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Liu P, Li Q, Tang YF, Cui CY, Liu Q, Zhang Y, Tang B, Lai QC. Multiple algorithms highlight key brain genes driven by multiple anesthetics. Comput Biol Med 2024; 179:108805. [PMID: 38991319 DOI: 10.1016/j.compbiomed.2024.108805] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2024] [Revised: 05/05/2024] [Accepted: 06/24/2024] [Indexed: 07/13/2024]
Abstract
Anesthesia serves as a pivotal tool in modern medicine, creating a transient state of sensory deprivation to ensure a pain-free surgical or medical intervention. While proficient in alleviating pain, anesthesia significantly modulates brain dynamics, metabolic processes, and neural signaling, thereby impairing typical cognitive functions. Furthermore, anesthesia can induce notable impacts such as memory impairment, decreased cognitive function, and diminished intelligence, emphasizing the imperative need to explore the concealed repercussions of anesthesia on individuals. In this investigation, we aggregated gene expression profiles (GSE64617, GSE141242, GSE161322, GSE175894, and GSE178995) from public repositories following second-generation sequencing analysis of various anesthetics. Through scrutinizing post-anesthesia brain tissue gene expression utilizing Gene Set Enrichment Analysis (GSEA), Robust Rank Aggregation (RRA), and Weighted Gene Co-expression Network Analysis (WGCNA), this research aims to pinpoint pivotal genes, pathways, and regulatory networks linked to anesthesia. This undertaking not only enhances comprehension of the physiological changes brought about by anesthesia but also lays the groundwork for future investigations, cultivating new insights and innovative perspectives in medical practice.
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Affiliation(s)
- Ping Liu
- Department of Anesthesiology, The Affiliated Traditional Chinese Medicine Hospital, Southwest Medical University, Luzhou, 646000, Sichuan, China
| | - Qun Li
- Department of Pain, The Affiliated Traditional Chinese Medicine Hospital, Southwest Medical University, Luzhou, 646000, Sichuan, China
| | - Yi-Fan Tang
- Department of Anesthesiology, The Affiliated Traditional Chinese Medicine Hospital, Southwest Medical University, Luzhou, 646000, Sichuan, China
| | - Chun-Yan Cui
- Department of Anesthesiology, The Affiliated Traditional Chinese Medicine Hospital, Southwest Medical University, Luzhou, 646000, Sichuan, China; Department of Pain, The Affiliated Traditional Chinese Medicine Hospital, Southwest Medical University, Luzhou, 646000, Sichuan, China
| | - Qing Liu
- Department of Pain, The Affiliated Traditional Chinese Medicine Hospital, Southwest Medical University, Luzhou, 646000, Sichuan, China; Department of Anesthesiology, Hejiang Hospital of Traditional Chinese Medicine, Southwest Medical University, China
| | - Ying Zhang
- Department of Anesthesiology, The Affiliated Traditional Chinese Medicine Hospital, Southwest Medical University, Luzhou, 646000, Sichuan, China; Central Nervous System Drug Key Laboratory of Sichuan Province, Southwest Medical University, Luzhou, 646000, Sichuan, China; Department of Anesthesiology, Hejiang Hospital of Traditional Chinese Medicine, Southwest Medical University, China.
| | - Bo Tang
- Department of Pathology, The Affiliated Traditional Chinese Medicine Hospital, Southwest Medical University, Luzhou, 646000, Sichuan, China
| | - Qian-Cheng Lai
- Department of Cardiac Surgery, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, China
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2
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Kumru H, Kofler M, Albu S, Vidal J, Benito J. Long-term use of intrathecal baclofen reduces neuropathic pain and its interference with general activity in spinal cord injury individuals. Acta Neurol Belg 2024:10.1007/s13760-024-02524-x. [PMID: 38763965 DOI: 10.1007/s13760-024-02524-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2023] [Accepted: 03/01/2024] [Indexed: 05/21/2024]
Abstract
INTRODUCTION Long-term analgesic effect of intrathecal baclofen was reported in individuals with spinal cord injury. We conducted a prospective study to evaluate the effect of intrathecal baclofen on subtypes of neuropathic pain and its interference with general activity. MATERIALS AND METHODS Nine spinal cord injury individuals who presented with severe spasticity and moderate to severe neuropathic pain received intrathecal baclofen via an implanted pump. We applied the ASIA Impairment Scale to assess spinal cord injury severity. Neuropathic pain was evaluated by numerical rating scale, Neuropathic Pain Symptom Inventory, and Brief Pain Inventory. Evaluations were performed at baseline and after at least 6 months of continuous intrathecal baclofen treatment. RESULTS Intrathecal baclofen led to significant pain reduction as measured by numerical rating scale, Neuropathic Pain Symptom Inventory, and Brief Pain Inventory (p < 0.05). Improvements were significant for paroxysmal pain and dysesthesia and for pain interference with general activity, as assessed by the Brief Pain Inventory (p < 0.05). There was a significant relationship between the time since spinal cord injury and changes in paroxysmal pain as well as in the total Neuropathic Pain Symptom Inventory score (p < 0.05). The baclofen dose correlated also to the percentage changes in neuropathic pain improvement and sleep (p < 0.003). CONCLUSIONS The present results provide evidence that intrathecal baclofen effectively reduces neuropathic pain, particularly paroxysmal pain and dysesthesia, and improves pain interference and overall well-being in individuals with spinal cord injury. Clinicians should be aware of this less well-known beneficial effect of intrathecal baclofen and should consider such a treatment option for better control of neuropathic pain in individuals with spinal cord injury.
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Affiliation(s)
- Hatice Kumru
- Institut Guttmann, Institut Universitari de Neurorehabilitació adscrit a la UAB, Camí Can Ruti s/n., 08916, Badalona, Barcelona, Spain.
- Universitat Autònoma de Barcelona, Bellaterra (Cerdanyola del Vallès), Spain.
- Fundació Institut d'Investigació en Ciències de la Salut Germans Trias I Pujol, Badalona, Barcelona, Spain.
| | - Markus Kofler
- Department of Neurology, Hochzirl Hospital, Zirl, Austria
| | - Sergiu Albu
- Institut Guttmann, Institut Universitari de Neurorehabilitació adscrit a la UAB, Camí Can Ruti s/n., 08916, Badalona, Barcelona, Spain
- Universitat Autònoma de Barcelona, Bellaterra (Cerdanyola del Vallès), Spain
- Fundació Institut d'Investigació en Ciències de la Salut Germans Trias I Pujol, Badalona, Barcelona, Spain
| | - Joan Vidal
- Institut Guttmann, Institut Universitari de Neurorehabilitació adscrit a la UAB, Camí Can Ruti s/n., 08916, Badalona, Barcelona, Spain
- Universitat Autònoma de Barcelona, Bellaterra (Cerdanyola del Vallès), Spain
- Fundació Institut d'Investigació en Ciències de la Salut Germans Trias I Pujol, Badalona, Barcelona, Spain
| | - Jesus Benito
- Institut Guttmann, Institut Universitari de Neurorehabilitació adscrit a la UAB, Camí Can Ruti s/n., 08916, Badalona, Barcelona, Spain
- Universitat Autònoma de Barcelona, Bellaterra (Cerdanyola del Vallès), Spain
- Fundació Institut d'Investigació en Ciències de la Salut Germans Trias I Pujol, Badalona, Barcelona, Spain
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Xu L, Wang Y, Jiao Y, Huang Y, Xu R, Gu X, Zhang W, Ma Z. Involvement of Spinal Neuroplastin 65 in Neuropathic Pain by GABAA Receptor α2 Subunit Regulation. Anesth Analg 2024:00000539-990000000-00797. [PMID: 38507554 DOI: 10.1213/ane.0000000000006964] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/22/2024]
Abstract
BACKGROUND Neuropathic pain (NP) is a highly challenging condition with complex pathological mechanisms, and the spinal gamma aminobutyric acid A receptor receptor plays a crucial role in its progression. Recent studies have revealed a potential interaction between neuroplastin 65 (NP65) and gamma aminobutyric acid A receptor α2 subunit (GABAAR-α2) on the cell surface. We hypothesize that NP65 is involved in the pathogenesis of NP by regulating the level of GABAAR-α2. METHODS A chronic constrictive injury (CCI) pain model was established in male Sprague-Dawley rats to verify the change in spinal NP65 expression. Alterations in pain behavior and GABAAR-α2 protein expression were observed after intrathecal injection of NP65 overexpressing adeno-associated virus (AAV) in CCI rats. In vitro investigations on Neuroblastoma 2a cells, the effect of NP65 on GABAAR-α2 expression via the calcineurin-nuclear factor of activated T-cell 4 (CaN-NFATc4) signaling pathway was evaluated by manipulating NP65 expression. RESULTS The expression level of NP65 protein and mRNA in the CCI group were significantly decreased (P < .05; analysis of variance [ANOVA]). After intrathecal injection of NP65, overexpression of AAV and pain behavior in CCI rats were significantly alleviated, and levels of GABAAR-α2 were upregulated. In vitro experiments verified alterations in the expression of GABAAR-α2, CaN, and phosphorylated NFATc4 on the application of NP65 with plasmid or small interfering RNA, respectively. After the application of the specific CaN inhibitor cyclosporine A (CsA), the changes in NP65 expression did not produce subsequent alterations in the expression of GABAAR-α2, CaN, or phosphorylated NFATc4 proteins. CONCLUSIONS NP65 modulates the level of GABAAR-α2 through the CaN-NFATc4 signaling pathway, which may serve as the underlying mechanism of NP.
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Affiliation(s)
- Li Xu
- From the Department of Anesthesiology, Nanjing Drum Tower Hospital Clinical College of Nanjing Medical University, Nanjing, China
| | - Yu Wang
- Department of Anesthesiology, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, Nanjing, China
| | - Yang Jiao
- Department of Anesthesiology, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, Nanjing, China
| | - Yulin Huang
- Department of Anesthesiology, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, Nanjing, China
| | - Rui Xu
- Department of Anesthesiology, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, Nanjing, China
| | - Xiaoping Gu
- Department of Anesthesiology, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, Nanjing, China
| | - Wei Zhang
- Department of Anesthesiology, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, Nanjing, China
| | - Zhengliang Ma
- From the Department of Anesthesiology, Nanjing Drum Tower Hospital Clinical College of Nanjing Medical University, Nanjing, China
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Marty-Lombardi S, Lu S, Ambroziak W, Schrenk-Siemens K, Wang J, DePaoli-Roach AA, Hagenston AM, Wende H, Tappe-Theodor A, Simonetti M, Bading H, Okun JG, Kuner R, Fleming T, Siemens J. Neuron-astrocyte metabolic coupling facilitates spinal plasticity and maintenance of inflammatory pain. Nat Metab 2024; 6:494-513. [PMID: 38443593 DOI: 10.1038/s42255-024-01001-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Accepted: 01/31/2024] [Indexed: 03/07/2024]
Abstract
Long-lasting pain stimuli can trigger maladaptive changes in the spinal cord, reminiscent of plasticity associated with memory formation. Metabolic coupling between astrocytes and neurons has been implicated in neuronal plasticity and memory formation in the central nervous system, but neither its involvement in pathological pain nor in spinal plasticity has been tested. Here we report a form of neuroglia signalling involving spinal astrocytic glycogen dynamics triggered by persistent noxious stimulation via upregulation of the Protein Targeting to Glycogen (PTG) in spinal astrocytes. PTG drove glycogen build-up in astrocytes, and blunting glycogen accumulation and turnover by Ptg gene deletion reduced pain-related behaviours and promoted faster recovery by shortening pain maintenance in mice. Furthermore, mechanistic analyses revealed that glycogen dynamics is a critically required process for maintenance of pain by facilitating neuronal plasticity in spinal lamina 1 neurons. In summary, our study describes a previously unappreciated mechanism of astrocyte-neuron metabolic communication through glycogen breakdown in the spinal cord that fuels spinal neuron hyperexcitability.
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Affiliation(s)
| | - Shiying Lu
- Institute of Pharmacology, Heidelberg University, Heidelberg, Germany
- Oliver Wyman GmbH, Munich, Germany
| | - Wojciech Ambroziak
- Institute of Pharmacology, Heidelberg University, Heidelberg, Germany
- Department of Translational Disease Understanding, Grünenthal GmbH, Aachen, Germany
| | | | - Jialin Wang
- Institute of Pharmacology, Heidelberg University, Heidelberg, Germany
| | - Anna A DePaoli-Roach
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Anna M Hagenston
- Department of Neurobiology, Interdisciplinary Center for Neurosciences (IZN), Heidelberg University, Heidelberg, Germany
| | - Hagen Wende
- Institute of Pharmacology, Heidelberg University, Heidelberg, Germany
- Taconic Biosciences, Leverkusen, Germany
| | | | - Manuela Simonetti
- Institute of Pharmacology, Heidelberg University, Heidelberg, Germany
| | - Hilmar Bading
- Department of Neurobiology, Interdisciplinary Center for Neurosciences (IZN), Heidelberg University, Heidelberg, Germany
| | - Jürgen G Okun
- Dietmar-Hopp-Metabolic Center, Division of Neuropaediatrics and Metabolic Medicine, Heidelberg University, Heidelberg, Germany
| | - Rohini Kuner
- Institute of Pharmacology, Heidelberg University, Heidelberg, Germany
- Molecular Medicine Partnership Unit (MMPU), European Molecular Biology Laboratory (EMBL), Heidelberg, Germany
| | - Thomas Fleming
- Department of Endocrinology, Diabetology, Metabolism and Clinical Chemistry (Internal Medicine 1), Heidelberg University Hospital, Heidelberg, Germany
- German Center of Diabetes Research (DZD), Neuherberg, Germany
| | - Jan Siemens
- Institute of Pharmacology, Heidelberg University, Heidelberg, Germany.
- Molecular Medicine Partnership Unit (MMPU), European Molecular Biology Laboratory (EMBL), Heidelberg, Germany.
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Perucca E, White HS, Bialer M. New GABA-Targeting Therapies for the Treatment of Seizures and Epilepsy: II. Treatments in Clinical Development. CNS Drugs 2023; 37:781-795. [PMID: 37603261 PMCID: PMC10501930 DOI: 10.1007/s40263-023-01025-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 06/29/2023] [Indexed: 08/22/2023]
Abstract
The inhibitory neurotransmitter γ-aminobutyric acid (GABA) plays an important role in the modulation of neuronal excitability, and a disruption of GABAergic transmission contributes to the pathogenesis of some seizure disorders. Although many currently available antiseizure medications do act at least in part by potentiating GABAergic transmission, there is an opportunity for further research aimed at developing more innovative GABA-targeting therapies. The present article summarises available evidence on a number of such treatments in clinical development. These can be broadly divided into three groups. The first group consists of positive allosteric modulators of GABAA receptors and includes Staccato® alprazolam (an already marketed benzodiazepine being repurposed in epilepsy as a potential rescue inhalation treatment for prolonged and repetitive seizures), the α2/3/5 subtype-selective agents darigabat and ENX-101, and the orally active neurosteroids ETX155 and LPCN 2101. A second group comprises two drugs already marketed for non-neurological indications, which could be repurposed as treatments for seizure disorders. These include bumetanide, a diuretic agent that has undergone clinical trials in phenobarbital-resistant neonatal seizures and for which the rationale for further development in this indication is under debate, and ivermectin, an antiparasitic drug currently investigated in a randomised double-blind trial in focal epilepsy. The last group comprises a series of highly innovative therapies, namely GABAergic interneurons (NRTX-001) delivered via stereotactic cerebral implantation as a treatment for mesial temporal lobe epilepsy, an antisense oligonucleotide (STK-001) aimed at upregulating NaV1.1 currents and restoring the function of GABAergic interneurons, currently tested in a trial in patients with Dravet syndrome, and an adenoviral vector-based gene therapy (ETX-101) scheduled for investigation in Dravet syndrome. Another agent, a subcutaneously administered neuroactive peptide (NRP2945) that reportedly upregulates the expression of GABAA receptor α and β subunits is being investigated, with Lennox-Gastaut syndrome and other epilepsies as proposed indications. The diversity of the current pipeline underscores a strong interest in the GABA system as a target for new treatment development in epilepsy. To date, limited clinical data are available for these investigational treatments and further studies are required to assess their potential value in addressing unmet needs in epilepsy management.
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Affiliation(s)
- Emilio Perucca
- Department of Medicine (Austin Health), Melbourne Brain Centre, The University of Melbourne, 245 Burgundy Street, Melbourne, VIC, 3084, Australia.
- Department of Neuroscience, Central Clinical School, Monash University, Melbourne, VIC, Australia.
| | - H Steve White
- Department of Pharmacy, School of Pharmacy, University of Washington, Seattle, WA, USA
| | - Meir Bialer
- Faculty of Medicine, Institute of Drug Research, School of Pharmacy, The Hebrew University of Jerusalem, Jerusalem, Israel
- David R. Bloom Center for Pharmacy, The Hebrew University of Jerusalem, Jerusalem, Israel
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6
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Rodríguez-Palma EJ, De la Luz-Cuellar YE, Islas-Espinoza AM, Félix-Leyva AE, Shiers SI, García G, Torres-Lopez JE, Delgado-Lezama R, Murbartián J, Price TJ, Granados-Soto V. Activation of α 6 -containing GABA A receptors induces antinociception under physiological and pathological conditions. Pain 2023; 164:948-966. [PMID: 36001074 PMCID: PMC9950299 DOI: 10.1097/j.pain.0000000000002763] [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: 02/23/2022] [Accepted: 08/15/2022] [Indexed: 11/26/2022]
Abstract
ABSTRACT The loss of GABAergic inhibition is a mechanism that underlies neuropathic pain. Therefore, rescuing the GABAergic inhibitory tone through the activation of GABA A receptors is a strategy to reduce neuropathic pain. This study was designed to elucidate the function of the spinal α 6 -containing GABA A receptor in physiological conditions and neuropathic pain in female and male rats. Results show that α 6 -containing GABA A receptor blockade or transient α 6 -containing GABA A receptor knockdown induces evoked hypersensitivity and spontaneous pain in naive female rats. The α 6 subunit is expressed in IB4 + and CGRP + primary afferent neurons in the rat spinal dorsal horn and dorsal root ganglia but not astrocytes. Nerve injury reduces α 6 subunit protein expression in the central terminals of the primary afferent neurons and dorsal root ganglia, whereas intrathecal administration of positive allosteric modulators of the α 6 -containing GABA A receptor reduces tactile allodynia and spontaneous nociceptive behaviors in female, but not male, neuropathic rats and mice. Overexpression of the spinal α 6 subunit reduces tactile allodynia and restores α 6 subunit expression in neuropathic rats. Positive allosteric modulators of the α 6 -containing GABA A receptor induces a greater antiallodynic effect in female rats and mice compared with male rats and mice. Finally, α 6 subunit is expressed in humans. This receptor is found in CGRP + and P2X3 + primary afferent fibers but not astrocytes in the human spinal dorsal horn. Our results suggest that the spinal α 6 -containing GABA A receptor has a sex-specific antinociceptive role in neuropathic pain, suggesting that this receptor may represent an interesting target to develop a novel treatment for neuropathic pain.
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Affiliation(s)
- Erick J. Rodríguez-Palma
- Neurobiology of Pain Laboratory, Departamento de Farmacobiología, Cinvestav, South Campus, Mexico City, Mexico
| | - Yarim E. De la Luz-Cuellar
- Neurobiology of Pain Laboratory, Departamento de Farmacobiología, Cinvestav, South Campus, Mexico City, Mexico
| | - Ana M. Islas-Espinoza
- Neurobiology of Pain Laboratory, Departamento de Farmacobiología, Cinvestav, South Campus, Mexico City, Mexico
| | - Adalberto E. Félix-Leyva
- Neurobiology of Pain Laboratory, Departamento de Farmacobiología, Cinvestav, South Campus, Mexico City, Mexico
- Facultad de Biología, Universidad Autónoma de Sinaloa, Culiacán, Sinaloa, Mexico
| | - Stephanie I. Shiers
- School of Behavioral and Brain Sciences, Center for Advanced Pain Studies, University of Texas at Dallas, Richardson, TX, USA
| | - Guadalupe García
- Departamento de Farmacobiología, Cinvestav, South Campus, Mexico City, Mexico
| | - Jorge E. Torres-Lopez
- Laboratorio de Mecanismos de Dolor, División Académica de Ciencias de la Salud, Universidad Juárez Autónoma de Tabasco, Villahermosa, Tabasco, Mexico
| | - Rodolfo Delgado-Lezama
- Departamento de Fisiología, Biofísica y Neurociencias, Cinvestav, Zacatenco, Mexico City, Mexico
| | - Janet Murbartián
- Departamento de Farmacobiología, Cinvestav, South Campus, Mexico City, Mexico
| | - Theodore J. Price
- School of Behavioral and Brain Sciences, Center for Advanced Pain Studies, University of Texas at Dallas, Richardson, TX, USA
| | - Vinicio Granados-Soto
- Neurobiology of Pain Laboratory, Departamento de Farmacobiología, Cinvestav, South Campus, Mexico City, Mexico
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7
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Asgharpour-Masouleh N, Rezayof A, Alijanpour S, Delphi L. Pharmacological activation of mediodorsal thalamic GABA-A receptors modulates morphine/cetirizine-induced changes in the prefrontal cortical GFAP expression in a rat model of neuropathic pain. Behav Brain Res 2023; 438:114213. [PMID: 36372242 DOI: 10.1016/j.bbr.2022.114213] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Revised: 10/21/2022] [Accepted: 11/08/2022] [Indexed: 11/13/2022]
Abstract
The present study investigated the involvement of mediodorsal thalamic (MD) GABA-A receptors in cetirizine/morphine-induced anti-allodynia using a rat model of neuropathic pain. To assess the importance of the prefrontal cortex (PFC) for chronic pain processing, its expression level changes of glial fibrillary acidic protein (GFAP) were measured following drug treatments. Each animal was subjected to chronic constriction of the sciatic nerve surgery simultaneously with the MD cannulation under stereotaxic surgery. The results showed that the administration of morphine (3-5 mg/kg) or cetirizine (1-3 mg/kg) produced significant analgesia in neuropathic rats. Systemic administration of cetirizine (2.5 and 3 mg/kg) potentiated the analgesic response to a low and intolerance dose of morphine (3 mg/kg). Intra-MD microinjection of muscimol, a selective GABA-A receptor agonist (0.005-0.01 μg/rat), increased the cetirizine/morphine-induced anti-allodynia, while muscimol by itself did not affect neuropathic pain. The neuropathic pain was associated with the increased PFC expression level of GFAP, suggesting the impact of chronic pain on PFC glial management. Interestingly, the anti-allodynia was associated with a decrease in the PFC expression level of GFAP under the drugs' co-administration. Thus, cetirizine has a significant potentiating effect on morphine response in neuropathic pain via interacting with the MD GABA-A receptors. It seems that neuropathic pain affects the prefrontal cortex GFAP signaling pathway. In clinical studies, these findings can be considered to create a combination therapy with low doses of GABA-A receptor agonist plus cetirizine and morphine to manage neuropathic pain.
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Affiliation(s)
| | - Ameneh Rezayof
- Department of Animal Biology, School of Biology, College of Science, University of Tehran, Tehran, Iran.
| | - Sakineh Alijanpour
- Department of Biology, Faculty of Science, Gonbad Kavous University, Gonbad Kavous, Iran
| | - Ladan Delphi
- Department of Animal Biology, School of Biology, College of Science, University of Tehran, Tehran, Iran
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8
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Osuntokun OS, Olayiwola G, Adekomi DA, Oyeyipo IP, Ayoka AO. Preliminary assessment of proanthocyanidin isolates of Vitis vinifera seed on the central nervous system of male Albino mice. Epilepsy Behav 2022; 127:108521. [PMID: 35065391 DOI: 10.1016/j.yebeh.2021.108521] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Revised: 10/25/2021] [Accepted: 12/19/2021] [Indexed: 11/03/2022]
Abstract
This study evaluated the potential neurobehavioral effects of proanthocyanidin-rich-fraction (PRF) obtained from Vitis vinifera seed in male Albino mice. Adult (2½- to 3-month old) male Albino mice were treated with PRF (200, 100, 50 mg/kg) and subjected to diverse behavioral models specially designed for the assessment of central nervous system-acting agents. One-shot intraperitoneal (i.p) injection of PRF (200 and 100 mg/kg) decreased the rectal temperature, exploratory activities (locomotion, rearing, and grooming), anxiety-like responses (% open-arm time, open-arm entries but decreased the total number of enclosed arm times). However, acute i.p administration of PRF decreased the total score of apomorphine-induced stereotyped behaviors, latency to hexobarbitone-induced sleep, and increased the total sleep duration. Moreover, indices of convulsion (tonic flexion, extension, clonic convulsion, stupor, and recovery time) were decreased in the PRF treatment groups, especially the PRF (50 mg/kg)-treated mice. Based on these present findings, it could therefore be inferred that systemic administration of PRF of V. vinifera seed origin induces diverse modification on the behaviors of the treated mice stemming from anxiolytic, anticonvulsant, sedative, and decrease in core temperature.
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Affiliation(s)
- Opeyemi Samson Osuntokun
- Department of Physiology, Faculty of Basic Medical Sciences, Osun State University, Osogbo, Nigeria; Department of Physiological Sciences, Faculty of Basic Medical Sciences, Obafemi Awolowo University, Ile-Ife, Osun State, Nigeria.
| | - Gbola Olayiwola
- Department of Clinical Pharmacy and Pharmacy Administration, Faculty of Pharmacy, Obafemi Awolowo University, Ile-Ife, Osun State, Nigeria
| | - Damilare Adedayo Adekomi
- Department of Anatomy, Faculty of Basic Medical Sciences, Osun State University, Osogbo, Nigeria
| | - Ibukun Peter Oyeyipo
- Department of Physiology, Faculty of Basic Medical Sciences, Osun State University, Osogbo, Nigeria
| | - Abiodun Oladele Ayoka
- Department of Physiological Sciences, Faculty of Basic Medical Sciences, Obafemi Awolowo University, Ile-Ife, Osun State, Nigeria
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9
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Engin E. GABA A receptor subtypes and benzodiazepine use, misuse, and abuse. Front Psychiatry 2022; 13:1060949. [PMID: 36713896 PMCID: PMC9879605 DOI: 10.3389/fpsyt.2022.1060949] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/04/2022] [Accepted: 12/29/2022] [Indexed: 01/14/2023] Open
Abstract
Benzodiazepines have been in use for over half a century. While they remain highly prescribed, their unfavorable side-effect profile and abuse liability motivated a search for alternatives. Most of these efforts focused on the development of benzodiazepine-like drugs that are selective for specific GABAA receptor subtypes. While there is ample evidence that subtype-selective GABAA receptor ligands have great potential for providing symptom relief without typical benzodiazepine side-effects, it is less clear whether subtype-selective targeting strategies can also reduce misuse and abuse potential. This review focuses on the three benzodiazepine properties that are relevant to the DSM-5-TR criteria for Sedative, Hypnotic, or Anxiolytic Use Disorder, namely, reinforcing properties of benzodiazepines, maladaptive behaviors related to benzodiazepine use, and benzodiazepine tolerance and dependence. We review existing evidence regarding the involvement of different GABAA receptor subtypes in each of these areas. The reviewed studies suggest that α1-containing GABAA receptors play an integral role in benzodiazepine-induced plasticity in reward-related brain areas and might be involved in the development of tolerance and dependence to benzodiazepines. However, a systematic comparison of the contributions of all benzodiazepine-sensitive GABAA receptors to these processes, a mechanistic understanding of how the positive modulation of each receptor subtype might contribute to the brain mechanisms underlying each of these processes, and a definitive answer to the question of whether specific chronic modulation of any given subtype would result in some or all of the benzodiazepine effects are currently lacking from the literature. Moreover, how non-selective benzodiazepines might lead to the maladaptive behaviors listed in DSM and how different GABAA receptor subtypes might be involved in the development of these behaviors remains unexplored. Considering the increasing burden of benzodiazepine abuse, the common practice of benzodiazepine misuse that leads to severe dependence, and the current efforts to generate side-effect free benzodiazepine alternatives, there is an urgent need for systematic, mechanistic research that provides a better understanding of the brain mechanisms of benzodiazepine misuse and abuse, including the involvement of specific GABAA receptor subtypes in these processes, to establish an informed foundation for preclinical and clinical efforts.
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Affiliation(s)
- Elif Engin
- Stress Neurobiology Laboratory, Division of Basic Neuroscience, McLean Hospital, Belmont, MA, United States.,Department of Psychiatry, Harvard Medical School, Boston, MA, United States
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10
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Ali A, Nasir A, Shah SWA, Khalil AAK, Ahn MJ, Shah SMM, Subhan F, Faheem M, Sajjad W, Shoaib M, Ahmad S, Nazir N, Nisar M. Evaluation of antinociceptive activity of Ilex dipyrena Wall. in mice. BMC Complement Med Ther 2021; 21:184. [PMID: 34210323 PMCID: PMC8247168 DOI: 10.1186/s12906-021-03357-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Accepted: 06/15/2021] [Indexed: 01/01/2023] Open
Abstract
BACKGROUND In order to find a new natural resource for pain-relief, the analgesic effects of Ilex dipyrena crude extract, fractions, and subfractions were evaluated in in-vivo mouse models with possible mechanism of action. METHODS Analgesic effects of crude extract (100 and 200 mg/kg body weight), fractions and subfractions (75 mg/kg body weight) were screened using heat-induced (tail-immersion and hot plate test) and chemical-induced (formalin and acetic acid) nociception models in mice. The samples were also tested for the elucidation of a possible mechanism through opioidergic and GABAergic systems. RESULTS The administration of crude extract, fractions and subfractions produced analgesic responses in acetic acid, formalin, tail immersion, and hot plate model for pain similar to those obtained with the standard. Naloxone antagonized the antinociceptive effects of the tested samples, whereas bicuculline showed partial inhibition. Considering the analgesic response, crude extract, fractions, and subfractions demonstrated promising inhibitory activity against all test models for pain, which was further supported by the possible involvement of opioidergic and GABAergic systems. CONCLUSION The results suggest that this plant may be useful in the development of new analgesic drugs. Further research with regard to the isolation of bioactive compounds is required to verify these findings.
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Affiliation(s)
- Amjad Ali
- Department of Botany, University of Malakand, Dir (Lower), Chakdara, Khyber Pakhtunkhwa, 18800, Pakistan
| | - Abdul Nasir
- Department of Molecular Science and Technology, Ajou University, Suwon, 16499, Republic of Korea
| | - Syed Wadood Ali Shah
- Department of Pharmacy, University of Malakand, Dir (Lower), Chakdara, Khyber Pakhtunkhwa, 18800, Pakistan
| | - Atif Ali Khan Khalil
- Department of Biological Sciences, National University of Medical Sciences, Rawalpindi, 46000, Pakistan.
| | - Mi-Jeong Ahn
- College of Pharmacy and Research Institute of Pharmaceutical Sciences, Gyeongsang National University, Jinju, Gyeongsangnam-do, 52828, South Korea
| | | | - Fazli Subhan
- Department of Biological Sciences, National University of Medical Sciences, Rawalpindi, 46000, Pakistan
| | - Muhammad Faheem
- Department of Biological Sciences, National University of Medical Sciences, Rawalpindi, 46000, Pakistan
| | - Wasim Sajjad
- Department of Biological Sciences, National University of Medical Sciences, Rawalpindi, 46000, Pakistan
| | - Mohammad Shoaib
- Department of Pharmacy, University of Malakand, Dir (Lower), Chakdara, Khyber Pakhtunkhwa, 18800, Pakistan
| | - Saeed Ahmad
- Department of Zoology, University of Malakand, Dir (Lower), Chakdara, Khyber Pakhtunkhwa, 18800, Pakistan
| | - Nausheen Nazir
- Department of Biochemistry, University of Malakand, Dir (Lower), Chakdara, Khyber Pakhtunkhwa, 18800, Pakistan
| | - Mohammad Nisar
- Department of Botany, University of Malakand, Dir (Lower), Chakdara, Khyber Pakhtunkhwa, 18800, Pakistan.
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11
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Zhou Z, Qiu N, Ou Y, Wei Q, Tang W, Zheng M, Xing Y, Li JJ, Ling Y, Li J, Zhu Q. N-Demethylsinomenine, an active metabolite of sinomenine, attenuates chronic neuropathic and inflammatory pain in mice. Sci Rep 2021; 11:9300. [PMID: 33927244 PMCID: PMC8085237 DOI: 10.1038/s41598-021-88521-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2021] [Accepted: 04/12/2021] [Indexed: 01/07/2023] Open
Abstract
Chronic pain is a significant public health problem that afflicts nearly 30% of the global population, but current pharmacotherapies are insufficient. Previous report indicated that N-demethylsinomenine, an active metabolite of sinomenine, is efficacious against postoperative pain. The present study investigated whether N-demethylsinomenine is effective for chronic painful conditions or whether repeated treatment alters its effect. Both chronic constriction injury (CCI) surgery and complete Freund’s adjuvant (CFA) intraplantar injection induced significant and reliable mechanical allodynia at least for 7 days. Acute treatment with N-demethylsinomenine (10–40 mg/kg, i.p.) dose-dependently attenuated the mechanical allodynia both in CCI-induced neuropathic pain and CFA-induced inflammatory pain in mice. The potency of N-demethylsinomenine for reducing CFA-induced mechanical allodynia was slightly higher than sinomenine. During the period of repeated treatment, N-demethylsinomenine maintained its anti-allodynic effect against both neuropathic and inflammatory pain without producing carry-over effect. Pretreatment with bicuculline, a selective γ-aminobutyric acid type A (GABAA) receptor antagonist, almost completely blocked the anti-allodynia of N-demethylsinomenine (40 mg/kg) both in CCI and CFA-treated mice. Our findings indicated that N-demethylsinomenine exhibits GABAA receptor-mediated anti-allodynic effects in mouse models of neuropathic and inflammatory pain, suggesting it may be a useful novel pharmacotherapy for the control of chronic pain.
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Affiliation(s)
- Zhiyong Zhou
- School of Pharmacy, Nantong University, 19 Qixiu Road, Nantong, 226001, Jiangsu Province, China
| | - Nanqing Qiu
- School of Pharmacy, Nantong University, 19 Qixiu Road, Nantong, 226001, Jiangsu Province, China
| | - Yuntao Ou
- School of Pharmacy, Nantong University, 19 Qixiu Road, Nantong, 226001, Jiangsu Province, China
| | - Qianqian Wei
- School of Pharmacy, Nantong University, 19 Qixiu Road, Nantong, 226001, Jiangsu Province, China
| | - Wenting Tang
- School of Pharmacy, Nantong University, 19 Qixiu Road, Nantong, 226001, Jiangsu Province, China
| | - Mingcong Zheng
- School of Pharmacy, Nantong University, 19 Qixiu Road, Nantong, 226001, Jiangsu Province, China
| | - Yaluan Xing
- School of Pharmacy, Nantong University, 19 Qixiu Road, Nantong, 226001, Jiangsu Province, China
| | - Jie-Jia Li
- School of Pharmacy, Nantong University, 19 Qixiu Road, Nantong, 226001, Jiangsu Province, China
| | - Yong Ling
- School of Pharmacy, Nantong University, 19 Qixiu Road, Nantong, 226001, Jiangsu Province, China
| | - Junxu Li
- School of Pharmacy, Nantong University, 19 Qixiu Road, Nantong, 226001, Jiangsu Province, China.
| | - Qing Zhu
- School of Pharmacy, Nantong University, 19 Qixiu Road, Nantong, 226001, Jiangsu Province, China.
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12
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Alijanpour S, Jafaripour S, Ghasemzadeh Z, Khakpai F, Zarrindast MR. Harmaline potentiates morphine-induced antinociception via affecting the ventral hippocampal GABA-A receptors in mice. Eur J Pharmacol 2020; 893:173806. [PMID: 33345854 DOI: 10.1016/j.ejphar.2020.173806] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2019] [Revised: 12/06/2020] [Accepted: 12/10/2020] [Indexed: 11/13/2022]
Abstract
Morphine is one of the most effective medications for treatment of pain, but its side effects limit its use. Therefore, identification of new strategies that can enhance morphine-induced antinociception and/or reduce its side effects will help to develop therapeutic approaches for pain relief. Considering antinociceptive efficacy of harmaline and also highlighted the important role of GABA-A receptors in the pain perception, this research aimed to determine whether the ventral hippocampal (vHip) GABA-A receptors are involved in the possible harmaline-induced enhancement of morphine antinociception. To achieve this, vHip regions of adult male mice were bilaterally cannulated and pain sensitivity was measured in a tail-flick apparatus. Intraperitoneally administration of morphine (0, 2, 4 and 6 mg/kg) or harmaline (0, 1.25, 5 and 10 mg/kg) increased the percentage of maximal possible effect (%MPE) and induced antinociception. Interestingly, co-administration of sub-effective doses of harmaline (5 mg/kg) and morphine (2 mg/kg) induced antinociception. Intra-vHip microinjection of muscimol (0, 200 and 300 ng/mice), a GABA-A receptor agonist, enhanced the anti-nociceptive effects of harmaline (2.5 mg/kg)+morphine (2 mg/kg) combination. Microinjection of the same doses of muscimol into the vHip by itself did not alter tail-flick latency. Intra-vHip microinjection of bicuculline (100 ng/mouse), a GABA-A receptor antagonist, did not cause a significant change in MPE%. Bicuculline (60 and 100 ng/mouse, intra-vHip) was administered with the harmaline (5 mg/kg)+morphine (2 mg/kg), and inhibited the potentiating effect of harmaline on morphine response. These findings favor the notion that GABAergic mechanisms in the vHip facilitate harmaline-induced potentiation of morphine response in the tail-flick test in part through GABA-A receptors. These findings shall provide insights and strategies into the development of pain suppressing drugs.
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Affiliation(s)
- Sakineh Alijanpour
- Department of Biology, Faculty of Science, Gonbad Kavous University, Gonbad Kavous, Iran.
| | - Samira Jafaripour
- Department of Biology, North Tehran Branch, Islamic Azad University, Tehran, Iran
| | - Zahra Ghasemzadeh
- Department of Animal Biology, School of Biology, College of Science, University of Tehran, Tehran, Iran
| | - Fatemeh Khakpai
- Cognitive and Neuroscience Research Center (CNRC), Tehran Medical Sciences, Islamic Azad University, Tehran, Iran
| | - Mohammad-Reza Zarrindast
- Department of Pharmacology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran; Iranian National Center for Addiction Studies, Tehran University of Medical Sciences, Tehran, Iran; Endocrinology and Metabolism Research Center, Endocrinology and Metabolism Clinical Sciences Institute, Tehran University of Medical Sciences, Tehran, Iran
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13
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Garrido-Suárez BB, Garrido G, Castro-Labrada M, Merino N, Valdés O, Pardo Z, Ochoa-Rodríguez E, Verdecia-Reyes Y, Delgado-Hernández R, Godoy-Figueiredo J, Ferreira SH. Anti-hypernociceptive and anti-inflammatory effects of JM-20: A novel hybrid neuroprotective compound. Brain Res Bull 2020; 165:185-197. [PMID: 33096198 DOI: 10.1016/j.brainresbull.2020.10.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Revised: 10/05/2020] [Accepted: 10/06/2020] [Indexed: 12/18/2022]
Abstract
The present study examines the possible effect of the novel hybrid molecule JM-20 (3-ethoxycarbonyl-2-methyl-4-(2-nitrophenyl)-411-dihydro-1H-pyrido[2,3-b] [1,5] benzodiazepine) on pain-related behaviours in a persistent pain model (5% formalin test) and in the neutrophil migration events during the inflammatory process. It further introduces JM-20 in a chronic constriction injury (CCI) model to clarify the possible subjacent mechanisms with its consequent clinical relevance. A single administration of JM-20 (20 or 40 mg/kg, per os [p.o.]) decreased licking/biting exclusively in the tonic phase of the formalin test in a GABA/benzodiazepine (BZD) receptor antagonist flumazenil-sensitive manner. JM-20 reduced in vivo neutrophil migration, rolling and adhesion to the endothelium induced by intraperitoneal administration of carrageenan in mice. In addition, plasma extravasation and tumour necrosis factor alpha production in the peritoneal fluid were decreased. Treatment with JM-20 (20 mg/kg, p.o.) for 7 days after CCI reduced mechanical hypersensitivity in a NG-monomethyl-l-arginine (L-NMMA)/methylene blue/glibenclamide-sensitive manner. Histopathological signs of Wallerian degeneration (WD) of the sciatic nerve were also attenuated, as well as interleukin-1 beta release in the spinal cord. The nitrate/nitrite concentration was increased centrally and did not show differences at the peripheral nerve level. The findings of this study suggest JM-20 can decrease persistent pain. A transient activity of its BDZ portion on nociceptive pathways mediated by GABA/BDZ receptors in association with its anti-inflammatory properties could be at least partially involved in this effect. JM-20 decreased CCI-induced mechanical hypersensitivity via the l-arginine/nitric oxide (NO)/cyclic GMP-sensitive ATP-sensitive potassium channel pathway. Its neuroprotective ability by preventing WD could be implicated in its anti-neuropathic mechanisms.
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Affiliation(s)
- Bárbara B Garrido-Suárez
- Centro de Investigación y Desarrollo de Medicamentos, Ave 26, No. 1605 Boyeros y Puentes Grandes, CP, 10600, La Habana, Cuba.
| | - Gabino Garrido
- Departamento de Ciencias Farmacéuticas, Facultad de Ciencias, Edificio Ñ3, Universidad Católica del Norte, Angamos, 0610, Antofagasta, Chile.
| | - Marian Castro-Labrada
- Centro de Investigación y Desarrollo de Medicamentos, Ave 26, No. 1605 Boyeros y Puentes Grandes, CP, 10600, La Habana, Cuba
| | - Nelson Merino
- Centro de Investigación y Desarrollo de Medicamentos, Ave 26, No. 1605 Boyeros y Puentes Grandes, CP, 10600, La Habana, Cuba
| | - Odalys Valdés
- Centro de Investigación y Desarrollo de Medicamentos, Ave 26, No. 1605 Boyeros y Puentes Grandes, CP, 10600, La Habana, Cuba
| | - Zenia Pardo
- Centro de Investigación y Desarrollo de Medicamentos, Ave 26, No. 1605 Boyeros y Puentes Grandes, CP, 10600, La Habana, Cuba
| | - Estael Ochoa-Rodríguez
- Laboratorio de Síntesis Orgánica de La Facultad de Química de La Universidad de La Habana, Zapata s/n entre G y Carlitos Aguirre, Vedado Plaza de la Revolución, CP, 10400, La Habana, Cuba
| | - Yamila Verdecia-Reyes
- Laboratorio de Síntesis Orgánica de La Facultad de Química de La Universidad de La Habana, Zapata s/n entre G y Carlitos Aguirre, Vedado Plaza de la Revolución, CP, 10400, La Habana, Cuba
| | - René Delgado-Hernández
- Centro de Investigación y Desarrollo de Medicamentos, Ave 26, No. 1605 Boyeros y Puentes Grandes, CP, 10600, La Habana, Cuba
| | - Jozi Godoy-Figueiredo
- Department of Pharmacology, Faculty of Medicine of Ribeirão Preto University of São Paulo, Avenida Bandeirantes, 3900, 14049-900, Ribeirão Preto, SP, Brazil
| | - Sergio H Ferreira
- Department of Pharmacology, Faculty of Medicine of Ribeirão Preto University of São Paulo, Avenida Bandeirantes, 3900, 14049-900, Ribeirão Preto, SP, Brazil
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14
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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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15
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Alghamdi S. Antinociceptive Effect of the Citrus Flavonoid Eriocitrinon Postoperative Pain Conditions. J Pain Res 2020; 13:805-815. [PMID: 32368133 PMCID: PMC7183786 DOI: 10.2147/jpr.s250391] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Accepted: 04/07/2020] [Indexed: 12/29/2022] Open
Abstract
BACKGROUND Postoperative pain remains a major clinical problem as there are limited analgesic strategies that have been proven to be effective in preventing and relieving this type of pain. Natural products, including flavonoids, have distinct pharmacological properties and play an important role in the discovery of analgesic drugs. MATERIALS AND METHODS In this study, the flavonoid eriocitrin (eriodictyol 7-O-rutinoside), which is the main flavonoid in lemon fruit (Citrus limon), was mechanistically investigated for its prospective antinociceptive effect in a mouse model of postoperative pain. The antinociceptive property was evaluated by utilizing both tonic (acetic acid-induced writhing behavior) and phasic (hot-plate) nociception modalities. The hindpaw incisional surgery was performed and hyperalgesia was assessed using von Frey filaments. RESULTS The tested doses of eriocitrin significantly attenuated (P<0.01, P<0.001) the chemically-induced tonic visceral nociception (5, 10, 15, and 30 mg/kg) and acute phasic thermal nociception (10, 15, and 30 mg/kg). A significant dose-dependent reduction in the incisional nociceptive hyperalgesia was exhibited by eriocitrin, with a marked antinociception observed at doses of 15 mg/kg (P<0.05 during 30-60 minutes) and 30 mg/kg (P<0.05, P<0.01 during 30-120 minutes). CONCLUSION The antinociceptive effect of eriocitrin (30 mg/kg) was strongly blocked by the antagonists of the opioid receptor, naltrexone, and GABAA receptor, bicuculline, thereby suggesting the involvement of opioidergic and GABAergic mechanisms in the nociception, reducing proclivity of eriocitrin during transmission of incisional nociception. These results concluded that eriocitrin has a potent antinociceptive effect in postoperative pain conditions, probably mediated through opioid and GABAA receptors.
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Affiliation(s)
- Saad Alghamdi
- Laboratory Medicine Department, Faculty of Applied Medical Sciences, Umm Al-Qura University, Makkah21955, Saudi Arabia
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16
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Wilke BU, Kummer KK, Leitner MG, Kress M. Chloride - The Underrated Ion in Nociceptors. Front Neurosci 2020; 14:287. [PMID: 32322187 PMCID: PMC7158864 DOI: 10.3389/fnins.2020.00287] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2019] [Accepted: 03/12/2020] [Indexed: 01/06/2023] Open
Abstract
In contrast to pain processing neurons in the spinal cord, where the importance of chloride conductances is already well established, chloride homeostasis in primary afferent neurons has received less attention. Sensory neurons maintain high intracellular chloride concentrations through balanced activity of Na+-K+-2Cl– cotransporter 1 (NKCC1) and K+-Cl– cotransporter 2 (KCC2). Whereas in other cell types activation of chloride conductances causes hyperpolarization, activation of the same conductances in primary afferent neurons may lead to inhibitory or excitatory depolarization depending on the actual chloride reversal potential and the total amount of chloride efflux during channel or transporter activation. Dorsal root ganglion (DRG) neurons express a multitude of chloride channel types belonging to different channel families, such as ligand-gated, ionotropic γ-aminobutyric acid (GABA) or glycine receptors, Ca2+-activated chloride channels of the anoctamin/TMEM16, bestrophin or tweety-homolog family, CLC chloride channels and transporters, cystic fibrosis transmembrane conductance regulator (CFTR) as well as volume-regulated anion channels (VRACs). Specific chloride conductances are involved in signal transduction and amplification at the peripheral nerve terminal, contribute to excitability and action potential generation of sensory neurons, or crucially shape synaptic transmission in the spinal dorsal horn. In addition, chloride channels can be modified by a plethora of inflammatory mediators affecting them directly, via protein-protein interaction, or through signaling cascades. Since chloride channels as well as mediators that modulate chloride fluxes are regulated in pain disorders and contribute to nociceptor excitation and sensitization it is timely and important to emphasize their critical role in nociceptive primary afferents in this review.
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Affiliation(s)
- Bettina U Wilke
- Institute of Physiology, Department of Physiology and Medical Physics, Medical University of Innsbruck, Innsbruck, Austria
| | - Kai K Kummer
- Institute of Physiology, Department of Physiology and Medical Physics, Medical University of Innsbruck, Innsbruck, Austria
| | - Michael G Leitner
- Institute of Physiology, Department of Physiology and Medical Physics, Medical University of Innsbruck, Innsbruck, Austria
| | - Michaela Kress
- Institute of Physiology, Department of Physiology and Medical Physics, Medical University of Innsbruck, Innsbruck, Austria
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17
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Matthey A, Daali Y, Curtin F, Poncet A, Desmeules J, Besson M. GABAergic modulation of secondary hyperalgesia: A randomized controlled 4-way crossover trial with the α2-subunit preferring GABA positive allosteric modulator, N-desmethyl-clobazam in healthy volunteers. Eur J Pain 2020; 24:1094-1106. [PMID: 32171038 DOI: 10.1002/ejp.1554] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2019] [Revised: 02/28/2020] [Accepted: 03/03/2020] [Indexed: 11/10/2022]
Abstract
The antihyperalgesic and sedative effects of the α2-subunit preferring GABAA positive allosteric modulator (GAM), N-desmethyl-clobazam (NDMC), 20 and 60 mg, were assessed in a randomized, placebo and active-controlled (clonazepam 1,5 mg), 4-way crossover study, in healthy volunteers, using the ultraviolet B-induced experimental pain model. Single (20, 40, 60 mg) and repeated doses (20 mg over 15 days) of NDMC pharmacokinetics were evaluated. Thirty-two subjects participated in the study. Primary outcome parameter was maximal change in the area of cutaneous UVB irradiation-induced secondary hyperalgesia (ASH). ASH decreased under all treatments. Mean (SD) relative change was 79 (22)%, 83 (24)%, 77 (30)% and 92 (16)% for placebo, NDMC20, NDMC60 and clonazepam, respectively. Neither absolute change nor relative change in ASH was significantly different between NDMC60 and placebo (mean difference = 2.3 cm2 [95% CI 4.0-8.5], p = .462 and 0.4% [-11.9 to 12.6], p = .952, respectively). An overall treatment effect was found on level of sedation. Compared to placebo, sedation was higher under clonazepam (mean difference = 39 mm [30-49] on a visual analogue scale, p < .001) while NDMC was free of sedative effect. NDMC pharmacokinetics after single doses showed poor absorption, but was linear. Steady-state plasma concentrations of NDMC20 were attained within 14 days, with low between-subjects variability. Mean steady-state concentration (CS-S , SD) reached 209 (22) ng/ml. NDMC absence of sedative effect and its overall well-characterized safety coming from years of utilization as a metabolite from clobazam, raise the prospect of dose escalating trials in patients to quantify its clinical utility. SIGNIFICANCE: This article, presenting the Phase I data of the new antihyperalgesic compound, α2-subunit GABAA positive allosteric modulator, N-desmethyl-clobazam (NDMC) is exploring the modulation of a new target in the treatment of neuropathic pain. Based on these results and on its preclinical properties NDMC would qualify as a good tool compound to seek confirmation of the clinical utility of selective GABA allosteric modulators in neuropathic pain patients.
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Affiliation(s)
- Alain Matthey
- Division of Clinical Pharmacology and Toxicology, Multidisciplinary Pain Center, Geneva University Hospitals, Geneva, Switzerland
| | - Youssef Daali
- Division of Clinical Pharmacology and Toxicology, Multidisciplinary Pain Center, Geneva University Hospitals, Geneva, Switzerland.,Faculty of Medicine, Geneva University, Geneva, Switzerland
| | - François Curtin
- Division of Clinical Pharmacology and Toxicology, Multidisciplinary Pain Center, Geneva University Hospitals, Geneva, Switzerland.,Faculty of Medicine, Geneva University, Geneva, Switzerland
| | - Antoine Poncet
- Division of Clinical Epidemiology, Geneva University Hospitals, Geneva, Switzerland
| | - Jules Desmeules
- Division of Clinical Pharmacology and Toxicology, Multidisciplinary Pain Center, Geneva University Hospitals, Geneva, Switzerland.,Faculty of Medicine, Geneva University, Geneva, Switzerland
| | - Marie Besson
- Division of Clinical Pharmacology and Toxicology, Multidisciplinary Pain Center, Geneva University Hospitals, Geneva, Switzerland.,Faculty of Medicine, Geneva University, Geneva, Switzerland
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18
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Owen RM, Blakemore DC, Cao L, Flanagan N, Fish R, Gibson KR, Gurrell R, Huh CW, Kammonen J, Mortimer-Cassen E, Nickolls S, Omoto K, Owen DR, Pike A, Pryde DC, Reynolds D, Roeloffs R, Rose CR, Stead C, Takeuchi M, Warmus JS, Watson C. Design and identification of a novel, functionally subtype selective GABAApositive allosteric modulator (PF-06372865). J Med Chem 2019; 62:5773-5796. [DOI: 10.1021/acs.jmedchem.9b00322] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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19
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Antinociceptive effect of flavonol and a few structurally related dimethoxy flavonols in mice. Inflammopharmacology 2019; 27:1155-1167. [PMID: 30850920 DOI: 10.1007/s10787-019-00579-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2018] [Accepted: 02/26/2019] [Indexed: 10/27/2022]
Abstract
Previous reports suggest flavonoids as potent analgesic compounds. Based on these observations, the present study investigated the antinociceptive action of flavonol, 3', 4'-dimethoxy flavonol, 6, 3'-dimethoxy flavonol, 7, 2'-dimethoxy flavonol, and 7, 3'-dimethoxy flavonol and the possible mechanisms involved in these effects. The antinociceptive effect of the investigated compounds in doses of 25, 50, 100, and 200 mg/kg was evaluated in male Swiss albino mice using the acetic acid test, formalin-induced nociception, and hot water tail immersion test. The role of opioid, tryptaminergic, adrenergic, dopaminergic, GABAergic, and K+ATP channels in producing the antinociceptive effect was also studied using appropriate interacting agents. Treatment with flavonol and dimethoxy flavonols resulted in a significant reduction in the number of abdominal constrictions in the acetic acid test, a significant inhibition of the paw-licking/biting response time in both the phases of formalin nociception and also a significant increase in mean reaction time in the hot water tail immersion test. These observations revealed the antinociceptive effect of dimethoxy flavonols. The role of opioid, serotonergic (5HT3), and dopaminergic system was identified in the antinociceptive effect of flavonol and all dimethoxy derivatives investigated. In addition, the role of GABAergic, K+ATP channel, and α-2 adrenergic mechanisms were also observed in the antinociceptive action of some of the investigated compounds. The present study identified the antinociceptive effect of flavonol and dimethoxy flavonols in mice acting through different neuronal pathways.
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Abstract
γ-aminobutyric acid has become one of the most widely known neurotransmitter molecules in the brain over the last 50 years, recognised for its pivotal role in inhibiting neural excitability. It emerged from studies of crustacean muscle and neurons before its significance to the mammalian nervous system was appreciated. Now, after five decades of investigation, we know that most neurons are γ-aminobutyric-acid-sensitive, it is a cornerstone of neural physiology and dysfunction to γ-aminobutyric acid signalling is increasingly documented in a range of neurological diseases. In this review, we briefly chart the neurodevelopment of γ-aminobutyric acid and its two major receptor subtypes: the γ-aminobutyric acidA and γ-aminobutyric acidB receptors, starting from the humble invertebrate origins of being an 'interesting molecule' acting at a single γ-aminobutyric acid receptor type, to one of the brain's most important neurochemical components and vital drug targets for major therapeutic classes of drugs. We document the period of molecular cloning and the explosive influence this had on the field of neuroscience and pharmacology up to the present day and the production of atomic γ-aminobutyric acidA and γ-aminobutyric acidB receptor structures. γ-Aminobutyric acid is no longer a humble molecule but the instigator of rich and powerful signalling processes that are absolutely vital for healthy brain function.
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Affiliation(s)
- Trevor G Smart
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, UK
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Yokoshima Y, Sumitani M, Nishizawa D, Nagashima M, Ikeda K, Kato R, Hozumi J, Abe H, Azuma K, Tsuchida R, Yamada Y. Gamma-aminobutyric acid transaminase genetic polymorphism is a candidate locus for responsiveness to opioid analgesics in patients with cancer pain: An exploratory study. Neuropsychopharmacol Rep 2018; 38:175-181. [PMID: 30277654 PMCID: PMC7292329 DOI: 10.1002/npr2.12030] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2018] [Revised: 07/31/2018] [Accepted: 08/03/2018] [Indexed: 01/03/2023] Open
Abstract
Aim Cancer pain impairs not only physical functions but also social functions and roles. Consequently, the overall health‐related quality of life of patients with cancer pain deteriorates. Opioid analgesics are recommended for treating moderate to strong cancer pain. Advances in human genome research have fueled a growing interest to understand individual differences in responsiveness to opioid analgesics. This study aimed to explore and identify novel loci for genes predisposing an individual to opioid analgesic responsiveness. Methods A total of 71 cancer patients rated their pain on an 11‐point numerical rating scale twice before and after increasing opioid analgesics. A genomewide association study focusing on single nucleotide polymorphisms (SNPs) was conducted to associate pain decrease with increased dosage of opioid analgesics based on weight (ie, responsiveness to opioid analgesics). A genomewide significance (P < 5E‐8) was set for multiplicity of analyses to control for false positives. Results Two SNPs passed the genomewide threshold for significance. One exonic SNP (rs1641025) was located in the ABAT [4‐aminobutyrate aminotransaminase (GABA transaminase)] gene on chromosome 16. The other SNP (rs12494691) was located on chromosome 3, which was not associated with any known genes. These SNPs were not associated with opioid‐related adverse effects. Conclusions Our results preliminarily suggest that both SNPs might be potential candidate loci for responsiveness to opioid analgesics, and GABA transaminase might be a possible target for developing adjuvant pharmacotherapy with opioid analgesics in adjuvant pharmacotherapy. Our results should be validated in a large‐scale study with a larger sample size. A genome‐wide association study revealed two candidate single nucleotide polymorphisms for responsiveness to opioid analgesics in patients with cancer pain, one of which locates on the GABA transaminase gene.
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Affiliation(s)
- Yaeko Yokoshima
- Department of Anesthesiology and Pain Relief Center, The University of Tokyo Hospital, Tokyo, Japan
| | - Masahiko Sumitani
- Department of Pain and Palliative Medicine, The University of Tokyo Hospital, Tokyo, Japan
| | - Daisuke Nishizawa
- Addictive Substance Project, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan
| | - Makoto Nagashima
- Department of Surgery, Toho University Medical Center, Sakura Hospital, Chiba, Japan
| | - Kazutaka Ikeda
- Addictive Substance Project, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan
| | - Ryoji Kato
- Department of Surgery, Toho University Medical Center, Sakura Hospital, Chiba, Japan
| | - Jun Hozumi
- Department of Anesthesiology and Pain Relief Center, The University of Tokyo Hospital, Tokyo, Japan
| | - Hiroaki Abe
- Department of Pain and Palliative Medicine, The University of Tokyo Hospital, Tokyo, Japan
| | - Kenji Azuma
- Department of Pain and Palliative Medicine, The University of Tokyo Hospital, Tokyo, Japan
| | - Rikuhei Tsuchida
- Department of Anesthesiology and Pain Relief Center, The University of Tokyo Hospital, Tokyo, Japan
| | - Yoshitsugu Yamada
- Department of Anesthesiology and Pain Relief Center, The University of Tokyo Hospital, Tokyo, Japan
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Mahendran G, Vijayan R. Neuropharmacological and molecular docking studies of xanthones from Swertia corymbosa. J Recept Signal Transduct Res 2018; 38:166-177. [DOI: 10.1080/10799893.2018.1458875] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- Ganesan Mahendran
- Department of Botany, Bharathidasan University, Tiruchirapalli, India
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Ou Y, Su M, Ling Y, Wei Q, Pan F, Li J, Li JX, Zhu Q. Anti-allodynic effects of N-demethylsinomenine, an active metabolite of sinomenine, in a mouse model of postoperative pain. Eur J Pharmacol 2018; 823:105-109. [PMID: 29408089 DOI: 10.1016/j.ejphar.2018.01.044] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2017] [Revised: 01/16/2018] [Accepted: 01/25/2018] [Indexed: 11/30/2022]
Abstract
Sinomenine, a major bioactive ingredient isolated from traditional Chinese medicine Sinomenium acutum, has been reported to have analgesic effects in various pain animal models. N-demethylsinomenine, the N-demethylated product of sinomenine, has been identified to be the major metabolite of sinomenine and is also a natural component extracted from Sinomenium acutum. This study examined the anti-allodynic effects of N-demethylsinomenine in a mouse model of postoperative pain. A significant and sustained mechanical allodynia that lasted for 4 days was induced by making a surgical incision on the right hind paw in mice. Acute treatment with N-demethylsinomenine (10-40 mg/kg, s.c.) relieved the mechanical allodynia in a dose-dependent manner. Although there was no difference in maximal analgesic effect between N-demethylsinomenine (40 mg/kg, s.c.) and sinomenine (40 mg/kg, s.c.), the onset of action of N-demethylsinomenine was quicker than sinomenine. Repeated treatment with N-demethylsinomenine (10-40 mg/kg/day, s.c.) also dose-dependently exerted sustained antinociception against postoperative allodynia and did not produce analgesic tolerance and carry-over effect. The anti-allodynia induced by N-demethylsinomenine (40 mg/kg, s.c.) was attenuated by bicuculline, a selective γ-aminobutyric acid type A (GABAA) receptor antagonist. In addition, the doses of N-demethylsinomenine used here did not alter the locomotor activity in mice. Our findings demonstrated that N-demethylsinomenine exerts behaviorally-specific anti-allodynia against postoperative allodynia mediated through the GABAA receptors, suggesting it may be a useful novel pharmacotherapy for the control of postoperative pain.
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Affiliation(s)
- Yuntao Ou
- School of Pharmacy, Nantong University, Nantong, 226001, Jiangsu Province, China
| | - Man Su
- School of Pharmacy, Nantong University, Nantong, 226001, Jiangsu Province, China
| | - Yong Ling
- School of Pharmacy, Nantong University, Nantong, 226001, Jiangsu Province, China
| | - Qianqian Wei
- School of Pharmacy, Nantong University, Nantong, 226001, Jiangsu Province, China
| | - Fei Pan
- School of Pharmacy, Nantong University, Nantong, 226001, Jiangsu Province, China
| | - Jiejia Li
- School of Pharmacy, Nantong University, Nantong, 226001, Jiangsu Province, China
| | - Jun-Xu Li
- School of Pharmacy, Nantong University, Nantong, 226001, Jiangsu Province, China.
| | - Qing Zhu
- School of Pharmacy, Nantong University, Nantong, 226001, Jiangsu Province, China.
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Schliessbach J, Siegenthaler A, Bütikofer L, Vuilleumier P, Jüni P, Stamer U, Arendt-Nielsen L, Curatolo M. Predicting drug efficacy in chronic low back pain by quantitative sensory tests. Eur J Pain 2018; 22:973-988. [PMID: 29363217 DOI: 10.1002/ejp.1183] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/21/2017] [Indexed: 01/25/2023]
Abstract
BACKGROUND Drugs are prescribed for chronic low back pain without knowing in advance whether a patient will respond to them or not. Quantitative sensory tests (QST) can discriminate patients according to sensory phenotype, possibly reflecting underlying mechanisms of pain processing. QST may therefore be a screening tool to identify potential responders to a certain drug. The aim of this study was to investigate whether QST can predict analgesic effects of oxycodone, imipramine and clobazam in chronic low back pain. METHODS Oxycodone 15 mg (n = 50), imipramine 75 mg (n = 50) and clobazam 20 mg (n = 49) were compared to active placebo tolterodine 1 mg in a randomized, double-blinded, crossover fashion. Electrical, pressure and thermal QST were performed at baseline and after 1 and 2 h. Pain intensity was assessed on a 0-10 numeric rating scale every 30 min for up to 2 h. The ability of baseline QST to predict pain reduction after 2 h was analysed using linear mixed models. Genetic variants of drug-metabolizing enzymes and genes affecting pain sensitivity were examined as covariables. RESULTS No predictor of analgesic effect was found for oxycodone and clobazam. Thermal QST was associated with analgesic effect of imipramine: patients more sensitive to heat or cold were more likely to experience an effect of imipramine. Pharmacogenetic variants and pain-related candidate genes were not associated with drug efficacy. CONCLUSIONS Thermal QST have the potential to predict imipramine effect in chronic low back pain. Oxycodone and clobazam effects could not be predicted by any of the selected QST or genetic variants. SIGNIFICANCE Predicting drug efficacy in chronic low back pain remains difficult. There is some evidence that patients more sensitive to heat and cold pain respond better to imipramine.
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Affiliation(s)
- J Schliessbach
- Department of Anesthesiology and Pain Medicine, Inselspital, Bern University Hospital, University of Bern, Switzerland.,Institute of Anesthesiology, University Hospital Zurich, Switzerland
| | - A Siegenthaler
- Chronic Pain Management, Lindenhof Hospital, Lindenhof Group Bern, Switzerland
| | - L Bütikofer
- CTU Bern, and Institute of Social and Preventive Medicine (ISPM), University of Bern, Switzerland
| | - P Vuilleumier
- Department of Anesthesiology and Pain Medicine, Inselspital, Bern University Hospital, University of Bern, Switzerland
| | - P Jüni
- Department of Medicine, Applied Health Research Centre (AHRC), Li Ka Shing Knowledge Institute of St. Michael's Hospital, University of Toronto, ON, Canada
| | - U Stamer
- Department of Anesthesiology and Pain Medicine, Inselspital, Bern University Hospital, University of Bern, Switzerland
| | - L Arendt-Nielsen
- Centre of Sensory Motor Interaction SMI, University of Aalborg, Denmark
| | - M Curatolo
- Centre of Sensory Motor Interaction SMI, University of Aalborg, Denmark.,Department of Anesthesiology and Pain Medicine, University of Washington, Seattle, WA, USA
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Ovalle-Magallanes B, Déciga-Campos M, Mata R. Antihyperalgesic activity of a mexicanolide isolated from Swietenia humilis extract in nicotinamide-streptozotocin hyperglycemic mice. Biomed Pharmacother 2017; 92:324-330. [DOI: 10.1016/j.biopha.2017.05.073] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2017] [Revised: 05/02/2017] [Accepted: 05/15/2017] [Indexed: 10/19/2022] Open
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The Link between Depression and Chronic Pain: Neural Mechanisms in the Brain. Neural Plast 2017; 2017:9724371. [PMID: 28706741 PMCID: PMC5494581 DOI: 10.1155/2017/9724371] [Citation(s) in RCA: 380] [Impact Index Per Article: 54.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2017] [Revised: 05/04/2017] [Accepted: 05/24/2017] [Indexed: 02/08/2023] Open
Abstract
Chronic pain, as a stress state, is one of the critical factors for determining depression, and their coexistence tends to further aggravate the severity of both disorders. Unfortunately, their association remains unclear, which creates a bottleneck problem for managing chronic pain-induced depression. In recent years, studies have found considerable overlaps between pain- and depression-induced neuroplasticity changes and neurobiological mechanism changes. Such overlaps are vital to facilitating the occurrence and development of chronic pain and chronic pain-induced depression. In this review, we summarized the role of neuroplasticity in the occurrence and development of the two disorders in question and explored individualized application strategies of analgesic drugs and antidepressants that have different pharmacological effects in the treatment of chronic pain-induced depression. Therefore, this review may provide new insights into the understanding of association between chronic pain and depression.
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Guerrini G, Ciciani G, Crocetti L, Daniele S, Ghelardini C, Giovannoni MP, Di Cesare Mannelli L, Martini C, Vergelli C. Synthesis and Pharmacological Evaluation of Novel GABAA
Subtype Receptor Ligands with Potential Anxiolytic-like and Anti-hyperalgesic Effect. J Heterocycl Chem 2017. [DOI: 10.1002/jhet.2882] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- Gabriella Guerrini
- Dipartimento NEUROFARBA, sezione Farmaceutica e Nutraceutica; Università degli Studi di Firenze; Florence Italy
| | - Giovanna Ciciani
- Dipartimento NEUROFARBA, sezione Farmaceutica e Nutraceutica; Università degli Studi di Firenze; Florence Italy
| | - Letizia Crocetti
- Dipartimento NEUROFARBA, sezione Farmaceutica e Nutraceutica; Università degli Studi di Firenze; Florence Italy
| | - Simona Daniele
- Dipartimento FARMACIA; Università degli Studi di Pisa; Pisa Italy
| | - Carla Ghelardini
- Dipartimento NEUROFARBA, sezione Farmacologia; Università degli Studi di Firenze; Florence Italy
| | - Maria Paola Giovannoni
- Dipartimento NEUROFARBA, sezione Farmaceutica e Nutraceutica; Università degli Studi di Firenze; Florence Italy
| | | | - Claudia Martini
- Dipartimento FARMACIA; Università degli Studi di Pisa; Pisa Italy
| | - Claudia Vergelli
- Dipartimento NEUROFARBA, sezione Farmaceutica e Nutraceutica; Università degli Studi di Firenze; Florence Italy
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Schliessbach J, Vuilleumier P, Siegenthaler A, Bütikofer L, Limacher A, Juni P, Zeilhofer H, Arendt-Nielsen L, Curatolo M. Analgesic effect of clobazam in chronic low-back pain but not in experimentally induced pain. Eur J Pain 2017; 21:1336-1345. [DOI: 10.1002/ejp.1032] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/11/2017] [Indexed: 11/12/2022]
Affiliation(s)
- J. Schliessbach
- University Department of Anesthesiology and Pain Medicine, Inselspital, Bern University Hospital; Bern Switzerland
| | - P.H. Vuilleumier
- University Department of Anesthesiology and Pain Medicine, Inselspital, Bern University Hospital; Bern Switzerland
| | - A. Siegenthaler
- Chronic Pain Management; Lindenhof Group Bern; Lindenhof Hospital; Bern Switzerland
| | - L. Bütikofer
- Clinical Trials Unit Bern; Department of Clinical Research and Institute of Social and Preventive Medicine; University of Bern; Bern Switzerland
| | - A. Limacher
- Clinical Trials Unit Bern; Department of Clinical Research and Institute of Social and Preventive Medicine; University of Bern; Bern Switzerland
| | - P. Juni
- Department of Medicine; Applied Health Research Centre; University of Toronto; Toronto ON Canada
| | - H.U. Zeilhofer
- Institute of Pharmacology and Toxicology; University of Zurich; Zurich Switzerland
- Institute of Pharmaceutical Sciences; ETH Zurich; Zurich Switzerland
| | - L. Arendt-Nielsen
- Centre of Sensory Motor Interaction SMI; School of Medicine; University of Aalborg; Aalborg Denmark
| | - M. Curatolo
- Department of Anesthesiology and Pain Medicine; University of Washington; Seattle WA USA
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Akbar S, Subhan F, Karim N, Aman U, Ullah S, Shahid M, Ahmad N, Fawad K, Sewell RD. Characterization of 6-methoxyflavanone as a novel anxiolytic agent: A behavioral and pharmacokinetic approach. Eur J Pharmacol 2017; 801:19-27. [DOI: 10.1016/j.ejphar.2017.02.047] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2016] [Revised: 02/18/2017] [Accepted: 02/27/2017] [Indexed: 12/01/2022]
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Midazolam as an active placebo in 3 fentanyl-validated nociceptive pain models. Pain 2017; 158:1264-1271. [PMID: 28338566 DOI: 10.1097/j.pain.0000000000000910] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The use of inactive placebos in early translational trials of potentially analgesic compounds is discouraged because of the side-effect profiles of centrally acting analgesics. Therefore, benzodiazepines are used, although their use has not been validated in this context. Whether benzodiazepines confound the results of acute pain tests is unknown. Midazolam (0.06 mg/kg) as an active placebo was investigated in 3 nociceptive models that included contact heat, electrical pain, and pressure pain thresholds in 24 healthy volunteers. Fentanyl (1 μg/kg) served as an internal validator in this randomized, placebo (saline) controlled, 3-way cross-over trial. The primary outcome parameter (contact heat pain) was analyzed using a one-way, repeated measures analysis of variance and Tukey's post test. Midazolam did not reduce pain ([numeric rating scale], 0-100) in a statistically significant manner compared with placebo for the contact heat (mean difference -1.7, 95% confidence interval -10.6 to 7.3; P = 0.89) or electrical pain (4.3, -5.1 to 13.7; P = 0.51) test, nor did it raise the pressure pain thresholds (-28 kPa, -122; 64 kPa, P = 0.73). The width of the confidence intervals suggested that there were no clinically meaningful analgesic effects compared with the placebo. In contrast, the analgesic efficacy of fentanyl was effectively demonstrated in all 3 models (P < 0.01 vs midazolam and placebo). The findings of this study show that midazolam can be used as an active placebo in analgesic drug trials. Furthermore, the proposed models were simple to implement and very effective in detecting analgesia. The test battery can be used in translational trials for new compounds and comes with an active placebo and an optional active comparator.
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Abstract
Abstract
Neuroplastic changes play an important role in the generation and maintenance of chronic pain syndromes. Such changes occur at all levels of the neuraxis, from the peripheral terminals of primary sensory neurons to the cerebral cortex. Changes observed in the spinal dorsal horn in particular provide a mechanistic basis for many of the characteristics of chronic pain syndromes. While facilitated synaptic transmission between nociceptive fibers and spinal projection neurons contributes to enhanced perception of noxious stimuli (hyperalgesia), diminished function of GABA-ergic and glycinergic interneurons not only induces hyperalgesia, but also triggers nociceptive reactions on exposure to innocuous stimuli and spontaneous pain behavior in the absence of any sensory stimulation. Spinal disinhibition thus recapitulates typical symptoms of chronic pathological pain syndromes. Studies performed by various groups over the last 10 years demonstrate that such spinal disinhibition occurs naturally in response to peripheral inflammation and nerve damage. The present article summarizes current status of this research.
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Dias QM, Prado WA. The lesion of dorsolateral funiculus changes the antiallodynic effect of the intrathecal muscimol and baclofen in distinct phases of neuropathic pain induced by spinal nerve ligation in rats. Brain Res Bull 2016; 124:103-15. [DOI: 10.1016/j.brainresbull.2016.04.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2015] [Revised: 03/31/2016] [Accepted: 04/04/2016] [Indexed: 12/20/2022]
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Zhu Q, Mao LN, Liu CP, Sun YH, Jiang B, Zhang W, Li JX. Antinociceptive effects of vitexin in a mouse model of postoperative pain. Sci Rep 2016; 6:19266. [PMID: 26763934 PMCID: PMC4817219 DOI: 10.1038/srep19266] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2015] [Accepted: 12/03/2015] [Indexed: 11/09/2022] Open
Abstract
Vitexin, a C-glycosylated flavone present in several medicinal herbs, has showed various pharmacological activities including antinociception. The present study investigated the antinociceptive effects of vitexin in a mouse model of postoperative pain. This model was prepared by making a surgical incision on the right hindpaw and von Frey filament test was used to assess mechanical hyperalgesia. Isobolographical analysis method was used to examine the interaction between vitexin and acetaminophen. A reliable mechanical hyperalgesia was observed at 2 h post-surgery and lasted for 4 days. Acute vitexin administration (3–10 mg/kg, i.p.) dose-dependently relieved this hyperalgesia, which was also observed from 1 to 3 days post-surgery during repeated daily treatment. However, repeated vitexin administration prior to surgery had no preventive value. The 10 mg/kg vitexin-induced antinociception was blocked by the opioid receptor antagonist naltrexone or the GABAA receptor antagonist bicuculline. The doses of vitexin used did not significantly suppress the locomotor activity. In addition, the combination of vitexin and acetaminophen produced an infra-additive effect in postoperative pain. Together, though vitexin-acetaminophen combination may not be useful for treating postoperative pain, vitexin exerts behaviorally-specific antinociception against postoperative pain mediated through opioid receptors and GABAA receptors, suggesting that vitexin may be useful for the control of postoperative pain.
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Affiliation(s)
- Qing Zhu
- School of Pharmacy, Nantong University, Nantong, 226001, Jiangsu Province, China
| | - Li-Na Mao
- School of Pharmacy, Nantong University, Nantong, 226001, Jiangsu Province, China
| | - Cheng-Peng Liu
- School of Pharmacy, Nantong University, Nantong, 226001, Jiangsu Province, China
| | - Yue-Hua Sun
- School of Pharmacy, Nantong University, Nantong, 226001, Jiangsu Province, China
| | - Bo Jiang
- School of Pharmacy, Nantong University, Nantong, 226001, Jiangsu Province, China
| | - Wei Zhang
- School of Pharmacy, Nantong University, Nantong, 226001, Jiangsu Province, China
| | - Jun-Xu Li
- School of Pharmacy, Nantong University, Nantong, 226001, Jiangsu Province, China
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Nashawi H, Masocha W, Edafiogho IO, Kombian SB. Paclitaxel Causes Electrophysiological Changes in the Anterior Cingulate Cortex via Modulation of the γ-Aminobutyric Acid-ergic System. Med Princ Pract 2016; 25:423-8. [PMID: 27336416 PMCID: PMC5588502 DOI: 10.1159/000447775] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/12/2015] [Accepted: 06/22/2016] [Indexed: 01/08/2023] Open
Abstract
OBJECTIVE The aim of this study was to elucidate any electrophysiological changes that may contribute to the development of neuropathic pain during treatment with the anticancer drug paclitaxel, particularly in the γ-aminobutyric acid (GABA) system. MATERIALS AND METHODS One hundred and eight Sprague-Dawley rats were used (untreated control: 43; vehicle-treated: 21, and paclitaxel-treated: 44). Paclitaxel (8 mg/kg) was administered intraperitoneally on 2 alternate days to induce mechanical allodynia. The rats were sacrificed 7 days after treatment to obtain slices of the anterior cingulate cortex (ACC), a brain region involved in the central processing of pain. Field excitatory postsynaptic potentials (fEPSPs) were recorded in layer II/III of ACC slices, and stimulus-response curves were constructed. The observed effects were pharmacologically characterized by bath application of GABA and appropriate drugs to the slices. RESULTS The paclitaxel-treated rats developed mechanical allodynia (i.e. reduced withdrawal threshold to mechanical stimuli). Slices from paclitaxel-treated rats produced a significantly higher maximal response (Emax) than those from untreated rats (p < 0.001). Bath application of GABA (0.4 µM) reversed this effect and returned the excitability to a level similar to control. Pretreatment of the slices with the GABAB receptor blocker CGP 55845 (50 µM) increased Emax in slices from untreated rats (p < 0.01) but not from paclitaxel-treated rats. CONCLUSION In this study, there was a GABA deficit in paclitaxel-treated rats compared to untreated ones. Such a deficit could contribute to the pathophysiology of paclitaxel-induced neuropathic pain (PINP). Thus, the GABAergic system might be a potential therapeutic target for managing PINP.
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Affiliation(s)
- Houda Nashawi
- Department of Pharmacology and Therapeutics, Faculty of Pharmacy, Health Sciences Centre, Kuwait University, Jabriya, Kuwait, Conn., USA
| | - Willias Masocha
- Department of Pharmacology and Therapeutics, Faculty of Pharmacy, Health Sciences Centre, Kuwait University, Jabriya, Kuwait, Conn., USA
- *Willias Masocha, Department of Pharmacology and Therapeutics, Faculty of Pharmacy, Health Sciences Centre, Kuwait University, PO Box 24923, Safat, Jabriya 13110 (Kuwait), E-Mail
| | - Ivan O. Edafiogho
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Saint Joseph, Hartford, Conn., USA
| | - Samuel B. Kombian
- Department of Pharmacology and Therapeutics, Faculty of Pharmacy, Health Sciences Centre, Kuwait University, Jabriya, Kuwait, Conn., USA
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GABAergic modulation in central sensitization in humans: a randomized placebo-controlled pharmacokinetic-pharmacodynamic study comparing clobazam with clonazepam in healthy volunteers. Pain 2015; 156:397-404. [PMID: 25687539 DOI: 10.1097/01.j.pain.0000460331.33385.e8] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Positive allosteric modulators of GABAA receptors (GAMs) acting at specific subtypes of GABAA receptors effectively restore compromised spinal pain control in rodents. Studies addressing a similar antihyperalgesic effect in humans are sparse and are hampered by sedative effects of nonselective GAMs available for use in humans. We present results from a randomized controlled double-blind crossover study in 25 healthy volunteers, which addressed potential antihyperalgesic actions of clobazam (CBZ) and clonazepam (CLN) at mildly sedating equianticonvulsive doses. Clobazam was chosen because of its relatively low sedative properties and CLN because of its use in neuropathic pain. Tolterodine (TLT) was used as an active placebo. The primary outcome parameter was a change in the area of cutaneous UVB irradiation-induced secondary hyperalgesia (ASH), which was monitored for 8 hours after drug application. Sedative effects were assessed in parallel to antihyperalgesia. Compared with TLT, recovery from hyperalgesia was significantly faster in the CBZ and CLN groups (P = 0.009). At the time point of maximum effect, the rate of recovery from hyperalgesia was accelerated by CBZ and CLN, relative to placebo by 15.7% (95% confidence interval [CI] 0.8-30.5), P = 0.040, and 28.6% (95% CI 4.5-52.6), P = 0.022, respectively. Active compounds induced stronger sedation than placebo, but these differences disappeared 8 hours after drug application. We demonstrate here that GAMs effectively reduce central sensitization in healthy volunteers. These results provide proof-of-principle evidence supporting efficacy of GAMs as antihyperalgesic agents in humans and should stimulate further research on compounds with improved subtype specificity.
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Klinger F, Bajric M, Salzer I, Dorostkar MM, Khan D, Pollak DD, Kubista H, Boehm S, Koenig X. δ Subunit-containing GABAA receptors are preferred targets for the centrally acting analgesic flupirtine. Br J Pharmacol 2015. [PMID: 26211808 PMCID: PMC4621994 DOI: 10.1111/bph.13262] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Background and Purpose The Kv7 channel activator flupirtine is a clinical analgesic characterized as ‘selective neuronal potassium channel opener’. Flupirtine was found to exert comparable actions at GABAA receptors and Kv7 channels in neurons of pain pathways, but not in hippocampus. Experimental Approach Expression patterns of GABAA receptors were explored in immunoblots of rat dorsal root ganglia, dorsal horns and hippocampi using antibodies for 10 different subunits. Effects of flupirtine on recombinant and native GABAA receptors were investigated in patch clamp experiments and compared with the actions on Kv7 channels. Key Results Immunoblots pointed towards α2, α3, β3 and γ2 subunits as targets, but in all γ2‐containing receptors the effects of flupirtine were alike: leftward shift of GABA concentration‐response curves and diminished maximal amplitudes. After replacement of γ2S by δ, flupirtine increased maximal amplitudes. Currents through α1β2δ receptors were more enhanced than those through Kv7 channels. In hippocampal neurons, flupirtine prolonged inhibitory postsynaptic currents, left miniature inhibitory postsynaptic currents (mIPSCs) unaltered and increased bicuculline‐sensitive tonic currents; penicillin abolished mIPSCs, but not tonic currents; concentration‐response curves for GABA‐induced currents were shifted to the left by flupirtine without changes in maximal amplitudes; in the presence of penicillin, maximal amplitudes were increased; GABA‐induced currents in the presence of penicillin were more sensitive towards flupirtine than K+ currents. In dorsal horn neurons, currents evoked by the δ‐preferring agonist THIP (gaboxadol) were more sensitive towards flupirtine than K+ currents. Conclusions and Implications Flupirtine prefers δ‐containing GABAA receptors over γ‐containing ones and over Kv7 channels.
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Affiliation(s)
- Felicia Klinger
- Department of Neurophysiology and Neuropharmacology, Centre for Physiology and Pharmacology, Medical University of Vienna, Spitalgasse 23, Vienna, 1090, Austria
| | - Mirnes Bajric
- Department of Neurophysiology and Neuropharmacology, Centre for Physiology and Pharmacology, Medical University of Vienna, Spitalgasse 23, Vienna, 1090, Austria
| | - Isabella Salzer
- Department of Neurophysiology and Neuropharmacology, Centre for Physiology and Pharmacology, Medical University of Vienna, Spitalgasse 23, Vienna, 1090, Austria
| | - Mario M Dorostkar
- Department of Neurophysiology and Neuropharmacology, Centre for Physiology and Pharmacology, Medical University of Vienna, Spitalgasse 23, Vienna, 1090, Austria
| | - Deeba Khan
- Department of Neurophysiology and Neuropharmacology, Centre for Physiology and Pharmacology, Medical University of Vienna, Spitalgasse 23, Vienna, 1090, Austria
| | - Daniela D Pollak
- Department of Neurophysiology and Neuropharmacology, Centre for Physiology and Pharmacology, Medical University of Vienna, Spitalgasse 23, Vienna, 1090, Austria
| | - Helmut Kubista
- Department of Neurophysiology and Neuropharmacology, Centre for Physiology and Pharmacology, Medical University of Vienna, Spitalgasse 23, Vienna, 1090, Austria
| | - Stefan Boehm
- Department of Neurophysiology and Neuropharmacology, Centre for Physiology and Pharmacology, Medical University of Vienna, Spitalgasse 23, Vienna, 1090, Austria
| | - Xaver Koenig
- Department of Neurophysiology and Neuropharmacology, Centre for Physiology and Pharmacology, Medical University of Vienna, Spitalgasse 23, Vienna, 1090, Austria
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Jiang J, Shen YY, Li J, Lin YH, Luo CX, Zhu DY. (+)-Borneol alleviates mechanical hyperalgesia in models of chronic inflammatory and neuropathic pain in mice. Eur J Pharmacol 2015; 757:53-8. [PMID: 25835611 DOI: 10.1016/j.ejphar.2015.03.056] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2014] [Revised: 03/17/2015] [Accepted: 03/17/2015] [Indexed: 01/28/2023]
Abstract
Chronic pain is a major public health problem categorized as inflammatory or neuropathic, each involving impaired GABAergic control in the spinal cord of mammals. (+)-Borneol, a bicyclic monoterpene present in the essential oil of plants, is used for analgesia and anesthesia in traditional Chinese medicine. It has been reported that (+)-borneol directly potentiates GABA activity at recombinant human GABAA receptors. Although borneol has antinociceptive effect on acute pain models, little is known about its effect on chronic pain and its mechanism. Here we report that (+)-borneol has remarkable anti-hyperalgesic effects on neuropathic and inflammatory pain in animal models. Neuropathic hypersensitivity was induced by segmental spinal nerve ligation (SNL), and inflammatory hypersensitivity was induced by intraplantar (i.pl.) injection of complete Freund׳s adjuvant (CFA). Both oral administration (125, 250 or 500 mg/kg) and intrathecal injection (i.t.) (15, 30 and 60 μg) of (+)-borneol reduced mechanical hypersensitivity dose-dependently in SNL and CFA models. The anti-hyperalgesic effects of (+)-borneol were abolished by a selective GABAA receptor (GABAAR) antagonist bicuculline (i.t., at 30 min after (+)-borneol injection). Furthermore, (+)-borneol (500 mg/kg, p.o. or 60 μg, i.t.) did not influence motor function. These findings suggest that (+)-borneol may ameliorate mechanical hyperalgesia by enhancing GABAAR-mediated GABAergic transmission in the spinal cord, and could serve as a therapeutic for chronic pain.
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Affiliation(s)
- Jun Jiang
- Department of Pharmacology, School of Pharmacy, Nanjing Medical University, Nanjing 211000, China
| | - Ying Ying Shen
- Department of Pharmacology, School of Pharmacy, Nanjing Medical University, Nanjing 211000, China
| | - Jun Li
- Department of Pharmacology, School of Pharmacy, Nanjing Medical University, Nanjing 211000, China
| | - Yu Hui Lin
- Department of Pharmacology, School of Pharmacy, Nanjing Medical University, Nanjing 211000, China
| | - Chun Xia Luo
- Department of Pharmacology, School of Pharmacy, Nanjing Medical University, Nanjing 211000, China
| | - Dong Ya Zhu
- Department of Pharmacology, School of Pharmacy, Nanjing Medical University, Nanjing 211000, China.
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Peng F, Qu ZW, Qiu CY, Liao M, Hu WP. Spinal vasopressin alleviates formalin-induced nociception by enhancing GABAA receptor function in mice. Neurosci Lett 2015; 593:61-5. [PMID: 25782631 DOI: 10.1016/j.neulet.2015.03.023] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2015] [Revised: 03/06/2015] [Accepted: 03/13/2015] [Indexed: 12/18/2022]
Abstract
Arginine vasopressin (AVP) plays a regulatory role in nociception. Intrathecal administration of AVP displays an antinociceptive effect. However, little is understood about the mechanism underlying spinal AVP analgesia. Here, we have found that spinal AVP dose dependently reduced the second, but not first, phase of formalin-induced spontaneous nociception in mice. The AVP analgesia was completely blocked by intrathecal injected SR 49059, a vasopressin-1A (V1A) receptor antagonist. However, spinal AVP failed to exert its antinociceptive effect on the second phase formalin-induced spontaneous nociception in V1A receptor knock-out (V1A-/-) mice. The AVP analgesia was also reversed by bicuculline, a GABAA receptor antagonist. Moreover, AVP potentiated GABA-activated currents in dorsal root ganglion neurons from wild-type littermates, but not from V1A-/- mice. Our results may reveal a novel spinal mechanism of AVP analgesia by enhancing the GABAA receptor function in the spinal cord through V1A receptors.
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Affiliation(s)
- Fang Peng
- Institute of Ion Channels, Department of Pharmacology, Hubei University of Science and Technology, 88 Xianning Road, Xianning 437100, Hubei, PR China; Department of Anatomy and Histology & Embryology, College of Basic Medicine, Wenzou Medical University, Wenzou 32500, Zhejiang, PR China
| | - Zu-Wei Qu
- Institute of Ion Channels, Department of Pharmacology, Hubei University of Science and Technology, 88 Xianning Road, Xianning 437100, Hubei, PR China
| | - Chun-Yu Qiu
- Institute of Ion Channels, Department of Pharmacology, Hubei University of Science and Technology, 88 Xianning Road, Xianning 437100, Hubei, PR China
| | - Min Liao
- Department of Anatomy and Histology & Embryology, College of Basic Medicine, Wenzou Medical University, Wenzou 32500, Zhejiang, PR China.
| | - Wang-Ping Hu
- Institute of Ion Channels, Department of Pharmacology, Hubei University of Science and Technology, 88 Xianning Road, Xianning 437100, Hubei, PR China.
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Zeilhofer HU, Ralvenius WT, Acuña MA. Restoring the Spinal Pain Gate. DIVERSITY AND FUNCTIONS OF GABA RECEPTORS: A TRIBUTE TO HANNS MÖHLER, PART B 2015; 73:71-96. [DOI: 10.1016/bs.apha.2014.11.007] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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Synaptic Inhibition and Disinhibition in the Spinal Dorsal Horn. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2015; 131:359-83. [DOI: 10.1016/bs.pmbts.2014.11.008] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Möhler H. The legacy of the benzodiazepine receptor: from flumazenil to enhancing cognition in Down syndrome and social interaction in autism. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2014; 72:1-36. [PMID: 25600365 DOI: 10.1016/bs.apha.2014.10.008] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The study of the psychopharmacology of benzodiazepines continues to provide new insights into diverse brain functions related to vigilance, anxiety, mood, epileptiform activity, schizophrenia, cognitive performance, and autism-related social behavior. In this endeavor, the discovery of the benzodiazepine receptor was a key event, as it supplied the primary benzodiazepine drug-target site, provided the molecular link to the allosteric modulation of GABAA receptors and, following the recognition of GABAA receptor subtypes, furnished the platform for future, more selective drug actions. This review has two parts. In a retrospective first part, it acknowledges the contributions to the field made by my collaborators over the years, initially at Hoffmann-La Roche in Basle and later, in academia, at the University and the ETH of Zurich. In the second part, the new frontier of GABA pharmacology, targeting GABAA receptor subtypes, is reviewed with special focus on nonsedative anxiolytics, antidepressants, analgesics, as well as enhancers of cognition in Down syndrome and attenuators of symptoms of autism spectrum disorders. It is encouraging that a clinical trial has been initiated with a partial inverse agonist acting on α5 GABAA receptors in an attempt to alleviate the cognitive deficits in Down syndrome.
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Affiliation(s)
- Hanns Möhler
- Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland; Department of Chemistry and Applied Biosciences, Federal Institute of Technology (ETH), Zurich, Switzerland.
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42
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Labrakakis C, Rudolph U, De Koninck Y. The heterogeneity in GABAA receptor-mediated IPSC kinetics reflects heterogeneity of subunit composition among inhibitory and excitatory interneurons in spinal lamina II. Front Cell Neurosci 2014; 8:424. [PMID: 25565959 PMCID: PMC4263102 DOI: 10.3389/fncel.2014.00424] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2014] [Accepted: 11/24/2014] [Indexed: 12/03/2022] Open
Abstract
GABAergic inhibition displays rich functional diversity throughout the CNS, which arises from variations in the nature of inputs, subunit composition, subcellular localization of receptors and synapse geometry, or reuptake mechanisms. In the spinal dorsal horn (SDH), GABAA and glycine receptors play a major role in the control of excitability and accuracy of nociceptive processing. Identifying which components shape the properties of the inhibitory synapses in different cell types is necessary to understand how nociceptive information is integrated. To address this, we used transgenic mice where inhibitory interneurons express GAD65-EGFP. We found that GABAA, but not glycine receptor-mediated evoked IPSCs displayed slower kinetics in EGFP+ vs. EGFP− interneurons. GABAA miniature IPSC decay kinetics showed a large variability in both populations, however the distribution of decays differed between EGFP+ and EGFP− interneurons. The range of mIPSC decay kinetics observed was replicated in experiments using rapid application of GABA on outside-out patches taken from SDH neurons in slices. Furthermore, GABAA decay kinetics were not affected by uptake blockers and were not different in mice lacking δ or α5 subunits, indicating that intrinsic channel properties likely underlie the heterogeneity. To identify whether other α subunits shape the various kinetic properties observed we took advantage of knock-in mice carrying point mutations in either the α1, α2, or α3 subunits rendering Ro 15-4513 a selective agonist at the benzodiazepine modulatory site. We found that α1 and α2 subunit underlie the fast decaying component of IPSCs while the slow component is determined by the α3 subunit. The differential distribution of GABAA subunits at inhibitory synapses thus sculpts the heterogeneity of the SDH inhibitory circuitry. This diversity of inhibitory elements can be harnessed to selectively modulate different components of the spinal nociceptive circuitry for therapeutic interventions.
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Affiliation(s)
- Charalampos Labrakakis
- Unité de Neurosciences Cellulaires et Moléculaire, Institut Universitaire en Santé Mentale de Québec Québec, QC, Canada ; Department of Biological Applications and Technology, University of Ioannina Ioannina, Greece
| | - Uwe Rudolph
- Laboratory of Genetic Neuropharmacology, McLean Hospital, and Department of Psychiatry, Harvard Medical School Belmont, MA, USA
| | - Yves De Koninck
- Unité de Neurosciences Cellulaires et Moléculaire, Institut Universitaire en Santé Mentale de Québec Québec, QC, Canada ; Department of Psychiatry and Neuroscience, Université Laval Québec, QC, Canada
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McCarson KE, Enna SJ. GABA pharmacology: the search for analgesics. Neurochem Res 2014; 39:1948-63. [PMID: 24532294 DOI: 10.1007/s11064-014-1254-x] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2013] [Revised: 01/28/2014] [Accepted: 01/31/2014] [Indexed: 12/28/2022]
Abstract
Decades of research have been devoted to defining the role of GABAergic transmission in nociceptive processing. Much of this work was performed using rigid, orthosteric GABA analogs created by Povl Krogsgaard-Larsen and his associates. A relationship between GABA and pain is suggested by the anatomical distribution of GABA receptors and the ability of some GABA agonists to alter nociceptive responsiveness. Outlined in this report are data supporting this proposition, with particular emphasis on the anatomical localization and function of GABA-containing neurons and the molecular and pharmacological properties of GABAA and GABAB receptor subtypes. Reference is made to changes in overall GABAergic tone, GABA receptor expression and activity as a function of the duration and intensity of a painful stimulus or exposure to GABAergic agents. Evidence is presented that the plasticity of this receptor system may be responsible for the variability in the antinociceptive effectiveness of compounds that influence GABA transmission. These findings demonstrate that at least some types of persistent pain are associated with a regionally selective decline in GABAergic tone, highlighting the need for agents that enhance GABA activity in the affected regions without compromising GABA function over the long-term. As subtype selective positive allosteric modulators may accomplish these goals, such compounds might represent a new class of analgesic drugs.
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Affiliation(s)
- Kenneth E McCarson
- Department of Pharmacology, Toxicology, and Therapeutics, University of Kansas Medical Center, 3901 Rainbow Boulevard, Mail Stop 1018, Kansas City, KS, 66160, USA
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Sharma M, Deekshith V, Semwal A, Sriram D, Yogeeswari P. Discovery of tetrahydropyrido[4,3-d]pyrimidine derivatives for the treatment of neuropathic pain. Bioorg Chem 2014; 52:69-76. [DOI: 10.1016/j.bioorg.2013.11.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2013] [Revised: 11/08/2013] [Accepted: 11/19/2013] [Indexed: 10/26/2022]
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Inhibition of carbonic anhydrase augments GABAA receptor-mediated analgesia via a spinal mechanism of action. THE JOURNAL OF PAIN 2014; 15:395-406. [PMID: 24412803 DOI: 10.1016/j.jpain.2014.01.001] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2013] [Revised: 10/22/2013] [Accepted: 01/04/2014] [Indexed: 12/21/2022]
Abstract
UNLABELLED Peripheral nerve injury (PNI) negatively influences spinal gamma-aminobutyric acid (GABA)ergic networks via a reduction in the neuron-specific potassium-chloride (K(+)-Cl(-)) cotransporter (KCC2). This process has been linked to the emergence of neuropathic allodynia. In vivo pharmacologic and modeling studies show that a loss of KCC2 function results in a decrease in the efficacy of GABAA-mediated spinal inhibition. One potential strategy to mitigate this effect entails inhibition of carbonic anhydrase activity to reduce HCO3(-)-dependent depolarization via GABAA receptors when KCC2 function is compromised. We have tested this hypothesis here. Our results show that, similarly to when KCC2 is pharmacologically blocked, PNI causes a loss of analgesic effect for neurosteroid GABAA allosteric modulators at maximally effective doses in naïve mice in the tail-flick test. Remarkably, inhibition of carbonic anhydrase activity with intrathecal acetazolamide rapidly restores an analgesic effect for these compounds, suggesting an important role of carbonic anhydrase activity in regulating GABAA-mediated analgesia after PNI. Moreover, spinal acetazolamide administration leads to a profound reduction in the mouse formalin pain test, indicating that spinal carbonic anhydrase inhibition produces analgesia when primary afferent activity is driven by chemical mediators. Finally, we demonstrate that systemic administration of acetazolamide to rats with PNI produces an antiallodynic effect by itself and an enhancement of the peak analgesic effect with a change in the shape of the dose-response curve of the α1-sparing benzodiazepine L-838,417. Thus, carbonic anhydrase inhibition mitigates the negative effects of loss of KCC2 function after nerve injury in multiple species and through multiple administration routes resulting in an enhancement of analgesic effects for several GABAA allosteric modulators. We suggest that carbonic anhydrase inhibitors, many of which are clinically available, might be advantageously employed for the treatment of pathologic pain states. PERSPECTIVE Using behavioral pharmacology techniques, we show that spinal GABAA-mediated analgesia can be augmented, especially following nerve injury, via inhibition of carbonic anhydrases. Carbonic anhydrase inhibition alone also produces analgesia, suggesting these enzymes might be targeted for the treatment of pain.
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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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The anticonvulsant enaminone E139 attenuates paclitaxel-induced neuropathic pain in rodents. ScientificWorldJournal 2013; 2013:240508. [PMID: 24385872 PMCID: PMC3872104 DOI: 10.1155/2013/240508] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2013] [Accepted: 11/20/2013] [Indexed: 11/30/2022] Open
Abstract
The enaminone methyl 4-(4′-bromophenyl)aminocyclohex-3-en-6-methyl-2-oxo-1-oate (E139) has anticonvulsant activities. It has been reported to have a better safety profile than some anticonvulsant drugs. Since some anticonvulsant drugs are used in the management of neuropathic pain, we evaluated the effects of E139 in rodent models of acute pain and paclitaxel-induced neuropathic pain. The reaction latency to thermal stimuli (hot-plate test) of BALB/c mice was recorded before and after intraperitoneal treatment with paclitaxel (2 mg/kg, i.p. for 5 consecutive days), and after treatment with E139 (0.1–40 mg/kg), amitriptyline (10 mg/kg), and gabapentin (10 and 30 mg/kg). Mechanical allodynia in paclitaxel-treated Sprague Dawley (SD) rats was measured using a dynamic plantar aesthesiometer before and after treatment with E139 (10 and 20 mg/kg) or its vehicle for four consecutive days from day 7 after first administration of paclitaxel (16 mg/kg on two alternate days). Administration of E139 (10–40 mg/kg) produced antinociceptive activity against thermal nociception in naïve mice. Treatment with E139, amitriptyline, or gabapentin reduced paclitaxel-induced thermal hyperalgesia. E139 reduced paclitaxel-induced mechanical allodynia, with the effects lasting longer (24 h) after repetitive dosing. Our results indicate that E139 has antinociceptive activity and attenuates paclitaxel-induced neuropathic pain in rodents.
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Yuan S, Burrell BD. Nonnociceptive afferent activity depresses nocifensive behavior and nociceptive synapses via an endocannabinoid-dependent mechanism. J Neurophysiol 2013; 110:2607-16. [PMID: 24027102 DOI: 10.1152/jn.00170.2013] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Previously, low-frequency stimulation (LFS) of a nonnociceptive touch-sensitive neuron has been found to elicit endocannabinoid-dependent long-term depression (eCB-LTD) in nociceptive synapses in the leech central nervous system (CNS) that requires activation of a presynaptic transient receptor potential vanilloid (TRPV)-like receptor by postsynaptically synthesized 2-arachidonoyl glycerol (2-AG). This capacity of nonnociceptive afferent activity to reduce nociceptive signaling resembles gate control of pain, albeit longer lasting in these synaptic experiments. Since eCB-LTD has been observed at a single sensory-motor synapse, this study examines the functional relevance of this mechanism, specifically whether this form of synaptic plasticity has similar effects at the behavioral level in which additional, intersegmental neural circuits are engaged. Experiments were carried out using a semi-intact preparation that permitted both synaptic recordings and monitoring of the leech whole body shortening, a defensive withdrawal reflex that was elicited via intracellular stimulation of a single nociceptive neuron (the N cell). The same LFS of a nonnociceptive afferent that induced eCB-LTD in single synapses also produced an attenuation of the shortening reflex. Similar attenuation of behavior was also observed when 2-AG was applied. LFS-induced behavioral and synaptic depression was blocked by tetrahydrolipstatin (THL), a diacylglycerol lipase inhibitor, and by SB366791, a TRPV1 antagonist. The effects of both THL and SB366791 were observed following either bath application of the drug or intracellular injection into the presynaptic (SB366791) or postsynaptic (THL) neuron. These findings demonstrate a novel, endocannabinoid-based mechanism by which nonnociceptive afferent activity may modulate nocifensive behaviors via action on primary afferent synapses.
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Affiliation(s)
- Sharleen Yuan
- Center for Brain and Behavior Research, Division of Basic Biomedical Sciences, Sanford School of Medicine, University of South Dakota, Vermillion, South Dakota
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Sałat K, Więckowska A, Więckowski K, Höfner GC, Kamiński J, Wanner KT, Malawska B, Filipek B, Kulig K. Synthesis and pharmacological properties of new GABA uptake inhibitors. Pharmacol Rep 2013; 64:817-33. [PMID: 23087134 DOI: 10.1016/s1734-1140(12)70877-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2011] [Revised: 04/05/2012] [Indexed: 12/01/2022]
Abstract
BACKGROUND γ-Aminobutanoic acid (GABA) is the principal inhibitory neurotransmitter in the mammalian central nervous system. The identification and subsequent development of the GABA transport inhibitors which enhance the GABA-ergic transmission has shown the important role that GABA transporters play in the control of numerous functions of the nervous system. Compounds which inhibit GABA uptake are used as antiepileptic drugs (tiagabine - a selective GAT1 inhibitor), they are also being investigated for other indications, including treatment of psychosis, general anxiety, sleep disorders, drug addiction or acute and chronic pain. METHODS In this paper, the synthesis of 2-substituted-4-(1,3-dioxoisoindolin-2-ylo)-butanamides and 2-substituted-4-aminobutanoic acids derivatives is described. These compounds were tested in vitro for their ability to inhibit GABA uptake. The inhibitory potency towards murine plasma membrane GABA transporters (mGAT1-4) was performed as [(3)H]GABA uptake assay based on stably transfected HEK cells. Compound 18, which demonstrated the highest affinity for mGAT1-4 (pIC(50) ranged from 4.42 for mGAT1 to 5.07 for mGAT3), was additionally investigated in several behavioral tests in mice. RESULTS Compound 18 increased the locomotor activity (14-38%) and had anxiolytic-like properties in the four-plate test (ED(50) = 9.3 mg/kg). It did not show analgesic activity in acute pain model, namely the hot plate test, however, it was antinociceptive in the acetic acid-induced writhing test (ED(50) = 15.3 mg/kg) and in the formalin model of tonic pain. In the latter assay, it diminished nocifensive behavior in both phases and in the first (neurogenic) phase of this test the obtained ED(50) value (5.3 mg/kg) was similar to morphine (3.0 mg/kg). CONCLUSION Compound 18 exhibited significant anxiolytic-like properties and was antinociceptive in some models of pain in mice. Moreover, it did not impair animals' motor coordination in the chimney test. Some of the described pharmacological activities of compound 18 can be partly explained based on its affinity for plasma membrane GABA transporters.
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Affiliation(s)
- Kinga Sałat
- Department of Physicochemical Drug Analysis, Jagiellonian University, Medical College, Kraków, Poland
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Paul J, Zeilhofer HU, Fritschy JM. Selective distribution of GABA(A) receptor subtypes in mouse spinal dorsal horn neurons and primary afferents. J Comp Neurol 2013; 520:3895-911. [PMID: 22522945 DOI: 10.1002/cne.23129] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
In the spinal cord dorsal horn, presynaptic GABA(A) receptors (GABA(A)Rs) in the terminals of nociceptors as well as postsynaptic receptors in spinal neurons regulate the transmission of nociceptive and somatosensory signals from the periphery. GABA(A)Rs are heterogeneous and distinguished functionally and pharmacologically by the type of α subunit variant they contain. This heterogeneity raises the possibility that GABA(A)R subtypes differentially regulate specific pain modalities. Here, we characterized the subcellular distribution of GABA(A)R subtypes in nociceptive circuits by using immunohistochemistry with subunit-specific antibodies combined with markers of primary afferents and dorsal horn neurons. Confocal laser scanning microscopy analysis revealed a distinct, partially overlapping laminar distribution of α1-3 and α5 subunit immunoreactivity in laminae I-V. Likewise, a layer-specific pattern was evident for their distribution among glutamatergic, γ-aminobutyric acid (GABA)ergic, and glycinergic neurons (detected in transgenic mice expressing vesicular glutamate transporter 2-enhanced green fluorescent protein [vGluT2-eGFP], glutamic acid decarboxylase [GAD]67-eGFP, and glycine transporter 2 (GlyT2)-eGFP, respectively). Finally, all four subunits could be detected within primary afferent terminals. C-fibers predominantly contained either α2 or α3 subunit immunoreactivity; terminals from myelinated (Aβ/Aδ) fibers were colabeled in roughly equal proportion with each subunit. The presence of axoaxonic GABAergic synapses was determined by costaining with gephyrin and vesicular inhibitory amino acid transporter to label GABAergic postsynaptic densities and terminals, respectively. Colocalization of the α2 or α3 subunit with these markers was observed in a subset of C-fiber synapses. Furthermore, gephyrin mRNA and protein expression was detected in dorsal root ganglia. Collectively, these results show that differential GABA(A)R distribution in primary afferent terminals and dorsal horn neurons allows for multiple, circuit-specific modes of regulation of nociceptive circuits.
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Affiliation(s)
- Jolly Paul
- Institute of Pharmacology and Toxicology, University of Zurich, CH-8057 Zurich, Switzerland
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