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Barut EN, Engin S, Yasar YK, Sezen SF. Riluzole, a neuroprotective agent, preserves erectile function following bilateral cavernous nerve injury in male rats. Int J Impot Res 2024; 36:275-282. [PMID: 36788353 DOI: 10.1038/s41443-023-00680-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Revised: 02/01/2023] [Accepted: 02/03/2023] [Indexed: 02/16/2023]
Abstract
Neurogenic erectile dysfunction is a highly prevalent complication in men undergoing radical prostatectomy. The underlying mechanisms remain incompletely defined and the effective therapy has been limited. This study aimed to evaluate the protective effect of riluzole and the role of PKC β and excitatory amino acid transporters (EAATs) mediating this effect in a rat model of bilateral cavernous injury (BCNI). A total of 48 male Sprague-Dawley rats were divided into sham, BCNI (at 7, 15 days post-injury) and BCNI treated with riluzole (8 mg/kg/day) groups. Erectile function was measured as maximum intracavernosal pressure (mICP)/mean arterial pressure (MAP) and total ICP/MAP. Changes in protein expressions of phospho (p)-PKC β IIser660 and EAATs were analysed in penis and major pelvic ganglion with western blotting. BCNI decreased erectile function at 7 and 15 days post-injury (mICP/MAP at 4 V: 0.45 ± 0.06 vs 0.84 ± 0.07; 0.34 ± 0.04 vs 0.77 ± 0.04 respectively; p < 0.001) whereas riluzole treatment (for 15 days) preserved erectile function (mICP/MAP at 4 V: 0.62 ± 0.03 vs 0.34 ± 0.04; p < 0.01). The decline in the expression of p-PKC β IIser660 was observed in penis at 7 and 15 days post-injury (p = 0.0003, p = 0.0033), which was prevented by riluzole treatment for 15 days (p = 0.0464). While expressions of EAAT-1 and EAAT-2 decreased in major pelvic ganglion following BCNI (p = 0.0428, p = 0.002), riluzole treatment for 15 days prevented the decrease only in EAAT-2 expression (p = 0.0456). Riluzole improved erectile function via possibly interacting with PKC β II and glutamatergic pathways, as a potential therapeutic candidate for erectile dysfunction.
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Affiliation(s)
- Elif Nur Barut
- Karadeniz Technical University, Faculty of Pharmacy, Department of Pharmacology, Trabzon, Türkiye.
| | - Seckin Engin
- Karadeniz Technical University, Faculty of Pharmacy, Department of Pharmacology, Trabzon, Türkiye
| | - Yesim Kaya Yasar
- Karadeniz Technical University, Faculty of Pharmacy, Department of Pharmacology, Trabzon, Türkiye
- Karadeniz Technical University, Drug and Pharmaceutical Technology Application and Research Center, Trabzon, Türkiye
| | - Sena F Sezen
- Karadeniz Technical University, Faculty of Pharmacy, Department of Pharmacology, Trabzon, Türkiye
- Karadeniz Technical University, Drug and Pharmaceutical Technology Application and Research Center, Trabzon, Türkiye
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Jang K, Garraway SM. A review of dorsal root ganglia and primary sensory neuron plasticity mediating inflammatory and chronic neuropathic pain. NEUROBIOLOGY OF PAIN (CAMBRIDGE, MASS.) 2024; 15:100151. [PMID: 38314104 PMCID: PMC10837099 DOI: 10.1016/j.ynpai.2024.100151] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/15/2023] [Revised: 01/04/2024] [Accepted: 01/19/2024] [Indexed: 02/06/2024]
Abstract
Pain is a sensory state resulting from complex integration of peripheral nociceptive inputs and central processing. Pain consists of adaptive pain that is acute and beneficial for healing and maladaptive pain that is often persistent and pathological. Pain is indeed heterogeneous, and can be expressed as nociceptive, inflammatory, or neuropathic in nature. Neuropathic pain is an example of maladaptive pain that occurs after spinal cord injury (SCI), which triggers a wide range of neural plasticity. The nociceptive processing that underlies pain hypersensitivity is well-studied in the spinal cord. However, recent investigations show maladaptive plasticity that leads to pain, including neuropathic pain after SCI, also exists at peripheral sites, such as the dorsal root ganglia (DRG), which contains the cell bodies of sensory neurons. This review discusses the important role DRGs play in nociceptive processing that underlies inflammatory and neuropathic pain. Specifically, it highlights nociceptor hyperexcitability as critical to increased pain states. Furthermore, it reviews prior literature on glutamate and glutamate receptors, voltage-gated sodium channels (VGSC), and brain-derived neurotrophic factor (BDNF) signaling in the DRG as important contributors to inflammatory and neuropathic pain. We previously reviewed BDNF's role as a bidirectional neuromodulator of spinal plasticity. Here, we shift focus to the periphery and discuss BDNF-TrkB expression on nociceptors, non-nociceptor sensory neurons, and non-neuronal cells in the periphery as a potential contributor to induction and persistence of pain after SCI. Overall, this review presents a comprehensive evaluation of large bodies of work that individually focus on pain, DRG, BDNF, and SCI, to understand their interaction in nociceptive processing.
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Affiliation(s)
- Kyeongran Jang
- Department of Cell Biology, Emory University, School of Medicine, Atlanta, GA, 30322, USA
| | - Sandra M. Garraway
- Department of Cell Biology, Emory University, School of Medicine, Atlanta, GA, 30322, USA
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Mazzone GL, Coronel MF, Mladinic M, Sámano C. An update to pain management after spinal cord injury: from pharmacology to circRNAs. Rev Neurosci 2023; 34:599-611. [PMID: 36351309 DOI: 10.1515/revneuro-2022-0089] [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: 07/22/2022] [Accepted: 10/19/2022] [Indexed: 08/04/2023]
Abstract
Neuropathic pain (NP) following a spinal cord injury (SCI) is often hard to control and therapies should be focused on the physical, psychological, behavioral, social, and environmental factors that may contribute to chronic sensory symptoms. Novel therapeutic treatments for NP management should be based on the combination of pharmacological and nonpharmacological options. Some of them are addressed in this review with a focus on mechanisms and novel treatments. Several reports demonstrated an aberrant expression of non-coding RNAs (ncRNAs) that may represent key regulatory factors with a crucial role in the pathophysiology of NP and as potential diagnostic biomarkers. This review analyses the latest evidence for cellular and molecular mechanisms associated with the role of circular RNAs (circRNAs) in the management of pain after SCI. Advantages in the use of circRNA are their stability (up to 48 h), and specificity as sponges of different miRNAs related to SCI and nerve injury. The present review discusses novel data about deregulated circRNAs (up or downregulated) that sponge miRNAs, and promote cellular and molecular interactions with mRNAs and proteins. This data support the concept that circRNAs could be considered as novel potential therapeutic targets for NP management especially after spinal cord injuries.
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Affiliation(s)
- Graciela L Mazzone
- Instituto de Investigaciones en Medicina Traslacional (IIMT), CONICET-Universidad Austral, Av. Pte. Perón 1500, B1629AHJ, Pilar, Buenos Aires, Argentina
| | - María F Coronel
- Instituto de Investigaciones en Medicina Traslacional (IIMT), CONICET-Universidad Austral, Av. Pte. Perón 1500, B1629AHJ, Pilar, Buenos Aires, Argentina
| | - Miranda Mladinic
- Laboratory for Molecular Neurobiology, Department of Biotechnology, University of Rijeka, 51000 Rijeka, Croatia
| | - Cynthia Sámano
- Departamento de Ciencias Naturales, Universidad Autónoma Metropolitana, Unidad Cuajimalpa. Avenida Vasco de Quiroga 4871, Col. Santa Fe Cuajimalpa. Alcaldía Cuajimalpa de Morelos, C.P. 05348, Ciudad de México, México
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Huang Y, Chen H, Jin D, Chen SR, Pan HL. NMDA Receptors at Primary Afferent-Excitatory Neuron Synapses Differentially Sustain Chemotherapy- and Nerve Trauma-Induced Chronic Pain. J Neurosci 2023; 43:3933-3948. [PMID: 37185237 PMCID: PMC10217996 DOI: 10.1523/jneurosci.0183-23.2023] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Revised: 03/30/2023] [Accepted: 04/14/2023] [Indexed: 05/17/2023] Open
Abstract
The spinal dorsal horn contains vesicular glutamate transporter-2 (VGluT2)-expressing excitatory neurons and vesicular GABA transporter (VGAT)-expressing inhibitory neurons, which normally have different roles in nociceptive transmission. Spinal glutamate NMDAR hyperactivity is a crucial mechanism of chronic neuropathic pain. However, it is unclear how NMDARs regulate primary afferent input to spinal excitatory and inhibitory neurons in neuropathic pain. Also, the functional significance of presynaptic NMDARs in neuropathic pain has not been defined explicitly. Here we showed that paclitaxel treatment or spared nerve injury (SNI) similarly increased the NMDAR-mediated mEPSC frequency and dorsal root-evoked EPSCs in VGluT2 dorsal horn neurons in male and female mice. By contrast, neither paclitaxel nor SNI had any effect on mEPSCs or evoked EPSCs in VGAT neurons. In mice with conditional Grin1 (gene encoding GluN1) KO in primary sensory neurons (Grin1-cKO), paclitaxel treatment failed to induce pain hypersensitivity. Unexpectedly, SNI still caused long-lasting pain hypersensitivity in Grin1-cKO mice. SNI increased the amplitude of puff NMDA currents in VGluT2 neurons and caused similar depolarizing shifts in GABA reversal potentials in WT and Grin1-cKO mice. Concordantly, spinal Grin1 knockdown diminished SNI-induced pain hypersensitivity. Thus, presynaptic NMDARs preferentially amplify primary afferent input to spinal excitatory neurons in neuropathic pain. Although presynaptic NMDARs are required for chemotherapy-induced pain hypersensitivity, postsynaptic NMDARs in spinal excitatory neurons play a dominant role in traumatic nerve injury-induced chronic pain. Our findings reveal the divergent synaptic connectivity and functional significance of spinal presynaptic and postsynaptic NMDARs in regulating cell type-specific nociceptive input in neuropathic pain with different etiologies.SIGNIFICANCE STATEMENT Spinal excitatory neurons relay input from nociceptors, whereas inhibitory neurons repress spinal nociceptive transmission. Chronic nerve pain is associated with aberrant NMDAR activity in the spinal dorsal horn. This study demonstrates, for the first time, that chemotherapy and traumatic nerve injury preferentially enhance the NMDAR activity at primary afferent-excitatory neuron synapses but have no effect on primary afferent input to spinal inhibitory neurons. NMDARs in primary sensory neurons are essential for chemotherapy-induced chronic pain, whereas nerve trauma causes pain hypersensitivity predominantly via postsynaptic NMDARs in spinal excitatory neurons. Thus, presynaptic and postsynaptic NMDARs at primary afferent-excitatory neuron synapses are differentially engaged in chemotherapy- and nerve injury-induced chronic pain and could be targeted respectively for treating these painful conditions.
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Affiliation(s)
- Yuying Huang
- Center for Neuroscience and Pain Research, Department of Anesthesiology and Perioperative Medicine, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030
| | - Hong Chen
- Center for Neuroscience and Pain Research, Department of Anesthesiology and Perioperative Medicine, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030
| | - Daozhong Jin
- Center for Neuroscience and Pain Research, Department of Anesthesiology and Perioperative Medicine, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030
| | - Shao-Rui Chen
- Center for Neuroscience and Pain Research, Department of Anesthesiology and Perioperative Medicine, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030
| | - Hui-Lin Pan
- Center for Neuroscience and Pain Research, Department of Anesthesiology and Perioperative Medicine, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030
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Temmermand R, Barrett JE, Fontana ACK. Glutamatergic systems in neuropathic pain and emerging non-opioid therapies. Pharmacol Res 2022; 185:106492. [PMID: 36228868 PMCID: PMC10413816 DOI: 10.1016/j.phrs.2022.106492] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/14/2022] [Revised: 10/05/2022] [Accepted: 10/06/2022] [Indexed: 01/14/2023]
Abstract
Neuropathic pain, a disease of the somatosensory nervous system, afflicts many individuals and adequate management with current pharmacotherapies remains elusive. The glutamatergic system of neurons, receptors and transporters are intimately involved in pain but, to date, there have been few drugs developed that therapeutically modulate this system. Glutamate transporters, or excitatory amino acid transporters (EAATs), remove excess glutamate around pain transmitting neurons to decrease nociception suggesting that the modulation of glutamate transporters may represent a novel approach to the treatment of pain. This review highlights and summarizes (1) the physiology of the glutamatergic system in neuropathic pain, (2) the preclinical evidence for dysregulation of glutamate transport in animal pain models, and (3) emerging novel therapies that modulate glutamate transporters. Successful drug discovery requires continuous focus on basic and translational methods to fully elucidate the etiologies of this disease to enable the development of targeted therapies. Increasing the efficacy of astrocytic EAATs may serve as a new way to successfully treat those suffering from this devastating disease.
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Affiliation(s)
- Rhea Temmermand
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, PA 19102, USA
| | - James E Barrett
- Center for Substance Abuse Research, Lewis Katz School of Medicine, Temple University, Philadelphia, PA 19140, USA
| | - Andréia C K Fontana
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, PA 19102, USA.
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7,8-Dihydroxyflavone accelerates recovery of Brown-Sequard syndrome in adult female rats with spinal cord lateral hemisection. Biomed Pharmacother 2022; 153:113397. [DOI: 10.1016/j.biopha.2022.113397] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2022] [Revised: 07/04/2022] [Accepted: 07/07/2022] [Indexed: 11/21/2022] Open
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Shen Z, Xiang M, Chen C, Ding F, Wang Y, Shang C, Xin L, Zhang Y, Cui X. Glutamate excitotoxicity: Potential therapeutic target for ischemic stroke. Biomed Pharmacother 2022; 151:113125. [PMID: 35609367 DOI: 10.1016/j.biopha.2022.113125] [Citation(s) in RCA: 50] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Revised: 05/01/2022] [Accepted: 05/13/2022] [Indexed: 11/29/2022] Open
Abstract
Glutamate-mediated excitotoxicity is an important mechanism leading to post ischemic stroke damage. After acute stroke, the sudden reduction in cerebral blood flow is most initially followed by ion transport protein dysfunction and disruption of ion homeostasis, which in turn leads to impaired glutamate release, reuptake, and excessive N-methyl-D-aspartate receptor (NMDAR) activation, promoting neuronal death. Despite extensive evidence from preclinical studies suggesting that excessive NMDAR stimulation during ischemic stroke is a central step in post-stroke damage, NMDAR blockers have failed to translate into clinical stroke treatment. Current treatment options for stroke are very limited, and there is therefore a great need to develop new targets for neuroprotective therapeutic agents in ischemic stroke to extend the therapeutic time window. In this review, we highlight recent findings on glutamate release, reuptake mechanisms, NMDAR and its downstream cellular signaling pathways in post-ischemic stroke damage, and review the pathological changes in each link to help develop viable new therapeutic targets. We then also summarize potential neuroprotective drugs and therapeutic approaches for these new targets in the treatment of ischemic stroke.
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Affiliation(s)
- Zihuan Shen
- Department of Cardiovascular, Guang'anmen Hospital, China Academy of Chinese Medical Sciences, Beijing 100053, China; Clinical Medical School, Beijing University of Traditional Chinese Medicine, Beijing 100029, China
| | - Mi Xiang
- Department of Cardiovascular, Guang'anmen Hospital, China Academy of Chinese Medical Sciences, Beijing 100053, China
| | - Chen Chen
- Department of Cardiovascular, Guang'anmen Hospital, China Academy of Chinese Medical Sciences, Beijing 100053, China
| | - Fan Ding
- Department of Cardiovascular, Guang'anmen Hospital, China Academy of Chinese Medical Sciences, Beijing 100053, China; Clinical Medical School, Beijing University of Traditional Chinese Medicine, Beijing 100029, China
| | - Yuling Wang
- Department of Cardiovascular, Guang'anmen Hospital, China Academy of Chinese Medical Sciences, Beijing 100053, China; Clinical Medical School, Beijing University of Traditional Chinese Medicine, Beijing 100029, China
| | - Chang Shang
- Department of Cardiovascular, Guang'anmen Hospital, China Academy of Chinese Medical Sciences, Beijing 100053, China; Clinical Medical School, Beijing University of Traditional Chinese Medicine, Beijing 100029, China
| | - Laiyun Xin
- Department of Cardiovascular, Guang'anmen Hospital, China Academy of Chinese Medical Sciences, Beijing 100053, China
| | - Yang Zhang
- Department of Cardiovascular, Guang'anmen Hospital, China Academy of Chinese Medical Sciences, Beijing 100053, China.
| | - Xiangning Cui
- Department of Cardiovascular, Guang'anmen Hospital, China Academy of Chinese Medical Sciences, Beijing 100053, China.
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Chen J, Li L, Chen SR, Chen H, Xie JD, Sirrieh RE, MacLean DM, Zhang Y, Zhou MH, Jayaraman V, Pan HL. The α2δ-1-NMDA Receptor Complex Is Critically Involved in Neuropathic Pain Development and Gabapentin Therapeutic Actions. Cell Rep 2019; 22:2307-2321. [PMID: 29490268 PMCID: PMC5873963 DOI: 10.1016/j.celrep.2018.02.021] [Citation(s) in RCA: 173] [Impact Index Per Article: 34.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Revised: 12/20/2017] [Accepted: 02/06/2018] [Indexed: 12/13/2022] Open
Abstract
α2δ-1, commonly known as a voltage-activated Ca2+ channel subunit, is a binding site of gabapentinoids used to treat neuropathic pain and epilepsy. However, it is unclear how α2δ-1 contributes to neuropathic pain and gabapentinoid actions. Here, we show that Cacna2d1 overexpression potentiates presynaptic and postsynaptic NMDAR activity of spinal dorsal horn neurons to cause pain hypersensitivity. Conversely, Cacna2d1 knockdown or ablation normalizes synaptic NMDAR activity increased by nerve injury. α2δ-1 forms a heteromeric complex with NMDARs in rodent and human spinal cords. The α2δ-1-NMDAR interaction predominantly occurs through the C terminus of α2δ-1 and promotes surface trafficking and synaptic targeting of NMDARs. Gabapentin or an α2δ-1 C terminus-interfering peptide normalizes NMDAR synaptic targeting and activity increased by nerve injury. Thus, α2δ-1 is an NMDAR-interacting protein that increases NMDAR synaptic delivery in neuropathic pain. Gabapentinoids reduce neuropathic pain by inhibiting forward trafficking of α2δ-1-NMDAR complexes.
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Affiliation(s)
- Jinjun Chen
- Center for Neuroscience and Pain Research, Department of Anesthesiology and Perioperative Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA; College of Bioscience and Biotechnology, Hunan Agricultural University, Changsha, Hunan 410128, China
| | - Lingyong Li
- Center for Neuroscience and Pain Research, Department of Anesthesiology and Perioperative Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Shao-Rui Chen
- Center for Neuroscience and Pain Research, Department of Anesthesiology and Perioperative Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Hong Chen
- Center for Neuroscience and Pain Research, Department of Anesthesiology and Perioperative Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Jing-Dun Xie
- Center for Neuroscience and Pain Research, Department of Anesthesiology and Perioperative Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA; Department of Anesthesiology, Sun Yat-Sen University Cancer Center, Guangzhou, Guangdong 510060, China
| | - Rita E Sirrieh
- Department of Biochemistry and Molecular Biology, The University of Texas Health Science Center, Houston, TX 77030, USA
| | - David M MacLean
- Department of Biochemistry and Molecular Biology, The University of Texas Health Science Center, Houston, TX 77030, USA
| | - Yuhao Zhang
- Center for Neuroscience and Pain Research, Department of Anesthesiology and Perioperative Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Meng-Hua Zhou
- Center for Neuroscience and Pain Research, Department of Anesthesiology and Perioperative Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Vasanthi Jayaraman
- Department of Biochemistry and Molecular Biology, The University of Texas Health Science Center, Houston, TX 77030, USA
| | - Hui-Lin Pan
- Center for Neuroscience and Pain Research, Department of Anesthesiology and Perioperative Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA.
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Gegelashvili G, Bjerrum OJ. Glutamate transport system as a key constituent of glutamosome: Molecular pathology and pharmacological modulation in chronic pain. Neuropharmacology 2019; 161:107623. [PMID: 31047920 DOI: 10.1016/j.neuropharm.2019.04.029] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Revised: 04/26/2019] [Accepted: 04/28/2019] [Indexed: 01/07/2023]
Abstract
Neural uptake of glutamate is executed by the structurally related members of the SLC1A family of solute transporters: GLAST/EAAT1, GLT-1/EAAT2, EAAC1/EAAT3, EAAT4, ASCT2. These plasma membrane proteins ensure supply of glutamate, aspartate and some neutral amino acids, including glutamine and cysteine, for synthetic, energetic and signaling purposes, whereas effective removal of glutamate from the synaptic cleft shapes excitatory neurotransmission and prevents glutamate toxicity. Glutamate transporters (GluTs) possess also receptor-like properties and can directly initiate signal transduction. GluTs are physically linked to other glutamate signaling-, transporting- and metabolizing molecules (e.g., glutamine transporters SNAT3 and ASCT2, glutamine synthetase, NMDA receptor, synaptic vesicles), as well as cellular machineries fueling the transmembrane transport of glutamate (e.g., ion gradient-generating Na/K-ATPase, glycolytic enzymes, mitochondrial membrane- and matrix proteins, glucose transporters). We designate this supramolecular functional assembly as 'glutamosome'. GluTs play important roles in the molecular pathology of chronic pain, due to the predominantly glutamatergic nature of nociceptive signaling in the spinal cord. Down-regulation of GluTs often precedes or occurs simultaneously with development of pain hypersensitivity. Pharmacological inhibition or gene knock-down of spinal GluTs can induce/aggravate pain, whereas enhancing expression of GluTs by viral gene transfer can mitigate chronic pain. Thus, functional up-regulation of GluTs is turning into a prospective pharmacotherapeutic approach for the management of chronic pain. A number of novel positive pharmacological regulators of GluTs, incl. pyridazine derivatives and β-lactams, have recently been introduced. However, design and development of new analgesics based on this principle will require more precise knowledge of molecular mechanisms underlying physiological or aberrant functioning of the glutamate transport system in nociceptive circuits. This article is part of the issue entitled 'Special Issue on Neurotransmitter Transporters'.
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Affiliation(s)
- Georgi Gegelashvili
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark; Institute of Chemical Biology, Ilia State University, Tbilisi, Georgia.
| | - Ole Jannik Bjerrum
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
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Chincholkar M. Analgesic mechanisms of gabapentinoids and effects in experimental pain models: a narrative review. Br J Anaesth 2018; 120:1315-1334. [DOI: 10.1016/j.bja.2018.02.066] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2016] [Revised: 02/07/2018] [Accepted: 03/14/2018] [Indexed: 12/17/2022] Open
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Genty J, Tetsi Nomigni M, Anton F, Hanesch U. Maternal separation stress leads to resilience against neuropathic pain in adulthood. Neurobiol Stress 2017; 8:21-32. [PMID: 29276736 PMCID: PMC5738238 DOI: 10.1016/j.ynstr.2017.11.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2017] [Revised: 11/03/2017] [Accepted: 11/21/2017] [Indexed: 12/24/2022] Open
Abstract
Early life stress (ELS) leads to a permanent reprogramming of biochemical stress response cascades that may also be relevant for the processing of chronic pain states such as neuropathy. Despite clinical evidence, little is known about ELS-related vulnerability for neuropathic pain and the possibly underlying etiology. In the framework of experimental studies aimed at investigating the respective relationships we used the established ELS model of maternal separation (MS). Rat dams and neonates were separated for 3 h/day from post-natal day 2–12. At adulthood, noxious mechanical and thermal thresholds were assessed before and during induction of neuropathic pain by chronic constriction injury (CCI). The potential involvement of spinal glutamatergic transmission, glial cells, pro-inflammatory cytokines and growth factors was studied by using qPCR. MS per se did not modify pain thresholds. But, when exposed to neuropathic pain, MS rats exhibited a marked reduction of thermal sensitivity and a delayed development of mechanical allodynia/hyperalgesia when compared to control animals. Also, MS did not alter glucocorticoid receptor mRNA levels, but prevented the CCI-induced down-regulation of NR1 and NR2 sub-units of the NMDA receptor and of the glutamate transporter EAAT3 as observed at 21 days post-surgery. Additionally, CCI-provoked up-regulation of glial cell markers was either prevented (GFAP for astrocytes) or dampened (Iba1 for microglia) by MS. Pro-inflammatory cytokine mRNA expression was either not affected (IL-6) or reduced (IL-1β) by MS shortly after CCI. The growth factors GDNF and NGF were only slightly downregulated 4 days after CCI in the MS-treated animals. The changes in glutamatergic signaling, astroglial and cytokine activation as well as neurotrophin expression could, to some extent, explain these changes in pain behavior. Taken together, the results obtained in the described experimental conditions support the mismatch theory of chronic stress where an early life stress, rather than predisposing individuals to certain pathologies, renders them resilient.
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Affiliation(s)
- Julien Genty
- Laboratory of Neurophysiology, Institute for Health and Behavior, University of Luxembourg, 162a, avenue de la Faïencerie, L-1511, Luxembourg, Luxembourg
| | - Milène Tetsi Nomigni
- Laboratory of Neurophysiology, Institute for Health and Behavior, University of Luxembourg, 162a, avenue de la Faïencerie, L-1511, Luxembourg, Luxembourg
| | - Fernand Anton
- Laboratory of Neurophysiology, Institute for Health and Behavior, University of Luxembourg, 162a, avenue de la Faïencerie, L-1511, Luxembourg, Luxembourg
| | - Ulrike Hanesch
- Laboratory of Neurophysiology, Institute for Health and Behavior, University of Luxembourg, 162a, avenue de la Faïencerie, L-1511, Luxembourg, Luxembourg
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Kang S, Li J, Bekker A, Ye JH. Rescue of glutamate transport in the lateral habenula alleviates depression- and anxiety-like behaviors in ethanol-withdrawn rats. Neuropharmacology 2017; 129:47-56. [PMID: 29128307 DOI: 10.1016/j.neuropharm.2017.11.013] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2017] [Revised: 11/02/2017] [Accepted: 11/07/2017] [Indexed: 12/21/2022]
Abstract
Alcoholism and psychiatric disorders like depression and anxiety are often comorbid. Although the mechanisms underlying this comorbidity are unclear, emerging evidence suggests that maladaptation of the glial glutamate transporter GLT-1 may play a role. Findings from animal and human studies have linked aversive states, including those related to drugs of abuse and depression, to aberrant activity in the lateral habenula (LHb). The relationship between GLT-1 maladaptation, LHb activity, and abnormal behaviors related to alcohol withdrawal, however, remains unknown. Here we show that dihydrokainic acid (DHK), a GLT-1 blocker, potentiated glutamatergic transmission to LHb neurons in slices from ethanol naïve rats; this potentiation, though, was not observed in slices from rats withdrawn from repeated in vivo ethanol administration, suggesting reduced GLT-1 function. Furthermore, GLT-1 protein expression was reduced in the LHb of withdrawn rats. This reduction was restored by systemic administration of ceftriaxone, a β-lactam antibiotic known to increase GLT-1 expression. Systemic ceftriaxone treatment also normalized the hyperactivity of LHb neurons in slices from withdrawn rats, which was reversed by bath-applied DHK. Finally, systemic administration of ceftriaxone alleviated depression- and anxiety-like behaviors, which was fully blocked by intra-LHb administrations of DHK, suggesting that GLT-1's function in the LHb is critical. These findings highlight the significant role of LHb astrocytic GLT-1 in the hyperactivity of LHb neurons, and in depressive- and anxiety-like behaviors during ethanol withdrawal. Thus, GLT-1 in the LHb could serve as a therapeutic target for psychiatric disorders comorbid with ethanol withdrawal.
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Affiliation(s)
- Seungwoo Kang
- Department of Anesthesiology, Pharmacology, Physiology, and Neuroscience, Rutgers, The State University of New Jersey, New Jersey Medical School, Newark, NJ, USA
| | - Jing Li
- Department of Anesthesiology, Pharmacology, Physiology, and Neuroscience, Rutgers, The State University of New Jersey, New Jersey Medical School, Newark, NJ, USA
| | - Alex Bekker
- Department of Anesthesiology, Pharmacology, Physiology, and Neuroscience, Rutgers, The State University of New Jersey, New Jersey Medical School, Newark, NJ, USA
| | - Jiang-Hong Ye
- Department of Anesthesiology, Pharmacology, Physiology, and Neuroscience, Rutgers, The State University of New Jersey, New Jersey Medical School, Newark, NJ, USA.
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Glutamate Transport System as a Novel Therapeutic Target in Chronic Pain: Molecular Mechanisms and Pharmacology. ADVANCES IN NEUROBIOLOGY 2017; 16:225-253. [PMID: 28828613 DOI: 10.1007/978-3-319-55769-4_11] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The vast majority of peripheral neurons sensing noxious stimuli and conducting pain signals to the dorsal horn of the spinal cord utilize glutamate as a chemical transmitter of excitation. High-affinity glutamate transporter subtypes GLAST/EAAT1, GLT1/EAAT2, EAAC1/EAAT3, and EAAT4, differentially expressed on sensory neurons, postsynaptic spinal interneurons, and neighboring glia, ensure fine modulation of glutamate neurotransmission in the spinal cord. The glutamate transport system seems to play important roles in molecular mechanisms underlying chronic pain and analgesia. Downregulation of glutamate transporters (GluTs) often precedes or occurs simultaneously with development of hypersensitivity to thermal or tactile stimuli in various models of chronic pain. Moreover, antisense knockdown or pharmacological inhibition of these membrane proteins can induce or aggravate pain. In contrast, upregulation of GluTs by positive pharmacological modulators or by viral gene transfer to the spinal cord can reverse the development of such pathological hypersensitivity. Furthermore, some multi-target drugs displaying analgesic properties (e.g., tricyclic antidepressant amitriptyline, riluzole, anticonvulsant valproate, tetracycline antibiotic minocycline, β-lactam antibiotic ceftriaxone and its structural analog devoid of antibacterial activity, clavulanic acid) can significantly increase the spinal glutamate uptake. Thus, mounting evidence points at GluTs as prospective therapeutic target for chronic pain treatment. However, design and development of new analgesics based on the modulation of glutamate uptake will require more precise knowledge of molecular mechanisms underlying physiological or aberrant functioning of this transport system in the spinal cord.
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14
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Xu D, Omura T, Masaki N, Arima H, Banno T, Okamoto A, Hanada M, Takei S, Matsushita S, Sugiyama E, Setou M, Matsuyama Y. Increased arachidonic acid-containing phosphatidylcholine is associated with reactive microglia and astrocytes in the spinal cord after peripheral nerve injury. Sci Rep 2016; 6:26427. [PMID: 27210057 PMCID: PMC4876408 DOI: 10.1038/srep26427] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2015] [Accepted: 04/28/2016] [Indexed: 12/30/2022] Open
Abstract
Peripheral nerve injury (PNI) triggers cellular and molecular changes in the spinal cord. However, little is known about how the polyunsaturated fatty acid-containing phosphatidylcholines (PUFA-PCs) are regulated in the spinal cord after PNI and the association of PUFA-PCs with the non-neuronal cells within in the central nervous system (CNS). In this study, we found that arachidonic acid-containing phosphatidylcholine (AA-PC), [PC(16:0/20:4)+K](+), was significantly increased in the ipsilateral ventral and dorsal horns of the spinal cord after sciatic nerve transection, and the increased expression of [PC(16:0/20:4)+K](+) spatiotemporally resembled the increase of reactive microglia and the astrocytes. From the lipidomics point of view, we conclude that [PC(16:0/20:4)+K](+) could be the main phospholipid in the spinal cord influenced by PNI, and the regulation of specific phospholipid molecule in the CNS after PNI is associated with the reactive microglia and astrocytes.
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Affiliation(s)
- Dongmin Xu
- Department of Orthopaedic Surgery, Hamamatsu University School of Medicine, 1-20-1, Handayama, Higashi-ku, Hamamatsu, Shizuoka 431-3192, Japan
| | - Takao Omura
- Department of Orthopaedic Surgery, Hamamatsu University School of Medicine, 1-20-1, Handayama, Higashi-ku, Hamamatsu, Shizuoka 431-3192, Japan
| | - Noritaka Masaki
- Department of Cell Biology and Anatomy, Hamamatsu University School of Medicine, 1-20-1, Handayama, Higashi-ku, Hamamatsu, Shizuoka 431-3192, Japan
| | - Hideyuki Arima
- Department of Orthopaedic Surgery, Hamamatsu University School of Medicine, 1-20-1, Handayama, Higashi-ku, Hamamatsu, Shizuoka 431-3192, Japan
| | - Tomohiro Banno
- Department of Orthopaedic Surgery, Hamamatsu University School of Medicine, 1-20-1, Handayama, Higashi-ku, Hamamatsu, Shizuoka 431-3192, Japan
| | - Ayako Okamoto
- Department of Orthopaedic Surgery, Hamamatsu University School of Medicine, 1-20-1, Handayama, Higashi-ku, Hamamatsu, Shizuoka 431-3192, Japan
| | - Mitsuru Hanada
- Department of Orthopaedic Surgery, Hamamatsu University School of Medicine, 1-20-1, Handayama, Higashi-ku, Hamamatsu, Shizuoka 431-3192, Japan
| | - Shiro Takei
- Department of Cell Biology and Anatomy, Hamamatsu University School of Medicine, 1-20-1, Handayama, Higashi-ku, Hamamatsu, Shizuoka 431-3192, Japan
| | - Shoko Matsushita
- Department of Cell Biology and Anatomy, Hamamatsu University School of Medicine, 1-20-1, Handayama, Higashi-ku, Hamamatsu, Shizuoka 431-3192, Japan
| | - Eiji Sugiyama
- Department of Cell Biology and Anatomy, Hamamatsu University School of Medicine, 1-20-1, Handayama, Higashi-ku, Hamamatsu, Shizuoka 431-3192, Japan
| | - Mitsutoshi Setou
- Department of Cell Biology and Anatomy, Hamamatsu University School of Medicine, 1-20-1, Handayama, Higashi-ku, Hamamatsu, Shizuoka 431-3192, Japan
- Department of Systems Molecular Anatomy, Institute for Medical Photonics Research, Preeminent Medical Photonics Education & Research Center, Hamamatsu University School of Medicine, 1-20-1, Handayama, Higashi-ku, Hamamatsu, Shizuoka 431-3192, Japan
- The Institute of Medical Science, The University of Tokyo, 4-6-1 Shirokanedai, Minato-ku, Tokyo 108-8639, Japan
- Department of Anatomy, The University of Hong Kong, Pokfulam, Hong Kong, 999077 China
- Division of Neural Systematics, National Institute for Physiological Sciences, 38 Nishigonaka Myodaiji, Okazaki, Aichi, 444-8585, Japan
| | - Yukihiro Matsuyama
- Department of Orthopaedic Surgery, Hamamatsu University School of Medicine, 1-20-1, Handayama, Higashi-ku, Hamamatsu, Shizuoka 431-3192, Japan
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15
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Yousuf MS, Kerr BJ. The Role of Regulatory Transporters in Neuropathic Pain. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2016; 75:245-71. [PMID: 26920015 DOI: 10.1016/bs.apha.2015.12.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
Neuropathic pain arises from an injury or disease of the somatosensory nervous system rather than stimulation of pain receptors. As a result, the fine balance between excitation and inhibition is perturbed leading to hyperalgesia and allodynia. Various neuropathic pain models provide considerable evidence that changes in the glutamatergic, GABAergic, and monoaminergic systems. Neurotransmitter reuptake transporter proteins have the potential to change the temporal and spatial profile of various neurotransmitters throughout the nervous system. This, in turn, can affect the downstream effects of these neurotransmitters and hence modulate pain. This chapter explores various reuptake transporter systems and implicates their role in pain processing. Understanding the transporter systems will enhance drug discovery targeting different facets of neuropathic pain.
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Affiliation(s)
- Muhammad Saad Yousuf
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, Alberta, Canada
| | - Bradley J Kerr
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, Alberta, Canada; Department of Pharmacology, University of Alberta, Edmonton, Alberta, Canada; Department of Anesthesiology and Pain Medicine, University of Alberta, Edmonton, Alberta, Canada.
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16
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Oklinski MK, Choi HJ, Kwon TH. Peripheral nerve injury induces aquaporin-4 expression and astrocytic enlargement in spinal cord. Neuroscience 2015; 311:138-52. [PMID: 26480815 DOI: 10.1016/j.neuroscience.2015.10.025] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2015] [Revised: 09/22/2015] [Accepted: 10/13/2015] [Indexed: 12/15/2022]
Abstract
Aquaporin-4 (AQP4), a water channel protein, is expressed mainly in the perivascular end-feet of astrocytes in the brain and spinal cord. Dysregulation of AQP4 is critically associated with abnormal water transport in the astrocytes. We aimed to examine whether peripheral nerve injury (PNI) could induce the changes of AQP4 expression and astrocytic morphology in the spinal cord. Two different PNI models [partial sciatic nerve transection (PST) and chronic constriction injury (CCI)] were established on the left sciatic nerve in Sprague-Dawley rats, which decreased the pain withdrawal threshold in the ipsilateral hind paws. Both PNI models were associated with a persistent up-regulation of AQP4 in the ipsilateral dorsal horn at the lower lumbar region over 3 weeks, despite an absence of direct injury to the spinal cord. Three-dimensional reconstruction of astrocytes was made and morphometric analysis was done. Up-regulation of AQP4 was accompanied by a significant increase in the length and volume of astrocytic processes and the number of branch points. The most prominent changes were present in the distal processes of the astrocytes and the changes were maintained throughout the whole experimental period. Extravasation of systemically administered tracers Evans Blue and sodium fluorescein was not seen in both models. Taken together, PNI was associated with a long-lasting AQP4 up-regulation and enlargement of astrocytic processes in the spinal cord in rats, both of which were not related to the disruption of blood-spinal cord barrier. The findings could provide novel insights on the understanding of pathophysiology of spinal cords after PNI.
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Affiliation(s)
- M K Oklinski
- Department of Biochemistry and Cell Biology, School of Medicine, Kyungpook National University, Taegu 41944, South Korea
| | - H-J Choi
- Department of Biochemistry and Cell Biology, School of Medicine, Kyungpook National University, Taegu 41944, South Korea
| | - T-H Kwon
- Department of Biochemistry and Cell Biology, School of Medicine, Kyungpook National University, Taegu 41944, South Korea.
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17
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Wang XQ, Zhong XL, Li ZB, Wang HT, Zhang J, Li F, Zhang JY, Dai RP, Xin-Fu Z, Li CQ, Li ZY, Bi FF. Differential roles of hippocampal glutamatergic receptors in neuropathic anxiety-like behavior after partial sciatic nerve ligation in rats. BMC Neurosci 2015; 16:14. [PMID: 25884414 PMCID: PMC4372276 DOI: 10.1186/s12868-015-0150-x] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2014] [Accepted: 02/25/2015] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND Neuropathic pain evoked by nerve injury is frequently accompanied by deterioration of emotional behaviors, but the underlying signaling mechanisms remain elusive. Glutamate (Glu) is the major mediator of excitatory synaptic transmission throughout the brain, and abnormal activity of the glutamatergic system has been implicated in the pathophysiology of pain and associated emotional comorbidities. In this study we used the partial sciatic nerve ligation (PSNL) model of neuropathic pain in rats to characterize the development of anxiety-like behavior, the expression of glutamatergic receptors, and the phosphorylation of extracellular signal-regulated kinase (ERK) in the hippocampus, the region that encodes memories related to emotions. RESULTS We found that the mechanical withdrawal threshold was significantly reduced and an anxiety-like behavior was increased as determined via open field tests and elevated plus-maze tests at 28 days after injury. No significant differences were found in the ratio of sucrose preference and immobility time detected by sucrose preference tests and forced swimming tests respectively, possibly due to the timing factor. The expression of N-methyl-D-aspartate (NMDA) receptor subtypes NR1 and NR2B, but not NR2A, GluR1, or GluR2 (the main subtype of the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid [AMPA] receptor) in the hippocampus of injured rats was significantly reduced. Moreover, PSNL resulted in decreased phosphorylation of ERK1/2 in the hippocampus. Intriguingly, treatment with D-serine (a co-agonist of NMDA receptor, 1 g/kg intraperitoneally) reduced the anxiety-like behavior but not the mechanical hypersensitivity induced by PSNL. CONCLUSIONS PSNL can induce significant anxiety-like but not depression-like behavior, and trigger down-regulation of NMDA but not AMPA receptors in the hippocampus at 28 days after injury.
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Affiliation(s)
- Xue-Qin Wang
- Center for Experimental Medicine, the Third Xiangya Hospital, Central South University, Tongzipo Road 138, Changsha, Hunan, China. .,Department of Anesthesiology, the Third Xiangya Hospital, Central South University, Tongzipo Road 138, Changsha, Hunan, China. .,Department of Anatomy and Neurobiology, School of Basic Medical Science, Central South University, Tongzipo Road 172, Changsha, Hunan, China.
| | - Xiao-Lin Zhong
- Department of Anatomy and Neurobiology, School of Basic Medical Science, Central South University, Tongzipo Road 172, Changsha, Hunan, China.
| | - Zhi-Bin Li
- Department of Neurology, XiangYa Hospital, Central South University, XiangYa Road 88, Changsha, Hunan, China.
| | - Hong-Tao Wang
- Department of Anatomy and Neurobiology, School of Basic Medical Science, Central South University, Tongzipo Road 172, Changsha, Hunan, China.
| | - Juan Zhang
- Department of Anatomy and Neurobiology, School of Basic Medical Science, Central South University, Tongzipo Road 172, Changsha, Hunan, China.
| | - Fang Li
- Department of Anatomy and Neurobiology, School of Basic Medical Science, Central South University, Tongzipo Road 172, Changsha, Hunan, China.
| | - Jian-Yi Zhang
- Department of Anatomy and Neurobiology, School of Basic Medical Science, Central South University, Tongzipo Road 172, Changsha, Hunan, China.
| | - Ru-Ping Dai
- Department of Anesthesia, the Second XiangYa Hospital of Central South University, Ren-Min Road 86, Changsha, Hunan, China.
| | - Zhou Xin-Fu
- School of Pharmacy and Medical Sciences, Sansom Institute, University of South Australia, Adelaide, SA, 5000, Australia.
| | - Chang-Qi Li
- Department of Anatomy and Neurobiology, School of Basic Medical Science, Central South University, Tongzipo Road 172, Changsha, Hunan, China.
| | - Zhi-Yuan Li
- Department of Anatomy and Neurobiology, School of Basic Medical Science, Central South University, Tongzipo Road 172, Changsha, Hunan, China.
| | - Fang-Fang Bi
- Department of Neurology, XiangYa Hospital, Central South University, XiangYa Road 88, Changsha, Hunan, China.
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18
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Murali SS, Napier IA, Mohammadi SA, Alewood PF, Lewis RJ, Christie MJ. High-voltage-activated calcium current subtypes in mouse DRG neurons adapt in a subpopulation-specific manner after nerve injury. J Neurophysiol 2014; 113:1511-9. [PMID: 25505111 DOI: 10.1152/jn.00608.2014] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Changes in ion channel function and expression are characteristic of neuropathic pain. Voltage-gated calcium channels (VGCCs) are integral for neurotransmission and membrane excitability, but relatively little is known about changes in their expression after nerve injury. In this study, we investigate whether peripheral nerve ligation is followed by changes in the density and proportion of high-voltage-activated (HVA) VGCC current subtypes in dorsal root ganglion (DRG) neurons, the contribution of presynaptic N-type calcium channels in evoked excitatory postsynaptic currents (EPSCs) recorded from dorsal horn neurons in the spinal cord, and the changes in expression of mRNA encoding VGCC subunits in DRG neurons. Using C57BL/6 mice [8- to 11-wk-old males (n = 91)] for partial sciatic nerve ligation or sham surgery, we performed whole cell patch-clamp recordings on isolated DRG neurons and dorsal horn neurons and measured the expression of all VGCC subunits with RT-PCR in DRG neurons. After nerve injury, the density of P/Q-type current was reduced overall in DRG neurons. There was an increase in the percentage of N-type and a decrease in that of P/Q-type current in medium- to large-diameter neurons. No changes were found in the contribution of presynaptic N-type calcium channels in evoked EPSCs recorded from dorsal horn neurons. The α2δ-1 subunit was upregulated by 1.7-fold and γ-3, γ-2, and β-4 subunits were all downregulated 1.7-fold in injured neurons compared with sham-operated neurons. This comprehensive characterization of HVA VGCC subtypes in mouse DRG neurons after nerve injury revealed changes in N- and P/Q-type current proportions only in medium- to large-diameter neurons.
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Affiliation(s)
- Swetha S Murali
- Discipline of Pharmacology, University of Sydney, Sydney, New South Wales, Australia;
| | - Ian A Napier
- Discipline of Pharmacology, University of Sydney, Sydney, New South Wales, Australia
| | - Sarasa A Mohammadi
- Discipline of Pharmacology, University of Sydney, Sydney, New South Wales, Australia
| | - Paul F Alewood
- Institute for Molecular Bioscience, The University of Queensland, St Lucia, Queensland, Australia
| | - Richard J Lewis
- Institute for Molecular Bioscience, The University of Queensland, St Lucia, Queensland, Australia
| | - MacDonald J Christie
- Discipline of Pharmacology, University of Sydney, Sydney, New South Wales, Australia
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19
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Gegelashvili G, Bjerrum OJ. High-affinity glutamate transporters in chronic pain: an emerging therapeutic target. J Neurochem 2014; 131:712-30. [DOI: 10.1111/jnc.12957] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2014] [Revised: 09/18/2014] [Accepted: 09/25/2014] [Indexed: 01/13/2023]
Affiliation(s)
- Georgi Gegelashvili
- Department of Drug Design and Pharmacology; Faculty of Health and Medical Sciences; University of Copenhagen; Copenhagen Denmark
- Institute of Chemical Biology; Ilia State University; Tbilisi Georgia
| | - Ole J. Bjerrum
- Department of Drug Design and Pharmacology; Faculty of Health and Medical Sciences; University of Copenhagen; Copenhagen Denmark
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20
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Chen NF, Huang SY, Chen WF, Chen CH, Lu CH, Chen CL, Yang SN, Wang HM, Wen ZH. TGF-β1 attenuates spinal neuroinflammation and the excitatory amino acid system in rats with neuropathic pain. THE JOURNAL OF PAIN 2014; 14:1671-85. [PMID: 24290447 DOI: 10.1016/j.jpain.2013.08.010] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2013] [Revised: 08/16/2013] [Accepted: 08/28/2013] [Indexed: 01/28/2023]
Abstract
UNLABELLED Previous studies have reported that the intrathecal (i.t.) administration of transforming growth factor β1 (TGF-β1) prevents and reverses neuropathic pain. However, only limited information is available regarding the possible role and effects of spinal TGF-β1 in neuropathic pain. We aimed to investigate the antinociceptive effects of exogenous TGF-β1 on chronic constriction injury (CCI)-induced neuropathic pain in rats. We demonstrated that sciatic nerve injury caused a downregulation of endogenous TGF-β1 levels on the ipsilateral side of the lumbar spinal dorsal gray matter, and that the i.t. administration of TGF-β1 (.01-10 ng) significantly attenuated CCI-induced thermal hyperalgesia in neuropathic rats. TGF-β1 significantly inhibited CCI-induced spinal neuroinflammation, microglial and astrocytic activation, and upregulation of tumor necrosis factor-α. Moreover, i.t. TGF-β1 significantly attenuated the CCI-induced downregulation of glutamate transporter 1, the glutamate aspartate transporter, and the excitatory amino acid carrier 1 on the ipsilateral side. Furthermore, i.t. TGF-β1 significantly decreased the concentrations of 2 excitatory amino acids, aspartate and glutamate, in the spinal dialysates in CCI rats. In summary, we conclude that the mechanisms of the antinociceptive effects of i.t. TGF-β1 in neuropathy may include attenuation of spinal neuroinflammation, attenuation, or upregulation of glutamate transporter downregulation, and a decrease of spinal extracellular excitatory amino acids. PERSPECTIVE Clinically, medical treatment is usually initiated after the onset of intractable pain. Therefore, in the present study, i.t. TGF-β1 was designed to be administered 2 weeks after the establishment of CCI pain. Compared to the continuous TGF-β1 infusion mode, single-dose administration seems more convenient and practical to use.
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Affiliation(s)
- Nan-Fu Chen
- Department of Marine Biotechnology and Resources, Asia-Pacific Ocean Research Center, National Sun Yat-sen University, Kaohsiung, Taiwan; Division of Neurosurgery, Department of Surgery, Kaohsiung Armed Forces General Hospital, Kaohsiung, Taiwan
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Glutamate dysregulation in the trigeminal ganglion: a novel mechanism for peripheral sensitization of the craniofacial region. Neuroscience 2013; 256:23-35. [PMID: 24144624 DOI: 10.1016/j.neuroscience.2013.10.009] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2013] [Revised: 09/24/2013] [Accepted: 10/07/2013] [Indexed: 10/26/2022]
Abstract
In the trigeminal ganglion (TG), satellite glial cells (SGCs) form a functional unit with neurons. It has been proposed that SGCs participate in regulating extracellular glutamate levels and that dysfunction of this SGC capacity can impact nociceptive transmission in craniofacial pain conditions. This study investigated whether SGCs release glutamate and whether elevation of TG glutamate concentration alters response properties of trigeminal afferent fibers. Immunohistochemistry was used to assess glutamate content and the expression of excitatory amino acid transporter (EAAT)1 and EAAT2 in TG sections. SGCs contained glutamate and expressed EAAT1 and EAAT2. Potassium chloride (10 mM) was used to evoke glutamate release from cultured rat SGCs treated with the EAAT1/2 inhibitor (3S)-3-[[3-[[4-(trifluoromethyl)ben zoyl]amino]phenyl]methoxy]-L-aspartic acid (TFB-TBOA) or control. Treatment with TFB-TBOA (1 and 10 μM) significantly reduced the glutamate concentration from 10.6 ± 1.1 to 5.8 ± 1.4 μM and 3.0 ± 0.8 μM, respectively (p<0.05). Electrophysiology experiments were conducted in anaesthetized rats to determine the effect of intraganglionic injections of glutamate on the response properties of ganglion neurons that innervated either the temporalis or masseter muscle. Intraganglionic injection of glutamate (500 mM, 3 μl) evoked afferent discharge and significantly reduced muscle afferent mechanical threshold. Glutamate-evoked discharge was attenuated bythe N-methyl-D-aspartate receptor antagonist 2-amino-5-phosphonovalerate (APV) and increased by TFB-TBOA, whereas mechanical sensitization was only sensitive to APV. Antidromic invasion of muscle afferent fibers by electrical stimulation of the caudal brainstem (10 Hz) or local anesthesia of the brainstem with lidocaine did not alter glutamate-induced mechanical sensitization. These findings provide a novel mechanism whereby dysfunctional trigeminal SGCs could contribute to cranial muscle tenderness in craniofacial pain conditions such as migraine headache.
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22
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Murugan M, Ling EA, Kaur C. Dysregulated glutamate uptake by astrocytes causes oligodendroglia death in hypoxic perventricular white matter damage. Mol Cell Neurosci 2013; 56:342-54. [PMID: 23859823 DOI: 10.1016/j.mcn.2013.07.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2012] [Revised: 07/04/2013] [Accepted: 07/08/2013] [Indexed: 01/31/2023] Open
Abstract
Excess glutamate mediates damage to oligodendroglia, resulting in myelination disturbances characteristic of hypoxic periventricular white matter (PWM) damage. We sought to examine if hypoxia altered the expression of astroglial excitatory amino acid transporters (EAAT1, EAAT2 and EAAT3) in the PWM, and, if so, whether it activated astroglial N-methyl D-aspartate receptors (NMDAR) which might lead to apoptosis of oligodendroglia. EAAT expression in the PWM of neonatal rats was measured at different time points after hypoxic exposure; it was attenuated at 7 and 14 d following hypoxia. Hypoxia prevented the uptake of glutamate by astroglial EAATs causing increased levels of extracellular glutamate. Excess glutamate augmented the expression of functional astroglial NMDAR. Following hypoxia, an increase in gap junction proteins between astroglia and oligodendroglia aided in the spreading of NMDAR-mediated excitotoxic calcium signals into the latter cell type triggering its apoptosis. Hence, dysregulated glutamate homeostasis is believed to contribute to hypoxia-induced death of oligodendroglia leading to neonatal PWM damage.
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Affiliation(s)
- Madhuvika Murugan
- Department of Anatomy, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117597, Singapore
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23
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Evidence for glutamate as a neuroglial transmitter within sensory ganglia. PLoS One 2013; 8:e68312. [PMID: 23844184 PMCID: PMC3699553 DOI: 10.1371/journal.pone.0068312] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2013] [Accepted: 05/28/2013] [Indexed: 11/19/2022] Open
Abstract
This study examines key elements of glutamatergic transmission within sensory ganglia of the rat. We show that the soma of primary sensory neurons release glutamate when depolarized. Using acute dissociated mixed neuronal/glia cultures of dorsal root ganglia (DRG) or trigeminal ganglia and a colorimetric assay, we show that when glutamate uptake by satellite glial cells (SGCs) is inhibited, KCl stimulation leads to simultaneous increase of glutamate in the culture medium. With calcium imaging we see that the soma of primary sensory neurons and SGCs respond to AMPA, NMDA, kainate and mGluR agonists, and selective antagonists block this response. Using whole cell patch-clamp technique, inward currents were recorded from small diameter (<30 µm) DRG neurons from intact DRGs (ex-vivo whole ganglion preparation) in response to local application of the above glutamate receptor agonists. Following a chronic constriction injury (CCI) of either the inferior orbital nerve or the sciatic nerve, glutamate expression increases in the trigeminal ganglia and DRG respectively. This increase occurs in neurons of all diameters and is present in the somata of neurons with injured axons as well as in somata of neighboring uninjured neurons. These data provides additional evidence that glutamate can be released within the sensory ganglion, and that the somata of primary sensory neurons as well as SGCs express functional glutamate receptors at their surface. These findings, together with our previous gene knockdown data, suggest that glutamatergic transmission within the ganglion could impact nociceptive threshold.
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24
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Naka A, Gruber-Schoffnegger D, Sandkühler J. Non-Hebbian plasticity at C-fiber synapses in rat spinal cord lamina I neurons. Pain 2013; 154:1333-42. [PMID: 23707311 PMCID: PMC3708128 DOI: 10.1016/j.pain.2013.04.011] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2012] [Revised: 03/26/2013] [Accepted: 04/03/2013] [Indexed: 11/23/2022]
Abstract
Current concepts of memory storage are largely based on Hebbian-type synaptic long-term potentiation induced by concurrent activity of pre- and postsynaptic neurons. Little is known about non-Hebbian synaptic plasticity, which, if present in nociceptive pathways, could resolve a number of unexplained findings. We performed whole-cell patch-clamp recordings in rat spinal cord slices and found that a rise in postsynaptic [Ca2+]i due to postsynaptic depolarization was sufficient to induce synaptic long-term potentiation (LTP) in the absence of any presynaptic conditioning stimulation. LTP induction could be prevented by postsynaptic application of the Ca2+ chelator BAPTA (1,2-bis(o-aminophenoxy)ethane-N,N,N′,N′-tetraacetic acid), the L-type voltage-gated calcium channel (VGCC) antagonist nifedipine, and by postsynaptic application of the NMDA receptor antagonist MK801. This indicates that synaptic potentiation was induced postsynaptically by Ca2+ entry likely via L-type voltage-gated Ca2+ channels (VGCC) and via NMDA receptor channels. The paired pulse ratio and the coefficient of variation remained unchanged in neurons expressing LTP, suggesting that this form of synaptic potentiation was not only induced, but also expressed postsynaptically. Postsynaptic depolarization had no influence on firing patterns, action potential shape, or neuronal excitability. An increase in [Ca2+]i in spinal lamina I neurons induces a non-Hebbian form of synaptic plasticity in spinal nociceptive pathways without affecting neuronal active and passive membrane properties.
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Affiliation(s)
- Asami Naka
- Department of Neurophysiology, Center for Brain Research, Medical University of Vienna, Spitalgasse 4, 1090 Vienna, Austria
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Mao J. Current challenges in translational pain research. Trends Pharmacol Sci 2012; 33:568-73. [PMID: 22959652 PMCID: PMC3482290 DOI: 10.1016/j.tips.2012.08.001] [Citation(s) in RCA: 90] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2012] [Revised: 08/08/2012] [Accepted: 08/13/2012] [Indexed: 12/31/2022]
Abstract
The current gap between basic science research and the development of new analgesics presents a serious challenge for the future of pain medicine. This challenge is particularly difficult in the search for better treatment for comorbid chronic pain conditions because: (i) animal 'pain' models do not simulate multidimensional clinical pain conditions; (ii) animal behavioral testing does not assess subjective pain experience; (iii) preclinical data provide little assurance regarding the direction of new analgesic development; and (iv) clinical trials routinely use over-sanitized study populations and fail to capture the multidisciplinary consequences of comorbid chronic pain. Therefore, a paradigm shift in translational pain research is necessary to transform the current strategy from focusing on molecular switches of nociception to studying pain as a system-based integral response that includes psychosocial comorbidities. Several key issues of translational pain research are discussed in this review.
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Affiliation(s)
- Jianren Mao
- MGH Center for Translational Pain Research, Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA.
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Hauser JL, Edson EB, Hooks BM, Chen C. Metabotropic glutamate receptors and glutamate transporters shape transmission at the developing retinogeniculate synapse. J Neurophysiol 2012; 109:113-23. [PMID: 23076103 DOI: 10.1152/jn.00897.2012] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Over the first few postnatal weeks, extensive remodeling occurs at the developing murine retinogeniculate synapse, the connection between retinal ganglion cells (RGCs) and the visual thalamus. Although numerous studies have described the role of activity in the refinement of this connection, little is known about the mechanisms that regulate glutamate concentration at and around the synapse over development. Here we show that interactions between glutamate transporters and metabotropic glutamate receptors (mGluRs) dynamically control the peak and time course of the excitatory postsynaptic current (EPSC) at the immature synapse. Inhibiting glutamate transporters by bath application of TBOA (DL-threo-β-benzyloxyaspartic acid) prolonged the decay kinetics of both α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) and N-methyl-D-aspartate receptor (NMDAR) currents at all ages. Moreover, at the immature synapse, TBOA-induced increases in glutamate concentration led to the activation of group II/III mGluRs and a subsequent reduction in neurotransmitter release at RGC terminals. Inhibition of this negative-feedback mechanism resulted in a small but significant increase in peak NMDAR EPSCs during basal stimulation and a substantial increase in the peak with coapplication of TBOA. Activation of mGluRs also shaped the synaptic response during high-frequency trains of stimulation that mimic spontaneous RGC activity. At the mature synapse, however, the group II mGluRs and the group III mGluR7-mediated response are downregulated. Our results suggest that transporters reduce spillover of glutamate, shielding NMDARs and mGluRs from the neurotransmitter. Furthermore, mechanisms of glutamate clearance and release interact dynamically to control the glutamate transient at the developing retinogeniculate synapse.
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Affiliation(s)
- Jessica L Hauser
- Department of Neurology, FM Kirby Neurobiology Center, Children's Hospital, Boston, MA 02115, USA
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