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Weman HM, Ceder MM, Ahemaiti A, Magnusson KA, Henriksson K, Andréasson L, Lagerström MC. Spinal Glycine Receptor Alpha 3 Cells Communicate Sensations of Chemical Itch in Hairy Skin. J Neurosci 2024; 44:e1585232024. [PMID: 38553047 PMCID: PMC11079978 DOI: 10.1523/jneurosci.1585-23.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2023] [Revised: 01/31/2024] [Accepted: 02/15/2024] [Indexed: 05/12/2024] Open
Abstract
Glycinergic neurons regulate nociceptive and pruriceptive signaling in the spinal cord, but the identity and role of the glycine-regulated neurons are not fully known. Herein, we have characterized spinal glycine receptor alpha 3 (Glra3) subunit-expressing neurons in Glra3-Cre female and male mice. Glra3-Cre(+) neurons express Glra3, are located mainly in laminae III-VI, and respond to glycine. Chemogenetic activation of spinal Glra3-Cre(+) neurons induced biting/licking, stomping, and guarding behaviors, indicative of both a nociceptive and pruriceptive role for this population. Chemogenetic inhibition did not affect mechanical or thermal responses but reduced behaviors evoked by compound 48/80 and chloroquine, revealing a pruriceptive role for these neurons. Spinal cells activated by compound 48/80 or chloroquine express Glra3, further supporting the phenotype. Retrograde tracing revealed that spinal Glra3-Cre(+) neurons receive input from afferents associated with pain and itch, and dorsal root stimulation validated the monosynaptic input. In conclusion, these results show that spinal Glra3(+) neurons contribute to acute communication of compound 48/80- and chloroquine-induced itch in hairy skin.
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Affiliation(s)
- Hannah M Weman
- Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala 75108, Sweden
| | - Mikaela M Ceder
- Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala 75108, Sweden
| | - Aikeremu Ahemaiti
- Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala 75108, Sweden
| | - Kajsa A Magnusson
- Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala 75108, Sweden
| | - Katharina Henriksson
- Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala 75108, Sweden
| | - Linn Andréasson
- Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala 75108, Sweden
| | - Malin C Lagerström
- Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala 75108, Sweden
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Huang 黄玉莹 Y, Chen 陈红 H, Shao 邵建英 JY, Zhou 周京京 JJ, Chen 陈少瑞 SR, Pan 潘惠麟 HL. Constitutive KCC2 Cell- and Synapse-Specifically Regulates NMDA Receptor Activity in the Spinal Cord. J Neurosci 2024; 44:e1943232023. [PMID: 38124193 PMCID: PMC10860486 DOI: 10.1523/jneurosci.1943-23.2023] [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: 10/13/2023] [Revised: 11/20/2023] [Accepted: 12/05/2023] [Indexed: 12/23/2023] Open
Abstract
K+-Cl- cotransporter-2 (KCC2) critically controls neuronal chloride homeostasis and maintains normal synaptic inhibition by GABA and glycine. Nerve injury diminishes synaptic inhibition in the spinal cord via KCC2 impairment. However, how KCC2 regulates nociceptive input to spinal excitatory and inhibitory neurons remains elusive. Here, we show that basal GABA reversal potentials were significantly more depolarized in vesicular GABA transporter (VGAT)-expressing inhibitory neurons than those in vesicular glutamate transporter-2 (VGluT2)-expressing excitatory neurons in spinal cords of male and female mice. Strikingly, inhibiting KCC2 with VU0463271 increased currents elicited by puff NMDA and the NMDAR-mediated frequency of mEPSCs in VGluT2, but not in VGAT, dorsal horn neurons. Notably, VU0463271 had no effect on EPSCs monosynaptically evoked from the dorsal root in VGluT2 neurons. Furthermore, VU0463271 augmented α2δ-1-NMDAR interactions and their protein levels in spinal cord synaptosomes. In Cacna2d1 KO mice, VU0463271 had no effect on puff NMDA currents or the mEPSC frequency in dorsal horn neurons. Disrupting α2δ-1-NMDAR interactions with α2δ-1 C-terminus mimicking peptide diminished VU0463271-induced potentiation in the mEPSC frequency and puff NMDA currents in VGluT2 neurons. Additionally, intrathecal injection of VU0463271 reduced mechanical and thermal thresholds in wild-type mice, but not in Cacna2d1 KO mice. VU0463271-induced pain hypersensitivity in mice was abrogated by co-treatment with the NMDAR antagonist, pregabalin (an α2δ-1 inhibitory ligand), or α2δ-1 C-terminus mimicking peptide. Our findings suggest that KCC2 controls presynaptic and postsynaptic NMDAR activity specifically in excitatory dorsal horn neurons. KCC2 impairment preferentially potentiates nociceptive transmission between spinal excitatory interneurons via α2δ-1-bound NMDARs.Significance statementImpaired function of potassium-chloride cotransporter-2 (KCC2), a key regulator of neuronal inhibition, in the spinal cord plays a major role in neuropathic pain. This study unveils that KCC2 controls spinal nociceptive synaptic strength via NMDA receptors in a cell type- and synapse type-specific manner. KCC2 inhibition preferentially augments presynaptic and postsynaptic NMDA receptor activity in spinal excitatory interneurons via α2δ-1 (previously known as a calcium channel subunit). Importantly, spinal KCC2 impairment triggers pain hypersensitivity through α2δ-1-coupled NMDA receptors. These findings pinpoint the cell and molecular substrates for the reciprocal relationship between spinal synaptic inhibition and excitation in chronic neuropathic pain. Targeting both KCC2 and α2δ-1–NMDA receptor complexes could be an effective strategy in managing neuropathic pain conditions.
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Affiliation(s)
- Yuying Huang 黄玉莹
- Department of Anesthesiology and Perioperative Medicine, Center for Neuroscience and Pain Research, The University of Texas MD Anderson Cancer Center, Houston 77030, Texas
| | - Hong Chen 陈红
- Department of Anesthesiology and Perioperative Medicine, Center for Neuroscience and Pain Research, The University of Texas MD Anderson Cancer Center, Houston 77030, Texas
| | - Jian-Ying Shao 邵建英
- Department of Anesthesiology and Perioperative Medicine, Center for Neuroscience and Pain Research, The University of Texas MD Anderson Cancer Center, Houston 77030, Texas
| | - Jing-Jing Zhou 周京京
- Department of Anesthesiology and Perioperative Medicine, Center for Neuroscience and Pain Research, The University of Texas MD Anderson Cancer Center, Houston 77030, Texas
| | - Shao-Rui Chen 陈少瑞
- Department of Anesthesiology and Perioperative Medicine, Center for Neuroscience and Pain Research, The University of Texas MD Anderson Cancer Center, Houston 77030, Texas
| | - Hui-Lin Pan 潘惠麟
- Department of Anesthesiology and Perioperative Medicine, Center for Neuroscience and Pain Research, The University of Texas MD Anderson Cancer Center, Houston 77030, Texas
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3
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Akbar S, Subhan F, Akbar A, Habib F, Shahbaz N, Ahmad A, Wadood A, Salman S. Targeting Anti-Inflammatory Pathways to Treat Diabetes-Induced Neuropathy by 6-Hydroxyflavanone. Nutrients 2023; 15:nu15112552. [PMID: 37299516 DOI: 10.3390/nu15112552] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2023] [Revised: 05/12/2023] [Accepted: 05/14/2023] [Indexed: 06/12/2023] Open
Abstract
It is evident that inflammation and metabolic syndrome instigated by diabetes mellitus can precipitate diabetes-induced neuropathy (DIN) and pain. In order to find an effective therapeutic method for diabetes-related problems, a multi-target-directed ligand model was used. 6-Hydroxyflavanone (6-HF) carrying anti-inflammatory and anti-neuropathic pain potential due to its quadruplicate mechanisms, targeting cyclooxygenase-2 (COX-2), 5-lipoxygenase (5-LOX), and opioid and GABA-A receptors was investigated. The anti-inflammatory potential of the test drug was confirmed utilizing in silico, in vitro, and in vivo tests. A molecular simulation approach was utilized to observe the interaction of 6-HF with the inflammatory enzyme COX-2 as well as opioid and GABA-A receptors. The same was confirmed via in vitro COX-2 and 5-LOX inhibitory assays. In vivo tests were performed to analyze the thermal anti-nociception in the hot-plate analgesiometer and anti-inflammatory action in the carrageenan-induced paw edema model in rodents. The potential anti-nociceptive effect of 6-HF was evaluated in the DIN model in rats. The Naloxone and Pentylenetetrazole (PTZ) antagonists were used to confirm the underlying mechanism of 6-HF. The molecular modeling studies revealed a favorable interaction of 6-HF with the identified protein molecules. In vitro inhibitory studies revealed that 6-HF inhibited the COX-2 and 5-LOX enzymes significantly. The 6-HF at dosages of 15, 30, and 60 mg/kg substantially reduced heat nociception in a hot plate analgesiometer as well as carrageenan-induced paw edema in rodent models. The authors discovered that 6-HF had anti-nociception properties in a streptozotocin-induced diabetic neuropathy model. According to the findings of this study, 6-HF was demonstrated to diminish inflammation caused by diabetes as well as its anti-nociception effect in DIN.
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Affiliation(s)
- Shehla Akbar
- Department of Pharmacy, CECOS University of IT and Emerging Sciences, Peshawar 25000, Pakistan
| | - Fazal Subhan
- Department of Pharmacy, CECOS University of IT and Emerging Sciences, Peshawar 25000, Pakistan
| | - Aroosha Akbar
- North West Institute of Health Sciences, Peshawar 25000, Pakistan
| | - Faiza Habib
- Institute of Basic Medical Sciences, Khyber Medical University, Peshawar 25000, Pakistan
| | - Naila Shahbaz
- Department of Pharmacy, Sarhad University of Science and Technology, Peshawar 25000, Pakistan
| | - Ashfaq Ahmad
- Department of Pharmacy, Sarhad University of Science and Technology, Peshawar 25000, Pakistan
| | - Abdul Wadood
- Department of Biochemistry, Shankar Abdul Wali Khan University, Mardan 23200, Pakistan
| | - Saad Salman
- Department of Pharmacy, CECOS University of IT and Emerging Sciences, Peshawar 25000, Pakistan
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4
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Cao B, Scherrer G, Chen L. Spinal cord retinoic acid receptor signaling gates mechanical hypersensitivity in neuropathic pain. Neuron 2022; 110:4108-4124.e6. [PMID: 36223767 PMCID: PMC9789181 DOI: 10.1016/j.neuron.2022.09.027] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Revised: 08/27/2022] [Accepted: 09/22/2022] [Indexed: 02/08/2023]
Abstract
Central sensitization caused by spinal disinhibition is a key mechanism of mechanical allodynia in neuropathic pain. However, the molecular mechanisms underlying spinal disinhibition after nerve injury remain unclear. Here, we show in mice that spared nerve injury (SNI), which induces mechanical hypersensitivity and neuropathic pain, triggers homeostatic reduction of inhibitory outputs from dorsal horn parvalbumin-positive (PV+) interneurons onto both primary afferent terminals and excitatory interneurons. The reduction in inhibitory outputs drives hyperactivation of the spinal cord nociceptive pathway, causing mechanical hypersensitivity. We identified the retinoic acid receptor RARα, a central regulator of homeostatic plasticity, as the key molecular mediator for this synaptic disinhibition. Deletion of RARα in spinal PV+ neurons or application of an RARα antagonist in the spinal cord prevented the development of SNI-induced mechanical hypersensitivity. Our results identify RARα as a crucial molecular effector for neuropathic pain and a potential target for its treatment.
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Affiliation(s)
- Bing Cao
- Department of Neurosurgery, Wu Tsai Neuroscience Institute, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Gregory Scherrer
- Department of Cell Biology and Physiology, UNC Neuroscience Center, Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Lu Chen
- Department of Neurosurgery, Wu Tsai Neuroscience Institute, Stanford University School of Medicine, Stanford, CA 94305, USA.
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5
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Intrathecal implantation surgical considerations in rodents; a review. J Neurosci Methods 2021; 363:109327. [PMID: 34418443 DOI: 10.1016/j.jneumeth.2021.109327] [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: 01/20/2021] [Revised: 07/16/2021] [Accepted: 08/16/2021] [Indexed: 11/20/2022]
Abstract
Intrathecal access in humans is a routine clinical intervention. However, intrathecal access is limited to drug delivery purposes in rodents, and intrathecal implantation is not a common surgical practice. Preclinically, we have successfully adopted different intrathecal implantation surgical methods for different implant materials in rodents. However, employing the appropriate intrathecal implantation method is a challenging process for surgeons, which includes several steps such as preoperative evaluations and postoperative care. The aim of this review is to define and compare the major documented surgical approaches applicable for intrathecal implantation in rodents along with the associated side effects, as well as highlighting the critical preoperative and postoperative considerations. Overall, this review will provide surgeons with the principles of intrathecal implantation approaches applicable for different implant materials.
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6
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Phuong TNT, Jang SH, Rijal S, Jung WK, Kim J, Park SJ, Han SK. GABA- and Glycine-Mimetic Responses of Linalool on the Substantia Gelatinosa of the Trigeminal Subnucleus Caudalis in Juvenile Mice: Pain Management through Linalool-Mediated Inhibitory Neurotransmission. THE AMERICAN JOURNAL OF CHINESE MEDICINE 2021; 49:1437-1448. [PMID: 34247560 DOI: 10.1142/s0192415x21500671] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Linalool, a major odorous constituent in essential oils extracted from lavender, is known to have a wide range of physiological effects on humans including pain management. The substantia gelatinosa (SG) of the trigeminal subnucleus caudalis (Vc) is involved in transmission of orofacial nociceptive responses through thin myelinated A[Formula: see text] and unmyelinated C primary afferent fibers. Up to date, the orofacial antinociceptive mechanism of linalool concerning SG neurons of the Vc has not been completely clarified yet. To fill this knowledge gap, whole-cell patch-clamp technique was used in this study to examine how linalool acted on SG neurons of the Vc in mice. Under a high chloride pipette solution, non-desensitizing and repeatable linalool-induced inward currents were preserved in the presence of tetrodotoxin (a voltage-gated Na[Formula: see text]channel blocker), CNQX (a non-NMDA glutamate receptor antagonist), and DL-AP5 (an NMDA receptor antagonist). However, linalool-induced inward currents were partially suppressed by picrotoxin (a GABA[Formula: see text] receptor antagonist) or strychnine (a glycine receptor antagonist). These responses were almost blocked in the presence of picrotoxin and strychnine. It was also found that linalool exhibited potentiation with GABA- and glycine-induced responses. Taken together, these data show that linalool has GABA- and glycine-mimetic effects, suggesting that it can be a promising target molecule for orofacial pain management by activating inhibitory neurotransmission in the SG area of the Vc.
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Affiliation(s)
- Thao Nguyen Thi Phuong
- Department of Oral Physiology, School of Dentistry & Institute of Oral Bioscience, Jeonbuk National University, Jeonju, Republic of Korea.,Faculty of Odonto-Stomatology, Hue University of Medicine and Pharmacy, Hue University, Hue, Vietnam
| | - Seon Hui Jang
- Department of Oral Physiology, School of Dentistry & Institute of Oral Bioscience, Jeonbuk National University, Jeonju, Republic of Korea
| | - Santosh Rijal
- Department of Oral Physiology, School of Dentistry & Institute of Oral Bioscience, Jeonbuk National University, Jeonju, Republic of Korea
| | - Woo Kwon Jung
- Department of Oral Pathology, School of Dentistry & Institute of Oral Bioscience, Jeonbuk National University, Jeonju, Republic of Korea
| | - Junghyun Kim
- Department of Oral Pathology, School of Dentistry & Institute of Oral Bioscience, Jeonbuk National University, Jeonju, Republic of Korea
| | - Soo Joung Park
- Department of Oral Physiology, School of Dentistry & Institute of Oral Bioscience, Jeonbuk National University, Jeonju, Republic of Korea
| | - Seong Kyu Han
- Department of Oral Physiology, School of Dentistry & Institute of Oral Bioscience, Jeonbuk National University, Jeonju, Republic of Korea
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7
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Alonso-Matielo H, Gonçalves ES, Campos M, Oliveira VRS, Toniolo EF, Alves AS, Lebrun I, de Andrade DC, Teixeira MJ, Britto LRG, Hamani C, Dale CS. Electrical stimulation of the posterior insula induces mechanical analgesia in a rodent model of neuropathic pain by modulating GABAergic signaling and activity in the pain circuitry. Brain Res 2021; 1754:147237. [PMID: 33400930 DOI: 10.1016/j.brainres.2020.147237] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Revised: 11/09/2020] [Accepted: 12/07/2020] [Indexed: 12/19/2022]
Abstract
The insula has emerged as a critical target for electrical stimulation since it influences pathological pain states. We investigated the effects of repetitive electrical stimulation of the insular cortex (ESI) on mechanical nociception, and general locomotor activity in rats subjected to chronic constriction injury (CCI) of the sciatic nerve. We also studied neuroplastic changes in central pain areas and the involvement of GABAergic signaling on ESI effects. CCI rats had electrodes implanted in the left agranular posterior insular cortex (pIC), and mechanical sensitivity was evaluated before and after one or five daily consecutive ESIs (15 min each, 60 Hz, 210 μs, 1 V). Five ESIs (repetitive ESI) induced sustained mechanical antinociception from the first to the last behavioral assessment without interfering with locomotor activity. A marked increase in Fos immunoreactivity in pIC and a decrease in the anterior and mid-cingulate cortex, periaqueductal gray and hippocampus were noticed after five ESIs. The intrathecal administration of the GABAA receptor antagonist bicuculline methiodide reversed the stimulation-induced antinociception after five ESIs. ESI increased GAD65 levels in pIC but did not interfere with GABA, glutamate or glycine levels. No changes in GFAP immunoreactivity were found in this work. Altogether, the results indicate the efficacy of repetitive ESI for the treatment of experimental neuropathic pain and suggest a potential influence of pIC in regulating pain pathways partially through modulating GABAergic signaling.
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Affiliation(s)
- Heloísa Alonso-Matielo
- Department of Anatomy, Institute of Biomedical Sciences of University of São Paulo - Av. Prof. Lineu Prestes, 2415, ICB-III, Cidade Universitária, 05508-900 São Paulo, SP, Brazil
| | - Elizamara S Gonçalves
- Department of Anatomy, Institute of Biomedical Sciences of University of São Paulo - Av. Prof. Lineu Prestes, 2415, ICB-III, Cidade Universitária, 05508-900 São Paulo, SP, Brazil
| | - Mariana Campos
- Department of Anatomy, Institute of Biomedical Sciences of University of São Paulo - Av. Prof. Lineu Prestes, 2415, ICB-III, Cidade Universitária, 05508-900 São Paulo, SP, Brazil
| | - Victória R S Oliveira
- Department of Anatomy, Institute of Biomedical Sciences of University of São Paulo - Av. Prof. Lineu Prestes, 2415, ICB-III, Cidade Universitária, 05508-900 São Paulo, SP, Brazil
| | - Elaine F Toniolo
- Center of Research in Neuroscience, Universidade Cidade de São Paulo, R. Cesário Galero, 448/475 - Tatuapé, São Paulo, SP 03071-000, Brazil
| | - Adilson S Alves
- Department of Physiology and Biophysics, Institute of Biomedical Sciences of University of São Paulo - Av. Prof. Lineu Prestes, 1524, ICB-I, Cidade Universitária, 05508-000 São Paulo, SP, Brazil
| | - Ivo Lebrun
- Laboratoryof Biochemistry and Biophysics, Institute Butantan, São Paulo, Brazil
| | - Daniel C de Andrade
- Department of Neurology, Central Institute, Av. Dr Enéas de Carvalho Aguiar, 255, 5(th) Floor, Room 5084, Cerqueira César, 05403-900 São Paulo, SP, Brazil; Instituto do Câncer Octavio Frias de Oliveira, University of São Paulo, Brazil
| | - Manoel J Teixeira
- Department of Neurology, Central Institute, Av. Dr Enéas de Carvalho Aguiar, 255, 5(th) Floor, Room 5084, Cerqueira César, 05403-900 São Paulo, SP, Brazil
| | - Luiz R G Britto
- Department of Physiology and Biophysics, Institute of Biomedical Sciences of University of São Paulo - Av. Prof. Lineu Prestes, 1524, ICB-I, Cidade Universitária, 05508-000 São Paulo, SP, Brazil
| | - Clement Hamani
- Harquail Centre for Neuromodulation, Sunnybrook Research Institute, University of Toronto, Toronto, ON M4N3M5, Canada
| | - Camila S Dale
- Department of Anatomy, Institute of Biomedical Sciences of University of São Paulo - Av. Prof. Lineu Prestes, 2415, ICB-III, Cidade Universitária, 05508-900 São Paulo, SP, Brazil; Department of Surgical Technique, Medical School, University of São Paulo, Av. Dr. Arnaldo, 455, 01246-903 São Paulo, SP, Brazil.
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8
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Uddin MS, Mamun AA, Rahman MA, Kabir MT, Alkahtani S, Alanazi IS, Perveen A, Ashraf GM, Bin-Jumah MN, Abdel-Daim MM. Exploring the Promise of Flavonoids to Combat Neuropathic Pain: From Molecular Mechanisms to Therapeutic Implications. Front Neurosci 2020; 14:478. [PMID: 32587501 PMCID: PMC7299068 DOI: 10.3389/fnins.2020.00478] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Accepted: 04/17/2020] [Indexed: 01/10/2023] Open
Abstract
Neuropathic pain (NP) is the result of irregular processing in the central or peripheral nervous system, which is generally caused by neuronal injury. The management of NP represents a great challenge owing to its heterogeneous profile and the significant undesirable side effects of the frequently prescribed psychoactive agents, including benzodiazepines (BDZ). Currently, several established drugs including antidepressants, anticonvulsants, topical lidocaine, and opioids are used to treat NP, but they exert a wide range of adverse effects. To reduce the burden of adverse effects, we need to investigate alternative therapeutics for the management of NP. Flavonoids are the most common secondary metabolites of plants used in folkloric medicine as tranquilizers, and have been claimed to have a selective affinity to the BDZ binding site. Several studies in animal models have reported that flavonoids can reduce NP. In this paper, we emphasize the potentiality of flavonoids for the management of NP.
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Affiliation(s)
- Md Sahab Uddin
- Department of Pharmacy, Southeast University, Dhaka, Bangladesh.,Pharmakon Neuroscience Research Network, Dhaka, Bangladesh
| | - Abdullah Al Mamun
- Department of Pharmacy, Southeast University, Dhaka, Bangladesh.,Pharmakon Neuroscience Research Network, Dhaka, Bangladesh
| | - Md Ataur Rahman
- Center for Neuroscience, Brain Science Institute, Korea Institute of Science and Technology, Seoul, South Korea
| | | | - Saad Alkahtani
- Department of Zoology, College of Science, King Saud University, Riyadh, Saudi Arabia
| | - Ibtesam S Alanazi
- Department of Biology, Faculty of Sciences, Univesity of Hafr Al Batin, Hafr Al Batin, Saudi Arabia
| | - Asma Perveen
- Glocal School of Life Sciences, Glocal University, Saharanpur, India
| | - Ghulam Md Ashraf
- King Fahd Medical Research Center, King Abdulaziz University, Jeddah, Saudi Arabia.,Department of Medical Laboratory Technology, Faculty of Applied Medical Sciences, King Abdulaziz University, Jeddah, Saudi Arabia
| | - May N Bin-Jumah
- Department of Biology, College of Science, Princess Nourah bint Abdulrahman University, Riyadh, Saudi Arabia
| | - Mohamed M Abdel-Daim
- Department of Zoology, College of Science, King Saud University, Riyadh, Saudi Arabia.,Pharmacology Department, Faculty of Veterinary Medicine, Suez Canal University, Ismailia, Egypt
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9
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Gradwell MA, Callister RJ, Graham BA. Reviewing the case for compromised spinal inhibition in neuropathic pain. J Neural Transm (Vienna) 2019; 127:481-503. [PMID: 31641856 DOI: 10.1007/s00702-019-02090-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2019] [Accepted: 09/30/2019] [Indexed: 12/20/2022]
Abstract
A striking and debilitating property of the nervous system is that damage to this tissue can cause chronic intractable pain, which persists long after resolution of the initial insult. This neuropathic form of pain can arise from trauma to peripheral nerves, the spinal cord, or brain. It can also result from neuropathies associated with disease states such as diabetes, human immunodeficiency virus/AIDS, herpes, multiple sclerosis, cancer, and chemotherapy. Regardless of the origin, treatments for neuropathic pain remain inadequate. This continues to drive research into the underlying mechanisms. While the literature shows that dysfunction in numerous loci throughout the CNS can contribute to chronic pain, the spinal cord and in particular inhibitory signalling in this region have remained major research areas. This review focuses on local spinal inhibition provided by dorsal horn interneurons, and how such inhibition is disrupted during the development and maintenance of neuropathic pain.
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Affiliation(s)
- M A Gradwell
- School of Biomedical Sciences and Pharmacy, Faculty of Health, University of Newcastle, Callaghan, NSW, 2308, Australia
- Hunter Medical Research Institute (HMRI), New Lambton Heights, NSW, Australia
| | - R J Callister
- School of Biomedical Sciences and Pharmacy, Faculty of Health, University of Newcastle, Callaghan, NSW, 2308, Australia
- Hunter Medical Research Institute (HMRI), New Lambton Heights, NSW, Australia
| | - B A Graham
- School of Biomedical Sciences and Pharmacy, Faculty of Health, University of Newcastle, Callaghan, NSW, 2308, Australia.
- Hunter Medical Research Institute (HMRI), New Lambton Heights, NSW, Australia.
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10
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Positive allosteric modulators of nonbenzodiazepine γ-aminobutyric acidA receptor subtypes for the treatment of chronic pain. Pain 2019; 160:198-209. [PMID: 30204648 DOI: 10.1097/j.pain.0000000000001392] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Chronic neuropathic pain may be caused, in part, by loss of inhibition in spinal pain processing pathways due to attenuation of local GABAergic tone. Nociception and nocifensive behaviors are reduced after enhancement of tonically activated extrasynaptic GABAAR-mediated currents by agonist ligands for δ subunit-containing GABAARs. However, typical ligands that target δ subunit-containing GABAARs are limited due to sedative effects at higher doses. We used the spinal nerve ligation (SNL) and gp120 models of experimental neuropathic pain to evaluate compound 2-261, a nonbenzodiazepine site positive allosteric modulator of α4β3δ GABAARs optimized to be nonsedative by selective activation of β2/3-subunit-containing GABAARs over receptor subtypes incorporating β1 subunits. Similar levels of 2-261 were detected in the brain and plasma after intraperitoneal administration. Although systemic 2-261 did not alter sensory thresholds in sham-operated animals, it significantly reversed SNL-induced thermal and tactile hypersensitivity in a GABAAR-dependent fashion. Intrathecal 2-261 produced conditioned place preference and elevated dopamine levels in the nucleus accumbens of nerve-injured, but not sham-operated, rats. In addition, systemic pretreatment with 2-261 blocked conditioned place preference from spinal clonidine in SNL rats. Moreover, 2-261 reversed thermal hyperalgesia and partially reversed tactile allodynia in the gp120 model of HIV-related neuropathic pain. The effects of 2-261 likely required interaction with the α4β3δ GABAAR because 2-301, a close structural analog of 2-261 with limited extrasynaptic receptor efficacy, was not active. Thus, 2-261 may produce pain relief with diminished side effects through selective modulation of β2/3-subunit-containing extrasynaptic GABAARs.
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11
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Gelsemine and koumine, principal active ingredients of Gelsemium, exhibit mechanical antiallodynia via spinal glycine receptor activation-induced allopregnanolone biosynthesis. Biochem Pharmacol 2019; 161:136-148. [PMID: 30668937 DOI: 10.1016/j.bcp.2019.01.014] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2018] [Accepted: 01/18/2019] [Indexed: 12/29/2022]
Abstract
Gelsemine, the principal active alkaloid from Gelsemium sempervirens Ait., and koumine, the most dominant alkaloids from Gelsemium elegans Benth., produced antinociception in a variety of rodent models of painful hypersensitivity. The present study explored the molecular mechanisms underlying gelsemine- and koumine-induced mechanical antiallodynia in neuropathic pain. The radioligand binding and displacement assays indicated that gelsemine and koumine, like glycine, were reversible and orthosteric agonists of glycine receptors with full efficacy and probably acted on same binding site as the glycine receptor antagonist strychnine. Treatment with gelsemine, koumine and glycine in primary cultures of spinal neurons (but not microglia or astrocytes) concentration dependently increased 3α-hydroxysteroid oxidoreductase (3α-HSOR) mRNA expression, which was inhibited by pretreatment with strychnine but not the glial inhibitor minocycline. Intrathecal injection of gelsemine, koumine and glycine stimulated 3α-HSOR mRNA expression in the spinal cords of neuropathic rats and produced mechanical antiallodynia. Their spinal mechanical antiallodynia was completely blocked by strychnine, the selective 3α-HSOR inhibitor medroxyprogesterone acetate (MPA), 3α-HSOR gene silencer siRNA/3α-HSOR and specific GABAA receptor antagonist isoallopregnanolone, but not minocycline. All the results taken together uncovered that gelsemine and koumine are orthosteric agonists of glycine receptors, and produce mechanical antiallodynia through neuronal glycine receptor/3α-HSOR/allopregnanolone/GABAA receptor pathway.
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Vale N, Ferreira A, Matos J, Fresco P, Gouveia MJ. Amino Acids in the Development of Prodrugs. Molecules 2018; 23:E2318. [PMID: 30208629 PMCID: PMC6225300 DOI: 10.3390/molecules23092318] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Revised: 08/30/2018] [Accepted: 09/06/2018] [Indexed: 01/03/2023] Open
Abstract
Although drugs currently used for the various types of diseases (e.g., antiparasitic, antiviral, antibacterial, etc.) are effective, they present several undesirable pharmacological and pharmaceutical properties. Most of the drugs have low bioavailability, lack of sensitivity, and do not target only the damaged cells, thus also affecting normal cells. Moreover, there is the risk of developing resistance against drugs upon chronic treatment. Consequently, their potential clinical applications might be limited and therefore, it is mandatory to find strategies that improve those properties of therapeutic agents. The development of prodrugs using amino acids as moieties has resulted in improvements in several properties, namely increased bioavailability, decreased toxicity of the parent drug, accurate delivery to target tissues or organs, and prevention of fast metabolism. Herein, we provide an overview of models currently in use of prodrug design with amino acids. Furthermore, we review the challenges related to the permeability of poorly absorbed drugs and transport and deliver on target organs.
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Affiliation(s)
- Nuno Vale
- Laboratory of Pharmacology, Department of Drug Sciences, Faculty of Pharmacy, University of Porto, Rua de Jorge Viterbo Ferreira 228, 4050-313 Porto, Portugal.
- Institute of Molecular Pathology and Immunology of the University of Porto (IPATIMUP), Rua Júlio Amaral de Carvalho, 45, 4200-135 Porto, Portugal.
- Instituto de Investigação e Inovação em Saúde (i3S), University of Porto, Rua Alfredo Allen, 208, 4200-135 Porto, Portugal.
- Department of Molecular Pathology and Immunology, Institute of Biomedical Sciences Abel Salazar (ICBAS), University of Porto, Rua de Jorge Viterbo Ferreira 228, 4050-313 Porto, Portugal.
| | - Abigail Ferreira
- Laboratory of Pharmacology, Department of Drug Sciences, Faculty of Pharmacy, University of Porto, Rua de Jorge Viterbo Ferreira 228, 4050-313 Porto, Portugal.
- LAQV&REQUIMTE, Laboratory of Applied Chemistry, Department of Chemical Sciences, Faculty of Pharmacy, University of Porto, Rua de Jorge Viterbo Ferreira 228, 4050-313 Porto, Portugal.
| | - Joana Matos
- SpiroChem AG, Rosental Area, WRO-1074-3, Mattenstrasse 24, 4058 Basel, Switzerland.
| | - Paula Fresco
- Laboratory of Pharmacology, Department of Drug Sciences, Faculty of Pharmacy, University of Porto, Rua de Jorge Viterbo Ferreira 228, 4050-313 Porto, Portugal.
| | - Maria João Gouveia
- Instituto de Investigação e Inovação em Saúde (i3S), University of Porto, Rua Alfredo Allen, 208, 4200-135 Porto, Portugal.
- Department of Molecular Pathology and Immunology, Institute of Biomedical Sciences Abel Salazar (ICBAS), University of Porto, Rua de Jorge Viterbo Ferreira 228, 4050-313 Porto, Portugal.
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Peripheral GABA A receptor-mediated signaling facilitates persistent inflammatory hypersensitivity. Neuropharmacology 2018; 135:572-580. [PMID: 29634983 DOI: 10.1016/j.neuropharm.2018.04.009] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2017] [Revised: 03/30/2018] [Accepted: 04/06/2018] [Indexed: 01/26/2023]
Abstract
Unlike in the central nervous system (CNS), in the adult peripheral nervous system (PNS), activation of GABAA receptors (GABAAR) is excitatory because of the relatively high concentration of intracellular chloride in these neurons. Indeed, exogenous GABA and muscimol, a GABAAR agonist, exacerbate acute inflammatory hypersensitivity in rodents. However, it remains unclear whether peripheral GABAAR and the endogenous GABA play an important role in persistent inflammatory hypersensitivity. In this study, we thus investigated how peripheral GABAAR affects pain hypersensitivity by using the complete Freund's adjuvant (CFA)-induced persistent inflammatory pain mouse model. We found that intraplantar (i.pl.) administration of GABAAR antagonists, picrotoxin, and 1(S),9(R)-(-)-bicuculline methiodide significantly inhibited both spontaneous nociceptive (paw licking and flinching) behavior and mechanical hypersensitivity in CFA-injected mice at day 3 (D3), but not in naïve mice. Interestingly, CFA-induced mechanical hypersensitivity was significantly reversed by anti-GABA antibody (anti-GABA, i.pl.). In addition, RT-qPCR revealed that glutamate decarboxylase Gad1 (GAD 67) and Gad2 (GAD 65) mRNA expression was also upregulated in the ipsilateral hind paw of CFA-injected mice at D3. Finally, 5α-pregnan-3α-ol-20-one (3α,5α-THP), a selective positive allosteric modulator of GABAAR, produced mechanical hypersensitivity in naïve mice in a dose-dependent manner. Taken together, our results indicate that peripheral GABAAR and endogenous GABA, possibly produced by the inflamed tissue, potentiate CFA-induced persistent inflammatory hypersensitivity, suggesting that they can be used as a therapeutic target for alleviating inflammatory pain.
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François A, Low SA, Sypek EI, Christensen AJ, Sotoudeh C, Beier KT, Ramakrishnan C, Ritola KD, Sharif-Naeini R, Deisseroth K, Delp SL, Malenka RC, Luo L, Hantman AW, Scherrer G. A Brainstem-Spinal Cord Inhibitory Circuit for Mechanical Pain Modulation by GABA and Enkephalins. Neuron 2017; 93:822-839.e6. [PMID: 28162807 DOI: 10.1016/j.neuron.2017.01.008] [Citation(s) in RCA: 213] [Impact Index Per Article: 30.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2016] [Revised: 11/22/2016] [Accepted: 01/06/2017] [Indexed: 10/20/2022]
Abstract
Pain thresholds are, in part, set as a function of emotional and internal states by descending modulation of nociceptive transmission in the spinal cord. Neurons of the rostral ventromedial medulla (RVM) are thought to critically contribute to this process; however, the neural circuits and synaptic mechanisms by which distinct populations of RVM neurons facilitate or diminish pain remain elusive. Here we used in vivo opto/chemogenetic manipulations and trans-synaptic tracing of genetically identified dorsal horn and RVM neurons to uncover an RVM-spinal cord-primary afferent circuit controlling pain thresholds. Unexpectedly, we found that RVM GABAergic neurons facilitate mechanical pain by inhibiting dorsal horn enkephalinergic/GABAergic interneurons. We further demonstrate that these interneurons gate sensory inputs and control pain through temporally coordinated enkephalin- and GABA-mediated presynaptic inhibition of somatosensory neurons. Our results uncover a descending disynaptic inhibitory circuit that facilitates mechanical pain, is engaged during stress, and could be targeted to establish higher pain thresholds. VIDEO ABSTRACT.
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Affiliation(s)
- Amaury François
- Department of Anesthesiology, Perioperative and Pain Medicine, Department of Molecular and Cellular Physiology, Department of Neurosurgery, Stanford Neurosciences Institute, Stanford University, Stanford, CA 94305, USA
| | - Sarah A Low
- Department of Anesthesiology, Perioperative and Pain Medicine, Department of Molecular and Cellular Physiology, Department of Neurosurgery, Stanford Neurosciences Institute, Stanford University, Stanford, CA 94305, USA
| | - Elizabeth I Sypek
- Department of Anesthesiology, Perioperative and Pain Medicine, Department of Molecular and Cellular Physiology, Department of Neurosurgery, Stanford Neurosciences Institute, Stanford University, Stanford, CA 94305, USA
| | - Amelia J Christensen
- Department of Electrical Engineering, Stanford University, Stanford, CA 94305, USA
| | - Chaudy Sotoudeh
- Department of Anesthesiology, Perioperative and Pain Medicine, Department of Molecular and Cellular Physiology, Department of Neurosurgery, Stanford Neurosciences Institute, Stanford University, Stanford, CA 94305, USA
| | - Kevin T Beier
- Howard Hughes Medical Institute, Department of Biology, Stanford University, Stanford, CA 94305, USA; Nancy Pritzker Laboratory, Department of Psychiatry and Behavioral Sciences, Stanford University, Stanford, CA 94305, USA
| | - Charu Ramakrishnan
- Department of Bioengineering, Stanford University, Stanford, CA 94305, USA
| | - Kimberly D Ritola
- Virus Services, Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Reza Sharif-Naeini
- Department of Physiology and Cell Information Systems Group, McGill University, Montreal, H3G0B1 QC, Canada
| | - Karl Deisseroth
- Howard Hughes Medical Institute, Department of Bioengineering, Department of Psychiatry, CNC Program, Stanford University, Stanford, CA 94305, USA
| | - Scott L Delp
- Department of Bioengineering, Department of Mechanical Engineering, Stanford University, Stanford, CA 94305, USA
| | - Robert C Malenka
- Nancy Pritzker Laboratory, Department of Psychiatry and Behavioral Sciences, Stanford University, Stanford, CA 94305, USA
| | - Liqun Luo
- Howard Hughes Medical Institute, Department of Biology, Stanford University, Stanford, CA 94305, USA
| | - Adam W Hantman
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Grégory Scherrer
- Department of Anesthesiology, Perioperative and Pain Medicine, Department of Molecular and Cellular Physiology, Department of Neurosurgery, Stanford Neurosciences Institute, Stanford University, Stanford, CA 94305, USA.
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Abstract
It has been recently proposed that α5-subunit containing GABAA receptors (α5-GABAA receptors) that mediate tonic inhibition might be involved in pain. The purpose of this study was to investigate the contribution of α5-GABAA receptors in the loss of GABAergic inhibition and in formalin-induced, complete Freund's adjuvant (CFA)-induced and L5 and L6 spinal nerve ligation-induced long-lasting hypersensitivity. Formalin or CFA injection and L5 and L6 spinal nerve ligation produced long-lasting allodynia and hyperalgesia. Moreover, formalin injection impaired the rate-dependent depression of the Hofmann reflex. Peripheral and intrathecal pretreatment or post-treatment with the α5-GABAA receptor antagonist, L-655,708 (0.15-15 nmol), prevented and reversed, respectively, these long-lasting behaviors. Formalin injection increased α5-GABAA receptor mRNA expression in the spinal cord and dorsal root ganglia (DRG) mainly at 3 days. The α5-GABAA receptors were localized in the dorsal spinal cord and DRG colabeling with NeuN, CGRP, and IB4 which suggests their presence in peptidergic and nonpeptidergic neurons. These receptors were found mainly in small and medium sized neurons. Formalin injection enhanced α5-GABAA receptor fluorescence intensity in spinal cord and DRG at 3 and 6 days. Intrathecal administration of L-655,708 (15 nmol) prevented and reversed formalin-induced impairment of rate-dependent depression. These results suggest that α5-GABAA receptors play a role in the loss of GABAergic inhibition and contribute to long-lasting secondary allodynia and hyperalgesia.
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Li L, Chen SR, Chen H, Wen L, Hittelman WN, Xie JD, Pan HL. Chloride Homeostasis Critically Regulates Synaptic NMDA Receptor Activity in Neuropathic Pain. Cell Rep 2016; 15:1376-1383. [PMID: 27160909 PMCID: PMC4871741 DOI: 10.1016/j.celrep.2016.04.039] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2015] [Revised: 02/07/2016] [Accepted: 04/05/2016] [Indexed: 12/31/2022] Open
Abstract
Chronic neuropathic pain is a debilitating condition that remains difficult to treat. Diminished synaptic inhibition by GABA and glycine and increased NMDA receptor (NMDAR) activity in the spinal dorsal horn are key mechanisms underlying neuropathic pain. However, the reciprocal relationship between synaptic inhibition and excitation in neuropathic pain is unclear. Here, we show that intrathecal delivery of K(+)-Cl(-) cotransporter-2 (KCC2) using lentiviral vectors produces a complete and long-lasting reversal of pain hypersensitivity induced by nerve injury. KCC2 gene transfer restores Cl(-) homeostasis disrupted by nerve injury in both spinal dorsal horn and primary sensory neurons. Remarkably, restoring Cl(-) homeostasis normalizes both presynaptic and postsynaptic NMDAR activity increased by nerve injury in the spinal dorsal horn. Our findings indicate that nerve injury recruits NMDAR-mediated signaling pathways through the disruption of Cl(-) homeostasis in spinal dorsal horn and primary sensory neurons. Lentiviral vector-mediated KCC2 expression is a promising gene therapy for the treatment of neuropathic pain.
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Affiliation(s)
- 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
| | - Lei Wen
- Center for Neuroscience and Pain Research, Department of Anesthesiology and Perioperative Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Walter N Hittelman
- Department of Experimental Therapeutics, 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
| | - 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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17
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Guo D, Hu J. Spinal presynaptic inhibition in pain control. Neuroscience 2014; 283:95-106. [PMID: 25255936 DOI: 10.1016/j.neuroscience.2014.09.032] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Revised: 09/10/2014] [Accepted: 09/14/2014] [Indexed: 12/22/2022]
Abstract
The gate control theory proposed that the nociceptive sensory information transmitted to the brain relies on an interplay between the inputs from nociceptive and non-nociceptive primary afferent fibers. Both inputs are normally under strong inhibitory control in the spinal cord. Under healthy conditions, presynaptic inhibition activated by non-nociceptive fibers modulates the afferent input from nociceptive fibers onto spinal cord neurons, while postsynaptic inhibition controls the excitability of dorsal horn neurons, and silences the non-nociceptive information flow to nociceptive-specific (NS) projection neurons. However, under pathological conditions, this spinal inhibition may be altered and lead to chronic pain. This review summarizes our knowledge of presynaptic inhibition in pain control, with particular focus on how its alteration after nerve or tissue injury contributes to neuropathic or inflammatory pain syndromes, respectively.
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Affiliation(s)
- D Guo
- Centre for Integrative Neuroscience (CIN), Otfried-Mueller-Straße 25, 72076 Tuebingen, Germany
| | - J Hu
- Centre for Integrative Neuroscience (CIN), Otfried-Mueller-Straße 25, 72076 Tuebingen, Germany.
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18
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Drinovac V, Bach-Rojecky L, Lacković Z. Association of antinociceptive action of botulinum toxin type A with GABA-A receptor. J Neural Transm (Vienna) 2014; 121:665-9. [DOI: 10.1007/s00702-013-1150-6] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2013] [Accepted: 12/20/2013] [Indexed: 01/31/2023]
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19
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Bonin RP, De Koninck Y. Restoring ionotropic inhibition as an analgesic strategy. Neurosci Lett 2013; 557 Pt A:43-51. [PMID: 24080373 DOI: 10.1016/j.neulet.2013.09.047] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2013] [Revised: 09/11/2013] [Accepted: 09/16/2013] [Indexed: 12/31/2022]
Abstract
Neuronal inhibition in nociceptive relays of the spinal cord is essential for the proper processing of nociceptive information. In the spinal cord dorsal horn, the activity of synaptic and extrasynaptic GABAA and glycine receptors generates rapid, Cl(-)-dependent neuronal inhibition. A loss of this ionotropic inhibition, particularly through the collapse of the inhibitory Cl(-)-gradient, is a key mechanism by which pathological pain conditions develop. This review summarizes the roles of ionotropic inhibition in the regulation of nociception, and explores recent evidence that the potentiation of GABAA or glycine receptor activity or the enhancement of inhibitory drive can reverse pathological pain.
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Affiliation(s)
- Robert P Bonin
- Unité de neurosciences cellulaires et moléculaire, Centre de recherche de l'institut universitaire en santé mentale de Québec, Québec, Canada
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Gelsemine, a principal alkaloid from Gelsemium sempervirens Ait., exhibits potent and specific antinociception in chronic pain by acting at spinal α3 glycine receptors. Pain 2013; 154:2452-2462. [PMID: 23886522 DOI: 10.1016/j.pain.2013.07.027] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2013] [Revised: 07/14/2013] [Accepted: 07/17/2013] [Indexed: 11/22/2022]
Abstract
The present study examined the antinociceptive effects of gelsemine, the principal alkaloid in Gelsemium sempervirens Ait. A single intrathecal injection of gelsemine produced potent and specific antinociception in formalin-induced tonic pain, bone cancer-induced mechanical allodynia, and spinal nerve ligation-induced painful neuropathy. The antinociception was dose-dependent, with maximal inhibition of 50% to 60% and ED50 values of 0.5 to 0.6 μg. Multiple daily intrathecal injections of gelsemine for 7 days induced no tolerance to antinociception in the rat model of bone cancer pain. Spinal gelsemine was not effective in altering contralateral paw withdrawal thresholds, and had only a slight inhibitory effect on formalin-induced acute nociception. The specific antinociception of gelsemine in chronic pain was blocked dose-dependently by the glycine receptor (GlyR) antagonist strychnine with an apparent ID50 value of 3.8 μg. Gelsemine concentration-dependently displaced H(3)-strychnine binding to the membrane fraction of rat spinal cord homogenates, with a 100% displacement and a Ki of 21.9μM. Gene ablation of the GlyR α3 subunit (α3 GlyR) but not α1 GlyR, by a 7-day intrathecal injection of small interfering RNA (siRNA) targeting α3 GlyR or α1 GlyR, nearly completely prevented gelsemine-induced antinociception in neuropathic pain. Our results demonstrate that gelsemine produces potent and specific antinociception in chronic pain states without induction of apparent tolerance. The results also suggest that gelsemine produces antinociception by activation of spinal α3 glycine receptors, and support the notion that spinal α3 glycine receptors are a potential therapeutic target molecule for the management of chronic pain.
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21
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Beyer C, Komisaruk B, González-Flores O, Gómora-Arrati P. Glycinamide, a glycine pro-drug, induces antinociception by intraperitoneal or oral ingestion in ovariectomized rats. Life Sci 2013; 92:576-81. [DOI: 10.1016/j.lfs.2013.01.022] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2012] [Revised: 01/11/2013] [Accepted: 01/15/2013] [Indexed: 01/13/2023]
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Kumru H, Kofler M, Flores MC, Portell E, Robles V, Leon N, Vidal J. Effect of intrathecal baclofen on evoked pain perception: an evoked potentials and quantitative thermal testing study. Eur J Pain 2012; 17:1039-47. [PMID: 23239275 DOI: 10.1002/j.1532-2149.2012.00266.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/14/2012] [Indexed: 11/06/2022]
Abstract
BACKGROUND AND OBJECTIVES Somatic antinociceptive effects of baclofen have been demonstrated in animal models. We hypothesized that if enhanced thermal or pain sensitivity is produced by loss of gamma-aminobutyric acid (GABA)-ergic tone in the central nervous system, spinal administration of GABA agonists might be predicted to be effective in thermal and/or pain perception changes and pain-related evoked potentials in candidates for intrathecal baclofen (ITB) treatment. METHODS Eleven patients with severe spinal cord injury (SCI) who suffered from severe spasticity were evaluated during a 50-μg ITB bolus test. Warm and heat pain thresholds, evoked heat pain perception, and contact heat-evoked potentials (CHEPs) were determined above SCI level from the right and left sides. Nine age- and gender-matched healthy volunteers undergoing repeat testing without any placebo injection served as control group. RESULT In patients, heat pain perception threshold increased, and evoked pain perception and amplitude of CHEPs decreased significantly after ITB bolus application in comparison with baseline (p < 0.005), with no change in warm perception threshold. In controls, no significant changes were observed in repeat testing over time. CONCLUSION Our findings indicate that ITB modulates heat pain perception threshold, evoked heat pain perception and heat pain-related evoked potentials without inducing warm perception threshold changes in SCI patients. This phenomenon should be taken into account in the clinical evaluation and management of pain in patients receiving baclofen.
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Affiliation(s)
- H Kumru
- Institut Guttmann, Institut Universitari de Neurorehabilitació adscrit a la UAB, Barcelona, Spain.
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23
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Leiphart JW, Dills CV, Levy RM. The analgesic effects of intrathecally pumped saline and artificial cerebrospinal fluid in a rat model of neuropathic pain. Neuromodulation 2012; 5:214-20. [PMID: 22150849 DOI: 10.1046/j.1525-1403.2002.02032.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Objective. This experiment was performed to test the hypothesis that intrathecally pumped saline, but not artificial cerebrospinal fluid (CSF), would be analgesic in a rat model of neuropathic pain. Materials and Methods. Surgery for the chronic constriction injury (CCI) model of neuropathic pain and intrathecal catheter placement were performed on the rats, baseline pain testing and pump implantation were performed 7 days later, and pain tests were repeated on days 1, 4, 7, and 14 after pump implantation. Results. Intrathecally pumped saline and artificial CSF were analgesic for cold allodynia (p < 0.05), and intrathecally pumped saline but not CSF for heat nociception in the affected paw (p < 0.005) compared to rats with unattached subcutaneous pumps. No analgesia was observed on tests of spontaneous pain or pressure hyperalgesia (p > 0.1). Conclusions. Intrathecally pumped saline and artificial CSF have analgesic effects on some neuropathic and normal, nociceptive pain signs in CCI rats.
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Affiliation(s)
- James W Leiphart
- Division of Neurosurgery, University of California at Los Angeles, Los Angeles, California and Departments of Neurosurgery, Physiology, and Institute for Neuroscience, Northwestern University, Chicago, Illinois
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Zhu Y, Dua S, Gold MS. Inflammation-induced shift in spinal GABA(A) signaling is associated with a tyrosine kinase-dependent increase in GABA(A) current density in nociceptive afferents. J Neurophysiol 2012; 108:2581-93. [PMID: 22914654 DOI: 10.1152/jn.00590.2012] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
To account for benzodiazepine-induced spinal analgesia observed in association with an inflammation-induced shift in the influence of the GABA(A) receptor antagonist gabazine on nociceptive threshold, the present study was designed to determine whether persistent inflammation is associated with the upregulation of high-affinity GABA(A) receptors in primary afferents. The cell bodies of afferents innervating the glabrous skin of the rat hind paw were retrogradely labeled, acutely dissociated, and studied before and after the induction of persistent inflammation. A time-dependent increase in GABA(A) current density was observed that was more than twofold by 72 h after the initiation of inflammation. This increase in current density included both high- and low-affinity currents and was restricted to neurons in which GABA increased intracellular Ca(2+). No increases in GABA(A) receptor subunit mRNA or protein were detected in whole ganglia. In contrast, the increased current density was completely reversed by 20-min preincubation with the tyrosine kinase inhibitor genistein and partially reversed with the Src kinase inhibitor PP2. Genistein reversal was partially blocked by the dynamin inhibitor peptide P4. Changes in nociceptive threshold following spinal administration of genistein and muscimol to inflamed rats indicated that the pronociceptive actions of muscimol observed in the presence of inflammation were reversed by genistein. These results suggest that persistent changes in relative levels of tyrosine kinase activity following inflammation provide not only a sensitive way to dynamically regulate spinal nociceptive signaling but a viable target for the development of novel therapeutic interventions for the treatment of inflammatory pain.
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Affiliation(s)
- Yi Zhu
- Department of Neural and Pain Sciences, University of Maryland, Baltimore School of Dentistry, Baltimore, Maryland, USA
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25
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Eaton MJ, Berrocal Y, Wolfe SQ. Potential for Cell-Transplant Therapy with Human Neuronal Precursors to Treat Neuropathic Pain in Models of PNS and CNS Injury: Comparison of hNT2.17 and hNT2.19 Cell Lines. PAIN RESEARCH AND TREATMENT 2012; 2012:356412. [PMID: 22619713 PMCID: PMC3348681 DOI: 10.1155/2012/356412] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/14/2011] [Accepted: 01/15/2012] [Indexed: 01/07/2023]
Abstract
Effective treatment of sensory neuropathies in peripheral neuropathies and spinal cord injury (SCI) is one of the most difficult problems in modern clinical practice. Cell therapy to release antinociceptive agents near the injured spinal cord is a logical next step in the development of treatment modalities. But few clinical trials, especially for chronic pain, have tested the potential of transplant of cells to treat chronic pain. Cell lines derived from the human neuronal NT2 cell line parentage, the hNT2.17 and hNT2.19 lines, which synthesize and release the neurotransmitters gamma-aminobutyric acid (GABA) and serotonin (5HT), respectively, have been used to evaluate the potential of cell-based release of antinociceptive agents near the lumbar dorsal (horn) spinal sensory cell centers to relieve neuropathic pain after PNS (partial nerve and diabetes-related injury) and CNS (spinal cord injury) damage in rat models. Both cell lines transplants potently and permanently reverse behavioral hypersensitivity without inducing tumors or other complications after grafting. Functioning as cellular minipumps for antinociception, human neuronal precursors, like these NT2-derived cell lines, would likely provide a useful adjuvant or replacement for current pharmacological treatments for neuropathic pain.
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Affiliation(s)
- Mary J. Eaton
- Miami VA Health System Center, D806C, 1201 NW 16th Street, Miami, FL 33199, USA
| | - Yerko Berrocal
- Department of Cellular Biology and Pharmacology, Herbert Wertheim College of Medicine, Florida International University, Miami, FL, USA
| | - Stacey Q. Wolfe
- Department of Neurosurgery, Tripler Army Medical Center, 1 Jarrett White Road, Honolulu, HI 96859-5000, USA
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Shortland P, Kinman E, Molander C. Sprouting of A-fibre primary afferents into lamina II in two rat models of neuropathic pain. Eur J Pain 2012; 1:215-27. [PMID: 15102403 DOI: 10.1016/s1090-3801(97)90107-5] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/1997] [Accepted: 08/20/1997] [Indexed: 10/26/2022]
Abstract
Following peripheral nerve section, injured sensory A-fibres into lamina II of the dorsal horn and form aberrant functional synapses. Such structural changes may underlie some of the sensory abnormalities observed in nerve-injured patients, including neuropathic pain. This study compared the ability of intact and injured A-fibres to sprout in two experimental models of neuropathic pain, where the onset and presence of abnormal behaviours indicative of neuropathic pain have been well described. Rats received either a unilateral chronic constriction injury of the sciatic nerve (CCI) or lesion of the L5 spinal nerve (SNL). The central distribution of the injured and uninjured afferents labelled with choleragenoid conjugated to horseradish peroxidase (B-HRP) was examined at different postoperative survival times. In both models, the contralateral uninjured side, used for control nerve or ganglion injections, showed labelling of the L3-6 spinal segments in laminae I, III-V, leaving lamina II unlabelled. In CCI rats, injured sciatic afferents sprouted in lamina II of the L4-5 dorsal horn by 10 days postinjury. In SNL rats, injured L5 afferents sprouted into lamina II of the L4-5 dorsal horn by 24 h postinjury and were robust from 3 to 10 days. In both models, the labelling in lamina II was absent by 4 months. Labelling of the adjacent uninjured saphenous or intact L4 spinal nerve afferents did not reveal A-fibre sprouting. As the time-course of sprouting of injured A-fibres parallels the previously described behaviour interpreted as neuropathic pain in these models, this may be a phenomenon that contributes to sensory abnormalities such as ongoing pain and mechanical hypersensitivity.
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Affiliation(s)
- P Shortland
- Department of Neuroscience, Division of Neuroanatomy and Neuronal Plasticity, Karolinska Institutet, Stockholm, Sweden
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Lee IO, Son JK, Lim ES, Kim YS. Pharmacology of intracisternal or intrathecal glycine, muscimol, and baclofen in strychnine-induced thermal hyperalgesia of mice. J Korean Med Sci 2011; 26:1371-7. [PMID: 22022192 PMCID: PMC3192351 DOI: 10.3346/jkms.2011.26.10.1371] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/26/2011] [Accepted: 08/10/2011] [Indexed: 11/30/2022] Open
Abstract
Glycine and γ-aminobutyric acid (GABA) are localized and released by the same interneurons in the spinal cord. Although the effects of glycine and GABA on analgesia are well known, little is known about the effect of GABA in strychnine-induced hyperalgesia. To investigate the effect of GABA and the role of the glycine receptor in thermal hyperalgesia, we designed an experiment involving the injection of muscimol (a GABA(A) receptor agonist), baclofen (a GABA(B) receptor agonist) or glycine with strychnine (strychnine sensitive glycine receptor antagonist). Glycine, muscimol, or baclofen with strychnine was injected into the cisterna magna or lumbar subarachnoidal spaces of mice. The effects of treatment on strychnine-induced heat hyperalgesia were observed using the pain threshold index via the hot plate test. The dosages of experimental drugs and strychnine we chose had no effects on motor behavior in conscious mice. Intracisternal or intrathecal administration of strychnine produced thermal hyperalgesia in mice. Glycine antagonize the effects of strychnine, whereas, muscimol or baclofen does not. Our results indicate that glycine has anti-thermal hyperalgesic properties in vivo; and GABA receptor agonists may lack the binding abilities of glycine receptor antagonists with their sites in the central nervous system.
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Affiliation(s)
- Il Ok Lee
- Department of Anesthesiology and Pain Medicine, College of Medicine, Korea University, Seoul, Korea.
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Sarkis R, Saadé N, Atweh S, Jabbur S, Al-Amin H. Chronic dizocilpine or apomorphine and development of neuropathy in two rat models I: behavioral effects and role of nucleus accumbens. Exp Neurol 2010; 228:19-29. [PMID: 21146525 DOI: 10.1016/j.expneurol.2010.12.004] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2010] [Revised: 12/02/2010] [Accepted: 12/03/2010] [Indexed: 01/10/2023]
Abstract
Dopaminergic and glutamatergic inputs converge on nucleus accumbens (NAC) and affect the neuropathic pain. We tested the effects of daily systemic administration of dizocilpine (MK-801), a N-methyl-d-Aspartate (NMDA) noncompetitive receptor antagonist, or apomorphine (APO), a dopamine (DA) D1 and D2 receptor agonist, on neuropathic manifestations in the chronic constriction injury (CCI) and the spared nerve injury (SNI) models of mononeuropathy in rats. Six groups of rats were subjected to CCI or SNI neuropathy and 5-7 days later received daily intraperitoneal (ip) injections of saline, MK-801, or APO for two weeks. Tests for nociception and motor behaviors were performed at regular intervals. Tactile and cold allodynia were assessed using von Frey hairs or acetone drops, respectively. Heat hyperalgesia was assessed by the paw withdrawal test. Tests were performed before administering the daily injections. Another four groups of rats were subjected to SNI surgery, and then had their NAC (contralateral to the lesioned paw) perfused for two weeks with MK-801, saline, APO+ascorbic acid, or ascorbic acid alone using mini-osmotic pumps. Behavioral manifestations were assessed as above. Systemic daily injections of MK-801 and APO markedly attenuated the neuropathic manifestations in the CCI and SNI models with a minimal effect on cold allodynia. The same results were seen in the SNI model with chronic perfusion of NAC. Our results suggest that daily systemic administration of DA agonists and NMDA antagonists can attenuate neuropathic pain manifestations and that the NAC is involved in the modulation of neuropathic-like behaviors.
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Affiliation(s)
- Rani Sarkis
- Department of Physiology, Faculty of Medicine, American University of Beirut, Beirut, Lebanon
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Lee IO, Lim ES. Intracisternal or intrathecal glycine, taurine, or muscimol inhibit bicuculline-induced allodynia and thermal hyperalgesia in mice. Acta Pharmacol Sin 2010; 31:907-14. [PMID: 20686515 DOI: 10.1038/aps.2010.82] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
AIM To investigate the effects of GABA and glycine on analgesia in the central nervous system. METHODS Glycine, taurine, or muscimol was injected with bicuculline into the cistern magna or the lumbar subarachnoidal space in ICR mice. The effects on bicuculline-induced allodynia in a touch-evoked agitation test and on pain threshold index in a hot-plate test were assessed. RESULTS The dosages of the amino acids administered with bicuculline had no effect on motor behavior in conscious mice. Glycine or muscimol reduced bicuculline-induced allodynia regardless of the administration site, whereas intrathecal taurine reduced bicuculline-induced allodynia. Glycine, taurine, and muscimol all antagonized the effects induced by bicuculline in the hot-plate test, regardless of the administration site. CONCLUSION Glycine, taurine, and muscimol were found to have anti-allodynic and anti-thermal hyperalgesic properties in vivo. These observations suggest an interaction between glycine and GABA receptors during the regulation of antinociception.
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Brusberg M, Ravnefjord A, Martinsson R, Larsson H, Martinez V, Lindström E. The GABAB receptor agonist, baclofen, and the positive allosteric modulator, CGP7930, inhibit visceral pain-related responses to colorectal distension in rats. Neuropharmacology 2009; 56:362-7. [DOI: 10.1016/j.neuropharm.2008.09.006] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2008] [Revised: 07/23/2008] [Accepted: 09/09/2008] [Indexed: 10/21/2022]
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Jolivalt CG, Lee CA, Ramos KM, Calcutt NA. Allodynia and hyperalgesia in diabetic rats are mediated by GABA and depletion of spinal potassium-chloride co-transporters. Pain 2008; 140:48-57. [PMID: 18755547 PMCID: PMC2593464 DOI: 10.1016/j.pain.2008.07.005] [Citation(s) in RCA: 111] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2008] [Revised: 06/10/2008] [Accepted: 07/07/2008] [Indexed: 02/02/2023]
Abstract
Diabetic rats show behavioral indices of painful neuropathy that may model the human condition. Hyperalgesia during the formalin test in diabetic rats is accompanied by the apparently paradoxical decrease in spinal release of excitatory neurotransmitters and increase in the inhibitory neurotransmitter GABA. Decreased expression of the potassium-chloride co-transporter, KCC2, in the spinal cord promotes excitatory properties of GABA. We therefore measured spinal KCC2 expression and explored the role of the GABA(A) receptor in rats with painful diabetic neuropathy. KCC2 protein levels were significantly reduced in the spinal cord of diabetic rats, while levels of NKCC1 and the GABA(A) receptor were unchanged. Spinal delivery of the GABA(A) receptor antagonist bicuculline reduced formalin-evoked flinching in diabetic rats and also dose-dependently alleviated tactile allodynia. GABA(A) receptor-mediated rate-dependent depression of the spinal H reflex was absent in the spinal cord of diabetic rats. Control rats treated with the KCC2 blocker DIOA, mimicked diabetes by showing increased formalin-evoked flinching and diminished rate- dependent depression. The ability of bicuculline to alleviate allodynia and formalin-evoked hyperalgesia in diabetic rats is consistent with a reversal of the properties of GABA predicted by reduced spinal KCC2 and suggests that reduced KCC2 expression and increased GABA release contribute to spinally mediated hyperalgesia in diabetes.
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Affiliation(s)
- Corinne G Jolivalt
- Department of Pathology, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0612, USA
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Lee JW, Siegel SM, Oaklander AL. Effects of distal nerve injuries on dorsal-horn neurons and glia: relationships between lesion size and mechanical hyperalgesia. Neuroscience 2008; 158:904-14. [PMID: 18992304 DOI: 10.1016/j.neuroscience.2008.10.010] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2008] [Revised: 09/29/2008] [Accepted: 10/27/2008] [Indexed: 10/21/2022]
Abstract
Penetrating limb injuries are common and usually heal without long-lasting effects, even when nerves are cut. However, rare nerve-injury patients develop prolonged and disabling chronic pain (neuralgia). When pain severity is disproportionate to severity of the inciting injury, physicians and insurers may suspect exaggeration and limit care or benefits, although the nature of the relationship between lesion-size and the development and persistence of neuralgia remains largely unknown. We compared cellular changes in the spinal dorsal-horn (the initial CNS pain-processing area) after partial or total tibial-nerve axotomies in male Sprague-Dawley rats to determine if these changes are proportional to the numbers of peripheral axons cut. Unoperated rats provided controls. Plantar hind-paw responses to touch, pin, and cold were quantitated bilaterally to identify hyperalgesic rats. We also compared data from nerve-injured rats with or without hyperalgesic responses to mechanical hind-paw stimulation to evaluate concordance between pain behaviors and dorsal-horn cellular changes. Hyperalgesia was no less prevalent or severe after partial than after total axotomy. L(5) spinal-cord sections from rats killed 7 days postoperatively were labeled for markers of primary afferents (substance P calcitonin gene-related peptide isolectin B4, gamma aminobutyric acid, and glial fibrillary acidic protein), then labeled cells were stereologically quantitated in somatotopically defined dorsal-horn regions. Total axotomy reduced markers of primary afferents more than partial axotomy. In contrast, GABA-immunoreactive profiles were similarly reduced after both lesions, and in rats with sensory loss versus hyperalgesia. Numbers of GFAP-immunoreactive astrocytes increased independently of lesion size and pain status. Small nerve injuries can thus have magnified and disproportionate effects on dorsal-horn neurons and glia, perhaps providing a biological correlate for the disproportionate pain of post-traumatic neuralgias (including complex regional pain syndrome-I) that follow seemingly minor nerve injuries. However, the presence of similar dorsal-horn changes in rats without pain behaviors suggests that not all transcellular responses to axotomy are pain-specific.
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Affiliation(s)
- J W Lee
- Departments of Neurology and Pathology, Massachusetts General Hospital, Harvard Medical School, 275 Charles Street, Warren 310, Boston, MA 02114, USA
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Naik A, Pathirathna S, Jevtovic-Todorovic V. GABAA receptor modulation in dorsal root ganglia in vivo affects chronic pain after nerve injury. Neuroscience 2008; 154:1539-53. [DOI: 10.1016/j.neuroscience.2008.04.061] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2008] [Revised: 04/18/2008] [Accepted: 04/22/2008] [Indexed: 11/28/2022]
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Midazolam administration reverses thermal hyperalgesia and prevents gamma-aminobutyric acid transporter loss in a rodent model of neuropathic pain. Anesth Analg 2008; 106:1296-302, table of contents. [PMID: 18349209 DOI: 10.1213/ane.0b013e318164f1e9] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
BACKGROUND Loss of gamma-aminobutyric acid (GABA) inhibition in the spinal dorsal horn may contribute to neuropathic pain. Here we examined whether systemic administration of the benzodiazepine midazolam would alleviate thermal hyperalgesia due to chronic constriction injury (CCI) of the sciatic nerve. METHODS Hyperalgesia was evaluated with the thermal paw withdrawal latency test before, and 3 and 7 days after CCI. Animals randomly received, via osmotic minipump infusion, midazolam (2.0 mg x kg(-1) x h(-1)), flumazenil (0.004 mg x kg(-1) x h(-1)), midazolam plus flumazenil at the same doses, or saline (0.01 mg x kg(-1) x h(-1)). Four groups of sham-operated rats (surgery without nerve ligation) received matched treatments. Levels of the GABA transporter 1 (GAT-1) in the lumbar spinal dorsal horn were estimated using western immunoblots 7 days after surgery. RESULTS Saline-treated CCI rats developed thermal hyperalgesia on Day 3 with a more pronounced effect on Day 7. Continuous midazolam infusion prevented thermal hyperalgesia on both days. The antihyperalgesic effect of midazolam was reversed by the coadministration of flumazenil. Infusion of flumazenil alone had no effect on the thermal hyperalgesia in CCI rats. Sham-operated rats treated with saline, midazolam, or midazolam plus flumazenil exhibited no thermal hyperalgesia. Unexpectedly, thermal paw withdrawal latency in sham animals treated with flumazenil alone was significantly decreased. Changes in GAT-1 levels paralleled the behavior. Midazolam prevented the CCI-associated decreases, and flumazenil reversed midazolam's effect. Flumazenil alone did not modify GAT-1 levels in CCI animals but in sham animals the transporter levels were significantly reduced. CONCLUSIONS GABA inhibition plays an important role in neuropathic pain. Continuous systemic benzodiazepine administration may prove effective in alleviating neuropathic pain.
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Jones TL, Sorkin LS. Activated PKA and PKC, but not CaMKIIα, are required for AMPA/Kainate-mediated pain behavior in the thermal stimulus model. Pain 2005; 117:259-270. [PMID: 16150547 DOI: 10.1016/j.pain.2005.06.003] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2005] [Revised: 05/30/2005] [Accepted: 06/06/2005] [Indexed: 11/25/2022]
Abstract
Secondary mechanical allodynia resulting from a thermal stimulus (52.5 degrees C for 45s) is blocked by intrathecal (i.t.) pretreatment with calcium-permeable AMPA/KA receptor antagonists, but not NMDA receptor antagonists. Spinal sensitization is presumed to underlie thermal stimulus-evoked secondary mechanical allodynia. We investigated whether this spinal sensitization involves activation and phosphorylation of calcium-dependent protein kinases (PKA, PKC and CaMKIIalpha), and examined if the noxious stimulus increases phosphorylated AMPA GLUR1 (pGLUR1 Ser-845 and pGLUR1 Ser-831). Secondary mechanical allodynia after thermal stimulation was not altered by i.t. pretreatment with control vehicles (saline or 5% DMSO). Comparable allodynia was observed after pretreatment with a selective CaMKIIalpha inhibitor (17 and 34nmol KN-93). In marked contrast, pretreatment with either a PKA (10nmol H89) or PKC (30nmol chelerythrine) inhibitor blocked allodynia. Western immunoblot analyses supported behavioral findings and revealed a thermal stimulus-evoked increase in spinal phosphorylated PKA and PKC, but not CaMKIIalpha. There was no increase in any of the total protein kinases. Although thermal stimulation did not change either pGLUR1 Ser-845 or pGLUR1 Ser-831, it was associated with an increase in cytosolic total GLUR1. Pretreatment with a selective calcium-permeable AMPA/KA receptor antagonist (5nmol joro spider toxin), but not an NMDA receptor antagonist (25nmol d-2-amino-5-phosphonovalerate, AP-5), blocked thermal stimulus-evoked increases in phosphorylated PKA and PKC, in addition to increased cytosolic GLUR1. These findings indicate that spinal sensitization in the thermal stimulus model does not involve CaMKIIalpha activation or AMPA GLUR1 receptor phosphorylation, and differs from that occurring in NMDAr-dependent pain states.
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Affiliation(s)
- Toni L Jones
- The University of California-San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0818, USA
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Kakinohana M, Kakinohana O, Jun JH, Marsala M, Davison KJ, Sugahara K. The Activation of Spinal N-Methyl-d-Aspartate Receptors May Contribute to Degeneration of Spinal Motor Neurons Induced by Neuraxial Morphine After a Noninjurious Interval of Spinal Cord Ischemia. Anesth Analg 2005; 100:327-334. [PMID: 15673851 DOI: 10.1213/01.ane.0000142123.63543.a6] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
We investigated the relationship between the degeneration of spinal motor neurons and activation of N-methyl-d-aspartate (NMDA) receptors after neuraxial morphine following a noninjurious interval of aortic occlusion in rats. Spinal cord ischemia was induced by aortic occlusion for 6 min with a balloon catheter. In a microdialysis study, 10 muL of saline (group C; n = 8) or 30 mug of morphine (group M; n = 8) was injected intrathecally (IT) 0.5 h after reflow, and 30 mug of morphine (group SM; n = 8) or 10 muL of saline (group SC; n = 8) was injected IT 0.5 h after sham operation. Microdialysis samples were collected preischemia, before IT injection, and at 2, 4, 8, 24, and 48 h of reperfusion (after IT injection). Second, we investigated the effect of IT MK-801 (30 mug) on the histopathologic changes in the spinal cord after morphine-induced spastic paraparesis. After IT morphine, the cerebrospinal fluid (CSF) glutamate concentration was increased in group M relative to both baseline and group C (P < 0.05). This increase persisted for 8 hrs. IT MK-801 significantly reduced the number of dark-stained alpha-motoneurons after morphine-induced spastic paraparesis compared with the saline group. These data indicate that IT morphine induces spastic paraparesis with a concomitant increase in CSF glutamate, which is involved in NMDA receptor activation. We suggest that opioids may be neurotoxic in the setting of spinal cord ischemia via NMDA receptor activation.
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Affiliation(s)
- Manabu Kakinohana
- *Department of Anesthesiology, Faculty of Medicine, University of the Ryukyus, Okinawa, Japan; †Department of Anesthesiology, University of California, San Diego, California; ‡Department of Anesthesiology, Hanyang University College of Medicine, Seoul, Korea; and §Department of Anesthesiology, Massachusetts General Hospital, Boston, Massachusetts
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Tambeli CH, Quang P, Levine JD, Gear RW. Contribution of spinal inhibitory receptors in heterosegmental antinociception induced by noxious stimulation. Eur J Neurosci 2004; 18:2999-3006. [PMID: 14656295 DOI: 10.1111/j.1460-9568.2003.03031.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Noxious (i.e. painful) stimulation in the rat induces profound heterosegmental antinociception as demonstrated by the ability of either thermal stimulation (50 degrees C water) or subdermal capsaicin injection in the hindpaw to attenuate the nociceptive trigeminal jaw-opening reflex. Importantly, noxious stimulus-induced antinociception (NSIA) is mediated by endogenous opioids (as well as other neurotransmitters) in nucleus accumbens, as indicated by the ability of intra-accumbens administration of mu- or delta-opioid receptor antagonists to block NSIA. Although noxious peripheral stimulation is known to release excitatory neurotransmitters such as glutamate at the level of the spinal cord, the present study was designed to test the hypothesis that NSIA depends on further activation of spinal inhibitory receptors. This hypothesis was based on findings that inhibition of spinal processing (e.g. intrathecal local anaesthetic administration) also produces heterosegmental antinociception mediated by endogenous opioids in nucleus accumbens. Thus, to reconcile the paradoxical findings that both spinal excitation and inhibition appear to activate the same nucleus accumbens opioid-mediated antinociceptive mechanism, we investigated whether spinal administration of antagonists for inhibitory receptors would block the antinociceptive effect of subdermal capsaicin. We report that spinal administration of selective antagonists for mu-opioid (Cys2, Tyr3, Orn5, Pen7amide), kappa-opioid (nor-binaltorphimine), GABA-A (bicuculline), GABA-B (CGP 35348) and glycine (strychnine) receptors significantly reduced NSIA. The selective delta-opioid receptor antagonist naltrindole had no significant effect. These results, together with our previous findings, suggest that peripheral noxious stimuli release endogenous opioids, GABA and glycine in the spinal cord which, in turn, inhibit tonic pronociceptive spinal activity to produce heterosegmental antinociception mediated in nucleus accumbens.
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MESH Headings
- Animals
- Bicuculline/pharmacology
- Capsaicin/pharmacology
- Dose-Response Relationship, Drug
- Drug Interactions
- Electrodes, Implanted
- Electromyography
- GABA Antagonists
- Glycine Agents/pharmacology
- Male
- Models, Neurological
- Narcotic Antagonists/pharmacology
- Neural Inhibition/physiology
- Nucleus Accumbens/physiopathology
- Organophosphorus Compounds/pharmacokinetics
- Pain/chemically induced
- Pain/physiopathology
- Pain Measurement/methods
- Physical Stimulation
- Rats
- Rats, Sprague-Dawley
- Receptors, Opioid, kappa/antagonists & inhibitors
- Receptors, Opioid, kappa/drug effects
- Receptors, Opioid, mu/antagonists & inhibitors
- Receptors, Opioid, mu/drug effects
- Spinal Cord/drug effects
- Spinal Cord/physiopathology
- Strychnine/pharmacology
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Affiliation(s)
- C H Tambeli
- Department of Oral and Maxillofacial Surgery, Room C-522, Box 0440, University of California at San Francisco, San Francisco, CA 94143-0440, USA
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Somers DL, Clemente FR. The relationship between dorsal horn neurotransmitter content and allodynia in neuropathic rats treated with high-frequency transcutaneous electric nerve stimulation. Arch Phys Med Rehabil 2003; 84:1575-83. [PMID: 14639554 DOI: 10.1053/s0003-9993(03)00290-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
OBJECTIVE To examine the relation between axon terminal neurotransmitter content in the dorsal horn and allodynia in neuropathic rats treated with high-frequency transcutaneous electric nerve stimulation (TENS). DESIGN A completely randomized experimental design. Two groups of rats received a chronic constriction injury to the right sciatic nerve, and 2 groups did not. The rats were either treated or not treated with TENS. SETTING Research laboratory. ANIMALS Adult male Sprague-Dawley rats (150-165g). INTERVENTIONS TENS was delivered daily for 1 hour to the chronic constriction injury rats or to the uninjured rats through self-adhesive electrodes applied to the skin innervated by the right dorsal rami of lumbar spinal nerves 1 to 6. MAIN OUTCOME MEASURES Thermal and mechanical pain thresholds were assessed bilaterally in the hind paws of all rats twice before the chronic constriction injury surgery (baseline) and then 12 days after the surgery. An analogous time frame of assessment was used for rats that did not have chronic constriction injury surgery. Thermal and mechanical allodynia were expressed as difference scores between the pain thresholds of the right and left hind paws. These values were normalized to differences that existed between the 2 paws at baseline. The amino acid content of dorsal horn axon terminals was assessed bilaterally with high-pressure liquid chromatography, and values were normalized to wet weight. RESULTS The mean level of thermal and mechanical allodynia did not differ between the TENS-treated and untreated rats with chronic constriction injury. However, there was a significant relation between the dorsal horn, axon terminal content of glutamate (adjusted R(2)=.45, P<.01) and glycine (adjusted R(2)=.51, P<.005) and the magnitude of mechanical allodynia present in TENS-treated chronic constriction injury rats, but not in any other group. As axon terminal glutamate and glycine decreased in the right dorsal horn and increased in the left, mechanical allodynia was reduced or absent. When this trend was reversed, mechanical allodynia was more severe. Daily TENS also reduced the mean axon terminal content of aspartate, glutamate, and glycine bilaterally in the chronic constriction injury rats from the level observed in untreated neuropathic rats (P<.05). CONCLUSION The variability in responsiveness of mechanical allodynia to daily TENS treatment in neuropathic rats is related to the axon terminal content of glutamate and glycine in the dorsal horn. These findings may help explain a similar variability in humans when TENS is used to treat neuropathic pain.
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Affiliation(s)
- David L Somers
- Department of Physical Therapy, John G. Rangos Sr. School of Health Sciences, Duquesne University, Pittsburgh, PA 15282-0011, USA.
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Al-Amin HA, Saadé NE, Khani M, Atweh S, Jaber M. Effects of chronic dizocilpine on acute pain and on mRNA expression of neuropeptides and the dopamine and glutamate receptors. Brain Res 2003; 981:99-107. [PMID: 12885430 DOI: 10.1016/s0006-8993(03)02988-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The mesocorticolimbic circuitry has been implicated in the pathophysiology of several neuropsychiatric syndromes like chronic pain and addiction. The aim of this study was to evaluate the effects of dizocilpine (MK-801), a non-competitive N-methyl-D-aspartate (NMDA) receptor antagonist, on sensorimotor behaviors and the consequent changes in the dopamine, glutamate, and opiate systems in rats. Five groups of rats were subjected to acute tests for nociception (hot plate and paw pressure) before and after MK-801 (0.05, 0.1, 0.2 and 0.4 mg/kg, i.p.) or saline. Another two groups received daily i.p. saline or MK-801 (0.4 mg/kg) for 15 days. The nociceptive tests were performed on days 1, 7, and 14. On day 15 the rats received the last injection and were immediately sacrificed. We measured the mRNA expression, by in situ hybridization (ISH), of various dopamine and glutamate receptors, and enkephalin (Enk), dynorphin (Dyn), and substance P (SP) in the striatum, nucleus accumbens (NAC), piriform and cingulate cortex. Acute MK-801, dose-dependently, resulted in hyperalgesia. The chronic effects of 0.4 mg/kg MK-801 showed an extinction of the acute hyperalgesic effects especially with the hot plate test. The ISH studies revealed a decrease in mRNA expression of Enk and SP in the striatum and NAC. Our results indicate that the reversal of acute MK-801-induced hyperalgesia, with repeated exposure to systemic MK-801, is not directly related to changes in dopamine and glutamate receptors and might involve alteration of the striatal neuropeptide system.
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Affiliation(s)
- Hassen A Al-Amin
- Department of Psychiatry, American University of Beirut Medical Center, Box 16A, Beirut, Lebanon.
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Cousins MJ, Kakinohana M, Fuchigami T, Nakamura S, Sasara T, Kawabata T, Sugahara K. Intrathecal administration of morphine, but not small dose, induced spastic paraparesis after a noninjurious interval of aortic occlusion in rats. Anesth Analg 2003; 96:769-775. [PMID: 12598261 DOI: 10.1213/01.ane.0000048855.24190.5f] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
UNLABELLED We sought to investigate the dose-response relationship for the effect of intrathecal morphine on the transient spastic paraparesis after short-lasting spinal ischemia in rats. Spinal ischemia was induced by aortic occlusion for 6 min with a balloon catheter in rats previously implanted with an intrathecal catheter for drug delivery. After ischemia, the animals were allowed to recover, and 3, 10, or 30 microg of morphine or saline was injected intrathecally at 30 min after reperfusion. In a separate group, the quantal bioassay for the effect of intrathecal morphine on neurological function after ischemia was performed to calculate 50% effective dose values for inducing paraparesis at 2 h of reperfusion. Subsequently, histopathology of the spinal cord was assessed at 48 h of reperfusion. Intrathecal injection of 30 or 10 micro g of morphine, but 3 micro g of neither morphine nor saline, caused a progressive development of hindlimb spasticity. The 50% effective dose values for inducing paraparesis were 16.1 +/- 1.5 microg in assessing behavioral analysis at 2 h after intrathecal morphine. Histopathological analysis of spinal cords in the 30- microg group revealed the presence of dark-staining alpha-motoneurons in lumbosacral segments. We conclude that spinal administration of a large dose of morphine after transient aortic occlusion may be associated with a potential risk of paraparesis and the corresponding development of neurological dysfunction. Careful attention should be paid when intrathecal morphine is used for pain control after thoracoabdominal aortic aneurysm repair. IMPLICATIONS Spinal administration of large-dose morphine after transient aortic occlusion may be associated with a potential risk of irreversible spinal neuronal degeneration and the corresponding development of neurological dysfunction.
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Affiliation(s)
- Michael J Cousins
- Department of Anesthesiology, Faculty of Medicine, University of the Ryukyus, Okinawa, Japan
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Marvizón JCG, McRoberts JA, Ennes HS, Song B, Wang X, Jinton L, Corneliussen B, Mayer EA. Two N-methyl-D-aspartate receptors in rat dorsal root ganglia with different subunit composition and localization. J Comp Neurol 2002; 446:325-41. [PMID: 11954032 DOI: 10.1002/cne.10202] [Citation(s) in RCA: 104] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
N-methyl-D-aspartate (NMDA) receptors in sensory afferents participate in chronic pain by mediating peripheral and central sensitization. We studied the presence of NMDA receptor subunits in different types of primary afferents. Western blots indicated that rat dorsal root ganglia (DRG) contain NR1, NR2B, NR2C, and NR2D but not NR2A. Real-time RT-PCR showed that NR2B and NR2D were expressed at higher levels than NR2A and NR2C in DRG. Immunofluorescence with an antibody that recognized NR1 and another that recognized NR2A and NR2B showed that NR1 and NR2B colocalized in 90% of DRG neurons, including most A-fibers (identified by the presence of neurofilament 200 kDa). In contrast, an antibody recognizing NR2C and NR2D labeled only neurofilament-negative DRG profiles. This antibody stained practically all DRG cells that contained calcitonin gene-related peptide and neurokinins and those that bound isolectin B4. The percentage of cells immunoreactive for NR1, NR2A/NR2B, and NR2C/NR2D were the same in the T9, T12, L4, and L6 DRG. The intracellular distribution of the NR2 subunits was strikingly different: Whereas NR2A/NR2B immunoreactivity was found in the Golgi apparatus and occasionally at the plasma membrane, NR2C/NR2D immunoreactivity was found in the cytoplasm but not in the Golgi. The NR1 subunit was present throughout the cytoplasm and was more intense in the Golgi. These findings indicate that DRG neurons have two different NMDA receptors, one containing the NR1, NR2D, and possibly the NR2C subunits, found only in C-fibers, and the diheteromer NR1/NR2B, present in the Golgi apparatus of both A- and C-fibers.
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MESH Headings
- Animals
- Antibody Specificity/immunology
- Calcitonin Gene-Related Peptide/metabolism
- Cell Compartmentation/physiology
- Chronic Disease
- Ganglia, Spinal/cytology
- Ganglia, Spinal/metabolism
- Lectins/metabolism
- Male
- Nerve Fibers/metabolism
- Nerve Fibers/ultrastructure
- Nerve Fibers, Myelinated/metabolism
- Nerve Fibers, Myelinated/ultrastructure
- Neurofilament Proteins/metabolism
- Neurons, Afferent/cytology
- Neurons, Afferent/metabolism
- Organelles/metabolism
- Organelles/ultrastructure
- Pain/metabolism
- Pain/physiopathology
- RNA, Messenger/metabolism
- Rats
- Rats, Sprague-Dawley/anatomy & histology
- Rats, Sprague-Dawley/metabolism
- Receptors, N-Methyl-D-Aspartate/genetics
- Receptors, N-Methyl-D-Aspartate/metabolism
- Tachykinins/metabolism
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Affiliation(s)
- Juan Carlos G Marvizón
- Neuroenteric Disease Program, CURE: Digestive Diseases Research Center, Department of Medicine, University of California at Los Angeles, Los Angeles, California 90095, USA.
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Somers DL, Clemente FR. Dorsal horn synaptosomal content of aspartate, glutamate, glycine and GABA are differentially altered following chronic constriction injury to the rat sciatic nerve. Neurosci Lett 2002; 323:171-4. [PMID: 11959412 DOI: 10.1016/s0304-3940(02)00157-x] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The present study directly examined the axon terminal (synaptosomal) level of amino acid neurotransmitters in rats following chronic constriction injury (CCI) to the sciatic nerve. Dorsal horn, synaptosomal content of aspartate (Asp), glutamate (Glu), glycine and gamma-aminobutyric acid (GABA) was assessed in these rats, and in normal age-matched and younger rats. The synaptosomal content of Asp and Glu in CCI rats was increased by 44-46% compared with control rats (P<0.016). The synaptosomal content of GABA in younger rats was 33% lower than that observed in control rats (P<0.005). Altered axon terminal levels of amino acid neurotransmitters accompany the painful symptoms of neuropathy. The lower axon terminal level of GABA in younger rats may help to explain the age-dependency of pain development in animal models of nerve injury.
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Affiliation(s)
- David L Somers
- Department of Physical Therapy, Duquesne University, 304 Health Sciences Building, Pittsburgh, PA 15282, USA.
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Stubley LA, Martinez MA, Karmally S, Lopez T, Cejas P, Eaton MJ. Only early intervention with gamma-aminobutyric acid cell therapy is able to reverse neuropathic pain after partial nerve injury. J Neurotrauma 2001; 18:471-7. [PMID: 11336447 DOI: 10.1089/089771501750171092] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Pharmacological treatment for neuropathic pain, although often effective for brief periods, can result in intractable persistent pain with certain patients. Cell therapy for neuropathic pain is a newly developing technology useful for an examination of enhanced normal sensory function after nerve injury with the placement of cells near the spinal cord, and grafts of immortalized cells bioengineered to chronically supply the inhibitory neurotransmitter gamma-aminobutyric acid (GABA) have been used to reverse the chronic pain behaviors. However, it is not known whether there is a therapeutic window for the use of intervention with cell therapy after partial nerve injury. To investigate whether neuropathic pain is sensitive to the timing of placement of cell grafts, neuronal cells bioengineered to synthesize GABA were transplanted in the lumbar subarachnoid space one to four weeks after unilateral chronic constriction injury (CCI) of the sciatic nerve and sensory behaviors were evaluated before and after CCI and transplants. Both thermal hyperalgesia and tactile allodynia were reversed when transplants were placed either one or two weeks after partial nerve injury, compared to maintenance of these behaviors with the injury alone. However, if GABA cells were placed any later than 2 weeks after nerve injury, such intervention was ineffective to reverse the thermal and tactile hypersensitivities induced by the injury. This suggests that altered spinal GABA levels may contribute to the early development of chronic neuropathic pain and that early intervention with cellular therapy to restore GABA may prevent the development of that pain.
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Affiliation(s)
- L A Stubley
- The Miami Project to Cure Paralysis, University of Miami School of Medicine, Florida 33136, USA
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Ma QP, Hargreaves RJ. Localization of N-methyl-D-aspartate NR2B subunits on primary sensory neurons that give rise to small-caliber sciatic nerve fibers in rats. Neuroscience 2001; 101:699-707. [PMID: 11113318 DOI: 10.1016/s0306-4522(00)00419-x] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
In the present study we have used immunohistochemical staining and retrograde tracing techniques to investigate the relationship between the N-methyl-D-aspartate receptor NR2B subunits and small-diameter primary afferent dorsal root ganglion neurons that give rise to the sciatic nerve fibers. Three days after an intra-sciatic nerve injection of tetramethyl rhodamine isothiocyanate-conjugated wheat germ agglutinin which labels small-diameter primary afferents, many NR2B and wheat germ agglutinin-double-labeled cells ( approximately 70% of wheat germ agglutinin-labeled neurons) were observed in the L5 dorsal root ganglia. Three days after an intra-sciatic nerve injection of fluorescein isothiocyanate-conjugated Bandeiraea simplicifolia agglutinin isolectin B4 which labels predominantly non-peptidergic C-fiber primary afferents, NR2B and Bandeiraea simplicifolia agglutinin isolectin B4 double-labeled neurons ( approximately 90% of Bandeiraea simplicifolia agglutinin isolectin B4-labeled neurons) were also observed in the L5 dorsal root ganglion. Three days after an intra-sciatic nerve injection of fluorescein isothiocyanate-conjugated cholera toxin B subunit, only approximately 40% of cholera toxin B subunit-labeled neurons were NR2B positive and those labeled neurons tended to be small-sized. When calcitonin gene-related peptide and NR2B were labeled by a double immunofluorescent staining technique, we found that the majority of calcitonin gene-related peptide-positive neurons was NR2B immunoreactive (>90% of calcitonin gene-related peptide-positive neurons, and approximately 60% of NR2B-positive neurons) as well. Size frequency analysis also demonstrated that NR2B subunits were predominantly localized on the small and medium-sized neurons. These results suggest that NR2B subunits are predominantly expressed on small diameter primary afferents, and these NR2B containing N-methyl-D-aspartate receptors may play a role in the modulation of neurotransmitter release from primary afferent terminals.
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Affiliation(s)
- Q P Ma
- Department of Pharmacology, Merck Sharp & Dohme Research Laboratories, Neuroscience Research Centre, Terlings Park, CM20 2QR, Harlow, UK.
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46
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Suzuki R, Matthews EA, Dickenson AH. Comparison of the effects of MK-801, ketamine and memantine on responses of spinal dorsal horn neurones in a rat model of mononeuropathy. Pain 2001; 91:101-9. [PMID: 11240082 DOI: 10.1016/s0304-3959(00)00423-1] [Citation(s) in RCA: 94] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Selective ligation of the L5/L6 spinal nerves produces a partial denervation of the hindpaw and has proved to be a useful model for studying the mechanisms underlying neuropathic pain. Two weeks after surgery, in vivo electrophysiological studies were performed in sham operated and nerve injured rats and the responses of spinal dorsal horn neurones to controlled electrical and natural (mechanical and heat) stimuli were recorded. The systemic effects of three N-methyl-D-aspartate receptor (NMDA) antagonists, ketamine (1-10 mg/kg), memantine (1-20 mg/kg) and MK-801 (0.1-5 mg/kg) were compared. Ketamine a clinically available NMDA receptor antagonist, produced greater reductions of the postdischarge, thermal (10 mg/kg, P=0.02), and mechanical evoked responses in spinal nerve ligated (SNL) rats (von Frey 9 g, 1 mg/kg, P=0.04; 5 mg/kg, P=0.01; 10 mg/kg, P=0.05; von Frey 50 g, 5 mg/kg, P=0.02; 10 mg/kg, P=0.003). The inhibition of wind-up was comparable in both animal groups. Memantine produced powerful inhibitions of wind-up after nerve injury with little effect in sham controls (5 mg/kg, P=0.02). The postdischarge, mechanical and thermal evoked responses were reduced to similar extents by memantine in both experimental groups. The effects of MK-801 were comparable between SNL and sham operated rats for all neuronal measures (wind-up, postdischarge, thermal and noxious mechanical evoked responses). The differential blocking abilities of these antagonists on the various neuronal responses may relate to the characteristics of their voltage-dependent blockage of the channel associated with the receptor. The favourable side effect profile of memantine supports its potential use for the treatment of neuropathic pain.
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Affiliation(s)
- R Suzuki
- Department of Pharmacology, University College London, Gower Street, WC1E 6BT, London, UK.
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Almeida FR, Schivo IR, Lorenzetti BB, Ferreira SH. Chronic intrathecal cannulation enhances nociceptive responses in rats. Braz J Med Biol Res 2000; 33:949-56. [PMID: 10920437 DOI: 10.1590/s0100-879x2000000800011] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The influence of a chronically implanted spinal cannula on the nociceptive response induced by mechanical, chemical or thermal stimuli was evaluated. The hyperalgesia in response to mechanical stimulation induced by carrageenin or prostaglandin E2 (PGE2) was significantly increased in cannulated (Cn) rats, compared with naive (Nv) or sham-operated (Sh) rats. Only Cn animals presented an enhanced nociceptive response in the first phase of the formalin test when low doses were used (0.3 and 1%). The withdrawal latency to thermal stimulation of a paw inflamed by carrageenin was significantly reduced in Cn rats but not in Nv or Sh rats. In contrast to Nv and Sh rats, injection in Cn animals of a standard non-steroid anti-inflammatory drug, indomethacin, either intraperitoneally or into the spinal cord via an implanted cannula or by direct puncture of the intrathecal space significantly blocked the intensity of the hyperalgesia induced by PGE2. Cannulated animals treated with indomethacin also showed a significant inhibition of second phase formalin-induced paw flinches. Histopathological analysis of the spinal cord showed an increased frequency of mononuclear inflammatory cells in the Cn groups. Thus, the presence of a chronically implanted cannula seems to cause nociceptive spinal sensitization to mechanical, chemical and thermal stimulation, which can be blocked by indomethacin, thus suggesting that it may result from the spinal release of prostaglandins due to an ongoing mild inflammation.
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Affiliation(s)
- F R Almeida
- Departamento de Farmacologia, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brasil
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48
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Eaton MJ. Emerging cell and molecular strategies for the study and treatment of painful peripheral neuropathies. J Peripher Nerv Syst 2000; 5:59-74. [PMID: 10905465 DOI: 10.1046/j.1529-8027.2000.00006.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Pharmacologic treatment for the symptoms of painful neuropathy has been problematic, because there has been limited understanding of the underlying etiologies and systemic levels that an effective dose can have on multiple side effects. The use of molecular methods, such as gene deletion from knockout mice and cellular minipumps for delivery of biologic antinociceptive molecules, has led to a better understanding of the underlying mechanisms of the induction of intractable neuropathic pain. The initiation of an excitatory cascade after injury or disease leads to the induction of various second messenger systems, loss or down-regulation of the endogenous inhibitory spinal GABA system and central sensitization, causing such pain. The development and use of cellular minipumps, immortalized cell lines bioengineered to secrete various antinociceptive molecules for the reversal of neuropathic pain, makes cellular therapy a strategy for clinical use in the next few years. The development of molecular "disimmortalization" technologies will make the use of such engineered cell lines safe for human use. Direct somatic gene transfer for neuropathic pain will eventually overcome the problems associated with transplantation of non-autologous and xenogenic cells. These virus-mediated methods, although at the early stages of evolution and use, offer large-scale production of biologic agents that can be conveniently and confidently used for the long-term relief of chronic neuropathic pain in a clinical setting, without systemic effects or surgical interventions.
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Affiliation(s)
- M J Eaton
- The Miami Project to Cure Paralysis and the Department of Neurological Surgery, University of Miami School of Medicine, Florida 33136, USA.
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49
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Cejas PJ, Martinez M, Karmally S, McKillop M, McKillop J, Plunkett JA, Oudega M, Eaton MJ. Lumbar transplant of neurons genetically modified to secrete brain-derived neurotrophic factor attenuates allodynia and hyperalgesia after sciatic nerve constriction. Pain 2000; 86:195-210. [PMID: 10779676 DOI: 10.1016/s0304-3959(00)00245-1] [Citation(s) in RCA: 88] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Chronic delivery of anti-nociceptive molecules by means of cell grafts near the pain processing centers of the spinal cord is a newly developing technique for the treatment of neuropathic pain. The rat neuronal cell line, RN33B, derived from E13 rat brainstem raphe and immortalized with the SV40 temperature-sensitive allele of large T antigen (tsTag), was transfected with rat brain-derived neurotrophic factor cDNA (BDNF), and the BDNF-synthesizing cell line, 33BDNF.4, was isolated. The 33BDNF.4 cells synthesized mature BDNF protein at permissive temperature (33 degrees C), when the cells were proliferating, and during differentiation at non-permissive temperature (39 degrees C) in vitro. The bio-active BDNF protein was also secreted by the cells during both growth conditions, as measured by ELISA analysis of BDNF content and secretion. The bio-activity of the BDNF in 33BDNF.4 cell conditioned media was assessed by neurite outgrowth from E15 dorsal root ganglion (DRG) cultures. A control cell line, 33V1, transfected with the vector alone, did not synthesize or secrete any significant BDNF at either growth condition. Both cell lines were used as grafts in a model of chronic neuropathic pain induced by unilateral chronic constriction injury (CCI) of the sciatic nerve. Pain-related behaviors, including cold and tactile allodynia and thermal and tactile hyperalgesia, were evaluated after CCI in the affected hindpaw. When 33BDNF.4 and 33V1 cells were transplanted in the lumbar subarachnoid space of the spinal cord 1 week after CCI, they survived greater than 7 weeks on the pia mater around the spinal cord and the 33BDNF.4 cells continued to synthesize BDNF in vivo. Furthermore, the tactile and cold allodynia and tactile and thermal hyperalgesia induced by CCI was significantly reduced during the 2-7 week period after grafts of 33BDNF.4 cells. The maximal effect on chronic pain behaviors with the BDNF grafts occurred 2-3 weeks after transplant and the anti-nociceptive effects of the BDNF cell grafts was permanent. Transplants of the control 33V1 cells had no effect on the allodynia and hyperalgesia induced by CCI and these cells did not synthesize BDNF in vivo. These data suggest that a chronically applied, low local dose of BDNF supplied by transplanted cells near the spinal dorsal horn was able to reverse the development of chronic neuropathic pain following CCI. The use of neural cell lines that are able to deliver anti-nociceptive molecules, such as BDNF, in a model of chronic pain offers a novel approach to pain management and such 'biologic minipumps' can be developed for safe use in humans.
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Affiliation(s)
- P J Cejas
- The Miami Project to Cure Paralysis, University of Miami School of Medicine, FL 33136, USA
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50
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Kontinen VK, Dickenson AH. Effects of midazolam in the spinal nerve ligation model of neuropathic pain in rats. Pain 2000; 85:425-431. [PMID: 10781915 DOI: 10.1016/s0304-3959(99)00298-5] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Potential changes in the spinal GABAergic activity after nerve injury were studied by comparing the effects of systemic administration of the benzodiazepine midazolam on the noxious evoked responses of dorsal horn in rats with spinal nerve ligation of neuropathy and control animals. The tight ligation of the L(5) and L6 spinal nerves was performed in adult male Sprague-Dawley rats and resulting mechanical and cold allodynia were assessed with von Frey hairs and the acetone drop test. Single unit extracellular recordings of dorsal horn neurones were performed 15-18 days after the surgery under halothane anaesthesia using transcutaneous electrical stimulation of the receptive field at three times the C-fibre threshold. The rats in the spinal nerve ligation group, but not in the sham-operated control group developed mechanical and cold allodynia. Subcutaneous administration of midazolam 0.1-3.0 mg/kg reduced the Adelta-fibre evoked activity in a dose-related manner in all study groups, but the C-fibre evoked activity was significantly reduced only in the spinal nerve ligation group. The inhibitory effects of s.c. midazolam were significantly reversed by i.t. administration of flumazenil, suggesting a spinal site of action. Midazolam reduced C-fibre evoked firing significantly more in the spinal nerve ligation model than in the non-operated or sham controls. These results indicate changes in the spinal GABAergic system in the neuropathic animals and could be of importance in the development of new treatments for neuropathic pain.
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Affiliation(s)
- Vesa K Kontinen
- Department of Pharmacology, University College London, Gower Street, London WC1E 6BT, UK Department of Pharmacology and Toxicology, Institute of Biomedicine, Siltavuorenpenger 10, FIN-00014 University of Helsinki, Finland
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