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Qian X, Zhao X, Yu L, Yin Y, Zhang XD, Wang L, Li JX, Zhu Q, Luo JL. Current status of GABA receptor subtypes in analgesia. Biomed Pharmacother 2023; 168:115800. [PMID: 37935070 DOI: 10.1016/j.biopha.2023.115800] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Revised: 10/15/2023] [Accepted: 10/26/2023] [Indexed: 11/09/2023] Open
Abstract
Gamma-aminobutyric acid (GABA), a non-protein-producing amino acid synthesized from the excitatory amino acid glutamate via the enzyme glutamic acid decarboxylase, is extensively found in microorganisms, plants and vertebrates, and is abundantly expressed in the spinal cord and brain. It is the major inhibitory neurotransmitter in the mammalian nervous system. GABA plays crucial roles in the regulation of synaptic transmission, the promotion of neuronal development and relaxation, and the prevention of insomnia and depression. As the major inhibitory neurotransmitter, GABA plays pivotal roles in the regulation of pain sensation, which is initiated by the activation of peripheral nociceptors and transmitted to the spinal cord and brain along nerves. GABA exerts these roles by directly acting on three types of receptors: ionotropic GABAA and GABAC receptors and G protein-coupled GABAB receptor. The chloride-permeable ion channel receptors GABAA and GABAC mediate fast neurotransmission, while the metabotropic GABAB receptor mediates slow effect. Different GABA receptors regulate pain sensation via different signaling pathways. Here we highlight recent updates on the involvement of specific GABA receptors and their subtypes in the process of pain sensation. Further understanding of different GABA receptors and signaling pathways in pain sensation will benefit the development of novel analgesics for pain management by targeting specific GABA receptor subtypes and signaling pathways.
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Affiliation(s)
- Xunjia Qian
- School of Pharmacy, Nantong University, Nantong 226001, Jiangsu, China
| | - Xinyi Zhao
- School of Pharmacy, Nantong University, Nantong 226001, Jiangsu, China
| | - Lulu Yu
- School of Pharmacy, Nantong University, Nantong 226001, Jiangsu, China
| | - Yujian Yin
- School of Pharmacy, Nantong University, Nantong 226001, Jiangsu, China
| | - Xiao-Dan Zhang
- School of Pharmacy, Nantong University, Nantong 226001, Jiangsu, China
| | - Liyun Wang
- School of Pharmacy, Nantong University, Nantong 226001, Jiangsu, China
| | - Jun-Xu Li
- School of Pharmacy, Nantong University, Nantong 226001, Jiangsu, China; Provincial Key Laboratory of Inflammation and Molecular Drug Target, Nantong 226001, Jiangsu, China
| | - Qing Zhu
- School of Pharmacy, Nantong University, Nantong 226001, Jiangsu, China; Provincial Key Laboratory of Inflammation and Molecular Drug Target, Nantong 226001, Jiangsu, China.
| | - Jia-Lie Luo
- School of Pharmacy, Nantong University, Nantong 226001, Jiangsu, China.
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Olde Heuvel F, Ouali Alami N, Aousji O, Pogatzki-Zahn E, Zahn PK, Wilhelm H, Deshpande D, Khatamsaz E, Catanese A, Woelfle S, Schön M, Jain S, Grabrucker S, Ludolph AC, Verpelli C, Michaelis J, Boeckers TM, Roselli F. Shank2 identifies a subset of glycinergic neurons involved in altered nociception in an autism model. Mol Autism 2023; 14:21. [PMID: 37316943 DOI: 10.1186/s13229-023-00552-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2022] [Accepted: 05/26/2023] [Indexed: 06/16/2023] Open
Abstract
BACKGROUND Autism Spectrum Disorders (ASD) patients experience disturbed nociception in the form of either hyposensitivity to pain or allodynia. A substantial amount of processing of somatosensory and nociceptive stimulus takes place in the dorsal spinal cord. However, many of these circuits are not very well understood in the context of nociceptive processing in ASD. METHODS We have used a Shank2-/- mouse model, which displays a set of phenotypes reminiscent of ASD, and performed behavioural and microscopic analysis to investigate the role of dorsal horn circuitry in nociceptive processing of ASD. RESULTS We determined that Shank2-/- mice display increased sensitivity to formalin pain and thermal preference, but a sensory specific mechanical allodynia. We demonstrate that high levels of Shank2 expression identifies a subpopulation of neurons in murine and human dorsal spinal cord, composed mainly by glycinergic interneurons and that loss of Shank2 causes the decrease in NMDAR in excitatory synapses on these inhibitory interneurons. In fact, in the subacute phase of the formalin test, glycinergic interneurons are strongly activated in wild type (WT) mice but not in Shank2-/- mice. Consequently, nociception projection neurons in laminae I are activated in larger numbers in Shank2-/- mice. LIMITATIONS Our investigation is limited to male mice, in agreement with the higher representation of ASD in males; therefore, caution should be applied to extrapolate the findings to females. Furthermore, ASD is characterized by extensive genetic diversity and therefore the findings related to Shank2 mutant mice may not necessarily apply to patients with different gene mutations. Since nociceptive phenotypes in ASD range between hyper- and hypo-sensitivity, diverse mutations may affect the circuit in opposite ways. CONCLUSION Our findings prove that Shank2 expression identifies a new subset of inhibitory interneurons involved in reducing the transmission of nociceptive stimuli and whose unchecked activation is associated with pain hypersensitivity. We provide evidence that dysfunction in spinal cord pain processing may contribute to the nociceptive phenotypes in ASD.
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Affiliation(s)
| | - Najwa Ouali Alami
- Department of Neurology, Ulm University, Ulm, Germany
- International PhD Program, Ulm University, Ulm, Germany
| | | | - Esther Pogatzki-Zahn
- Department of Anesthesiology, Intensive Care and Pain Medicine, University Hospital Münster, Münster, Germany
| | - Peter K Zahn
- Department of Anesthesiology, Intensive Care and Pain Medicine, University Hospital Münster, Münster, Germany
- Clinic for Anesthesiology, Intensive Care and Pain Medicine, University Hospital Bergmannsheil Bochum, Bochum, Germany
| | - Hanna Wilhelm
- Department of Neurology, Ulm University, Ulm, Germany
| | | | | | - Alberto Catanese
- Institute of Anatomy and Cell Biology, Ulm University, Ulm, Germany
| | - Sarah Woelfle
- Institute of Anatomy and Cell Biology, Ulm University, Ulm, Germany
| | - Michael Schön
- Institute of Anatomy and Cell Biology, Ulm University, Ulm, Germany
| | - Sanjay Jain
- Department of Internal Medicine (Renal), Pathology and Immunology, Washington University School of Medicine, St. Louis, USA
| | | | - Albert C Ludolph
- Department of Neurology, Ulm University, Ulm, Germany
- German Center for Neurodegenerative Diseases (DZNE), Ulm, Germany
| | - Chiara Verpelli
- Institute of Neuroscience, National Science Council, Milan, Italy
| | | | - Tobias M Boeckers
- Institute of Anatomy and Cell Biology, Ulm University, Ulm, Germany.
- German Center for Neurodegenerative Diseases (DZNE), Ulm, Germany.
- Department of Anatomy and Cell Biology, Ulm University, Albert-Einstein Allee 11, 89081, Ulm, Germany.
| | - Francesco Roselli
- Department of Neurology, Ulm University, Ulm, Germany.
- German Center for Neurodegenerative Diseases (DZNE), Ulm, Germany.
- Center for Biomedical Research (ZBF), Helmholtzstraße 8/2, 89081, Ulm, Germany.
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Subunit-dependent interaction of propoxazepam and its metabolite with the -aminobuturic acid type A receptor. EUREKA: HEALTH SCIENCES 2022. [DOI: 10.21303/2504-5679.2022.002649] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Benzodiazepines (BDZ) are widely used in clinics in the treatment of psychiatric disorders, and their main action is considered to be determined by more selective binding with α1, α2, α3 or α5 subunits of GABA receptor.
The aim of this work was studying of the molecular mechanism of action of new analgesic – propoxazepam and its metabolite (3-hydroxypropoxazepam) on α1, α2, α3, α4 or α5 subunits containing GABAA channels.
Materials and methods GABA ha1b3g2, ha2b3g2, ha3b3g2, ha4b3g2 and ha5b3g2 ionotropic GABAARs expressed in HEK293 were used on the automated SP384PE Patch Clamp system. In addition, Propoxazepam, 3-hydroxypropoxazepam, diazepam (positive allosteric modulator) and GABA (positive control) were administered at concentrations 0.001–300 nM to determine the EC50 and Emax for corresponding substances.
Results The α subunit plays a significantl role in determining the receptor’s affinity for propoxazepam and 3-hydroxypropoxazepam. The rank order of decreasing EC50 are α1 = α5> α2 > α3 > α4 (propoxazepam) and α1> α2> α5 > α3 > α4 (3-hydroxypropoxazepam), and for Emax α3 > α2 >α5 > α1 > α4 (propoxazepam), α3 > α1 > α2> α5 > α4 (3-hydroxypropoxazepam).
The data, transformed to Emax/EC50, show that propoxazepam exhibits tenfold (compared to diazepam) activity (taking into account the magnitude of the maximum effect) to the α3 subunit, which distinguishes it from 3-hydroxypropoxazepam.
Conclusion Due to the determined selectivity of propoxazepam for binding with different α subunit-containing GABAA-receptors (mostly α3 and α2 types), it has the potential to provide analgesia with less sedation than non-selective BDZ.
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Hasriadi, Dasuni Wasana PW, Suwattananuruk P, Thompho S, Thitikornpong W, Vajragupta O, Rojsitthisak P, Towiwat P. Curcumin Diethyl γ-Aminobutyrate, a Prodrug of Curcumin, for Enhanced Treatment of Inflammatory Pain. ACS Pharmacol Transl Sci 2022; 5:774-790. [PMID: 36110378 PMCID: PMC9469498 DOI: 10.1021/acsptsci.2c00062] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Indexed: 11/30/2022]
Abstract
Curcumin is a naturally occurring polyphenol compound with potential analgesic effects. It has been shown to improve pain-like behaviors in numerous models of pain. Despite its potential, curcumin exhibits poor physicochemical and pharmacokinetic properties, which hinder its oral therapeutic efficacy. Curcumin diethyl γ-aminobutyrate (CUR-2GE), a carbamate prodrug of curcumin, was designed to overcome these limitations and demonstrated greater anti-neuroinflammatory effects compared to curcumin in vitro. Thus, this study evaluated the effect of CUR-2GE and its parent compound on pain-like behaviors in carrageenan- and LPS-induced mouse models. The possible side effects of CUR-2GE were also assessed by exploring its effects on motor coordination and spontaneous locomotor activity after acute and chronic treatments. The results showed that CUR-2GE improved mechanical and thermal hyperalgesia and locomotor activity to a greater extent than curcumin in carrageenan-induced mice. These results are in line with the ability of CUR-2GE to suppress peripheral inflammation in the paw tissue of carrageenan-induced mice, indicated by a significant decrease in TNF-α and IL-6 expression levels. Similarly, in LPS-induced mice, CUR-2GE improved sickness and pain-like behaviors (exploratory behaviors and long-term locomotor activity) to a greater extent than curcumin. Furthermore, CUR-2GE significantly reduced the level of proinflammatory cytokines in both the plasma and spinal cord tissue of LPS-induced mice, exhibiting significantly higher inhibition than curcumin. Moreover, the motor coordination, and locomotive behaviors of mice were not affected by both acute and chronic administration of CUR-2GE, indicating no potential CNS side effects. Thus, CUR-2GE demonstrated enhanced therapeutic efficacy in mouse models of inflammatory pain without any possible CNS side effects, suggesting its potential to be developed as an analgesic agent against inflammatory pain.
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Affiliation(s)
- Hasriadi
- Center of Excellence in Natural Products for Ageing and Chronic Diseases, Chulalongkorn University, Bangkok 10330, Thailand
- Department of Pharmacology and Physiology, Faculty of Pharmaceutical Sciences, Chulalongkorn University, Bangkok 10330, Thailand
| | - Peththa Wadu Dasuni Wasana
- Department of Pharmacology and Physiology, Faculty of Pharmaceutical Sciences, Chulalongkorn University, Bangkok 10330, Thailand
- Pharmaceutical Sciences and Technology Program, Faculty of Pharmaceutical Sciences, Chulalongkorn University, Bangkok 10330, Thailand
| | - Piyapan Suwattananuruk
- Pharmaceutical Sciences and Technology Program, Faculty of Pharmaceutical Sciences, Chulalongkorn University, Bangkok 10330, Thailand
| | - Somphob Thompho
- Pharmaceutical Research Instrument Center, Faculty of Pharmaceutical Sciences, Chulalongkorn University, Bangkok 10330, Thailand
| | - Worathat Thitikornpong
- Center of Excellence in Natural Products for Ageing and Chronic Diseases, Chulalongkorn University, Bangkok 10330, Thailand
- Department of Food and Pharmaceutical Chemistry, Faculty of Pharmaceutical Sciences, Chulalongkorn University, Bangkok 10330, Thailand
| | - Opa Vajragupta
- Center of Excellence in Natural Products for Ageing and Chronic Diseases, Chulalongkorn University, Bangkok 10330, Thailand
- Molecular Probes for Imaging Research Network Faculty of Pharmaceutical Sciences, Chulalongkorn University, Bangkok 10330, Thailand
| | - Pornchai Rojsitthisak
- Center of Excellence in Natural Products for Ageing and Chronic Diseases, Chulalongkorn University, Bangkok 10330, Thailand
- Department of Food and Pharmaceutical Chemistry, Faculty of Pharmaceutical Sciences, Chulalongkorn University, Bangkok 10330, Thailand
| | - Pasarapa Towiwat
- Center of Excellence in Natural Products for Ageing and Chronic Diseases, Chulalongkorn University, Bangkok 10330, Thailand
- Department of Pharmacology and Physiology, Faculty of Pharmaceutical Sciences, Chulalongkorn University, Bangkok 10330, Thailand
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Cao T, Chen H, Huang W, Xu S, Liu P, Zou W, Pang M, Xu Y, Bai X, Liu B, Rong L, Cui ZK, Li M. hUC-MSC-mediated recovery of subacute spinal cord injury through enhancing the pivotal subunits β3 and γ2 of the GABA A receptor. Theranostics 2022; 12:3057-3078. [PMID: 35547766 PMCID: PMC9065192 DOI: 10.7150/thno.72015] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Accepted: 03/12/2022] [Indexed: 12/19/2022] Open
Abstract
Rationale: Spinal cord injury (SCI) remains an incurable neurological disorder leading to permanent and profound neurologic deficits and disabilities. Human umbilical cord-derived mesenchymal stem cells (hUC-MSCs) are particularly appealing in SCI treatment to curtail damage, restore homeostasis and possible neural relay. However, the detailed mechanisms underlying hUC-MSC-mediated functional recovery of SCI have not been fully elucidated. The purpose of our current study is to identify novel therapeutic targets and depict the molecular mechanisms underlying the hUC-MSC-mediated recovery of subacute SCI. Methods: Adult female rats suffering from subacute incomplete thoracic SCI were treated with intrathecal transplantation of hUC-MSCs. The beneficial effects of hUC-MSCs on SCI repair were evaluated by a series of behavioral analyses, motor evoked potentials (MEPs) recording of hindlimb and immunohistochemistry. We carried out extensive transcriptome comparative analyses of spinal cord tissues at the lesion site from the subacute phase of SCI (sub-SCI) either treated without (+PBS) or with hUC-MSCs (+MSC) at 0 (sub-SCI), 1, 2, and 4 weeks post-transplantation (wpt), as well as normal spinal cord segments of intact/sham rats (Intact). Adeno-associated virus (AAV)-mediated neuron-specific expression system was employed to functionally screen specific γ-aminobutyric acid type A receptor (GABAAR) subunits promoting the functional recovery of SCI in vivo. The mature cortical axon scrape assay and transplantation of genetically modified MSCs with either overexpression or knockdown of brain-derived neurotrophic factor (BDNF) were employed to demonstrate that hUC-MSCs ameliorated the reduction of GABAAR subunits in the injured spinal cord via BDNF secretion in vitro and in vivo, respectively. Results: Comparative transcriptome analysis revealed the GABAergic synapse pathway is significantly enriched as a main target of hUC-MSC-activated genes in the injured spinal cord. Functional screening of the primary GABAAR subunits uncovered that Gabrb3 and Garbg2 harbored the motor and electrophysiological recovery-promoting competence. Moreover, targeting either of the two pivotal subunits β3 or γ2 in combination with/without the K+/Cl- cotransporter 2 (KCC2) reinforced the therapeutic effects. Mechanistically, BDNF secreted by hUC-MSCs contributed to the upregulation of GABAAR subunits (β3 & γ2) and KCC2 in the injured neurons. Conclusions: Our study identifies a novel mode for hUC-MSC-mediated locomotor recovery of SCI through synergistic upregulation of GABAAR β3 and γ2 along with KCC2 by BDNF secretion, indicating the significance of restoring the excitation/inhibition balance in the injured neurons for the reestablishment of neuronal circuits. This study also provides a potential combinatorial approach by targeting the pivotal subunit β3 or γ2 and KCC2, opening up possibilities for efficacious drug design.
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Affiliation(s)
- Tingting Cao
- Department of Cell Biology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, 510515, China
| | - Huan Chen
- Department of Cell Biology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, 510515, China
| | - Weiping Huang
- Department of Cell Biology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, 510515, China
| | - Sisi Xu
- Department of Cell Biology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, 510515, China
| | - Peilin Liu
- Department of Cell Biology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, 510515, China
| | - Weiwei Zou
- Department of Cell Biology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, 510515, China
| | - Mao Pang
- Department of Spine Surgery, The Third Affiliated Hospital of Sun Yat-sen University, Guangzhou, 510515, China.,Guangdong Provincial Center for Engineering and Technology Research of Minimally Invasive Spine Surgery, 510630, China.,Guangdong Provincial Center for Quality Control of Minimally Invasive Spine Surgery, 510630, China
| | - Ying Xu
- Department of Spine Surgery, The Third Affiliated Hospital of Sun Yat-sen University, Guangzhou, 510515, China.,Guangdong Provincial Center for Engineering and Technology Research of Minimally Invasive Spine Surgery, 510630, China.,Guangdong Provincial Center for Quality Control of Minimally Invasive Spine Surgery, 510630, China
| | - Xiaochun Bai
- Department of Cell Biology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, 510515, China
| | - Bin Liu
- Department of Spine Surgery, The Third Affiliated Hospital of Sun Yat-sen University, Guangzhou, 510515, China.,Guangdong Provincial Center for Engineering and Technology Research of Minimally Invasive Spine Surgery, 510630, China.,Guangdong Provincial Center for Quality Control of Minimally Invasive Spine Surgery, 510630, China
| | - Limin Rong
- Department of Spine Surgery, The Third Affiliated Hospital of Sun Yat-sen University, Guangzhou, 510515, China.,Guangdong Provincial Center for Engineering and Technology Research of Minimally Invasive Spine Surgery, 510630, China.,Guangdong Provincial Center for Quality Control of Minimally Invasive Spine Surgery, 510630, China
| | - Zhong-Kai Cui
- Department of Cell Biology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, 510515, China
| | - Mangmang Li
- Department of Cell Biology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, 510515, China
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6
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Jin S, Cinar R, Hu X, Lin Y, Luo G, Lovinger DM, Zhang Y, Zhang L. Spinal astrocyte aldehyde dehydrogenase-2 mediates ethanol metabolism and analgesia in mice. Br J Anaesth 2021; 127:296-309. [PMID: 33934892 PMCID: PMC8362281 DOI: 10.1016/j.bja.2021.02.035] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Revised: 02/10/2021] [Accepted: 02/25/2021] [Indexed: 01/14/2023] Open
Abstract
BACKGROUND Little is known about the targets in the CNS that mediate ethanol analgesia. This study explores the role of spinal astrocyte aldehyde dehydrogenase-2 (ALDH2), a key ethanol-metabolising enzyme, in the analgesic effects of ethanol in mice. METHODS Astrocyte and hepatocyte ALHD2-deficient mice were generated and tested in acute and chronic pain models. Cell-type-specific distribution of ALDH2 was analysed by RNA in situ hybridisation in spinal slices from astrocytic ALDH2-deficient mice and their wild-type littermates. Spinal ethanol metabolites and γ-aminobutyric acid (GABA) content were measured using gas chromatography/mass spectrometry and liquid chromatography/mass spectrometry. RESULTS ALDH2 mRNA was expressed in both astrocytes and neurones in spinal cord slices. Astrocyte ALDH2-deficient mice had decreased expression of ALDH2 mRNA in astrocytes, but not in neurones. Astrocyte ALDH2 deficiency inhibited ethanol-derived acetate, but not acetaldehyde content in spinal cord tissues. Depletion of spinal astrocyte ALDH2 selectively inhibited ethanol-induced anti-nociceptive effect, but not the effect of ethanol, on motor function. Astrocyte ALDH2 deficiency abolished ethanol-induced GABA elevation. The ethanol metabolite acetate produced anti-nociception and increased GABA synthesis in a manner similar to ethanol. I.T. delivery of either GABAA or GABAB receptor antagonists prevented ethanol and acetate-induced analgesia. CONCLUSIONS These findings provide evidence that ALDH2 in spinal astrocytes mediates spinal ethanol metabolism and ethanol-induced analgesic effects by promoting GABA synthesis and GABAergic transmission in spinal cord.
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Affiliation(s)
- Shiyun Jin
- Department of Anesthesiology, Second Affiliated Hospital of Anhui Medical University, Hefei, China; Laboratory for Integrative Neuroscience, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD, USA
| | - Resat Cinar
- Laboratory for Metabolic Diseases, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD, USA
| | - Xudong Hu
- Department of Anesthesiology, Second Affiliated Hospital of Anhui Medical University, Hefei, China
| | - Yuhong Lin
- Laboratory for Liver Diseases, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD, USA
| | - Guoxiang Luo
- Laboratory for Integrative Neuroscience, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD, USA
| | - David M Lovinger
- Laboratory for Integrative Neuroscience, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD, USA
| | - Ye Zhang
- Department of Anesthesiology, Second Affiliated Hospital of Anhui Medical University, Hefei, China.
| | - Li Zhang
- Laboratory for Integrative Neuroscience, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD, USA.
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Obeng S, Hiranita T, León F, McMahon LR, McCurdy CR. Novel Approaches, Drug Candidates, and Targets in Pain Drug Discovery. J Med Chem 2021; 64:6523-6548. [PMID: 33956427 DOI: 10.1021/acs.jmedchem.1c00028] [Citation(s) in RCA: 40] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Because of the problems associated with opioids, drug discovery efforts have been employed to develop opioids with reduced side effects using approaches such as biased opioid agonism, multifunctional opioids, and allosteric modulation of opioid receptors. Receptor targets such as adrenergic, cannabinoid, P2X3 and P2X7, NMDA, serotonin, and sigma, as well as ion channels like the voltage-gated sodium channels Nav1.7 and Nav1.8 have been targeted to develop novel analgesics. Several enzymes, such as soluble epoxide hydrolase, sepiapterin reductase, and MAGL/FAAH, have also been targeted to develop novel analgesics. In this review, old and recent targets involved in pain signaling and compounds acting at these targets are summarized. In addition, strategies employed to reduce side effects, increase potency, and efficacy of opioids are also elaborated. This review should aid in propelling drug discovery efforts to discover novel analgesics.
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Affiliation(s)
- Samuel Obeng
- Department of Medicinal Chemistry, College of Pharmacy, University of Florida, Gainesville, Florida 32610, United States.,Department Pharmacodynamics, College of Pharmacy, University of Florida, Gainesville, Florida 32610, United States
| | - Takato Hiranita
- Department Pharmacodynamics, College of Pharmacy, University of Florida, Gainesville, Florida 32610, United States
| | - Francisco León
- Department of Drug Discovery and Biomedical Sciences, College of Pharmacy, University of South Carolina, Columbia 29208, United States
| | - Lance R McMahon
- Department Pharmacodynamics, College of Pharmacy, University of Florida, Gainesville, Florida 32610, United States
| | - Christopher R McCurdy
- Department of Medicinal Chemistry, College of Pharmacy, University of Florida, Gainesville, Florida 32610, United States.,Translational Drug Development Core, Clinical and Translational Sciences Institute, University of Florida, Gainesville, Florida 32610, United States
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Neumann E, Küpfer L, Zeilhofer HU. The α2/α3GABAA receptor modulator TPA023B alleviates not only the sensory but also the tonic affective component of chronic pain in mice. Pain 2021; 162:421-431. [PMID: 32773599 PMCID: PMC7808355 DOI: 10.1097/j.pain.0000000000002030] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Revised: 07/20/2020] [Accepted: 07/27/2020] [Indexed: 12/11/2022]
Abstract
ABSTRACT Diminished synaptic inhibition in the spinal dorsal horn is a major contributor to pathological pain syndromes of neuropathic or inflammatory origin. Drugs that enhance the activity of dorsal horn α2/α3GABAARs normalize exaggerated nociceptive responses in rodents with neuropathic nerve lesions or peripheral inflammation but lack most of the typical side effects of less specific GABAergic drugs. It is however still unknown whether such drugs also reduce the clinically more relevant conscious perception of pain. Here, we investigated the effects of the α2/α3GABAAR subtype-selective modulator TPA023B on the tonic aversive component of pain in mice with peripheral inflammation or neuropathy. In neuropathic mice with a chronic constriction injury of the sciatic nerve, TPA023B not only reversed hyperalgesia to tactile and heat stimuli but also was highly effective in the conditioned place preference test. In the formalin test, TPA023B not only reduced licking of the injected paw but also reversed facial pain expression scores in the mouse grimace scale assay. Taken together, our results demonstrate that α2/α3GABAA receptor subtype-selective modulators not only reduce nociceptive withdrawal responses but also alleviate the tonic aversive components of chronic pain.
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Affiliation(s)
- Elena Neumann
- Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland
| | - Laura Küpfer
- Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland
| | - Hanns Ulrich Zeilhofer
- Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland
- Institute of Pharmaceutical Sciences, ETH Zurich, Zurich, Switzerland
- Drug Discovery Network Zurich (DDNZ), University of Zurich and ETH Zurich, Zurich, Switzerland
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9
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Presynaptic Inhibition of Pain and Touch in the Spinal Cord: From Receptors to Circuits. Int J Mol Sci 2021; 22:ijms22010414. [PMID: 33401784 PMCID: PMC7795800 DOI: 10.3390/ijms22010414] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Revised: 12/28/2020] [Accepted: 12/30/2020] [Indexed: 02/07/2023] Open
Abstract
Sensory primary afferent fibers, conveying touch, pain, itch, and proprioception, synapse onto spinal cord dorsal horn neurons. Primary afferent central terminals express a wide variety of receptors that modulate glutamate and peptide release. Regulation of the amount and timing of neurotransmitter release critically affects the integration of postsynaptic responses and the coding of sensory information. The role of GABA (γ-aminobutyric acid) receptors expressed on afferent central terminals is particularly important in sensory processing, both in physiological conditions and in sensitized states induced by chronic pain. During the last decade, techniques of opto- and chemogenetic stimulation and neuronal selective labeling have provided interesting insights on this topic. This review focused on the recent advances about the modulatory effects of presynaptic GABAergic receptors in spinal cord dorsal horn and the neural circuits involved in these mechanisms.
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