101
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Kato AS, Witkin JM. Protein complexes as psychiatric and neurological drug targets. Biochem Pharmacol 2018; 151:263-281. [PMID: 29330067 DOI: 10.1016/j.bcp.2018.01.018] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Accepted: 01/05/2018] [Indexed: 12/25/2022]
Abstract
The need for improved medications for psychiatric and neurological disorders is clear. Difficulties in finding such drugs demands that all strategic means be utilized for their invention. The discovery of forebrain specific AMPA receptor antagonists, which selectively block the specific combinations of principal and auxiliary subunits present in forebrain regions but spare targets in the cerebellum, was recently disclosed. This discovery raised the possibility that other auxiliary protein systems could be utilized to help identify new medicines. Discussion of the TARP-dependent AMPA receptor antagonists has been presented elsewhere. Here we review the diversity of protein complexes of neurotransmitter receptors in the nervous system to highlight the broad range of protein/protein drug targets. We briefly outline the structural basis of protein complexes as drug targets for G-protein-coupled receptors, voltage-gated ion channels, and ligand-gated ion channels. This review highlights heterodimers, subunit-specific receptor constructions, multiple signaling pathways, and auxiliary proteins with an emphasis on the later. We conclude that the use of auxiliary proteins in chemical compound screening could enhance the detection of specific, targeted drug searches and lead to novel and improved medicines for psychiatric and neurological disorders.
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Affiliation(s)
- Akihiko S Kato
- Neuroscience Discovery, Lilly Research Labs, Eli Lilly and Company, Indianapolis, IN, USA.
| | - Jeffrey M Witkin
- Neuroscience Discovery, Lilly Research Labs, Eli Lilly and Company, Indianapolis, IN, USA
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102
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Cheng T, Wallace DM, Ponteri B, Tuli M. Valium without dependence? Individual GABA A receptor subtype contribution toward benzodiazepine addiction, tolerance, and therapeutic effects. Neuropsychiatr Dis Treat 2018; 14:1351-1361. [PMID: 29872302 PMCID: PMC5973310 DOI: 10.2147/ndt.s164307] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Benzodiazepines are one of the most prescribed medications as first-line treatment of anxiety, insomnia, and epilepsy around the world. Over the past two decades, advances in the neuropharmacological understanding of gamma aminobutyric acid (GABA)A receptors revealed distinct contributions from each subtype and produced effects. Recent findings have highlighted the importance of α1 containing GABAA receptors in the mechanisms of addiction and tolerance in benzodiazepine treatments. This has shown promise in the development of tranquilizers with minimal side effects such as cognitive impairment, dependence, and tolerance. A valium-like drug without its side effects, as repeatedly demonstrated in animals, is achievable.
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Affiliation(s)
| | | | | | - Mahir Tuli
- University of British Columbia, Vancouver, BC, Canada
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103
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Annecchino LA, Schultz SR. Progress in automating patch clamp cellular physiology. Brain Neurosci Adv 2018; 2:2398212818776561. [PMID: 32166142 PMCID: PMC7058203 DOI: 10.1177/2398212818776561] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2018] [Accepted: 04/19/2018] [Indexed: 12/30/2022] Open
Abstract
Patch clamp electrophysiology has transformed research in the life sciences over the last few decades. Since their inception, automatic patch clamp platforms have evolved considerably, demonstrating the capability to address both voltage- and ligand-gated channels, and showing the potential to play a pivotal role in drug discovery and biomedical research. Unfortunately, the cell suspension assays to which early systems were limited cannot recreate biologically relevant cellular environments, or capture higher order aspects of synaptic physiology and network dynamics. In vivo patch clamp electrophysiology has the potential to yield more biologically complex information and be especially useful in reverse engineering the molecular and cellular mechanisms of single-cell and network neuronal computation, while capturing important aspects of human disease mechanisms and possible therapeutic strategies. Unfortunately, it is a difficult procedure with a steep learning curve, which has restricted dissemination of the technique. Luckily, in vivo patch clamp electrophysiology seems particularly amenable to robotic automation. In this review, we document the development of automated patch clamp technology, from early systems based on multi-well plates through to automated planar-array platforms, and modern robotic platforms capable of performing two-photon targeted whole-cell electrophysiological recordings in vivo.
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Affiliation(s)
- Luca A. Annecchino
- Centre for Neurotechnology and Department of Bioengineering, Imperial College London, London, UK
| | - Simon R. Schultz
- Centre for Neurotechnology and Department of Bioengineering, Imperial College London, London, UK
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104
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Altered Gene Expression of RNF34 and PACAP Possibly Involved in Mechanism of Exercise-Induced Analgesia for Neuropathic Pain in Rats. Int J Mol Sci 2017; 18:ijms18091962. [PMID: 28902127 PMCID: PMC5618611 DOI: 10.3390/ijms18091962] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Revised: 08/29/2017] [Accepted: 09/04/2017] [Indexed: 01/19/2023] Open
Abstract
Despite the availability of several modalities of treatment, including surgery, pharmacological agents, and nerve blocks, neuropathic pain is often unresponsive and sometimes progresses to intractable chronic pain. Although exercise therapy is a candidate for treatment of neuropathic pain, the mechanism underlying its efficacy has not been elucidated. To clarify the molecular mechanism for pain relief induced by exercise, we measured Rnf34 and Pacap mRNA levels in the spinal cord dorsal horn of SNL rats, a model of neuropathic pain. SNL model rats exhibited stable mechanical hyperalgesia for at least 6 weeks. When the rats were forced to exercise on a treadmill, mechanical and thermal hyperalgesia were significantly ameliorated compared with the non-exercise group. Accordingly, gene expression level of Rnf34 and Pacap were also significantly altered in the time course analysis after surgery. These results suggest that exercise therapy possibly involves pain relief in SNL rats by suppressing Rnf34 and Pacap expression in the spinal cord.
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105
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Bell DC, Dallas ML. Using automated patch clamp electrophysiology platforms in pain-related ion channel research: insights from industry and academia. Br J Pharmacol 2017. [PMID: 28622411 DOI: 10.1111/bph.13916] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Automated patch clamp (APC) technology was first developed at the turn of the millennium. The increased throughput it afforded promised a new paradigm in ion channel recordings, offering the potential to overcome the time-consuming, low-throughput bottleneck, arising from manual patch clamp investigations. This has relevance to the fast-paced development of novel therapies for chronic pain. This review highlights the advances in technology, using select examples that have facilitated APC usage in both industry and academia. It covers both first generation and the latest developments in second-generation platforms. In addition, it also provides an overview of the pain research field and how APC platforms have furthered our understanding of ion channel research and the development of pharmacological tools and therapeutics. APC platforms have much to offer to the ion channel research community, and this review highlights areas of best practice for both academia and industry. The impact of APC platforms and the prospects of ion channel research and improved therapeutics for chronic pain will be evaluated. LINKED ARTICLES This article is part of a themed section on Recent Advances in Targeting Ion Channels to Treat Chronic Pain. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v175.12/issuetoc.
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Affiliation(s)
| | - Mark L Dallas
- School of Pharmacy, University of Reading, Reading, UK
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106
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Functional Synaptic Integration of Forebrain GABAergic Precursors into the Adult Spinal Cord. J Neurosci 2017; 36:11634-11645. [PMID: 27852772 DOI: 10.1523/jneurosci.2301-16.2016] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Revised: 08/26/2016] [Accepted: 08/31/2016] [Indexed: 01/17/2023] Open
Abstract
Spinal cord transplants of embryonic cortical GABAergic progenitor cells derived from the medial ganglionic eminence (MGE) can reverse mechanical hypersensitivity in the mouse models of peripheral nerve injury- and paclitaxel-induced neuropathic pain. Here, we used electrophysiology, immunohistochemistry, and electron microscopy to examine the extent to which MGE cells integrate into host circuitry and recapitulate endogenous inhibitory circuits. Whether the transplants were performed before or after nerve injury, the MGE cells developed into mature neurons and exhibited firing patterns characteristic of subpopulations of cortical and spinal cord inhibitory interneurons. Conversely, the transplanted cells preserved cortical morphological and neurochemical properties. We also observed a robust anatomical and functional synaptic integration of the transplanted cells into host circuitry in both injured and uninjured animals. The MGE cells were activated by primary afferents, including TRPV1-expressing nociceptors, and formed GABAergic, bicuculline-sensitive, synapses onto host neurons. Unexpectedly, MGE cells transplanted before injury prevented the development of mechanical hypersensitivity. Together, our findings provide direct confirmation of an extensive, functional synaptic integration of MGE cells into host spinal cord circuits. This integration underlies normalization of the dorsal horn inhibitory tone after injury and may be responsible for the prophylactic effect of preinjury transplants. SIGNIFICANCE STATEMENT Spinal cord transplants of embryonic cortical GABAergic interneuron progenitors from the medial ganglionic eminence (MGE), can overcome the mechanical hypersensitivity produced in different neuropathic pain models in adult mice. Here, we examined the properties of transplanted MGE cells and the extent to which they integrate into spinal cord circuitry. Using electrophysiology, immunohistochemistry, and electron microscopy, we demonstrate that MGE cells, whether transplanted before or after nerve injury, develop into inhibitory neurons, are activated by nociceptive primary afferents, and form GABA-A-mediated inhibitory synapses with the host. Unexpectedly, cells transplanted into naive spinal cord prevented the development of nerve-injury-induced mechanical hypersensitivity. These results illustrate the remarkable plasticity of adult spinal cord and the potential of cell-based therapies against neuropathic pain.
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107
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mir-500-Mediated GAD67 Downregulation Contributes to Neuropathic Pain. J Neurosci 2017; 36:6321-31. [PMID: 27277808 DOI: 10.1523/jneurosci.0646-16.2016] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Accepted: 04/28/2016] [Indexed: 12/18/2022] Open
Abstract
UNLABELLED Neuropathic pain is a common neurobiological disease involving multifaceted maladaptations ranging from gene modulation to synaptic dysfunction, but the interactions between synaptic dysfunction and the genes that are involved in persistent pain remain elusive. In the present study, we found that neuropathic pain induced by the chemotherapeutic drug paclitaxel or L5 ventral root transection significantly impaired the function of GABAergic synapses of spinal dorsal horn neurons via the reduction of the GAD67 expression. We also found that mir-500 expression was significantly increased and involved in the modulation of GAD67 expression via targeting the specific site of Gad1 gene in the dorsal horn. In addition, knock-out of mir-500 or using mir-500 antagomir rescued the GABAergic synapses in the spinal dorsal horn neurons and attenuated the sensitized pain behavior in the rats with neuropathic pain. To our knowledge, this is the first study to investigate the function significance and the underlying molecular mechanisms of mir-500 in the process of neuropathic pain, which sheds light on the development of novel therapeutic options for neuropathic pain. SIGNIFICANCE STATEMENT Neuropathic pain is a common neurobiological disease involving multifaceted maladaptations ranging from gene modulation to synaptic dysfunction, but the underlying molecular mechanisms remain elusive. The present study illustrates for the first time a mir-500-mediated mechanism underlying spinal GABAergic dysfunction and sensitized pain behavior in neuropathic pain induced by the chemotherapeutic drug paclitaxel or L5 ventral root transection, which sheds light on the development of novel therapeutic options for neuropathic pain.
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108
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Activation of cortical somatostatin interneurons prevents the development of neuropathic pain. Nat Neurosci 2017; 20:1122-1132. [PMID: 28671692 PMCID: PMC5559271 DOI: 10.1038/nn.4595] [Citation(s) in RCA: 94] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2016] [Accepted: 05/20/2017] [Indexed: 12/13/2022]
Abstract
Neuropathic pain involves long-lasting modifications of pain pathways that result in abnormal cortical activity. How cortical circuits are altered and contribute to the intense sensation associated with allodynia is unclear. Here we report a persistent elevation of layer V pyramidal neuron activity in the somatosensory cortex of a mouse model of neuropathic pain. This enhanced pyramidal neuron activity was caused in part by increases of synaptic activity and NMDA-receptor-dependent calcium spikes in apical tuft dendrites. Furthermore, local inhibitory interneuron networks shifted their activity in favor of pyramidal neuron hyperactivity: somatostatin-expressing and parvalbumin-expressing inhibitory neurons reduced their activity, whereas vasoactive intestinal polypeptide–expressing interneurons increased their activity. Pharmacogenetic activation of somatostatin-expressing cells reduced pyramidal neuron hyperactivity and reversed mechanical allodynia. These findings reveal cortical circuit changes that arise during the development of neuropathic pain and identify the activation of specific cortical interneurons as therapeutic targets for chronic pain treatment.
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109
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Lewter LA, Fisher JL, Siemian JN, Methuku KR, Poe MM, Cook JM, Li JX. Antinociceptive Effects of a Novel α2/α3-Subtype Selective GABA A Receptor Positive Allosteric Modulator. ACS Chem Neurosci 2017; 8:1305-1312. [PMID: 28150939 DOI: 10.1021/acschemneuro.6b00447] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Pain remains a challenging clinical condition and spinal GABAA receptors are crucial modulators of pain processing. α2/α3-subtype GABAA receptors mediate the analgesic actions of benzodiazepines. Positive allosteric modulators (PAMs) at α2/α3-subtype GABAA receptors may have analgesic potential. Here we report a new selective α2/α3-subtype GABAA receptor PAM in in vitro and in vivo pain assays. KRM-II-81 demonstrated similar efficacy at α1/α2/α3 GABAA receptors and negligible efficacy at α4/α5/α6 GABAA receptors, with α2 and α3-subtypes being 17- and 28-fold more potent than α1 subtypes in HEK-293T cells expressing GABAA receptors with different α subunits. In contrast, KRM-II-18B showed significant efficacy at α1/α2/α3/ α5 subtypes, with similar potency at α1/α2/α3 subtypes. Both PAMs and morphine dose-dependently decreased 0.6% acetic acid- and 0.32% lactic acid-induced writhing. The effects of both PAMs were reversed by the benzodiazepine receptor antagonist flumazenil, confirming their action at the benzodiazepine binding site of GABAA receptors. Both PAMS and morphine all dose-dependently reversed 0.32% lactic acid (but not 0.6% acetic acid) induced suppression of nesting behavior. Acetaminophen, but not the PAMs, reversed acid-depressed locomotor activity. Combined, these findings suggest that KRM-II-81 is a selective α2/α3 subtype GABAA PAM with significant antinociceptive effects in chemical stimulation-induced pain in mice.
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Affiliation(s)
- Lakeisha A. Lewter
- Department of Pharmacology and Toxicology, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, New York 14214, United States
| | - Janet L. Fisher
- Department of Pharmacology, Physiology & Neuroscience, School of Medicine, University of South Carolina, Columbia, South Carolina 29208, United States
| | - Justin N. Siemian
- Department of Pharmacology and Toxicology, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, New York 14214, United States
| | - Kashi Reddy Methuku
- Department of Chemistry, University of Wisconsin—Milwaukee, Milwaukee, Wisconsin 53211, United States
| | - Michael M. Poe
- Department of Chemistry, University of Wisconsin—Milwaukee, Milwaukee, Wisconsin 53211, United States
| | - James M. Cook
- Department of Chemistry, University of Wisconsin—Milwaukee, Milwaukee, Wisconsin 53211, United States
| | - Jun-Xu Li
- Department of Pharmacology and Toxicology, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, New York 14214, United States
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110
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Abstract
Acute and chronic pain complaints, although common, are generally poorly served by existing therapies. This unmet clinical need reflects a failure to develop novel classes of analgesics with superior efficacy, diminished adverse effects and a lower abuse liability than those currently available. Reasons for this include the heterogeneity of clinical pain conditions, the complexity and diversity of underlying pathophysiological mechanisms, and the unreliability of some preclinical pain models. However, recent advances in our understanding of the neurobiology of pain are beginning to offer opportunities for developing novel therapeutic strategies and revisiting existing targets, including modulating ion channels, enzymes and G-protein-coupled receptors.
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111
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Abstract
Over the past three decades the research on GABAB receptor biology and pharmacology in pain processing has been a fascinating experience. Norman Bowery's fundamental discovery of the existence of the GABAB receptor has led the way to the definition of GABAB molecular mechanisms; patterns of receptor expression in the peripheral and central nervous system; GABAB modulatory functions within the pain pathways. We are now harnessing this acquired knowledge to develop innovative approaches to the therapeutic management of chronic pain through allosteric modulation of the GABAB. Norman's legacy would be ultimately fulfilled by the development of novel analgesics that activate the GABAB receptor. This article is part of the "Special Issue Dedicated to Norman G. Bowery".
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Affiliation(s)
- Marzia Malcangio
- Wolfson Centre for Age Related Diseases, King's College London, London SE1 1UL, UK.
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112
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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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113
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Fischer BD, Schlitt RJ, Hamade BZ, Rehman S, Ernst M, Poe MM, Li G, Kodali R, Arnold LA, Cook JM. Pharmacological and antihyperalgesic properties of the novel α2/3 preferring GABA A receptor ligand MP-III-024. Brain Res Bull 2017; 131:62-69. [PMID: 28267561 PMCID: PMC5501353 DOI: 10.1016/j.brainresbull.2017.03.001] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2017] [Accepted: 03/01/2017] [Indexed: 12/11/2022]
Abstract
γ-Aminobutyric acid type A (GABAA) receptors are located in spinal nociceptive circuits where they modulate the transmission of pain sensory signals from the periphery to higher centers. Benzodiazepine-type drugs bind to GABAA receptors containing α1, α2, α3, and α5 subunits (α1GABAA, α2GABAA, α3GABAA and α5GABAA receptors, respectively) through which they inhibit the transmission of these signals. In the present study we describe the novel benzodiazepine site positive allosteric modulator modulator methyl 8-ethynyl-6-(pyridin-2-yl)-4H-benzo[f]imidazo[1,5-a][1,4]diazepine-3-carboxylate (MP-III-024). MP-III-024 displayed preference for α2GABAA and α3GABAA receptors relative to α1GABAA and α5GABAA receptors as well as an improved metabolic profile relative to subtype-selective positive modulators that are available currently. Administration of MP-III-024 resulted in a dose- and time-dependent reversal of mechanical hyperalgesia. On locomotor activity and schedule-controlled responding, MP-III-024 was ineffective across the doses tested. These data provide further evidence that α2GABAA and α3GABAA receptors play an important role in the antihyperalgesic effects and may not be involved in some of the undesired effects of benzodiazepine-like drugs. Further, these findings suggest that MP-III-024 is a suitable research tool for investigating the role of α2GABAA and α3GABAA receptors in the behavioral properties of benzodiazepine-like drugs in mice.
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Affiliation(s)
- Bradford D Fischer
- Cooper Medical School of Rowan University, Department of Biomedical Sciences Camden, NJ 08103, USA.
| | - Raymond J Schlitt
- Cooper Medical School of Rowan University, Department of Biomedical Sciences Camden, NJ 08103, USA
| | - Bryan Z Hamade
- Cooper Medical School of Rowan University, Department of Biomedical Sciences Camden, NJ 08103, USA
| | - Sabah Rehman
- Medical University of Vienna, Department of Molecular Neurosciences, 1090 Vienna, Austria
| | - Margot Ernst
- Medical University of Vienna, Department of Molecular Neurosciences, 1090 Vienna, Austria
| | - Michael M Poe
- University of Wisconsin-Milwaukee, Department of Chemistry and Biochemistry and the Milwaukee Institute for Drug Discovery, Milwaukee, WI 53201, USA
| | - Guanguan Li
- University of Wisconsin-Milwaukee, Department of Chemistry and Biochemistry and the Milwaukee Institute for Drug Discovery, Milwaukee, WI 53201, USA
| | - Revathi Kodali
- University of Wisconsin-Milwaukee, Department of Chemistry and Biochemistry and the Milwaukee Institute for Drug Discovery, Milwaukee, WI 53201, USA
| | - Leggy A Arnold
- University of Wisconsin-Milwaukee, Department of Chemistry and Biochemistry and the Milwaukee Institute for Drug Discovery, Milwaukee, WI 53201, USA
| | - James M Cook
- University of Wisconsin-Milwaukee, Department of Chemistry and Biochemistry and the Milwaukee Institute for Drug Discovery, Milwaukee, WI 53201, USA
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114
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Curcumol allosterically modulates GABA(A) receptors in a manner distinct from benzodiazepines. Sci Rep 2017; 7:46654. [PMID: 28436443 PMCID: PMC5402396 DOI: 10.1038/srep46654] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2016] [Accepted: 03/22/2017] [Indexed: 12/11/2022] Open
Abstract
Inhibitory A type γ-aminobutyric acid receptors (GABAARs) play a pivotal role in orchestrating various brain functions and represent an important molecular target in neurological and psychiatric diseases, necessitating the need for the discovery and development of novel modulators. Here, we show that a natural compound curcumol, acts as an allosteric enhancer of GABAARs in a manner distinct from benzodiazepines. Curcumol markedly facilitated GABA-activated currents and shifted the GABA concentration-response curve to the left in cultured hippocampal neurons. When co-applied with the classical benzodiazepine diazepam, curcumol further potentiated GABA-induced currents. In contrast, in the presence of a saturating concentration of menthol, a positive modulator for GABAAR, curcumol failed to further enhance GABA-induced currents, suggesting shared mechanisms underlying these two agents on GABAARs. Moreover, the benzodiazepine antagonist flumazenil did not alter the enhancement of GABA response by curcumol and menthol, but abolished that by DZP. Finally, mutations at the β2 or γ2 subunit predominantly eliminated modulation of recombinant GABAARs by curcumol and menthol, or diazepam, respectively. Curcumol may therefore exert its actions on GABAARs at sites distinct from benzodiazepine sites. These findings shed light on the future development of new therapeutics drugs targeting GABAARs.
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115
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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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116
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The Transition of Acute Postoperative Pain to Chronic Pain: An Integrative Overview of Research on Mechanisms. THE JOURNAL OF PAIN 2017; 18:359.e1-359.e38. [DOI: 10.1016/j.jpain.2016.11.004] [Citation(s) in RCA: 180] [Impact Index Per Article: 25.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2016] [Revised: 10/15/2016] [Accepted: 11/16/2016] [Indexed: 01/01/2023]
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117
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Müller Herde A, Benke D, Ralvenius WT, Mu L, Schibli R, Zeilhofer HU, Krämer SD. GABAA receptor subtypes in the mouse brain: Regional mapping and diazepam receptor occupancy by in vivo [18F]flumazenil PET. Neuroimage 2017; 150:279-291. [DOI: 10.1016/j.neuroimage.2017.02.022] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2016] [Revised: 01/22/2017] [Accepted: 02/09/2017] [Indexed: 12/19/2022] Open
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118
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Xue M, Liu J, Yang Y, Suo Z, Yang X, Hu X. Inhibition of α5 subunit-containing GABAAreceptors facilitated spinal nociceptive transmission and plasticity. Eur J Pain 2017; 21:1061-1071. [DOI: 10.1002/ejp.1009] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/12/2016] [Indexed: 01/09/2023]
Affiliation(s)
- M. Xue
- Department of Molecular Pharmacology, School of Pharmacy; Lanzhou University; China
| | - J.P. Liu
- Department of Molecular Pharmacology, School of Pharmacy; Lanzhou University; China
| | - Y.H. Yang
- Department of Molecular Pharmacology, School of Pharmacy; Lanzhou University; China
| | - Z.W. Suo
- Department of Molecular Pharmacology, School of Pharmacy; Lanzhou University; China
| | - X. Yang
- Department of Molecular Pharmacology, School of Pharmacy; Lanzhou University; China
| | - X.D. Hu
- Department of Molecular Pharmacology, School of Pharmacy; Lanzhou University; China
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119
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Lind AL, Emami Khoonsari P, Sjödin M, Katila L, Wetterhall M, Gordh T, Kultima K. Spinal Cord Stimulation Alters Protein Levels in the Cerebrospinal Fluid of Neuropathic Pain Patients: A Proteomic Mass Spectrometric Analysis. Neuromodulation 2017; 19:549-62. [PMID: 27513633 DOI: 10.1111/ner.12473] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2015] [Revised: 06/07/2016] [Accepted: 06/09/2016] [Indexed: 01/03/2023]
Abstract
OBJECTIVES Electrical neuromodulation by spinal cord stimulation (SCS) is a well-established method for treatment of neuropathic pain. However, the mechanism behind the pain relieving effect in patients remains largely unknown. In this study, we target the human cerebrospinal fluid (CSF) proteome, a little investigated aspect of SCS mechanism of action. METHODS Two different proteomic mass spectrometry protocols were used to analyze the CSF of 14 SCS responsive neuropathic pain patients. Each patient acted as his or her own control and protein content was compared when the stimulator was turned off for 48 hours, and after the stimulator had been used as normal for three weeks. RESULTS Eighty-six proteins were statistically significantly altered in the CSF of neuropathic pain patients using SCS, when comparing the stimulator off condition to the stimulator on condition. The top 12 of the altered proteins are involved in neuroprotection (clusterin, gelsolin, mimecan, angiotensinogen, secretogranin-1, amyloid beta A4 protein), synaptic plasticity/learning/memory (gelsolin, apolipoprotein C1, apolipoprotein E, contactin-1, neural cell adhesion molecule L1-like protein), nociceptive signaling (neurosecretory protein VGF), and immune regulation (dickkopf-related protein 3). CONCLUSION Previously unknown effects of SCS on levels of proteins involved in neuroprotection, nociceptive signaling, immune regulation, and synaptic plasticity are demonstrated. These findings, in the CSF of neuropathic pain patients, expand the picture of SCS effects on the neurochemical environment of the human spinal cord. An improved understanding of SCS mechanism may lead to new tracks of investigation and improved treatment strategies for neuropathic pain.
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Affiliation(s)
- Anne-Li Lind
- Department of Surgical Sciences, Anaesthesiology and Intensive Care, Uppsala University, Uppsala, Sweden
| | - Payam Emami Khoonsari
- Department of Medical Sciences, Cancer Pharmacology and Computational Medicine, Uppsala University, Uppsala, Sweden
| | - Marcus Sjödin
- Department of Chemistry-BMC, Analytical Chemistry, Uppsala University, Uppsala//GE Healthcare, Sweden
| | - Lenka Katila
- Department of Surgical Sciences, Anaesthesiology and Intensive Care, Uppsala University, Uppsala, Sweden
| | - Magnus Wetterhall
- Department of Chemistry-BMC, Analytical Chemistry, Uppsala University, Uppsala//GE Healthcare, Sweden
| | - Torsten Gordh
- Department of Surgical Sciences, Anaesthesiology and Intensive Care, Uppsala University, Uppsala, Sweden
| | - Kim Kultima
- Department of Medical Sciences, Cancer Pharmacology and Computational Medicine, Uppsala University, Uppsala, Sweden
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Khangura RK, Bali A, Jaggi AS, Singh N. Histone acetylation and histone deacetylation in neuropathic pain: An unresolved puzzle? Eur J Pharmacol 2017; 795:36-42. [DOI: 10.1016/j.ejphar.2016.12.001] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2016] [Revised: 11/25/2016] [Accepted: 12/01/2016] [Indexed: 12/18/2022]
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Abstract
It has been recently proposed that α5-subunit containing GABAA receptors (α5-GABAA receptors) that mediate tonic inhibition might be involved in pain. The purpose of this study was to investigate the contribution of α5-GABAA receptors in the loss of GABAergic inhibition and in formalin-induced, complete Freund's adjuvant (CFA)-induced and L5 and L6 spinal nerve ligation-induced long-lasting hypersensitivity. Formalin or CFA injection and L5 and L6 spinal nerve ligation produced long-lasting allodynia and hyperalgesia. Moreover, formalin injection impaired the rate-dependent depression of the Hofmann reflex. Peripheral and intrathecal pretreatment or post-treatment with the α5-GABAA receptor antagonist, L-655,708 (0.15-15 nmol), prevented and reversed, respectively, these long-lasting behaviors. Formalin injection increased α5-GABAA receptor mRNA expression in the spinal cord and dorsal root ganglia (DRG) mainly at 3 days. The α5-GABAA receptors were localized in the dorsal spinal cord and DRG colabeling with NeuN, CGRP, and IB4 which suggests their presence in peptidergic and nonpeptidergic neurons. These receptors were found mainly in small and medium sized neurons. Formalin injection enhanced α5-GABAA receptor fluorescence intensity in spinal cord and DRG at 3 and 6 days. Intrathecal administration of L-655,708 (15 nmol) prevented and reversed formalin-induced impairment of rate-dependent depression. These results suggest that α5-GABAA receptors play a role in the loss of GABAergic inhibition and contribute to long-lasting secondary allodynia and hyperalgesia.
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122
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Poe MM, Methuku KR, Li G, Verma AR, Teske KA, Stafford DC, Arnold LA, Cramer JW, Jones TM, Cerne R, Krambis MJ, Witkin JM, Jambrina E, Rehman S, Ernst M, Cook JM, Schkeryantz JM. Synthesis and Characterization of a Novel γ-Aminobutyric Acid Type A (GABA A) Receptor Ligand That Combines Outstanding Metabolic Stability, Pharmacokinetics, and Anxiolytic Efficacy. J Med Chem 2016; 59:10800-10806. [PMID: 27933953 DOI: 10.1021/acs.jmedchem.6b01332] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
1,4-Benzodiazepines are used in the treatment of anxiety disorders but have limited long-term use due to adverse effects. HZ-166 (2) has been shown to have anxiolytic-like effects with reduced sedative/ataxic liabilities. A 1,3-oxazole KRM-II-81 (9) was discovered from a series of six bioisosteres with significantly improved pharmacokinetic and pharmacodynamic properties as compared to 2. Oxazole 9 was further characterized and exhibited improved anxiolytic-like effects in a mouse marble burying assay and a rat Vogel conflict test.
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Affiliation(s)
- Michael M Poe
- Department of Chemistry and Biochemistry and the Milwaukee Institute for Drug Discovery, University of Wisconsin-Milwaukee , Milwaukee, Wisconsin 53201, United States
| | - Kashi Reddy Methuku
- Department of Chemistry and Biochemistry and the Milwaukee Institute for Drug Discovery, University of Wisconsin-Milwaukee , Milwaukee, Wisconsin 53201, United States
| | - Guanguan Li
- Department of Chemistry and Biochemistry and the Milwaukee Institute for Drug Discovery, University of Wisconsin-Milwaukee , Milwaukee, Wisconsin 53201, United States
| | - Ashwini R Verma
- Department of Chemistry and Biochemistry and the Milwaukee Institute for Drug Discovery, University of Wisconsin-Milwaukee , Milwaukee, Wisconsin 53201, United States
| | - Kelly A Teske
- Department of Chemistry and Biochemistry and the Milwaukee Institute for Drug Discovery, University of Wisconsin-Milwaukee , Milwaukee, Wisconsin 53201, United States
| | - Douglas C Stafford
- Department of Chemistry and Biochemistry and the Milwaukee Institute for Drug Discovery, University of Wisconsin-Milwaukee , Milwaukee, Wisconsin 53201, United States
| | - Leggy A Arnold
- Department of Chemistry and Biochemistry and the Milwaukee Institute for Drug Discovery, University of Wisconsin-Milwaukee , Milwaukee, Wisconsin 53201, United States
| | - Jeffrey W Cramer
- Lilly Research Laboratories, Eli Lilly and Company , Indianapolis, Indiana 42685, United States
| | - Timothy M Jones
- Lilly Research Laboratories, Eli Lilly and Company , Indianapolis, Indiana 42685, United States
| | - Rok Cerne
- Lilly Research Laboratories, Eli Lilly and Company , Indianapolis, Indiana 42685, United States
| | - Michael J Krambis
- Lilly Research Laboratories, Eli Lilly and Company , Indianapolis, Indiana 42685, United States
| | - Jeffrey M Witkin
- Lilly Research Laboratories, Eli Lilly and Company , Indianapolis, Indiana 42685, United States
| | - Enrique Jambrina
- Lilly Research Laboratories, Eli Lilly and Company , 28108 Alcobendas, Spain
| | - Sabah Rehman
- Department for Molecular Neurosciences, Medical University of Vienna , 1090 Vienna, Austria
| | - Margot Ernst
- Department for Molecular Neurosciences, Medical University of Vienna , 1090 Vienna, Austria
| | - James M Cook
- Department of Chemistry and Biochemistry and the Milwaukee Institute for Drug Discovery, University of Wisconsin-Milwaukee , Milwaukee, Wisconsin 53201, United States
| | - Jeffrey M Schkeryantz
- Lilly Research Laboratories, Eli Lilly and Company , Indianapolis, Indiana 42685, United States
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Chagraoui A, Skiba M, Thuillez C, Thibaut F. To what extent is it possible to dissociate the anxiolytic and sedative/hypnotic properties of GABAA receptors modulators? Prog Neuropsychopharmacol Biol Psychiatry 2016; 71:189-202. [PMID: 27495357 DOI: 10.1016/j.pnpbp.2016.08.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/13/2016] [Revised: 07/21/2016] [Accepted: 08/01/2016] [Indexed: 01/16/2023]
Abstract
The relatively common view indicates a possible dissociation between the anxiolytic and sedative/hypnotic properties of benzodiazepines (BZs). Indeed, GABAA receptor (GABAAR) subtypes have specific cerebral distribution in distinct neural circuits. Thus, GABAAR subtype-selective drugs may be expected to perform distinct functions. However, standard behavioral test assays provide limited direction towards highlighting new action mechanisms of ligands targeting GABAARs. Automated behavioral tests, lack sensitivity as some behavioral characteristics or subtle behavioral changes of drug effects or that are not considered in the overall analysis (Ohl et al., 2001) and observation-based analyses are not always performed. In addition, despite the use of genetically engineered mice, any possible dissociation between the anxiolytic and sedative properties of BZs remains controversial. Moreover, the involvement the different subtypes of GABAAR subtypes in the anxious behavior and the mechanism of action of anxiolytic agents remains unclear since there has been little success in the pharmacological investigations so far. This raises the question of the involvement of the different subunits in anxiolytic-like and/or sedative effects; and the actual implication of these subunits, particularly, α-subunits in the modulation of sedation and/or anxiety-related disorders. This present review was prompted by several conflicting studies on the degree of involvement of these subunits in anxiolytic-like and/or sedative effects. To this end, we explored the GABAergic system, particularly, the role of different subunits containing synaptic GABAARs. We report herein the targeting gene encoding the different subunits and their contribution in anxiolytic-like and/or sedative actions, as well as, the mechanism underlying tolerance to BZs.
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Affiliation(s)
- A Chagraoui
- Inserm U982, Laboratory of Neuronal and Neuroendocrine Differentiation and Communication, Institute for Research and Innovation in Biomedecine, Normandy University, France; Department of Medical Biochemistry, Rouen University Hospital, Rouen, France.
| | - M Skiba
- Inserm U982, Laboratory of Neuronal and Neuroendocrine Differentiation and Communication, Institute for Research and Innovation in Biomedecine, Normandy University, France
| | - C Thuillez
- Department of Pharmacology, Rouen University Hospital, Rouen, and INSERM U1096, Laboratory of New Pharmacological Targets for Endothelial Protection and Heart Failure, Institute for Research and Innovation in Biomedicine, Normandy University, France
| | - F Thibaut
- Department of Psychiatry, University Hospital Cochin (site Tarnier), University of Paris-Descartes and INSERM U 894 Laboratory of Psychiatry and Neurosciences, Paris, France
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Perez-Sanchez J, Lorenzo LE, Lecker I, Zurek AA, Labrakakis C, Bridgwater EM, Orser BA, De Koninck Y, Bonin RP. α5GABAAReceptors Mediate Tonic Inhibition in the Spinal Cord Dorsal Horn and Contribute to the Resolution Of Hyperalgesia. J Neurosci Res 2016; 95:1307-1318. [DOI: 10.1002/jnr.23981] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2016] [Revised: 10/02/2016] [Accepted: 10/06/2016] [Indexed: 12/12/2022]
Affiliation(s)
| | | | - Irene Lecker
- Leslie Dan Faculty of Pharmacy; University of Toronto; Toronto Ontario Canada
| | | | - Charalampos Labrakakis
- Department of Biological Applications and Technology; University of Ioannina; Ioannina Greece
| | | | - Beverley A. Orser
- University of Toronto, Department of Physiology; Toronto Ontario Canada
- University of Toronto, Department of Anesthesia; Toronto Ontario Canada
- Department of Anesthesia; Sunnybrook Health Sciences Centre; Toronto Ontario Canada
| | - Yves De Koninck
- Institut Universitaire en Santé Mentale de Québec; Québec Canada
- Department of Psychiatry and Neuroscience; Université Laval; Québec Canada
| | - Robert P. Bonin
- Institut Universitaire en Santé Mentale de Québec; Québec Canada
- Leslie Dan Faculty of Pharmacy; University of Toronto; Toronto Ontario Canada
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125
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Akbar S, Subhan F, Karim N, Shahid M, Ahmad N, Ali G, Mahmood W, Fawad K. 6-Methoxyflavanone attenuates mechanical allodynia and vulvodynia in the streptozotocin-induced diabetic neuropathic pain. Biomed Pharmacother 2016; 84:962-971. [PMID: 27764759 DOI: 10.1016/j.biopha.2016.10.017] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2016] [Revised: 10/03/2016] [Accepted: 10/06/2016] [Indexed: 12/26/2022] Open
Abstract
BACKGROUND Diabetic neuropathy is the most prevalent, persistent and debilitating complication of diabetes mellitus often coupled with vulvodynia that may present as an isolated symptom or as a part of constellation of other neuropathic abnormalities. OBJECTIVE Flavonoids have selective affinity for GABA receptors and 6-methoxyflavanone (6-MeOF) is a positive allosteric modulator of GABA responses at human recombinant GABAA receptors. GABAergic and opioidergic system inhibition have been shown to facilitate neuropathic pain. METHODS 6-MeOF was evaluated for analgesic effect in the hot plate test and streptozotocin-induced diabetic neuropathic pain in female rats using von Frey hairs. The possible involvement of opioidergic and GABAergic mechanisms was investigated using naloxone and pentylenetetrazole (PTZ) antagonists, respectively. The biodistribution of 6-MeOF in plasma and CNS was examined using a validated HPLC/UV analytical method. The binding affinity of 6-MeOF with opioid and GABA receptors was studied using molecular docking simulation approach. RESULTS 6-MeOF (10 and 30mg/kg) attenuated the acute phasic thermal nociception in the hot plate test while in the case of streptozotocin-induced diabetic neuropathy model, 6-MeOF (10 and 30mg/kg) produced static/dynamic anti-allodynic (increased paw withdrawal threshold and latency) as well as static/dynamic anti-vulvodynic effects (increased flinching response threshold and latency), when compared to the vehicle and standard gabapentin (75mg/kg). In silico studies depicted the preference of 6-MeOF for the delta- and kappa-opioid and GABAA receptors. Moreover, the pharmacokinetic profile revealed a quick appearance of 6-MeOF in the systemic circulation and brain areas with maximum concentration observed after 30min in the amygdala, brain stem and cerebral cortex. CONCLUSION 6-MeOF readily crosses the blood brain barrier and may be effective in attenuating the diabetes-induced allodynia as well as vulvodynia, probably through interactions with the GABAergic and opioidergic systems.
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Affiliation(s)
- Shehla Akbar
- Department of Pharmacy, University of Peshawar, Peshawar, Pakistan.
| | - Fazal Subhan
- Department of Pharmacy, University of Peshawar, Peshawar, Pakistan.
| | - Nasiara Karim
- Department of Pharmacy, University of Malakand, Chakdara, Pakistan.
| | - Muhammad Shahid
- Department of Pharmacy, University of Peshawar, Peshawar, Pakistan.
| | - Nisar Ahmad
- Department of Pharmacy, University of Peshawar, Peshawar, Pakistan.
| | - Gowhar Ali
- Department of Pharmacy, University of Peshawar, Peshawar, Pakistan.
| | - Wajahat Mahmood
- Department of Pharmacy, COMSATS Institute of Information Technology, Abbottabad, Pakistan.
| | - Khwaja Fawad
- Department of Pharmacy, University of Peshawar, Peshawar, Pakistan.
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Reduction of chronic abdominal pain in patients with inflammatory bowel disease through transcranial direct current stimulation: a randomized controlled trial. Pain 2016; 157:429-437. [PMID: 26469395 DOI: 10.1097/j.pain.0000000000000386] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Inflammatory bowel disease (IBD) is frequently associated with chronic abdominal pain (CAP). Transcranial direct current stimulation (tDCS) has been proven to reduce chronic pain. This study aimed to investigate the effects of tDCS in patients with CAP due to IBD. This randomized, sham-controlled, double blind, parallel-designed study included 20 patients with either Crohn disease or ulcerative colitis with CAP (≥3/10 on the visual analog scale (VAS) in 3/6 months). Anodal or sham tDCS was applied over the primary motor cortex for 5 consecutive days (2 mA, 20 minutes). Assessments included VAS, pressure pain threshold, inflammatory markers, and questionnaires on quality of life, functional and disease specific symptoms (Irritable Bowel Syndrome-Severity Scoring System [IBS-SSS]), disease activity, and pain catastrophizing. Follow-up data were collected 1 week after the end of the stimulation. Statistical analyses were performed using analysis of variance and t tests. There was a significant reduction of abdominal pain in the anodal tDCS group compared with sham tDCS. This effect was evident in changes in VAS and pressure pain threshold on the left and right sides of the abdomen. In addition, 1 week after stimulation, pain reduction remained significantly decreased in the right side of the abdomen. There was also a significant reduction in scores on pain catastrophizing and on IBS-SSS when comparing both groups. Inflammatory markers and disease activity did not differ significantly between groups throughout the experiment. Transcranial direct current stimulation proved to be an effective and clinically relevant therapeutic strategy for CAP in IBD. The analgesic effects observed are unrelated to inflammation and disease activity, which emphasizes central pain mechanisms in CAP.
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Ralvenius WT, Acuña MA, Benke D, Matthey A, Daali Y, Rudolph U, Desmeules J, Zeilhofer HU, Besson M. The clobazam metabolite N-desmethyl clobazam is an α2 preferring benzodiazepine with an improved therapeutic window for antihyperalgesia. Neuropharmacology 2016; 109:366-375. [PMID: 27392635 PMCID: PMC4981430 DOI: 10.1016/j.neuropharm.2016.07.004] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2016] [Revised: 05/27/2016] [Accepted: 07/04/2016] [Indexed: 12/14/2022]
Abstract
Data from genetically modified mice suggest that benzodiazepine (BDZ)-site agonists with improved selectivity for α2-subtype GABAA receptors (α2GABAAR) are potentially useful for the treatment of neuropathic pain. Subtype-selective compounds available for preclinical tests in rodents support this concept but have not been approved for human use, hindering proof-of-concept studies in patients. We recently proposed that N-desmethyl clobazam (NDMC), the main metabolite of the licensed BDZ clobazam (CBZ), is responsible for most of the antihyperalgesia observed in mice after CBZ administration. In order to assess a potentially favorable pharmacological profile of NDMC, we analyzed differences in the GABAAR subtype specificity of CBZ, NDMC and diazepam (DZP) in recombinant receptors. DZP and CBZ potentiated sedating α1GABAARs and antihyperalgesic α2GABAARs with similar efficacies, whereas NDMC preferred α2GABAARs over α1GABAARs across a wide concentration range. In vivo, DZP and NDMC reduced neuropathic pain at doses between 3 and 30 mg/kg. At these doses, DZP had strong locomotor sedating effects while NDMC caused no or only weak sedation. Sedative effects of NDMC became apparent when the action of NDMC was restricted to α1GABAARs. However, when GABAAR point-mutated mice were studied that allow the analysis of antihyperalgesia and sedation in isolation, we found that, compared to DZP, NDMC had a significantly improved therapeutic window, consistent with its more favorable α2/α1 in vitro activity ratio. Given that NDMC should share the safety profile of its parent compound CBZ, it should be well-suited for proof-of-concept studies in human volunteers or patients.
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Affiliation(s)
- William T Ralvenius
- Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland
| | - Mario A Acuña
- Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland
| | - Dietmar Benke
- Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland
| | - Alain Matthey
- Division of Clinical Pharmacology and Toxicology, Multidisciplinary Pain Center, Department of Anesthesiology, Pharmacology and Intensive Care, Geneva University Hospitals, University of Geneva, 4 rue Gabrielle-Perret-Gentil, CH-1211 Geneva, Switzerland
| | - Youssef Daali
- Division of Clinical Pharmacology and Toxicology, Multidisciplinary Pain Center, Department of Anesthesiology, Pharmacology and Intensive Care, Geneva University Hospitals, University of Geneva, 4 rue Gabrielle-Perret-Gentil, CH-1211 Geneva, Switzerland
| | - Uwe Rudolph
- Laboratory of Genetic Neuropharmacology, McLean Hospital, 115 Mill Street, Belmont, MA 02478, USA; Department of Psychiatry, Harvard Medical School, 401 Park Drive, Boston, MA 02215, USA
| | - Jules Desmeules
- Division of Clinical Pharmacology and Toxicology, Multidisciplinary Pain Center, Department of Anesthesiology, Pharmacology and Intensive Care, Geneva University Hospitals, University of Geneva, 4 rue Gabrielle-Perret-Gentil, CH-1211 Geneva, Switzerland
| | - Hanns Ulrich Zeilhofer
- Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland; Institute of Pharmaceutical Sciences, Swiss Federal Institute of Technology (ETH) Zurich, Vladimir-Prelog-Weg 10, CH-8093 Zürich, Switzerland; Drug Discovery Network Zurich (DDNZ), CH-8057 Zurich, Switzerland.
| | - Marie Besson
- Division of Clinical Pharmacology and Toxicology, Multidisciplinary Pain Center, Department of Anesthesiology, Pharmacology and Intensive Care, Geneva University Hospitals, University of Geneva, 4 rue Gabrielle-Perret-Gentil, CH-1211 Geneva, Switzerland
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Stamenić TT, Poe MM, Rehman S, Santrač A, Divović B, Scholze P, Ernst M, Cook JM, Savić MM. Ester to amide substitution improves selectivity, efficacy and kinetic behavior of a benzodiazepine positive modulator of GABA A receptors containing the α5 subunit. Eur J Pharmacol 2016; 791:433-443. [PMID: 27639297 DOI: 10.1016/j.ejphar.2016.09.016] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2016] [Revised: 09/07/2016] [Accepted: 09/07/2016] [Indexed: 12/22/2022]
Abstract
We have synthesized and characterized MP-III-022 ((R)-8-ethynyl-6-(2-fluorophenyl)-N,4-dimethyl-4H-benzo[f]imidazo[1,5-a][1,4]diazepine-3-carboxamide) in vitro and in vivo as a binding- and efficacy-selective positive allosteric modulator of GABAA receptors containing the α5 subunit (α5GABAARs). By approximation of the electrophysiological responses which the estimated free rat brain concentrations can induce, we demonstrated that convenient systemic administration of MP-III-022 in the dose range 1-10mg/kg may result in a selective potentiation, over a wide range from mild to moderate to strong, of α5βγ2 GABAA receptors. For eliciting a comparable range of potentiation, the widely studied parent ligand SH-053-2'F-R-CH3 containing an ester moiety needs to be administered over a much wider dose range (10-200mg/kg), but at the price of activating non-α5 GABAARs as well as the desired α5GABAARs at the highest dose. At the dose of 10mg/kg, which elicits a strong positive modulation of α5GABAARs, MP-III-022 caused mild, but significant muscle relaxation, while at doses 1-10mg/kg was devoid of ataxia, sedation or an influence on the anxiety level, characteristic for non-selective benzodiazepines. As an amide compound with improved stability and kinetic properties, MP-III-022 may represent an optimized tool to study the influence of α5GABAARs on the neuronal pathways related to CNS disorders such as schizophrenia, Alzheimer's disease, Down syndrome or autism.
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Affiliation(s)
- Tamara Timić Stamenić
- Department of Pharmacology, Faculty of Pharmacy, University of Belgrade, Vojvode Stepe 450, 11221 Belgrade, Serbia
| | - Michael M Poe
- Department of Chemistry and Biochemistry, University of Wisconsin-Milwaukee, P.O. Box 413, Milwaukee, Wisconsin 53201, USA
| | - Sabah Rehman
- Department of Molecular Neurosciences, Center for Brain Research, Medical University of Vienna, Vienna, Austria
| | - Anja Santrač
- Department of Pharmacology, Faculty of Pharmacy, University of Belgrade, Vojvode Stepe 450, 11221 Belgrade, Serbia
| | - Branka Divović
- Department of Pharmacology, Faculty of Pharmacy, University of Belgrade, Vojvode Stepe 450, 11221 Belgrade, Serbia
| | - Petra Scholze
- Department of Pathobiology of the Nervous System, Center for Brain Research, Medical University of Vienna, Vienna, Austria
| | - Margot Ernst
- Department of Molecular Neurosciences, Center for Brain Research, Medical University of Vienna, Vienna, Austria
| | - James M Cook
- Department of Chemistry and Biochemistry, University of Wisconsin-Milwaukee, P.O. Box 413, Milwaukee, Wisconsin 53201, USA
| | - Miroslav M Savić
- Department of Pharmacology, Faculty of Pharmacy, University of Belgrade, Vojvode Stepe 450, 11221 Belgrade, Serbia.
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Humble SR. Neurosteroids are reduced in diabetic neuropathy and may be associated with the development of neuropathic pain. F1000Res 2016; 5:1923. [PMID: 28357038 PMCID: PMC5345788 DOI: 10.12688/f1000research.9034.1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 07/29/2016] [Indexed: 01/10/2023] Open
Abstract
Introduction: Peripheral and central sensitisation are implicated in the development of neuropathic pain. Hypersensitivity of pain pathway neurons has been described in animal models of diabetic neuropathy, which is postulated to be related to an imbalance between inhibitory and excitatory signals within the spinal cord. GABAergic neurons within the pain pathway are vital for the transmission of painful stimuli to higher centres. A developmental change in the rate of exponential decay of GABAergic synaptic events has been observed in other types of neurons and this may be associated with fluctuations in endogenous neurosteroid tone. Methods: The whole-cell patch-clamp technique was used on slices of neural tissue. Electrophysiological recordings were obtained from wild type mice between the ages of 6 and 80 days in the spinal cord, the nucleus reticularis of the thalamus and the cerebral cortex. Recordings were also obtained from mice with diabetic neuropathy (ob/ob and db/db) between the ages of 60 and 80 days. Behavioural experiments were performed to examine mechanical and thermal nociception. Results: Electrophysiological recordings from cortical pain pathway neurons from mature type-2 diabetic mice revealed that the endogenous neurosteroid tone is reduced compared to control. However, selected neurosteroid compounds had a more pronounced effect on the GABA
A receptors of these diabetic mice. ob/ob mice exhibit mechanical hyperalgesia and allodynia, which was reduced by neurosteroids applied exogenously. Conclusions: The reduced endogenous neurosteroid tone in ob/ob mice may be linked to their hypersensitivity. Neurosteroids may exert analgesic effects in pathological pain states by attempting to restore the physiological GABAergic inhibitory tone.
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Affiliation(s)
- Stephen R Humble
- Department of Anaesthetics and Pain Management, Charing Cross Hospital, Imperial College NHS Healthcare Trust London, London, W6 8RF, UK
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Doyon N, Vinay L, Prescott SA, De Koninck Y. Chloride Regulation: A Dynamic Equilibrium Crucial for Synaptic Inhibition. Neuron 2016; 89:1157-1172. [PMID: 26985723 DOI: 10.1016/j.neuron.2016.02.030] [Citation(s) in RCA: 156] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2015] [Revised: 12/24/2015] [Accepted: 02/18/2016] [Indexed: 01/02/2023]
Abstract
Fast synaptic inhibition relies on tight regulation of intracellular Cl(-). Chloride dysregulation is implicated in several neurological and psychiatric disorders. Beyond mere disinhibition, the consequences of Cl(-) dysregulation are multifaceted and best understood in terms of a dynamical system involving complex interactions between multiple processes operating on many spatiotemporal scales. This dynamical perspective helps explain many unintuitive manifestations of Cl(-) dysregulation. Here we discuss how taking into account dynamical regulation of intracellular Cl(-) is important for understanding how synaptic inhibition fails, how to best detect that failure, why Cl(-) regulation is energetically so expensive, and the overall consequences for therapeutics.
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Affiliation(s)
- Nicolas Doyon
- Institut Universitaire en Santé Mentale de Québec, Québec, QC G1J 2G3, Canada; Department of Mathematics and Statistics, Université Laval, Québec, QC G1V 0A6, Canada
| | - Laurent Vinay
- Team P3M, Institut de Neurosciences de la Timone, UMR 7289, CNRS and Aix Marseille Université, F-13385 Marseille, France
| | - Steven A Prescott
- Program in Neurosciences and Mental Health, Hospital for Sick Children, Toronto, ON M5G 1X8, Canada; Department of Physiology, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Yves De Koninck
- Institut Universitaire en Santé Mentale de Québec, Québec, QC G1J 2G3, Canada; Department of Psychiatry and Neuroscience, Université Laval, Québec, QC, G1V 0A6, Canada.
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The lidocaine metabolite N-ethylglycine has antinociceptive effects in experimental inflammatory and neuropathic pain. Pain 2016; 156:1647-1659. [PMID: 25932687 PMCID: PMC4617288 DOI: 10.1097/j.pain.0000000000000206] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Supplemental Digital Content is Available in the Text. The lidocaine metabolite N-ethylglycine specifically reduces GlyT1-dependent glycine uptake and has antinociceptive effects in experimental inflammatory and neuropathic pain, while no adverse effects are observed. Glycine transporter 1 (GlyT1) plays a crucial role in regulating extracellular glycine concentrations and might thereby constitute a new drug target for the modulation of glycinergic inhibition in pain signaling. Consistent with this view, inhibition of GlyT1 has been found to induce antinociceptive effects in various animal pain models. We have shown previously that the lidocaine metabolite N-ethylglycine (EG) reduces GlyT1-dependent glycine uptake by functioning as an artificial substrate for this transporter. Here, we show that EG is specific for GlyT1 and that in rodent models of inflammatory and neuropathic pain, systemic treatment with EG results in an efficient amelioration of hyperalgesia and allodynia without affecting acute pain. There was no effect on motor coordination or the development of inflammatory edema. No adverse neurological effects were observed after repeated high-dose application of EG. EG concentrations both in blood and spinal fluid correlated with an increase of glycine concentration in spinal fluid. The time courses of the EG and glycine concentrations corresponded well with the antinociceptive effect. Additionally, we found that EG reduced the increase in neuronal firing of wide-dynamic-range neurons caused by inflammatory pain induction. These findings suggest that systemically applied lidocaine exerts antihyperalgesic effects through its metabolite EG in vivo, by enhancing spinal inhibition of pain processing through GlyT1 modulation and subsequent increase of glycine concentrations at glycinergic inhibitory synapses. EG and other substrates of GlyT1, therefore, may be a useful therapeutic agent in chronic pain states involving spinal disinhibition.
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Smith KM, Boyle KA, Mustapa M, Jobling P, Callister RJ, Hughes DI, Graham BA. Distinct forms of synaptic inhibition and neuromodulation regulate calretinin-positive neuron excitability in the spinal cord dorsal horn. Neuroscience 2016; 326:10-21. [PMID: 27045594 PMCID: PMC4919388 DOI: 10.1016/j.neuroscience.2016.03.058] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2016] [Revised: 02/26/2016] [Accepted: 03/25/2016] [Indexed: 01/12/2023]
Abstract
CR+ spinal dorsal horn neurons form excitatory (Typical) and inhibitory (Atypical) subpopulations. Typical neurons received mixed (GABAergic and glycinergic) inhibition. Atypical neurons received inhibition dominated by glycine. Noradrenaline and serotonin evoke responses in Typical but not Atypical neurons. Enkephalins evoke responses in Atypical but not typical neurons.
The dorsal horn (DH) of the spinal cord contains a heterogenous population of neurons that process incoming sensory signals before information ascends to the brain. We have recently characterized calretinin-expressing (CR+) neurons in the DH and shown that they can be divided into excitatory and inhibitory subpopulations. The excitatory population receives high-frequency excitatory synaptic input and expresses delayed firing action potential discharge, whereas the inhibitory population receives weak excitatory drive and exhibits tonic or initial bursting discharge. Here, we characterize inhibitory synaptic input and neuromodulation in the two CR+ populations, in order to determine how each is regulated. We show that excitatory CR+ neurons receive mixed inhibition from GABAergic and glycinergic sources, whereas inhibitory CR+ neurons receive inhibition, which is dominated by glycine. Noradrenaline and serotonin produced robust outward currents in excitatory CR+ neurons, predicting an inhibitory action on these neurons, but neither neuromodulator produced a response in CR+ inhibitory neurons. In contrast, enkephalin (along with selective mu and delta opioid receptor agonists) produced outward currents in inhibitory CR+ neurons, consistent with an inhibitory action but did not affect the excitatory CR+ population. Our findings show that the pharmacology of inhibitory inputs and neuromodulator actions on CR+ cells, along with their excitatory inputs can define these two subpopulations further, and this could be exploited to modulate discrete aspects of sensory processing selectively in the DH.
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Affiliation(s)
- K M Smith
- School of Biomedical Sciences & Pharmacy, Faculty of Health, University of Newcastle, Callaghan, NSW, Australia
| | - K A Boyle
- Institute of Neuroscience Psychology, College of Medical, Veterinary & Life Sciences, University of Glasgow, Glasgow, UK
| | - M Mustapa
- Institute of Neuroscience Psychology, College of Medical, Veterinary & Life Sciences, University of Glasgow, Glasgow, UK
| | - P Jobling
- School of Biomedical Sciences & Pharmacy, Faculty of Health, University of Newcastle, Callaghan, NSW, Australia
| | - R J Callister
- School of Biomedical Sciences & Pharmacy, Faculty of Health, University of Newcastle, Callaghan, NSW, Australia
| | - D I Hughes
- Institute of Neuroscience Psychology, College of Medical, Veterinary & Life Sciences, University of Glasgow, Glasgow, UK
| | - B A Graham
- School of Biomedical Sciences & Pharmacy, Faculty of Health, University of Newcastle, Callaghan, NSW, Australia.
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Zuiker RGJA, Chen X, Østerberg O, Mirza NR, Muglia P, de Kam M, Klaassen ES, van Gerven JMA. NS11821, a partial subtype-selective GABAA agonist, elicits selective effects on the central nervous system in randomized controlled trial with healthy subjects. J Psychopharmacol 2016; 30:253-62. [PMID: 26655084 DOI: 10.1177/0269881115620435] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
NS11821 is a partial GABAA agonist with relatively dominant α2,3 and α5 subtype efficacy but negligible α1 agonism. This first-in-human study was performed in healthy male subjects using a single-dose, parallel, double blind, placebo-controlled, randomized, dose-escalation study design. In total six cohorts (N=48) were enrolled. The eight subjects of each cohort received NS11821 (10 mg, 30 mg, 75 mg, 150 mg, 300 mg or 600 mg) or placebo in a 6:2 ratio. At low dose levels, NS11821 had a relatively low exposure and a more-than-proportional increase of the area under the curve and maximum plasma concentrations, probably due to poor solubility. Saccadic peak velocity decreased in a dose-related manner while limited impairments were seen on body sway and the visual analogue scale for alertness. The most common adverse events were somnolence and dizziness, which were more prominent with the higher doses. Although no positive control was used in this study, the results were compared post hoc with a Centre for Human Drug Research dataset for lorazepam 2 mg. The maximum saccadic peak velocity effects seemed comparable to the typical effects of lorazepam, whereas the other central nervous system effects were smaller. These results support the pharmacological selectivity of NS11821 and show that pharmacodynamic effective doses of NS11821 were safe and well tolerated in healthy subjects.
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Affiliation(s)
| | - Xia Chen
- Centre for Human Drug Research (CHDR), Leiden, the Netherlands Clinical Pharmacological Research Centre (CPRC), Peking Union Medical College Hospital, Beijing, PR China
| | | | | | | | - Marieke de Kam
- Centre for Human Drug Research (CHDR), Leiden, the Netherlands
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Aman U, Subhan F, Shahid M, Akbar S, Ahmad N, Ali G, Fawad K, Sewell RDE. Passiflora incarnata attenuation of neuropathic allodynia and vulvodynia apropos GABA-ergic and opioidergic antinociceptive and behavioural mechanisms. Altern Ther Health Med 2016; 16:77. [PMID: 26912265 PMCID: PMC4765057 DOI: 10.1186/s12906-016-1048-6] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2015] [Accepted: 02/11/2016] [Indexed: 12/20/2022]
Abstract
Background Passiflora incarnata is widely used as an anxiolytic and sedative due to its putative GABAergic properties. Passiflora incarnata L. methanolic extract (PI-ME) was evaluated in an animal model of streptozotocin-induced diabetic neuropathic allodynia and vulvodynia in rats along with antinociceptive, anxiolytic and sedative activities in mice in order to examine possible underlying mechanisms. Methods PI-ME was tested preliminary for qualitative phytochemical analysis and then quantitatively by proximate and GC-MS analysis. The antinociceptive property was evaluated using the abdominal constriction assay and hot plate test. The anxiolytic activity was performed in a stair case model and sedative activity in an open field test. The antagonistic activities were evaluated using naloxone and/or pentylenetetrazole (PTZ). PI-ME was evaluated for prospective anti-allodynic and anti-vulvodynic properties in a rat model of streptozotocin induced neuropathic pain using the static and dynamic testing paradigms of mechanical allodynia and vulvodynia. Results GC-MS analysis revealed that PI-ME contained predominant quantities of oleamide (9-octadecenamide), palmitic acid (hexadecanoic acid) and 3-hydroxy-dodecanoic acid, among other active constituents. In the abdominal constriction assay and hot plate test, PI-ME produced dose dependant, naloxone and pentylenetetrazole reversible antinociception suggesting an involvement of opioidergic and GABAergic mechanisms. In the stair case test, PI-ME at 200 mg/kg increased the number of steps climbed while at 600 mg/kg a significant decrease was observed. The rearing incidence was diminished by PI-ME at all tested doses and in the open field test, PI-ME decreased locomotor activity to an extent that was analagous to diazepam. The effects of PI-ME were antagonized by PTZ in both the staircase and open field tests implicating GABAergic mechanisms in its anxiolytic and sedative activities. In the streptozotocin-induced neuropathic nociceptive model, PI-ME (200 and 300 mg/kg) exhibited static and dynamic anti-allodynic effects exemplified by an increase in paw withdrawal threshold and paw withdrawal latency. PI-ME relieved only the dynamic component of vulvodynia by increasing flinching response latency. Conclusions These findings suggest that Passiflora incarnata might be useful for treating neuropathic pain. The antinociceptive and behavioural findings inferring that its activity may stem from underlying opioidergic and GABAergic mechanisms though a potential oleamide-sourced cannabimimetic involvement is also discussed. Electronic supplementary material The online version of this article (doi:10.1186/s12906-016-1048-6) contains supplementary material, which is available to authorized users.
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135
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Benarroch EE. Dorsal horn circuitry: Complexity and implications for mechanisms of neuropathic pain. Neurology 2016; 86:1060-9. [PMID: 26888981 DOI: 10.1212/wnl.0000000000002478] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
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Barrett JE, Haas DA. Perspectives and Trends in Pharmacological Approaches to the Modulation of Pain. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2016; 75:1-33. [PMID: 26920007 DOI: 10.1016/bs.apha.2015.12.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Pharmacological approaches to our understanding and treatment of pain have had a long history and have traditionally relied on very few drugs that either have significant side effects and abuse liability, such as the nonsteroidal anti-inflammatory drugs or the opioids, respectively, or those that have been developed for other conditions such as the tricyclic antidepressants. The pathophysiology of pain is undoubtedly complex, complicated in part by the fact that it is not a singular condition, and has a variety of etiologies and a number of associated comorbidities that make treatment interventions challenging. Moreover, there are changes in the central nervous system during the course of the development of chronic pain that, in a manner parallel to neurodegenerative disorders, likely require different pharmacological approaches in the early stages of acute pain compared to those that would be effective when pain has become chronic. This chapter reviews the current status of the field of pain research focusing on some relatively underdeveloped areas, such as pain and its associated comorbidities, and the use of transgenic animals and drug self-administration procedures in the context of analgesic assessment. This chapter also incorporates more recent developments and emerging trends in the area of epigenetics, biomarkers, and the use of induced pluripotent stem cells for pharmacological evaluation, target identification, and validation. Recent progress in the study of "organs-on-a-chip" will also be included in this overview, setting expectations for future progress that integrates these advances for deeper insights into mechanisms, novel treatments, and facilitated efforts in drug discovery.
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Affiliation(s)
- James E Barrett
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, Pennsylvania, USA.
| | - Derick A Haas
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, Pennsylvania, USA
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Abstract
Among many mechanisms implicated in the development of neuropathic pain after nerve damage is a profound dysfunction of GABAergic inhibitory controls, manifested by ongoing pain, mechanical hypersensitivity, and thermal hyperalgesia. In some respects, neuropathic pain can be considered a "disease" of the nervous system, with features in common with trauma-induced seizures. Indeed, first-line management involves anticonvulsant therapy. An alternative to pharmacotherapy for neuropathic pain is an approach that reestablishes the inhibitory tone that is lost after nerve damage. To this end, we have transplanted embryonic cortical GABAergic precursor neurons into the spinal cord of nerve-injured mice. Using a combination of light and electron microscopic analyses, and also in vitro electrophysiological recordings from spinal cord slice preparations, we demonstrated remarkable integration of the transplants into the host, adult spinal cord. Most importantly, transplants produced a complete reversal of the hypersensitivity in a sciatic nerve injury model and in a paclitaxel-generated chemotherapy model of neuropathic pain. In related studies, we demonstrated that medial ganglionic eminence cell transplants are also effective in a chronic neuropathic itch model in which there is a significant loss of dorsal horn inhibitory interneurons. Most importantly, in contrast to systemic or intrathecal pharmacological therapies, adverse side effects are minimized when the inhibitory control, namely, γ-aminobutyric acid release, occurs in a spinal cord circuit. These studies suggest that therapy targeted at repairing the GABAergic dysfunction is a viable and novel alternative to the management of neuropathic pain and itch, particularly those that are or become refractory to traditional pharmacotherapy.
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Affiliation(s)
- Allan I Basbaum
- Department of Anatomy, University of California San Francisco, San Francisco, CA, USA
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Amirmohseni S, Segelcke D, Reichl S, Wachsmuth L, Görlich D, Faber C, Pogatzki-Zahn E. Characterization of incisional and inflammatory pain in rats using functional tools of MRI. Neuroimage 2016; 127:110-122. [DOI: 10.1016/j.neuroimage.2015.11.052] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Revised: 11/04/2015] [Accepted: 11/23/2015] [Indexed: 02/07/2023] Open
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Doyon N, Prescott SA, De Koninck Y. Mild KCC2 Hypofunction Causes Inconspicuous Chloride Dysregulation that Degrades Neural Coding. Front Cell Neurosci 2016; 9:516. [PMID: 26858607 PMCID: PMC4731508 DOI: 10.3389/fncel.2015.00516] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2015] [Accepted: 12/23/2015] [Indexed: 11/17/2022] Open
Abstract
Disinhibition caused by Cl− dysregulation is implicated in several neurological disorders. This form of disinhibition, which stems primarily from impaired Cl− extrusion through the co-transporter KCC2, is typically identified by a depolarizing shift in GABA reversal potential (EGABA). Here we show, using computer simulations, that intracellular [Cl−] exhibits exaggerated fluctuations during transient Cl− loads and recovers more slowly to baseline when KCC2 level is even modestly reduced. Using information theory and signal detection theory, we show that increased Cl− lability and settling time degrade neural coding. Importantly, these deleterious effects manifest after less KCC2 reduction than needed to produce the gross changes in EGABA required for detection by most experiments, which assess KCC2 function under weak Cl− load conditions. By demonstrating the existence and functional consequences of “occult” Cl− dysregulation, these results suggest that modest KCC2 hypofunction plays a greater role in neurological disorders than previously believed.
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Affiliation(s)
- Nicolas Doyon
- Institut Universitaire en Santé Mentale de QuébecQuébec, QC, Canada; Department of Mathematics and Statistics, Université LavalQuébec, QC, Canada
| | - Steven A Prescott
- Program in Neurosciences and Mental Health, Hospital for Sick ChildrenToronto, ON, Canada; Department of Physiology, University of TorontoToronto, ON, Canada
| | - Yves De Koninck
- Institut Universitaire en Santé Mentale de QuébecQuébec, QC, Canada; Department of Psychiatry and Neuroscience, Université LavalQuébec, QC, Canada
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140
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Yan L, Pan M, Fu M, Wang J, Huang W, Qian H. Design, synthesis and biological evaluation of novel analgesic agents targeting both cyclooxygenase and TRPV1. Bioorg Med Chem 2016; 24:849-57. [PMID: 26795113 DOI: 10.1016/j.bmc.2016.01.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2015] [Revised: 01/06/2016] [Accepted: 01/06/2016] [Indexed: 01/08/2023]
Abstract
Multitarget-directed ligands might offer certain advantages over traditional single-target drugs and/or drug combinations. In the present study, a series of novel analgesic agents targeting both cyclooxygenase and TRPV1 were prepared and evaluated in an effort to optimize properties of previously described lead compounds from piperazine, ethanediamine cores. These compounds were evaluated for antagonism of hTRPV1 activation by capsaicin and the ability to inhibit Ovine COX-1 and human recombinant COX-2 in vitro. The favorable potentials of these test compounds were further characterized in preliminary analgesic and side-effects tests in vivo. On the basis of comprehensive evaluations, compound 8d which showed strong TRPV1 antagonistic activity, middle COX-2 inhibition, weak ulcerogenic action and had no hyperthermia side-effect was considered as a safe candidate for the further development of analgesic drugs.
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Affiliation(s)
- Lin Yan
- Institute of Chemistry & Biology, Henan University, Kaifeng 475004, China
| | - Miaobo Pan
- State Key Laboratory of Natural Medicines, Center of Drug Discovery, China Pharmaceutical University, 24 Tongjiaxiang, Nanjing 210009, China
| | - Mian Fu
- State Key Laboratory of Natural Medicines, Center of Drug Discovery, China Pharmaceutical University, 24 Tongjiaxiang, Nanjing 210009, China
| | - Jingjie Wang
- State Key Laboratory of Natural Medicines, Center of Drug Discovery, China Pharmaceutical University, 24 Tongjiaxiang, Nanjing 210009, China; WuXiAppTec (Wuhan) Co., Ltd, Wuhan 430000, China
| | - Wenlong Huang
- State Key Laboratory of Natural Medicines, Center of Drug Discovery, China Pharmaceutical University, 24 Tongjiaxiang, Nanjing 210009, China.
| | - Hai Qian
- State Key Laboratory of Natural Medicines, Center of Drug Discovery, China Pharmaceutical University, 24 Tongjiaxiang, Nanjing 210009, China.
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Fischer BD, Platt DM, Rallapalli SK, Namjoshi OA, Cook JM, Rowlett JK. Antagonism of triazolam self-administration in rhesus monkeys responding under a progressive-ratio schedule: In vivo apparent pA2 analysis. Drug Alcohol Depend 2016; 158:22-9. [PMID: 26596587 PMCID: PMC4698084 DOI: 10.1016/j.drugalcdep.2015.10.026] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/26/2015] [Revised: 10/19/2015] [Accepted: 10/19/2015] [Indexed: 02/02/2023]
Abstract
BACKGROUND Conventional benzodiazepines bind non-selectively to GABAA receptors containing α1, α2, α3, and α5 subunits (α1GABAA, α2GABAA, α3GABAA, and α5GABAA receptors, respectively), and the role of these different GABAA receptor subtypes in the reinforcing effects of benzodiazepines has not been characterized fully. We used a pharmacological antagonist approach with available subtype-selective ligands to evaluate the role of GABAA receptor subtypes in the reinforcing effects of the non-selective conventional benzodiazepine, triazolam. METHODS Rhesus monkeys (n=4) were trained under a progressive-ratio schedule of intravenous midazolam delivery and dose-response functions were determined for triazolam, in the absence and presence of flumazenil (non-selective antagonist), βCCT and 3-PBC (α1GABAA-preferring antagonists), and XLi-093 (α5GABAA-selective antagonist). RESULTS Flumazenil, βCCT and 3-PBC shifted the dose-response functions for triazolam to the right in a surmountable fashion, whereas XLi-093 was ineffective. Schild analyses revealed rank orders of potencies of flumazenil=βCCT>3-PBC. Comparison of potencies between self-administration and previous binding studies with human cloned GABAA receptor subtypes suggested that the potencies for βCCT and 3-PBC were most consistent with binding at α2GABAA and α3GABAA receptors, but not α1GABAA or α5GABAA receptor subtypes. CONCLUSIONS Our findings were not entirely consistent with blockade of α1GABAA receptors and are consistent with the possibility of α2GABAA and/or α3GABAA subtype involvement in antagonism of the reinforcing effects of triazolam. The α5GABAA receptor subtype likely does not play a substantial role in self-administration under these conditions.
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Affiliation(s)
- Bradford D. Fischer
- Harvard Medical School, New England Primate Research Center, One Pine Hill Drive, PO Box 9102, Southborough, MA 01772-9102, USA
| | - Donna M. Platt
- Harvard Medical School, New England Primate Research Center, One Pine Hill Drive, PO Box 9102, Southborough, MA 01772-9102, USA
| | - Sundari K. Rallapalli
- University of Wisconsin–Milwaukee, Department of Chemistry and Biochemistry, Milwaukee, WI 53201, USA
| | - Ojas A. Namjoshi
- University of Wisconsin–Milwaukee, Department of Chemistry and Biochemistry, Milwaukee, WI 53201, USA
| | - James M. Cook
- University of Wisconsin–Milwaukee, Department of Chemistry and Biochemistry, Milwaukee, WI 53201, USA
| | - James K. Rowlett
- Harvard Medical School, New England Primate Research Center, One Pine Hill Drive, PO Box 9102, Southborough, MA 01772-9102, USA,Corresponding author. Current address: Department of Psychiatry and Human Behavior, University of Mississippi Medical Center, Jackson, MS 39216, USA. Tel.: +1 601 984 4488. (J.K. Rowlett)
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Chen ZY, Shen FY, Jiang L, Zhao X, Shen XL, Zhong W, Liu S, Wang ZR, Wang YW. Attenuation of Neuropathic Pain by Inhibiting Electrical Synapses in the Anterior Cingulate Cortex. Anesthesiology 2016; 124:169-83. [PMID: 26566282 DOI: 10.1097/aln.0000000000000942] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
BACKGROUND Synaptic mechanisms and neuronal oscillations have been proposed to be responsible for neuropathic pain formation. Many studies have also highlighted the important role of electrical synapses in synaptic plasticity and in neuronal oscillations. Thus, electrical synapses may contribute to neuropathic pain generation. However, previous studies have primarily focused on the role of chemical synapses, while ignoring the role of electrical synapses, in neuropathic pain generation. METHODS The authors adopted microinjection, RNA interference techniques, and behavioral tests to verify the link between connexin 36 (Cx36) and neuropathic pain. They also studied the selective Cx36 blocker mefloquine in rat chronic constriction injury and spared nerve injury model of neuropathic pain. Electrophysiologic recordings were used to further confirm the behavioral data. RESULTS The authors found that Cx36, which constitutes the neuron-neuron electrical synapses, was up-regulated in the anterior cingulate cortex after nerve injury (n = 5). Meanwhile, Cx36-mediated neuronal oscillations in the gamma frequency range (30 to 80 Hz) (n = 7 to 8) and the neuronal synaptic transmission (n = 13 to 19) were also enhanced. Neuropathic pain was relieved by disrupting Cx36 function or expression in the anterior cingulate cortex. They also found that mefloquine, which are clinically used for treating malaria, affected gamma oscillations and synaptic plasticity, leading to a sustained pain relief in chronic constriction injury and spared nerve injury models (n = 7 to 12). CONCLUSION The electrical synapses blocker mefloquine could affect gamma oscillations and synaptic plasticity in the anterior cingulate cortex and relieve neuropathic pain. Cx36 may be a new therapeutic target for treating chronic pain.
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Affiliation(s)
- Zhi-Yu Chen
- From the Department of Anesthesiology and Intensive Care Medicine, Xinhua Hospital, College of Medicine, Shanghai Jiaotong University, Shanghai, China (Z.-Y.C., F.-Y.S., L.J., X.Z., X.-L.S., Y.-W.W.); and Laboratory of Neural Circuit Plasticity & Memory, Institute of Brain Functional Genomics, East China Normal University, Shanghai, China (W.Z., S.L., Z.-R.W.)
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Testing for Ancient Selection Using Cross-population Allele Frequency Differentiation. Genetics 2015; 202:733-50. [PMID: 26596347 DOI: 10.1534/genetics.115.178095] [Citation(s) in RCA: 73] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2015] [Accepted: 11/18/2015] [Indexed: 12/18/2022] Open
Abstract
A powerful way to detect selection in a population is by modeling local allele frequency changes in a particular region of the genome under scenarios of selection and neutrality and finding which model is most compatible with the data. A previous method based on a cross-population composite likelihood ratio (XP-CLR) uses an outgroup population to detect departures from neutrality that could be compatible with hard or soft sweeps, at linked sites near a beneficial allele. However, this method is most sensitive to recent selection and may miss selective events that happened a long time ago. To overcome this, we developed an extension of XP-CLR that jointly models the behavior of a selected allele in a three-population tree. Our method - called "3-population composite likelihood ratio" (3P-CLR) - outperforms XP-CLR when testing for selection that occurred before two populations split from each other and can distinguish between those events and events that occurred specifically in each of the populations after the split. We applied our new test to population genomic data from the 1000 Genomes Project, to search for selective sweeps that occurred before the split of Yoruba and Eurasians, but after their split from Neanderthals, and that could have led to the spread of modern-human-specific phenotypes. We also searched for sweep events that occurred in East Asians, Europeans, and the ancestors of both populations, after their split from Yoruba. In both cases, we are able to confirm a number of regions identified by previous methods and find several new candidates for selection in recent and ancient times. For some of these, we also find suggestive functional mutations that may have driven the selective events.
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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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Chen X, Jacobs G, de Kam M, Jaeger J, Lappalainen J, Maruff P, Smith MA, Cross AJ, Cohen A, van Gerven J. The central nervous system effects of the partial GABA-Aα2,3 -selective receptor modulator AZD7325 in comparison with lorazepam in healthy males. Br J Clin Pharmacol 2015; 78:1298-314. [PMID: 24802722 DOI: 10.1111/bcp.12413] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2013] [Accepted: 04/25/2014] [Indexed: 11/29/2022] Open
Abstract
AIMS AZD7325 is a novel α2,3 -subtype-selective partial GABA-A-receptor modulator. This study investigated the pharmacodynamics of single oral doses of AZD7325 2 mg and 10 mg on the central nervous system (CNS) compared with placebo and lorazepam 2 mg. METHODS This double-blind, randomized, four way crossover study enrolled 16 healthy males and administered two validated CNS test batteries to measure drug effects on cognitive, neurophysiologic and psychomotor function and subjective feelings. The pharmacological selectivity of AZD7325 was compared with lorazepam by plotting saccadic peak velocity change from baseline (ΔSPV) against body sway (ΔSway) and visual analogue scale for alertness(ΔVASalertness ). This analysis has previously been used to identify α2,3 -subtype-selectivity. RESULTS In contrast with the robust impairment caused by lorazepam (all P < 0.05 vs. placebo), neither dose of AZD7325 induced statistically significant effects on any pharmacodynamic measurements. Lorazepam-induced SPV-reduction was linearly related to changes in other neurophysiologic biomarkers. In contrast, the slopes of the regression lines were flatter for AZD7325, particularly for the Δlog(Sway) -ΔSPV relation (estimate slope, AZD7325 10 mg vs. lorazepam, difference [95% confidence interval], P value -0.00036 vs. -0.00206, 0.001704 [0.000639, 0.002768], P = 0.0018) and the ΔVASalertness -ΔSPV relationship (0.01855 vs. 0.08216, -0.06360 [-0.1046, -0.02257], P = 0.0024). AZD7325 10 mg and lorazepam induced different response patterns on VAS 'feeling high' and electro-encephalography. CONCLUSION The characteristic ΔSPV-relative effect profiles of AZD7325 vs. lorazepam suggest anxio-selectivity related to α2,3 -selective GABAA agonism. However, exploration of higher doses may be warranted. The paucity of effects on most CNS-PD parameters also indicates a mitigated side effect pattern, with potentially lower cognitive and neurophysiological side effect burden than non-selective benzodiazepines.
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Affiliation(s)
- Xia Chen
- Phase I Unit, Clinical Pharmacology Research Center (CPRC), Peking Union Medical College Hospital, Beijing, China; Centre for Human Drug Research, Leiden, The Netherlands
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146
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Korpi ER, den Hollander B, Farooq U, Vashchinkina E, Rajkumar R, Nutt DJ, Hyytiä P, Dawe GS. Mechanisms of Action and Persistent Neuroplasticity by Drugs of Abuse. Pharmacol Rev 2015; 67:872-1004. [DOI: 10.1124/pr.115.010967] [Citation(s) in RCA: 101] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
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147
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Javdani F, Holló K, Hegedűs K, Kis G, Hegyi Z, Dócs K, Kasugai Y, Fukazawa Y, Shigemoto R, Antal M. Differential expression patterns of K(+) /Cl(-) cotransporter 2 in neurons within the superficial spinal dorsal horn of rats. J Comp Neurol 2015; 523:1967-83. [PMID: 25764511 DOI: 10.1002/cne.23774] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Revised: 03/03/2015] [Accepted: 03/03/2015] [Indexed: 01/21/2023]
Abstract
γ-Aminobutyric acid (GABA)- and glycine-mediated hyperpolarizing inhibition is associated with a chloride influx that depends on the inwardly directed chloride electrochemical gradient. In neurons, the extrusion of chloride from the cytosol primarily depends on the expression of an isoform of potassium-chloride cotransporters (KCC2s). KCC2 is crucial in the regulation of the inhibitory tone of neural circuits, including pain processing neural assemblies. Thus we investigated the cellular distribution of KCC2 in neurons underlying pain processing in the superficial spinal dorsal horn of rats by using high-resolution immunocytochemical methods. We demonstrated that perikarya and dendrites widely expressed KCC2, but axon terminals proved to be negative for KCC2. In single ultrathin sections, silver deposits labeling KCC2 molecules showed different densities on the surface of dendritic profiles, some of which were negative for KCC2. In freeze fracture replicas and tissue sections double stained for the β3-subunit of GABAA receptors and KCC2, GABAA receptors were revealed on dendritic segments with high and also with low KCC2 densities. By measuring the distances between spots immunoreactive for gephyrin (a scaffolding protein of GABAA and glycine receptors) and KCC2 on the surface of neurokinin 1 (NK1) receptor-immunoreactive dendrites, we found that gephyrin-immunoreactive spots were located at various distances from KCC2 cotransporters; 5.7 % of them were recovered in the middle of 4-10-µm-long dendritic segments that were free of KCC2 immunostaining. The variable local densities of KCC2 may result in variable postsynaptic potentials evoked by the activation of GABAA and glycine receptors along the dendrites of spinal neurons.
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Affiliation(s)
- Fariba Javdani
- Department of Anatomy, Histology and Embryology, Faculty of Medicine, University of Debrecen, Debrecen 4012, Hungary
| | - Krisztina Holló
- Department of Anatomy, Histology and Embryology, Faculty of Medicine, University of Debrecen, Debrecen 4012, Hungary
| | - Krisztina Hegedűs
- Department of Anatomy, Histology and Embryology, Faculty of Medicine, University of Debrecen, Debrecen 4012, Hungary
| | - Gréta Kis
- Department of Anatomy, Histology and Embryology, Faculty of Medicine, University of Debrecen, Debrecen 4012, Hungary
| | - Zoltán Hegyi
- Department of Anatomy, Histology and Embryology, Faculty of Medicine, University of Debrecen, Debrecen 4012, Hungary
| | - Klaudia Dócs
- Department of Anatomy, Histology and Embryology, Faculty of Medicine, University of Debrecen, Debrecen 4012, Hungary
| | - Yu Kasugai
- Department of Pharmacology, Innsbruck Medical University, Innsbruck 6020, Austria
| | - Yugo Fukazawa
- Division of Cell Biology and Neuroscience, Faculty of Medical Sciences, University of Fukui, Yoshida, 910-1193, Japan
| | - Ryuichi Shigemoto
- Institute of Science and Technology Austria, Klosterneuburg, 3400, Austria
| | - Miklós Antal
- Department of Anatomy, Histology and Embryology, Faculty of Medicine, University of Debrecen, Debrecen 4012, Hungary
- MTA-DE Neuroscience Research Group, Debrecen, 4012, Hungary
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148
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Obradović ALJ, Scarpa J, Osuru HP, Weaver JL, Park JY, Pathirathna S, Peterkin A, Lim Y, Jagodic MM, Todorovic SM, Jevtovic-Todorovic V. Silencing the α2 subunit of γ-aminobutyric acid type A receptors in rat dorsal root ganglia reveals its major role in antinociception posttraumatic nerve injury. Anesthesiology 2015; 123:654-67. [PMID: 26164299 PMCID: PMC4568754 DOI: 10.1097/aln.0000000000000767] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
BACKGROUND Neuropathic pain (NPP) is likely the result of repetitive high-frequency bursts of peripheral afferent activity leading to long-lasting changes in synaptic plasticity in the spinal dorsal horn. Drugs that promote γ-aminobutyric acid (GABA) activity in the dorsal horn provide partial relief of neuropathic symptoms. The authors examined how in vivo silencing of the GABA receptor type A (GABAA) α2 gene in dorsal root ganglia (DRG) controls NPP. METHODS After crush injury to the right sciatic nerve of female rats, the α2 GABAA antisense and mismatch oligodeoxynucleotides or NO-711 (a GABA uptake inhibitor) were applied to the L5 DRG. In vivo behavioral assessment of nociception was conducted before the injury and ensuing 10 days (n = 4 to 10). In vitro quantification of α2 GABAA protein and electrophysiological studies of GABAA currents were performed on acutely dissociated L5 DRG neurons at relevant time points (n = 6 to 14). RESULTS NPP postcrush injury of a sciatic nerve in adult female rats coincides with significant down-regulation of the α2 subunit expression in the ipsilateral DRG (approximately 30%). Selective down-regulation of α2 expression in DRGs significantly worsens mechanical (2.55 ± 0.75 to 5.16 ± 1.16) and thermal (7.97 ± 0.96 to 5.51 ± 0.75) hypersensitivity in crush-injured animals and causes development of significant mechanical (2.33 ± 0.40 to 5.00 ± 0.33) and thermal (10.80 ± 0.29 to 7.34 ± 0.81) hypersensitivity in sham animals (data shown as mean ± SD). Conversely, up-regulation of endogenous GABA via blockade of its uptake in DRG alleviates NPP. CONCLUSION The GABAA receptor in the DRG plays an important role in pathophysiology of NPP caused by sciatic nerve injury and represents promising target for novel pain therapies.
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Affiliation(s)
- Aleksandar LJ Obradović
- Department of Anesthesiology, University of Virginia Health System, Charlottesville, VA, USA
- Department of Physiology, University of Belgrade School of Pharmacy, Belgrade, Serbia
| | - Joseph Scarpa
- Department of Anesthesiology, University of Virginia Health System, Charlottesville, VA, USA
- Icahn Institute for Genomics and Multiscale Biology, Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Hari P Osuru
- Department of Anesthesiology, University of Virginia Health System, Charlottesville, VA, USA
| | - Janelle L Weaver
- Department of Anesthesiology, University of Virginia Health System, Charlottesville, VA, USA
| | - Ji-Yong Park
- Department of Anesthesiology, University of Virginia Health System, Charlottesville, VA, USA
- Department of Anesthesiology and Pain Medicine, College of Medicine, Korea University, Seoul, Republic of Korea
| | - Sriyani Pathirathna
- Department of Anesthesiology, University of Virginia Health System, Charlottesville, VA, USA
| | - Alexander Peterkin
- Department of Anesthesiology, University of Virginia Health System, Charlottesville, VA, USA
| | - Yunhee Lim
- Department of Anesthesiology, University of Virginia Health System, Charlottesville, VA, USA
- Department of Anesthesiology and Pain Medicine, Sanggye Paik Hospital, College of Medicine, Inje University, Seoul, Republic of Korea
| | - Miljenko M Jagodic
- Department of Anesthesiology, University of Virginia Health System, Charlottesville, VA, USA
| | - Slobodan M Todorovic
- Department of Anesthesiology, University of Virginia Health System, Charlottesville, VA, USA
- Department of Neuroscience, University of Virginia Health System, Charlottesville, VA, USA
| | - Vesna Jevtovic-Todorovic
- Department of Anesthesiology, University of Virginia Health System, Charlottesville, VA, USA
- Department of Neuroscience, University of Virginia Health System, Charlottesville, VA, USA
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149
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Niederberger E, Kuner R, Geißlinger G. [Pharmacological aspects of pain research in Germany]. Schmerz 2015; 29:531-8. [PMID: 26294077 DOI: 10.1007/s00482-015-0042-0] [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] [Indexed: 11/25/2022]
Abstract
In spite of several approved analgesics, the therapy of pain still constitutes a challenge due to the fact that the drugs do not exert sufficient efficacy or are associated with severe side effects. Therefore, the development of new and improved painkillers is still of great importance. A number of highly qualified scientists in Germany are investigating signal transduction pathways in pain, effectivity of new drugs and the so far incompletely investigated mechanisms of well-known analgesics in preclinical and clinical studies. The highlights of pharmacological pain research in Germany are summarized in this article.
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Affiliation(s)
- E Niederberger
- pharmazentrum frankfurt/ZAFES, Institut für Klinische Pharmakologie, Klinikum der Goethe-Universität Frankfurt, Theodor-Stern-Kai 7, 60590, Frankfurt am Main, Deutschland
| | - R Kuner
- Pharmakologisches Institut, Universität Heidelberg, Im Neuenheimer Feld 584, 69120, Heidelberg, Deutschland
| | - G Geißlinger
- pharmazentrum frankfurt/ZAFES, Institut für Klinische Pharmakologie, Klinikum der Goethe-Universität Frankfurt, Theodor-Stern-Kai 7, 60590, Frankfurt am Main, Deutschland.
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150
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[Neuropathic pain. How to open the blackbox]. Schmerz 2015; 29:479-80, 482-5. [PMID: 26264897 DOI: 10.1007/s00482-015-0028-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
This article, without presuming to be comprehensive, gives a brief outline of the development of research on neuropathic pain in Germany. Current clinical research on this subject focusses on the validation of human models, patient phenotyping, mechanism-based classification and treatment as well as on molecular pathomechanisms. This clinical research is based to a large extent on the work of several internationally recognized basic researchers in the 1990s. In particular, findings from system physiology led to the analysis of clinical phenotypes and the underlying pathophysiology. In parallel, basic research achieved international top levels through the development of innovative methods. Close cooperation, building of consortia and European networking made major contributions to the success of this research.
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