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Beckers P, Belo Do Nascimento I, Charlier M, Desmet N, Massie A, Hermans E. Implication of system x c- in neuroinflammation during the onset and maintenance of neuropathic pain. J Neuroinflammation 2024; 21:117. [PMID: 38715127 PMCID: PMC11077843 DOI: 10.1186/s12974-024-03112-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2024] [Accepted: 04/25/2024] [Indexed: 05/12/2024] Open
Abstract
BACKGROUND Despite the high prevalence of neuropathic pain, treating this neurological disease remains challenging, given the limited efficacy and numerous side effects associated with current therapies. The complexity in patient management is largely attributed to an incomplete understanding of the underlying pathological mechanisms. Central sensitization, that refers to the adaptation of the central nervous system to persistent inflammation and heightened excitatory transmission within pain pathways, stands as a significant contributor to persistent pain. Considering the role of the cystine/glutamate exchanger (also designated as system xc-) in modulating glutamate transmission and in supporting neuroinflammatory responses, we investigated the contribution of this exchanger in the development of neuropathic pain. METHODS We examined the implication of system xc- by evaluating changes in the expression/activity of this exchanger in the dorsal spinal cord of mice after unilateral partial sciatic nerve ligation. In this surgical model of neuropathic pain, we also examined the consequence of the genetic suppression of system xc- (using mice lacking the system xc- specific subunit xCT) or its pharmacological manipulation (using the pharmacological inhibitor sulfasalazine) on the pain-associated behavioral responses. Finally, we assessed the glial activation and the inflammatory response in the spinal cord by measuring mRNA and protein levels of GFAP and selected M1 and M2 microglial markers. RESULTS The sciatic nerve lesion was found to upregulate system xc- at the spinal level. The genetic deletion of xCT attenuated both the amplitude and the duration of the pain sensitization after nerve surgery, as evidenced by reduced responses to mechanical and thermal stimuli, and this was accompanied by reduced glial activation. Consistently, pharmacological inhibition of system xc- had an analgesic effect in lesioned mice. CONCLUSION Together, these observations provide evidence for a role of system xc- in the biochemical processes underlying central sensitization. We propose that the reduced hypersensitivity observed in the transgenic mice lacking xCT or in sulfasalazine-treated mice is mediated by a reduced gliosis in the lumbar spinal cord and/or a shift in microglial M1/M2 polarization towards an anti-inflammatory phenotype in the absence of system xc-. These findings suggest that drugs targeting system xc- could contribute to prevent or reduce neuropathic pain.
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Affiliation(s)
- Pauline Beckers
- Institute of Neuroscience, Group of Neuropharmacology, Université catholique de Louvain (UCLouvain), Avenue Hippocrate 53 (B1.53.01), Brussels, 1200, Belgium
| | - Inês Belo Do Nascimento
- Institute of Neuroscience, Group of Neuropharmacology, Université catholique de Louvain (UCLouvain), Avenue Hippocrate 53 (B1.53.01), Brussels, 1200, Belgium
| | - Mathilde Charlier
- Institute of Neuroscience, Group of Neuropharmacology, Université catholique de Louvain (UCLouvain), Avenue Hippocrate 53 (B1.53.01), Brussels, 1200, Belgium
| | - Nathalie Desmet
- Institute of Neuroscience, Group of Neuropharmacology, Université catholique de Louvain (UCLouvain), Avenue Hippocrate 53 (B1.53.01), Brussels, 1200, Belgium
| | - Ann Massie
- Neuro-Aging & Viro-Immunotherapy, Center for Neurosciences, Vrije Universiteit Brussel (VUB), Laarbeeklaan 103, Brussels, 1090, Belgium
| | - Emmanuel Hermans
- Institute of Neuroscience, Group of Neuropharmacology, Université catholique de Louvain (UCLouvain), Avenue Hippocrate 53 (B1.53.01), Brussels, 1200, Belgium.
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Drinovac Vlah V, Bach-Rojecky L. Mirror-Image Pain Update: Complex Interactions Between Central and Peripheral Mechanisms. Mol Neurobiol 2024:10.1007/s12035-024-04102-x. [PMID: 38602655 DOI: 10.1007/s12035-024-04102-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Accepted: 03/06/2024] [Indexed: 04/12/2024]
Abstract
The appearance of contralateral effects after unilateral injury has been shown in various experimental pain models, as well as in clinics. They consist of a diversity of phenomena in contralateral peripheral nerves, sensory ganglia, or spinal cord: from structural changes and altered gene or protein expression to functional consequences such as the development of mirror-image pain (MP). Although MP is a well-documented phenomenon, the exact molecular mechanism underlying the induction and maintenance of mirror-like spread of pain is still an unresolved challenge. MP has generally been explained by central sensitization mechanisms leading to facilitation of pain impulse transfer through neural connections between the two sides of the central nervous system. On the contrary, the peripheral nervous system (PNS) was usually regarded unlikely to evoke such a symmetrical phenomenon. However, recent findings provided evidence that events in the PNS could play a significant role in MP induction. This manuscript provides an updated and comprehensive synthesis of the MP phenomenon and summarizes the available data on the mechanisms. A more detailed focus is placed on reported evidence for peripheral mechanisms behind the MP phenomenon, which were not reviewed up to now.
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Affiliation(s)
- Višnja Drinovac Vlah
- Department of Pharmacology, University of Zagreb Faculty of Pharmacy and Biochemistry, Domagojeva 2, 10000, Zagreb, Croatia
| | - Lidija Bach-Rojecky
- Department of Pharmacology, University of Zagreb Faculty of Pharmacy and Biochemistry, Domagojeva 2, 10000, Zagreb, Croatia.
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Goksu AY, Kocanci FG, Akinci E, Demir-Dora D, Erendor F, Sanlioglu S, Uysal H. Microglia cells treated with synthetic vasoactive intestinal peptide or transduced with LentiVIP protect neuronal cells against degeneration. Eur J Neurosci 2024; 59:1993-2015. [PMID: 38382910 DOI: 10.1111/ejn.16273] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2023] [Revised: 01/11/2024] [Accepted: 01/18/2024] [Indexed: 02/23/2024]
Abstract
A common pathological hallmark of neurodegenerative disorders is neuronal cell death, accompanied by neuroinflammation and oxidative stress. The vasoactive intestinal peptide (VIP) is a pleiotropic peptide that combines neuroprotective and immunomodulatory actions. The gene therapy field shows long-term promise for treating a wide range of neurodegenerative diseases (ND). In this study, we aimed to investigate the in vitro efficacy of transduction of microglia using lentiviral gene therapy vectors encoding VIP (LentiVIP). Additionally, we tested the protective effects of the secretome derived from LentiVIP-infected "immortalized human" microglia HMC3 cells, and cells treated with Synthetic VIP (SynVIP), against toxin-induced neurodegeneration. First, LentiVIP, which stably expresses VIP, was generated and purified. VIP secretion in microglial conditioned media (MG CM) for LentiVIP-infected HMC3 microglia cells was confirmed. Microglia cells were activated with lipopolysaccharide, and groups were formed as follows: 1) Control, 2) SynVIP-treated, or 3) LentiVIP-transduced. These MG CM were applied on an in vitro neurodegenerative model formed by differentiated (d)-SH-SY5Y cells. Then, cell survival analysis and apoptotic nuclear staining, besides measurement of oxidative/inflammatory parameters in CM of cells were performed. Activated MG CM reduced survival rates of both control and toxin-applied (d)-SH-SY5Y cells, whereas LentiVIP-infected MG CM and SynVIP-treated ones exhibited better survival rates. These findings were supported by apoptotic nuclear evaluations of (d)-SH-SY5Y cells, alongside oxidative/inflammatory parameters in their CM. LentiVIP seems worthy of further studies for the treatment of ND because of the potential of gene therapy to treat diseases effectively with a single injection.
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Affiliation(s)
- Azize Yasemin Goksu
- Department of Histology and Embryology, Faculty of Medicine, Akdeniz University, Antalya, Turkey
- Department of Gene and Cell Therapy, Faculty of Medicine, Akdeniz University, Antalya, Turkey
| | - Fatma Gonca Kocanci
- Department of Medical Laboratory Techniques, Vocational High School of Health Services, Alanya Alaaddin Keykubat University, Alanya/Antalya, Turkey
| | - Ersin Akinci
- Brigham and Women's Hospital, Division of Genetics, Harvard Medical School, Boston, MA, USA
- Department of Biotechnology, Faculty of Agriculture, Akdeniz University, Antalya, Turkey
| | - Devrim Demir-Dora
- Department of Gene and Cell Therapy, Faculty of Medicine, Akdeniz University, Antalya, Turkey
- Department of Medical Pharmacology, Faculty of Medicine, Akdeniz University, Antalya, Turkey
| | - Fulya Erendor
- Department of Gene and Cell Therapy, Faculty of Medicine, Akdeniz University, Antalya, Turkey
- Department of Medical Biology and Genetics, Faculty of Medicine, Akdeniz University, Antalya, Turkey
| | - Salih Sanlioglu
- Department of Gene and Cell Therapy, Faculty of Medicine, Akdeniz University, Antalya, Turkey
| | - Hilmi Uysal
- Department of Neurology, Faculty of Medicine, Akdeniz University, Antalya, Turkey
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Li QY, Chen SX, Liu JY, Yao PW, Duan YW, Li YY, Zang Y. Neuroinflammation in the anterior cingulate cortex: the potential supraspinal mechanism underlying the mirror-image pain following motor fiber injury. J Neuroinflammation 2022; 19:162. [PMID: 35725625 PMCID: PMC9210588 DOI: 10.1186/s12974-022-02525-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2022] [Accepted: 06/06/2022] [Indexed: 11/10/2022] Open
Abstract
Background Peripheral nerve inflammation or lesion can affect contralateral healthy structures, and thus result in mirror-image pain. Supraspinal structures play important roles in the occurrence of mirror pain. The anterior cingulate cortex (ACC) is a first-order cortical region that responds to painful stimuli. In the present study, we systematically investigate and compare the neuroimmune changes in the bilateral ACC region using unilateral- (spared nerve injury, SNI) and mirror-(L5 ventral root transection, L5-VRT) pain models, aiming to explore the potential supraspinal neuroimmune mechanism underlying the mirror-image pain. Methods The up-and-down method with von Frey hairs was used to measure the mechanical allodynia. Viral injections for the designer receptors exclusively activated by designer drugs (DREADD) were used to modulate ACC glutamatergic neurons. Immunohistochemistry, immunofluorescence, western blotting, protein microarray were used to detect the regulation of inflammatory signaling. Results Increased expressions of tumor necrosis factor alpha (TNF-α), interleukin-6 (IL-6) and chemokine CX3CL1 in ACC induced by unilateral nerve injury were observed on the contralateral side in the SNI group but on the bilateral side in the L5-VRT group, representing a stronger immune response to L5-VRT surgery. In remote ACC, both SNI and L5-VRT induced robust bilateral increase in the protein level of Nav1.6 (SCN8A), a major voltage-gated sodium channel (VGSC) that regulates neuronal activity in the mammalian nervous system. However, the L5-VRT-induced Nav1.6 response occurred at PO 3d, earlier than the SNI-induced one, 7 days after surgery. Modulating ACC glutamatergic neurons via DREADD-Gq or DREADD-Gi greatly changed the ACC CX3CL1 levels and the mechanical paw withdrawal threshold. Neutralization of endogenous ACC CX3CL1 by contralateral anti-CX3CL1 antibody attenuated the induction and the maintenance of mechanical allodynia and eliminated the upregulation of CX3CL1, TNF-α and Nav1.6 protein levels in ACC induced by SNI. Furthermore, contralateral ACC anti-CX3CL1 also inhibited the expression of ipsilateral spinal c-Fos, Iba1, CD11b, TNF-α and IL-6. Conclusions The descending facilitation function mediated by CX3CL1 and its downstream cascade may play a pivotal role, leading to enhanced pain sensitization and even mirror-image pain. Strategies that target chemokine-mediated ACC hyperexcitability may lead to novel therapies for the treatment of neuropathic pain. Supplementary Information The online version contains supplementary material available at 10.1186/s12974-022-02525-8.
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Affiliation(s)
- Qiao-Yun Li
- Pain Research Center and Department of Physiology, Zhongshan Medical School of Sun Yat-Sen University, Guangdong Provincial Key Laboratory of Brain Function and Disease, 74 Zhongshan Rd. 2, Guangzhou, 510080, People's Republic of China
| | - Shao-Xia Chen
- Department of Anesthesiology, Sun Yat-Sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, 651 Dongfeng Road East, Guangzhou, 510060, People's Republic of China
| | - Jin-Yu Liu
- Pain Research Center and Department of Physiology, Zhongshan Medical School of Sun Yat-Sen University, Guangdong Provincial Key Laboratory of Brain Function and Disease, 74 Zhongshan Rd. 2, Guangzhou, 510080, People's Republic of China
| | - Pei-Wen Yao
- Pain Research Center and Department of Physiology, Zhongshan Medical School of Sun Yat-Sen University, Guangdong Provincial Key Laboratory of Brain Function and Disease, 74 Zhongshan Rd. 2, Guangzhou, 510080, People's Republic of China
| | - Yi-Wen Duan
- Pain Research Center and Department of Physiology, Zhongshan Medical School of Sun Yat-Sen University, Guangdong Provincial Key Laboratory of Brain Function and Disease, 74 Zhongshan Rd. 2, Guangzhou, 510080, People's Republic of China
| | - Yong-Yong Li
- Pain Research Center and Department of Physiology, Zhongshan Medical School of Sun Yat-Sen University, Guangdong Provincial Key Laboratory of Brain Function and Disease, 74 Zhongshan Rd. 2, Guangzhou, 510080, People's Republic of China
| | - Ying Zang
- Pain Research Center and Department of Physiology, Zhongshan Medical School of Sun Yat-Sen University, Guangdong Provincial Key Laboratory of Brain Function and Disease, 74 Zhongshan Rd. 2, Guangzhou, 510080, People's Republic of China.
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Kim D, Doty RL. Positive Long-Term Effects of Third Molar Extraction on Taste Function. Chem Senses 2021; 46:6308464. [PMID: 34161573 DOI: 10.1093/chemse/bjab032] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Taste and other neurosensory defects have been reported postoperatively in a number of patients who have undergone mandibular third molar extraction (TME). Although the taste deficits are generally believed to resolve within a year, the long-term effects of TME remain unknown. We retrospectively examined the whole-mouth taste function of 891 individuals who had received TMEs, on average, more than 2 decades earlier, and 364 individuals who had not undergone TME. All had been extensively tested for chemosensory function at the University of Pennsylvania Smell and Taste Center over the course of the last 20 years. The whole-mouth identification test incorporated 2 presentations each of 5 different concentrations of sucrose, sodium chloride, citric acid, and caffeine. Analyses of covariance (age = covariate) found those with histories of TME to exhibit better overall test scores for all 4 taste qualities than nonoperated controls. Such scores were not associated with the time since the TME. In both groups, women outperformed men and function declined with age. The basis of this phenomenon, which requires confirmation from prospective studies, is unknown, but could reflect sensitization of CN VII nerve afferents or the partial release of the tonic inhibition that CN VII exerts on CN IX via central nervous system processes.
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Affiliation(s)
- Dane Kim
- School of Dental Medicine, 240 S. 40th Street, Philadelphia, PA 19104, USA.,Smell and Taste Center, Department of Otorhinolaryngology: Head and Neck Surgery, Perelman School of Medicine, University of Pennsylvania, 3400 Spruce Street, Philadelphia, PA 19104, USA
| | - Richard L Doty
- Smell and Taste Center, Department of Otorhinolaryngology: Head and Neck Surgery, Perelman School of Medicine, University of Pennsylvania, 3400 Spruce Street, Philadelphia, PA 19104, USA
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Nociceptor-localized cGMP-dependent protein kinase I is a critical generator for central sensitization and neuropathic pain. Pain 2021; 162:135-151. [PMID: 32773598 DOI: 10.1097/j.pain.0000000000002013] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Patients with neuropathic pain often experience exaggerated pain and anxiety. Central sensitization has been linked with the maintenance of neuropathic pain and may become an autonomous pain generator. Conversely, emerging evidence accumulated that central sensitization is initiated and maintained by ongoing nociceptive primary afferent inputs. However, it remains elusive what mechanisms underlie this phenomenon and which peripheral candidate contributes to central sensitization that accounts for pain hypersensitivity and pain-related anxiety. Previous studies have implicated peripherally localized cGMP-dependent protein kinase I (PKG-I) in plasticity of nociceptors and spinal synaptic transmission as well as inflammatory hyperalgesia. However, whether peripheral PKG-I contributes to cortical plasticity and hence maintains nerve injury-induced pain hypersensitivity and anxiety is unknown. Here, we demonstrated significant upregulation of PKG-I in ipsilateral L3 dorsal root ganglia (DRG), no change in L4 DRG, and downregulation in L5 DRG upon spared nerve injury. Genetic ablation of PKG-I specifically in nociceptors or post-treatment with intervertebral foramen injection of PKG-I antagonist, KT5823, attenuated the development and maintenance of spared nerve injury-induced bilateral pain hypersensitivity and anxiety. Mechanistic analysis revealed that activation of PKG-I in nociceptors is responsible for synaptic potentiation in the anterior cingulate cortex upon peripheral neuropathy through presynaptic mechanisms involving brain-derived neurotropic factor signaling. Our results revealed that PKG-I expressed in nociceptors is a key determinant for cingulate synaptic plasticity after nerve injury, which contributes to the maintenance of pain hypersensitivity and anxiety. Thereby, this study presents a strong basis for opening up a novel therapeutic target, PKG-I, in nociceptors for treatment of comorbidity of neuropathic pain and anxiety with least side effects.
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Dietz C, Reinhold AK, Escolano-Lozano F, Mehling K, Forer L, Kress M, Üçeyler N, Sommer C, Dimova V, Birklein F, Rittner HL. Complex regional pain syndrome: role of contralateral sensitisation. Br J Anaesth 2021; 127:e1-e3. [PMID: 33941363 DOI: 10.1016/j.bja.2021.03.018] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2020] [Revised: 03/03/2021] [Accepted: 03/17/2021] [Indexed: 10/21/2022] Open
Affiliation(s)
- Christopher Dietz
- Centre for Interdisciplinary Pain Medicine, Department of Anaesthesiology, University Hospital of Würzburg, Würzburg, Germany
| | - Ann-Kristin Reinhold
- Centre for Interdisciplinary Pain Medicine, Department of Anaesthesiology, University Hospital of Würzburg, Würzburg, Germany
| | | | - Katharina Mehling
- Centre for Interdisciplinary Pain Medicine, Department of Anaesthesiology, University Hospital of Würzburg, Würzburg, Germany
| | - Lukas Forer
- Division of Genetic Epidemiology, Department of Medical Genetics, Molecular and Clinical Pharmacology, Medical University of Innsbruck, Innsbruck, Austria
| | - Michaela Kress
- Division of Physiology, Department of Physiology and Medical Physics, University of Innsbruck, Innsbruck, Austria
| | - Nurcan Üçeyler
- Department of Neurology, University Hospital of Würzburg, Würzburg, Germany
| | - Claudia Sommer
- Department of Neurology, University Hospital of Würzburg, Würzburg, Germany
| | - Violeta Dimova
- Department of Neurology, University Hospital of Mainz, Mainz, Germany
| | - Frank Birklein
- Department of Neurology, University Hospital of Mainz, Mainz, Germany
| | - Heike L Rittner
- Centre for Interdisciplinary Pain Medicine, Department of Anaesthesiology, University Hospital of Würzburg, Würzburg, Germany.
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González V, Pelissier T, Cazanga V, Hernández A, Constandil L. Magnesium Salt, a Simple Strategy to Improve Methadone Analgesia in Chronic Pain: An Isobolographic Preclinical Study in Neuropathic Mice. Front Pharmacol 2020; 11:566. [PMID: 32457607 PMCID: PMC7225258 DOI: 10.3389/fphar.2020.00566] [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: 11/19/2019] [Accepted: 04/14/2020] [Indexed: 11/13/2022] Open
Abstract
Analgesic efficacy of methadone in cancer and chronic non-cancer pains is greater than that of other opioids, probably because of its unique pharmacokinetics properties and also because it targets glutamatergic receptors in addition to µ-opioid receptors. However, methadone has drawbacks which are clearly related to dosing and treatment duration. The authors hypothesized that the antinociceptive efficacy of methadone could be synergistically potentiated by magnesium and copper salts in a preclinical mouse model of chronic pain, using the intraplantar formalin test as algesimetric tool. The spared nerve injury mice model was used to generate mononeuropathy. A low dose (0.25%) formalin was injected in the neuropathic limb in order to give rise only to Phase I response, resulting from direct activation by formalin of nociceptive primary afferents. Licking/biting of the formalin-injected limb was evaluated as nociceptive behavior during a 35-min observation period. Dose-response curves for intraperitoneal magnesium sulfate (10, 30, 100, and 300 mg/kg i.p.), copper sulfate (0.1, 0.3, 1, and 3 mg/kg i.p.) and methadone (0.1, 0.3, 1, and 3 mg/kg i.p.) allowed to combine them in equieffective doses and to determine their interaction by isobolographic analysis. Magnesium sulfate, copper sulfate and methadone dose-dependently decreased the nociceptive response evoked by formalin injection, the respective ED50 being 76.38, 1.18, and 0.50 mg/kg i.p. Isobolographic analysis showed a superadditive interaction for magnesium and methadone. Indeed, despite that both ED50 are obviously equieffective, the ED50 for the MgSO4/methadone combination contained less than one third of the methadone having the ED50 for methadone alone. For the CuSO4/methadone combination, the interaction was only additive. Extrapolated to clinical settings, the results suggest that magnesium salts might be used to improve synergistically the efficacy of methadone in neuropathy, which would allow to reduce the dose of methadone and its associated side effects.
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Affiliation(s)
- Valeria González
- Laboratory of Neurobiology, Department of Biology, Faculty of Chemistry and Biology, University of Santiago of Chile, Santiago, Chile
| | - Teresa Pelissier
- Laboratory of Neurobiology, Department of Biology, Faculty of Chemistry and Biology, University of Santiago of Chile, Santiago, Chile
| | - Victoria Cazanga
- Laboratory of Neurobiology, Department of Biology, Faculty of Chemistry and Biology, University of Santiago of Chile, Santiago, Chile
| | - Alejandro Hernández
- Laboratory of Neurobiology, Department of Biology, Faculty of Chemistry and Biology, University of Santiago of Chile, Santiago, Chile
| | - Luis Constandil
- Laboratory of Neurobiology, Department of Biology, Faculty of Chemistry and Biology, University of Santiago of Chile, Santiago, Chile.,Center for the Development of Nanoscience and Nanotechnology (CEDENNA), Santiago, Chile
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Acute hyperalgesia and delayed dry eye after corneal abrasion injury. Pain Rep 2018; 3:e664. [PMID: 30123857 PMCID: PMC6085140 DOI: 10.1097/pr9.0000000000000664] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Revised: 04/12/2018] [Accepted: 04/28/2018] [Indexed: 01/01/2023] Open
Abstract
Introduction: Corneal nerves mediate pain from the ocular surface, lacrimation, and blinking, all of which protect corneal surface homeostasis and help preserve vision. Because pain, lacrimation and blinking are rarely assessed at the same time, it is not known whether these responses and their underlying mechanisms have similar temporal dynamics after acute corneal injury. Methods: We examined changes in corneal nerve density, evoked and spontaneous pain, and ocular homeostasis in Sprague-Dawley male rats after a superficial epithelial injury with heptanol. We also measured changes in calcitonin gene-related peptide (CGRP), which has been implicated in both pain and epithelial repair. Results: Hyperalgesia was seen 24 hours after abrasion injury, while basal tear production was normal. One week after abrasion injury, pain responses had returned to baseline levels and dry eye symptoms emerged. There was no correlation between epithelial nerve density and pain responses. Expression of both ATF3 (a nerve injury marker) and CGRP increased in trigeminal ganglia 24 hours after injury when hyperalgesia was seen, and returned to normal one week later when pain behavior was normal. These molecular changes were absent in the contralateral ganglion, despite reductions in corneal epithelial nerve density in the uninjured eye. By contrast, CGRP was upregulated in peripheral corneal endings 1 week after injury, when dry eye symptoms emerged. Conclusion: Our results demonstrate dynamic trafficking of CGRP within trigeminal sensory nerves following corneal injury, with elevations in the ganglion correlated with pain behaviors and elevations in peripheral endings correlated with dry eye symptoms.
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Young A, Kalladka M, Viswanath A, Zusman T, Khan J. Consomic rats parental strains differ in sensory perception, pain developed following nerve injury and in IL-1 beta and IL-6 levels. ACTA ACUST UNITED AC 2018; 25:137-141. [PMID: 29580677 DOI: 10.1016/j.pathophys.2018.03.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2018] [Revised: 03/12/2018] [Accepted: 03/18/2018] [Indexed: 11/26/2022]
Affiliation(s)
- Andrew Young
- Orofacial Disorders Clinic, Department of Diagnostic Sciences, Arthur A. Dugoni School of Dentistry, University of the Pacific, 155 Fifth Street, San Francisco, CA, 94103, USA.
| | - Mythili Kalladka
- Orofacial Pain and TMJ Disorders, Eastman Institute for Oral Health, 625 Elmwood Ave, Rochester, NY, 14620, USA.
| | - Archana Viswanath
- Department of Oral and Maxillofacial Surgery, Tufts University School of Dental Medicine, USA.
| | - Tal Zusman
- Graduate School of Biomedical Sciences, Rutgers University, Newark, NJ, USA.
| | - Junad Khan
- Orofacial Pain and TMJ Disorders, Eastman Institute for Oral Health, 625 Elmwood Ave, Rochester, NY, 14620, USA.
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Sanchez JJ, Noor S, Davies S, Savage D, Milligan ED. Prenatal alcohol exposure is a risk factor for adult neuropathic pain via aberrant neuroimmune function. J Neuroinflammation 2017; 14:254. [PMID: 29258553 PMCID: PMC5738192 DOI: 10.1186/s12974-017-1030-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Accepted: 12/08/2017] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND Clinical studies show that prenatal alcohol exposure (PAE) results in effects that persist into adulthood. Experimental animal models of moderate PAE demonstrate that young adults with PAE display potentiated sensitivity to light touch, clinically termed allodynia, following sciatic nerve chronic constriction injury (CCI) that coincides with heightened spinal glial, spinal macrophage, and peripheral immune responses. However, basal touch sensitivity and corresponding glial and leukocyte activation are unaltered. Therefore, the current study explored whether the enduring pathological consequences of moderate PAE on sensory processing are unmasked only following secondary neural insult. METHODS In middle-aged (1 year) Long Evans rats that underwent either prenatal saccharin exposure (control) or moderate PAE, we modified the well-characterized model of sciatic neuropathy, CCI, to study the effects of PAE on neuro-immune responses in adult offspring. Standard CCI manipulation required 4 chromic gut sutures, while a mild version applied a single suture loosely ligated around one sciatic nerve. Spinal glial immunoreactivity was examined using immunohistochemistry. The characterization and functional responses of leukocyte populations were studied using flow cytometry and cell stimulation assays followed by quantification of the proinflammatory cytokines interleukin-1beta (IL-1β) and tumor necrosis factor-alpha (TNF-α). Data were statistically analyzed by ANOVA and unpaired t tests. RESULTS The current report demonstrates that mild CCI generates robust allodynia only in PAE rats, while the pathological effects of PAE following the application of a standard CCI are revealed by enhanced allodynia and elevated spinal glial activation. Additionally, mild CCI increases spinal astrocyte activation but not microglia, suggesting astrocytes play a larger role in PAE-induced susceptibility to aberrant sensory processing. Leukocyte populations from PAE are altered under basal conditions (i.e., prior to secondary insult), as the distribution of leukocyte populations in lymphoid organs and other regions are different from those of controls. Lastly, following in vitro leukocyte stimulation, only PAE augments the immune response to antigen stimulation as assessed by heightened production of TNF-α and IL-1β. CONCLUSIONS These studies demonstrate PAE may prime spinal astrocytes and peripheral leukocytes that contribute to enduring susceptibility to adult-onset neuropathic pain that is not apparent until a secondary insult later in life.
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Affiliation(s)
- Joshua J. Sanchez
- Department of Neurosciences, School of Medicine, University of New Mexico Health Sciences Center, Albuquerque, NM 87131-0001 USA
| | - Shahani Noor
- Department of Neurosciences, School of Medicine, University of New Mexico Health Sciences Center, Albuquerque, NM 87131-0001 USA
| | - Suzy Davies
- Department of Neurosciences, School of Medicine, University of New Mexico Health Sciences Center, Albuquerque, NM 87131-0001 USA
| | - Daniel Savage
- Department of Neurosciences, School of Medicine, University of New Mexico Health Sciences Center, Albuquerque, NM 87131-0001 USA
| | - Erin D. Milligan
- Department of Neurosciences, School of Medicine, University of New Mexico Health Sciences Center, Albuquerque, NM 87131-0001 USA
- Department of Anesthesiology and Critical Care Medicine, University of New Mexico Health Sciences Center, MSC08 4740, Albuquerque, NM 87131-001 USA
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