevated plus-maze, open field, Y maze, forced swimming and food intake tests were performed. In addition, c-Fos expression in the dorsal periaqueductal gray matter (DPAG) was also determined. The results revealed that the administration of LPA 18∶1 reduced the time in the open arms of the elevated plus-maze and induced hypolocomotion in the open field, suggesting an anxiogenic-like phenotype. Interestingly, these effects were present following LPA 18∶1 infusion under conditions of novelty but not under habituation conditions. In the forced swimming test, the administration of LPA 18∶1 dose-dependently increased depression-like behavior, as evaluated according to immobility time. LPA treatment induced no effects on feeding. However, the immunohistochemical analysis revealed that LPA 18∶1 increased c-Fos expression in the DPAG. The abundant expression of the LPA1 receptor, one of the main targets for LPA 18∶1, was detected in this brain area, which participates in the control of emotional behavior, using immunocytochemistry. These findings indicate that LPA is a relevant transmitter potentially involved in normal and pathological emotional responses, including anxiety and depression.
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Affiliation(s)
- Estela Castilla-Ortega
- Unidad de Gestión Clínica de Salud Mental, Hospital Regional Universitario de Málaga, Instituto de Investigación Biomédica de Málaga (IBIMA), Málaga, Spain
- Departamento de Psicobiología y Metodología de las Ciencias del Comportamiento, Universidad de Málaga, Instituto de Investigación Biomédica de Málaga (IBIMA), Málaga, Spain
| | - Leticia Escuredo
- Departamento de Psicobiología, Universidad Complutense de Madrid, Madrid, Spain
| | - Ainhoa Bilbao
- Unidad de Gestión Clínica de Salud Mental, Hospital Regional Universitario de Málaga, Instituto de Investigación Biomédica de Málaga (IBIMA), Málaga, Spain
| | - Carmen Pedraza
- Departamento de Psicobiología y Metodología de las Ciencias del Comportamiento, Universidad de Málaga, Instituto de Investigación Biomédica de Málaga (IBIMA), Málaga, Spain
| | - Laura Orio
- Unidad de Gestión Clínica de Salud Mental, Hospital Regional Universitario de Málaga, Instituto de Investigación Biomédica de Málaga (IBIMA), Málaga, Spain
- Departamento de Psicobiología, Universidad Complutense de Madrid, Madrid, Spain
| | - Guillermo Estivill-Torrús
- Unidad de Gestión Clínica de Neurociencias, Hospital Regional Universitario de Málaga, Instituto de Investigación Biomédica de Málaga (IBIMA), Málaga, Spain
| | - Luis J. Santín
- Departamento de Psicobiología y Metodología de las Ciencias del Comportamiento, Universidad de Málaga, Instituto de Investigación Biomédica de Málaga (IBIMA), Málaga, Spain
- * E-mail: (LJS); (FRDF)
| | - Fernando Rodríguez de Fonseca
- Unidad de Gestión Clínica de Salud Mental, Hospital Regional Universitario de Málaga, Instituto de Investigación Biomédica de Málaga (IBIMA), Málaga, Spain
- Departamento de Psicobiología, Universidad Complutense de Madrid, Madrid, Spain
- * E-mail: (LJS); (FRDF)
| | - Francisco Javier Pavón
- Unidad de Gestión Clínica de Salud Mental, Hospital Regional Universitario de Málaga, Instituto de Investigación Biomédica de Málaga (IBIMA), Málaga, Spain
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Krzyzanowska A, Avendaño C. Behavioral testing in rodent models of orofacial neuropathic and inflammatory pain. Brain Behav 2012; 2:678-97. [PMID: 23139912 PMCID: PMC3489819 DOI: 10.1002/brb3.85] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/17/2012] [Revised: 07/10/2012] [Accepted: 07/13/2012] [Indexed: 11/12/2022] Open
Abstract
Orofacial pain conditions are often very debilitating to the patient and difficult to treat. While clinical interest is high, the proportion of studies performed in the orofacial region in laboratory animals is relatively low, compared with other body regions. This is partly due to difficulties in testing freely moving animals and therefore lack of reliable testing methods. Here we present a comprehensive review of the currently used rodent models of inflammatory and neuropathic pain adapted to the orofacial areas, taking into account the difficulties and drawbacks of the existing approaches. We examine the available testing methods and procedures used for assessing the behavioral responses in the face in both mice and rats and provide a summary of some pharmacological agents used in these paradigms to date. The use of these agents in animal models is also compared with outcomes observed in the clinic.
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Affiliation(s)
- Agnieszka Krzyzanowska
- Department of Anatomy, Histology and Neuroscience, Autonoma University of Madrid, Medical School Madrid, Spain
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Avila-Martin G, Galan-Arriero I, Gómez-Soriano J, Taylor J. Treatment of rat spinal cord injury with the neurotrophic factor albumin-oleic acid: translational application for paralysis, spasticity and pain. PLoS One 2011; 6:e26107. [PMID: 22046257 PMCID: PMC3202524 DOI: 10.1371/journal.pone.0026107] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2011] [Accepted: 09/19/2011] [Indexed: 01/11/2023] Open
Abstract
Sensorimotor dysfunction following incomplete spinal cord injury (iSCI) is often characterized by the debilitating symptoms of paralysis, spasticity and pain, which require treatment with novel pleiotropic pharmacological agents. Previous in vitro studies suggest that Albumin (Alb) and Oleic Acid (OA) may play a role together as an endogenous neurotrophic factor. Although Alb can promote basic recovery of motor function after iSCI, the therapeutic effect of OA or Alb-OA on a known translational measure of SCI associated with symptoms of spasticity and change in nociception has not been studied. Following T9 spinal contusion injury in Wistar rats, intrathecal treatment with: i) Saline, ii) Alb (0.4 nanomoles), iii) OA (80 nanomoles), iv) Alb-Elaidic acid (0.4/80 nanomoles), or v) Alb-OA (0.4/80 nanomoles) were evaluated on basic motor function, temporal summation of noxious reflex activity, and with a new test of descending modulation of spinal activity below the SCI up to one month after injury. Albumin, OA and Alb-OA treatment inhibited nociceptive Tibialis Anterior (TA) reflex activity. Moreover Alb-OA synergistically promoted early recovery of locomotor activity to 50 ± 10% of control and promoted de novo phasic descending inhibition of TA noxious reflex activity to 47 ± 5% following non-invasive electrical conditioning stimulation applied above the iSCI. Spinal L4-L5 immunohistochemistry demonstrated a unique increase in serotonin fibre innervation up to 4.2 ± 1.1 and 2.3 ± 0.3 fold within the dorsal and ventral horn respectively with Alb-OA treatment when compared to uninjured tissue, in addition to a reduction in NR1 NMDA receptor phosphorylation and microglia reactivity. Early recovery of voluntary motor function accompanied with tonic and de novo phasic descending inhibition of nociceptive TA flexor reflex activity following Alb-OA treatment, mediated via known endogenous spinal mechanisms of action, suggests a clinical application of this novel neurotrophic factor for the treatment of paralysis, spasticity and pain.
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Affiliation(s)
- Gerardo Avila-Martin
- Neurología Experimental, Hospital Nacional de Parapléjicos, Servicio de Salud de Castilla-La Mancha, Toledo, Castilla La-Mancha, Spain
| | - Iriana Galan-Arriero
- Neurología Experimental, Hospital Nacional de Parapléjicos, Servicio de Salud de Castilla-La Mancha, Toledo, Castilla La-Mancha, Spain
| | - Julio Gómez-Soriano
- Neurología Experimental, Hospital Nacional de Parapléjicos, Servicio de Salud de Castilla-La Mancha, Toledo, Castilla La-Mancha, Spain
- Escuela de Enfermería y Fisioterapia de Toledo, Universidad de Castilla La-Mancha, Toledo, Castilla-La Mancha, Spain
| | - Julian Taylor
- Neurología Experimental, Hospital Nacional de Parapléjicos, Servicio de Salud de Castilla-La Mancha, Toledo, Castilla La-Mancha, Spain
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Krzyzanowska A, Pittolo S, Cabrerizo M, Sánchez-López J, Krishnasamy S, Venero C, Avendaño C. Assessing nociceptive sensitivity in mouse models of inflammatory and neuropathic trigeminal pain. J Neurosci Methods 2011; 201:46-54. [PMID: 21782847 DOI: 10.1016/j.jneumeth.2011.07.006] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2011] [Revised: 07/01/2011] [Accepted: 07/08/2011] [Indexed: 12/31/2022]
Abstract
Chronic orofacial pain encompasses a range of debilitating conditions, however in contrast to other body regions, few animal models are available to investigate mechanisms and treatments in the trigeminal area. Particularly, there is a lack of reliable models and testing methods in mice. We have behaviourally tested C57BL/6 mice subjected to unilateral chronic constriction injury (CCI) of the infraorbital nerve (IoN) or unilateral injections of Complete Freunds Adjuvant (CFA) into the vibrissal pad region with the aid of von Frey filaments and air-puffs and the use of a newly designed restraining device. These models were validated by suppressing the pain responses with appropriate drugs. The IoN-CCI group showed significant hyperalgesia on the ipsilateral side in comparison to baseline values for up to 20 days post-CCI following von Frey and air-puff stimulation. Gabapentin (60mg/kg), but not saline, temporarily reversed the hyperalgesia. Animals that received a CFA injection showed hyperresponsivity to both von Frey and air-puff stimulation for up to 4 days post injection. These effects were transiently reversed with 3mg/kg i.p. morphine but not saline. Our study proposes a new restraining device for mice, and validates a behavioural testing procedure of several facial pain models in mice, allowing for reproducible and robust assessment of the effects of pain-related agents and treatments, or phenotyping of genetically modified animals.
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Affiliation(s)
- Agnieszka Krzyzanowska
- Department of Anatomy, Histology & Neuroscience, Autonoma University of Madrid, Medical School, 28029 Madrid, Spain.
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Poh KW, Yeo JF, Ong WY. MicroRNA changes in the mouse prefrontal cortex after inflammatory pain. Eur J Pain 2011; 15:801.e1-12. [PMID: 21397537 DOI: 10.1016/j.ejpain.2011.02.002] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2010] [Revised: 02/02/2011] [Accepted: 02/03/2011] [Indexed: 12/26/2022]
Abstract
Activation of the prefrontal cortex occurs during acute and chronic pain and models of experimental hyperalgesia. The present study was carried out to determine possible miRNA changes in the prefrontal cortex, after inflammatory pain induced by facial carrageenan injection in mice. miRNA microarray analyses showed significantly increased levels of miR-155 and miR-223 in the prefrontal cortex of carrageenan-injected mice. The changes were verified by real-time RT-PCR, and shown to occur bilaterally. The potential targets of the two miRNAs were predicted, and changes in two of the miRNA targets, c/ebp Beta and granulocyte colony-stimulating factor (GCSF) verified by real-time RT-PCR. Significantly downregulated c/ebp Beta but upregulated GCSF, accompanied by increased immunolabeling with an antibody to myeloperoxidase were found in the prefrontal cortex of facial carrageenan treated mice. It is postulated that this could lead to increased inflammation and activation of the prefrontal cortex. Further studies are necessary to determine if specific miRNAs could be useful as therapeutic molecules for pain.
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Affiliation(s)
- Kay-Wee Poh
- Department of Oral and Maxillofacial Surgery, National University of Singapore, Singapore 119260, Singapore
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Partial infraorbital nerve ligation as a model of trigeminal nerve injury in the mouse: behavioral, neural, and glial reactions. THE JOURNAL OF PAIN 2008; 9:1036-48. [PMID: 18708302 DOI: 10.1016/j.jpain.2008.06.006] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2008] [Revised: 06/05/2008] [Accepted: 06/09/2008] [Indexed: 01/03/2023]
Abstract
UNLABELLED Trigeminal nerve damage often leads to chronic pain syndromes including trigeminal neuralgia, a severely debilitating chronic orofacial pain syndrome. Options for treatment of neuropathic pain are limited in effectiveness and new approaches based on a better understanding of the underlying pathologies are required. Partial ligation has been shown to effectively mimic many of the qualities of human neuropathic pain syndromes. We have devised a mouse model of trigeminal neuralgia using a partial infraorbital nerve ligation (pIONL) that induces persistent pain behaviors and morphological changes in the brainstem. We found that the pIONL effectively induced mechanical allodynia lasting for more than 3 weeks. Cell proliferation (bromodeoxyuridine), activation of astrocytes and microglia in the ipsilateral caudal medulla, and persistent satellite cell reaction in the ipsilateral ganglion were observed. Neurochemical markers calcitonin gene-related peptide, substance P were decreased in medullary dorsal horn ipsilateral to the injury side, whereas substance P receptor NK1 expression was increased after 8 days. Nerve injury marker ATF3 was markedly increased in ipsilateral trigeminal ganglion neurons at 8 days after pIONL. The data indicate that partial trigeminal injury in mice produces many persistent anatomical changes in neuropathic pain, as well as mechanical allodynia. PERSPECTIVE This study describes the development of a new mouse model of trigeminal neuropathic pain. Our goal is to devise better treatments of trigeminal pain, and this will be facilitated by characterization of the underlying cellular and molecular neuropathological mechanisms in genetically designed mice.
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Fu Y, Wang H, Huff TB, Shi R, Cheng JX. Coherent anti-Stokes Raman scattering imaging of myelin degradation reveals a calcium-dependent pathway in lyso-PtdCho-induced demyelination. J Neurosci Res 2008; 85:2870-81. [PMID: 17551984 PMCID: PMC2277477 DOI: 10.1002/jnr.21403] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Coherent anti-Stokes Raman scattering (CARS) microscopy, which allows vibrational imaging of myelin sheath in its natural state, was applied to characterize lysophosphatidylcholine (lyso-PtdCho)-induced myelin degradation in tissues and in vivo. After the injection of lyso-PtdCho into ex vivo spinal tissues or in vivo mouse sciatic nerves, myelin swelling characterized by the decrease of CARS intensity and loss of excitation polarization dependence was extensively observed. The swelling corresponds to myelin vesiculation and splitting observed by electron microscopy. The demyelination dynamics were quantified by the increase of g ratio measured from the CARS images. Treating spinal tissues with Ca2+ ionophore A23187 resulted in the same kind of myelin degradation as lyso-PtdCho. Moreover, the demyelination lesion size was significantly reduced upon preincubation of the spinal tissue with Ca2+ free Krebs' solution or a cytosolic phospholipase A2 (cPLA(2)) inhibitor or a calpain inhibitor. In accordance with the imaging results, removal of Ca2+ or addition of cPLA(2) inhibitor or calpain inhibitor in the Krebs' solution remarkably increased the mean compound action potential amplitude in lyso-PtdCho treated spinal tissues. Our results suggest that lyso-PtdCho induces myelin degradation via Ca(2+) influx into myelin and subsequent activation of cPLA(2) and calpain, which break down the myelin lipids and proteins. The current work also shows that CARS microscopy is a potentially powerful tool for the study of demyelination.
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Affiliation(s)
- Yan Fu
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Indiana
| | - Haifeng Wang
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Indiana
| | - Terry B. Huff
- Department of Chemistry, Purdue University, West Lafayette, Indiana
| | - Riyi Shi
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Indiana
- Department of Basic Medical Sciences, Institute for Applied Neurology, and Center for Paralysis Research, Purdue University, West Lafayette, Indiana
| | - Ji-Xin Cheng
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Indiana
- Department of Chemistry, Purdue University, West Lafayette, Indiana
- *Correspondence to: Ji-Xin Cheng, Weldon School of Biomedical Engineering, Purdue University, 206 South Intramural Drive, West Lafayette, IN 47907. E-mail:
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